LIPPINCOTT'S
FARM LIFE TEXT SERIES

EDITED BY

KARY C. DAVIS, PH.D. (CORNELL)

APPLIED
ECONOMIC BOTANY

LIPPINCOTT'S

FARM MANUALS

Edited by
K. C. DAVIS, Ph.D.

KNAPP SCHOOL OF COUNTRY LIFE, NASHVILLE, TENN.

PRODUCTIVE SWINE HUSBANDRY 1915
BY GEORGE E. DAY, B.S.A.

PRODUCTIVE POULTRY HUSBANDRY 1919
BY HARRY R. LEWIS, B.S.

PRODUCTIVE HORSE HUSBANDRY 1916
BY CARL W. GAY, D.V.M., B.S.A.

PRODUCTIVE ORCHARDING 1917
BY FRED C. SEARS, M.S.

PRODUCTIVE VEGETABLE GROWING 1918
BY JOHN W. LLOYD, M.S.A.

PRODUCTIVE FEEDING of FARM ANIMALS 1916
BY F. W. WOLL, PH.D.

COMMON DISEASES OF FARM ANIMALS 1919
BY R. A. CRAIG, D.V.M.

PRODUCTIVE FARM CROPS 1918
BY E. G. MONTGOMERY, M.A.

PRODUCTIVE BEE KEEPING 1918
BY FRANK C. PELLETT

PRODUCTIVE DAIRYING 1919
BY R. M. WASHBURN, M.S.A.

INJURIOUS INSECTS AND USEFUL BIRDS 1918
BY F. L. WASHBURN, M.A.

PRODUCTIVE SHEEP HUSBANDRY 1918
• BY WALTER C. COFFEY, M.S.

SOIL PHYSICS AND MANAGEMENT 1919
BY J. G. MOSIER, B.S., A. F. GUSTAFSON, M.S.

APPLIED ECONOMIC BOTANY 1919

BY MELVILLE T. COOK, PH.D.

LABORATORY MANUAL AND NOTEBOOK

ON THE FOLLOWING SUBJECTS
SOILS, BY J. F. EASTMAN and K. C. DAVIS ms

POULTRY, BY H. R. LEWIS i9tg
DAIRYING, BY E. L. ANTHONY 1917

FEEDING, BY F. W. WOLL wi?
FARM CROPS, BY F. W. LATHROP

Cfl V

H O

o .5

- 1

gfi

FARM LIFE TEXT SERIES

EDITED BY K. C. DAVIS, PH.D. (COKNEU.)

APPLIED
ECONOMIC BOTANY

/,

BY

MELVILLE THURSTON COOK, PH.D.

RUTGERS COLLEGE, NEW BRUNSWICK, N. J.

142 ILLUSTRATIONS

PHILADELPHIA AND LONDON
J. B. LIPPINCOTT COMPANY

COPYRIGHT, 1919, BY J- B. LIP?1NCOFT COMPANY

Electrolysed and printed by J. B. Lippir.cotl Company
The Washington Square Press, Philadelphia. U. S. A.

PREFACE

THERE are already so many text-books on botany that the
author has long hesitated to present another to the educational
public. The study of botany has developed very rapidly in the
past quarter of a century and as a result we have a great variety
of text-books representing an almost equally great variety of
methods of presenting the subject. Yet, we meet with a con-
tinuous series of complaints against the poorly adapted sec-
ondary text-books for teaching in secondary schools, technical
schools and colleges. The teacher in the secondary school says
that text-books are written by college professors who do not
understand the problems involved in secondary education; the
teacher in the technical school complains because the students
from the secondary schools cannot correlate the botany with
related subjects; the college professors complain because of the
mechanical methods used in the secondary schools which dis-
courage rather than encourage further study of the subject by
those who enter college.

Having served for a time as a high-school teacher, the author
has some realization of the difficulties of the secondary schools.
As a college professor he has some appreciation of the keen dis-
appointment felt by those who conduct the Freshman entrance
examinations, and who try to teach botany to the college students
that come to college with ideas of botany obtained from their
training in the secondary schools. By experience, he has learned
that the results of the entrance examinations are fully as un-
satisfactory when the questions are prepared by the high-school
teachers as when prepared by himself.

The placing of the responsibility for this condition is a

vi PREFACE

problem not easily solved. But the writer is inclined to believe
that the secondary school is trying to do too much, trying to do
work beyond the pupils, trying to do work that should be left
for the college. We give the pupils compound microscopes,
which is much like giving them a complete set of surveying
instruments for use in the study of elementary arithmetic. We
try to teach facts when we should teach fundamental principles,
close observation and accuracy. We try to teach scientific names
when we should teach simple methods of experimental work.

In this little work the author has aimed at three things,
viz. : (1) A brief statement of the recognized facts and prin-
ciples concerning plants and plant growth usually given in text-
books for secondary schools. (2) A list of simple exercises and
suggestions for observations which the pvipil can conduct with-
out "great difficulty and which will demonstrate many of the
statements given in the book. (3) A list of questions which are
intended to be suggestive to the pupils and to encourage further
studies.

The title, " Applied Economic Botany," implies first, that
it is intended as a guide to experimental work in the study
of plants, such as should be carried on in any high school,
and second, that it is intended as a preliminary work to the
agricultural studies which are now recognized in many high
schools.

The author has endeavored to make the work so flexible
that it may be used in schools regardless of the amount of time
devoted to the subject, the available laboratory space and equip-
ment. The author has also been mindful of the fact that the
course in botany in the secondary school should meet the needs
of very different classes of pupils — those who study it as one
of the requirements of the curriculum and to whom it must be
primarily a cultural subject, those who study it as a prepara-
tion to agriculture and horticulture, and those who may use it

PREFACE vii

to fulfill one of the college entrance requirements. The same
course can and should serve all of these purposes in the same
manner that the courses in mathematics and English literature
serve those who go direct from the secondary schools into the
trades, or business houses, or professions, or to college.

The manuscript has been submitted to both high-school
teachers and college professors for criticisms and suggestions
and many changes have been made in an effort to meet the
requirements of both classes of teachers, although the general
plan of the work has not been changed.

Many of the illustrations in this book are purely diagram-
matic and are intended as guides and not completed work to be
copied by the pupil ; many others are from drawings made by
the author's students and are such as can be readily made by
most high-school pupils.

A text-book in botany is a guide, and it is neither neces-
sary nor desirable that the class should follow it in all details.
The teacher should select such exercises in this or other books
as may suit the purpose and should make such variations and
additions as may be desirable. Supplementary reading along
the lines of plant geography, and economic botany, observations
in field, forest and stream, and home studies in the growing of
plants should be encouraged. The success or failure of the
course in botany is more dependent on the teacher than on the
books, laboratories and equipment. A good teacher is more
•ncct'Hsary than books, laboratories and equipment. The acquire-
ment of industry, enthusiasm, methods of work, self-reliance,
close observation and accuracy on the part of the pupils are
much more desirable than much of the so-called knowledge that
consists of disconnected or questionable facts.

MEL. T. COOK.
RUTGERS COLLEGE,

NEW BRUNSWICK, N. J.

CONTENTS

PAGE

PREFACE v

INTRODUCTION ix

EQUIPMENT AND METHODS xiii

PART I.— PLANT LIFE

CHAPTER

I. SEEDS AND SEEDLINGS 3

II. ROOTS 18

III. STEMS AND BUDS ; 31

IV. LEAVES 45

V. THE FLOWER ; 54

VI. REPRODUCTION 74

VII. FRUITS AND SEEDS 83

VIII. ANATOMY OF STEMS, ROOTS, AND LEAVES 93

IX. CHEMICAL COMPOSITION OF THE PLANT 105

X. PLANT FOODS AND PLANT GROWTH Ill

XI. THE GYMNOSPERMS ' 121

XII. ECOLOGICAL RELATIONS 126

XIII. FORESTRY 134

XIV. PLANT DISEASES 139

XV. PLANT BREEDING 147

XVI. WEEDS 150

XVII. PTERIDOPHYTES 158

XVIII. BRYOPHYTES 164

XIX. THALLOPHY-HES 169

XX. BACTERIA 177

PART II.— MOST IMPORTANT FAMILIES OF ECONOMIC
PLANTS, WITH SPECIAL EXERCISES

XXI. IMPORTANT FAMILIES OF PLANTS 183

MUSTARD — CRUCIFER.E 185

VIOLET — VIOLACE.E 189

MALLOW — MALVACEAE 191

STERCULIA — STERCULIACE.E 193

FLAX — LINAGES 193

RUE — RUTACEJE 195

ix

X CONTEXTS

VINE — VITACE^E 196

SOAP BERRY — ACERACE^ 198

PEA — LEGUMINOSE.E 199

ROSE — ROSACES 204

SAXIFRAGE — SAXIFRAGACE^; 211

GOURD — CUCURBITACE^E 211

PARSLEY — UMBELLIFER*: 215

MADDER — RUBIACE^E 215

SUNFLOWER — COMPOSITE 216

HEATH — VACCINIACE^E 217

CONVOLVULUS — CONVOLVULACE^E 218

NIGHTSHADE — SOLANACE^E 219

GOOSEFOOT — CHENOPODIACE.E , 221

BUCKWHEAT — POLYGON ACE^E 222

NETTLE — URTICACE.E 223

WALNUT — JUGLANDACE^E 225

OAK — CupuLiFERuE 226

WILLOW — SALICACE^E 227

BANANA — ZINGIBREACE.E 227

LILY — LILIACE.E 228

GRASS — GRAMINE^E 228

XXII. SPECIAL EXERCISES WITH PLANT FAMILIES 234

APPENDIX — REFERENCES.... . 243

INTRODUCTION

BOTANY is a science of the very greatest importance but
one which is frequently misunderstood and neglected in our
educational system. To many people, it means the learning of
scientific names of plants, but this is an incorrect idea. Botany
is neither the study of flowers nor the learning of scientific
names. Botany is the study of plants and plant life. It is of
great importance because plant life is absolutely necessary for
the existence of all animal life, including mankind. We are
dependent either directly or indirectly upon the plants for food,
clothing, building materials, fuel and many other necessaries.
We use plants, or animals which have fed on plants, for food.
Every article of food on the table, except the salt and water,
is derived from plants or from animals which are dependent
on plants for food. We use cotton and linen, and many other
vegetable fibres, for clothing and many other purposes; and
we also use wool and silk which are derived from animals that
have fed on plants. We use wood for building purposes, for
making furniture and parts of tools and implements, and for
the making of paper pulp. We use wood and coal and oil,
which are derived from plants, for fuel. And finally, we go
to the plants for about 90 per cent of the drugs to relieve our
aches and pains and restore us to health.

When we once realize our absolute dependence on plant life,
we also begin to think something about the number of industries
that are dependent on plants. The farmers, the horticulturists,
the gardeners, the florists and the foresters are not the only
people who are dependent on plants for a livelihood. Practically
all manufacturing industries are dependent on plants in some
form; for fuel if for nothing else. Even the electric establish-
ments must use fuel to run the machinery for the generation of

xii INTRODUCTION

electricity. When we think of these things we wonder why it is
that man has not given more attention to this primary source
of life, health, wealth and happiness; why he has not given
more attention to increasing it. The answer lies in the fact that
nature is good to us; nature has supplied man with the neces-
saries and more, and man has been satisfied. f But with the in-
creasing population it will become more and more necessary for
man to study plants and plant life and to learn the secrets of
nature which will enable him to increase the production of val-
uable plants.

Plants have influenced the migration of man. In the
account of his journeys of discovery and exploration he has
always given much attention to the character of the plant life.
And most of the permanent settlements of importance have
depended on the character of the plant life and the possibilities
for agriculture. Big factories may have been located where
the water power was good, but they must also be accessible to
the raw materials to be used ; or they may have been located near
the great beds of coal, oil or natural gas and in that case they
were dependent upon the plant products of past ages. How-
ever, the great migrations of the world have always been along
the lines of great plant growths, and the early settlements in
America and the rapid progress of the American people, with
which you are familiar, are ample proofs of these statements.

But this is not all ; the great joy of life is in life itself. To
fully enjoy the life within us we must take pleasure in the life
around us. The joy of the country, of the forests and plains,
the mountains and valleys, of the parks and gardens, is not only
in their beauty but in the appreciation of the value of the plant
life which makes them beautiful.

Botany cannot be studied like most subjects; it does not con-
sist in committing facts. It cannot be learned from books, for
there is no botany in books. Books contain a few plans and
methods for study; a few records of observations and studies

INTRODUCTION xiii

already made; a few facts already learned. The plans and
studies may be changed to-morrow ; the records of observations
and studies will be increased; and many of the supposed facts
may prove to be errors and be supplanted by other statements.

No, we must not study books ; we can use the books as guides,
but we must study the plants themselves. Louis Agassiz said,
"Study Nature, not Books" ; and in studying botany, we should
study the nature of plants and not the nature of books. In this
brief work we can give but very few of the best known and
simplest plans and methods for study and a very brief state-
ment of facts. Many volumes have been written on botanical
subjects, and botany is now recognized as well worthy of the
time and attention of the most learned men and women of our
age. When we compare the knowledge that we have of plant
life with the many problems of plant life yet unsolved we
realize that we know but very little of the subject. Plant life
lends itself so readily to observation and study that the pupils
of a beginning class may quickly learn many things not recorded
in your text-book.

The first question that you ask when you see a strange
plant is, what is its name ? We learn to know plants by their
common names, but the common names used in one part of the
country may be entirely different from those used in another
part, and, of course, the common names must be different in
different languages. Therefore, it is necessary for the botanists
to use scientific names (mostly Latin) which will be the same
in all parts of the world and in all civilized languages. But
these names must also show something else, they must show the
relationship of plants. This working out of the relationship and
classifications of plants is known as systematic botany or tax-
onomy. This subject will bo considered again in Chapter V.

But this is only one phase of botany. We should know
something of the structure of plants, of the parts of which they
are composed. This study involves the comparison of the

xiv INTRODUCTION

different parts of the plant aiid the comparison of the parts of
one plant with those of another kind, it is known as morphol-
ogy and will be the basis of much of our study.

But there is still a third phase of botany, the studies of the
activities of plants, their methods of securing food, their growth,
their reproduction and their behavior in general. This is
known as plant physiology and will also be the basis of much
of our study. Let us always remember that plants are living
things just as much as animals are living things and should be
studied as such.

Therefore, we may say that there are three great divisions of
botany, TAXONOMY, MOKPHOLOGY and PHYSIOLOGY. However,
we have made many other divisions of the subject which are
more or less artificial, but which are very convenient for study.
The most important are: Agricultural botany, horticultural
botany, floriculture, forestry, plant pathology, pharmaceutical
botany, plant geography and many other divisions to please the
individual workers. But they must all depend 'on some one,
two or all of the three great divisions. We will give some
attention to them later.

There is much to be gained in the study of plants that is
more far-reaching, than the subject of botany. After all, our
education consists more in training than in facts learned. We
cannot, in the short time allowed to the subject, expect to learn
much about many thousands of plants, growing under the varied
conditions found in. the different parts of the world, but we can
le,arn certain principles of plant growth. We can also learn to
ibe close observers of both the plant and animal life around us
and we can also learn to be accurate in our observations, in. our
experiments and in making records. If we learn close observa-
tion and accuracy in our work we will have gained a training
well worth all the time devoted to this subject ; a training which
will be helpful in any future trade, business or profession that
we mav enter.

EQUIPMENT AND METHODS

THE necessary equipment for a course in. botany will vary
with the time devoted to the subject and the available labora-
tory space. If you do not have a laboratory, many interesting
studies can be made and experiments conducted in the ordinary
school-room.

The simplest possible equipment is a good pocket knife, a
small hand lens, a note-book suitable for drawings and records
and a reasonably hard lead pencil.

To this equipment may be added ilower pots, tin cans, bot-
tJf-s, glass jars, glass and rubber tubing, boxes, seeds, bulbs,
fruits, vegetables, living plants, sands and soils. The amount
and variety of supplies of this kind will depend on the available
space for the work. Practically all of these supplies can be
secured from the local merchants or collected in the vicinity.

The laboratory should be well lighted and properly heated
both day and night, and should be supplied with tables, shelves,
water and a dark room.

The library should contain as good a supply of text-books on
general botanical and agricultural subjects as is possible to
secure. The daily work should always lie supplemented with
readings on botanical subjects. The study of botany may be
correlated with many other subjects, especially chemistry,
physics, geology, soils, geography, agriculture, horticulture, gar-
dening, agronomy, meteorology, and history.

The indoor studies should always be supplemented by out-
door studies. Walks in the parks or country after school hours,
or on a Saturday, will prove exceedingly advantageous. The
growing of plants at home, the determining of the number of
different kinds of trees in a piece of woodland, along a street or
in a park are usually both interesting and helpful.

xvi EQUIPMENT AND METHODS

The number of dissecting and compound microscopes will
depend on the number of pupils and the time allotted to the
subject. Secondary schools have but very little use for micro-
scopes and can get along very nicely without them. They should
not be used except for the demonstration of a few points 011 the
structure of the plants. It is far better that the pupil have a
good understanding of a few fundamental principles of plant
growth than a poor understanding of plant structure.

There is no hard and fast line between botany and agricul-
ture and horticulture, and in the agricultural high schools it
may be found desirable to merge these subjects into a continu-
ous course on plant studies, but neither the teacher nor the pupil
should ever lose sight of the fundamental principles of plant
growth. Study plants and plant growth first and agriculture
and horticulture will follow in due course.

The sciences are the most variable subjects taught in our
schools; new discoveries cause continuous change of views and
methods and present new lines of thought Although botany is
in some respects the oldest of the sciences the fact that its great-
est developing has been within the last quarter of a century
makes it the youngest. These facts explain the great diversity
of opinion as to the importance of the subject, the t;me devoted
to it, and the amount and character of equipment.

The author fully appreciates that no. teacher can dictate
methods of teaching botany to another teacher, but suggestions
may be given which are well worth consideration. The first
suggestion that the author makes is that the pupils should recog-
nize the importance of the subject. Botany should appeal to
the every-day life of the students • the pupils learn to read, that
they may read not the one exercise at the set period, but that
reading may be used bv them for pleasure and business in every-
day life; they lea»ri arithmetic not for the class period but that
it may serve them in their vocational work ; and thev should

EQUIPMENT AND METHODS xvii

study botany with the idea that it is to be of future use, that
it may help to earn a livelihood, that it may contribute to the
joy of living.

Botany should be taught differently from most subjects.
History may be more or less complete, truthful records and de-
ductions ; mathematics may be exact ; but natural science implies
doubt, and the pupils should approach the experiment with
doubt' and with the determination to secure an lionest result.
Of course, the pupil cannot be expected to test every statement
in the literature, most of these experiments must be left for
another and more advanced worker ; but doubt is one of the solid
foundation stones of scientific work. No one will ever fully
appreciate or enjoy any science who does not approach the sub-
ject armed with an interrogation point.

The order of the subjects and experiments will depend on
the pleasure and judgment of the teacher. It is not always
necessary to follow the outline given in this or any other book.
Begin with any topic to suit your own ideas. Most teachers will
find it desirable to work from the known to the unknown, but
the problematical side should be kept clearly in view. The
experiments should be prepared with the greatest possible care
and accuracy; and originality in apparatus and method should
be encouraged. The interpretations and conclusions drawn by
the students should be carefully guarded by the teacher. As
much attention should be given to the control or check as to the
experiment itself. The records should be full and complete and
both drawings and records should be accurate and neat.

Mechanical methods, the rock on which nature study was
wrecked, should be avoided. All work should have an objective.
Devise or select exercises from other books, use other materials
than those suggested, or any and all other possible methods to
prevent " rule of thumb " work.

One of the oldest devices in teaching botany was the making

xviii EQUIPMENT AND METHODS

of collections under the belief that the pupils would thus learn
to know plants. It is not necessary to explain the shortcomings
of this method to any who have tried it. We all appreciate
the importance of having pupils know the common plants, but a
knowledge of the laws of plant growth and of the relations of
plant groups is of much greater importance than scientific
names. Collections should be made in the same manner as
experiments, i.e., with an objective. Collections illustrating
certain groups of plants or a certain number of groups, or of the
plants of a locality, or of the economic plants, or of the plants
used in certain industries may often be made with great profit.
Additional work for the bright and willing students is let
be encouraged. Pupils with a love for the work will do much
more than the requirements and are the real joy of the teacher.

PART I

PLANT LIFE

APPLIED
ECONOMIC BOTANY

CHAPTER I

SEEDS AND SEEDLINGS

THE seeds of a plant are such familiar objects that most of
us fail to appreciate their very great imp'ortance. Of course,
we know in a general way that a new plant may come from a
seed and that the seeds of this new plant will produce other
plants. We also know that the seeds of many plants are used
as food by man and beast. However, few people have any very
clear ideas of the structural or chemical characters which make
the seeds of some plants valuable for food while the seeds of
others are useless for this purpose. Neither do they have a
very clear conception of the parts of the seed which produce the
parts of the young plant and the conditions necessary for their
development. Let us examine and compare a few seeds and
try a few experiments with the seeds of different plants to
determine these points.

Parts of a Seed. — The seed is a young plant and its food
supply. It is in a dormant or resting state and is waiting for
the necessary conditions before growing into the form generally
recognized as a living plant. The most important parts of a seed
are, (a) a miniature plant known as the embryo and which
under certain conditions will develop into a full-grown plant ;
(6) an ample supply of exceptionally nutritious food for the
nourishment of the new plant or seedling until it becomes self-
supporting; and (c) the necessary protective covering (Figs.
1, 2 and 3).

The little plant within the seed is complete in itself. It pos-

4 SEEDS AND SEEDLINGS

sesses all the organs of a mature plant ; root, stem and leaf. All
the other parts of a plant with which we are familiar, such as
flowers and fruits, are modifications of these primary organs.
The food within the seed is especially well suited for nourishing
the young plant during the early stages of its development and
under favorable conditions of warmth and moisture is readily
utilized for this purpose. The highly nutritious character of

FIG. 1.— a, diagrammatic under-aide view of a grain of corn showing the embryo (em) and
the layers of food; b, longitudinal section of corn showing same parts; c, cross-section of
gram of corn showing the same parts.

this stored food makes many seeds, such as corn, wheat, oats,
beans and peas especially useful as food for man and animals.
(Chapter IX.) The outside coverings' of different kinds of
seeds are extremely variable in character and have many modi-
fications, some of which aid in their distribution. These points
will be discussed later. (Chapter VII.)

Two Classes of Seeds.— Seeds are extremely variable in
size, shape and color, but they can be readily grouped into two
main classes, monocotyledons and dicotyledons, dependent on
whether they possess one or two cotyledons or primary leaves.
These cotyledons are easily recognized in most large seeds, such

STORAGE OF FOOD

as the bean, which is made up almost entirely of two large
cotyledons. These two classes include all the true flowering-
plants which are frequently referred to as monocots and dicots,
or mono and dicotyledonous plants. Our common Indian corn
is a good example of the first and the common bean of the second
of these groups.

Storage of Food. — There are two general types of storage
of food in seeds. In some seeds the entire food supply is to

FIG. 2. — Seed of lima bean; a, b, showing micropyle (mi) and hilum (h); c, with seed
coat and one cotyledon removed showing root hypocotyl (hy) and plumule (pi) ; d, germination.

Fia. 3. — Seed of caator oil plant; a and b, upper and lower surfaces; c, after removal of the
seed coat; d, e, cotyledon showing leaf characters.

be found in the cotyledons, as in the case of the bean (Fig. 2),
while in others the food is found in the cells which immediately
surround the little embryo plant, as in the corn and the so-called
castor bean. (Figs. 1 and 3.) Tn, these latter cases the cotyle-
dons frequently serve as organs through which the stored food

6 SEEDS AND SEEDLINGS

passes to the young growing plant. In some seeds, of which
corn is a good example, the only apparent function of the coty-
ledon is for absorption of the stored food, but in the castor bean
the cotyledons serve first for absorption and later as foliage.
In some seeds the cotyledons serve for storage only, but in others
they serve for storage and as the first leaves.

The corn, bean and castor bean are most excellent types for
study. They are easily secured, large and easily handled, and
possess all the characters commonly found in seeds. They illus-
trate all the preceding points concerning cotyledons and food
supply.

A grain of corn is flat, almost triangular in shape and has
a depression or groove on one side. Lying beneath this groove
is the little embryo plant with its root turned towards the point
of the grain, and the stem and cotyledon towards the large end.
The embryo plant is almost surrounded by the tip or endosperm
starch. The remainder of the grain is made up primarily of
starch, which is covered with a thin layer of gluten and a thin
membranous, horny coat. The corn is not a simple seed in the
same sense that the bean is a simple seed. You will recall that
the bean seed is removed from the pod. But the grain of corn
is not taken from a pod. In fact, the thin membranous horny
coat just referred to is the pod which adheres to the seed cover-
ing or seed coats. Therefore, the grain of corn, as we shall learn
later, is not a simple seed, but a fruit. The grain of corn con-
sists of the embryo plant, surrounded by the stored food and en-
closed in a thin membranous covering consisting of the united
seed coat and pod. The grains of wheat, oats and other grasses
possess similar characters. (Fig. 1.) The embryo consists
of a single cotyledon (or primary leaf), a short stem and a
short root.

The seed of the bean is very different from the grain of corn.
The two large fleshy parts are the cotyledons and since there
are two of them it is a dicotyledonous seed. They are the

CONDITIONS FOR SPROUTING 7

primary leaves and they also contain the food supply. They are
united by a very short embryonic stem, known as the Tiypocotyl
(i.e., the part below the cotyledons). Of course, this hypocotyl
is very short, but from one end arises the primary root, which
is known as the radicle, while at the opposite end we find the
minute bud known as the epicotyl (i.e., the part above the
cotyledons). These parts are covered by the seed coats which
show certain markings. The scar, marking the point of attach-
ment, is known as the hilum. On one side of this hilum we
find a slightly raised ridge known as the raphe and on the other
side we find a minute opening known as the micropyle. (Fig. 2.)

The seed of the castor plant is dicotyledonous like the bean,
but the food is stored as an endosperm around the embryo, as
in the case of the corn, instead of in the cotyledons, as in the
bean. The arrangement of the various parts of the embryo is
the same as in the bean, but the cotyledons are very thin and
show their leaf-like character very distinctly. The entire em-
bryo is surrounded by the food supply which is enclosed within
the seed coats. At the tip of the seed there is a mass of spongy
material, covering the hilum. It is called the caruncle and will
be discussed later. (Page 12.) The embryos of monocoty-
ledonous seeds are usually smaller than those in dicotyledon-
ous seeds. The food supply in the former is always found sur-
rounding the embryo, while in the latter it may be either around
the embryo or in the enlarged cotyledons. Embryos in .which
the food is in the cotyledons are usually more advanced in their
development before ripening than those in which the food sur-
rounds the embryo. In the former the embryo has absorbed
its food supply before ripening, while in the latter it must be
absorbed during germination. (Fig. 3.)

Conditions for Sprouting — When the seeds of most plants
are ripe they can be stored in a dry place and kept for a long
time, and then used for planting. But of course, the seeds of

8 SEEDS AND SEEDLINGS

the uncultivated or wild plants are not stored, they remain weeks
or months exposed to the weather and when the conditions are
favorable they germinate readily and grow. The seeds of some
plants will grow immediately, but the seeds of most plants will
not grow until they have passed through a period of rest. The
seeds of many plants will not sprout unless subjected to the
action of frost. This is especially true of many nuts and the
seeds of some other forest trees. The seeds of some water plants
remain in the water for long periods of time before sprouting.
When the seeds of a plant have undergone their proper period
of rest and have been brought either by nature or by man into
favorable conditions of irnnnlh, and moisture and air they show
signs of life and the embryo plant resumes its growth ; that is,
it increases in size and is very soon readily recognized as a
young plant. During the early stages of its growth, the young
plant lives on the food which is stored in the seed. By the time
this supply of food is exhausted the young plant is sufficiently
well developed and established to manufacture its own food from
raw materials that are secured from the soil and air. The
three most essential factors for the sprouting of seeds are
warmth, moisture and oxygen of the air.

Warmth. — The most favorable temperature for most garden
and field seeds ranges from 85 to 95 degrees, Fahrenheit, but
it is not the same for all plants. Some seeds sprout much earlier
in the season than others, while some weeds sprout in the sum-
mer or fall and pass the winter as growing plants instead of
being stored until spring. The farmer has long ago learned the
best time for his various crops. Winter wheat, clover and
grasses are sown in the fall ; corn, oats and many other seeds in
the spring.

We all know that seeds cannot sprout without water, al-
though a very small amount is necessary for the sprouting of
some seeds. The 'dry seeds of some plants may be kept for

MOISTURE

9

long periods of time, but when placed in moist surroundings
they absorb water rapidly and in great abundance, swell and
sprout very quickly.

Oxygen from the air is also of very great importance in the
sprouting of seeds. Even when seeds are supplied with the
proper warmth and the proper amount of water but deprived of
oxygen they will not grow.

Fio. 4. — a, Longitudinal section of corn seed showing the embryo; b and c, the germi-
nating seed showing the emergence of the root and plumule, the formation of rootlets and
root-hair.

Moisture. — However, it is possible for the seeds of some
plants to have too much water, which will affect the tempera-
ture and interfere with the plant securing the necessary oxygen.
In fact, the little embryo plant may be smothered or drowned
in very much the same manner as an animal may be killed
when submerged in water, but of course it requires more time.
Every farmer knows that land for certain crops must be well
drained and that too much rainfall in the spring interferes
with proper germination, causes grain to rot in the field, and
causes those plants that survive to be yellow and weak.

10

SEEDS AND SEEDLINGS

Sprouting Process. — When the seed sprouts the root and
stem of the embryo plant elongate, the one growing downward
and the other upward ; in some seeds the cotyledons remain un-
derground as in the case of the corn and the pea (Figs. 4 and 6) ,
while in other young plants the cotyledons are carried above
ground as in the case of the squash and the bean. (Figs. 7 and
8.) It is very important that seeds should not be planted too

FIG. 5.

FIG. 6.

FIG. 5. — Bean seedling showing cotyledons and first leaves.
FIG. 6. — Pea seedling. The cotyledons remain below the ground.

deep, but this is especially important in the case of those seeds
which lift the cotyledons above the ground. The raising of the
cotyledons above the ground is due to the elongation of the stem,
and deep planting requires unnecessary growth and tends to the
production of a weak plant.

The cotyledons are the first leaves of the young plant and
when raised above ground they perform the duties of foliage
(Figs. 5, Y and 8), which will be described later. (Page 11).
We have already learned that they may also serve as storage

SPROUTING PROCESS 11

for food (Figs. 4-8) for the young plaiit; but they may also
have a third function, that of absorption, as illustrated by the
germinating corn. (Fig. 4.) In the corn the single cotyledon
has been so modified that it serves as a special organ (known as
the scutellum) through which the food passes from the endo-
sperm of the grain to the embryo. The pea (Fig. 6) and
numerous other seeds never raise their food-laden cotyledons
above ground, but draw the nourishment directly from them,
or through them from the surrounding parts of the seed. In
the bean, squash and related plants, the cotyledons serve for
storage and also as first leaves for a short time. The cotyledons
of the squash (Fig. 7) persist for a much longer time than those
of the bean (Figs. 5 and 8) and show their leaf -like character
much better. The cotyledons of the castor bean (Fig. 3) serve
first, for the absorption of the stored food and, later, as the
first leaves. It is very evident that in most plants the leaf
characters of the cotyledons vary in proportion as they serve
for foliage or for storage. However, it should be remembered
that their leaf characteristics vary somewhat from those of the
leaves which are formed later.

The very rapid sprouting of seeds is partly due to certain
peculiar substances known as enzymes or ferments. These sub-
stances are usually produced inside the cells and serve to digest
or make soluble or otherwise modify the food which is stored
within the seeds, thus making it available for the young plant.
Probably the most important of these ferments is known as
diastase, an enzyme which changes the starch into sugar in
very much the same manner as the ptyalin of the saliva in our
own mouths changes starch into sugar. The starch is only
slightly soluble in water, but the sugar is readily soluble and
therefore becomes an important factor in plant growth.

By the time the supply of stored food is exhausted the young
plant has a fairly well developed root, stem and leaf system

12 SEEDS AND SEEDLINGS

enabling it to carry on an independent existence. We will
study the root, stem and leaf in the succeeding chapters.

The seeds of some plants retain their power to germinate
much longer than those of others. The harvesting of seeds be-
fore they are fully ripened is one of the most common causes
of loss of vitality, but there may be other factors which tend
to injure seeds. These facts make it very important that seeds
should be tested and their power of germination determined
before planting. (Chapter XVI.)

Germination means the growth or enlargement of the young
embryo of the mature seed. We have learned that this occurs
under the proper conditions of moisture, temperature and air.
The young plant may be considered a seedling until it has used
the supply of stored food, and thus becomes an independent
plant, drawing its food from water, soil and air.

Since we have three types of seeds it is very probable that
we will find three or more types of germination. If we examine
the seed of the bean again we will find a very minute opening
near the hilum. It is the micro pyle (Fig. 2 a and &) through
which the water passes very readily. If the micropyle is closed
by wax the absorption of water will be much slower. The
embryo gradually enlarges and the first evidence of growth
that we see is the elongation of the radicle, which breaks through
the seed coat near the hilum and turns downward. The con-
tinued enlargement of the cotyledons and plumule forces the
seed coats off and the rapid elongation of that part of the stem
below the cotyledons carries them above the surface of the soil.
This elongated stem is not straight at first, but gradually appears
above the soil in advance of the cotyledons as a loop which
later becomes erect. (Figs. Y and 8.)

The seed of the castor plant (sometimes improperly called
castor bean) has a small mass of spongy substance (caruncle)
(Fig. 3 a and &) covering the hilum through which the water

GERMINATION

13

is absorbed and passed on to the other parts of the seed. The
taking in of water causes both embryo and surrounding food (en-
dosperm) to swell and the seed coat to crack lengthwise. The
appearance of the radicle through or near the hiluin is again

/Si.

FIG. 7. — Different stages in the germination of the squash.

our first evidence of germination, followed by the elongation
of the hypocotyl and the lifting of the cotyledons above the sur-
face of the soil very much as in the case of the bean. How-
ever, the seed coats persist much longer than in the bean and the

FIG. 8. — Bean seedling coming through the soil.

food is gradually absorbed by the cotyledons. As the food dis-
appears the cotyledons gradually become green and leaf-like in
appearance and function. They usually fall early, but are
sometimes retained for a long time.

14 SEEDS AND SEEDLINGS

The first evidence of germination in the corn (Fig. 4) is
the emergence of the root sheath enclosing the root which soon
pushes through at the tip. This is quickly followed by the
formation of side roots which really arise from the stem. Imme-
diately following the emergence of the root sheath, the coni-
cally rolled leaves (plumule) push out from the opposite end
of the groove and grow upward. The single cotyledon acts as
an organ of absorption, the same as in the castor oil seed but
does not rise above the surface of the soil and take on foliage
characteristics.

The primary root elongates rapidly and produces an abun-
dance of minute root-hairs (Pages 25 and 26), which serve for
the absorption of water and nutriment from the soil. The stem
elongates and new leaves are produced.

We have seen that the cotyledons serve different functions
in different seeds; i.e., for storage, for absorption and for fol-
iage. A careful study of the characters of the seeds of a large
number of plants and their germination will prove both instruc-
tive and interesting.

EXERCISES WITH SEEDS AND SEEDLINGS

1. Take a few dry beans and a few that have been soaked in water
for three or four hours. Note the shape, the point of attachment (hilum)
and the small opening or micropyle near it. Remove the seed coats and
note their horny character. Note the two large' cotyledons ; they are con-
nected by the short radicle which gives rise to the first root and the first
stem or hypocotyl. Note the plumule or first bud lying between the two
cotyledons, just above and attached to the radicle. Make drawings or
diagrams, to show all these points.

2. Castor Bean Seeds. — Examine a few castor beans and compare with
the beans. Note the thick bodies (caruncles) at point of attachment. Re-
move the seed coats. Make a careful examination and locate the embryo.
Compare the cotyledons with those of the bean and note that they are thin
and leaf-like. Note the character of the surrounding material. In what
way is this seed like the bean? How is it different? Make drawings or
diagrams and label the parts.

EXERCISES WITH SEEDS 15

3. Corn Kernels. — Take a few dry grains of corn and a few that have
been soaked in water for a few hours. Hold each grain with the groove
towards you and the point or cap downwards. Note that it is covered
with a thin horny coat which can be removed. Within the groove is the
young plant or embryo with the root pointing downward. The stem
is partly surrounded by a single leaf or cotyledon The entire embryo
is surrounded by starch. The remainder of the grain consists primarily
of two other forms of starch varying in amount in the different varieties.
Cut some of the grains lengthwise and some in cross* section, and examine
the relationship of the various parts. Make a series of drawings or
diagrams to show the preceding points.

4. Write a comparative description of these three types of seeds.

5. Examine a number of other seeds and group them with some
of the above groups or types.

C. Absorption of Water. — Weigh a small quantity of dry seeds,
place in water for a few hours and weigh again.. What is the percentage of
loss or gain in weight?

7. Fill a tall bottle or tube with dry seeds and add enough water
to cover them. Mark the level of the water at the end of one, two, three,
four and five hours respectively. Explain.

8. Fill a test tube or a bottle or a glass fruit jar with dry beans, tie
a strong cloth over the top and immerse in water over night What is the
result? Why?

9. Remove the seed coats from a quantity of dry beans and weigh
without the coats; weigh out an equal amount of dry beans without
removing the seed coats. Put the two lots in water for one hour. Compute
changes in weight. Put in water for an additional hour and again com-
pute changes in weight Explain.

10. Take two lots of dry beans of equal weight. Cover the micropyles
of one lot with varnish or shellac and put both lots in wet sand for two
hours. Weigh each lot and compute, changes in weight. Explain.

11. Germination. — Plant a quantity of corn, beans, peas, melon,
squash, cucumber and such other seeds as may be desirable, in clean sand.
Remove a few seeds at intervals of three or four days. Make drawings,
label the parts and write descriptions and comparisons. (Or, plant the
seeds at intervals of three or four days for two or three weeks and then
study the seedlings at various stages of growth at the same time. )

12'. Cut a small slice off one side of several grains of corn. Ger-
minate these with an equal number of uninjured grains between sheets of
blotting paper. Is there any difference in time of germination? Why?

13. Influence of Moisture, Heat and Light. — (a) Plant two or three
kinds of seeds in wet sand in a flower pot and keep in. a warm, well-lighted
place.

16 SEEDS AND SEEDLINGS

(6) Plant as in (a) but keep in a warm, dark closet.

(c) Plant as in (a) but keep in a cool, well-lighted place.

(d) Plant as in (a) but use a glass vessel instead of a flower pot,
completely cover with water and keep in a warm, well-lighted place.

Examine; all the above from time to time to determine the moisture,
heat and light requirements. Write an account of results with
explanations.

14. Plant seeds in a pot, keep well watered in a warm place, but
covered with a box permitting the entrance of light from one direction.
(The interior of the box should be painted black.) Note the direction of
growth of the various parts. Explain.

15. Work of Cotyledons. — Plant several beans in a pot and keep in
favorable condition for germination. As soon as the seedlings appear above
the surface remove one cotyledon from each of one-third of the plants, and
both cotyledons from each of one-third of the plants. Take note on the
growth of the three sets of plants for several days. Explain difference.

16. Water Requirements for Growth. — Select two flower pots of the
same size and weight. Cans with holes in the bottoms may be used. Secure
enough garden soil to fill them; sift to remove all pebbles and mix thor-
oughly to secure uniformity of character. Fill the two pots with equal
amounts (by weight) of soil. Plant six or more kernels of corn in one
and set both in a warm, light place.

17. Set an ordinary piece of Avindow glass in one side of a deep box.
Fill the box with soil and plant seeds at various depths against the glass,
so that their growths can be observed from the outside. Cover the glass
with black cloth or paper, so that it can be easily removed for observation.
Supply the necessary amount of water, keep hi a warm place and note the
germination and growth from time to time. What is the proper depth for
planting seeds of this kind?

18. Partly fill a cigar box with wet sand. Cover the sand with a cloth
that has been ruled into squares. Place a, certain number of seeds in each
square. Cover with a wet canton flannel cloth, and put in a warm place.
Examine after forty-eight hours and estimate the percentage of germina-
tion. Make a second estimate after ninety-six hours. (This experiment
should be tried with a number of different kinds of seeds from various
sources.) How can seedj testing be made of advantage to the farmer?

19. Put a few beans and a little water in each of two bottles. Fill
one bottle with oxygen and the other with any other kind of gas. Close
both in such a manner as to prevent the escape of idle gas. Note the
germination.

20. Gas Formed During Germination. — Put a few beans and a lit-,
tie water in each of two bottlos. Stopper one with a good cork and leave

QUESTIONS 17

the other open. After 24 hours test both with a burning match. What
is the result? Explain.

21. Repeat, but instead of testing with a match pour a little lime water
into each. What is the result? Explain.

QUESTIONS

1. What are the three most important parts of the seed?

2. W'hat are the parts of the embryo?

3. Why are the seeds of many plantsi valuable as food for man and
animals?

4. Make a list of seeds used for food by man.

a. What are the two main classes of seeds and what are their
characters ?

(i. In what part or parts of the seed is the food stored?

7. What are the functions of the cotyledons'.'

8. What are the hypocotyl, the radicle, the epicotyl, the hilum, the
raphe, the micropyle, and the caruncle?

9. What are the necessary factors for seed germination?

10. Make a list of seeds that are planted in the spring*

1 1. Make another list of seeds that are planted in the fall.

12. What does the sprouting seed obtain from the air?

13. What is the effect of too much water on field crops?

14. When a seed sprouts, what part cornea through the seed coat
first ?

lf>. When corn sprouts, what part is the first to appear above ground?
10. When a bean sprouts, what part is the first' to appear above
ground? What is the second part?

17. When a pea sprouts, what part is first to appear above ground?

18. What are the functions of the. cotyledons? Give illustrations.

19. To what can we attribute the rapid germination of the seed?

20. What are enzymes?

21. Are enzymes found in the animal body?

22. If so, name a few of them and give their functions.

23. What do you mean by " seedling plant " ?

24. What is the function of the micropyle?

2;'). What part of the seedling bean stem is the first to elongate?

