BEGIKNERS'
B O XAN Y
L-H-BAILEY
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Albert K. Mann Library
COKNELL UnIVEFLSITY
a Cornell University
^ Library
The original of tliis book is in
tine Cornell University Library.
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BEGINNERS' BOTANY
THE MACMILLAN COMPANY
NEW YORK • BOSTON • CHICAGO
ATLANTA • SAN FKANCISCO
MACMILLAN & CO., Limited
LONDON • BOMBAY ■ CALCUTTA
MELBOURNE
THE MACMILLAN CO. OF CANADA, Ltd.
TORONTO
BOUQUET OF BEARDED WHEAT
BEGINNERS' BOTANY
BY
L. H. BAILEY
Wefa gotk
THE MACMILLAN COMPANY
1909
Ail rights reserve4
Copyright, 1908, 1909,
Bv THE MACMILLAN COMPANY.
Set up and electrotyped. Published February, igog.
Nottooob ^ress
J. 9. Cushiag Co. — Berwick & Smith Co.
J^orwood, Mass., U.S.A.
PREFACE
In all teaching of plants and animals to beginners, the
plants themselves and the animals themselves should be
made the theme, rather than any amount of definitions and
of mere study in books. The book will be very useful in
guiding the way, in arranging the subjects systematically,
and in explaining obscure points ; but if the pupil does not
know the living and growing plants when he has completed
his course in botany, he has not acquired very much that
is worth the while.
It is well to acquaint the beginner at first with the main
features of the entire plant rather than with details of its
parts. He should at once form a mental picture of what
the plant is, and what are some of its broader adaptations
to the life that it leads. In this book, the pupil starts with
the entire branch or the entire plant. It is sometimes said
that the pupil cannot grasp the idea of struggle for exist-
ence until he knows the names and uses of the different
parts of the plant. This is an error, although well estab-
lished in present-day methods of teaching.
Another very important consideration is to adapt the
statement of any fact to the understanding of a beginner.
It is easy, for example, to fall into technicalities when dis-
cussing osmosis ; but the minute explanations would mean
nothing to the beginner and their use would tend to con-
fuse the picture which it is necessary to leave in the pupil's
mind. Even the use of technical forms of expression would
probably not go far enough to satisfy the trained physicist.
VI PREFACE
It is impossible ever to state the last thing about any
proposition. All knowledge is relative. What is very
elementary to one mind may be very technical and ad-
vanced to another. It is neither necessary nor desirable
to safeguard statements to the beginner by such qualifica-
tions as will make them satisfactory to the critical expert
in science. The teacher must understand that while
accuracy is always essential, the degree of statement is
equally important when teaching beginners.
The value of biology study lies in the work with the
actual objects. It is not possible to provide specimens for
every point in the work, nor is it always desirable to do so ;
for the beginning pupil may not be able to interest himself
in the objects, and he may become immersed in details
before he has arrived at any general view or reason of the
subject. Great care must be exercised that the pupil is
not swamped. Mere book work or memory stuffing is
useless, and it may dwarf or divert the sympathies of
active young minds.
The present tendency in secondary education is away
from the formal technical completion of separate subjects
and toward the developing of a workable training in the
activities that relate the pupil to his own life. In the
natural science field, the tendency is to attach less im-
portance to botany and zoology and physiology as such,
and to lay greater stress on the processes and adaptations
of life as expressed in plants and animals and men. This
tendency is a revolt against the laboratory method and
research method of the college as it has been impressed
into the common schools, for it is not uncommon for the
pupil to study botany without really knowing plants, or
physiology without knowing himself. Education that is
not applicable, that does not put the pupil into touch with
PREFACE vii
the living knowledge and the affairs of his time, may be
of less educative value than the learning of a trade in a
shop. We are beginning to learn that the ideals and the
abilities should be developed out of the common surround-
ings and affairs of life rather than imposed on the pupil
as a matter of abstract, unrelated theory. '
It is much better for the beginning pupil to acquire a
real conception of a few central principles and points of
view respecting common forms that will enable him to tie
his knowledge together and organize it and apply it, than
to familiarize himself with any number of mere facts about
the lower forms of life which, at the best, he can know
only indirectly and remotely. If the pupil wishes to go
farther in later years, he may then take up special groups
and phases.
CONTENTS
CHAPTER
I. No Two Plants or Parts are Alike . . . i
11. The Struggle to Live 4
III. Sqrvival of the Fit 7
IV. Plant Societies g
V. The Plant Body 15
VI. Seeds and Germination 20
VII. The Root — The Forms of Roots .... 32
VIII. The Root — Function and Structure . . 38
IX. The Stem — Kinds and Forms — Pruning . 49
X. The Stem — Its General Structure ... 59
XI. Leaves — Form and Position 73
XII. Leaves — Structure and Anatomy ... 86
XIII. Leaves — Function or Work 92
XIV. Dependent Plants 106
XV. Winter and Dormant Buds 11 1
XVI. Bud Propagation 121
XVII. How Plants Climb 129
XVIII. The Flower — Its Parts and Forms . . -133
XIX. The Flower — Fertilization and Pollination . 144
XX. Flower-clusters 15S
XXI. Fruits 163
XXII. Dispersal of Seeds 172
XXIII. Phenogams and Cryptogams 176
XXIV. Studies in Cryptogams 182
Index 205
BEGINNERS' BOTANY
CHAPTER I
NO TWO PLANTS OR PARTS ARE ALIKE
No Two Branches are Alike.
(Hemlock.)
If one compares any two plants of
the same kind ever so closely, it will be
found that they differ from each other. The
difference is apparent in size, form, color, mode
of branching, number of leaves, number of flowers, vigor,
season of maturity, and the like ; or, in other words, all
plants and animals vary from an assumed or standard type.
If one compares any two branches or twigs on a tree, it
will be found that they differ in size, age, form, vigor, and
in other ways (Fig. i).
If one compares any two leaves, it will be found that
they are unlike in size, shape, color, veining, hairiness,
markings, cut of the margins, or other small features. In
some cases (as in Fig. 2) the differences are so great as to
be readily seen in a small black-and-white drawing.
BEGINNERS' BOTANY
If the pupil extends his observation to animals, he
will still find the same truth ; for probably no two living
objects are exact duplicates. If any person finds two objects
that he thinks to be exactly aHke, let him set to work to
Fig. 2. — No Two Leaves are Alike.
discover the differences, remembering that nothing in
nature is so small or apparently trivial as to be overlooked.
Variation, or differences between organs and also be-
tween organisms, is one of the most significant facts in
nature.
Suggestions. — The first fact that the pupil should acquire
about plants is that no two are alike. The way to apprehend this
great fact is to see a plant accurately and then to compare it with
NO TWO PLANTS OR PARTS ARE ALIICE 3
another plant of the same species or kind. In order to direct and
concentrate the observation, it is well to set a certain number of
attributes or marks or qualities to be looked for. 1. Suppose
any two or more plants of corn are compared in the following
points, the pupil endeavoring to determine whether the parts
exactly agree. See that the observation is close and accurate.
Allow no guesswork. Instruct the pupil to measure the parts
when size is involved :
(i) Height of the plant.
(2) Does it branch ? How many secondary stems or " suck-
ers" from one root?
(3) Shade or color.
(4) How many leaves ?
(5) Arrangement of leaves on stem.
(6) Measure length and breadth of six main leaves.
(7) Number and position of ears ; color of silks.
(8) Size of tassel, and number and size of its branches.
(9) Stage of maturity or ripeness of plant.
(10) Has the plant grown symmetrically, or has it been
crowded by other plants or been obliged to struggle for hght
or room ?
(t i) Note all unusual or interesting marks or features.
(12) Always make note of comparative vigor of the plants.
Note to Teacher. — The teacher should always insist on per-
sonal work by the pupil. Every pupil should handle and study
the object by himself. Books and pictures are merely guides and
helps. So far as possible, study the plant or animal jtist where it
grows naturally.
Notebooks. — Insist that the pupils make full notes and preserve
these notes in suitable books. Note-taking is a powerful aid in
organizing the mental processes, and in insuring accuracy of obser-
vation and record. The pupil should draw what he sees, even
though he is not expert with the pencil. The drawing should not
be made for looks, but to aid the pupil in his orderly study of the
object; it should be a means of self-expression.
Laboratory. — Every school, however small, should have a
laboratory or work-room. This work-room may be nothing more
than a table at one side of the room where the light is good.
Here the specimens may be ranged and studied. Often an
aquarium and terrarium may be added. A cabinet or set of
shelves should be provided for a museum and collection.
The laboratory may be in part out of doors, as a school garden ;
or the garden may be at the pupil's home, and yet be under the
general direction of the teacher.
CHAPTER II
THE STRUGGLE TO LIVE
Every plant and animal is exposed to unfavorable con-
ditions: It is obliged to contend with these conditions in
order to live.
No two plants or parts of plants are identically exposed
to the conditions in which they live. The large branches
Fig. 3. — A Battle for Life.
in Fig. I probably had more room and a better exposure
to light than the smaller ones. Probably no two of the
leaves in Fig. 2 are equally exposed to light, or enjoy
identical advantages in relation to the food that they re-
ceive from the tree.
Examine any tree to determine under what advantages
or disadvantages any of the limbs may live. Examine
similarly the different plants in a garden row (Fig. 3); or
the different bushes in a thicket ; or the different trees in
a wood,
4
THE STRUGGLE TO LIVE
5
The plant meets its conditions by succumbing to them
(that is, by dying), or by adapting itself to them.
The tree meets the cold by ceasing its active growth,
hardening its tissues, dropping its leaves. Many her-
baceous or soft-stemmed plants meet the cold by dying
to the ground and withdrawing all life into the root parts.
Some plants meet the cold by dying outright and provid-
ing abundance of seeds to perpetuate the kind next season.
Fig. 4. — The Reach for Light of a Tree on the Edge of a Wood.
Plants adapt themselves to light by growing toward it
(Fig. 4); or by hanging their leaves in such position that
they catch the light ; or, in less sunny places, by expand-
ing their leaf surface, or by greatly lengthening their
stems so as to overtop their fellows, as do trees and vines.
The adaptations of plants will afford a fertile field of
study as -we proceed.
6 BEGINNERS' BOTANY
Struggle for existence and adaptation to conditions are
among the most significant facts in nature.
The sum of all the conditions in which a plant or an ani-
mal is placed is called its environment, that is, its surround-
ings. The environment comprises the conditions of climate,
soil, moisture, exposure to light, relation to food supply,
contention with other plants or animals. TJie organism
adapts itself to its environment, or else it zveakens or dies.
Every weak branch or plant has undergone some hardship
that it was not wholly able to withstand.
Suggestions. — The pupil should study any plant, or branch of
a plant, with reference to the position or condition under which it
grows, and compare one plant or branch with another. With
animals, it is common knowledge that every animal is alert to
avoid or to escape danger, or to protect itself. 2. It is well to
begin with a branch of a tree, as in Fig. i. Note that no two
parts are alike (Chap. I). Note that some are large and strong
and that these stand farthest towards light and room. Some are
very small and weak, barely able to live under the competition.
Some have died. The pupil can easily determine which ones of
the dead branches perished first. He should take note of the
position or place of the branch on the tree, and determine whether
the greater part of the dead twigs are toward the center of the
tree top or toward the outside of it. Determine whether acci-
dent has overtaken any of the parts. 3. Let the pupil examine
the top of any thick old apple tree, to see whether there is any
struggle for existence and whether any limbs have perished. 4. If
the pupil has access to a forest, let him determine why there are
no branches on the trunks of the old trees. Examine a tree of
the same kind growing in an open field. 5. A row of lettuce
or other plants sown thick will soon show the competition between
plants. Any fence row or weedy place will also show it. Why
does the farmer destroy the weeds among the corn or potatoes?
How does the florist reduce competition to its lowest terms?
what is the result ?
CHAPTER III
THE SURVIVAL OF THE FIT
The plants that most perfectly meet their conditions are
able to persist. They perpetuate themselves. Their off-
spring are likely to inherit some of the attributes that
enabled them successfully to meet the battle of life. The
fit (those best adapted to their conditions) tend to survive.
Adaptation to conditions depends on the fact of varia-
tion; that is, if plants were perfectly rigid or invariable
(all exactly alike) they could not meet new conditions.
Conditions are necessarily new for every organism. It is
impossible to picture a perfectly inflexible and stable succes-
sion of plants or animals.
Breeding. — Man is able to modify plants and animals.
All our common domestic animals are very unhke their
original ancestors. So all our common and long-culti-
vated plants have varied
from their ancestors. Even
in some plants that have
been in cultivation less than
a century the change is
marked : compare the com-
mon black-cap raspberry
with its common wild ances-
tor, or the cultivated black-
berry with the wild form.
By choosing seeds from a plant that pleases him, the
breeder may be able, under given conditions, to produce
7
Fig. s. — Desirable and Undesirable
Types of Coiton Plants. Vv'hy?
BEGINNERS' BOTANY
numbers of plants with more
or less of the desired quali-
ties ; from the best of these,
he may again choose ; and so
on until the race becomes
greatly improved (Figs. 5, 6,
7). This process of continu-
ously choosing the most suita-
ble plants is known as selec-
tion. A some-
what similar
process pro-
ceeds in wild
nature, and it
is then known
as natural se-
lection.
Fig. 6. — Flax Breeding.
^ is a plant grown for seed production
Bt for fiber production. Why ?
Suggestions.
— 6. Every pu-
pil should un-
dertake at least
one simple ex-
periment in se-
lection of seed. He may select kernels from the
best plant of corn in the field, and also from the
poorest plant, — having reference not so much to
mere incidental size and vigor of the plants that
may be due to accidental conditions in the fielil,
as to the apparently constitutional strength and
size, number of ears, size of ears, perfectness of
ears and kernels, habit of the plant as to sucker-
ing, and the like. The seeds may be saved and
sown the next year. Every crop can no doubt
be very greatly improved by a careful process
of selection extending over a series of years.
Crops are increased in yield or efficiency in three
ways : better general care ; enriching the land
in which they grow ; attention to breeding.
Fig.
7. — Breed-
ing.
A, effect from breed-
ing from smallest
grains (after four
years), average
head; B, result
from breeding from
the plumpest and
heaviest grains
(after four years),
average head.
CHAPTER IV
PLANT SOCIETIES
In the long course of time in which plants have been
accommodating themselves to the varying conditions in
which they are obliged to grow, they have become adapted
to every different environment. Certain plants, therefore,
may live together or near each other, all enjoying the
same general conditions and surroundings. These aggre-
gations of plants that are adapted to similar general con-
ditions are known as plant societies.
Moisture and temperature are the leading factors in
determining plant societies. The great geographical
societies or aggregations of the plant world may con-
veniently be associated chiefly with the moisture supply,
as : wet-region societies, comprising aquatic and bog
vegetation (Fig. 8); arid-region societies, comprising desert
and most sand-region vegetation ; mid-region societies,
comprising the mixed vegetation in intermediate regions
(Fig. 9), this being the commonest type. Much of the
characteristic scenery of any place is due to its plant
societies. Arid-region plants usually have small and hard
leaves, apparently preventing too rapid loss of water.
Usually, also, they are characterized by stiff growth, hairy
covering, spines, or a much-contracted plant-body, and
often by large underground parts for the storage of water.
Plant societies may also be distinguished with reference
to latitude and temperature. There are tropical societies,
tem.perate-region societies, boreal or cold-region societies,
9
lO
BEGINNERS' BOTANY
With reference to altitude, societies might be classified
as lowland (which are chiefly wet-region), intermediate
(chiefly mid-region), siibalpine or mid-motintain (which are
chiefly boreal), alpine or higk-moimtain.
The above classifications have reference chiefly to great
geographical floras or societies. But there are societies
within societies. There are small societies coming within
the experience of every person who has ever seen plants
Fig. 8. — a Wet-region Society.
growing in natural conditions. There are roadside, fence-
row, lawn, thicket, pasture, dune, woods, cliff, barn-yard
societies. Every different place has its characteristic vegeta-
tion. Note the smaller societies in Figs. 8 and 9. In the
former is a water-lily society and a cat-tail society. In
the latter there are grass and bush and woods societies.
Some Details of Plant Societies. — Societies may be com-
posed of scattered and intermingled plants, or of dense
clumps or groups of plants. Dense clumps or groups are
usually made up of one kind of plant, and they are then
PLANT SOCIETIES
II
called colonies. Colonies of most plants are transient :
after a short time other plants gain a foothold amongst
them, and an intermingled society is the outcome. Marked
exceptions to this are grass colonies and forest colonies, in
which one kind of plant may hold its own for years and
centuries.
In a large newly cleared area, plants usually ^rj^ estab-
lish themselves in dense colonies. Note the great patches
Fig. 9. — a Mid-region Society.
of nettles, jewel-weeds, smart-weeds, clot-burs, fire-weeds
in recently cleared but neglected swales, also the fire-weeds
in recently burned areas, the rank weeds in the neglected
garden, and the ragweeds and May-weeds along the re-
cently worked highway. The competition amongst them-
selves and with their neighbors finally breaks up the
colonies, and a mixed and intermingled flora is generally
the resiclt.
In many parts of the world the general tendency of neg-
lected areas is to run into forest. All plants rush for the
12
BEGINNERS' BOTANY
cleared area. Here and there bushes gain a foothold.
Young trees come up ; in time these shade the bushes and
gain the mastery. Sometimes the area grows to poplars
or birches, and people wonder why the original forest trees
do not return ; but these forest trees may be growing unob-
served here and there in the tangle, and in the slow pro-
cesses of time the poplars perish — for they are short-lived
— and the original forest may be replaced. Whether one
kind of forest or another returns will depend partly on the
kinds that are most seedful in that vicinity and which,
therefore, have sown themselves most profusely. Much
depends, also, on the kind of undergrowth that first springs
up, for some young trees can endure more or less shade
than others.
Some plants associate. They grow together. This is
possible largely because they diverge or differ in charac-
ter. Plants asso-
ciate in two ways :
by growing side by
side ; by growing
above or bejteath.
In sparsely popu-
lated societies,
plants may grow
alongside each
other. In most
cases, however,
there is overgrowth
and undergrowth :
one kind grows beneath another. Plants that have be-
come adapted to shade are usually undergrowths. In a cat-
tail swamp, grasses and other narrow-leaved plants grow
in the bottom, but they are usually unseen by the casual
Fig. io. — Overgrowth and U.ndergrowth in
Three Series, — trees, bushes, grass.
PLANT SOCIETIES 1 3
observer. Note the undergrowth in woods or under trees
(Fig. 10). Observe that in pine and spruce forests there
is almost no undergrowth, partly because there is very little
light.
On the same area the societies may differ at different
times of the year. There are spring, summer, and fall soci-
eties. The knoll which is cool with grass and strawber-
ries in June may be aglow with goldenrod in September.
If the bank is examined in May, look for the young plants
that are to cover it in July and October ; if in Septem-
ber, find the dead stalks of the flora of May. What suc-
ceeds the skunk cabbage, hepaticas, trilliums, phlox, violets,
buttercups of spring .■" What precedes the wild sunflowers,
ragweed, asters, and goldenrod of fall .''
The Landscape. — To a large extent the color of the land-
scape is determined by the character of the plant societies.
Evergreen societies remain green, but the shade of green
varies from season to season ; it is bright and soft in
spring, becomes dull in midsummer and fall, and assumes
a dull yellow-green or a black-green in winter. Deciduous
societies vary remarkably in color — from the dull browns
and grays of winter to the brown greens and olive-greens
of spring, the staid greens of summer, and the brilliant
colors of autumn.
The autumn colors are due to intermingled shades of
green, yellow, and red. The coloration varies with the kind
of plant, the special location, and the season. Even in the
same species or kind, individual plants differ in color ; and
this individuality usually distinguishes the plant year by
year. That is, an oak which is maroon red this autumn is
likely to exhibit that range of color every year. The au-
tumn color is associated with the natural maturity and
death of the leaf, but it is most brilliant in long and open
14 BEGINNERS' BOTANY
falls — largely because the foliage ripens more gradually
and persists longer in such seasons. It is probable that
the autumn tints are of no utility to the plant. Autumn
colors are not caused by frost. Because of the long, dry
falls and the great variety of plants, the autumnal color of
the American landscape is phenomenal.
Ecology. — The study of the relationships of plants and
animals to each other and to seasons and environments is
known as ecology (still written cecology in the dictionaries).
It considers the habits, habitats, and modes of life of liv-
ing things — the places in which they grow, how they
migrate or are disseminated, means of collecting food,
their times and seasons of flowering, producing young,
and the like.
Suggestions. — One of the best of all subjects for school instruc-
tion in botany is the study of plant societies. It adds definiteness
and zest to excursions. 7. Let each excursion be confined to one
or two societies. Visit one day a swamp, another day a forest,
another a pasture or meadow, another a roadside, another a weedy
field, another a cliff or ravine. Visit shores whenever possible.
Each pupil should be assigned a bit of ground — say lo or 20 ft.
square — for special study. He should make a list showing (i)
how many kinds of plants it contains, (2) the relative abundance
of each. The lists secured in different regions should be com-
pared. It does not matter greatly if the pupil does not know all
the plants. He may count the kinds without knowing the names.
It is a good plan for the pupil to make a dried specimen of each
kind for reference. The pupil should endeavor to discover why
the plants grow as they do. Note what kinds of plants grow next
each other ; and which are undergrowth and which overgrowth ;
and which are erect and which wide-spreading. Challenge every
plant society.
CHAPTER V
THE PLANT BODY
The Parts of a Plant. — Our familiar plants are made up
of several distinct parts. The most prominent of these
parts are root, stem, leaf, flower, fruit, and seed. Familiar
plants differ wonderfully in size and shape, — from fragile
mushrooms, delicate waterweeds and pond-scums, to float-
ing leaves, soft grasses, coarse weeds, tall bushes, slender
climbers, gigantic trees, and hanging moss.
The Stem Part. — In most plants there is a main central
part or shaft on which the other or secondary parts are
borne. This main part is the plant axis. Above ground,
in most plants, the main plant axis bears the branches,
leaves, a.nA flowers ; below ground, it bears the roots.
The rigid part of the plant, which persists over winter
and which is left after leaves and flowers are fallen, is the
framework of the plant. The framework is composed of
both root and stem. When the plant is dead, the frame-
work remains for a time, but it slowly decays. The dry
winter stems of weeds are the framework, or skeleton of
the plant (Figs, ii and 12). The framework of trees is
the most conspicuous part of the plant.
The Root Part. — The root bears the stem at its apex,
but otherwise it normally bears only root-branches. The
stem, however, bears leaves, flowers, and fruits. Those
living surfaces of the plant which are most exposed to
light are green or highly colored. The root tends to grow
downward, but the stem tends to grow upward toward light
15
i6
BEGIAWERS' BOTANY
and air. The plant is anchored or fixed in the soil by the
roots. Plants have been called "earth parasites."
The Foliage Part. — The leaves precede the flowers in
point of time or life of the plant. Tlie flowers always
precede the fruits and seeds. Many plants die when the
seeds have matured. The whole mass of leaves of any
plant or any branch is
known as its foliage.
In some cases, as in
crocuses, the flowers
seem to precede the
leaves ; but the leaves
that made the food for
these flowers grew the
preceding year.
The Plant Generation.
— The course of a
plant's life, with all the
events through which
the plant naturally
passes, is known as
the plant's life-history.
The life-history em-
braces various stages,
or epochs, as dormant
ination, growth, flowering, fruiting. Some plants
run their course in a few weeks or months, and some live
for centuries.
The entire life-period of a plant is called a generation.
It is the whole period from birth to normal death, without
reference to the various stages or events through which it
passes.
A generation begins with the young seed, not with germi-
FiG. II. — Plant of a
Wild Sunflower.
seed, genu
Fig. 12. — Frame-
work OF Fig. II.
THE PLANT BODY If
nation. It ends with death — that is, when no life is left
in any part of the plant, and only the seed or spore
remains to perpetuate the kind. In a bulbous plant, as a
lily or an onion, the generation does not end until the bulb
dies, even though the top is dead.
When the generation is of only one season's duration,
the plant is said to be annual. When it is of two seasons,
it is biennial. Biennials usually bloom the second year.
When of three or more seasons, the plant is perennial.
Examples of annuals are pigweed, bean, pea, garden sun-
flower ; of biennials, evening primrose, mullein, teasel ; of
perennials, dock, most meadow grasses, cat-tail, and all
shrubs and trees.
Duration of the Plant Body. — Plant structures which
are more or less soft and which die at the close of the
season are said to be herbaceous, in contradistinction to
being ligneous or woody. A plant which is herbaceous to
the ground is called an herb ; but an herb may have a
woody or perennial root, in which case it is called an
herbaceous perennial. Annual plants are classed as herbs.
Examples of herbaceous perennials are buttercups, bleed-
ing heart, violet, water lily, Bermuda grass, horse-radish,
dock, dandelion, golden rod, asparagus, rhubarb, many
wild sunflowers (Figs, ii, 12).
Many herbaceous perennials have short generations.
They become weak with one or two seasons of flowering
and gradually die out. Thus, red clover usually begins to
fail after the second year. Gardeners know that the best
bloom of hollyhock, larkspur, pink, and many other plants,
is secured when the plants are only two or three years
old.
Herbaceous perennials which die away each season to
bulbs or tubers, are sometimes called pseud-annuals (that
I8 BEGINNERS' BOTANY
is, false annuals). Of such are lily, crocus, onion, potato,
bull nettle, and false indigo of the Southern states.
True annuals reach old age the first year. Plants which
are normally perennial may become annual in a shorter-
season climate by being killed by frost, rather than by dying
naturally at the end of a season of growth. They are cli-
matic annuals. Such plants are called plur-annuals in the
short-season region. Many tropical perennials are plur-
r*nrS,V
Fig. 13. — A Shrub or Bush. Dogwood osier.
annuals when grown in the north, but they are treated as
true annuals because they ripen sufficient of their crop the
same season in which the seeds are sown to make them
worth cultivating, as tomato, red pepper, castor bean,
cotton. Name several vegetables that are planted in
gardens with the expectation that they will bear till frost
comes.
Woody or ligneous plants are usually longer lived than
herbs. Those that remain low and produce several or
THE PLANT BODY
19
many similar shoots from the
base are called shrubs, as lilac,
rose, elder, osier (Fig. 13). Low
and thick shrubs are bushes.
Plants that produce one main
trunk and a more or less elevated
head are trees (Fig. 14). All
shrubs and trees are perennial.
Every plant makes an effort
to propagate, or to perpetuate its
kind ; and, as far as we can
see, this is the end for which
the plant itself lives. The seed
or spore is the final product of
the plant.
'it-riitx./.;--:
Fig. 14. -
- A Tree. The weeping
birch.
Suggestions. — 8. The teacher may assign each pupil to one
plant in the school yard, or field, or in a pot, and ask him to bring
out the points in the lesson. 9. The teacher may put on the
board the names of many common plants and ask the pupils to
classify into annuals, pseud-annuals, plur-annuals (or climatic
annuals), biennials, perennials, herbaceous perennials, ligneous
perennials, herbs, bushes, trees. Every plant grown on the farm
should be so classified : wheat, oats, corn, buckwheat, timothy,
strawberry, raspberry, currant, tobacco, alfalfa, flax, crimson clover,
hops, cowpea, field bean, sweet potato, peanut, radish, sugar-cane,
barle)', cabbage, and others. Name all the kinds of trees you
know.
CHAPTER VI
SEEDS AND GERMINATION
The seed contains a miniature plant, or embryo. The
embryo usually has three parts that have received
names : the stemlet, or caulicle ; the seed-leaf, or cotyledon
(usually I or 2); the bud, or plumule, lying between or
above the cotyledons. These parts are well
seen in the common bean (Fig. 15), particu-
larly when the seed has been soaked for a
few hours. One of the large cotyledons —
Fig. 15. — Parts . . u ir »£ <-t, i, • u t
OF THE Bean compnsmg half 01 the bean — is shown at
R, cotyledon; o, R. The cauliclc is at O. The plumule is
mule -'^'j^!' first showuat^. The cotylcdons are attached
""de- to the caulicle at F : this point may be taken
as the first node or joint.
The Number of Seed-leaves. — All plants having two
seed-leaves belong to the group called dicotyledons. Such
seeds in many cases split readily in halves, e.g. a bean.
Some plants have only one seed-leaf in a seed. They
form a group of plants called monocotyledons. Indian
corn is an example of a plant with only one seed-leaf :
a grain of corn does not split into halves as a bean does.
Seeds of the pine family contain more than two cotyledons,
but for our purposes they may be associated with the dicoty-
ledons, although really forming a different group.
These two groups — the dicotyledons and the mono-
cotyledons — represent two great natural divisions of the
vegetable kingdom. The dicotyledons contain the woody
SEEDS AND GERMINATION 21
bark-bearing trees and bushes (except conifers), and most
of the herbs of temperate climates except the grasses,
sedges, rushes, lily tribes, and orchids. The flower-parts
are usually in fives or multiples of five, the leaves mostly
netted-veined, the bark or rind distinct, and the stem often
bearing a pith at the center. The monocotyledons usually
have the flower-parts in threes or multiples of three, the
leaves long and parallel-veined, the bark not separable,
and the stem without a central pith.
Every seed is provided with food to support the germinat-
ing plant. Commonly this food is starch. The food may
be stored i?i the cotyledons, as in bean, pea, squash ; or out-
side the cotyledons, as in castor bean, pine, Indian corn.
When the food is outside or around the embryo, it is
usually called endosperin.
Seed-coats; Markings on Seed. — The embryo and en-
dosperm are inclosed within a covering made of two or
more layers and known as the seed-coats.
Over the point of the caulicle is a minute
hole or a thin place in the coats known as
the micropyle. This is the point at which fig.i6.— exter-
the pollen-tube entered the forming ovule "^^^ parts of
Bean.
and through which the caulicle breaks in
germination. The micropyle is shown at M in Fig. i6.
The scar where the seed broke from its funiculus (or stalk
that attached it to its pod) is named the hilum. It occu-
pies a third of the length of the bean in Fig. i6. The
hilum and micropyle are always present in seeds, but they
are not always close together. In many cases it is difficult
to identify the micropyle in the dormant seed, but its loca-
tion is at once shown by the protruding caulicle as germi-
nation begins. Opposite the micropyle in the bean (at the
other end of the hilum) is an elevation known as the raphe.
22 BEGINXERS' BOTANY
This is formed by a union of the funiculus, or seed-stalk,
with the seed-coats, and through it food was transferred
for the development of the seed, but it is now functionless.
Seeds differ wonderfully in size, shape, color, and other
characteristics. They also vary in longevity. These
characteristics are peculiar to the species or kind. Some
seeds maintain life only a few weeks or even days, whereas
others will " keep " for ten or twenty years. In special
cases, seeds have retained vitality longer than this limit,
but the stories that live seeds, several thousand years old,
have been taken from the wrappings of mummies are un-
founded.
Germination. — The embryo is not dead ; it is only dor-
mant. When supplied with moisture, warmth, and oxygen
(air), it awakes and grows : this groivth is germination.
The embryo lives for a time on the stored food, but gradu-
ally the plantlet secures a foothold in the soil and gathers
food for itself. When the plantlet is finally able to shift
for itself, gerniinatio7i is complete.
Early Stages of Seedling. — The germinating seed first
absorbs water, and swells. The starchy matters gradually
become soluble. The seed-coats are ruptured, the caulicle
and plumule emerge. During this process the seed
respires freely, throwing off carbon dioxid (COj).
The caulicle usually elongates, and from its lower end
roots are emitted. The elongating caulicle is known as
the hypocotyl (" below the cotyledons "). That is, the
hypocotyl is that part of the stem of the plantlet lying
between the roots and the cotyledon. The general direc-
tion of the young hypocotyl, or emerging caulicle, is down-
wards. As soon as roots form, it becomes fixed and its
subsequent growth tends to raise the cotyledons above the
ground, as in the bean. When cotyledons rise into the
SEEDS AND GERMINATION
23
Fig. 17. — Pea. Grotesque forms assumed
when the roots cannot gain entrance to
the soil.
air, germination is said to be epigeal (" above the earth ").
Bean and pumpkin are examples. When the hypocotyl
does not elongate greatly
and the cotyledons remain
under ground, the germi-
nation is hypogeal ("be-
neath the earth"). Pea
and scarlet runner bean
are examples (Fig. 48).
When the germinating
seed lies on a hard sur-
face, as on closely com-
pacted soil, the hypocotyl
and rootlets may not be able to secure a foothold and they
assume grotesque forms. (Fig. 17.) Try this with peas
and beans.
The first internode ("between nodes") above the coty-
ledons is the epicotyl. It elevates the plumule into the
air, and the plumule-leaves expand into the first true leaves
of the plant. These first true leaves, however, may be
very unlike the later leaves in shape.
Germination of Bean. — The common bean, as we have
seen (Fig. 15), has cotyledons that occupy all the space
inside the seed-coats. When the hy-
pocotyl, or elongated caulicle, emerges,
the plumule-leaves have begun to en-
large, and to unfold (Fig. 18). The
hypocotyl elongates rapidly. One end
of it is held by the roots.' The othei
is held by the seed-coats in the soil.
It therefore takes the form of a loop,
and the central part of the loop " comes up " first {a, Fig.
19). Presently the cotyledons come out of the seed-coats.
Fig. iS. — Cotyledons
OF Germinating
Bean spread apart
TO SHOW Elongat-
ing Caulicle and
Plumule.
24
BEGINNERS' BOTANY
and the plant straightens and the
cotyledons expand. These coty-
ledons, or " halves of the bean,"
persist for some time {h, Fig.
19). They often become green
and probably perform some
function of foliage. Because of
its large size, the Lima bean
shows all these parts well.
Germination of Castor Bean. —
In the castor bean the hilum
and micropyle are at the smaller end
(Fig. 20). The bean " comes up" with a
loop, which indicates that the hypocotyl
greatly elongates. On examining germi-
nating seed, however, it will be found
that the cotyledons are contained inside a fleshy body,
or sac {a, Fig. 21). This sac is the endosperm,
its inner surface the thin, veiny coty-
ledons are very closely pressed, ab-
FlG. 19.
-Gekmixation of
Bean.
Fig. 20. — Sprout,
ING OF Castor
Bean,
Against
Fig. 21. — Germina-
tion OF Castor Bean.
Fig. 22. — Castor
Bean.
Endosperm at a,n', coty-
ledons at b.
Fig. 23. — Germination
Complete in Castor
Bean.
Endosperm at a,
sorbing its substance (Fig. 22). The cotyledons increase
in size as they reach the air (Fig. 23), and become funp-
tional leaves.
SEEDS AND GERMINATION
25
Germination of Monocotyledons. — Thus far we have stud-
ied dicotyledonous seeds ; we may now consider the mono-
cotyledonous group. Soak kernels of corn. Note that
the micropyle and hilum are at the smaller end (Fig. 24).
Make a longitudinal section through the
narrow diameter; Fig. 25 shows it. The
Fig. 24. — Sprout-
ing Indian Corn.
Hilum at h ', micro-
pyle at d.
Fig. 25. — Kernel
OF Indian Corn.
Caulicle at 6; cotyle-
don at a; plumule
at p.
Fig. 26.— Indian
Corn.
