1910

LIBRARY

OF THE

UNIVERSITY OF CALIFORNIA.

BIOLOGY

Class L1B*ARf

BIOLOGY

LIBRARY

G

COPYRIGHT, 1901, BY
SHE PRESIDENT AND FELLOWS OF HARVARD COLLEGE

ENTERED AT STATIONERS' HALL, LONDON.

OUTLINES OF BOTANY
W. P. TO

PREFACE

THE present text-book has been prepared to meet a specific
demand. There are many schools which, having outgrown certain
now antiquated methods of teaching botany, find the best of the
more recent text-books too difficult and comprehensive for practical
use in an elementary course. The large number of subjects included
in the modern high school course necessarily confines within narrow
time limits the attention which can be devoted to any one branch.
Thus, more than ever before, a careful selection and judicious ar-
rangement as well as great simplicity and definiteness in presentation
are all requisite to the practical success of any one course of study.
This book offers (1) a series of laboratory exercises in the morphology
and physiology of phanerogams, (2) directions for a practicable study
of typical cryptogams, representing the chief groups from the lowest
to the highest, and (3) a substantial body of information regarding
the forms, activities, and relationships of plants and supplementing
the laboratory studies.

The practical exercises and experiments have been so chosen that
schools with compound microscopes and expensive laboratory appa-
ratus may have ample opportunity to employ to advantage their
superior equipment. On the other hand, the needs of less fortunate
schools, which possess as yet only simple microscopes and very limited
apparatus, have been constantly borne in mind. Even when the
cryptogams and certain anatomical features of the phanerogams are
to be dealt with, much may be accomplished with the hand lens, and,
where applicable at all, it is in an elementary course usually a better
aid to clear comprehension of objects examined than the compound
microscope. Furthermore, the experiments covering the fundamental
principles of plant physiology have been so far as possible arranged
in such a manner as to require only simple appliances.

In arranging a scientific text-book it has been a common practice
to interpolate directions for observation and experiment in the body
of the text. In teaching, however, the writer has found this arrange-
ment highly objectionable. Both laboratory work and class-room
exercises suffer from it. Accordingly, in this book instructions for
laboratory study are placed in divisions by themselves, preceding the
related chapters of descriptive text. The pupil with his book open
before him in the laboratory will, therefore, not here be confronted
by pictures and statements constituting keys to the work which he
should carry out independently. Although it is not intended that
each laboratory chapter should of necessity be finished before the
following chapter of text is taken up, the examination of the plants
themselves should naturally be kept somewhat in advance of the
recitations which summarize and complement the information gained
from that study.

3

195927

4 PREFACE

The descriptive text follows in the main the sequence of topics of
Gray's " Lessons in Botany," and certain parts of that book have been
retained, as occasional paragraphs will show. In view of the relation
of the present book to the " Lessons " as indicated on the title-page,
the writer has felt free to adopt the phraseology of Dr. Gray wherever
desired, without quotation marks. A considerable number of descrip-
tive terms and definitions applied to the leaf and the flower have
been taken from the " Lessons," being now placed apart, for the use
of the classes making a somewhat detailed study of phanerogams in
a systematic way. But the greater part of the descriptive text
throughout is new, the chapters on cryptogams and on physiology
being entirely so.

In an endeavor to combine the best features of newer methods
with the lucidity and defimteness which have given Dr. Gray's text-
books their extraordinary merit, the present book departs from its
predecessor in paying more attention to the life of plants, as con-
trasted with mere form. The writer has aimed to give due promi-
nence to function which underlies form, that is to physiology and the
relations of plants to their surroundings. Yet while seeking properly
to emphasize the ecological aspects of plant life, he believes that ecol-
ogy should not be made the basis of elementary botany. It seems to
him that a course should be built primarily upon a careful study of
form, leading to some power of intelligent discrimination in morphol-
ogy and of accurate description in the technical language of the
science. Equally essential are certain perfectly definite principles of
vegetable physiology. The core of any rational elementary course
is thus -believed to be concrete, embodied in precise and more or less
technical language, and measurably endowed with a quality which
some would with disfavor characterize as formalism. The writer be-
lieves that the body of concrete instruction is not likely soon to be
displaced by the less definite and as yet more tentative generalizations
of the latest Ecology.

The Appendix is an essential part of the book, but is primarily
addressed to the teacher. It contains suggestions in regard to equip-
ment, books, materials, experiments, and additional exercises, as well
as pedagogical methods.

The writer appreciates, and here takes occasion to acknowledge,
the care with which Mr. C. E. Faxon and Mr. F. Schuyler Mathews
have made many new drawings for this book. Thanks are due to the
staff of the Gray Herbarium for aid in proof reading, especially to
Miss M. A. Day, Librarian. The writer is deeply indebted for advice
and criticism to Mr. William Orr, Principal of the High School,
Springfield, Massachusetts. Above all, the writer would acknowledge
his great obligation to Dr. B. L. Robinson, Asa Gray Professor of
Systematic Botany in Harvard University.

R. G. LEAVITT.

CONTENTS

I. LABORATORY STUDIES OF SEEDS AND SEKDLINGS. — Outline of the prob-
lem. The seed. Exercise I., The embryo: its form and condition previous
to germination. Exercise II., The store of food. The seedling: germina-
tion. Exercise III., Vital processes in germination: experiments. Exercise
IV., Influence of temperature. Exercise V., Direction of growth of shoot
and root. Exercise VI., Development of the seedling. Supplementary
topics. Divisions of the vegetable kingdom. The course of study. The
members of a complete plant 7-14

II. SEEDS AND SEEDLINGS. — Origin of the seed. The embryo. Store of
food. The resting state. Vitality. Conditions of germination. Develop-
ment of seedlings. Root hairs. Chlorophyll . 15-23

III. LABORATORY STUDIES OF BUDS. — Exercise VII., General structure of
buds. Exercise VIII., Further examples. Exercise IX., Number and posi-
tion of buds. Exercise X., Wintering of buds. Exercise XL, Development,
or unfolding. Exercise XII., Non-development. Exercise XIII., Compara-
tive vigor. General summary . . . . . » . . 23-27

IV. BUDS. — Growing buds. Resting buds: formation, resting condition,
protection, storage of food. Non-development. Adventitious buds. Defi-
nite and indefinite annual growth. Forms of trees. Supplementary work :
ecology of buds .',/» ............ 27-34

V. LABORATORY STUDIES OF THE ROOT. — Exercise XIV., General mor-
phology and gross anatomy. Exercise XV., Roots for climbing. Exercise
XVI., Roots for storage. Supplementary subjects .... 34,35

VI. THE ROOT. — Origin. Functions. Action of root hairs. Growing point.
Root cap. Roots of epiphytes. Of parasites. Roots as holdfasts. Storage.
Duration 36-45

VII. LABORATORY STUDIES OF THE STEM. — Exercise XVII., Characteristic
external features. Exercise XVIII., Internal structure (monocotyledons,
dicotyledons). Exercise XIX., Structure of wood. Exercise XX., Ascent
of sap: experiment. Exercise XXL, Geotropism : experiments. Heliotropism.
Exercise XXII., Special uses and forms 45-51

VIII. THE STEM. — Composition. Growth. Upright, clambering, climbing
stems. Organs for climbing. Movement of tendrils. Acaulescent plants.
Creeping stems. Vegetative propagation by means of stems. Stems as
foliage. Longevity of trees. Types of adaptation : xerophytes, halophytes,
hydrophytes, mesophytes • • • • 51-00

IX. LABORATORY STUDIES OF THE LEAF. —Exercise XXIII. , Activities of
the leaf. Experiments on assimilation, respiration, transpiration, helio-
tropism, sleep movements, sensitiveness. Exercise XXIV., Parts and struc-
ture of the leaf. Experiments on conduction and turgidity. Exercise XXV.,
Leaf of the Pea. Exercise XXVI., Venation. Exercise XXVIL, Compound
leaves. Exercise XXVIII., Special uses and modifications . . 60-71

X. THK T-.KAF.— Offices. Form and qualities. Stipules. The petiole; its
uses and movements. The " Sensitive Plant." The blade. Venation.
Shape. Influence of natural surroundings. Compounding. Special uses
of leaves. Storage. Scales. Spines. Leaves for climbing. Tendril leaf
of Cobaea. The "Sundew. Pitcher Plants. Bladderwort. Duration OA
leaves. Defoliation. Phyllotaxy. Technical terms used in description.

6 CONTENTS

XI. LABORATORY STUDIES OF THE FLOWER. — Exercise XXIX., The ovules
and ovary. Exercise XXX., The pollen and stamen. Exercise XXXI. , The
perianth. Exercise XXXil., Arrangement of floral organs. Exercise
XXXIII., Inflorescence. Exercise XXXIV., The flowers of Conifera.
Further work on the flower 99-103

XII. THE FLOWER. — General morphology. Ovules. The pistil. Pistil of
the gymnosperms. Pollen. Stamens. Perianth. Forms of corolla and
calyx. Functions. The receptacle. Floral plan. Morphological nature
of floral organs. Suppression, adnation, coalescence. Processes leading to
formation of seed: pollination, fertilization. Structure of the pollen grain.
Cellular structure of plants. Growth of the pollen grain, penetration of
pollen tube, fertilization. Ecology of the flower. Self- and cross-fertiliza-
tion. The former often prevented. Agencies and adaptations for inter-
crossing. Wind, water, animals. Cypripedium. Salvia. Milchella.
Opening and closing of the Catchfly. Protection of nectar. Grouping of
flowers. Effect of crossing. Supplementary reading. Supplementary
studies : field work on ecology of the flower. Terminology of the flower.

103-143

XIII. LABORATORY STUDIES OF THE FRUIT. — Exercise XXXV., Floral
organs involved in the fruit. Exercise XXXVI. , The seed. Outgrowths of
the testa. Exercise XXXVIL, The fruit in relation to dissemination. 144-147

XIV. THE FRUIT. — Nature and origin. The kinds. Simple, aggregate,
accessory, and multiple fruits. Stone and dry fruits. Dehiscent and inde-
hiscent fruits. Berry, pome, drupe, achene, caryopsis, fig. The seed.
Ecology of fruit and seed as regards dissemination .... 14 ('-150

XV. LABORATORY STUDIES OF CRYPTOGAMS. — Nostoc. Pleurococcus.
Spirogyra. Vaucheria. Ectocarpus. Rockweed. Polysiphonia. Nema-
lion. Bacteria. Yeast. Rhizopus. Saprolegniacefe. Peziza. Micro-
sphaera. Toadstool. Lichen. Marchantia. Moss. Fern. Selaginella.
Lycopodiurn. Equisetum 157-168

XVI. CRYPTOGAMS. — General statement. Blue-green Algae : characters of
the group ; Nostoc, Oscillatoria. Green Algae : general characters ; Pleuro-
coccus, Ulothrix, Spirogyra, Vaucheria. Brown Algae : general characters,
habitat, etc.; Ectocarpus (Cutleria), Rockweed. Red Algae: characteris-
tics, habitat ; tetraspores (Polysiphonia), Nemalion. General summary of
reproduction in Algae. Fungi: general statement; Bacteria; Yeasts;
Bread Mold; Water Mold; Sac Fungi, Peziza, Microsphaera, Aspergillus ;
Rusts; Basidiomycetes, Toadstool, Clavaria, Hydnum, Polyporus. Lichens.
Liverworts and Mosses. Marchantia. Mosses. Ferns and their allies.
Ferns. Selaginella. Other Pteridophytes : Lycopodium, Equisetum. Re-
lationship of Cryptogams and Phanerogams ; the transition and homologies.

168-212

XVII. THE MINUTE ANATOMY OF FLOWERING PLANTS. — Cellular struc-
ture. The cell: protoplasm, nucleus, nuclear division, cytoplasm, chloro-
phyll bodies, vacuoles, sap cavity. Starch. Protein granules. Calcium
oxalate. Multinuclear cells. Cell wall and modifications. Modified cells.
Wood fibers. Bast fibers. Collenchyma. Grit cells. Cell fusion. Latex
tubes. Fibrovascular bundles. Structure of stems. Structure of leaves.
Structure of roots 212-229

XVIII. A BRIEF OUTLINE OF VEGETABLE PHYSIOLOGY. — Constituents of
the plant body. Sources of constituents. Absorption of water; of nutrient
salts. Transfer of water. Root pressure. Ascent of sap. Transpiration.
Carbon assimilation. Digestion. Formation of albuminous matter. Trans-
location of food. Storage. Respiration. Resting periods. Growth : phases,
grand period, fluctuations, conditions. Movements, spontaneous, induced.
Circumnutation. Geotropism, heliotropism, hydrotropism. Variations of
light and heat. Change of turgidity. Irritability .... 229-240

APPENDIX 241-259

INDEX AND GLOSSARY 261-272

OF THE

UNIVERSITY

OF

OUTLINES OF BOTANY

I. LABORATORY STUDIES OF SEEDS AND
SEEDLINGS

A seed comes to the ground, lodges in a crevice of the
earth, is warmed by the sun and wet by the rain, and
after a time a new plant, the seedling, appears.

a. To what extent is the new plant already formed

within the seed before germination begins ?

b. What provision is made in the seed, in the way of

food, for the growth of the seedling and its estab-
lishment as an independent individual ?

c. What internal processes at the time of germination

may be detected by suitable experiments ?

d. By what steps does the nascent plant {embryo) de-

velop and attain to a life of self-support ?

These are the general questions which the student is
asked to answer for himself in the studies outlined in this
chapter. The first exercises deal with the seed before
germination, and the later ones with the seedling, that is,
with the germination of the embryo and subsequent
events.

THE SEED

EXERCISE I. THE EMBRYO: ITS FORM AND CONDITION PREVIOUS

TO GERMINATION
<_
Castor Bean. — Beginning at the smaller end of the seed, cut away

the hard outer coat, or integument, without injuring the contents, or
kernel. Run the point of a knife around the edge of the kernel, then
split the halves apart.

7

8 STUDIES OF SEEDS AND SEEDLINGS

Carefully remove for study the structures discovered within. Exam-
ine them with the lens. Describe all parts of the kernel with included
embryo.

The substance surrounding the embryo is the albumen; the leaves
are the cotyledons ; the axis, or stemlet upon which they are borne, is
the caulicle.

Draw : (1) The embryo separated from the albumen ( x 2).1 (2) A
longitudinal section of the kernel cutting the cotyledons in halves ( x 3).

White Lupine. — The parts all become visible on removing the seed
coats and separating the well-marked halves of the seed. Note caulicle,
cotyledons, and between the latter a third part, the plumule, of several
diminutive members. Compare with the embryo of Castor Bean,
noting striking differences.

Draw the embryo with one cotyledon removed, so as to show the
plumule (x3).

Indian Corn. — Lying just beneath the surface of the grain is a
roughly wedge-shaped body. Remove this, leaving the pasty portion
— the albumen. In one face is a cleft. Pull this apart, exposing
structures within.

Study the embryo now in hand. A longitudinal section will help.
In order to identify more surely the members of the embryo, study
also a sprouted seed, in which root and plumule show plainly. The
large single cotyledon is one feature to be especially noted.

Compare and correlate all its different portions with the parts of
the embryos of Castor Bean and Lupine.

Draw surface and sectional views of the embryo to show the
structure (x 3).

From the examples above answer the question, To what extent
is the new plant already formed within the seed before germination
begins ?

EXERCISE II. THE PROVISION OF FOOD DESIGNED FOR THE
EARLIEST GROWTH OF THE YOUNG PLANT

1. Where is the nourishment stored ? Answer this for Castor Bean,
Lupine, and Indian Corn. In addition, examine seeds of the Four-
o'clock, and others provided by the teacher.

Longitudinal sections will generally show at once the location of the
food store, whether outside the embryo, in which case the seed is said to
be albuminous, or within the much swollen tissues of the nascent plant
itself, when the seed is called exalbuminous, or lacking in albumen.

Classify the seeds studied as albuminous or exalbuminous.

1 This means the drawing is to be two times the size of nature.

STUDIES OF SEEDS AND SEEDLINGS 9

In the Four-o'clock remove the integuments, and separate embryo
and albumen carefully.

Draw the food mass of Four-o'clock. Indicate by dotted lines the
natural position of the embryo. Use the hand lens ( x 3).

2. What substances constitute the food of the seedling ? The very
numerous substances of which plants are composed are capable of
being recognized by appropriate tests. A test consists of the treat-
ment of the tissues with certain chemicals. The success of the test
depends upon observing some change of appearance, as of color, known
to be due to the action of the chemical employed upon the substance
for which search is being made.

Test for starch. — Treat a piece of laundry starch with dilute iodine.
Note the color imparted. Starch alone receives this hue from this
reagent. Experiment upon the seeds supplied in order to determine
which contain starch, and in what parts the starch, if found, is lodged.
It may be necessary to pulverize or boil a part of the seed in some
cases.

A second food material, of frequent occurrence in seeds. — Crush a
whole kernel of Castor Bean. If this is done with the fingers, the
characteristic feeling of the expressed liquid when the fingers are
rubbed together shows the nature of the food material in question.
Seeds of Flax and of Cotton may be crushed out with the flat of a
knife blade for the same substance.

Other forms of reserve food matter. — Several of these are not readily
discovered without chemical tests or microscopic examination. But a
form occurring in the seeds of a number of plants of considerable
economic importance is well seen in the date seed. Cut the " stone "
of a date in halves transversely. Examine with the hand lens the
small embryo lying crosswise of the seed.

Note the toughness of the main bulk of the seed. It is not gritty,
like the stone of a cherry, but hornlike. It is the albumen, dissolved
during germination and used for the support of the seedling.

From the studies in Exercise II answer the question, What provi-
sion is made in the seed, in the way of food, for the growth of the
seedling and its establishment as an independent individual?

THE SEEDLING. GERMINATION

EXERCISE III. WHAT INTERNAL PROCESSES ARE DISCOVERABLE
AS THE EMBRYO BEGINS TO GROW, AND GROWTH PROGRESSES?

Experiment i. — Select seedlings of Bean in the first stages of germi-
nation, the caulicles coming into view. Remove the seed coats. Drop
a dozen of the denuded beans into a four-ounce or six-ounce bottle
filled with water which has been recently boiled to drive off dissolved
air, and allowed to cool.

10 STUDIES OF SEEDS AND SEEDLINGS

The cork, pierced by two glass tubes that penetrate a quarter of an
inch or so beyond the inner surface, should be put in with care to
exclude even the smallest bubbles of air; and the water should rise to
fill the tubes completely as the cork is pushed in. Place the fingers
tightly over the glass tubes and invert the bottle. Stand it mouth
down in a dish of water (e.g. a tumbler). Be sure no air is present in
the bottle.

Displace the water in the bottle by hydrogen gas. Lead the hydro-
gen from the flask into the bottle only after all air has been driven
off in the flask. Allow the apparatus to stand as now adjusted in
some situation favorable to the growth of the beans.

Beside it place a quite similar arrangement, also with sprouted
beans, but let this one contain air in place of hydrogen.

Make full notes of the preparation and conditions of this experi-
ment. Several days may be required for the result to be plainly
seen. Thereafter finish the notes on the experiment.

In this exercise hydrogen, a harmless gas, is used to give an
atmosphere devoid of oxygen. The second jar, filled with air, has of
course a supply of the latter gas. What is your inference concerning
the presence of oxygen?

Experiment 2. — In a fruit jar one-third full of sprouting corn place
a small beaker of limewater. Cover the jar tightly. Another beaker
with like contents is to be placed in an empty jar beside the first, and
this jar likewise closely covered. After an interval of from one to
several hours observe the appearance of the liquid in both beakers.
Note any difference.

Take a small beaker of fresh limewater. Breathe gently upon it
till a change is produced. This action of one's breath upon limewater
has what bearing in explaining the effect observed in the jar of sprout-
ing corn? What is the object of the second jar and beaker?

Experiments 1 and 2 will enable the student to infer —

(1) Whether the atmosphere supplies anything more than moisture
to the germinating plant ; (2) Whether the plant gives back anything
into the atmosphere.

What action necessary to the life of animals does this double pro-
cess in growing plants resemble ?

Experiment 3. — Having removed the beaker from the jar of seed-
lings used in the previous experiment, tie a cloth over the mouth of
the jar. Near by lay a thermometer. When the mercury column has
become stationary, note the reading accurately (without handling the
bulb), and passing the instrument through a small hole in the cloth,
insert its bulb amongst the seedlings.

Within five or ten minutes observe with exactness the temperature
of the seedlings. Is it higher or lower than that of the room?

STUDIES OF SEEDS AND SEEDLINGS 11

The jar must not stand in direct sunlight, the effect of which
would be to render the contents wanner than the room.

It would be well to find by means of another thermometer whether
the temperature outside the jar changes in the same direction equally,
during the time of observation.

Is there any connection between the activity of the seedlings,
detected by Experiments 1 and 2, and their heat condition indicated
by the thermometer in Experiment 3 ?

EXERCISE IV. INFLUENCE OF TEMPERATURE ON GERMINATION

Experiment 4. — Take 100 seeds of Bean, 100 grains of Indian Corn,
and 100 grains of Wheat. Soak all the seeds for twenty-four hours in
water. Note the change or changes produced.

The seeds of each kind are then to be divided into two sets of 50
each. Place one set of each kind in a suitable receptacle, where they
will be kept moist, but not covered with water (e.g. place between
layers of wet blotting paper, or in moist cotton, or in wet sphagnum
moss, the receptacle being closed to prevent evaporation). Put the
receptacle in a warm place where the temperature will be as nearly
75° Fahr. as possible. Treat the other sets in like manner, but expose
to a low temperature — but, of course, above freezing. Each day
record in a table the number of seeds of each kind that have
sprouted. What is your inference concerning the influence of tem-
perature ?

EXERCISE V. DIRECTION OF GROWTH OF PLUMULE AND ROOTLET

Experiment 5. — By a chance position of the seed in the soil the nas-
cent root, or radicle, on emerging may have its tip directed toward any
point but the right one. Ascertain as follows how an inverted seedling
behaves. Fit a double roll of blotting paper into a beaker. Moisten.
Between the paper and the glass place seedlings, well sprouted, with
the roots pointing upward, the plumules downward. They are held
in place by the pressure of the paper. But if some of the seeds are
large, — like the Lupine, — tuck wads of cotton in on either side to
support the radicle, and prevent it from falling or bending over.

Pour a little water into the beaker. This, soaking up on the blot-
ting paper, will keep the seedlings moist. Cover the beaker to pre-
vent drying up. Draw some of the seedlings well enough to record
their positions. After two or three days examine and draw again.

Record the preparation and results of this experiment. Is there
indicated anything which might be termed sensitiveness, together
with active growth toward or away from the direction of gravity?

Or are the affected parts simply bent by their own weight?

12 STUDIES OF SEEDS AND SEEDLINGS

EXERCISE VI. THE DEVELOPMENT OF THE SEEDLING

Experiment 6. — An exceedingly important change undergone by
the seedling as it conies out of the soil or the seed into the light,
may easily be overlooked. In order to single out this effect from
others observed in the course of the young plant's development, next
to be studied, germinate some seeds in the dark, and let the seedlings
develop quite away from the influence of light. Their increase of size
and the succession of parts will be much like that of ordinary seedlings,
and their appearance similar except in the one vital particular — a
characteristic of plants so commonplace that it is hard to realize its
true importance.

In the course of the studies below let the above seedlings, and per-
haps others grown in very dim light, be compared with those grown
in full light.

Turning now to the general development of the seedling, the
student should consider afresh that in the buried seed there is a
nascent plant, and that at the start it is confronted by a complicated
problem. In many cases the very first difficulty is how to escape from
the wrappings of the seed itself. After that there is the question how,
through growth from a very limited food supply, on the one hand to
reach the air and spread a small crown of leaves, and on the other to
establish connection with the soil.

Germinate seeds of Squash, Onion, White Lupine, Pea, and Morn-
ing Glory, to various stages. Write notes along the lines indicated
below, and illustrate by drawings.

1. Any special methods of getting free from seed coats.

2. Whether the cotyledons are raised out of the ground or not.

3. The mode of extracting cotyledons or plumule from the soil.

4. AVhether the cotyledons serve as food sacs, as foliage leaves, or
as both.

5. In which cases the plumule develops early, in which late ;
reasons.

6. In albuminous seeds, what organ of the embryo acts to absorb
the albumen.

On points calling for individual judgment rather than statement of
facts, let the opinion formed by the pupil be expressed distinctly as
such.

Supplementary Topics for Investigation (optional)

1. The rudimentary embryos of orchids. Material, seeds of native
or greenhouse plants. Polyembryony of Spiranthes cernua.

2. Embryos of certain Conifers. Pinus Lambertiana, P.pinea, or
even smaller seeded species for the seeds. Larix Americana (Hack-
matack) and Picea exceha (Norway Spruce) for germination.

STUDIES OF SEEDS AND SEEDLINGS 13

3. The dependence of seedlings upon the nourishment in the
cotyledons. Compare the growth of entire plantlets with that of
plantlets deprived of one or both cotyledons.

4. To what size will the food store of the seed, with the addition
of water alone, bring the seedling ? Exclude light ; for in darkness
the seedling can make no new food. Sprout several kinds of seeds,
choosing a variety as regards the amount of albumen or size of the
embryo. Tie mosquito netting loosely over the mouth of a dish, and
fill the dish with water until it touches the netting, upon which place
the sprouted seeds with the radicles going down into the water.
Report the results, and illustrate with the plants grown.

Investigations 3 and 4 may be made at home.

Divisions of the Vegetable Kingdom. The Course of Study

One has but to draw upon his everyday observation to
realize how varied is the plant realm. There are such
diverse types as the trees and herbs that we see every-
where about us, the ferns, the mosses, the molds and
toadstools, and the seaweeds. These differ so widely
from one another that at first sight there seems to be
little upon which one could base any notion of a common
relationship.

Nevertheless, the multitude of forms have been brought
together into comparatively few grand divisions, and close
study has revealed a considerable measure of agreement
running through the whole series. We may reasonably
suppose that all plants are of one stock, and that the
higher groups have sprung from forms resembling the
lower.

In his present work the student is concerned with but
one type, the highest of all, that of the FLOWERING
PLANTS, or PHANEROGAMS. It comprises nearly all
the plants of large size, and by far the greater part
of those which are useful to mankind — the forests,
the grasses, the grains, the fruits, the fiber plants,—
those that at present make the earth green and hab-
itable.

All the lower plants of diverse sorts, from the ferns
downward, are termed FLOWERLESS PLANTS, or CRYPTO-
GAMS. They are reserved for the latter part of the course.

14 STUDIES OF SEEDS AND SEEDLINGS

Phanerogams and Cryptogams have much in common,
as has just been stated : the highest Cryptogams closely
resemble the lowest Phanerogams. Yet the latter, as a
whole, form a well-marked group by themselves. One
mark of distinction may be stated thus : —

Phanerogamous plants grow from seed and bear flowers
destined to the production of seed. By many recent
authorities they have been termed Seed Plants, or Sper-
matophytes; and this designation is more significant than
the earlier and commoner one of flowering plants.

The reproduction of Cryptogams is carried on by means
of spores, bodies very much smaller and simpler than the
smallest and most rudimentary seed. The spores contain
no ready-formed plants. They go through a series of
changes, quite unlike anything to be observed in the
germination of seeds, before the form of the plant which
gave rise to them is reproduced. The pollen of flowering
plants, which must be familiar even to those who have
paid little or no attention to plant structure, closely
resembles the spores of the floweiiess plants. This may
enable one to see, at a single glance, the wide difference
between spores and seeds.

The Members of a Complete Plant

The seedlings studied in the last Exercise were com-
plete plants. They were provided with all necessary
organs of vegetation. All phanerogamous plants con-
sist of (1) root, and. (2) shoot ; the shoot consisting of
(a) stem, and (6) leaf. It is true that some excep-
tional plants, in maturity, lack leaves, or lack roots.
These exceptions are few. The parts of the phanerogams
studied are to be assigned to root, stem, or leaf. Let
it be understood that when in the studies on flowering
plants the question is asked, " What is the mor*phology,
or nature, of this part ? " this is equivalent to asking,
" Is the part in question of the nature of root, or .of
stem, or of leaf?"

SEEDS AND SEEDLINGS

15

1. Central portion of one
of the flowers of
Hermannia Tex-
ana, showing the
seed rudiments.

Bud

II. SEEDS AND SEEDLINGS

I. The seed carries within it a minute plant. The seed
originates in the flower, within an often globular or pod-
like structure (Fig. 1), which,
though generally the least
conspicuous of the floral
organs, may have attracted
the student's attention on
account of its central posi-
tion and peculiar form. This
receptacle may contain a
very great number of the
rudiments of the future
seeds, or only a few, or even
only one ; and may be the

Seed vessel

2. Buds, flowers, and ripened seed vessels
(fruit) of Hermannia Texana.

sole seed-bearing part, or one of several in the same
flower. After the floral leaves with their wide expanse
and bright colors have performed the part they play in
the life of the flower, and have fallen away, this seed
receptacle enters upon a new period of its history. It
grows, often vigorously, and through alteration of form

16

SEEDS AND SEEDLINGS

and texture approaches nearer and nearer to its final con-
dition of fruit (Figs. 2, 3).

2. The seed rudiments meanwhile undergo fundamen-
tal changes : the embryonic plants are formed, seed coats

3. a, the fruit, or matured form of the central organ of the flower
(Fig. 1), cut across to show the seeds ; 6, a seed, magnified ; c, a
section of the seed ; d, the embryo removed from the seed.

develop, fitted to secure the dispersal of the seeds far and
wide, or to protect the embryo, and a store of food for
rearing the young plant to a certain stage is provided
(Fig. 3).

3. At length, when the seed is fully ready for its
mission, the now ripened fruit falls to the ground and
decays, liberating the seeds, or is borne away by currents
of wind or water, or by animals. Or, remaining on its stem,
it either opens (Fig. 3), allowing the seeds to be scattered

by a variety of agencies, or in a
number of cases bursts, forcibly
ejecting the seeds from their
receptacle.

4. The primitive plant, or em-
bryo, inclosed in the seed, may be
so rudimentary that it shows not
distinction of organs. Such a case
is furnished by Orchids, epiphyt-^
ic1 upon trees in tropical forests,
•i. Seed of an Orchid, with Their flowers are often large ; but

loose, buoyant coat, and ., , ,

a rudimentary embryo the extremely numerous seeds are
(magnified). of the smallest size, and of the

1 Epiphytes grow upon, but derive no sustenance from, other plants.
Parasites live at the expense of their hosts.

SEEDS AND SEEDLINGS

17

simplest structure throughout (Fig. 4). Floating through
the air like chaff, they are borne to situations suited to
the life habit of these plants. The very much reduced
embryo is a minute rounded body with no sign of leaf
and stem appearing until germination has considerably
advanced.

5. But every well-developed embryo consists essentially
of a nascent axis, or stem, — the caulicle, — bearing at one
end a leaf or leaves, — the cotyledons, — while from the
other end a root is normally to be produced (Fig. 3, d).

6. The number of cotyledons. — Several of the embryos
examined in the laboratory were dicotyledonous, that is,
two-cotyledoned. Plants which are thus similar in the
plan of the embryo, agree likewise in the general struc-
ture of their stems, leaves, and blossoms ; and thus form
a class, named from their cotyledons,

the DICOTYLEDONS.

7. Figure 5 represents the Pine seed
seen in section, together with the young
tree after its cotyledons are fully ex-
panded. Of these there are several, a
case which is much less usual, but con-
stant in the various kinds of Pine, where
in some species the cotyledons number
twelve, or even more. And in some
other Coniferce, or cone-bearing trees,
the same peculiarity is found. The em-
bryo is here said to be polycotyledonous.

8. The term monocotyledonous denotes
the possession of but a single cotyle-
don. This condition goes along with

other peculiarities of external and internal structure, and
is thus characteristic of a class of plants — exemplified by
the true Lilies and the Grasses — called the MONOCOTYLE-
DONS.

9. In addition to the parts already referred to, many
embryos show in miniature one or two lengths of the stem
which is to carry the growth of the plant upward above

OUT. OF 3OT. 2

5. Section of a Pine
seed; seedling
showing 6 coty-
ledons.

18

SEEDS AND SEEDLINGS

6. Embryo of the Yel-
low Pond Lily
(magnified).

the cotyledons, with several of the first leaves which it
will bear (Fig. 6). This bud of the ascending axis, already
developed in the seed, is the plumule.
In the Bean and similar strong embryos
the leaves of the plumule are already
perfect as concerns outline, veining,
and so on, and need only to gain green
color and a larger size to become use-
ful to the seedling as foliage. These
plants, therefore, very soon after coming out of the
ground are found actively acquiring the means of further
growth, while still using nourishment
inherited from the parent plant.

10. Food. — Along with the incipient
plant is sent a store of food in a form
easily . used, with which its start in

an independent ca-
reer will be made.
The amount is as
variable as the size
of the embryo it-
self. It may be

relatively very large, as seen in the
seed of Actsea (Fig. 7). In Fig. 8
the embryo is relatively larger than

the mass of nutrient material. This

example prepares us for the condition

seen in the seed of many families of

plants, where a supply of nutriment

separate from the germ itself is never

developed (Fig. 9).

11. Food matter external to >the
embryo is termed albumen, or endo-
sperm, and seeds having it are called albuminous seeds.
Those lacking albumen are called exalbuminous.

12. It will readily be seen in most cases that embryos
unfurnished with albumen are not in consequence the
worse off, for they are of larger size and their tissues are

8. Seed of the Purslane,
in section, the em-
bryo surrounding
the reduced albu-
men (magnified).

7. Section of the seed
of Actsea, show-
ing the minute
embryo and the
relatively abun-
dant albumen
(magnified).

9. Exalbuminous seed
of Gynandrop-
sis, in section
(magnified) .

SEEDS AND SEEDLINGS 19

swollen out with nutrient substances. This is the arrange-
ment in seeds like the Peanut, Walnut, and Chestnut ;
the edible kernel is really a rudimentary plant.

13. The seed food of embryonic plants consists chiefly
of starch, fat, sugar, and in smaller quantities proteid
substances ; that is, substances resembling the white of
egg and the curd of milk. Transformed by the growing
embryo and seedling into living substance and frame-
work, with the addition of water alone, these concentrated
formative matters may enable the young plant to grow to
Inany times the size of the original seed.

14. The resting state. — The germ may remain long
dormant in the seed. Its condition is then like that of
the buds of trees and the underground bulbs of herbaceous
plants in winter. Life sleeps, so to speak ; and the living
parts can endure extremes of dryness, cold, and so on,
which they are unable to bear in their more active periods.
Thus the embryo passes uninjured through change of sea-
sons that would cause the death of a seedling. Dormant
and well protected, it may be carried to great distances.
If at first unfavorably lodged, the seed may long await a
change of circumstances. When a forest is cleared away,
a great variety of field plants at once spring up, doubtless
from seed deposited in the soil long before.

15. Retention of vitality De Candolle kept seeds of

many kinds for fifteen years, when those of a few species
germinated. In another case the known age of seeds
which still kept their vitality was forty-three years.1 On
the other hand, certain seeds must be planted as soon as
separated from the fruit.

16. The conditions of germination. — When the slow
inward changes of the dormant period have fully pre-
pared the seed, — or when ripeness has come, even without
a resting stage, — germination will begin, if a few neces-
sary conditions are fulfilled. There must be water,
warmth, and oxygen.

1 The stories of the germination of seeds from mummy cases are with-
out foundation.

20 SEEDS AND SEEDLINGS

17. Water. — Seeds are usually rather dry on issuing
from the fruit. Dryness makes the seed hardy. In
contact with water therefore, at the time of germination,
they often swell to two or three times their dry volume.
Actual growth in plants, too, always requires much water.

18. Warmth. — Moderate heat has a strong influence in
hastening germination. For Indian Corn and Squash the
most favorable temperature is given as about 81° Fahr.
A few exceptional seeds will sprout at the freezing point
of water. Thus seeds of a Maple have been germinated
on a block of ice, the rootlets penetrating to a depth of
more than two inches into the dense, clear ice, in which
they melted out cylindrical cavities for themselves. Heat
for growth is here generated by the seedling itself.

19. Oxygen is actively inhaled and combines with the
substances of the embryo. This oxidation furnishes energy
which appears in growth and in vital heat ; that is, in heat
in the seedling similar in all respects to the bodily warmth
of animals.

20. As a result of oxidation carbonic acid gas is formed
and exhaled. The young plant thus breathes in and out.
Respiration is common to all living things. But in plants
the in-take of the one gas and the out-going of the other
are slow, continuous, and imperceptible processes.

21. The development of seedlings. — If one looks under
the White Oak in late autumn, he is likely to find that the
acorns have sprouted. He will then discover that many of
the nuts, if lying on proper surface, for instance on short-
cropped pasture sward, are already fast-bound to the earth,
the radicles, or incipient roots, having penetrated the soil.
It appears, therefore, that seeds may germinate and attach
themselves without being covered up ; though a covering
of some sort, as sand, soil, or dead leaves, is advantageous,
and some fruits, or their carpels, are even provided with
mechanical contrivances for partially burying themselves.1

22. Suppose that a seed lies thus, like the acorn, cleanly
upon the surface, and that it has been drenched by rain

1 See Fig. 279.

SEEDS AND SEEDLINGS

21

and dew until germination actually begins. Plainly the
first need in this case is a root developed in the soil,
whence it may suck up the water and other substances
required for the con-
tinued growth of the
plantlet. To achieve
this object the caulicle
is pushed out of the
shell, and the radicle be-
gins to develop; and at
once it may be seen that
the elongating axis mani-
fests something very like
a rudimentary sense, or
a number of senses. It
is affected by outward
influences. The radicle
of the oak is found, for
instance, to have been
turned sharply down-
ward; or in many in-
stances the movement of
curvature has gone still
farther, and the grow-
ing radicle has followed
the under surface of the
shell backward to the
dampest spot in the im-
mediate neighborhood ; namely, the place where the acorn,
resting on the turf, has collected a little of the moisture
exhaling from the earth — or at least preserved a humid-
ity higher than that of the open. Here the root has made
another turn, under the combined influence of gravity
and humidity, and has entered the soil (Fig. 10).

23. The curving movements of the radicle are made a
little way back of the tip, and the growth of the latter is
thereby directed toward the proper surroundings.

24. Seedlings from buried seed come into the air by a

10. Germination of the White Oak.

UNIVERSITY

SEEDS J.ND SEEDLINGS

variety of methods. When the cotyledons are designed
to act in the sunlight as green foliage for a time, they are,

in general, brought out of the
ground by the lengthening of the
caulicle. As it grows, this usually
bends abruptly just below the
cotyledons; and the top of the
loop thus formed is seen when
the cracking of the soil allows
one the first sight of the springing
seedling. The extraction of the
leafy parts is thus managed with
the least danger of injury from
the resistance of the soil (Fig. 11),
and at the same time the seed
coats are often slipped off.

25. The main part of the origi-
nal seed may remain permanently
buried, while the nutrient con-
tents are gradually absorbed and carried away to the
actively growing regions of the root and the ascending
shoot. This is the case in the Horse-chestnut. The coty-
ledons are mere reservoirs of food.
Their stalks elongate (see Fig. 12),
freeing the caulicle and plumule
from the shell. The root develops
strongly, and the plumule rises,
looped, toward the surface.

26. The end of the root for a
greater or less length, according to
the size of the plant, is always elon-
gating in growth, and slipping forward
between the particles of soil, which it
avoids or pushes aside as the occasion
demands. A portion just behind this smooth thrusting
tip, having become fixed in position, throws out a velvety
coating of so-called root hairs. These penetrate sidewise
into the minutest interspaces of the soil, and adhere to

11. Germination of the Morn-
ing Glory. At the
left, the seedling as it
appears when breaking
from the soil ; at the
right, the same seedling
a little later, the seed
coats thrown off, the
stem straightened, and
the cotyledons opened.

12. Germination of the
Horse-chestnut.

LABORATORY STUDIES OF BUDS . 23

the stony particles. Each hair is a microscopic tube
(Fig. 27), out-growing from a surface cell, and serves to
conduct water and draw food materials into the tissues
of the root, whence they are conveyed to the leaves
above.

27. Color. — The embryo in the seed is pale or color-
less. The seedling — except the root — is dark green,
after a short exposure to the light. But if the seedling
is thrown into strong alcohol, this newly acquired green
color is extracted, the coloring matter proving to be sepa-
rable from the leaves and stems, where it is generated.
It is a definite substance, to which the name Chlorophyll
has been given. Without this substance, plants cannot turn
mineral matters of scil and atmosphere into nourishment.

III. LABORATORY STUDIES OP BUDS

Buds appear as conspicuous features on most of the
perennial plants of temperate and cool climates, after the
autumnal fall of leaves. Such winter buds are to be
the subjects of the following studies.1

EXERCISE VII. THE GENERAL STRUCTURE OF BUDS

Buds of the following common species will show what winter buds
usually contain, in what a compact way the parts are pressed together,
and how some parts are shielded by others.

Lilac. — View the bud endwise. What is the arrangement of the
scales? How were the leaves arranged on the twig?

Remove the scales and little leaves one after another, laying them
down in the order of removal. Note a gradual change in the outlines.
From the last-removed members it is easy to see the morphology of
all the parts, including the scales. What are the scales ? Cut a longi-
tudinal section. Use the lens. All parts are seen in position and
proper attachment.

Draw : (1) An outer, a transitional, and an inner member, as taken
off (x 3.). (2) A longitudinal section (x 10). Label all parts.

1 The parts of the leaf — blade, petiole, and stipules — should be
shown on the board to the class.

24 LABORATORY STUDIES OF BUDS

Horse-chestnut. — Note the arrangement of the scales. Of the leaf
scars on the twig.

Remove the scales by cutting at the base. Separate the wool-
covered members within and remove them, counting and noting down
the number of pairs. Holding one of these parts by its stalk, scrape
off much of the wool, first from the back, then from between the leaf-
lets.

Cut longitudinally down through the bud core, or axis, after remov-
ing all scales and leaves. With the lens notice the short, narrow,
conical part upon which the leaves proper, not the scales, were inserted.
How many internodes l in this bud axis ? (Refer to the number of
pairs of leaves removed.) How many internodes in the last season's
growth on the same twig? Does the bud contain an ordinary year's
growth, as to number of internodes and leaves?

Draw: The bud entire (x 2). One of the young leaves, spread
out (x 3).

Witch-hazel.2 — Note the surface of the bud leaves. Scrape. Use
the lens. Beneath the exterior coating is the leaf soft, green, and
apparently alive, or leathery and dead ? Pull the bud to pieces. Are
any parts different from the outer leaves ? The latter, as well as the
inner ones, finally develop into foliage leaves. There are no scales.
Such buds are termed naked buds. Draw the bud entire (x 2).

EXERCISE VIII.

The Tulip Tree (Liriodendron). — Note the flattish form of the bud ;
the nearly round scar near the base. Separate the two exterior scales
at the tip, and pull them off. Relatively to the little leaf now seen,
in what position does the next pair of scales stand? Examine all re-
maining parts. What is the round scar at the base of the outer pair
of scales? What is the morphology of the scales?

Draw the bud after removal of the outer envelop.

Magnolia. — Does the caplike covering of the bud consist of two
parts fused in growth, or is it single? What is the small scar at one
side of the bud? Examine the contents of the bud. What is the
morphology of the bud cap? Draw the bud, showing the scar.

ADDITIONAL STUDIES

Make a study of several other buds as directed by the teacher.
Among these, the buds of Mountain Ash (Pyrus Americana or P.
Aucuparia), Green Brier (Smilax rotund i folia), Mullein, Dandelion, and
some subterranean bud like those of Smilacina, Trillium, Sanguinaria,
or Uvularia, are suggested.

1 Interspaces between leaves. 2 For alternative material, see Appendix.

LABORATORY STUDIES OF BUDS 25

EXERCISE IX. THE NUMBER AND POSITION OF THE BUDS

The position of buds in general, with reference to the leaves of the
previous season, must have already attracted attention. What is that
position? When two or more buds occur together they have, rela-
tively to one another, one of two characteristic arrangements, as seen
in the following species.