26. Compare the cotyledons of the common bean and the castor oil
plant.

27. Describe the opening of the seed coats of the bean, castor oil plant
and other seeds.

CHAPTER II
ROOTS

WE ALL know that plants have roots, but they are usually
buried in the ground and thus hidden from sight and are not
especially attractive. Therefore, most persons prefer to study
the more prominent and pleasing parts of the plant. How-
ever, no part is of greater importance to the plant as a whole
than the root system. When the seed sprouts, the root is the
first organ of the embryo to break through the seed coats. (Figs.
2 d, 4, 6 and 7 a.) It grows downward, away from the light,
but into the soil which contains the food and water. This ten-
dency to go downward is called geotropism.

The soil should contain the necessary supply of food and
moisture, and should be of such character that the roots can
penetrate it readily if the plant is to make its normal growth.
But we shall learn later that all plants do not require the same
amounts of moisture, nor the same amounts and kinds of food.
The farmer cultivates the soil for his crop plants and thus aids
the plants in the work necessary for their growth.

Extent of Roots. — The root usually grows very rapidly, and
when the entire root system is compared with the parts of the
plant above ground, it is found to be much more extensive than
we have ever imagined. When we pull a plant from the soil
a very large number of the roots are broken off and left be-
hind. Therefore, we get a very imperfect idea of the root
system and its ramifications in the soil. But if a plant is grown
in a pot of loose soil, and this soil carefully washed from the
roots we begin to have some slight idea of the very great value
of this part of the growing plant. It has numerous branches,
18

GATHERING FOOD AND MOISTURE 19

many of which have a delicate hair-like growth. The total
length of all the roots of some plants may be many times the
total of the stem and branches. The total length of all the roots
of a mature oat plant are said to aggregate 154 feet, and those
of a mature corn plant 1320 feet. Of course, no one root is
likely to be more than a few feet in length. However, some
plants are known to produce individual roots of considerable
length. The alfalfa is said to produce single roots as much as
31 feet in length and the mesquites of the dry western plains
are said to produce individual roots of as much as 60 feet in
length. The greater the root surface, the greater the amount
of food and water that can be secured by the plant. Of course,
an increase of the root system is usually necessary to an in-
crease of the part above ground.

The roots serve many purposes in the life of the plants, but
these duties are somewhat variable for different plants. The
most important functions are as follows: anchorage, gathering
of water and food, storage of water and food, and in some cases
for climbing. The roots serve as an anchor by which the plant
is held in place. When we try to uproot a plant or think of the
terrific wind storms to which our trees are frequently exposed,
we can appreciate the importance of a secure anchorage. Some
of the large trees of California are said to be thousands of
years old and, after battling with the storms of ages, are still
standing, objects of great admiration.

Gathering Food and Moisture. — We know that the roots
are organs through which water and much of the food materials
enter the plant, but we have very little idea of the amount of
water and food necessary for plant growth. Our land plants
require enormous quantities of water (Page 105), which must
enter through the roots. Therefore, it is necessary for the
roots to spread through the soil in such a manner as to reach

20 ROOTS

both water and food. The soil food is dissolved in the water,
and the two usually enter the plant at the same time.

The thick, fleshy roots which are characteristic of some
plants, such as the turnip, beet and radish, serve for the storage
of food and water. Roots of this kind are used extensively for
food by man and animals. The roots of some plants, such as the
poison ivy, serve for climbing.

Forms and Arrangements of Root Systems.- — The roots of
a plant are not as irregular as many persons suppose; they
assume forms and arrangements which are nearly as definite
as the parts above ground. These forms and arrangements are
just as characteristic of many plants as the stems, leaves, flowers
and fruits. The roots of some kinds of plants go deep into the
soil, while the roots of other kinds spread out, forming a mat
just below the surface.

However, the arrangement of the roots of plants of the same
kinds will vary somewhat with the character of the soil. The
most important soil characters which influence the arrange-
ment of roots are texture, depth, fertility and amount of mois-
ture content. In general, it may be said that in shallow soil
the roots will spread near the surface of the ground, while in
deep soil they will tend to lie deeper; in rich, moist soil they
will be short and branching, while in poor, dry soil they will be
long and with few branches. However, some plants by nature
tend to spread their roots near the surface, while others, like
alfalfa, tend to go deep into the earth and are, therefore, espe-
cially well suited fOr certain soil conditions. Some crops require
much deeper and richer soil and much more thorough cultiva-
tion than others. The potato and other plants with large, fleshy,
underground structures require loose, deep, rich soil to thrive
and give the best results: A knowledge of this relationship
between root systems of plants and soil conditions is of very
great value in selecting crops for different localities.

FORMS AND ARRANGEMENTS OF ROOT SYSTEMS 21

The roots of some plants are fibrous (Figs. 9, 10 and 13),
and in large plants very woody and hard, while the roots of
other plants are thick and fleshy. (Figs. 11 and 12.) The
fibrous roots branch irregularly and serve for anchorage and
also for the entrance of water and dissolved food materials.

FIG. 9. — A grass plant showing the fibrous
root system.

FIG. 10.— A bean seedling showing the bac-
terial nodules on the roots.

The fleshy roots^ in addition to this work, also serve as places
for storage of large quantities of foods. Man and animals take
advantage of these stored products and use the roots of many
plants for food. However, this food is stored in the roots for
the future use of the plants themselves and is usually an import-
ant factor in their production of flowers and seeds. (Page 52.)
Some plants use this stored food the same season that it is
accumulated, while others hold it in reserve for one or more

22

ROOTS

years. The radish is a plant in which the food is used for seed
production the same season that it is stored. The turnip develops
the fleshy root one year and uses it for seed production the
second year.

Food for Man.—The supply of stored food in the roots of
many plants makes them valuable for food of man and other

FIG. 11. — Carrot showing fleshy root.

FIG. 12. — Sweet potato showing cluster of fleshy
roots.

animals if used before they start to form the shoot for flower
and seed production. But if we wait until this shoot is well
advanced, we find the root becoming dry and pithy, owing to
the loss of moisture and food which has been passed on into this
new growth. In some plants, this storage for future use is
performed by the stems or leaves. (Page 51.) The sweet
potato (Fig. 12) is a plant which seldom produces seeds in our
northern latitude, but uses the accumulated food of the large

AERIAL ROOTS 23

fleshy roots for the immediate production of new plants or
slips. Sometimes, new plants are also produced directly from
fibrous roots, as in the case of the poplar, plum, etc., but as
a rule new plants are not produced from the roots.

Length of Life.- Plants which live but one year, as in the
case of the radish are known as annuals; those that live for two

FIG. 13. — Corn plants showing the aerial roots.

years, as in the case of the turnip, are known as biennials; while
those that normally live for several years, as in the case of
trees, are known as perennials.

Aerial Roots. — Roots are frequently borne on parts of the
stem above the ground, and are known as aerial roots. (Fig.
13.) These roots tend to reach the soil and serve as prop roots
and help to support the plant against wind storms. They are
well developed on the lower part of the corn, and are especially
prominent on those plants which have not been tilled properly.

24

ROOTS

The Banyan tree of the tropical East Indies produces roots
from its branches which tend to reach the soil and finally assume
the character of tree trunks. Some plants, known, as epiphytes,
especially abundant in warm, moist climates, often produce
aerial roots which never reach the soil but spread out into
the moist air and serve for the absorption of water. The
orchids of tropical countries, and the so-called Florida moss of
our own Southern States are striking examples of epiphytic

FIG. 14. — Cross-section of stem showing dodder attached by haustoria or parasitic root.

plants. The orchids in the colder climates are rooted in the
soil.

The aerial roots may also serve for climbing on trees, fences
or buildings, stone walls and other firm objects. Climbing
plants are frequently injurious to trees, not only because their
roots penetrate the minute crevices, but also because they retain
the moisture and make favorable conditions for organisms which
cause decay. They are also injurious to wooden structures on
which they are allowed to grow, in that they retain moisture
and cause decay.

Parasitic Roots. — Some plants feed upon other plants by
means of roots which penetrate them. They are called parasites,
and their roots parasitic roots or Jiaustoria. The mistletoe of
the South and the common dodder (Fig. 14) which is much

STRUCTURES

25

more widely distributed throughout the country are good illustra-
tions of this type of roots.

Aquatic Roots. — Some floating plants produce roots which
never penetrate the soil. They are known
as aquatic roots and absorb water and the ^ C I €

various food substances in solution which
are necessary for plant growth. The very
small but widely distributed duck weeds
and the much larger water hyacinth of the
South are excellent examples of floating
plants. However, many aquatic plants,
such as the pond lily, cat-tails, etc., have
roots which penetrate the mud, while the
plant either floats or stands upright.

Structures.— Knots arc made up of
three parts, a central cylinder composed pri-
marily of woody tissue and surrounded by
a sheath or cellular cortex, and covered
with a very thin epidermis or skin-like
coating. (Fig. 15.) They grow in length
much more rapidly than in thickness and
the very delicate tip is protected by a mass
of cells known as the root caj>. All parts
of the root do *iot elongate with equal ra-
pidity. There is a zone just back of the
tip in which the growth is most rapid.

mr .• « f. i i T j FIG. 15. — Diagramm-

Ihe tips 01 roots are soft and delicate and atic longitudinal sec-
tion of a root tip; a,

easily broken, vet they must exert an enor- central cylinder; c,

cortex; e, epidermis;

mous force which we cannot appre- r-c- root Cftp-
ciate. The surface of the young roots, just back of the tip, is
covered with numerous very delicate root-hairs or trichomes.
(Figs. 4, 16 and 19.) These root-hairs are very numerous and
should be studied on very young plants that have been grown in

26 BOOTS

a germinator, and also on plants that have been grown in loose
soils. They grow between the very fine particles of soil. If
the plant is pulled from hard soil they are torn off, but if
pulled from loose, wet soil, they are retained and the soil clings
to them. In order to understand them it will be necessary to
study them with a microscope.

FIG. 16. — Seedling showing FIG. 17. — Cross-section of rootlet showing root-hairs,
soil held by root-hairs.

Work of Root-Hairs. — Each root-hair is a thin-walled cell
containing living protoplasm and cell sap. This living proto-
plasm has the power of absorbing water by osmosis, causing the
cells to become very much expanded or turgid. The excess of
certain substances in the soil may cause an exosmosis or with-
drawal of water from the roots and thus injure or even kill the
plant. This explains one reason why certain soils may be

AIDED BY OTHER ORGANISMS

27

unsuited for certain plants and also how the farmer may injure
his crops by using too much of certain fertilizers or by the im-
proper mixtures of the fertilizers with the soil. The root-hairs
persist for a very short time and then perish, but new ones are
produced near the growing tips. The number of root-hairs
varies with the amount of water in the soil. They are more
numerous in dry than in wet soils. (Figs. 17, 18 and 19.)

FIG. 18. — Showing attachment of root-
hair to epidermis.

FIG. 19. — Showing relation of root-hair to
soil particle.

Aided by Other Organisms. — Plants are frequently facil-
itated in securing their food by other organisms. Dead plants,
dead animals and manures must undergo a decay before they are
sources of available food for most plants. This decay is caused
by bacteria and fungi. (Page 172.) Certain bacteria also aid
the plant by taking the nitrogen from the air and fixing it
in such' a manner as to make it available for plant food.
(Page 117.)

28 ROOTS

Roots of Plants Require More or Less Air. — The securing
of this air is facilitated in many of our cultivated plants by
drainage and by cultivation of the soil, thereby keeping it loose
so that the air penetrates it readily. But plants growing in a
state of nature have various parts and organs through which the
necessary air is secured. Many aquatic plants, such as pond
lilies and cat-tails, have air passages by which the air passes from
the parts exposed to the air to the submerged parts. The swamp
cypress has peculiar upward root growths known as " knees,"
which project above the surface of the water and serve for the
absorption of oxygen. Many forest trees have root growths
extending above the surface of the soil which serve for the
same purpose. The filling in around trees which is frequently
necessary in making grades is injurious because it prevents the
air from reaching the roots.

EXERCISES WITH ROOTS

1. Direction of Growth of Roots. — Sprout a number of seeds and
suspend in a moist chamber on long- pins or by means of threads so that
the root tips will point in different directions. Examine from day to day
and note the direction of growth. Small moist chambers can be made by
putting a small amount of water in a wide bottle or) glass jar ; run a hat
pin through the cork for supporting seeds.

2. Direction of Growth in Soil. — Sprout a number of seeds and plant
in wet sand in such a manner that the root tips point in different direc-
tions. Examine one a few days later and note the direction of growth
of roots and stems.

3. Growth Against Resistance. — Partly till a small cup with mer-
cury. Pour a little water on the surface. Fasten a germinated seed in such
a manner that the root tip rests on the mercury. Inclose in a moist cham-
ber for 24 hours. Has the root tip penetrated the mercury? Does this
require force?

4. Geotropism or Direction of Root Growth. — Sprout a number of.
beans in sphagnum moss or other loose material that will insure the forma-
tion of straight roots. Mark the roots into short, equal sections, using
India ink, pin them to corks and place in large moist chambers * in such

* Moist chambers can be made by lining large battery or other glass
jars with wet filter paper and covering so as to prevent excessive
evaporation.

EXERCISES WITH ROOTS 29

a manner that they will point in various, directions. Examine at the
end of 24 hours and again at the end of 48 hours. Note the direction of
growth, the point at which curving begins and where the curvature is
greatest as indicated by the marks and the point at which the greatest
growth occurs.

i>. Examine the root system of a growing bean, castor bean, or sun-
llower. Note the tap root, the mode of branching, the location of oldest
and youngest branches, size and shape of tap root and branches. Make
drawings or diagrams.

6. Examine the root system of growing corn, wheat or oats. Com-
pare the root system with that in Ex. 5. Make drawings or diagrams.

7. Examine the root system of a growing beet, turnip or radish.
Note the tap root and its branches Compare with that in Ex. 5. Make
drawings or diagrams.

8. Examine the root system of the dahlia or sweet potato. Compare
with that in Ex. 7. Make drawings or diagrams.

!l. Examine the root system of English ivy or some other plant or
plants in which the roots serve for climbing. Note their location, branch-
ings and general character. Make drawings or diagrams.

10. Region for Root-hairs. — Sprout a number of grains of corn,
okra. radish seed, clover seed, or white mustard, between wet blotting
paper until the roots tire about one and one-half inches in length. Note
the region on which the root-hairs occur. Examine the root-hairs undier
a compound microscope, or strong hand lens.

11. Soil Held by Root-hairs. — Plant seeds in fine, sandy soil. After
two weeks wet the soil thoroughly and very gently remove the plants.
Note the manner in which the soil is held by the root hairs.

12. Roots from Willow Twigs. — Cut a number of willow twigs about
twelve inches in length and put in a jar of water so that about half the
length will be covered. Put part of them upside-down. Use an earthen
jar or a glass jar covered with black paper so as to exclude the light.
Examine from time to time and note the formation of roots. Where arc
they located and what is the direction of growth?

13. Osmosis with a Thistle Tube. — Make an artificial root-hair
by covering the large end of a thistle tube with an animal or plant mem-
brane, piece of intestine (sausage covering) or bladder, fill the bulb with
a thick syrup (molasses) and invert in a jar of water so that the two
fluids stand at the same level. Examine after a few hours and note the
rise of the fluid in the tube. This passing of a fluid of less density through
an animal membrane into a fluid of greater density is called osmosis.
(Pages 112 and 113.)

14. Osmosis with an Egg. — Remove the shell without breaking the
skin from the large end of an egg over an area about the size of a dime.
In the same manner remove a small bit of shell from the small end over

30 ROOTS

an area about one-eighth of an inch in diameter. Run a glass tube through
a small section of a wax candle and directly over the small opening. Now
push the wire down the tube and puncture the membrane at the small end
of the egg. Fill a wide-mouthed bottle level full of water and set the egg
in the top. ( Fig. 80. ) Note and explain the rise of water in the tube.

15. Osmosis with a Fleshy Root- — Cut a slice from the upper part
of a carrot or other fleshy root; hollow out the centre of the root and
fill with sugar. Let stand for twenty-four hours. What has occurred?
Explain.

16. Cut thin strips, about one-eighth inch thick, of a fleshy root and
place in salt water for a few hours. Examine and then place in distilled
water for a few hours. Examine and explain.

QUESTIONS

1. Where do we find the root system of the plant?

2. What do you understand by geotropism ?

3. What are the characters of the soil that make it suitable for plant
growth .?

4. What can you say about the different types of root systems of
plants ?

5. What are the functions of the roots ?

6. Is there any difference in the arrangement of the root systems of
plants? Explain.

7. Upon what is the variation of the root system dependent?

8. What is the difference between the root system of the radish and
that of the turnip? What functions do they serve?

9. Give a list of plants whose roots are used for food by man and
livestock.

10. Define and give examples of annuals, biennials, and perennials.

11. What is the difference between aerial and epiphytic roots.

12. Name some plants with parasitic roots. •

13. Name some plants with aquatic roots.

14. Name and locate the three parts of a root.

15. Explain osmosis.

16. Why are some fertilizers injurious to plants?

17. How does air reach the roots of plants? How can the farmer
aid plants to secure air?

18. What is the general direction of root growth? Of stem growth?

CHAPTER III

STEMS AND BUDS

THE stem is that part of the plant which connects the root
with the leaves. The most common types of stems of seed-
bearing plants are above ground and serve to support the foliage
and flowers. They usually show more or less well-defined divi-
sions into nodes (joints), and internodes as indicated by
branches, leaves and leaf scars, buds and bud scars. (Figs. 20
and 21.) They produce branches at the nodes more or less
regularly. At the points where the new season's growth begins
we find a number of scars very close together. (Fig. 20.) By
examining the scars we can usually determine the amount of
growth of the twigs for several years past.

There are two well-defined types of stems, the exogenous
(Fig. 22 a), or the outside growing, and the endogenous (Fig.
23 a) or inside growing. The former is much more abundant
than the latter, and the two can be readily distinguished by cut-
ting them in cross sections. In both cases the stems are com-
posed of hard, woody bundles surrounded by a softer substance
which is covered by the bark or protective covering. The ar-
rangement of these bundles is quite different in -the two classes.
In the exogenous stems (Fig. 22) the bundles are almost always
arranged in a circle and the strength of the stem depends, in
a large measure, on their compactness. Such stems will in-
crease in diameter as long as the plant is alive and growing.
This increase in diameter is due to the formation of a layer
of wood just outside the last year's growth of wood. This very
thin layer of cells in which the new growth is occurring is
known as the cambium. These annual layers are so distinct that

31

32

STEMS AND BUDS

they can be readily seen on the cut ends of tree trunks, with the
naked eye, and are known as annual rings. (Fig. 24.) All the
dicotyledonous and coniferous plants have stems of this type.
If you cut a cross-section of a soft, rapidly growing stem (be-
gonia or geranium), you can see these bun-
dles more or less well defined. If you cut
a cross-section of a woody stem, you will
readily recognize these bundles which are sep-
arated by radiating lines.

We find two types of endogenous stems.
One which consists of a mass of soft," pithy
tissue surrounded by a hard rind and con-
taining scattered, woody strings kiiown as
fibro-vascular bundles (Fig. 23), and an-
other which is of the same general character,
but is hollow, and therefore the fibro-vascular
bundles are forced into the form of a cyl-
inder. All of the grass stems are endogen-
ous; the corn which is a coarse grass, is a
good example of the first type and the various
grains and most common grasses are exam-
ples of the second type. These fibro-vascu-
lar bundles or woody strings can be readily
recognized in the corn stalk.

Sterns in which the fibrous bundles are
small as compared with the surrounding ma-
terials are soft and juicy, and are called
licrlmceous, while those in which the bundles
bThOT^ch^tnuTTwig1 constitute the greater part of the substance

showing same. n i ^ -nr f ±1 i • j/l

are called woody. Most 01 the strictly woody

plants have exogenous stems and show rings. (Chapter VIII.)

Stems Above Ground. — The aerial, or above-ground, stems

may be very short as in the case of the turnip or radish, in which

b

FIG. 20. — a, maple
twig showing buds, leaf
scar and annual growth ;

STEMS ABOVE GROUND

33

ic supports a mass of leaves very close to the root and is known
as a crown or acquiescent stem, or it may be more or less elong-
ated, as in the case of many herbaceous plants and trees. The
elongated stems may be erect, as in the case of trees, but
extremely variable in size and form. Two well-defined types of

FIG. 21. — Twig showing alternate buds.

the stems are the excurrent (Fig. 25), in which we find a tree
with a central axis or trunk giving off numerous small branches,
like the pine, and the deliquescent (Fig. 26), in which the main
trunk sub-divides by branching and loses its identity as in the
oak and elm. Stems belonging to either of these types vary

FIG. 22. — a, cross-section of dicotyledonous FIG. 23. — a, cross-section of monocoty-
Btent; b, fibrovascular bundle from same. ledonous stem; b, cross-section of fibro-

vascular bundle ef same.

greatly in the method of arrangement of the branches. Persons
who have given some attention to this subject can recognize
many trees by their style of branching.

However, many elongated aerial stems cannot stand erect,
but are decumbent, or leaning, as in the case of many berry
plants ; or prostrate, as in the case of those plants which trail
3

34

STEMS AND BUDS

Fia. 24. — Diagrammatic cross-section of a tree stem showing the medullary rays and

annual rings.

FIG. 25. —Trees showing the excurrent type of stems.

along the ground (ground ivy) ; or climbers, as in the case of
many vines which cling to other plants, walls or buildings for
support. Climbing may be accomplished by twining or by
means of specially modified branches or stems (tendrils of

UNDERGROUND STEMS

35

FIG. 26. — Tree showing the deliquescent type of stem.

grape), or by rootlets (poison ivy), or by modified leaves
(clematis).

Underground Sterns. — The stems of many plants are under-
ground and are frequently mistaken for roots. However, they

36

STEMS AND BUDS

can be readily recognized by the fact that, like all stems, they are
divided into more or less regular nodes and internodes, and the
branching is alwaysi from these nodes and is, therefore, regular,
while the roots are without nodes and branch irregularly.

Fia. 27. — Underground stem of the Solomon's seal.

FIG. 28. — a, tulip bulb; b, same cut longitudinally to show short basal stem and fleshy
leaf overlapping the single terminal bud.

Numerous roots are frequently formed at the nodes of these
underground stems.

Underground stems may be divided into two general types,
the elongated and the short. The elongated stems, which are so
well illustrated by the Solomon's seal and May-apple (Fig. 27),

UNDERGROUND STEMS

37

bear roots at regular intervals and show well-defined leaf scars
at the nodes. Some grasses, such as the witch grass, have
similar underground stems bearing buds at the nodes. When
such grass stems are torn to pieces by the farm implements each

FIG. 29. — Potato showing the tuber type of stem. Fia. 30. — Stem or trunk of the

birch showing the peculiar markings
of the bark.

bud is capable of growing into a new plant. Such stems are
called root stocks or rhizomes. Shortened stems have very short
internodes and are generally designated as bulbs (Fig. 28) and
tubers (Fig. 29). The bulbs are very short stems covered with
scales which are really modified leaves. These scales may be

38 STEMS AND BUDS

very prominent, as in the case of the hyacinth or onion, or they
may be small and on a very short, thick, fleshy stem, as in the
case of the Indian turnip. This last type is known as a corm.

Bulbs or bulblets are sometimes borne on the stem above
ground; they are nothing more nor less than modified buds.

Sometimes the underground stems become very thick and
fleshy and are known as tubers. The common white or Irish
potato is an excellent example of the tuber. The so-called
" eyes " are buds and indicate the nodes of the stem. True
tubers, such as the Irish potato, are fleshy stems and are entirely
different from the fleshy roots of such plants as the sweet potato
and the dahlia.

Two Chief Uses of Stems. — As previously stated, stems con-
nect the roots with the leaves and support the latter in the air
and light, but some plants, such as the cactus, have leaves that
are poorly developed and of little importance. The stems of
these so-called " leafless " plants are green and serve the same
function as leaves. (Page 47.) The stems of many other plants
are also green and perform the duties of leaves for a part or for
the entire life of the plants. The young twigs are usually green
and have stomata (Chapter IV), the same as leaves. How-
ever, these stomata soon lose their ^original character, and de-
velop into leiiticles. (Chapter VIII.) The lenticles are the
little specks which are so readily recognized on the smaller twigs.
(Figs. 20, 21 and 30.) They will be referred to again.

Stems also serve for the passage of the water and food sub-
stances from one part of the plant to another. (Chapter VIII.)
These are the primary functions of stems, but they also serve
many other purposes. In the cacti and other plants living in
very dry regions they serve for the accumulation of considerable
quantities of water. Floating plants frequently have large
chambers filled with air which increases their buoyancy. Many
stems, such as tubers, serve for the accumulation of food sub-

THE ART OF BUDDING AND GRAFTING 39

stances for future use. Man has taken advantage of this fact
and uses potatoes, onions and many other fleshy stems for food.

But one of the most important of the secondary functions
of the stem is reproduction This is accomplished by under-
ground stems, by the branching and the breaking-up of the
root stocks, and by the budding or formation of bulblets in the
bulb types. Many plants, lilies and hyacinths, have practically
lost their power to produce seeds and depend entirely upon this
method of reproduction. Irish potatoes are very generally
grown from tubers, but they will occasionally produce seeds, and
the wild potatoes of South America produce seeds very freely.
The growing of bulbs of ornamental plants is a leading industry
in many parts of the world. Holland is one of the greatest of
the bulb-producing countries of the world.

Many aerial stems reproduce by runners and offsets and we
depend largely upon this method of reproduction to secure
plants for agricultural purposes. This is the regular method
of propagating strawberry plants. Branches of many plants
when set in the soil will produce roots and grow rapidly, and in
nature broken branches of willows and many other plants catch
in the soil or become partially covered and grow. We have
taken advantage of this tendency and propagate many useful
plants from cuttings.

The art of budding and grafting is based on this tendency of
cuttings to grow under favorable conditions. Budding consists
in setting the buds of one plant within the bark of another plant,
and is generally used in propagating peaches, cherries and sim-
ilar fruits. Grafting consists in setting a part of a living twig
with its buds from one tree into the branch of another and is
very generally used in propagating apples and similar fruits.

The structure of stems, their methods of growth and the
movements of the plant juices through them will be taken up
in a later chapter.

In the first chapter we learned that plants are made up of

40

STEMS AND BUDS

but three primary organs, roots, steins and leaves, and that the
other so-called organs with which we are so familiar are modifi-
cations of these three. We have already studied the roots and the
stems, but before taking up the study of the leaves let us con-
sider the buds which are undeveloped shoots or stems. ,

Fio. 31. — A newly opened leaf bud of the maple and the same bud dissected to show
graduation from scale to leaf.

A leaf bud consists of a very short, undeveloped stem bearing
a compact mass of minute leaves. (Figs. 20, 21 and 31.) This
stem will elongate and the leaves grow to full size. It is then
known as a stem or shoot with its leaves.

Flower buds are those which develop into flowers, but we
will learn later that flowers are made up of modified leaves on
short stems and therefore, it is not necessary to change our
definition of a bud. (Chapter V.)

Location and Structure of Buds. — Buds are borne in the
axils, that is just above the point of union of the leaf to the
stem. In our northern climates they are produced a year in
advance of their development into shoots or flowers and remain
over winter in a dormant or resting condition. In temperate
climates the buds are frequently spoken of as scaly buds because
the lower or outside leaves are modified as scales and serve to

LOCATION AND STRUCTURE OF BUDS 41

protect the true leaves and flowers within. These scales never
develop into true leaves. The examination of the buds of many
of our plants in the spring will show a gradual graduation from
scales on the outside to well-formed leaves on the inside. (Fig.
13.) These outside scales are frequently covered with masses
of plant hairs (trichomes) or with wax or have the appearance of
being varnished. These structures serve as a protection against
the entrance of water which would cause great damage, espe-
cially during the winter season. Many of the plants of warm
climates and some of the plants of temperate climates have
naked or nearly naked buds ; that is, buds that have very little
or no protection from the climatic conditions.

Buds are also classified with reference to their location on
the stem. Those at the tip are apical or terminal, while those
on the sides are lateral. Lateral buds may be opposite or alter-
nate. When lateral buds are directly in the angle formed by
the stem and leaf they are axillary, but when to one side or above
they are called accessory. Buds borne on other parts of the
stem, on the roots and on the leaves are known as adventitious;
they are of the greatest importance in the propagation of plants
by cuttings.

A plant cannot produce food for the growth of all of its leaf
buds into shoots and, therefore, many buds perish, but some
of them remain dormant and many later develop into the well-
known sucker or water shoots. Such growths are very common
on trees that have been over-pruned, or broken by storms. If it
were possible for all the buds to grow, all our trees would as-
sume the characters of very dense hedge plants. The tendency
of some plants, such as the privet and osage-orange, to produce
a very large number of shoots increases their value as hedge
plants and ornamentals.

The growth of shoots from the buds may be definite or in-
definite. The definite annual growths are those in which the

42 STEMS AND BUDS

shoots increase in length for a few weeks only and the remainder
of the season is used for maturing the wood and buds. Such
growths are not likely to winter-kill, and the growths of succes-
sive years can be readily traced by the bud scars on the stem.
The shoots of other plants grow throughout the entire season and
until checked by the cold weather ; they are known as indefinite
growths, and are likely to suffer from winter injury. The roses,
lilacs, sumac and ailanthus or tree-of-heaven are excellent ex-
amples of this type of growth.

Underground stems produce buds at the nodes in the same
manner as the stems above ground. The so-called " eyes " of
the potatoes are buds which give rise to shoots. The bulbs of
many plants, although usually described as stems, are, in
reality, buds.

EXERCISES WITH STEMS AND BUDS

1. Study of Woody Twigs. — Cut a branch from a maple, linden, horse
chestnut or other dicotyledonous tree and note the nodes and internodes
of the newest growth as marked by buds and scales; trace as many seasons
of growth as possible, beginning with the tip of the twig. Examine the
bark with a hand lens and note leaf scars, lenticles and other peculiarities.

2. Monocptyledonous Stems. — Examine a corn stalk, grass stem,
grain straw and other monocotyledonous stems and compare with a woody
stem studied in previous exercise.

3. Cross-section of Herbaceous Stem. — Cut through a Begonia stem
(dicotyledonous), examine with a hand lens and.note (a.) the central mass
or pith surrounded by (6) a circle of wedge-shaped areas which are fibro-
vascular bundles of wood, and which are separated from each other by
material like the pith and known as medullary rays. Outside the fibro-
vascular bundles is another zone which is in turn surrounded by the
epidermis or bark covering.

4. Layers of Bark. — Take the last season's growth of a lilac, horse-
chestnut or maple. Gently scrape off the outer brown bark, the inner
green bark and the fibrous bark and examine with a hand lens and note,
(a) the outer brown bark layer, (&) the second or dark green layer of
new bark and (c) the third layer of tough fibrous bark or bast.

5. Cross-section of Woody Twigs. — Cut through a woody twig of
oak or basswood and note (a) the central pith surrounded by (&) the

EXERCISES WITH STEMS AND BUDS 43

wedge-shaped fibro- vascular bundles separated by (c) the radiating
medullary rays and (d) the concentric circles or annual rings.

0. The Parts in Large Timber. — Examine the cut end of a large
stem or tree trunk and note the same points as in the preceding exercise.
Examine the enda of sawed timber and determine the above parts. Trace
them in the long section of the timber.

7. Rise of Sap in Stems. — Stand the freshly cut stems of Begonia,
horse-chestnut and other plants in water colored with eosin or red ink
for 30 minutes, one hour, and for 24 hours. Cut off small pieces, beginning
at the base and examine with a hand lens. Note the part through which
the colored fluid rises and the height to which it has risen.

8. Persistent Upward Tendency of Stems. — Take an upright, pot-
ted plant and place in a horizontal position (pot and all). Make a dia-
gram to denote the relative position of the parts and examine again at the
end of 24 and 48 hours.

9. Dandelion Stem and Buds. — Examine the short stem of the dan-
delion or similar plant. Count the number of buds you can find near the
surface of the soil. Does the number vary with the size and age of the
plant? Split the entire plant lengthwise and try to determine point of
union between stem and root.

10. Examine the under-ground stem of Solomon's seal, May-apple,
Johnson grass or similar plants and compare with an aerial stem.

11. Examine the bulbs of crocus, tulip, gladiolus, Indian turnip,
onion, etc., and note their general character. Cut them open lengthwise
and note the short stems and scale-like leaves.

12. Examine a potato tuber and note its general character. Note the
arrangement of the eyes or buds. Compare with the fleshy root of a sweet
potato. Cut through it and note the fibro- vascular bundles just beneath
the epidermis or peeling.

13. Buds of Twigs. — Examine the stems of lilac, horse-chestnut,
hickory and maple. Note number, arrangement and relative sizes of the
buds on the different stems and on the same stem.

14. Structure of Buds. — Take the large buds of the lilac, horse-
chestnut, hickory, etc., and carefully dissect by successively removing the
scales and inner parts. Note the gradual transition from scales' to leaves.
Note the short, conical, undeveloped stem to which they are attached.
Compare the bud to a scaly bulb. (This study is most satisfactory if
conducted in the early spring when the buds are swollen. In winter the
stems should stand in water a few days before the study.)

15. Opening of Buds. — Cut a few of the newest and most vigorous
shoote from a lilac in winter or early in the spring before the buds open and
place in water in a warm room. Examine from day to day and note the
opening of the buds and growth of new shoots.

44 STEMS AND BUDS

QUESTIONS

1. What is the stem?

2. What are nodes? Internodes?

3. Name and explain the types of stems.

4. Describe a cross-section of each.

5. Describe the outside coverings of a stem.

6. What are the annual rings?

7. What are the differences between herbaceous and woody stems?

8. What do you understand by acaulescent? Excurrent? Decumbent?
Prostrate ?

9. Explain the methods by which plants climb.

10. How can you distinguish underground stems from roots?

11. Describe a rhizome. A bulb. A tuber. Give examples of each.
12 What are lenticles ?

13. What are the various functions ofi stems?

14. Read and give a report of the flower industry of Holland.

15. Read and give a report of the history of the potato.

16. Explain the natural methods of plant propagation by means of
stems.

17. What are the artificial methods of plant reproduction by stems?

18. Compare a corn stalk with the stem of a woody plant.

19. What are medullary rays?

20. Through what part of the stem does water rise? How demonstrated?

21. When you examine the cut end of a large woody stem what
do you see?

22. What occurs when plants are exposed so as to receive the sun on
one side only?

23. What is the general direction of stem growth as compared with
root growth ?

24. Where do you find the fibro-vascular bundles in the tuber of the
Irish potato?

25. Compare the tuber of the Irish potato with the root of the
sweet potato.

26. What is a bud?

27. What is a flower bud?

28. Where are buds borne?

29. When are buds produced?

30. What do you understand by apical, lateral, opposite, alternate,
axillary, accessory and adventitious buds?

31. Do all the leaf buds grow into shoots? WTiy?

32. What do you mean by definite and indefinite growths?

33. What are the eyes of the potato tuber?

CHAPTER IV
LEAVES

THE leaves of a plant are always borne on the stem and have
the same relative position as the buds. (Figs. 20 and 21.) They
are the expanded parts of the plant and have a definite rela^
tionship to the air and sunlight.

Green plants must have an expanded surface (usually the
foliage) into which the gaseous elements (Chapter X) of the
air may pass. These gaseous elements are as necessary for the
growth of the plant as are the raw food materials of the soil.
These expanded parts contain chlorophyll or the green coloring
material which is necessary for the formation of true food sub-
stances from the elements and compounds obtained from the
water, soil and air.

Relation to Light. — If you stand under a tree and look
upwards, you will note that the leaves are on or near the tips of
the twigs and thus form a canopy or tent with the trunk and
branches as the supporting framework. If you place yourself
in such a position as to look down upon a small tree or other
plant or at a vine (Fig. 32), climbing over a wall you will be
surprised to note how very little the leaves shade one another,
and that all have very nearly the same light and air exposure.
The leaves of many plants, especially the legumes, are also
raised and lowered to some extent throughout the day in such
a manner as to receive the sunlight to the best advantage.

The leaves are the factories in which the raw food sub-
stances are transformed into true food substances for the growth
of the plant. The water and these various raw or crude food
substances which may be dissolved in it are taken from the soil

45

46

LEAVES

and carried to the leaves where the most of the water is trans-
pired into the air. (Page 114.) The leaves take carbon dioxide
gas (CO2) from the air and as a result of the action of the sun-
light on the green coloring matter (chlorophyll) these sub-
stances are transformed into starch. This process is known as

FIG. 32. — Ivy leaves on a wall showing the arrangement with very little overlapping.

photosynthesis (Page 115), which is the most remarkable
process in all nature. It is the most important process in plant
growth, and without plant life there could be no animal life.
. Sunlight and Chlorophyll. — The formation of the complex
food substances or compounds from the crude materials of the
soil and air is accomplished in green plants only and, there-

SUNLIGHT AND CHLOROPHYLL

47

fore, all animals and all plants that do not contain chlorophyll
are dependent either directly or indirectly upon these green
plants for their food supply. Different kinds of plants require
varying amounts of light and, therefore, we find some plants
growing in the direct sunlight, while others are usually found in
the shade and will not thrive in the intense sunlight. We also
notice that the arrangement of the foliage on the plant, and its

FIG. 33. — Self-pruned twigs of the poplar showing the cleavage planes.

position during different hours of the day and on cloudy and
clear days, are such as to relieve the sunlight in proportions more
or less suitable for its own work. Plants growing in the desert,
or other dry places, may be " leafless " or have the leaves greatly
reduced, but the stems of such plants contain the chlorophyll
and serve as foliage. Plants may produce more foliage than is
necessary for their normal growth. Such plants may drop in-
dividual leaves or even large shoots during the growing season
by a process of self -pruning. These leaves and shoots are not

48

LEAVES

broken off but " grow off " by the formation of definite cleav-
age planes as in the shedding of leaves for winter. This self-
pruning process is very comrnoii among willows, poplars, cotton-
woods and many other trees. (Fig. 33.)

Parts of Leaves. — A simple, typical leaf (Fig. 34) has a
blade or lamella supported by a framework composed of ribs

FIG. 34. — Simple net-veined leaf.

FIG. 35. — Simple parallel-veined leaf.

and veins. The principal rib is known as the midrib and is a
continuation of the leaf stem or petiole. Leaves which do not
have petioles are sessile. These ribs and veins are continuations
of the woody bundles found in the stems and serve not only to
support the leaf but as channels through which the water and raw
food materials pass to the leaf, and through which more com-
plex food substances pass to other parts of the plant. Minute
structures, known as stipules, frequently are found at the bases
of the petioles. They are extremely variable in form and
character. Sometimes they are leaf-like and may fall soon after
the unfolding of the leaves as in the willows ; sometimes they are

TYPES OF LEAVES

49

attached along the margin of the petioles as in the clovers;
sometimes they are developed as sheaths enclosing the stem as
in the grasses and grains ; and sometimes' they enclose the young
leaves as in the tulip tree.

Types of Leaves. — Leaves which have one prominent mid-

Fio. 36. — Palmately veined leaf.

Fia. 37. — Palmately veined leaf.

rib running from base to apex, and giving rise to numerous side
branches with smaller veinations between them are said to be
net-veined (Fig. 34), while leaves which have a number of
equally prominent veins running from base to tip are said to
be parallel-veined. (Fig. 35.) Most dicotyledonous plants
have net-veined leaves, while most monocotyledonous plants
have parallel-veined leaves. Leaves which have three, five or
more prominent ribs or veins arising from a common point are
said to be palmate-net-veined or radiate-net-veined (Figs. 36
and 37), while those that have numerous veins arising from a
main mid-rib are said to be pinnate-net-veined or feather-net-
veined. (Fig. 34.)

60

LEAVES

Compound Leaves. — Leaves which are composed of two or
more leaflets arisiug from a single petiole are said to be com-
pound and are described as palmate- or radiate-compound (Fig.
38), or as pinnate- or feather-compound. (Fig. 39.) The size,
form, arrangement and various other modifications of the leaves
of plants are largely dependent upon the environmental factors,

Fia. 38. — Palmately compound leaf.

FIG. 39. — Pinnately compound leaf.

especially light and moisture. Land plants, growing in very
wet surroundings tend to have larger leaves than those growing
in dry or arid surroundings. Aquatic plants in running water
tend to have long, narrow leaves as compared with plants living
in still water.

The Leaf Blade. — The veination of the leaves supports a
delicate structure (Page 102), within which are numerous air

USES OF LEAVES 51

passages with openings (stomata) to the outside, usually on the
lower surface. These passages and openings facilitate the trans-
piration of water (Page 114), and the absorption of gases.
(Page 115.) The texture of leaves varies largely with the en-
vironment in which they live. The surfaces of leaves are also
frequently covered with spines, hairs (trichomes), gland hairs,
wax, etc., which serve to protect the plant, prevent excessive
transpiration and otherwise facilitate its work.

Uses of Leaves. — Leaves are so abundant, and come with
such great regularity that we are likely to fail to appreciate their
importance in the life of the plant. But these very common-
place facts should convince us that they are invaluable to the
plant, that they are something more than elements of beauty
in the individual plant or in the landscape. We have already
learned that the primary function of leaves is to serve as
foliage through which the living, growing plant receives gases
from the air and energy from the sun and in which the raw
food substances are transformed into true foods (photosyn-
thesis, Page 115). But the leaves serve many other useful pur-
poses which are important in the life history of the plant : (a)
they are the organs of transpiration (Page 114), by which are
given off quantities of water previously absorbed through the
roots; (6) they are organs of respiration, although this func-
tion is not confined to the leaves; (c) they may serve as bud
scales for the protection of the more typical foliage leaves and
flowers (Page 40) ; (d) they may develop a bitter gum and
thus serve as a protection against birds and other small animals
which feed on the new growths in the early spring; (e) or they
may develop as briars or thorns which, no doubt, serve to some
extent as a protection against larger animals. Thistles and other
plants which are armed with these protective structures will
stand unmolested in the stock pasture, even though the food

52 LEAVES

supply for the cattle may be very limited. Every good farmer
knows the advantage of using sheep or goats for the cleaning
of neglected lands of these armed weed pests which most live-
stock will not touch.

Leaves also serve for the storage of food and water as in
the case of the so-called " century plant," which grows for a
number of years and then develops its flowers and seeds at the
expense of the food stored in the large fleshy leaves. This is
no more wonderful than the common cabbage in which exactly
the same thing occurs in a cycle of two years ; the accumula-
tion of the food is during the first, and producing the flower
and seed during the second year. Man has taken advantage of
this tendency of the plant to store its food in the leaves and
makes use of many such plants as food for himself. Leaves may
also serve for the storage of air as in the case of the floating-
plants which contain large air-chambers.