Caulicle at c; roots emerging at
m; plumule at/.
single cotyledon is at a, the cauUcle at b, the plumule
at/. The cotyledon remains in the seed. The food is
stored both in the cotyledon and as endosperm, chiefly the
latter. The emerging shoot is the plumule, with a sheath-
ing leaf {p, Fig. 26). The root is emitted from the tip of.
the caulicle, c. The caulicle is held in a sheath
(formed mostly from the seed-coats), and some of
the roots escape through the upper end
of this sheath {m. Fig. 26). The
'x-^\T epicotyl elongates, particularly if
'^(. The true plumule-leaf is at o, but
other leaves grow from its sheath. In Fig. 28 the roots
are seen emerging from the two ends of the caulicle-
FiG. 27. — Indian Corn.
e, plumule; » to_/5, epicotyl.
26
BEGINNERS' BOTANY
sheath, c, m ; the epicotyl has grown to / ; the first plu-
mule-leaf is at 0.
In studying corn or other fruits or seeds, the pupil should
note how the seeds are arranged, as on the cob. Count the
rows on a corn cob. Odd or
even in number .'' Always the
same number '>. The silk is
the style : find where it was
attached to the kernel. Did
the ear have any coverings ?
Explain. Describe colors and
markings of kernels of corn ;
and of peas, beans, castor
bean.
Gymnosperms. — The seeds
in the pine cone, not being
inclosed in a seed-vessel,
readily fall out when the cone
dries and the scales separate.
Hence it is difficult to find
cones with seeds in them after
autumn has passed (Fig. 29).
The cedar is also a gymno-
sperm.
Remove a scale from a
pine cone and draw it and
the seeds as they lie in place
on the upper side of the scale.
Examine the seed, preferably with a magnifying glass. Is
there a hilum .' The micropyle is at the bottom or little
end of the seed. Toss a seed upward into the air. Why
does it fall so slowly .? Can you explain the peculiar whirl-
ing motion by the shape of the wing } Repeat the ej5-
FiG. 28. — Germination is Com
PLETE.
/, top of epicotyl: (5, plumule-leaf;
tn, roots; c, lower roots.
SEEDS AND GERMINATION
27
periment in the wind. Remove tiie
wing from a seed and toss it and an
uninjured seed into the air together.
What do you infer from these ex-
periments .''
Suggestions. — Few subjects con-
nected with the study of plant-life are so
useful in schoolroom demonstrations as
germination. The pupil should prepare
the soil, plant the seeds, water them, and
care for the plants. 10. Plant seeds in
pots or shallow boxes. The box should
not be very wide or long, and not over
four inches deep. Holes may be bored
in the bottom so it will not hold water.
Plant a number of squash, bean, corn,
pine, or other seeds about an inch deep
in damp sand or pine sawdust in this
box. The depth of planting should be
two to four times the diameter of the
seeds. Keep the sand or sawdust moist
but not wet. If the class is large, use
several boxes, that the supply of speci-
mens may be ample. Cigar boxes and
chalk boxes are excellent for individual
pupils. It is well to begin the planting
of seeds at least ten days in advance of
the lesson, and to make four or five differ-
ent plantings at intervals. A day or two
before the study is taken up, put seeds
to soak in moss or cloth. The pupil
then has a series from swollen seeds to
complete germination, and all the steps can be made out. Dry
seeds should be had for comparison. If there is no special room
for laboratory, nor duplicate apparatus for every pupil, each ex-
periment may be assigned to a committee of two pupils to watch
in the schoolroom. 11. Good seeds for study are those detailed
in the lesson, and buckwheat, pumpkin, cotton, morning glory,
radish, four o'clock, oats, wheat. It is best to use familiar seeds
of farm and garden. Make drawings and notes of all the events
in the germination. Note the effects of unusual conditions, as
planting too deep and too shallow and different sides up. For
hypogeal germination, use the garden pea, scarlet runner or Dutch
Fig. 29. — Cones of Hem-
lock (above), White
Pine, Pitch Pine.
28 BEGINNERS' BOTANY
case-knife bean, acorn, horse-chestnut. Squash seeds are excellent
for germination studies, because the cotyledons become green and
leafy and germination is rapid. Its germination, as also that of the
scarlet runner bean, is explained in " Lessons with Plants." Onion
is excellent, except that it germinates too slowly. In order to study
the root development of germinating plantlets, it is well to pro-
vide a deeper box with a glass side against which the seeds are
planted. 12. Observe the germination of any common seed
about the house premises. When elms, oaks, pines, or maples are
abundant, the germination of their seeds may be studied in lawns
and along fences. 13. When studying germination, the pupil
should note the differences in shape and size between cotyledons
and plumule-leaves, and between plumule-leaves and the normal
leaves (Fig. 30). Make drawings. 14. Make the tests described
in the introductory experi-
^---^J^i^ i^^\ y^ ments with bean, corn, the
* "**' '' ^feir''.K^^ castor bean, and other seed
i' y''::^K''\m^ ^°^ starch and proteids. Test
flour, oatmeal, rice, sunflower,
four o'clock, various nuts, and
any other seeds obtainable.
Record your results by ar-
FiG. 30. — MusKMELON SEEDLINGS, with ranging the seeds in three
the unlike seed-leaves and true leaves. classes, I. Much Starch (color
blackish or purple), 2. Little
Starch (pale blue or greenish), 3. No starch (brown or yellow).
15. Jiafe of growth of seedlitigs as affected by differences in tempera-
ture. Pack soft wet paper to the depth of an inch in the bottom
of four glass bottles or tumblers. Put ten soaked peas or beans into
each. Cover each securely and set them in places having different
temperatures that vary little. (A furnace room, a room with a
stove, a room without stove but reached by sunshine, an unheated
room not reached by the sun.) Take the temperatures occasion-
ally with a thermometer to find difference in temperature. The
tumblers in warm places should be covered very tightly to prevent
the germination from being retarded by drying out. Record the
number of seeds which sprout in each tumbler within i day ; 2 days ;
3 days ; 4 days, etc. 16. Is air necessary for the germination and
groivth of seedlings 1 Place damp blotting paper in the bottom of a
bottle and fill it three fourths full of soaked seeds, and close it
tightly with a rubber stopper or oiled cork. Prepare a " check
experiment" by having another bottle with all conditions the same
except that it is covered loosely that air may have access to it,
and set the bottles side by side (why keep the bottles together?).
Record results as in the preceding experiment. 17. What is the
SEEDS AND GERMINATION
29
nature of the gas given off by germinating seeds ? Fill a tin box or
large-necked bottle with dry beans or peas, then add water; note
how much they swell. Secure two fruit-jars. Fill one of them a
third full of beans and keep them moist. Allow the other to remain
empty. In a day or two insert a lighted splinter or taper into
each. In the empty jar the taper burns : it contains oxygen.
In the seed jar the taper goes out : the air has been replaced
by carbon dioxid. The air in the bottle may be tested for
carbon dioxid by removing some of it with a rubber bulb attached
to a glass tube (or a fountain-pen filler) and bubbling it through
limfe water. 18. Temperature. Usually there is a perceptible
rise in temperature in a mass of germinating seeds. This rise may
be tested with a thermometer. 19. Interior of seeds. Soak
seeds for twenty-four hours and remove the coat. Distinguish
the embryo from the endosperm. Test with iodine. 20. Of
what utility is the food in seeds? Soak some grains of corn
overnight and remove the endosperm, being careful not to
injure the fleshy cotyledon. Plant the incomplete and also some
complete grains in moist sawdust and measure their growth at
intervals. (Boiling the sawdust will destroy molds and bacteria
which might interfere with experiment.) Peas or beans may be
sprouted on damp blotting paper ; the cotyledons of one may be
removed, and this with a normal seed equally advanced in germi-
nation may be placed on a perforated cork floating in water in
a jar so that the roots extend into the water. Their growth
may be observed for several weeks. 21. Effect of darkness on
seeds and seedlings. A box may be placed mouth downward
over a smaller box in which seedlings are growing. The empty
box should rest on half-inch blocks to allow air to reach the
seedlings. Note any effects on the seedlings of this cutting off
of the light. Another box of seedlings, not so covered may
be used for a check. Lay a plank on green grass and after a
week note the change that takes place beneath it. 22. Seedling
of pine. Plant pine seeds. Notice how they emerge. Do the
cotyledons stay in the ground ? How many cotyledons have
they ? When do the cotyledons get free from the seed-coat ?
What is the last part of the cotyledon to become free ? Where is
the growing point or plumule ? How many leaves appear at
once ? Does the new pine cone grow on old wood or on wood
formed the same spring with the cone? Can you always find
partly grown cones on pine trees in winter? Are pine cones
when mature on two-year-old wood? How long do cones stay
on a tree after the seeds have fallen out ? What is the advantage
of the seeds falling before the cones? 23. Home experiments.
If desired, nearly all of the foregoing experiments may be
30
BEGINNERS' BOTANY
Fig. 31. — A Home-made
Seed-tester.
tried at home. The pupil can thus make the drawings for the
notebook at home. A daily record of measurements of the change
in size of the various parts of the seedling should also be made.
24. Seed-testing. — It is important that one know before planting
whether seeds are good, or able to grow. A simple seed-tester
may be made of two plates, one inverted over the other (Fig. 31).
The lower plate is nearly filled with clean
sand, which is covered with cheese cloth
or blotting paper on which the seeds are
placed. Canton flannel is sometimes
used in place of sand and blotting paper.
The seeds are then covered with another
blotter or piece of cloth, and water is
apphed until the sand and papers are
saturated. Cover with the second plate.
Set the plates where they will have about
the temperature that the given seeds
would require out of doors, or perhaps a
slightly higher temperature. Place 100 or more grains of clover,
corn, wheat, oats, rye, rice, buckwheat, or other seeds in the tester,
and keep record of the number that sprout. The result will give
a percentage measure of the ability of the seeds to grow. Note
whether all the seeds sprout with equal vigor and rapidity. Most
seeds will sprout in a week or less. Usually such a tester must
have fresh sand and paper after every test, for mold fungi are likely
to breed in it. If canton flannel is used, it may be boiled. If
possible, the seeds should not touch each other.
Note to Teacher. — With the study of germination, the pupil
wiU need to begin dissecting.
For dissecting, one needs a lens for the examination of the
smaller parts of plants and animals. It is best to have the lens
mounted on a frame, so that the pupil has both hands free for
pulling the part in pieces. An ordinary pocket lens may be
mounted on a wire in a block, as in Fig. A. A cork is slipped on
the top of the wire to avoid injury to the face. The pupil should
be provided with two dissecting needles (Fig. B), made by
securing an ordinary needle in a pencil-like stick. Another con-
venient arrangement is shown in Fig. C. A small tin dish is used
for the base. Into this a stiff" wire standard is soldered. The
dish is filled with solder, to make it heavy and firm. Into a cork
slipped on the standard, a cross wire is inserted, holding on the
end a Jeweler's glass. The lens can be moved up and down and
sidewise. This outfit can be made for about seventy-five cents.
Fig. D shows a convenient hand-rest or dissecting-stand to be
SEEDS AND GERMINATION
31
used under this lens. It may be 16 in. long, 4 in. high, and 4 or 5
in. broad.
Various kinds of dissecting microscopes are on the market, and
these are to be recommended when they can be afforded.
i5.— Dissecting Stand.
5. — Dis-
secting
Needle
% natural
size.
C. — Dissecting Glass.
^. — Improvised
Stand for Lens.
Instructions for the use of the compound microscope, with
which some schools may be equipped, cannot be given in a brief
space ; the technique requires careful training. Such microscopes
are not needed unless the pupil studies cells and tissues.
CHAPTER VII
THE ROOT — THE FORMS OF ROOTS
The Root System. — The offices of the root are to hold
the plant hi place, and to gather food. Not all the food
materials, however, are gathered by the roots.
Fig. 32. — Tap-root
System of Alfalfa.
Fig. 33. — Tap-root of the Dandelion.
The entire mass of roots of any plant is called its root
system. The root system may be annual, biennial or peren-
nial, herbaceous or woody, deep or shallow, large or small.
Kinds of Roots. — A strong leading central root, which
runs directly downwards, is a tap-root. The tap-root forms
32
THE ROOT— THE FORMS OF ROOTS
33
an axis from which the side roots may branch. The side
or spreading roots are usually smaller. Plants that have
such a root system are said to be tap-rooted. Examples
are red clover, alfalfa, beet, turnip,
radish, burdock, dandelion, hickory
(Figs. 32, 33).
A fibrous root system is one that
is composed of many nearly equal
slender branches. The greater
number of plants have fibrous roots.
Examples are many common
grasses, wheat, oats, corn. The
buttercup in Fig. 34 has a fibrous
root system. Many trees have a
strong tap-root when very young,
but after a while it ceases to ex-
tend strongly and the side roots
develop until finally the tap-root
character disappears.
Shape and Extent of the Root Sys-
tem. — The depth to which roots
extend depends on the kind of plant, and the nature of the
soil. Of most plants the roots extend far in all directions
and lie comparatively near the surface. The roots usually
radiate from a common point just beneath the surface of
the ground.
The roots grow here and there in search of food, often
extending much farther in all directions than the spread
of the top of the plant. Roots tend to spread farther in
poor soil than, in rich soil, for the same size of plant.
The root has no suck definite form as the stem has. Roots
are usually very crooked, because they are constantly
turned aside by obstacles. Examine roots in stony soil.
Fig. 34. — A Buttercup
Plant, with fibrous roots.
34
BEGINNERS' BOTANY
The extent of root surface is usually very large, for the
feeding roots are fine and very numerous. An ordinary
plant of Indian corn may have a total length of root
(measured as if the roots were placed end to end) of several
hundred feet.
The fine feeding roots are most abundant in the richest
part of tlie soil. They are attracted by the food materials.
Roots often will completely surround a bone or other
morsel. When roots of trees are exposed, observe that
most of them are horizontal and lie near the top of the
ground. Some roots, as of willows, extend far iiz search
of water. They often run into wells and drains, and into
the margins of creeks and ponds. Grow plants in a long
narrow box, in one end of which the soil is kept very dry
and in the other moist : observe where the roots grow.
Buttresses. — With the increase in diameter, the upper
roots often protrude above the ground and become bracing
buttresses. These buttresses are usually largest in trees
which always have been
exposed to strong winds
(Fig. 35). Because of
growth and thickening,
the roots elevate part of
their diameter, and the
washing away of the soil
makes them to appear as
if having risen out of
the ground.
Aerial Roots. — Although roots usually grow underground,
there are some that naturally grow above gi'ound. These
usually occur on cHmbing plants, the roots becoming sup-
ports or fulfilling the office of tendrils. These aerial roots
usually turn away from the light, and therefore enter the
Fro- 35-
-The Bracing Base of a
Field Pine.
THE ROOT— THE FORMS OF ROOTS
35
crevices and dark places of the wall or tree over which the
plant ,j,^ climbs. The trumpet creeper (Fig. 36), true or
' English ivy, and poison ivy climb by
means of roots.
, „^.^ B,
^m^V/'
Fig. 37. — Aerial Roots of an Orchid.
In some plants all the roots are
aerial ; that is, the plant grows above
ground, and the roots gather food
from the air. Such plants usually
grow on trees. They are known as
epiphytes or air-plants. The most fa-
miliar examples are some of the tropi-
cal orchids, which are grown in glass-
houses (Fig. 37). Roothke organs of dodder and other
parasites are discussed in a future chapter.
Fig. 36. — Aerial Roots
OF Trumpet Creeper
or Tecoma.
36
BEGINNERS' BOTANY
Some plants bear aerial roots, that may propagate the
plant or may act as braces. They are often called prop-roots.
The roots of Indian corn are familiar (Fig. 38). Many
Ecus trees, as the banyan of India, send out roots from
their branches ; when these roots reach the ground they
take hold and become great trunks, thus spreading the
top of the parent tree over large
areas. The muscadine grape of the
Southern states often sends down
roots from its stems. The man-
grove tree of the tropics grows along
seashores and sends down roots
from the overhanging branches
(and from the fruits) into the shal-
low water, and thereby gradually
marches into the sea. The tangled
mass behind catches the drift, and
soil is formed.
Adventitious Roots. — Sometimes
roots grow from the stem or other
unusual places as the result of some
accident to the plant, being located
without known method or law.
They are called adventitious (chance )
roots. Cuttings of the stems of
roses, figs, geraniums, and other plants, when planted,
send out adventitious roots and form new plants. The
ordinary roots, or soil roots, are of course not classed as
adventitious roots. The adventitious roots arise on occa-
sion, and not as a normal or regular course in the growth
of the plant.
No two roots are alike ; that is, they vary among them-
selves as stems and leaves do. Each kind of plant has its.
Fig. 38. — Indian Corn,
showing the brace roots
at 00.
{
THE ROOT— THE FORMS OF ROOTS
37
own form or habit of root (Fig. 39). Carefully wash away
the soil from the roots of any two related plants, as oats
and wheat, and note the differences in size, depth, direc-
tion, mode of branching, num-
ber of fibrils, color, and other
Fig. 39. — Roots of Barley at A and Corn at B.
Carefully trace the differences.
features. The character of the root system often governs
the treatment that the farmer should give the soil in which
the plant or crop grows.
Roots differ not only in their form and habit, but also in
color of tissue, character of bark or rind, and other features.
It is excellent practice to try to identify different plants by
means of their roots. Let each pupil bring to school two
plants with the roots very carefully dug up, as cotton,
corn, potato, bean, wheat, rye, timothy, pumpkin, clover,
sweet pea, raspberry, strawberry, or other common plants.
Root Systems of Weeds. — Some weeds are pestiferous
because they seed abundantly, and others because their
underground parts run deep or far and are persistent.
Make out the root systems in the six worst weeds in your
locality.
CHAPTER VIII
THE ROOT. — FUNCTION AND STRUCTURE
The function of roots is twofold, — to provide support or
anchorage for the plant, and to collect and convey food ma-
terials. The first function is considered in Chapter VII ;
we may now give attention in more detail to the second.
The feeding surface of the roots
is near their ends. As the roots
become old and hard, they serve
only as channels through which
food passes and as holdfasts or
supports for the plant. The root-
hold of a plant is very strong.
Slowly pull upwards on some plant,
and note how firmly it is anchored
in the soil.
Roots have power to choose their
food; that is, they do not absorb
all substances with which they
come in contact. They do not take
up great quantities of useless or
harmful materials, even though
these materials may be abundant in the soil ; but they
may take up a greater quantity of some of the plant-foods
than the plant can use to advantage. Plants respond very
quickly to liberal feeding, — that is, to the application of
plant-food to the soil (Fig 40). The poorer the soil, the
more marked are the results, as a rule, of the application
38
Fig. 40. — Wheat GROWING
UNDER Different Soil
Treatments. Soil defi-
cient in nitrogen ; com-
mercial nitrogen applied
to pot 3 (on right).
THE ROOT— FUNCTION AND STRUCTURE
39
of fertilizers. Certain substances, as common salt, will kill
the roots.
Roots absorb Substances only in Solution. — Substances
cannot be taken in solid particles. These materials are
in solution in the soil water, and the roots themselves
also have the power to dissolve the soil materials to some
extent by means of substances that
they excrete. The materials that ,J^ %
come into the plant through the
roots are water and mostly the min-
eral substances , as compounds of po-
tassium, iron, phosphorus, calcium,
magnesium, sulfur, and chlorine.
These mineral substances compose
the ash when the plant is burned.
The carbon is derived from the air
through the green parts. Oxygen
is derived from the air and the soil
water.
Nitrogen enters through the Roots.
— All plants must have nitrogen;
yet, although about four fifths of fig. 41. -Nodules on roots
, . . . , OF RED Clover.
the air is nitrogen, plants are not
able, so far as we know, to take it in through their leaves.
It enters through the roots in combination with other ele-
ments, chiefly in the form of nitrates (certain combinations
with oxygen and a mineral base). The great family of
leguminous plants, however (as peas, beans, cowpea,
clover, alfalfa, vetch), use the nitrogen contained in the air
in the soil. They are able to utilize it through the agency
of nodules on their roots (Figs. 41, 42). These nodules
contain bacteria, which appropriate the free or uncom-
bined nitrogen and pass it on to the plant. The nitrogen
40
BEGINNf.JiS' BOTANY
becomes incorporated in the plant tissue, so that these
crops are high in their nitrogen content. Inasmuch as
nitrogen in any form is
expensive to purchase in
fertilizers, the use of legu-
minous crops to plow under
is a very important agricul-
tural practice in preparing
the land for other crops.
In order that leguminous
crops may acquire atmos-
^ M^if Wf:f7M3M^WM^!i pherlc nitrogen more freely
and thereby thrive better,
the land is sometimes sown
or inoculated with the nod-
FiG. 42. — Nodules on Vetch. , r ■ i, , „■
ule-jornimg bacteria.
Roots require moisture in order to serve the plant. The
soil water that is valu-
able to the plant is not
the free water, but the
thin film of moisture
which adheres to each
little particle of soil. The
finer the soil, the greater
the number of particles,
and therefore the greater
is the quantity of film
moisture that it can hold.
This moisture surround-
ing the grains may not
be perceptible, yet the
plant can use it. Root absorption may continue in a soil
which seems to be dust dry. Soils that are very hard and
Fig. 43. — Two Kinds of Sou. that have
BEEN Wet and then Dried. The
loamy soil above remains loose and capa-
ble of growing plants; the clay soil below
has baked and cracked.
THE ROOT— FUNCTION AND STRUCTURE
41
"baked" (Fig. 43) contain very little moisture or air, —
not so much as similar soils that are granular or mellow.
Proper Temperature for Root Action. — The root must be
warm, in order to perform its functions. Should the soil of
fields or greenhouses be much colder than the air, the
plant suffers. When in a warm atmosphere, or in a dry
atmosphere, plants need to absorb much water from the
soil, and the roots must be warm if the root-hairs are to
supply the water as rapidly as it is needed. If the roots are
chilled, the plant may wilt or die.
Roots need Air. — Corn on land that has been flooded by
heavy rains loses its green color and turns yellow. Besides
diluting plant-food, the water drives the air from the soil, and
this suffocation of the roots is very soon ap-
parent in the general ill health of the plant.
Stirring or tilling, the soil aerates it. Water
plants and bog plants have adapted them-
selves to their particular conditions. They
get their air either by special surface roots,
or from the water through stems and leaves.
Rootlets. — Roots divide into the thijinest
and finest fibrils : there ai'e roots and there
are rootlets. The smallest rootlets are so
slender and delicate that they break off
even when the plant is very carefully lifted
from the soil.
The rootlets, or fine divisions, are clothed with the root-
hairs (Figs. 44, 45, 46). These root-hairs attach to the
soil particles, and a great amount of soil is thus brought
into actual contact with the plant. These are very deli-
cate prolonged surface cells of the roots. They are borne
for a short distance just back of the tip of the root.
Rootlet and root-hair differ. The rootlet is a compact
Fig. 44. — Root-
hairs OF THE
Radish.
BEGINNERS' BOTANY
Fig. 45. — Cross-section of Root,
enlarged, showing root-hairs.
cellular structure. The root-hair is a delicate tubular
cell (Fig. 45), within which is contained living matter
{jirotoplasjn); and the protoplasmic linitig membrane of the
wall governs the entrance of
water and substances in solu-
tion. Being long and tube-
like, these root-hairs are
especially adapted for tak-
ing in the largest quantity
of solutions ; and they are
the principal means by which
plant-food is absorbed from
the soil, although the sur-
faces of the rootlets them-
selves do their part. Water
plants do not produce an
abundant system of root-hairs, and such plants depend
largely on their rootlets.
The root-hairs are very small, often invisible. They,
with the young roots, are usually broken off when the
plant is pulled up. They are
best seen when seeds are germi-
nated between layers of dark
blotting paper or flannel. On
the young roots, they will be
seen as a mold-like or gossamer-
like covering. Root-hairs soon
die : they do not grow into roots.
New ones form as the root grows.
Osmosis. — The water with its
nourishment goes through the
thin walls of the root-hairs and rootlets by the process
of osmosis. If there are two liquids of different density
Fig. 46. — Root-hair, much en-
larged, in contact with the soil
particles (s) . Air-spaces at a ;
water-films on the particles, as
at w.
THE ROOT— FUNCTION AND STRUCTURE 43
on the inside and outside of an organic (either vegetable
or animal) membrane, the liquids tend to mix through the
membrane. The law of osmosis is that the most rapid
flow is toward the denser solution. The protoplasmic lin-
ing of the cell wall is such a membrane. The soil water
being a weaker solution than the sap in the roots, the
flow is into the root. A strong fertilizer sometimes causes
a plant to wither, or "burns it." Explain.
Structure of Roots. — The root that grows from the lower
end of the caulicle is the first or primary root. Secondary
roots branch from the primary root. Branches of second-
ary roots are sometimes called tertiary roots. Do the sec-
ondary roots grow from the cortex, or from the central
cylinder of the primary root.' Trim or peel the cortex
from a root and its branches and determine whether the
branches still hold to the central cylinder of the main root.
Internal Structure of Roots. — A section of a root shows
that it consists of a central cylinder (see Fig. 45) sur-
rounded by a layer. This layer is called the cortex. The
outer layer of cells in the cortex is called the epidermis,
and some of the cells of the epidermis are prolonged
and form the dehcate root-hairs. The cortex resembles
the bark of the stem in its nature. The central cylinder
contains many tube-like canals, or "vessels" that convey
water and food (Fig. 45). Cut a sweet potato across (also
a radish and a turnip) and distinguish the central cylin-
der, cortex and epidermis. Notice the hard cap on the tip
of roots. Roots differ from stems in having no real pith.
Microscopic Structure of Roots. — Near the end of any
young root or shoot the cells are found to differ from each
other more or less, according to the distance from the
point. This differentiation takes place iji the region Jnst
back of the growing point. To study growing points, use
44
BEGINNERS' BOTANY
the hypocotyl of Indian corn which has grown about one
half inch. Make a longitudinal section. Note these points
(Fig. 47): {a) the tapering root-cap beyond the growing
point ; (^) the blunt end of the root proper and the rec-
tangular shape of the cells found there; (c) the group
of cells in the middle of the first layers beneath the root-
cap, — this group is the growing
point; {d) study the sHght differ-
ences in the tissues a short dis-
tance back of the growing point.
There are four regions : the central
cylinder, made up of several rows
of cells in the center (//); the en-
dodermis, {e) composed of a single
layer on each side which separates
the central cylinder from the bark ;
the cortex, or inner bark, {e) of sev-
eral layers outside the endodermis ;
and the epidermis, or outer layer of
bark on the outer edges (^). Make
a drawing of the section. If a
series of the cross-sections of the
hypocotyl should be made and stud-
ied, beginning near the growing
point and going upward, it would
be found that these four tissues become more distinctly
marked, for at the tip the tissues have not yet assumed
their characteristic form. The central cyHnder contains
the ducts and vessels which convey the sap.
The Root-cap. — Note the form of the root-cap shown in
the microscopic section drawn in Fig. 47. Growing cells,
and especially those which are forming tissue by sub-
dividing, are very dehcate and are easily injured. The
Fig. 47. — Growing Point
OF Root of Indian Cokn.
dy d, cells which will form the
epidermis; p, /, cells that
will form bark; ^, ^, endoder-
mis; pi, cells which will form
the axis cylinder; /, initial
group of cells, or growing
point proper: c, root-cap.
THE ROOT— FUNCTION AND STRUCTURE
45
cells forming the root-cap are older and
tougher and are suited for pushing
aside the soil that the root may pene-
trate it.
Region of most Rapid Growth. — The
roots of a seedling beah may be marked
at equal distances by waterproof ink or
by bits of black thread tied moderately
tight. The seedling is then replanted
and left undisturbed for two days.
When it is dug up, the region of most
rapid growth in the
Fig. 48. — The Mark-
ing OF THE Stem
AND Root.
Fig. 49. — The Result.
root can be deter-
mined. Give a reason why a root
cannot elongate throughout its length,
— whether there is anything to pre-
vent a young root from doing so.
In Fig. 48 is shown a germinating
scarlet runner bean with a short root
upon which are marks made with
waterproof ink ; and the same root
(Fig. 49) is shown after it has
grown longer. Which part of it
did not lengthen at all 1 Which
part lengthened slightly .' Where
is the region of most rapid growth.'
Geotropism. — Roots turn to-
ward the earth, even if the seed
is planted with the micropyle up.
This phenomenon is called posi-
tive geotropism. Stems grow away
from the earth. This is negative
geotropism.
46
BEGINNERS' BOTANY
Suggestions (Chaps. VII and VIII). — 25. Tests for food. Ex-
amine a number of roots, including several fleshy roots, for the
presence of food material, making the tests used on seeds. 26.
Study of root-hairs. Carefully germinate radish, turnip, cabbage,
or other seed, so that no delicate parts of the root will be injured.
For this purpose, place a few seeds in packing-moss or in the folds
of thick cloth or of blotting paper, being careful to keep them moist
and warm. In a few days the seed has germinated, and the root
has grown an inch or two long. Notice that, except at a dis-
tance of about a quarter of an inch behind the tip, the root is
covered with minute hairs (Fig. 44). They are actually hairs ;
that is, root-hairs. Touch them and they collapse, they are so
delicate. Dip one of the plants in water, and when removed the
hairs are not to be seen. The water mats them together along
the root and they are no longer evident. Root-hairs are usually
destroyed when a plant is pulled out of the soil, be it done
ever so carefully. They cling to the minute particles of soil
(Fig. 46). The hairs show best against a dark background.
27. On some of the blotting papers, sprinkle sand ; observe how
the root-hairs cling to the grains. Observe how they are flat-
tened when they come in contact with grains of sand. 28. Root
hold of plant. The
pupil should also
study the root hold.
Let him carefully pull
up a plant. If a plant
grow alongside a
fence or other rigid
object, he may test
the root hold by se-
curing a string to
the plant, letting the
string hang over the
fence, and then add-
ing weights to the
string. Will a stake
of similar size to the
plant and extending
no deeper in the
ground have such
firm hold on the soil ?
What holds the ball
of earth in Fig. 50?
29. Roots exert pressure. Place a strong bulb of hyacinth or
daffodil on firm-packed earth in a pot ; cover the bulb nearly to
the top with loose earth ; place in a cool cellar ; after some days
Fig. so. — The Grasp of a Plant on the Parti-
cles OF Earth. A grass plant pulled in a garden.
THE ROOT— FUNCTION AND STRUCTURE
47
Fig. si.—
Plant grow-
ing IN In-
verted Pot.
or weeks, note that the bulb has been raised out of the earth by
the forming roots. All roots exert pressure on the soil as they grow.
Explain. 30. Response of roots and stems to the force of gravity,
or geotropism. Plant a fast-growing seedling in a
pot so that the plumule extends through the drain
hole and suspend the pot with mouth up {i.e. in
the usual position). Or use a pot in which a plant
is already growfng, cover with cloth or wire gauze
to prevent the soil from falling, and suspend the
pot in an inverted position (Fig. 51). Notice the
behavior of the stem, and after a few days remove
the soil and observe the position of the root. 31. If
a pot is laid on one side, and changed every two
days and laid on its opposite side, the effect on the
root and stem will be interesting. 32. If a fleshy
root is planted wrong end up, what is the result ?
Try it with pieces of horse-radish root. 33. By
planting radishes on a slowly revolving wheel the
effect of gravity may be neutralized. 34. Region of
root most sensitive to gravity. Lay on its side a pot containing a
growing plant. After it has grown a few days, wash away the earth
surrounding the roots. Which turned downward most decidedly,
the tip of root or the upper part? 35. Soil texture. Carefully turn
up soil in a rich garden or field so that you have unbroken lumps
as large as a hen's egg. Then break these lumps apart carefully
with the fingers and
determine whether
there are any traces
or remains of roots
(Fig. 52). Are there
any pores, holes, or
channels made by
roots ? Are the roots
in them still living ?
36. Compare an-
other lump from a
clay bank or pile
where no plants
have been growing.
Is there any differ-
ence in texture? 37. Grind up this clay lump very fine, put it in
a saucer, cover with water, and set in the sun. After a time it
will have the appearance shown in the lower saucer in Fig. 43.
Compare this with mellow garden soil. In which will plants grow
best, even if the plant-food were the same in both ? Why? 38. To
test the effect of moisture on the plant, let a plant in a pot or box dry
Fig. 52. — Holes in Soil made by Roots, now
decayed. Somewhat magnified.
48 BEGINNERS' BOTANY
out till it wilts ; then add water and note the rapidity with which
it recovers. Vary the experiment in quantity of water apphed.
Does the plant call for water sooner when it stands in a sunny win-
dow than when in a cool shady place? Prove it. 39. Immerse
a potted plant above the rim of the pot in a pail of water and let
it remain there. What is the consequence ? Why ? 40. To test
the effect of ternperature on roots. Put one pot in a dish of icp
water, and another in a dish of warm water, and keep them in a
warm room. In a short time notice how stiff and vigorous is the
one whose roots are warm, whereas the other may show signs of
wilting. 41. The process of osmosis. Chip away the shell from
the large end of an egg so as to expose the uninjured membrane
beneath for an area about as large as a dime. With sealing-wax,
chewing-gum, or paste stick a quill about three inches long to
the smaller end of the egg. After the tube is in place, run a
hat pin into it so as to pierce both shell and membrane ; . or use
a short glass tube, first scraping the shell thin with a knife and
then boring through it with the tube. Now set the egg upon the
mouth of a pickle jar nearly full of water, so that the large end
with the exposed membrane is beneath the water. After several
hours, observe the tube on top of the egg to see whether the water
has forced its way into the egg and increased its volume so that
part of its contents are forced up into the tube. If no tube is at
hand, see whether the contents are forced through the hole which
has been made in the small end of the egg. Explain how the law
of osmosis is verified by your result. If the eggshell contained
only the membrane, would water rise into it? If there were no
water in the bottle, would the egg-white pass down into the bot-
tle ? 42. The region of most rapid growth. The pupil should
make marks with waterproof ink (as Higgins' ink or indelible
marking ink) on any soft growing roots. Place seeds of bean,
radish, or cabbage between layers of blotting paper or thick cloth.
Keep them damp and warm. When stem and root have grown
an inch and a half long each, with waterproof ink mark spaces
exactly one quarter inch apart (Figs. 48, 49). Keep the plantlets
moist for a day or two, and it will be found that on the stem some
or all of the marks are more than one quarter inch apart ; on the
root the marks have not separated. The root has grown beyond
the last mark.
Note to Teacher. — The microscopic structure of the root can
be determined only by the use of the compound microscope ; but
a good general conception of the structure may be had by a care-
ful attention to the text and pictures and to explanations by the
teacher, if such microscopes are not to be had. See note at close
of Chapter X.
CHAPTER IX
THE STEM — KINDS AND FORMS; PRUNING
The Stem System. — The stem of a plant is the part
that bears the buds, leaves, flowers, and fruits. Its office
is to hold these parts 7ip to the light and air ; and through
its tissues the various food-materials and the life-giving
fluids are distributed to the growing and working parts.
The entire mass or fabric of stems of any plant is called
its stem system. It comprises the trunk, branches, and
twigs, but not the stalks of leaves and flowers that die and
fall away. The stem system may be herbaceous or woody,
annual, biennial, or perennial ; and it may assume many
sizes and shapes.