Red Maple. — How many buds in a group? Which ones maybe
termed extra, or accessory ?

Draw enough of the twig to show the essential relations of the buds,
both to the leaf scar and to one another.

Pipevine. — Examine the neighborhood of the leaf scar with the
lens. Cut a longitudinal section of the stem through the middle of
the scar. Examine the cut surfaces of the bark. Growing points,
distinguished by superior greenness, can be made out. Note their
number and relative position.

Make a drawing (enlarged) to show the disposition of accessory
buds here found.

EXERCISE X. THE WINTERING OF THE YOUNG SHOOT

Refer to the records and drawings made in the laboratory for the
materials of a comparative account of buds, with reference to their,
adaptations to winter conditions. Protection against sudden chilling
is sometimes perfect; in other cases temperature seerns to be disre-
garded. Arrange the various modes of meeting the dangers of cold
in an orderly manner in your account.

Are there any other sources of destruction besides low temperature?
If so, what? And are buds protected against these dangers?

EXERCISE XL THE DEVELOPMENT OR UNFOLDING OF BUDS 1

The Lilac, forced to grow indoors, may be studied. Determine
what parts have grown since the bud came out of the typical winter
state. Have all grown equally ? Have some not grown?

Draw enough to show what happens to the different members of
the winter bud.

If possible, compare with the Lilac the unfolding buds of two other
species, as the Buttonwood and the Sycamore Maple.

EXERCISE XII. THE NOXDEVELOPMENT OF BUDS

Select a branch of the Horse-chestnut five years old, or thereabouts.
Count the total number of leaf scars. Of these, how many now sub-
tend buds, or have subtended buds? In how many cases have buds
developed into branches or flower clusters?

1 This may be a home experiment.

26

LABORATORY STUDIES OF BUDS

Add the ages of all the existing buds, individually. Then divide
this total by the whole number of buds. This gives the average age
of the buds. How old is the oldest bud on the branch? Cut some of
the oldest ones open. Should you judge them to be still capable of
development, in case of need?

Record in your notes all numbers and ages.

EXERCISE XIII. COMPARATIVE VIGOR OF DEVELOPMENT

Select a lateral branch of the Maple provided, showing a few years'
growth. Hold the branch in the position in which it grew. Certain
of the leaf scars now look upward, part of them to right or left (hori-
zontally), and part toward the earth. That is, there are two sets,
the vertical (above and below) and the horizontal. In each set count
the whole number of pairs of leaf scars ; also the number (pairs)
where the buds have made some growth.

Record in a table like the following : —

HORIZONTAL

VERTICAL

Whole number (pairs)
Number, where buds de-
velop to twigs

Whole number (pairs)
Number, with twigs

Measure roughly the combined length of all the horizontal twigs
developed from lateral buds. Combined length of vertical twigs.
Compare the numbers obtained thus : —

Total length of all horizontal twigs

Total length of all vertical twigs

Count the whole number of present winter buds on all the twigs of
each set separately. This gives a hint as to their comparative vigor.
Record thus : —

Buds on horizontal twigs
Buds on vertical twigs .

Is there any advantage to the tree in the superior development of
one system over the other?

This exercise is intended to bring out two facts: first, that certain
buds are more likely to develop than others ; second, that certain buds
develop more vigorously than others. The exercise is not intended to
teach — what would not be universally true — that the horizontally
directed buds, for example, are always more vigorous than vertically
directed buds ; or vice versa.

SUDS 27

General summary. — The pupil should by this time be
self-informed as to —

a. What a bud, as a whole, is.

b. What the reason for its formation is.

c. What rudiments of future growth are present.

d. How nearly these approach the full-grown condition
as to form.

e. What parts are of merely temporary use.
/. What the morphology of these parts is.

Make a brief statement covering these points, by way of
summary of the work on buds.

For Supplementary Work, see the end of Chapter IV., where sugges-
tions for outdoor and indoor observations are made.

IV. BUDS
GROWING BUDS

28. In actively growing herbs the tip of the stem and
the rudiments of the coming leaves — appearing at first as
small prominences close to the apex — are usually pro-
tected from accidents. Bites of insects or other animals,
and extremes of
heat, light, dry-
ness, and cold, are
guarded against by
the nidturer leaves
standing together
over the younger
parts (Figs. 13, 14),

or bv Special COVer- 13- Terminal portion of a shoot of Coleus; young
J *, leaves shielding the growing tip.

ings. The forming

members of the Begonia shoot are sheathed by a pair
of scalelike appendages — stipules — at the base of the
highest full leaf (Fig. 15). In addition, in this plant,
the hot rays of the sun are in nature fended off by the
leaves themselves, which are raised umbrellalike over the

28 SUDS

/

growing point ; a mode of protection quite perfectly

represented, also, by the Castor Bean plant (Fig. 16).
In the Mullein, protection is assured both in the growing

14. End of the stem, and two nas-
cent leaves, in Coleus, after
removal of several pairs of
the leaves of the growing
bud.

15. Protection of the growing bud of
Begonia.

season and in winter by a thick, woolly covering of plant
hairs, or trichomes. These are produced by all the leaves
in their earliest stages when crowded together in the bud,

16. Protection of the terminal bud in the Castor Bean.

and persist when the leaves are mature. The tender
sprouts of many plants are well supplied with trichomes
of a special kind, secreting distasteful liquids which dis-
courage the attacks of herbivorous insects.

BUDS

29

. Buds of the
Hickory.

Sometimes

RESTING BUDS

29. The most conspicuous buds are the scaly resting
buds of most trees and shrubs of temperate or cold
climates. When these are formed at the
end of a stem or branch, they are referred
to as terminal buds. In the angle, or axil,

of nearly all the leaves

others are found, termed

axillary or lateral buds

(Fig. 17).

30. Accessory or su-
pernumerary buds. —
There are cases where
two, three, or more
buds spring from the
axil of a leaf, instead
of the single one which
is ordinarily found there.

they are placed one over the other, as
in the Aristolochia, or Pipevine ; and
in - Pterocarya (Fig. 18), where the
upper bud is a good way out of the
axil. In other cases three buds stand
side by side in the axil, as in the Red
Maple.

31. Formation of winter buds. —
Such plants as prepare for winter by
the production of winter buds form
them early in the foregoing summer.
In many woody plants the axillary
buds do not show themselves until
spring- ; but if searched for, they may

18. The accessory buds 5 ; n -

of Pterocarya be detected, though of small size,

EhoifoKa, some- hidden under the bark. Sometimes,
what above the

axil, and already though early formed, they may be
partially devel- collceaie(i au summer long under the

oped in the nrst °

summer. base of the leaf stalk, which is then

30

BUDS

hollowed out into a sort of inverted cup, as in the Button-
wood, or Plane Tree
(Fig. 19).

32. Large and
strong buds, like
those of the Horse-
chestnut and Hick-
• ory, contain besides
the scales several
leaves or pairs of
leaves, ready formed,
folded, and packed away in small compass, just as the
seed leaves of a strong embryo are folded away in the
seed ; they may even contain all the blossoms of the ensu-
ing season plainly visible as small buds. Buds containing

19. Sub-petiolar bud of the Plane Tree.

20. UndergroT-nd stem (**), thickened roots (rf), and
resting bud of Bell wort (Uvularia).

both leaves and flowers are termed mixed buds. Under
the surface of the soil, too, or on it, covered with the dead
leaves of autumn, similar strong buds of our perennial
herbs may be found (Fig. 20).

33. The resting state. — Buds, like seeds, remain in a
state of rest, or dormancy, during the winter, although
life is hardly reduced to such low terms in buds as it is in
seeds. Buds are therefore more easily aroused to activity;

SUDS

31

and they are less hardy. Yet in the coldest weather buds
are frozen without injury, providing the freezing and sub-
sequent thawing are not too sudden.
Some buds which will grow and unfold
when placed in water in the latter
part of the winter, refuse to open at
an earlier period, behaving like those
seeds that will germinate only after
a definite length of time.

34. Protection. — The means and
the degree of protection are various.
Against sudden changes of tempera-
ture thick, woolly covering is often
provided, growing from the young
leaves and around their bases. To
this several thicknesses of scales —

modified leaves —
may be added. The
scales usually fall
away soon after the
bud bursts open in
spring ; but in many
instances, like the
Buckeye (Fig. 21),
make a little growth toward foliage. In
Pterocarya (Fig. 22) the younger leaves
are shielded only by the somewhat broad-
ened stalks of the
partly developed out-
er ones. When the
latter become, in the spring, the full
leaves of the season, such buds are
termed naked buds, i.e. without spe-
cialized protective scales.

35. The slender, pointed axillary
buds of the Horse Brier, or Green
Brier, lie in the groove of the petiole
of the subtending leaf, and are partly

21. Development of the
parts of the bud
in the Buckeye.

22. Naked bud of
Pterocarya
fraxinifolia.

23. Remains of the
petiole protect-
ing the bud in
Horse Brier.

32

BUDS

covered by the margins of the groove. When the leaf
falls off in autumn, the base remains as protection to
the bud (Fig. 23).

36. Store of food. — In trees, the stems which bear the
buds are filled with abundant nourishment deposited the
summer before in the wood and in the bark. Subterranean
buds are supplied from thick roots, root stocks, or tubers,
charged with a great store of nourishment for their use.
(See Figs. 20, 47, 48.)

37. Renewal of growth. — We see that the on-coming
of spring finds plants ready to resume their interrupted
activities, since new shoots are complete in the buds, and
food is at hand for their development. As soon as the
tide of warmth has fairly set in, therefore, vegetation
pushes forth vigorous^ from such buds, and clothes the
bare and lately frozen surface of the soil, as well as the
naked boughs of trees, with a covering of green, and often
with brilliant blossoms. Only a small part, and none of
the earliest, of this vegetation comes from seed.

38. Nondevelopment of buds. — It never
happens that all the buds grow. If they
did, there might be as many branches in
any year as there were leaves the year
before. And of those which do begin to
grow, a large portion perish, sooner or later,
for want of nourishment or for want of
light. In the Hickory (Fig. 17), and most
other trees with large scaly buds, the ter-
minal bud is the strongest, and has the
advantage in growth ; and next in strength
are the upper axillary buds ; while the for-
mer continues the shoot of the last year,
some of the latter give rise to branches,
and the rest fail to grow. In the Lilac
(Fig. 24), the uppermost axillary buds are
stronger than the lower ; but the terminal
bud rarely appears at all; in its place the
uppermost pair of axillary buds grow, and so each stem branches every
year into two, — making a repeatedly two-forked ramification.

39. Latent buds. — Axillary buds that do not grow at the proper
season, and especially those which make no appearance externalLv,

24. Buds and branching of
Lilac.

BUDS 33

may long remain latent, and at length upon a favorable occasion start
into growth, so forming branches apparently out of place as they are
out of time. The new shoots seen springing directly out of large
stems may sometimes originate from such latent buds, which have
preserved their life for years. But commonly these arise from

40. Adventitious Buds. — These are buds which certain shrubs and
trees produce anywhere on the surface of the stem, especially where
it has been injured. They give rise to the slender twigs which often
feather the sides of great branches of our American Elm. They
sometimes form on the root, which naturally is destitute of buds;
they are found even upon some leaves ; and they are sure to appear
on the trunks and roots of Willows, Poplars, and Chestnuts, when
these are wounded or mutilated.

41. Definite annual growth from winter buds is marked in most
of the shoots from strong buds, such as those of the Horse-chestnut
and Hickory. Sucli a bud generally contains, already formed in
miniature, all or a great part of the leaves and joints of stem it is to
produce, makes its whole growth in length in the course of a few
weeks, or sometimes even in a few days, and then forms and ripens
its buds for the next year's similar growth.

42. Indefinite 'annual growth, on the other hand, is well marked
in such trees or shrubs as the Sumac, and in sterile shoots of the Rose,
Blackberry, and Raspberry. That is, these shoots are apt to grow all
summer long, until stopped by the frosts of autumn or some other
cause. Such stems commonly die back from the top in winter, and
the growth of the succeeding year takes place mainly from the lower
axillary buds.

43. Forms of trees determined by the development of the buds. —
The main stem of Firs and Spruces, unless destroyed by some injury,
is carried on in a direct line throughout the whole growth of the tree,
by the development year after year of a terminal bud : this forms a
single, uninterrupted shaft, — an excurrent trunk, which cannot be
confounded with the branches that proceed from it. Of such spiry or
spire-sltaped trees, the Firs or Spruces are characteristic and familiar
examples.

44. On the other hand, when the terminal bud fails to take the
lead regularly, there is no single main stem, but the trunk is soon lost
in its branches. Trees so formed commonly have rounded or spread-
ing tops. The American Elm is a good illustration of this type, in
which the stem is said to be deliquescent.

Supplementary Work. Ecology of Buds

The following outline is meant to suggest some lines of individual research
that may be followed throughout the year in any place where plants grow.
Notes made from nature will not, of course, follow this scheme ; for such a
OUT. OF HOT. — 3

34 LABORATORY STUDIES OF THE ROOT

summary could come only after a good deal of looking into particular cases.
Observations should be numbered in the notebooks; and specimen parts of
the plants whose buds are described should be kept properly numbered, for
determining with certainty what the plants are that have been studied. There
are several popular works from which the names of plants in flower, or of trees
even not in flower, may be made out to some extent. If one learns the use
of the Manual, names may be determined without other help. Assistance
may often be had from a trained botanist through correspondence, if none is
available near at hand.

I. Summer. Growing buds. Protection of the tender tips : against (a) in-
sects, (b) snails (water plants and low wider-herbs), (c) any ot hef animals ?
(d) excessive light, heat, and drying; by means of (a) stipules, (b) petioles
of older leaves, (c) trichomes, (d) convergence and overshading by all the
parts generally, (e) other arrangements.

II. Summer, fall, and winter. Resting (or "winter") buds. A. When
are they formed, in different plants ? B. Sources of danger. Determine some
of these by actual observations on (a) birds — e.g. note the food of flocks of
northern birds that visit your locality in winter — and (b) other animals.
As to temperature, it may be asked, Do buds freeze? Does freezing kill?
Does prolonged freezing kill? Does thawing kill? C. Methods of offsetting
the dangers by (a) special scales (what is the nature, or morphology, of the
scales?), (b) coatings of the parts (wool, glandular secretions), (c) seclusion
(1) under bark, (2) in hollows, (d) other means.

III. Experimental. Earliest date at which buds of different species can be
made to open, within doors. Effects of removing some or all of the scales in
certain species. Do buds grow at all, in diameter or length, between Decem-
ber 1 and March 1, or otherwise change?

V. LABORATORY STUDIES OP THE ROOT
EXERCISE XIV. THE GENERAL MORPHOLOGY OF THE ROOT

The root suggested is that of Shepherd's Purse. (Do not remove
the leaves from the plants.)

Note the general habit of the root system, consisting of one main
root (taproot), and numerous lateral roots and rootlets.

What is the direction of growth of the 'taproot? Of the lateral
roots ? Examine the taproot with the lens for contraction wrinkles.
Of what service is contraction of the roots, in the case of such a plant?

Place some of the fine, fibrous rootlets on the stage of the dissecting
microscope in water, and carefully pick apart with needles, so as to see
their length, branching, and relative slenderness. Can root hairs be
made out? Does the branching show regularity? Is the root jointed
where branches spring out? At what angle do the branches spring?

Chip away one side of the main root to show the wood at the center.
(In doing this, save half or more of the upper part uncut, for later
use.) This is the central cylinder. All outside of this is the cortex
(bark). By scraping and stripping, a distinct external layer, like a
skin, may be detached from the taproot. This resembles the external

LABORATORY STUDIES OF THE ROOT 35

layer of the leaf and stem in being more or less impermeable by water.
Does the. central cylinder of the taproot connect directly with those
of the lateral roots and rootlets?

Experiment 7. — What part of the root conveys liquids up to the
leaves of the shoot? Determine this by cutting off the lower half of
the main root and the ends of some other roots, and placing the still
leafy plant with these cut surfaces in water colored with eosin. After
a tinu cut oft' the cortex on one side of the root, at different levels, to
find whether the eosin water has been taken up ; and, if so, what path
it has followed. Save a thin cross section of the taproot for drawing.
Draw : (1) The general habit of the root system, to show the points
already mentioned. Show the rings or wrinkles due to longitudinal
contraction. (2) A piece of the branching fibrous root (as seen with
the dissecting microscope, and therefore much magnified), showing the
points noted above. (3) Longitudinal section of taproot (short piece),
showing the wood, cortex, and coating, and the connections with
branches ( x 3-4). (4) Cross section of the taproot (x 4-5).

EXERCISE XV. ROOTS FOR CLIMBING

Make a drawing of the given stem with its climbing roots, to show
the mode of occurrence of the roots, whether in rows or not, and
whether at or near the nodes of the stem or not. With the lens,
examine the roots for root hairs. Ts there any sign that they play a
part in the adhesion of the roots to supporting surfaces?

EXERCISE XVI. ROOTS FOR STORAGE

Compare the internal structure of the given root with that of Shep-
herd's Purse. Are all the regions which were observed in that root
found in this one? In what region or regions of the storage root is
thickening most pronounced? In what part or parts is nourishment
stored ? How can you test this ? What part does this root play in the
life history of the plant? Will the root grow — i.e. give rise to shoots
— when planted in a pot of earth ? (Try it.)

Is any part of the stem of the plant present and closely incorporated
with the root? Distinguish root and stem carefully in such a case.

Draw whatever diagrams are necessary to illustrate your notes.

Supplementary Subjects

1. The roots of epiphytic Orchids. Note their origin and structure, and
behavior toward water. What is the hahitat of these plants ?

2. Roots of the Dodder.

3. Contraction of the roots of plants.

4. Direction of growth of roots under influence of moisture.

5. The rate of growth of the roots of seedlings.

6. Koot pressure shown hy guttation.

THE ROOT

VI. THE ROOT

45. Origin. — Roots ordinarily come from stems, not, as
is generally thought, stems from roots. It is true that in

springtime flowering herbs
like the Trillium, and the
Bloodroot (Fig. 25), are
seen to break from the
ground as if produced from
a root; but the subter-
ranean stock in all such
cases is a true stem.

46. Exceptions to the
general rule are not uncom-
mon, for many roots, espe-
cially if severed from the
stem, have a power of
forming afresh within their
tissues, buds developing
into leafy shoots.1

47. The initial stem of
the embryo produces from
its end a root which be-
comes the first or primary
root of the plant. Some
plants keep this as a main

or taproot throughout the whole of their life, and send out
only small side roots (Fig. 42); but commonly the main
root divides off very soon, and is lost in its branches. A
root system is thus formed with no marked central axis.
In plants of large size, as trees, the roots often extend on
all sides, not far below the surface, sometimes to a con-
siderable distance beyond the limits of the aerial parts.2

1 The reproduction of lacking parts (as buds by roots, roots by stems,
and both roots and stems by cut leaves) is termed regeneration. The
faculty is common to many plants, and to not a few animals, especially
those of the lower types.

2 "Those of an elm have been known to fill up drains fifty yards dis-
tant from the tree." — Goodale, " Physiological Botany," p. 235.

25. The Bloodroot, producing in spring
leaves and flowers from an un-
derground stem which is popu-
larly mistaken for a root.

THE ROOT

37

48. Every flowering plant, with some rare exceptions,
has thus at the beginning one or more primary roots de-
veloped from the tip of the caulicle; but

when occasion arises, additional roots are
freely produced from other parts of the
stem. The Poison Ivy is a woody vine,
sometimes assuming a partially erect,
shrublike habit. Wherever, in clambering
over the rocks, the stem finds shade and
moisture, it produces a thick growth of
fibrous, clinging rootlets (Fig. 26). The
higher shoots, rising well above the under
shrubbery, and thus exposed to sun and
air, are quite devoid of them. In this case
the accessory roots owe their existence to
causes which are in a sense accidental, and
they are accordingly said to be adventi-
tious.

49. Any part of the stem may give rise
to adventitious roots, but they come most
readily from the nodes, as may be seen
upon examining almost any creeping plant
(see Figs. 34, 45).

THE FUNCTIONS OF ROOTS

26. Adventitious
-/* T> P i j • roots of the

50. Roots serve as organs of absorption Poison ivy.
and storage, and as holdfasts.

51. Absorption. — They absorb water and dissolved min-
eral matters, and in some cases organic matter left by the
decay of former vegetation, or even the juices of living
plants.

52. Water and salts. — If we uncover the roots of a tree,
we find that they have a bark impermeable by water. This
impermeable covering is thicker or thinner according as it
is older or younger, but is never altogether lacking until
we reach the young rootlets. Even here the surface is
coated with a substance that hinders the free entrance of

88 THE ROOT

water, except for a short distance from the tip backward.
Only the parts most recently formed are active in absorption.

53. The production of new rootlets is thus of high importance.
Accordingly, as long as the plant grows above ground, and expands
fresh foliage from which moisture largely escapes into the air, so long
it continues to extend and multiply its roots in the soil beneath, re-
newing and increasing the fresh surface for absorbing moisture in
proportion to the demand from above ; and when growth ceases above
ground, and the leaves die and fall or no longer act, then the roots
generally stop growing, and their soft and tender tips harden. From
this period, therefore, until growth begins anew the next spring,' is the
best time for transplanting, especially for trees and shrubs.

54. The action of root hairs. — It has already been
noted in the laboratory that the tip of the seedling root is
for a space smooth, but that at a little distance back a
thick covering of root hairs soon arises. These not only
insinuate themselves into the interspaces of the soil along-
side of the root, and suck up whatever water may be

there ; but they apply
themselves closely to the
soil particles, the walls
even becoming lobed and
distorted in order to gain
closer contact with the

27. A root hair, much magnified. It is . ,

seen to be a tubular outgrowth uneven particles compos-

from an exterior cell of the root, jnp. ^he Soil (Tiff. 27).
in this case much distorted. ^ 11

tor adhering to the sur-
faces of the latter are certain substances much needed by
the plant. These substances, mineral salts,1 are not re-
moved by the simple flow of soil water,2 but remain firmly
bound until acted upon by the root hairs. At the points of
contact, the root hairs excrete an acid which acts to release

1 Salts such as potassium nitrate (saltpeter), magnesium sulphate,
calcium phosphate, etc.

2 Fertilizers applied to land and dissolved by the rain are held in the
same manner by the soil, until taken by the roots of the crops. But if
applied when the ground is frozen, the fertilizers do not penetrate the
absorbent soil to the same extent, and much is washed away by surface
drainage, and lost.

THE ROOT 39

the mineral matters in question. These then pass into the
root in solution, and are conveyed to the parts of the
plant where their presence is required.

55. As the food sought becomes exhausted the root
hairs cease to act, and after a short time die and fall away.
Meanwhile further on new hairs have been put forth in
soil lately invaded. These likewise serve their turn and
shrivel. In this manner the root tip in its progress is
followed by a belt of absorptive organs which explore the
soil on every side of the line of- advance.

56. Root hairs are the chief organs for the absorption of
water and dissolved mineral salts, in the usual cases.
They are, however, wanting in many aquatics and even in
some terrestrial plants.

57. Protection of the root
tip. — In growth new tissue
is formed close to the end of
the root (see Fig. 28). The

very forefront, subject to 28. The end of a growing root, tipped

wear and tear by the resist- and protected by the root cap;

* g, the growing point. (Con-

ance Ot the SOll to the root S siderably magnified.)

advance, is furnished with a

shield of tissue, somewhat in the form of a thimble, which
is renewed from the growing point within as fast as it is
worn away externally. This is called the root cap.

58. Aerial roots are such as are produced above ground.
Some of the most highly specialized aerial roots are those
adapted to the absorption of rain and dew. Epiphytes —
that is, plants seated upon other plants, but not living at
their expense — are obliged to depend upon occasional
supplies of water, which the roots take up rapidly at the
time and pass on to the leaves and stem to be stored for
future use. Epiphytic orchids accomplish this by means
of a thick spongy layer covering nearly the entire length of
their numerous aerial roots (Fig. 29).

59- Absorption of organic food.. — The waste from decaying vegeta-
tion is made use of by a very large number of plants having no other
means of support. These are saprophytes. They are mainly Crypto-

40

THE ROOT

gams of small size, but among them are several flowering plants. The
Indian Pipe is common in woods, where its short stems push up in

29. An epiphytic Orchid with numerous aerial roots for the
absorption of rain and dew. — ScniMPEK.1

little groups through the leaf mold. The pale hue of its stem, leaves,
and flower remind one of the toadstools in company with which it
grows. The roots are adapted to absorb organic matters in solution
from vegetable mold.

60- Parasitic roots. — Part of the roots of the Yellow Gerardia are,
or may be, transformed by the development of suckers near their
tips, by which they grow fast to the roots of other plants and steal

nourishment (Fig. 30). At the same time the Gerardia, possessing

•

1 A. F. W. Schimper, " Pflanzen-Geographie," 1898. An account of
plants ID the world -wMe aspects of distribution and adaptation.

THE ROOT

41

green coloring matter, is able like all green plants to provide for itself;
and it does carry on the work of forming plant food in a quite normal

30. Roots of the Yellow Gerardia, some of
them parasitic on the root of a Blue-
berry bush.

way even while taking the sap
of other plants. This is, there-
fore, the case of a partial para-
site.

61. Parasites proper, which
strike their roots into the tissues
of living plants, or form attach-
ments to their surface so as to
suck up their juices, are amongst
the most interesting of all vege-
table forms. Of this sort is the
Mistletoe (Fig. 31),1 the ^seed
of which germinates on the
bough where it falls or is left
by birds ; and the forming root
penetrates the bark and en-
grafts itself into the wood, to
which it becomes united as
firmly as a natural branch to
its parent stem ; and indeed the
parasite lives just as if it were
a branch of the tree it grows

and feeds on. A most common parasitic herb is the Dodder (Fig. 32),
which abounds in low grounds in summer, and coils its long and
slender, leafless, yellowish stems — resembling tangled threads of yarn
— round and round the stocks of other plants; wherever they touch,
piercing the bark with minute and very short rootlets in the form
of suckers, which draw out the nourishing juices of the plants
laid hold of. Other parasitic plants, like the Beech Drops and Pine-

1 Not the Mistletoe proper of the Old World. The plant represented is
an American relative of the well-known European planjt, very much
smaller, and properly denominated the Dwarf Mistletoe.

31. Plants of the Dwarf Mistletoe para-
sitic on a Branch of the Spruce.

42

THE ROOT

sap, fasten their roots underground upon the roots of neighboring
plants, and rob them of their juices.

62. Roots as holdfasts. — This function comes to be

of great importance as
the plants become tall
and have to stand
against the violence of
the winds. And so
the main roots of a
tree, spreading abroad
underground, corre-
spond in girth with
the largest of the
branch trunks spread
in the air above.
They increase, like the
trunk and limbs, by
the annual formation
of wood. Yet notwith-
standing their great
size and strength,
every heavy wind
storm leaves here and
there a tree over-
turned.

63. Roots for climb-
ing are well shown by
the Trumpet Creeper
(Fig. 34). Near the
nodes, on the shaded
and moister sides of
the stem, aeriaj. roots
are produced in longi-
tudinal rows, and become matted together like felt by
means of the numerous root hairs that cover them through-
out. As the young stems of the vine push upward close
to the face of a wall or building, these webs of roots grow
out until tliey strike the stone, when they flatten oiit and

32. Dodder parasitic on the stem of an herb.
Note the absence of leaves (except a
few small scales, I) , the development of
sucking roots, h, and the flower cluster.
The plant has no connection with the
ground, except in the seedling stage.

THE ROOT

h

become firmly glued to the surface. Firm support is thus
p afforded to the ascending creeper.

64. Roots used for storage. — The roots
of almost all plants that
persist for more than a
single season serve, in
common with the stem,
as organs of storage, to
some extent. But their
forms are not altered
for the special purpose

oo. A section through
Dodder and host
plant at the
point where the
haustorium, or
sucker, of the
former pene-
trates the bark
of the host; p,
stem of the para-
site; s, sucker,
piercing to the 34. Roots of Trum-
woodof the host, pet Creeper,

h (much magni- used in clirnb-

fied) . — SAC HS. ing.

35. Thickened storage roots in
cultivated plants. On the
left Carrot, on the right
Radish. In both cases the
root is confl uent above with
an exceedingly shortened
stem bearing the leaves.

of storage in ordinary cases. Yet roots are sometimes
much enlarged to hold the nourishment made by the
plant during one growing season for its use in the next.
Among the plants that owe their early appearance in the
spring to food stored up in a somewhat fleshy root is the
Dandelion (Fig. 42). In certain plants the tendency to a
thickening of the root has been fostered by cultivation
and selection until from the original wild stock, not more
promising in the beginning than some of our common
herbs, such useful food plants as the Beet, Turnip, Parsnip,
and Radish have been produced. These make use of

44

THE ROOT

the taproot alone (Fig. 35). The Anemonella (Fig. 36),
flowering in early spring with the more familiar and

closely related Anemone,
draws upon supplies of
food held in a cluster, or
fascicle, of roots. A fine
example of adventitious
roots, some of which remain
fibrous for absorption, while
a few thicken and store up

37. Roots of the Sweet,
Potato.

food for the next season's
growth, is furnished by the
Sweet Potato (Fig. 37).

DURATION OF ROOTS

65. Roots are said to be an-
imal, biennial, or perennial.
These terms apply also to the
whole plant.

66. Annuals, as the name de-

early spring growth supplied notes> live onlJ for one year>
from a fascicle of storage roots, generally for only a part of the

year. They are of course herbs ;

they spring Irotn the seed, blossom, mature their fruit and seed,
and then die, root and all. Annuals of our temperate climates with
severe winters start from the seed in spring, and perish at or
before autumn. Where the winter is a moist and growing season
and the summer is dry, winter annuals prevail; their seeds germinate

36. Anemonella thalictroides. The

LABORATORY STUDIES OF THE STEM 45

under autumn or winter rains, grow mor? or less during winter, blos-
som, fructify, and perish in the following spring or summer. Annuals
are fibrous rooted.

67. Biennials, of which the Turnip, Beet, and Carrot are familiar
examples, grow the first season without blossoming, usually thicken
their roots, laying up in them a stock of nourishment, are quiescent
during the winter, but shoot vigorously, blossom, and seed the next
spring or summer, mainly at the expense of the food stored up, and
then die completely.

68. Perennials live and blossom year after year. A perennial
herb, in a temperate or cooler climate, usually dies down to the
ground at the end of the season's growth. But subterranean portions
of stern, charged with buds, survive to renew the development.
Shrubs and trees are of course perennial; even the stems and branches
above ground live on and grow year after year.

VII. LABORATORY STUDIES OP THE STEM

At the beginning of the study of the stem, it is well to
recall the fact that a flowering plant typically consists of
root, stem, and leaf. Stems and leaves may be so dis-
guised as not to be readily recognized in their true charac-
ter. Thus some stems are so modified as very closely to
resemble leaves, while others assume the general appear-
ance of roots. Yet there are, with few exceptions, certain
marks of the stem proper even in these dissembled forms.

The Marks of the True Stem

1st. The stem is characterized by a general plan of
construction, as viewed externally, differing essentially
from that of either root or leaf.

What is the Plan ?

2d. It bears appendages at certain definite places.

What are the Appendages?

Where inserted upon the stem ?

3d. If the stem in question is an offshoot from an
older one, its point of origin has a certain definite loca-
tion. Position determines the fact that a lateral member
is a branch, stem, and not a leaf.

46 LABORATORY STUDIES OF THE STEM

What is its Position ?

These are the questions to be kept in mind in the fol-
lowing exercise.

EXERCISE XVII. THE CHARACTERISTIC FEATURES OF STEMS

Red Maple. — Examine with care all marks and features of form
and the position of the branches and buds with respect to certain of
these markings. Examine especially the newest parts. A low power
of the hand lens brings out the desired points well.

Most trees and shrubs upon the approach of cold weather shield the
tender extremities of their stems by numerous scales. When growth
is resumed at the beginning of the next season, the scales fall away,
leaving scars to mark the occurrence of winter. These are to be looked
for on the material in hand, and noted as interesting traces of events
in the recent history of the twigs. But such annual demarkations are
not to be found on all stems. Refer to the questions immediately pre-
ceding this exercise, and answer them in the notes. The sections of
the stem at which leaves are borne are called nodes; the lengths
between leaves are internodes.

Draw the terminal, and one or two adjacent, annual lengths of the
twig — enough to show all the points learned in the study.

EXERCISE XVIII. THE INTERNAL STRUCTURE OF STEMS1

Looking at the plants of the fields about us, we perceive the great-
est variety in the size, proportions, and attitude of stems. In some
the stem is so short as to seem to be quite wanting, the leaves appear-
ing to spring directly from the root. In other cases the stem, elon-
gated, reclines upon the ground, or twines for support upon any object
within reach.

Yet there is a prevailing type. Its erect habit and height most
clearly show the purpose of stems in general. What is this pur-
pose ?

As height from the ground means encounter with winds, the tall
stem must also be strong. Furthermore, the sap has a considerable
distance to travel from the root to the leafy crown, and hence
the conduction of water becomes one of the functions of the stem.

1 See also Chapter XVII. If compound microscopes are available, the
minute structure may be taken up more in detail than the directions here
given require. In any case use should here be made of figures and ex-
planations from Chapter XVII. The cambium region, especially, should
be located even under the dissecting microscope, and its meaning
explained.

LABORATORY STUDIES OF THE STEM 47

These considerations lead us at once to examine the internal struc-
ture. We shall expect to find out whether the internal construction
answers to the uses of the stem or not.

1. A comparison of dicotyledonous and monocotyledonous stems. —

Begonia (dicotyledon^), Asparagus (monocotyledon).

(1) Even a naked-eye examination of the cross sections, held up
side by side to the window light, shows marked differences. Consider
carefully wherein they are alike and wherein dissimilar, and write a
comparative account of the cross sections as you see them.

(2) Place the Begonia section under the highest power of the dis-
secting microscope. Notice the following points : —

(a) The central space is filled with a more or less irregular and
indistinct network, in which some meshes (cells) of tolerably
regular form may be made out.

(6) Outside of this is an interrupted circle of somewhat wedge-
shaped, denser spots, nearer the circumference than the center
of the section.

(c) Exterior to these is a region filled by a network of large cells.
Toward the margin, however, the cells become gradually
smaller.

The outermost layer of cells, which may not be distinguishable, is
of a distinct nature, and forms the epidermis.

The three regions thus noted are characteristic of dicotyledonous
stems. They are (a) pith, (b) hollow cylinder of wood, and (c) bark.
Strictly the bark includes the outer ends of the elongated areas noted
under (ft), and only the inner half or two-thirds is wood. (The lens
will probably show the division line.) In this fleshy herbaceous stem
the wood does not form a complete ring in the cross section, it will be
noticed. The Lilac, soon to be studied, will show an apparent differ-
ence in this respect.

Draw a sector of the cross section, showing the character of the
three regions (x 5 — 10).

(3) Examine in the same manner the section of Asparagus.
NOTE : — (a) The large cells composing by far the greater part of

the section. They are replaced by cells of a different char-
acter in two instances ; namely, in

(6) The scattered darker parts which much resemble the denser
areas in Begonia ; and in

(c) A distinct dense ring, not far from the edge of the section.

Finally there is

(d) The outermost zone, composed of round cells of uniform size

(the epidermis).

The monocotyledonous stem has no separate region of wood includ-
ing pith and surrounded by bark, such as one finds in dicotyledons.
A cylinder of firm tissue (c), giving a degree of rigidity to the stem,

48 LABORATORY STUDIES OF THE STEM

is found at or near the surface. Throughout the loose cellular tissue
(a) the wood is scattered in bundles, or strands (6). The bundles
are tough and add strength to the stem, and, more important still, fur-
nish the means by which water ascends. The sap ducts appear in
the cross section as large circular apertures on the periphery of the
bundles.

Draw a sector (60°) of the monocotyledonous stem ( x 5-10).

2. The woody dicotyledonous stem. — Lilac.

(1) The first cross section examined should be of the end twigs ;
that is, of the stem not more than one year old.

NOTE: — (a) The pith.

(6) The wood, which seems now to be a solid ring. A high power
of the microscope, however, would show traces of pith tissue
running out to the bark between the wood wedges.

(c) The bark, beginning at the outer edge of the wood. Careful
looking, aided by lenses of even moderate power, will show in
the inner bark region a ring of somewhat glistening bodies,
distantly resembling a string of beads. These are the ends of
bundles of bast fibers. What is a possible use of strong fibers
in this position in the twig?

Immediately under the dark outer line of the bark are
several rows of cork cells, the examination of which may
require the use of a compound microscope. What is the use,
to the plant, of this layer of cork ?

Draw a sector of the cross section (90°), to show these parts.

(2) Make smooth cuts across the twig of Lilac where it is one, two,
and three years old respectively. Examine the ends with the lens.
In what part of the stem (what part of the cross section) is new wood
annually formed?

Draw the three cross sections in diagram ( x 3).

EXERCISE XIX. THE STRUCTURE OF WOOD (OPTIONAL)

First, decide which side of the block furnished for examination was
toward the center of the trunk. Then note : —

(1) The annual additions of wood.

(2) The difference in appearance between spring wood and fall

wood. What makes the difference (use lens) ?

(3) The radiating lines, crossing all the annual layers (rnea illary

rays).

These features are seen on the cross-sectional face. Look on the
other faces for the ends of the medullary rays and the sap ducts.
Show by drawings the points learned from the study.
Examine also a piece of board containing a knot. Explain the

LABORATORY STUDIES OF THE STEM 49

nature and origin of the knot. Are trees grown in the open, or those
grown in a thick forest, more likely to give timber free from knots?

EXERCISE XX. THE ASCENT OF SAP IN THE STEM

Experiment 8. — In order to trace the course followed by the sap
current as it passes from the root to the leaves, make use of water
tinged with eosin. Put the cut end of the given (leafy) stem in the
colored water. After fifteen or twenty minutes examine the stem.
If it is translucent, like the Balsam (Impatiens), the course of the
eosin water is readily seen without dissection. Note the branching
of the conducting tissue at the nodes.

If the path of the coloring fluid is not seen from without, dissect.

Having determined the facts, write a statement, and illustrate by a
diagram or diagrams.

EXERCISE XXI. GEOTROPISM OF THE STEM

The manner in which the growing plumule behaves toward the
attraction of gravitation has been seen. It is well to find out whether
the stem retains this power of reaction to the effect of gravity at a
lator date.

Experiment 9. — This may be done by turning an upright potted
plant — as a young Sunflower or a young Nasturtium — into a hori-
zontal position, pot and all. Make a diagram of pot, stem, and one or
two selected leaves. Leave for a day. Then compare with the diagram.
Indicate any changes by making dotted lines for the new positions.

Alternative. Experiment 10. — The leafy scapes of the Shepherd's
Purse (Capsella Bursa-pastoris}, not too old, make excellent subjects for
this experiment. Fit the scape into a small bottle by splitting and
grooving the cork. Fill the bottle quite full of water before inserting
the scape and cork. Fix the bottle to a block with a rubber band, to
keep the bottle from rolling when the arrangement is laid on its side.
After making a diagram of the stem, etc., set it away in a safe place
in a horizontal position until the next day.

Compare with the diagram. Represent any new position by dotted
lines on the original diagram.

Write full notes.

NOTE : — The same scape will show the reaction of the stem to light
in a marked manner, at least if taken while still freely growing.
When the reaction to gravity is completely apparent, and the end of
the scape has become vertical, place the scape, still in its bottle, so that
it faces a window. In front and shading it place an opaque object two
or three inches wide. Draw a diagram of the whole arrangement, and

OUT. OF EOT. 4

50 LABORATORY STUDIES OF THE STEM

note the time. Observe the scape again later, looking for a change
from the original attitude of the stem.

EXERCISE XXII. SPECIAL USES AND FORMS OF STEMS

Creeping or underground stem. — Study the rhizome. Look for
stem, leaf, and root. Which are present? What are the marks show-
ing the true nature of stem, if that is present? What is the distribu-
tion of the roots, if present? If thickened, does the rootstock contain
food in store ?

Draw what is needed to illustrate your notes.

Tuber of Potato. — First, try to distinguish between the tip and the
base of the tuber. By base is meant the end by which the Potato was
originally attached to the Potato plant.

Holding the tuber right end up, examine it. With the lens look
at several minute prominences within the depression of each eye.
These are buds.

Below is a ridge, and frequently at its middle point may be seen
a small, erect scale. What is the morphology of this scale (subtend-
ing a bud) ? Test the pulp Avith iodine. Morphologically, what is
the tuber? AVhat is the proof? What is its purpose in the life history
of the potato plant ?

Draw an enlarged view of the eye, showing ridge, scale, and
rudimentary buds ( x 3-4).

Houseleek. — (Optional.) Examine : (1) The green heads, with
close-set, thickish leaves.

(2) The dull-colored, rootlike parts connecting them. Precisely
whence do the latter spring? In what do they end, and how? Cut
away leaves enough to determine these questions clearly. Have they
any scars, scales, or appendages ? What is their morphology ? Proof ?
Cut a longitudinal section of one of the heads. Note the sudden
enlargement of the axis at the point where the leaves begin to be
crowded. Apply dilute iodine.

Compare the stem of Houseleek with the tuber of Potato in all
respects, — as to organs present, the comparative development of these
organs, the purpose of the whole, and any other points.

Draw the longitudinal section of the head.

Asparagus. — Select a sprig which branches several times. At the
base of every branch at least one small, scalelike structure is found.
What is it? Follow up the successive subdivisions of one of the
branches, arriving finally at the smallest members of the ramification.
At each dividing note a similar scale. Is it found at the foot of the
needlelike "leaves"? If so, what is their morphology? Note the
color of all parts of the plant. What is the function of stem in
Asparagus ?

THF STEM 51

Draw enough of the stem or stems to show the points discovered
(x3).

Crocus. — Remove the scales. What is the morphology of the
denuded bulb?

Draw the stem, showing nodes, internodes, buds, stolons (under-
ground, propagative branches), if present.

Cut a cross section. Is the plant monocotyledonous or dicoty-
ledonous? Test for starch. What is the life history of this plant?

Flowering Quince (Cydonia Japonica).

Draw a thorn, bearing a lateral bud, with accessory buds at the
base, and the subtending leaf scar ( x 3}.

Boston Ivy (Ampelopsis Veitchii). — Are the tendrils associated in
any way with leaves or leaf scars? Answer in drawing (x3). Ex-
amine the tendril itself with the lens. Are there any indications of
leaf formations at the bases of the branches? Answer in drawing
(x5). What is the use of the flattened ends of the branches? In-
clude these disks in one of the drawings.

VIII. THE STEM

69. The stem is the axis of the plant and the stock from
which spring all the other organs. Side stems, or
branches, spring from just above the axils of the leaves.
Leaves are present on the stem of every flowering plant at
some stage of its existence, though they may often be
reduced to the merest rudiments. This is the case with
stems that run along beneath the surface of the soil, where
leaves would be of no use. But the tendency to produce
leaves never quite disappears, and on underground steins
manifests itself in scales and prominences at more or less
uniform distances ; the joints or nodes thus made, serving
to distinguish such stems from roots, which they otherwise
closely imitate.

70. The stem of an annual herbaceous plant is composed
largely of living tissue, and is commonly seen to be green,
pulpy, more or less translucent, and full of sap. A few
strands of woody fiber run through it ; but the general
mass is succulent, and abounds in living substance. As
age and height and the weight of foliage and fruit in-
crease, woody strengthening tissue may be largely devel-

52 THE STEM

oped even in annual stems. If the plant is a perennial,
especially if it grows to a considerable height, the wood
increases and the living tissue becomes a relatively smaller
part of the whole. In the stems of trees the living por-
tions comprise only the growing tips of branches, the
younger bark, and a film of active tissue just outside the
wood. The bark (except those parts freshly formed), and
the cylinders of wood, are essentially dead, and serve
merely mechanical purposes in the support and protection
of that which is alive.