In some few plants the leaves have undergone modifications,
enabling them to serve as imect traps for the capture of insects
which die, decay, and furnish a supply of nitrogenous food for
the growing plant. The most interesting insect catchers are the
sun-dew, Venus fly-trap, and the pitcher plants, which you
will find described in an encyclopedia, and in many works on
botany.

Probably the most important function of leaves after photo-
synthesis is the formation of flowers and fruits, for as we shall
learn later, the flowers are modified leaves. (Page 54.)

EXERCISES

1. Collect the following forms of leaves: simple net-veined, simple par-
allel-veined, simple palmate-veined, compound palmate-veined and com-
pound pinnate-veined. Make drawings and label the parts.

2. Collect and make drawings of leave* witli and without petioles.

3. Collect leaves showing different types of stipules.

QUESTIONS 53

QUESTIONS

1. On what part of the plant are the leaves borne?

2. Why is it necessary that the leaves should be exposed to the air?

3. What are the sources of plant food?

4. Why is it necessary that the plant receive sunlight?

5. Why are animals dependent on plants for food?

6. Are there any other sources from which animals can secure food?

7. What parts of the plant other than the leaves may possess chlor-
ophyll? Give examples.

8. Name the parts of a simple leaf.

9. What are the differences between net- and parallel-veined leaves?

10. What are the differences between simple and compound leaves?
Give examples of each.

11. What are the functions of the leaves?

CHAPTER V
THE FLOWER

HAVING studied the three primary parts of the plant, the
root, stem and leaves, we now turn our attention to the most
important secondary organ, the flower. The llowers of many
plants are objects of beauty, but the great majority of plants
bear flowers which are very small and inconspicuous, or which
are of such character that they do not attract the attention of
the casual observer. Many people are so accustomed to think-
ing of flowers as mere objects of beauty that they fail to realize
the very great importance of these organs in the life history of
the plant. The flowers contain the sexual organs of the plant
and are necessary for the production of seeds and fruits.

Parts of the Flower. — The flower does not present any new
structures, but is a shortened stem bearing circles of leaves,
which have been greatly modified in shape and color into
parts constituting the flower, Instead of being borne on a
long stem, they are now brought together in circles and the
shortened stem is known as the receptacle, or torus; the first or
outer circle, composed of parts which are usually green and
resembling ordinary leaves, is known as the calyx, and each
leaf -like part is called a sepal; the second circle or series of
circles composed of parts which also have some resemblance
to leaves but which are usually colored is known as the corolla,
and each part is called a petal; the third set of organs consisting
of one or more circles is composed of stamens which bear very
little resemblance to leaves ; the last or central group consist-
ing of one or more organs which may be distinct or united is the
pistil which also bears very little resemblance to leaves. (Figs.
54

PARTS OF THE FLOWER

55

40 to 44.) The calyx and corolla constitute the floral envelope
or perianth while the stamens and pistils are the sexual or essen-
tial organs of the plant. The arrangement of the organs in
circles permits the making of diagrams which represent the
general plan of a flower as clearly as a map shows the physical

b

Fio. 40. — a, cherry blossom; b and c, diagrams showing the arrangement of the parts.

Fia. 41. — a, diagrammatic longitudinal section of apple blossom; b and c, peach blossom.

and political divisions of the earth. If this diagram is accom-
panied by a second diagram made at right angles to the first,
the general architecture of the flower is well shown.

The sepals and petals being leaf-like in character sometimes
grade imperceptibly the one into the other. In some flowers, of
which many lilies are examples, the parts of these outer circles

56

THE FLOWER

are practically alike in both shape and color; while in other
flowers there is no corolla. When the corolla is missing, the
calyx may be green, but it is usually of some other color which
deceives many observers into believing it to be the corolla. The
common hepatica and the wind flower are good examples of
flowers with colored calyx and no corolla.

When the corolla alone is absent, the flower is described
as apetalous {i.e., without petals). Some plants have flowers

FIG. 42

FIG. 43

FIG. 42. — Diagrammatic drawing and cross-section of a lily.
Fia. 43. — Diagrammatic longitudinal and cross-sections of a pea blossom.

with neither calyx nor corolla, but these, incomplete flowers are
just as important in the life history of the plant as the very
complicated and highly colored flowers of other species.

The stamens in most flowers are distinct and have no external
resemblance to leaves, but in some flowers the gradual transi-
tion from petals to stamens is so apparent as to leave no doubt
whatever as to origin, even in the mind of the most casual
observer. This is especially well illustrated in the white water
lilies. In a state of nature, we sometimes find flowers in which
the petals assume stamen character or the stamens tend to

FLOWER TYPES

57

become petal-like in character. This tendency in plants makes
it possible for the florist to develop double flowers from the
natural single ones; the wild rose has but five petals, and
numerous stamens, but the double rose has many petals and few
or no stamens, they having bean transformed into petals, more
or less like the other petals.

The pistils are more distinct than the stamens but will
sometimes assume petal-like characters. The organs of some

—a

— $

FIG. 44. — a, twig and two clusters of elm blossoms; b and c, diagrammatic longitudinal and
cross- sections of a single blossom.

flowers are imperfect and of no use to the plant. If all of the
stamens or all of the pistils are imperfect the plant cannot
produce seeds and, therefore, must be propagated by some
method other than by seeds. This will be explained later.
(Chapter VI.)

Flower Types. — A flower which is composed of the four sets
of organs is said to be complete (Fig. 40), and a flower pos-
sessing both stamens and pistils, regardless of the presence or
absence of calyx and corolla, is said to be perfect. (Fig. 40.)
A flower in which the number of organs in each set is the same
or a multiple of the same is symmetrical. (Figs. 42 and 43.)

58

THE FLOWER

If all of the organs of each set are the same size! and shape it
is regular. (Fig. 40.) The opposites of the above are : incom-
plete, imperfect, unsymmetrical and irregular. The, apple,
peach and cherry (Figs. 40 and 41) are complete and perfect;

the lily (Figs. 42 and 51) is
symmetrical and regular ;
the corn (Figs. 46 and 48)
and castor oil plant are both
incomplete and imperfect ;
the apple and peach unsym-
metrical ; the violet and bean
(Fig. 47) irregular.

Imperfect Flowers.—
Some plants bear two kinds
of imperfect flowers, those
with stamens which are
known as staminate flowers,
and those with pistils which
are known as pistillate flow-
ers. In some cases the two
sets of flowers are so different
in general appearance as to
be readily distinguished while
in other cases they are very
much alike and cannot be distinguished except by a more care-
ful examination. Plants which bear these two kinds of imperfect
flowers are said to be monoecious (Figs. 46 and 48), i.e., of one
household. The common corn is a good example of a mon-
oscious plant, the tassel being composed of staminate flowers
while each grain with a single thread of silk is a pistil. Each
mature grain of corn is a fruit produced from a single pistil-
late flower.

Other plants bear the staminate and pistillate flowers on
different individuals and are known as dioecious (i.e., of separate

FIG. 45. — Single blossom of rye; a, stamen; o,
pistil.

IMPERFECT FLOWERS

59

FIG. 46. — Two ears of Indian corn; i.e. the pistillate flower.

households). The mulberry, willow and poplar are excellent
examples of dioecious plants. The fruits of these plants are
always borne on the pistillate plants.

GO

THE FLOWER

In the examination of a large number of plants we will find
many interesting modifications of strictly monoecious and di-
OGcious types. The Indian turnip or J ack-in-the-pulpit (Fig.
49) is usually dioecious, but many plants will be found which
are monoecious. Some species of plants, of which the maples
are good examples, both bear perfect and imperfect flowers, while
individuals are frequently found which do not bear flowers
of anv kind.

FIG. 47. — Legume blossom; a and b, the blossom; c, the blossom dissected showing the
petals; d, the sepal, stamen and pistil; e, the mature seed pod.

Modified Calyx and Corolla — Both the calyx and the cor-
olla are frequently modified. The simplest modification is
the union or partial union of the sepals or petals or both to
form tubes. Flowers in which these unions occur are described
as gamo-sepalous and gamo-petalous (Fig. 50), while those in
which there is no union are described as poly-petalous and poly-
sepalous. (Figs. 40, 42, 43 and 51.) The petals and sepals may
also be modified to form spurs, as in the violet, or in many other
ways. The calyx and corolla are borne on the receptacle, but
in some cases the corolla appears to be attached to the calyx.
We will find these numerous modifications of very great inter-
est, and they are of very great importance in the life history of

PARTS OF THE STAMENS

61

FIG. 48. — The tassel or staniinate flowers of the Indian corn.

the plant. This question will be taken up more fully on page 80.
Parts of the Stamens. — An ordinary stamen (Fig. 40) con-
sists of two very distinct parts, the filament or stem, which
corresponds to the petiole and midrib of a leaf, and the anther,
at the tip, which corresponds to the blade rolled or modified so

62

THE FLOWER

as to form small sacs containing a delicate powder, known as
pollen. The stamens also present different forms in the various
plants. They are usually borne on the receptacles, but some-
times appear to be attached to other parts. They are fre-
quently united into groups
and in some plants in such
a manner as to form a tube
enclosing the pistil. The
little pollen sacs have differ-
ent methods of opening
which may be readily seen
with the hand lens and which
will prove very interesting to
the close observer. The pol-
len is very important, ^o
two plants have exactly the
same kind of pollen. It var-
ies in size, shape and struc-
ture. The study of the pollen
of various flowers under the
microscope is very interest-
ing. It is carried by wind
and water, and sometimes by
other means to the pistil,
where it undergoes a growth
which will be described later.
(Chapter VI.)

The Pistil. — There may be one or more pistils. (Fig. 40.)
If one, it may represent one or it may represent many united
leaves. Where there are two or more pistils, they may be en-
tirely separate or they may be partly united. The pistil is com-
posed of an ovary or basal part containing the ovules, which
are to become seeds ; a style, which varies1 in length in different
plants; and a stigma, which is the only part of the plant not

FIG. 49. — Indian turnip or Jack-in-the-
pulpit; a, bulb; b, leaf and spathe; c, spathe
open to show spadrix and flower near the
base.

THE PISTIL 63

covered with an epidermis or skin. The pistils are also subject
to many modifications, but are always borne on the receptacle.
However, if the other organs originate below the ovary, it is
saici to be superior (as in the peach flower), but if they origin-
ate above it, it is said to be inferior (as in the apple blossom).
The arrangement of the organs in the flower can be described
by three terms: liypogynous (Fig. 44), the simplest form,
in which the sepals, petals, and stamens arise from below

Fio. 50. — Squash blossoms. A gamopetalous flower.

X

the carpels; perigynous (Fig. 40), in which the receptacle is
extended into a cup-like structure about the carpels and bearing
the sepals, petals and stamens on its rim and frequently more
or less united at their bases ; and epigynous, in which this cup
envelops the ovary, thus giving the true inferior ovary.

The modified leaves of which the pistil is composed are
frequently called the carpels, and the point of attachment of
the ovules is called the placentae. The placentae may be either
central or parietal (i.e., on the sides of the ovary). The num-
ber of carpels can usually be determined by cutting a cross sec-
tion of the ovary and examining with a hand lens ; the number of
carpels being represented by the number of fibrous bundles
which correspond to the midribs of the leaves of which the

64

THE FLOWER

pistil is composed. The number of carpels does not necessarily
correspond with the number of chambers in the ovary. Of
course, it will be readily recognized that the ovary eventually
becomes the seed case of a dry fruit and that it is also an im-
portant factor in the formation of fleshy fruits.

Fio. 51. — Lily blossom. A polypetalous flower.

Flower Clusters. — The arrangement of flowers on the stem
is called the inflorescence. A few of the most common types
of inflorescence are as follows: (1) The raceme (Fig. 52) in
which a number of flowers are borne along a stem, the lower
blooming first. The minute leaf which is usually at the base
of each flower is called a bract. (2) The corymb is a raceme
in which the pedicels, or little stems, of the lower flowers are
elongated so that the flowers are* practically on the same level.

FLOWER TYPES 65

(3) The umbel (Fig. 53) in which the pedicels arise from the
same point and are practically the same length. (4) The spike
(Figs. 54, 55 and 56) in which flowers are numerous, compact
and sessile. (5) The head (Figs. 57 and 58), in which the
main stem is shortened, giving rise to a cluster of flowers form-
ing a more or, less definite sphere. (6) The spadix (Fig. 49)
in which tho main stem is fleshy and the cluster of flowers en-
veloped in a leaf-like structure called a spathe. (7) The catkin
in which the minute flowers are more or less compact, and tho

FIG. 52. — Toad flax blossoms, showing the open development of the blosaomn.

entire raceme pendant. (8) The cyme which is similar to the
raceme, but which differs from all of the preceding by having the
apical flowers bloom before the lateral flowers. Finally, there
are many special terms which are used for describing other
forms of inflorescence, but which we will omit for the present.

CLASSIFIOATfON

Flower Types — When we stop to think about, or try to
count and record the many plants with which we are familiar,
although we may not know their names, we find that we have
a task which is extremely difficult. But when we realize that
we know only a few of the many hundreds of thousands of
plants of different kinds which are distributed over the face
of the earth, we understand that we must have some very
definite system of classification or grouping by which we will
5

66

THE FLOWER

be enabled to locate aiid record them aiid designate those in
which we are most interested. This system must be the same
throughout the world and for people of all civilized languages.
Several systems have been suggested, used and discontinued at
various times during the centuries that mankind has studied

plants. The one that we now
use is known as the natural
system and is, no doubt, better
than any of the preceding. By
this system, we try to group or
classify plants by their blood
relationships and not upon the
superficial resemblances.

We readily recognize that
apples, pears and quinces are
very much alike. The foliage
on the trees is almost identical,
the flowers have corresponding
parts in the same general ar-
rangements, and if we cut the
fruits we find that they have the same general characters.

Peaches, plums and cherries form another well-defined
group ; they also have flowers and fruits of the same character.
Now if we compare one of the two groups with the members
of the other we find that the flowers of all are very similar
except that in the ovaries and fruits of the two groups they are
quite different. In the first group the ovaries are inferior and
the fruit with a five-parted, papery seed chamber, while in the
second group, the ovaries are superior and have the one stony
seed chamber.

If we take the blackberries and the raspberries as repre-
senting a third group, we find flowers similar to the preceding
but with masses of superior ovaries ; and if we take the wild

FIG. 53. — Wild carrot blossoms. The
umbel type of inflorescence.

FLOWER TYPES

67

rose as representing a fourth group, we again find flowers
strikingly similar to these groups but with inferior ovaries that
never have the development represented by the apple.

FIG. 54. — Sedge or spike type of inflorescence. FIG. 55. — Blue grass inflorescence.

Now, the very great resemblance in all theste groups leads
u? to place them all in the one family, Rosacece.

But in the study of these characters we must make sure that
the resemblances are real and not superficial. The fruits of the
blackberry and mulberry are very similar in general appear-

68 THE FLOWER

aiice, but when we go back to the flower and study them botan-
ically, we find that they are quite different; the fruit of the
former is composed of the many ripened ovaries of a single

FIG. 56. — Rye inflorescence.

flower, while the fruit of the latter is composed of the ripened
ovaries of a number of small flowers.

On the other hand, the potato, tomato, pepper and tobacco

FLOWER TYPES

69

may appear quite different, but an examination of the flowers
shows them to be very similar and belonging to one family
(Solenacece). The flowers of the potato, tomato and pepper are
very similar; the flower of the tobacco is somewhat different,

FIG. 57. — Sunflower head. Composite type of inflorescence.

but has the same general characters; the cultivated potato has
almost the power of producing fruit, but when the fruit is pro-
duced it is very similar to a small tomato ; the fruit of the tomato
is fleshy; the fruit of the pepper very similar but tending to
become leathery ; the fruit of the tobacco is of the same char-
actor but tending to become papery in character.

70

THE FLOWER

The Natural Classification endeavors to group plants in
accordance with true botanical resemblances, and these groups
are combined into larger, until we have the entire plant king-
dom in four large groups. Thus far we have studied flowering
plants only, but the plant kingdom includes many plants which
do not produce flowers or seeds. The principal groups of the
plant kingdom may be represented by the f ollowig outline :

A. Cryptogams
(Seedless plants)

B. Phanerogams
(Seed plants)

1. Thallophytes

2. Bryophytes

3. Pteridophytes

4. Spermatophytes

a. Algae — mostly water

plants.
6. Fungi — plants

without chlorophyll;

moulds, mushrooms,

etc.

a. Hepaticae — Liver -

worts.
6. Musci — Mosses.

c. Ferns and related
plants.

a. Gymnosperms — cone-
bearing plants ; pines,
cedars, etc.

6. Angiosperms — true
flowering plants.

For the present we will not study the Cryptogams or the
Gymnosperms, but will continue our studies on the Angiosperms
or true flowering plants. We have already learned that this last
group is sub-divided into monocotyledonous and dicotyledon-
ous plants, and that in the former the embryo has but one
cotyledon, while in the latter it has two. When we do not have
the seed, or when it is too small for the determination of this
point with ease, the classification may be determined by the
following characteristics of the mature plant : The monocotyle-
donous plants usually have leaves with parallel veins and stems

EXERCISES WITH FLOWERS

71

with irregular arrangement of fibro-vascular bundles (endogen-
ous) ; the dicotyledonous plants usually have leaves with net
veins, and stems with the fibro-vascular bundles definitely ar-
ranged to form a circle (exogenous).

Both groups are sub-divided into orders, and these orders
into families, these families into genera, and
these genera into species. The generic and
specific names constitute the scientific or
Latin name of the plant. The classification
and naming is the same in all civilized
languages. The committing to memory of
classifications and scientific names is wasted
time and useless, unless we understand the
relationship of plants and the basis for their
groupings. However, a careful study of
plants will enable the thorough and closely
observing pupil to classify many plants to
their families and even to their genera with-
out the use of a manual. Students who are
interested in the classification of plants
should secure and use a manual suited to the locality in which
they live.

EXERCISES WITH FLOWERS

1. Plant Studies. — The study should be associated with the plant as
a whole, provided time and material will permit. The following points
should be determined if possible:

(1) Is the plant monocotyledonous or dicotyledonous?

(2) Is it an herb, shrub, or tree?

(3) Under what conditions did it grow?

(4) Describe in brief the root, stem and leaf.
(5.) Is the flower perfect or imperfect?

Is the flower complete or incomplete?

Is the flower regular or irregular?

Is the flower symmetrical or unsymmetrical?

Fio. 58. — Dandelion
head. Composite type
of inflorescence.

72 THE FLOWER

(6) If imperfect, is it monoecious or dioecious?

( 7 ) What is the type of inflorescence ?

(8) Is the flower apetalous or complete?

(9) Is the flower poly- or gamo-sepalous ?

(10) Is the flower poly- or gamo-petalous ?

(11) Is the ovary superior or inferior?

(12) How many sepals, petals, stamens and pistils?

(13) To what are the different sets of organs attached?

(14) If unsymmetrical, describe the parta.

( 15 ) Describe the stamens. How do they open ?

(16) Describe the pistil or pistils. What type of placenta?
How many ovules (estimated by cross and long sections) ?

(17) If a single pistil, how many carpels and chambers?

2. Plant Description. — Having determined the preceding points a com-
plete description of the plant and flower should be written. The pupil is
now ready to use a manual for the determination of the family, genus and
species. The family characters1 should be carefully noted and when an-
other plant of the same family is studied, the pupil should try to determine
the family without the use of a manual.

3- Careful drawings and diagrams should be made of all plants and
flowers studied.

The following types are suggested for these exercises:
Monocotyledonous Dicotyledonous

Lily Rose Potato or tomato

Tulip Apple or pear Sunflower or daisy

Lily of the Valley Peach, plum, cherry Dandelion

Amarillus Blackberry Morning glory

Indian turnip Pea or bean Melon or gourd

Wheat Bloodroot Maple

Oats Mustard Elm

Corn Buttercup Oak

Willow

QUESTIONS

1. What are the parts of the flower?

2. What constitutes the floral envelope?

3. What constitutes the essential organs?

QUESTIONS 73

4. What do you understand by complete, perfect, symmetrical and
regular flowers ? Give examples of each.

o. What is meant by apetalous, gamo-petalous and poly-petalous ?
G. What is meant by monoecious and dioecious"?

7. Wliat is the difference between superior and inferior ovaries? Give
examples of each.

8. Define carpel, placenta.

9. Give the different forms of inflorescence and examples of each.

CHAPTER VI
REPRODUCTION

Reproduction Without Seed. — We have already referred to
some of the methods of reproduction in plants. We have learned
that a bud is an undeveloped stem with its undeveloped leaves ;
and that the cuttings of many plants when placed in moist soil
or in water will grow readily; that is, the buds expand, a root
system is developed and a new plant possessing a complete set
of organs like the parent is formed. In nature many plants, such
as the willow, shed twigs which catch in the soil and grow. This
growing of twigs explains the rapidity with which willows come
into existence along water courses. Many grasses and other
troublesome plants increase in number as a result of having the
underground stems torn in pieces by farming tools, thus per-
mitting each bud to form a new plant. We know that this power
of buds to grow makes it possible to perpetuate many valuable
varieties by cuttings, budding, and grafting. These methods
are the common practices of florists, nurserymen, orchardists
and others who wish to produce large numbers of plants of def-
inite varieties.

Many plants are grown almost exclusively from the tubers
or bulbs which we now recognize as forms of stems (Chapter
IV), and many of these plants have partly or entirely lost
their power to produce seeds. Plants which have lost this
power to produce seeds must be grown entirely from bulbs, or
cuttings, or by budding or grafting.

We know that, although roots do not generally produce
buds, many plants are propagated by shoots developed from
adventitious buds formed on the roots. The sweet potato
74

THE TRANSFER OF THE POLLEN 75

is a notable example of a root producing buds and young
plants. And finally we know that even the leaves of some
plants have the power to produce buds which will grow into
plants. But this is not so strange as it may first appear, when
we stop to consider that the ovules which develop into seeds
are a part of the pistil which is a modified leaf. It is very
evident that the preceding methods of reproduction by buds
is very rapid and that a large number of new individuals like
the parents can be produced in a very short time. It is known
as the asexual or non-sexual method.

By Flowers and Seeds. — However, the most important, the
most complicated, and the highest method of reproduction is
by means of seeds which are the result of the sexual activ-
ities of the plant. In all the preceding methods of reproduction,
each young plant has but one parent. But in reproduction by
means of seeds each plant, with a few exceptions (Chapter V),
has two parents. The stamens may be considered the male
organs and the pistils the female organs, and the process of
seed production may be briefly described as follows : Within the
anthers are borne great numbers of pollen (Fig. 59) grains
which are readily recognized as the powder which is so abun-
dant in the large lilies and many other flowers. This pollen
must be transferred to the stigma of the pistil of the same or
another flower. (Fig. 60.) You will recall that the stigma
is the only part of the plant that is without an epidermal cov-
ering. (Page 62.)

The transfer of the pollen is sometimes accomplished by
some of the many insect visitors that are attracted by the honey
or odor of the flower, or by humming birds, or in some cases
by the wind. The transfer of the pollen is called pollination,
and should not be confused with fertilization. Each pollen
grain is a single cell which undergoes a growth resulting in the
formation of a long, dedicate tube which grows downward

76

REPRODUCTION

through the style and eventually reaches the ovule. The tube
enters the ovule usually through the micropyle (Chapter 1),
which persists and is plainly visible in many mature seeds. In
the meantime, interesting changes are going on within the small
ovule, which results in the formation of a minute chamber
known as the embryo sac. (Fig. 61 a.) This sac contains
eight minute cells, one of which is known as the ovum or egg.

FIG. f>9. — Types of pollen grain.

Tho tip of the pollen tube finjilly reaches this egg cell and n
certain nucleus from the tube unites with the nucleus of the
egg. This is the process of true feriHization, and this fer-
tilized egg now develops into an embryo or young plant (Fig.
01 b) surrounded by a supply of rich food for its future nour-
ishment. This embryo, together with its food supply and cover-
ings, constitutes the seed. (Chapter V.) The parts involved
in this process, are so small that it is impossible to see them
without using a compound microscope, and the study of this
delicate and complicated process must necessarily be reserved
for the more advanced students of botany.

^o two plants in nature are ever exactly alike and, there-
fore, if thei pollen of one plant falls on the pistil of a slightly

DIFFERENCES IN STRUCTURES OF SEEDS

77

different plant of the same or a closely related species or variety,
the new plants should possess some characters of both parents,
This gives a basis for work in the production of new varieties of
plants. (Chapter XV.)

Differences in Structures of Seeds. — There are some facts
concerning the structure of the seed which
we have already learned, but which we
should now recall in the light of these new
facts. (Chapter VII.) The young plant
or embryo consists of a very short stem on
one end of which is a root tip; and on the
other end a plumule, or bud, and one or two
cotyledons or primary leaves. It is a com-
plete plant possessing the three essential
parts: root, slem, and leaf. We will recall
that the seeds of corn and castor oil plants
contained embryos surrounded by an abund-
ant food supply for their nourishment dur-
ing the period of germination and before
they had become firmly established as inde-
pendent plants. We will also recall that in
the bean we found a much larger embryo
without the surrounding food supply. In this case the food for
the early growth of the young plant was in the cotyledons.

The seeds of corn and castor oil plant matured very early
when the embryos were small, but with a good supply of stored
food for the growth of the embryo during germination. The
seed of the bean matured much later, the embryo having ab-
sorbed the surrounding food supply and stored it in the coty-
ledons previous to maturity. In the corn, the single cotyledon
is an organ which serves for the absorption of the food supply;
in the castor oil plant the cotyledons serve first as organs of
absorption and later as the primary leaves; in the bean they
serve for the storage of the food supply and as primary leaves.

FIG. 60. — Diagram-
matic longitudinal sec-
tion of ovary showing
developing ovules.

78

REPRODUCTION

The examination of the seed of a large number of differ-
ent kinds of plants will show great variation in the relative
sizes of the, embryos and the amount of the food supply, and
will suggest many germination tests and growth experiments.

b

FIG. 61. — a, diagrammatic drawing of stamen and pistil showing longitudinal section of
ovule. The pollen tube is entering through the micropyle; b, longitudinal diagrammatic sec-
tion of ovule showing the formation of the embryo.

Advantages of the Seed Method. — It is very evident that
sexual reproduction is higher and more complicated than non-
sexual reproduction, but let us see if it is of any advantage. It
is necessarily much slower than reproduction by buds, but the

INSECT POLLINATION 79

dry seeds of a plant can undoubtedly resist greater extremes
and longer duration of heat, cold and drouth than buds and
can be carried to much greater distances by natural means and
by man. Many believe that sexual reproduction gives the
plants much more vigor than non-sexual reproduction. This
belief seems to be supported by the fact that when some varieties
of plants are grown continuously from cuttings, tubers or bulbs,
they tend to. lose their original varietal characters and vital-
ity. Sexual reproduction, owing to the fact that the two
parents are never exactly the same, tends to cause variations in
plants, and results in new varieties. This tendency to pro-
duce variations is greatly increased by cross breeding different
varieties and has given rise to some of our most valuable fruits,
vegetables and ornamentals. (Page 148.) The transfer of the
pollen from the stamens to the stigma is known as pollination
and should not be confused with fertilization. (Page 76.).

Pollen may be carried by the wind, and some of our most
valuable plants depend entirely upon the wind for pollination.
The corn, and other grains and grasses belong to this class. The
tassel of the corn is a mass of small staminate flowers, while
each thread of the silk represents a pistil with a single grain
of corn for its ovary. During the blooming season there is a
rain of pollen grains, some of which fall upon the silk. Of
course, this is in a sense very wasteful for the number of
pollen grains which are lost is infinitely greater than the number
which fall upon the silk (i. e., pistils).

Insect Pollination. — The great majority of our flowering
plants are pollinated through the agency of insects, which visit
the flower primarily to collect the nectar and pollen. Many
insects use the nectar immediately for food, but the bees take
it into their bodies where it undergoes chemical changes by
which it is transformed into honey and then stored up for
future use. Many insects are doubtless attracted by the odors
of flowers and some few may be attracted by the color, although

80 REPRODUCTION

we should remember that it is extremely doubtful if insects can
distinguish shape, size or color for any considerable distance.

Interesting modifications of their parts are found in many
flowers. These facilitate pollination by means of insects, and
some flowers are so specialized that certain insects are neces-
sary for this work. Among the simplest of these modifications
is the long tubular corolla of the morning glories and honey-
suckles which make it necessary that their visitors have long
beaks or mouth parts by which they can reach the nectar glands
at the bottom. The tubular corolla of the red clover is such
that it is imperfectly pollinated except by the bumble bee and,
therefore, it is practically impossible to grow red clover seed
without these insects. The barberry, and some other plants,
have stamens of such character that when touched by the in-
sect they serve as springs, striking the anthers against its body.
The milkweed and other plants are so constructed that masses
of pollen may cling to the body of the insect and be carried
from flower to flower, losing some pollen with each visit. Beans,
peas, and similar flowers have peculiarly shaped corollas which
conceal the essential organs, but when the insect settles upon
them these parts are exposed and the lower surface of the body
brought in direct contact with them. A thorough discussion
of the devices for facilitating the pollination by means of insect
visitors would require a large volume and then be incomplete,
but it is a subject in which any close observer can learn some-
thing previously unknown, something not jn the books.

Cross Pollination. — It will be readily seen that sexual
pollination is usually accomplished by the pollen of one flower
on the stigma of another flower of the same or a different plant.
This is known as cross pollination and, of course, results in
cross fertilization which, as previously stated, is believed, in
many cases, to give increased vigor to the new generation of
plants. If this is true, we are certainly justified in expecting
to find some modifications in nature which prevent self-pollin-

DICECIOUS PLANTS 81

ation. If we examine flowers carefully we will find some in
which the stamens and pistils mature at different times and,
therefore, it is impossible for the flower to be pollinated by its
own pollen. Of course, the flowers do not open at the same
time and pollen of some flowers will mature at just the right
time to be transferred to, and grown on, the stigma of others.
Sometimes the flowers will be pollinated from other flowers of
the same plant and sometimes by flowers of different plants.
In some plants we can see the effects of this cross pollination
in the seeds, as in the case where corn of one color has been
pollinated by corn of another, resulting in the speckled or mixed
ears. But in most plants we do not see the results of cross
pollination until we grow the new plants. Cross pollination is
accomplished in various ways. Some plants have two kinds of
tubular flowers, some with short stamens and long pistils, and
others long stamens and short pistils. The insect visiting the
first flower gets pollen on the front part of its body; visiting
the latter it leaves some of the pollen on the short pistil and gets
a load of pollen on the back part of its body. Therefore, it is
practically impossible for the flower to be pollinated with its
own pollen. Some plants, especially cultivated varieties, have
impotent pollen and, therefore, cannot be pollinated with their
own pollen or with pollen from plants of the same variety.
Many apple, pear and plum growers mix their varieties in the
orchard so as to insure pollination and thus get the stimulating
effect of fertilization and secure a richer harvest. In some cases,
growers may even set a few trees of an inferior variety in order
to secure satisfactory cross pollination of the desirable varieties.
In some plants, such as the common banana, the pollen is useless
and the plants no longer produce seeds.

Dioecious plants (Chapter V) are necessarily cross pollin-
ated, and many savage and half-civilized races learned, many
centuries ago, the necessity of growing the staminate as well
6

82 REPRODUCTION

as the pistillate trees, although they had no explanation for this
phenomenon of nature.

Self-Pollination. — However, the flowers of some plants are
very generally self-pollinated. Wheat belongs to this group or
class.

Buds That Never Open. — The buds of some flowers never
open, making cross pollination impossible. Such flowers are
called cleistogamous. Some species of violets produce incon-
spicuous cleistogamous buds under the leaf -mold, these buds pro-
ducing abundant seeds, while the showy flowers of these species
are usually sterile.

EXERCISES IN POLLINATION

1. Carriers of Pollen. — Observe flowers and note the insects which
visit them. Are the different species of flowers visited by the same species
of insects? Do the insects exercise a choice in visiting flowers?

2. Examine pollen of a number of flowers under the microscope. Make
drawings.

3. Pollen Growth in Sugar Solution. — Make a solution by boiling
one part of sugar in ten of water. Put a spoonful into each of several
watch glasses. Mix the pollen of several flowers into them and keep cov-
ered. Examine a drop of the fluid with pollen under the miscroscope from
time to time and note the germination.

QUESTIONS

1. How* do you account for the rapid increase in numbers of willows
and similar plants along water courses?

2. Can other plants be produced in a similar manner?

3. How do we make! use of this power of .reproduction in the grow-
ing plant?

4. How are many grasses and other pests frequently propagated?

5. Give a list of plants that grow from bulbs.

6. Give a list of plants that grow from tubers.

7. Give a list of plants that are seldom of never grown from se"eds.
How are they grown ?

8. Do roots produce buds? Give some exceptions.

9. Explain pollination.

10. Explain fertilization.

11. Explain cross pollination.

12. Explain self-pollination.

13. Explain cleistogamous seed production.

WE make use of plants in a great many ways, but the most
important way is as food for the sustenance of life of man
and beast. Among the most important parts of the plants used
for this purpose are the seeds and fruits. However, these terms
(fruit and seed} are very indefinite and should be used with
care. Fruits and vegetables are frequently confused; the to-
mato is usually spoken of as a vegetable, although the edible
part does not differ materially from many true berry fruits.
Botanically, a fruit is the ripened ovary, or the ripened ovary
with such other parts as may be united to it. However, some
fruits, such as the banana and the navel orange, have lost the
power to produce seeds and the fruit consists of only the ovary.
They are known as seedless fruits, and these plants must be
propagated by some of the non-sexual methods previously re-
ferred to. (Chapter VI.) Although we usually think of fruits
as being fleshy structures, the cotton boll, a gourd, a pepper
pod, or a bean pod are fruits as truly as is the peach or apple.
The seed is the mature ovule with its enclosed embryo, or as we
may have learned, the embryo with food supply and coverings.
The final result of plant energy is the production of its kind
and the distributing of its offsprings as far as possible. Each
species of plant, if uncontrolled by climate, water, soil, animals
and other plants would eventually tend to occupy the entire
earth. But many plants cannot spread beyond a certain limit,
because of the extremes of the climate; others are checked for
want of suitable soil ; others by bodies of water or desert plains ;
and still others by coming into competition with other plants
which are stronger and crowd them out. Man has taken advan-

83

84 FRUITS AND SEEDS

tage of this tendency of plants to reproduce themselves 'and to
vary their characters, and has selected those which are the best
suited to his purposes, and has protected and cultivated them.
By his intelligent management he has increased their value to
himself. (Chapter XV.)

For convenience we will classify fruits as follows :

Drupe . .

{Simple drupe

Fleshy

Pome

Aggregate
Multiple

Berry
Accessory

Dehiscent ....

f Pod or capsule

Dry

I Legume

±jij . .

Indehiscent . .

f Achens
1 C'aryopsisi
I Samara or key
' Nut

The drupe or stone fruit has the seed surrounded by a
strong, or hard, stony growth (endocarp) which is, in turn,
surrounded by a fleshy growth (exocarp). The stony and
fleshy growths constitute the ovary.. The peach (Fig. 62),
plum and cherry are of this type, and each fruit is a
.single or simple ovary derived from a single flower. (Page 55.)
There are several modifications of the simple drupe which
are given special names, but the differences are superficial.
They are:

(a) The aggregate fruit which consists of a number of
ripened, fleshy pistils derived from a single flower. The black-
berry and raspberry are excellent types.

(6) The multiple fruit which consists of a number of small
single pistils each derived from a single flower. The mulberry
is a type. Although the blackberry and mulberry fruits show

THE POME

85

a very striking superficial resemblance, they are radically differ-
ent; the former representing a single*, rather large flower
with many pistils, and the latter a number of very small flowers,
each having a single pistil. None of the above are true berries
from the botanical viewpoint, but the name is so closely asso-

FIG. 62. — The peach, the drupe type of fruit.

ciated with them that it is practically impossible to make a
change.

The pome is a fruit in which the ovary, or ovaries, the
calyx and receptacle are united, both becoming fleshy. The tips
of the sepals persist at the blossom end of the fruit and the

86

FRUIT.S AND SEEDS

endocarp develops as a papery core. The apple (Fig. 63), pear
and quince are typical of this group.

The true berry is a more or less leathery -structure enclosing
a mass of seeds. It may consist of the ovary only, or of the
ovary enclosed in the calyx. Many plants belonging to a great
diversity of families produce fruits of this type. Among the

FIG. 63. — The apple, the pome type of fruit.

most important are the gooseberry, huckleberry, cranberry,
grape, orange, melon and cucumber. However, melons, cucum-
bers and gourds and other fruits belonging to the family Cucur-
bitacece are frequently given a special name of " pepo."

The accessory fruit is the fleshy receptacle of a single flower
covered with achenes which are usually called seeds ; the straw-
berry belongs to this type.

The dry fruits are those in which the ovaries develop into
dry pods. If this pod opens and releases the seeds it is dehiscent

THE NUT

87

(Fig. 64, a), but if it does not open until burst by the germi-
nating seed, it is indehiscent. (Fig. 64, &.)

The term pod or capsule will apply to any of the dehiscent
fruits, regardless of the number of carpels involved in its
formation. The term legume applies to those peculiar elongated
pods (Fig. 64, a) of the leguminosew or pea family, each of
which represents a single capsule of two valves and a single
placentae.

The indehiscent fruits are :

(a) The achene, a small, dry, one-seeded pod representing
one or more carpels. (Fig. 64, b.)

FIG. 64. — a, legume or dehiscent pod ; b, an achene or indehiscent pod cut so as to show the
enclosed seed; c, caryopsis or grain showing the pericarp or ovary, the integument or seed
coat, the aleurone cells and the starch area; d, samara or key fruit; e, acorn or nut type.

(b) The caryopsis or grain in which the pod or ovary is
united to the seed. (Fig. 64, c.)

(c) The samara or key in which the pod is developed into
a thin flat wing. (Fig. 64, d.)

(d) The nut is a single seed in which the ovary is developed
into a hard, bone-like or horn-like covering.

There are several types of nuts, such as the acorn (Fig. 64, e)
which is a cup formed of involucral leaves ; the hazelnut, chest-
nut, and beechnut, in which the nuts are enclosed in a pod also
formed of involucral leaves ; the hickory nut inclosed in a shuck,
probably composed partly of calyx and partly of involucral
leaves, which tend to split when dry. The walnut is of the same
type as the hickory nut, but does not tend to split ; it is some-

88 FRUITS AND SEEDS

what fleshy and resembles the drupes, but the fleshy part is of
an entirely different origin from that of the true drupes.

Fig Type. — There are some fruits which are difficult to
classify in any of the preceding groups and must be distin-
guished by special names. Among the most important is the
synconium or fig fruit which is derived from an enlarged, soft,
hollow stem enclosing a large number of very small flowers
which are never exposed. Many people believe the fig produces
fruit without blooming, but this is not true.

Seed Distribution. — If seeds are to fulfill their place in
nature they must be distributed over a considerable range of
country. If they are all dropped within the immediate vicin-
ity of the parent plant, the new plants will be too crowded, the
weaker cannot survive, and the vigor of both parent and off-
spring will be impaired. Seeds are mostly carried by wind
and water, by animals and by man. It is very evident to the
most casual observer that of the enormous quantities of seeds
produced by a single plant, very few can ever serve their primary
purpose in nature, that of producing new plants. The majority
will be eaten by animals, or will fall in unfavorable places where
they cannot germinate, while many of those that do germinate
will never grow to maturity. (Fig. 65.)

Carried by Water. — It is very easy to understand how seeds
can be carried from place to place by water. Those that are
buoyant will be carried along by streams, or float over the
surfaces of lakes. Those that will not float may be carried along
in the mud and debris. Heavy rainfall will carry many seeds
for considerable distances and will frequently cover them with
earth. Seeds that float are frequently propelled by wind and
carried for long distances over lakes and other large bodies of
water. Seeds from plants growing near the salt water will
frequently be carried for long distances by means of water and
wind and find a resting place on other shores. Of course, it is

RESISTANCE TO HEAT, COLD AND DRYNESS

89

important that seeds, which are carried in this manner, shall
be of such character as not to be easily injured by long sub-
mergence in water, and this is especially true of those seeds
which are carried by salt water. The cocoanut is a striking
example of a large floating seed which frequently is carried
on the salt water. The vegetation of the volcanic and coral

FIG. 65. — Devices for seed distribution.

islands of the sea frequently owes its origin to seeds of this
type.

Resistance to Heat, Cold and Dryness. — The seeds of many
plants are also, resistant, to extreme drying and to extreme heat
and cold. The seeds of some plants will lie in the soil for
years waiting until the conditions are favorable for their germin-
ation, while the seeds of other plants will perish in a few
weeks or months, even when kept under the most favorable
conditions.

90 FRUITS AND SEEDS

Carried by Wind. — We have all observed the dispersal of
seeds by means of the wind. Of course, strong air currents
will carry light seeds for great distances, but many seeds have
special structures which are very important in this work. The
maple, ash and elm have membranous wings, or outgrowths by
which the wind carries them. These outgrowths are a part
of the ovary. The dandelion, lettuce, thistle and many other
plants have seeds which are enclosed in the ovary (achenes),
on which is developed a downy outgrowth serving as an air
float, a sort of balloon or parachute. The seeds of the milkweed
bear a superficial resemblance to those of the dandelion, but are
quite different. You will recall that the dandelion is an inde-
hiscent fruit, while the milkweed is dehiscent. The outgrowth
on the former is from the ovary; on the latter from the seed
coat. Some plants, especially weeds, of which the tumble weed is
the most striking example, will break loose and be carried by the
wind for great distances, distributing their seeds as they travel.

Carried by Man and Animals. — The lower animals are the
involuntary carriers of many seeds, and man, the highest of
the animals, is both an involuntary and a voluntary carrier.
The seeds of many fruits will pass through the alimentary canal
of animals unharmed and will grow if dropped in suitable
places. Squirrels and other animals bury nuts and other seeds
which grow ; while birds accidentally drop the seeds of cherries,
berries and other fruits, here and there. Burs and many other
seeds have spines or hooks by which they cling to animals. Man
carries many seeds in feed and bedding for himself and live
stock, in packing materials, and in grain for various agricultural
and commercial purposes. The shipping of grain and grass
seeds from country to country has been the means of introduc-
ing many of our most troublesome weeds.