Stems are of Many Forms. — The general way in which
a plant grows is called its habit. The habit is the appear-
ance or general form. Its habit may be open or loose,
dense, straight, crooked, compact, straggling, climbing,
erect, weak, strong, and the like. The roots and leaves
are tJie important functional or working parts ; the stem
merely connects them, and its form is exceedingly variable.
Kinds of Stems. — The stem, may be so short as to be
scarcely distinguishable. In such cases the crown of the
plant — that part just at the surface of the ground — bears
the leaves and flowers ; but this crown is really a very
short stem. The dandelion. Fig. 33, is an example. Such
plants are often said to be stemless, however, in order to
distinguish them from plants that have Long or conspic-
E 49
so
BEGINNERS-' BOTANY
uous Stems. These so^alled stemless plants die to the
ground every year.
Stems are erect when they grow straight up (Figs. 53,
54). They are trailing when they run along on the ground,
Fig. 53. — Strict Simple
Stem of Mullein.
Fig. 54. — Strict Upright Stem
OF Narrow-leaved Dock.
as melon, wild morning-glory (Fig. 55). They are creep-
ing when they run on the ground and take root at places,
Fig. 55. — Trailing Stem of Wild Morning Glory {Convolvulus arvensis).
as the strawberry. They are decumbent when they lop
over to the ground. They are ascending when they lie
mostly or in part on the ground but stand more or less
upright at their ends ; e.xample, a tomato. They are
THE STEMS— KINDS AND FORMS; PRUNING
51
climbing when they cling to other objects
for support (Figs. 36, 56).
Trees in which the main trunk or the
"leader" continues to grow from its tip
are said to be excurrent in growth. The
branches are borne along the sides of the
trunk, as in common pines (Fig. 57) and
spruces. Excurrent means running out or
running up.
Trees in which the main trunk does
not continue are said to be deliques-
cent. The branches arise from one
common point or from each other. The
stem is lost in the branches. The apple
tree, plum (Fig. 58), maple, elm, oak, China
tree, are familiar examples. Deliquescent
means dissolving or melting away.
Each kind of plant has its own peculiar
habit or direction of growth; spruces al-
ways grow to a single stem or trunk, pear
>\ %' >
Fig. 57. — Excurrent
Trunk. A pine.
Fig. 58. — Deliquescent Trunk
OF Plum Tree.
52 BEGINNERS' BOTANY
trees are always deliquescent, morning-glories are always
trailing or climbing, strawberries are always creeping.
We do not know why each plant has its own habit, but
the habit is in some way associated with the plant's gene-
alogy or with the way in which it has been obliged to live.
The stem may be simple or branched. A simple stem
usually grows from the terminal bud, and side branches
either do not start, or, if they start, they soon perish.
Mulleins (Fig. 53) are usually simple. So are palms.
Branclicd stems may be of very different habit and shape.
Some stem systems are narrow and erect ; these are said
to be strict (Fig. 54). Others are diffuse, open, branchy,
tzviggy.
Nodes and Internodes. — The parts of the stem at which
buds grow are called nodes or joints and the spaces be-
tween the buds are internodes. The stem at nodes is
usually enlarged, and the pith is usually interrupted. The
distance between the nodes is influenced by the vigor of
the plant: how.?
Fig. 59. — Rhizome or Rootstock.
Stems vs. Roots. — Roots sometimes grow above ground
(Chap. VII); so, also, stems sometimes grow underground,
and they are then known as subterranean stems, rhizomes,
or rootstocks (Fig. 59).
Stems normally bear leaves and buds, and thereby are
they distinguished from roots; usually, also, they contain
a pith. The leaves, however, may be reduced to mere
scales, and the buds beneath them may be scarcely visible.
THE STEMS— KINDS AND FORMS; PRUNING 53
Thus the "eyes" on a white potato are cavities with a
bud or buds at the bottom (Fig. 60). Sweet potatoes have
no evident "eyes" when first dug (but they may develop
adventitious buds before the next grow-
ing-season). The white potato is a stem :
the sweet potato is probably a root.
How Stems elongate. — Roots elongate
by growing near the tip. Stems elon-
gate by growing more or less throuzh- ^'*^" *°' ~ sprouts
° ° ARISING FROM THE
oiLt the young or soft part or " between buds, or eyes, of a
joints " (Figs. 48, 49). But any part p°'^'° '"''^'••
of the stem soon reaches a limit beyond which it cannot
grow, or becomes "fixed"; and the new parts beyond
elongate until they, too, become rigid. When a part of
the stem once becomes fixed or hard, it never increases in
length : that is, the trunk or woody parts never grow lotiger
or higher ; branches do not become farther apart or higher
from, the ground.
Stems are modified in form by the particular or incidental
conditions under which they grow. The struggle for light
is the chief factor in determining the shape and direction
of any limb (Chap. II). This is well illustrated in any
tree or bush that grows against a building or on the mar-
gin of a forest (Fig. 4). In a very dense thicket the
innermost trees shoot up over the others or they perish.
Examine any stem and endeavor to determine why it took
its particular form.
The stem is cylindrical, tJie outer part being bark and
the inner part being wood or woody tissue. In the dicoty-
ledonous plants, the bark is usually easily separated from
the remainder of the cylinder at some time of the year ; in
monocotyledonous plants the bark is not free. Growth in
thickness takes place inside the covering and not on the very
54
BEGINA'F.RS' BOTAKY
outside of the plant cylinder. It is evident, then, that the
covering of bark imist expand in order to alloxv of the expan-
sion of the woody cylinder within it. The tis-
sues, therefore, must be under constant pressure
or tension. It has been determined that the
pressure within a growing trunk is often as
much as fifty pounds to the square inch. The
lower part of the limb in Fig. 6i shows that
the outer layers of bark (which are long since
dead, and serve only as protective tissue) have
reached the limit of their expanding capacity
and have begun to split. The pupil will now
be interested in the bark on the body of an old
elm tree (Fig. 62); and he should be able to
suggest one reason why stems remain cylindri-
cal, and why the old bark becomes marked
with furrows, scales, and plates.
Most woody plants increase in diameter by the
addition of an anmial layer or "ring" on the
outside of the woody cylinder,
underneath the bark. The monocotyledo-
nous plants comprise very few trees and
shrubs in temperate climates (the palms,
yuccas, and other tree-like plants are of
this class), and they do not increase
greatly in diameter and they rarely branch
to any extent. Consult the woodpile for
information as to the annual rings.
Bark-bound Trees. — If, for any rea-
son, the bark should become so dense
and strong that the trunk cannot ex-
pand, the tree is said to be " bark-bound." Such condition
is not rare in orchard trees that have been neglected.
Fig. 61.—
Cracking
OF THE
Bark on an
Elm
Branch.
Fig. 62. — Piece of
Bark from an
Old Elm Trunk.
THE STEMS— KINDS AND FORMS; PRUNING
55
When good tillage is given to such trees, they may not
be able to overcome the rigidity of the old bark, and,
therefore, do not respond to the treatment. Sometimes
the thinner-barked parts may outgrow in diameter the
trunk or the old branches below them. The remedy is
to release the tension. This may be done either by soften-
ing the bark (by washes of soap or lye), or by separating
it. The latter is done by slitting the bark-bound part
(in spring), thrusting the point of a knife through the
bark to the wood and then drawing the blade down the
entire length of the bark-
bound part. The slit is
scarcely discernible at first,
but it opens with the growth
of the tree, filling up with
new tissue beneath. Let the
pupil consider the ridges
which he now and then finds
on trees, and determine
whether they have any sig-
nificance — whether the tree
has ever been released or in-
jured by natural agencies.
The Tissue covers the
Wounds and " heals " them.
— This is seen in Fig. 63, in which a ring of tissue rolls out
over the wound. This ring of healing tissue forms most
rapidly and uniformly when the wound is smooth and regu-
lar. Observe the healing on broken and splintered limbs ;
also the difference in rapidity of healing between wounds
on strong and weak limbs. There is difference in the
rapidity of the healing process in different kinds of trees.
Compare the apple tree and the peach. This tissue may in
Fig. 63. — Proper Cutting of a
Branch. The wound will soon he
"healed."
56
BEGIXXEKS' BOTANY
Fig. 64. — Erroneous
Pruning.
turn become bark-bound, and the healing may stop. On
large wounds it progresses more rapidly the first few years
than it does later. This roll or
ring of tissue is called a callus.
The callus grows from the liv-
ing tissue of the stem just about
the wound. It cannot cover long
dead stubs or very rough broken
branches (Fig. 64). Therefore,
in pruning the branches should be
cut close to the trunk and made
even and smooth ; all lofig stubs
must be avoided. The seat of
the wound should be close to the
living part of the trunk, for the
stub of the limb that is severed
has no further power in itself
of making healing tissue. The
end of the remaining stub is
merely covered over by the
callus, and usually remains a
dead piece of wood sealed in-
side the trunk (Fig. 6$). If
wounds do not heal over speed-
ily, germs and fungi obtain
foothold in the dying wood
and rot sets in. Hollow trees
are those in which the decay-
fungi have progressed into the
inner wood of the trunk ; they
have been infected {Y\g. 66).
Large wounds should be protected with a covering of
paint, melted wax, or other adhesive and lasting material,
Fig. 65.
Knot in a Hemlock
Log.
THE STEMS— KINDS AND FORMS; PRUNING
57
Fig. 66. — a Knot Hole,
and the beginning of a
hollow trunk.
to keep out the germs and fungi.
A covering of sheet iron or tin may
keep out the rain, but it will, not ex-
clude the germs of decay ; in fact,
it may provide tlie very moist con-
ditions that such germs need for
their growth. Deep holes in trees
should be treated by having all the
decayed parts removed down to the
clean wood, the surfaces painted or
otherwise sterilized, and the hole
filled with wax or cement.
Stems and roots are living, and
they should not be wounded or
mutilated unnecessarily. Horses
should never be hitched to trees.
Supervision should be exercised
over persons who run telephone,
telegraph, and electric light wires,
to see that they do not mutilate
trees. Electric light wires and trol-
ley wires, when carelessly strung
or improperly insulated, may kill
trees (Fig. tj).
Suggestions. — Forms of stems.
43. Are ttie trunks of trees ever per-
fectly cylindrical? If not, what may
cause the irregularities ? Do trunks often
grow more on one side than the other?
44. Slit a rapidly growing limb, in spring,
with a knife blade, and watch the re-
sult during the season. 45. Consult the
woodpile, and observe the variations in fig. 67.— Elm Tree killed
thickness of the annual rings, and espe- by a Direct Current
cially of the same rii'^ at different places from an Electric
in the circumference. Cross-sections of railroad System.
58
BEGINNERS' BOTANY
horizontal branches are interesting in this coiinection. 46. Note
the enlargement at the base of a branch, and determine whether
this enlargement or bulge is larger on long, horizontal limbs than
on upright ones. Why does this bulge develop? Does it serve
as a brace to the limb, and is it developed as the result of constant
strain? 47. Strength of stems. The pupil should observe the
fact that a stem has wonderful strength. Compare the propor-
tionate height, diameter, and weight of a grass stem with those of
the slenderest tower or steeple. Which has the greater strength ?
Which the greater height? Which will withstand the most wind?
Note that the grass stem will regain its position even if its top is
bent to the ground. Note how plants are weighted down after a
heavy rain and how they recover themselves. 48. Spht a corn-
stalk and observe how the joints are tied together and braced with
fibers. Are there similar fibers in stems of pigweed, cotton, sun-
flower, hollyhock ?
Fig. 68. — Potato. What are roots, and what stems ? Has the plant more than
one kind of stem ? more than two kinds ? Explain.
CHAPTER X
THE STEM — ITS GENERAL STRUCTURE
There are two main types of stem structure in flowering
plants, the differences being based on the arrangement of
bundles or strands of tissue. These types are endogenous
and exogenous (page 20). It will require patient laboratory
work to understand what these types and structures are.
Endogenous, or Monocotyledonous Stems. — Examples of
endogenous stems are all the grasses, cane-brake, sugar-
cane, smilax or green-brier,
palms, banana, canna, bam-
boo, lilies, yucca, aspara-
gus, all the cereal grains.
For our study, a cornstalk
may be used as a type.
A piece of cornstalk,
either green or dead, should
be in the hand of each
pupil while studying this
lesson. Fig. 69 will also
be of use. Is there a swelling at the nodes.' Which
part of the internode comes nearest to being perfectly
round .' There is a grooved channel running along one
side of the internode : how is it placed with reference to
the leaf ? with reference to the groove in the internode
below it .'' What do you find in each groove at its lower
end? (In a dried stalk only traces of this are usually
seen.) Does any bud on a cornstalk besides the one at
Fig. 69.'— Cross-section of Corn-
stalk, showing the scattered fibro-
vascular bundles. Slightly enlarged.
6o
BEGINNERS' BOTANY
the top ever develop ? Where do suckers come from ?
Where does the ear grow ?
Cut a cross-section of the stalk between the nodes (Fig.
69). Does it have a distinct bark ? The interior consists
of soft "pith" and tough woody parts. The wood is found
in strands or fibers. Which is more abundant .-' Do the
fibers have any definite arrangement .-' Which strands are
largest.'' Smallest.-' The firm smooth r/«r
-r-
from leaves. As a rule leaves can be distinguished by
the following tests: (i) L,&a.ves are temporary s/ructu/rs,
sooner or later falling. (2) Usually iicds are borne in their
axils. (3) Leaves are usually borne at joints or
7wdes. (4) They arise on wood of the current
years growth. (5) They have a more or less
definite arrangement. When leaves fall, the twig
that bore them remains ; when leaflets fall, the
main petiole or stalk that bore them also falls.
Shapes. — Leaves and leaflets are infinitely
variable in shape. Names have been given to
some of the more definite or regular shapes.
These names are a part of the language of bot-
any. The names represent ideal or
typical shapes ; there are no two
leaves alike and very
few that perfectly con-
form to the definitions. ^
The shapes are likened
to those of familiar ob-
jects or of geometrical
Fig. 102.— figures. Some of the
Linear- commoner shapes are as
ACUMINATE ^ ,, , ...
LEAF OF follows (name origmal fig. ios.-Short-obi.ong
Grass. examples in each class): Leaves of Box.
Linear, several times longer than broad, with the sides
\ nearly or quite parallel. Spruces and most grasses
are examples (Fig. 102). In linear leaves, the main
veins are usually parallel to the midrib.
Oblong, twice or thrice as long as broad, with the sides
\ parallel for most of their length. Fig. 103 shows the
short-oblong leaves of the box, a plant that is used
for permanent edgings in gardens.
'^
\
^ I
I
'1
LEAVES— FORM AND POSITION
79
Elliptic differs from the oblong in having the sides gradu-
ally tapering to either end from the middle. The
^k European beech (Fig. 104) has elliptic
^1^ leaves. (This tree is often planted in
this country.)
Lanceolate, four to six times longer than
broad, widest below the middle, and
\ tapering to either end. Some of the
narrow-leaved willows are examples.
Most of the willows and the peach
have oblong-lanceolate leaves.
Spatulate, a narrow leaf that is broadest
\ toward the apex. The top is usually
rounded.
Fig, \ 104.
Elliptic Leaf
OF Purple
Beech,
Fig, log. — Ovate
Serrate Leaf of
Hibiscus.
Fig. 106, — Leaf of Apple, showing blade, petiole,
and small narrow stipules.
Ovate, shaped somewhat like the longitudinal section of an
^ egg : about twice as long as broad, tapering from near
^ the base to the apex. This is one of the commonest
^ leaf forms (Figs. 105, 106).
8o
BEGINNERS' BOTANY
Obovate, ovate inverted, — the wide part towards the apex.
Leaves of mullein and leaflets of horse-chestnut and
V false indigo are obovate. This form is commonest
in leaflets of digitate leaves : why .''
Reniform, kidney-shaped. This form is sometimes seen in
^^ wild plants, particularly in root-leaves. Leaves of
^^ wild ginger are nearly reniform.
Orbicular, circular in general outHne. Very few leaves are
^^ perfectly circular, but there are many that are
^^ nearer circular than any other shape (Fig. la/).
Fig. 107. — Orbicular
LoBED Leaves.
Fig. ioS.— Truncate
Leaf of Tulip Tree.
The shape of many leaves is described in combinations
of these terms : as ovate-lanceolate, lanceolate-oblong.
The shape of the base and apex of the leaf or leaflet
is often characteristic. The base may be rounded (Fig.
104), tapering (Fig. 93), cordate or heart-shaped (Fig. 105),
truncate or squared as if cut off. The apex may be blunt
or obtuse, acute or sharp, acuminate or long-pointed, trun-
cate (Fig. 108). Name examples.
The shape of the margin is also characteristic of each
kind of leaf. The margin is entire when it is not in-
dented or cut in any way (Figs. 99, 103). When not
LEAVES — FORM AND POSITION
entire, it may be undulate or wavy (Fig. 92), serrate or
saw-toothed (Fig. 105), dentate or more coarsely notched
(Fig. 95), crenate or round-toothed, lobed, and the hke.
Give examples.
Leaves often differ greatly in form on the same plant.
Observe the different shapes of leaves on the young
growths of mulberries (Fig. 2) and wild grapes ; also
on vigorous squash and pumpkin vines. In some cases
there may be simple and
compound leaves on the
same plant. This is
marked in the so-called
Boston ivy or ampelop-
sis (Fig. 109), a vine
that is used to cover
brick and stone build-
ings. Different degrees
of compounding, even
in the same leaf, may
often be found in honey
locust and Kentucky
coffee tree. Remarka-
ble differences in forms are seen by comparing seed-leaves
with mature leaves of any plant (Fig. 30).
The Leaf and its Environment. — The form and shape
of the leaf often have direct relation to the place in which
the leaf groivs. Floating leaves are usually expanded and
flat, and the petiole varies in length with the depth of
the water. Submerged leaves are usually linear or thread-
like, or are cut into very narrow divisions: thereby
more surface is exposed, and possibly the leaves are less
injured by moving water. Compare the sizes of the leaves
on the ends of branches with those at the base of the
Fig, 109, — Different Forms of Leaves
FROM ONE Plant of Ampelopsis.
82 BEGINiVERS' BOTANY
branches or in the interior of the tree top. In dense
foliage masses, the petioles of the lowermost or under-
most leaves tend to elongate — to push the leaf to the light.
On the approach of winter the leaf usually ceases to
work, and dies. It may drop, when it is said to be decidu-
ous; or it may remain on the plant, when it is said to be
persistent. If persistent leaves remain green during the
winter, the plant is said to be evergreen. Give examples
in each class. Most leaves fall by breaking off at the
lower end of the petiole with a distinct joint or articula-
tion. There are many leaves, however, that wither and
hang on the plant until torn off by the wind; of such
are the leaves of grasses, sedges, lilies, orchids, and other
plants of the monocotyledons. Most leaves of this char-
acter are parallel-veined.
Leaves also die and fall from lack of light. Observe the
yellow and weak leaves in a dense tree top or in any
thicket. Why do the lower leaves die on house plants .'
Note the carpet of needles under the pines. All ever-
greens shed their leaves after a time. Counting back from
the tip of a pine or spruce shoot, determine how many
years the leaves persist. In some spruces a few leaves
may be found on branches ten or more years old.
Arrangement of Leaves. — Most leaves have a regular
position or arrangement on the stem. This position or
direction is determ,ined largely by exposure to sunlight. In
temperate climates they usually hang in such a way that
they receive the greatest amount of light. One leaf shades
the other to the least possible degree. If the plant were
placed in a new position with reference to light, the leaves
would make an effort to turn their blades.
When leaves are opposite the pairs usually alternate.
That is, if one pair stands north and south, the next pair
LEAVES— FORM AND POSITION
83
stands east and west. See the box-elder shoot, on the
left in Fig. 1 10. One pair does not shade the pair beneath.
The leaves are in four vertical ranks.
There are several kinds of alternate arrangement. In the
elm shoot, in Fig. 1 10, the third bud is vertically above the
first. This is true no
matter which bud is taken
as the starting point.
Draw a thread around
the stem until the two
buds are joined. Set a
pin at each bud. Ob-
serve that two buds are
passed (not counting the
last) and that the thread
makes one circuit of the
stem. Representing the
number of buds by a de-
nominator, and the num-
ber of circuits by a
numerator, we have the
fraction J, which expresses
the part of the circle that lies between any two buds.
That is, the buds are one half of 360 degrees apart, or
180 degrees. Looking endwise at the stem, the leaves
are seen to be 2-ranked. Note that in the apple shoot
(Fig. 1 10, right) the thread makes two circuits and five
buds are passed : two-fifths represents the divergence
between the buds. The leaves are S-ranked.
Every plant has its own arrangement of leaves. For
opposite leaves, see maple, box elder, ash, lilac, honey-
suckle, mint, fuchsia. For 2-ranked arrangement, see
all grasses, Indian corn, basswood, elm. For 3-ranked
Fig. iio. ■
- Phyllotaxy of Box Elder,
Elm, Apple.
84
BEGINNERS' BOTANY
arrangement, see all sedges. For 5-ranked (which is one
of the commonest), see apple, cherry, pear, peach, plum,
poplar, willow. For 8-ranked, see holly, osage orange,
some willows. More complicated arrangements occur in
bulbs, house leeks, and other condensed parts. The buds
or " eyes" on a potato tuber, which is an underground stem
^^ (why .''), show a spiral arrangement (Fig. in).
The arrangement of leaves on the stem is
known as phyllotaxy (literally, "leaf arrange-
ment "). Make out the phyllotaxy on six
different plants nearest the schoolhouse door.
In some plants, several leaves occur at one
level, being arranged in a circle around the
stem. Such leaves are said to be verticillate,
or whorled. Leaves arranged in this way are
usually narrow: why.'
Although a definite arrangement of leaves
is the rule in most plants, it is subject to
modification. On shoots that receive the
light only from one side or that grow in dif-
ficult positions, the arrangement may not be
definite. Examine shoots that grow on the
under side of dense tree tops or in other par-
tially lighted positions.
Fig. in.—
Phyllotaxy
OF THE Po-
tato Tuber.
Work it out
on a fresh
long tuber.
Suggestions. — 55. The pupil should match leaves to determine
whether any two are alike. Why ? Compare leaves from the
same plant in size, shape, color, form of margin, length of petiole,
venation, texture (as to thickness or thinness), stage of maturity,
smoothness or hairiness. 56. Let the pupil take an average
leaf from each of the first ten different kinds of plants that
he meets and compare them as to the above points (in Exer-
cise 55), and also name the shapes. Determine how the various
leaves resemble and differ. 57. Describe the stipules of rose,
apple, fig, willow, violet, pea, or others. 58. In what part of
the world are parallel-veined leaves the more common ? 59. Do
LEAVES— FORM AND POSITION
85
you know of parallel-veined leaves that have lobed or dentate mar-
gins ? 60. What becomes of dead leaves ? 61. Why is there
no grass or other undergrowth under pine and spruce trees ?
62. Name several leaves that are useful for decorations. Why
are they useful ? 63. What trees in your vicinity are most
esteemed as shade trees ? What is the character of their foliage ?
64. Why are the internodes so long in water-sprouts and suckers ?
65. How do foliage characters in corn or sorghum differ when the
plants are grown in rows or broadcast ? Why ? 66. Why may
removal of half the plants increase the yield of cotton or sugar-
beets or lettuce ? 67. How do leaves curl when they wither ?
Do different leaves behave differently in this respect? 68. What
kinds of leaves do you know to be eaten by insects ? By cattle ?
By horses ? What kinds are used for human food ? 69. How
would you describe the shape of leaf of peach? apple? elm?
hackberry? maple? sweet-gum? corn? wheat? cotton? hickory?
cowpea? strawberry? chrysanthemum? rose? carnation? 70. Are
any of the foregoing leaves compound ? How do you describe the
shape of a compound leaf ? 71. How many sizes of leaves do you
find on the bush or tree nearest the schoolroom door ? 72. How
many colors or shades? 73. How many lengths of petioles?
74. Bring in all the shapes of leaves that you can find.
Fig. 112. — Cow-
pea. Describe
the leaves. For
what is the plant
used?
CHAPTER XII
LEAVES — STRUCTURE OR ANATOMY
Besides the framework, or system of veins found in
blades of all leaves, there is a soft cellular tissue called
mesophyll, or leaf parenchyma, and an epidermis or skin
that covers the entire outside part.
Mesophyll. — The mesophyll is not all alike or homoge-
neous. The upper layer is composed of elongated cells
placed perpendicular to the surface of the leaf. These
are called palisade cells. These cells are usually filled
with green bod-
ies called chlo-
rophyll grains.
The grain con-
tains a great
number of chlo-
rophyll drops
imbedded in
the protoplasm.
Below the pali- '
sade cells is the
spongy parenchyma, composed of cells more or less spher-
cal in shape, irregularly arranged, and provided with many
intercellular air cavities (Fig. 113). In leaves of some
plants exposed to strong light there may be more than one
layer of paUsade cells, as in the India-rubber plant and
oleander. Ivy when grown in bright light will develop
two such layers of cells, but in shaded places it may be
86
Fig. 113. — Section of a Leaf, showing the air spaces.
Breathing-pore or stoma at a. The palisade cells which chiefly
contain the chlorophyll are at b. Epidermal cells at c.
LEAVES— STRUCTURE OR ANATOMY 87
found with only one. Such plants as iris and compass
plant, which have both surfaces of the leaf equally exposed
to sunlight, usually have a palisade layer beneath each
epidermis.
Epidermis. — The outer or epidermal cells of leaves do
not bear chlorophyll, but are usually so transparent that
the green mesophyll can be seen through them. They
often become very thick-walled, and are in most plants
devoid of all protoplasm except a thin layer lining the
walls, the cavities being filled with cell sap. This sap is
sometimes colored, as in the under epidermis of begonia
leaves. It is not common to find more than one layer of
epidermal cells forming each surface of a leaf. The epi-
dermis serves to retain moisture in the leaf and as a general
protective covering. In desert plants the epidermis, as a
rule, is very thick and has a dense cuticle, thereby pre-
venting loss of water.
There are various outgrowths of the epidermis. Hairs
are the chief of these. They may be (i) simple, as on
primula, geranium, naegelia ; (2) once branched, as on wall-
flower; (3) compound, as on verbascum or mullein; (4)
disk-like, as on shepherdia; (5) stellate, or star-shaped, as
in certain crucifers. In some cases the hairs are glandular,
as in Chinese primrose of the greenhouses {Primula
Sinensis) and certain hairs of pumpkin flowers. The hairs
often protect the breathing pores, or stomates, from dust
and water.
Stomates (sometimes called breathing-pores) are small
openings or pores in the epidermis of leaves and soft stems
that allow the passage of air and other gases and vapors
{stomate or stoma, singular ; stomates or stomata, plural).
They are placed near the large intercellular spaces of the
mesophyll, usually in positions least affected by direct
88
JiJ'.GhXNERS' BOTANY
sunlight. Fig. 1 14 shows the structure. There are two
guard-cells at the mouth of each stomate, which may in
most cases open or close the passage as the conditions
of the atmosphere may require. The guard-cells contain
■4 >>T^#'7i/f'
Fig. 114.— Diagram of Stomate
OF Iris (Osterhout).
Fig. 115. — Sto.mate of Ivy,
showing compound guard-cells.
chlorophyll. In Fig. 1 1 5 is shown a case in which there
are compound guard-cells, that of ivy. On the margins
of certain leaves, as of fuchsia, impatiens, cabbage, are
openings known as water-pores.
Stomates are very numeroiis, as will be seen from the num-
bers showing the pores to each square inch of leaf surface :
Peony . ...
Holly . .
Lilac
Mistletoe . .
Tradescautici
Garden Flag (iris) .
The arrangement of stomates on the leaf dijfers with
each kind of plant. Fig. 116 shows stomates and also the
outlines of contiguous epidermal cells.
The function or work of the stomates
is to regulate the passage of gases into
and out of the plant. The directly
active organs or parts are guard-cells,
on either side the opening. One
Fig. 116, — Stomates ' °
OF Geranium Leaf. method of opening is as follows: The
,o\ver surface
Upper surface
13,790
None
63,600
None
160,000
None
200
200
2,000
2,000
11.572
11,572
LEAVES— STRUCTURE OR ANATOMY
89
thicker walls of the guard-cells (Fig. 114) absorb water
from adjacent cells, these thick walls buckle or bend and
part from each other at their middles on either side the
opening, causing the stomate to open, when the air gases
may be taken in and the leaf gases may pass out. When
moisture is reduced in the leaf tissue, the guard cells part
with some of their contents, the thick walls
straighten, and the faces of the two opposite
ones come together, thus closing the stomate
and preventing any water vapor from pass-
ing out. When a leaf is actively at work
making new organic compounds, the stomates
are usually open; when unfavorable condi-
tions arise, they are usually closed. They
also commonly close at night, when growth
(or the utilizing of the new materials) is most
likely to be active. It is sometimes safer to
fumigate greenhouses and window gardens
at night, for the noxious vapors are less
likely to enter the leaf. Dust may clog or
cover the stomates. Rains benefit plants
by washing the leaves as well as by provid-
ing moisture to the roots.
Lenticels. — On the young woody twigs
of many plants (marked in osiers, cherry,
birch) there are small corky spots or eleva-
tions known as lenticels (Fig. 117). They mark the loca-
tion of some loose cork cells that function as stomates,
for green shoots, as well as leaves, take in and discharge
gases; that is, soft green twigs function as leaves. Under
some of these twig stomates, corky material may form
and the opening is torn and enlarged : the lenticels are
successors to the stomates. The stomates lie in the epi-
%
fli
Fig. 117. — Len-
ticels on
Young Shoot
OF Red Osier
(CORNUS).
go BEGINNERS' BOTANY
dermis, but as the twig ages the epidermis perishes and
the bark becomes the external layer. Gases continue to
pass in and out through the lenticels, until the branch be-
comes heavily covered with thick, corky bark. With the
growth of the twig, the lenticel scars enlarge lengthwise
or crosswise or assume other shapes, often becoming char-
acteristic markings.
Fibro-vascular Bundles. — We have studied the fibro-
vascular bundles of stems (Chap. X). These stem bun-
dles continue into the leaves, ramifying into the veins,
carrying the soil water inwards and bringing, by diffusion,
the elaborated food out through the sieve-cells. Cut
across a petiole and notice the hard spots or areas in it ;
strip these parts lengthwise of the petiole: what are they.''
Fall of the Leaf. — In most common deciduous plants,
when the season's work for the leaf is ended, the nutritious
matter may be withdrawn, and a layer of corky cells is com-
pleted over the surface of the stem where the leaf is attached.
The leaf soon falls. It often falls even before it is killed
by frost. Deciduous leaves begin to show the surface line
of articulation in the early growing season. This articula-
tion may be observed at any time during the summer. The
area of the twig once covered by the petioles is called the
leaf-scar after the leaf has fallen. In Chap. XV are shown
a number of leaf-scars. In the plane tree (sycamore or
buttonwood), the leaf-scar is in the form of a ring surround-
ing the bud, for the bud is covered by the hollowed end of
the petiole ; the leaf of sumac is similar. Examine with a
hand lens leaf-scars of several woody plants. Note the
number of bundle-scars in each leaf-scar. Sections may
be cut through a leaf -scar and examined with the micro-
scope. Note the character of cells that cover the leaf-
scar surface.
LEAVES — STRUCTURE OR ANATOMY 9 1
Suggestions. — To study epidermal hairs : 75. For this study,
use the leaves of any hairy or woolly plant. A good hand lens will
reveal the identity of many of the coarser hairs. A dissecting micro-
scope will show them still better. For the study of the cell structure,
a compound microscope is necessary. Cross-sections may be made
so as to bring hairs on the edge of the sections ; or in some
cases the hairs may be peeled or scraped from the epidermis and
placed in water on a slide. Make sketches of the different kinds of
hairs. 76. It is good practice for the pupil to describe leaves in
respect to their covering : Are they smooth on both surfaces ? Or
hairy? Woolly? Thickly or thinly hairy? Hairs long or short?
Standing straight out or lying close to the surface of the leaf ?
Simple or branched? Attached to the veins or the plane surface?
Color? Most abundant on young leaves or old? 77. Place a
hairy or woolly leaf under water. Does the hairy surface appear
silvery ? Why ? Other questions : 78. Why is it good practice
to wash the leaves of house plants ? 79. Describe the leaf-scars
on six kinds of plants : size, shape, color, position with reference
to the bud, bundle-scars. 80. Do you find leaf-scars on mono-
cotyledonous plants — corn, cereal grains, lilies, canna, banana,
palm, bamboo, green brier? 81. Note the table on page 88.
Can you suggest a reason why there are equal numbers of stomates
on both surfaces of leaves of tradescantia and flag, and none on
upper surface of other leaves ? Suppose you pick a leaf of lilac
(or some larger leaf), seal the petiole with wax and then rub
the under surface with vaseline ; on another leaf apply the vaseline
to the upper surface ; which leaf withers first, and why ? Make a
similar experiment with iris or blue flag. 82. Why do leaves and
shoots of house plants turn towards the light? What happens
when the plants are turned around? 83. Note position of leaves
of beans, clover, oxalis, alfalfa, locust, at night.
CHAPTER XIII
LEAVES — FUNCTION OR WORK
We have discussed (in Chap. VIII) the worlc or function
of roots and also (in Chap. X) the function of stems.
We are now ready to complete the view of the main vital
activities of plants by considering the function of the
green parts (leaves and young shoots).
Sources of Food. — The ordinary green plant has but two
sources from ivhicJi to seaire food, — the air and the soil.
When a plant is thoroughly dried in an oven, the water
passes off ; this water came from tlie soil. The remaining
part is called the dry substance or dry matter. If the dry
matter is burned in an ordinary fire, only the ash remains;
tliis ash came from the soil. The part that passed off as
gas in the burning contained the elevients that cam.c from
the air ; it also contained some of those that came from
the soil — all those (as nitrogen, hydrogen, chlorine) that
are transformed into gases by the heat of a common fire.
The part that comes from the soil (the ash) is small in
amount, being considerably less than lO per cent and
sometimes less than i per cent. Water is the most
abundant single constituent or substance of plants. In a
corn plant of the roasting-ear stage, about 80 per cent of
the substance is water. A fresh turnip is over 90 per
cent water. Fresh wood of the apple tree contains about
45 per cent of water.
Carbon. — Carbon enters abundantly into the composition
of all plants. Note what happens when a plant is burned
LEAVES— FUNCTION OR WORK 93
without free access of air, or smothered, as in a charcoal
pit. A mass of charcoal remains, almost as large as the
body of the plant. Charcoal is almost pure carbon, the ash
present being so small in proportion to the large amount
of carbon that we look on the ash as an impurity. Nearly-
half of the dry substance of a tree is carbon. Carbon
goes off as a gas when the plant is burned in air. It does
not go off alone, but in combination with oxygen in the
form of carbon dioxid gas, COj.
The green plant secures its carbon from the air. In
other words, much of the solid matter of the plant comes
from one of the gases of the air. By volume, carbon dioxid
forms only a very small fraction of i per cent of the air.
It would be very disastrous to animal Hfe, however, if this
percentage were much increased, for it excludes the life-
giving oxygen. Carbon dioxid is often called "foul gas."
It may accumulate in old wells, and an experienced person
will not descend into such wells until they have been tested
with a torch. If the air in the well will not support com-
bustion, ■ — • that is, if the torch is extinguished, — it usually
means that carbon dioxid has drained into the place. The
air of a closed schoolroom often contains far too much of
this gas, along with little solid particles of waste matters.