71. The growth of stems. — Stems increase in length at
or near the young tips. In plants of definite annual
growth the number of internodes — or interspaces between
leaves — is predetermined in the bud. Early in the fol-
lowing season these internodes gain their full extension
and thereafter remain fixed in length. Girth increases
through the formation of wood by the living tissue that sur-
rounds the woody cylinder. Growth is, of course, inter-
rupted as often as severe cold or extreme drought sets in ;
and in those parts of the world where this is a regularly
recurring event, the wood is formed in successive layers.
When cut across, the layers appear as rings. Stems of trees
and shrubs grown in temperate climates show in the cross
section the spring wood — laid down when growth is par-
ticularly active — differing in color or texture from the
fall wood. The age of trees, therefore, is easily made out
when the trunk is cut off. Sometimes, however, two
rings are formed in a single season, when midsummer
drought interrupts the regular growth. Allowance must
be made for these cases in estimating the age of trees.

72. The direction of growth. — Most stems grow upward;
that is, toward the light ; for it is the benefit got by full
exposure of the foliage to the sun that has led to tall
stems. Leaves of tall-stemmed plants are raised out of
the shade cast by crowding neighbors.

73. Upright stems include, besides the ordinary rigid
and self-sustaining type, many climbing forms. Certain
ones gain the advantages of elevation by twining upon the

THE STEM 53

stems of other plants for support (Fig. 38), and often
grow until they spread their own leaves above those of the
plants that they encum-
ber. The way in which
such climbers bend from
side to side until they
strike some vertical sup-
port may be told in the
words of Darwin : - t^jj^)} n 38- Twining stem of the

Morning Glory.
" When the shoot of a hop
rises from the ground, the two
or three first-formed joints or
internodes are straight and
remain stationary ; but the next-formed, whilst very young, may be
seen to bend to one side and to travel slowly around towards all
points of the compass, moving like the hands of a clock, with the sun.
The movement very soon acquires its full ordinary velocity. From
seven observations made during August, and on another plant during
April, the average rate during hot weather and during the day is two
hours eight minutes for each revolution ; and none of the revolutions
varied much from this rate. The revolving movement continues as
long as the plant continues to grow; but each separate internode,
as it becomes old, ceases to move."

74. The revolutions are less rapid at night than in the
daytime, but are maintained until some object of support
is met with, when the free extremity still goes on revolv-
ing and the stem shortly encircles the support. The
movement then continues in an upward-winding spiral,
the coils tightening and the twiner steadily ascending.

75. Most species of twining plants wind in a definite
direction. That is, as we look down upon the plant, the
revolving tip moves with the hands of a watch lying face
upward, in some species ; opposite to the hands, in other
species.

76. Another class of climbing plants includes those that
simply clamber in a haphazard fashion through and over
the surrounding herbage. The thorns of many Brambles
and the minute backward-pointing hooks studding the
angles of the stems and the margins of the leaves in

54

THE STEM

The stem and leaves of Galiiim, or
Bedstraw, studded with backward
pointing hooks (magnified).

Galium (Fig. 39), catching on leaves and branches, pre-
vent these climbers from slipping from their supports.

If we attempt to pull
a tangle of Galium away
from the foliage of the
herbs and shrubs over
which it runs, the plant
itself is torn in pieces
before we succeed in
dislodging it.

77. Of special organs
for climbing, the clinging
rootlets of the Trumpet
Creeper have already
been described. Leaves, and parts of leaves serving the
same general purpose, but adapted in a much more
remarkable manner to a climbing habit, will be described
in the next chapter. In the list of specialized climbing
organs there still remain certain stems, modified into
either adherent or twining tendrils.

78. Adhesive disks. — The Virginia Creeper illustrates
the first case. The tips of certain branches are flattened
into disks with an

adhesive face (Fig.
40). This is applied
to the supporting
object, to which it be-
comes firmly glued.
Then a shortening
of the branches by
coiling brings up the
growing shoot close
to the support. This is an adaptation to climbing mural
rocks and walls or the trunks of trees, to which the
vine would not be able to cling by means of twining
tendrils.

79. Twining tendrils. — Some tendrils are leaves or parts
of leaves, as those of Cobcea (Fig. 73). The nature of a

40. Tendrils of Virginia Creeper.

THE STEM

55

41. Tendrils of the Pas
sioii Flower.

tendril is known by its position. A tendril from the axil
of a leaf, like that of the Passion Flower (Fig. 41), is, of
course, a stem, i.e. a
branch.

80. In the young
stage, when still ex-
tended, tendrils are
endowed with motion
and with sensitive-
ness to contact.
Their movements are
like those of twining
stems, — they de-
scribe circles or el-
lipses until brought
against some object.

When, by the curving of the tip, a hold has been secured
upon this object, the tendril coils in a double spiral.
The coil or spiral itself is of importance in all such
cases, for its elasticity prevents a sudden stress caused,
for example, by a blast of wind, from snapping the
tendril off, as might be the result were the tendril
straight and already tightly drawn at the moment of
onslaught.

" I have more than once gone on purpose, during a gale, to watch a
Bryony growing in an exposed hedge, with its tendrils attached to the
surrounding bushes; and as the thick and thin branches were tossed
to and fro by the wind, the tendrils, had they not been excessively
elastic, would instantly have been torn off and the plant thrown .pros-
trate. But as it was, the Bryony safely rode out the gale, like a ship
with two anchors down, and with a long range of cable ahead to serve
as a spring as she surges to the storm." — DARWIN.

81. The tendrils of the Passion Flower are wonderfully sensitive to
slight pressure. In Darwin's experiments, " A bit of platinum wire, ^
of a grain in weight, gently placed on the concave point, caused a
tendril to become hooked, as did a loop of soft, thin cotton thread ^
of a grain. The point of a tendril of Passiflora gracilis began to move
distinctly in twenty-five seconds after a touch, and in many cases after
thirty seconds."

56

THE STEM

82. So-called stemless plants. — At the opposite end
of the scale from the plants with tall stems, rising as high
as possible toward the sources of light, are those that, like
the Dandelion (Fig. 42), reduce the leaf-bearing axis to
the shortest possible span. Owing to the extreme brevity
of the stem, and perhaps as well to the difficulty of

42. Root, shortened stem, buds, and leaves, of the Dandelion.

distinguishing the stem portion from the taproot, these
plants are sometimes spoken of as stemless. A better term
is acaulescent (which literally means becoming stemless).
The summit of the stem — in the Dandelion — is at the
level of the ground, or slightly lower.1 Crowded together
by the shortening of the internodes, the leaves radiate in

1 The roots of some plants, after gaining a firm hold on the earth, con-
tract and gradually draw the stem into the soil.

THE STEM 57

the form of a rosette, and pressing back the grass and
other low herbage, make a way for the inflow of light.
At the same time the stem, with the growing point and
much of the foliage, is safe from the teeth of grazing
animals : though it would be hard to say just how much
this kind of security has had to do with the development
of the shortened stem. For other advantages of the acau-
lescent habit may have played a part in the gradual acquire-
ment of a shortened stem through successive generations
of Dandelionlike plants ; such as the increased moistness
of the half-subterranean situation, and the relatively stable
temperature of the soil.

83. Certain stems develop wholly beneath the surface, as we shall
presently see, the leaves alone, with the flowering axis, appearing above
ground. To such forms as these the Dandelion and other acaulescent
plants offer a natural transition from the ordinary aerial type. In the
buried stems the habit of taking refuge in the soil is fully formed. In
the Dandelion it may be in process of formation. At least we may
see in the latter one stage in the change of habit by which the Jack-
in-the-pulpit, for example (Figs. 50, 173), has become, as to its stem,
a confirmed dweller beneath ground.

84. Thus far only vertical stems, or stems of a more or
less upright character, have been considered. There are
all gradations between these and prostrate or horizontal
forms, many species habitually taking a leaning attitude,
between the vertical and the horizontal.

85. Of the creeping, or repent, kinds the Partridge Berry
is a good example. It frequents moderately shaded situ-
ations, especially open woods, where it runs along upon
the ground, striking root at short intervals and spreading
its small, rounded, evergreen leaves quite close to the sur-
face. Each year it is covered by the leaves fallen from
the trees. These accumulate from season to season upon
the older parts of the stem, which thus finally becomes
partly subterranean through burial by the leaf mold,
loses its leaves, and gradually decays at the older extrem-
ity. The young, growing sections of the shoot, not more
than a year or two old, push forward continually, over
the dead leaves, and thus remain subaerial. Such cases

58

THE STEM

43. Bulblets of the Tiger Lily.

as this perhaps represent the first step in the process of
change by which the ancestors of our Bell wort (Fig. 20)
and Bloodroot (Fig. 25) became subterranean in habit.

86. Stems for propagation; that is, for the establish-
ment of new individual plants. Many plants reproduce
their kind without the intervention of seed. Some part
of the original plant is separated from the parent stock
and develops into a new plant. This is termed vegetative
reproduction, to distinguish it from reproduction by seed.
The Potato is regularly propagated by this method, as
also in the tropics are Sugar Cane, the Banana, and the
Pineapple, none of which ordinarily produce seed.

87. A curious mode of vegetative
reproduction is by the bulblets, or small
bulbs, formed in the axils of the leaves
of certain garden Lilies (Fig. 43), and
often in the flower clusters of the Onion.
They are plainly buds with thickened
scales. They never grow into branches,

but detach themselves when full grown, fall to the ground, and take

root there to form new plants.

88. A stolon is a branch from above ground, which reclines or
becomes prostrate and strikes root (usually from the nodes) wherever
it rests on the soil. Thence it may send up a vigorous shoot, which
has roots of its own, and becomes an

independent plant when the connecting
part dies, as it does after a while.

89. An offset is a short stolon, or
sucker, with a crown of leaves at the end,
as in the Houseleek (Fig. 44), which
propagates abundantly in this way.

90. A runner, of which the Straw-
berry presents the most familiar and
characteristic example, is a long and

slender, tendril-like stolon, or branch from next the ground, destitute
of conspicuous leaves. Each runner of the Strawberry, after having
grown to its full length, strikes root from the tip becoming fixed
to the ground, then forms a bud there, which develops into a tuft of
leaves, and so gives rise to a new plant, which sends out new runners
to act in the same way. In this manner a single Strawberry plant
will spread over a large space, or produce a great number of plants,
in the course of the summer, all connected at first by the slender

44. Houseleek, propagating
by offsets.

I UK STEM

59

runners; but these die in the following winter, if not before, and
leave the plants as so many separate individuals.

91. Subterranean stems and branches. — These are very
numerous and various. The vegetation that is carried on

46. Rhizome of the Iris.

45. Khizoines of the Peppermint.

underground is hardly less varied
or important than that above
ground. All their forms may be
referred to four principal kinds :
namely, the Rhizome, or Rootstock,
the Tuber, the Corm or solid bulb,
and the true Bulb.

92. The rootstock, or rhizome, in its
amplest form, is merely a creeping stem
or branch growing beneath the surface of the soil, or partly covered
by it (Fig. 45).

93. Rootstocks are commonly thickened by the storing up of con-
siderable nourishing matter in their tissue. The common species of
Iris (Fig. 46) in the gardens have stout rootstocks, which are only
partly covered by the soil, and which bear foli-
age leaves instead of mere scales, closely covering

the upper part, while the lower produces roots.

94. A tuber may be understood to be a por-
tion of a rootstock thickened, and with buds
(eyes) on the sides. Of course, there are all

gradations between a tuber

and a rootstock. Helian-

thus tuberosus, the so-called

Jerusalem Artichoke (Fig.

48), and the common

Potato, are typical and fa-
miliar ex-

, ,. 47. Corm or Caudex.
amples of of Trillium.

the tuber.

The stalks by which the tubers
48. Tubers oi Heliantlms tuberosus. are attached to the parent stem

60

THE STEM

are at once seen to be different from the roots, both in appearance
and manner of growth. The scales on the tubers are the rudiments
of leaves ; the eyes are the buds in their axils. The Potato plant
rears annual stems that bear ordinary leaves expanded in the air, to
digest what they gather from it and what the roots gather from the
soil, and convert these substances into nourishment. A large part of
this nourishment, while in a liquid state, is carried down the stem, into
the underground branches, and accumulated in the form of starch at
their extremities, which become tubers, or depositories of prepared solid
food, — just as in the Turnip, Carrot, and Anemonella (Figs. 35, 36),
it is deposited in the root. Taking advantage of this, man has trans-
ported the Potato from the cool Andes of Chile to other cool climates,
and made it yield him a copious supply of food, especially important
in countries where the season is too short, or the summer's heat too
little, for profitable cultivation of the principal grain plants.

49. Cyclamen.

50. Indian Turnip (Arissema).

95. The corm or solid bulb, like that of Cyclamen (Fig. 49), and
of Indian Turnip or Jack-in-the-pulpit (Fig. 50), is a very short and
thick fleshy subterranean stem, often broader than high.

96. The bulb, strictly so-called, is a stem like a reduced corm as to
its solid part (or plate) ; while the main body consists of thickened

scales, which are leaves or leaf
bases. These are like bud
scales; so that in fact a bulb is
a bud with fleshy scales on an
exceedingly short stem. Com-
pare a White Lily bulb (Fig. 51)
with the strong scaly buds of
the Hickory (Fig. 17), and the
resemblance will appear. In
corms, as in tubers and root-

51. Bulb of White Lily. The longitudi-
nal section shows two buds of
the next year.

stocks, the store of food for
future growth is deposited in the
stem; while in the bulb, the
greater part is deposited in the bases of the leaves, changing them
into thick scales, which closely overlap or inclose one another.

THE STEM

61

97. A scaly bulb (like that of the Lily, Fig. 51), is one in which
the scales are thick but comparatively narrow.

98. A tunicated or coated bulb is one in which the scales enwrap
each other, forming concentric coats or layers, as in Hyacinth and
Onion.

99. Stems as foliage. — All green parts of the plant,
whether belonging to the leaf or to the stem, serve the
same purpose as the foliage to some extent ; for example,
the green twigs of a tree and the green stem of an herb.

52. Flattened leaflike steins of Muhlenbeckia ptoty-
clados, bearing flower clusters at the nodes.

A considerable number of plants have come to dispense
with leaves entirely, modified stems doing their work.
Thus, in the Asparagus what appear to be needle-like
leaves are in reality branches springing from the axils of
the true leaves; the leaves themselves being minute, dry
scales. In Muhlenbeckia (Fig. 52) the nodes of the stem

62 THE STEM

are very well marked, but they bear only small temporary
leaves or none at all. The stems are adapted to function
as leaves by being flattened and by retaining the green
color necessary for active foliage. Thus many desert

53. Opuntia Jilipendula. A Prickly Pear Cactus, and
typical desert plant, having a thickened stem with
green rind, numerous protective spines hut no
foliage leaves. The roots are partly transformed
by tuberous swellings into organs of storage ; when
planted they grow, like the thickened roots of the
Sweet Potato.

plants like the Cactuses (Fig. 53) have no foliage leaves.
The green rind takes on their function. The total sur-
face of these plants is thus very small compared with
the surface exposed by a leafy plant of the same bulk,
growing in moist climates. The water that the desert
plants are able to obtain through their roots in the wet

THE STEM 63

season is therefore not lost, or lost only with extreme
slowness, in the dry period.

100. To all more or less flattened stems thus modified
to serve as foliage (e.g. Asparagus, Muhlenbeckia, Prickly
Pear) the name phyllocladia (singular phyllocladium) has
been given.

101. The longevity of trees. — The duration of the stem is the
duration of the plant, for the stem is the permanent seat of life in
plants, the part from which new organs arise and new shoots of the
same individual are produced. When the stem dies, the plant as an
individual perishes.1 In considering stems, therefore, the length of
life of plants is naturally suggested. Annual, biennial, arid perennial
are terms already explained in the chapter on the root. Many of the
perennial herbs, such as the acaulescent kinds, live for a comparatively
long time, without forming any considerable quantity of wood or
much increasing the length of the stem, probably for a dozen or a
score of years.2 The continuance of life in shrubs and trees in
these cases is often great compared with that of human life, and in
not a few cases, is exceedingly great, so that single trees still living are
known to have sprung from the seed long before any but the oldest
of existing nations came into being. "The celebrated Lime of Neu-
stadt in Wiirtemberg is between eight hundred and one thousand
years old ; the age of the Fir of Beque is estimated at twelve hundred
years, and a Yew in Braburn (Kent) is at least as old."3 John Muir
cites two cases of Sequoias, the Big Trees of California, determined
by the annual rings as being respectively thirteen hundred and twenty-
two hundred years old ; though the latter was " not a very old-looking
tree." " Under the most favorable conditions these giants probably
live five thousand years or more, though few of even the larger trees
are more than half as old. I never saw a Big Tree that had died a
natural death ; barring accidents they seem to be immortal, being
exempt from all the diseases that afflict and kill other trees. Unless
destroyed by man, they live on indefinitely until burned, smashed by
lightning, or cast down by storms, or by the giving way of the ground
on which they stand. . . . The colossal scarred monument in the
King's River forest mentioned above is burned half through, and

1 Though, as has been stated, the roots even when cut away — or when
the stern is removed — may produce new buds. But these are out of the
ordinary course of events, and in a sense result in new individuals, not
the continuance of the old.

2 The only available data seem to be casual observations. The sub-
ject is an excellent one for definite observations and record.

8 Strasburger, "Text Book of Botany," 1898, p. 239.

64 THE STEM

I spent a day in making an estimate of its age, clearing away the
charred surface with an ax, and carefully counting the annual rings
with the aid of a pocket lens. The wood rings in the section I laid
bare were so involved and contorted in some places that I was not able
to determine its age exactly, but I counted over four thousand rings,
which showed that this tree was in its prime, swaying in the Sierra
winds when Christ \valked the earth."1

102- Types of adaptation. — Plants are machines fitted to do work
under certain conditions. The work done by the plant is to take cer-
tain materials into itself, move them about, break them up chemically,
recombine them into new compounds, and build up its body, adding
to old parts and organizing new parts. Certain new parts finally
become new individuals. Growth and reproduction, and the moving
of materials for these purposes, are the work of the plant machine.

The conditions under which the work is done are dependent upon
the nature of surrounding materials and the nature of certain forces
affecting the plant. Of materials, there are soil, water, and air ; of
forces, chiefly heat and light. Each of these conditioning factors
varies from place to place. The composition of the soil, the amount
and purity of the water, even the composition and density of the atmos-
phere, change as we go from one part of the earth's surface to another.
So, also, light is intense or feeble, and temperature high or low.

Every new condition requires a new adjustment of the running
parts of the machine. It is peculiar to the machines which we call
plants and animals that they have the power of becoming adjusted to
new or changed conditions. Even in the individual plant there is
often seen a certain degree of the capacity for accommodation. When
we regard generations rather than individuals, this capacity becomes
still further apparent. Finally, when we look at the whole history of
plants we see that the plasticity of the plant machine is in the long
run perfect (within certain limits). Thus, plants become accustomed
to extremes of temperature. Arctic plants remain frozen for months
without harm. At a temperature very near the freezing point, arctic
and mountain plants are often active. On the other hand, tropical
plants resist heat. In the Punjab (India), air temperatures of 120°
Fahr. are not uncommon. Schimper states that in a hot spring of
Venezuela certain low Algae thrive at above 176° Fahr. The vegeta-
ble machine, then, has the power of adapting itself in the course of
time to any kind of heat condition within the absolute death limits.
And heat is taken merely for illustration. Adaptation to light and
shade, or to variations of any other of the external factors of plant
existence, might have been given.

Next, it is to be noted that plants of very different kinds often be-
come adapted to like conditions by taking on much the same structural
1 "The Mountains of California," by John Muir, p. 181.

THE STEM 65

features. That is, the general type of machinery that serves one
species under given conditions comes to be assumed by all the species
living under the same conditions. As a result \ve are able to distin-
guish certain types of adaptation prevailing wherever certain sets of
conditions are found. The adaptation is seen in external form and in
internal anatomy. The types are the most marked where the condi-
tions are extreme.

1. The Xerophytic Type is exemplified in desert plants. The ex-
treme condition is scarcity of water. The plant surfaces from which
moisture might be lost (leaf surfaces, particularly) are in these plants
reduced to the smallest limits. See, for example, Opuntia, in § 99,
which at maturity is without foliage leaves. A similar form is
exhibited by certain Spurges (Euphorbia) and Groundsels (Senecio),
quite unrelated plants. The internal anatomy is characterized by the
development of tissue for water reservoirs, and of a thick waterproof
cuticular covering of the epidermis (see § 526).

Between the extreme desert type and that of ordinary plants there
are all gradations. When leaves are present on xerophytic plants
they are likely to be leathery, or thick and succulent, or thickly cov-
ered with hair ; the pores (§ 527) are sunken in the thick epidermis
and the leaf is often turned edgewise to light and heat. Xerophytic
characters are found in plants growing in dry situations in ordinary,
moist climates.

Other causes besides dryness of soil and air may lead to scarcity of
water in the plant, at particular times or in particular locations. In
temperate climates, for example, the winter brings frozen soil, and
consequent arrest of absorption at the root. Hence, the plants are
placed temporarily in xerophytic conditions, and most perennials meet
the emergency by the loss of leaves. So, also, the coldness of far
northern and high mountain soils produces a condition of drought,
with the resultant appearance of xerophytic characters in the vegeta-
tion. Root absorption may also be diminished by the presence of
salts dissolved in large quantities in the water about the root. Such
an effect is wrought in salt marshes, and on sea shores above the tide,
where the plants show characteristic xerophytic adaptations. Plants
fitted to life in such conditions are termed Halophytes.

2. The Hydrophytic Type. — Submerged plants, and such as grow
largely submerged in fresh water, are in general characterized by a
thin epidermis, weak development of the framework, and large air
passages traversing the entire plant body. These interspaces allow
the penetration of air for respiration to submerged parts, as well as
give buoyancy to floating parts. For characteristic forms of the leaves
see §§ 130-135.

2. The Mesophytic Type of structure is that of plants living under
ordinary conditions. The common tillage plants are Mesophytes.

OUT. OK BOX 6

66 STUDIES OF THE LEAF

It must be understood that the terms, Xerophyte, Hydrophyte,
Mesophyte, are merely abstract designations for general types of
adaptation. When we say Xerophyte, we mean any plant showing
adaptation to a dry habitat. The same plant may be at different
periods of the year mesophytic (as the Maple or Elm in summer) and
xerophytic (as the same tree in winter).

IX. LABORATORY STUDIES OP THE LEAF
EXERCISE XXIII. THE ACTIVITIES OF THE LEAF

Experiment n. — Select a healthy green Nasturtium plant. Place
it in darkness for three days. Then cut one or two leaves, boil them in
water, decolorize them in strong alcohol (this may take a day or so),
and then treat with iodine to determine the presence or absence of
starch.

Meanwhile, when the plant is first taken from darkness, cover a part
of one of the leaves in the following manner : Cut disks from a cork
stopper ; place them on opposite sides of the leaf ; stick two pins through
both corks and leaf, to hold the corks in place. A portion of one leaf
being thus entirely darkened, expose the plant for at least a day in
sunlight. Then test two or three of the leaves, including the partly
darkened one, for the presence or absence of starch, in the same man-
ner as before directed. Compare with the former results.

Where is starch formed in plants? What is one condition of its
production, as determined by this experiment ? (There are other con-
ditions.)1

Experiment 12. — Pour a little water into a fruit jar, enough to
cover the bottom. Put in a few leaves, with their stalks in the water.
Put in, also, a small beaker with limewater. Close the jar tightly.
Place the jar in the dark.

Arrange a second jar, water and limewater, without leaves, and
place it beside the first.

After twenty-four hours examine the limewater in both beakers for
the action of carbon dioxide, as in the experiment on respiration of
germinating seeds.

Experiment 13. — Select a plant with a single stem below, bearing a
good number of leaves. Wrap the pot in sheet rubber, which is to
be brought up around the stem of the plant and securely tied. The
evaporation of water from the pot and soil is thus prevented.

Weigh the plant as thus fixed, and record both weight and time.
In doing this, set the scales in the sun if possible, and having found

1 Experiment 6, from Ganong's "Teaching Botanist," may well he
introduced here if the apparatus is available. See also Appendix, where
important experiments are recommended.

STUDIES OF THE LEAF

67

the weight, leave the plant counterbalanced on the scales. In a
relatively short time it will be seen whether the plant gains or
loses.

Set the plant in a sunny or well-lighted place. If possible weigh
again some hours later the same day ; if not, the next day. Record
weight and time.

Let the plant now remain in darkness as nearly as possible an equal
length of time. Again weigh, and record weight and time.

What has caused the change of weight? (Before the answer is re-
quired, the next experiment will naturally have been done; there will
be additional reason to assign the change of weight to one particular
cause.) What effect has light upon the rate of change?

Experiment I4.1 — Two tumblers, a piece of pasteboard, a piece of
sheet rubber large enough to cover the mouth of the tumbler, and a
leaf, are needed. One tumbler is nearly filled with water. The paste-
board, with a hole in it, is placed on this tumbler. A puncture is
made in the middle of the rubber, the rubber stretched, and the leaf-
stalk put through the puncture. The leaf is now put on the tumbler,
its stalk descends into the water through the hole in the pasteboard.
The blade of the leaf is now covered with the second tumbler, and the
apparatus set in the sun.

In a few minutes an effect, due to the activity
of the leaf under the influence of light and heat,
should be seen.

Experiment 15. — Relative activity of the
upper and under sides of the Begonia leaf. —
Two dry watch glasses are to be placed on oppo-
site sides of a Begonia leaf (still on the plant)
and held in place by a clip, or by two wooden
strips and elastic bands, as in the figure. Two
inclosed spaces are thus made, on the under and
upper faces of the leaf respectively. Neither
should be in direct sunlight. Examine the
watch glasses for a deposition of moisture after
fifteen or twenty minutes, or longer. Which side
of the leaf exhales moisture the more rapidly?

Experiment 16. — Secure two mature leaves
of the India Rubber Plant (Ficus elastica).
After smearing the under face of one and the
upper face of the other with vaseline, as well as the cut end of the leaf
stalk in each case, so as to prevent the escape of moisture from these
surfaces, hang the two leaves side by side to dry. When either one is

1 Experiments 14, 15, and 16 may be given to different pupils, or groups,
simultaneously, as one or two preparations of each experiment will serve
for a whole class or division.

54. Method of holding
watch glasses
(w) upon Begonia
leaf.

68 STUDIES OF THE LEAF

considerably dried, record the result and the conclusion as to which
surface exhales vapor more freely.

Experiment 17. — A growing plant of Nasturtium, which has been
standing for several hours in one position so that the light lias steadily
come from one direction, is to be observed. Do all the leaves face in
one direction ? Or several leaves ? If so, mark the side of the pot
toward which they incline with some distinctive mark (e.g., A.B. 9.80).
Young leaves, or at least those not declining in vigor, should be chosen
for record. In the notebook record the position of one of these leaves
diagrammatically, as seen from above. The diagram will consist of a
circle, for the pot; a radial line (marked le), for the petiole of the
selected leaf; a line across the end of this, for the blade; and an
arrow (marked li) outside the circle, for the direction of the principal
body of light.

Note the attitude of the stem, as seen from the marked side of the
pot. Represent it by a diagram: make a straight level line for
the rim of the pot; another rising from this, for the stem. Record
the time. Now expose the plant to strong light from a new direction.
Indicate this on the first diagram by a second arrow (li'}-

Leave till a change is plain. At length indicate the position of the
selected leaf by new lines (le') on diagram 1, and the attitude of the
stem, as seen from the original side of observation, by a dotted line on
diagram 2. If any movements of leaf blades are discovered, find how
far they are due to the curvings of the petioles.

Experiment 18. — So-called sleep movements.

Note the position of the leaflets on seedlings of the Sensitive Plant
(Mimosa pudica) when standing in the light. Now place over the pot
carefully, without jarring the plants, a box or blackened bell jar, so as
to exclude all light. In fifteen minutes or so, uncover carefully.
What change in the position of the leaves? Oxalis may be used for
this experiment. If Lupine or Bean is used, the time will be longer.
They may be left in a dark closet over night.

Experiment 19. — Sensitiveness of Mimosa.

Use the seedlings of the last experiment. Touch one of the leaflets
very gently. Touch others less gently. Note the several effects in any
one leaf, and if they occur, the resulting effects on surrounding leaves.
Are the cotyledons sensitive? Select a plant which is still in the
normally expanded condition. Press a hot needle against one of the
cotyledons, without shaking the plant. Wait for the effect.

If a large plant is available, apply a match flame to the tip of one of
the leaves. Note what parts are affected in succession, and the manner
in which the effect travels over the plant. Measure the greatest distance
to which the effect is transmitted, and the time taken in transmission.

This experiment may be done before the whole laboratory division,
one plant serving for all. If time and facilities permit, it will be of

STUDIES Of THE LEAF 69

interest to determine the effect of low temperature on the sensitiveness
of the plant ; temperature between 40° and 50°, for instance, to which
the plant has been exposed for a few hours. The effect of varying the
humidity of the surrounding air may be ascertained by keeping some
well-moistened young plants under a bell jar, and comparing with
others kept in a very dry place.

EXERCISE XXIV

(1) The parts of a typical leaf. — Draw the given leaf in simple
outline to show the blade; the petiole, or stalk; the stipules (a pair of
members at the base of the petiole, like leaflets).

(2) The structure of the blade 1 — Examine the blade under the lens
by transmitted light, shielding it from direct light.

NOTE : — («) The translucence.

(6) The distribution of the green color.
(c) The relative thickness of the ribs and the rest of the
blade (use direct light).

Trace the main framework of one half of the leaf, including in the
drawing only the most prominent ribs and their conspicuous connect-
ing veins.

How many ranks or orders of ribs and veins do you distinguish ?
Determine this as follows : Follow the midrib, then one of its large
branches, then one of the main branches from this, — and so on ;
counting the number of turns made to arrive at the smallest veinlet's
end.

Draw a small square to show the veinlets of the two or three lowest
ranks, as seen through the lens.

Experiment 20. — Place a leaf with its stalk in water colored with
eosin, and later trace the water courses of the leaf.

Experiment 21. — Take a wilted leaf, and after noting with care how
flaccid it is, put it entirely under water for a day. Then note again
the degree of rigidity.

Does contained water play any part in the support and stability of
the leaf blade? 2

EXERCISE XXV

Take a shoot of the Pea three or four weeks old at least, with several
leaves fully formed and a growing bud.

Note the stipules. Where is the growing tip of the shoot, and how
is it protected? What two uses do the stipules here subserve? The

1 For the minute structure see Chapter XVII.

2 To determine whether in this experiment water is taken up readily
through the general surface, use several uninjured leaves, some of which
have the petioles raised above water.

70 STUDIES OF THE LEAF

lateral tendrils occupy the same relative positions on the main axis
(or rhachis) of the leaf as what other parts? What is the morphology
of the lateral tendrils? What three very distinct and different offices
does the leaf of the Pea fulfill ?

Draw the entire leaf with its parts labeled. Show (by another
drawing if necessary) the mode of protecting the bud; indicate the
position of the bud by dotted lines.

EXERCISE XXVI. TYPES OF VENATION

Consider the character of the veining, and the arrangement or plan
of the framework, in the given leaves.

Compare and assort the leaves. Divide them into groups according
to the similarities and differences in these respects.

Draw the margins and main structure lines of the several leaves
(half the leaf will show the points wanted).

After the notes covering the above, write a concise description of
each leaf, under the headings (1) Venation, (2) General Shape,
(o) Margin, (4) Apex, (5) Base ; referring to pages 77, 78, and 92-96
of this book for the proper terms.

EXERCISE XXVII. COMPOUND LEAVES

To which of the types of frame plan, studied in the last exercise,
does each of the compound leaves correspond, in the arrangement of
its leaflets ? Are the leaflets jointed to the main stalk ?

Draw the given leaves in simple outline. Label each with the
proper descriptive term (see pages 96-99).

EXERCISE XXVIII. SPECIAL USES OR MODIFICATIONS OF THE

LEAF

Barberry. — Study the leaves subtending the lateral buds or leaf
clusters on a shoot of barberry. What is the use of these leaves ?

Draw two or three examples to show transition from the foliage to
the spinelike condition.

Onion. — The material suggested is the Onion " set," or young bulb,
slightly sprouted. Note the outer, thin scales, — for what purpose are
they formed ? What are they morphologically ? Cut the bulb in half,
lengthwise. Study the parts. Note the stem, producing roots, and
leaves. Some of the outer leaves are thickened, and do not extend
upward. What is their use?

Draw the longitudinal section of the bulb, somewhat enlarged.

Foliage of Acacia (Optional). — What is the morphology of the flat,
green appendages of the stern? Answer after noting (a) their posi-
tion on the stem, (&) direction in which the surfaces look, whether to

THE LEAF 71

sky and earth like normal leaf blades, or to right and left. Do they
belong to the class of leaf formations or that of modified stems ? They
represent how much stem? leaf?

Draw the body in question, with enough of the stem to show the
position.

X. THE LEAP

103. We have seen that as soon as the seedling comes
up the cotyledons are spread, and the leaves of the plumule,
if already formed, are shortly unfolded to catch the sun-
light; and that even within the first day after emerging
from the soil, the leaves of the seedling take on a deep
green color, the sign of healthy activity in plants. In
buds, leaves have been studied in their early stages and
in the resting condition ; and it has been seen how both
above-ground and beneath-ground leaves are prepared long
before they are needed as foliage, and are held in reserve in
order that upon the return of warm weather in the spring
the plants may begin with little delay to make new growth.
The varied developments of the stem, as rigid shafts of
great height, as twining or as climbing stems, have the
object of displaying the leaves to the light to the best
advantage. All these things point to the activity of the
leaf in carrying on vegetable life.

THE OFFICE OF THE LEAF

104. The leaf is doubly active in nourishing the plant.
In the first place, it absorbs, like the root ; only, while
the root takes up liquids and solutions, the leaf takes in
gases. Secondly, the leaf is especially the organ in which
solar energy is caught and stored by the formation of
certain substances. These substances are the food of the
plant, — using now the word food in the same sense in
which it was used in the chapter on seeds and seedlings.
The food formed in the leaf contains energy to be used
in growth and motion.

105. The food provided for the seedling by the mother
plant is of small amount. Very soon after germination

72 rY tHE LEAF

the seedling HI Ustieed itself. In the soil there is no
supply of starch, oil, sugar, or the like, or, if there is a
small proportion of these matters present through the
decay of former vegetation, yet these would not be enough
to furnish material for all the new plants that grow. If
there is none at all, — if, for example, we grow the seedling
in clear sand watered with distilled water, with the addi-
tion merely of a few mineral salts in very small quantity, —
the young plant grows perfectly well. In other words, it
is able to form its own food. This food it makes largely
through the agency of its leaves.

106. Soil and air furnish the raw materials. These are
water, sucked up by the root, and carbonic acid gas (car-
bon dioxide), absorbed by the leaf from the atmosphere.
These two meet in the soft green tissue of the leaf. By
the power of sunlight, in the presence of chlorophyll (the
green coloring matter), the water and the gas are decom-
posed, and their elements recombined in such a manner
that a solid makes its appearance ; namely, starch. Starch
is in its nature very like the living substance itself, and
may be used in growth. It is then food, in the most
appropriate sense of the word. Water, carbon dioxide,
and small quantities of other substances, since they can be
added only indirectly to the living substance, are not food
in the same sense as starch.

107. The formation of organic substance (as starch)
from these raw materials is called carbon assimilation ;
when brought about through the agency of light, as in
all ordinary cases, it is called photosynthesis.

FORM AND QUALITIES OF THE LEAF

108. The form of the leaf results from its use. Thin-
ness gives full exposure to light and good aeration. The
leaf is translucent as well as thin, so that all parts of the
tissue are reached by the energizing rays. It is compara-
tively strong and elastic, — qualities given by the woody
framework of ribs and veins. The strengthening ele-

THE LEAF

73

Leaf of the Quince ;
b, blade; p, peti-
ole ; st, stipules.

ments are also conduits of water and of the prepared plant
food when this is drawn away from the leaf in a liquid
form to other parts of the plant. The smallest veinlets
penetrate to every section of the active green tissue, assur-
ing an abundance of water. That water throughout the
whole body of the leaf plays an important part in keeping
the leaf elastic and outspread is seen when, from lack of
watering, the leaves of plants wilt and
droop.

109. The parts of the leaf. — When
most highly developed, the leaf has
three parts, — the petiole, or stalk, a
pair of stipules at the base of the peti-
ole, and the blade, or lamina (Fig. 55).

110. Stipules. — In the majority of
leaves stipules are quite wanting; if
produced at all, they are in many cases
soon lost. In the Pea, however, where

the terminal part of the blade is converted into a tendril,
the stipules are large and take part in
assimilation. Ordinarily, the stipules
originate when the leaf is very small,
attain their growth early, and overarch
and protect the young and tender blade ;
or, as in Begonia (Fig. 15), the stipules
of each leaf regularly inclose and shield
the younger leaves of the shoot. In very
many winter buds the scales are of the
nature of stipules. The chief use of
stipules is, then, protective.

111. A special modification of stipules to serve
quite other uses is seen in the case of the prickles
of the Locust (Fig. 56).

112. In Acacia spadicigera the stipules are
the developed as hollow thorns, an inch or more in

length, which become the dwelling places of cer-
kles. tain small and exceedingly warlike ants. At the

ends of the leaflets this Acacia bears small food
bodies, rich in fat, and in special glands secretes nectar. These mate-

74

THE LEAF

rials constitute the food of the thorn-inhabiting ants, for whose sub-
sistence the tree seems thus definitely to provide. In return the
warlike ants defend the Acacia from animal foes, in particular from
leaf-cutting insects.

113. The petiole. — The petiole is sometimes lacking-,
and in this case the leaf is said to be sessile. The gen-
eral office of the petiole is to aid in securing the best posi-
tion for the blade in respect to light. This it would do
merely by its length, since the space
available for all the leaves around the
stem is increased in proportion to the
length of the petioles.1 But further

58. A prostrate shoot of Galium. The leaves now dis-
pose themselves in horizontal positions, and with-
out much over-shading of one by another.

57. An erect shoot of
Galium. The
whorled leaves

ahout equally

than this the petiole, by its own move-
ment, so disposes the blade that it

*-

receives the best illumination possible
under anJ Siven circumstances (Figs.
57, 58). If a potted plant, not too old,
is taken from a position where it has
been lighted from above or on all sides, and placed at a
little distance from the window in a room where the light
enters only at one side, and the plant is closely watched,
it will shortly be seen that nearly all the leaves are very
slowly moving. The whole plant indeed seems to be
alive to the new direction of light and gradually turns
its leaves in that direction. This result is effected by
the leaf stalks, though young portions of the stem are
pretty sure to take part in the general movement.

1 Strictly the area in any one plane is proportional to the square of the
length of the lines. If the petioles are doubled in length, the space avail-
able for the blades becomes quadrupled.

THE LEAF 75

114. At the junction with the blade and at the base,
next to the stem, portions of the petiole may possess a
special structure by which more or less rapid movements
are secured when the blade is stimulated through con-
tact or injury or by changes in the intensity of light.
These portions, marked off from the rest of the petiole
and often somewhat swollen, are called pulvini (singular,
pulvinus). They are well seen in the Bean and other
plants of the same family.

115. Of periodic movements executed by the action of
the petiole, the " sleep " move-
ments of numerous plants are to

be noted. Figure 59 represents
the leaflets of the White Lupine
at night. The blade is here
divided into five or more parts,
or leaflets. Each has a short
stalk, or petiolule. When day-
light fails, the petiolules bend
more or less sharply downward.
When this action is most vigor-
ous, as in some of the younger
leaves, the leaflets are brought 59. The " si- of the White
closely together ; and they are
retained in this position with some force. With the return
of daylight the petiolules are stimulated to elevate the
leaflets again.1

116. When the cotyledons of seedlings exhibit sleep
movements, they usually fold upward, the inner faces
approaching each other more or less closely.

117. It must not be supposed that the lowering of
leaves or leaflets in such cases is an act of resting on the
part of the plant ; although Linnseus gave the name

lrTry the effect of keeping seedlings of Clover, Oxalis, Bean, or
Lupine in the dark until late in the forenoon, or even all day. Are the
sleep movements habitual or effected only in response to change of illu-
mination ? Is lamp light or electric light bright enough to wake sleeping
plants ?

76 THE LEAF

" Sleep of Plants" to all such movements from the evident
suggestion of rest. A definite advantage is gained by
the nocturnal position. The surfaces of the blades being
vertical, or nearly so, and the several leaflets brought to-
gether in a cluster (in the case of compound leaves), there
is less likelihood that the leaves will be chilled or, in cool
climates, frost-bitten.

118. The "Sensitive Plant." — The most striking exhibition of
leaf movements after stimulation is perhaps given by the house plant,
known from its peculiar behavior as the Sensitive Plant (Mimosa
pudicd). The merest touch on one of the leaflets causes the suc-
cessive closing together of all the neighboring leaflets, or perhaps all
parts of the entire leaf. If the shock is slightly increased, the effect
may not only traverse the entire leaf and cause it to droop on the
stem, but be transmitted to the other leaves as well.1

119. Leaves without blades. — fn a few cases the blade of the leaf
is quite lacking, while its place is supplied by the enlarged and flat-
tened petiole. Certain Acacias of Australia normally have no other

foliage. In the seedling,
however, leaves appear
bearing blades. As the
seedling grows older, the
petioles of these bladed
leaves are seen to be flat-
tened. Finally the blades
fail altogether, on leaves
produced at a little later
60. Terminal portion of the shoot of a seed- . stage, only phyllodes (phyl-

ling Acacia: 1, the last of the seedling iodia\ ai)Dearino. rFis- 60^

leaves to show true blades; 2 and 3,

bladeless, flattened petioles, or phyl- Tne flattening is vertical,

lodes. so that the phyllode (phyl-

lodium) presents its edges

to earth and sky. This fact, even in the total absence of blade or
blades, would distinguish these formations from normal leaf blades.

The Blade

120. Framework and venation. — The framework consists of wood,
— a fibrous and tough material which runs from tne stem through the

1 The most remarkable effects are produced by applying a flame, as a
match flame, to one of the terminal leaflets. The impulse to contraction
may often be followed from one leaf to another over the whole plant.
Measure the greatest distance to which the stimulus is transmitted.

THE LEAF

77

leaf stalk, when there is one, in the form of parallel threads or bundles
of fibers ; and in the blade these spread out in a horizontal direction,
to form the ribs and veins of the leaf. The stout main branches of
the framework are called the ribs. When there is only one, as in
Fig. 61 ,. or a middle one decidedly larger than the rest, it is called the
midrib. The smaller divisions are termed veins; and their still
smaller subdivisions, veinlets. The latter subdivide again and again,
until they become so fine that they are invisible to the naked eye. The
fibers of which they are composed are hollow ; forming tubes by which
the sap is brought into the leaves and carried to every part.

121. Venation is the name of the mode of veiniug; that is, of the
way in which the veins are distributed in the blade. This is of two
principal kinds; namely, the parallel-veined, and the netted-veined.

122. In netted-veined (also called reticulated) leaves, the veins
branch off from the main rib or ribs, divide into finer and finer vein-
lets, and the branches unite with each other to form meshes of network.
That is, they anastomose, as anatomists

say of the veins and arteries of the body.
The Willow leaf, in Fig. 61, shows this

Reticulated venation of a
Willow leaf. — ETTINGS-

HAUSEN.

62. Parallel venation of the
Lily of the Valley leaf.
— ETTINGSHAUSEN.

kind of veining in a leaf with a single rib. The Maple, Basswood,
and Plane or Buttonwood show it in leaves of- several ribs.