Seeds Thrown. — Many plants have peculiar devices by
which seeds are thrown for considerable distances. The touch-

EXERCISES CONCERNING FRUITS AND SEEDS 91

me-not is an excellent illustration of this last method. The pod
splits suddenly and the parts curl with such force as to throw
the seeds out.

EXERCISES CONCERNING FRUITS AND SEEDS

1. The Peach, — Examine the fruit of the peach. What part of the
flower is involved in its make-up? How many carpels does it represent?
Note the fleshy exocarp, the hard endocarp and the seed.

2. Blackberry. — Examine the fruits of the blackberry or dewberry
What part of the flower? How many carpels? Where are the exo- and
endocarps ?

3. Compare the fruits and tell how the blackberry differs from the
raspberry.

4. Compare the fruits and state how the strawberry differs from the
blackberry.

5. Compare the fruits and state how the mulberry differs from the
blackberry.

6. Apple. — Examine the fruit of the apple or pear. What parts of
the flower are involved in its make-up? How many pistils and carpels
does it represent? How does the endocarp differ from that of the peach?

7. Gooseberry. — Examine the fruit of the gooseberry. What parts
of the flower are involved in its make-up ? How many pistils and carpels ?
What is the dry part on the tip?

8. Melon, Orange and Tomato. — Cut a melon or cucumber, an
orange and a tomato in cross- section. Study in the same manner as the
gooseberry.

9. Seedless Fruits. — Cut a navel orange and a banana in cross-sec-
tion and study in the same manner. How do they differ?

10. True Pods. — Examine the pod of a bean or pea or similar dry
fruit. How many pistils? How many carpels? Where are the seeds
attached ?

11. Examine as many other forms of pods as possible and answer
the same questions.

12. Winged Fruits. — Study the seeds of the maple, dandelion, etc.,
for methods of distribution.

13. Study the seeds of the milkweed and compare with the dande-
lion.

. 14. Burs. — Study burs, stick-tight* and other seeds for special devices
for distribution.

92 FRUITS AND SEEDS

15. Explosive pods such as the touch-me-not and witch hazel should
be collected. Note their- explosive power.

It). Examine bladdery seeds and ovaries of .such plants as may be
available.

QUESTIONS

1. What is a fruit?

2. What is a seed?

3. Give the different types of fruits.

4. Define each.

5. Give examples of each.

6. Give different methods of seed distribution and examples of each.

CHAPTER VIII
ANATOMY OF STEMS, ROOTS, AND LEAVES

WE HAVE learned that stems are composed of strands of
woody, fibrous material embedded in a softer substance or pith,
and that this entire structure is enclosed in a water-proof sheath
of epidermis or bark. We have also learned that the arrange-
ment of these strands of fibrous material, which arc known as
fibro-vascular bundles, is different in the moiiocotyledonous and
dicotyledonous stems. In the former (Fig. 66) they are dis-
tributed throughout the stem except in those plants in which
the stem is hollow, while in the latter they are arranged in a
circle. (Fig. 67.) This difference in the arrangement of the
mono- and dicotyledonous stems enables us readily to recognize
these two groups of plants. (Chapter III.)

Cellular Structure. — If we can examine cross and longitud-
inal sections of a moiiocotyledonous stem with a microscope, we
will find that the pithy part of the stem is composed of large,
thin-walled cells. (Fig. 68.) We have previously referred to
cells, but have not given an explanation of them. All parts of all
plants are made up of cells of which this is the simplest type.
The cell is the unit of the plant structure, the same as a brick
or a stone may be the unit of a building. The name " cell "
was given by the students of botany, soon after the invention
of the microscope, who saw the plant as a structure composed
of many minute, apparently empty boxes or cells. Later
students learned that these cells when young and active con-
tained a substance which we now call protoplasm, (Fig. 60),
and still later students learned that protoplasm might exist with-
out being enclosed in a cell-wall. Therefore, the definition of

93

94

ANATOMY OF STEMS, ROOTS, AND LEAVES

a cell was protoplasm which may be either naked or enclosed in
a cell-wall, or a small microscopic chamber from which the
protoplasm has been withdrawn.

The protoplasm is an albuminous substance more nearly like
the white of an egg than any other substance with which we can
compare it. It is that part of the plant in which the life is
said to exist, and, so far as we know, is not different from the
protoplasm of the animal cell. In its active condition, it is

FIG. 66

FIG. 67

FIG. 68

FIG. 66. — Cross-section of monocotyledonous stem showing arrangement of the fibro-

vascular bundles.
FIG. 67. — Cross-section of dicotyledonous stem showing arrangement of fibro-vascular

bundle.
Fia. 68. — Parenchyma cells.

very sensitive to change of humidity, temperature, and to poison-
ous substances. The active growing cells of the plant are rich
in protoplasm, but many cells which persist throughout the
entire life of the plant die and lose their protoplasm. In fact,
the great bulk of the cells of most of our higher plants is dead.
The cell can be studied to the best advantage in some of the
water plants, especially the algae, which will be studied later.
If we examine a very small amount of one of these plants known
as Spirogyra under the microscope, we find that it is made
up of a single row of elongated cells placed end to end. These
cells appear to be rectangular, but they are cylindrical tubes
closed at both ends. We very readily recognize the cell-wall and
the chlorophyll, which is in a body known as the chromatophore.

95

If we examine the cells of other plants, we find that these chrom-
atophores vary greatly in size and shape. The other parts of
the cell are not so easily recognized. But if we will keep some of
the algse in alcohol for a few hours the chlorophyll will be partly
or entirely removed so that we can recognize the very delicate
layer of protoplasm lying next to the cell-
wall and also delicate strands extending
across the cell. This will be greatly
aided by treating the algae with eosin or
some other coloring matter which will
stain the protoplasm. In this plant, the
protoplasm does not completely fill the
cell, but there are large spaces which are
filled with water or air and known as
vacuoles. We will also be able to recog-
nize the nucleus which is a very import-
ant part of the cell.

The nucleus is protoplasmic in char-
acter and very complicated in structure.
It is present in nearly all living cells, and
when the cell divides the nucleus also divides, one part going
into each new cell. In a few plants, the cells are multinuclear,
and when they divide some nuclei are found in each new cell.

Cells also contain many compounds. The most prominent
is the starch, which can be readily recognized by examining
a very thin section of potato or apple under the microscope.
If we treat this section with iodine, the starch grain will turn
blue. The starch grains of different plants differ in size and
form; this fact enables the microscopist to decide on amount
and character of many adulterations of foods and drugs. The
cells also contain sugar, fats, oils and other compounds which
will be discussed later. (Chapter IX.)

As the plant grows the cells undergo many changes and modi-
fications. These variations are much more pronounced in the

FIG. 69. — A typical plant
cell showing protoplasm.

96

ANATOMY OF STEMS, ROOTS, AND LEAVES

higher or flowering plants than in the lower forms. Some cells
have thin walls and contain a great deal of food materials which
make them valuable foods for man and other animals. Some
are fibrous in character and have thick walls which make them

Fia. 70.— Cross-section of fibro-vascular bundle from corn stem.

useful in many industries. We will give a brief discussion of
these different types of cells.

Parenchyma. — The cells of pith are large, somewhat vari-
able in size, thin-walled, more or less spherical in shape and
usually show irregular spaces between them. They are known
as parenchyma or soft cells. (Fig- 68.)

The great majority of the cells of fruits, grains and other
edible parts of plants are made up of parenchyma cells. Their

EACH FIBRO-VASCULAR BUNDLE

97

value as food depends on the size of the cells, the thinness of
the cell-walls, the amount and digestible character of the food
(carbohydrates, hydrocarbons, proteids; Chapter IX) which
they contain, and the absence of poisonous or injurious
compounds.

Each fibro-- vascular bundle is made up of a variety of cells.
In the young bundle of the monocotyledonous stem (Fig. TO)
is a small group of cells known as the cambium. They have the

FIG. 71. — Tracheary tissue.

power of rapid growth and division and are primarily respon-
sible for the increase in diameter of the monocotyledon stem.
After a comparatively short time they lose the power of division
and this checks the increase in diameter of the stem. On one
side of the bundle will be a mixture of large and small cells
constituting the woody part. Some of these cells have peculiar
thickenings of the cell-walls forming rings, spirals, pits, etc.
They are known as tracheids and tracheary cells. (Fig. 71.)
On the oppositei side of the bundle is a group of small, thick-
walled cells constituting the fibre or bast. (Fig. 72.) There
are other types of cells which will be described later. A mono-
cotyledonous stem increases in diameter for a limited time only,
partly by the increase in the size of the fibre-vascular bundles
7

98 ANATOMY OF STEMS, ROOTS, AND LEAVES

and partly by the increase in number of bundles. The hard
outer covering of the corn and similar plants is composed of
these nbro-vascular bundles.

The dicotyledonous stem has bundles made up of the same
kind of cells which are arranged very differently. The outer
part of the bundle contains the bast ; the inner, the woody cells ;
and between the two groups lies the cambium which persists
throughout the entire life of the plant. The cells of the cam-

Fia. 72. — Fibrous tissue; bast and wood cells.

bium form a continuous layer of living, growing cells. These
cells divide repeatedly cutting off inner layers which go to form
layers of wood and outer layers which eventually help to form
the outer parts of the stem. All the other types of cells are
derived from these cambium cells. Among the bast cells are
the peculiar, sieve cells (Fig. 73) or tubes, so called because of
the peculiarly perforated cross walls. On the opposite side of
the cambium are a number of cells and tubes which have peculiar
thickenings on the inside of the walls. If the cells are short,
more or less tapering at the ends and with numerous pits in the
walls, they are known as traclieids, but if they are elongated into
tubes in which the wall thickenings take the form of spirals,
^ings, pits, etc., they are known as tracheary tissue. (Fig. 71.)
This term is also used to include the tracheids. This tracheary
tissue is surrounded by long fibrous or wood cells. (Fig. 72.)
The outer part of the bundle containing the sieve and bast cells
is called the phloem region ; the inner part containing the trach-
eary and wood fibre is called the xylem region.

THE DICOTYLEDONOUS STEM

99

In the centre of the stem is the pithy stele composed of
parenchyma cells. The fibro-vascular bundles are also separated
by masses of thin- walled cells called the medullary rays (Fig.
74), and the entire structure is enclosed in an epidermal mass
of cells known as the bark. In soft stems of the herbaceous
plants, geranium, etc., the bundles are separated by thick medul-
lary rays while in hard, woody stems of the tree, the rays are
very thin. In the stems or trunks of young trees, the bundles are

FIG. 73

FIG. 74

FIG. 73. — Sieve tissue.

FIG. 74. — Cross section of dicotyledonous woody stem, showing annual rings, medullary

rays and bark.

few and the rays thick, but the number of bundles increases and
the rays become thinner and thinner with age. If we cut across
a large stem, i.e., the trunk of a tree, we can readily recognize
the small point in the centre which we call the pith or stele,
the colored heart-wood, the sap-wood, and the bark. We will
also note the great number of circles known as the annual
rings. (Fig. 74.) In many trees, each ring represents one
year's growth. We will also observe a large number of lines
which radiate from the centre and are known as medullary rays.
(Fig. 74.) In young stems these rays are composed of paren-

100 ANATOMY OF STEMS, ROOTS, AND LEAVES

chyma cells and are a coutinuatiou of the pith cells ; but in older
stems they are frequently compressed into extremely thin, flat
layers of cells separating the fibre-vascular bundles.

The bundles increase in number with the age of the plant.
In young stems the bark is soft and greenish in color and can
be readily separated from the underlying woody parts. In the
older stems the outer bark is dead and freqtiently cracked and
conceals the soft or true bark. In peeling the stem the separa-
tion sometimes occurs in the cambium. The increase in the
number of cells in the dicotyledonous stems is confined almost
entirely to the cambium layer of cells which produces new cells
for both the xylem and the phloem. Therefore, it will be readily
seen that the formation of the new layers of xylem cells results
in increasing the diameter of the stem without increasing lln1
inner diameter of the cylinder of bark. This increase of the size
of the stem must necessarily exert a considerable strain on the
bark covering, which results in the very slow splitting and peel-
ing of the outer bark. This explains the roughness of the bark
of most of our trees and the characteristic natural peeling of
many others. As the old, outer bark is gradually shed, the
newly formed inner bark becomes the outer and new layers
are formed from below.

Cause of Annual Rings. — The formation of the cells of the
xylem is not uniform throughout the season. In our northern
climate, the cells formed in the first part of the growing season
are larger and have thinner walls than those formed later. This
difference causes the so-called annual rings.

Sap-Wood. — The light-colored sap-wood is composed of cells
in which there is little or no growth, but which contain more
or less protoplasm.

Heart-Wood.— The dark-colored heart-wood is composed of
cells from which the protoplasm has disappeared. They are

THE ROOT

101

dead cells but are sound and give support to the trees. Some-
times the heart- wood decays and the tree becomes hollow but
continues to live and grow so long as the cambium is uninjured.
The root (Figs. 75 and 76) is composed of the same tissues
as the stem, but they are arranged in an entirely different man-
ner. In the centre is the central cylinder or axis made up of
fibro-vascular bundles which are separated by thin layers of
parenchyma. Immediately surrounding this axis is a compar-
atively thick zone of parenchyma cells known as the cortex. This

FIG. 75

FIQ. 76

FIG. 75. — Diagrammatic longitudinal section of root tip showing: a, axis cylinder; c, cortex;

e, epidermis; x, root cap.
FIQ. 76. — Cross-section of root tip showing cellular structure and root-hairs.

is surrounded by a very thin layer of cells known as the epi-
dermis. The epidermis of the very young roots gives rise to a
great number of extremely delicate root hairs which penetrate
the soil and take the water and necessary substances which may
be in solution. (Page 26.)

102

ANATOMY OF STEMS, ROOTS, AND LEAVES

The structure of the leaves varies somewhat in the different
plants. Probably the most common form is that which we will
describe. The typical leaf may be said to be composed of four
layers of parenchyma cells supported by delicate frame work
of fibro-vascular bundles. The upper layer of cells is the upper
epidermis and consists of thick-walled, transparent cells ; below
this is the layer of columnar or palisade cells which are elon-

FIG. 77

FIG. 78

Fia. 77. — Cross-section of leaf showing: u, upper epidermis; p, palisade cells; m, mes-

ophyll cells; 1, lower epidermis; s, stomata.
FIG. 78. — Lower surface of leaf showing stomata.

gated, more or less cylindrical and placed at right angles to the
epidermal layer ; just below the palisade, layer is a thick layer
of loose, irregularly shaped parenchyma cells known as the
mesophyll; just below the mesophyll is the last layer or lower
epidermis which is very similar to the upper epidermis. The
palisade cells are rich in protoplasm and in the green coloring
matter which is known as the chlorophyll. The chlorophyll is
usually confined to very definite small bodies known as chloro-
plasts and is essential for the photosynthesis work of the plant.
(Page 115.)

EXERCISES SHOWING MINUTE STRUCTURES

103

In the lower epidermis will be found a considerable number
of small openings or stomata (singular stoma) (Figs. 77 and
78), leading into the irregular tunnels or intercellular spaces
found between the cells of the
mesophyll. Each stoma or open-
ing is between two crescent-shaped
cells called guard cells. The func-
tion of these parts will be consid-
ered in Chapter X.

Hair-like Growth on Leaves. —
The leaves of some plants are very
smooth while others have more or
less delicate hair-like growths
known as trichomes. (Fig. 79.)
(Chapter IV.) These trichomes
are so numerous on the leaves of
some plants as to give them the
appearance of velvet. These
structures are also found on the
young stems of many plants. They
are outgrowths of the epidermal
cells and present numerous very
interesting forms. Some of them
are glandular in character, and cause the plant to feel sticky to
the touch. They are, no doubt, protective in many ways.

EXERCISES SHOWING MINUTE STRUCTURES

1. Pith. — Cut a very thin section of a pith, mount in a drop of
alcohol and glycerine and examine under the microscope. Note the
large, thin-walled parenchyma cells and the intercellular spaces between
them. They resemble a large number of thin hollow balls thrown together
and slightly pressed out of shape where they come in contact.

2. Examine a small piece of algae (preferably Spirogyra) under
the microscope. Note the size and form of the cells and the chromato-
phore.

FIG. 79. — Trichomes or plant hair
from leaf surface.

104 ANATOMY OF STEMS, ROOTS, AND LEAVES

3. Examine a small piece of alga> that has been kept in alcohol and
stained with eosin. Note the protoplasm and nucleus.

4. Examine a very thin section of potato under the microscope and
note the starch grains. Stain with dilute iodine and examine again.

5. Cut a very thin cross-section from the pith of corn stalk. Note
the parenchyma cells and the fibro-vascular bundles. Study out the parts
as indicated in the figures.

6. Geranium Stem. — Cut a very thin cross-section of the stem of a
geranium. Note the parts as indicated in Figs. 67, 70.

71. Woody Stem. — Cut a very thin cross-section of a twig from a
tree. Note the, parts as indicated in Fig. 74.

8. Many Forms of Cells. — Make longitudinal sections of all of the
above stems and find as many kinds of cells as possible.

9. Leaf Structure.— Hold a bit of a leaf between two pieces of pith
and cut very thin cross-sections. Examine under the miscroscope and note
the parts as indicated in Fig. 77.

10. Peel small fragments of epidermis from both lower and upper
surfaces of a leaf and examine under the microscope.

11. Root Structure. — Hold a young root from corn or l>ean between
two pieces of pith and cut very thin cross-sivl ions. Examine under the
microscope and note the parts as indicated in Figs. 75 and 70.

QUESTIONS

1. What do you understand by fibro-vascular bundles?

2. How are they arranged in the plant?

3. What do you understand by plant cell?

4. What are some of the different kinds of plant cells ?

5. What do you understand by protoplasm?
C. What else do you find in plant cells?

7. What is the cambium? Where is it located?

8. Explain the difl'erence between mono- and' dicotyledonous steins.

9. What is meant by phloem and xylem? Where are they located?

10. What are the medullary rays?

11. What are annular rays?

12. What is meant by epidermis?

13. In what parts of the plant do you find chlorophyll?

14. What is meant by mesophyll ?

15. What and where are the trie-homes?

CHAPTER IX
CHEMICAL COMPOSITION OF THE PLANT

WE HAVE examined both young and mature plants and have
studied the various organs of which they are composed. We
have also learned something of the structure of these plant
organs. Let us learn something of their chemical composition ;
something about the qualities that make them useful or unfit
for food and other purposes. Of course, we have reason to believe
that the different parts of the plant are unlike in chemical com-
position, for we know that they are different in structure and
texture, and that we use them for radically different purposes.

Water, which is so essential for plant growth (Chapter I)
is the most abundant and one of 'the most important compounds
in the plant. We know that fruits and vegetables are juicy and
we have seen the bleeding of trees when pruned too late in the
season, and, therefore, it is not necessary to demonstrate that
plants contain water. The quantity of water in the different
parts of the plant varies from the very large amounts in juicy
fruits to the very small amounts in dry grains. The following
table shows some of the extremes :

Percentage of water content
Plant by weight

Cucumber (fruit) 96

v Cabbage ( leaves ) . 90

Beets, red (roots) 88.5

Apples (fruit) 83.2

Potato (Irish) 78.9

Potato (sweet) 71.1

Corn (green fodder) 79.8

Corn (dry grain) 10.9

We also know that plants contain carbon, for we have seen
the charcoal which is formed as a result of burning a piece of

105

106 CHEMICAL COMPOSITION OF THE PLANT

wood. But when the fragment of charcoal is burned we have a
few ashes remaining. The chemist tells us that this ash contains
small quantities of phosphorus, potassium, calcium, mag-
nesium, sulphur, sodium, chlorine, manganese, aluminum, etc.
The water, carbon and nitrogen which we know make up a con-
siderable part of the plant have been carried off as vapor and
gas during the process of burning.

The water is composed of two gaseous elements, hydrogen
and oxygen. When wood burns or decays, the carbon (C) unites
with the oxygen (O) of the air forming a gaseous compound
known as carbon dioxide (CO2), which is available for new
plant growth. (Page 115.)

Starch. — We also know that plants contain starch which is
composed of three elements, carbon, hydrogen and oxygen, com-
bined as C6H10O5. Starch is one of the most abundant plant
substances and is one of the valuable plant products of com-
merce. It constitutes a considerable part of the dry substance
of seeds, green fruits, fleshy roots, tubers, bulbs, fleshy leaves,
etc., in which it can be readily detected by very simple experi-
ments. Starch is one of the important food substances for both
man and beast. Potatoes, sweet potatoes and other tubers and
fleshy roots contain large quantities of starch. Grains, peas,
beans and other seeds contain an abundance of starch. The
starch not only makes these plants valuable for food but also for
other purposes. Tapioca, some forms of paste and other ar-
ticles of commerce are made from starch. The following table
shows the relative amount of starch found in some common food
plants, as estimated in percentage of dry weight.

Plant products Percentage of starch

Seeds of navy beans 45

Seeds of peas 52

Seeds of corn 60

Seeds of wheat 68

Seeds of rice 68

Tubers of potatoes 80

FATS 107

The starch is found in definite bodies known as starch
grains within the cells of the plant, and can be seen readily
with the aid of the microscope. The size and form of the starch
grains vary in different plants.

Sugar is another plant product very similar to starch, but
it occurs in a much greater variety of forms. The most com-
mon type is the cane sugar (C(5H12OC) which is abundant in
many plants and forms a valuable food product. It is found
in the cell-sap and can be readily detected by simple experiments.
It is especially abundant in sugar beets, sugar maple, sugar
cane and ripened fruits. We all recognize the value of sugar
for food and as an article of commerce. One of the great prob-
lems of the plant breeders is to increase the percentage of
sugar in the sugar-producing plants. (Chapter XV.) The
amount of sugar in the sugar beet has been increased from 7
to 15 per cent by scientific methods of plant breeding.

Carbohydrates. — The cell-walls are composed of cellulose
which is made up of the same elements as starch and sugar, but
they are also infiltrated with various other substances. Cellu-
lose is the most important plant compound in the manufacture
of paper. Cellulose is also used extensively in the manufacture
of the many celluloid articles on the market, and it is also used
in the making of gun cotton and other high explosives. Many
plants also produce gums which are composed of these same
elements and some of which are important articles of com-
merce. The starch, sugar, gums, and cellulose are known as
carbohydrates ; that is, their hydrogen and oxygen is always in
the ratio of two to one.

Fats. — Many plants also contain fats and oils which are
composed of the same elements as the carbohydrates (i.e., hydro-
gen and oxygen), but the hydrogen and oxygen ratio is never
two to one. The fats and oils are known as hydrocarbons and
are usually most abundant in the seeds, especially nuts. They

108 CHEMICAL COMPOSITION OF THE PLANT

are used for food, medicine, soap making and many other pur-
poses and are among the most important articles of commerce.

Proteins. — Plants also contain a third group of foods, known
as proteins or proteid foods which are composed of carbon,
hydrogen, oxygen and nitrogen, and are among our most im-
portant food substances. They are especially abundant in seeds
and the food value of many plants over others depends almost
entirely on their percentage of protein. They may be associated
with the carbohydrates, but in some cases are borne in separate
cells. The great value of clover, cowpeas, soybeans and related
plants for stock feed, and of beans and peas as food for man
depends primarily on their protein content.

Plants contain many other compounds, some of which are
referred to as waste products. Among the most important of
these compounds are the following:

(a) The essential (or volatile) oils, which are entirely
different from the true oils previously referred to. They may
occur in any part of the plant, but are especially abundant in
the foliage and flowers. Most of the odors of plants are due to
these essential oils, many of which are extracted and used in
the manufacture of medicines, perfumes, soap and other articles
of commerce.

(b) Gums and resins of various kinds are familiar articles
of commerce. Among the most important .a re turpentine, resin,
balsams, gum-camphor, gum-arabic and guin-tragacanth;

(c) Organic acids are very numerous and are especially
abundant in certain fruits. Among the most common organic
acids of commerce are oxalic, malic, tartaric and citric acids.

(d) Tannins are abundant and are founcf in the great ma-
jority of the higher plants. They are used for the making of
hides into leather, in medicines and for other purposes.

(e) Alkaloids are abundant plant products from which we
obtain many valuable medicines and some of our most danger-

EXERCISES, COMPOSITION OF PLANT TISSUES 109

ous poisons. Among the most familiar are quinine, strychnine,
cocaine and morphine. In this connection, it is well to remem-
ber that about 90 per cent of our medicines are of plant origin
and that much of the early work in botany was for the discovery
of new drug plants with which to relieve the sufferings of
mankind.

EXERCISES SHOWING THE COMPOSITION OF PLANT TISSUES

1. Ash in Leaves. — Weigh a bunch of green cabbage or lettuce leaves.
Dry them in an oven. Weigh again and compute percentage of water.
Burn the leaves, weigh and compute the percentage of ash.

2. Water in Seeds. — Put a few seeds in a test tube, plug with cotton
and heat gently so as not to scorch the seeds. Hold the tube as nearly
horizontal as possible while beating. Do you see signs of water on the
glass?

3. Ash in Wood. — Put a piece of wood in a test tube and heat until
a piece of charcoal (carbon) is formed. Burn the charcoal to ashes.
Shake the ashes in water. Do they dissolve?

4. Tests for Starch and Sugar. — Put a little commercial starch and
a little sugar in separate test tubes of water, and shake. Do they both dis-
solve? Add a few drops of iodine to the starch and note the change in
color. This is the test for starch. Add a small amountl of Fehling's fluid,
a few drops at a time; a brick red color indicates the presence of sugar.
This test will not work with cane sugar unless the solution has been
boiled with dilute acid before adding the Fehling's fluid.

Fehling's solution can be made in the laboratory. It consists of two
solutions: (A) 36.G4 grams of pure powdered copper sulphate in 200 c.c.
of water. (B) 150 grams of Rochelle salt and 50 grams caustic soda in
500 c.c. of water.

Keep the two solutions separate and mix before using as follows:
2 parts of solution A.
5 parts of solution B.
10 part's of water.

5. Carbon in Sugar. — Put a little siugar in a test tube and heat
slowly until you have a black mass of carbon. Note what occurs during
the process and explain.

6. Testing Seeds and Fruits. — Test fruits, tubers, fleshy roots and
various other parts of plants by applying the starch and sugar tests to
freshly cut surfaces.

7. Examining Potatoes and Apples. — Cut very small, thin slices of

110 CHEMICAL COMPOSITION OF THE PLANT

potato and apple, mount in water and examine under the microscope. Add
a drop of iodine and note the effect.

8. Starch and Sugar after Germination. — Crush a few well ger-
minated seeds and put in two test tubes, fill about one-third full of water
and shake thoroughly. Boil and test for starch and sugar.

0. Changing Starch to Sugar. — Make a thin paste by boiling starch
in two test tubes of water. Allow to cool and add a small amount of
diastase or saliva to one. Keep in a warm place for 24 hours and tetft
both for sugar.

10. Oil in Seeds. — Crush a seed of castor bean or the kernel of some
nut between the fingers and thumb and note the oily character. Rub the
seed or nut on a piece of paper for the same purpose. Tie a small amount
of crushed seeds or other plant material in a bit} of cheese-cloth and soak
in a small dish of benzine; squeeze and remove and allow the benzine to
evaporate. Any oil that may be present will be found in the dish. Make
a list of vegetable oils of commercial importance and give their sources.

11. Protein in Flour. — Tie a small quantity of wheat flour in a bag
and knead under a stream of water. The sticky dough that remains is
largely protein. The starch was mostly washed out by the stream of
water.

12. Starch and Protein in Wheat. — Cut very thin slices of wheat
grain and examine under the microscope. Test for starch. Note that
the starch is in the center and in very thin-walled cells. Also note that
the proteid (aleurone) is in cells surrounding the starch. Also note the
hull is made up of the union of seed and ovary coats.

QUESTIONS

1. What compound is found in greatest amount in the plant? How
does it get into the plant? Is the total amount entering the plant retained?
If not, how does it pass out?

2. Explain the results obtained in the drying and burning of a
piece of wood. How do these elements and compounds become a part of
the wood?

3. What substances found in plants are useful as foods for animals?
In what parts of the plant are they found?

4. Give a list of commercial products of plants. Tell where found
and their uses.

5. Mentjon several plants or products rich in sugar.

6. From what plants is starch obtained commercially ?

7. What plants yield oil for commerce?

8. Mention several stock feeds rich in protein.

CHAPTER X
PLANT FOODS AND PLANT GROWTH

WE HAVE learned something about the important substances
found in plants, the starches, sugar, oils and proteids which make
them valuable for food. We have also learned that they con-
tain many other substances of more or less value in commerce.
We also know that many plants are grown for their fibre which
is used in many manufacturing industries, and we also use the
wood of many of the larger plants for many purposes. There-
fore, it is very evident that the plant kingdom produces a very
large number of useful plants. Let us now study the source of
these products and the processes by which they are formed.

Plants are unlike animals in that they use comparatively
simple compounds which are obtained from the soil and air and
transformed into true food materials for their own growth;
animals cannot use such simple compounds, but are compelled
to feed upon plants from which they secure already manufac-
tured or true foods, carbohydrates and proteids. Therefore, all
animal life is dependent either directly or indirectly on plant
life for its existence. The most important raw foods or com-
pounds that the plant gets from the earth are water (IT2O),
ammonia compounds (N1T3), sulphur, potassium and phos-
phorus, and various salts. The most important raw foods from
the air are carbonic acid gas or carbon dioxide (CO2) and very
small amounts of oxygen (O).

The energy with which these raw materials are transformed
into true foods comes from the sun in the form of heat and light.
Therefore, all life (both plant and animal) upon the earth is
dependent upon the sun for its existence. These raw foods are
transformed into true foods in the plant before they can be

111

112 PLANT FOODS AND PLANT GROWTH

used even for its own growth. However, the process by which
these simple compounds are transformed into true food materials
is imperfectly understood.

The amount of water in the soil varies with the amount of
rainfall and the texture of the soil. Coarse, sandy soils are poor
retainers of water as compared with the very tine clay soils.
Humus soils are excellent retainers of water, and this fact,
together with their richness in organic matter, makes them espe>-
cially good for agricultural purposes. It is very evident that
water acts as a solvent for the available soil substances and salts,
and is then taken up by the root-hairs. We have already
studied the root-hairs, and know that they are long, delicate cells
containing very active living protoplasm and a watery sub-
stance called cell-sap. This cell-sap is water containing salts,
acids and sugars. The root-hairs are evidently well filled and
somewhat distended. When cells are distended in this man-
ner they are said to be turgescent, or in a state of turgor. All
the active cells of a normal, growing plant are turgid and it is
this condition -which enables the soft parts of a plant to main-
tain their form and position. When cells lose their turgidity
the plants wilt.

Osmosis. — It is well known that when a substance dissolves
in a liquid it gradually diffuses until equally distributed.
If two solutions of equal density are separated by a plant or
animal membrane, the substances in solution will gradually dif-
fuse through the membrane until the two solutions are uniform
throughout. This is known as osmosis. (Fig. 80.) If two solu-
tions of unequal density are used there will be a flow from the
less dense to that of the greater density. When a plant is
growing under suitable conditions, the solution of greater dens-
ity is within the cells, especially the root-hairs ; and the solution
of lesser density surrounding them. The delicate root-hairs
ramify pmon<^ the extremely fine particles of soil. The soil,

OSMOSIS

113

water and the salts in solution pass into the cells of the root-
hairs and thence into the fibrous and tracheary tissues of the
root and thence through the same and probably other tissue of
the sap wood of the stem into the leaves where a considerable
part of it is given off by transpiration.. (Chapter VIII.) The
exact process by which water passes through a growing plant is

FIQ. 80. — Apparatus for demonstrating osmosis; thistle lube on left and egg on right.

not understood. Some of the acid within the root-hairs passes
out (exosmosis} and helps to dissolve the raw food compounds
in the soil, thus making them more available. If the character
of the soil is such that the water solution is of greater density
than the contents of the plant cells, the plant cannot live in it,
and if a plant should be set in such soil it would wilt very
quickly because of the loss of water which would pass out to
the soil.
8

114 PLANT FOODS AND PLANT GROWTH

Transfer of Water. — The process by which water is trans-
ferred from one part of the plant to another part is very imper-
fectly understood, hut we do know that it is transferred from
place to place and that it is carried upward in great quantities
against the tremendous force of gravity. We know that the
force necessary to lift this column of water to the top of very
tall trees must be enormous. We know also that this activity
is much greater at certain seasons of the year than at others.
We have all observed the bleeding of trees and vines when
primed too late in the spring, and know that considerable injury
may result from this practice.

Transpiration. — We have said that a considerable amount
of water is given off through the leaves by transpiration. This is
also true of the new shoots and such other green parts as the
plant may possess. The transpiration of water should not be
confused with evaporation. The latter process takes place from
the free surface of a body of water and is controlled by the
physical conditions of the air, but the former is controlled by
the structural character of the plant and the living protoplasm
of the plant cells. The water in the plant must pass through
the cell-walls into the intercellular spaces of the mesophyll to
which we have previously referred (Chapter IV), and then
passes out through the stomata by a process of diffusion.

Of course, when the air is dry the transpiration of water will
be much greater than when moist. The number of stomata
varies greatly in different species of plants, those growing in
dry places usually having fewer than those growing in wet places.
The amount of water which plants take from the soil and give
out through the lea.ves during a growing season is enormous,
but extremely variable when we compare plants living under
different conditions. It is estimated that some of our common
farm crops take up and give off an average of 300 pounds of
water in the production of one pound of dry material, although
in some plants it is three times this amount.

THE FORMATION OF CARBOHYDRATES 115

A Change of Gases. — The giving off of water through the
stomata is associated with a change of gas by transfusion be-
tween the air within the intercellular spaces of the leaf and the
air on the outside. Therefore, as the water passes outward
through the stomata$ the carbon dioxide (CO2) of the air passes
into the intercellular spaces, is absorbed by the protoplasm of
the mesophyll cells and immediately dissolved in the cell sap,
thus forming carbonic acid (CO2-f-H2O=CH2O3). The action
of the sunlight on the chlorophyll results in the breaking up of
this carbonic acid and the recombination of the elements with
the elements of water into other compounds. This delicate and
complicated process is very imperfectly understood, and the
first result that we can recognize with any degree of certainty
is glucose or grape sugar (C6H12O6).

Plants and Animals Help Each Other. — We know that the
process results in the liberation of free oxygen (6CO2 + 6H2O
— C6H12O6-|-12O) which is given out through the stomata and
is essential for the life of animals. Therefore, we see that ani-
mal and plant life are more or less inter-dependent, but it is
very evident that animals are more dependent upon plants than
plants are upon animals. Plants utilize the carbon dioxide
which is exhaled by the animals, but they could readily obtain
this supply from other sources. Animals utilize the oxygen
given off by plants, and are absolutely dependent upon plants
for their food supply.

The formation of carbohydrates, that is, starches and
sugars, from these crude materials (water and carbon dioxide)
by the action of sunlight on the chlorophyll is known as photo-
synthesis and is the most wonderful and most mysterious process
in all nature. With this as a beginning, we have the basis for
the formation of innumerable other plant and animal products.
A small part of this organized food is used immediately for cell
formation and growth, but the greater part is stored for fu-
ture use.

116 PLANT FOODS AND PLANT GROWTH

Grape sugar which is formed in the green parts of plants
can be readily transformed into starch by the loss of one molecule
of water (C6H12O6 — H2O = C6H10O5). In some plants,
such as the sugar beet and sugar corn, the sugar is transferred
directly and stored as such without change. But in most plants
it is very quickly transformed into starch, which is reconverted
into sugar during the night and transferred to other parts.
Therefore, if the leaves are examined early in the afternoon they
will be found to' be very rich in starch as compared with their
condition before sunrise.

Other Organic Compounds Formed. — We know that search
and sugars are the most abundant food products of the plant;
that they are especially abundant in vegetables, fruits and seeds.
But we also know that there are other substances, such as hydro-
carbons (fats and oils) ; and the proteins, which contain nitro-
gen (and some sulphur and phosphorus). These are among the
most important food products, but we know very little about
their formation.

Mineral Substances. — Plants take a great many minerals
from the soil. The most important are phosphorus, potassium,
calcium, magnesium, sulphur, iron, sodium, chlorine, silicon,
manganese and aluminum. These elements go into solution in
the water of the soil and then pass into the root-hairs in the
manner already described. They may be found by making
a chemical analysis of the ash of the plant. They vary in pro-
portion in different species of plants, in plants at different ages
and in different parts of the same plant.

These minerals exist in varying quantities in the soil, but
their proportions may not be such as are needed by the crop,
or they may not be in such form as to be available as plant food.
Therefore, the progressive farmer, who is familiar with his
soil and with the needs of his crop, makes use of manures
and commercial fertilizers to overcome these deficiencies.

Nitrogen and Protein. — One other most important element

IMPORTANCE OF HUMUS

117

of plant food which we have not taken into consideration is
nitrogen, an element which is essential in the formation of
protoplasm and protein. The food value of many plants de-
pends upon their protein content. Nitrogen constitutes 78 per
cent of the atmosphere, and one might readily suppose that the
plant could secure its supply from
that source. But such is not the
case. The free nitrogen of the air
is not available for plant food. It
must be united with hydrogen to
form a nitrate before it can be uti-
lized by the growing plant. There
are several sources of nitrogen for
plant food.

(a) By the decay or disintegra-
tion of organic matter; i.e., dead
plants and animals and their waste
products. This is brought about by
millions of minute organisms of
decay known as bacteria.

(&) By certain soil bacteria
which live in the tubercles or no-
dules (Fig. 81) on the roots of legu-
minous plants and which enable the
plant to take the nitrogen from the air, and combine it with
hydrogen, thus forming ammonia compounds.

(c) By rainfall, which carries the nitrogen of the air to the
soil where it becomes available for these bacteria.

(d*) By electrical discharges (lightning) producing nitrous
and nitric acids which are carried to the earth by the rainfall.
The first and second of these are the most important.

Importance of Humus. — The first of these sources shows
the importance of utilizing animal manures and decaying plant
materials as fertilizers. These decayed animal and plant prod-

FIQ. 81. — Root of legume showing
tubercles.

118 PLANT FOODS AND PLANT GROWTH

nets are called humus, and we have long recognized that humus
is essential for plant growth. The second shows the importance
of the use of leguminous plants to increase the nitrogen content
of the soil and explains why clovers, alfalfa, cowpeas, soybeans,
vetch and similar plants are of such great importance as soil
improvers.

Circulation. — Knowing that plants take in water from the
soil, that it rises through the plants and is given off through the
foliage, naturally indicates that the plant possesses a circulatory
system similar to that of animals. Although the circulation, is
through definite parts of the plant tissues, it is not through a
definite set of tubes and does not have a propelling organ or
pump such as the heart of the animal. The water rises in the
wood (or xylem) part of the stem and carries the mineral
substances of the soil in solution. But this does not complete
the problem of circulation. Very little of the manufactured
plant food is stored in the parts in which it is formed but is
transferred to fruits, seeds, tubers, bulbs, roots and other parts
for storage. This transfer is primarily through the outer (or
phloem) part of the stem. We do not understand just how
this transfer is accomplished, but much of the food must undergo
modifications, must become soluble, before it can be moved.
The carbohydrate is probably moved while in the form of sugar
(glucose), and the fats and true soils as glycerine and fatty
acids, and the proteids in a form known as amides.

EXERCISES SHOWING PROCESSES IX PLAXT GROWTH

1. Osmosis Through a Bladder. — Tie a bit of bladder or sausage
casing or parchment over the large end of a thistle tube; partly fill the
tube with molasses and immerse the large end in water until the two
liquids are on a level. Make observations at intervals of one hour and
explain the phenomena.

2. Exosmosis and Endosmosis- — Peel some fleshy root such as car-
rot, turnip or beet and cut in slices about % x 1% inches and about l/s
inch in thickness. Put a few of them in distilled water and a few in a
salt or sugar solution. Examine after a few hours and explain. Now

EXERCISES SHOWING PROCESSES IN PLANT GROWTH 119

transfer them, putting those that were in the solution, in the distilled
water, and those that were in the water in the solution. Examine
after a few hours and explain.

3. Movement of Plant Fluids. — Cut * a stem of a Begonia two
or three inches from the surface of the soil, and place the severed part
in a glass of water that has been colored with some analine dye or red
ink. After twenty-four hours, remove and cut the stem at various points
and examine. Fasten a small glass tube on the stump by means of
adhesive tape, and keep the roots well watered. Note the rise of water
in the tube. Explain.

4. Transpiration. — Take a small actively growing plant and tie a
piece of sheet rubl>er over the pot allowing the plant to project through a
small opening; invert a. glass over the plant and note the moisture which
collect^ within the next few hours. Where did it come from? Cut a
bunch of fresh growing plants or a cabbage and weigh. Allow to wilt
and dry and then weigh again. Dry in an oven, but do not char, and
weigh again. Explain.

5. Plant Food. — Secure a quantity of coarse, clean sand, and fill two
flower pots or cans of equal size with equal quantities. Plant several grains
of corn of approximately the same size and character in each. Water
one from time to time with rain water or distilled water and the other
with soil solution. Soil solutions may be prepared, by filling a large pail
two-thirds full of rich soil or well rotted manure and then adding enough
water to make a thin slop. Stir, allow to settle and draw off the water.
Refill with water and allow to stand until needed again. In which pot
do the plants grow best? Why?

6. Moisture in Wood. — Weigh a piece of green wood. Heat until
thoroughly dry. Weigh again. What has it lost and how much?

7. Carbon in Wood.— Burn the wood until charcoal is formed. This
is almost pure carbon. Weigh again. What has been lost and how much?

8. Ash in Wood. — Burn the charcoal. What have you remaining
and how much?

9. Carbon in Sugar. — Put a little white sugar in a test tube and
heat. What happens? Explain.

10. Study of Oxygen. — Mix a teaspoonful of potassium chlorate
with about one-fourth the amount of finely powdered manganese dioxide.
Put the mixture in a large test tube or small flask. Close the container
with a stopper through which a small delivery tube passes. Fix the con-
tainer in a slanting position on an iron stand, and run the free end of
the delivery tube into a tray of water. Heat the mixture gently with gas
or alcohol flame. Fill several bottles with water; invert one over the
mouth of the delivery tube in such a manner that the water will be

* The stem should be held in the liquid during the cutting so that
the cut surface is not exposed to the air.

120 PLANT FOODS AND PLANT GROWTH

forced out by the gas. When all the water has been forced out, cover the
mouth of the bottle with a card and invert. Repeat until three or four
bottles are filled.