Carbon dioxid is often known as carbonic acid gas.
Appropriation of the Carbon. — The carbon dioxid of the
air readily diffuses itself into the leaves and other greeji
parts of the plant. The leaf is delicate in texture, and when
very young the air can diffuse directly into the tissues.
The stomates, however, are the special inlets adapted for
the admission of gases into the leaves and other green
parts. Through these stomates, or diffusion-pores, the out-
side air enters into the air-spaces of the plant, and is finally
absorbed by the Httle cells containing the living matter.
94 BEGINNERS' BOTANY
Chlorophyll ("leaf green") is the agent that secures
the energy by means of which carbon dioxid is utiHzed.
This material is contained in the leaf cells in the form of
grains (p. 86) ; the grains themselves are protoplasm, only
the coloring matter being chlorophyll. The chlorophyll
bodies or grains are often most abundant near the upper
sicrface of the leaf, where they can secure the greatest
amomit of light. Without this green coloring matter,
there would be no reason for the large flat surfaces which
the leaves possess, and no reason for the fact that the
leaves are borne most abundantly at the ends of branches,
where the light is most available. Plants with colored
leaves, as coleus, have chlorophyll, but it is masked by
other coloring matter. This other coloring matter is
usually soluble in hot water : boil a coleus leaf and notice
that it becomes green and the water becomes colored.
Pla7its grown in darkness are yellow and slender, and
do not reach maturity. Compare the potato sprouts that
have grown from a tuber lying in the dark cellar with
those that have grown normally in the bright light.
The shoots have become slender and are devoid of chloro-
phyll ; and when the food that is stored in the tuber is
exhausted, these shoots will have lived useless lives. A
plant that has been grown in darkness from the seed will
soon die, although for a time the little seedling will grow
very tall and slender: why.? Light favors the prodtictiott
of chlorophyll, and the chlorophyll is the agent in the mak-
ing of the organic carbon compounds . Sometimes chloro-
phyll is found in buds and seeds, but in most cases these
places are not perfectly dark. Notice how potato tubers de-
velop chlorophyll, or become green, when exposed to light.
Photosynthesis. — Carbon dioxid diffuses into the leaf ;
during sunlight it is used, and oxygen is given off. How the
LEAVES— FUNCTION OR WORK 95
carbon dioxid which is thus absorbed may be used in mak-
ing an organic food is a complex question, and need not
be studied here; but it may be stated that carbon dioxid
and water are the constituents. Complex compounds are
built up out of simpler ones.
Chlorophyll absorbs certain light rays, atid the energy
thus directly or indirectly obtained is used by the living
■matter in uttiting the carbon dioxid absorbed from the air
with some of the water brought ttp from the roots. The
ultimate result itsually is starch. The process is obscure,
but sugar is generally one step ; and our first definite
knowledge of the product begins when starch is deposited
in the leaves. The process of using the carbon dioxid of
the air has been known as carbon assimilation, but the
term now most used is photosynthesis (from two Greek
words, meaning light and to put together).
Starch and Sugar. — All starch is composed of carbon,
hydrogen, and oxygen (CgHigOg)^. The sugars and the
substance of cell walls are very similar to it in composition.
All these substances are called carbohydrates. In making
fruit sugar from the carbon and oxygen of carbon dioxid
and from the hydrogen and oxygen of the water, there
is a surplus of oxygen (6 parts CO2 + 6 parts H2O
= CgHj.^Og + 6 O2). It is this oxygen that is given off
into the air during sunlight.
Digestion. — Starch is in the form of insoluble granules.
When such food material is carried from one part of the
plant to atiother for purposes of growth or storage, it is
made soluble before it can be transported. When this
starchy material is transferred from place to place, it is
usually changed into sugar by the action of a diastase.
This is a process ^digestion. It is much like the change
of starchy foodstuffs to sugary foods by the saliva.
96
BEGINNERS' BOTANY
Distribution of the Digested Food. — After being changed
to the soluble form, this material is ready to be used in
growth, either in the leaf, in the stem, or in the roots.
With other more complex products it is then distributed
tJiroughout all of the growing parts
of the plant; and when passing
down to the root, it seems to pass
more readily through the inner
bark, in plants which have a defi-
nite bark. This gradual down-
ward diffusion through the inner
bark of materials suitable for
growth is the process referred to
when the " descent of sap " is men-
tioned. Starch and other products
are often stored in one growing
season to be used in the next sea-
son. If a tree is constricted or
strangled by a wire around its
trunk (Fig. ii8), the digested food
cannot readily pass down and it is stored above the girdle,
causing an enlargement.
Assimilation. — The food from the air and that from the
soil unite in the living tissues. The "sap" that passes
upwards from the roots in the growing season is made up
largely of the soil water and the salts which have been
absorbed in the diluted solutions (p. 67). This upward-
moving water is conducted largely through certain tubular
canals of the young wood. These cells are never continu-
ous tubes from root to leaf; but the water passes readily
from one cell or canal to another in its upward course.
The upward-moving water gradually passes to the grow-
ing parts, and everywhere in the living tissues, it is of
Fig. 118. — Trunk Girdled
BY A Wire. See Fig. 85.
LEAVES— FUNCTION OR WORK 97
course in the most intimate contact with the soluble carbo-
hydrates and products of photosynthesis. In the build-
ing up or reconstructive and other processes it is therefore
available. We may properly conceive of certain of the
simpler organic molecules as passing through a series of
changes, gradually increasing in complexity. There will
be formed substances containing nitrogen in addition to
carbon, hydrogen, and oxygen. Others will contain also
sulfur and phosphorus, and the various processes may
be thought of as culminating in protoplasm. Protoplasm
is the living matter in plants. It is in the cells, and is
usually semifluid. Starch is not living matter. The
complex process of building up the protoplasm is called
assimilation.
Respiration. — Plants need oxygen for respiration, as
animals do. We have seen that plants need the carbon
dioxid of the air. To most plants the nitrogen of the air
is inert, and serves only to dilute the other elements ; but
the oxyge7t is necessary for all life. We know that all
animals need this oxygen in order to breathe or respire.
In fact, they have become accustomed to it in just the
proportions found in the air; and this is now best for
them. When animals breathe the air once, they make it
foul, because they use some of the oxygen and give off
carbon dioxid. Likewise, all living parts of the plant must
have a constant supply of oxygen. Roots also need it, for
they respire. Air goes in and out of the soil by diffusion,
and as the soil is heated and cooled, causing the air to
expand and contract.
The oxygen passes into the air-spaces and is absorbed
by the moist cell membranes. In the living cells it makes
possible the formation of simpler compounds by which
energy is released. This energy enables the plant to
98 BEGINNERS' BOTANY
work and grow, and the final products of this action are
carbon dioxid and water. As a result of the use of this
oxygen by night and by day, plants give off carbon dioxid.
Plants respire ; bnt since they are stationary, and more or
less inactive, they do not need as mnch oxygen as animals,
and they do not give off so much carbon dioxid. A few plants
in a sleeping room need not disturb one more than a family
of mice. It should be noted, however, that germinating
seeds respire vigorously, hence they consume much oxy-
gen ; and opening buds and flowers are likewise active.
Transpiration. — Much more water is absorbed by the
roots than is used in growth, and this surplus water passes
from the leaves into tlie atmosphere by an evaporation process
known as transpiration. Transpiration takes place more
abundantly from the under surfaces of leaves, and through
the poVes or stomates. A sunflower plant of the height
of a man, during an active period of growth, gives off a
quart of water per day. A large oak tree may transpire
150 gallons per day during the summer. For every ounce
of dry matter produced, it is estimated that 15 to 25 pounds
of water usually passes through the plant.
When the roots fail to supply to the plant sufficient water
to equalize that transpired by the leaves, the plant wilts.
Transpiration from the leaves and delicate shoots is in-
creased by all of the conditions which increase evapora-
tion, such as higher temperature, dry air, or wind. The
stomata open and close, tending to regulate transpiration
as the varying conditions of the atmosphere affect the
moisture content of the plant. However, in periods of
drought or of very hot weather, and especially during a
hot wind, the closing of these stomates cannot sufficiently
prevent evaporation. The roots may be very active and
yet fail to absorb sufficient moisture to equalize that given
LEAVES — FUNCTION OR WORK 99
off by the leaves. The plant shows the effect (how ?).
On a hot dry day, note how the leaves of corn " roll " tow-
ards afternoon. Note how fresh and vigorous the same
leaves appear early the following morning. Any injury to
the roots, such as a bruise, or exposure to heat, drought, or
cold may cause the plant to wilt.
Water is forced up by root pressure or sap pressure.
(Exercise 99.) Some of the dew on the grass in the morn-
ing may be the water forced up by the roots ; some of it is
the condensed vapor of the air.
The wilting of a plant is dite to the loss of water from
the cells. The cell walls are soft, and collapse. A toy
balloon will not stand alone until it is inflated with air
or liquid. In the woody parts of the plant the cell walls
may be stiff enough to support themselves, even though
the cell is empty. Measure the contraction due to wilt-
ing and drying by tracing a fresh leaf on page of note-
book, and then tracing the same leaf after it has been
dried between papers. The softer the leaf, the greater
will be the contraction.
Storage. — We have said that starch may be stored in
twigs to be used the following year. The very early flowers
on fruit trees, especially those that come before the leaves,
and those that come from bulbs, as crocuses and tulips,
are supported by the starch or other food that was organ-
ized the year before. Some plants have very special stor-
age reservoirs, as the potato, in this case being a thickened
stem although growing underground. (Why a thickened
stem.' p. 84.) It is well to make the starch test on winter
twigs and on all kinds of thickened parts, as tubers and bulbs.
Carnivorous Plants. — Certain plants capture insects and
other very small animals and utilize them to some extent
as food. Such are the sundew, that has on the leaves
lOO
BEGINNERS' BOTANY
sticky hairs that close over the insect ; the Venus's flytrap
of the Southern states, in which the halves of the leaves
close over the prey like the jaws
of a steel trap ; and the various
kinds of pitcher plants that col-
lect insects and other organic
matter in deep, water-iilled, flask-
like leaf pouches (Fig. 1 19).
The sundew and Venus's fly-
trap are sensitive to contact.
OtheK plants are sensitive to the
touch without being insectivo-
rous. The common cultivated
sensitive plant is an example.
This is readily grown from seeds
(sold by seedsmen) in a warm
place. Related wild plants in
the south are sensitive. The
utility of this sensitiveness is not understood.
Parts that Simulate Leaves. — We have learned that
leaves are endlessly modified to suit the conditions in which
the plant is placed. The most marked modifications are in
adaptation to light. On the other hand, other organs often
pcrfor'm the functions of leaves. Green shoots function as
leaves. These shoots may look like leaves, in which case
they are called cladophylla. The foliage of common
asparagus is made up of fine branches : the real morpho-
logical leaves are the minute dry functionless scales at the
bases of these branchlets. (What reason is there for calling
them leaves.?) The broad " leaves" of the florist's smilax
are cladophylla : where are the leaves on this plant .'' In
most of the cacti, the entire plant body performs the func-
tions of leaves until the parts become cork-bound,
Fig. 119. — The Common
Pitcher Plant {Sarracenia
purpurea) of the North, show-
ing the tubular leaves and the
odd, long-stalked flowers.
LEAVES— FUNCTION OR WORK
lOI
Leaves are sometimes modified to perform other functions
than the vital processes: they may be tendrils, as the
terminal leaflets of pea and sweet pea; or spines, as in
barberry. Not all spines and thorns, however, represent
modiiied leaves: some of them (as of hawthorns, osage
orange, honey locust) are branches.
Suggestions. — To test for chlorophyll. 84. Purchase about a
gill of wood alcohol. Secure a leaf of geranium, clover, or other
plant that has been exposed to sunlight for a few hours, and, after
dipping it for a minute in boiling water, put it in a white cup with
sufficient alcohol to cover. Place the cup in a shallow pan of
hot water on the stove where it is not hot enough for the alcohol
to take fire. After a time tRe chlorophyll is dissolved by the
alcohol, which has become an intense green. Save this leaf for
the starch experiment (Exercise 85). Without chlorophyll, the
plant cannot appropriate the carbon dioxid of the air. Starch
and photosynthesis. 85. Starch is present in the green leaves
which have been exposed to sunlight ; but in the dark no starch
can be formed from carbon dioxid. Apply iodine to the leaf from
which the chlorophyll was dissolved in the previous experiment.
Note that the leaf is colored purplish brown throughout. The leaf
contains starch. 86. Se-
cure a leaf from a plant
which has been in the dark-
ness for about two days.
Dissolve the chlorophyll as
before, and attempt to stain
this leaf with iodine. No
purplish brown color is pro-
duced. This shows that
the starch manufactured in
the leaf may be entirely
removed during darkness.
87. Secure a plant which
has been kept in darkness
for twenty-four hours or
more. Split a small cork
and pin the two halves on opposite sides of one of the leaves, as
shown in Fig. 120. Place the plant in the sunlight again. After
a morning of bright sunshine dissolve the chlorophyll in this leaf
with alcohol ; then stain the leaf with the iodine. Notice that the
leaf is stained deeply except where the cork was ; there sunlight and
carbon dioxid were excluded, Fig. 121. There is no starch in the
Fig. 120. — Exclud-
ing Light and
CO2 FROM Part
OF A Leaf.
Fig. 121. — The
Result.
102
BEGINNERS' BOTANY
covered area. 88. Plants or parts of plants that have developed
no chlorophyll can form no starch. Secure a variegated leaf of
coleus, ribbon grass, geranium, or of any plant showing both white
and green areas. On a day of bright sunshine, test one of these
leaves by the alcohol and iodine method for the presence of starch.
Observe that the parts devoid of green color have formed no
starch. However, after starch has once been formed in the leaves.
it may be
to be again
the living
changed into soluble substances and removed,
converted into starch in certain other parts of
tissues. To test the giving off of oxygen by day.
89. Make the experiment illus-
trated in Fig. 12 2. Under a fun-
nel in a deep glass jar containing
fresh spring or stream water place
fresh pieces of the common
waterweed elodea (or anacharis).
Have the funnel considerably
smaller than the vessel, and sup-
|:||"||j|||jj Ij I ' IJII port the funnel well up from the
bottom so that the plant can more
readily get all of the carbon dioxid
available in the water. Why would
boiled water be undesirable in this
experiment? For a home-made
glass funnel, crack the bottom off
a narrow-necked bottle by press-
ing a red-hot poker or iron rod
against it and leading the crack
around the bottle. Invert a test-
tube over the stem of the fun-
nel. In sunlight bubbles of
oxygen will arise and collect in
the test-tube. If a sufficient
quantity of oxygen has collected,
a lighted taper inserted in the
tube will glow with a brighter flame, showing the presence of
oxygen in greater quantity than in the air. Shade the vessel.
Are bubbles given off? For many reasons it is impracticable
to continue this experiment longer than a few hours. 90. A
simpler experiment may be made if one of the waterweeds
Cabomba (water-lily family) is available. Tie a lot of branches
together so that the basal ends shall make a small bundle. Place
these in a large vessel of spring water, and insert a test-tube of
water as before over the bundle. The bubbles will arise from the
cut surfaces. Observe the bubbles on pond scum and water-
weeds on a bright day. To illustrate the results of respiration
Fig. 122.
-To SHOW 'I'HE Escape
or Oxygen.
LEAVES — FUNCTION OR WORK
103
Fig. 123. — To ILLUS-
TRATE A Product
OP Respiration.
Fig. 124. — KKsi'iRA-
tjon of Thick
Roots.
(CO2). 91. In a jar of germinating seeds (Fig. 123) place carefully
a small dish of liraewater and cover tightly. Put a similar dish in
another jar of about the
same air space. After a few
hours compare the cloudi-
ness or precipitate in the
two vessels of liraewater.
92. Or, place a growing
plant in a deep covered
jar away from the light,
and after a few hours in-
sert a hghted candle or
splinter. 93. Or, perform
a similar experiment with
fresh roots of beets or
turnips (Fig. 124) from
which the leaves are mostly
removed. In this case,
the jar need not be kept dark ; why ?
To test transpiration. 94. Cut a succulent
shoot of any plant, thrust the end of it through a hole in a cork,
and stand it in a small bottle of water. Invert over this a fruit
jar, and observe
that a mist soon
accumulates on
the inside of the
glass. In time
drops of water
form. 95. The ex-
periment may be
varied as shown in
Fig. 125. 96. Or,
invert the fruit
jar over an entire
plant, as shown in
Fig. 126, taking
care to cover the
soil with oiled
paper or rubber
cloth to prevent
evaporation from
the soil. 97. The
test may also be
made by placing
the pot, properly
protected, on bal- Fig. 125. —To illustrate Transpiration.
104
BEGLVNERS' BOTANY
Fig
ances, and the loss of weight will be noticed (Fig. 127). 98. Cut
a winter twig, seal the severed end with wax, and allow the twig
to he several days ; it shrivels. There must be some upward
movement of water even in winter, else plants would shrivel
and die. 99. To illustrate sap pressure.
The upward movement of sap water often
takes place under considerable force. The
cause of this force, known as root pressure,
is not well understood. The pressure varies
with different plants and under different
conditions. To illustrate :
cut off a strong-growing Hj-^J
small plant near '
the ground. By
means of a bit of
rubber tube attach
a glass tube with
a bore of approxi-
mately the diame-
ter of the stem.
Pour in a little
water. Observe
the rise of the
water due to the
pressure from be-
low (Fig 128). Some plants yield a large
amount of water under a pressure sufficient
to raise a column several feet ; others force
out httle, but under consider- \
able pressure (less easily de-
monstrated). The vital pro-
'f^^-^^""''^^ cesses {i.e., the life processes).
100. The pupil
having studied
roots, stems,
and leaves,
should now
be able to de-
scribe the main
vital functions
of plants : what
is the root func-
tion? stem function? leaf function? 101. What
is meant by the " sap "? 102. Where and how
does the plant secure its water? oxygen? car-
bon? hydrogen? nitrogen? sulfur? potassium?
126. — To ILLUSTRATE
Transpiration.
Loss OF Water.
Fig. 128. — To SHOW
Sap Pressure.
LEAVES— FUNCTION OR WORK
los
calcium? iron? phosphorus? 103. Where is all the starch in the
world made? What does a starch-factory establishment do?
Where are the real starch factories ? 104. In
what part of the twenty-four hours do
plants grow most rapidly in length? When
is food formed and stored most rapidly?
105. Why does corn or cotton turn yellow
in a long rainy spell? 106. If stubble,
corn stalks, or cotton stalks are burned
in the field, is as much plant-food returned
to the soil as when they are plowed
under? 107. What process of plants is
roughly analogous to perspiration of ani-
mals? 108. What part of the organic
world uses raw mineral for food ? 109. Why
is earth banked over celery to blanch it?
110. Is the amount of water transpired
equal to the amount absorbed? 111. Give
some reasons why plants very close to a
house may not thrive or may even die.
112. Why are fruit-trees pruned or thinned
out as in Fig. 129? Proper balance be-
tween top and root. 113. We have learned
that the leaf parts and the root parts work
together. They may be said to balance
each other in activities, the root supplying pj^ 1,0 _ p^^ apple
the top and the top supplying the root Tree, with suggestions
(how?). If half the roots were cut from as to pruning when it
a tree, we should expect to reduce the top is set in the orchard. At
also, particularly if the tree is being trans- ^^ *' =''°™ * P™"^'^
planted. How would you prune a tree or °^'
bush that is being transplanted? Fig. 130 may be suggestive.
Fig. 129. — Before and after Pruning.
CHAPTER XIV
DEPENDENT PLANTS
Thus far we have spoken of plants with roots and
foliage and that depend on themselves. They collect the
raw materials and make them over into assimilable food.
They are independent. Plants without green foliage can-
not make food; they
must have it made for
them or they die.
They are dependent. A
sprout from a potato
tuber in a dark cellar
cannot collect and elab-
orate carbon dioxid. It
lives on the food stored
in the tuber.
All plants with natu-
rally white or blanched
parts are dependent. Their leaves do not develop. They
live on organic matter — that which has been made by a
plant or elaborated by an animal. The dodder, Indian
pipe, beech drop, coral root among flower-bearing plants,
also mushrooms and other fungi (Figs. 131, 132) are exam-
ples. The dodder is common in swales, being conspicuous
late in the season from its thread-like yellow or orange
stems spreading over the herbage of other plants. One
kind attacks alfalfa and is a bad pest. The seeds germi-
nate in the spring, but as soon as the twining stem at-
106
Fig. 131. — A Mushroom, example of a sapro-
phytic plant. This is the edible cultivated
mushroom.
DEPENDENT PLANTS
107
taches itself to another plant, the dod-
der dies away at the base and becomes
wholly dependent. It produces flowers
in clusters and seeds itself freely
(Fig. 133).
Parasites and Saprophytes. — A plant
that is dependent on a living plant or
animal is a parasite, and the plant or
animal on which it lives is the host.
The dodder is a true parasite ; so are
the rusts, mildews, and other fungi that
attack leaves and shoots and injure
them.
The threads of a parasitic fungus
usually creep through the intercellular
spaces in the leaf or stem and send
suckers (or haustoria) into the cells
(Fig. 132). The threads (or the hy-
phae) clog the air-spaces of the leaf
and often plug the stomates,
and they also appropriate and
disorganize the cell fluids ; thus
they injure or kill their host. The mass of hyphae
of a fungus is called mycelium. Some of the
hyphae finally grow out of the leaf and produce
spores or reproductive cells that an-
swer the purpose of seeds in distrib-
uting the plant {b. Fig. 132).
A plant that lives on dead or de-
caying matter is a saprophyte. Mush-
rooms (Fig. 131) are examples; they
live on the decaying matter in the
soil. Mold on bread and cheese is an
d o
Fig. 132. — A Pa rasitic
Fungus, magnified.
The mycelium, or
vegetative part, is
shown by the dotted-
shaded parts ramify-
ing in the leaf tissue.
The rounded haus-
toria projecting into
the cells are also
shown. The long
fruiting parts of the
fungus hang from the
under surface of the
leaf.
io8
BEGINNERS' BOTANY
example. Lay a piece of moist bread on a plate and
invert a tumbler over it. In a few days it will be moldy.
The spores were in the air, or perhaps they had already
fallen on the bread but had not had opportunity to grow.
Most green plants are unable to make any direct use of
the humus or vegetable mold in the soil, for they are not
saprophytic. The shelf-
fungi (Fig. 134) are sap-
rophytes. They are com-
mon on logs and trees.
Some of them are perhaps
partially parasitic, extend-
ing the mycelium into the
wood of the living tree
and causing it to become
black-hearted (Fig. 1 34).
Some parasites spring
from the ground, as other
plants do, but they are
parasitic on the roots of
their hosts. Sonie para-
sites may be partially
parasitic and partially
saprophytic. Many (per-
haps most) of these
ground saprophytes are
aided in securing their
food by soil fungi, which spread their delicate threads over
the root-like branches of the plant and act as intermedi-
aries between the food and the saprophyte. These fungus-
covered roots are known as my corrhizas (meaning "fungus
root"). Mycorrhizas are not peculiar to saprophytes.
They are found on many wholly independent plants, as,
Fig. 134. — Tinder Fungus (Polyporus
igniarius) on beech log. The external
part of the fungus is shown below ; the
heart-rot injury above.
DEPENDENT PLANTS
109
for example, the heaths, oaks, apples, and pines. It is
probable that the fungous threads perform some of the
offices of root-hairs to the
host. On the other hand,
the fungus obtains some
nourishment from the
host. The association
seems to be mutual.
Saprophytes break
down or decompose or-
ganic substances. Chief
of these saprophytes are
many microscopic organ-
FiG. 135. — Bacteria of Several
Forms, much magnified.
isms known as bacteria (Fig. 135). These innumerable
organisms are immersed in water or in dead animals and
plants, and in all manner of
moist organic products. By
breaking down organic
combinations, they produce
decay. Largely through
their agency, and that of
many true but microscopic
fungi, all things pass into
soil and gas. Thus are the
bodies of plants and animals
removed and the continuing
round of life is maintained.
Some parasites are green-
leaved. Such is the mistle-
toe (Fig. 136). They anchor
themselves on the host and
absorb its juices, but they
Fig. 136. — American Mistletoe ' ■'
GROWING ON A WALNUT BRANCH. also appropriate and use
no BEGINNERS' BOTANY
the carbon dioxid of the air. In some small groups of
bacteria a process of organic synthesis has been shown to
take place.
Epiphytes. — To be distinguished from the dependent
plants are those that grow on other plants without taking
food from them. These are green-leaved plants whose
roots burrow in the bark of the host plant and perhaps
derive some food from it, but which subsist chiefly on
materials that they secure from air dust, rain water, and
the air. These plants are epiphytes (meaning " upon
plants") or air plants.
Epiphytes abound in the tropics. Certain orchids are
among the best known examples (Fig. 37). The Spanish
moss or tillandsia of the South is another. Mosses and
lichens that grow on trees and fences may also be called
epiphytes. In the struggle for existence, the plants
probably have been driven to these special places in which
to find opportunity to grow. Plants grow where they
must, not where they will.
Suggestions. — 114. Is a puffball a plant ? Why do you
think so? 115. Are mushrooms ever cultivated, and where
and how? 116. In what locations are mushrooms and toadstools
usually found? (There is really no distinction between mush-
rooms and toadstools. They are all mushrooms.) 117. What
kinds of mildew, blight, and rust do you know? 118. How do
farmers overcome potato blight? Apple scab? Or any other
fungous "plant disease"? 119. How do these things injure
plants? 120. What is a plant disease? 121. The pupil should
know that every spot or injury on a leaf or stem is caused by
something, — as an insect, a fungus, wind, hail, drought, or other
agency. How many uninjured or perfect leaves are there on
the plant growing nearest the schoolhouse steps? 122. Give
formula for Bordeaux mixture and tell how and for what it is used.
CHAPTER XV
WINTER AND DORMANT BUDS
A bud is a growing point, terminating an axis either long
or short, or being the starting point of an axis. All
branches spring from buds. In the growing season the
bud is active ; later in the season it ceases to increase the
axis in length, and as winter approaches the growing
point becomes more or less thickened and covered by pro-
tecting scales, in preparation for the long resting season.
This resting, dormant, or winter body is what is commonly
spoken of as a "bud." A winter bud may be defined
as an inactive covered growing point, waiting for spring.
Structurally, a dormant bud is a shortened axis or branch,
bearing miniature leaves or flowers or both, and protected
by a covering. Cut in two, lengthwise, a
bud of the horse-chestnut or other plant
that has large buds. With a pin separate
the tiny leaves. Count them.
Examine the big bud of the
rhubarb as it lies under the
ground in late winter or early
spring ; or the crown buds of
asparagus, hepatica, or other
early spring plants. Dis-
sect large buds of the apple
and pear (Figs. 137, 138).
The bud is protected by firm and dry scales. These
scales are modified leaves. The scales fit close. Often
Fig. 137. — Bud
OF Apricot,
showing the
miniature
leaves.
Fig. 138.— Bud of
Pear, showing
both leaves and
fl o w e r s. The
latter are the lit-
tle knobs in the
center.
1 12
BEGINNERS' BOTANY
the bud is protected by varnish (see horse-chestnut and
the balsam poplars). Most winter buds are more or less
woolly. Examine them under a lens. As we might
expect, bud coverings are most prominent in cold and dry
climates. Sprinkle water on velvet or flannel, and note
the result and give a reason.
All winter buds give rise to branches, not to leaves alone;
that is, the leaves are borne on the lengthening axis.
Sometimes the axis, or branch, remains very short, — so
short that it may not be noticed. Sometimes it grows
several feet long.
Whether the branch grows large or not depends on the
chance it has, — position on the plant, soil, rainfall, and
many other factors. The new shoot is the
unfolding and enlarging of the tiny axis
and leaves that we saw in the bud. If the
conditions are congenial, the shoot may
form more leaves than were tucked away
in the bud. The length of the shoot usu-
ally depends more on the lengths of the
internodes than on the number of leaves.
Where Buds are. — Buds are borne in the
axils of the leaves, — in the acute angle
that the leaf makes with the stem. When
the leaf is growing in the summer, a bud
is forming above it. When the leaf falls,
the bud remains, and a scar marks the
place of the leaf. Fig. 139 shows the large leaf-scars of
ailanthus. Observe those on the horse-chestnut, maple,
apple, pear, basswood, or any other tree or bush.
Sometimes two or more buds are borne in one axil ; the
extra ones are accessory or supernumerary buds. Observe
them in the Tartarian honeysuckle (common in yards).
Fig. 139. —Leaf-
scars. — Ailanthus
WINTER AND DORMANT BUDS
113
walnut, butternut, red maple, honey locust, and sometimes
in the apricot and peach.
If the bud is at the end of a shoot, however short the
shoot, it is called a terminal bud. It continues the growth
of the axis in a direct line. Very often
three or more buds are clustered at the tip
(Fig. 140); and in this case there may be
more buds than leaf scars. Only one of
them, however, is strictly terminal.
A bud in the axil of a leaf is an axillary
or lateral bud. Note that there is normally
at least one bud in the axil of every leaf on
a tree or shrub in late summer and fall. The
axillary buds, if they grow, are the starting
points of new shoots the following season. If
a leaf is pulled off early in summer, what
will become of the young' bud in its axil.-'
Try this.
Bulbs and cabbage heads may be likened to buds ; that is,
they are condensed stems, with scales or modified leaves
densely overlapping
and forming a
rounded body (Fig.
141). They differ
from true buds, how-
ever, in the fact
that they are con-
densations of whole
main stems rather
than embryo stems
borne in the axils of
leaves. But bulblets (as of tiger Hly) may be scarcely dis-
tinguishable from buds on the one hand and from bulbs
Fig. 140. — Ter-
minal Bud
between two
OTHER Buds.
— Currant.
Fig. 141. — a Gigantic Bud. — Cabbage.
114
BEGINNERS' BOTANY
on the other. Cut a cabbage head in two, lengthwise,
and see what it is like.
The buds that appear on roots are unusual or abnormal,
— they occur only occasionally and in no definite order.
Buds appearing in unusual places on any part of the plant
are called adventitious buds. Such usually are the buds
that arise when a large limb is cut off, and
from which suckers
or water sprouts
arise.
How Buds Open.
— WJicn the bud
sivells, the scales
are pushed apart,
the little axis elon-
gates and pushes
out. In most plants
the outside scales
fall very soon, leaving a little ring of scars.
With terminal buds, this ring marks the end
of the year's growth: how.?
Notice peach, apple, plum,
willow, and other plants. In
some others, all the scales grow for a time,
as in the pear (Figs. 142, 143, 144). In
other plants the inner bud scales become
green and almost leaf-like. See the maple
and hickory.
Sometimes Flowers come out of the
Buds. — Leaves may or may not accompany
the flowers, We saw the embryo flowers in
Fig. 138. The bud is shown again in Fig.
142. In Fig. 143 it is opening. In Fig. 145
m
w
If
1
y \
Fig. 143. — The
Fig. 142. —
OPENING OF
Fruit-bud
THE Pear
OF Pear.
Fruit-bud.
Fig. 144. — Open-
ing Pear
Leaf-bud.
Fig. 145. — Open-
ing OF THE
Pear-bud.
WINTER AND DORMANT BUDS
115
it is more advanced, and the woolly unformed flowers are
appearing. In Fig. 146 the growth is more advanced.
Fig. 146. — A SIN-
GLE Flower
IN THE Pear
CLUSTER, as
seen at 7 a.m.
on the day of
its opening. At
lo o'clock it
will be fully ex-
panded.
Fig. 147. — THE
OPENING OF
THE Flower-
bud OF
Apricot.
Fig. 148. — Apricot
Flower-bud, enlarged.
leaf-buds.
Buds that contain or
produce only leaves are
Those which contain only flowers are flower
buds or fruit-buds. The latter occur on
peach, almond, apricot, and many very
early spring-flowering plants. The
single flower is emerging from the
apricot bud in Fig. 147. A longi-
tudinal section of this bud, enlarged, is
shown in Fig. 148. Those that contain
both leaves and flowers are mixed buds,
as in pear, apple, and most late spring-
flowering plants.
Fruit buds are usually thicker or
stouter than leaf-buds. They are borne
in different positions on different plants.
In some plants (apple, pear) they are
on the ends of short branches or spurs;
in others (peach, red maple) they are
along the sides of the last year's
° •' Fig. 149. — Fruit-buds
growths. In Fig. 149 are shown and leaf-buds of pear.
Ii6
BEGINNERS' BOTANY
three fruit-buds and one leaf-bud on E, and leaf-buds on
A. See also Figs. 150, 151, 152, 153, and explain.
Fig. 150. — Fruit-euds of Apple
ON Spurs : a dormant bud at
the top.
Fig. 151, — Clus-
ter OF Fruit-
buds OF SWEET
Cherry, with
one pointed
leaf-bud in cen-
ter.
Fig. 152. — Two
Fruit-buds
OF Peach
with a leaf-
bud between.
Fig. 153. — Opening of Leaf-buds and Flower-buds of Apple.
"The burst of spring" means in large part the opening of
the buds. Everything was made ready the fall before. The
embryo shoots and flowers were tucked away, and the food
was stored. The warm rain falls, and the shutters open
and the sleepers wake : the frogs peep and the birds come.
Arrangement of Buds. — We have found that leaves are
usually arranged in a definite order ; buds are borne in the
axils of leaves : therefore bjids must exhibit phyllotaxy.
WINTER AND DORMANT BUDS
117
Moreover, branches grow from buds: branches, therefore,
should show a definite arrangement; usually, however, they
do not show this arrangement because not all the buds grow
and not all the branches live. (See Chaps. II and III.)
It is apparent, however, that the mode of arrangement of
buds determines to some extent the form of the tree: com-
pare bud arrangement in pine or fir with that in maple or
apple.
Fig. 154. — Oak Spray. How are the leaves borne with reference to
the annual growths ?
The uppermost buds on any twig, if they are well
matured, are usually the larger and stronger and they are
the most likely to grow the next spring ; therefore, branches
tend to be arranged in tiers (particularly well marked in
spruces and firs). See Fig. 1 54 and explain it.
Winter Buds show what has been the Effect of Sunlight. —
Buds are borne in the axils of the leaves, and the size or
vigor of the leaf determines to a large extent the size of the
bud. Notice that, in most instances, the largest buds are
nearest the tip (Fig. 157). If the largest ones are not
near the tip, there is some special reason for it. Can you
state it .' Examine the shoots on trees and bushes.
Il8 BEGINNERS' BOTANY
Suggestions. — Some of the best of all observation lessons are
those made on dormant twigs. There are many things to be
learned, the eyes are trained, and the specimens are everywhere
accessible. 123. At whatever time of year the pupil takes up the
study of branches, he should look for three things : the ages of
the various parts, the relative positions of the buds and leaves, the
different sizes of similar or comparable buds. If it is late in
spring or early in summer, he should watch the development of
the buds in the axils, and he should determine whether the
strength or size of the bud is in any way related to the size and
vigor of the subtending (or supporting) leaf. The sizes of buds
should also be noted on leafless twigs, and the sizes of the former
leaves may be inferred from the size of the leaf-scar below the
bud. The pupil should keep in mind the fact of the struggle
for food and hght, and its effects on the developing buds.