123. In parallel-veined leaves, the whole, framework consists of
slender ribs or veins, which run parallel with each other, or nearly so,
from the base to the point of the leaf, — not dividing and subdividing,
nor forming meshes, except by minute cross veinlets. The leaf of any
grass or that of the Lilly of the Valley (Fig. 62) will furnish a good

78 THE LEAF

illustration. Such parallel veins Linnaeus called nerves, and parallel-
veined leaves are still commonly called nerved leaves, while those of
the other kind are said to be veined, — terms which it is convenient to
use, although these "nerves" and "veins" are all the same thing, and
have no likeness to the nerves and little to the veins of animals.

124. Netted-veined leaves belong, with comparatively few excep-
tions, to the dicotyledonous plants; while parallel-veined or nerved
leaves belong in general to the Monocotyledons. So that a mere glance
at the leaves generally tells what the structure of the embryo is, and
refers the plant to one or the other of these two grand classes. For
when plants differ from each other in some one important respect,
they usually differ correspondingly in other respects also.

125. Parallel-veined leaves are of two sorts, — one kind, and the
commonest, having the ribs or nerves all running from the base to
the point of the leaf, as in the examples already given ; while in
another kind they run from a midrib to the margin, as in the common
Pickerel weed of our ponds, in the Banana, in Calla, and many similar
plants of warm climates.

126. Netted-veined leaves are also of two sorts, as in the examples
already referred to. In one case the veins all rise from a single rib
(the midrib), as in Fig. 61. Such leaves are called feather-veined or
pinna^ej^v^ined^; both terms meaning the same thing, namely, that
the veins are arranged on the sides of the rib like the plume of a
feather on each side of the shaft.

127. In the other case (as in Fig. 15), the veins branch off from
three, five, seven, or nine ribs, which spread from the top of the leaf-
stalk, and run through the blade like the toes of a web-footed bird.
Hence these are said to be palmately or digitately veined, or (since the
ribs diverge like rays from a center) radiate-veined.

128. Since the general outline of leaves accords with the frame-
work or skeleton, it is plain that feather-veined leaves will incline to
elongated shapes ; while in radiate-veined leaves more rounded forms
are to be expected.

129. The shape of the blade. — Infinite variety is ex-
hibited by plants as regards the figure of the blade. Some
of the chief influences to which the forms are owing are
(1) the character of the natural surroundings, (2) the
mode of folding and of growth in the bud, and (3) the
advantage of certain shapes in respect to the equal illumi-
nation of all the leaves.

130. Natural surroundings. — As examples of the influ-
ence of the natural surroundings, or habitat, we may take
aquatic plants with submerged, and again others with

THE LEAF

79

floating, leaves. In general, submerged plants possess

long and narrow, or linear, leaves (Fig.

63). Or, they may have leaves of a more

or less rounded form, but much divided,

or dissected, into linear parts (Fig. 64).

Since submerged plants of many widely

separated families in common show this

type of leaf, — or these types, — the form

must in some way be due to the circum-
stances of life in water. In exactly what

respect these cir-
cumstances call for
linear leaf forms
is, however, an
open question.
They may be ad-
vantageous from
any one or all
of the following
causes. First,
light diminishes
rapidly as depth

of water increases. It will, therefore, be an advantage

for the blade to reach upward as far as possible in its

growth ; that is, to take a linear form.

131. Secondly, the narrow and dissected forms have
been attributed to the scarcity of carbon dioxide and
oxygen in water. The amount of these necessary sub-
stances that will be absorbed by a leaf, other things
being equal, is proportional to the extent of the surface
in contact with the water. The more divisions the leaf
has, or the longer and narrower it is, the greater the
surface for any given quantity of tissue ; and hence the
more rapid the absorption of the dissolved gases.

132. In the third place, Sir John Lubbock has suggested
that, while the forms under discussion do offer a large
amount of surface relatively to the total mass of the leaf,
we must not forget that- the buoyancy of the water favors

64. One of the submerged
leaves of Cabomba, a
near relative of the
Water Lily.

63. Fresh water

Eelgrass.

80 THE LEAF

the dissected or the slender conformation; in so far as the
water supports the weight, to that extent a compact and
rigid framework is rendered unnecessary. He compares
such leaves as those of Cabomba (Fig. 64) to the gills of
fishes, which while in water float apart, but have not enough
strength to support their own weight, and consequently
collapse in air.

133. Finally, it is evident that in running water and
in waves the slender forms give readily to the movements
of the water, and are therefore less likely to be torn than
broader forms would be.

134. Floating leaves show as pronounced a tendency to
become circular as the submerged ones to become linear.
The circle, or ellipse, may be complete with the leaf stalk

65. Floating leaves : a, of the Water Shield ; 6, of the Water Lily.

running to the center, as in the Water Shield (Fig. 65, a).
In this case, the form is said to be peltate. Or the circum-
ference may be interrupted by a cleft, or sinus, leading to
the summit of the petiole (e.g. the Water Lily, Fig. 65, 5).
The point of attachment of blade and petiole is the real
base of the blade. The circle is filled out, in fact, by the
growing backward of the blade at each side of the base.
This leaf is described as orbicular, and cordate (heart-
shaped), or cordate cleft, at the base.

135. We may suppose that the circle is the most advan-
tageous form in leaf building, since the parts are equi-
distant from the petiole, and thus conduction of food

THE LEAF

81

matters to and from the leaf stalk is most easily per-
formed; and that floating leaves are free to acquire this
shape because they do not overshade one another.

136. Again, the rounded forms are plainly better bal-
anced, ride the waves better, and are less likely to be
tipped and partially
submerged. It is im-
portant that the upper
surface of floating leaves
should be kept free, as
is shown by the fact
that they are coated
with a waxy substance
which prevents wetting,
and which causes water
thrown upon the leaves
to roll away in all direc-
tions. The pores which
admit carbonic acid gas «• Leaf °' *e Tulip Tree (Uriodendron).
and oxygen are in this upper surface. The circular blade
with the petiole attached near the center is well adapted
to keeping every part afloat.

137. The influence of the mode of .fold-
ing of the blade in the bud on its final
shape is well illustrated by the leaf of the
Tulip tree (Liriodendron, Fig. 66). The
end of the lamina is seen to be cut off, as
it were, or truncate. There are also pro-
jections, or lobes, on either side. Figure
68 shows how the lobes, and recesses, and
the truncation fit the space which the very
young blade occupies between and around
other parts of the developing bud. Fig-
ure 67 shows the blade, with its two

67. winter bud of halves flatly folded together, in the win-

Liriodendron, , ,

ter bud.

138. The benefit of equal illumination

for all the leaves may well be the cause

with some
of the outer
scales turned
back.

OUT. OF HOT. — 6

82

THE LEAF

68. A young bud of Lirio-
dendron, much en-
larged, showing the
manner in which the
blade of a young
leaf is shaped in its
growth by the con-
figuration of the
parts upon which it
lies folded. — LUB-

BOCK.

of many leaf shapes. Leaves standing side by side on the
same bough or around the same stem are thus shaped
so that they fit well together with
little overshading. Divided and com-
pound blades (see § 177) seem to be
better than entire forms in the matter
of allowing sunlight to filter through
to foliage on lower parts of the stem.

139. Perhaps enough cases have
been given to make it clear that the
philosophy of leaf forms is to be
sought in the circumstances of life
of the different sorts of plants.

140. Division of the blade: the
margin. — The margin of the blade
may be even, or entire, through-
out. Oftener it is more or less in-
dented. If slightly irregular, and
the projections are pretty sharp, the

margin is toothed, or dentate (Fig. Ill) ; or, if the teeth
point forward like those of a ripsaw, the margin is serrate
(Fig. 110). If the depressions are rather deep and sharp,
like cuts, the margin is incised (Fig. 115). Large projec-
tions, especially if somewhat rounded, are termed lobes.
All degrees and kinds of marginal irregularity are similarly
designated by proper terms for the ready description and
recognition of the various species of plants : in two or
three words the botanist may describe any one of the
almost endlessly diversified shapes of leaves so as to give
a definite idea of it.

141. Compound leaves. — The blade is often so deeply
divided that it consists of quite separated parts. The blade
(and the leaf) is then compound (Figs. 59, 124). Each
part often has a stalklet of its own, and the stalklet (or
petiolule) is often jointed with the main leaf stalk just as
this is jointed with the stem.

142 . Leaves with no distinction of petiole and blade. — The leaves
of Iris show one form of this. The flat but narrow leaves of

THE LEAF

83

Jonquils, Daffodils, and the cylindrical leaf of Onions are other
instances. Needle-shaped leaves, like those of the Pine, Larch, and
Spruce, are examples.

LEAVES OF SPECIAL CONFORMATION AND USE

143. Leaves for storage. — A leaf may at the same time serve
both ordinary and special uses. Thus in those leaves of Lilies, such
as the common White Lily, which spring from the bulb, the upper
and green part serves for foliage and elaborates nourishment, while
the thickened portion or bud scale beneath serves

for the storage of this nourishment. The thread-
shaped leaf of the Onion fulfills the same office,
and the nourishing matter it prepares is deposited
in its sheathing base, forming one of the concen-
tric layers of the Onion. When these layers, so
thick and succulent, have given up their store to
the growing parts within, they are left as thin and
dry husks.

144. Leaves as bud scales have already been
studied.

145. Leaves as spines occur in several plants.
A familiar instance is that of the common Bar-
berry (Fig. 69). In almost any summer shoot
most of the gradations may be seen between the
ordinary leaves, with sharp bristly teeth and leaves
which are reduced to a branching spine or thorn.

The fact that the spines of the Barberry produce a leaf bud in their
axils also proves them to be leaves.

146, Leaves for climbing. — The

leaves of several common climbing or
clambering plants, one of which has
been figured in another place (page 54),
are roughened on the ribs and margins
like the stem, as an aid to climbing.
Even without roughening, the outstand-
ing leaves and side-stems of plants of
this general habit support the shoots
as they weave their way through the
thickets and latticed herbage. It is but
a step from the mere resting of the leaf
ro. Tendril leaves of on chance supports to the habit of hook-

jets- . i i

ing °ver them, more or less ; and but

69. The common
Barberry.

Solanum

84

THE LEAF

another step to winding about them in the fashion of a
tendril. The complete adoption of the clasping habit,

taken on in this case
by the petiole, is seen
in the Solanum jas-
minoides of the gar-
dens (Fig. 70) and
the common Clem-
atis.

147. Or the ten-
dril habit may orig-
inate in the blade
itself. Thus the pro-
longed medium portion of the blade in Crloriosa (Fig. 71)
curves round the supporting object. This is a simple
leaf. Several compound
leaves, as those of the Pea
and Sweet Pea, have the
extremity of the main
stalk, or rachis, developed

71. Tendril leaves of Gloriosa superba.

If

72. Tendril leaves of Lathy-
rus Aphaca, the stipules
performing the duty of
foliage.

into a tendril having all
the qualities of the stem-
tendrils before described.
The leaflets also, in these

cases, may be transformed 73- Tendril leaf of Cobsea macrostemma ;

st, main stem of the plant ; If, the
for the Same purpose. In extent of a single leaf.

THE LEAF

85

a> mo^e °^ attachment of the tendril
tips to a support; 6, the clawed ex-
tremity, enlarged.

Lathyrus Aphaca (Fig. 72) only the stipules remain to
perform the offices of the blade.

148. One of the most
remarkable of tendril
leaves is that of the
Cobcea figured herewith
(Fig. 73). The tendril
portion branches several
times. Each branch
again divides and sub-
divides. The final sub-
divisions are clawed
(Fig. 74).

Owing to the dichot-

omous — or two-forked — branching, neighboring claws
cooperate in catching slender objects coming into the axils

of the dichotomy, as the
jaws of a pair of ice tongs
act together in holding the
block of ice. The tendril,
therefore, catches with great
readiness upon anything it
may strike as the leaf is
swayed by the breeze. Yet
the leaf is far from depend-
ent upon the winds for mo-
tion. Like the extremity
of a twining stem, it makes
regular revolutions. The
leaf from which the figure
was drawn made complete
revolutions in one hour and
ten minutes, the end swing-
ing round a circle about one
foot in diameter. The mo-
tion is easy to see, since the
average rate of progress is about one-third the rate at
which the end of the second hand of a watch travels.

75. Coiling of the tendril after having
fastened to a support.

86

THE LEAF

The actual motion is often faster than this, since the for-
ward movement is interrupted by retracings of the path
and by up and down or oblique deviations from the
level course.

149. In case a twig or stem of another plant is encoun-
tered, the tendril bends round it and the clawed extremities
catch in the bark (Fig. 74, a). The several divisions of
the tendril, with their numerous hooks, lay hold on the
newly found support, and soon twist about it, while the
rachis shortens by coiling (Fig. 75), in the manner char-
acteristic of tendrils.

150. The leaves of insectivorous plants. — The habitat
of insectivorous plants is chiefly marshes, like peat bogs.

Those that the student will
be most likely to meet are
the Sundews and Pitcher
Plants. The commonest,
Sundew (Drosera rotundi-
folici), is a little plant,
generally acaulescent, with
its five or six rounded
leaves spread out horizon-
tally in a rosette from two
to four inches in diameter.
The leaves are thickly set
with hairlike organs (Fig.
76), each tipped with a
glistening drop of sticky
secretion. To • judge from
the number of small insects,
mainly gnats and flies, usually found sticking on the leaves
of the Sundew, it seems not unlikely that the plants exer-
cise upon them some attraction, perhaps through an odor,
perhaps only by the brilliance of the clear secretion drops
shining in the sun, and the color of the purplish glands.

151. The gland-tipped outgrowths are tentacles. The
marginal ones are the longest, and when fully spread out
in all directions, double the total diameter of the leaf. If

76. A leaf of Drosera rotundifolia, or
round-leaved Sundew (x2).

THE LEAF 87

a small fly touches the viscid globule at the extremity
of one of these tentacles, he is at once securely held ; the
liquid being extraordinarily sticky, and so tenacious when
drawn out into little strings that considerable motion may
be imparted to the whole leaf through a single filament
before it is broken. In its efforts to free itself, the fly is
likely to strike neighboring tentacles with its legs and
wings. All the tentacles touched begin almost at once to
bend inward, toward the center of the leaf. The fly is, in
fact, finally deposited on the shorter tentacles of the blade.
Then from all sides the tentacles converge toward the cap-
tured insect, and their glands pour upon it secretions of
digestive fluid, which now begins to flow, resembling the
digestive secretions of the animal stomach. The soft parts
of the insect are dissolved and the products of digestion
absorbed by the glands. Subsequently the tentacles re-
expand, and the secretions dry up, so that the remains of
the insect may be blown away or shaken off. The secre-
tions appear again after a time, in readiness for new prey.

152. Bending of the tentacles was distinctly observed
by Darwin ten seconds after excitation. The closing
together of the tentacles takes from one to four or five
hours. The tentacles expand again in from one to seven
days, according to the nature of the exciting object.

153. Pitcher Plants. — Pitcher Plants, of the type repre-
sented by the genus Sarracenia, are also low bog plants.
Their general habit, and the shape of their leaves — the
upward-curving tube, the wing on one side, and the
rounded, more or less arching hood at the apex, — are seen
in the accompanying illustration (Fig. 77). In some
species the hood quite overarches the mouth of the pitcher.
Its surface and that of the throat of the pitcher are set
with stiff downward-pointing bristles. The tube is habitu-
ally half filled with water, in which the fragments of
insects, in all stages of decomposition, may be found in
considerable quantities. In most species these insects
have been lured by secretions of honey to the rim of the
pitcher ; and then slipping on the extraordinarily smooth

88

THE LEAF

77. Sarracenia purpurea, the Pitcher Plant of
the Northern United States.

surface, their descent aided by the direction of the bristly

hairs, they have fall-
en helplessly into the
liquid below. The
liquid exudes from
the tissues of the
leaf itself ; though
the spreading hood
of Sarracenia pur-
purea must catch a
certain amount of
rain. To what ex-
tent the dissolution
of the captured
insects is promoted
by digestive ele-
ments produced by

^^e Ditcher to what

extent by ordinary
decay, is not certain. It is held, however, that the
organic solutions are absorbed and used by the plant.

154. Insects are caught in another
way, and more expertly, by the most
extraordinary of all the plants of this
country, the Dioncea or Venus's Fly-
trap, which grows in the sandy bogs
around Wilmington, North Carolina.
Here (Fig. 78) each leaf bears at its
summit an appendage which opens and
shuts, in shape something like a steel
trap, and operating much like one.
For when open, no sooner does a fly
alight on its surface, and brush against
any one of the two or three bristles that
grow there, than the trap suddenly
closes, capturing the intruder. If the fly escapes, the
trap soon slowly opens, and is ready for another cap-
ture. When retained, the insect is after a time moistened

THE LEAF . 89

by a secretion from minute glands of the inner surface,
and is digested.

155. The Bladderwort, one of the most interesting of our car-
nivorous plants, should be sought in still water of ponds and large
pools — where it is common — and examined under the lens. Nepenthes,
the East Indian Pitcher Plant, is not uncommon in greenhouses. In
nature it grows as an epiphyte on trees.

156. The development of devices for entrapping animals, on the
part of the carnivorous plants, has the following significance. These
plants are found in places where nitrogenous compounds are scarce.
If their roots reach soil, it is merely wet sand or mud, poor in com-
bined nitrogen. Often the plants are aquatic or epiphytic. The
animals caught are rich in nitrogenous food, and so supply just that
nutritive element which could not otherwise be obtained.

157. Duration of leaves. — The leaves of such trees as the Elm,
Maple, Chestnut, Linden, and so on, last but a single season and then
fall off. Their leaves are deciduous; and the trees themselves are
spoken of as deciduous trees, meaning trees with deciduous foliage.
Evergreen leaves last more than one season at least. Those of the
Pines and Firs persist for two to five years, or in some cases more.
In the Conifer, Abies Pinsapo, the age of the leaf reaches sixteen or
seventeen years.

158. The fall of deciduous leaves is not caused by their death.
Even before they begin to turn yellow in the autumn, the disarticulation
is begun which, when complete, allows them to drop away, leaving a
clean scar. Before this event, a large part of the useful substances in
the active tissue of the blade is withdrawn and saved to the plant.
The brilliant colors of autumn foliage are the signs that the living
matter is being chemically changed preparatory to this withdrawal.
Frost and cold have only an indirect effect, if any, in bringing about
the high coloration.

The Arrangement of Leaves

159. It has come to the student's notice in the study of buds and
of the stem that leaves are given off from the stem in somewhat defi-
nite fashion ; at least in such cases as that of the Horse-chestnut,
where they occur in pairs, on opposite sides of the stem. The regu-
larity would not be so apparent in the leafy branch of the Apple.
Yet here, too, a little attention shows a pretty definite system in the
disposition of the leaves. The study of leaf arrangement is called
Phyllotaxy.

160. The attachment of the leaf to the stem is the insertion. Leaves
are inserted in three different modes. They are

90

THE LEAF

Alternate, that is one after another; or with only a single leaf to
each node ;

Opposite, when there is a pair to each node, the two leaves in this
case being always on opposite sides of the stem ;

Whorled or verticillate, when there are more than two leaves on a
node, in which case they divide the circle equally between them, form-
ing a verticel or whorl. When there are three leaves in the whorl,
the leaves are one-third of the circumference apart; when four, one-
quarter ; and so on. So the plan of opposite leaves is merely that of
whorled leaves, with the fewest leaves to the whorl ; namely, two.

161. Phyllotaxy of alternate leaves. — Alternate leaves are distrib-
uted along the stem in an order which is tolerably uniform for each
species. The arrangement in all its modifications is said to be spiral,
because, if we draw a line from the insertion (i.e. the point of attach-
ment) of one leaf to that of the next, and so on, this line will wind
spirally around the stem as it rises, and in the same plant will commonly
bear the same number of leaves for each turn
round the stem. That is, any two successive
leaves will always be separated from each
other lay an equal portion of the circumfer-
ence of the stem. The distance in height
between any two leaves may vary greatly,
even on the same shoot, for that depends upon
the length of the internodes, or spaces between
the leaves; but the distance as measured
around the circumference (the angular diver-
gence, or angle formed by any two successive
leaves) is practically the same.

162. Two-ranked. — The greatest possible
divergence is, of course, where the second leaf
stands on exactly the opposite side of the stem
from the first, the third on the side opposite
the second, and therefore over the first, and
the fourth over the second. This brings
all the leaves into two ranks, one on one side
of the stem and one on the other, and is
therefore called the two-ranked arrangement.
Next is the

163. Three-ranked arrangement, — that of
all Sedges, and of White Hellebore. Here

the second leaf is placed one-third of the way round the stem, the
third leaf two-thirds of the way round, the fourth leaf accordingly
directly over the first, the fifth over the second, and so on. That is,
three leaves occur in each turn round the stem, and they are separated
from each other by one-third of the circumference (Fig. 79).

79. Three-ranked ar-
rangement, shown
in a piece of the
stalk of a Sedge,
with the leaves cut
off above their
bases ; the leaves
are numbered in
order, from 1 to 6.

THE LEAF

91

0-"

5-ranked arrangement : 80,
shoot with its leaves 5-ranked,
the sixth leaf over the first, as
in the Apple Tree ; 81, diagram
of this arrangement.

164. Five-ranked is the next in series, and the most common. It
is seen in the Apple (Fig. 80), Cherry, Poplar, and the greater number
of trees and shrubs. In this case

the line traced from leaf to leaf
will pass twice round the stem
before it reaches a leaf situated
directly over any below. Here
the sixth leaf is over the first;
the leaves stand in five perpen-
dicular ranks, with equal angular
distance from each other ; and
this distance between any two
successive leaves is just two-
fifths of the circumference of the
stem.

165. The above arrangements

of spirally placed leaves are the 80-81.
most common. A three-eighths
or five-thirteenths divergence is
not uncommon. It will be noted
that the precise arrangement may
be indicated by a fraction, thus : the two-ranked by i, the three-ranked
by $, the five-ranked by f, and so on with
the f, T5^, and other arrangements, the whole
fraction indicating the angular divergence of
the leaves, while the denominator shows the
number of vertical ranks. It will be seen
that, beginning with f, any one of the frac-
tions may be derived by adding the numera-
tors of the two preceding fractions for the
following numerator, and in like manner
adding the two preceding denominators for
the new denominator.

166. Phyllotaxy of opposite and whorled
leaves. — This is simple and comparatively
uniform. The leaves of each pair or whorl
are placed over the intervals between those
\.*)Y of the preceding, and therefore under the

^~Jj intervals of the pair or whorl next above.

fj The whorls or pairs alternate or cross each

82. Opposite leaves of Eu- other, usually at right angles, that is, they
onymus, or Spindle decussate (Fig. 82). Opposite leaves, that
Tree, showing the jgj whorls of two leaves only, are far com-

crossi'gTachoth'er moner thau whorls of three or four or more
at right angles. members.

92

THE LEAF

TERMS USED IN THE DESCRIPTION OF LEAVES

[Inserted for reference use by classes making the determination of
plants a part of their course.]

167. Forms of leaves as to general outline. — It is necessary to
give names to the principal shapes, and to define them rather precisely,
since they afford easy marks for distinguishing species. The same
terms are used for all other flattened parts as well, such as petals ; so
that they make up a great part of the descriptive language of Botany.
Beginning with the narrower and proceeding to the broadest forms, a
leaf is said to be

Linear (Fig. 83), when narrow, several times longer than wide, and
of the same breadth throughout.

Lanceolate, or Lance-shaped, when conspicuously longer than wide,
and tapering upwards (Fig. 84), or both upwards and downwards.

OUong (Fig. 85), when nearly twice or thrice as long as broad and
of uniform breadth.

Elliptical (Fig. 86), when similar to oblong but with continuously
rounding sides.

Oval, when broadly elliptical, or elliptical with the breadth con-
siderably more than half the length.

Ovate (Fig. 87), when the outline is like a section of a hen's egg
lengthwise, the broader end toward the stern.

85

86

87

88

83-88. A series of shapes of feathered-veined leaves : 83, linear ; 84,
lanceolate ; 85, oblong ; 86, elliptical ; 87, ovate ; 88, cordate.

Orbicular, or Rotund (Fig. 97), circular in outline, or nearly so.

A leaf which tapers toward the base instead of toward the apex
may be

Oblanceolate (Fig. 89), when of the lance-shaped form, only more
tapering toward the base than in the opposite direction.

Spatulate (Fig. 90), when more rounded abeve, but tapering thence
to a narrow base, like an old-fashioned spatula.

Obovate (Fig. 91), when inversely ovate, that is, ovate with the nar-
rower end toward the stem.

Cuneate, or Cuneiform, that is, Wedge-shaped (Fig. 92), broad above
and tapering by nearly straight lines to an acute angle at the base.

THE LEAF

93

168. As to the base, its shape characterizes several forms, such as

Cordate, or Heart-shaped (Figs. 88, 94), when a leaf of an ovate
form, or something like it, has the outline of its rounded base turned
in (forming a notch or sinus), where the
stalk is attached.

Reniform, or Kidney-shaped (Fig. 96),
like the last, only rounder and broader
than long.

Auriculate, or Eared, having a pair of
small and blunt projections, or ears, at
the base, as in one species of Magnolia
(Fig. 99).

Sagittate, or Arrow-shaped, where such
ears are acute and turned downwards,
while the main body of the blade tapers upwards to a point, as in
the common Sagittaria or Arrowhead, and in the Arrowleaved Poly-
gon um (Fig. 98).

93

90 91 92

89-92. Feather- veined leaves :
89, oblanceolate ; 90,
spatulate; 91, obovate;
92, wedge-shaped.

96 9T

93-97. Various forms of radiate-
veined leaves : 93, 94, cor-
date; 95, 96, reniform;
97, peltate.

99

100

98-100. Feather-veined leaves: 98,
sagittate; 99, auriculate; 100,
halberd-shaped or hastate.

Hastate, or Halberd-shaped, when such lobes at the base point out-
wards, giving the shape of the halberd of the olden time, as in another
Polygonum (Fig. 100).

Peltate, or Shield-shaped (Fig. 97), is the name applied to a curious
modification of the leaf, commonly of a rounded form, where the foot-
stalk is attached to the lower surface instead of the margin, and there-
fore is naturally likened to a shield borne by the outstretched arm.
The common Watershield, the Nelumbo, and the White Water Lily,
and also the Mandrake, exhibit this sort of leaf.

169. As to the apex, the following terms express the principal
variations : —

A cuminate, Pointed, or Taper-pointed, when the summit is more or
less prolonged into a narrowed or tapering point; as in Fig. 101.

94 THE LEAF

Acute, ending in an acute angle or not prolonged point; Fig. 102.

Obtuse, with a blunt or rounded apex ; as in Fig. 103, etc.

Truncate, with the end as if cut off square ; as in Fig. 1(M.

Refuse, with rounded summit slightly indented, forming a very
shallow notch, as in Fig. 105.

Emarginate, or Notched, indented at the end more decidedly ; as in
Fig. 106.

Obcordate, that is, inversely heart-shaped, where an obovate leaf is
more deeply notched at the end (Fig. 107), as in White Clover and
Wood-sorrel ; so as to resemble a cordate leaf inverted.

104 105 106 107 108 109

101-109. Forms of the apex of leaves: 101, acuminate; 102, acute; 103, ob-
tuse; 104, truncate ; 105, retuse; 106, emarginate ; 107, obcordate ; 108,
cuspidate, 109, mucronate.

Cuspidate, tipped with a sharp and rigid point ; as in Fig. 108.

Mucronate, abruptly tipped with a small and short point, like a
mere projection of the midrib; as in Fig. 109.

Aristate, Awn-pointed, and Bristle-pointed, are terms used when this
mucronate point is extended into a longer bristle-form or slender
appendage.

The first six of these terms can be applied to the lower as well as
to the upper end of a leaf or other organ. The others belong to the
apex only.

170. As to degree and nature of division, there is first of all the
difference between

Simple leaves, those in which the blade is of one piece, however
much it may be cut up, and

Compound leaves, those in which the blade consists of two or more
separate pieces, upon a common leafstalk or support. Yet between
these two kinds every intermediate gradation is to be met with.

171. As to particular outlines of simple leaves (or the parts of
compound leaves), they are

Entire, when their general outline is completely filled out, so that
the margin is an even line, without teeth or notches.

Serrate, or Saiv-toothed, when the margin is cut into sharp teeth, like
those of a ripsaw, that is, pointing forwards; as in Fig. 110.

Dentate, or Toothed, when such teeth point outwards, instead of
forwards; as in Fig. 111.

Crenate, or Scalloped, when the teeth are broad and rounded ; as in
Fig. 112.

THE LEAF

95

110

114 115

Repand, Undulate, or Wavy, when the margin of the leaf forms a
wavy line, bending slightly inwards and outwards in succession; as
in Fig. 113.

Sinuate, when the margin is
more strongly sinuous or turned
inwards and outwards ; as in
Fig. 114.

Incised, Cut, or Jagged, when
the margin is cut into sharp,
deep, and irregular teeth or in-
cisions; as in Fig. 115.

Lobed, when deeply cut.
Then the pieces are in a gen- 110-115. Kinds of margin of leaves : 110,
eral way called LOBES. The serrate; 111, dentate? 112, ere-

i . ., , i • , • a nate; 113, repaud; 114. sinuate;

number of the lobes is briefly 115> incjsed.

expressed by the phrases two-

lobed, three-lobcd, five-lobed, many-lobed, etc., as the case may be.

When the depth and character of the lobiug needs to be more par-
ticularly specified, the following terms are employed, viz. : —

Lobed, in a special sense, when the incisions do not extend deeper
than about halfway between the margin and the center of the blade,

if so far, and are

117 more or less round-

ed; as in the
leaves of the Post
Oak, Fig. 116, and
the Hepatica, Fig.
120.

Cleft, when the
incisions extend
halfway down or
more, and especially
when they are sharp;
as in Figs. 117, 121.
And the phrases
two-cleft, or, in the
Latin form, bifid,
three-cleft or trifid,
four-cleft or quadri-
fiL five-cleft or quin-
quefid, etc., or many-
cleft, in the Latin form, multifid, — express the number of the segments,
or portions.

Parted, when the incisions are still deeper, but yet do not quite
reach to the midrib or the base of the blade ; as in Figs. 118, 122. And

116-123. Margins of deeply cut leaves : 116, pinnately
lobed; 117, pinnately cleft; 118, pinnately
parted ; 119, pinnately divided ; 120, pal-
mately three-lobed ; 121, palmately three-
cleft; 122, palmately three-parted; 123,
palmately three-divided, or trisected.

96 THE LEAF

the terms two-parted, three-parted, etc., express the number of such
divisions.

Divided, when the incisions extend quite to the midrib, as in the
lower part of Fig. 119, or to the leafstalk, as in Fig. 123; which really
makes the leaf compound.

172. The mode of lobing or division corresponds to that of the
veiuiug, whether pinnately veined or palmately veined. In the former
the notches or incisions, or sinuses, corning between the principal veins
or ribs are directed toward the midrib : in the latter they are directed
toward the apex of the petiole ; as the figures show.

173. So degree and mode of division may be tersely expressed in
brief phrases. Thus, in the four upper figures of pinnately veined
leaves, the first is said to be pinnately lobed (in the special sense), the
second pinnately cleft (or pinnatifid in Latin form), the third pinnately
parted, the fourth pinnately divided.

174. Correspondingly in the lower row, of palmately veined leaves,
the first is palmately lobed, the second palmately cleft, the third palmately
parted, the fourth palmately divided. Or, in other language of the
same meaning (but now less commonly employed), they are said to be
digitately lobed, cleft, parted, or divided.

175. The number of the divisions or lobes may come into the
phrase. Thus in the four last named figures the leaves are respectively
palmately three-lobed, three-cleft (or trifid), three-parted, three-divided.
And so for higher numbers, as Jive-lobed, Jive-cleft, etc., up to many-lobed,
many-cleft, or multifid, etc. The same mode of expression may be used
for pinnately lobed leaves, as pinnately seven-lobed, -cleft, -parted, etc.

176. The divisions, lobes, etc., may themselves be entire (without
teeth or notches), or serrate, or otherwise toothed or incised ; or lobed,
cleft, parted, etc. : in the latter cases making twice pinnatifid, twice
palmately or pinnately lobed, parted or divided leaves, etc. From these
illustrations one will perceive how the botanist, in two or three words,
may describe any one of the almost endlessly diversified shapes of
leaves, so as to give a clear and definite idea of it.

177. Compound leaves. — A compound leaf is one which has its
blade in entirely separate parts, each usually with a stalklet of its own ;
and the stalklet is often jointed (or articulated) with the main leaf-
stalk, just as this is jointed with the stem. When this is the case, there
is no doubt that the leaf is compound. But when the pieces have no
stalklets, and are not jointed with the main leafstalk, it may be con-
sidered either as a divided simple leaf, or a compound leaf according
to the circumstances. This is a matter of names where all intermedi-
ate forms may be expected.

178. While the pieces or projecting parts of a simple leaf blade are
called lobes, or in deeply cut leaves, etc., segments or divisions, the sepa-
rate pieces or blades of a compound leaf are called LEAFLETS.

THE LEAF

97

124^126. Pinnate leaves : the first with an odd leaflet
(odd-pinnate) ; the second with a tendril in
place of uppermost leaflets ; the third abruptly
pinnate, or of even pairs.

179. Compound leaves are of two principal kinds, namely, the
pinnate and the palmate; answering to the two modes of veining in
reticulated leaves, and to the two sorts of lobed or divided leaves
(Figs. 116, 120).

180. Pinnate leaves are those in which the leaflets are arranged on
the sides of a main

leafstalk ; as in
Figs. 124-126. They
answer to (he feather-
veined (i.e. pinnately-
veinecT) simple leaf;
as will be seen at
once on comparing
the forms. The leaf-
lets of the former
answer to the lobes
or divisions of the
latter; and the con-
tinuation of the peti-
ole, along which the
leaflets are arranged,
that is, the leaf rachis answers to the midrib of the simple leaf.

181. Three sorts of pinnate leaves are here given. Fig. 124 is pin-
nate with an odd or end lea/let, as in the Common Locust and the Ash.
Fig. 125 is pinnate with a tendril at the end, in place of the odd leaflet,
as in the Vetches and the Pea. Fig. 126 is evenly or abruptly pinnate,
as in the Honey Locust.

182. Palmate (also named digitate} leaves are those in which the
leaflets are all borne on the tip of the leafstalk, as in the Lupine,

the common Clover, the Virginia Creeper,
the Horse-chestnut and Buckeye (Fig. 127).
They evidently answer to the radiate veined
or palmately veined simple leaf.

183. Either sort of compound leaf may
have any number of leaflets; yet palmate
leaves cannot well have a great many, since
they are all crowded together on the end
of the main leafstalk. Some Lupines have
nine or eleven ; the Horse-chestnut has
seven, the Sweet Buckeye more commonly
five, the Clover three. A pinnate leaf often
has only seven or five leaflets, or only three,
as in the Beans of the genus Phaseolus, etc. ; in some rarer cases only
two; in the Orange and Lemon and also in the common Barberry
there is only one. The joint at the place where the leaflet is united

OUT. OP HOT. 7

127. Palmate (or digitate)
leaf of five leaflets
of the Sweet Buck-
eye.

THE LEAF

with the petiole distinguishes this last case from a simple leaf. In
other species of these genera the lateral leaflets also are present.

184. The leaflets of a compound leaf may be either entire (as iu
Figs. 124-126), or serrate, or lobed, cleft, parted, etc. ; in fact, may pre-
sent all the variations of simple leaves,

and the same terms equally apply to
them.

185. When the division is carried
so far as to separate what would be
one leaflet into two, three, or several,
the leaf becomes doubly or twice com-
pound, either pinnately or palmately, as
the case may be. For example, while
the clustered leaves of the Honey
Locust are simply pinnate, that is, once
pinnate, those on new shoots are bipin-
nate, or twice pinnate, as in Fig. 128.
AVhen these leaflets are again divided
in the same way, the leaf becomes
\hrice pinnate, or tripinnate, as in many
Acacias. The first divisions are called
pinnce; the others, pinnules; and the
last, or little blades themselves,
leaflets.

186. So the palmate leaf, if again compounded in the same way.
becomes twice palmate, or, as we say when the divisions are in threes,

twice ternate (in Latin form biternate*)', if a
third time compounded, thrice ternate or triter-
nate. But if the division goes still further,
or if the degree is variable, we simply say
that the leaf is decompound; either palmately
or pinnately decompound, as the case may be.
Thus, Fig. 129 represents a four times ter-
nately compound (in other words a ternatelij
decompound} leaf of a common Meadow Rue.

187. When the botanist, in describing

129. Teruately decom- leaves, wishes to express the number of the
leaflets, he may use terms like these : —

Unifoliolate, for a compound leaf of a single
leaflet; from the Latin unum, one, and foliolum, leaflet.

Bifoliolate, of two leaflets, from the Latin bis, twice, and foliolum,
leaflet.

Trifoliolate (or ternate), of three leaflets, as the Clover, and so on.
Palmately bifoliolate, trifoliolate, quadrifoliolate, plurifoliolate (of
several leaflets), etc. : or else

128. A twice-pinnate (abruptly)
leaf of the Honey Locust.

pound leaf

Meadow Rue.

of

LABOE4TORY STUDIES OF THE FLOWER 99

Pinnately bi-, trt-, quadri-, or pluri-foliolate (that is, of two, three,
four, or several leaflets), as the case may be : these are terse ways of
denoting in single phrases both the number of leaflets and the kind
of compounding.

XI. LABORATORY STUDIES OP THE FLOWER

The object of the flower is the bearing of seed for the reproduction
of the plant. It is best to examine at once the seed rudiments with
the parts in which they are borne, and those equally important prod-
ucts, the pollen grains, which act upon the seed rudiments to make
them capable of growth into seed, as well as the organs which bear
the pollen. After that the less important, though more showy, parts
of the flower are to be studied.

EXERCISE XXIX. THE RUDIMENTS OF THE SEEDS

Look the flower over as well as possible, without pulling it to
pieces, to see what the various parts are like. Note in a general way,
without drawing, the number, arrangement, and varied shapes of the
parts.

Remove the members at one side in order to get at the central
organ, the pistil. Cut this off at the end gradually until white, seed-
like bodies — the ovules — are brought to view.

Cut down the sides wherever necessary in order to split off the
outer walls, so as to leave the ovules undisturbed and exposed to view
in their natural positions. "*

Examine with the lens, noting: —

(1) the arrangement ;

(2) the number of rows hi each compartment;

(3) the attachment of the ovules;

(4) the number of compartments.

The hollow portion of the pistil is the ovary; its compartments
are termed cells. The middle part of the ovary, where the walls of
the cells meet, is the axis. The partitions between the cells are the
dissepiments. The surface where the ovules are attached in a cell is
the placenta ; if there are several cells there are several placentae. The
manner in which the ovules are placed, as concerns attachment, is the
placentation. If they are attached to the axis the placentation is
axile ; if to the walls of the cell, it is parietal.

Add to your notes a few words describing the pistil in hand as to
the number of cells and th'e placentation.

Taking up a fresh flower, for the moment, note how the pistil ends
above. The somewhat enlarged end with granular or loose tissue on
the surface is the stigma. Below this the pistil is often narrowed, so

100 LABORATORY STUDIES OF THE FLOWER

that the stigma is raised on a more or less slender column, the style.
When seated on the ovary the stigma is sessile. Draw the pistil and
label the parts.

Draw the ovary with walls removed, side view, to show the ovules
in position (x 4-6); end view, to show placentation and number of
cells of ovary (x 3-5).

Examine the ovules, removed, with the highest power of the dis-
secting microscope, or, perhaps, with a compound microscope. Draw a
side view, including the little stalk of attachment to the placenta.

EXERCISE XXX. THE POLLEN

Examine the organs standing next to the pistil — the stamens.
Find one opened and shedding its yellow, mealy contents, the pollen ;
and one not yet opened.

f.f a high power is available examine and draw the individual
grains.

Cut a thin cross section o?. the unopened stamen to show the
cavities in which the pollen is produced — the pollen sacs.

Note where the pollen sacs open, or dehisce.

Draw a stamen (x 2-3). The stalk is the filament. The pollen-
bearing terminal portion is the anther. The continuation of the fila-
ment, or the part that connects the pollen sacs, is the connective. Label
all parts. Draw anther, side view, to show dehiscence ( x 3-5) ; cross
section of anther showing the pollen sacs ( x 5-10).

The really essential parts of the flower have now been seen. The
ovules, acted upon by the pollen, give rise to new plants. Many
flowers have no other parts than pistils or stamens ; that is, no pro-
tecting envelopes such as the brightly colored leaves of the flower
which i> now being studied. These leaves are of great service in pro-
moting the transfer of pollen from flower to flower and in protecting
the pistil and stamens while they are maturing. But they take only
an indirect, not a strictly necessary, part, in reproduction.

EXERCISE XXXI. THE FLORAL ENVELOPES

Are there two sets of the floral leaves ? Do they differ in any
respect except in position ? Draw one member of each set if there is
a difference.

Examine one of the floral leaves under the lens with transmitted
light, shading meanwhile from direct light, to discover any venation.
If any is found indicate this on the drawing.

The leaflike organs together are the perianth. When in two dis-
tinct sets, the outer set is the calyx, the members being the sepals ; the
inner is the corolla, made up of petals.

LABORATORY STUDIES OF THE FLOWER 101

EXERCISE XXXII.

THE PARTS OF THE FLOWER IN RELATION
TO ONE ANOTHER

Cut a new flower neatly in halves lengthwise.

Draw the half flower as seen from the cut side, to show : —

(1) the shape of the pistil;

(2) the relative positions and heights of the other parts.

The summit of the flower stem, generally somewhat enlarged, from
which the organs spring, is the receptacle.

Looking down upon or into the flower, endwise, make out the rela-
tive position of the sepals, petals, stamens, and cells of the ovary.

When these have been made out definitely, make a diagram of the
flower as seen from above, in the following manner : —
1st. Represent the ovary in cross section.

2d. In a circle — if so found in the flower — around the ovary,
roughly indicate the cross sections of the anthers, properly
placed as regards direction from the ovary cells.
3d. Represent petals by arcs of a
circle, properly placed ; the
arcs may be thickened a
little at the middle to repre-
sent midribs of the petals.
4th. Outside these draw similar
figures for, the sepals, in
the proper places with
respect to the other parts.
The diagram thus constructed
shows the ground plan of the flower.
The annexed figure shows the method
of constructing such diagrams.

In case any two parts of the
flower are grown together, as two
petals, or a petal and a sepal, as
sometimes happens, this fact may
easily be indicated in the diagram
by drawing a dotted line between
the conjoined members.

129 a. Flower and floral diagram
of Trillium.

EXERCISE XXXIII. THE ARRANGEMENT OF THE FLOWERS ON
THE STEM OR STEMS : OR INFLORESCENCE

When flowers come in clusters they are found in one of two differ-
ent types of inflorescence. Either a flower, early produced, ends the
main stem of the cluster, so that no further growth of the cluster in
the line of the axis is possible ; in this case new flowers are produced
only on side branches, and these side flowers are younger than that

102 LABORATORY STUDIES OF THE FLOWER

on the central axis of inflorescence; or the cluster goes on growing in
the main axis and putting out new flowers for a time, — so that the
lower flowers are older, the upper ones younger. The first type is
called determinate, or cymose ; the second, indeterminate, or racemose.

Determine the type of inflorescence in the material furnished.
• Draw a diagram of the arrangement of the flowers, letting lines rep-
resent the stems, branches, and individual flower stalks (or pedicels),
and putting at the ends dots for the flowers, larger for the older, and
smaller for the younger, flowers.

Turn to the figures of the different sorts of cymose and racemose
inflorescences (page 140 and following), and select the proper term
for the material in hand.

EXERCISE XXXIV. THE FLOWER OF A CONIFEROUS PLANT

1. The Staminate Flower

Cut a longitudinal section. Note the positions of the stamens.
Draw the outline of the whole flower (or cone) and the central axis,
and indicate the position and outline of two or three stamens.