This gas is oxygen. Note its color. Thrust glowing pieces of char-
coal into the bottles and note the result. Explain.

11. Study of Carbon Dioxide. — Put some small fragments of marble
into a flask thoroughly closed with a cork through which has been passed
a delivery tube as in: Exercise 10, and a small funnel or thistle tube. Pour
dilute hydrochloric acid into the funnel until Nthe lower end is covered.
Collect the resulting gas (carbon dioxide) as in Exercise 10. Run a
little of the gas into lime water and note the result. Take a little fresh
lime water and blow into it through a straw or tube. Note the result.
Explain.

12. Burn a piece of charcoal in a bottle of pure oxygen. Remove
quickly, pour in lime water and shake. Note the result. Explain.

13. Study of Hydrogen. — Put a few fragments of zinc into the
same or a similar apparatus as uaed in Exercise 10. Add the dilute
hydrochloric acid but allow the gas to be given off for some minutes. Then
collect a bottle of the gas (hydrogen) and place upside down on a table.
Darken the room and thrust a burning match into the inverted bottle.
Note the result.

14. Study of Nitrogen. — Fasten a bit of candle to a cork and float
in a vessel of lime water. Light the candle and cover with a wide bottle
so placed that the edges are under water. When the candle goes out,
cover the mouth of the bottle with card-board or cork and reverse so as to
retain all the water that has risen in the bottle. Shake thoroughly, and
allow to stand .until the upper part is clear. What has been used by the
burning candle? What gas has been formed as indicated by the lime water
in the bottle? The gas remaining in the bottle is nitrogen.

QUESTIONS .

1. What are the three great groups of substances found in plants?

2. Of what elements are each of these food substances composed?

3. What are the sources of these elements?

4. What other elements are found in plants?

5. What relation does the texture of the soil bear to the water con-
tent?

6. What do you understand by humus?

7. What do you understand by turgor?

8. What do you understand by osmosis?

9. Why do plants wilt?

10. What do you understand by transpiration?

11. What do you understand by photosynthesis?

CHAPTER XI
THE GYMNOSPERMS

THUS far we have devoted our time to the study of the
higher plants, that is to the plants which produce flowers and
seeds. This great group of trees, shrubs and herbs presents by-
far the most conspicuous types of vegetation and includes our
most important agricultural crops. But we must now con-
sider the yyninosperms (for classification, see Chapter V), that
great group of seed-bearing plants which do not produce true
flowers. They are also called coniferous or cone-bearing plants
because of the cones which contain the seeds. The largest, most
important and best-known group is the order Pinacece which
are widely distributed throughout the world especially in the
northern hemisphere. They are the pines, spruces, firs, bal-
sams, larches, cypresses, cedars, hemlocks, arbor vitse and the
giant red oaks of our Pacific coast.

Structure of Stems. — The general character and gross struc-
ture of the stems and roots is somewhat similar to the angio-
sperms, but the leaves are modified until in most cases they are
described as needles. These needles may be compared to the
midrib of an ordinary leaf, but when cut in cross-section and
examined under the microscope they show a thick cuticle and
epidermis covering a few layers of sclerenchyma cells (Chapter
VIII), which in turn cover the chlorophyll bearing parenchyma
(Chapter VIII). The small size and peculiar structure of the
leaves make them especially well suited for withstanding either
dry or cold climates. Most coniferous trees shed their needles
gradually and, therefore, are in foliage the entire year. For
this reason they are known as evergreens and are especially suit-
able for ornamental plantings. Some few conifers such as the

121

122 THE GYMNOSPERMS

bald cypress and larch are deciduous, i.e., shed their entire
foliage each year and are bare during the winter season.

A cross-section of the stem will show the annular rings and
medullary rays the same as in dicotyledonous plants. Very thin
sections should be made and mounted in water for study under
the microscope. Each section is cut at right angles to the other
two as follows :

(a) The cross-section which will show the varying thick-
nesses of the cell-walls by which the annular, rings are produced,
the large thin-walled cells of the late summer growth. It will
also show the medullary rays and large resin ducts. (&) The
radial section which is cut longitudinally and on a plane passing
through the axis of the tree (i.e., quarter sawed) will show the
peculiar markings of the cells (trackeids}. By studying care-
fully made tangential sections which are also longitudinal but
at right angles to the radial section we can get some idea of these
peculiar markings.

The cones are of two kinds, staminate and pistillate. They
correspond to bunches of staminate and pistillate flowers. We
are most familiar with the pistillate (or carpellate) (Fig. 82, c)
cones and will give them first consideration. They become the
mature cones which we find hanging on the trees. These cones
are made up of scales, corresponding to needles or leaves, but
instead of being arranged in circles as in the case of a true
flower, they are arranged in spirals. You will also note that
when they spread apart they each bear two winged seeds.

But let us examine an immature cone such as we will find
early in the spring. (Fig. 82, c.) Each cone is small and the
scales naturally spread so as to expose two ovules (macrosporan-
gici). (Fig. 82, d.} This is quite different from the true flower-
ing plants in which the ovules are always enclosed in an ovary.

Pollination. — In the spring we will also find clusters of
very small staminate cones. (Fig. 82, a.} Each scale of these

POLLINATION

123

small cones is a stamen (sporophyll) bearing sacs (microspor-
anyia) tilled with great quantities of yellow pollen grains
(microspores) which fall in showers and are scattered by the
wind. These pollen grains are provided with flattened exten-
sions of the cell-wall, forming wings for their ready support in
the air.

FIG. 82. — a, cluster of starninate cones; b, pollen grain; c, pistillate cone; d, scale from
pistillate cone showing two ovules.

Some of the pollen is caught in the pistillate cones and falls
upon the exposed ovules. The scales close and the pollen grain
produces a delicate tube which penetrates the ovule, reaches the
egg and results in fertilization similar to that described for the
angiosperm. (Chapter VI.) This process cannot be followed
except by the study of carefully prepared slides with the aid
of the microscope. However, the interval of time between pol-
lination and the maturity of the seed is much greater than in
most angiosperms. The seed cone enlarges rapidly, but the
seeds are not mature until late in the summer of the following
year.

124 THE GYMNOSPERMS

Cycadales. — Another very interesting group of the (jymno-
sperms is the order Cycadales which is mostly tropical in habit.
In this order we find the Cycas revoluta which is frequently
grown in greenhouses. Its chief point of interest botanically is
in the fact that it possesses many characters in common with the
ferns and forms a sort of connecting link between the Gymno-
sperms and the Pteridophytes or ferns.

We all readily recognize the great value of the Gymno-
s perms. Many of them are among our most important forest
trees from which we derive enormous amounts of lumber for
building purposes and cabinet making. They also furnish our
commercial supply of turpentine, resin and balsams. The
cypress is used extensively for telegraph and telephone poles.
The use of evergreens for ornamental plants is directly con-
nected with the nursery business and landscape gardening and
involves very large expenditures of money.

EXERCISES WITH (JY^IXOSPERMS

1. Examine a number of evergreen trees and note their straight
shaft, mode of branching and general form.

2. Growth and Leaves of Pines.— Examine a pine tree and note
the long shoots that are produced each year. Also note the short shoot*
composed of clusters of needles. Count the needles in the clusters in tlu>
different kinds of pines that may be available. Is the number constant
for each species?

3. Examine a needle carefully; make cross-sections by cutting the
needle in a bit of pith and examine under the microscope. Note the thick
cuticle, the thick epidermis, the sclerenchyma and the chlorophyll-bearing
parenchyma.

4. Twigs of Cone-bearing Trees. — Cut across radial and tangential
sections of a branch from a cone-bearing tree and examine under the
compound microscope and note the points referred to in the text.

5. Cone Flowers. — Examine young staminate and pistillate cones
and note the points, referred to in the text. (This material can be col-
lected in the spring and preserved in alcohol or formalin.)

6. Pollen Grains. — Examine some of the pollen grains under the
compound microscope.

QUESTIONS 125

7. Seeds and Cone. — Examine a mature cone. Remove some of the
seeds and examine.

8. Study Seedlings. — Plant some of the seeds and note characters of
the seedlings.

9. Greenhouse Gymnosperms. — Visit the greenhouse and ask to
see a Cycas revoluta.

QUESTIONS

1. What do you understand by Gymnosperms?

2. Compare the leaf of a\ Gymnosperm with that of an Angiospenn.

3. What do you understand by deciduous?

4. Are any of the Gymnosperms deciduous?

5. Have you seen any of these in the winter condition?

6. Name the parts of the staminate and pistillate cones of a con-
iferous tree.

7. Compare these parts with the corresponding parts of a true llow-
eriug plant.

CHAPTER XII
ECOLOGICAL RELATIONS

THE growth of the plant . is influenced by many factors,
among the most important of which are water, soil, temperature
and light. The combination of these four factors may not be
such as to give the maximum in growth and productiveness ;
for while one or two of these factors may be in the correct pro-
portion for the best growth of the plant, the other two may be
in proportion unsuited for the greatest possible development.
The plant is also influenced by animals, wind currents, and
many other factors too numerous for discussion at this time.
When a factor is such as to kill or prevent the growth of the
plants of any particular species, it becomes a limiting factor
in the spread of the species regardless of the character of the
other factors. Lack of water may prevent the spread of a
species into a territory when all other factors may be satisfac-
tory. This is, well illustrated by the great desert regions of the
world which produce abundant vegetation when subjected to
irrigation. Any species of plants will extend its range as fast
as the controlling factors will permit, and will reach its max-
imum development where the combination; of the factors is best
suited to its existence and its minimum where it is most
unsuitable.

Water. — We have already learned that plants cannot live
without water and that it is the most abundant compound in most
plants and also one of the most important. It passes into the
plant by means of the root-hairs and passes out of the plant by
transpiration, mostly through the leaves. We have also learned
that many plants are composed almost entirely of water. How-
ever, plants differ in the amount of water required for their
126

THE HYDROPHYTE SOCIETIES

127

existence. Some plants float in the water and have no direct
connection with the soil ; others are rooted to the soil but float
in the water (water lilies). Some are rooted in the mud but
extend fan above the water (cat-tails) ; some grow in wet soil;
still others grow in dry soil and are easily killed by too much

FIG. 83. — Zone formation of vegetation dependent upon depth of water.

water. These facts enable us to group plants into societies de-
pendent upon their water requirements. (Figs. 83 and 84.)

The Hydrophyte societies are made up of those plants which
live in the water or in very wet swampy soils. Ponds and lakes
in which the water varies in depth frequently show many of
these societies to an advantage ; the floating plants in the moder-
ately deep water, the cat-tails near the margin and the willows
on the margin. Rice is one of the few hydrophytes which is of
great agricultural importance.

128

ECOLOGICAL RELATIONS

The Mesophyte societies are those made up of plants which
require a fair amount of rainfall. The forest and prairie
plants and most of our agricultural plants are mesophytes.

The Xerophyte societies require very little water and in-
clude the desert plants.

Via. 84. — Zone formation of vegetation dependent upon depth of water.

In addition to these societies we have also

The Halophytes or those plants which grow in salt water
and salt marshes, and

The Tropophytes which are mesophytic in habit for a part
of the year and xerophytic in habit for the remainder.

Soil. — The majority of plants with which we are familiar
grow in the soil, but we must not forget that a great number of

NITROGEN OBTAINED FROM THE AIR 129

species of plants live in the water, while others live either para-
sitically or saprophytically on plants and animals. The soil in
which plants live must have a suitable texture and must fur-
nish certain elements which constitute most of the crude food
materials of the plants. Since our agricultural crop plants are
dependent upon the soil and since the animals are dependent
upon the plants, it is evident that all animal life is dependent
upon the soil. If we are to understand plant growth we must
know something about the soil in which the plants grow.

The various soils are made up of numerous small particles
of disintegrated rocks of various kinds, in which is usually
mixed more or less decaying or decayed organic materials. The
disintegration of the rocks is due to the freezing of the water
which penetrates the minute crevices, to the grinding action of
moving masses of ice, to the mechanical and solvent action of
water and to many other minor influences. Soils are designated
as gravel, sand, sandy loam, loam, clay, etc., dependent upon the
coarseness or the fineness of the particles of which they are com-
posed. The variation in the texture of the soil results in varia-
tion in its power to retain water.

The most important elements in the soil which either serve
as food or influence the growth of plants are phosphorus, potas-
sium, calcium, magnesium, sulfur, iron, sodium, chlorine, sili-
con, manganese, aluminum and nitrogen. All of these except the
last can be found in the ash of the plant and of course must have
been taken from the soil by the plant. These elements may be
in the soil in proportions too great or too small for the needs of
certain plants and satisfactory for others, or may be present,
but in such a form as to be unavailable for the plant. Since the
different species of plants are unlike in their requirements we
find them more or less in groups dependent to some extent upon
the character of the soil in which they grow.

Nitrogen Obtained from the Air. — Probably the most im-

130 ECOLOGICAL RELATIONS

portaiit of all the elements is the nitrogen which is essential for
all plants and animals. Nitrogen is very abundant in the air,
but the plants cannot make use of it in this free form. However,
the air penetrates the soil and its nitrogen is seized upon by
certain bacteria and fungi and fixed in the form of nitrates which
can be used by the plants. (Chapter X.) This gives us one
good reason for keeping the soil in which we are growing plants
in loose condition. Nitrogen is also carried down and into the
soil by rainfall. The bacteria found in the tubercles of the
leguminous plants are the most important organisms in this
work. Nitrogen is also obtained from decaying organic mater-
ials and this is one reason that humus is so important in agri-
cultural lands.

Use of Fertilizers. — If the soil does not contain these food
elements in the proper proportions or if any of them are unavail-
able, the farmer endeavors to overcome its deficiencies by the
application of fertilizers, such as stable manure, bone meal, ni-
trate of soda, rock phosphate, potash, lime, etc., or by the grow-
ing of the leguminous plants or by both. In order to do this to
the best advantage it is important that he understand the crop
plants to be grown and their food requirements. The elements
most likely to be lacking in farm soils are nitrogen (N), phos-
phorus (P), potash (K), and sometimes calcium (Ca).

Temperature. — This is another factor of plant growth which
we very readily recognize and we know that certain fruits such
as oranges and bananas grow only in tropical and subtropical
countries, and that many other plants are limited in their
range by the temperature. In traveling across the country we
easily see that forest and prairie sections can be readily divided
into smaller areas, such as the pine forest, oak forest, beech
forest, etc. We also recognize great belts or areas of agricultural
crops, such as the corn belt, cotton belt, wheat belt,, peach belt,
etc. On the boundaries of these belts we frequently find these

PLANT GEOGRAPHY 131

crops grown with considerable difficulty owing to droughts, frosts
and other factors.

Light. — This is also an important factor which is very
generally recognized. Our attention has been called to the
fact that plants turn to the light and that their foliage is ad-
justed to receive the light to the best advantage. (Chapter IV.)
But a little careful observation will show us that while some
plants thrive best in the direct rays of the sun others are always
found growing in the shady places. It is now well known that
some of our agricultural crops thrive much better in the shade
than in the open. Coffee is very generally grown in the shade
of larger trees and many plants are grown in an artificial shade
produced by slat coverings or by large cheesecloth tents.

These and many other factors of nature which influence the
spread of plants have given rise to that phase of botany known
as Plant Geography.

PLANT GEOGRAPHY

Plant geography is so closely associated with Ecology that
it is practically impossible to separate the two subjects by well-
defined boundaries. In our early study of geography we learned
that the earth was divided into five zones: Arctic, North Tem-
perate, Torrid, South Temperate and Antarctic, and we soon
learned to associate these zones with cold, temperate and hot
climates. But a little later we learned that countries in the
same parallels of latitudes did not necessarily have the same
temperature; mountainous regions in the torrid zone might
be cold as Iceland ; the Gulf current makes England much
warmer than points on our Atlantic coast which are much farther
south. It is very evident that elevations, mountains and water
barriers and the ocean currents exert very pronounced influences
on the temperature of a country and its plant growth.

132 ECOLOGICAL RELATIONS

A little later we learned that rainfall was fully as important
as a climatic factor as temperature and that it had fully as
much influence on the character of the vegetation. Probably the
greatest rainfall in the United States is over a small area of
Gulf coast extending from western Florida to a short distance
west of New Orleans, a section of the country well adapted to
growing rice and sugar cane. The rainfall of most of the
southern states is somewhat higher than for the states north of
the Ohio River, but cotton has reached its northern boundary far
south of the river. The rainfall of the Rocky Mountain Plateau
is lower than for any other part of the United States, giving
us a great area of country frequently referred to as the American
desert.

EXERCISES ON PLANT RELATIONS TO SURROUNDINGS

1. Moisture and Germination. — -Fill two small flower pots with
soil of the same kind, put into an oven until thoroughly dry, allow to
cool, plant seeds in both, add a definite amount of water to one from time
to time, keep the other dry, and keep both in a warm, well-lighted place.
Note the germination and growth.

2. Growth in Different Soils. — Fill several small flower pots with
different kinds of soils and sand, plant with seeds of the same kind, give
the same amount of water to each at definite intervals, keep in a warm,
well-lighted place. Note time of germination and rate of growth.

3. Influence of Sand on Rate of Growth.— Take a supply of rich,
loamy soil and a supply of clean sand, fill one flower pot with the soil,
a second with three parts soil plus one part sand, a third with two parts
soil and two parts sand, a fourth with one part soil plus three parts
sand and a fifth with pure sand. Plant the same kind of seeds in all,
give the same amount of water from time to time, and keep in a warm,
well-lighted place. Note the time of germination and rate of growth.

4. Temperature Affects Growth. — Fill two pots with the same kind
of good, rich soil and plant with same kind of seeds. Give the same
amount of water and keep each in a well-lighted place, but keep one in
a warm place (70 degrees F. or more) and the other in a cold place
(about 40 degrees F. or less). Note the rate of growth.

5. Effect of Light on Germination and Growth.— Fill two flower
pots with the same kind of good, rich soil, plant with the same kind of

QUESTIONS 133

seeds, give the same amount of water from time to time, keep in a warm
room, but keep one in the light and one in the dark ( closet or box ) . Note
the time of germination and rate of growth.

QUESTIONS

1. Name the four most important factors in plant growth.

2. Tell of the importance of water in plants.

3. What are the hydrophytes? Give examples.

4. What are the mesophytes? Give examples.

5. What are the xerophytes? Give examples.

6. What are the halophytes?

7. What are the tropophytes?

8. How may plants obtain the nitrogen found in air?

9. What elements are likely to be deficient in some soils?

10. How does temperature affect growth of plants?

11. Tell of the influence of light on plant growth.

12. Make a list of plants that thrive in partial'shade.

13. Make a list of common food plants and tell in what part of the
United States or of the world they are grown.

14. Same for common fibre plants. Why are they not grown over
wider ranges of country?

15. What are some of the geographic influences governing the plant
life of a region?

CHAPTER XIII
FORESTRY

THE study of forestry is a branch of botany that has attracted
a great deal of attention in recent years. When America was
explored and settled by white men, millions of acres were cov-
ered with virgin forest. The land was more valuable for culti-
vation than the forest was for any use that the settlers could
make of it. Therefore, enormous quantities of these wonder-
ful forests were cut and burned in the course of settlement.
But with the increasing population and decreasing forests, lum-
ber and wood became more and more valuable, until the United
States Government found it necessary to set aside large areas
of land as forest reserves. These conditions naturally led to the
study of forestry, a subject which involves the planting and
care of forests and proper protection and economic handling of
our natural forest products and the planting and care of shade
trees. (Fig. 85.) Many woodland areas have been denuded
which are of little or no value for other crops. (Fig. 86. ) The
United States Government and the various state governments
employ a large number of professional foresters for this work,
and many cities employ foresters to attend to the planting and
care of shade trees. Forestry is now recognized as one of the
most important studies in our large institutions of learning.
The principles of forestry are also practiced on many individual
farms throughout the land.

Although we cannot take a course of forestry in connection
with this brief course in botany, we can learn something of the
life of the individual trees of which the forest is composed and
some general principles of tree growth.
134

TREE CHARACTERISTICS

135

Tree Characteristics. — Trees are not only the largest plants,
but they are extremely complex and highly developed. How-
ever, each tree must arise from a single cell, in exactly the same
manner as any other plant, and is subject to exactly the same
laws of plant growth as any other plant. A tree is a woody

FIG. 85. — Modern forestry methods provide for perpetual crops of lumber and other
forest products. Forest beetles are held in check by burning the twigs after each harvest.
(U. S. D. A.)

plant with a single stem or trunk which may be straight with
many side branches or the trunk may divide into subdivisions.
It has a well-developed root system which gives it firmness and
by which it secures water and mineral foods. It has leaves of
size, shape and arrangement peculiar to its species. The flowers
of some trees are large and showy while those of others are so
small and inconspicuous that many people never see them and

136

FORESTRY

believe that certain species of trees never produce flowers. The
fruits are of various kinds and will repay you for careful study.
Trees have definite forms which are characteristic of their
species ; some trees are low with round dense heads, as the Nor-
way maples, others are tall and open as the elm and plane-tree ;
some have a single straight shaft as the pine and hickory, while
in others the main trunk branches in such a manner as to lose
its identity in several subordinate branches,

Fio. 86. — Denuded of forest growth by ruthless cutting and fires. A barren rocky waste
is left, unsuited to other agricultural crops. (U. S. D. A.)

Tree Foods. — The tree uses the same kind of food and
secures it in the same manner as any other plant (Chapter X),
and the amount of energy required in securing the raw food,
transferring it throughout the plant, and making it into ma-
terial of its own is far greater than we can appreciate. Wood is
composed primarily of carbon, oxygen and hydrogen. When
absolutely dry about one-half its weight is carbon. We have
already studied the processes and results obtained in burning
wood. (Chapter IX.)

TREES PRODUCE GREAT NUMBERS OF SEEDS 137

Tree Growths. — We have already learned something of
growth (Chapter X) and know the part played by the cam-
bium. When we think of the growing tree, we must think of
the thin cambium in not only the trunk but in every branch and
twig, and in every root and rootlet. (Chapter VIII.) When an
annular ring is once formed, its position in the tree is never
changed, but new annular rings will be formed, each outside
of the preceding one. In most trees the inner wood becomes
darker and harder with age and is known as the heart-wood,
while the outer which is softer and lighter in color is known
as the sap-wood. The passage of water through the heart-wood
is checked, but it continues to pass through the sap-wood during
the life of the tree. As the tree grows, the amount of heart-
wood increases by continual additions from the cambium. Tis-
sues of different woods have peculiar characters by which
students can readily recognize them.

Conditions of Growth. — Different species of trees require
different conditions for their growth. Some grow in cold
climates, others in warm climates; some in dry soils, and others
in swamps ; some require certain kinds of soil and light exposure.
.Natural forests are seldom of a single species but of several
species which live and grow under the same or similar condi-
tions. Under natural conditions there is a continual struggle
between the trees for food, water, and light, and many trees
die because other trees near them are more vigorous.

Trees produce great numbers of seeds, but very few of these
seeds produce trees. Many of them fall in places where the
soil, water or light requirements are unsuited to their existence,
or are destroyed by man or some of the lower animals. How-
ever, some of them grow where they fall and some of them are
carried for long distances, grow and may be the beginning of a
new forest area. Some young trees are more vigorous than^
others of the same kind, grow faster, overtop them and shut

138 FORESTRY

oil' the light and eventually starve them to death. A few are
able to^grow beneath the shade of others. Sometimes a forest
is so dense that it is difficult for young trees of the same species
as the forest to get a start, but other trees of a different species
and with different light requirements may become established.

Forest Enemies. — The forest has many enemies; the most
destructive is man who may lumber it with great waste, or use
it for grazing with great losses to the young growth, or care-
lessly set fires by which large areas are destroyed.

Insects, fungi, wind storms and snow storms also take heavy
toll from these natural resources.

EXERCISES ON FORESTRY

1. Learn the names of as many trees as possible on your street, in
your town, in the park or in a near-by forest tract.

2. Collect flowers, seeds and leaves of as many trees as possible.

3. Forms of Trees. — Make a diagram showing the peculiar branch-
ing and form of the common trees.

4. Tree Differences. — Make studies in the woods or elsewhere and
report on what kinds of trees in your vicinity are the tallest and what
kinds are the shortest, what ones make the densest shade, what ones en-
dure shade, what are rapid growers and what are slow growers ?

5. Study blocks of different kinds of wood and learn to recognize
them. Carpenters and other wood workers can help you in this study.

6. Close and Open Plantings- — Compare the shapes of trees of any
species in dense plantings with the same in open places. Explain.

QUESTIONS

1. What uses, are made of the lumber trees in your community?

2. What fruit - producing trees are found in the forests of your
community?

3. What nut-producing trees are found in the forests of your com-
munity?

CHAPTER XIV
PLANT DISEASES

PLANTS are subject to diseases which are similar in cause
and character to those of the animal, except that the majority of
animal diseases are caused by bacteria, while the majority of
plant diseases are caused by fungi.

A healthy plant is one in which all the parts are perform-
ing their regular functions ; a plant which is growing and pro-
ducing fruit in the regular manner. A disease is any condition
which interferes with the regular functions of the plant or
causes its death.

Anything that interferes with the taking of food materials of
anv kind, with photosynthesis, with the movements of plant
fluids, with transpiration, with reproduction or with any other
function of the plant is the cause of disease. The disease itself
is frequently designated by the name of the causal organism.

Two Groups of Diseases. — Diseases may be conveniently
grouped into organic and environmental :

Organic (caused by organisms)

Fungi Flowering plants Mites

Bacteria Insects Nematodes

Slime moulds

Environmental (caused by surrounding influences)
Soil Temperature Smoke

Moisture Gas Chemical (near factories)

Some Symptoms of Disease. — A disease may cause (a) dis-
coloration of the foliage or other parts of the plant ; (fc) new or
excessive growth ; (c) wilting; (d~) unnatural shedding of parts ;

139

140 PLANT DISEASES

»

(e) foliage spots; (/) perforation of foliage; (g) variegation
of foliage; (h) dying of leaves and twigs; (i) dwarfing or
atrophy of parts; (j) development of distorted or abnormal
growths, such as witches broom, galls, corky out-growths, etc. ;
(&) cankers; (Z) increase in size or modification of parts; (m)
curling of foliage and formation of rosettes; (n) hairy roots;
(o) exudation (gums, resins) ; (p) sun burns; (q) rot of fruits,
stems or roots.

The most noticeable diseases of plants are the rots of fruits
and stems which are usually caused by fungi and bacteria;
blights of the leaves, stems, flowers and fruits, which are also
caused by bacteria and fungi ; spots on leaves and fruits, which
are caused by both fungi and bacteria ; mildews, which are white
powdery fungous growths on leaves, twigs and fruits ; smuts and
rusts, which are fungous diseases of grains and other plants :
cankers, which may be due to fungi or other causes ; yellowings,
mosaics, and other discolorations, which may be due to any one
of many causes.

Wilts. — When the disease injures or destroys the root sys-
tem, the food and water supply from soil is reduced or cut off
and the plant , is either weakened or killed. Diseases of the
stem may have the same effect. Diseases of the foliage may
interfere with the absorption of carbon dioxide, the transpira-
tion of water and the photosynthesis of the plant.

The wilt diseases are usually due to fungi or bacteria which
live in the tracheary tissue of the fibro-vascular bundles and thus
interfere with the rise of water. These diseases are especially
injurious on herbaceous plants. The fact that the organisms live
within the plant make it impossible to treat by means of spray-
ing. Many of these wilt organisms live in the soil from year to
year and cannot be controlled except by crop rotation in which
it is necessary to use crops which are not subject to the disease
in question.

ROOT DISEASES

141

Root Diseases. — The crown gall (Fig. 87) is one of the very
common diseases of our fruit and other trees, roses, berries and
many other plants. It is caused by bacteria and appears as
abnormal growths on the roots and sometimes on the trunk and

FIG. 87 — Young tree with crown gall.

branches. In some cases it does but little harm, but in, other
cases it reduces the vitality of the plants and in extreme cases
causes death. The so-called hairy root of the apple, pear and
quince is caused by the same organism. The roots of these dis-

142

PLANT DISEASES

eased trees are covered with numerous small roots which are
usually associated with small galls. There is no known treat-
ment for this disease. Diseased trees should not be planted.

Galls or knots on the roots of plants may be due to other
causes. Among the most common are the galls on the roots of
apples and grapes which are caused by insects ; abnormal growths

FIG. 88. — Leaf spot disease of the pear.

on the roots of cabbage and related plants due to slime moulds ;
and knots on many plants due to minute worms (nematodes).
These and many other diseases of the root systems of plants in-
terfere with nutrition, dwarf the plants, reduce the crop and
frequently cause death.

The leaf diseases are mostly due to fungi which cause leaf
spots, leaf curls, blights, wilting, dying and droppings. One of

THE DISEASES OF THE FRUITS

143

the most noticeable of these diseases is the leaf curl of the peach
which is a fungous disease occurring in the spring and causing
the leaves to curl, turn yellow or pinkish and finally drop. In
severe cases practically all the leaves fall. The tree puts out
new foliage but drops the fruit. The disease when once estab-
lished persists from year to year. It can be controlled by
proper spraying.

The many leaf spot diseases (Fig. 88) reduce the amount
of leaf surface and thus reduce the amount of work which the

FIG. 89. — One of the apple rote, called "bitter rot."

plant is capable of doing. Therefore, severe leaf injury will
usually result in reduced vitality and reduced yield.

The diseases of the trunks of trees usually start with wounds
through which fungi gain entrance and cause heart rots. Spe-
cial care should be taken to protect street, shade and ornamental
trees against such injury. Tree wounds should be painted. The
filling of tree cavities is very satisfactory if well done.

The diseases of the fruits may appear as deformities, spot-
tings and rots. (Figs. 89 and 90.) The great majority of these
diseases are due to fungi. If you will examine the rots on a
number of apples of various kinds you will be able to throw

144

PLANT DISEASES

them into several groups. These diseases are especially severe
on fleshy fruits, such as apples, pears, peaches, plums, cherries,
tomatoes and many other plants. Many of these diseases can
be held in check by the proper spray treatment.

The diseases of the grain crops are very destructive and arc
the causes of heavy losses. The most conspicuous and most im-

Fia. 90. — One of the grape rota.

portant of these diseases are the rusts and srnuts (Fig. 91) which
are fungous growths in and on the plants. But there are many
other less prominent diseases of the grain plants which are
very destructive.

The study of plant diseases is a study in itself, a well-defined
branch of botany known as Plant Pathology. Most of the Agri-
cultural Experiment Stations, of which there is at least one in
each state, employ one or more plant pathologists who should be
consulted by the growers of crops.

THE STUDY OF PLANT DISEASES

145

FIG. 91. — Smut disease of oats. Healthy oats at right.

10

146 PLANT DISEASES

The control of plant diseases depends on the cause and char-
acter of the disease in question. In some cases the diseases are
carried on the seed and can be controlled by seed selection and
seed treatment ; some diseases are carried on nursery stock which
should be subjected to careful inspection for the elimination of
both diseases and insect pests; some diseases persist in the soil
and can be controlled by crop rotation and soil sterilization ; and
other diseases are controlled by spraying. Advice concerning
the character and treatment of diseases of plants ean be obtained
by writing directly to the Agricultural Experiment Station of
your state.

EXERCISES WITH PLANT DISEASES.

1. Collections Showing Diseases. — Examine a large number of
plants and make collections of diseased plants or parts of plants.

2. Inoculating Sound Apples. — Select a few sound apples, wash
in 5 per cent formaldehyde, then in sterilized water, and put them in
two or more closed glass dishes that have been treated in the same
manner. Set one or more aside for comparison. Puncture the apples in
the other with a sterilized needle or sharp pointed knife and insert a
minute fragment of the rotten part of another apple. Observe from day
to day and report results.

3. Examine apples kept in this manner for signs of formation of
spores. It nlay be necessary to keep them under observation for a month
or more.

4. Potato Diseases. — These experiments may be duplicated with
potatoes and other plants.

5. Make a list of diseases as a result of your own observation.

QUESTIONS

1. What do you understand by " plant diseases " ?

2. Enumerate the common symptoms of disease.

3. To what causes are these due?

4. Explain a common cause of wilt.

5. Describe the crown or root gall and its effect.

6. What are the chief forms of leaf diseases?

7. Name some common plant diseases which you know.

CHAPTER XV
PLANT BREEDING

THIS very important branch of botany which is attracting
so much attention at the present time and which is so often
referred to as a new subject, no doubt began with the earliest
dawn of civilization. Man selected and cultivated the plants
best suited to his purpose and the excellent qualities of many
of our economic plants are no doubt largely due to plant selec-
tions conducted by many generations who did not fully appre-
ciate just what they were doing. Plant breeding is based on three
laws of plant growth: variation, mutation and hybridization.
(Fig. 92.)

Variation is that law of nature which leads to differences
of more or less importance among plants of the same species.
Many thousands of plants of a species may appear to be the
same, but a close examination will show that no two are exactly
the same. By selecting seed from the individual plants which
possess the desired characters through a number of generations
it is frequently possible to emphasize these important charac-
ters. In the beginning of the sugar-beet industry in America,
the plants yielded about seven per cent sugar, but by careful
selection we now grow crops that yield double this amount.
Many of our most important varieties of fruits, vegetables and
grains are the results of more or less careful selection through
many generations.

Mutation is the law by which plants produce new species
with well-defined characters in a single generation. The per-
centage of new species is very small and yet of sufficient im-
portance to be of considerable value in agriculture. The study

147

148

PLANT BREEDING

of mutation is so new that we do not know how much we are
indebted to it for valuable economic plants. Some of our valu-
able plants which we have considered the results of selection
may really be the results of mutation.

Hybridization is the production of new varieties (hybrids)
by the cross fertilization of more or less closely related species.
This process no doubt occurs to some extent in nature, but man
has taken advantage of the possibilities of this method of secur-
ing new and valuable varieties and many men are now devoting
their time to this very important line of work. The method is

.Flo. 92. — In crossing different varieties of wheat the stamens are removed before they
she'd their pollen.- The pistils are impregnated with pollen brought by a soft brush from
another variety. The head is then covered with a paper bag and properly labeled. (U.S.D.A.)

not difficult but Requires care, time and patience. The pollen
can be readily collected in a watch glass or other small receptacle
and then applied to the stigmas of the flowers of the other plants
with a delicate camel's hair brush. The stamens of the opening
flowers should be removed, the pollen applied to the stigma and
the blossom then protected against accidental pollination from
other sources by covering with a paper bag. (Frontispiece.)
After a few days the bag can be removed and a tag fastened to
the shoot. In growing annual plants, the results of cross breed-
ing can be determined in a comparatively short time, but in the
cross-breeding perennials the time will be much longer unless

QUESTIONS 149

the seedlings are grafted into mature trees and brought to fruit
in a short time.

Selection. — Of course, it will be readily seen that in breed-
ing plants that will not hybridize or that do not produce seeds,
we must depend entirely on selection. In fact, selection was
the most important factor in plant improvement until recent
years and is now a method that can be used with great advan-
tage. Most farmers, fruit growers and gardeners can select their
best plants for seed purposes with great advantage to themselves.

EXERCISES IN POLLINATION

1. Removal of Stamens. — Select several flowers of tomato or other
plants just ready to open. Remove the stamen and cover with paper bags.
Examine in a week or ten days.

2. Artificial Pollinating. — Select another lot of flowers, remove the
stamens, touch the pistil with open stamens from another flower of the
same kind. Examine in a week or ten days.

3; Pollination in Greenhouses. — Visit some local greenhouse in
which the tomatoes, cucumbers and other vegetables are grown and see
how pollination is managed.

QUESTIONS

1. How are common plants pollinated?

2. What insects are important in pollinating plants?

3. Make a list of crops pollinated by insects.

4. Make a list of crops pollinated by wind.

CHAPTER XVI
WEEDS

IT HAS been said that a " weed is a plant growing in the
wrong place." There is much truth in this statement for many
well-known plants are pests or valuable products, depending
upon their location. The morning-glory is a beautiful orna-
mental plant in the home grounds but a pest in our cultivated
fields ; and mustard is a useful plant which becomes a pest when
the farm lands are thoroughly infested with it.

Many of our valuable cultivated crops were at one time wild
plants of the plains and forest which man -has found to be use-
ful and has learned to cultivate in an advantageous manner.
In fact, if we would go far enough back in, the history of man-
kind, back to the time when man was uncivilized, we should no
doubt find that all plants were at one time wild or unculti-
vated. With the progress of the human race man has learned
to cultivate and make use of many plants, but never in all his-
tory has man put forth so much effort to conquer nature and
utilize her products as at present. Every year sees plants that
we have in the past looked upon as weeds brought under culti-
vation and every year our government's traveling specialists
are collecting both cultivated and uncultivated plants from
abroad, many of them from the remote corners of the earth, and
sending them to America to be tested in order that their value
as farm crops can be determined.

Weed Defined. — A weed is not only a plant growing in the

wrong place, but it may be a plant which we have not yet learned

to make use of, or one which we have not learned to cultivate

profitably. However, for our purpose, a weed is a plant which

150

NEW WEEDS INTRODUCED 151

interferes with the growing of the crop in which we are inter-
ested. It may be a valuable crop if grown separately, but
we do not want it to interfere with the crop under cultivation.
The weed may be an excellent crop in one part of the world and
a pest in another part. The value of the plant depends upon
the use we can make of it and the ease and profit with which
it can be grown.

How Weeds are Injurious. — Weeds are injurious for many
reasons. (1) They take a certain amount of the food and
water which the crop plant should have for its growth. The
farmer cauiiot afford to have his crop plants weakened and the
amount of the harvest reduced by the weeds and he cannot
afford to buy fertilizers to feed useless plants. (2) Weeds may
prove injurious to the crop by shading and if too numerous
may completely choke out the crop plants. (3) The weeds
may harbor certain insects and fungi which attack the crops.
(4) Thistles, nettles, and other thorny or prickly plants may
interfere with using the growing crop for pasture or interfere
with tillage. (5) Weeds in the meadow reduce the feed value
of hay. ( 6 ) The presence of weed seeds in the harvest crop may
reduce its value. (Figs. 93 and 94.)

Weeds Sometimes Useful. — It is sometimes said that weeds
are useful, especially on unused lands, because they serve as a
cover and prevent the escape of nitrogen and can be plowed
under and thus used as a fertilizer. This is an old idea that has
come to us from the time when the land was rested by being
left uncultivated for a period of one or more years. But we
now know that in most cases it is much better to use a good
agricultural cover crop. Rye, certain clovers, vetches and other
plants are much more valuable than a miscellaneous lot of
weeds.

New Weeds Introduced. — When a new country is settled
and brought under cultivation we find certain native weeds,

152

WEEDS

Fio. 93. — Some common weeds. Left to right: Jimson, ragweed, lamb's quarter, joint-
weed, rough pigweed.

Fio. 94. — Some common grasses. Left to right: crabgrass, two barnyard grasses, two
of foxtail, panicum, fescue.

PREVENT INTRODUCTION

153

Fia. 95. — Crop seeds: 1, red clover; 2, alfalfa; 3, alsike clover; 4, sweet clover; 5, timothy;
6, red top; 7, Kentucky blue grass; 8, sweet vernal grass; 9, annual rye grass; 10, tall meadow
oat grass; 11, English rye grass; 12, orchard grass; 13, broom corn millet; 14, Hungarian
millet; 15, German millet.

154 WEEDS

some of which disappear rather rapidly, while others appear to
thrive as a result of cultivation, and are a continual source of
annoyance. But the number of different kinds of weeds will
increase. Man will naturally introduce the grains, grasses,
clovers and vegetables that he believes can be grown advantage-
ously and more or less weed seeds will be introduced with
them. Some of these weeds will grow for a single season and
die while others will persist from year to year. Other weed
seeds will be carried with nursery stock and on the feet and in
the hair of live stock, in bedding for live stock, in feeds and
in packing materials and in many other ways. In many local-
ities stable manure is shipped from the cities to the farms and
since the animals from which it is secured may have been fed
on imported feeds and bedded with materials brought from a
considerable distance we can easily understand how great quan-
tities of weed seeds can be introduced.

Fighting Weeds. — Every grower of farm crops must make
a continuous fight against weed pests. In doing this there are
two general methods to follow : ( 1 ) Prevent the introduction of
the weeds not already present on the farm, and (2) the destruc-
tion of those that are present.

Prevent Introduction. — The introduction of many weed
pests can be prevented by using nothing but clean seeds. Many
seeds, especially clover and grass seeds, frequently carry many
weed seeds. The examination of an ounce or more of such
seed will frequently reveal the presence of many seeds of trou-
blesome weeds. Unfortunately, the seeds of some plants are so
similar to certain clover and alfalfa seeds that they cannot
be detected by persons unfamiliar with their minor character-
istics. The Federal government and most of the State gov-
ernments employ seed analysts who make examination of sam-
ples which are sent to them. Home-grown seed should be just
as carefully examined as seeds that are purchased on the mar-
ket. (Figs. 95 and 96.)

FIG. 96. — Weed seeds: 1, Night-flowering catchfly (Silene erectifolid) ; 2, Sheep's sorrel
(Rumex acetoaella) ; 3, Curled dock (Rumex criapus); 4, Pennsylvania smartweed (Polygonum
pennsyhanicum) ; 5, Lamb's quarter (Chenopodium album); 6, Tumbling pigweed (Ama-
ranthus retroflexus) ; 7, Peppergrass (Lepidium virginicum) ; 8, Field cress (Lepidium eam-
pestre); 9, Yellow trefoil (Medicago lupulina); 10, Evening primrose (Onagra biennis); 11,
Wild carrot (Caucus carota); 12, Rugel's plantain (Plantago Rugelii); 13, Buckhorn (Plan-
tayo lanceolate) ; 14, Ox-eye daisy (Chrysanthemum leucanthemum) ; 15, Canada thistle (Cnicus
arvensis); 16, Bull thistle (Cnicus lanceolatus) ; 17, Yarrow (Achillea millefolium); 18, Dan-
delion (Taraxacum officinale); A, ventral side; B, dorsal side. 1, Caryophyllacese; 2-4,
Polygnacete; 5, Chenopodiacese; 6, Amaranthacese; 7-8, Cruciferae; 9, Leguminosffi; 10,
Anagracese; 11, Umbelliferse; 12-13, Plantaginaceee; 14-18, Composite.

156 WEEDS

Straw and similar material which has been used for pack-
ing and is likely to contain weed seeds should be burned or
rotted in compost to kill seeds. Stock bedding and feeds should
be produced on the farm whenever possible, instead of pur-
chased from a distance.