124. The bud and the branch. A twig cut from an apple tree
in early spring is shown in Fig. 155. The most hasty obser-
vation shows that it has various parts, or members. It seems to
be divided at the point / into two parts. It is evident that the
part from/ to h grew last year, and that the part below/ grew
two years ago. The buds on the two parts are very unlike,
and these differences challenge investigation. — In order to under-
stand this seemingly hfeless twig, it will be necessary to see it as
it looked late last summer (and this condition is shown in Fig.
156). The part from / to /«, — which has just completed its
growth, — is seen to have its leaves growing singly. In every axil
(or angle which the leaf makes when it joins the shoot) is a bud.
The leaf starts first, and as the season advances the bud forms in
its axil. When the leaves have fallen, at the approach of winter,
the buds remain, as seen in Fig. 155. Every bud on the last
year's growth of a winter twig, therefore, marks the position
occupied by a leaf when the shoot was growing. — The part below
/, in Fig. 156, shows a wholly different arrangement. The leaves
are two or more together (aaaa), and there are buds without
leaves (bbbb). A year ago this part looked like the present shoot
from / to h, — that is, the leaves were single, with a bud in the
axil of each. It is now seen that some of these bud-hke parts
are longer than others, and that the longest ones are those which
have leaves. It must be because of the leaves that they have
increased in length. The body c has lost its leaves through some
accident, and its growth has ceased. In other words, the parts
at aaaa are like the shoot //;, except that they are shorter, and
they are of the same age. One grew from the end or terminal
bud of the main branch, and the others from the side or lateral
buds. Parts or bodies that bear leaves are, therefore, branches.
— The buds at bbib have no leaves, and they remain the same
WINTER AND DORMANT BUDS
119
size that they were a year ago. They are dormant. The only way
for a mature bud to grow is by making leaves for itself, for a leaf
Fig. 155. — An
Apple Twig.
Fig. 156. — Same twig before leaves fell.
will never stand below it again. The twig, therefore, has buds of
two ages, — those at bbbb are two seasons old, and those on the
120 BEGINNERS' BOTANY
tips, of all the branches {aaaa, h), and in the axil of every leaf,
are one season old. It is only the terminal buds that are not
axillary. When the bud begins to grow and to put forth leaves,
it gives rise to a branch, wliich, in its turn, bears buds. — It will
now be interesting to determine why certain buds gave rise to
branches and why others remained dormant. The strongest
shoot or branch of the year is the terminal one {fh). The
next in strength is the uppermost lateral one, and the weakest
shoot is at the base of the twig. The dormant buds are on the
under side (for the twig grew in a horizontal position) . All this
suggests that those buds grew which had the best chance, — the
most sunlight and room. There were too many buds for the space,
and in the struggle for existence those that had the best oppor-
tunities made the largest growths. This struggle for existence
began a year ago, however, when the buds on the shoot below/
were forming in the axils of the leaves, for the buds near the tip
of the shoot grew larger and stronger than those near its base.
The growth of one year, therefore, is very largely determined by
the conditions under which the buds were formed the previous
year. Other bud characters. 125. It is easy to see the swelling
of the buds in a room in winter. Secure branches of trees and
shrubs, two to three feet long, and stand them in vases or jars,
as you would flowers. Renew the water frequently and cut off
the lower ends of the shoots occasionally. In a week or two the
buds will begin to swell. Of red maple, peach, apricot, and other
very early-flowering things, flowers may be obtained in ten to
twenty days. 126. The shape, size, and color of the winter buds
are different in every kind of plant. By the buds alone botanists
are often able to distinguish the kinds of plants. Even such
similar plants as the different kinds of willows have good bud
characters. 127. Distinguish and draw fruit-buds of apple, pear,
peach, plum, and other trees. If different kinds of maples grow
in the vicinity, secure twigs of the red or swamp maple, and the
soft or silver maple, and compare the buds with those of the sugar
maple and Norway maple : What do you learn?
Fig. 157. — Buds of the Hickory.
CHAPTER XVI
BUD PROPAGATION
We have learned (in Chap. VI) that plants propagate
by means of seeds. They also propagate by means of bud
parts, — as rootstocks {rhizomes), roots, runners, layers, bulbs.
The pupil should determine how any plant in which he is
interested naturally propagates itself (or spreads its kind).
Determine this for raspberry, blackberry, strawberry, June-
grass or other grass, nut-grass, water lily, May apple or
mandrake, burdock, Irish potato, sweet potato, buckwheat,
cotton, pea, corn, sugar-cane, wheat, rice.
Plants may be artificially propagated by similar means,
as by layers, cuttings, and grafts. The last two we may
discuss here.
Cuttings in General. — A bit of a plant stuck into the
ground stands a chance of growing ; and this bit is a cutting.
Plants have preferences, however, as to the kind of a bit
which shall be used, but there is no way of telling what this
preference is except by trying. In some instances this prefer-
ence has not been discovered, and we say that the plant
cannot be propagated by cuttings.
Most plants prefer that the cutting be made of the soft
or growing parts (called "wood" by gardeners), of which
the "slips" of geranium and coleus are examples. Others
grow equally well from cuttings of the hard or mature parts
or wood, as currant and grape; and in some instances this
mature wood may be of roots, as in the blackberry. In
some cases cuttings are made of tubers, as in the Irish
122
BEGINNERS' BOTANY
potato (Fig. 60). Pupils sliould malce cuttings now and
then. If they can do nothing more, they can make cut-
tings of potato, as the farmer does; and they can plant
them in a box in the window.
The Softwood Cutting. — The softwood cutting is made
from tissue that is still growing, or at least from that
which is not dormant. It comprises one or two joints, with
Fig. 158. — Geranium Cutting.
Fig. 159. —Rose Cutting.
a leaf attached (Figs. 158, 159). It must not be allowed
to wilt. Therefore, it must be protected from direct sun-
light and dry air until it is well established ; and if it has
many leaves, some of them should be removed, or at least cut
in two, in order to reduce the evaporating surface. The
soil should be uniformly moist. The pictures show the
depth to which the cuttings are planted.
For most plants, the proper age or maturity of wood for
the making of cuttings may be determined by giving the
twig a quick bend: if it snaps and hangs by the bark, it is in
proper condition; if it bends witliout breaking, it is too
young and soft or too old ; if it splinters, it is too old and
woody. The tips of strong upright shoots usually make
the best cuttings. Preferably, each cutting should have a
joint or node near its base; and if the internodes are very
short it may comprise two or three joints.
BUD PROPAGATION
123
Fig. 160. — Cutting-box.
The stem of the cutting is inserted one third or more its
length in clean sand or gravel, and the eartli is pressed firmly
about it. A newspaper may be laid over the bed to ex-
clude the light — if the sun strikes it — and to prevent too
rapid evaporation. The soil should be moist clear through,
not on top only.
Loose sandy or gravelly soil is used. Sand used by
masons is good material in which to start most cuttings; or
fine gravel — sifted of most
of its earthy matter — may
be used. Soils are avoided
which contain much decay-
ing organic matter, for these
soils are breeding places of
fungi, which attack the soft
cutting and cause it to " damp
off," or to die at or near the surface of the ground. If the
cuttings are to be grown in a window, put three or four
inches of the earth in a shallow box or a pan. A soap
box cut in two lengthwise, so that it makes a box four or
five inches deep — as a gardener's flat — is excellent (Fig.
160). Cuttings of common plants, as geranium, coleus,
fuchsia, carnation, are kept at a
living-room temperature. As long
as the cuttings look bright and
green, they are in good condition.
It may be a month before roots
form. When roots have formed,
the plants begin to make new
leaves at the tip. Then they may
be transplanted into other boxes
or into pots. The verbena in Fig. 161 is just ready for
transplanting.
Fig. 161. — Verbena Cutting
ready for transplanting.
124
BEGINNERS' BOTANY
f
Eh
V^v -°25SiiftJ8^^B
a'-^BI*-' vfir ifT^^^^^^^M
m!^^^ ^^^^^Hm
Fig. 162. — Old Geranium Plant
cut eack to make it throw out
Shoots from which Cuttings
can ee made.
dow plants are those which
old. Tlie geranium
and fuchsia cut-
tings which are
made in January,
February, or March
will give compact
blooming plants for
the next winter ;
and tJiereafter new
ones should take
their places (Fig.
163).
The Hardwood
Cutting. — Best re-
sults with cuttings
It is not always easy to
find growing shoots from •
which to make the cut-
tings. The best practice,
in that case, is to cut back
an old plant, then keep it
warm and zvell watered,
and thereby force it to throw
out new shoots. The old
geranium plant from the
window garden, or the one
taken up from the lawn
bed, may be treated this
way (see Fig. 162). The
best plants of geranium
and coleus and most win-
are not more than one year
of mature wood are
Fig. 163. — Early Winter Geranium, from
a spring cutting.
BUD PROPAGATION
125
secured when the cuttings are made in the fall and then
buried until spring in sand in the cellar. These cuttings
are usually six to ten inches long. They are not idle while
they rest. The lower end calluses or heals, and the roots
form more readily when the cutting is planted in the
spring. But if the proper season has passed, take cuttings
at any time in winter, plant them in a deep
box in the window, and watch. They will
need no shading or special care. Grape,
currant, gooseberry, willow, and poplar
readily take root from the hardwood.
Fig. 164 shows a currant cutting. It has
only one bud above the ground.
The Graft. — When the cutting is inserted
in a plant rather than in the soil, it is a
graft ; and the graft may grow. In this
case the cutting grows fast to the other
•plant, and the two become one. When
the cutting is inserted in a plant, it is no
longer called a cutting, but a cion ; and the
plant in which it is inserted is called the
stock. Fruit trees are grafted in order
that a certain variety or kind may be per-
petuated, as a Baldwin or Ben Davis vari-
ety of apple, Seckel or Bartlett pear, Navel
or St. Michael orange.
Plants have preferences as to the stocks on which they
will grow ; but ive can find out ivhat their choice is only
by making the experiment. The pear grows well on the
quince, but the quince does not thrive on the pear.
The pear grows on some of the hawthorns, but it is an
unwilling subject on the apple. Tomato plants will grow
on potato plants and potato plants on tomato plants.
Fig. 164. — Cur-
rant Cutting.
126 BEGINNERS' BOTANY
When the potato is the root, both tomatoes and potatoes
may be produced, although the crop will be very small;
when the tomato is the root, neither potatoes nor tornatoes
will be produced. Chestnut will grow on some kinds of
oak. In general, one species or kind is grafted on the
same species, as apple on apple, pear on pear, orange on
orange.
The forming, growing tissue of the stem (on the plants
we have been discussing) is the cambium (Chap. X), lying
on tJie outside of tJie woody cylinder beneath the bark. In
order that union may take place, the cambium of the cion
ajid of the stock must come together. Therefore the cion
is set in the side of the stock. There are many ways of
shaping the cion and of preparing the stock to receive it.
These ways are dictated largely by the relative sizes of
cion and stock, although many of them are matters of
personal preference. The underlying principles are two :
securing close contact between the cambiums of cion and
stock ; covering the wounded surfaces to prevent evapora-
tion and to protect the parts from disease.
On large stocks the commonest form of grafting is the
cleft-graft. The stock is cut off and split ; and in one or
both sides a wedge-shaped cion is firmly inserted. Fig.
165 shows the cion; Fig. 166, the cions set in the stock;
Fig. 167, the stock waxed. It will be seen that the lower
bud — that lying in the wedge — is covered by the wax;
but being nearest the food supply and least exposed to
weather, it is the most likely to grow : it will push through
the wax.
Cleft-grafting is practiced in spring, as growth begins.
The cions are cut previously, when perfectly dorm.ant, and
from the tree which it is desired to propagate. The cions
are kept in sand or moss in the cellar. Limbs of various
BUD PROPAGATION
127
sizes may be cleft-grafted, — from one half inch up to four
inches in diameter ; but a diameter of one to one and one
half inches is the most convenient size. All the leading
or main branches of a tree top may be grafted. If the
remaining parts of the top are gradually cut away and
the cions grow well, the entire top will be changed over to
the new variety.
Fig. 165.—
ClON OF
Apple.
Fig. 166,— The
CiON Inserted.
Fig. 167.— The
Parts Waxed.
Another form of grafting is known as budding. In this
case a single bud is used, and it is slipped underneath the
bark of the stock and securely tied (not waxed) with soft
material, as bass bark, corn shuck, yarn, or raffia (the last
a commercial palm fiber). Budding is performed when the
bark of the stock will slip or peel (so that the bud can be
inserted), and when the bud is mature enough to grow.
Usually budding is performed in late summer or early
fall, when the winter buds are well formed ; or it may be
practiced in spring with buds cut in winter. In ordinary
summer budding (which is the usual mode) the "bud" or
cion forms a union with the stock, and then lies dormant
till the following spring, as if it were still on its own twig.
128
BEGINNERS' BOTANY
Budding is mostly restricted to young trees in the nursery.
In the spring following the budding, the stock is cut off
just above the bud, so that only the shoot from the bud
grows to make the future tree. This prevailing form of
budding (shield-budding) is shown in Fig.
i68.
Suggestions. — 128. Name the plants that the
gardener propagates by means of cuttings.
129. By means of grafts. 130. The cutting-box
may be set in the ■window. If the box does not
receive direct sunlight, it may be covered with a
pane of glass to prevent evaporation. Take care
that the air is not kept too close, else the damping-
off fungi may attack the cuttings, and they will
rot at the surface of the ground. See that the
pane is raised a httle at one end to afford ventila-
tion ; and if the water collects in drops on the
under side of the glass, remove the pane for a
time. 131. Grafting wax is made of beeswax,
resin, and tallow. A good recipe is one part (as
one pound) of rendered tallow, two parts of bees-
wax, four parts of rosin ; melt together in a kettle \
pour the liquid into a pail or tub of water to so-
lidify it ; work with the hands until it has the
color and " grain " of taffy candy, the hands being
greased when necessary. The wax will keep any
length of time. For the httle grafting that any
pupil would do, it is better to buy the wax of a
seedsman. 132. Grafting is hardly to be recom-
mended as a general school diversion, as the mak-
ing of cuttings is ; and the account of it in this
chapter is inserted chiefly to satisfy the general
curiosity on the subject. 133. In Chap. V we had
a definition of a plant generation : what is " one
generation " of a grafted fruit tree, as Le Conte
pear, Baldwin, or Ben Davis apple? 134. The
Elberta peach originated about i88o : what is
Fig i68 — Bud- meant by " originated " ? 135. How is the grape
DING The propagated so as to come true to name (explain
"bud"; the what is meant by "coming true")? currant?
opening to re- Strawberry? raspberry? blackberry? peach?
ceive it; the pear? orange? fig? plum? cherry? apple? chest-
bud tied. nut ? pecan ?
CHAPTER XVII
HOW PLANTS CLIMB
We have found that plants struggle or contend for a
place in which to live. Some of them become adapted to
grow in the forest shade, others to grow on other plants,
as epiphytes, others to climb to the light. Observe how
woods grapes, and other forest climber^, spread their foli-
age on the very top of the forest tree, while their long
flexile trunks may be bare.
There are several ways by which plants climb, but most
climbers may be classified into four, groups : (i) scramblers,
(2) root climbers, (3) tendril climbers, (4) twiners.
Scramblers. — Some plants rise to light and air by rest-
ing their long and weak stems on the tops of bushes and
quick-growing herbs. Their stems may be elevated in part
by the growing twigs of the plants on which they recline.
Such plants are scramblers. Usually they are provided
with prickles or bristles. In most weedy swamp thickets,
scrambling plants may be found. Briers, some roses, bed-
straw or galium, bittersweet {Solanum Dulcamara, not the
Celastrus), the tear-thumb polygonums, and other plants are
familiar examples of scramblers.
Root Climbers. — Some plants climb by means of true
roots. These roots seek the dark places and therefore
enter the chinks in walls and bark. The trumpet creeper
is a familiar example (Fig. 36). The true or English
ivy, which is often grown to cover buildings, is another
instance. Still another is the poison ivy. Roots are
K 129
I30
BEGINNERS' BOTANY
Fig. 169. — Tendril, to show
where the coil is changed.
distinguished from stem tendrils by their irregidar or
indefinite position as well as by their mode of growth.
Tendril climbers. — A slender coiling part that serves to
hold a climbing plant to a support is known as a tendril.
The free end swings or curves
until it strikes some object, when
it attaches itself and then coils
and draws the plant close to the
support. The spring of the coil
also allows the plant to move i^i
the wind, thereby enabling the
plant to maintain its hold. Slowly pull a well-matured
tendril from its support, and note how strongly it holds
on. Watch the tendrils in a wind-storm. Usually the
tendril attaches to the support by coiling about it, but the
Virginia creeper and Boston ivy (Fig. 170) attach to walls
by means of disks .-. ,
on the ends of the
tendrils.
Since both ends
of the tendril are
fixed, when it iinds
a support, the coil-
ing would tend to
twist it in two. It
will be found, how-
ever, that the tendril
coils in dijferent di-
rections in different parts of its length,
ing an old and stretched-out tendril, the change of direction
in the coil occurred at a. In long tendrils of cucumbers
and melons there may be several changes of direction.
Tendrils may represent either branches or leaves. In the
Fig. 170. — Tendril
OF Boston Ivv.
In Fig. 169, show-
now PLANTS CLIMB
131
Virginia creeper and grape they are branches ; they stand
opposite the leaves in the position of fruit clusters, and
sometimes one branch of a fruit cluster is a tendril. These
tendrils are therefore homologous with fruit-clusters, and
fruit-clusters are branches.
In some plants tendrils are leaflets (Chap. XI). Ex-
amples are the sweet pea and common garden pea. In
Fig. 171, observe the leaf with its two great
stipules, petiole, six normal leaflets, and two
or three pairs of leaflet tendrils and a termi-
nal leaflet tendril. The cobea, a common
garden climber, has a similar arrangement.
In some cases tendrils are stipules, as prob-
ably in the green briers
C
(smilax).
The petiole or midrib
may act as a tendril, as
in various kinds of clem-
atis. In Fig. 172, the
common wild clematis
or " old man vine," this
mode is seen.
Twiners. — The entire
plant or shoot may wind about a support. Such a plant is
a twiner. Examples are bean, hop, morning-glory, moon-
flower, false bittersweet or waxwork {Celastrus'), some
honeysuckles, wistaria, Dutchman's pipe, dodder. The
free tip of the twining branch sweeps about in curves, much
as the tendril does, until it finds support or becomes old
and rigid.
Each kind of plant usually coils in only one direction.
Most plants coil against the sun, or from the observer's
left across his front to his right as he faces the plant.
Fig. 171. — Leaves of Pea,
— very large stipules, op-
posite leaflets, and leaflets
represented by tendrils.
'32
BEGINNERS' BOTANY
Examples are bean, morning-glory. The hop twines from
the observer's right to his A left, or with the sun.
Fig. 172. — Clematis climbing bv Leaf-tendril.
Suggestions. — 136. Set the pupil to watch the behavior of any
plant that has tendrils at different stages of maturity. A vigorous
cucumber plant is one of the best. Just beyond the point of a young
straight tendril set a stake to compare the position of it. Note
whether the tendril changes position from hour to hour or day
to day. 137. Is the tip of the tendril perfectly straight? Why?
Set a small stake at the end of a strong straight tendril, so the
tendril will just reach it. Watch, and make drawing. 138. If a
tendril does not find a support, what does it do? 139. To test the
movement of a free tendril, draw an ink Une lengthwise of it, and
note whether the line remains always on the concave side or the
convex side. 140. Name the tendril-bearing plants that you know.
141. Make similar observations and experiments on the tips of
twining stems. 142. What twining plants do you know, and which
way do they twine ? 143. How does any plant that you know get
up in the world ? 144. Does the stem of a chrabing plant con-
tain more or less substance (weight) than an erect self-supporting
stem of the same height ? Explain.
CHAPTER XVIII
THE FLOWER — ITS PARTS AND FORMS
The function of the flower is to produce seed. It is
probable that all its varied forms and colors contribute
to this supreme end. These forms and colors please the
human fancy and add to the joy of living, but the flower
exists for the good of the plant, not for the good of man.
The parts of the flower are of two general kinds — those
that are directly concerned in the production of seeds, and
those that act as covering and protecting organs. The
former parts are known as the essential organs; the latter
as the floral envelopes.
Envelopes. — The floral envelopes usually bear a close
resemblance to leaves. These envelopes are very com-
monly of two series or kinds — the
outer and the inner. The outer series,
known as the calyx, is usually smaller
and green. It usually comprises the
outer cover of the flower bud. The
calyx is the lowest whorl in Fig. 173. f^,, 173. _ flower of
The inner series, known as the a buitercup in sec-
coroUa, is usually colored and more
special or irregular in shape than the calyx. It is the
showy part of the flower, as a rule. The corolla is the
second or large whorl in Fig. 173.
The calyx may be composed of several leaves. Each
leaf is a sepal. If it is of one piece, it may be lobed or
divided, in which case the divisions are called calyx-lobes.
133
134
BEGINNERS' BOTANY
In like manner, the corolla may be composed of petals, or
it may be of one piece and variously lobed. A calyx of
one piece, no matter how deeply lobed, is gamosepalous.
A corolla of one piece is gamopetalous. When these
series are of separate pieces, as in Fig. 173, the flower is
said to be polysepalous and polypetalous. Sometimes both
series are of separate parts, and
sometimes only one of them is so
formed.
The floral envelopes are ho-
mologous with leaves. Sepals and
petals, at least when more than
three or five, are in more than
one whorl, and one whorl stands
below another so that the parts
overlap. They are borne on the
expanded or thickened end of the
flower stalk ; this end is the torus.
In Fig. 173 all the parts are seen
as attached to the torus. This
part is sometimes called the re-
ceptacle, but this word is a common-language term of
several meanings, whereas torus has no other meaning.
Sometimes one part is attached to another part, as in the
fuchsia (Fig. 174), in which the petals are borne on the
calyx-tube.
Subtending Parts. — Sometimes there are leaf-like parts
just below the calyx, looking like a second calyx. Such
parts accompany the carnation flower. These parts are
bracts (bracts are small specialized leaves); and they form
an involucre. We must be careful that we do not mistake
them for true flower parts. Sometimes the bracts are
large and petal-like, as in the great white blooms of the
Fig. 174. — t LOWER OF
Fuchsia in Section.
THE FLOWER — ITS PARTS AND FORMS
135
flowering dogwood : here the real flowers are several,
small and greenish, forming a small cluster in the center.
Essential Organs. — The essential organs are of two
series. The outer series is composed of the stamens. The
inner series is composed of the pistils.
Stamens bear the pollen, which is made up of grains or
spores, each spore usually being a single plant cell. The
stamen is of two parts, as is readily seen in Figs. 173,
174, — the enlarged terminal part or anther, and the stalk
or filament. The filament is often so short as to seem to
be absent, and the anther is then said to be sessile. The
anther bears the pollen spores. It is made up of two or
four parts (known as sporangia or spore-cases), which
burst and discharge the
pollen. When the pollen is
shed, the stamen dies.
The pistil has three
parts : the lowest, or seed-
bearing part, which is the
ovary; the stigma at the
upper extremity, which is
a flattened or expanded
surface, and usually rough-
ened or sticky; the stalk-
like part or style, connect-
ing the ovary and stigma.
Sometimes the style is apparently wanting, and the stigma
is said to be sessile on the ovary. These parts are shown
in the fuchsia (Fig. 174). The ovary or seed vessel is at a.
A long style, bearing a large stigma, projects from the
flower. See also Figs. 175 and 176.
Stamens and pistils probably are homologous with leaves.
A pistil is sometimes conceived to represent anciently a
Fig. 175. — The Structure of a
Plum Blossom.
Jtf, sepals; /, petals; j/a, stamens: tf, ovary;
.r, style; .r^, stigma. The pistil consists of
the ovary, style, and stigma. It contains
the seed part. The stamens are tipped with
anthers, in which the pollen is borne. The
ovary, o^ ripens into the fruit.
136
BEGINNERS' BOTANY
Fig. 176. — Simple
Pistils of But-
tercup, one in
longitudinal sec-
tion.
leaf as if rolled into a tube ; and an anther, a leaf of which
the edges may have been turned in on the midrib.
The pistil may be of one part or com-
partment, or of many parts . The different
units or parts of which it is composed are
carpels. Each carpel is homologous with
a leaf. Each carpel bears one or more
seeds. A pistil of one carpel is simple;
of two or more carpels, compound. Usu-
ally the structure of the pistil may be de-
termined by cutting horizontally across the lower or seed-
bearing part, as Figs. 177, 178 explain. A flower may
contain a simple pistil (one carpel), as
the pea (Fig. 177); several simple pis-
tils (several separate carpels), as the
buttercup (Fig. 176); or a componnd
pistil with carpels united, as the Saint
John's wort (Fig. 178) and apple. How
many carpels in an apple .' A peach t
An okra pod t A bean pod ? The
seed cavity in each carpel is called a
locule (Latin locus, a place). In these
locules the seeds, are boi'ue.
Conformation of the Flower. — A
flower that has calyx, corolla, stamens,
and pistils is said to be complete (Fig.
173); all others are incomplete. In
some flowers both the floral envelopes
are wanting : such are naked. When
one of the floral envelope series is
wanting, the remaining series is said
to be calyx, and the flower is therefore
apetalous (without petals). The knot-
FiG. 177, — Pistil of
Garden Pea, the
stamens being pulled
down in order to dis-
close it ; also a section
showing the single
compartment (com-
pare Fig. 188).
Fig. 178. — Compound
Pistil of a St.
John's Wort. It
has 5 carpels.
THE FLOWER — ITS PARTS AND FORMS
137
weed (Fig. 179), smartweed, buckwheat, elm are
examples.
Some flowers lack the pistils : these are stami-
nate, whether the envelopes are missing or not.
Others lack the stamens : these are pistillate.
Others have neither stamens nor pistils: these
are sterile (snowball and hydrangea). Those
that have both stamens and pistils are per-
fect, whether or not the envelopes are missing.
Those that lack
either stamens or
pistils are imper-
fect or diclinous.
Staminate and
pistillate flowers
are imperfect or
diclinous.
When staminate and pistillate flowers are borne on the
same plant, e.g. oak (Fig. 180), corn,
beech, chestnut, hazel, walnut, hickory,
pine, begonia (Fig. 181), watermelon.
Fig. 179. — KNOTWEED, a very common but inconspicu-
ous plant along hard walks and roads. Two flowers,
enlarged, are shown at the right. These flowers are
very small and borne in the axils of the leaves.
Fig, 180. — Staminate Catkins of
Oak. The pistillate flowers are in the
leaf axils, and not shown in this pic-
ture.
Fig. 181.— Begonia
Flowers.
Staminate at A \ pistil-
late below, with the
winged ovary at B,
138
BEGIXXERS' BOTANY
^^--
gourd, pumpkin, the plant is monoecious ("in one house").
When they are on different plants, e.g. poplar, cottonwood,
bois d'arc, willow (Fig. 182),
the plant is dioecious ("in two
houses "). Some varieties of
strawberry, grape, and mul-
berry are partly dicecious. Is
the rose either monoecious
or dioecious .''
Flowers in which the parts
of each series are alike are
said to be regular (as in Figs.
173. 174, 175)- Those in
which some parts are unlike
other parts of the same series
are irregular. Their regularity may be in calyx, as in
nasturtium (Fig. 183); in corolla (Figs. 1S4, 185); in the
(X \\ stamens (compare nasturtium, catnip,
Fig. 185, sage); in the pistils. Irregu-
r \ larity is most frequent in the corolla.
Fig. 182. — Catkins of a Willow.
A staminate flower is shown at j, and a
pistillate flower at /. The staminate
and pistillate are on different plants.
Fig. 183.— Flower of
Garden Nasturtium.
Separate petal at a. The
calyx is produced into a
spur.
FIG. 1S4. — The Five Petals
OF THE P\NbV, detached to
show the form.
THE FLOWER — ITS PARTS AND FORMS 1 39
Various Forms of Corolla. — The corolla often assumes
very definite or distinct forms, especially when gamopet-
alous. It may have a long tube with a wide-flaring limb,
when it is said to be funnelform, as in morning-glory
and pumpkin. If the tube is very narrow and the limb
stands at right angles to it, the corolla is salverform, as
in phlox. If the tube is very short and the limb wide-
spreading and nearly circular in outline, the corolla is
rotate or wheel-shaped, as in potato.
A gamopetalous corolla or gamosepalous calyx is often
cleft in such way as to make two prominent parts. Such
parts are said to be lipped or labiate. Each of the lips or
lobes may be notched or toothed. In S-membered flowers,
the lower lip is usually 3-lobed and the upper one 2-lobed.
Labiate flowers are characteristic of the mint family (Fig.
185), and the family therefore is called the Labiatae. (Lit-
erally, labiate means merely "Hpped," without specifying the
number of lips or lobes ; but it is commonly used to desig-
nate 2-lipped flowers.) Strongly 2-parted polypetalous
flowers may be said to be labiate ; but the term is often-
est used for gamopetalous co-
rollas.
Labiate gamopetalous flowers
that are closed in the throat (or
entrance to the tube) are said to
be grinning or personate (per-
, , . riG. 1S6.— PERSONATE FLOWER
sonate means viasked, or person- ^^ toadflax.
like). Snap-dragon is a typical
example; also toadflax or butter-and-eggs (Fig. 186), and
many related plants. Personate flowers usually have
definite relations to insect pollination. Observe how an
insect forces his head into the closed throat of the toad-
flax.
I40
BEGINNERS' BOTANY
The peculiar flowers of the pea tribes are explained in
Figs. 187, 188.
Spathe Flowers. — In many plants, very simple (often
naked) flowers are borne in dense, more or less fleshy
spikes, and the spike is inclosed in or attended by a leaf,
sometimes corolla-like, known as a spathe. The spike of
flowers is technically known as a spadix. This type of
flower is characteristic of the great arum family, which is
Fig. 187. — Flowers of the
Common Bean, with one
flower opened (a) to show
the structure.
Diagram of Alfalfa Flower
IN Section :
C, calyx, D, standard; W^ wing; K, keel; T^ sta-
men-tube; F, filament of tenth stamen; Xy
stigma; K, style; C, ovary; the dotted lines at
E show position of stamen- tube, when pushed
upward by insects. Enlarged.
chiefly tropical. The commonest wild representatives in
the North are Jack-in-the-pulpit, or Indian turnip, and
skunk cabbage. In the former the flowers are all diclin-
ous and naked. In the skunk cabbage all the flowers are
perfect and have four sepals. The common calla is a
good example of this type of inflorescence.
Compositous Flowers. — The head (anthodium) or so-
called "flower" of sunflower (Fig. 189), thistle, aster,
dandelion, daisy, chrysanthemum, goldenrod, is com-
posed of several or viany little flowers, or florets. These
THE FLOWER — ITS PARTS AND FORMS
141
Fig.
-Head of Sunflower.
florets are inclosed in a more or less dense and usually
green involucre. In the thistle (Fig. 190) this involucre is
prickly. A longitudinal
section discloses the flo-
rets, all attached at bot-
tom to a common torus,
and densely packed in
the involucre. The pink
tips of these florets con-
stitute the showy part of
the head.
Each floret of the this-
tle (Fig. 190) is a com-
plete flower. At a is the ovary. At ^ is a much-divided
plumy calyx, known as the pappus. The corolla is long-
tubed, rising above the pappus, and is enlarged and 5-lobed
at the top, c. The style pro-
jects at e. The five anthers
are united about the style in
a ring at d. Such anthers
are said to be syngenesious.
These are the various parts
of the florets of the Com-
positse. In some cases the
pappus is in the form of
barbs, bristles, or scales, and
sometimes it is wanting.
The pappus, as we shall see
later, assists in distributing
the seed. Often the florets
are not all alike. The corolla
of those in the outer circles may be developed into a long,
straplike, or tubular part, and the head then has the ap-
FiG. 190. — Longitudinal Section
OF Thistle Head ; also a Floret
OF Thistle.
142
BEGINNERS' BOTANY
pearance of being one flower with a border of petals. Of
such is the sunflower (Fig. 189), aster, bachelor's button or
cornflower, and field daisy (Fig. 211). These long corolla-
limbs are called rays. In some cultivated composites, all
the florets may develop rays, as in the dahlia and chrysan-
themum. In some species, as dandelion, all the florets
naturally have rays. Syngenesious arrangement of an-
thers is the most characteristic single feature of the
composites.
Double Flowers. — Under the stimulus of cultivation ^and
increased food supply, flowers tend to become double.
True doubling arises
in two ways, mor-
phologically : {\)sta-
mens or pistils may
produce petals (Fig.
191) ; (2) adventi-
tious or accessory
petals may arise in
the circle of petals.
Both of these cate-
gories may be pres-
ent in the same
flower. In the full
double hollyhock the petals derived from the staminal col-
umn are shorter and make a rosette in the center of the
flower. In Fig. 192 is shown the doubling of a daffodil
by the modification of stamens. Other modifications of
flowers are sometimes known as doubling. For example,
double dahlias, chrysanthemums, and sunflowers are forms
in which the disk flowers have developed rays. The snow-
ball is another case. In the wild snowball the external
flowers of the cluster are large and sterile. In the culti-
yA
Fig. 191. — Petals arising from the Stami-
nal Column of Hollyhock, and accessory
petals in the corolia-whorl.
THE FLOWER — ITS PARTS AND FORMS 1 43
vated plant all the flowers have become large and sterile.
Hydrangea is a similar case.
Fig. 192. — Narcissus or Daffodil. Single flower at the right.
Suggestions. — 145. If the pupil has been skillfully conducted
through this chapter by means of careful study of specimens rather
than as a mere memorizing process, he will be in mood to chal-
lenge any flower that he sees and to make an effort to understand
it. Flowers are endlessly modified in form ; but they can be
understood if the pupil looks first for the anthers and ovaries.
How may anthers and ovaries always be distinguished? 146. It is
excellent practice to find the flowers in plants that are commonly
known by name, and to determine the main points in their struc-
ture. What are the flowers in Indian corn? pumpkin or squash?
celery? cabbage? potato? pea? tomato? okra? cotton? rhubarb?
chestnut? wheat? oats? 147. Do all forest trees have flowers?
Explain. 148. Name all the moncecious plants you know.
Dioecious. 149. What plants do you know that bloom before
the leaves appear? Do any bloom after the leaves fall? 150. Ex-
plain the flowers of marigold, hyacinth, lettuce, clover, asparagus,
garden calla, aster, locust, onion, burdock, lily-of-the-valley, crocus.
Golden Glow rudbeckia, cowpea. 151. Define a flower.
Note to the Teacher. — It cannot be urged too often that
the specimens themselves be studied. If this chapter becomes a
mere recitation on names and definitions, the exercise will be
worse than useless. Properly taught by means of the flowers
themselves, the names become merely incidental and a part of
the pupil's language, and the subject has hving interest.
CHAPTER XIX
THE FLOWER — FERTILIZATION AND POLLINATION
Fertilization. — Seeds result from the union of two ele-
ments or parts. One of these elements is a cell-nucleus
of the pollen-grain. The other ele-
ment is the cell-nucleus of an egg-
cell, borne in the ovary. The
pollen-grain falls on the stigma
(Fig. 193). It absorbs the juices
exuded by the stigma, and grows
by sending out a tube (Fig. 194).