Detach one stamen. Note its general form, and the number of
pollen sacs. Do the sacs lie on the under or the upper side of the
stamen? Find out about the place where the sacs open for the emis-
sion of pollen. Draw one stamen, so as to show the pollen sacs
opened.

Are there any scales or other structures answering to the perianth
of an angiospermous flower?

Note the size and number of the pollen grains and examine with the
compound microscope if possible.

2. The Pistillate Flower

Before cutting into the flower (or cone), note the arrangement of
the scales.

Note also the outstanding edges of the scales ; this feature is related
to the method of pollination.

Draw a simple outline of the cone, and then indicate diagrammati-
cally the arrangement of the scales ; that is, draw simple continuous
lines for the boundaries of the rows of scales. Can you see rows in
more than one direction ? If so, draw the diagram accordingly.

Break the cone across. Separate one of the scales. On careful
examination it will be seen that the scale is double, so that there
seem to be two scales with a common base. The under one is the
smaller. The upper one is the placental scale, or ovuliferous scale.

Examine the upper surface of the placental scale for two promi-
nences near the base. Each has a few short filaments projecting
toward the axis of the cone. The prominences are the ovules. The

THE FLOWER

103

filaments serve to catch the pollen when it has fallen upon the cone
and down between the scales to the ovules.

Draw upper and under views, to show the two scales and the ovules.

FURTHER WORK ON THE FLOWER

The study of the flower, as far as many of the details are concerned,
depends so much on the available material that specific directions had
best be left to the teacher.

For suggestions as to systematic study of flowering plants, see the
Appendix.

XII. THE FLOWER
GENERAL MORPHOLOGY OF THE FLOWER

188. The flower is destined to produce seed ; the seed,
to bring forth a plant of the next generation. At the
center of the flower bud, in their proper cavities the
beginnings of the seed rudiments are distinguishable long
before the flower is ready to open. If, after the bud

130. A flower of the Cherry Tree cut
open to show the single ovule
in its receptacle, the ovary.

finally Ullfolds and the several 131- The ovary of Mandrake
., , opened at one side to

envelopes separate, the receptacle show the numer0us

seen within is CUt Open, One Or ovules, each contain-

ing the starting point

two, often several, and not uncom- of a new plant,

monly very many, rounded bodies

are discovered, — white, shining, and translucent, spring-
ing in definite and orderly arrangement from the walls
or the central axis. These are the ovules (Figs. 130, 131).
To these small vesicles the life of the species of plants
which bear them is for a time intrusted. Each one car-

104

THE FLOWER

ries within it an inheritance of the racial characteristics:
the forms of the leaves, the colors of the flower, the height
and character of the stem, even the movements of the
parent plant are passed down through the ovule (with the
aid, as will shortly be seen, of the pollen) to the plant
which is to spring from the ovule.

189. The ovule-bearing organ is the pistil (Fig. 132).
Three parts are usually distinguishable : the hollow lower
portion is the ovary ; the column sur-
mounting this is the style; and at the
tip of the style — sometimes on its
side — a part of the surface without
epidermis and moist or even sticky,
is termed the stigma. The style may
be lacking ; the stigma is then sessile
on the ovary (Fig. 131).

190. The flower commonly contains
but one pistil. Such flowers as those
of the Pea and Bean illustrate the
simplest case of all, when the pistil is
solitary and has but one cavity with
ovules borne on but one v side -of it. In the Buttercup
(Fig. 133) there are many pistils, each simple, with a
single cavity, containing but a
single ovule. In the majority
of plants, however, the two or
more original pistils grow up
from a very early stage in their
development united throughout
the greater part of their length.
Compound pistils are thus

formed. The several combined pistils are then termed
carpels.

191. The portion of the ovary to which the ovules are
attached is the placenta, and the manner in which the
ovules are distributed on the interior surfaces of the. ovary
is the placentation. When the ovules are numerous,, the
placenta is apt to be a well-developed cushion or projection

132. Pistil of Wild Ge-
ranium ; ov, ova-
ry ; stl, style ;
stg, stigma.

133. Flower of the Buttercup.

THE FLOWER

105

of some sort (see Fig. 138).
when no special outgx jwth
is to be seen,

But the name applies even

134. The several distinct pistils of a
single flower. One cut across,
and one cut lengthwise, to show
the placentation.

192. Types of ovary and
placentation. — When the pis-
tils are separate and the ovaries,
therefore, one-celled, the typical
arrangement of the ovules in
each ovary is in a double verti-
cal row on the side nearest the
center of the flower (Fig. 134).
A solitary ovule may be sus-
pended from the top of the
cell, or spring from the side

toward the flower axis, or rise from the bottom.

193. When the pistil is compounded of several carpels, various
arrangements of the parts are possible. The common one is that

194. With two or more cells
and axile placentation (Figs. 135-
137). — Such a pistil is*just what
would be formed if simple pis-
tils, like those of the Larkspur,
pressed together in the center
of the flower, were to cohere by
their contiguous faces. In such
a case the placentae are naturally
axile, or all brought together in
the axis or center. The ovary
has as many internal partitions,
or dissepiments, as there are car-
pels in the composition. When
such pistils ripen into pods
they often separate along these
lines into their elementary car-
pels.

195. One-celled, with parietal placentae (Figs. 138, 139). — In this
not uncommon case it is conceived that the several original carpellary
cavities are thrown into one as the organ grows. The ovules now
spring from the lines of junction of the different carpels. A placenta
belongs here half to one carpel, half to another. At each placenta a
double row of ovules is apt to be found ; but the two rows originate
from distinct carpels. The number of carpels is still to be told from
the number of placentae. The placentation is here termed parietal.

135 136 .137

135-137. Pistils: 135, a Saxifrage, the
carpels or simple pistils united
below, free above; 13(5, common
St. Johnswort, the styles of the
carpels distinct ; 137, another St.
Johnswort, the carpels united
throughout.

106

THE FLOWER

196. One-celled, with free central placenta. — The free central
placenta of the Pink (compare Fig. 140) y have come about by the
dissepiments having been suppressed in growth.
Indeed, traces of the original partitions are often to
be detected. On the other
hand, it is equally supposable

138. Placentation
of Parnas-
sia.

r

Placentation
of Drosera
filiformis.

140. Pistil of Spergularia rubm,
one of the Pink family, with
free central placentation.

that in the Primrose (Fig. 160) the free central placenta has been
derived from parietal placentation by the united carpels bearing ovules
only at the base. Now, however, the placenta arises directly from the
end of the floral axis, not from the carpels.

197. To the great majority of flowers with which one meets, one
or another of the above types will apply. These types exhibit most

clearly the structural principles of the
pistil. Occasionally, some different
mode of disposing the ovules or of
separating the ovary into chambers
will be discovered.

198. Pistils of the Gymno-
sperms. — These are so distinct
and the group of plants which
produce them is so important
that they need a separate de-
scription.

199. The fertile flowers of the
Pine1 and other trees of the
same group appear in early spring
as small richly colored cones
(Fig. 141). The scales are soft,
and though not very thin are

1 What is here designated a single female flower is also spoken of as
an inflorescence.

141. The flower of a Gymno-
sperm. At the right a
single carpellary scale
bearing two ovules.

THE FLOWER 107

rather leaflike. Each fertile scale bears on its upper sur-
face near the base a pair of ovules. In such flowers the
pistils, therefore, are not closed, and the seed throughout
its history is naked, i.e. exposed. Accordingly, the cone-
bearing trees and their relatives are designated as GYMNO-
SPEBMS (naked seeded).

200. The corresponding term for plants with closed
ovaries is ANGIOSPERMS. Angiospermous flowers will be
meant in this chapter unless otherwise stated.

201. The stigma has been described as a definite portion
of the surface of the style, or, when the style is lacking,
of the ovary. When the tip of the style is enlarged in
a knob, or branched, or finely dissected in a plume (Fig.
166), it is convenient to speak of the whole organ — and
not merely the surface — as the stigma.

Under the lens and even to the naked eye the stigmatic
surface is distinguished by a granular texture and often
by a viscid secretion, designed to secure the pollen grains
which fall upon it or are brought to it.

202. For the ovules are not the sole conceptacles of
racial life as it is passed onward from one generation to
the next. Other and simpler bodies produced in the
flower are equally freighted with inheritance, namely, the
individual pollen grains, emitted in multitudes as yellow
dust by the floral or-
gans standing around

the pistil or pistils.
Each " grain " viewed

0 . 142. Various forms of pollen, magnified,

through the microscope illustrating the manner in which the

is 86611 to be a Spherical wal1 is sculptured in different species

body. (Fig. 166) -in

many cases, however, elongated or otherwise modified —
of the simplest description as regards structure. It con-
sists of a minute portion of living substance of jellylike
consistency, surrounded by a tough elastic coat or wall.
As will shortly be seen, this body is capable of growth,
and plays an equally important part with the ovule in the
reproduction of plants.

108

THE FLOWER

203.

p

The pollen-bearing organ is the stamen (Fig. 143)
Its parts are the stalk, called
the filament, and the anther,
containing the pollen in pollen
sacs. In the young condition
of the stamen four longitudi-
nal pollen sacs are found.
The whole mass of tissue
filling these sacs is finally con-
verted to pollen. At matu-
rity, if not before, the wall
between the two cavities on
143. a, a stamen ; p, pollen sac: c, the same side of the anther

connective; f, tilameut; b, IT i •

a stamen with the anther commonly disappears, leaving
cut through at the time of a single pollen sac in either

maturity. , • , ,, , , ~,

halt-anther. The middle part

or axis of the anther between the two pouches thus formed
is the connective.

204. The pollen sacs open for the liberation of the pollen
usually by a slit along the groove running down each side
of the anther ; in Pyrola and other members of the Heath
family, by terminal pores (Fig. 144) ;

and in the Barberry by uplifting
valves (Fig. 145). And other modes
of dehiscence occur, suited to the
various means by which the pollen
is to reach its destination.

205. The number of stamens is
often large, as in the wild Rose, the

Buttercup, the Magnolia, and the 144, 145. stamens : 144, of

, T*? ? . ,, Pyrola, the auther

Water Lily. In a tew species there
is but one. Generally speaking, the
number is small, not more than ten ;
and, when small, usually definite for
each species. For example, most grasses have three sta-
mens, most Mints four, the Violets five, and the true
Lilies commonly six. Each pollen sac produces a vast
number of pollen grains. And when the flowers borne

144

opening by terminal
pores ; 145, ol Bar-
berry, the anther
opening by uplifting
valves.

THE FLO WEE

109

by the plant, or the stamens in the individual flowers, are
very numerous, the pollen may be exceedingly
abundant.

206. In a few families the stamens are regularly
united, either by the anthers — as in the Composite,
of which the Daisy is an example; or by the fila-
ments, as in the Mallows and

the LeguminosoB (e.g. the Sweet-
pea, Bean, etc., Figs. 146-148).

207. The pistils collectively are
known as the gynoecium ; the
stamens as the andrcecium. It
is well to hold clearly in mind
that these two groups of organs, u6

though often concealed Or ren- 146-148. United stamens: 146, of a

, j . . plant of the Pulse family ;

dered inconspicuous by the vi- 147, in the Mallow family;

cinity of highly colored floral 148> stamens united by

anthers in the Composite

envelopes, are essentially the family,

flower. That is to say, pistils

and stamens perform the essential function of the flower ;

and the floral leaves
act a subordinate
part. Not very
rarely flowers con-
sist of pistils or
stamens alone.
This is practically
the case in the
Willows. The familiar
catkins are of two kinds.
The more showy ones
are made up of numer-
ous flowers, each com-
prising stamens, usually
two, with a scale at the
base. In catkins of the
other sort each minute
flower is composed of

149

150

152

151

149-152. Flowers of a Willow: 149, staminate
catkin ; 150, one of the flowers ; 151 , pis-
tillate catkin ; 152, a pistillate flower.

110

THE FLOWER

a single pistil with the basal scale (Figs. 149-152). The
seed-bearing flowers of the Pine and other Coniferce, as
already described, contain only pistils; their pollen-
bearing flowers, only stamens. When a flower lacks
both gynoecium and andrcecium, it either becomes merely
tributary to other, fertile flowers — as in the case of the
marginal florets in the heads of the Sunflower — or it
lacks altogether the essential character of a flower proper,
as regards purpose, either directly or indirectly ; as in the
double Rose and other flowers transformed by cultivation.

208. The floral leaves together are called the perianth,
meaning about the flower — a term not far from appropriate
if what has just been said is allowed. Commonly, two
distinct sets of these leaves are present : the inner called
petals, together forming the corolla; the outer termed
sepals, composing the calyx.

209. The number of sepals and petals in particular
species is generally constant. In a majority of the Dicotyle-
dons' the sepals are five, and the petals five, though four is
a. common number ; in Monocotyledons the members of

the perianth are prevailingly in
threes. As the stamens are apt
to be as many or twice as many
as the petals or sepals, a numerical
plan is often prominent in the
parts of the flower. We say that
the flowers of the Dicotyledons
are often on the plan of five, those
of the Monocotyledons on the plan
of three.

210. Forms of the corolla. — As
an example of the regular corolla
— i.e. with petals all alike — the
flowers of any of the Rose family
may be recalled ; but the Colum-
bine (Fig. 153) as well, since all the petals are spurred,
presents a regular corolla. In the Violet (Fig. 154), on
the contrary, only one petal is spurred, and the petals

153. Flower of the Colum-
bine.

THE FLOWER

111

154. Flower of the Violet ;
below, the parts of
the perianth sepa-
rated.

are of unequal size : such corollas, and all in which the

petals are not entirely uniform, are

irregular.

211. A second important respect in
which corollas differ is in the sepa-
ration or union of the petals. The
trumpet-shaped corolla of the Morn-
ing Glory (Fig. 155) furnishes an
extreme instance of union, where the
original petals are
not easily distin-
guishable. Fre-
quently the limb,
or border, is so
lobed that the

number of component parts is evident.
Another familiar form is the two-
lipped, labiate, corolla (Fig. 169).

212. In case the petals remain quite
separate, the corolla is said to be poly-
petalous ; but if they grow up united when the floral
organs are in process of formation, the corolla becomes
gamop&talous. When the petals are all wanting, the
flower is apetalous.

213. The calyx presents features very similar to the
corolla as regards union of sepals and other modifications.
It is usually inferior to the corolla in size and coloration,
since its service is chiefly to protect the bud, of which it
forms the coat. But in numerous plants the calyx shares
with the corolla in another duty.

214. Functions of the perianth. — The role of the perianth
in the natural history of the flower is chiefly twofold :
(1) it protects the developing organs within while the bud
is coming to maturity ; and (2) at the time of blooming
it aids in the proper distribution of the pollen. Without
anticipating the subject of fertilization, it may be said that
it is of advantage to plants to secure the dusting of the
stigma of each flower by the pollen of some other flower of

155. Calyx and corolla
of Morning Glory.

112

THE FLOWER

the same kind, and that this is most commonly accom-
plished by the aid of insects. The various forms of the
perianth are, as a rule, very definitely related to the work
of attracting the attention of insects, or of receiving and
supporting them when they alight, or of guiding them to
the "honey" or nectar secreted by special glands at the
base of the flower. In view of such offices the labiate
corolla of the Mints, the tubular or funnelform corolla of
the Morning Glory, the spurred (nectariferous) petals of
the Columbine, and the irregular flower of the Violet, are
readily understood. This subject will be treated more fully
under The Ecology of the Flower.

215. The receptacle of the flower is that part which be-
longs to the stem. It is commonly short, and some-
what enlarged or knoblike. Flowers
with very numerous pistils generally
have the receptacle enlarged so as to
give them room ; it sometimes becomes
broad and flat, as in the Flowering
Raspberry ; sometimes
elongated, as in the
Blackberry (Fig. 256),

the Magnolia, etc. It is the receptacle in
the Strawberry (Fig. 156), much enlarged
and pulpy when ripe, which forms the eata-
ble part of the fruit, and bears the small
seedlike pistils on its surface. In the Rose
(Fig. 157), instead of being convex or
conical, the receptacle is deeply concave,
or urn-shaped. Indeed, a Rose hip may be likened to
a strawberry turned inside out.

216. In Nelumbo, of the Water Lily family, the singu-
lar and greatly enlarged receptacle is shaped like a top,
and bears the small pistils immersed in separate cavities of
its flat upper surface (Fig. 158).

217. Arrangement of the parts of the flower. — This is
most easity studied in those flowers, in which all parts
are present — calyx, corolla, stamens, and pistils ;

156. Section through
a Strawberry.

157. Longitudinal
section of a
Rose.

Ill

THE FLOWER

113

158. The top-shaped recep-
tacle of Nelumbo,
the Water Chinque-
pin, ripening into a
float for the dissemi-
nation of the seeds.

which all the organs of each kind are separate from one

another ; and each set comprises a

small number, as three or five. In

such a case l it is the rule to find

the organs in whorls,2 and the whorls

arranged so that the organs of one

whorl stand above the spaces of

the whorl below, just as is the case

with whorled foliage leaves. The

petals thus stand over the spaces

between the sepals, the first row

of stamens alternates with the

petals, the second row of stamens

(if present) with the first, and the pistils alternate with

the stamens. When the various members of the flower

are more numerous and the receptacle somewhat elon-
gated, as in the Magnolia, the parts are spirally placed.

In short, the organs of the flower are arranged like

leaves.

218. Morphology of the floral parts. — Sepals and petals

are evident leaves, as they are commonly and properly

called. There are numerous
cases where green forms, func-
tioning as foliage, pass over
by easy gradations to the
white or bright-colored forms
subserving the purposes of
the flower. In shape, in fun-
damental structure (in pos-
sessing veins, etc.), and in

159. Transition from green outer x

floral leaves (sepals), through arrangement on the axis, the

petals, to stamens, in Water tg ()f the perianth show

Lily ; indicating the unity of r

nature of sepals, petals, and the morphology OI leaves.

stamens- Stamens and pistils, also, agree

with leaves in the order of insertion on the axis, as well

1 Sometimes called a pattern flower.

2 A whorl is a circular group of several organs standing at the same
level on the axis.

OUT. OF BOX. — 8

114 THE FLOWER

as iii possessing what answer to the veins or ribs of leaves,
— fibrous elements coming out from the flower stem.
Occasionally stamens and pistils are found which have
failed to develop in their proper character. They then
take the shape of foliage leaves, more or less exactly.
The conclusion is inevitable, from all these considerations,
that the essential organs of the flower, as well as the floral
envelopes, are morphologically leaves.1

219. The carpels, in this conception, become leaves rolled inward,
bearing on the inrolled edges rows of ovules. When the pistil is
simple (of one carpel or leaf), a seam, the ventral suture, marks the
closing together of the ovuliferous leaf on the side toward the center
of the flower ; while a ridge up and down the opposite side of the pis-
til evidently stands for a midrib.

220. Departures from a simple floral plan. — If one were to examine
the first score of different flowers that he should meet on going into
the field, he would probably find among them few or none that display
the regularity, simplicity, and completeness spoken of in § 217. The
fundamental plan — that is, the order and mode of growth, num-
ber of parts, etc. — would be found in many cases to be obscured
by a variety of adaptations to the special functions of the flower.
Some of the commonest modifications to be discovered are the
following : —

221. Absence of some of the organs.2 — Occasionally the gradual dis-
appearance of some of the organs may be directly noted, as in stamens
lacking the anther, or reduced to a mere ridge or rudiment ; or in the
reduction of one whorl of the perianth to an inconspicuous ring. In
many of the trees and shrubs the perianth will be found to consist of
only the calyx (e.g. in the Elm), or it may even be wanting (e.g. in the
Buttonwood). And two cases have already been mentioned (the Wil-
low and the Pine) where each flower contains but one kind of essen-
tial organ.

222. Union of like parts, or coalescence, of which examples have
been given above.

1 This is not to be construed to mean that what were once merely
foliage leaves have in the course of time been modified so as to become
carpels, stamens, etc. All that is to be inferred here is that both foliage
leaves and floral organs have a common morphological nature, as foliar
appendages of the stem.

2 It is possible to suppose in some cases that the fewness of parts, or
the absence of certain organs, has come about, not by reduction from
more highly organized forms, but by inheritance from ancestry charac-
terized by simple flowers from the first.

THE FLO WEE

115

223. Union of unlike parts, or adnation. — Frequently the stamens
seem to grow from the corolla, because the filaments have grown
to the petals (Figs. 160, 161). Again, in the flower of Cuphea, for
example, calyx, corolla, and stamens adhere in a cup around the pistil,

160. Flower of a Primrose laid open;
co, corolla ; ca, calyx.

161. Flower of Cuphea laid open ;
ct, calyx tube ; pt, petals.

in such a manner that both stamens and petals seem to be inserted on
the margin of the calyx tube (Fig. 161). Finally, in the Purslane
(Fig. 162) all the different members are united, with the ovary in the
center. The ovary is in such cases said to be inferior. When free
from the organs, it is superior (Fig. 160). The adherence of unlike
members is termed adnation. In the Purslane, for example, the calyx
is said to be adnate to the ovary.

Coalescence and adnation come about in the following manner.
The rudiments of the carpels, stamens, petals, and sepals appear at
first as minute elevations on the young receptacle. As these increase
the surface of the receptacle between them may be involved in the
growth. Thus, if the tissue between
the nascent petals is affected, a cir-
cular ridge arises, upon the edge of
which the position of the original
petal rudiments is indicated by prom-
inences. The ridge, or ring, grows up
into a longer or shorter tube (the
corolla tube), the original prominences
becoming lobes or divisions. By a

similar process, in the Primrose (Fig. 160) the rudiments of the
stamens become united to the corolla ring at an early stage. In
the Purslane (Fig. 162) a single ring arising from the receptacle,
and bearing all the floral organs on its summit, comes to form the.
so-called "calyx tube.'*

162. Flower of the Purslane.

116 THE FLO WEE

PROCESSES LEADING TO THE FORMATION OF SEED

224. The student is already aware that the pollen is
destined to reach the stigmatic surface of the pistil ; and
he probably also understands in a general way that the
result of the pollination of a flower is the production of
seed; that if pollination fails to be brought about, the
ovules of the unpollinated pistil do not develop into fertile
seed. The history of the pollen from its deposition on
the stigma (pollination) onward and the resulting effect
on the ovule (fertilization) are now to be followed.

225. The pollen grain has been briefly described as a
simple vesicle filled with living matter, capable of growth.
The wall is relatively strong, though thin and transparent,
and often beset with projections. The living substance
within, termed protoplasm, is more or less jellylike in

consistency and clearness,
but is far from being a
simple mass of jelly. The
protoplasmic body is in fact
very definitely and highly
organized, with permanent
parts or organs performing
definite functions in har-
n mony with one another.

163. A pollen grain highly magnified. These members may be
it contains two nuclei (n, ri) dimly made out in the living

at the stage here represented. .

protoplasm with the com-
pound microscope. But when killed and stained with
proper dyes, the structure stands out with distinctness and
its great complication is then seen. A constant com-
ponent is a rounded central body of especially dense proto-
plasm, known as the nucleus (Fig. 163). In the earlier
stages of the pollen grain there is but one nucleus. The
pollen grain is then an excellent example of the typical
vegetable cell.

226. Cellular structure of plants. — Every plant is made
of minute members, or cells, essentially similar to the

THE FLO WEE

117

pollen grain in internal constitution, though of course
not as to form and external appearance. The cells of
vegetable tissue
take on various
shapes. Generally
their duration as
living elements is
limited. The walls
become thickened
and hardened and
remain, after the
death of the cells,
as components of
the plant's frame-
work (e.g. the fibers
of wood). The
simplest plants
among the crypto-
gams consist of but
a single cell.

227. The pollen
grain a plant. —
In truth the pollen
grain itself behaves
like a simple plant.
For it absorbs water
and nutriment
from the pistil
upon which it is
deposited, and uses
these materials in
growth.

228. Growth is
manifested in two
ways : ( 1 ) in the
formation of new

164. Fertilization of the ovule. The pollen tubes
traverse the loose tissue of the stigma and
style, finally emerging in the cavity of the
ovary. In the figure a tube is represented
as applying itself to the micropyle of an
ovule. This ovule is seen in section, and
shows at the micropylar end the embryo-
sac with several nuclei, one of which takes
part in the formation of the embryo.

nuclei in the proto-
plasm ; and (2) in the extension of the wall in a tube

118 THE FLOWER

(Fig. 164). The tube penetrates the tissue of the stigma
and style, and at length reaches the cavity of the ovary,
through which it descends until one of the ovules is
reached. Penetrating the ovule at a certain spot, the
tube comes in contact with the large cell, termed embryo
sac, in which the embryo is to be formed (Fig. 164).

Before this time the original pollen nucleus has given
rise, by division, to several nuclei. One of these nuclei,
which has followed the tube in its descent, now passes
over into the embryo sac and fuses with one of the sev-
eral nuclei to be found there. From the united body so
formed the new plant takes its start. New cells begin
to appear in the embryo sac and the embryo gradually
assumes form. At the same time the whole ovule, and
in fact the entire ovary, begins courses of development
resulting in seed and fruit respectively.

229. While every step of this process — which can be
followed only by aid of the microscope and numerous dis-
sections— may not be entirely clear to the beginner, the
brief account here given should serve to fix in mind the fact
that the pollen and the ovule play very definite and neces-
sary parts in the life of plants ; and the conception gained
of the method and results of fertilization, even if some-
what incomplete, will give the flower and its varied forms
an added meaning.

ECOLOGY OF THE FLOWER

230. Self-fertilization and cross-fertilization. — Self -fer-
tilization is the action of a flower's pollen on its own ovules;
cross-fertilization, on the ovules of some other flower, of the
same species.

231. A limited number of plants bear in addition to the
ordinary flowers certain specialized flowers which are fer-
tilized by their own pollen alone. The Violet is one of
these. The vernal flowers are cross-fertilized. Later on
another set, of a different appearance, are produced. The
calyx remains permanently closed, while the corolla is un-
developed. Only two stamens reach maturity, and their

THE FLOWER 119

anthers are pressed against the end of the style. The
pollen grains are few and unusually small. Fertilization
is effected in the closed flowers, and abundant seed results,
the pods seeding far more freely indeed than those of the
ordinary flowers. In some species of Violet, these deistog-
amous flowers are concealed under the leaves, or are borne
on runners underground.

232. Self-fertilization prevented. — Many flowers are
habitually fertilized either (1) by their own, or (2) by
foreign pollen, — sometimes in one way, sometimes in the
other, as chance decides. In the great majority of flower-
ing plants, however, cross-fertilization is the rule. Self-
fertilization may be absolutely prevented. This must be
the case when the flower bears only pistils (is pistillate),
or stamens (is staminate). Sometimes the staminate and
pistillate flowers are produced on separate individual plants
(when the plants are said to be dioecious) ; sometimes on
the same plant (when the species is monoecious). An
equally sure mode of preventing self-fertilization is seen
where the pistils and stamens, though both present, are
active at different times. This may well be illustrated
by the common Plantain. The flowers are borne on long
spikes. The unfolding of the flowers " proceeds from
base to apex of the spike in regular order, and rather
slowly. While the anthers are still in the unopened
corolla and on short filaments, the long and slender hairy
stigma projects from the tip and is receiving pollen blown
to it from neighboring plants or spikes : a day or two after-
wards, the corolla opens, the filaments greatly lengthen,
and the four anthers now pendent from them give their
light pollen to the wind ; but the stigmas of that flower
and of all below it on that spike are withered or past
receiving pollen."1

233. When the stamens mature first, as in many flowers,
the condition is termed proterandry. In the opposite case,
proterogyny, which is less usual, the pistils have been fertil-
ized or are no longer receptive by the time the anthers open.

i Asa Gray, " Structural Botany," p. 219.

OF THE

UNIVERSITY

120 THE FLOWER

165. A pollen grain of the
Pine, provided with
two air-filled vesi-
cles to give buoyancy
in the air.

234. Agencies and adaptations for intercrossing. — The
agents serving to transport pollen from flower to flower
are wind, water, and small animals (mainly insects).

235. Pollination by wind. — Among the adaptations
displayed by wind-pollinated flowers are to be mentioned
the character and quantity of the pollen produced. Thus

the pollen grain of the Pine con-
sists of three compartments, the
two lateral ones empty and serving
as wings (Fig. 165). "The im-
mense abundance of pollen, its
lightness, and its free and far diffu-
sion through the air in Pines, Firs,
and other Coniferse, are familiar.
Their pollen fills the air of a forest
during anthesis ; arid the ' showers

of sulphur,' popularly so-called, the yellow powder which
after a. transient shower accumulates as
a scum on the surface of water several
or many miles from the nearest source,
testifies to these particulars."1 All cat-
kin-bearing trees — except Willows —
and most grasses and sedges are wiiid-
pollinated. Their flowers are mostly
dull-colored, odorless, and
destitute of honey. The
stigmas are relatively
prominent and apt to be
plumose (Fig. 166). The
anthers are often poised
on the tip of the filament
(Fig. 167), so that they
are shaken by the wind.
As they turn readily in all directions
they are said to be versatile.

236. The pollen of aquatic plants is 1G6 piumeiike stig-
sometimes carried from one flower to mas of a srass-

1 Gray, "Structural Botany," p. 217.

167. A versatile
anther.

THE' FLOWER

121

another by the water, or water and wind together ; the
staminate flowers of the fresh- water Eel-grass, for instance,
after being detached from the submerged heads, are driven
like minute rafts before the wind, and collect about the
much larger pistillate flowers on the surface.1

237. A few species of plants are regularly cross-polli-
nated by snails, and

others by birds.

238. Pollination by
insects. — Cross-fertili-
zation in flowering
plants is brought about
by aid of insects far more
frequently than by all
other agencies combined.
A few cases will be de-
scribed in some detail.

239. Lady's Slipper
(Qypripedium) and the
South American Seleni-
pedium, Fig. 168, show
a very perfect mode of
compelling the insects
that visit them to serve
as pollen bearers. One
of the petals is shaped
into a sac, or labellum,

Open above an don either 168. Flower of South American Seleni-

side near the base (0).

The bee alighting on

this labellum in search

of the honey secreted by

glandular hairs within,

and entering through the main opening, is prevented by

the incurved edges of the latter, as well as by the depth

of the labellum, from escaping except by one of the two

pedium SchKmU, The dotted lines
with arrow tips show the course fol-
lowed by a visiting bee. In b, the
flower is seen from the side, the
labellum, or saccate petal, being cut
open ; p, a pollen mass ; s, the stigma ;
e, exits.

1 See Kerner and Oliver, "Natural History of Plants," Vol. II., p. 132.

122

THE FLOWER

posterior openings, or exits (<?). As it emerges through
this rather narrow portal, it brushes against one of the
pollen masses (jt?), which adheres to its head or shoulder,
In the next flower visited, the bee in leaving encounters
the stigma (s), and leaves on the surface some of the pollen
brought from the former flower. Finally succeeding in
crawling past this obstacle, it brushes a pollen mass from
this flower, to be carried to the next ; and so passes about,
always taking away pollen, but not depositing it upon
the stigma of the same flower.

240. Sage (Salvia, Fig. 169 1).— The corolla is two-
lipped, as nearly always in the Mint family, the lower lip
serving as a convenient landing stage for insects, while the
upper, erect and arched, incloses the two anthers (#) . The

flower is proterandrous,
and at the period rep-
resented in the figure
the stigma is seen pro-
truding from the upper
lip, its two branches
folded together. The
stamens are inserted
on the sides of the
narrow throat and
are hinged near the
point of insertion.
Each bears a projec-

B

169.

Mechanism of the flower of Salvia; a,
pollen sacs of the anthers, hidden
under the upper lip of the corolla; a',
their position when dusting the back
or sides of a hee ; c, lobes against
which the bee pushes in thrusting its tion (<?) standing Out
head into the throat of the corolla; j nartlv hlnpkino-

s, stigma, immature ; *', stigma when ™

mature. In A the stamens ai*e seen,
removed from the corolla ; /, filament
on which the anther turns.

the throat. When a
bee pushes its head
into the corolla tube,

these projections are pushed back, and the whole upper
parts of the stamens are rotated on the hinges. The
pollen sacs, heretofore concealed under the hood, are

1 From M tiller's " Fertilization of Flowers," by courtesy of the Macmil-
lan Company, publishers, New York. The book is a valuable reference
work.

THE FLOWER

12S

170. Partridge Berry, with two forms of
flowers.

brought down into the position a' and dust the bee's back
with pollen. When the bee withdraws its head, the
anthers resume their former station. At a later stage,
after the pollen is exhausted or the anther withered, the
stigma becomes receptive. It then occupies the position
»', and its branches
spread to brush pollen
from the back of a
subsequent visitor.

241. Partridge Ber-
ry (^Mitchell a, Fig.
170). — The plant
grows abundantly, as
a small trailing herb
with evergreen leaves,

in open woods. The blossoms are of two forms ; namely,
one form (a) with long style and low stamens, the other

(5) with short style and high
stamens (Fig. 171). The sta-
mens of form a are at about
the same level as the stigma
of form b ; and the stamens
of b are level with the stigma
of a. An insect brushing the
stamens of b with its sides
will subsequently bring these
pollen-dusted sides in contact

a, long-styled form ; &, short- with the stigma of a. The
styled form, of flower in the proboscis of the insect, smeared

Partridge Berry. ^

with pollen from the stamens

, will leave some of it on the stigma of b. When
a species of plants bears two sorts of flowers, as regards
the relative lengths of stamens and style, the flowers are
said to be dimorphic. In many dimorphic flowers the pol-
len of a differs in size from that of b ; and neither kind of
pollen is capable of fertilizing the flower that produces it.

242. The opening and closing of flowers, according to
the habits of the insects that pollinate them, — opening by

of

124 THE FLO WEE

day when pollinated by diurnal, at night when by nocturnal,
insects, — may be illustrated from a flower described by
Sir John Lubbock.1 It is the Nottingham Catchfly, a
British and European plant related to our Chickweeds
and Pinks. " Each flower lasts three days, or rather three
nights. The stamens are ten in number, arranged in two
sets ; the one set standing in front of the sepals, the other
in front of the petals. Like other night flowers, it is
white, and opens toward evening, when it also becomes
very fragrant. The first evening, toward dusk, the five
stamens in front of the sepals grow very rapidly for about
two hours, so that they emerge from the flower ; the pollen
ripens, and is exposed by the bursting of the anther. So
the flower remains through the night, very attractive to,
and much visited by, moths. Toward three in the morn-
ing the scent ceases, the anthers begin to shrivel up or
drop off, the filaments turn themselves outward, so as to
be out of the way, while the petals, on the contrary, begin
to roll themselves up, so that by daylight they close the
aperture of the flower, and present only their brownish
green under sides to view ; which, moreover, are thrown
into numerous wrinkles. Thus, by the morning's light,
the flower has all the appearance of being faded. It has
no smell, and the honey is covered over by the petals.
So it remains all day. Toward evening, however, every-
thing is changed. The petals unfold themselves ; by eight
o'clock the flower is as fragrant as before, the second set
of stamens have rapidly grown, their anthers are open,
and the pollen again exposed. By morning the flower is
again ' asleep,' the anthers are shriveled, the scent has
ceased, and the petals rolled up as before. The third
evening, again the same process occurs, but this time it
is the pistil which grows : the long spiral stigmas on the
third evening take the position which on the previous
two had been occupied by anthers, and can hardly fail to
be dusted by moths with pollen brought from another
flower."

1 Lubbock, "Dowers, Fruits, and Leaves," Macinillan, 1894, p. 40.

THE FLOWER 125

243. The object of the insects' visits is usually a
sweetish liquid, the nectar secreted by glands — commonly
in the forms of swellings of the tissue of the receptacle —
at the base of the flower. These are the nectaries. In
flowers with spurred petals, like the Columbine, the nectar
is secreted at the end of the spur, whence it can be sucked
up only by the long-tongued insects, which are the most
effective in transferring the pollen of these plants.

244. In addition to nectar, the pollen itself, a highly
nutritious product, is sought by many insects.

245. Protection of the nectar. — Such a desirable food
as the nectar is sure to be attractive to insects which, by
reason of their size or habits, are not likely to make any
return of service to the plant. Ants, for instance, travel
all over the herbage in the vicinity of their nests in search
of food. Happening upon the wells of honey within the
flower, they would drink their fill, and perhaps bring their
fellow-ants to the place, as their custom is, with the result
that the flower would be drained of its nectar; but these
visitors would be too small, in the case of many flowers,
to brush the pollen from the tall stalked stamens, or de-
posit it on the stigma at the summit of the lengthened style.
And, further, even were it possible for transference to be
made by the adherence of the pollen to the bodies of the ants,
the slow movements of these insects, their short-sightedness
and blind wanderings, and their indiscriminate visiting of
all sorts of plants would make them unprofitable carriers,
as regards any one vegetable species, when compared with
swift-flying, long-sighted, and often times discriminating
insects like the various bees, butterflies, and moths.

246. Consequently, very many flowers are fortified
against the invasions of the ants — and other undesirable
visitors. One of the common and effective methods of
defense is a coating of downward-pointing, or in cases
stioky, hairs on the flower stalk or on the calyx. In
some instances the secretion from the hairs not only pre-
vents insects from going farther up the stalk, but holds
any trespasser firmly, so causing its death.

126

THE FLO WEE

172. Two of the florets in a head of Dandelion
(diagrammatic) .

247. The protection of the nectar from rain is effected
sometimes by the habitually drooping attitude of the

flower, sometimes
by the bending or
bowing of the
flower stalk on the
approach of rain,
sometimes by some
special construc-
tion of the flower.
248. The group-
ing of flowers in a
specialized part of
the shoot in a man-
ner likely to secure the attention of insects, and so lead
to the process of cross-fertilization, should be noted. The
Dandelion (Fig. 172) and the Jack-in-the-pulpit (Fig. 173)
may be taken as illustrations. In
both these cases clusters of flowers
are commonly mistaken for single
flowers. The apparent "petals" of
the Dandelion head are the several
separate corollas of as many small
flowers or florets. On close examina-
tion each of these florets is seen to
possess its own two-parted stigma,
and andrcecium of five stamens united
around the style. What might pass
at a casual glance for a calyx, sur-
rounding the whole head, is a collec-
tion of subtending leaves (bracts) 173>
serving to protect the bud.

249. In the Jack-in-the-pulpit
(Fig. 173), a fleshy spike of small
flowers (termed a spadix) is sur-
rounded and overarched by a single
more or less striped or colored bract (termed in sucli
a case a spathe).

The bract (spathe)
partly cut away
helow to show the
fleshy spike (spa-
dix) of flowers
which it surrounds.

THE FLOWER 127

250. In both these cases, and countless others, the inflo-
rescence — mode of arrangement of the flowers — is deter-
mined by the need of cross-fertilization.

EFFECT OF CROSSING

251. The arrangements for cross-fertilization are ex-
tremely varied and in many cases extraordinarily compli-
cated. It could not well be doubted that such elaboration
has been evolved because some important benefit is derived
from intercrossing. And experiment goes to show that
this is actually the case. When seeds derived from both
self-fertilization and cross-fertilization of the same plant are
grown side by side, the offspring of cross-fertilization gen-
erally outstrips that produced by self-fertilization. In
spite of the fact that a small number of species are propa-
gated indefinitely without intercrossing (seedless plants,
reproduced vegetatively), and as far as is known without
harmful results, the important truth remains that inter-
crossing is a means of giving increased vigor to seedlings.

Supplementary Reading

1. Adaptations for Securing Intercrossing. Gray's "Structural
Botany," p. 220 and following.

2. The Pollination of Orchids. C. M. Weed's " Ten New England
Blossoms," Nos. VI. and VII.

3. " The Mayflower." Same source, No. II.

4. The Industriousness of Bees, and the Perception of Color by
Insects. Sir John Lubbock's " Flowers, Fruits, and Leaves," pp. 11-14.

Supplementary Studies: Fieldwork on the Ecology
of the Flower

252. The account of adaptations to secure cross-fertilization given in
this chapter is necessarily brief, hardly more than suggesting some general
principles. Subjects not touched, but well worth study in the field, are :
Attraction of Insects («) by colors, (6) by grouping flowers, (c) by scent ;
Opening of Flowers at special times to receive special classes of insects ;
Guides to Honey, (a) spots and streaks, (6) conformation of floral parts ;
Reward to Insects, (a) honey and sap (with distribution and form of
secreting organs), (6) pollen, (c) edible tissue, (of) shelter; Dusting the
Insect, (a) by irritable stamens (Barberry), (5) by springing stamens

128 THE FLOWER

(Mountain Laurel), (c) by explosion ; Movement of Stamens anl Style,
(a) to avoid, (5) to secure self-fertilization ; Protection of Pollen and
Honey, (a) against unwelcome visitors, (6) against weather, (1) by shape
and position of the flower, (2) by bowing of the flower stem at times.
This outline will serve as a working basis, which may be extended to
include cases that arise in actual observation.

TERMINOLOGY OF THE FLOWER

[Inserted for the use of classes that are to take up the determination of
flowering plants.]

For the student who is preparing to study Systematic Botany, a
knowledge of the descriptive terms applied to the parts of the flower
and the inflorescence is indispensable. The relationships of plants
are more easily studied in their flowers than in the vegetative parts,
because in the flower there are brought together in small compass so
many sharply marked and readily described characteristics, varying
slowly, for the most part, through wide ranges of related plants.
Descriptions written to enable one to determine the names of the
plants that he collects are accordingly based very largely on the
flower. Many of the more usual terms — not already given — are now
to be explained.

253. Terms relating to the general plan of the flower. Flowers
are said to be : —

Perfect (hermaphrodite) when provided with both kinds of essential
organs, i.e., with both stamens and pistils.

Complete, when, besides, they have the two sets of floral envelopes ;
namely, calyx and corolla. Such are completely furnished with all
that belongs to a flower.

Regular or actinomorphic, when all the parts of each set are alike in
shape and size. Flowers of this type can be divided by at least two

planes into equal and symmetrical
parts.

Imperfect, or better, unisexual,
flowers, in which some flowers lack
the stamens, others the pistils.
Taking hermaphrodite flowers as
the pattern, it is natural to say that
the missing organs are suppressed.
This expression is justified in the
very numerous cases in which the
missing parts are abortive, that is,
are represented by rudiments or

vestiges, which serve to exemplify
174. Unisexual flowers of the Castor , , , ,, , , ,

Oil plant ;p, pistillate, a, stem- the Plan' altho"Sh useless as to
inate flowers. office. Unisexual flowers are : —

THE FLOWER

129

175.

Unisexual flowers of
Moonseed , borne on
different plants.

Monoecious {i.e., of one household), when flowers of both sorts or
sexes are produced by the same individual plant, as in the Ricinus or
Castor Oil plant (Fig. 174).

Dioecious {i.e., of separate households),
when the two kinds are borne on different
plants ; as in Willows, Poplars, and Moon-
seed (Fig. 175).

Polygamous, when the flowers are some of
them perfect, and some staminate or pistil-
late only.

254. A blossom having stamens and no
pistil is a staminate or male flower. Sometimes it is called a sterile
flower, not appropriately, for other flowers may equally be sterile.
One having pistil but no stamens is a pistillate or female flower.

255. Incomplete flowers are so named in con-
tradistinction to complete : they
want either one or both of the
floral envelopes. Those of the
Anemone (Fig. 176) are incom-
plete, having calyx but no corolla.
The sepals, however, are highly col-
ored and petal-like. The flowers
of Saururus or Lizard's tail, although perfect,
have neither calyx nor corolla (Fig. 177). Incomplete flowers, accord-
ingly, ar-e: —

Naked or achlamydeous, destitute of both floral envelopes, as in

Fig. 177, or—

Apetalous, when wanting only
the corolla. The case of corolla
present and calyx wholly wanting
is extremely rare, although there
are seeming instances. In fact, a
single or simple perianth is taken
to be a calyx, unless the absence
or abortion of a calyx can be
made evident.