Eradication.— The fight against weeds already on the farm
will depend upon many conditions. Many weeds can be erad-
icated by sowing a crop which requires close cultivation ; others
by the use of smother crops ; others by the repeated sowing of a
quick-growing crop which can be pastured with sheep.

The success of these and other treatments will depend in
some measure on the training of the farmer. It will be readily
seen that the methods used against annuals, biennials, and per-
ennials must necessarily vary. Therefore, the greater the famil-
iarity with the life history of the pest, the greater are the possi-
bilities for success.

Perennial weeds will thrive best in fields where they are
least disturbed, as in pastures and hayfields. When such weeds
are gaining too strong a hold, many of them may be destroyed
by plowing the field and using it for cultivated crops for a few
years. Potatoes, corn, and other summer crops may be used,
but they should be well cultivated.

Annual weeds are often very bad in grain fields or in corn
and other cultivated fields. They may be choked to some extent
by sowing the field very densely with grass for hay or pasture.

EXERCISES RELATING TO WEEDS

1. Make a collection of tile noxious weeds of your neighborhood.

2. Corn-field Weeds. — • Which ones of these are most commonly
found in cultivated fields?

3. Pasture Weeds. — Make a list of the weeds most common in the
pastures of the vicinity.

4. In Grain Fields. — If possible, examine a field of wheat or other
small grain, either while the grain is growing or after it is cut. Make
lists of the weeds growing in the grain or in the field after harvest.

QUESTIONS 157

i

5. Examining Seed Samples. — Get samples of clover seeds, and other

small seeds. Examine each sample for (a) weed seeds; (b) dead seeds;
(c) foreign inert matter or grit; (d) sound seeds true to the variety; (e)
others of useful varieties. Count the number in each of these five classes
and then determine the percentage of each.

6. Numbers of Weeds. — Search the fields, fence rows, road sides
and other places for dense growths of weeds. Bend a wire into a circle
or use a barrel hoop and throw it over the densest cluster you can
find, count the number of weeds in the circle. Determine the number in
a square foot and calculate the number per acre ( 43,500 sq. ft. ) . Do
likewise for several different species of weeds.

7. Study the smothering influence of weeds found growing in rows
of young garden crops, corn, etc.

QUESTIONS

1. What is a weed?

2. In what ways are weeds injurious?

3. How are weeds introduced into new localities?

4. Have you seen instances of these?

5. How can a farmer prevent the introduction of weeds?

6. How may perennial weeds be most easily eradicated?

7. How may annual weeds be eradicated?

CHAPTER XVII
PTERIDOPHYTES

WE HAVE studied that group of plants and the subdivisions
(the seed-bearing plants) which you may consider the most
important and we have learned that there are three other great
groups. (Chapter V.) Although these groups furnish us com-
paratively little in the way of food, clothing and building ma-
terials, yet they are of great interest and of considerable value
to man. To the botanist they are especially interesting because
we cannot get a thorough knowledge of the plant kingdom with-
out studying them. They are of value to all of us because many
plants belonging to these groups are of commercial value. There-
fore, let us consider the next highest group, the Pteridophytes,
which includes the ferns and the related plants.

True Ferns. — The largest and most familiar group is the
order Filicales or true ferns. (Fig. 97.) These plants have
true roots, stems and leaves, but the structure of the stems is
quite different from anything we have studied. - The stems may
be short and erect or creeping, underground type known as
rhizomes, giving rise to many roots and to the masses of green
foliage with which we are familiar. But- in tropical countries
we frequently find the beautiful tree ferns with their very large
trunks. If we cut a cross-section of a stem and examine it under
a compound microscope we find a well-developed fibro-vascular
system composed of practically the same tissues as in the higher
plants but arranged quite differently. The wood cells are in
the centre surrounded by the bast cells which are in turn sur-
rounded by an endodermis. This is known as the concentric
arrangement. These bundles are weak as compared with bun-
158

FRUIT DOTS

159

dies of the spermatophytes, but the stem is strengthened by the
masses of schlerenchyma tissue which can be readily seen.

The leaves or fronds, as they are usually called, are very
similar in structure to the leaves of the Angiosperm. In fact,
the similarity is so striking that it is not necessary to describe
it at this time, but the student will do well to make a careful
study and comparison of the leaf with that of the Angiosperm.

FIG. 97. — A fern glade.

(Chapter IV.) However, the leaves tend to unroll in a peculiar
manner (Fig. 98) which can be readily seen and- which is char-
acteristic of the ferns.

Fruit Dots. — On the under surfaces of many of the older
leaves will be found numerous fruit dots or sori (singular sorus).
(Fig. 99 and 100.) They vary greatly in size, character and
arrangement in the different species of ferns and in most cases
are covered with a delicate membrane known as the indusium.

160

PTERIDOPHYTES

(Fig. 100.) These dots contain numerous sporangia (singular
sporangium) (Fig. 101), which are rilled with spores. Each
sporangium is supported by a stalk and from a side view appears
to be flat, but as a matter of fact is slightly thicker in the centre
than on the margin. The marginal cells are highly specialized
and are of two kinds; the thick-walled cells from about three-
fourths of the distance and the thin-walled cells for the re-
mainder of the distance. When the spores (Fig. 102) are
mature, the drying out of the sporangia results in an uneven

FIG. 100.

Fia. 98.

Fio. 101.

FIG. 102.

Fio. 98. — Young fern leaf showing method of unrolling.
Fio. 99. — Part of fern leaf showing sori or fruit clusters.
Fro. 100. — Part of fern leaf showing sori with indusium.

FIG. 101. — Sporangium, from fern sorus.
FIQ. 102. — Fern spores from sporangium.

tension of the two kinds of cells, a bursting of the sporangium
and a scattering of the spores.

Two Steps in Reproduction. — The spores germinate and
eventually form what is known as the prothallium. (Fig. 103, e.)
In most feme this prothallium is very small and somewhat
heartshaped. It is composed of chlorophyll bearing paren-
chyma cells and has many rhizoids which are very similar to the
root-hairs of the higher plants. They penetrate the moist soil
from which they derive both water and food in the same man-
ner as root-hairs. On the under surface will be found numerous
small bodies, the archegonia (singular archegonium} and the

HORSE TAILS 161

antheridia (singular antheridium). In some ferns they are
borne on the same prothalhis while on others they are borne
on different prothallia.

The Archegonia (Fig. 103, V) are borne near the notch of
the prothallus, and somewhat flask-shaped with the base imbed-
ded in the tissues and the neck extending downward and slightly
curved. An examination with the compound microscope shows a
large egg (ovum) or female cell (Fig. 103, c") in the large part
and a row of canal cells in the neck. These canal cells become
gelatinous or semi-fluid in character.

The Antheridia (Fig. 103, 6') are spherical and produce
great numbers of minute, unicellular, spiral, free swimming
bodies known as sperms or male cells. (Fig. 103, c'.) The
sperm cells swim in the moisture on the surface of the prothallia
and the soil, and some few eventually reach the archegonia, enter
the canal and one unites with each ovum or egg cell. This is
known as fertilization. It corresponds to the fertilization of
the egg in the embryo sac of the Angiosperm. (Chapter VI.)
As a result of this fertilization, cell division occurs and the
egg grows into a fully developed fern, (Fig. 103, e, /.) With the
development of the fern, the prothallus, upon which it at first
feeds, is gradually destroyed.

Horse Tails. — There are many other fern-like plants which
we will find quite interesting if we have time to study them.
Among the most common are the horse-tails or scouring rushes
(Equiseturri). The aerial stems are derived from an under-
ground stem and may be branched or unbranched, hollow jointed,
fluted with well-marked longitudinal ridges and furrows and
infiltrated with silica which makes them rough and rigid. The
branches and modified leaves are always in whorls and at the
nodes. At each node the stem is surrounded with membran
ous sheaths which correspond to the leaves of higher plants. A
cone-shaped fruiting structure is borne at the apex of the stem
11

162

PTERIDOPHYTES

and is composed of modified leaves or Sporophylls, bearing small
Bacs or sporangia containing the spores. The spores have four
spiral rings which straighten out when dry and roll up when
wet and thus cause the spore to move over short distances. The

Fio. 103. — Diagrammatic representation of the life history of the fern: a, prothallium;
b',antheridium;b", archegonium;c', sperm; c", ovum;d, obspore;e, prothallus and young fern;
f, mature fern snowing under-ground stem, root and leaf bearing gori; g, sporangium; h, spores.

life history of the horse tail is practically the same as that of
the true fern.

Other Fern-like Plants. — The so-called club mosses or
ground pines, the selaginellas and the quillwort are groups of
small plants which have life histories very similar to that of the
true ferns.

The greatest value of the ferns at the present time lies in
their great beauty for decorations of various kinds and we must

EXERCISES WITH PTERIDOPHYTES 163

not forget that the growing of ferns is an industry representing
many thousands of dollars. In past ages the ferns were much
more abundant and much larger than at the present time and
we are indebted to them, to some extent, for the enormous beds
of coal from which we secure most of our supply of fuel. (Chap-
ters* IX and XVIII.)

EXERCISES WITH PTERIDOPHYTES

1. Examine a fern carefully and note its roots, stem, leaves, sori and
indusium.

2. Cut cross-sections of the stem and examine under a compound
microscope and note the points referred to in the text. Material for this
purpose can be preserved in alcohol or formaldehyde.

3. Study the leaf in the same manner as indicated for leaf of the
Angiosperm. (Chapter IV.)

4. Remove a sorus, crush and examine under the compound micros-
cope. Note the character of the sporangia as referred to in the text.

5. Examine a prothallus with a hand lens or under a low power
of the compound microscope. Material for this purpose can usually be
secured from a neighboring greenhouse.

QUESTIONS

1. Where do you find the stems of the fern?

2'. Compare the fern stem with the stems of a flowering plant.

3. Compare the leaf of a fern with the leaf of a flowering plant.

4. What do you find on the fern leaf not found on the ordinary leaf?
Reference. — Read all you can about the formation of coal-beds. For

such information see a good encyclopedia and works on Geology.

CHAPTER XVIII
BRYOPHYTES

WE WILL now study the two great groups of Bryophytes, the
Musci or mosses and the Hepaticce or liverworts. They are
of little value at the present time except for packing material
where it is necessary to retain moisture, but in past ages (the
Carboniferous Age) they were much more abundant than at
any time since and we are indebted to them for the greater part
of our enormous beds of coal which we are now using.

Mosses. — An ordinary moss plant presents an upright stem
with three more or less distinct rows of leaves. A more careful
examination will show us that this stem is very weak, that it does
not contain a fibro-vascular bundle but is composed of elongated
parenchyma cells. We will find also that the leaves are com-
posed entirely of parenchyma cells and that their apparent mid-
rib is composed of elongated cells. These characteristics very
readily convince us that we are studying a very simple type of
plant as compared with the Pteridophytes and Spermatophytes.

Arising from the top of this plant is a long, slender stem,
ftetea-, bearing a capsuJe which is covered with a cap or calyptra.
(Fig. 104, a, ?;.) If we remove this cap we will find the oper-
culum (Fig. 104, c), which is a small cover on the end of the
capsule. If we remove the operculum (Fig. 104, e) we will find
the peristome or teeth (Fig. 104, d.} These teeth are very sensi-
tive to varying degrees of moisture which causes them to move
inward and outward and thus controls the distribution of the
spores which are borne within the capsule. These spores will
grow and each produce a filamentous prothallus or protonema
which gives rise to new moss plants.
164

MOSSES

165

But moss plants also have sexual organs similar to the ferns.
They are borne in the tops of the leafy plants early in the spring
and are known as antheridia and archegonia. (Fig. 104, /, #.)
The antheridia are club-shaped and have very long necks. The

FIG. 104. — a, mature moss plant; b, capsule covered with calyptra; c, capsule without
calyptra; d, capsule with operculum removed showing peristome; e, operculum; f, arche-
goniuiii; g, antheridium; h, paraphyses or sterile organ.

antheridia and archegonia are always borne on different plants.
The process of fertilization is practically the same as in the
ferns and the fertilized egg grows into the seteee and capsule
referred to above.

166

BRYOPHYTES

There are two large groups of mosses, the Bryales, which
we have just described and the Sphagnales. This latter group
is the characteristic moss of the sphagnum swamps and was the
most important group of plants in the formation of peat and
coal beds.

The Hepaticae or liverworts are not so familiar to most
of us as are the mosses and ferns. They rank next below the
mosses and are an extremely interesting group for study, but of
very little, if any, economic value. There .are several divisions
of the hepaticae, but one of the largest and most common forms

FIG. 105 Fia. 106 FIG. 107

FIG. 105 — Marchantia polymorpha showing two cupules bearing gemmule.

Fio. 106. — Surface view of marchantia polymorpha very much magnified.

Fia. 107. — a, female plant of marchantia polymorpha bearing two archegonial branches;

I >, also a single antheridial branch from a male plant.

is known as Marchantia polymorpha. (Fig. 105.) It reminds
us of the fern prothallus but is much larger and branching. It
is thick along its central axis and thin at the edges, lies flat on
the wet soil and has many rhizoids. The upper surface is
divided into small areas with a small opening (stoma) (Fig.
106) in the centre of each. These small areas give it a super-
ficial resemblance to the liver of an animal and therefore the
name " liverwort." As the apical part of the plant grows the
basal part is gradually dying. Along the upper surface will fre-
quently be found saucer-shaped structures containing small buds
which are capable of growing into new plants; a non-sexual
method of reproduction.

THE HEPATIC^ OR LIVERWORTS

167

If we examine a cross-section of the thallus under a com-
pound microscope we will find the epidermis covering a large
chamber beneath each stomata. Within the chamber are great
numbers of delicate chlorophyll bearing parenchyma cells while
the lower cells contain little or no chlorophyll.

The sexual organs are borne on separate plants. The female

9'

f

Fia. 108. — Diagrammatic representation of the life cycle of Marchantia polymorpha; a',
mature male plant; a", mature female plant; b' antheridium; b" archegonium; c', sperm;
c", ovum; d, oospore; e, young sporoplyte; f, and f", spores; g', and g", young plants.

plants (Fig. 107, a) bear erect stalks supporting radiating struc-
tures which resemble the handle and ribs of an umbrella in their
arrangement. On the under surface of the radiating parts will
be found the minute flask-shaped archegonia. The male plants
(Fig. 107, b) bear erect stalks supporting disk-shaped bodies,
on the upper surface of which will be found minute openings
into cavities containing the antheridia. The fertilization is
the same as in the ferns and mosses. The stalk of the female

168 BRYOPHYTES

body elongates and numerous capsules are produced on the under
surface. These capsules contain numerous spores and also some
spiral-shaped bodies known as elaters, which burst the capsules
and help to distribute the spores. The spores grow and pro-
duce new plants. (Fig. 108.)

There are many other forms of liverworts, some of which
are leafy and resemble moss plants, and are frequently mis-
taken for mosses.

EXERCISES WITH BRYOPHYTES

1. Examine a moss plant and note the character of its stem and
leaves.

2. Examine a fruiting moss plant and note the setea, capsule, and
ralyptra. Remove the calyptra and examine with a hand lens for the
peristome.

3. Examine a non-fruiting plant of the Marchantia polymorpha
and note shape, surface area, stomata, and cupules or non-sexual fruiting
cups. Scrape some of the rhizoids from the under surface and examine
under the compound microscope.

4. Cut a cross-section and examine under a compound microscope
and note different types of parenchyma cells.

5. Examine the plants which are carrying the fruiting bodies.

6. Crush a capsule and examine under the microscope; note spores
and elaters.

QUESTIONS

1. To what great group do the mosses and liverworts belong?

2. Describe a true moss plant.

3. Describe the thallus of the liverworts.

4. How and where are the sexual organs of the liverwort borne?
How does the fertilization take place?

5. 'What are the most striking points learned in your study of Bry-
ophyt«s ?

CHAPTER XIX
THALLOPHYTES

WE HAVE now come to the lowest great division of the plant
kingdom,, the Tliallopliytes, which are subdivided into three
divisions, the Algce, the Fungi and the Bacteria. The second
and third of these groups do not contain chlorophyll and are
therefore quite different in habit from all other groups of the
plant kingdom.

The algae vary greatly in both size, structure and color, but
all of them contain chlorophyll and are able to do the work of
photosynthesis or starch-making. The range from the small,
one-celled plant which cannot be seen without the aid of the
microscope, through delicate thread-like forms up to the enor-
mous sea-weeds, possessing root-like, stem-like and leaf-like
organs. They are widely distributed throughout the world and
are of much greater importance than we might at first suppose.
Minute forms are found in great numbers, causing the green
stain on the bark of trees and stones and brick walls, in the
streams and pools, and in the seas, gulfs and bays and even the
broad ocean itself.

The types are entirely too numerous to mention in a work
of this kind, and therefore, we must content ourselves with a
study of two or three of the most common forms. Many of the
unicellular forms found in moist places on trees and walls repro-
duce by simple division, each division resulting in the forma-
tion of two new plants, each similar to the parent. Each plant
is capable of performing all the function of a much larger and
more complex plant; i.e., the absorption of water and minerals
in solution and of nitrogen, the taking in of carbon dioxide, and
photosynthesis and reproduction.

169

170

THALLOPHYTES

The filamentous forms are composed of single rows of cells,
each cell capable of sub-division, and if separated from the
others,- of producing a new plant. The very common Spirogyra
(Fig. 109) is an excellent type for study. The cells are cylin-
drical in shape and attached end-to-end. Each cell contains an
inner lining of protoplasm and numerous cross strands of the
same material ; also a nucleus which may be located in any
part of the cell but usually in the centre. The protoplasm and
nucleus are transparent and cannot be seen readily without the

FIG. 109.

FIG. 110.

Fio. 109. — Spriogyra: a, single cell showing chromatophore and nucleus; b, two plants

showing sexual reproduction.

Fio. 110. — (Edogonium: a, plant showing non-sexual cells; b, plant showing oogonium

and antheridiuni.

use of an artificial stain. The spaces between the strands of
protoplasm are known as vacuoles and are filled with water.
Embedded in this protoplasm will be readily seen the spiral
chromataphores or chloroplasts containing the chlorophyll. Scat-
tered along this chlorophyll will be seen the round shining
pyrenoids which are supposed to be the centres for food forma-
tion or photosynthesis. The cell of the spirogyra may be looked
upon as a typical plant cell in which all the functions of plant
life are performed.

Spirogyra. — If we examine a great many plants of spiro-
gyra we will probably find some specimens which are attached

OTHER ALGLE 171

two-and-two by means of short tubes, the one plant being male
and the other female. The tubes are outgrowths from both
plants which tend to unite; the separating walls are dissolved
and the contents of the male cells pass into and unite with the
contents of the female cells, forming what is known as zygo-
spores, which will eventually produce new plants.

Ulothrix is another filamentous form which produces a
large number of ciliated free-swimming cells known as
zoospores. They swim for a time, come to rest and each grows
into a new plant. In some cases these free-swimming cells
(gametes) unite in pairs and form zygospores.

QEdogonium (Fig. 110) is another filamentous form, a spe-
cies which presents a great variation in sexual character. A
cell may produce a single large, ciliated cell or zoospore which
will swim for a time, attach itself and grow into a new plant.
Or, it may produce a large female cell (gamete) which is
retained in the old cell-wall (ob'gonium) and fertilized by small
free-swimming zoospores or sperms (gametes) which are pro-
duced by another cell or antheridium. In other species of
(Edogonium the oogonia are produced in large female plants and
the antheridia in the small male plants.

The Vaucheria are filamentous but unicellular and multi-
nuclear forms. The non-sexual reproduction is by the formation
of a cross wall at the end of a filament, thus forming a cell from
which a single large motile or non-motile spore is produced. The
sexual reproduction, is by the formation of oval oogonia, each
containing a single large ovum or egg and curved, tubular an-
theridium containing many small sperms. The sperm escape
and at last one reaches the ovum which is fertilized and results
in an oospore or resting spore. This is more nearly like the
liverworts, mosses and ferns than most of the algae.

Other Algae. — Concerning the many other forms of algae,
we may briefly say that they are the forests and the pastures of

172 THALLOPHYTES

the waters and without them animal life in the water would
be as impossible as animal life on the land without land plants.
We may also add that some articles of commerce, such as iodine,
are obtained from the algae, and the time may not be far distant
when the enormous beds of seaweeds will prove a valuable source
of commercial potash for fertilizers.

The fungi are surprisingly like the algae, but differ from
them in, the fact that they do not possess chlorophyll. There-
fore, they are unable to do the work of photosynthesis and must
depend primarily upon organic matter, i.e., either dead or living-
plants or animals, for their food supply. Those which live on
dead organic material are saprophytes and those which live
on living organisms are parasites. We will give brief descrip-
tions of the most common types.

The yeast plants (Saccharomyces) are among, the very sim-
plest in structure. They are very minute, spherical, and repro-
duce by budding. They are found abundantly in sugary solu-
tions and are extremely important in alcoholic fermentations.
We are all familiar with their use in the making of bread.
Although simple in structure they have a method of reproduc-
tion which takes them from the lowest of the fungi.

The common bread mould (ETiizapus nigricans) (Fig. Ill)
is one of the best known of the lower fungi. It occurs on stale
bread kept in damp places and appears as numerous delicate,
white threads containing protoplasm, both in the bread and erect
on. the surface. These threads are called mycelium, but a single
one is often called the hypha. On the tips of the hyphre are
numerous spherical sporangia or spore cases containing spores.
They become black with age, burst and discharge the spores
which are readily carried in the air.

The sexual reproduction is by the formation of lateral
branches from two filaments. These branches come in contact
and swell, a cell-wall is formed across each and the wall at

PARASITIC FUNGI

173

the point of union is dissolved, permitting the union of the
contents of the two cells. This results in the formation of the
zygospore which is capable of giving rise to a new plant. The
sexual method of reproduction rarely occurs in nature.

The species of Saprolegnia (Fig. 112) are parasitic on fish,
but will grow on floating dead flies and other insects and occa-
sionally on decaying food. Thread-like filaments of the fungus
grow out from the material on which it is living. Cross walls
or septa are formed in these filaments and great numbers of

Fio. 111.— Rhizopus nigricans or bread mould; a, entire plant showing sporangia; b,

mature zygoapore.

unicellular, free-swimming zoospores will be produced in the
apical cell. These zoospores escape, swim for a time, become
attached to suitable food material and produce new plants. Cer-
tain of the filaments will also produce antheridia and ob'gonia,
giving rise to ob'spores, but there is some doubt as to whether
fertilization really occurs.

Parasitic Fungi. — The downy mildews, powdery mildews,
and many other fungi are parasitic on the higher plants and are
causes of heavy losses to our agricultural interests every year.

174

THALLOPHYTES

Among the most interesting of these parasitic fungi are the
rusts and smuts, some of which are very destructive to our grain
crops. Some of the rusts have the peculiar habit of requiring
two distinct host plants in order to complete their life cycle.
In such cases they have two or more stages, one occurring on one
host and the other on the other host; the spores in each case
will, as a rule, grow only on the opposite host plant.

FIG. 112.— Saprolegnia. a, infested fly; b, immature sporangium; c, mature sporangium;
d, same after the escape of the spores; e, free swimming spores.

The fleshy fungi (Fig. 113), many of which are spoken of
as mushrooms, and toad-stools, usually grow either parasitically
or saprophytically on woody plants. Some are umbrella-shaped,
while others are shelving in character and still others are the
well-known puff-balls.

The stipe or stem of the mushroom usually rests in a volva
or cup. The stipe supports the pileus, or cap, on the under side

OUR GREATEST INTEREST IN THE FUNGI 175

of which we find the gills or lamellae on the surface of which
the spores are borne. We frequently speak of fungi as growing-
very rapidly because of their sudden appearance in a fully de-
veloped form. However, the growth is not nearly so rapid as
it appears. The mycelium may grow slowly and for many
months in the tissues of the host plant, which it is slowly eating

Fio. 113. — Two specimens of mushrooms. The one on the left shows the annular or ring.

away, and finally come to the surface and form the sporophores
or fruiting bodies, with which we are familiar, in a very few
hours. Some few fungi are used for food, but many of them
are deadly poison and the inexperienced person will do well to
refuse all forms except the strictly fresh puff-balls.

Our greatest interest in the fungi lies in the fact that so
many of them are parasitic on our farm crops and cause the loss

176 THALLOPHYTES

of many millions of dollars every year. This loss is so enormous
that a new branch of botany, known as plant pathology, has
been developed for the study of plant diseases and methods for
their control.

EXERCISES WITH THALLOPHYTES

1. Examine algae, as many as circumstances will permit, and note the
points referred to in the text. The algae may • be collected from small
streams and kept in jars and dishes on the laboratory tables for many
days and studied with the aid of the compound microscope.

2. Collect many specimens of parasitic fungi found on leaves
and fruits of plants, especially on cultivated plants. Study them in their
different stages of reproduction.

3. Develop yeast in a weak solution of water and sugar and study
specimens under the microscope.

4. Keep some moistened bread in a warm chamber (i. e., under an
inverted jar or in a closed dish). When mould has developed study its
different stages.

5. Keep some dead flies in an open bottle of water and watch for
the development of Saprolegnia; then make a microscopic study of it.

QUESTIONS

1. What three groups are included in the Thallophytes ?

2. In what respect do all the algae resemble each other?

3. Describe reproduction in unicellular algae.

4. Describe reproduction in Spirogyra.

5. Describe reproduction in Ulothrix.

6. Describe the forms of reproduction in Oedogonium.

7. How is reproduction accomplished, in Vaucheria?

8. Tell of the economic value of algae.
0. How do the fungi differ from algae?

10. Describe the structure of yeast plants.

11.' What is the structure of bread mould? Tell of its reproduction.

12. Give examples of parasitic fungi. Of what importance are they?

13. Tell what you can of the fleshy fungi.

Reference. — Read accounts of algae and of fungi, found in an encyclo-
pedia and special books on these subjects.

BACTERIA

Bacteria are the smallest of all plants and in fact some of
them are the smallest known organisms. It would require
125,000 of the smaller ones, placed side by side, to make a line
one inch long. They are like the fungi in that they do not con-
tain chlorophyll and cannot perform the work of photosynthesis.
Therefore, they are either saprophytic or parasitic. Some are
motile and others non-motile. They multiply by simple cell
division and many species form resting spores which enable them
to resist extremes of temperature and humidity.

Abundance. — Bacteria are more abundant than other forms
of life. They float in the air that we breathe, are in the water
that we drink and the food that we eat. They are to be found
in our mouths, lungs, stomach, and intestines. They cause the
souring of milk, the fermentation of various liquids, the decay
of fruits, vegetables and meats. Fortunately the great major-
ity are harmless and many are beneficial. Among the most
interesting of the beneficial species are those which are involved
jn the fixation of nitrogen. (Page 117.)

Causes of Disease. — However, many bacteria are the causes
of diseases of both plants and animals. Among the most serious
of plant diseases caused by bacteria are the fire blight of the
pear and apple, the black rot of cabbage and related plants and
the root or crown gall of our fruit trees and many other plants.
Many serious animal diseases are caused by bacteria such as
tuberculosis or consumption, diphtheria, tetanus or lockjaw,
grippe, anthrax, cholera and many others which attack man
and the lower animals.

12 177

178 BACTERIA

With our increasing knowledge of these diseases we are
learning to combat them. We are learning how to cure patients
suffering from them and also how to prevent them. It is an
old saying that "an ounce of prevention is worth a pound. of
cure," and we are learning that proper sanitation, the removal
of filth in which the bacteria breed, the protection of drink-
ing water, the destruction of flie*, mosquitoes and other insects
that carry bacteria, and personal cleanliness are great helps in
the prevention of bacterial diseases.

The study of bacteria has resulted in the development of
a branch of applied botany known as bacteriology which is re-
ceiving a great deal of attention, especially in our Universities
and Medical Colleges.

The Myxomycet.es (Mycetozoa) or Slime Mounds. — These
are forms of life which possess both plant and animal charac-
teristics. They are truly on the border between the plant and
animal kingdoms. They are found in the water or on wet soil
or decaying vegetables as naked slimy masses of protoplasm,
called plasmodia. They move very slowly by a peculiar creep-
ing movement similar1 to that of the amceba, which is one of the
lowest forms of animal life. This plasmodium has the char-
acteristics of the species to which it belongs and finally produces
great numbers of spores, similar to those of some of the fungi.
These spores eventually give rise to minute one-celled amoeboid
individuals which unite to form a new and growing plasmodium.
One species of this group (Plasmodiophora, brassicce] is the
cause of the very common and serious club root disease of
cabbage.

EXERCISES WITH BACTERIA.

1. Put a few small shreds of meat into two flasks of water. Boil both
for thirty minutes or more; plug one with cotton immediately; leave the
other open and set both away for a few days. Examine them from time
to time and note differences in their appearance. When they show very

QUESTIONS 179

noticeable differences examine a drop of each under the compound micros-
cope. What do you see? What has caused the difference?

QUESTIONS

1. What can you say of the importance and abundance of bacteria?

2. What plant diseases are caused by bacteria?

3. Tell of the character and occurrence of the slime moulds.

4. Why do canned fruits and vegetables keep? Why do they occa-
sionally spoil?

PART II

MOST IMPORTANT FAMILIES OF ECONOMIC
PLANTS, WITH SPECIAL EXERCISES

CHAPTER XXI
IMPORTANT FAMILIES OF PLANTS

First Uses of Plants by Man. — The origin and development
of agriculture are veiled in the mystery and tradition of the
early civilization of the human race. The early historical records
are incomplete and no one knows just when the different races
began the practice of agricultural methods. Traditions con-
nected with some plants tell us that they were introduced by
gods or by kings. It may be that the introduction of some plants
date from the reign of certain great monarchs, but in most cases
these traditions are of doubtful value.

It is very probable that most, if not all, races of people were
more interested in war, hunting and fishing than in agriculture,
and that under these circumstances the beginnings of agriculture
must have been feeble, interrupted and obscure. The destruc-
tion and abandonment of growing crops by war or in the search
of better hunting grounds was not conducive to the advance-
ment of agriculture.

Early agriculture must have developed very slowly, and as
a result of necessity, or because it made life easier for the
individual and the tribe. These early beginnings probably
originated in, the gathering and storing of wild crops, followed
first by a protecting of these wild crops from the ravages of
wild animals and other tribes, then by the increasing of their
range by scattering seeds, and finally by cultivation. This last
step very naturally led to improvements in methods and the
selection of the most valuable plants.

Our earliest records of agriculture concern Egypt and
China, but it is very likely that agriculture was practiced in
India and other parts of Asia as early as in China. There was

183

184 IMPORTANT FAMILIES OF PLANTS

aiso a very ancient agriculture in parts of America, but it is
very doubtful if it is as old as the eastern agriculture.

Mankind very naturally began to cultivate those plants which
they had previously used from the wild and the practice very
naturally tended to discourage their nomadic habits. Increas-
ing population very naturally made greater and greater demands
on agriculture and resulted in improved methods, the selec-
tion of the best plants and the introduction of new plants.

Westward Movements. — But man could not give up his
old nomadic habits quickly. His love for the chase, for travel
and exploration, for war and conquest were strong and must be
satisfied by actual experiences. Therefore, we see certain
great movements of the human race, such as the migrations of the
early Christians from Judea westward, the Crusaders from
Europe back to the Holy Land and their return to Europe, the
discovery, conquest and settlement of America. These and many
other similar movements of greater or less proportions very
naturally resulted in the introduction of many new and valuable
plants into countries in which they were previously unknown.

The history and origin of our agricultural plants is obscure
and in some cases the confusion is increased by the names which
many of the plants bear. The English walnut is from Persia
and not England, the Irish potato is from Peru and Equador
and not Ireland, the peach (Prunus persica} is from China, but
went into Europe by way of Persia.

A knowledge of our most important cultivated plants would
be well worth while and very interesting. It is of much greater
importance than a knowledge of wild flowers, although this line
of work should not be neglected. All of our cultivated plants
were originally wild plants, and in recent years many of these
so-called " wild plants," such as alfalfa and sweet clover, have
been brought under cultivation. Useful plants of our own part
of the world may be of very little value in other parts.

CABBAGE 185

IMPORTANT ECONOMIC FAMILIES OF PLANTS

Students should familiarize themselves, in so far as pos-
sible, with representative plants in the following families, by
studying the living plants where possible, and by giving
special attention to their commercial importance. Most of these
families are represented by plants which are common to our
farms ; the fruits of others can be secured on the local markets ;
and the historical accounts and commercial uses will furnish
important lines of study. The studies of these families may be
supplemented by others that are convenient or of local
importance.

MUSTARD FAMILY (CUUCIFER.E)

The flowers of this family are usually borne in terminal
racemes; usually white or yellow; four petals; four sepals ar-
ranged in form of a cross ; four long and two short stamens and
two stigmas on a single, two-chambered, many-seeded ovary.
The plants are mostly herbaceous, sometimes woody, with cylin-
drical or angular stems1 and with a pungent, watery juice. The
leaves are simple, usually alternate, entire, lobed or bisected
and without stipules. The fruit is long, slender and pod-like.
None of these plants are poisonous. Many members of this
. family of plants are very useful as vegetables, forage crops
and in medicines. Let us consider a few of the most common
and important.

Cabbage (Brassica oleracece L.) (Fig. 114). — This well-
known plant is derived from a wild plant in the south of Eng-
land and other parts of western Europe. It is perennial, pro-
ducing yellow flowers and abundant seeds the second year.
Plants selected for seed are put in trenches and covered with
soil for the winter. They are reset the following spring, bloom
and produce seed abundantly. Cabbage seed growing is a well-

186 IMPORTANT FAMILIES OF PLANTS

developed industry in some parts of the country. It is not known
when the cabbage was first used as food. It is referred to in
literature antedating the Christian Era by about three hundred
years, and it is now very generally used throughout the world.
There are many important commercial varieties. These may
be classified into (a) the early or short-season group, with

FIG. 114. — The spherical form of cabbage.

small round or pointed heads, as Jersey Wakefield; (6) the late
or long-season group, with large round or flat heads, as Drum-
head and Flat Dutch. All endure spring and fall frosts.

Cauliflower (Fig. 115), Brussels sprouts, Kale and Kohl-rabi
(Fig. 116) are derived from the same wild plant.

Mustards (B. alba Gray and B. nigra Koch). — These well-
known plants are annuals and produce seeds of considerable com-

CABBAGE

187

FIG. 115. — Cauliflower, with outer leaves trimmed.

FIG. 116. — Kohl rabi of edible size.

188

IMPORTANT FAMILIES OF PLANTS

mercial importance. They are used in the preparation of foods
and also as medicines. Their use antedates the Christian Era.

FIG. 117. — The flat form of true turnip with white flesh.

Field Turnips (B. campestris*) and true turnips (B. rapa)
(Fig. 117) are well known plants used for food for both man
and beast. They originated in northern Europe and Asia and

VIOLET FAMILY 189

their use also antedates the Christian Era, but they were not
grown extensively until early in the seventeenth century. Seed
turnips are also kept and grown the second season in the same
manner as the cabbage.

There are several types and varieties of the true or flat
turnips. Those with white flesh are most popular, but the
yellow-fleshed sorts are also grown. The field turnip, or ruta-
baga, has yellowish flesh and is rich in flavor. They produce
heavier yields than other turnips.

The radish (Rapkanus sativus), the horseradish (Coch-
learia armoracia) , the rape (Brassica napa), and the water
cress (Nasturtium officinale) and many other valuable plants
belong to this family. Most of them originated in the tem-
perate regions of Europe and Asia, and their use and cultivation
dates back to a very early period in history.

All of these plants are grown from the seeds which are
usually sown direct in the soil in which they are to be grown.
The water cress is usually started by transplanting from one
locality to another. The mustards frequently escape cultiva-
tion and become troublesome weeds. This family also includes
wild radish, field cress and many other weeds which are more
or less troublesome. However, most of them are annuals or
biennials and can be controlled by using a crop requiring fre-
quent cultivation or if growing in wheat or oats by spraying
with sulphate of iron.

VIOLET FAMILY

Flowers perfect, irregular, axillary, usually solitary, two
bracts at base or near the middle of each pedicel. Five sepals
which are usually free and persistent ; five petals \vhich are
hypogynous and alternate with the sepals, unequal in size, the
lower one forming a hollow spur ; five stamens inserted on lower

190

IMPORTANT FAMILIES OF PLANTS

part of calyx; fruit a three-parted pod with parietal placenta
leaves alternate and stipulate.

This family includes the many species and varieties of
violets. These flowers were known through practically all his-
torical time and are now grown very extensively to supply the
flower markets of our cities. The cultivated pansy is a species
of violet (V. tricolor} (Fig. 118).

'; ,

FIG. 118. — Pansies are so hardy as to stand much frost.

Commercial violets are grown from cuttings which are
started in cool greenhouses. Common varieties of pansies are
grown from seeds, but some of the more important com-
mercial varieties are grown from layers or from cuttings made
late in the season. If pansy beds are covered in the fall with
a loose layer of grass or leaves, they will usually survive the
winter and be more vigorous the second than the first year.

COTTON 191

MALLOW FAMILY ( MALVACEAE )

The plants of this family are either herbs or shrubs. The
flowers have five sepals united at the base, five petals, many
stamens and a single- one-chambered ovary with many pistils.
The mature fruit is a capsule.

Cotton. — In this family we find the cotton plants (Gos-
sypium herbaceum L., G. barbadense L., G. arboreum L.) which
are among the most valuable of the fibre or lint plants. The
fibre is produced on the seeds within the capsule. The cotton
plant was used long before Christ. It probably originated in
India and spread throughout the tropical and subtropical parts
of the world, although the early Spanish explorers claim to have
found it growing in Mexico and Central America and that the
natives were using it for making clothing. It is one of the most
important crops of the southern states and is used for many
purposes other than that of making clothing, such as gun-cotton
and collodion. The oil is extracted from the seeds and used for
culinary purposes and as a substitute for olive oil and the re-
maining solid part of the seed is used for stock feed. Cotton-
, seed meal is also used extensively as a fertilizer for the soil.

Accepting the idea that cotton is a native of both the old
and the new world, it is evident that G. herbaceum is the old
world form, G. arboreum (tree cotton) the African form and
G. barbadense the American type. Many varieties of types are
now recognized ; one of the most popular of our American types
is the " sea island " or " long staple cotton " which is a variety
of G. barbadense.

The fruit of the okra or gumbo (Hibiscus esculentus L.)
(Fig. 119) is extensively used in soups, stews and catsups, espe-
cially in the southern part of the United, States. Its origin is
unknown, but it probably originated in Africa or the American
tropics.

192 IMPORTANT FAMILIES OF PLANTS

FIG. 119. — Pods of okra or gumbo in green and ripe stages.

FLAX FAMILY 193

The Hollyhocks (Althaea, rosea) (Fig. 120), mallows and
some other interesting ornamental plants belong to this family.
Most of the members of this family are grown from seeds,
but the hollyhocks and related forms persist from year to year.
The cheese (Malva rotundifolia) and the Indian mallow or vel-
vet weed (Abutilon abutilon) are common weeds.

STERCTJLIA FAMILY (STERCULIACE^)

The members of this family are trees or shrubs somewhat
similar to the Malvaceae, but the capsules are much larger and
are fleshy. Here we find one of the very important plants which
America gave to the world, the cocoa or chocolate plants —
(Theobroma cocoa}. It is tropical and was taken to Europe by
the Spaniards about 1520, but it was more than a hundred years
before its spread to England. It is now cultivated in other parts
of the world, but the greater part of the supply comes from trop-
ical America.

FLAX FAMILY (LINAGE^)

Herbaceous, slightly woody plants with perfect, regular
flowers, borne in terminal racemes or corymbs. Five sepals, oc-
casionally four, hypogynous; stamens, same number as petals
and alternate with them; styles three to five; ovary five to four-
chambers with two ovules in each chamber ; fruit capsular.

Flax (Linum usitatissimum, and L. angustifolium) is
one of the most important fibre plants. It is supposed to have
originated in some of the Mediterranean or Far East countries,
but its use as a fibre plant began long before the Christian Era.
This is a very important crop in some parts of the United States,
especially in Minnesota and the Dakotas. It is grown pri-
marily for the fibre which is used in the manufacture of linen
and for the seed from which the linseed oil of commerce is
extracted.
13

194 IMPORTANT FAMILIES OF PLANTS

FIG. 120. — Hollyhock, representing the flower type of the mallow family.

RUE FAMILY

195

The oil is used in the manufacture of paints, varnishes,
patent leather, linoleum and other products. The cake and meal
left after extracting the oil is used extensively for stock feed.

FIG. 121. — The sweet orange, often nearly seedless.

KUE FAMILY

Shrubs and small trees with perfect flowers. Five sepals ;
five to ten petals ; many stamens ; style one, ovary ripening into
a many-chambered berry, capsule or samara.

196

IMPORTANT FAMILIES OF PLANTS

The sweet orange (Citrus ciurantium) (Fig. 121) is the
•best-known and most important fruit of this family. No one
knows just where the orange came from or where it was first
used by man, but it probably came from South China or India
and was brought into Europe by the returning Crusaders or the
Moorish invasion of Spain or possibly both. It was introduced
into America by the early Spanish explorers.

The grapefruit (C. decumana), the lemon ((\ limonum'}.

Fia. 122. — Modern improved grape.

the lime (C. limetta) and the citron (C. medica) are important
members of this genus.

VINE FAMILY

This family is made up of shrubs, usually climbing by means
of tendrils ; alternate, simple or compound leaves ; flowers min-
ute, greenish, perfect or imperfect ; calyx entire or four to five
toothed ; petals four or five, separate or united and disappearing
very soon after development ; stamens four or five and opposite
the petals ; pistil one, consisting of two to six chambers ; fruit
usually a two-celled berry.

PROPAGATION

107

In this family we find the grape (Fig. 122), which is thought
to be the oldest of the cultivated fruits. The very, very early
historical records refer to grape-growing and wine. The most
important grape of the old world is the Vitis vinifera, which is
probably of Asiatic origin. In Europe, the grape is grown
largely for wine, but it is also grown for raisins and other
purposes. The effort to introduce the European grapes into the
American colonies was a failure, owing to the fungous diseases
and insects which destroyed them. But in time a number of

FIG. 123.— Grape-vine cuttings of four forms. A, one bud or single eye; B, simple
cutting showing two buds; C, heel cutting with some of the wood of the larger stem;
D, mallet cutting, with a piece cut out of the larger stem. (Productive Farming.)

good varieties were developed from the native American grapes.
Among the most important are the Concord and Catawba types
from V. labrusca and the Scuppernong from the V. rotundi-
folia. With the spread of civilization westward, the European
grape has been introduced into southern California. In America
the grapes are grown primarily for food instead of for the pro-
duction of wine.