This tube grows downward through
the style, absorbing food as it goes,
and finally reaches the egg-cell in
the interior of an ovule in the
ovary (Fig. 195), and fertilization,
or union of a nucleus of the pollen and the
nucleus of the egg-cell in the ovule, takes place.
The ovule and embryo within then develops
into a seed. The growth of the pollen-tube is
often spoken of as germination of the pollen,
but it is not germination in the sense in which
the word is used when speaking of seeds.
Better seeds — that is, those that produce
stronger and more fruitful plants — often re-
sult when i\\Q pollen comes from anotJier flower. a pollen-
Fertilization effected between different flowers <5rain and
THE GROW-
is cross -fertilization ; that resulting from the ing tube
Fig. 193. — B, Pollen escap-
ing from anther; A, pollen
germinating on a stigma.
Enlarged.
THE FLOWER — FERTILIZATION AND POLLINATION
145
application of pollen to pistils in the same flower is close-
fertilization or self-fertilization. It will be seen that the
cross-fertilization relationship may be of many degrees —
between two flowers in the same cluster, between those
in different clusters on the same
branch, between those on different
plants. Usually fertilization takes
place only between plants of the
same species or kind.
In many cases there is, in effect,
an apparent selection of pollen when
pollen from two or more sources is
applied to the stigma. Sometimes
the foreign pollen, if from the same
kind of plant, grows, and fertiliza-
tion results, while pollen from the
same flower is less promptly effec-
tive. If, however, no foreign pol-
len is present, the pollen from the
same flower may finally serve the
same purpose.
In order that the pollen may grow, the stigma must be
ripe. At this stage the stigma is usually moist and some-
times sticky. A ripe stigma is said to be receptive. The
stigma may remain receptive for several hours or even
days, depending on the kind of plant, the weather, and how
soon pollen is received. Watch a certain flower every day
to see the anther locules open and the stigma ripen. When
fertilization takes place, the stigma dies. Observe, also,
how soon the petals wither after the stigma has received
pollen.
Pollination. ^ — The transfer of the pollen from anther
to stigma is known as pollination. The pollen may
Fig. 195. — Diagram to
represent fertiliza-
TION.
i, stigma; j/, style: oz/, ovary: o,
ovule; p, pollen-grain; pt,
pollen-tube; e^ egg-cell; m,
micropyle.
146 BEGINNERS' BOTANY
fall of its own weight on the adjacent stigma, or it
may be carried from flower to flower by wind, insects, or
other agents. There may be self-pollination or cross-pol-
lination, and of course it must always precede fertilization.
g. Usually the pollen is discharged by the burst-
ing of the anthers. The commonest method of
discharge is through a slit on either side of the
anther (Fig. 193). Sometimes it discharges
through a pore at the apex, as in azalea. (Fig.
Fig. 196. —
Anther of 196), rhododendron, huckleberry, wintergreen.
Azalea, Jj^ gome plants a part of the anther wall raises
opening by ,
terminal or falls as a /la, as m barberry (Fig. 197), blue
pores. cohosh, May apple. The opening of an anther
(as also of a seed-pod) is known as dehiscence (de, from ;
kisco, to gape). When an anther or seed pod opens, it is
said to dehisce.
Most flowers are so constructed as to increase the ckatices
of cross-pollination. We have seen that the stigma may
have the power of choosing foreign pollen. The
commonest means of necessitating cross-pollina-
tion is the different times of maturing of stamens
and pistils in the same flower. In most cases
the stamens mature first : the flower is then
proterandrous. When the pistils mature first,
the flower is proterogynous. {Aner, andr, is a
Greek root often used, in combinations, for sta- barberry
men, and gyne for pistil.) The difference in Stamen,
... . with anther
time of ripening may be an hour or two, or it opening by
may be a day. The ripening of the stamens ''"i^-
and pistils at different times is known as dichogamy, and
flowers of such character are said to be dichogamous.
There is little chance for dichogamous flowers to pollinate
themselves. Many flowers are iinperfectly dichogamous —
THE FL WER — PER TILIZA TION AND POLLINA TION 1 47
Fig. 198. — Flower OF Hollyhock; proterandrous.
some of the anthers mature simultaneously with the pistils,
so that there is chance for self-pollination in case for-
eign pollen does
not arrive. Even
when the stigma
receives pollen
from its own
flower, cross-fer-
tilization may
result. The hol-
lyhock is proter-
androus. Fig.
198 shows a
flower jfecently
expanded. The center is occupied by the column of sta-
mens. In Fig. 199, showing an older flower, the long
styles are conspicuous.
Some flowers are so constructed as to prohibit self-polli-
nation. Very irregular flowers are usually of this kind.
iiMN ^^ When a cen-
tripetal flower-
cluster is long
and dense and
the flowers are
sessile or nearly so,
it is called a spike
(Fig. 215). Common
examples of spikes
are plantain, migno-
nette, mullein.
A very short and
dense spike is a head.
Clover (Fig. 216) is
a good example. The
sunflower and related
plants bear many
small flowers in a
very dense and often flat head. Note that in the
sunflower (Fig. 189) the outside or exterior flowers
Fig. 213. — Raceme of Currant.
Terminal or lateral ?
Fig. 214. — Lateral Racemes (in fruit) of Barberry.
Fig. 215.—
Spike of
Plantain.
158
BEGINNERS' BOTANY
open first. Another special form of spike is the catkin,
which usually has scaly bracts, the whole cluster being
deciduous after flowering or fruiting, and the flowers (in
typical cases) having only stamens or pistils. Examples
are the "pussies" of willows (Fig.
:^Mlk«i^ z*^ 1 82) and flower-clusters of oak (Fig.
180), walnuts (Fig. 204), poplars.
Fig. 216. — Head of Clo-
ver Blossoms.
Fig. 217. — Corymb of Caniiy-
TUFT.
When a loose, elongated centripetal flower-cluster has
some primary branches simple, and others irregularly
branched, it is called a panicle. It is a branching raceme.
Because of the earlier growth of the lower branches, the
panicle is usually broadest at the base or conical in outline.
True panicles are not very common.
When an indeterminate flower-cluster is short, so that
FLOWER-CLUSTERS
159
the top is convex or flat, it is a corymb (Fig. 217). The
outermost flowers open first. Centripetal flower-clusters
are sometimes said to be corymbose in mode.
When the branches of an indeterminate cluster arise from
a common point, like the frame of an umbrella, the cluster
is an umbel (Fig. 218). Typical umbels occur in carrot,
parsnip, caraway and other plants of the parsley family :
the family is known as the Umbelliferse, or umbel-bearing
Fig. 218. — Remains of a Last Year's Umbel of Wild Carrot.
family. In the carrot and many other Umbelliferae, there
are small or secondary umbels, called umbellets, at the end
of each of the main branches. (In the center of the wild
carrot umbel one often finds a single, blackish, often
aborted flower, comprising a i -flowered umbellet.)
Centrifugal or Determinate Clusters. — When the ter-
minal or central flower opens first, the cluster is said to be
centrifugal. The growth of the shoot or cluster is deter-
minate, since the length is definitely determined or stopped
by the terminal flower. Fig. 219 shows a determinate or
centrifugal mode of flower bearing.
i6o
BEGINNERS' BOTANY
i-J(/(.
Dense centrifugal clusters are
usually flattish on top because of
the cessation of growth in the
main or central axis. These com-
pact flower-clusters are known
as cymes. Centrifugal clusters
are sometimes said to be cymose
in mode. Apples, pears (Fig.
220), and elders bear flowers in
cymes. Some cyme-forms are
like umbels in general appear-
ance. A head-like cymose clus-
ter is a glomerule ; it blooms from
the top downwards rather than
from the base upwards.
Mixed Clusters. — Often the
cluster is mixed, being determi-
nate in one part and indeterminate
in another part of the same clus-
ter. The main cluster may be indeterminate, but the
branches determinate. The cluster has the appearance of
a panicle, and is usually so called, but it is really a thyrse.
Lilac is a familiar example of a
thyrse. In some cases the main
cluster is determinate and the
branches are indeterminate, as in
hydrangea and elder.
Inflorescence. — The mode or
method of flower arrangement is
known as the inflorescence. That
is, the inflorescence is cymose, co-
rymbose, paniculate, spicate, solitary, determinate, inde-
terminate. By custom, however, the word " inflorescence "
Fig. 219. — Determinate or
Cymose Arrangement. —
Wild geranium.
Fig. 220. — Cyme of Pear.
Often imperfect.
4
3 ,
2
\
1 *-
/4
FLOWER-CLUSTERS l6l
3^3. 1231*1.32 1.
1 r
Fig. 221. — Forms of Centripetal Flower-clusters.
I, raceme; z, spike; 3, umbel; 4, head or anthodium; 5, corymb.
Fig. 222. — Centripetal Inflorescence, ^i?«/i«ai?rf.
6, spadix; 7, compound umbel ; 8, catkin.
Fig. 223. — Centrifugal Inflorescence.
1, cyme; ^y scirpioid raceme (or half cymel.
l62 BEGINNERS' BOTA^VY
has come to be used for the flower-cluster itself in works
on descriptive botany. Thus a cyme or a panicle may be
called an inflorescence. It will be seen that even solitary
flowers follow either indeterminate or determinate methods
of branching.
The flower-stem. — The stem of a solitary flower is
known as a peduncle ; also the general stem of a flower-
cluster. The stem of the iridividual flower in a cluster is
a pedicel. In the so-called stemless plants the peduncle
may arise directly from the ground, or crown of the plant,
as in dandelion, hyacinth, garden daisy ; this kind of
peduncle is called a scape. A scape may bear one or
many flowers. It has no foliage leaves, but it may have
bracts.
Suggestions. — 166. Name six columns in your notebook as
follows : spike, raceme, corymb, umbel, cyme, solitary. Write
each of the following in its appropriate column : larkspur, grape,
rose, wistaria, onion, bridal wreath, banana, hydrangea, phlox,
China berry, hly-of-the-valley, Spanish dagger (or yucca), sorghum,
tuberose, hyacinth, mustard, goldenrod, peach, hollyhock, mul-
lein, crepe myrtle, locust, narcissus, snapdragon, peppergrass,
shepherd's purse, coxcomb, wheat, hawthorn, geranium, carrot,
elder, millet, dogwood, castor bean ; substitute others for plants
that do not grow in your region. 167. In the study of flower-
clusters, it is well to choose first those that are fairly typical of the
various classes discussed in the preceding paragraphs. As soon
as the main types are well fixed in the mind, random clusters
should be examined, for the pupil must never receive the impres-
sion that all flower-clusters follow the definitions in books. Clus-
ters of some of the commonest plants are very puzzling, but the
pupil should at least be able to discover whether the inflorescence
is determinate or indeterminate. Figures 221 to 223 (from the
German) illustrate the theoretical modes of inflorescence. The
numerals indicate the order of opening.
CHAPTER XXI
FRUITS
The ripened ovary, with its attachments, is known as the
fruit. It contains the seeds. If the pistil is simple, or of
one carpel, the fruit
also will have one com-
partment. If the pistil
is compound, or of
more than one carpel,
the fruit usually has an
equal number of com-
partments. The com-
partments in pistil and
fruit are known as lo-
cules (from Latin locus,
meaning "a place").
The simplest kind
of fruit is a ripened
i-loculed ovary. The
first stage in complex-
ity is a ripened 2- or
many-loculed ovary. Very complex forms may arise by the
attachment of other parts to the ovary. Sometimes the style
persists and becomes a beak (mustard pods, dentaria.
Fig. 224), or a tail as in clematis; or the calyx may be
attached to the ovary ; or the ovary may be embedded in
the receptacle, and ovary and receptacle together consti-
tute the fruit : or an involucre may become a part of the
i6^
Fig. 224.-
-Dentaria, or Tooth- wort,
fruit.
164
BEGINNERS' BOTANY
fruit, as possibly in the walnut and hickory (Fig. 225), and
cup of the acorn (Fig. 226). The chestnut and the beech
bear a prickly involucre, but the nuts, , )
Fig. 225. — HlCKORY-NUT.
The nut is the fruit, con-
tained in a husk.
Fig. 226. — Live-oak Acorn.
The fruit is the " seed " part ;
the involucre is the "cup."
or true fruits, are not grown fast to it, and the involucre
can scarcely be called a part of the fruit. A ripened ovary
is a pericarp. A pericarp to which other parts adhere has
been called an accessory or reenforced fruit. (Page 169.)
Some fruits are dehiscent, or split open at maturity and
liberate the seeds ; others are indehiscent, or do not open.
A dehiscent pericarp is called a
The parts into which such
a pod breaks or splits are
known as valves. In inde-
hiscent fruits the seed is
hberated by the decay of
the envelope, or by the
rupturing of the envelope
by the germinating seed.
Indehiscent winged peri-
carps are known as samaras or key fruits.
Fig. 227, — Key of
Sugar Maple.
Fig. 228. — Key
OF Common
American Elm.
Maple (Fig.
227), elm (Fig. 228), and ash (Fig. 93) are examples.
FRUITS
165
Fig. 229.—
Akenes of
Buttercup.
Fjg. 230. — Akeni s
OF Buttercup,
one in longitudi-
nal section.
Pericarps. — The simplest pericarp is a dry, one-
seeded, indehiscent body. It is known as an akene. A
head of akenes is shown in Fig. 229, and the
structure is explained in Fig.
230. Akenes may be seen in
buttercup, hepatica, anemone,
smartweed, buckwheat.
A i-loculed pericarp which
dehisces along the front edge
(that is, the inner edge, next
the center of the flower) is a follicle. The fruit of the
larkspur (Fig. 231) is a follicle. There are usually five of
these fruits (sometimes three or
four) in each larkspur flower, each
pistil ripening into a follicle. If
these pistils were united, a single
compound pistil would be formed.
Columbine, peony, ninebark, milk-
weed, also have follicles.
A i-loculed pericarp that de-
hisces on both edges is a legume.
Peas and beans are typical exam-
ples (Fig. 232); in fact, this character gives
name to the pea family, — Leguminosse.
Often the valves of the
legume twist forcibly and
expel the seeds, throwing
them some distance. The
word " pod " is sometimes restricted to
legumes, but it is better to use it generi-
cally for all dehiscent pericarps.
A compound pod — dehiscing peri-
carp of two or more carpels — is a capsule (Figs. 233, 234,
Fig. 232.— a
Bean Pod.
Fig. 233. — Capsule of
Castor - oil Bean
after Dehiscence.
1 66
BEGIAW'EA'S' BOTANY
Fig. 234. — Cap-
sule OF Morn-
ing Glory.
236, 237). Some capsules are of one
locule, but they may have been compound
when young (in the ovary stage) and the
partitions may have vanished. Sometimes
one or more of the carpels are uniformly
crowded out by the exclusive growth of
other carpels (Fig. 235). The seeds or
parts which are crowded out are said to
be aborted.
There are several ways in which cap-
sules dehisce or open. When they break
along the partitions (or septa), the mode is known as septi-
cidal dehiscence (Fig. 236) ;
In septicidal dehiscence the
fruit separates into parts
representing the original
carpels. These carpels
may still be entire, and
they then dehisce individu-
ally, usually along the inner
edge as if they were follicles. When the compartments
split itt the middle, between the
partitions, the mode is loculicidal
dehiscence (Fig. 237). In some
cases the dehiscence is at the top,
when it is said to be apical (al-
though several modes of dehis-
cence are here included). When
the ivhole top comes off, as in purs-
lane and garden portulaca (Fig.
238), the pod is known as a pyxis. In some cases apical
dehiscence is by means of a hole or clefts.
The peculiar capsule of the mustard family, or Cruci-
FiG. 235. — Three CARPELED Fruit
OF Horse-chestnut. Two locules
are closing by abortion of the ovules.
Fig. 236. —
Sr. John's
Wort. Sep-
ticidal.
Fig. 237.—
Loculici-
dal Pod of
Day-lily.
FRUITS
167
ferse, is known as a silique when it is distinctly longer than
broad (Fig. 224), and a silicle when its breadth nearly
Fig. 238. — Pyxis of Portu-
LACA OR Rose-moss.
Fig. 239. — Berries of Goose-
berry. Remains of calyx at c.
equals or exceeds its length. A cruciferous capsule is
2-carpeled, with a thin partition, each locule containing
seeds in two rows. The two valves detach from below
upwards. Cabbage, turnip, mustard, water-cress, radish,
rape, shepherd's purse,
sweet alyssum, wall-
flower, honesty, are
examples.
Fig. 240. — Uerry of the Ground Cherry
OR Husk Tomato, contained in the inflated
calyx.
The pericarp may \)& fleshy and
indehiscent. A pulpy pericarp
with several or many seeds is a
berry (Figs. 239, 240, 241). To
the horticulturist a berry is a
small, soft, edible fruit, without
Fig. 241. — URAhGE, example
of a berry.
1 68
BEGINNERS' BOTANY
particular reference to its structure. The botanical and
horticultural conceptions of a berry are, therefore, unlike.
In the botanical sense, gooseberries, currants, grapes, to-
matoes, potato-balls, and even eggplant fruits and oranges
(Fig. 241) are berries; strawberries, raspberries, black-
berries are not.
A fleshy pericarp containing one relatively large seed
or stone is a drupe. Examples are plum (Fig. 242), peach,
cherry, apricot, olive. The walls of
the pit in the plum, peach, and cherry
are formed from the inner coats of
the ovary, and the flesh from the
outer coats. Drupes are also known
as stone-fruits.
Fruits that are formed by the sub-
sequent union of separate pistils are
aggregate fruits. The carpels in
aggregate fruits are usually more or less fleshy. In the
raspberry and blackberry flower, the pistils are essentially
distinct, but as the
pistils ripen they co-
here and form one
body (Figs. 243, 244).
Fig. 242. — Plum; exam-
ple of a drupe.
Fio. 244. — Aggregate
FKUIT of MULBERRY;
and a separate fruit.
Fig. 243. — Fruit of Rasp-
berry.
Each of the carpels or pistils in the
raspberry and blackberry is a little
drupe, or drupelet. In the rasp-
berry the entire fruit separates from
the torus, leaving the torus on the
plant. In the blackberry and dew-
FRUITS
169
berry the fruit adheres to the torus, and the two are re-
moved together when the fruit is picked.
Accessory Fruits. — When the pericarp and some other
part grow together, the fruit is said to be accessory or
reenforced. An example is the straw-
berry (Fig. 24s). The edible part is a
greatly enldrged torus, and the pericarps
are akenes embedded in it. These akenes
are commonly called seeds.
Various kinds of reenforced fruits have
received special names. One of these is
the hip, characteristic of roses. In this
case, the torus is deep and hollow, like an
urn, and the sepai-ate akenes are borne
inside it. The mouth of the receptacle
may close, and the walls sometimes become fleshy ; the
fruit may then be mistaken for 1 berry. The fruit of the
pear, apple, and quince is known as a
Fig. 245. — Straw-
berry; fleshy
torus in which akenes
are embedded.
Fig. 246. — Secti<.>n of
AN Apple.
Fig. 247. - Cross-section
OF iN Apple.
pome. In this case the five united carpel ; are completely
buried in the hollow torus, and the torus makes most of
the edible part of the ripe fruit, while the pistils are repre-
sented by the core (Fig. 246). Observe the sepals on the
top of the torus (apex of the fruit) in Fig. 246. Note
the outlines of the embedded pericarp in Fig. 247,
I/O BEGINNERS' BOTANY
Gymnospermous Fruits. — In pine, spruces, and their kin,
there is no fruit in the sense in which the word is used
in the preceding pages, because tliere is no ovary. The
ovules are naked or uncovered, in the axils of the scales of
the young cone, and they have neither style nor stigma.
The pollen falls directly on the mouth of the ovule. The
ovule ripens into a seed, which is usually winged. Because
the ovule is not borne in a sac or ovary, these plants are
called gymnosperms (Greek for "naked seeds"). All the
true cone-bearing plants are of this class ; also certain
other plants, as red cedar, juniper, yew. The plants are
monoecious or sometimes dioecious. The staminate flowers
are mere naked stamens borne beneath scales, in small
yellow catkins which soon fall. The pistillate flowers are
naked ovules beneath scales on cones that persist (Fig.
29). Gymnospermous seeds may have several cotyledons.
Suggestions. ■ — 168, Study the following fruits, or any five fruits
chosen by the teacher, and answer the questions for each : Apple,
peach, bean, tomato, pumpkin. What is its form ? Locate the
scar left by the stem. By what kind of a stem was it attached ?
Is there any remains of the blossom at the blossom end? De-
scribe texture and color of surface. Divide the fruit into the seed
vessel and the surrounding part. Has the fruit any pulp or flesh?
Is it within or without the seed vessel? Is the seed vessel simple
or subdivided? What is the number of seeds? Are the seeds
free, attached to the wall of the vessel, or to a support in the
center? Are they arranged in any order? What kind of wall has
the seed vessel ? What is the difference between a peach stone
and a pe^ch seed? 169. The nut fruits are always available for
study. Note the points suggested above. Determine what the
meat or edible part represents, whether cotyledons or not. Figure
248 is suggestive. 170. Mention all the fleshy fruits you know,
tell where they come from, and refer them to their proper groups.
171. What kinds of fruits can you buy in the market, and to what
groups or classes do they belong? Of which ones are the seeds
only, and not the pericarps, eaten ? 172. An ear of corn is always
available for study. What is it — a fruit or a collecdon of fruits ?
How are the grains arranged on the cob ? How many rows do
you count on each of several ears ? Are all the rows on an ear
FRUITS
171
equally close together ? Do you find an ear with an odd number
of rows ? How do the parts of the husk overlap ? Does the
husk serve as protection from rain ? Can birds pick out the grains?
How do insect enemies enter the ear ? How and when do weevils
lay eggs on corn ? 173. Study a grain of corn. Is it a seed ?
Describe the shape of a grain. Color. Size. Does its surface
show any projections or depressions ? Is the seed-coat thin or
thick ? Transparent or opaque ? Locate the hilum. Where is
the silk scar ? What is the silk ? Sketch the grain from the two
points of view that show it best. Where is the embryo ? Does
the grain have endosperm ? What is dent corn ? Flint corn ?
How many kinds of corn do you know ? For what are they used ?
Fig. 248. — Pecan
Fruit.
Note to Teacher. — There are few more interesting subjects
to beginning pupils than fruits, — the pods of many kinds, forms,
and colors, the berries, and nuts. This interest may well be
utilized to make the teaching alive. All common edible fruits
of orchard and vegetable garden should be brought into this dis-
cussion (some of the kinds are explained in " Lessons with
Plants"). Of dry fruits, as pods, burs, nuts, collections may be
made for the school museum. Fully mature fruits are best for
study, particularly if it is desired to see dehiscence. For com-
parison, pistils and partially grown fruits should be had at the
same time. If the fruits are not ripe enough to dehisce, they
may be placed in the sun to dry. In the school it is well to have
a collection of fruits for study. The specimens may be kept in
glass jars. Always note exterior of fruit and its parts : interior
of fruit with arrangement and attachment of contents.
CHAPTER XXII
DISPERSAL OF SEEDS
It is to the plant's advantage to have its seeds distributed
as widely as possible. It has a better chajice of surviving
in the struggle for existence. It gets away from competi-
tion. Many seeds and fruits are of such character as to
increase their chances of wide dispersal. The commonest
means of dissemination may be classed under four heads :
explosive fruits ; transportation by wind ; transportation by
birds; burs.
Fig. 249. — Explosion of
THE Balsam Pod.
Fig. 250. — Explosive
Fruits of O.xalis.
An exploding pod is shown
at c. The dehiscence is
shown at h. The structure
of the pod is seen at a.
Explosive Fruits. — Some pods open with explosive force
and discharge the seeds. Even bean and everlasting peas
do this. More marked examples , are the locust, witch
hazel, garden balsam (Fig. 249), wild jewel-weed or impa-
tiens (touch-me-not), violet, crane's-bill or wild geranium,
bull nettle, morning glory, and the oxalis (Fig. 250). The
172
DISPEKSAL OF SEEDS 1 73
oxalis is common in several species in the wild and in
cultivation. One of them is known as wood sorrel. Figure
250 shows the common yellow oxalis. The pod opens
loculicidally. The elastic tissue suddenly contracts when
dehiscence takes place, and the seeds are thrown violently.
The squirting cucumber is easily grown in a garden (pro-
cure seeds of seedsmen), and the fruits discharge the seeds
with great force, throwing them many
feet.
Wind Travelers. — Wind -transported
seeds are of two general kinds : those
that are provided with wings, as the flat
seeds of catalpa (Fig. 251) and cone-bear-
ing trees and the samaras of ash, elm,
tulip-tree, ailanthus, and maple; and
those which have feathery buoys or para-
chutes to enable them to float in the air.
Of the latter kind are the fruits of many
composites, in which the pappus is
copious and soft. Dandelion and thistle
are examples. The silk of the milkweed
and probably the hairs on the cotton seed
have a similar office, and also the wool of
the cat-tail. Recall the cottony seeds of fig. 251. — vv^inged
, .„ , , Seeds OF Catalpa.
the willow and poplar.
Dispersal by Birds. — Seeds of berries and of other
small fleshy fruits are carried far and wide by birds. The
pulp is digested, but the seeds are not injured. Note how
the cherries, raspberries, blackberries, June-berries, and
others spring up in the fence rows, where the birds rest.
Some berries and drupes persist far into winter, when they
supply food to cedar birds, robins, and the winter birds.
Red cedar is distributed by birds. Many of these pulpy
174
BEGINNERS' BOTANY
fruits are agreeable as human food, and some of them
have been greatly enlarged or " improved " by the arts of
the cultivator. The seeds are usually indigestible.
Burs. — Many seeds and fruits bear spines, hooks, and
hairs, which adiiere to t/tc coats of animals a)id to clothing.
The burdock has an involucre with hooked scales, contain-
ing the fruits inside. The clotbur is also an involucre.
Both are compositous plants, allied to thistles, but the
whole head, rather than the separate
fruits, is transported. In some com-
positous fruits the pappus takes the
form of hooks and spines, as in the
" Spanish bayonets " and " pitch-
forks." Fruits of various kinds are
known as "stick tights," as of the
agrimony and hound's-tongue. Those
who walk in the woods in late sum-
mer and fall are aware
that plants have means
of disseminating them-
selves (Fig. 252). If it
is impossible to iden-
tify the burs which one
finds on clothing, the seeds may be planted and specimens
of the plant may then be grown.
Fig. 252. — Stealing a Ride.
Suggestions. — 174. What advantage is it to the plant to have
its seeds widely dispersed? 175. What are the leading ways in
which fruits and seeds are dispersed? 176. Name some explosive
fruits. 177. Describe wind travelers. 178. What seeds are car-
ried by birds? 179. Describe some bur with which you are
familiar. 180. Are adhesive fruits usually dehiscent or indehis-
cent? 181. Do samaras grow on low or tall plants, as a rule?
182. Are the cotton fibers on the seed or on the fruit? 183.
Name the ways in which the common weeds of your region are
disseminated. 184. This lesson will suggest other ways in which
DISPERSAL OF SEEDS
175
seeds are transported. Nuts are buried by squirrels for food ; but
if they are not eaten, they may grow. The seeds of many plants
are blown on the snow. The old stalks of weeds, standing through
the winter, may serve to disseminate the plant. Seeds are carried
by water down the streams and along shores. About woolen mills
strange plants often spring up from seed brought in the fleeces.
Sometimes the entire plant is rolled for miles before the winds.
Such plants are " turableweeds." Examples are Russian thistle,
hair grass or tumblegrass {Panicum capillare), cyclone plant
{Cydoloma platyphyllum), and white amaranth {Amarantas
alius). About seaports strange plants are often found, having
been introduced in the earth that is used in ships for ballast.
These plants are usually known as " ballast plants." Most of them
do not persist long. 185. Plants are able to spread themselves by
means of the great numbers of seeds that they produce. How
many seeds may a given elm tree or apple tree or raspberry bush
produce ?
CHAPTER XXIII
PHENOGAMS AND CRYPTOGAMS
The plants thus far studied produce flowers ; and the
flowers produce seeds by means of which the plant is prop-
agated. There are other plants,
however, that produce no seeds,
and these plants (including bac-
teria) are probably more numer-
ous than the seed-bearing plants.
These plants propagate by means
of spores, which are generative cells,
•usually simple, containing no em-
bryo. These spores are very small,
and sometimes are not visible to
the naked eye.
Fig. 254. — Christmas Fern.
— Dryopteris acrostichoides ;
known also as Aspidium.
Prominent among the spore-
propagated plants are ferns. The
common Christmas fern (so called
because it remains green during
winter) is shown in Fig. 254. The
plant has no trunk. The leaves
spring directly from the ground.
The leaves of ferns are called
fronds. They vary in shape, as
other leaves do. Some of the
fronds in Fig. 254 are seen to be
narrower at the top. If these are
examined more closely (Fig. 255),
176
Fig. 255. — Fruiting FtoND
OF Christmas Fern.
Sori at a. One sorus with its in-
dusium at b.
PHENOGAMS AND CRYPTOGAMS
177
it will be seen that the leaflets are contracted and are
densely covered beneath with brown bodies. These bodies
are collections of sporangia or spore-cases.
Fig. 256. — Common Polypode Fern.
Polypodium vulgare.
Fig. 257. — Sori and Spo-
rangium OF Polypode.
A chain of cells lies along
the top of the sporangium,
which springs back elasti-
cally on drying, thus dis-
seminating the spores.
Fig. 258. — The Brake
Fruits underneath
THE Revolute
Edges of the Leaf.
The sporangia are collected into little groups, known as
sori (singular, sorus) or fruit-dots. Each sorus is covered
with a thin scale or shield, known as
an indusium. This indusium sepa-
rates from the frond at its edges, and
the sporangia are exposed. Not all
ferns have indusia. The polypode
(Figs. 256, 257) does not; the sori
are naked. In the brake (Fig. 258)
and maidenhair (Fig. 259) the
edge of the frond turns over
and forms an indusium. The
nephrolepis or sword fern of
greenhouses is allied to the
polypode. The sori are in a
single row on either side the
midrib (Fig. 260). The indu-
sium is circular or kidney-
FiG. 259. — Fruiting Pinnules
of Maidenhair Fern. shaped and open at one edge
178
BEGIA'iVEJiS' BOTANY
Fig. 260. — Part of Frond of
Sword Fern. To the pupil: Is
this illustration right side up ?
or finally all around. The
Boston fern, Washington fern,
Pierson fern, and others, are
horticultural forms of the
common sword fern. In some
ferns (Fig. 261) an entire
frond becomes contracted to
cover the sporangia.
The sporangium or spore-case of a fern is a more or less
globular body and usually with a stalk (Fig. 257). It con-
tains the spores. When ripe it
bursts and the spores are set free.
In a moist, warm place the spores
germinate. They produce a small,
flat, thin, green, more or less heart-
shaped membrane (Fig. 262). This
is the prothallus. Sometimes the
prothallus is an inch or more
across, but oftener it is less than
a dime in size. Although easily
seen, it is commonly unknown ex-
cept to botanists. Prothalli may
often be found in greenhouses where ferns are grown.
Look on the moist stone or
brick walls, or on the firm soil
of undisturbed pots and beds ;
or spores may be sown in a
damp, warm place.
On the under side of the
prothallus two kinds of organs
are borne. These are the
Fig. 262. — Prothallus of a i_ . /
FERN. Enlarged. archegonium (contammg egg-
Archcgonia at a ; antheridia at i. ccUs) and the antheridium (con-
FiG. 261. — Fertile and
Sterile Fronds of the
Sensitive Fern.
PHENOGAMS AND CRYPTOGAMS 179
taining sperm-cells). These organs are minute specialized
parts of the prothallus. Their positions on a particular
prothallus are shown at a and b in Fig. 262, but in some
ferns they are on separate prothalli (plant dioecious). The
sperm-cells escape front the antheridium and in the water
that collects on the prothallus are carried to the archegonium,
where fertilization of the egg takes place. From the ferti-
lized egg-cell a plant- grows, becoming a "fern." In
most cases the prothallus soon dies. The prothallus is the
gametophyte (from Greek, signifying the fertilized plant).
The fern plant, arising from the fertilized egg in the
archegonium, becomes a perennial plant, each year pro-
ducing spores from its fronds (called the sporophyte) ; but
these spores — which are merely detached special kinds of
cells — produce the prothallic phase of the fern plant,
from which new individuals arise. A fern is fertilised but
once in its lifetime. The " fern " bears the spore, the
spore gives rise to the prothallus, and the egg-cell of the
prothallus (when fertilized) gives rise to the fern.
A similar alternation of generations runs all through the
vegetable kingdom, although there are some groups of
plants in which it is very obscure or apparently wanting.
It is very marked in ferns and mosses. In algae (includ-
ing the seaweeds) the gametophyte is the "plant," as
the non-botanist knows it, and the sporophyte is incon-
spicuous. There is a general tendency, in the evolution of
the vegetable kingdom, for the gametophyte to lose its rela-
tive importance and for the sporophyte to become larger and
more highly developed. In the seed-bearing plants the
sporophyte generation is the only one seen by the non-
botanist. The gametophyte stage is of short duration and
the parts are small ; it is confined to the time of fertiliza-
tion.
l8o BEGINNERS' BOTANY
The sporophyte of seed plants, or the "plant" as we
know it, produces two kinds of spores — one kind becom-
ing pollen- grains and the other kind embryo-sacs. The
pollen-spores are borne in sporangia, which are united into
what are called anthers. The embryo-sac, which contains
the egg-cell, is borne in a sporangium known as an ovule.
A gametophytic stage is present in both pollen and embryo
sac : fertilization takes place, and a sporophyte arises. Soon
this sporophyte becomes dormant, and is tlien known as an
embryo. The embryo is packed away within tight-fitting
coats, and the entire body is the seed. When the condi-
tions are right the seed grows, and the sporophyte grows
into herb, bush, or tree. The utility of the alternation of
generations is not understood.
The spores of ferns are borne on leaves ; the spores of
seed-bearing plants are also borne amongst a mass of
specially developed conspicuous leaves known as flowers,
therefore these plants have been known as the flowering
plants. Some of the leaves are developed as envelopes
(calyx, corolla), and others as spore-bearing parts, or spo-
rophylls (stamens, pistils). But the spores of the lower
plants, as of ferns and mosses, may also be borne in spe-
cially developed foliage, so that the line of demarcation
between flowering plants and flowerless plants is not so
definite as was once supposed. The one definite distinction
between these two classes of plants is th^ fact that one class
produces seeds and the other does not. The seed-plants are
now often called spermaphytes, but there is no single
coordinate term to set off those which do not bear seeds.
It is quite as well, for popular purposes, to use the terms
phenogams for the seed-bearing plants and cryptogams for
the others. These terms have been objected to in recent
years because their etymology does not express literal facts
PHENOGAMS AND CRYPTOGAMS
181
{phenogam signifying " showy flowers," and cryptogam
" hidden flowers "), but the terms represent distinct ideas
in classification. The cryptogams include three great
series of plants — the Thallophytes or algae, lichens, and
fungi; the Bryophytes or mosslike plants; the Pteridophytes
or fernlike plants.
Suggestions. — 186. The parts of a fern leaf. The primary
complete divisions of a frond are called pinnae, no matter whether
the frond is pinnate or not. In
ferns the word "pinna" is used in
essentially the same way that leaf-
let is in the once-compound leaves
of other plants. The secondary
leaflets are called pinnules, and in
thrice, or more, compound fronds,
the last complete parts or leaflets
are ultimate pinnules. The dia-
gram (Fig. 263) will aid in making
the subject clear. If the frond
were not divided to the midrib, it
would be simple, but this diagram
represents a compound frond.