256. In contradistinction to
regular and symmetrical, very
many flowers are : —

Irregular, that is, with the mem-
bers of some or all of the floral
circles unequal or dissimilar. A
special and important case of floral
irregularity is shown by —

Zygomorpliic flowers which, like

ITS

181

178, 179. Mustard: 178, flower; 179,
its stamens and pistil separate
and enlarged.

180,181. Violet: 180, flower; 181, its
calyx and corolla displayed ; the
five smaller parts are the sepals ;
the five intervening larger ones
are the petals.

OUT. OF BOT. - 9

130

THE FLOWER

most of those in the Pulse and Mint families, can be divided by one
and only one plane into two equal parts.

257. The relation of the perianth and stamens to the pistil is ex-
pressed by the terms hypogynous (i.e. under the pistil), when they are
all free, that is, not adnate to pistil or united with each other, as in
Fig. 182.

Perigynous (around the pistil), when adnate to each other, that
is, when petals and stamens are inserted or borne on the calyx, whether

187

as in Cherry flowers (Fig. 183) they are free from the pistil, or as in
Purslane and Hawthorn (Figs. 184, 185) they are also adnate below to
the ovary.

Epigynous (on the ovary), when so adnate that all these parts appear
to arise from the very summit of the ovary, as in Fig. 186. The last
two terms are not very definitely distinguished.

258. Position of the parts of the flower. — The terms superior and
inferior, or upper and lower, are also used to indicate the relative
position of the parts of a flower in reference to the axis of inflores-
cence. An axillary flower stands between the bract or leaf which
subtends it and the axis or stem which bears this bract or leaf. This
is represented in sectional diagrams (as in Figs. 187, 188) by a trans-
verse line for the bract, and a small circle for the axis of inflorescence.

THE FLO WEE

131

Now the side of the blossom which faces the bract is the anterior, or
inferior, or lower side; while the side next the axis is the posterior,
or superior, or upper side of the flower.

259. So, in the labiate corolla (Figs. 198, 200),
the lip which is composed of three of the five
petals is the anterior, or inferior, or lower lip; the
other is the posterior, or superior, or upper lip.

260. Terms applicable to corolla and calyx. —
Gamopetalous, said of a corolla the petals of which
are coalescent into one body, whether only at base
or higher. The union may extend to the very
summit as in Morning Glory, the Datura (Fig.
189), and the like, so that the number of petals
in it may not be apparent. The old name for
this was monopetalous, but that means "one-
petaled"; while gamopetalous means "petals
united," and therefore is the proper term.

Polypetalous is the counterpart term, to denote

a corolla of distinct, that is, separate petals. As it means " many-
petaled," it is not the best possible name, but it is the old one and
in almost universal use.

Gamosepalous applies to the calyx when the sepals are in this way
united.

Polysepalous, to the calyx when of separate sepals.

261. Degree of union or of separation in descriptive botany is ex-
pressed in the same way as is the lobing of leaves. See Figs. 116-123,

and the explanations.

262. A corolla when
gamopetalous commonly
shows a distinction (well
marked in Figs. 191-
193) between a con-
tracted tubular portion
below, the TUBE, and the
spreading part above,

the BORDER or LIMB. The junction between tube and limb, or a
more or less enlarged upper portion of the tube between the two,
is the THROAT. The same is true of the calyx.

263. Some names are given to particular forms of the gamopeta-
lous corolla, applicable also to a gamosepalous calyx, such as

Wheel-shaped, or rotate, when spreading
out at once, without a tube or with a very short
one, something in the shape of a wheel or of
its diverging spokes (Figs. 194, 195).

Salver-shaped, or salver-formed, when a flat^ 194 195

132

THE FLOWER

196 197 198 199 200

196-200. Corollas : 196, a Campanula or Hare-
bell, with a campanulate or bell-shaped
corolla ; 197, a Phlox, with salver-shaped
corolla ; 198, Dead Nettle (Lamium) , with
labiate ringent (or gaping) corolla ; 199,
Snapdragon, with labiate personate co-
rolla; 200, Toadflax, with a similar
corolla spurred at the base.

201

spreading border is raised on a narrow tube, from which it diverges

at right angles, like the
salver represented in old
pictures, with a slender
handle beneath (Figs.
191-193, 197).

Sell-shaped, or cam-
panulate, where a short
and broad tube widens
upward, in the shape of a
bell, as in Fig. 196.

Funnel - shaped, or
funnel-form, gradually
spreading at the summit
of a tube which is narrow
below, in the shape of
a funnel or tunnel, as

in the corolla of the common Morning Glory and of the Datura

(Fig. 189).

Tubular; when prolonged into a tube, with

little or no spreading at the border, as in the

calyx of Datura (Fig. 189).

264. Although sepals and petals are
usually all blade or lamina, like a sessile
leaf, yet they may have a contracted and
stalklike base, answering to petiole. This is
called CLAW, in Latin unguis. Unguiculate
petals are universal and strongly marked
in the Pink tribe, as in Soapwort (Fig.
190).

265. Such petals, and various others, may 201-202. Crowns: 201, un-
have an outgrowth of the inner face into an guiculate (clawed)
appendage or fringe, as in Soapwort, and in petal of a Silene ;
Silene (Fig. 201), where it is at the junction

of claw and blade. This is called a CROWN,
or corona. In Passion Flowers (Fig. 202)
the crown consists of numerous threads on
the base of each petal.

266. Papilionaceous corolla ( Figs. 203, 204) . — This is polypetalous,
except that two of the petals cohere, usually but slightly. It belongs
only to the Leguminous or Pulse family. The name means butter-
flylike ; but the likeness is hardly obvious. The names of the five petals
of the papilionaceous corolla are curiously incongruous. They are,

The STANDARD or banner (vexillum), the large upper petal which is
external in the bud and wrapped around the others.

crown ; 202, a small
Passion Flower,
with crown of slen-
der threads.

THE FLOW EH

133

The WINGS (ate), the pair of side petals, of quite different shape

from the standard.

The KEEL (carina), the two lower and

usually smallest petals ; these are lightly coa-

lescent into a body which bears some likeness,

not to the keel, but to the prow of a boat ; and

this incloses the stamens and pistil. A Pea

blossom is a typical example.
267. Labiate corolla (Figs. 198-200), which

would more properly have been called bilabiate,

that is, two-lipped. This is a common form

of gamopetalous corolla; and the calyx is

often bilabiate also. These flowers are all on

the plan of five; and the irregularity in the

corolla is owing to unequal union of the petals

as well as to diversity of form. The two

petals of the upper or posterior side of the

flower unite with each other higher up than

with the lateral petals (in Fig. 198, quite to

the top), forming the upper lip ; the lateral 203, 204.

and the lower similarly unite to form the lower

Up. The single notch which is generally found

at the summit of the upper lip, and the two

notches of the lower lip, or in other words the

two lobes of the upper and the three of the

lower lip, reveal the real composition. So also

does the alternation of these five parts with those of the calyx outside.

When the calyx is also bilabiate, as in the Sage, this alternation gives

three lobes or sepals to the upper and two to the lower lip. Two

forms of the labiate corolla have been designated, viz. : —
Ringent or gaping, when the orifice is wide open (Fig. 198).
Personate or masked, when a protuberance or intrusion of the base

of the lower lip (called a palate) projects over or closes the orifice,

as in Snapdragon and Toadflax (Figs.
199-200 ..

268. Ligulate corolla. — The ligu-
late or strap-shaped corolla mainly
belongs to the family of Compositae,
in which numerous small floweia are
gathered into a head, within an involucre
that imitates a calyx. It is well exem-
plified in the Dandelion and in Chiccory
(Fig. 205). Each one of these straps or
ligules, looking like so many petals, is

the corolla of a distinct flower : the base is a short tube, which opens

ous corolla : 203,
front view ; 204, the
parts of the same
displayed : s, stand-
ard, or vexillura ;
w, wings, or alse;
k, keel, o/ carina.

205

134

THE FLOWER

206. A slice of the Coreopsis head
enlarged, with one tubular per-
fect flower (a) left standing
on the receptacle, with its
bractlet or chaff (6), one ligu-
late and neutral ray flower,
and part of another (cc) ; dd,
section of bracts or leaves of
the involucre.

out into the ligule ; the five minute teeth at the end indicate the
number of constituent petals. So this is a kind of gamopetalous
corolla, which is open along one side nearly to the base, and outspread.

269. In Asters, Daisies, Sunflower, Coreopsis (Fig. 206), and the

like, only the marginal (or ray) co-
rollas are ligulate ; the rest (those
of the disk) are regularly gamo-
petalous, tubular, and five-lobed
at summit; but they are small
and individually inconspicuous,
only the ray flowers making a
show. In fact, those of Coreopsis
and of Sunflower are simply for
show, these ray flowers being not
only sterile, but neutral, that is,
having neither stamens nor pistil.
But in Asters, Daisies, Golden-
rods, and the like, these ray flowers

are pistillate and fertile, serving therefore for seed bearing as well

as for show.

270. The Stamens. — First as regards their insertion, or place of
attachment.

The stamens usually go with the petals rather than with the pistil,
when adherent to either. Not rarely they are

Epipetalous, that is, inserted on (or adnate to) the corolla, as
in Fig. 171. When free from the corolla, they may be

Hypogynous, inserted on the receptacle under
the pistil or gynoecium.

Perigynous, inserted on the calyx, that is,
with the lower part of filament adnate to the
calyx tube.

Epigynous, borne apparently on the top of the
ovary; all which is shown in Figs. 182-186.

Gynandrous is another term relating to inser- 207. Style of a Lady's
tion of rarer occurrence, that is, where the sta-
mens are inserted on (in other words, adnate to)
the style, as in Lady's Slipper (Fig. 207), and in
the Orchis family generally.

271. In relation to each other, stamens are
more commonly

Distinct, that is, without any union with each
other. But when united, the following tech-
nical terms of long use indicate their modes of
mutual connection : —

Monadelphous (from two Greek words, mean-

Slipper Cypri-
pedium) , and
stamens united
with it; a, a,
the anthers of
the two good
stamens ; st, an
abortive sta-
men, what
should be its
anther changed
into a petal-like
body; stig, the
stigma.

THE FLOWER

135

208

210

ing "in one brotherhood "), when united by their filaments into one
set, usually into a ring or cup below, or into a tube, as in the Mallow
family (Fig. 208), the Passion Flower (Fig. 202), and the Lupine
(Fig. 210).

Diadelphous (meaning in two brother-
hoods), when united by the filaments into
two sets, as in the Pea and most of its near
relatives (Fig. 209), usually nine in one set,
and one in the other.

Triadelplwus (three brotherhoods), when
the filaments are united in three sets or
clusters, as in most species of Hypericum.

Pentad elplious (five brotherhoods), when in five sets, as in some
species of Hypericum and in American Linden.

Polyadelphous (many or several brotherhoods) is the term generally
employed when these sets are several, or even more than two, and the
particular number is left unspecified. These terms all relate to the
filaments.

Syngenesious is the term to denote that stamens have their anthers
united, coalescent into a ring or tube ; as in Lobelia, in Violets, and
in all of the great family of Composites (Fig. 211).

272. Their number in a flower is commonly expressed directly, but
sometimes adjectivelyyJ>y a series of terms which were the names of
classes in the Linnsean artificial system, of which the following names,

as also the preceding, are a survival : —

ij Monandrous, i.e. solitary-stamened, when the flower has only

one stamen,

Diandrous, when it has two stamens only,
Triandrous, when it has three stamens; and so on.
Didynamous, when, being only four, they form two pairs,
one pair longer than the other, as in the Trumpet Creeper,
in Gerardia, etc.

Tetradynamous, when, being only six, four of them surpass the other
two, as in the Mustard flower and most of the Cruciferous Family
(Fig. 179).

273. The Anther is said to be

Innate (as in Fig. 212), when it is attached
by its base to the very apex of the filament,
turning neither inward nor outward;

Adnate (as in Fig. 213), when attached as
it were by one face, usually for its whole length,
to the side of a continuation of the filament; and

Versatile (as in Fig. 214), when fixed by or
near its middle only to the very point of the filament, so as to swing
loosely, as in the Lily, in Grasses, etc. Versatile or adnate anthers are

I

211

213 214

136

THE FLOWER

215 216 217

Introrse, or incumbent, when facing inward, that is, toward the
center of the flower, as in Magnolia, Water Lily,

efcc-

Extrorse, when facing outward, as in the
Tulip Tree.

274. Anthers may become one-celled either by
confluence or by suppression.

275. By confluence, when the two cells run
together into one, as they nearly do in most

species of Pentstemon (Fig. 216), more so in Monarda (Fig. 219),
and completely in the Mallow (Fig. 217) and all the Mallow family.

276. By suppression in certain cases the anther may be reduced to
one cell or halved. In Globe Amaranth (Fig. 218) there is a
single cell without vestige of any other. Different species
of Sage and of the White Sages of California show various
grades of abortion of one of the anther cells, along with a
singular lengthening of the connective (Figs. 220-224).

224 225 226

225, 226. Pollinia : 225, a pair of pollinia of a Milkweed (Asclepias) attached
by stalks to a gland; moderately magnified; 22(5, pollinium of an
Orchis (Habenaria), with its stalk attached to a sticky gland, mag-
nified ; each of the packets or partial pollinia of which it is made up
is composed of a large number of pollen grains.

Pollinia. — In Milkweeds and in most Orchids all the pollen of an
anther cell is compacted or coherent into one mass, called a pollen
mass, or POLLINIUM, plural POLLINIA (Figs. 225, 226).

The Ovule

277. Ovule (from the Latin, meaning a little egg) is the technical
name of that which in the flower answers to and becomes the seed.

278. Ovules are naked in gymnospermous plants (as above de-
scribed) ; in all others they are inclosed in the ovary. They may be
produced along the whole length of the cell or cells of the ovary, and
then they are apt to be numerous ; or only from some part of it, gen-
erally the top or the bottom. In this case they are usually few or
single (solitary, as in Figs. 228-230). They may be sessile, i.e. without

THE FLOWER

137

stalk, or they may be attached by a distinct stalk, the FUNICLE or
FUNICULUS (Fig. 227).

22T 228

227-230. Ovules: 227, a cluster of ovules, pendulous on their funicles; 228,
section of the ovary ^f a Buttercup, lengthwise, showing its ascending
ovule ; 229, section of the ovary of Buckwheat, showing the erect ovule ;
230, section of the ovary of Anemone, showing its suspended ovule.

279. In structure an ovule is a pulpy mass of tissue, usually with
one or two coats or coverings. The following parts are to be noted;
viz. : —

KERNEL or NUCELLUS, the body of the
ovule. In the Mistletoe and some related
plants, there is only this nucellus, the coats
being wanting.

TEGUMENTS, or coats, sometimes only one,
more commonly two, an outer and an inner

one' 231. Longitudinal section of

ORIFICE, or FORAMEN, an opening an ovule enlarged,

through the coats at the organic apex of the

ovule. In the seed it is micropyle.

CHALAZA, the place where the coats and

the kernel of the ovule blend.

HILUM, the place of junction of the funiculus with the body of the

ovule.

280. The Kinds of Ovules. — The ovules in their growth develop in
three or four different ways, and thereby are distinguished into

showing the parts:
a, outer coat; 6,
inner coat; c, nu-
cellus ; d, raphe.

232-235. Ovules: 232, orthotropous ovule of Buckwheat: c, hilum and cha-
laza; /, orifice; 233, campylotropous ovule of a Chickweed : c, hilum
and chalaza ; /, orifice; 234, amphitropous ovule of Mallow : f, orifice ;
h, hilum ; r, raphe; c, chalaza; 235, anatropous ovule of a Violet; the
parts lettered as in the last.

Orthotropous, or straight, those which develop without curving or
turning, as in Fig. 232. The chalaza is at the insertion or base ; the

138 THE FLOWER

foramen or orifice is at the apex. This is the simplest, but the least
common, kind of ovule.

Campylotropous, or incurved, in which, by the greater growth of one
side, the ovule curves into a kidney-shaped outline, so bringing' the
orifice down close to the base or chalaza ; as in Fig. 233.

Amphitropous, or half-inverted, Fig. 234. Here the forming ovule,
instead of curving perceptibly, keeps its axis nearly straight, and, as
it grows, turns round upon its base so far as to become transverse to
its funiculus, and adnate to its upper part for some distance. There-
fore in this case the attachment of the funiculus or stalk is about the
middle, the chalaza is at one end, the orifice at the other.

Anatropous, or inverted, as in Fig. 235, the commonest kind, so
called because in its growth it has as it were turned over upon its
stalk, to which it has continued adnate, the attached portions o£ the
stalk being known as the raphe. The organic base, or chalaza, thus
becomes the apparent summit.

Arrangement of Parts in the Bud

281. Estivation was the fanciful name given by Linnaeus to denote
the disposition of the parts, especially the leaves of the flower, before
anthesis, i.e. before the blossom opens. Prcefloration, a better term, is
sometimes used. This is of importance in distinguishing different
families or genera of plants, being generally uniform in each. The
aestivation is best seen by making a cut across the flower bud ; and
it may be expressed in diagrams, as in the accompanying figures.

ff

y

240

282- The pieces of the calyx or the corolla either overlap each
other in the bud, or they do not. When they do not overlap, the
aestivation is

Valvate, when the pieces meet each other by their abrupt edges,
without any infolding or overlapping, as in the calyx of the Linden or
Basswood (Fig. 236).

Induplicate, which is valvate with the margins of each piece project-
ing inwards, as in the calyx of a common Virgin's-bower (Fig. 238), or

Involute, which is the same, but with the margins rolled inward,
as in most of the large-flowered species of Clematis (Fig. 239).

Reduplicate, a rarer modification of valvate, is similar, but with
margins projecting outward.

Open, the parts not touching in the bud, as the calyx of Mignonette.

THE FLOWER 139

283. When the pieces overlap in the bud, it is in one of two ways ;
either every piece has one edge in and one edge out, or some pieces
are wholly outside and others wholly inside. In the first case the
aestivation is

Convolute, also named contorted or twisted, as in Fig. 240, a cross
section of a corolla very strongly thus convolute or rolled up to-
gether. Here one edge of every petal covers the next before it, while
its other edge is covered by the next behind it. The other mode
is the

Imbricate, or imbricated, in which the outer parts cover or overlap
the inner so as to "break joints," like tiles or shingles on a roof;
whence the name (calyx in Fig. 237).

284. The imbricate and the convolute modes sometimes vary one
into the other, especially in the corolla.

285. In a gamopetalous corolla or gamosepalous calyx, the shape
of the tube in the bud may sometimes be noticeable. It may be

Plicate, or plaited, that is, folded lengthwise; and the plaits may
either be turned outward, forming projecting ridges, as in the
corolla of Campanula; or turned inward, as in that of Gentian
or of Belladonna.

Position and Arrangement of Flowers, or Inflorescence

286. Inflorescence, which is the name used by Linnaeus to sig-
nify mode of flower arrangement, is of three classes ; namely, inde-
terminate, when the flowers are in the axils of the leaves, that is,
are from axillary buds ; determinate, when they are from terminal
buds, and so terminate a stem or branch ; and mixed, when these two
are combined.

287. Indeterminate, or indefinite,
Inflorescence is so named because, as
the flowers all come from axillary buds,
the terminal bud may keep 011 grow-
ing and prolong the stein indefinitely.
This is so in Moneywort (Fig. 241).

288. When flowers thus arise singly from the axils of ordinary
leaves, they are axillary and solitary, not collected into flower clusters.

289. But when several or many flowers are produced near each
other, the accompanying leaves are apt to be of smaller size, or of
different shape or character: then they are called BRACTS, and the
flowers thus brought together form a cluster. The kinds of flower
clusters of the indeterminate class have received distinct names, ac-
cording to their form and disposition. They are principally raceme,
corymb, umbel, spike, head, spadix, catkin, and panicle.

290. In defining these it will be necessary to use some of the fol-
lowing terms of descriptive botany which relate to inflorescence. If a

140 THE FLOWER

flower is stalkless, i.e. sits directly in the axil or other support, it is said
to be sessile. If raised on a naked stalk of its own (as in Fig. 241), it
is pedunculate, and the stalk is a PEDUNCLE.

291. A peduncle on which a flower cluster is raised is a common
peduncle. That which supports each separate flower of the cluster is a
partial peduncle, and is generally called the PEDICEL. The portion
of the general stalk along which flowers are disposed is called the
axis of inflorescence, or, when covered with sessile flowers, the rachis
(backbone), and sometimes the receptacle. The leaves of a flower
cluster generally are termed BRACTS. But when bracts of different
orders are to be distinguished, those on the common peduncle or axis,
and with a flower in their axil, keep the name of bracts ; and those
on the pedicels or partial flower stalks, if any, that of BRACTLETS.

292. A Raceme (Fig. 242) is that form of flower cluster in which
the flowers, each on its own foot stalk or pedicel, are arranged along
the sides of a common stalk or axis of inflorescence ; as in the Lily

of the Valley, Currant,
Barberry, one section of
Cherry, etc. Each flower
comes from the axil of a
small leaf, or bract, which,
however, is often so small
that it might escape notice,
242^ 243 244 and even sometimes (as in

the Mustard family) dis-
appears altogether. The lowest blossoms of a raceme are of course
the oldest, and therefore open first, and the order of blossoming is
ascending. The summit never being stopped by a terminal flower,
may go on to grow, and often does so (as in the common Shep-
herd's Purse), producing lateral flowers one after another for many
weeks.

293. A Corymb (Fig. 243) is the same as a raceme, except that it
is flat and broad, either convex, or level-topped. ThaJ is, a raceme
becomes a corymb by lengthening the lower pedicels, while the upper-
most remain shorter. The axis of a corymb is short in proportion to
the lower pedicels. By extreme shortening of the axis the corymb
may be converted into

294. An Umbel (Fig. 244), as in the Milkweed, a sort of flower
cluster where the pedicels all spring apparently from the same point,
from the top of the peduncle, so as to resemble, when spreading, the
rays of an umbrella ; whence the name. Here the pedicels are oome-
times called the rays of the umbel. And the bracts, when brought
in this way into a cluster or circle, form what is called an INVOLUCRE.

295. The corymb and the umbel being more or less level-topped,
bringing the flowers into a horizontal plane or a convex form, the

THE FLO WEE

141

ascending order of development appears as centripetal. That is, the
flowering proceeds from the margin or circumference regularly toward
the center; the lower flowers of the former answering to the outer
ones of the latter.

296. In these three kinds of flower clusters, the flowers
are raised on conspicuous pedicels or stalks of their own.
The shortening of these pedicels, so as to render the flowers
sessile or nearly so, converts a raceme into a spike, and a
corymb or an umbel into a head.

297. A Spike is a flower cluster with a more or less
lengthened axis, along which the flowers are sessile or nearly
so ; as in the Plantain (Fig. 245).

298. A Head is a round or round-
ish cluster of flowers, which are sessile
on a very short axis or receptacle, as
in the Buttonball, Buttonbush (Fig.
246), and Red Clover. It is just what a spike
would become if its axis were shortened ; or an
umbel, if its pedicels were all shortened until
the flowers became sessile. The head of the
Buttonbush is naked; but that of the Thistle,
of the Dandelion, and the like, is surrounded
by empty bracts, which form an involucre. Two

particular forms of the spike and the head have received particular

names ; namely, the spadix and the catkin.

299. A Spadix is a fleshy spike or head, with small
and often imperfect flowers, as in the Calla, Indian Tur-
nip (Fig. 173), Sweet Flag, etc. It is commonly sur-
rounded or embraced by a peculiar enveloping leaf,
called a SPATHE.

300. A Catkin, or ament, is the name given to the
scaly sort of spike of the Birch (Fig. 247) and Alder,
the Willow and Poplar, and one sort of flower clusters
of the Oak, Hickory, and the like, — the so-called amen-
taceous trees.

301. Compound flower clusters
of these kinds are not uncommon.
When the stalks which in the
simple umbel are the pedicels of
single flowers themselves branch into an umbel,
a compound umbel is formed. This is the inflor-
escence of Caraway (Fig. 248), Parsnip, and

almost all of the great family of umbelliferous (umbel-bearing)

plants.

The secondary or partial umbels of a compound umbpl are

Jf

247

248

142

THE FLOWER

UMBELLETS. When the umbellets are subtended by an involucre,
this secondary involucre is called an INVOLUCEL.

302. A compound raceme is a cluster of racemes racemosely ar-
ranged, as in Smilacina racemosa. A compound corymb is a corymb,
some branches of which branch again in the same way,
as in Mountain Ash. A compound spike is a spicately
disposed cluster of spikes.

303. A Panicle, such as that of Oats and many
Grasses, is a compound flower cluster of a more or less
open sort which branches with apparent irregularity,
neither into corymbs nor racemes. Figure 249 repre-
sents the simplest panicle. It is, as it were, a raceme
of which some of the pedicels have branched 'so as to
bear a few flowers on pedicels of their own, while
others remain simple. A compound panicle is one that
branches in this way again and again.

304. Determinate Inflorescence is that in which the
flowers are from terminal buds. The simplest case is
that of a solitary terminal flower, as in Fig. 250. This
stops the growth of the stem; for its terminal bud,

becoming a blossom, can no more lengthen in the manner of a leaf
bud. Any further growth must be from axillary buds developing
into branches. If such branches are leafy shoots, at length terminated
by single blossoms, the inflorescence still consists of solitary flowers at
the summit of stern and branches. But if the flowering branches
bear only bracts in place of ordinary leaves, the result is the kind of
flower cluster called

305. A Cyme. — This is commonly a flat-topped or convex flower
cluster, like a corymb, except that the blossoms are from terminal
buds. Figure 251 illustrates the simplest cyme in a plant with opposite
leaves ; namely, with three flowers. The middle flower, a, terminates
the stem ; the two others, bb, terminate branches, one from the axil
of each of the uppermost ft a 6

leaves; and being later than
the middle one, the flowering
proceeds from the center out-
ward, or is centrifugal. This
is the opposite of the indeter-
minate mode, or that where all
the flower buds are axillary.
If flowering branches appear from the axils below, the lower ones are
the later, so that the order of blossoming continues centrifugal or,
which is the same thing, descending, as in Fig. 253, making a sort
of reversed raceme or false raceme, — a kind of cluster which is to
the true raceme Just what the flat cyme is to the corymb.

251

252

THE FLOWER

143

f

253. Diagram of a
simple cyme
in which the
axis length-
ens, so as- to
take the form
of a raceme.

306. Wherever there are bracts or leaves, buds may be produced
from their axils and appear as flowers. Figure 252 represents the case
where the branches, bb, of Fig. 251, each with a pair of small leaves
or bracts about their middle, have branched again, and produced the
branchlets and flowers, cc, on each side. It is the continued repetition
of this which forms the full or compound cyme,

such as that of the Hobblebush, Dogwood, and
Hydrangea.

307. A Fascicle (meaning a bundle), like that
of the Sweet William and Lychnis of the gardens,
is only a cyme with the flowers much crowded
together.

308. A Glomerule is a cyme still more com-
pacted, so as to imitate a head. It may be known
from a true head by the flowers not expanding
centripetally ; that is, not from the circumference
toward the center.

309. Scorpioid or Helicoid Cymes, of various
sorts, are forms of determinate inflorescence (often
puzzling to the student) in which one-half of the
ramification fails to appear. So that they may
be called incomplete cymes. The commoner forms

may be understood by comparing a complete cyme, like that of
Fig. 252, with Fig. 254, the diagram of a cyme of an opposite-leaved
plant, having a series of terminal flowers
and the axis continued by the development
of a branch in the axil of only one of the
leaves at each node. The dotted lines on
the left indicate the place of the wanting
branches, which if present would convert
this scorpioid cyme into the complete one
of Fig. 252. Figure 254 a is a diagram
of similar inflorescence with alternate
leaves. An axis made up in this way of a
succession of branches is termed a sympodium.

310. Mixed Inflorescence is that in which the two plans are mixed
or combined in compound clusters. A mixed panicle is one in which,
while the primary ramification is of the indeterminate order, the
secondary or ultimate is wholly or partly of the determinate order. A
contracted or elongated inflorescence of this sort is called a THYRSUS.
Lilac and Horse-chestnut afford common examples of mixed inflores-
cence of this sort. When loose and open such flower clusters are called
oy the general name of panicles. The heads of Composite are cen-
tripetal; but the branches or peduncles which bear the heads are
usually of centrifugal order.

254 a

144 LABORATORY STUDIES OF THE FRUIT

XIII. LABORATORY STUDIES OF THE FRUIT

The whole purpose of the fruit is embodied in the seed.
The portion external to the seed is important in the life
history of the plant only as it ministers to the maturing,
preservation, transporting, or planting of the germ. The
ways in which the character of the exterior parts of the
fruit affects the destiny of the seed will be studied after
the general structure of fruits has been examined.

The studies of the first Exercise have to do with the
parts of the fruit external to the seed ; the second
Exercise is concerned with the seed itself ; and the third,
with dissemination.

EXERCISE XXXV. FLORAL ORGANS INVOLVED IN THE FRUIT

Wild Indigo. — Notice the base and the slender termination of the
pod. What was this termination in the flower ? What .still surrounds
the pod stalk? Can you discover any marks of other organs, now
fallen away ? Open the pod : where are the seeds attached ? Pod and
seeds are the ripened forms of what members of the flower? How
many carpels in this fruit ? The ripened ovary is termed the pericarp.

Violet. — After examining all exterior features, cut a cross section.
With the lens, and by trying the seeds with a needle, find the places
of attachment. How many placentae, f Of how many carpels is the
pod composed? From dried and opened specimen0 determine whether
the pod bursts between the carpels or along the carpellary midribs.
Of what floral organ does the fruit consist ?

Cranberry. — Opposite the stem end is a slight hollow, roughly
square, edged and often nearly covered in by four projections. Cut
these projections away. Observe the bottom of the depression. At
the center is a single scar, marking the position of what member of
the flower ? Around this, within the crater, notice two circles of scars.
What are they ? Finally, what is the nature of the four projections
first noticed and then cut away? Parts of what organs of the original
flower now compose the berry?

Cut the fruit transversely. How many carpels compose it? The
size of the cavities in which the seeds lie is striking when compared
with the minute size of the seeds themselves. Will the berry float?
Try it. Count and record the number of seeds.

Draw : Wild Indigo. The pod, with persistent calyx. This sort of
fruit is termed a legume.

Violet. Cross section, to show the seeds attached ( x 5). The
dehiscent fruit ( x 2). The fruit is termed a capsule.

LABORATORY STUDIES OF THE FRUIT 145

Cranberry. Cross section, showing cavities and attachment of seeds
(x 2). The terminal depression showing remains of the flowers
( x 10). Soft, fleshy fruits of this sort are termed berries.

Checkerberry. — Dissect the fruit. What is the morphological
nature of the lower, fleshy part ?

Draw a longitudinal section to show all parts — including the seeds
in one of the cavities — and their arrangement (x 3).

The Rose hip. — Examine the fruit to discover, if possible, where
the floral parts were situated. Cut the hip open. Are seeds seen?
Are seeds of Angiosperms produced in an open receptacle or cavity, as
these seedlike bodies are? Are they seeds or fruits? The hollow,
pulpy portion bearing them on its inner surface is an enlarged
receptacle.

Draw a diagram representing a longitudinal section ( x 2-3).

EXERCISE XXXVI. THE SEED

The student is already familiar with the interior of the seed — with
embryo and albumen. The integuments need to be looked at more
particularly than has been done heretofore.

Squash. — Notice the place at which the seed was broken from its
connection with the placenta. It is called the hilum. Beside this there
is a distinct aperture leading into the interior, the micropyle. Cut
away the shell. How many seed coats? This is the characteristic
number. The outer is the testa; the inner, the tegmen.

Draw a cross section of the Squash seed (diagrammatic).

Castor Bean. — On one side observe a straight, dark line, running
three quarters the length of the seed (the raplie). At one end is a
very slight elevation, the point at which the coats are organically
connected with the kernel ; this point is the chalaza. At the other
end is the hilum, nearly covered by a structure called the caruncle.

Bean. — At one side of the hilum is the micropyle, more easily made
out if the material has been properly soaked. On the other side of
the hilum, running to the end of the bean, is a ridge, more or less
indistinct — the raphe. Overlying its inner extremity, next the hilum,
is a heart-shaped, purple excrescence, called the strophiole.

Draw the bean, showing the features indicated ( x 3).

Outgrowths of the testa. — By the aid of the hand lens make
enlarged drawings of the seeds of Milkweed and of the Trumpet
Creeper. Cut the seed of the Cotton Plant in half. Draw the
section, so as to show the length of the Cotton fibers relatively to the
diameter of the seed proper. What is the use of these outgrowths ?

EXERCISE XXXV1T. THE FRUIT IN RELATION TO DISSEMINATION

The need of dissemination will be most keenly realized by a rough
computation of the number of seeds produced by a single plant, all
OUT. or ROT. — 10

146 LABORATORY STUDIES OF THE FRUIT

of which would have a chance of germinating upon the plot of ground
occupied by the parent, unless carried elsewhere. Take as an example
the Cranberry, studied in Exercise XXXV. Allow fifty berries to a
single bush, and multiply by the number of seeds actually observed
in one berry. The resulting product represents the possible number
of seedlings upon less than a square yard of ground.

That even one seedling should occupy part of the soil held by the
parent plant would evidently be disadvantageous to both. Accord-
ingly, plants exhibit a great variety of devices by which the service
of various agencies is secured for the dispersal of the seeds. The
means of dissemination may be (1) some feature of the coat of the
seed itself, (2) some special character, construction, or outgrowth of
the pericarp. The first case has been seen in the Milkweed; the
second remains to be studied in more- detail.

Bladder Nut. — Examine the bladdery fruit before dehiscence, not-
ing (1) the morphology of the pericarp, (2) the number of carpels,
and (3) the relative size of the pericarp and the seeds. Place the
fruit on the table. Blow it about. The object of the inflated peri-
carp becomes apparent.

Draw the fruit, natural size. Indicate in dotted line the position
and size of the seed.

Curled Dock. — With a lens examine the three-winged and coarsely
veined parts, each bearing at its base a granule resembling a seed.
They are persistent sepals, and are closely appressed. Hidden between
them is the three-angled achene (dry pericarp, containing a single
seed). The dispersal apparatus here comes from the calyx. Note
how readily the fruit is driven by a mere breath.

Draw the fruit, with one sepal removed to show achene, magnified
about eight diameters.

Bur Marigold. — The barbed bristles, well seen with the lens, are
morphologically the border of the calyx, the lower part of which is
adherent to the pericarp. What is the mode of dissemination ?

Draw the fruit, magnified about four diameters.

Witch-hazel. — Notice : —

(1) The pericarp proper, with the old calyx surrounding the lower
half. (2) The partial splitting at the tips of unopened fruits. (3) The
number of cells (loculi) in the opened capsules. (4) The mode of
dehiscence. The loculi are split open along the median line in each
case. This is locnllcidal dehiscence. (5) The backward curving of the
open jaws. (6) The very hard, smooth inner surface of the loculi, and
the similar surface of the seeds, which indeed makes it rather difficult
to hold them securely between finger and thumb. (7) Cut away the
calyx and the outer, softer layer of the pericarp. It will be seen that
the inner and immediate receptacle of the seeds is a bony and rather
thick-vailed double case. There was originally one seed in each

THE FRUIT 147

compartment. (8) The halves (valves) of the seed case are separated
nearly to the middle, cohering only by their basal portions. (9) The
edges of the inner, bony seed cases curve in somewhat, as if com-
pressed. (10) Try to fit the seeds back into the cases. Are the cases
large enough to cover the seeds ?

The fruit of Witch-hazel is a projectile apparatus. As the valves
open wider and wider, in the process of drying, the seeds are squeezed
more and more by the shrinkage of the bony layer and the incurving
of the valve edges. At a certain point, the intensity and direction of
pressure become such that the seed is shot out with much force —
enough force, under the most favorable conditions, to carry the seed
to a distance of forty or fifty feet.

Draw whatever is necessary to illustrate your notes on this fruit.

XIV. THE FRUIT

311. Nature of the fruit. — The mature ovary is the
Fruit. In the strictest sense the fruit is the seed vessel,
technically named the PERICARP. But practically it may
include other parts organically connected with the peri-
carp. The calyx especially, or a part of it, is often in-
corporated with the ovary, so as to be indistinguishably
a portion of the pericarp. The receptacle forms, along
with the calyx, the whole bulk of such edible fruits as
Apples and Pears. The receptacle is an obvious part in
Blackberries (see Fig. 256), and is the whole edible por-
tion in the strawberry.

312. A cluster of distinct carpels may, also, in ripening,
be consolidated or compacted, so as practically to be taken
for one fruit. Such are Raspberries, Blackberries, etc.
Moreover, the ripened product of many flowers may be
compacted or grown together so as to form a single com-
pound fruit.

THE KINDS OF FRUITS

313. In respect to composition, fruits may be classified
into

Simple, those which result from the ripening of a single
pistil, and consist only of the matured ovary, either by
itself, as in a Peach (Fig. 255), or with the receptacle and

148

THE FRUIT

255. Sectioii of a Peach.

calyx tube completely incorporated with it, as in the Goose-
berry and Pear (Fig. 259).

Aggregate, when a cluster of carpels of the same flower
are crowded into a mass ; as in
Raspberries and Blackberries (Fig.
256).

Accessory, when the surroundings
or supports of the pistil make up
a part of the mass. In an accessory
fruit such as the Strawberry the great
mass is receptacle (Fig. 156).

Multiple or collective, when formed

from several flowers consolidated into one mass, of which

the common receptacle or axis of

inflorescence, the floral enve-
lopes, and even the bracts, etc.,

make a part. A Mulberry (Fig.

257, which superficially much

resembles a Blackberry) is of

this multiple sort. A Pineapple

is another example.

Stone fruits, or drupaceous

(Fig. 255), the outer part fleshy

like a berry, the inner hard or

stony, like a nut ; and

Dry fruits (Fig. 266), those 257

which have no flesh or pulp.

314. In reference to the splitting apart of the pericarp
for the liberation of the seeds, fruits are said to be

Dehiscent, when they open regularly along certain lines.
A dehiscent fruit almost always contains many or several
seeds, or at least more than one seed (Fig. 267).

Indehiscent, when they do not open at maturity. Fleshy
fruits and stone fruits are of course indehiscent. The
seed becomes free only through decay or by being fed
upon by animals. Of dry fruits also many are indehiscent.

315. The principal kinds of fruits which have received
distinctive names are the following : —

257

256. Aggregate fruit of the
Blackberry : consisting
of a number of ripened
pistils crowded on a
fleshy receptacle. At
the right, one of the in-
dividual fruits (a drupe)
further enlarged.
Multiple fruit of the Mul-
berry.

THE FRUIT

149

258. Fruit of the
Cranberry.

259.

Sections of
Pear.

316. The berry, such as the Gooseberry and Currant, the Blueberry
and Cranberry (Fig. 258), the Tomato, and the Grape.

Here the whole flesh is soft throughout. The Orange
is a berry with a leathery rind.

317. The pome, a name applied
to the Apple, Pear (Fig. 259), and
Quince. These are fleshy fruits,
like a berry, but the principal
thickness is the enlarged receptacle,
only the papery pods arranged like
a star in the core really belonging
to the carpels.

318. The drupe, or stone fruit,
of which the Cherry, Plum, and
Peach (Fig. 255) are familiar exam-
ples. In these the outer part of the
thickness of the pericarp becomes

fleshy, or softens like a berry, while the inner hardens like a nut.

Two portions of the drupe are thus distinguishable, named respec-
tively exocarp — the outer, fleshy layer;
and the endocarp — the innermost layer,
the stone.

319~, Of dry fruits there is a great
diversity of kinds having distinct names.
320. The achene is a small, dry, and
indehiscent one-seeded fruit, often so
seedlike in ap-
pearance that it is
popularly taken

for a naked seed. The fruit of the Buttercup

is a good example (Fig. 260). Its nature, as

a ripened pistil (in this case a simple carpel),

is apparent by its bearing the remains of a

style or stigma, or a scar from which this has

fallen. It may retain the style and use it in

various ways for dissemination (Fig. 261).
321. The fruit of Compositse (though not

of a single carpel) is also an achene. In this

case the pericarp is invested by an adherent

calyx tube, the limb of which, when it has 261 Acnei,e of Clematis,

any, is called the PAPPUS. This name was

first given to the down like that of the Thistle,

but is applied to the limb of the calyx, in

whatever form it appears, of the "compound

flower." In Lettuce, Dandelion (Fig. 263), and the like, the achene

260. Achene of Buttercup
the right, opened
show the seed.

the style retained
as a plume for
purposes of dis-
persal by winds.

150

THE FRUIT

262 263

262, 263. Achenes : 262,
of a Thistle, pro-
vided with a pap-
pus for wind-dis-
semination; 263,
of a Dandelion,
the pappus borne
on a long beak.

264. 265. Samara
An Acorn, of the Elm.

as it matures tapers upwards into a slender beak, like a stalk to the
m Pappus.

f- ;^ *&%• ^ carv°Psis> or Srain> is like an achene

with the seed adhering to the thin pericarp
throughout, so that both are incorporated into
one body ; as in Wheat, Indian Corn.
I 323. A nut is a dry and indehiscent fruit,

I commonly one-celled and one-seeded, with a
\ \ hard, crustaceous, or bony wall, such as the
™ Cocoanut, Hazelnut, Chestnut, and the Acorn
(Fig. 264). Here the involucre, in the form of
a cup at the bas6j is called the CUPULE. In

tlie Chestnut> near relative of the Oak, the

cupule forms the bur ; in the Hazel, another

relative, a leafy husk.
324. A samara, or

key fruit, is either a

nut or an achene, or any

other indehiscent fruit, furnished with a wing,
like that of Ash, and Elm (Fig. 265). The
Maple fruit is a pair of keys (Fig. 266).

325. Dehiscent fruits, -or pods, are of two
classes, viz., those of a simple pistil or carpel,

and those of a compound pistil. Two common sorts of the first are
named as follows : —

326. The follicle, a fruit of a simple carpel,
which dehisces down one side only, i.e. by
the inner or ventral suture. The fruits of

Marsh Marigold (Fig. 267)
are of this kind.

327. The leg-
ume or true pod,

such as the Pea

pod (Fig. 268),

and the fruit of

the Leguminous

or Pulse family

generally, which

opens along the

dorsal as well as

the ventral suture.

The two pieces into which it splits are called
VALVES. A LOMENT is a legume which is con-
stricted between tho seeds, and at length breaks
up crosswise into distinct joints, as in Fig. 269.

266 267

266. Fruit of the Maple.

267. Follicle of the Marsh Mari-

gold.

268

268. A Legume.

269. ALoment.

THE FEU IT

151

271.

328. The pods or dehiscent fruits belonging to a compound ovary
have several technical names : but they all may be regarded as
kinds of

329. The capsule, the dry and dehiscent fruit of any
compound pistil. The capsule may discharge its seeds
through chinks or pores, as in the Poppy, or burst irregu-
larly in some part, as in Lobelia and the Snapdragon;
but commonly it splits open (or is dehiscent) lengthwise
into regular pieces, called VALVES.

330. Regular dehiscence in a capsule takes place in

two ways, which are best illustrated
in pods of two or three cells. It is
either

Loculicidal, or, splitting directly
into the loculi or cells, that is, down the back (or
the dorsal suture) of each cell or carpel, as in
Iris (Fig. 270) ; or

Septicidal, that is, splitting through the parti-
tiong or septat ag in gt> JohnVwort (Figt 271),

Rhododendron, etc. This divides the capsule
into its component carpels, which then open
by their ventral suture.

331. In loculicidal dehiscence the valves naturally bear the parti-
tions on their middle ; in the septicidal, half the partition is borne on
the margin of each valve. See the annexed diagrams, Fig. 272. A

270. Capsule
of Iris.

John's-wort!

272. Diagrams of the various modes
of dehiscence : a, loculicidal ;
6, septicidal ; c, d, septifragal.

274

273, 274. Fruit of the Fig : 273, fruit
laid open ; 274, a part magnified
to show the minute, interior
flowers.

variation of either mode occurs when the valves break away from the
partitions, these remaining attached in the axis of the fruit. This is
called septifragal dehiscence.