Propagation. — Grapes are usually propagated by means of
cuttings, but can be grafted without great difficulty. Four com-
mon forms of grape cuttings are shown in Fig. 123. It is
usual with our varieties east of the Mississippi to use simple
cuttings with two or three buds, shown at B in the* figure. Cut-

198 IMPORTANT FAMILIES OF PLANTS

tings are made in early winter and stored in wet sawdust in a
cool cellar. Here they form calluses over the wounds and elab-
orate the food stored in the tissues, and are ready to grow when
set in the soil in the spring.

Some varieties are rooted in sharp sand under glass. Others
are commonly planted in garden soils deep enough to allow only
one bud to show. The soil should be tramped firmly. The
planting is done after all danger of frost is over. They are set
a few inches to one foot apart in rows, and the rows far enough
apart to allow of clean cultivation. They should become well
rooted and make some growth the first year in the garden or
nursery. They may be then transplanted to the permanent vine-
yard. The distances apart in vineyards vary from six to twelve
feet, depending upon varieties, method of trellising, and style
of pruning to be used. The history of grape growing in America
is extremely interesting and well worth reading. An excellent
account is given in Bailey's " Evolution of Our Native Fruits."

This family also includes the Virginia creeper, Boston ivy,
and some other ornamental vines.

SOAP BERRY OR MAPLE FAMILY (ACERACE^l)

i

This family includes many shrubs and trees, with saccharine
sap; leaves opposite, simple or palmately lobed, occasionally
palmately or pinnately divided; flowers small, regular, usually
polygamous or dioecious, occasionally apetalous; pistil one,
two-chambered.

Maples.— This family contains the maples (Fig. 124) of the
genus Acer which are very -important as shade and ornamental
trees. Among the most important of our native species are the
silver maples (A. saccharinum) , the red or scarlet maples (A.
rubrum), the sugar or rock maples (A. saccharinum) , the box
elder (A. negundo} and others. The Norway maple (A. platan-

PEA FAMILY

199

oides) is used extensively for shade and the Japanese species
are used extensively for ornamental purposes.

A very excellent grade of sugar is made from the sap of
the sugar maple and its manufacture forms a very important
industry in some parts of the country, especially in the New
England States and the northern states farther west. In the
early history of the country, this was the most important and
in many cases the only source of sugar for the early settlers.

FIG. 124.— Maple.

Most species are grown from seeds sown one or two inches
deep. The seeds of the early ripening species will not*retain
their vitality until the following spring and, therefore, should
be sown as soon as possible after they fall from the tree. They
can also be grown from layers and by grafting. Some fancy
species and varieties are always propagated in this manner.

PEA FAMILY

This family includes herbs, shrubs, trees and vines; leaves
alternate and usually odd-pinnately compound, with stipules;

200

IMPORTANT FAMILIES OF PLANTS

flowers mostly irregular and often showy and papilionaceous
(i.e., butterfly-like) ; calyx four to five cleft; corolla usually of
five petals which may be united (as in the case of the clover)

or only partly united (as in
the pea) ; stamens unusu-
ally 10 with all the stamens
united (monadelplious^ or
nine united, and one free,
but forming a tube, enclos-
ing the pistil ; pistil one,
with one chamber fruit usu-
ally a legume or pod.

This is one of the most
important families, econom-
ically, to be found in the
plant kingdom. It contains
nearly four hundred and
fifty genera and more than
s.e v e n thousand species,
many of which are impor-
tant agricultural crops.
They include cultivated
crops used as food for man
and beast; forest trees and
ornamentals. The growing
of leguminous crops is also
recognized as one of the best
methods of improving the
soil.

Legumes Gather Nitrogen.— The use of legumes in the
improvement of soils depends upon the partnership (or symbi-
osis) existing between these plants and certain nitrogen-
gathering bacteria which make their homes on the roots (Fig.

FIG. 125. — Red clover plant with no-hiles
°n the roots, containing bacteria which enable
the plant to gather nitrogen from soil air. (t ights
of the Farmer.)

LEGUMES

125). The nodules seen on the roots are the homes of the bac-
teria. When the bacteria are present on the roots the plants
are enabled to gather nitrogen from the air. This power is
not found in other families of plants.

The relationship existing between the plants of the legume
family and the bacteria on the roots is a kind of partnership
(or symbiosis). The clover plant, for example, furnishes
homes for the bacteria and supplies them with nourishment.

FIG. 126. — Pod and seeds of lima bean.

In return for these benefits, the bacteria enable the clover plant
to gather nitrogen from the air and use it in its own growth.

Different kinds of bacteria are found to suit the different
legumes. The red clover bacteria do not thrive on alfalfa or
on beans. There are some forms of bacteria that are adapted
to several legumes. For example, those on alfalfa are also
found on sweet clover and on bur clover.

Legumes aid other crops grown in the same soil after
them. If clover or cowpeas, for example, are plowed under,

202 IMPORTANT FAMILIES OF PLANTS

the nitrogen which they have gathered and stored in their
leaves, stems and roots is added to the soil. This may soon be
changed to forms which corn, potatoes, or other crops may use
while growing in that soil.

Beans. — The term " bean " is applied to many plants of
this family; the broad bean (Vicia faba} is of Asiatic origin

Fio. 127.— Alfalfa and clover.

and is extensively grown in Europe for the feeding of live stock ;
the kidney bean (Phaseolus vulgwris) probably originated in
tropical America and is represented by many species and
varieties of garden and field beans which are so extensively
grown throughout the world; the Lima bean (P. lunatus} (Fig.
126) is a native of South America, the soy or soja bean
(Glycine hispida} is of Asiatic origin and is grown extensively
for stock feed ; the so-called cowpea or bean ( Vigna simensis) is

PEANUT 203

also grown extensively for the same purpose ; the scarlet runner
(P. multiftorus} is an interesting ornamental.

Peas. — The common garden pea (Pisum sativum) is well
known as one of our most valuable garden crops and is fre-
quently grown very extensively for canning.

Clovers. — The genus Trifolium includes about three hun-
dred species of clovers (Fig. 127), many of which are num-
bered among our most important agricultural crops.

The most important clovers are the red clover (Tn folium
pratense L.) the mammoth clover (T. medium}, the white
clover (T. repens}, the alsike or Swedish clover (T. hy-
bridum) and the crimson or scarlet clover (T. incarnatum).

The term clover is also often applied to other genera, such
asHhe alfalfa (Medicago sativa) (Fig. 127), the common yellow
clover or trefoil (M. lupulina}, the bur clover (M. denticulata} ,
the sweet clovers (Melilotus alba, M. offirinalis*) , the bush or
Japan clover (Lespedeza stria-ta}.

Peanut. — This family also includes the peanut (Arachis
hypogcea) (Fig. 128), licorice plant (Glycyrrhiza glabra), the
indigo plant (Indigofera tinctoria) and many other plants which
are valuable as forest trees, field crops, drug plants, etc.

The peanut has a peculiar habit of sending down a long
flower stem to thrust tne young seed into the mellow soil near
the roots. This occurs just after pollination. The pod develops
and ripens under ground. The crop is grown for forage as well
as for the peanuts themselves. There are chiefly two types of
peanuts- commercially grown for human use: the large Virginia
type and the small Spanish type. The latter is commonly used
in candies, for making peanut butter, and for extracting oil.

The garden and field crops are very generally grown from
the seeds, and the production of the commercial supply is a very
important industry. Great care should be exercised to guar-
antee seeds true to name and free from weed seeds.

204

IMPORTANT FAMILIES OF PLANTS
EOSE FAMILY (ROSACE2E)

This is the most important fruit producing family in the
plant kingdom. The flowers are perfect and regular. There

FIG. 128. — Peanut plant with the elongated stems sending seeds into the soil shown at

right arid left.

are usually five sepals, five petals and many stamens, but the
character of the ovary is extremely variable in the different
genera. The wild rose may be taken as a type ; it possesses the
above characters and has an inferior ovary.

PEACH

205

The apple (Pyrus malus) (Fig. 129) shows the same gen-
eral characters, but the ovary becomes fleshy and shows a division
into five well-developed parts. It probably originated in south-
western Asia and adjacent Europe and was used by the human
race in prehistoric times.

The pear (P. communis} and the quince (P. cydonia] are
very similar in character to the apple.

Fia. 129. — Apple, with section showing structure of seed cases.

The peach (Prunus persica) (Fig. 130) shows the same
general character of sepals, petals and stamens as the preceding,
but the ovary is superior and develops into a fleshy fruit with
a single hard-shelled seed. It is undoubtedly of Asiatic origin,
but was carried into Europe by the Greeks and Romans at a
very early date. It was introduced into Great Britain during
the sixteenth century and thence into America about 1680. It

206

IMPORTANT FAMILIES OF PLANTS

reaches its greatest perfection in China and in the United
States. The almonds (P. communis and P. nana) are closely
related to the peach ; and the nectarines are smooth-skinned vari-
eties of the peach.

Plums also belong to the genus Prunus (P. domestica —
Damson plum) and are also said to be of Asiatic origin, al-
though some botanists claim that they are indigenous to Europe.
The prunes of commerce are varieties of plums which are espe-

FIG. 130. — Peach, an example of the stone fruits. The plum and cherry are other examples.

cially well adapted to drying. There are also several species
of American plums.

Cherries also belong to the genus Prunus and are well known
in both Europe and America.

Raspberries, blackberries (Fig. 131) and dewberries belong
to the genus Rubus of the family Kosacese. In most cases there
are five petals and five sepals and many stamens as in the preced-
ing genera, but they differ from the preceding in having a num-
ber of ovaries which ripen into the well-known aggregate fruit.

POLLINATION OF STRAWBERRIES

207

In the blackberries and dewberries, the receptacle forms a part
of the fruit, but in the raspberries the ovaries are separated
from the receptacle.

Strawberries (Fig. 132.) belong to the genus Fragaria and
have flowers very similar to the members of the genus Rubus, but

Fio. 131, — Blackberry, a form of aggregate fruit.

fruit consists primarily of a large fleshy receptacle carrying
numerous naked akenes on its surface.

Pollination of Strawberries. — The flowers of some varieties
of strawberries have very little or no pollen. The two types
of blossoms, with and without stamens, are shown in Fig. 133.
Growers are unable to obtain fruit from the imperfect va-

208

IMPORTANT FAMILIES OF PLANTS

pieties (not having pollen) unless those with perfect flowers are
grown near them. The two* types may be planted together, with
at least one row of a perfect-flowered sort for three or four rows
of the imperfect ones, and these must be such as blossom at
the same season.

FIG. 132.— ^Strawberry.

The perfect-flowered varieties will produce fruit when
planted alone. They are more popular than the others. Two
varieties with imperfect flowers are Warfield and Ilaverland.
Crescent and Glen Mary bear very little pollen. Over fifty
perfect-flowered varieties are known. Some of these are Dun-
lap, Aroma, Gandy and Excelsior.

209

As the strawberry propagates itself by means of runners
which take root at the nodes, the varieties are easily kept pure.
The crossing of the pollen does not affect the character of the
fruit or the purity of the plants grown from the runners.

Poorly developed fruits, called " nubbins," are often the
result of poor pollination. This may be due to one of several
causes: (a) frost, (b) hail, (c) rain, (d) spattering of soil on
the pistils, (e) insufficient pollen oji varieties blooming late in
the season. Mulches of straw or other litter will prevent injury
from spattering soil during heavy storms. Growing several
varieties together will aid in supplying enough vigorous pollen
and cause better development
of the fruit.

Propagation. - - Apples,
pears, and quinces are poma-
ceous fruits and propagated
by growing stocks from seeds,

tli on Vmrlrlirifr inri or-d^fino- FIG. 133- — Flowers of strawberries.

ing Pistillate or imperfect at left. Perfect at

with the desired varieties. right <Productlve Farming.)
The seeds are obtained from the pomace of the cider mills. For
many years it was very generally believed that seeds and stocks
from France were better than the domestic supply, but in recent
years the sentiment has been changing and a very important
stock-growing industry has developed in Kansas, Nebraska,
Iowa and other states.

Blackberries, dewberries and raspberries are usually grown
from suckers and root cuttings. New varieties are grown
from seed.

Budding of Peaches and Plums. — The steps in the method
of shield-budding are shown in Fig. 134. The seeds are sprouted
in early spring after being mechanically cracked, or broken by
freezing in moist soil. Scions are cut from the current season's
growth in August and September, and the buds from these are
14

210

IMPORTANT FAMILIES OF PLANTS

inserted under the bark of the young seedlings right away.
These buds remain dormant until spring. When growth begins
the seedling top is pruned away, leaving only the shoot of the
good variety.

For June budding, dormant buds are gathered in late fall
and held until June in, wet sawdust in a cold cellar or in other
cold storage. The budding is done in June on seedlings started
in very early spring.

Root Grafting of Apples and Pears. — When trees are to be

FIG. 134. — Steps in budding the stems of seedlings with buds of good varieties. A,
the shield-shaped bud and parts cut from any good variety. B, a T-shaped cut made in
the bark of the seedling stem. C, the same with bark opened. D, the good bud set in
place under bark. E, the wound well wrapped and tied with raffia or waxed cotton.
(Productive Farming.)

propagated by root grafts (Fig. 135), .the tongue-grafting is
usually done in the winter. The seedlings of one season's
growth are dug in the fall after the leaves are off. They are
stored in small bundles in boxes of wet sawdust in a cold cellar.
The scions from the desired varieties are gathered about the
same time. They are labeled and stored in like manner. The
spare hours of winter are used for the work, which should be
done in a cool room or cellar. The materials and new grafts
must be kept moist and cool during the process. The grafts
are then stored in wet sand or sawdust in a cool cellar till dan-

GOURD FAMILY

211

ger of severe frost is over in the spring. They are then set in
rows in good garden soil. They are planted deep enough to
leave only one or two buds above ground. Here they arq grown
for a year or more before being transplanted to the orchard.

The peach, plum and cherry are drupaceous fruits and are
usually propagated by growing stock from seeds and then
budding or occasionally grafting. Plums are sometimes grown
from suckers.

SAXIFRAGE FAMILY (sAXIFRAGACE^E)

Herbs or shrubs with perfect, reg-
ular (occasionally irregular) flowers.
Calyx more or less united with the
ovary, four to five petals attached to
calyx, stamens same number as the
petals and alternate with them or two
to ten times as many. Ovary more or
less inferior. Fruit a two-chambered
capsule or true berry. Leaves alter-
nate or opposite or whorled.

Currant and Gooseberry. — The
common red currant (Ribes rubrum},
the black currants (R. floridum and
R. nigrum}, the gooseberries (R. grossularia and R. cynosbate),
the American gooseberry (R. liirtellum) and many species and
varieties of currants and gooseberries (Fig. 136) are valuable
fruits. They are extensively grown as garden fruits, but the
historical records are very imperfect and uncertain.

Gooseberries and currants are usually obtained from hard-
wood cuttings, but new varieties are grown from seed.

GOURD FAMILY (CUCURBITACE^)

This very important family has monoecious or dioecious, oc-
casionally perfect, usually solitary white or yellow flowers (Fig.

FIG. 135. — Steps in making the
tongue-graft used in root grafting
apples, pears, etc. A and B, root
and scion with tongue cut in each.
C, the two shoved together and
ready to be tied with waxed cotton.
(Productive Farming.)

212

IMPORTANT' FAMILIES OF PLANTS

FIG. 136. — Gooseberry.

FIG. 137. — Cucurbit blossom.

THE PUMPKIN, GOURD, AND SQUASH

213

137.) Calyx five-cleft and bell-shaped; corolla five-cleft and
bell- or wheel-shaped; stamens five, ovary inferior and one to
many chambered, developing into a many-seeded true berry
fruit. In many species the fruit is large and fleshy and edible.
Among the most important are:

The cucumber (Cucumis sativus), which is of Asiatic
origin and was cultivated about three thousand years before

Fid. 138. — Ribbed type of cantaloupe.

the Christian Era. The muskmelon or cantaloupe (C. melo)
(Fig. 138), is indigenous to Asia and possibly to Africa.
It was cultivated by the ancient Egyptians and was known to
the early Greeks and Komans. The watermelon (Citrullus
vulgaris) is a native of the torrid regions of Africa, but was
cultivated long before the Christian Era. It is now widely
distributed throughout the tropical and temperate zones.
The pumpkin, gourd, and squash — (Cucurbita melopepo)
flat squash, (C. verrucosa) warty or long-necked squash, (C.

214

maxima) winter or gourd squash, (C. pepo) pumpkin — are
well-known products of both tropical and temperate climates.
The pumpkin is supposed to be of American origin.

FIG. 139. — The long form of carrot.

The members of this family are very generally grown from
seed and are widely distributed throughout the temperate and
tropical" climates. The growing of cucumbers under glass has

COFFEE AND QUININE 215

developed into an important industry near many of our large
cities. The weed members of this family are of no very great
importance.

PAESLEY FAMILY (UMBELLIFEE^E)

The family is characterized by five-parted calyx and cor-
olla; two-chambered inferior ovary and umbel inflorescence.
Among the most important members are : The celery (Apium
graveolens), which is well known. It was used as food by the
,, ancient Egyptians, Greeks and Romans and. also as a medicine
by the Egyptians. The parsnip (Pastinaca sativa) originated
in Europe but is now widely cultivated as a food for man and
live stock. The carrot (Daucus carota) (Fig. 139) is a vege-
table whose history is not known.

This family also includes the anise (Pimpinella anisum) ;
asafoetida (Ferula narthex] ; coriander (Coriandrum sativum) ;
parsley (Carum petroselinum) ; caraway (Carum carui) ; and
many other more or less well-known plants, some of which are
useful while others are pests.

The members of this family are grown from the seed. Cel-
ery, parsnips and carrots may be kept in storage for consider-
able time. This family also includes a number of weeds which
can be kept in control by the use of cultivated crops and also
by the use of cowpeas, soy beans or similar smother crops.

MADDER FAMILY (EUBIACE^E)

Coffee and Quinine. — This family includes the coffee
(Coffea arabica and C. liberica), the quinine plant (Cinchona
officinalis) and other plants with interesting histories. (Read
the history of these plants in an encyclopedia.)

216

IMPORTANT FAMILIES OF PLANTS

SUNFLOWER OK COMPOSITE FAMILY ( COMPOSITE)

This is one of the largest families of the flowering plants.
It is characterized by numerous small flowers growing in a close
head. These flowers are either polygamous or monoecious. The
ovary is inferior and the calyx tube is attached to it ; the corolla
is five cleft, either tubular or strap-shaped ; stamens five, attach-
ed to corolla; anthers united into a tube surrounding the two-
cleft style. In most plants the central or disk flowers arc

Fio. 140. — Sunflower, showing the composite flower head.

tubular and the marginal flower strap-shaped, but in some
plants all of the flowers are of the same kind.

This family includes some few plants used for food, such
as the Jerusalem artichoke (Helianthus tuberosus L.), lettuce
(Lactuca sativa}, some few others that are used in medicines,
and a large number that are used for ornamental purposes,
such as the sunflower (Helianthus annuus} (Fig. 140), the
daisy and chrysanthemum (Chrysanthemum carineum}, gold-
enrods (Solidagos}, asters, dahlias and others.

BLUEBERRY, HUCKLEBERRY AND CRANBERRY

JIT

This family also includes the dandelion (Taraxacum
officinale), iron* weed (Vernonia), fleabane and meadow white
top (Erigeron), thistle (Carduus), and many others that are
troublesome as weeds.

HEATH FAMILY

The flowers of this very interesting family are four to five
parted ; calyx attached to am inferior ovary, the petals united ;

FIG. 141. — Cranberries.

stamens eight to ten ; ovary of several chambers and developing
into a true berry.

Blueberry, Huckleberry and Cranberry. — The most im-
portant plants of this family are the blueberries and huckleber-
ries (Gayhissacia} and the cranberries (Oxy coccus) (Fig.
141), both of which are indigenous to America.

Cranberiy-growing is a highly specialized industry which is

218 IMPORTANT FAMILIES OF PLANTS

restricted to very limited, parts of the country. The conditions
for success in this line of farming are to be found in very few
parts of the country. Old peat bogs with an ample supply of
water are essential.

CONVOLVULUS FAMILY (CONVOLVULACE^E)

The flowers of this family are perfect and terminal; calyx
five-cleft and persistent; corolla, funnel-shaped and five-cleft;
stamens five and attached to the corolla. The family contains
a large number of ornamental plants of which the morning
glory is typical. Many of these plants are so common as to
be weed pests.

Sweet Potato. — The most important economic member of
this family is the sweet potato (Ipomoea batatas}. Some au-
thorities claim that this .plant is Asiatic, while others claim
that it is American. It may possibly be indigenous to both
continents. It reaches its greatest development in the tropidal
countries, where it makes a very luxuriant growth and blooms
freely, but it is extensively cultivated in the sandy districts
of the temperate zones. Certain varieties are cultivated un-
der the name of yams, but the true yam belongs to the family
Dioscoreacece.

Propagation. — In the temperate zone, sweet potato plants
are grown from roots which are laid in hot-beds, cold-frames
or forcing houses, dependent upon the climatic conditions. The
plants are then transferred to the field and are most productive
in sandy soil. In tropical countries, the crops are usually grown
from cuttings set directly in the field. This family includes
a number of very troublesome weeds, which are difficult to
eradicate except by the use of cowpeas, soy beans or similar
smother crops.

This family also includes the dodder or love vine, which
we find growing parasitically on many of our flowering plants.

POTATO

219

The seeds germinate in the soil, but the vine very soon attaches
itself to another plant and loses its connection with the soil,
thus becoming strictly parasitic. Some of the dodders are very
troublesome weeds.

NIGHTSHADE FAMILY ( SOLAN ACE^l)

This is one of the most important families in the plant king-
dom. The calyx is five-cleft (occasionally four or six)" and

»

FIG. 142. — Blossom of egg-plant. Note its similarity to the Irish potato blossom.

persistent ; corolla five-cleft (sometimes so deeply that the petals
appear to be distinct) ; stamens five and attached to the corolla ;
ovary two- to five-chambered and with many ovules. (Fig. 142.)
Fruit varying from a dry pod to a true fleshy berry. The most
important members of this family are :

The potato (Solatium tuberosum) is indigenous to Chile,
Peru and Equador, where it was found growing by the early
Spanish explorers. It is now widely distributed throughout
the world and is one of our most important food products. The
wild potatoes produce small tubers and many seeds, but careful

220

IMPORTANT FAMILIES OF PLANTS

selection has given us many varieties with large tubers and few
or no seeds.

The tomato (Lycopersipum esciilentum) (Fig. 143) is a
native of Central and South America and is said to have been
cultivated by the ancient inhabitants of Mexico. Its uses are
well known.

The pepper (Capsicum annuiim) (Fig. 144) (red pepper.

FIG. 143. — Tomatoes.

C. fastiyiaium and C. fructescens, Cayenne pepper, and C.
yrossum, bell pepper) is also indigenous to tropical and sub-
tropical America. The uses are well known.

Tobacco (Nicotiana tabacum) is another well-known Amer-
ican plant which is now cultivated in many parts of the world.

This family also includes the deadly nightshade (Atropa
belladonna} from which certain important drugs are obtained,
the common black nightshade (Solatium mgrum), and many
Other interesting plants.

GOOSEFOOT FAMILY

221

Propagation. — It is well known that the potato is grown
from the tubers, but the other cultivated members of this fam-
ily are very generally grown from seeds. The seedlings are read-

FIG. 144. — The sweet pepper.

ily transplanted.' This family also contains a few troublesome
weeds which can usually be controlled by smother crops.

GOOSEFOOT FAMILY (CITENOPODIACE^E)

The members of this family are very widely distributed.
They are mostly herbaceous with alternate leaves ; flowers small,
greenish, in spikes or beads, usually regular ; no corolla ; calyx

222

IMPORTANT FAMILIES OF PLANTS

three to five lobed (rarely one or no sepals) ; stamens as many
as lobes of calyx or fewer; pistil one with one chamber; fruit
one-seeded in a loose bladdery capsule or utricle.

Beets, Spinach and Swiss Chard. — This family includes
the common beet (Beta vulgaris) (Fig. 145), which is indigen-
ous to both Europe and Asia and was used for five hundred

years or more before the
Christian Era. Some varie-
ties are extensively used as a
table vegetable, others for
stock feed and still others for
the manufacture of sugar.
The spinach is an Asiatic
plant which has been culti-
vated and used from un-
known time. The Swiss
chard, which is so extensively
used as a salad, is a variety
of the common beet.

BUCKWHEAT FAMILY
(POLYGONACEJE)

Buckwheat. — This fam-
ily includes the buckwheat
(Fagopyrum esculentum]
(Fig. 146), an Asiatic plant
which is well known. It was at one time known as beech wheat,
owing to the resemblance of the seed to that of the beech, but
this was gradually modified to " buckwheat."

Rhubarb. — This family also includes the well-known vege-
table, rhubarb or pie-plant (Rheum rhaponticum) , which is of
East European or West Asiatic origin.

Buckwheat is grown from seed. Rhubarb may be grown

FIG. 145.— The table beet.

MULBERRY

223

from the seed, but will not come true to type and requires
three years to come to maturity. It is much better to secure new
plants by dividing the crowns. This family includes many
important weeds; among the most troublesome is the sorrel,
which grows in great abundance in sour (acid) soil. It can

FIG. 146.— Buckwheat.

be eradicated by heavy applications of lime and the use of
legume crops. The docks are also members of this family.

NETTLE FAMILY (iJRTICACEyE)

This family contains herbs, shrubs and trees and includes
some very important plants. Flowers monoecious, dioecious or
rarely with perfect flowers; calyx regular; stamens as many
as the tubes of the calyx or fewer and opposite them; pistil
one with two cells.

The mulberry (Morus rubra, American red mulberry, and
M. alba, Asiatic white mulberry) is well known. The flowers

224

IMPORTANT FAMILIES OF PLANTS

are unisexual and the plants are usually monoecious. Both
male and female flowers are borne on short spikes and have a
four-parted perianth or calyx. The white mulberry was intro-
duced into Europe about the middle of the fifteenth century,
into Mexico by Cortez in 1522 and into Virginia by James I

Fio. 147.— Fig.

in 1619. It is extensively grown in China for the feeding of the
silk worm. The American mulberry produces a very good fruit
and the wood is very durable and serviceable for many piirposes.
The elms (Ulmus Americana, American or white elm;
U. fulva, slippery or red elm; U. racemosa, corky elm) are
among our most valuable shade and ornamental trees.

HICKORIES 225

The common hop (Humulus /w/m/us) is well known. It
is used in making yeast, beer and medicine.

Fig and Rubber. — The genus Ficus includes the common
fig (Ficus carica) (Fig. 147), the India rubber tree (F. elas-
iica~] and the banyan tree (F. bengalensis) .

The hemp (Cannabis sativa) also belongs to this family.

Propagation. — The mulberry is usually grown from root
cuttings, or from layerings, or by budding. New varieties are
obtained from seeds. The elms are usually grown from seeds
which mature very early in the spring and are sown at once,
but may also be grown by layering or by grafting. Hops may
be grown from seeds, from divisions or from hard wood cut-
tings. Hemp is grown from seed and is one of the very im-
portant fibre plants.

WALNUT FAMILY (jUGLANDAGEJi)

This very important family contains two valuable groups of
trees, the walnut and the hickory. The flowers are monoecious.
The staminate flowers are usually borne in catkins and each
consists of a six-lobed (occasionally two- or three-lobed) peri-
anth and from six to forty stamens. The pistillate flowers are
terminal and may bo solitary, few or clustered; the calyx tube
is four-toothed and styles two in number. The fruit is a dru-
paceous nut.

Walnuts. — The American black walnut (Juglans nigra) is
well known both for the nuts and for the high quality of the
wood. The American butter-nut (/. cinerea) produces an ex-
cellent nut, but the wood is not so valuable as that of the black
walnut. The so-called English walnut (/. regia*}, which is now
extensively cultivated in many parts of the world, is of Asiatic
origin. It is of great value both for nuts and lumber.

Hickories. — The various species of hickory (Hicoria ovata,,
15

226

IMPORTANT FAMILIES OF PLANTS

shell bark, and H. olivceformis, H. pecan, the pecan of com-
merce) are well known for their nuts and useful woods.

Propagation. — The members of this family can be grown
from seeds or by grafting. The fact that seedlings are subject
to more or less variation makes it necessary to perpetuate de-
sirable varieties by grafting, which must be done with consid-
erable care in order to be successful.

Fia. 148. — Pecan nuts, showing one of tho many forms grown for market. (U. S. D. A.)

OAK FAMILY

This family is similar to the preceding. The flowers are
monoecious. The staminate flowers in catkins, calyx five-parted
(occasionally five to twelve), stamens two to twenty. The pis-
tillate flowers terminal, six-parted, and attached to the two- to
seven-chambered ovary. Fruit a one-seeded nut. This family
includes the oaks, chestnut, hazelnuts, beech, and others.

There are many species of oaks (Quercus} which are among

BANANA FAMILY

227

the most important of our forest trees. The hazelnuts (Cory-
ZMS) and the chestnuts (Costarica') are highly prized for their
edible nuts.

Feed for Swine. — The nuts of the trees of this family and
the preceding one are abundantly used in feeding swine. The
animals are allowed to gather the acorns and nuts (called mast)
from the ground under the trees, during the fall and winter days
when there is no snow on the ground. The flesh produced from
'mast is often of good quality, and the economy of its produc-
tion is readily understood. Beechnuts
alone produce a soft flesh, and some
corn or other grain is fed for a few
weeks before slaughtering.

WILLOW FAMILY ( SALIC ACE^E)

In this family, both the staminate
and pistillate flowers are borne in cat-
kins. It includes the willows (Salix),
the poplars, and the cottonwoods
(Populus}.

All members of this family grow FIG. 149.— Bur of native chest-

nut showing two seeds within. ("Pro-

readily from cuttings and can be ductive Plant Husbandry.")
grown from grafts: The poplars and cottonwoods are frequently
grown from seed.

BANANA FAMILY (ziNGIBREACE^E)

This very important family includes a number of inter-
esting families of which the banana of commerce (Musca para-
disiaca) is an example. Another species of the banana (M.
textilis) produces a fibre from which the Manila hemp is
manufactured.

The edible bananas are grown from suckers, but the fibre
varieties are grown from seeds.

228 IMPORTANT FAMILIES OF PLANTS

LILY FAMILY

This very large and interesting family contains many valu-
able plants. The flowers are perfect, usually terminal and
solitary but occasionally in racemes or spikes. The perianth
is more or less tubular and six-parted or united into six lobes;
six stamens and a three-chambered, many-seeded superior
ovary.

Lily, Asparagus, Onion. — This family may be character-
ized by the many species of lilies which grow wild or are culti-
vated for ornamental purposes.

Among other important vegetable plants of this family are
the asparagus {Asparagus officinalis) and the onion (Allium
cepa and 'A. fislulosum). Among the ornamental plants arc
the many true lilies, tulips, hyacinths, lilies of the valley, etc.

Some Bad Weeds. — ^Jhe family includes a large number
of uncultivated plants, some of which are troublesome weeds.
Among the most important of .these weeds are the wild onions,
or wild garlic, which frequently becomes established in old pas-
tures and gives a peculiar odor to milk and butter from cows
that feed on it. It is very difficult to eradicate, but can be
done by shallow plowing just deep, enough to expose the bulbs
to the sun, followed by the growing of well-cultivated crops.

Propagation. — The asparagus is usually grown from seed,
but old crowns are sometimes divided. Onions are grown from
seeds, sets and bulbs. The ornamentals are usually grown from
bulbs or seeds.

GRASS FAMILY (GRAMINE^E)

Annuals or perennials, frequently with fibrous or creeping
rhizomes and often stoloniferous at the lower nodes. Flowers
perfect (occasionally monoecious or dioecious or polygamous)
and borne in spikelets which are collected into spikes or panicles.
Perianth imperfect (occasionally wanting) membranous or
fleshy. Stamens three or six (occasionally four, two or one).

WHEAT

229

sur-

Ovary superior with one chamber and one ovule and
mounted by two (occasionally three) styles. Stems cylindrical
(occasionally flattened), tubular (occasionally hollow). Leaves
alternate, in two ranks, springing from the nodes, petioles
sheathing the stems. This very large family contains our grains
and grasses (Fig. 55).

Wheat (Triticum vulgare and varieties) is the well-known

Fin. loO. — Six types of wheat. Top row, durum, Polish wheat, and white winter. Bottom
row, red winter, hard winter, and hard spring. ("Productive Farm Crops.")

bread plant of the temperate zones. The spikelets bearing
from two to many flowers are arranged in a firm spike. The
little flowers are arranged in two rows and protected by glumes
which sometimes bear awns or bristles; three stamens and two
plum-like stigmas. The fruits (L e., grain enclosed in ovary
coats) are about one-quarter of an inch in length, oval, flattened
and grooved on one side. Some varieties are sowed in the early

230 IMPORTANT FAMILIES OF PLANTS

spring and harvested during" the summer and' known as " spring
wheat." Other varieties are sowed in the fall and harvested
the following July and known as " winter wheat." Wheat
probably originated in western Asia and was cultivated long
before we have any authentic historical records. (Fig. 150.)

Rye (Secale cereal e) is very similar to wheat and is used as
food for both man and beast. We have no satisfactory records
telling us where it was first cultivated by mankind. (Fig. 56.)

Barley (Hordeum vulgar e, H. distichum, H. hexastichon
and H. Zeocriton) is also similar to wheat and is also used for
man and beast. Its cultivation probably antedates historical
records.

Oats (A vena saliva} have the two- to five-flowered spike-
lets borne in panicles. The glumes are membranous and with-
out awns ; three stamens and two stigmas. Annuals which are
sowed in the spring and harvested in July or August. Its geo-
graphic^l range is not so great as most of the other cereals ; it
grows well in cold regions and rather poorly in warm countries.
It probably originated in western Asia and eastern Europe,
but we have no very satisfactory records of its early cultiva-
tion and uses. Although it is less nutritive than wheat or rye
it is very extensively used as food for man and beast.

Millet (Setaria italica) is an Asiatic plant cultivated many
centuries before the Christian Era. It 'is very widely but not
extensively grown through many temperate and tropical coun-
tries. It is very inferior to oats and many other forage crops
which can be grown with no greater expense of time and labor.

Rice (Oryza sativa and other species) is an important trop-
ical and subtropical plant growing in low, wet lands. We have
no definite records telling us when it first became the food of
man, but it was cultivated for at least 2800 years before the
Christian Era and has probably contributed more food to the
human race than any other food plant.

CORN 231

Corn (Zea Mays) (Fig. 151) is not typical of the grass
family; the stem is solid and the flower is imperfect and mo-
noecious. The staminate flowers are borne in two-flowered spike-
lets which are in turn borne on the long spikes constituting the
tassel; the pistillate flowers are borne on a large spike (cob),
each having a long, delicate, thread-like pistil (silk) and the
entire ear enclosed in the large bracts (husks). The fruit

FIG. 151. — Corn showing both pistillate and staminate flowers.

consists of the grain inclosed in the ovary ; many of these fruits
are arranged in rows on the cob and constitute the ear. This
very important plant undoubtedly originated in America and
was first introduced into Europe by Columbus in 1520. It is
now extensively cultivated in temperate and tropical countries.
There are a great many varieties of corn, but they are usu-
ally classified in six groups as follows: (1) the pod corns, in
which each grain has a peculiar shuck covering, (2) the pop

232 IMPORTANT FAMILIES OF PLANTS

corns, (3) the Hiiit corns, (-i) the dent corns, (5) the soft corns,
and (6) the sugar corns.

Sugar cane (Saccharum officinarum) is the well-known
tropical and subtropical plant from which the greater part of
our sugar of commerce is derived. It is an Asiatic plant, but
there are no satisfactory records concerning its early
cultivation.

Broom Corn (Sorghum saccharatum) . — This is an African
plant which is grown in the United States for the manufacture
of brooms and for stock feed.

QUESTIONS

1. What are the distinguishing characters of the families Orucifera?,
Leguminoseae, Rosaceae, Cucurbitaceae, Convolvulaceip, Solanacea1, Juglan-
daceae, Cupulifera, Solanaoea1, Liliaceae and Graminaca?.

2. (a) Make a list of grain-producing plants.
(6) Give the origin of each.

(c) Give the present range of each.

(d) Give the uses of each.

(e) Give the valuation of each.

3. (a) Make a list of ths fibre-producing plants.
(6) Give the origin of each.

(c) Give the present range of each.

(d) Give the usea of each.

(e) Give the valuation of each.

4. (a) Make a list of the fruit-producing plants.
(6) Give the origin of each.

(c) Give the present range of each.

(d) Give the uses of each.

(e) Give the valuation of each.

5. (a) Make a list of vegetable plants.
(6) Give the origin of each.

(c) Give the present range of each.

(d) Give the uses of each.

(e) Give the valuation of each.

6. (a) Make a list of lumber trees.
(&) Give the origin of each.

(c) Give the present range of each.

(d) Give the uses of each.

(e) Give the valuation of each.

QUESTIONS 233

7. Make a listl of agricultural plants which are of American origin.
Tell something about their present range and uses.

8. Give an example of symbiosis.

9. Tell how legumes improve soils.

10. Describe the propagation of the apple by root grafting.

11. Describe the budding of peaches and plums.

12. How and when are stocks and scions grown, gathered, stored,
and used?

13. What are some of the pollination problems with strawberries?

14. Mention the different types of cabbages; of turnips.

15. Describe the peculiar seed-bearing habits of the peanut plant;

SPECIAL EXERCISES WITH IMPORTANT FAMILIES
OF PLANTS

NOTE TO THE TEACHER. — This outline is intended to be
very brief and to serve as an outline for further reading in
various books which should be in the study-room or laboratory.
The exercises are also brief and may be expanded as circum-
stances may demand. They may be taken in any order to suit
the convenience of the teacher. Other exercises may be added
to the list or substituted.

1. The Lily and Its Relatives. — Dissect and study the
flower of the lily. Make a series of drawings to show the shapes
of the parts and relations one to another.

Study flower of amarillis, iris, onion and other similar
plants and compare with the lily.

2. Mustard or Radish. — Select a mustard, radish or any
other cruciferous plant in full bloom. Note the differences in
the leaves, in the different parts of the plant from base to tips.
Make drawings of a few typical specimens.

Dissect the flower, make drawings of the different parts and
a diagram showing the number and arrangement of the parts.
The character of the ovary can be best studied from seed pods
near maturity.

Examine the seeds and make drawings.

Examine the roots and make drawings. Compare with
the roots of other cruciferous plants.

How long from seed planting to maturity of a new crop
of seeds ? Is this the same for all crucifers ?

Make a list of food plants belonging to this family. Make
a list of native weeds, belonging to this family.

3. Maple. — The flowers of the maple open very early ; some
234

OAK, HICKORY OR WALNUT 235

of them are in bloom long before the snow and ice have
disappeared.

Study the flowers carefully, using a small hand lens. Make
drawings and diagrams showing the shape a,nd arrangement of
parts.

Examine flowers from different trees. Do they all show
both stamens and pistils ? Make a record of the date of the
blooming and of the appearance of the leaves.

Follow the development of the seeds throughout the season.

Make drawings and measurements of the leaves and seeds
from time to time until maturity.

Make a list of the maples in the vicinity. tyLake a list of
their uses.

4. Gooseberry or Currant. — Dissect the flowers of one or
both and make drawings to show the shape and arrangement
of the parts.

Make drawings of fruits. Tell what parts of the flower go
to form the fruit.

5. Cucurbits. — Examine the flowers of cucumber, melon or
pumpkins. Make drawings of parts and diagrams to show the
arrangements.

What parts go to make up the fruits ?

G. Composite. — Study one or more composite flowers such
as daisy, sunflower, or dandelion. Note the inflorescence or
arrangement of the flowers in the head.

Examine flowers from the margin and centre of the head.
Make series of drawings and diagrams to show parts and ar-
rangement of the individual flower.

Make list of useful composite plants.

Make' list of weeds belonging to Composite.

7. Oak, Hickory or Walnut. — Collect, examine and make
drawings of both staminate and pistillate flowers.

Compare with willow.

236 SPECIAL EXERCISES

8. Willow. — Collect, examine and make drawings of both
staminate and pistillate flowers. Compare with oak or hickory
or walnut.

9. Corn Kernel. — Select good grains of several different
kinds of corn, such as flint, soft, pop, and sweet corn.

Make drawings and write descriptions of each. (Fig. 1.)

Soak the grains in hot water for 15 minutes. Cut each
grain longitudinally and note the following: hull, endosperm
(hard and soft starch), germ (scutellum, plumule, radicle) tip
cap. (Figs. 1 and 4.)

Compare, make drawings and write descriptions of each.

Cut another lot of grains in cross' section ; make drawings
and write descriptions.

Write a brief discussion of the uses and value of each of
the varieties used.

10. Corn Seedling. — Germinate a few grains of corn be-
tween layers of wet filter paper.

Examine newly germinated seed and others that have been
germinated for several days. Note the plumule, radicle, pri-
mary and secondary roots and root-hairs. Make drawings and
write descriptions. (Fig. 4.)

Carefully lift seedlings that have been growing in fine,
moist soil. Why does the soil cling to the roots ? Wash gently
and examine the root system.

What does the plant obtain from the soil ?

11. Large Corn Plant. — Examine a full-sized corn plant.
Note the nodes and internodes. How many rows of leaves?
Where are they attached ?

Note the sheath and blade of the leaf. Is the leaf parallel-
veined or net-veined ?

Note the brace roots near the base of the plant.

Where is the ear borne ?

What part is borne at the top of the plant ?

BEAN OR PEA 237

Cut the stalk ; examine and describe its structure.

12. Corn Flowers. — Where are the corn flowers located?
Make a drawing of the tassel. Make a drawing showing one
pair of spikelets in place. Separate the parts of a pair of
spikelets. Make drawings of parts and drawing to show their
position.

Make a drawing of a young ear in silk. The husks are bracts.
Remove the husks from one side. Make drawing and show the
relation of the silk to the grains.

Each grain is a single flower. What do the grains and
silks correspond to in other flowers ?

Explain pollination in the corn flower.

13. Wheat Kernel and Its Germination. — Examine a grain
of wheat and compare it with a grain of corn.

Make germination studies the same as in corn.