Tlie general outline of the frond,
as bounded by the dotted line, is
ovate. The stipe is very short.
The midrib of a compound frond
is known as the rachis. In a de-
compound frond, this main rachis
is called the primary rachis. Seg-
ments (not divided to the rachis)
are seen at the tip, and down to
h on one side and to m on the
other. Pinnae are shown at i, k, I, 0, n. The pinna is entire ;
n is crenate-dentate ; i is sinuate or wavy, with an auricle at the
base ; k and /are compound. The pinna k has twelve entire pin-
nules. (Is there ever an even number of pinnules on any pinna?)
Pinna / has nine compound pinnules, each bearing several entire
ultimate pinnules. The spores. — 187. Lay a mature fruiting frond
of any fern on white paper, top side up, and allow it to remain in
a dry, warm place. The spores will discharge on the paper.
188. Lay the full-grown (but not dry) cap of a mushroom or
toadstool bottom down on a sheet of clean paper, under a venti-
lated box in a warm, dry place. A day later raise the cap.
Fig, 263. — Diagram to explain
THE Terminology of the
Frond.
CHAPTER XXIV
STUDIES IN CRYPTOGAMS
The pupil who has acquired skill in the use of the com-
pound microscope may desire to make more extended ex-
cursions into the cryptogamous orders. The following
plants have been chosen as examples in various groups.
Ferns are sufficiently discussed in the preceding chapter.
Bacteria
If an infusion of ordinary hay is made in water and allowed to
stand, it becomes turbid or cloudy after a few days, and a drop
under the microscope will show the presence of minute oblong
cells swimming in the water perhaps by means of numerous hair-
like appendages, that project through the cell wall from the pro-
toplasm within. At the surface of the dish containing the infusion
the cells are non-motile and are united in long chains. Each
of these cells or organisms is a bacterium (plural, bacteria).
(Fig. 135.)
Bacteria are very minute organisms, — the smallest Known, —
consisting either of separate oblong or spherical cells, or of
chains, plates, or groups of such cells, depending on the kind.
They possess a membrane-like wall which, unlike the cell walls of
higher plants, contains nitrogen. The presence of a nucleus has
not been definitely demonstrated. Muldplication is by the fission
of the vegetative cells ; but under certain conditions of drought,
cold, or exhaustion of the nutrient medium, the protoplasm of the
ordinary cells may become invested with a thick wall, thus form-
ing an endospore which is very resistant to extremes of environ-
ment. No sexual reproduction is known.
Bacteria are very widely distributed as parasites and sapro-
phytes in almost all conceivable places. Decay is largely caused
by bacteria, accompanied in animal tissue by the liberation of
foul-smelling gases. Certain species grow in the reservoirs and
pipes of water supplies, rendering the water brackish and often
undrinkable. Some kinds q>{ fermentation (the breaking down or
decomposing of organic compounds, usually accompanied by the
STUDIES IN CRYPTOGAMS 1 83
formation of gas) are due to these organisms. Other bacteria
oxidize alcohol to acetic acid, and produce lactic acid in railk and
butyric acid in butter. Bacteria live in the mouth, stomach, in-
testines, and on the surface of the skin of animals. Some secrete
gelatinous sheaths around themselves; others secrete sulfur or
iron, giving the substratum a vivid color.
Were it not for bacteria, man could not live on the earth, for
not only are they agents in the process of decay, but they are
concerned in certain healthful processes of plants and animals.
We have learned in Chap. VIII how bacteria are related to nitro-
gen-gathering.
Bacteria are of economic importance not alone because of their
eifect on materials used by man, but also because of the disease-
producing power of certain species. Pus is caused by a spherical
form, tetanus or lock-jaw by a rod-shaped form, diphtheria by
short oblong chains, tuberculosis or " consumption " by more slen-
der oblong chains, and typhoid fever, cholera, and other diseases
by other forms. iVlany diseases of animals and plants are
caused by bacteria. Disease-producing bacteria are said to be
pathogenic.
The abihty to grow in other nutrient substances than the natu-
ral one has greatly facilitated the study of these minute forms
of life. By the use of suitable culture media and proper precau-
tions, pure cultures of a particular disease-producing bacterium
may be obtained with which further experiments may be con-
ducted.
Milk provides an excellent collecting place for bacteria coming
from the air, from the coat of the cow and from the milker. Dis-
ease germs are sometimes carried in milk. If a drop of milk is
spread on a culture medium (as agar), and provided with proper
temperature, the bacteria will multiply, each one forming a colony
visible to the naked eye. In this way, the number of bacteria
originally contained in the milk may be counted.
Bacteria are disseminated in water, as the germ of typhoid fever
and cholera ; in milk and other fluids ; in the air ; and on the
bodies of flies, feet of birds, and otherwise.
Bacteria are thought by many to have descended from algae by
the loss of chlorophyll and decrease in size due to the more
specialized acquired saprophytic and parasitic habit.
The algse comprise most of the green floating " scum " which
covers the surfaces of ponds and other quiet waters. The masses
of plants are often called " frog spittle." Others are attached to
stones, pieces of wood, and other objects submerged in streams
iS4
BEGINNERS' BOTANY
and lakes, and many are found on moist ground and on dripping
rocks. Aside from these, all the plants commonly known as seaweeds
belong to this category ; these latter are inhabitants of salt water.
The simplest forms of algae consist of a single spherical cell,
which multiplies by repeated division or fission. Many of the
forms found in fresh water are filamentous, i.e. the plant body
consists of long threads, either simple or branched. Such a plant
body is termed a thallus. This term applies to the vegetative
body of all plants that are not differentiated into stem and leaves.
Such plants are known as thallophytes (p. i8i). All algae contain
chlorophyll, and are able to assimilate carbon dioxid from the air.
This distinguishes them from the fungi.
Nostoc. — On wet rocks and damp soil dark, semitransparent
irregular or spherical gelatinous masses about the size of a pea are
often found. These consist of a colony of contorted filamentous
algae embedded in the jelly-like mass. The chain of cells in the
filament is necklace-like. Each cell is homogeneous, without
apparent nucleus, and blue-green in color, except one cell which
is larger and clearer than the rest. The plant therefore belongs
to the group of blue-green alga. The jelly probably serves to
maintain a more even moisture and to provide mechanical protec-
tion. Multiplication is wholly by the breaking
up of the threads. Occasionally certain cells
of the filament thicken to become resting-
spores, but no other spore formation occurs.
Oscillatoria. — The blue-green coatings
found on damp soil and in water frequently
show under the microscope the presence of
filamentous algae composed of many short
rffl
mm..
Fig.
264.— FII,A^IENT OF Oscillatoria, showing one
dead cell where the strand will break.
homogeneous cells (Fig. 264). If watched
closely, some filaments will be seen to wave
back and forth slowly, showing a peculiar power
of movement characteristic of this plant.
Multiplication is by the breaking up of the
threads. There is no true spore formation.
Spirogyra. — One of the most common forms
of the green algae is spirogyra (Fig. 2C5). This
Fig. 265. — Strand
OF Spirogyra,
showing the chlo-
rophyll bands.
Tliere is a nu-
cleus at a. How
many cells, or
parts of cells, are
shown in this fig-
ure ?
STUDIES IN CRYPTOGAMS
185
plant often forms the greater part of the floating green mass (or
" frog spittle ") on ponds. The threadhke character of the thallus
can be seen with the naked eye or with a liand
lens, but to study it carefully a microscope
magnifying two hundred diameters or more
must be used. The thread is divided into long
cells by cross walls which, according to the
species, are either straight or curiously folded
(Fig. 266). The chlorophyll is arranged in
beautiful spiral bands near the wall of each cell.
From the character of these bands the plant
takes its name. Each cell is provided with a
nucleus and other protoplasvi. The nucleus is
suspended near the center of the cell {a, Fig.
265) by delicate strands of protoplasm radiat-
ing toward the wall and terminating at certain
points in the chlorophyll band. The remainder
of the protoplasm forms a thin layer lining the
wall. The interior of the cell is filled with
cell-sap. The protoplasm and nucleus cannot
be easily seen, but if the plant is stained with
a dilute alcoholic solution of eosin they become
clear.
Spirogyra is propagated vegetatively by the
breaking off of parts of the threads, which con-
tinue to grow as new plants. Resting-spores,
which may remain dormant for a time, are formed by a process
known as conjugation. Two threads lying side
by side send out short projections, usually from
all the cells of a long series (Fig. 266). The
projections or processes from opposite cells
grow toward each other, meet, and fuse, form-
ing a connecting tube between the cells. The
protoplasm, nucleus, and chlorophyll band of
one cell now pass through this tube, and unite
with the contents of the other cell. The en-
tire mass tPien becomes surrounded by a thick
cellulose wall, thus completing the resting-
spore, or zygospore (z, Fig. 266).
Fig. 266. — Con-
jugation OF
Spirogyra.
Ripe zygospores
on the left ; t/,
connecting
tubes.
Fig. 267. — Strand,
OR Filament of
Zygnema, freed
from its gelatinous
covering.
Zygnema is an alga closely related to spiro-
gyra and found in similat places. Its life
history is practically the same, but it differs
from spirogyra in having two star-shaped
chlorophyll bodies (Fig. 267) in each cell, in-
stead of a chlorophyll-bearing spiral band.
1 86 BEGIA'NEJiS' BOTANY
Vaucheria is another alga common in shallow water and on
damp soil. The thallus is much branched, but the threads are
not divided by cross walls as in spirogyra. The plants are attached
by means of colorless root-like organs which are much like the
root hairs of the higher plants : these are rhhoids. The chloro-
phyll is in the form oi grams scattered through the thread.
Vaucheria has a special mode of asexual reproduction by
means of swimming spores or swarm-spores . These are formed
singly in a short enlarged lateral branch known as the sporangium.
When the sporangium bursts, the entire contents escape, forming
a single large swarm-spore, which swims about by means of
numerous lashes or cilia on its surface. The swarm spores are so
large that they can be seen with the naked eye. After swimming
about for some time they come to rest and germinate, producing
a new plant.
The formation of resting-spores of vaucheria is acoraplished by
means of special organs, odgonia (p, Fig. 268) and antheridia
(a, Fig. 268). Both of
these are specially devel-
oped branches from the
thallus. The antheridia
are nearly cylindrical, and
curved toward the oogonia.
FiG. 268.-TH.EAD OP VAUCHERIA WiT.i '['le, uppcr part of an an-
05G0NIA AND ANTHERIDIA. theridium IS cut off by a
cross wall, and within it
numerous ciliated sperm-cflls are formed. These escape by the
ruptured apex of the antheridium. The oogonia are more en-
larged than the antheridia, and have a beak-like projection turned
a little to one side of the apex. They are separated from the
thallus thread by a cross wall, and contain a single large green
cell, the egg-cell. The apex of the oogonium is dissolved, and
through the opening the sperm-cells enter. Fertilization is thus
accomplished. After fertilization the egg-cell becomes invested
with a thick wall and is thus converted into a resting-spore, the
oospore.
Fucus. — These are rather large specialized algse belonging to the
group known as brown seaweeds and found attached by a disk to
the rocks of the seashore just below high tide (Fig. 269). They
are firm and strong to resist wave action and are so attached as to
avoid being washed ashore. They are very abundant algse. In
shape the plants are long, branched, and multicellular, with either
flat or terete branches. They are olive-brown. Propagation is by
the breaking off of the branches. No zoospores are produced,
as in many other seaweeds ; and reproduction is wholly sexual.
STUDIES IN CRYPTOGAMS
187
The antheridia, bearing sperm-cells, and the oogonia, each bearing
eight egg-cells, are sunken in pits or conceptacles. These pits
are aggregated in the swollen lighter colored tips of some of the
branches {s, s, Fig. 269). The egg-cells and sperm-cells escape
from the pits and fertilization takes place in the water. The
matured eggs, or spores, reproduce the fucus plant directly.
Flo. 269. — Fucus. Fruiting
branches at s, s. On the
stem are-two air-bladders.
Fig. 270. — NiTELLA.
Nitella. — This is a large branched and specialized fresh-water
alga found in tufts attached to the bottom in shallow ponds (Fig.
270) . Between the whorls of branches are long internodes consisting
of a single cylindrical cell, which is oiie of the largest cells known in
vegetable tissue. Under the microscope the walls of this cell are
found to be lined with a layer of small stationary chloroplastids,
within which layer the protoplasm, under favorable circumstances,
will be found in motion, moving up one side and down the other
(in rotation). Note the clear streak up the side of the cell and its
relation to the moving current.
Fungi
Some forins of fungi are familiar to every one. Mushrooms
and toadstools, with their varied forms and colors, are common
in fields, woods, and pastures. In every household the common
molds are familiar intruders, appearing on old bread, vegetables,
and even within tightly sealed fruit jars, where they form a felt-
like layer dusted over with blue, yellow, or black powder. The
strange occurrence of these plants long mystified people, who
BEGINNERS' BOTANY
thought they were productions of the dead matter upon which they
grew, but now we know that a mold, as any other plant, cannot
originate spontaneously ; it must start from something which is
analogous to a seed. The "seed " in this case is a spore. A spore
may be produced by a vegetative process (growing out from the
ordinary plant tissues), or it may be the result of a. fertilization
process.
Favorable conditions for the growth of fungi. — Place a piece
of bread under a moist bell jar and another in an uncovered
place near by. Sow mold on each. Note the result from day to
day. Moisten a third piece of bread with weak copper sulfate
(blue vitriol) or mercuric chlorid solution,
sow mold, cover with bell jar, note results,
and explain. Expose pieces of different kinds
of food in a damp atmosphere and observe
the variety of organisms appearing. Fungi
are saprophytes or parasites, and must be
provided with organic matter on which to
grow. They are usually most abundant in
moist places and wet seasons.
Fig. 271. — MucoR Mold. — One of these molds (j^/i/(r(?r mii-
MucEDo, showing habit, cedo) , which is very common on all decay-
ing fruits and vegetables, is shown in Fig.
271, somewhat magnified. When fruiting, this mold appears as a
dense mass of long white hairs, often over an inch high, standing
erect from the fruit or vegetable on which it is growing.
The Hfe of this mucor begins with a minute rounded spore
{a, Fig. 272), which lodges on the decaying material. When the
spore germinates, it sends out a dehcate thread that grows rapidly
in length and forms very many branches that
soon permeate every part of the substance on
which the plant grows {b, Fig. 272). One of
these threads is termed a hypha. All the
threads together form the mycelium of the
fungus. The mycelium disorganizes the ma-
terial in which it grows, and thus the mucor
plant (Fig. 271) is nourished. It corresponds
physiologically to the roots and stems of other
plants.
When the mycelium is about two days old, it begins to form the
long fruiting stalks which^we first noticed. To study them, use a
compound microscope magnifying about two hundred diameters.
One of the stalks, magnified, is shown in a, Fig. 274. It consists
of a rounded head, the sporangium, sp, supported on a long.
Fig. 272. — Spores
ofMucor, some
germinating.
STUDIES IN CRYPTOGAMS
189
Fig. 274. — MucoR.
, sporangium; 3, sporangium
bursting; c', columella.
delicate stalk, the sporangiophore. The stalk is separated from
the sporangium by a wall which is formed at the base of the spo-
rangium. This wall, however, does not
extend straight across the thread, but it
arches up into the sporangium like an
inverted pear. It is known as the col-
umella, c. When the sporangium is
placed in water, the wall immediately
dissolves and allows hundreds of spores,
which were formed in the cavity within
the sporangium, to escape, b. All that
is left of the fruit is the stalk, with the
pear-shaped columella at its summit, c.
The spores that have been set free by the
breaking of the sporangium wall are now
scattered by the wind and other agents.
Those that lodge in favorable places be-
gin to grow immediately and reproduce
the fungus. The others soon perish.
The mucor may continue to reproduce itself in this way indefi-
nitely, but these spores are very delicate and
usually die if they do not fall on favorable
ground, so that the fungus is provided with
another means of carrying itself over unfavora-
ble seasons, as winter. This is accomplished
by means of curious thick-walled resting-spores
or zygospores. The zygospores are formed on
the mycelium buried within the substance on
which the plant grows; They originate in the
following way : Two threads that lie near to-
gether send out short branches, which grow
toward each other and finally meet (Fig. 273).
The walls at the ends, a, then disappear, allow-
ing the contents to flow together. At the same
time, however, two other walls are formed at
points farther back, b, b, separating the short
section, c, from the remainder of the thread.
This section now increases in size and becomes
covered with a thick, dark brown wall orna-
mented with thickened tubercles. The zygo-
spore is now mature and, after a period of
rest, it germinates, either producing a sporan-
gium directly or growing out as mycelium.
The zygospores of the mucors form one of the most interesting
and instructive objects among the lower plants. They are, how-
ever, very difficult to obtain. One of the mucors \Sporodinia
Fig. 273. — Mucor,
showing formation
of zygospore on
the right; germi-
nating zygospore
on the left.
igo BEGINNERS' BOTANY
grandis) may be frequently found in summer growing on toad-
stools. This plant usually produces zygospores that are formed
on the aerial mycelium. The zygospores are large enough to be
recognized with a hand lens. The material may be dried and
kept for winter study, or the zygospores may be prepared for
permanent microscopic mounts in the ordinary way.
Yeast. — This is a very much reduced and simple fungus, con-
sisting normally of isolated spherical or elliptical cells (Fig. 275)
containing abundant protoplasm and prob-
ably a nucleus, although the latter is not
easily observed. It propagates rapidly by
budding, which consists of the gradual extru-
sion of a wart-like swelling that is sooner or
later cut off at the base by constriction, thus
forming a separate organism. Although sim-
■c^r. r viTAST plfi in structure, the yeast is found to be
Plants closely related to some of the higher groups of
fungi as shown by the method of spore forma-
tion. When grown on special substances like potato or carrot, the
contents of the cell may form spores inside of the sac-like mother
cell, thus resembling the sac-fungi to which blue mold and mildews
belong. The yeast plant is remarkable on account of its power to
induce alcoholic fermentation in the media in which it grows.
There are many kinds of yeasts. One of them is found in the
common yeast cakes. In the process of manufacture of these
cakes, the yeast cells grow to a certain stage, and the material is
then dried and fashioned into small cakes, each cake containing
great numbers of the yeast cells. AVhen the yeast cake is added
to dough, and proper conditions of warmth and moisture are pro-
vided, the yeast grows rapidly and breaks up the sugar of the
dough into carbon dioxid and alcohol. This is fermentation.
The gases escape and puff up the dough, causing the bread to rise.
In this loosened condition the dough is baked ; if it is not baked
quickly enough, the bread ^' falls." Shake up a bit of yeast cake
in slightly sweetened water : the water soon becomes cloudy from
the growing yeasts.
Parasitic fungi. — Most of the molds are saprophytes. Many
other fungi are parasitic on living plants and animals (Fig. 285).
Some of them have complicated life histories, undergoing many
changes before the original spore is again produced. The willow
mildew and the common rust of itiheat yi'\\\ serve to illustrate the
habits of parasitic fungi.
The willow mildew (fJncinula salicis). — This is one of the sac
fungi. It forms white downy patches on the leaves of willows
STUDIES IN CRYPTOGAMS
191
Fig. 276. — Colonies of Willow Mildew.
(Fig. 276). These patches consist of numerous interwoven
threads that may be recognized under the microscope as the
mycehum of the fungus.
The mycehum in this
case hves on the surface
of the leaf and nour-
ishes itself by sending
short branches into the
cells of the leaf to ab-
sorb food materials from
them.
Numerous summer-spores are formed of short, erect branches all
over the white surface. One of these branches is shown in Fig.
277. When it has grown to a cer-
tain length, the upper part begins
to segment or divide into spores
which fall and are scattered by the
wind. Those faUing on other wil-
lows reproduce the fungus there.
This process continues all summer,
but in the later part of the season
provision is made to maintain the
mildew through the winter. If some
of the white patches are closely ex-
amined in July or August, a number
of Httle black bodies will be seen among the threads. These little
bodies are csHA&A. perithecia, shown in Fig. 278. To the naked eye
they appear as minute specks,
but when seen under a magnifi-
cation of 200 diameters they
present a very interesting appear-
ance. They are hollow spheri-
cal bodies decorated around
the outside
with a fringe
of crook-like
hairs. The
resting-spores
of the willow
mildew are
produced in
sacs or (jij'cnn-
closed witli-
in the leath-
ery perithecia. Figure 279 shows a cross-section of a perithecium
with the asci arising from the bottom. The spores remain securely
Fig.
277. — Summer-spores of
Willow Mildew.
Fig. 278.
— Perithecium of Wii^
LOW Mildew.
Fig. 279. — Section
THROUGH Peri-
thecium of Wil-
low Mildew.
192
BEGINNERS' BOTANY
packed in the perithecia. They do not ripen in the autumn, but
fall to the ground with the leaf, and there remain securely pro-
tected among the dead foliage. The following spring they mature
and are liberated by the decay of the perithecia. They are then
ready to attack the unfolding leaves of the willow and repeat the
work of the summer before.
Fig, 280. — Sori con-
taining Teleuto-
SPORES OF Wheat
Rust.
The wheat rust. — The development of some of the rusts, as the
common wheat rust {Pucchiia gi-aminis), is eveji more interesting
and compHcated than that of the
mildews. Wheat rust is also a true
parasite, affecting wheat and a few
other grasses. The mycelium here
cannot be seen by the unaided eye,
for it consists of threads which are
present within the host plant, mostly
in the intercellular spaces. These
threads also send short branches, or
haiistoria (Fig. 132), into the neigh-
boring cells to absorb nutriment.
The resting-spores of wheat rust
are produced in late summer, when
they may be found in black lines
breaking through the epidermis of
the wheat stalk (black-rust stage).
They are formed in masses, called
sori (Fig. 280), from the ends of
numerous crowded myceUal strands just beneath the epidermis of
the host. The individual spores are very small and can be well
studied only with a microscope of high power
(x about 400). They are brown two-celled bod-
ies with a thick wall (Fig. 281). Since they are
the resting or winter-spores, they are termed teleu-
tospores ("completed spores"). Usually they do
not fall, but remain in the sori during winter.
The following spring each cell of the teleutospore
puts forth a rather stout thread, which does not
grow more than several times the length of the
spore and terminates in a blunt extremity. This
germ tube, promycelium, now becomes divided
into four cells by cross walls, which are formed
from the top downwards. Each cell gives rise to a short, pointed
branch which, in the course of a few hours, forms at its summit
a single spore called a spoi-idium. This in turn germinates and
produces a mycelium. In Fig. 2S2 a germinating teleutospore
is drawn to show the promycelium, /, divided into four cells,
Fig. 281. — Te-
leutospore
OF Wheat
Rust.
STUDIES IN CRYPTOGAMS
193
each producing a short branch with a httle spo-
ridium, s.
A most remarkable circumstance in the life
history of the wheat rust is the fact that the my-
celium produced by the sporidium can live only
in barberry leaves, and it follows that if no- bar-
berry bushes are in the neighborhood the sporidia
finally perish. Those which happen to lodge on
a barberry bush germinate immediately, produc-
ing a mycelium that enters the barberry leaf and
grows within its tissues. Very soon the fungus
produces a new kind of spores on the barberry
leaves. These are called cBcidiospores. They are
formed in long chains in little fringed cups, or
cecidia, which appear in groups on the lower side
of the leaf (Fig. 283). These orange or yellow
aecidia are termed cluster-cups. In Fig. 284 is
shown a cross-section of one of the cups, outlin-
ing the long chains of spores, and the mycelium in the tissues.
The aecidiospores are formed in the spring, and after they have
been set free, some of them lodge on wheat or other grasses,
where they germinate immediately. The germ-tube enters the
Fig. 282. — Ger-
minating Te-
leutospore
OF Wheat
Rust.
Fig. 283. — Leaf
OF Barberry
WITH Clus-
ter-cups.
Fig. 284.— Section through a
Cluster-cup on Barberry Leaf.
leaf through a stomate, whence it spreads among the cells of the
wheat plant. In summer one-celled reddish icredospores ("blight
spores," red-rust stage) are produced in a manner similar to the
teleutospores. These are capable of germinating immediately.
194
BEGINNERS' BOTANY
and serve to disseminate the fungus during the summer on other
wheat plants or grasses. Late in the season, teleutospores are
again produced, completing the life cycle of the plant.
Many rusts besides Fucdnia graminis produce different spore
forms on different plants. The phenomenon is called heterxcistii,
and was first shovvn to exist in the wheat rust. Curiously enough,
the peasants of Europe had observed and asserted that barberry
bushes cause wheat to blight long before science explained the
relation between the cluster-cups on barberry and the rust on
wheat. The true relation was actually demonstrated, as has since
been done for many other rusts on their respective hosts, by sow-
ing the secidiospores on healthy wheat plants and thus producing
Anmracnose CatiKer
Fig. 285. — How a Parasitic Fungus works. Anthracnose on a bean pod
entering the bean beneath. (Whetzel.)
the rust. The cedar apple is another rust, producing the curious
swellings often found on the branches of red cedar trees. In the
spring the teleutospores ooze out from the " apple " in brown-
ish yellow masses. It has been found that these attack various
fruit trees, producing secidia on their leaves. Fig. 285 explains
how a parasitic fungus works.
Puffbalh, mushrooms, toadstools, and shelf fungi. — These
represent what are called the higher fungi, because of the size and
complexity of the plant body as well as from the fact that they
seem to stand at the end of one hne of evolution. The mycelial
threads grow together in extensive strands in rotten wood or in
the soil, and send out large complex growths of mycelium in con-
STUDIES IN CRYPTOGAMS
195
Fig. 286. — Part of Gill of the Cul-
tivated Mushroom.
ir, trama tissue; j/i, hymenium; 5, basidium;
sii sterigma; sp, spore. (Atkinson.)
nection with which the spores are borne. These aerial parts are
the only ones we ordinarily see, and which constitute the "mush-
room" part (Fig. 131).
Only asexual spores (ba-
sidiospores) are produced,
and on short stalks (basidia)
(Fig. 286). In the puff-
balls the spores are inclosed
and constitute a large part
of the "smoke." In the
mushrooms and toadstools
they are borne on gills, and
in the shelf fungi (Fig. 134)
on the walls of minute pores
of the underside. The my-
celium of these shelf fungi
frequently lives and grows
for a long time concealed in
the substratum before the
visible fruit bodies are sent
out. Practically all timber
decay is caused by such
growth, and the damage is
largely done before the fruiting bodies appear. For other ac-
counts of mushrooms, see Chap. XIV.
Lichens
Lichens are so common everywhere
that the attention of the student is sure
to be drawn to them. They grow on
rocks, trunks of trees (Fig. 287), old
fences, and on the earth. They are
thin, usually gray ragged objects, ap-
parently lifeless. Their study is too
difficult for beginners, but a few words
of explanation may be useful.
Lichens were formerly supposed to
be a distinct or separate division of
plants. They are now known to be or-
ganisms, each species of which is a con-
stant association of a fungus and an alga.
The thallus is ordinarily made up of fun-
gous mycelium or tissue within which
Fig. 287. ^Lichen on an the imprisoned alga is definitely dis-
Oak Trunk. (A species tributed. The result is a growth unlike
cf Phvscia^ either component. This association of
196
BEGINNERS' BOTANY
alga and fungus is usually spoken of as symbiosis, or mutually
helpful growth, the alga furnishing some things, the fungus others,
and both together being able to accomplish work that neither
could do independently. By others this union is considered to
be a mild form of parasitism, in which the fungus profits at the
expense of the alga. As favorable to this view, the facts are cited
that each component is able to grow independently, and that under
such conditions the algal cells seem to thrive better than when
imprisoned by the fungus.
Lichens propagate by means of soredia, which are tiny parts
separated from the body of the thallus, and consisting of one or
more algal cells overgrown with fungus threads. These are readily
observed in many lichens. They also produce spores, usually
ascospores, which are always the product of the fungus element,
and which, reproduce the lichen by germinating in the presence of
algal cells, to which the hyphse immediately cling.
Lichens are found in the most inhospitable places, and, by
means of acids which they secrete, they attack and slowly disin-
tegrate even the hardest rocks. By making thin sections of the
thallus with a sharp razor and examining under the compound
microscope, it is easy to distinguish the two components in many
lichens.
Liverworts
The liverworts are peculiar flat green plants usually found
on wet cliffs and in other moist, shady places. They frequently
occur in greenhouses where the soil is kept constantly wet.
Fig. 288. Fig. 289.
Plants of Marchantia.
One of the commonest liverworts is Marchantia pohmorpha,
two plants of which are shown in Figs. 288, 289. The plant
consists of a ribbon-like thallus that creeps along the ground,
becoming repeatedly forked as it grows. The end of each branch
STUDIES IN CRYPTOGAMS
197
is always conspicuously notched. There is a prominent midrib
extending along the center of each branch of the thallus. On the
under side of the thallus, especially along the midrib, there are
numerous rhizoids which serve the purpose of roots, absorbing
nourishment from the earth and
holding the plant in its place. The
upper surface of the thallus is di-
vided into minute rhombic areas
that can be seen with the naked
eye. Each of these areas is per-
forated by a small breathing pore
or stomate that leads into a cavity
just beneath the epidermis. This
space is surrounded by chlorophyll-
bearing cells, some of which stand
in rows from the bottom of the
cavity (Fig. 290). The dehcate
assimilating tissue is thus brought in close communication with the
outer air through the pore in the thick, protecting epidermis.
At various points on the midrib are little cups containing
small green bodies. These bodies are buds or gemma which are
outgrowths from the cells at the bottom of the cup. They become
loosened and are then dispersed by the rain to other places, where
they take root and grow into new plants.
The most striking organs on the thallus of marchantia are the
peculiar stalked bodies shown in Figs. 288, 289. These are
termed archegoniophores and antheridiophores or receptacles. Their
structure and function are very interesting, but their parts are so
minute that they can be studied only with the aid of a microscope
magnifying from 100 to 400 times. Enlarged drawings will guide
the pupil.
Fig. 290. — Section of Thallus
OF Marchantia. Stomate at a.
Fig. 291. — Section through Antheridiophore of Marchantia,
showing antheridia. One antheridium more magnified."
The antheridiophores are fleshy, lobed disks borne on short stalks
(Fig. 291). The upper surface of the disk shows openings scarcely
visible to the naked eye. However, a section of the disk, such as
is drawn in Fig. 291, shows that the pores lead into oblong cavi-
igS
BEGINNERS' BOTANY
Fig. 292. —
Archego-
NIUM OF
Marchantia.
ties in the receptacle. From the base of each cavity there arises
a thick, club-shaped body, the antheridium. Within the anther-
idium are formed many sperm -cells which are capa-
ble of swimming about in water by means of long
lashes or cilia attached to them. When the anther-
idium is mature, it bursts and allows the ciliated
sperm cells to escape.
The archegoiiiophores are also elevated on stalks
(Fig. 289). Instead of a simple disk, the recepta-
cle consists of nine or more finger-like rays. Along
the under side of the rays, between dehcately
fringed curtains, peculiar flask-like bodies, or arche-
gonia, are situated. The archegonia are not visible
to the naked eye. They can be studied only with
the microscope (x about 400). One of them
much magnified is represented in Fig. 292. Its
principal parts are the long neck, a, and the
rounded venter, b, inclosing a large free cell — the
egg-cell.
We have seen that the antheridium at maturity discharges its
sperm-cells. These swim about in the water provided by the dew
and rain. Some of them finally find their way
to the archegonia and egg-cells, the latter
being fertilized, as pollen fertilizes the ovules
of higher plants.
After fertilization the egg-cell develops into
the spore capsule or sporogoniuvi. The mature
spore capsules may be seen in Fig. 293. They
consist of an oval spore-case on a short stalk,
the base of which is imbedded in the tissue of
the receptacle, from which it derives the neces-
sary nourishment for the development of the
sporogonium. At maturity the sporogonium
is ruptured at the apex, setting free the spheri-
cal spores together with numerous filaments
having spirally thickened walls (Fig. 294). These filaments are
called elaters. When drying, they exhibit rapid movements by
means of which the spores are scattered. The spores germinate
and again produce the thallus of marchantia.
Fig. 293. — Arche-
goniophorr.
WITH SPORO-
gonia, of Mar-
chantia.
Fig. 294. — Spores and Elaters of Marchantia.
STUDIES IN CRYPTOGAMS
199
Mosses (Bryophyta)
If we have followed carefully the development of marchantia,
the study of one of the mosses will be comparatively easy. The
mosses are more familiar plants than the liver-
worts. They grow on trees, stones, and on. the
soil both in wet and dry places. One of the
common larger mosses, known as Polytrichum
co7}imune, may serve as an
example. Fig. 295. This plant
grows on rather dry knolls,
mostly in the borders of open
woods, where it forms large
beds. In dry weather these
beds have a reddish brown
appearance, but when moist
they form beautiful green
cushions. This color is due,
in the first instance, to the
color of the old stems and
leaves, and, in the second in-
stance, to the peculiar action
of the green living leaves
under the influence of chang-
ing moisture-conditions. The
inner or upper surface of the
leaf is covered with thin, lon-
gitudinal ridges of delicate
cells which contain chloro-
phyll. These cells are shown
in cross-section in Fig. 296, as dots or granules. All the other
tissue of the leaf consists of thick-walled, corky cells which do
Fig. 295. — Polytrichum commune.
_/",/", fertile plants, one on the left in fruit;
;», antheridial plant.
Fig. 296. —Section o-f Leaf or Polytrichum commune.
not allow moisture to penetrate. When the air is moist the green
leaves spread out, exposing the chlorophyll cells to the air, but in
200 BEGINNERS' BOTANY
dry weather the margins of the leaves roll inward, and the leaves
fold closely against the stem, thus protecting the delicate assimi-
lating tissue.
The antheridia and archegonia of polytrichum are borne in
groups at the ends of the branches on different plants (many
mosses bear both organs on the same branch). They are sur-
rounded by involucres of characteristic leaves termed perichcetia
ox perichatal leaves. Multicellular hairs known as /ari7/;^jCJ« are
scattered among the archegonia and antheridia. The involucres
with the organs borne within them are called receptacles, or, less
appropriately, " moss flowers." As in marchantia, the organs are
very minute and must be highly magnified to be studied.
The antheridia are borne in broad cup-like receptacles on the
antheridial plants (Fig. 297). They are much like the antheridia
of marchantia, but they stand free
among the paraphyses and are not
sunk in cavities. At maturity they
burst and allow the sperm cells or
spermatozoids to escape. In poly-
trichum, when the receptacles have
fulfilled their function, the stem con-
FiG. 297. - SECTION THROUGH A tiuues to grow from the center of
RECEPTACLE OF PoLVTRi- the cup (^, Fig. 295 ) . The archc-
CHUM COMMUNE showing gonia are bornc in Other rcceptacles
paraphyses and antheridia. j-cr ^ 1 i mi i-i
on different plants. They are like
the archegonia of marchantia except that they stand erect on the
end of the branch.