332. The syconium, or fig fruit (Fig. 273), is a fleshy axis or
summit of stem, hollowed out, and lined within by a multitude of
minute flowers, the whole becoming pulpy, and, in the common fig?
luscious.

152 THE FEUIT

THE SEED

333. Seeds are the final product of the flower, to which all its parts
and offices are subservient. Like the ovule from which it originates,
a seed consists of coats and kernel.

334. The seed coats are commonly two,
the outer aud the inner. Fig. 275 shows the
two, in a seed cut through lengthwise. The
outer coat is often hard or crustaceous, whence
275. a, hilum; 6, testa; ^ ig called the testa, or shell of the seed; the
c, inner coat; d, inner is almost always thin and delicate,
albumen; e, em- 335. The shape and the markillgs, so vari-
ous in different seeds, depend mostly on the

outer coat. Sometimes this fits the kernel closely; sometimes it is
expanded into a wing, as in the Trumpet Creeper (Fig. 276, a), and
occasionally this wing is cut up into shreds or tufts, as in the .Catalpa
(Fig. 276, ft) ; or instead of a wing the seed may bear a coma, or tuft
of long and soft hairs, as in the Milkweed or Silk weed
(Fig. 276, c). The use of wings or downy tufts is to render
the seeds buoyant for dispersion by the winds. This is
clear, not only from their evident adaptation to this pur-

276. Seeds fitted by outgrowths of the testa for dispersion by the winds :
a, Trumpet Creeper; 6, Catalpa; c, Milkweed.

pose, but also from the fact that winged and tufted seeds are found
only in fruits that split open at maturity, never in those that remain
closed. The coat of some seeds is beset with long hairs or wool.
Cotton, one of the most important vegetable products, since it forms
the principal clothing of the larger part of the human race, consists
of the long and woolly hairs which thickly cover the whole surface
of the seed. There are also crests or other appendages of various
sorts on certain seeds. A few seeds have an additional, but
more or less incomplete, covering outside of the real seed
coats, called an

336. Aril, or arillus. — The loose and transparent bag
which incloses the seed of the White Water Lily (Fig. 277)
is of this kind. So is the mace of the Nutmeg. The aril is
a growth from the extremity of the seed stalk, or from the
placenta when there is no seed stalk.

A short and thickish appendage or outgrowth around the micropyle
in certain seeds is called a CARUNCLE (Fig. 278).

THE FRUIT 153

The various terms which define the position or direction of the
ovule (erect, ascending, etc.) apply equally to the seed : so also the
terms anatropous, orthotropous, campy lotropo us,1 etc., as
already denned, and such terms as

HILUM, or scar left where the seed stalk or funiculus
has fallen away, or where the seed was attached directly
to the placenta if there was no seed stalk.

RAPHE, the line or ridge which runs from the hilum
to the chalaza in anatropous and amphitropous seeds.

CHALAZA, the place where the seed coats and the kernel
or nucellus are organically connected, — at the hilum in orthotropous
and campylotropous seeds, at the extremity of the raphe or tip of
the seed in other kinds.

MICROPYLE, answering to the foramen or orifice of the ovule.

ECOLOGY OF THE FRUIT AND SEED AS REGARDS DIS-
SEMINATION

337. The word dissemination here signifies the scatter-
ing of the seeds. In a vast number of cases not only the
seeds, but the entire fruits, are dispersed, the pericarp fur-
nishing the same protection to the seed that it provided
during the period of ripening, and furthermore aiding
directly by its construction in the transportation or even
in the planting of the seed.

338. The need of seed dispersal is plain, both for the
parent plant — which should not be crowded by its own
offspring — and for the interests of the seedlings them-
selves. That an advantage is to be won through wide dis-
tribution of seed is shown by the fact that the seed or
the fruit is, in most species, adapted to the special work
of dissemination.

339. The agents of dissemination are wind, water, and
animals. But a considerable number of plants are quite
independent of external aid, being provided with special
mechanisms for throwing their seeds to a distance.

340. Structures to accomplish dissemination through the
agency of the winds are exemplified by the wings of the
Elm and Maple fruits (Figs. 265, 266), the plume of

1 For these terms see the section on the ovule, § 280.

154

THE FRUIT

the Clematis achene (Fig. 261), and the tufted pappus
in the case of the Dandelion (Fig. 263). The wing of
the Maple key does not avail to carry the seed very far
from the source, on the average, as may be seen if we
examine the neighborhood of a Maple tree when the seed-
lings are coming up in the spring. The seedlings are
very numerous near the paront, very few at a distance of
two or three times the height of the tree. But one can-
not fail to be struck with the successful planting of the
seeds. Although not originally covered by the soil, they
stand in multitudes, rooted and growing, in spots where
the grass was beaten down and matted before the fruits
fell. Though bulky, the keys find their way into the
grass through the action of the winds in driving the
wings this way and that, until the seed ends have been

worked Avell toward the moist sur-
face of the soil. This example
illustrates the fact, of common
occurrence, that appendages of
the fruit may serve both in dis-
semination and in placing the seed
in the position most likely to
secure germination.

341. In connection with this
subject, the mechanism of Ero-
dium (Fig. 279) for burying the
fruit may be mentioned. The
elongated extremity of the fruit
279. Fruit of Erodium. On is hygroscopic ; that is, it absorbs

the left a single carpel J &

vapor of water rapidly in damp
weather, and exhales it in dry.
the changes being accompanied
by twistings and untwistings.

As the fruit naturally falls with its weightier or seed
end toward the earth, these hygroscopic movements, aided
by backward-pointing hairs, enable it to work its waj
through grass or other impediments toward the soil, ant
finally even partially to bury itself.

in damp weather; at
the right, several car-
pels in the calyx, in dry
weather.

THE FRUIT 155

342. The appendages of seeds securing dissemination by
wind are very similar to those of fruits in many cases.
Compare, for instance, the seed of the Trumpet Creeper
(Fig. 276, a) with the fruit of the Elm (Fig. 265) ; and
the seed of the Milkweed (Fig. 276, c), possessing a coma,
or tuft of hairs, with the pappus-bearing achene of the
Thistle (Fig. 262).

343. Water. — The fruits of the Cocoanut Palm are
originally covered with husks impermeable to sea water.
They sometimes fall into the ocean, and being carried
to distant strands are cast up by the waves and there
germinate. In a like manner the achenes of the Arrow-
head (Sagittaria) — a plant which is common along the
margins of ponds — buoyed up by the air-filled cells of
the pericarp, are floated to a distance. In a number of
species they float for a definite length of time ; then,
when germination is about to begin, they sink to the
bottom.

344. Animals. — The fruits of many plants are thickly
set with hooks suited to catch in the fur of animals
(Fig. 280). The fruits are thus

separated from the plant and car-
ried away, to be subsequently re-
moved by the animals themselves
or brushed off accidentally. Nuts
hidden away in the ground by squir-
rels must occasionally be left to
grow, either through oversight or
on occasion of the death of the de- 28°- The f™!t of Asri-
positor. Then again, edible fruits

like the Cherry, the Apple, and the berries offer to
animals a substantial reward in return for the service
of dispersal.

345. Ejection of the seeds is not uncommon. The most
familiar example is that of the Jewelweed, or Touch-me-
not, the ripe pods of which, when touched, burst and
throw the seed in all directions. The bursting is due
to the sudden splitting asunder and coiling up of the

156

THE FRUIT

several valves, already in a high state of tension, the

touch which
produces the
explosion
merely in-
creasing the
stress along the lines
of dehiscence. The
opened valves of the Vio-
let fruit, constricting,
cause the forcible expul-
sion of the seeds one after
another. The hard, bony
capsules of the Witch-

281. Fruit of Witch-hazel discharging hazel (Fig. 281), contract-
ing, squeeze the smooth,

hard seeds with much force ; and the seeds are shot to a
distance of many feet.1

Supplementary Reading

1. Plants that bury their Seeds. Lubbock's " Flowers, Fruits, and
Leaves," pp. 85-88.

2. The Fruits and Seeds of Plants Parasitic on Trees. Same
source, pp. 83, 84.

3. Dispersal of various Fruits and Seeds. Same source, Chap. III.

4. Dissemination of Plants by Ocean Currents and by Migrating
Birds. Darwin's " Origin of Species," Chap. XI, Dispersal.

1 If a bough with the ripe but unopened fruits is hung on the wall of
one's room, the force with which the seeds are ejected and the distance
to which they fly are likely to be observed.

Distances to which seeds are ejected by several plants are given by
Kerner and Oliver ("Natural History of Plants," II, 839) as follows: —

Cardamine impatiens 3 ft.

Viola canina 3 ft.

Geranium palustre 8 ft.

Lupinus digitatus ." 23 ft.

Acanthus mollis 31 ft.

Hura crepitans 48 ft.

Bauhinia purpurea 51 ft.

LABORATORY STUDIES OF CRYPTOGAMS 157

XV. LABORATORY STUDIES OF CRYPTOGAMS

[NOTE : — Many of the following types may be studied without
compound microscopes, if good hand lenses or, better, dissecting
microscopes, are provided. In the suggestions for study which fol-
low, (simple) following the number of a paragraph indicates that the
simple microscope is to be used; similarly, (compound) indicates that
a compound microscope is to be used ; and (compound or simple)
indicates that the simple microscope may be used, but the compound
is to be used if available. ]

. 346 (Compound). Nostoc. Make a note of the general character
— form, consistency, color, etc. — of the masses in which the plant
occurs. Mount a bit of the mass in a drop of water on a glass slide,
cover with a cover glass, pressing the latter down gently, and examine
first with a low, then with a higher power of the compound micro-
scope.

What constitutes one single individual plant? How are the indi-
viduals grouped? What is the color? Are any cells distinguished
by size or other character ? What holds the cells and chains (colonies)
together? Draw one chain by aid of the highest power you have.

347 (Compound). Unicellular Green Algae: Pleurococcus, or the
like. Upon what do the plants provided grow? Examine this sub-
stratum with the hand lens, to see if the individual plants causing the
green tinge on the surface can be distinguished. Then scrape a bit
of the green film into a drop of water on a glass slide, cover, and
examine with different powers of the compound microscope, the lowest
first. Do you find the plants single? In groups? If in both ways,
draw both. Is there anything in the number of plants in a group, or
in the position of the members of a group, or any other circumstance,
to suggest to you the way in which these plants multiply?

348 (Simple). Spirogyra. Use the simple lens to obtain an idea
of the actual size of the plants. Do the filaments branch? Are there
cross partitions? Do any parts of the filaments differ markedly from
others ? How does the color differ from that of Nostoc, if at all ?
What portion of any cell bears the color? What is the arrangement
of the color-bearing bands (chromatophores) f

349 (Compound). Is there more than one chromatophore in each
cell ? Draw a short portion of one filament, using a moderate power.
Indicate, without drawing all of them, the arrangement of the chrc-
matophores.

350 (Compound). Select a cell (for example a terminal cell) in
which the spirals are rather loose. Look for the nucleus, near the
center, a colorless body from which colorless strings radiate. If this
is not distinguishable, delay search until after the following treatment.

158 LABORATORY STUDIES OF CRYPTOGAMS

Place a small drop of dilute (30 per cent) eosin glycerine at the edge
of the cover glass so that it will run under. If the glycerine reaches
the Spirogyra, many of the cells will now be found with their contents
much distorted. Does it appear that the contents are separable from
the walls oil all sides? Select a cell slightly affected. Is there a
definite layer of substance in which the chromatophores are imbedded ?
The nucleus, stained by the eosin, will now be readily made out.
Draw a cell highly magnified, showing a part of one chromatophore,
the nucleus, and the layer of living substance (protoplasm) where
separated from the wall.

351 (Compound). If material is provided, make drawings of con-
jugating cells, showing stages in the process. Label the rounded
bodies found where conjugation has been effected zygospores.

352 (Compound). Vaucheria. — Use the hand lens to gain an idea
of size and general habit. If the feltlike mass is growing on earth,
pick off a little with needles, using care to get rid of soil in the
preparation. Mount in water under the compound microscope. Are
the filaments septate (partitioned), or not? Focus on the upper sur-
face. What is the shape and size of the chromatophores here?
Focus down until the side walls stand out sharply. Do the chromato-
phores occur only near the walls, or are they scattered throughout the
interior of the tubes ? Do the filaments branch ?

353 (Compound). Do you find lateral club-shaped (not globular)
branches, or somewhat swollen tips of filaments, of a very dark green
color (sporangia) ? Are they cut off by partitions (septa) ?

354 (Compound). Look for short, nearly globular branches, in
company with others more slender, lighter green, and somewhat coiled.
If any of these can be made out clearly in all parts, draw them
(ob'gonia and antheridia). If the form and attachment are not clear,
turn to the figure given by the teacher, and with its help decide
whether the oogonia and antheridia are found on the material you
have. The species studied and that represented in the figure may
not be the same, in which case exact similarity of organs will not be
expected.

355 (Compound). Ectocarpus, exemplifying the Brown Algae. —
View with the hand lens, then with higher magnifications. Are the
main trunks more than one cell in thickness? The branches? Draw
a small, branching portion. Are there any very short branches dis-
tinguished by greater thickness? If so, are they .more than one cell
in thickness, or does each branch consist chiefly of one large terminal
cell, or sac, with granular contents? Draw both sorts of branches, if
found, labeling the many-celled ones gametangia, and the saclike ones
sporangia.

356 (Simple). Rockweed. — Make a life-size drawing from a
branching portion, to show the habit of the plant. With the hand

LABORATORY STUDIES OF CRYPTOGAMS 159

lens examine the thickened tips. Have the minute raised spots
openings?

357 (Compound or Simple). With a wet razor make a good many
sections, as thin as possible, across the tips where the raised spots are
thickest, and mount them in water. Have the cavities seen in the
sections, and more or less lined with dark bodies (oogonia), any rela-
tion to the little prominences before seen? Have the cavities (concep-
tacles) openings? Make a diagram two or more inches in diameter,
showing the cavity of a conceptacle as seen in section, with opening
if any, and adjacent external surface of the ihallus (or general body
of the plant). Show a few oogonia in proper proportion and form,
with some of the long filaments that spring from the walls of the con-
ceptacle.

358 (Compound). Examine the oogonia with the compound micro-
scope and draw if additional details are found. Look in the same
conceptacles (or in others from different plants, according to the
teacher's directions) for swollen cells borne on short filaments, much
smaller than the oogonia, and distinguished by coarsely granular
contents and orange color. These are the antheridia. If necessary
pick one of the sections apart with needles — or merely squeeze it
enough under the cover glass to break it up — in order to see how
these antheridia are borne. Make a drawing to show this. Also
indicate on the diagram before made the relative size and the posi-
tion of the antheridia in the conceptacle, (But if antheridia and
oogonia are not found together, use two diagrams.)

359 (Simple). Polysiphonia,1 one of the Red Alga?. — Draw the
habit of the plant, enlarged, as seen with the lens. Look for dark
round bodies embedded in some of the branches — the tetrasporangia.
Do they seem to be somewhat eccentrically placed, or are they situ-
ated centrally so as to occupy the whole diameter of the branch where
they occur? Draw a portion very much enlarged to show the facts.

360 (Compound). Are the filaments of the thallus (or plant
body) composed of more than single rows of cells? How do the
branches end? Into how many separate parts (tetraspores) is the
contents of each tetrasporangium divided? (It should be said that
the tetraspores are so arranged that one of them is always hidden
from view.) Draw a tetrasporangium with a short portion of the
thallus adjoining.

361 (Compound). Nemalion, a Red Alga. — Draw a short branch-
ing portion to show the filamentous habit. If possible select a piece
bearing the small, rounded antheridia at the tips. If so directed by
the teacher, seek to identify carpogonia and cystocarps by aid of the
figures provided.

1 Material bearing tetrasporangia is to he provided.

160 LABORATORY STUDIES OF CRYPTOGAMS

362 (Compound). Bacteria. — With a needle transfer to a slide a
bit of the scum, that gathers on water in which vegetable matter is
decaying. Cover with a cover glass and examine with a high power.
The Bacteria are glistening white (i.e. colorless) bodies of small size
often occurring in broad patches of gelatinous matter (the matter
which holds the " scum " together) in which they are more or less
evenly spaced ; or occurring in chains or threads. Some may be spiral
in form and exhibit very active motion. Having found the Bacteria,
remove the cover glass, spread the scum out thin on the slide, and
dry this preparation by holding it at some distance above a flame.
When the last bits of the spread scum are about to become dry,
remove from the heat and add drops of gentian violet stain.1 After
a moment wash this off with a little water, cover, and reexamine.
The various forms, now more plainly seen, are to be drawn.

For suggestions as to the biological study of Bacteria see Appendix.

363 (Compound). Yeast. — Mount in water a small bit of yeast
cake, spreading the material out thin, and examine with a high power.
Are the yeast plants of uniform size? Have they any peculiarity of
form, common to all, or nearly all (i.e. are they uniformly spherical,
or elliptical, or ovate, etc.)? Have they any common features of
internal structure? Having determined these points in your own
mind, make a drawing of a typical yeast plant of the species you have,
the drawing to be large enough to show easily any internal features.2

364 (Compound). From material that has been growing for a few
hours in sweetened water (a teaspoonful of sugar to a half glass of
water), study the method of multiplication. Do the buds — the new
individuals growing out from the bodies of the old plants — spring
from any particular region, as a rule? Draw in outline three stages
in the budding process.

365. Is any action of the yeast upon or in the sugar solution
to be seen? To test this, drop small pieces of yeast cake into tum-
blers of (1) sugar solution, (2) water alone. In fifteen minutes or
so the result should be observable, and within an hour very marked.
What bearing has the action observed upon the utility of yeast plants
in bread making? Answer this question in your notes on this
experiment.

366 (Simple). Bread Mold (Rhizopus nigricans). — Use the hand
lens to examine the moldy bread without disturbing it, so as to see

1 Strong eosin solution may be used, and it leaves the Bacteria with a
more lifelike appearance, though not so sharply denned. If the prepara-
tion is stained with gentian violet, washed, and thoroughly dried, Canada
balsam may be used upon it and the preparation thus be made permanent.

2 The teacher should draw upon the board the characteristic form and
striations of starch grains to be found in the yeast cafce, so mat they may
not be mistaken for the yeast plants.

LABORATORY STUDIES OF CRYPTOGAMS 161

how the mold grows. Especially notice the growth on the bottom of
the dish where the fungus is spreading away from the bread. Make
a much enlarged drawing to show the groups of stalked sporangia as
seen from the side. Are these groups connected in any way ? Are
there any special organs for attachment to the substratum ? Is the
number of sporangia in a group constant? Estimate the height of
the sporangial stalks in inches. State the magnification which your
drawing represents.

367 (Compound). With a needle carefully remove a bit of the
plant, selected from a spot where both white (young) and black (old)
fruiting heads (sporangia') can be seen, and mount in water, or better
in alcohol followed by a drop of water. Use first a low power, after-
wards a higher power. Have the threads partitions ? What is the
color and appearance of the contents? Compare an unopened spor-
angium with one where the external membrane has given way.
What portion of a whole head is occupied by spores? Answer by
drawings; show one of the spores separately, more enlarged.

368 (Compound). If material is furnished, draw two or three
stages to illustrate zygospore formation.

369 (Compound). Water Molds : Saprolegniaceae. — Upon what is
the given plant growing ? Remove a bit with forceps and needle to a
drop of water on a slide. Examine with the hand lens, to get an idea
of the actual size. Then use low and high powers of the microscope.
Are the hyphse of even diameter ? Is the protoplasm dense or thin ?
What is the shape of the ends of the hyphse? Answer these questions
in drawing.

Do you find certain branches filled with denser protoplasm, and
somewhat enlarged or club-shaped? Can you find stages leading
to this condition? Are the swollen extremities (zoosporangid) sepa-
rated by a partition from the rest of the hyphae? Find zoosporangia
in which the protoplasm seems gathered into many definite masses ;
others empty, with these masses (zoospores) escaped, but still near
by. From what point do the zoospores escape ? Draw an unopened
zoosporangium, and one ruptured, together with a mass of the spores.

370 (Compound). Short-stalked, globular organs (slightly re-
sembling the sporangia of Bread Mold) will probably be found in
abundance in both old and young stages. Are the youngest ones cut
off by a wall? The oldest? What difference in the contents at the
two different stages? You may find gradations from one condition to
the other. The organs are the ob'gonia, and when mature contain a
number of oospores. How many? Have the oospores walls? If so,
are they thicker or thinner than walls (if any) of the zoospores
before noted?

371 (Compound). Look for slender branches with ends applied
to the oogonia, and somewhat swollen at the point of contact. In

OUT. OF EOT. 11

162 LABORATORY STUDIES OF CRYPTOGAMS

some cases these branches (antheridia) may send tubes into the
oogonia. The antheridia may grow from the stalks of the oogonia
themselves, or from the main hyphae close by.

Draw old and young oogonia, with contents, and antheridia (if
found).1

372 (Simple). Peziza. Upon what as a substratum does the spe-
cies of Peziza furnished grow ? If the Peziza is small, use the hand
lens in examination. What is the general shape? Is the external
surface entirely smooth ? Is the color the same on inner and outer
surfaces? Represent all features of form in a drawing considerably
larger than nature, if necessary.

373 (Compound). Cut sections perpendicular to the inner sur-
face. Mount in water. Do you find, with a high power, elongated
sacs containing a definite number of rounded bodies (spores) ? Do
you find many or few such sacs? (If the sections are not very thin,
press the cover glass down cautiously with a needle to spread them out
thinner.) How are they situated relatively to one another and to the
surface of the plant ? They are near which surface, inner or outer ?
How many spores in each sac, or ascus? Draw a diagram of the Peziza
in section, showing the region of the sacs, and indicate some of the
sacs in position. Draw a sac (ascus) highly magnified, with spores,
and the threads that grow up between the sacs.

374 (Compound). Pulling off with forceps bits of the substratum
at the point where the cup of the Peziza was attached, and spreading
these bits out with needles in water on a slide, you may find the
threads of the fungus, which gather nourishment from decayed vege-
table matter. These threads together form the mycelium ; the sau-
cer-shaped or cup-shaped sac-bearing body first examined is the
apotheciunr. That layer of the apothecium in which the sacs are
found is the hymemum. Label drawings according to the terms given.

375 (Simple). Microsphsera.2 With the lens examine the whit-
ened patches of the fungus-infested leaf. Is the whitening external
or internal? To decide this, wet the leaf with a drop of alcohol, and
scrape gently with a knife point. The black, rounded bodies are
perithecia. Indicate by drawing the size of the leaf and of the peri-
thecia. Wet a bit of the fungus with alcohol, and remove with a
knife to water on a slide. If the material has been dried, add strong
potash solution to the preparation. Is the white film composed of
granules or of threads ? Examine the perithecia by transmitted
light. Have they appendages ? Draw a perithecium much magni-

1 In the same mount more than one kind of Water Mold may be
found, the species differing in position and character of oogonia, and in
antheridia and sporangia.

2 Or any genus of the group Erysiphece ; perhaps the commonest form
being Microsphcera alni, the cause of mildew on Lilac leaves.

LABORATORY STUDIES OF CRYPTOGAMS 163

fied. (But if the compound microscope is to be used, delay drawing
until further examination has been made.)

376 (Compound). With a moderate power reexamine the ma-
terial noting the composition of the white coating and the details
of the perithecia. Draw a perithecium, showing one or two appen-
dages with care, and indicating the rest. Press down the cover glass
so as to rupture some of the perithecia. Draw one of the spore-con-
taining organs. In what essential respect, if any, does it differ from
the ascus of Peziza?

377. Toadstool, illustrative of Basidiomycetes. — Draw the habit.
Cut smoothly down through the middle of the umbrella, so as to split
the stem at the junction with the umbrella. Draw the section of the
umbrella and summit of stem as now seen. Label the radial folds
gills (lamellae) ; the part from which they are suspended, the pileus.
Do all the gills extend from the margin of the pileus to the stem or
stipe t Are the inner ends of the gills attached to the stipe? Draw
a diagram of a sector of the umbrella as seen from below, to show
arrangement of gills.

378 (Compound). With a wet razor section a portion of the
umbrella so as to get cross sections of the gills. Carefully wash the
sections from the razor to a slide, cover, and examine with low and
high powers. If small and thin-gilled species are used, sections need
not be made; simply mount a piece of the gill flatwise, when the
spores will be seen, grouped in a particular way, and at the edge of
the piece the manner in which the spores are borne will probably be
seen. How many spores are borne upon the same swollen hypha tip
(basidium)! How are they attached to the basidium? Draw a basid-
ium with spores. Make a diagram of the cross section of a gill,
showing where the spores are borne. Label the layer in which the
basidia are founi hymenium.

With needles dissect small pieces of the stipe and pileus, and
examine with the high power. Of what microscopic elements is the
toadstool made up?

379 (Simple). Lichen. — Examine the lichen with the hand lens.
Is there stem or leaf, or an appearance of a main axis of growth ? Is
there indication of green (chlorophyllous) color? Are there struc-
tures resembling the spore-bearing portion of any fungus heretofore
studied? Draw one of the "fruit" bodies (apothecia) as seen from
above, much magnified. The deeper-colored layer nearly filling the
saucer is the hymenium. Draw the apothecium in outline as seen
from the side.

380 (Compound or Simple). Detach an apothecium, place it in a
piece of pith split to hold it, and section it as thin as possible with a
wet razor. Mount the sections in water, and examine with the lens
or a low power of the microscope. Draw the section of the apothe-

164 LABORATORY STUDIES OF CRYPTOGAMS

cium, with the attached portion of the thallus. Where is the green
color distributed? (Show in drawing.) Distinguish small brown
bodies (spore sacs) standing in large numbers perpendicularly to the
inner surface of the apothecium, and indicate these in the drawing.
The layer in which they occur is the hymenium. If possible, examine
this with a higher power, and draw an ascus (spore sac) with the (how
many?) spores. Also determine further the exact location of the
green color, and draw the green bodies.

381 (Simple). Marchantia: a Liverwort. — Draw the outline of a
single plant, as seen from above, about twice the natural diameter.
Distinguish the growing tip and the base of the plant. Represent
the position and outline of any structures produced from the upper
surface. Is there a midrib? Examine the upper surface with the
hand lens. What do the cup-shaped structures contain? Draw,
much magnified, labeling the receptacle cupule, and the small bodies
within gemmce. Are the gemmae easily detached? Put a drop of water
into one of the cupules and note the behavior of the gemmae? (The
gemmae are best seen on living plants ; in other material they may be
absent.) What are the purpose and nature of the gemmae ? By what
means are they likely to be disseminated?

382 (Simple). Examine the upper surface of the thallus (plant
body) with the lens. Have the minute prominences pores at their
summits? It will be well to use also a low power of the compound
microscope to settle this question definitely. Do the same promi-
nences occur on the under side of the thallus? By what means is the
plant attached to the ground? Draw a little portion of the upper
surface as seen by the hand lens, making the drawing large enough to
show all discernible details clearly.

383 (Simple) . Turn your attention now to certain slender branches
of the thallus, ending in umbrellalike portions. Do you find more
than one kind, as regards the shape of the " umbrella" ? If so, repre-
sent one sort in side view, " stalk " and all. Draw both of the " um-
brellas" as seen from above. The branch ending in free rays is to
be labelled archegonial branch, that ending in a lobed disk, antheridial
branch.

384 (Simple). Select a branch bearing well-matured sporogonia.
Remove the stalk. Lay the head, under side upward, on the dissect-
ing stage, and study the position of the sporangia. How are they
arranged, and to what are they attached? Note the fringed sheaths
that partly inclose them. Detach a sporogonium. Draw it to show
the form, the method of dehiscence (press the sporogonium slightly),
the relative length of the stalk, etc. What does the sporogonium
contain besides spores (use a high power)?

385 (Compound). The antheridial heads may be sectioned with
comparative ease, and the antheridia studied under the teacher's direc-

LABORATORY STUDIES OF CRYPTOGAMS 165

tion. Good preparations of the archegonia, from which the sporogonia
originate, are more difficult to make. If time allows, vertical sections
of the young archegonial heads may-be made by the pupils; or better,
the- archegonia may be drawn from preparations provided by the
teacher. Distinguish the central egg cell, the neck and canal.

386 (Simple). Moss. — Select a single plant, in fruit. Draw the
habit as seen with the hand lens. Examine with the highest power
of the dissecting microscope. Is there distinction of leaf and stem ?
Are the leaves petioled? Have they midribs? With needles clear
away the leaves at the point where the stalk of the spore capsule
(sporogonium) originates. Does this stalk spring from the end of a
shoot of the moss, or is it a branch springing directly from the side of
a shoot? Is there any appearance of a joint or any mark around the
base of the stalk? Are the shoot and stalk separable?

387 (Simple). Look for a capsule which still bears on its summit
a loose cap, the calyptra. Draw the capsule, much enlarged. Remove
the calyptra. Examine the now exposed end of the capsule with a
strong lens. Do you find any appearance of a lid, or cover, by the
removal of which the capsule may be opened ? Draw the outlines of
this part of the capsule, labeling the lid operculum. Slight pressure
may force the latter off. Teeth standing within the edge of the open-
ing may be seen. Note the quantity and appearance of the spores.

388 (Compound). With the compound microscope examine the
protonerna of the moss, if this is provided, and draw a portion. Look
for buds, or beginnings of new leafy shoots.

389 (Simple or Compound). If ready mounted sections of the
flower, so called, are provided, the archegonia and anlheridia may be
studied under the teacher's direction. At least, the shoot tips bearing
these organs should be examined with a lens, and then dissected care-
fully with needles in a little water under the dissecting lens. By
skillfully removing the leaves that form more or less of a rosette
around the desired parts, and by further separation if necessary,
archegonia and antheridia may be distinctly seen, together with the
sterile filaments, or paraphyses, that grow up with them on the end of
the stem.

390 (Simple). Fern. — 1. The prothallium. Place a young prothal-
liutn on the stage of the dissecting microscope, without water. Ex-
amine rapidly with the lens. Are the upper and under surfaces alike?
Is the protliallium of equal thickness throughout? By what means is
the plant attached to the soil ? Add water. If soil particles still ad-
here, remove carefully with a small wet brush or with needles. The
general form reminds you of what cryptogamous plant before studied?
In what respects (refer to former drawings) ? Which is the younger
extremity of the prothallium?

Turn it under side upwards and view by transmitted light. Draw

166 LABORATORY STUDIES OF CRYPTOGAMS

the outline ( x 3-5) ; mark the margin at the bottom of the chief notch
as the growing point. Indicate by shading in the proper place any
thickened portion, and mark this cushion. Show the root hairs, or
rhizoida.

391 (Compound or Simple). Antheridia. Small prothallia should
show the antheridia plainly under the simple lens, especially if the
(living) material is first treated with aqueous iodine for two or three
minutes and then washed. The antheridia are seen as small round,
brown bodies. Indicate their position and relative size on the draw-
ing already made. With the compound microscope the general
structure of these organs can be made out probably without section-
ing, and a drawing may be made.

392 (Compound or Simple). Archegonia. Older prothallia may be
required. Treat with iodine, as before. With a low power the pres-
ence and distribution of the archegonia (appearing as numerous short
columns of cells projecting from the cushion) may be made out. In
many of the older and over-ripe archegonia a central cell, embedded
in the prothallium at the base of the projecting neck, is seen as an
opaque, brownish sphere. Indicate the position and number of the
archegonia on the diagram before drawn.

The details of structure will require higher powers and sections of
the prothallium, either provided already mounted, or made under the
teacher's directions.

393 (Simple). 2. Origin of the spore-bearing plant. From the ma-
terial provided find out from what part of the prothallium the leafy
shoot springs. Is there a root? and if so, does it originate from the
tissue of the prothallium or from the new shoot? Answer these ques-
tions in a drawing ( x 2-4).

394 (Simple). 3. The spores. Examine a "fruiting" leaf of the
mature plant. Are the " fruit spots " (sori, sing, sorus) on the upper
or under side ? Have they a definite location upon the divisions of
the leaf? Indicate the facts in an outline sketch. Pick oft* a leaf
segment and placing it on the dissecting stage under the lens, with
needles carefully raise the covering (indusium) of a sorus. Estimate
the number of spore cases (sporangia) found beneath. Have they
stalks? If you have no high-power instrument, draw, highly magni-
fied, all the details you can discern with the simple microscope.
Much can be made out in this way. Draw (1) the sorus covered by
the indusium (if present), (2) the group of sporangia uncovered.

395 (Compound). If high powers are at hand, further examine
sporangia and spores, after removing from the leaf with a knife point
and mounting in water in the usual way.

396 (Simple). Selaginella. — With hand lens examine the arrange-
ment and shapes of the leaves, and draw a short section of the shoot
( x 3-4) to show these points. Do the shoots of Selaginella grow

LABORATORY STUDIES OF CRYPTOGAMS 167

upright or more or less prostrate? Has the leaf arrangement any
relation to the habit of growth ? Look for special leafless, root-bearing
branches.

397 (Simple). Do you find the tips of some of the shoots modi-
fied (fruiting spikes) ? The leaves of these spikes differ in what ways
from those of the rest of the plant? In their axils are the rounded
sporangia. On the stage of the dissecting microscope, in a few drops
of water, dissect a fruiting spike with needles. Pull off some of the
leaves. Do the sporangia come away with them ? Make a drawing
to show the facts. Let the drawing be large enough to show the form
of the sporangium clearly.

398 (Simple or Compound). Crush some of the sporangia; what
do they contain ? If possible, see these very numerous bodies (spores)
with a good power of the compound microscope. Do they resemble
anything you have seen in flowering plants ?

399 (Simple). Look over the fruiting spikes for sporangia con-
siderably larger than those already seen. Determine from a number
of cases whether they occur with the lower or the upper leaves of the
spike ; on one side of the spike only, or on all sides. Draw one of
these sporangia (how many protuberances) ? Open it ; how many
bodies (spores) contained?

Having now seen the two sorts of sporangia, label the one produc-
ing small spores, microsporangium ; the other, macrosporangium.
Indicate roughly the relative size of small spores (microspores) and
large spores (macrospores) in drawing.

400 (Simple). Club Moss, Lycopodium. — Sketch the general habit,
to show the attitude of the main and branch stems. Are there dis-
tinct fruiting spikes in the species studied? If so, are they raised on
stalks, or not? Show these points in the habit drawing. Compare
herbarium specimens of a few different species with regard to the
same features. Does the material furnished show any roots? If so,
show them in the habit drawing. Are the leaves petioled ? Are they
evenly distributed around the stem?

401 (Simple). Dissect under the lens a fruiting spike. Do you
find sporangia? How many to each leaf ? Draw one of the leaves to
show the facts. On which surface of the leaves are the sporangia
borne, upper or under? Press one of the sporangia; what does it
contain? Look at the bodies emitted with the compound instrument.
Have they any resemblance to any bodies produced by Phanerogams ?
Do you find more than one size of sporangium and of the spores?
Would the number of spores in any sporangium be represented in
10's, in 100's, or in 1000's?

402 (Simple). Horsetail, Equisetum. — Find the leaves. If the main
axis bears offshoots of any sort, determine whether these are leaves, or
stems, or both. Make a drawing to show the facts, and another of

168 CRYPTOGAMS

the cone terminating the fertile shoot. Dissect the cone under the
lens. Note the peculiarly modified leaves : how many saclike folds
has each? Is the number constant? What is the nature of these
"folds " as determined by the contents ? Draw a diagrammatic longi-
tudinal section of one of the cone leaves, much enlarged.

403 (Compound). With the compound microscope examine the
contents of the sacs. Draw. Allow some of the spores to dry on a slide,
and then, while viewing them through the microscope with a low
power, breathe out gently so that the moisture from the breath will
strike the spores. Describe the action seen, illustrating by diagrams.

XVI. CRYPTOGAMS

404. The plants to be described in the present chapter
are a few chosen from a very great number of forms,
making up a series which differs in many important re-
spects from the group of Phanerogams. Cryptogams on
the whole are smaller than Phanerogams. It is true that
the Ferns (cryptogamous plants) are a conspicuous element
of land vegetation almost everywhere, and in the warmer
regions attain to the stature of trees ; and that Seaweeds,
some of them of great size, hold exclusive possession of
the littoral rocks and the borders of the ocean bed. But
the great majority of cryptogamic forms are too small to
attract attention, and many are even too minute to be seen
by the naked eye. Although many of the Cryptogams,
both great and small, have a very varied life history and a
structure that is by no means very easy to understand, yet
as a group the Cryptogams are structurally simpler than
the Phanerogams.

405. Viewing all cryptogamic plants together, we find
that they fall into a kind of series, which, if followed in
one direction, leads toward the general type of organization
found in Flowering Plants ; or, in the other direction, leads
toward the simplest microscopic forms. The series is,
however, a very imperfect one, broken by many gaps.
Next to the Phanerogams stand Selaginella (Fig. 353),
Lycopodium (Fig. 357), and similar plants, with stem,
leaf, root, and even structures answering to rudimentary
flowers. A little further removed come the true Ferns

CRYPTOGAMS 169

(Fig. 345). Still less like Flowering Plants, but closely
allied to the Ferns, stand the Mosses and Liverworts
(Figs. 340, 334). In the groups named — found at what
we speak of as the upper end of the cryptogamic series —
the stem-and-leaf type of structure prevails. In the lower
groups a contrast in this respect will be noted.

406. Going below the Liverworts — i.e. away from the
Phanerogams — we come to the Algae (Seaweeds and the
like, Figs. 291, 298), between which and the Liverworts
the similarity is not marked. The Algse include all green
(chlorophyllous) plants below the Liverworts, down to the
smallest and simplest (Fig. 282). Along with them, and
often resembling them in many respects, are the Fungi, of
which ordinary molds and toadstools are examples. Fungi
lack chlorophyll.

407. In the Algse and Fungi the plant body is not
distinguished as in Flowering Plants and higher Crypto-
gams into axis or stem, and leaves. It is a simpler
structure, and is termed a thallus. In the simplest
Cryptogams the thallus is the single cell constituting
the individual ; in higher forms it becomes a filament,
membrane, or solid mass. Algse and Fungi together are
termed Thallophytes.

408. The Algse fall into four grand divisions, conven-
iently distinguished in most cases by the color. In the
lowest group the green due to chlorophyll is more or less
modified by the presence of a blue pigment ; in the second
group the chlorophyll gives its true hue; in the third,
green is masked by brown ; and in the fourth, a red pig-
ment is usually present to obscure the green more or less
effectually. The description of typical Cryptogams will
begin with the simplest Algae.

Throughout the present chapter merely the structures
and processes most commonly found in the groups selected
will be described. Let it be understood that a full
account of even the few forms brought forward would
involve many qualifying additions to the general state-
ments now made.

170 CRYPTOGAMS

BLUE-GREEN ALGJE

409. On wet walls of stone and on undisturbed moist
earth may often be found small, rounded, jellylike masses
of a greenish or bluish color. A bit placed under the
microscope shows a great number of chains of rounded

cells (Fig. 282), embedded in the
gelatinous matter. Certain cells
of each chain are somewhat
larger and lighter colored than
the rest. When a chain breaks
282. A chain of Nostoc cells: in pieces, as occasionally happens,

h, heterocyst; d, recent , . ,, . , ,

divisions. separation usually takes place

next to one of these enlarged

cells, or heterocysts. The fragments finally develop into
chains of the original character. The cells increase in
number by transverse division (Fig. 282, d). Cell divi-
sion is, in fact, the ordinary process by which the plants
of this group multiply.

410. If the substratum on which the plants are grow-
ing dries up, the investing mass of gelatinous substance
hardens in proportion as it parts with water, and so be-
comes a protective coating which enables the plant to
withstand extreme drought.

411. The plant here described and figured (Nostoc) is
representative of the Blue-green Algae in color, in the
filamentous arrangement of the cells, in the method of
multiplication by transverse fission, and in throwing off
mucilaginous matter from the Avails to form sheaths and
embedding masses. In some species, however, the cells
are found in small groups, not filamentous ; and in others
the gelatinous coating is either very thin or entirely
wanting.

412. Oscillatoria (Fig. 283) is, like many of the group, often
aquatic, either floating freely or gathered in small tufts. The filaments
have a characteristic motion of bending slowly from side to side —
whence the name Oscillatoria. They also possess some means of
locomotion, by which they slip along over the substratum, while at the
same time slowly revolving upon the longer axes of the filaments.

CRYPTOGAMS

171

New filaments arise from short portions (hormogonia} with rounded
ends (Fig. 283, h), when these portions have been set free from the old
filaments.

283. Oscillatoria : a, part of a filament showing hormogonia (A, A) ; c,
filaments, less magnified.

413. The Blue-green Algse comprise a large number of species,
many of which differ considerably in general habit from the forms
just described.

GREEN ALGJE

414. The Green Algse (so called from their pure
chlorophyll green color) are mainly small aquatic plants,
and chiefly inhabit fresh waters ; though some of them
are sub-aerial. The smallest members are distinguishable
only with the microscope ; the largest form growths
several inches in diameter.1 The exceedingly numerous
species vary widely in structure and mode of life. The
few here described will give some idea of the chief types.
It should be understood at the outset that only the most
important facts of life history are given ; and that in
many of the forms modes of reproduction, not here de-
scribed, exist.

415. Pleurococcus. — Almost all surfaces that are occa-
sionally wet and are not too much exposed to heat and
drying — as shaded sides of tree trunks, rough posts, and
rocks — after a time become

green by the growth of mi-
nute unicellular plants of vari-
ous kinds. They thrive and
multiply in rain, and dew, and
resist ordinary drying. One
of the commonest of these unicellular forms is Pleuro-
coccus (Fig. 284). The plant is simply a microscopic

284. Pleurococcus.

1 For example, the familiar Sea Lettuce of the seashore.

17!

-Jtx

Or THE

UNIVERSITY

OF

CRYPTOGAMS

sphere. Its only known mode of reproduction is by
division. That is, each individual divides by a cross
wall, and the two new individuals so produced increase in
size. Before they separate they may each again divide ;
and in fact the plants are commonly found cohering in
small colonies (Fig. 284, B).

416. Ulothrix. — The fine unbranched filaments of Ulo-
thrix are abundant in fresh water, where they grow
attached to stones, sticks, etc. (Fig. 285, a). The fila-
ments increase in length by the division and elongation of
any or all of the cells. When Ulothrix is about to repro-
duce, its cells divide internally, so that within
each one are produced several cells ; but the
latter have no cell wall formed about them.
When these naked cells escape, by the rupture
of the mother cell wall, it is seen that they are

285. Ulothrix: a, a young filament; b, larger zoospore; c, escape of these
spores ; d, e, escape and conjugation of smaller zoospores. — DODEL-POBT.

provided with hairlike organs called cilia, by means of
which they swim energetically about (Fig. 285, 6, d).
The motile cells (called, from their animal-like power
of locomotion, zoospores) are of two kinds, large and
small. The larger have four cilia (Fig. 285, 6). After
a short active period they settle down, lose their cilia,
invest themselves with cell walls, and germinate by
growing out into new filaments. The smaller zoospores
are provided with but two cilia. After swarming they
fuse (Fig. 285, e), generally in pairs. This process,
wherein two cells unite to form the germ of a new plant,
is called conjugation. The body formed by the conjuga-
tion of two similar cells is a zygospore. In the case of

CRYPTOGAMS 173

Ulothrix the zygospore forms a wall about itself, rests for
a time, then makes some growth by elongating and
enlarging, and finally its contents break up into several
zoospores which are like the larger ones described above
and develop in a similar fashion.