14. Wheat Plant and Flower. — Compare a stalk of wheat
with a stalk of corn.

Where are the flowers located ? Make a drawing of a head
of wheat. Remove a number of spikelets and make a drawing
to show their attachment. Dissect a spikelet and show the fol-
lowing parts: Glumes, palea, stamens, ovary and stigmas.
Make drawings of each part and drawing to show their relation
to each other.

15. Oats. — Repeat the preceding exercise, using oats in-
stead of wheat.

16. Bean or Pea. — Make a drawing of the leaf and label
all parts. If the plant is a climber explain! method of climbing.

Dissect the flower. How many sepals ? Make drawings.
(Fig. 47.)'

Note that there is one large petal or standard, two smaller
petals or laterals and two others which form the keel. Make
drawings of each and diagram to show the arrangement.

How many stamens and what is their arrangement? Make
drawing.

238 SPECIAL EXERCISES

How many pistils ? Make drawing and show the parts.
What is its relation to the stamens ?

Make drawing of pod, showing both outside and inside.
(Fig. 47.)

17. Bean and Pea. — Examine as many other beans and
peas as circumstances will permit. Compare the leaves,
method of climbing, flowers and seed pods.

18. Bean and Pea Seedlings. — Eeview your studies on the
bean.

Plant a number of beans and peas. Note the methods of
germination and compare the seedlings from time to time for
a period of two or three weeks. Make drawings.

19. Purity Test for Clover Seeds. — Collect a number of
samples of clover seeds. One ounce of each is sufficient.

Weigh out two or three grains of each very carefully. (Be
sure to use an accurate set of balances such as you will find in
the physical and chemical laboratories.)

Spread this sample on a sheet of white paper. Examine
through a large lens or reading glass and remove (1) weed
seeds, (2) grass and other varieties of clover seed, (3) dirt and
other inert material. Weigh, and make and fill the following
table in your note-book.

Name of Pupil

No. of sample Kind of Seed

Weight of Pure Seed Per cent of pure seed

Weight of other clover and grass Per cent of other clover and grass

seed seed

Weight of weed seeds Per cent of weed seed

Weight of inert material Per cent of inert material

Total weight

20. Germination of Commercial Seeds.— Count 100, 200,
300, 400, or 500 seeds from preceding exercise. Germinate
these seeds between sheets of wet blotting paper.

PEPPER AND EGG-PLANTS 239

21. Weed Seeds. — How many kinds of weed seeds did you
find in the sample used in exercise for purity of clover? Do
you know all the kinds \

Heat a quantity of soil long enough, to kill all seeds in it.
If you are in doubt, keep the soil wet, and in a warm place
for a week. If any growth appears, heat it a second time.
Plant your weed seeds in this soil and see if you can recognize
the little plants.

22. Grasses. — Repeat the preceding exercise for grasses.

23. Potato or Tomato. — Describe the plant. Make a
drawing of the leaf. How are the leaves arranged on the stem ?
Where are the flowers located ? Are they single or in groups ?

Make drawing or diagram showing location of flowers and
character of inflorescence. Dissect a flower and make draw-
ings of parts.

How many sepals ? How many petals ? How many sta-
mens ? How many pistils ! Is it gamo- or poly-sepalous ? Is
it gamo- or poly-petalous ?

24. Tomato Fruit. — Examine a few good tomato fruits.
Can you find the calyx ?

Can you find the corolla ?

From what part of the flower is the fruit developed ?
Do potatoes form the corresponding part of the flower?
Why?

How many seeds in a single tomato ?

25. Potato Tuber. — Examine a potato tuber. Is the tuber
a root or a stem ?

What are the eyes of the potato tuber ?

Cut a potato tuber so that some of the pieces will have eyes
and others not. Plant and watch for germination. Will they
all grow ? From what part of the piece do the sprouts arise ?

26. Pepper and egg-plants may be studied in the same man-
ner as indicated in the exercise with tomato fruit.

240 SPECIAL EXERCISES

27. Apple, Pear or Quince. — Examine an apple or pear
blossom. How many sepals f. How many petals '{ How many
stamens \ How many pistils '( Is it gaino- or poly-sepalous '(
Is it gamo- or poly-petalous ? How are the parts attached ?
What is the position of the ovary ?

28. Peach, Plum or Cherry. — Use the same outline as in the
preceding exercise.

29. Apple, Pear or Quince Fruits. — From what parts of
the flower is the apple, pear or quince developed \

Make a drawing of the fruit.

Cut a fruit lengthwise, make drawing and label all parts.
Cut a fruit in cross section, make drawing and label all
parts.

30. Peach, Plum or Cherry Fruits. — Use same outline as
in the preceding exercise.

31. Blackberry or Raspberry. — Compare the blossom of a
blackberry or raspberry with the blossom of the apple or peach.
How does it resemble and how does it differ from the blossom of
the apple or peach ?

Make a series of drawings showing characters of the flowers.
Examine a berry. From what, part or parts of the flower is
the fruit developed '{ Make a series of drawings.

32. Strawberry. — Use same outline as in the preceding
exercise.

33. Morning Glory. — Dissect the flower of the morning
glory. How many sepals? How many petals? How many
stamens ? How many pistils ? To what are the various parts
attached ?

Is the flower gamo- or poly-sepalous ? Is the flower gamo-
or poly-petalous ?

34. Sweet Potato. — The sweet potato belongs to the same
family as the morning glory and the flowers are almost the
same. The sweet potato produces an abundance of blossom?

COTTON 241

in the tropical countries, bujt in the temperate climates it sel-
dom produces blossoms.

Is the edible part a root or a stem ? Compare it with the
edible part of the white or Irish potato ?

35. Cotton. — A hollyhock may be substituted in sections
where the cotton is not grown. Study the plant. Note its
shape, length of internodes, long vegetative and short flower
branches of the plant. How many flowers and fruits has it I

Study the flower, and make a series of drawings to show
parts.

Make a study of the boll of the cotton or seed-pod of the
hollyhock. -

REFERENCES

Atkinson, G. F. : ( 1 ) Elementary Botany. New York : Henry Holt &
Co., 1898, $1.25.

(2) Lessons in Botany. New York: Henry Holt & Co., 1900, $1.12.

(3) Mushrooms, Edible, Poisonous, etc. New York: Henry Holt &

Co., 1903, $3.00.

(4) First Studies of Plant Life. Boston: Ginn & Co., 1901, $1.00.

(5) A College Text Book of Botany. New York: Henry Holt & Co.,

1905, $2.00.

Bailey, L. H.: (1) The Survival of the Unlike. New York: The Macmil-
lan Co., 1896 and later, $2.00.

(2) Lessons with Plants. New York: The Macmillan Co., 1898, $1.10.

(3) Plant Breeding. New York: The Macmillan Co., 1895 and later,

$1.25.

(4) Botany, an Elementary Text for Schools. New York: The Mac-

millan Co., 1900 and later, $1.10.

(5) Beginner's Botany. New York: The Macmillan Co., 1909, 60

cents.

Bailey, L. H. ( Editor ) : ( 1 ) Standard Cyclopedia of Horticulture. New
York: The Macmillan Co., 6 vols., 1914-1916, and later issues,
$30.00.

(2) Cyclopedia of American Agriculture, New York: The Mac-
millan Co., 4 vols., 1907-1909, $20.00.

Bailey, L. H., and Coleman, W. M. : First Course in Biology. New
York: The Macmillan Co., 1908, $1.25.

Bailey, W. W. : Botanizing. Providence: Preston & Rounds Co., 1907,
$1.00.

Barnes, C. R. : ( 1 ) Plant Life, Considered with Special Reference to
Form and Function. New York: Henry Holt & Co., 1898, $1.12.
(2) Outlines of Plant Life, with Special Reference to Form and Func-
tion. New York: Henry Holt & Co., 1900, $1.00.

Beal, W. J.: Seed Dispersal. Boston: Ginn & Co., 1898 and later, 60
cents.

Bergen, J. Y.: (1) Elements of Botany. Boston: Ginn & Co., 1896 and

later, $1.00. (Also with a brief Flora, $1.30.)

(2) Foundations of Botany. Boston: Ginn & Co., 1896 and later,
$1.30. (Also with a brief Flora, $1.50. A handbook for teach-
ers is supplied, 30 cents.)
242

APPENDIX 243

(3) Essentials of Botany. Boston: Ginn & Co., 1909, $1.20. (Also

with a brief Flora, $1.50.)

Bergen, J. Y., and Caldwell, O. W. : Practical Botany. Boston: Ginn & Co.
Bergen, J. Y., and Davis, B. M.: (1) Principles of Botany. Boston:

Ginn & Co., 1906, $1.50.
(2) Laboratory and Field Manual of Botany (to accompany the

preceding). Boston: Ginn & Co., 1907, 90 cents.
Bessey, C. E.: Botany for High Schools and Colleges. New York: Henry

Holt & Co., 1880 and later editions, $2.20.

Britton, N. L.: (1) Manual of the Flora of the Northern States and Can-
ada. New York: Henry Holt & Co., 1901, $2.25.
(2) North American Trees, being Descriptions and Illustrations

of the Trees Growing Independently of Cultivation in North

America, North of Mexico, and /the West Indies. New York:

Henry Holt & Co., 1908, $7.00.

Britton, N. L., and Brown, A.: An illustrated Flora of ) the Northern
United States, Canada, etc. New York: Charles Scribner's Sons,

3 vols., 1896-1898, $4.00 a volume.
Caldwell, O. W. : Laboratory Manual of Botany. New York: D. Appleton

& Co., 1902, 60 cents.
Campbell, D. H. : (4) A University Text Book of Botany. New York:

The Macmillan Co., 1902, $4.00.
Clark, C. H. : A Laboratory Manual of Practical Botany. New York:

American Book Company, 1898, 96 cents.
Clute, W. N. : ( 1 ) Our Ferns in Their Haunts, a Guide to all the Native

Species. New York: F. A. Stokes Co., 1901, $2.00.
(2) The Fern Allies of North America, North of Mexico. New York:

F. A. Stokes Co., 1905, $2.00.
Collins, F. S.: Green Algae of the United StateaL Tufts College Studies,

1909, $3.50.
Conn, H. W.: Bacteria, Yeasts, and Molds in the Home. Boston: Ginn

& Co., 1903, $1.20.
Coulter, J. M. : ( 1 ) Manual of the Botany of the Rocky Mountain Region.

New York: American Book Co., 1885, $1.62.
(2) Plants, a Text-book of Botany (combining .two books, Plant

Relations and Plant Structures). New York: D. Appleton

& Co., 1900. Suggestions for teachers, two pamphets, one

by O. W. Oaldwell, are supplied to teachers with this work, $1.80.
Gray, Asa: (2) Field, Forest and Garden Botany. Revised by L. H.

Bailey. New York: American Book Co., 1868 and later, $1.44.
(5) Elements of Botany. New York: American Book Co., 1887 and

later editions, 94 cents.

244 APPENDIX

(8) Manual of the Botany of the Northern United States. Sixth
Edition. New York: American Book Co., 1890, $1.62. Field
edition, $2.00. Seventh edition, by Robinson, B. L.

Green, J. R. : ( 1 ) An Introduction to Vegetable Physiology. Philadelphia :
P. Blakiston's Son & Co., 1900 and later, $3.00.

Hilgard, E. W. : Soils, their Formation, Properties, Composition and
Relations to Climate and Plant Growth in the Humid and
Arid Regions. New York: The Macmillan Co., 1906, $4.00.

Hough, R. B.: Handbook of the Trees of the Northern States and Canada,
East of the Rocky Mountains. Photo-descriptive, Lowville,
N. Y. : Published by the Author, 1907, $8.00.

Jackson, B. D. : A Glossary of Botanic Terms with their Derivation and
Accent. Philadelphia: J. B. Lippincott & Co., 1900, $2.00.

Kerner von Merilaun, A. Translated by F. W. Oliver: The Natural His-
tory of Plants. New York: Henry Holt & Co., 4 vols., 1894-
1895, $11.00.

Kraemer, Henry: A Text-book of Botany and Pharmacognosy Intended
for .the use of studentsi of Pharmacy, as a Reference Book for
Pharmacists, and as a Handbook for Food and Drug Analysis.
Philadelphia: J. B. Lippincott Co., Third Edition, 1908, $5.00.

Leavitt, R. G. : Outlines of Botany for the High School Laboratory and
Classroom (based on Gray's Lessons in Botany). New York:
American Book Co., 1901, $1.00.

MacDougal, D. T. : ( 1 ) The Nature and Work of Plants. An Introduction
to the Study of Botany. New Yftrk: The Macmillan Co., 1900,
80 cents.

(2) Practical Text-book of Plant Physiology. New York: Long-

mans, Green & Co., 1901, $3.00.

(3) Elementary Plant Physiology. New York: Longmans, Green &

Co., 1902, $1.20.

Osterhout, W. J. V.: Experiments with Plants. New York: The Mac-
millan Co., 1905, $1.25.

Penhallow, D. P.: A Manual of the North American Gymnosperms. Bos-
ton: Ginn & Co., 1907, $4.50.

Sargent, C. S.: (2) Manual of the Trees of North America (exclusive of
Mexico). Boston: Houghton, Mifflin & Co., 1899, 75 cents.

Small, J. K. : Flora of the Southeastern United States. New York : Pub-
lished by the Author at the New York Botanical Garden, 1903,
$3.60.

Stevens, W. C.: (2) Plant Anatomy, from the standpoint of the develop-
ment and functions of the tissues, and handbook of micro-
technic. Philadelphia: P. Blakiston's Son & Co., 1907, $2.00.

APPENDIX 245

Strasburger, E., Noll, F., Scbenck, H., and Karsten, G., Translated by W. H.
Lang: A Text-book of Botany. New York: The Macmillan Co.,
1908, $5.00.
Underwood, L. M. : ( 1 ) Our Native Ferns and their Allies. New York :

Henry Holt & Co., 1881 and later, $1.00.
(2) Molds, Mildews, and Mushrooms. New York: Henry Holt &

Co., 1899, $1.50.
Vines, S. H.: (1) Lectures on the Physiology of Plants. Cambridge:

University Press, 1886, $5.00.
(2') Elementary Text-book of Botany. New York: The Macmillan

Co., 1898, $2.25.

Waters, C. E. : Ferns. A Manual of the Northeastern States. New York :
Henry Holt & Co., 1903, $3.00.

GLOSSARY.

Ac'au-les'cent. Apparently stemless.

Ac-ces'so-ry. Something added. Extra organ or part.

Ad-he'rent. Growing to or attached to.

Ad-he'sion. The union of organs of different kinds, as stamens to petals,

etc.

Ad'nate. Growing fast to; united.
Ad'ven-ti'tious. Out of the usual order; accidental.
Ag'gre-gate. Assembled close together. /

A-kene', or a-ken'ium, or a-chene'. An indehiscent seed vessel or fruit,

bearing one seed.
Al'ter-nate. Distributed singly at different heights of the stem; not

opposite.

Am'ent. A catkin type of inflorescence.
Am'en-ta'ceous. Catkin-like, or catkin-bearing.
A-nal'y-sis (botanical). The process of classifying and finding the names

of plants.

A-nat'ro-pous. Having the ovule inverted at an early period in its devel-
opment, so that the chalaza is at the apparent apex.
An'dre-oe'cium. . The stamens of a flower taken together.
An'e-moph'i-lous. Wind-loving; said of wind-pollinated flowers.
An'gi-o-sperrtis. Plants whose seeds are borne in a closed vessel.
An'nu-al. Yearly.

An'nu-lar cells. Cells with ring-like markings.
An'ther. The part of the stamen that contains the pollen.
An'ther-id'i-um. The organ in cryptograms corresponding to the anther in

flowering plants.
A-pet'al-ous. Without petals.
A'pex. The top or point, especially of a leaf.
Ap'i-cal. Belonging to the apex or point.
Ap-pend'age. Any superinduced part.
A-quat'ic. Living in the water.
Ar'bo-re'tum. A collection of trees.
Ar-bo're-ous. Tree-like.
Ar'che-go'ni-um. The organ in cryptograms1 corresponding to the pistil of

flowering plants.

As-cend'ing, or as-cend'ent. Arising obliquely; assurgent.
As-sim'i-la'tion. The function of producing starch or other plant food.
At'ro-pous, or at'ro-pal. Not inverted; orthotropous.

247

248 GLOSSARY

Awn ( on ) . The bristle or beard of barley and similar plants.

Ax'il. The angle between the petiole and the branch on the upper side.

Ax'is. The stem or other central line of the plant.

Bac-te'ri-um. The smallest organism known; micro-organisms, destitute of
chlorophyll, which multiply with great rapidity and cause putrefaction
and disease.

Bast-cells. Long cells of bark.

Beard'ed. Having tufts of long hairs, or awns.

Ber'ry. A fruit with a fleshy pericarp.

Bi'col'or. Two-colored.

Bi-en'ni-al. Of two years' duration, bearing seeds the second year only.

Bi-fo'li-ate. With two leaflets.

Bi-la'bi-ate. Two-1'pped.

Bi'lobed. Two-lobed.

Bi-loc'u-lar. Divided into two cells.

Bi-no'mi-al. Having two names.

Blade. The expanded part of the leaf.

Bot'a-ny. The science which treats of plants and plant growth.

Bract. The small leaf or scale from the axil of which a flower or its pedicel
proceeds.

Branch. A shoot growing from the stem.

Bry-oph'y-ta. Moss and moss-like plants.

Bud scales. Coverings of a bud.

Bulb. An underground bud.

Bulb-if'er-ous. Bearing or producing bulbs.

Bulb'lets. Little bulbs, borne above ground.

Ca-lyp'tra. The hood of the spore-case of a moss.

Ca'lyx. The outer floral envelope.

Cam'bi-um. An old name for the growing cells between the wood and bark ;

nascent structure.
Cam'py-lot'ro-pous. Having the ovule curved, with the apex near the

hilum.
Cap'il-la-ry, or cap-il-la'ceous. Resembling hair; long and slender; the

passage of water through small openings.
Cap'i-tate. Head-shaped ; growing in close clusters of heads.
Cap'sule. A dry dehiscent seed vessel with more than one carpel.
Car'pel. A simple pistil.

Car'un-cle. An excrescence near the hilum of some seeds.
Car'y-op'sis. A grain ; a thin, dry, one-seeded pericarp.
Cat'kin. An ainent.

GLOSSARY 249

Cau'dex. The trunk or stem of a plant.
Cau-les'cent. Having a distinct stem.

Cau'li-cle. A little stem, or rudimentary stem of a seedling.

Cau'line. Relating to the stem.

Cell growth. Formation and enlargement of cells.

Cel'lu-lar tis'sue. Tissue formed of cells.

Cel'lu-lose. The substance of which cell walls are formed.

Ce're-al. Relating to grains, corn, etc.

Cha-la'za. The part of an ovule where the covering and nucellus join.

Chlo'ro-phyll. The green substance of leaves and bark.

Cir'cu-la'tion. A moving around (as of the sap).

Cla'vate. Club-shaped.

Cleis-tog'a-mous. Pollination in closed buds.

Climb'ing. Rising by clinging to other objects for support.

Com-plete' flow'er. One that has all the organs — calyx, corolla, stamens
and pistils.

Corn-pound' flow'er. One composed of a number cf separate flowers
crowded on the torus.

Corn-pound' leaf. One composed of separate leaflets, or little leaves.

Cone. A strobile, a multiple fruit having the shape of a cone.

Cork'y. Of the texture of cork.

Corm. A sort of bulb or fleshy stem.

Co-rol'la. Inner perianth made up of petals.

Co-ro'na. A crown.

Cor'ti-cal bark. Outer bark.

Cor'ymb. A flat- topped or convex cluster of flowers, each on its own foot-
stalk, and arising from different points of a common axis.

Cot'y-le'dons. Lobes or seed leaves, or first leaves of the embryo.

Creep'er. A plant that trails on the ground.

Cre'nate. Bordered with round teeth.

Cross'-pol'li-na'tion. The pollination of a plant by pollen from a different
individual.

Cru'ci-form. In the form of a Roman cross.

Cryp'to-ga'mia. Name of the division of plants without flowers.

Culm. The straw of grasses.

Cu'ne-ate, or cu-ne'i-form. Wedge-shaped.

Cu'pule. A little cup, as the cup of the acorn.

Cus'pi-date. Having a sharp, stiff point.

Cu'ti-cle. Outer lamina of wall of epidermis.

Cyme. Flower cluster with the oldest flowers at the top or centre.

250 GLOSSARY

De-cid'u-ous, Falling at the end of the season.

De-cum'bent. Reclining with the top ascending.

De-fo'li-a'tion. The casting off of leaves.

De-his'cent. Opening by regular valves.

Del'i-ques'cent. Branching, so that the stem is lost in branches.

Del'toid. Like the Greek letter A in form.

Den'droid. Tree-like in form.

Den'tate. Toothed.

De-nud'ed. Become naked.

De-pend'ent. Hanging down.

De-pressed. Flattened from above; low.

De-scend'ing. Tending gradually downward.

Dex'trin. A gummy substance produced by the action of diastase upon

starch.
Di'a-del'phous. Having stamens grouped into two sets by united

filaments.
Di'ag-no'sis. A brief statement of the distinctive character of a plant or

group.

Di-an'drous, With two star. Jens.

Di'a-stase. A peculiar ferment in malt, altering starch into dextrin.
Di-chla-myd'e-ous. Having both calyx and corolla.
Di-chot'o-mous. Two equal forks.

Di-cot'y-le'don-ous. Having two cotyledons, or seed lobes.
Di-cot'y-le'dons. Plants which have two seed leaves in their embryos.
Dif'fuse. Much divided and spreading.
Digl-tate. Having several distinct leaflets palmately arranged, as in the

leaf of the horse-chestnut.
Di-mor'phous. Having two forms.
Di-ce'cious. Having staminate and pistillate flowers borne on different

plants.

Dru-pa'ceous. Like a drupe.
Drupe. A stone fruit, as the peach and cherry.

El'a-ters. Spiral, elastic threads accompanying certain spores.

El'lip-soi'dal. Shaped like an ellipsoid.

El-lip'tic. Having the form of an ellipse.

Em'bry-o. The young plant in the seed.

Em'bry-o sac. The cell in the ovule in which the embryo is formed.

En-dog'e-nous struc'ture. Structure in which the pith and woody fibre

are indiscriminately mingled.

En'do-gens. Plants whose structure is endogenous.
En'do-sperm. The food immediately surrounding the embryo.

GLOSSARY 251

En-tire'-mar'gined. Having a continuous edge.

En/to-moph/i-lous (flowers). Frequented and pollinated by insects.

E-phem'er-al. Enduring for one day.

Ep'i-carp. The outer layer of a seed vessel.

Ep'i-der'mis. Outer layer of cells.

Es-sen'tial or'gans (of a flower). Stamens and pistils.

Ex'o-carp. Outer layer of a pericarp.

Ex-og'e-nous struc'ture. Structure like an exogen.

Fas'ci-cle. A bundle, or cluster.

Feath'er-veined. With alb veins from the sides of the mid-rib or mid-vein.

Fer'ti-li-za'tion. Union of sex cells.

Fi'bro-vas'cu-lar. Containing woody fibres and ducts.

Fil'a-ment. The stalk of a stamen.

Fil'i-form. Slender, like a thread.

Flesh'y. Composed of firm pulp or flesh.

Flo'ral en've-lope. The perianth of a flower.

Flow'er. The organ which produce* the seed.

Fo'li-ate. Provided with leaves.

Fol'li-cle. A one-celled, many-seeded carpel, opening by the ventral suture.

Fo-ra'men. A small opening or orifice.

Frond. An organ which is both stalk and leaf ; usually applied to ferns.

Fruc'ti-fi-ca'tion. The act of producing fruit.

Fruit. A ripened pistil; a seed vessel with its contents.

Fru-tes'cent. Shrubby in character.

Fu'ni-cle, fu-nic'u-lus. The stalk of an ovule or seed.

Fu'si-form. Spindle-shaped.

Gam'o-pet'a-lous. Having the petals united; sympetalous.
Gam'o-sep'a-lous. With the sepals united.
Gla'brous. Smooth, not hairy.
Glu-ma'ceous. Glume-like; glume bearing.

Glumes. Bracteal coverings of flowers or of the seeds of grains and grasses.
Grain. The gathered seeds of cereal plants.

Gym'no-sper'mae. A class of exogenous plants characterized by naked
seeds.

Has'tate. Triangular, with the base lobes abruptly spreading as in a

halberd.

Heart/wood. The wood near the central part of an exogenous tree or shrub.
Her-ba'ceous. Green and cellular in texture.
Her-maph'ro-dite (flower). Having both stamens and pistils.

252 GLOSSARY

Het'er-og'a-mous. Having two sorts of (lowers on the same head.

Hi'lum. The eye, or scar, of the seed.

Kir'sute. Hairy; with rather long hairs.

His'pid. Bristly; having stiff hairs.

His-tol'o-gy. The science of cells and tissues.

Hy'a-line. Transparent, or nearly so.

Hy'brid. A cross breed between two species.

Im-per'fect flow'er. A flower wanting either stamens or pistils.

In-com-plete' flow'er. Wanting calyx or corolla.

In-cum'bent. Having the radicle lying against the back of one of the

cotyledons.

In-def'i-nite. Too numerous or variable for specific enumeration.
In-def'i-nite in'flo-res'cence, or in'de-ter'mi-nate in'flo-res'cence. A

process of inflorescence in which the flovvers all arise from axillary

buds, the terminal bud continuing to grow, and extending the stem

indefinitely.

In'de-his'cent. Not opening.
In-dig'e-nous. Native to a country.

In-du'si-um. The shield of the fruit dots (sori) in many ferns.
In'flo-res'cence. Mode of flowering, or the arrangement of flowers on a

plant.

In'nate. Growing on the top of the part that sustains it.
In-sert'ed. Situated upon, growing out of, or attached to some part.
In-teg'u-ment. A coat or covering.

In'ter-cel'lu-lar (passages, spaces). Lying between the cells.
In'ter-node. The space between two nodes.
Ir-reg'u-lar flow'ers. Flowers whose like parts differ either in size or

shape.

Key-fruit. A dry, indehiscent, usually one-seeded, winged fruit; a samara.

Lac-tif'er-ous tis'sue. A tissue whose cells and ducts bear milk-like fluid.
Leg'ume. A seed vessel which opens by both a ventral and dorsal opening,

as the bean, pea, etc.
Len'ti-cel. A small oval rounded spot upon a stem or branch, from which

the underlying tissues may protrude.
Loc'u-lar. Relating to the cell or compartment of an ovary.

Med'ul-la-ry rays. Rays of cellular tissue seen in a transverse section of
exogenous wood which pass from the pith to the bark.

GLOSSARY 253

Mer'is-matic. Dividing into cells or segments by the formation of internal

partitions ; i. e., the formation of new cells.
Mes'o-carp. The middle layer of a pericarp, consisting of three distinct

layers.
Mi'cro-pyle. An opening in the outer coat of a seed through which .the

pollen tube enters the ovule.

Mid'-rib, or mid'-vein. The central vein of a leaf.

Mon'a-del'phous. Having the stamens united in one body by the filaments.
Mon'o-cot'y-le'don. A plant having only one cotyledon, or seed leaf.
Mo-noe'cious. Having stamens and pistils on the same plant.
Mon'o-pet'al-ous. Having but one petal.
Mor-phol'o-gy. That branch of biology which deals with the structure of

animals and plants, and treats of the forms of organs, describing their

homologies.
My-cc'li-um. The white threads of filamentous growth of a fungus.

No'men-cla'ture. The technical names used in any particular branch of

science or art.

Nu-cel'lus. The essential body of an ovule where the embryo is developed.
Nu-cle'o-lus. A dense rounded body within a nucleus.
Nu'cle-us. A dense body within the protoplasm of a cell.

Ob-cor'date. Heart shaped, with the attachment at the pointed end.
Ob-lan'ce-o-late. Lanceolate, narrowing toward the point of attachment.
Or'gan. Any member of a plant, as a leaf, a stamen, etc.
O'vule. The young seed.

Pa'lea. Chaff, or chaff-like bract.

Pal'et. Same as palea.

Pal'mate. Lobed so that the sinuses point to the apex.

Pan'i-cle. A branching raceme.

Pa-pil'i-o-na'ccous. Resembling the butterfly, as in some of the legumes.

Pap'pus. The awns, or bristles, which represent the calyx in composite.

Par'al-lel-vein'ed. Having the veins or nerves extending from the base of

the leaf to the apex, parallel to the midvein.
Pa-raph/y-sis. A minute-jointed filament among the archegonia and

antheridia of mosses.
Par'a-site. A plant obtaining nourishment immediately from another plant

to which it attaches itself.
Pa-ren'chy-ma. Soft cellular plant tissue, like the pulp of leaves, having no

wood fibre.
Pa-ri'e-lal. Attached to the main wall of the ovary.

254 GLOSSARY

Per-en'ni-al. Living several years.

Per'fect flow'er. A flower having both stamens and pistils.
Per'i-anth. Calyx or corolla, or both; the leafy parts of a flower surround-
ing the stamens and pistils.

Per'i-carp. The ripened ovary; the covering of the seed.
Pet'al. Part of the corolla.

Pet'i-ole. The stalk of a leaf connecting the leaf with the stem.
Phae'no-ga'rnia, or pha-ne-ro-garmi-a. Name of that division of the

vegetable kingdom which bears visible flowers.
Pis'til. Organ of a flower, made up of ovary, style and stigma, or ovary

and stigma.

Pith. The soft tissue in the centre of the stems of dicotyledonous plants.
Pla-cen'ta. The part of a pistil or fruit to which the ovules, or seeds are

attached.

Plu'mule. The first bud of the embryo plant.
Pod. A capsule, especially a legume.
Pol'len. The fructifying cells borne in the anthers.
Pol'len tube. The slender. tube sent down from the pollen through the

style of the pistil to the ovum in the ovule.
Pol'li-na'tion. The act of transferring pollen to the stigma.
Pol'y-cot'y-le'don-ous. Having many (more than t^vp) cotyledons, as in

the pines.

Pol'y-pet'a-lous. Having the petals separate fronr each other.
Pol'y-sep'a-lous. Having the sepals separate from each other.
Pome. A fruit like an apple.
Pro-cum'bent. Trailing, prostrate.
Pro-thal'li-um, pro-thal'lus. The minute primary growth from the spore

of ferns which bears the true sexual organs.
Pro'to-plasm. The primary organic substance of the cell.
Pseu'do. False.

Pter'i-do-phytes'. Ferns and fern-like plants.
Pu-bes'cent. Covered with fine short hairs.

Ra-ceme'. A flower cluster with an elongated axis and many one-flowered

lateral pedicels.
Ra'chis, or rha'chis. The principal axis in a spike, raceme, panicle or

corymb.
Rad'i-cle. The rudimentary stem of a plant which supports the cotyledons

in the seed, and from which the root is developed downward; a rootlet.
Ra'phe. The continuation of the seed stalk along the side of an anatropoiu

ovule or seed, forming a ridge or seam.

GLOSSARY 255

Re-cep'ta-cle. The apex of the flower stalk, from which the organs of the
flower grow.

Reg'u-lar. Having all the parts of the same kind alike in size and shape.

Res'pi-ra'tion. Breathing ; the absorption by plants of oxygen ; the oxida-
tion of assimilated products, and the release of carbon dioxide and
watery vapor.

Rha'chis. The axis of a spike inflorescence.

Rha'phe. The continuation of the seed stalk along the side of an anatropous
ovule or seed, forming a ridge or seam.

Rhi'zome. An underground stem.

Root. The descending axis of a plant ; the part of a plant that grows down-
ward into the ground. It bears no true buds.

Root' cap. A mass of dead cells which cover and protect the growing cells
at the end of a root.

Root' stock. Same as rhizome.

Sag'it-tate. Arrow shaped.

Sam'a-ra. Indehiscent, winged fruit.

Sap. The watery fluid taken up by the root, and moved through the vessel

up to the leaves.

Sap' wood. The last growth of wood in an exogen.
Seed. Matured ovule.
Se'pal. One of the parts of the calyx.
Ses'sile. Without stem.
Sol'i-ta-ry. Growing alone or singly.
So'rus. A fruit dot of ferns.
Spa'dix. A spike with a fleshy axis.

Spathe. A large bract, or a pair of bracts, inclosing a flower cluster.
Spike. An inflorescence in which the flowers) are sessile on a lengthened

axis.

Spo-ran'gi-um. A spore case in cryptogamous plants.
Spore. A reproductive grain in flowerless plants, analogous to a seed in

flowering plants.
Sta'mens. The organs that produce pollen, consisting of filament and

anther.

Sto'lon. A branch at the base of a plant which roots easily.
Sto'ma. One of the openings in the epidermis of a leaf ; a breathing pore.
Style. That part of the pistil between the ovary and the stigma.
Su-pe'ri-or. Above the ovary
Su-pe'ri-or o'va-ry. Ovary free from calyx.
Sym-pet'al-ous. Having the petals united ; gamopetalous.

256 GLOSSARY

Thal'lus. A mass of cellular tissue, usually in the form of a flat stratum or

expansion, instead of stem and leaves.
Tri'chomc. A hair on the surface of a leaf or stem, or any modification of

a hair.
Tu'ber. A fleshy underground stem, or branch, with buds.

Um'bel. An inflorescence in which the pedicels all spring from the same
point, like the ribs of an umbrella.

Veins. The system of branching vascular woody tissue seen in leaves.
Xy'lem. That portion of a fibro-vascular bundle developed into wood cells.

Zo'6-spore. A spore provided with one or more slender cilia, by the vibra-
tion of which it swims in the water.

INDEX

Aceraceae, 198

Acids, 108

Agriculture, earliest records, 183

history of, 184
Alkaloids, 108
Algae, 169
Almond, 206
Althea, 193
Anatomy, 93
Annuals, 23

Annular rings, 31, 99, 100
Anther, 61

Antheridium, 161, 165, 107, 171
Apetalous, 56
Apium, 215
Apple, 205, 240

Archegonium, 160, Ifil, 105, 107
Asparagus, 228
Avena, 230

Bacteria, 117, 169, 177

Banana, 227

Barley, 230

Bean, 6, 14, 202, 237

Beets, 222

Berries, 206-208, 217, 235, 240

Biennials, 23

Blade of leaf, 48

Brassica, 185

Bread mold, 172

Breeding of plants', 147

Broom corn, 232

Bryales, 16fl

Bryophytes, 164

Buckwheat, 222

Budding, 39

Burl scales, 51

Buds, 31, 4«>, 41

Bundles, fibro-vascular, 97, 100

Cabbage, 185
Calyptra, 164
Calyx, 54

modifications of, 60
Cambium, 31, 97
Cannabis, 225
Carrot, 215
Capsicum, 220
Capsule, 164
Carbohydrates, 107

formation of, 115
Caruncle, 7, 12
Castanea, 227
Castor bean, 7, 14
Catkin, 65
Celery, 215
Cells, 93, 98
Cellulose, 107
Chemical composition, 105
Chenopodiaceae, 221
Cherry, 206, 240
Chestnut, 227
Chlorophyll, 46
Cinchona, 215
Circulation, 118
Citrus, 196
Classification, 65, 70
Clover, 200, 203, 238
Cocoa, 193
Coffee, 215
Composite, 216, 235
Cones, 122
Convolvulaceae, 218
Corn, 6, 15, 231, 236
Corolla, 54, 60
Corylus, 227
Corymb, 64
Cotton, 191, 241
Cotyledons, 4, 5, 10, 16

257

258

INDEX

Cruciferea, 185
Cryptogams, 70
Cucurbitacese, 211, 235
Cupuliferse, 226
Currants, 211, 235
Cycadales, 124
Cyme, 65

Caucus, 215

Deciduous, 122

Dicotyledons, 4, 70

Dioecious, 58

Dioscoraecese, 218

Diseases of plants, 139, 141, 177

Ecological relations, 126
Egg, 76
Eggplant, 239
Elaters, 168
Elm, 224

Embryo, 3, 5, 76, 83
Endogenous, 31, 71
Energy, 111
Epicotyl, 7
Epigynous, 63
Equisetum, 161
Exogenous, 31, 71
Exosmosis, 113
Evergreens, 121

Fagopyrum, 222

Fats, 107

Ferns, 158

Fertilization, 75, 76, 123

Fertilizers, 130

Fibrovascular bundles, 97

Ficus, 225

Filaments, 61

Flax, 193

Flowers, 54, 57, 58, 64, 65, 75

Foliage, first, 10

Foods, 5, 19, 22, 111

Forestry, 134
Fruits, 83
Fungi, 169

Gamopetalous, 60

Galls, 142

Gas, formation of, 16, 115

Geography, 131

Geotropism, 18

Germination, 12, 15

Goosefoot, 221 .

Gossypium, 191

Gourd, 213

Grafting, 39

Graminese, 228

Grape, 197

Grass, 228, 239

Growth, 41, 42

Gumbo, 191

Gymnosperms, 70, 121

Halophyte, 128
H'au&toria, 24
Hazelnut, 227
Head, 65
Heart wood, 100
Heat, 15
Heath, 217
Hemp, 225
Hepaticese, 164, 166
Hibiscus, 191
Hickories, 225, 235
Hilum, 7, 12
Hollyhock, 193
Hop, 225
Horsetail, 161
Hordeum, 230
Humulus, 225
Humus, 117
Hybridization, 148
Hydrocarbons, 107
Hydrophyte, 127

INDEX

259

Indusium, 159
Inflorescence, 64
Ipomceae, 218

Juglandacese, 225

Lamella of leaf, 48

Leaves, 4, 45, 48-51, 93, 102, 131,

142, 159

Leguminosese, 199
Light, 15, 45
Liliaceae, 228, 232
Linaceae, 193
Linum, 193
Liverwort, 164, 166
Lycopersicum, 220

Madder, 215
Mallow, 191
Malvaceae, 191
Maple, 198, 234
Marchantia, 166
Medullary rays, 99
Melons, 213
Mesophyte, 128
Micropyle, 7
Microsporangia, 123
Midrib, 48
Millet, 230
Minerals, 116
Moisture, 9, 12, 15, 19
Mould, 172

Monocotyledonous, 4, 70
Morning glory, 240
Morus, 223
Mosses, 164
Mulberry, 223
Musca, 227
Musci, 164
Mustards, 185; 186, 234

Mutation, 147
Myoetozoa, 178
Myxomycetes, 178

Nettle, 223
Nicotiana, 220
Nightshade, 219
Nitrogen, 116, 117, 129

Oak, 226, 235
Oats, 230, 237
CEdogonium, 171
Oils, 107, 108
Okra, 191
Onion, 228

Operculum, 164
Orange, 196
Organic acids, 108
Oryza, 230
Osmosis, 29, 112
Ovary, 62, 63
Ovum, 76
Ovules, 62, 83
Oxygen, 9

Parenchyma, 99
Parsley, 215
Parsnip, 215
Pastinaca, 215
Pea, 199, 203, 237
Peach, 205, 240
Peanut, 203
Pear, 205, 240
Pepper, 220, 239
Perennials, 23
Perianth, 55
Perigynous, 63
Peristome, 164
Petal, 54
Petiole, 48
Phloem, 98

260

INDEX

Photosynthesis, 46
Pistil, 54, 62
Placenta, 63
Plant breeding, 147

diseases, 139

foods, 111

geography, 131

hair, 103

societies, 147
Plants, composition of, 105

uses of, 183
Pluni, 240
Plumule, 14
Pollen, 62, 123
Pollination, 75, 79, 80, 122
Polygonaceous, 222
Polypetalous, 60
Populous, 227
Potato, 219

sweet, 218, 240
Proteins, 108, 116
Prothallus, 160, 164
Protonema, 164
Protoplasm, 93
Pteridophytes, 158
Pyrus, 205

Quercus, 226
Quince, 240
Quinine, 215

Raceme, 64
Radicle, 7, 12
Radish, 189, 234
Raphe, 7

Rays, medullary, 99
Reproduction, 74

of ferns, 160
Respiration, 51
Rheum, 222
Rhizome, 37
Rhizopus nigricans, 172

Rhubarb, 222

Ribs of leaves, 48

Rice, 230

Rings, annular, 32, 99, 100

Roots, 4, 18, 20, 23-25, 27-30,

101

Root hair, 25, 26
Rosacesfi, 204
Rose, 204
Rootstock, 37
Rubiaceae, 215
Rue, 195
Rutaceae, 195

Saccharum, 232

Saccharomyces, 172

Salicacese, 227

Salix, 227

Saprolegnia, 173

Sapwood, 100

Saxifragacese, 211

Saxifrage, 211

Scales of buds, 51

Scutellum, 11

Secale, 230

Seeds, 3, 4, 7, 75, 77, 78, 83, 88,

89, .137, 239
Seedling, 3
Sepal, 54
Setaria, 230
Scietjes of plants, 127
Soil, 128, 129
Solanceae, 219
Solanum, 219
Sorghum, 232
Sori, 159
Spadix, 65
Sperms, 171
Sphagnales, 166
Spike, 65
Spinach, 222
Spirogyra, 94, 170

INDEX

261

Sporangium, 160, 173

Sporophyll, 162

Sprouting, 7, 10

Stamen, 54, 61, 123

Starch, 106

Stems, 4, 31-33, 35, 38, 47, 93,

98, 121
Sterculia, 193
Sterculiacese, 193
Stigma, 62
Stomata, 38
Style, 62

Sugar, 107, 116, 232
Sunflower, 216
Sunlight, 46
Sweet potato, 218, 240

Tannins, 108
Temperature, 130
Thallophytes, 169
Theobroma, 193
Tobacco, 220
Tomato, 220, 239
Torus, 54

Transpiration, 113, 114
Trees, 135-137
Trichomes, 25, 103
Triticum, 229
Tropophyte, 128
Turnips, 188

Ulmus, 224
Ulothrix, 171

Umbel, 65
Umbilliferse, 215
Urticaceae, 223
Uses of plants, 183

Vacciniaceae, 217
Variations^ 147
Vaucheria, 171
Veins, 48
Vine, 196
Violaceae, 189
Violet, 189
Vitaceae, 196
Vitis, 197

Walnut, 225, 235

Warmth, 8

Water, 15, 16, 105, 112, 114, 126

Weeds, 150, 239

Wheat, 229, 237

Willow, 227, 236

Wood, 100

Xerophytes, 128
Xylem, 98

Yam, 218
Yeast, 172

Zea, 231

Zingibraceae, 227
Zoospores, 171
Zygospores, 171

9 1 *'l

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