The sporogonium which develops from the fertilized egg is
shown in a, b, Fig. 295. It consists of a long, brown stalk bearing
the spore-case at its summit. The base of the stalk is imbedded
in the end of the moss stem by which it is nourished. The
capsule is entirely inclosed by a hairy cap, the calyptra, b. The
calyptra is really the remnant of the archegonium, which, for a
time, increases in size to accommodate and protect the young
growing capsule. It is finally torn loose and carried up on the
spore-case. The mouth of the capsule is closed by a circular lid,
the operculum, having a conical projection at the center.
The operculum soon drops, or it may be removed, displaying a
fringe of sixty-four teeth guarding the mouth of the capsule. This
ring of teeth is known as the peristome. In most mosses the
teeth exhibit pecuhar hygroscopic movements ; i.e. when moist
they bend outwards, and upon drying curve in toward the mouth
of the capsule. This motion, it will be seen, serves to disperse
the spores gradually over a long period of time.
Not the entire capsule is filled with spores. There are no
elaters, but the center of the capsule is occupied by a columnar
STUDIES IN CRYPTOGAMS
20 1
Strand of tissue, the columella, which expands at the mouth into a
thin, membranous disk, closing the entire mouth of the capsule
except the narrow annular chink guarded by the
teeth. In this moss the points of the teeth are
attached to the margin of the membrane, allow-
ing the spores to sift out through the spaces be-
tween them.
When the spores germinate they form a green,
branched thread, the protonema. This gives rise
directly to moss plants, which appear as little
buds on the thread. When the moss plants have
sent their little rhizoids into the earth, the pro-
tonema dies, for it is no longer necessary for the
support of the little plants, and the moss plants
grow independently.
Funaria is a moss very common on damp,
open soil. It forms green patches of small fine
leaves from which arise long brown stalks termi-
nated by curved capsules (Fig. 298). The struc-
ture is similar to that of polytrichum, except the
absence of plates on the under side of the leaves,
the continuous growth of the stem, the curved
capsule, double peristome, monoecious rather than dioecious re-
ceptacles, and nearly glabrous unsymmetrical calyptra.
Fig. 298. — FU-
NARIA HY-
GROSCOPiCA.
Equisetums, or Horsetails (Pteridophyta)
There are about twenty-five species of equisetum, constituting
the only genus of the unique family Equisetacece. Among these
E. arvense (Fig. 299) is common on clayey and sandy soils.
In this species the work of nutrition and that of spore
production are performed by separate shoots from an underground
rhizome. The fertile branches appear early in spring. The stem,
which is 3 to 6 inches high, consists of a number of cylindrical,
furrowed internodes, each sheathed at the base by a circle of scale
leaves. The shoots are of a pale yellow color. They contain no
chlorophyll, and are nourished by the food stored in the rhizome
(Fig. 299).
The spores are formed on specially developed fertile leaves or
sforophylh which are collected into a spike or cone at the end of
the stalk {a, Fig. 299). A single sporophyll is shown at /;. It
consists of a short stalk expanded into a broad, mushroom-like
head. Several large sporangia are borne on its under side. The
spores formed in the sporangia are very interesting and bea'utiful
202
BEGINNERS' BOTANY
objects when examined under the microscope (X about 200).
They are spherical, green bodies, each surrounded by two spiral
bands attached to the spore at their intersection, s. These bands
exhibit hygroscopic movements by means of which the spores be-
come entangled, and are held together. This is of advantage to the
plant, as we shall see. All the spores are alike, but some of Xhepro-
thallia grow to a greater size than the others. The large prothallia
produce only archegonia while the smaller ones produce antheridia.
Both of these organs are much like those of the ferns, and fertili-
FlG. 299. — Equisetum arvense.
st, sterile shoot; f, fertile shoot showing the spike at a ; b, sporophyll, with sporangia;
o', spore.
zation is accompUshed in the same way. Since the prothallia are
usually dioecious, the special advantage of the spiral bands, holding
the spores together so that both kinds of prothaUia may be in
close proximity, will be easily understood. As in the fern, the
fertilized egg-cell develops into an equisetum plant.
The sterile shoots (ji". Fig. 299) appear much later in the season.
They give rise to repeated whorls of angular or furrowed branches.
The leaves are very much reduced scales, situated at the inter-
nodes. The stems are provided with chlorophyll and act as
assimilating tissue, nourishing the rhizome and the fertile shoots.
Nutriment is also stored in special tubers developed on the rhi-
STUDIES IN CRYPTOGAMS
203
Other species of equisetum have only one kind of shoot — a tall,
hard, leafless, green shoot with the spike at its summit. Equise-
tum stems are full of silex, and they are sometimes used for scour-
ing floors and utensils ; hence the common name " scouring rush."
IsoETES (Pteridophyta)
Isoetes or quillwort is usually found in water or damp soil on
the edges of ponds and lakes. The general habit of the plant is
seen in Fig. 300, a. It consists
of a short, perennial stem bear-
ing numerous erect, quill-like
leaves with broad sheathing bases.
The plants are commonly mis-
taken for young grasses.
Isoetes bears two kinds of
spores, large roughened ones,
the macrospores, and small ones
or microspores. Both kinds are
formed in sporangia borne in an
excavation in the expanded base
of the leaf. The macrospores are
formed on the outer and the
microspores on the inner leaves.
A sporangium in the base of a
leaf is shown at b. It is partially
covered by a thin membrane,
the velum. The minute triangu-
lar appendage at the upper end
of the sporangium is called the
ligule.
The spores are liberated by
the decay of the sporangia. They
form rudimentary prothallia of two
kinds. The microspores produce
prothallia with antheridia, while
the macrospores produce pro-
thallia with archegonia. Ferti-
lization takes place as in the mosses or liverworts, and the fertihzed
egg-cell, by continued growth, gives rise again to the isoetes plant.
Fig. 300. — IsoiiTES, showing habit
of plant at a ; b, base of leaf, show-
ing sporangium, velum, and ligule.
Club-Mosses (Pteridophyta)
The club-mosses are low trailing plants of moss-like looks and
habit, although more closely allied to ferns than to true mosses.
Except one genus in Florida, all our club mosses belong to the
204
BEGINNERS' BOTANY
genus Lycopodium. They grow mostly in woods, havirj; i -nerved
evergreen leaves arranged in four or more ranks. Sonie of them
make long strands, as the ground pine, and are much used for
Christmas decorations. The spores are all of one kind or form,
borne in i-ceUed sporangia that open on the margin into t7c>o
valves. The sporangia are borne in some species (Fig. 301)
Fig. 301. — A Lycopodium
WITH Sporangia in
THE Axn.s OF THE Fo-
liage Leaves. (Lyco-
podium lucidulum.)
Fig. 302, — A Ci.uB-Moss
(Lycopodium complanatum) .
as small yellow bodies in the axils of the ordinary leaves near the
tip of the shoot; in other species (Fig. 302) they are borne
in the axils of small scales that form a catkin-like spike. The
spores are very numerous, and they contain an oil that makes them
inflammable. About 100 species of lycopodium are known.
The plants grown by florists under the name of lycopodium are
of the genus Selaginella, more closely allied to isoetes, bearing
two kinds of spores (microspores and macrospores) .
INDEX
Aborted seeds, i66.
Abutilon, 156.
Accessory fruit, 164, i6g.
Adaptation to environment, 6.
Adventitious roots, 36; buds, 114.
Aerial roots, 34.
Aggregate fruit, 168.
Air plants, 35.
Akenes, 165.
Algs, 179. 183, 195.
Alternation of generation, 179.
Anemophilous, 149.
Annual plant, 17.
Anther, 135, 144, 180.
Antheridium, 175, 186, 198, 200, 202,
203.
Apical dehiscence, 166.
Archegonium, 178, 198, 200, 202, 203.
Arum family, 140.
Ash, 92.
Assimilation, 97.
Axil, 112.
Axis, plant, 15.
Bacteria, 39, 109, 182.
Barberry, 157, 193.
Bark, 54, 66, 67.
Bark-bound trees, S4-
Bast, 61, 66.
Bean, 20, 28, 39, 194.
Berry, 167.
Biennial plant, 17.
Brace cells, 67.
Bracts, 134.
Branch, in.
Breeding, plant, 7, 8.
Bryophytes, 181.
Budding, 127, 128.
Bud propagation, 181.
Buds, 72, 82, 87, hi; flower, 115;
fruit, 115.
Burs, 172, 174.
Bushes, 191.
Cabbage, 113.
Callus, 56.
Calyx, 133.
Cambium, 63, 65.
Capsule, 165.
Carbohydrate, 95.
Carbon, 92.
Carbon dioxid, 22, 93, 106.
Carnivorous, 99.
Carpel, 136.
Castor bean, 24.
Catkin, 158.
Caulicle, 20, 22, 23.
Cedar apple, 194.
Cell, 42, 63, 145, 176.
Chlorophyll, 86, 94, loi, 183, 186.
Cion, 125.
Cladophylla, 100.
Cleft graft, 126.
Cleft leaf, 75.
Cleistogamous, 151.
Climbing plants, 129.
Clover, 39.
Club mosses, 203.
Cluster, flower, 155, 159; centrifugal,
^5^1 159; centripetal, 156; inde-
terminate, 156.
Colonies, plant, 11.
Composite flowers, 140.
Conjugation, 185.
Cork, 66, 67.
Corn, 3, 25, 26.
Corolla, 133; funnel form, 138;
labiate, 138; personate, 139; rotate,
138; salver form, 138.
Cortex, 44.
Corymb, 159.
Cotton plant, 7.
Cotyledon, 20.
Cryptogam, 176, iSo, 183-204.
Currant, 157.
Cuttings, 121, 123, 124.
Cyme, 159, 160.
Deciduous, 82.
Decumbent, 50.
Dehiscence, 144, 164.
Deliquescent, 51.
Dependent plants, 106,
Dichogamy, 144.
205
2o6
INDEX
Dicotyledon, 20,
Dicotyledonous stems, 61.
Digestion, 95.
Digitate, 74.
Dimorphous, 144.
Dioecious, 13S, 170.
Dispersal of seeds, 172.
Dissection, 30.
Dodder, t^^, 106.
Drupe, 168.
Drupelet, 168.
Ecology, 14.
Elaters, 198.
Embryo, 26, 180.
Embryo sac, 180.
Endodermis, 44.
Endosperm, 21, 24.
Entomophilous, 148.
Environment, 6.
Epicotyl, 23, 25.
Epidermis, of leaf, 86, 87.
Epxgeal, 23.
Epiphyte, 35, no.
Equisetums, 201.
Essential organs, 135.
Excurrent, 51.
Explosive seeds, 172.
Fermentation, 190.
Fern, 176.
Fertilization, 144; cross, 144, 146;
self, 145, 147, 188.
Fibro-vascular bundles, 61, 90.
Field study, 3, 6, 8, 14, 19, 27, 46, 57,
71, 84, 91, loi, no, 118, 128, 132,
143, 152, 162, 170, 174, 181.
Filament, 135.
Floral envelopes, 133.
Florets, 140-
Flower, 133, 180; apetalous, 136;
clusters, 155; complete, 136; dicli-
nous, 137; double, 142; imperfect,
137; incomplete, 136; lateral, 136;
naked, 136; perfect, 137; pistillate,
137; regular, 138; staminate, 137;
sterile, 137; solitary, 156; terminal,
156.
Foliage, 16.
Follicle, 165.
Forestry, 68.
Framework of plant, 15.
Frond, 176, 178, iSi.
Fruit, 163.
Fucus, 186.
Funaria, 201.
Fungi, 187.
Fungus, 107, loS, 1S4, 187, 195.
Gamctophyte, 179.
Gamopetalous, 134.
Gamosepalous, 134.
Generation of plants, 16.
Geotropism, 44, 47.
Germination, 22, 23, 27.
Glomerule, 160.
Grafting, 125.
Grit cells, 67.
Guard cells, 88.
Gymnosperm, 26, 170.
Hairs, 87.
Herb, 17.
Hilum, 21, 26.
Hip, 168.
Hollyhock, 147.
Homologous, 134, 135.
Host, 107.
Houstonia, 107. i
Hyphse, 107, 188.
Hypocotyl, 22.
Hypogcal, 23.
Indehiscent, 164.
Indusium, 177.
Inflorescence, 155, 160.
Internodc, 52.
Involucre, 34, 141, 163, 164.
Iron, 39.
Isoetes, 203. «
Key fruit, 164.
Laboratory, 3.
Landscape, 13.
Larkspur, 14S, 149.
Latex tubes, 67.
Leaf, apex of, 80; base of, 80; function
of, 92; margin of, 80; structure, 86.
Leaf scar, 90.
Leaves, arrangement of, 82; shapes of,
78, 85.
Legume, 165.
Legume family, 35, 169.
Lenticel, 89.
Lichens, 195.
Ligneous, 17.
Liverworts, 196.
Lobes of leaf, 75.
Locule, T36, 163, 166.
INDEX
207
Loculicidal dehiscence, 166.
Lumber, 68.
Lycopodium, 204.
Macrospore, 203, 204.
Marchantia, 196.
Medullary ray, 64.
Mesophyll, 86.
Micropyle, 21, 26.
Microscope, 21, 26.
Microspore, 203.
Midrib, 77.
Mint family, 139.
Mistletoe, 109.
Mold, 1 88.
Monocotyledons, 20, 25, 63.
Monoecious, 138; 150, 170.
Mosses, 199.
Moss, Spanish, no.
Mullein, 87.
Muscadine, 36.
Mushroom, 107, 194.
Mycelium, 107, 108, 188.
Mycorrhiza, 108.
Natural selection, 8.
Nectar, 148.
Nitella, 187.
Nitrogen, 39, 40.
Nodes, 20, 52.
Nodules, 39, 40-
Nostoc, 184.
Notebooks, 3.
Nucleus, 144, 185.
Nuts, 164.
Oleander, 86.
Oogonia, 186.
Orchid, 35, no.
Oscillatoria, 184.
Osmosis, 42, 48.
Ovary, 135, 144. 163, 170.
Overgrowth, 12.
Ovule, 144, 186.
Palisade cells, 86.
Palmate, 74.
Panicle, 158.
Pappus, 141.
Parasites, 107.
Parenchyma, 60, 86.
Pedicel, 162.
Peduncle, 62.
Peltate, 77.
Perennial, 17.
Pericarp, 164, 165, 169.
Petals, 134.
Petiole, 76.
Phenogam, 177, 180.
Photo-synthesis, 94, loi.
Phyllotaxy, 84.
Pine cone, 27, 170.
Pinna, 181.
Pinnate, 74.
Pinnatifid, 76.
Pistil, 135.
Plantain, 157.
Plant societies, g.
Plants, unlikcncss of, 9.
Plumule, 20, 23, 25.
Plur-annual, 18.
Pod, 164.
Pollen, 135, 144, 180.
Pollination, 144, 145; artificial, 153.
Polypetalous, 134.
Polysepalous, 134.
Polytrichum, 199.
Pome, 169.
Primrose, 140.
Propagation by buds, 121.
Prop-roots, 36.
Proterandrous, 146.
Proterogynous, 146.
Prothallus, 178, 202.
Protoplasm, 42, 94, 97, 185.
Pruning, 105.
Pseud-annual, 17.
Pteridophytes, 181, 201, 203.
Puffball, 194.
Pyxis, 166.
Quarter-sawed, 70.
Receptacle, 134, 163.
Respiration, in plants, 97, 103.
Resting spore, 184, 185, 189, 191, 192.
Rhizome, 52, '202.
Root cap, 44.
Root climber, 129.
Root hairs, 41, 42, 46.
Rootlet, 41.
Root pressure, 99, 104.
Roots, and air, 41; forms of, 32; func-
tion, 38; structure, 38, 43; systems,
32.
Rust, 192,
Samara, 164.
Sap, 67.
Saprophyte, 107, 108.
208
INDEX
Scape, i6i-
Scouring rush, 203.
Scramblers, 129.
Seed, 20, 163, 180; coatj 21.
Selaginella, 204.
Selection, natural, 8; artificial, 8.
Sepal, 133, 169.
Septicidal capsule, 166.
Sessile, 77.
Shelf fungus, 194.
Shrub, 19.
Sieve tubes, 66.
Silicle, 167.
SiHque, 167.
Societies, 9.
Soil, 40, 47,
Soredia, 196.
Sori, 177, 192,
Spadix, 140.
Spathe, 138, 140.
S per mate phytes," iSo.
Spike, 157.
Spirogyra, 184.
Sporangium, 177, 186, 188, 201, 203, 204.
Spore, 176, 178, 181, 184.
Sporophyll, 180, 201.
Sporophyte, 177.
Stamen, 135.
Starch, 95, loi.
Stem, 49; endogenous, 59; exogenous,
61; kinds of, 49.
Stigma, i35j 144, i45-
Stipule, 76, 84.
Stock, 125.
Stomate, 87.
Stone fruit, 168.
Storage of food, 99.
Struggle to live, 4, 6.
Style, 135, 163.
Summer-spore, 191.
Sun energy, 95.
Survival of fittest, 7.
Swarm-spores, 186.
Symbiosis, 196.
Syngenesious, 141.
Teleutospores, 192,
Tendril, loi.
Thallophyte, 181, 184.
Thallus, 184, 197.
Thorns, loi.
Thyrse, 160.
Tillandsia, no.
Timber, decay of, 195.
Tissue, 60, 62.
Toadstool, 194.
Torus, 134, 169.
Tracheid, 65.
Transpiration, 98, 103.
Twiners, 129, 131.
Umbel, 159.
Undergrowth, 12.
Valve, 164.
Variation, :^.
Vaucheria, 186.
Verticellatc, 84.
Water-pore, 88.
Wheat rust, 192.
White weed, or ox-eye daisy, 155.
Whorled, 84.
Willow mildew, 190.
Wind travelers, 173.
Woody fiber, 17.
Wounds of plants, 56.
Yeast plants, 190.
Zygnema, 185.
Zygospore, 185, 189.
GLOSSARY
accessory or reinforced fruits are those in which the ripened pericarp is
combined with other parts, as with the torus or the calyx.
adventitious. Coming by chance or without order, as the sprouts that
arise wliere a limb is cut off.
aggregate fruits are those in which several distinct pistils cohere to
form one body, as in blackberry, raspberry, mulberry.
akene or achene. A one-seeded indehiscent fruit, usually small and
seed-like.
analogous. Like to, in function or use. See homologous,
anemopkilous. Said of flowers that are pollinated by the wind.
annual. A plant that naturally does not live more than one year, as
garden bean, pea, Indian corn, buckwheat, cowpea.
anther. The knob or enlargement of the stamen, bearing the pollen.
antheridium. The male or sperm-cell organ, such as occurs on the
prothallus of ferns and similar plants. See archegonium.
apetalous. Without petals.
apical. At the top.
archegonium. The female or egg-cell organ on the prothallus of ferns
and related plants. See antheridium.
assimilation. The building up of protoplasm from the materials elabo-
rated in the plant.
axil. The angle or place just above the petiole of a leaf (or pedicel of
a flower) where it joins the twig.
berry. In botany, a fleshy pericarp containing a number of seeds, as
current, orange, tomato, grape, cranberry, but not strawberry,
blackberry, raspberry, or mulberry.
biennial. A plant that lives two years. It usually blooms the second
year.
blade. The expanded part of a leaf
bract. A small or much-reduced leaf, often a mere scale.
calyx. The outer row or series in the floral envelope. The outer
" leaves " of the flower, usually green.
cambiuTH. Growth tissue, lying between the bark-part and wood-part
of the fibro-vascular bundle and giving rise to the cells of both.
ii GLOSSARY
capsule. A pod consisting of two or more carpels or parts, usually
opening naturally.
carbohydrate. The compounds of the starch and sugar class.
carpel. One part or member of a compound pistil, or a simple pistil
itself.
catkin or ainent. A raceme-like or spike-like flower-cluster that falls
away after flowering or fniiting, as of willows and staminate flower-
clusters of walnuts and birches.
centrifugal. From the inside out ; as a flower-cluster of which the
inside, terminal, or uppermost flowers open first ; a determinate
cluster.
centripetal. From the outside in ; as a flower-cluster of which the
outer flowers open first ; an indeterminate cluster.
chlorophyll. Leaf green. Chlorophyll is the pigment that gives the
characteristic color to plants.
cladophylla. Stems that look like leaves, and function as leaves, as in
asparagus and the florists' smilax.
cleistogamous . Applied to small flowers, usually hidden beneath the
earth, that are little developed as to floral envelopes, and are self-
fertilized; also to self-fertilization in flowers that do not open.
complete flowers have all the parts, — calyx, corolla, stamens, pistil.
corolla. The inner row or series of flower-leaves, usually colored, and
often of irregular shape. It may be all one piece or of many
pieces.
corymb. A flatfish flower-cluster in which the outermost flowers open
first.
cotyledon. A leaf of the embryo ; seed-leaf. The embryo may have
one cotyledon (monocotyledon), or two cotyledons (dicotyledon),
or sometimes more than two.
cross-fertilization is fertilization by means of pollen produced in another
flower.
cryptogam. One of the group of flowerless or non-seed-bearing plants,
as a fern, fungus, moss, seaweed.
cutting. A shoot planted in soil or water for the purpose of making a
new plant.
cyme. A flattish or broad flower-cluster in which the innermost or ter-
minal flowers open first.
dectc7nbent. Said of branches or stems that lop or lie over on the
ground.
decurrcnt. Said of a leaf that runs down on the stem, thereby not
having a distinct petiole.
dehiscence. The mode of opening, as of a seed-pod or an anther.
GLOSSARY iii
deliquescent. Said of trees in which the leader or main trunk disappears
at the tree-top, forking into several or many main branches.
determinate. See centrifugal.
dichogamy. The condition when stamens and pistils in the same
flower mature at different times ; this prevents or hinders self-
pollination. Sie.& proterandrozis and proterogynous.
diclinous. Said of flowers that are imperfect, — lacking either stamens
or pistils.
dicotyledon. Having two cotyledons or seed-leaves.
digestion. Change in the food materials whereby they may be trans-
ported, or used in assimilation. Starch is changed into sugar in
the plant by a process of digestion.
dimorphous. Of two forms ; as flowers that bear two kinds of stamens.
dicecious. Said of plants that bear stamens and pistils in flowers on
different plants.
drupe. A fleshy pericarp or fruit, containing a relatively large stone or
pit, as peach, cherry, plum.
drupelet. A very small drupe, particularly one comprising part of an
aggregate fruit, as a drupelet of raspberry.
embryo. The dormant plantlet comprising part of the seed. It is
enclosed within the seed-coats. Its parts are the caulicle (or
stemlet), cotyledons or seed-leaves, and plumule. The food may
be stored in the embryo, or around the embryo (endosperm).
endogen. A plant of the monocotyledon class, not enlarging in diam-
eter by means of outside rings ; as palms. All grasses and lilies
and orchids and cereal grains are of this kind. Now used, if at
all, to express a general mode of growth rather than a class of
plants. See exogen.
endosperm. The food material that is packed around the embryo
(rather than inside it) in the seed.
entomophilous . Said of flowers that are pollinated by insects.
environment. The surroundings ; or the conditions in which a plant
or animal lives. The environment comprises the soil, climate, and
the influence of the other plants and animals with which or among
which the plant or animal grows.
epicotyl. The internode or "joint" above the seed-leaves or cotyledons.
epidermis. The outermost layer or part of the cortex ; the skin.
epigeal. Said of seeds (as common bean) in which the cotyledons or
seed-leaves rise above ground in germination. See hypogeal.
epiphyte. A plant that grows on another plant, or on other objects
above ground, but which does not derive much or any of its nour-
ishment from its host ; an air-plant.
IV GLOSSARY
excurrent. Said of trees (as firs and spruces) in which the main
trunk or leader continues through the tree-top.
exogen (see endogen). Of the dicotyledon class, the stem enlarging
by external layers or rings.
fertilization takes place in the flower when a pollen nucleus and an
egg-cell nucleus unite in a forming ovule.
fibro-vasculdr. Bundles or strands of tissue composed of sieve tubes,
mechanical fiber and vessels or ducts.
filament. The stalk part of a stamen.
follicle. A single-cavity fruit or pod opening along its inner edge.
frond. A leaf of a fern and related plants.
fruit. In botany, the ripened ovary- with the attached parts. All
flowering plants, therefore, produce fruits. The term is also used
for the ripened reproductive bodies of flowerless plants.
fruit-dot, sorus. A collection or cluster of sporangia, as in ferns.
function. What a plant or an organ does ; how it works.
gamete. A cell or nucleus that takes part in fertilization.
gametophyte. The stage of the plant (as the prothallus) that bears or
produces the sex organs ; sexual stage of the plant.
gamopetalous . Said of a corolla with the petals united.
gainosepalous. Said of a calyx with the sepals united.
generation. The entire life period of a plant.
geotropism. Turning toward the earth, as the action of the roots.
glomerule. A dense globular or oblong flower-cluster in which the
upper or inner flowers open first.
graft. A cutting inserted in another plant for the purpose of having it
grow there.
gymnosperm ("naked seed"). A name applied to a group of plants
(pines, spruces, cedars, and the like) in which the seeds are not
contained in an ovary.
head. A very dense globular or oblong flower-cluster in which the
outer flowers open first ; often applied to any dense flower-cluster.
herb. A plant that never becomes woody and that dies to the ground,
or dies entirely, in winter.
hilitm. The scar or spot where the seed was attached to its stalk.
hip. The fruit of the rose, which is a hollowed torus containing the dry
fruits or " seeds."
Related to, or with, in origin or structure. Thus, a ten-
dril of grape is homologous with a branch ; a tendril of grape is
analogous to a tendril of pea (similar in function), but not homolo-
gous, for one represents a branch (or flower-cluster) and the other
represents a leaf.
GLOSSARY V
host. A plant or animal on which another organism grows or feeds.
hypha (plural hypha). The threads of the mycelium of a fungus.
hypocotyl. The stem or internode below the seed-leaves.
hypogeal. Said of seeds (as garden pea) in which the cotyledons
remain under ground in germination. See epigeal.
imperfect flowers lack either stamens or pistils.
incomplete flowers lack one of the parts or series, as the calyx, corolla,
stamens, or pistil.
indeterminate. See centripetal.
indiisium. The scale or lid covering a sorus, in ferns and allied plants.
inflorescence. Properly, the mode of flowering (page i6o), but some-
times used in the sense of a flower-cluster.
involucre. A set or whorl of leaves or bracts beneath a flower or a
cluster of flowers ; sometimes looks like an outer or extra calyx.
irregular flowers have some members of one or more of the series unlike
their fellows.
key fruit. See samara,
labiate. Lipped ; that is, divided into parts, as the lips of a mouth.
Said usually of corollas that are lobed into two parts.
lateral. On the side ; as a flower or leaf borne on the side of a shoot
rather than at its end. See tertriinal.
leaflet. One of the divisions or parts of a compound leaf.
legume. Like a follicle, but opening along both edges. In some
cases, as in peanut, the pod does not actually open.
leguminous plants are those that bear legumes or true pods, as peas,
beans, clovers, alfalfa, vetch, sweet pea, peanut, locusts, red-bud.
lenticel. Very small spots or corky elevations on young twigs, marking
the place of former twig stomates.
locule. One cavity or " cell " in a pistil or anther.
loculicidal.... Said of capsules when the carpels or compartments open
between the partitions.
mesophyll. The parenchyma in the leaf.
micropyle. The place on the seed at which the pollen-tube entered
when the seed was forming (when impregnation took place).
monocotyledon. Having one cotyledon or seed-leaf.
monacious. Said of plants that bear the stamens and pistils in different
flowers on the same plant.
vtycelium. The vegetative part of a fungus, composed of threads or
hyphae.
mycorrhiza. A root covered with or bearing a fungus that aids the
root in securing nourishment from the soil.
naked. Said of flowers that lack envelopes (calyx and corolla) .
VI GLOSSARY
nectary. A cup, sac, or place in the flower in which nectar (or
" honey ") is borne.
osmosis. The passing or diffusion of liquids or gases through mem-
branes.
ovary. The lower enlarged part of the pistil, containing the ovules or
forming seeds.
ovule. The young or forming seed.
palmate. Palm-like ; said of venation that arises from the base of the
leaf (top of petiole), or of leaflets similarly arranged.
panicle. A branching raceme. The lower or outer flowers open first ;
but the word is often used loosely.
pappus. The hair, plumes, bristles, or scales on the top of a dry fruit,
particularly of a fruit (or " seed ") of the Compositae or sunflower
family.
parasite. A plant or animal that lives on a living host (as on a plant
or an animal), taking its food from the host. See saprophyte,
parenchyma. The general underlying tissue, from which other tissue
arises. (Word not derived itom parent.)
pedicel. Stem of a single flower in a cluster.
peduncle. A flower stem, supporting a solitary flower or a cluster of
flo~wers.
perennial. A plant that lives more than two years, as most grasses,
docks, alfalfa, asparagus, and all trees and shrubs.
perfect flowers bear both stamens and pistils.
pericarp. A ripened ovary, without counting attached parts.
personate. Masked ; that is, so formed as to suggest a masked face,
in labiate corollas with a large lower lip.
petal. One of the parts or leaves of the corolla.
petiole. Stem or stalk of a leaf.
petiolule. Stem of a leaflet.
phenogam {phanogam, phanerogam) . A seed-bearing plant ; that is,
one of the seed-bearing or flowering group of plants.
phloem. Bark or soft bast tissue.
photosynthesis. The process whereby the carbon dioxid of the air is
appropriated in the formation of material for plant growth.
phyllotaxy. Mode of arrangement of leaves or flowers on the plant or
stem.
pinnate. Feather-like ; said of leaves in which the veins strike off
from a continuing midrib, or in which the leaflets are arranged in
a similar order.
pistil. The innermost member in the flower, bearing the forming seeds.
pistillate. Of pistils only; a flower that contains pistils and no
stamens, or a plant that bears only pistils.
GLOSSARY Vli
plur-anmial. A plant of a tropical or semi-tropical climate that is
annual in a colder country only because it is killed by frost; as
tomato, castor-bean.
pollen. The dust or grains contained in the anther and which, falling
on the stigma, grows and fertilizes the forming ovules.
pollination. The transfer of pollen from the anther to the stigma.
The transfer may be accomplished by wind, insects, birds, water
(in the case of water plants), or by the natural falling of the pollen.
polypetaloas (" many-petaled"). Said of a corolla with the petals not
united.
polysepalous (" raany-sepaled "). Said of a calyx with sepals not united.
poi7te. An apple-like or pear-like or quince-Uke fruit, with a five-car-
peled or ten-carpeled " core."
proterandrous. Said of a flower when the anthers mature in advance
of the pistils in the same flower.
proterogynoiis. Said of a flower when its pistils mature before its
anthers.
prothallus (" first thallus "). The minute leaf-like body or organ pro-
duced by the germination of a spore, in ferns and allied plants.
It bears the sex organs.
protoplasm. The living matter in plants. It is the living part of the
cells, usually in a semi-fluid, translucent state.
pseud-annual. A plant that is apparently annual, but which is carried
over winter by a bulb, tuber, or similar body ; as potato, onion.
pyxis. A dry fruit or capsule in which the top comes off', like a cover
to a jar.
raceme. A simple (unbranched) cluster in which the flowers are on
short pedicels and open from the base upwards.
raphe. A ridge or elevation on some seeds caused by the seed-stalk
and seed-coats growing together.
ray. The elongated corolla-limb of some members of the Compositas
family.
receptive. Said of a stigma when it is " ripe " or ready to receive the
pollen.
regular flowers are those in which all the members of each series (as
all the sepals, or all the petals, or all the stamens) are like each
other in shape, size, and color.
reinforced. See accessory fruits,
respiration. Breathing; manifest by oxygen taken in and carbon
dioxid given off'.
rhizome. A rootstock ; an underground root-like stem. It has joints,
usually scales representing leaves, and is often thick and fleshy.
Vlll GLOSSARY
samara. A key fruit, being an indeliiscent (not opening) fruit provided
with a wing or wings.
saprophyte. A plant that lives on dead or decaying material. See
parasite,
scape. A flower-stem rising directly from the crown of the plant at the
surface of the ground or near it. A scape may have bracts.
self-fertilization or close-fertilization is fertilization by means of pollen
produced in the same flower.
sepal. One of the parts or leaves of the calyx.
septicidal. A form of dehiscence or opening along the natural partitions
of the capsule.
sessile. Sitting ; without a stem, as a leaf without petiole, or a flower
without pedicel or peduncle.
shrub. A low woody plant that does not have a distinct trunk. When
a plant normally has a trunk, it is a tree.
silicle. A short, more or less circular, capsule of the mustard family.
silique. A long capsule of the mustard family.
society. An aggregation or company of plants, comprising a more or
less distinct group.
sorus (plural wr/). 'i^^ fruit-dot .
spadix. A spike of flowers (each flower usually minute), with a more
or less fleshy axis, and usually accompanied by a spathe.
spathe. A corolla-like or involucre-like leaf or bract (or a pair of
them) surrounding or accompanying a spadix. In the calla, the
spathe is the large white flower-like part.
sperniaphyte ("seed plant"). A seed-bearing plant; one of the
flowering-plant class.
spike. A dense and slender flower-cluster in which the flowers open
from below upwards.
sporangium (plural sporangia ; spore-case). A body or receptacle
holding spores.
spore. A reproductive or generative cell ; in flowerless plants answer-
ing the purpose of a seed, but containing no embryo. It may not
be the direct product of fertilization.
sporophyll ("spore leaf"). A member or part that bears spores.
sporophyte. The stage of the plant arising directly from the fertilized
egg, and which ordinarily produces asexual spores (as the " plant "
or conspicuous part of the fern or of a seed-plant).
stamen. The pollen-bearing organ of the flower, of which the essential
part is the anther (usually borne on a stem or filament).
staniinate. Said of a flower that has stamens and no pistils.
stigma. The part of the pistil (usually on a stalk or style) on
GLOSSARY ix
which the pollen germinates ; it is sticky, rough, or hairy at
maturity.
stipel. A stipule of a leaflet.
stipule. A leafy or scale-like appendage at the base of a petiole.
Stipules are usually two in each case.
stomate, stoma (plural stomates^ or stomal a). The openings on leaves
and green parts through which gases pass ; diflfiision-pores or
" breathing-pores."
stone-fruil. A drupe.
strict. Said of a stem that grows straight up, without breaking into
branches.
style. The stalk between the ovary and stigma ; sometimes not present.
syngenesiojis . Said of anthers when they cohere in a ring, as in the
Compositae, the style usually being enclosed.
tap-root. A single or leading strong root that runs straight down into
the earth.
tendril. A slender coiling member of a plant that enables it to climb.
A tendril may represent a branch, a petiole, a leaflet, a stipule, an
entire leaf.
terminal. At the end ; as a flower borne on the end of a shoot. See
lateral,
thyrse. A compound, usually elongated or pyramidal flower-cluster in
which the mode of inflorescence is mixed.
torus. The end of the flower-stalk (usually somewhat enlarged) to
which the flower-parts' are attached; receptacle.
transpiration. Evaporation or loss of water from plants.
umbel. A flower-cluster opening from the outside, in which the branches
or stems arise from one place, as the rays of an opened umbrella.
umbellet. -A small umbel, comprising part of a larger or compound
umbel.
valve. One of the integral parts into which a fruit or an anther natu-
rally splits, or into which it is divided.
venation. The mode or fashion of veining, as in a leaf or petal.
xyleni. Wood tissue.
By L. H. BAILEY
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Botany
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