417. Spirogyra. — Spirogyra may be found floating in
unattached masses at the surface of almost any sunny
pool or spring in warm weather. It is often known as
Frog slime or Frog spittle. Under the microscope a bit
of the mass becomes a tangle of beautiful green filaments,

286. Spirogyra: n, nucleus; s, chromatophores.

unbranched, and consisting of elongated cylindrical cells
(Fig. 286) placed end to end. In the cells of Spirogyra
the essential parts of the typical vegetable cell are well
seen.1 The wall is lined with a thin, layer of living
matter (protoplasm*), embedded in which are several
spiral bands of denser composition, the chromatophores, or
color-bearing organs (s), containing the chlorophyll.
Near the center of the cell is found the rounded nucleus
(n), from which strands of protoplasm run to the peripheral
layer. The remaining space is filled with cell sap —
water with dissolved substances.

418. The cells of the filament live in apparent inde-
pendence of one another, each forming its own food
supplies, and every one capable of dividing transversely
to form two daughter cells ; by which process the plant
increases rapidly under favorable conditions.

1 Refer here to §§ 494-498 ; a full discussion of the cell should "be hail
at this point. Emphasize the relative unimportance of the wall ; the
idea of the living unit having the nucleus as the center and conservator of
vital activity ; the r61e of the nucleus in cell division (briefly); arid the
occurrence of many cells (represented by nuclei) in a common wall, as in
Vaucheria next to be described.

174

CRYPTOGAMS

419. Growth and reproduction should now be clearly
distinguished. Growth is the increase in size of an
already existing individual ; reproduction is the forma-
tion of a new individual, or new individuals. In the
case of Pleurococcus cell division results in the produc-
tion of two new individuals, which separate sooner or
later. In the growing root tip of a Flowering Plant,
on the other hand, cell division is merely a step in the
formation of more root, and is therefore only a growth
process. In the case of Spirogyra, if we consider the
whole filament to be the individual, then division of the
several cells is to be regarded as growth. But if the cells
of the filaments are considered to be the individuals, i.e.
essentially independent organisms, their division must
then be regarded as reproduction. The two processes here
run together, since it is not easy to say how much of the
plant may be termed the individual.

420. Reproduction. — Under certain
conditions, however, the cells of Spi-
rogyra take part in a distinctly repro-
ductive process. The cells of a filament
send out lateral processes which meet
similar processes from cells of another
filament (Fig. 287). Cells thus become
united in pairs. Openings are then
made in the conjoined outgrowths, by
which the contents of all the cells on
one side pass over into those on the
other. The contents of each pair of
— =-j I cells unite to make up a single body,

287. Conjugation of Or zygospore (zs), which becomes invested

Spirogyra : zs. -,,-,• i , •

zygospore; f, uj a thick wall preparatory to a resting

fusion in pro- period. In this form the plant endures

periods of drought, when the pools

where it grows dry up; and thus it also passes the winter.

421. Here, as in Ulothrix, two similar cells unite in

reproduction. In plants soon to be described the fusing

cells differ largely in size and other characteristics.

CRYPTOGAMS

175

288. Desmids.

422. Conjugation of similar unciliated reproductive
cells is characteristic of a considerable group of Green
Algse. Fresh water preparations very often contain
unicellular forms belonging to this group, more

or less resembling the species represented in Fig.

288. Sometimes they cohere in chains. Usually
they are capable of slow locomotion. They are
Desmids.

423. Vaucheria. — The green filaments
of Vaucheria are large enough to be dis-
tinguished by the naked eye. By repeated
branching they form upon moist soil
matted growths which may be several
inches in diameter. The plant also grows

submerged in water. The filaments are continuous tubes,
ordinarily without cross partitions (i.e. unseptate'), and
are, lined with a protoplasmic layer in which numerous
nuclei and small rounded chromatophores are held; the
main cavity of the tubes being filled with cell sap as in
the case of Spirogyra cells. In fact the thallus of Vau-
cheria is to a certain degree such as would be produced
if the cells of Spirogyra were not separated by end walls,
the chief differences in this respect being
the greater number of nuclei, the shape
of the chlorophyll bodies, and the
branching habit of Vaucheria.

424. Reproduction. — Zoo spores are
produced in the ends of side branches
after these portions have been cut off
by septa and thus converted into zoospo-
ranqia. The whole contents of each

289. Zoospore and

zoosporangium zoosporangium escapes by the rupture

of the wal1 at the aPex CFig-' 289)> and
constitutes a single large zoospore pro-
vided with numerous pairs of cilia distributed over its
surface. The motile period may last for several hours,
after which time the cilia are lost, a wall is formed around
the zoospore, and germination very soon takes place by

176

CRYPTOGAMS

the protrusion of one or two tubular filaments, which

grow directly to new plants.

425. Zoospores are apt to be formed when the plant is

growing in a submerged situation. In places where it is

exposed to the air and moistened only occasionally, as by
the dew, a second method of repro-
duction prevails. Swellings arise
on the thallus, which develop into
short, thick branches of peculiar
form. When cut off by septa
below they become the oogonia
(Fig. 290, og). The contents of
the oogonium contracts somewhat
to form the egg cell, and an open-
ing makes its appearance in the
oogonium wall. Near by, short,
slender, often coiled branches grow
up. Their extremities are cut off

Vaucheria : A, the un-
opened antheridium
(a) and oogonium
(og) ; B, the same
after fertilization
and formation of to form the anthendia (rig. 290, #),

from which antherozoids, bodies
small

the oospore (os) . —
PBINGSHEIM.

resembling small zoospores, are
finally liberated. The latter make their way through
water to the opening of the oogonium, and one, enter-
ing, fuses with the egg cell. The resulting body, or
oospore, now surrounds itself with a cell wall and enters
a resting state. It is ultimately set free by the rupture
of the oogonium wall, and germinates.

426. In Vaucheria we have essentially the same reproductive pro-
cesses as in Ulothrix, but now appearing in a much modified form.
The single large zoospore of Vaucheria, with its many cilia, performs
the same office as the numerous small zoospores of Ulothrix. The pro-
duction of the oospore in Vaucheria may be likened to the union of
reproductive cells in Ulothrix, with the important difference that now
the fusing cells differ greatly in size, and only one of them is motile.

427. Cells designed for reproductive union are called gametes.
When they are of unequal size, the larger is termed egg cell or simply
egg ; the smaller, if motile, is an antherozold. The egg is said to be
fertilized by the antherozoid. The body directly resulting from the
\mion of unequal gametes is an oospore.

CRYPTOGAMS

177

BROWN ALGJE

428. The Brown Algge (Fig. 291) are almost exclusively-
salt-water plants. They are in most cases attached. In size
they range from microscopic, unicellular forms, through
the fine filamentous species (Fig. 291, D), to thalloid
forms of immense length. " Of these, Macrocystis pyrifera

291. Brown Algae: A, the Sea Colander (much reduced) ; B, Larainaria (much
reduced) ; C, the Gulf Weed with floats (a) ; D, Ectocarpus (magni-
fied), s being sporangia.

is noted for its gigantic size : rising obliquely upward to
the surface of the water from the sloping sides of eleva-
tions in the ocean bed, its floating thallus has a length of
600 to 900 feet. The stalk below is naked, but at the
surface, where it streams out horizontally, it bears many
long pendent segments, each provided at the base with a

OUT. OF EOT. 12

178 CRYPTOGAMS

large bladderlike float filled with air." 1 The Gulf Weed
(Fig. 291, C), which collects in such quantities in the so-
called Sargasso seas, belongs to this group. On certain
coasts it grows as an attached plant. Portions which have
been detached and carried off by currents continue to grow
and multiply vegetatively as they float in the quieter areas
of the ocean.

429. The brownish color of the Brown Algse is due to
a pigment in the cells, which probably aids the chlorophyll
present in the work of assimilation.

430. Reproduction. — Reproductive cells are of several
sorts in this group. First and simplest are the zoospores
borne in Zoosporangia (Fig. 292, A), found in most

members of this
g^P- Their Ms-
tory is like that
of the larger zoo-
spores of Ulo-
thrix ; that is,
they germinate

292. A, zodsporangium, and B, gametangium, of directly after

Ectocarpacese ; C, gametes (g) and their con- swarming1, witll-
iugation (s) . — PRINGSHEIM.

out fusion.

431. Secondly. We find processes of cell fusion, not
unlike those already seen in the reproductive bodies
of Green Algae. We may select three representative
cases. (1) In Ectocarpus and allied plants, zoospores
(gametes) are produced, which are indistinguishable from
the zoospores intended for direct germination, except that
the bodies now in mind arise in sporangia of a different
character (Fig. 292, B). They may conjugate in pairs (C),
like the small zoospores of Ulothrix. (2) In some forms
(Cutleria), the fusing zoospores (gametes) differ in size.
The larger come to rest before fusion. This is a step
intermediate between the condition in Ectocarpus and that
next to be described. (3) In the common Rock weed of
the shores, the gametes are egg cells and antherozoids

1 Strasburger, "Text Book of Botany," p. 330.

CRYPTOGAMS

179

(Fig. 297). The egg cells are produced in od'gonia
(Fig. 295), found in cavities or conceptacles (Fig. 294),
which make their appearance at cer-
tain seasons in special portions of the
branching thallus (Fig. 293). The
antherozoids originate in antheridia

293. A Branch of Rock-
weed : /, a fertile
portion.

— THURET.

294. Section of a conceptacle. — THURET.

(Fig. 296), enlarged cells produced
on branching filaments. The anther-

idial filaments grow from the walls of conceptacles, either
with the oogonia, or in other conceptacles upon separate
plants, according to the species of
Rockweed considered. At maturity
both egg cells and antherozoids escape
from the concepta-
cles and float about.
The antherozoids
swarm about the
naked egg cell ener-
getically (Fig. 297),
and one of them

^fi^W^lliFN ^na^y penetrates and
fuses with it. At
An oogouium. — once a wall begins

THURET. tQ form about t]ie fertilized egg, or

oospore, which now settles to the bottom, and upon ger-
mination gives rise to a new plant.

296.

295.

An autheridial
branch ; a, au-
theridia.

— THURET.

180

CRYPTOGAMS

432. From the series given
above (Ectocarpus, Cutleria,
Rockweed) it is apparent
that the antherozoids in
Rockweed are in the nature
of reduced zoospores ; while,
the egg cell also answers to
a zoospore, only in this case
the cell is of increased size,
and being from the first;

297. Antherozoids swarming about deV°id °f cilia> is entirely
the egg cell. — THUBBT. passive.

RED ALGJE

433. The Red Algse (Fig. 298) are, with few excep-
tions, marine. 1 While many forms may be found in very
shallow water, many are found in deep water where,
owing to the feeble light, no other algse can exist. In

298. Red Algae: A, Delesseria sinuosa;
B, the so-called Irish Moss ; C, 2.
fresh- water species, Batrachosper-
mum ccsrulescens ; D, two fila-
ments of the last, showing the
cells.

some of the smallest and simplest species the thallus con-
sists of loose branched filaments (Fig. 298, D); in others,
as in the Irish Moss (Fig. 298, B), the flattened thallus is
divided into narrow segments ; while in many others, the

1 Of fresh-water species. Batrachospermum, Fig. 298, C, is very common
on stones in brooks.

CRYPTOGAMS

181

plant body is very thin and much expanded, and reaches a
length of several feet. In most cases the plants are
attached by more or less rootlike holdfasts. The often
beautiful color is due to the presence of a red pigment,
which more or less completely masks the chlorophyll.

434. Reproduction. — A characteristic method of bearing
spores is in groups of four (Fig. 299), each group result-
ing from the division of the contents of

an original mother cell. Such spores are
termed tetraspores. They are bright red
bodies without cell walls, and being un-
provided with cilia, are dependent upon
water currents for dissemination.

435. Reproduction, with fusion of the
reproductive cells, may be illustrated by
the case of Nemalion ; this being taken
as a simple instance of a process which

e in some members of

the group becomes
highly complicated.
The reproductive cells of Nemalion are
pollinoids, naked spherical cells pro-
duced singly in rounded antheridia
(Fig. 300, a), and
differing from an-
therozoids only in
being unciliated ;
and egg cells formed
within elongated
cells termed carpo-
gonia (Fig. 300, <?).
The egg occupies
the enlarged basal
portion of the car-
pogonium, the hair-
like extremity of
Several pollinoids,

299. Tetraspores («)
in a filament
of Polysipho-
nia.

B O

300. Nemalion: A, showing the earpogonium (c),
trichogyne (t) with pollinoids near, and
antheridia (a) ; B, after fertilization, the
carpogonium beginning to hranch ; G, the
nearly mature spore-bearing body (cysto-
carp, c?/). — THUBET.

which is known as the trichogyne (f).

brought by circulation of the water, may adhere to the

182 CRYPTOGAMS

trichogyne ; they surround themselves by membranes, and
the contents of one of them passes through the trichogyne
wall and makes its way to the egg cell. After fertilization
the fertilized egg (oospore), remaining in position, divides
and, on all sides, sends out branches (Fig. 300, c), from
which separable cells, called carpospores, are finally formed.
These spores serve the same purpose as the tetraspores,
growing directly to new plants.

436. It is to be noted that while in Vaucheria and Rockweed the
oospore is set free from the parent plant before germination and
grows directly to a new plant, in Nemalion the corresponding body
(fused egg cell and pollinoid) is not liberated from the carpogonium,
but, as we may say, germinates in position. The free spores are pro-
duced only after an interval of growth.

437. We summarize reproduction in the types of Green, Brown,
and Red Algse as they have here been described, as follows : —

(1) Reproductive cells give rise to new plants without conjugating.
A single cell, set free from the parent, germinates without having to
fuse with another cell. This single cell is a spore : in Ulothrix and
Brown Algse, a zoospore; in Red Algae, a tetraspore or a carpo-
spore.

(2) Reproductive cells conjugate before giving rise to new plants.
Two cells unite to make up a body which is the starting point of
a new plant. The uniting cells are gametes. Gametes may be :
(a) zobspores (zoogametes), indistinguishable in some cases from the
zoospores which germinate without conjugating; (b) pairs of similar
unciliated cells (Spirogyra); (c) egg cells and antherozoids or polli-
noids (Vaucheria, Rockweed, Nemalion). The egg cell may be
fertilized in position (Vaucheria, Nemalion), or after liberation (Rock-
weed). The immediate result of conjugation is a zygospore when the
uniting cells are alike ; an oospore, when they are unlike. The oospore
may be freed from the oogonium before it germinates (Vaucheria,
Rockweed), in which case the reproduction is described as oosporic ;
or may develop in position (Nemalion), carpospores being the indirect
result, in which case the reproduction is said to be carposporic. In
Vaucheria and Rockweed the germination of the oospore gives a new
plant; we may properly, therefore, think of the structure resulting
from the fertilization of the egg in Nemalion (namely, the branches
of the carpogonium and the carpospores while forming) as a new
plant parasitic upon the parent.

(3) Reproduction without conjugation serves for rapid propagation ;
and at the same time for dispersion, since the spores are often motile,
and when unciliated float easily in the water.

CRYPTOGAMS 183

(4) Reproduction with conjugation,1 in the Algae and other low
plants, is often associated with exposure of the plant to adverse con-
ditions, such as the approach of winter or drought or the old age of
the plant. It seems to be a mode of reinvigorating the species at the
moment when the production of a new plant is to be provided for.
It is clearly of the same nature as the fertilization of the egg cell in
the ovule of the Flowering Plants.

Reproduction with conjugation (sexual reproduction) in the Thallo-
phytes is of three types, as indicated above; viz., 1) zygosporic,
2) oosporic, 3) carposporic. An important system of classification of
both Algae and Fungi (in which essentially the same reproductive pro-
cesses occur as in Algae) is founded upon these types.

FUNGI

438. Fungi may conveniently be defined as Thallo-
phytes lacking chlorophyll. In structure and life habit
many of them closely resemble certain Algae. In some
instances the resemblance is so striking that we may with
assurance regard the fungal forms, in these cases, as having
been derived from Algse, chlorophyll having been lost
through the adoption of a parasitic or saprophytic mode
of life. Parallel cases in Flowering Plants are furnished
by the Dodder (a parasite, Fig. 32) and the Indian Pipe
(a saprophyte, § 59).

439. Many of the species are unicellular and very
minute. When of more than one cell, the plant body is
generally filamentous. Even in the compact, fleshy forms,
like the Toadstools, the solid structures are built up of
an immense number of essentially independent threads.
The vegetative filaments of Fungi are termed hyphce ;
and the plant body composed of hyphse (aside from special
spore-bearing parts) is the mycelium.

440. The number of species of Fungi is very great,
and the types are extremely various. A few common
forms will be described in order, thereby, to present sev-
eral of the most important groups.

lrThe last two methods of reproduction are also termed the asexual
and the sexual modes, respectively.

184

CRYPTOGAMS

Bacteria

441. The Bacteria (Fig. 301) include the smallest of
all living organisms. Even the highest powers of the
microscope fail to show much of their inner structure ;
so that at present very little is known of their relation-
ship to other groups. Our knowledge is confined to their
external forms, methods of multiplication, and modes of
life, with their effects, good and bad ; but this knowledge
is of the highest practical importance, since the Bacteria
affect the lives of other living beings, including man, in
very direct ways.

442. Size. A common spherical form is ^oyuoT ^nc^ ^n
diameter ; the rod-shaped germ of consumption is from
three to nine times as long as this ; many species, however,

are considerably larger. Form. The
principal forms are (1) spherical,
(2) straight cylindrical, (3) spiral.
Movements. Many Bacteria exhibit
very lively movements. Locomotion
is usually accomplished by means of
extremely fine cilia (Fig. 301). Mul-
tiplication commonly takes place by
fission. Each individual divides into
two parts, by transverse division,
each part becoming a new individual.
Under favorable conditions — abun-
dance of food and considerable

cilia; b, a spiral
ciliated form ; c, a

301. Bacteria, highly mag-
nified : a, the germ
of typhoid fever,

stained to show the warmth — the Bacteria may double
in numbers about every half hour,
rod-shaped form, in In this way enormous multitudes may

chains; d. a spheri- -i, <• • • i • i-

cai form. — a, &, result even from one original mdi-

from ENGLER and vidual in a comparatively short time.

Low temperatures retard growth and

division : hence the utility of ice in preserving foods in
warm weather. Under certain conditions Bacteria pass
into a spore condition, in which they become highly
resistant to destruction by heat or drying. In a dry

CRYPTOGAMS 185

state the spores of some species may live for years. They
are not necessarily killed by boiling. Only repeated or
greatly prolonged boiling will sterilize liquids, i.e. free
them from all Bacteria ; though a single boiling will kill
all active Bacteria present. Prevalence. Bacteria are
present in considerable numbers in ordinary air and in
most fresh waters. They are very abundant in most
soils. They abound in many milk supplies and are present
in butter, cheese, and other foods. Subsistence. Bacteria
are (1) saprophytic and (2) parasitic. The parasitic
species may cause deadly diseases in animals (including
man).

443. Effects. Bacteria bring about chemical changes
in the substances in which they live. Such changes are :
the decay of the dead bodies of animals and plants ; the
fermentation (souring) of milk; the "ripening" of cream
and of cheese ; and the conversion of the alcohol in cider
into the acid of vinegar. In the manufacture of butter,
cheese, and vinegar, therefore, Bacteria play an important
part. Other instances of their usefulness in the arts
might be given.

Among diseases known to be due to Bacteria are influ-
enza, erysipelas, scarlet fever, typhoid fever, consumption,
leprosy, lockjaw, and cholera. The principal source of
harm is the production of virulent poisons in the blood.
In spite, however, of the dangerous character of the para-
sitic species, the Bacteria are on the whole a highly bene-
ficial group of organisms. The dissolution of dead organic
bodies, and the enrichment and preparation of soils for
the uses of higher plants, effected by Bacteria, are very
important services.

Yeasts

444. If one examines microscopically a small portion of
yeast cake sold for raising bread, he finds (along with
starch grains from the potato used in making the cake)
numbers of small, colorless, unicellular plants, broadly
elliptical or somewhat ovate in outline, and of various

186 CRYPTOGAMS

sizes (Fig. 302). Though very small plants, the Yeasts
are larger than most Bacteria, averaging perhaps ^lyFo
inch in length. Each cell consists of
wall and protoplasmic body, generally
including refractive granules and a
large sap cavity.

Reproduction. — New individuals are
formed riot by division into two equal
"Y parts, as in the Bacteria, but by a pro-
302. Yeast plants: i cess of "budding." The cell wall is
and 2 repre- pushed out at some point in a small

sent successive -, j in. -,• -,

stages in the rounded swelling, which receives pro-
process of bud- toplasmic contents from the parent cell.
It increases in size and is finally cut oft'
by a new cell wall ; though it may long remain attached
to the parent cell. Before its separation it may itself bud
in one or more directions, and thus irregular colonial
growths arise. Yeasts may multiply very rapidly, an
entire new generation appearing in a couple of hours.

There are many different sorts of Yeast. The usefulness
of all Yeasts, however, depends upon their power of
decomposing certain sugars, with the resultant formation
of alcohol and carbonic acid gas (that is, their power of
exciting alcoholic fermentation). In beer and wine
making, alcohol is the product sought ; in bread raising,
on the contrary, carbonic acid gas is the useful product,
its bubbles giving the bread its lightness.

Bread Mold (Rhizopus)

445. If fresh moist bread is placed in a tightly closed
dish in a warm place, within a few days a thick growth
of fine white mold will probably make its appearance,
unless special precautions have been taken to prevent such
a result. That the plant may be secured without failure
by such means of course demonstrates the prevalence of
its minute spores in the air, or in the dust which has
settled on the bread or on the dishes used. If we were to

CRYPTOGAMS

187

follow a spore to its destination and observe its develop-
ment, we should find that after soaking up some of the
juices of the bread it germinates by putting out a trans-
parent hypha (Fig. 306). The hypha grows by further
absorption of food matter, increases rapidly in length,

303. Bread Mold : S, a sporangium ; r, rootlike organs.

branches repeatedly, and thus ultimately develops into a
complex mycelium running over the bread and sending
hyphse into the interior. All portions of this mycelium
may be in communication internally, for there are no
cross walls, or septa. In this respect Rhizopus is like
Vaucheria.

446. Reproduction. — Special erect filaments are soon
sent up, at the summits of which white globular sporangia

A B c

304. A, young sporangium ; B, section of a mature
sporangium ; C, sporangium after rupture of
the exterior membrane (w).

305. A spore of Bread
Mold, more high-
ly magnified.

are formed (Figs. 303, 304). At maturity both turn
black. The numerous spores are ovate bodies (Fig.
305), covered with cell walls which protect them from

188

CRYPTOGAMS

the chief danger which besets all very small organisms
exposed in the air, namely, drying. Where the Fungus
spreads away from the bread along the bottom of the
dish, it is seen that the sporangial stalks arise in groups
at points where the hyphse touch the dish, at which
points also rootlike organs appear (whence the name
Rhizopus, root footed). The whole has very much the
habit of a Strawberry plant propagating by runners
(Fig. 303).

A B

306. Germination of 307. Conjugation of Rhizopus : A, B, C, D, suc-

the spore. cessive stages in the production of the

zygospore.

447. Under certain conditions short lateral branches
spring out near one another from neighboring hyphse and
grow until their tips are in contact (Fig. 307). The
end parts of the branches become cut off by septa. They
are the gametes, which fuse after the walls have been
absorbed at the point of contact. The result is the
formation of a thick-walled resting spore, or zygospore
(Fig. 307, z).

Water Molds (Saprolegniaceae)

448. The best way to secure material for the study of
these plants is to bring in a large handful of decaying
leaves from some pond hole or bog where water stands,
throw them into a jar of water, and after them throw in
either dead insects or succulent shoots of seedlings killed
by heat. Upon these food materials the spores of the
Water Molds from the dead leaves will fasten and ger-

CRYPTOGAMS

189

minate. The short floating filaments, often much stouter
than those of the Bread Mold, may be distinguished by
the naked eye. Under the microscope they are seen to
compose an unseptate branching mycelium, which pene-
trates the object upon which it grows.

449. Reproduction. — The more or less swollen ends of
some branches are seen to be filled with dense protoplasm
and to be cut off by

septa to form the
zoosporangia (Fig.
308, A). The con-
tents finally breaks
up into numerous
rounded bodies which
finally escape from a
terminal opening in
the zoosporangium.
These bodies, the zoo-
spores, in some spe-
cies are motile from
the time they are set
free ; in other species
just after ejection
they surround them-
selves by a delicate
cell wall, from which
they soon escape and
swim away, soon to
germinate.

450. Resting oo-
spores are formed
from egg cells, pro-
duced in spherical
oogonia (Fig. 308,
D), fertilized from

antheridial tubes (Fig. 309), which penetrate the oogonial
wall in order to reach the egg cells. After fertilization
the Qpspore surrounds itself with a thick wall.

. Water Mold: A, zoosporangium; B, es-
caped zoospores, before becoming motile ;
C, zoospores in the active stage; D,
oogonia and antheridia (a) . The lower
oogonium contains an unfertilized egg
cell (e), and two young oospores (o) ; the
upper shows four mature oospores (sp) .

190

CRYPTOGAMS

310. Germination of
the oo'spore :
a, zoo'sporau-
gium ; s, zoo-
spores.
-DE BARY.

451. This process differs from oospore formation in
Vaucheria chiefly in the usual presence of several egg

cells in each oogonium, and in the con-
duction of the fertilizing cells (or nuclei)
to the egg cells by means of tubes. In
Vaucheria, it will be remembered, the
fertilizing cells are an-
therozoids. Frequently

309. Fertilization of . «,. , ,, ,-, ,,

Water Mold: m Water Molds there

a, antheridial is this further peculiar-
ity, that without fertili-
zation egg cells become oospores capable
of germination.

452. It is from resting oospores in the
dead leaves that the plant is obtained
for study, as recommended above. The

oospores on germinating shortly give rise to zoospores
(Fig. 310), and these infect the dead flies, etc., thrown
into the water.

Sac Fungi (Ascomycetes)

453. The *name Sac Fungi or Ascomycetes (ascus,
sac, and mycetes, fungi) is given from the fact that
spores are borne in more or less oval, club-shaped, or
elongated sacs at the ends of hyphse (Fig. 313). The
sacs may be present in large numbers and are generally
grouped in special structures, or "fructifications," built
up from the mycelium around the sac-bearing hyphae.
The following common forms will serve to familiarize the
student with prevailing types of fructification, for it is
by the forms of these structures that the different Sac
Fungi are chiefly distinguished.

454. Peziza. — Common species of Peziza are most readily
found growing on rotting logs and sticks, though many
spring from the soil. Tlie mycelium of septate threads
spreads through the substratum for absorption of decaying
organic matter. The fructification, known as apothecium,
is in many species saucer-shaped (Fig. 311), in others

CRYPTOGAMS

191

bowl-shaped, or even club-shaped. The largest have
apothecia several inches across, but the commoner kinds

311. Peziza on wood.

312. Section of apothecium;
h, hymenium.

are a quarter inch or less in diameter. The interior of
the saucer is lined by a layer Qiymenium, Fig. 312) made
up of spore sacs (Fig. 313) and sterile filaments that
grow up between them. When ripe,
the (eight) spores escape by the rupture
of the sac (ascus). On germinating, the
spores give rise to mycelia, the apothe-
cia not ap-
pearing for a
considerable
time.

455. Micro-
sphaera Alni,
one of the
Powdery Mil-
dews, is par-
asitic, often
on the leaves
of Lilac (Fig.
314). . The
my c el i um

spreads over the surface of the
leaf and sends haustoria (suck-
ing hyphse) into the interior.
In the earlier part of the season

Simple erect filaments arise, at 314. Lilac leaf , infected by Micro-

tffe ends of which spores are

formed (somewhat as in Penicillium). Later, fructifica-

313.

A part of the hy-
meniiim, great-
ly magnified : a,
an ascus ; /, a
sterile filament.

192

CRYPTOGAMS

315. A perithecium brok-
en open to show
the asci.

tions are produced on the leaf surface, appearing to the
naked eye as minute rounded black bodies. These are
the perithecia "(Fig- 315) which in-
close the spore sacs. The perithecia
bear radial appendages.

456. Aspergillus, a very common
fine mold on dry bread, cake, cheese,
preserved fruits, etc., should be men-
tioned here, since, though it is really
an Ascomycete, it would not be rec-
ognized as such at one stage of its
existence. On first appearing upon
the given substratum the mycelium sends up great num-
bers of erect branches ending in globular heads, from
which are produced spores in chains
radially arranged (Fig.
316). At a later stage
of its history the myce-
lium gives rise to small
rounded fructifications
inclosing the character-
istic spore sacs of an

Ascomycete. In like 317- Fruit of AsPer-

gillus, with
manner other members asci (a).

of this group are known — KNY.

to pass through two stages of develop-

316. S^tion of the ment differing in the
method of spore bear-
ing. Periicillium, a very
common blue mold (Fig.

318), is an example.

457. The Rusts. — Many Fungi un-
dergo remarkable transformations in the

course of their life history. This is very

marked in the case of the Rusts, of which

the common Rust of Wheat (Puednia

r/raminis) may be taken for description.

*' . . ., J, . --t, 318. Sporophore of

It infests the leaves and stems of Wheat, peniciiiium.

sporophore of
Aspergillus. —
KNY.

CRYPTOGAMS

193

Rye, Oats, and various other grasses. The first appear-
ance of this Fungus in the spring that one is at all likely
to see, however, is not upon a grass,
but 011 the leaves of the common
Barberry, in the form of thick-
ened red patches. On the under
side of these areas, embedded in
the leaf tissues, are then found the
so-called cluster cups, or fructifica-
tions (Fig. 319),

filled with chains

of rounded spores.

New spores are

formed at the base

of the chains while

the terminal ones

fall off and are

carried by the winds to the Wheat (or

other grass). The mycelium produced

from these spores penetrates the body

of the new host,

where it increases

largely, working

320. A stalk of grass damage to the
with spores of Wheat, and form-

Puccinia break- . .-, f

ing through the mg at tne surface
masses of spores
for the further

319. Section through a clus-
ter cup of Puccinia in
the leaf of Barberry.

epidermis in
dark patches.

spread of the disease. The spores
produced on the Wheat are differ-
ent both in shape and in the manner
in which they are borne from the
spores of the cluster-cup stage on

Barberry. Moreover, on Wheat 32L Uredospores and a te-
the spores are of two sorts (Fig.
321): (1) unicellular uredospores,
prevailing until late summer or fall, the office of which is to
spread the Rust by immediate germination on being blows-

OUT. OF BOT. 13

leutospore (£) of Puc-
cinia. — DE BARY.

194

CRYPTOGAMS

to uninfected plants ; (2) two-celled teleutospores, charac-
teristic of the latter part of the season, thick-walled, and
fitted to survive the winter. While still
remaining on the dead stalks of the grain
in the following spring, the teleutospores
germinate. Each cell puts out a short
filament (Fig. 322) ; and on the sides of
these filaments small spores called spo-
ridia are formed. Finally, by these spo-
ridia the Barberry leaves are infected,
and the life cycle is brought to the point
at which this description was begun.

458. Puccinia graminis is one of many
Fungi adapted to different hosts at dif-
ferent periods of their life history, and
failing to develop if the proper hosts are
not met with at the particular stages
when they are required. The sporidia
of this Rust germinate only on Barberry;
while the cluster-cup spores and uredospores of the same
Fungus refuse to develop except on certain grasses
(Wheat, Oats, Rye, etc.).

322. Germination of
the teleuto-
spore (t) ; s,
s, the spo-
ridia.
-DE BARY.

Basidiomycetes

459. The Basidiomycetes include the Toadstools and
Puffballs and their relatives. The mycelia usually live
saprophytically in soil, leaf mold, decaying wood, etc.1
The fructifications which arise may be simple layers of
tissue, coating the surface of the substratum, as in the
whitish or brownish incrusting growths found everywhere
on the under sides of rotting sticks ; but in the majority
of cases they are stalked structures.

In the common Toadstool (Fig. 323) the stalk (stipes, s)
supports a cap (pileus,p) from which depend radial gills (la-
meUce, I). Upon the surfaces of these gills the sporiferous

1 Some Basidiomycetes are parasitic ; for example, the Fungus which
causes on Azalea and allied plants the growths known as "May Apples."

CRYPTOGAMS

195

layer Qiymenium) lies. Figure 325 shows part of the cross
section of a gill. The spores (s) are borne, usually in fours,

on enlarged hy-
pha tips called
b a s i d i a (B) .
This character
— namely, bear-
ing spores on
basidia — has
given the group
(Basidiomycetes)
its name.

460. Other types
of fructification. —
The Basidiomyce-
tes furnish the col- 324-
lector a great vari-
ety of curious and
interesting forms. A little search
in almost any woods will bring
some of them to light. The hy me-
nial layer is variously disposed.
In some incrusting forms men-
tioned above (Corlicium) it is sim-
ple (not folded) ; in Clavaria (Fig.
326) it covers the coral-like branches ; in Hydnum (Fig. 327) the hy-

A part of
the myce-
lium.

323. Fructification of a toadstool

(Amanita phalloides) : p,
pileus, or cap ; I, lamellae, or
gills.

325. Section of a gill, highly magnified : B, basidia; S, spores.

196

CRYPTOGAMS

menial surface is thrown into teeth; in the Pol}-
porus sub group (Fig. 328) the arrangement is
exactly the reverse, for the hymenium lines the
numerous pores. Branches, teeth, pores, and gills
are all devices for increasing the extent of spo-
riferous surface.

326. Clavaria.

327. Hydnum.

328. Polyporus : p, pores of the
under surface.

LICHENS (Figs. 329, 330)

461. Lichens form gray or yellowish patches on rocks
and trees, festoons on the branches, and incrusting sheets
and spongy mats on barren soil. They are commonly

known as " Moss " — a wholly
wrong name, as will be seen when

-a

329. A lichen (Physcia stellaris) :
a, apothecia.

330. Usnea barbata.

CRYPTOGAMS

197

we come to the real Mosses. A section through a Lichen
thallus (Fig. 381) shows large numbers of green cells
having much the appearance of such unicellular Algae as
Pleurococcus and Nostoc, held in the
meshes of a tissue made up of filaments
resembling Fungus hyphse. These
appearances represent the truth of
the matter. Lichens are composite
growths in Avhich certain unicellular
Algse and certain Fungi take part.
Figure 332 shows how this union be-
gins. The spore of a Fungus has
fallen near a cell of Pleurococcus.
The young mycelium is already ap-
plied to the Alga, which has divided.
Further development consists in. the

Section of a lichen
thallus.

extension and branching of
the mycelium, and the multi-
plication of the algal cells; the
construction, by these means,
332. Fh-st stages in the formation of a thallus having certain
of the lichen thallus.— distinguishing peculiarities of

BORNET. ,.

structure, according to the

kind of Fungus and the kind of Alga concerned ; and
finally, the production of a spore-bearing body. In many
Lichens this fructification is an apo-
thecium (Fig. 329, a) very like that
of Peziza, with a hymenium con-
taining spore sacs or asci (Fig. 333).
Most of the Lichen Fungi are Sac
Fungi. They are parasitic upon
the Algse and cannot exist without them. The Algae,
however, are known to be able to exist perfectly well
without the Fungi.1

1 Symbiosis (as the word is understood among English-speaking
botanists) is the living together of unlike organisms for mutual advan-
tage. Many botanists regard Lichens as examples of symbiotic accom-
modation.

Section of an apothe-
cium.

198 CRYPTOGAMS

LIVERWORTS AND MOSSES (BRYOPHYTES)

462. The account of Chlorophyllous plants was inter-
rupted at the end of the section on Red Seaweeds. A
series of colorless forms (Fungi) was then introduced, in
general structure and often in detail closely resembling
Algae. We return to chlorophyll-bearing plants at a point
where the ascending line of vegetable life leaves the
waters to become henceforward very largely terrestrial.

463. The words " line " and " series " are not to be understood in
too restricted a sense. For example, in Algae several seeming lines of
progressive development, running more or less side by side, are to be
discerned ; and the same may be said of any large group of plants.
Moreover the " line " or " series " is never continuous, — is in fact
merely a succession of considerably separated groups, through which
run certain general principles of structure. In the grand series begin-
ning with unicellular Algae and ending with Flowering Plants, many
breaks occur. That is, at certain points new features appear in the
plant body, not matched by anything in any known lower form. It is
not to be imagined that the whole organization is new — that the
break in the series is absolute. The nature of the cells upon which
the whole character of all vegetable life depends is always the same,
and certain reproductive processes are always essentially the same.
By the interruption of the series, we mean that in considering the ori-
gin of certain plants we are unable to find anything which we can
regard as their near ancestry in the lower grades. This is the con-
dition in the Liverworts. We may suppose they sprung from an
algal stock ; for the plant body is an expanded thallus, the habitat is
often damp earth or even water, and reproduction is brought about
through fertilization of an egg cell by antherozoids, as in many Algae.
But there is nothing by which we can fix the Liverworts as near rela-
tives of any particular one of the existing algal groups.1

464. Marchantia (Fig. 334), one of the commonest of
the Liverworts, is found growing prostrate upon the
ground in damp situations. The ordinary length is an
inch or two. The thallus forks frequently, and the
branches grow forward while the oldest portion of the
thalbis continually dies away ; so that finally the branches

1 By some authorities the Liverworts have been regarded as related
to the Stoneworts ( Characece) or the like ; by others to be descendants of
Algse resembling Coleochsete, the Water Shield.

CRYPTOGAMS

199

become separate individuals. The plant is attached to the
ground by absorptive hairs, or rhizoids. Above, the sur-

B

334. Marchantia : A, thallus with rhizoids (r), cupules (c), and archegonial
branch (6) ; B, section of archegonium, the fertilized egg (e) having
divided once; C, disk of fruiting branch cut to show sporogonia
(m, n, o) ; D, opened sporogonium with enveloping sheath (pe), and
remains of old archegonium (ar).

face is seen on close inspection to be divided into small,

slightly raised areas, each with a pore at the summit.

The pore leads into a chamber (Fig. 335), from the floor of

which rise short fila-

ments or rows of richly

chlorophyllous cells —

the chief assimilatory

tissue. This arrange-

ment has the same ef-

fect as that of the loose

tissues in the leaf of

Flowering Plants (see

Fig. 382), where pores (stomates) give free passage to gases,

while the epidermal covering retains moisture,

335. Section in upper part of thallus to
show P°re <P) and assimilating cells

200

CRYPTOGAMS

337'

465. Reproduction. — Upon the upper surface, over the
axes of growth, or midribs, small cup-shaped structures
called cupules (Fig. 334, A, c) are found. From the bottom
of each, several small lens-shaped bodies, composed of a con-
siderable number of cells, arise ; they are known as gemmce
(literally buds). When set free and scattered by rains and
running water they develop directly into new plants.
This is vegetative propagation much resembling the propa-
gation of Lilies by bulblets and various other Flowering
Plants by offsets. Gemmae serve the same purpose as
zoospores in the Algse, namely, rapid multiplication.

466. A second reproductive process is now to be de-
scribed, in which gametes much like the equivalent bod-
ies in Algse

take part. In
late spring
and in ear-
ly summer
erect, more

or less umbrellalike, branches are
found. They are of two kinds. In
one case (antheridial branches, Fig.
336) the termination is a disk with
scalloped margin. In the other the
stalks end in a disk from which
fingerlike rays
project (Fig.
334) ; these are
the archegonial
branches. In

depressions of the scalloped disks

stand the short-stalked antheridia.
The large cell of the anther-

idium (Fig. 338) becomes divided

into a great number of smaller

cells, in each of which a single

antherozoid is formed. The an-

therozoids are like those of Rock- —SACHS.

336. Antheridial branch.

338. Antheridium : anther-

CRYPTOGAMS 201

weed — and like the zoospores of many Algse — in hav-
ing two cilia for locomotion.

467. The archegonial branches bear on the under side
at the base of the rays rows of flask-shaped organs called
archegonia (Fig. 334, B). In the archegonium an egg cell
(e) is situated at the center of the enlarged basal part.
When ready for fertilization the egg may be reached
through the canal in the slender portion, or neck, of the
archegonium. When the dew is on the plants the anthero-
zoids make their way to the archegonial branches (which
at the season of fertilization are not much grown), and
swarm to the mouth of the archegonia. One of them
passes through the canal and fuses with the egg cell.

468. In most cases of oosporic reproduction in Algse
and Fungi, it will be remembered, the oospore falls from
the parent plant before it germinates. In Nemalion,
however, fertilization of the egg gives rise to a structure
organically united to the original plant; this structure
ultimately bears spores (carpospores), serving to dis-
seminate the species. Marchantia is like Nemalion in
the noteworthy fact that the oospore germinates in posi-
tion, and gives rise to spores only after an interval of
growth upon the parent plant. For after fertilization the
oospore divides into two, then into four, then into eight
parts, and so on. The mass of cells thus originating
grows and finally forms a stalked spore capsule (Fig.
334, c, D), or sporogonium. The foot of the sporogonium
is embedded in the tissue at the base of the old arche-
gonium (ar).

469. The spores are numerous, free, rounded or some-
what angular, walled cells. When the capsule bursts, one
sees that it contains a great number of fine threads mixed
with the spores. They have the property of twisting and
untwisting with changes of atmospheric moisture, and so
serve to give the spores to the winds from time to time.
From the spores new plants develop.

470. The archegonium is a structure that is found in
no plant lower than the Liverworts. As we go upward,

202

CRYPTOGAMS

however, the archegonium appears in all the cryptogamic
forms, and even in the Gymnosperms among Flowering
Plants. In Liverworts and all plants higher in the vege-
table series the fertilized egg cell germinates in position,
and develops to a spore-bearing body.

471. Other Liverworts. — Some of the Liverworts are simpler than
Marchantia. The archegonia and antheridia are borne by the thallus

without the forma-
tion of special erect
branches. The
structure of the spo-
rogonium (spore-
bearing body) dif-
fers widely in other
339. A foliose Liverwort. members of the

group also. Many

of the species — e.g. many small forms found on tree trunks — show a
distinction of stem and leaf (Fig. 339). Between thalloid and leafy
forms gradations are found. The essential structure of archegonium
and antheridium is the same throughout the group.

472. Mosses are closely related to the Liverworts. The
foliose (leafy) Liverworts might indeed at a casual glance
be mistaken for Mosses. In the latter, however, the
leaves are generally arranged

radially about the stem (Fig.
340) ; while in the foliose Liver-
worts, as seen from Fig. 339,
the leaves are so disposed that
the whole shoot has a flattened
character in accordance with
the creeping habit.

473. The Mosses live in
ver}' diverse situations. Some
common species grow wholly
submerged in running water
like Algae. Again, many com-
mon species inhabit extremely
dry places, like the bare face

of rocks, where there is no soil but dust and debris col-
lected by the Mosses themselves, and where the plants can

340. A Moss shoot after the pro-
duction of a sporogonium :
s, spore capsule ; o, opercu-
lum ; c, calyptra.

CRYPTOGAMS

203

have water only when dew or rain falls. Other kinds live
in the crevices of bark on tree trunks ; others on soil. The
Sphagnum Mosses live in bogs, of which they sometimes
form the chief vegetation. Peat from
these bogs (used for fuel in some coun-
tries) is to a considerable extent made
up of the dead stems and leaves of these
Mosses.

474. Reproduction is essentially the same
in Mosses as in Liverworts. On the end
of the stem, usually,
at the proper sea-
son archegonia (Fig.
341) are found. An-
theridia (Fig. 342)
arise in a similar

341.

position ; but in
most species the
two kinds of or-

(/) on the end of a gans OCCUr on dif-
Moss stem. j? i mi

terent snoots. Ine

342. Group of antheridia : (a)
and sterile filaments

Archegonium
of a Moss :
e, egg cell;
n, neck; I,
lid (opening
before fertil-
ization) .
— SACHS.

antlierozoid is motile by means of two cilia, and reaches
the archegonium and finally the egg cell when the plants
are wet. Fertilization
results, as in Liverworts,
in the production of a
(usually long - stalked)
sporogonium (Fig. 340).
The upper part of the old
archegonium may be car-
ried up on the growing
sporogonium as a cap
(calyptra, c). The spore
capsule opens for libera-
tion of the spores by the

displacement of a lid (operculum, o) in most Mosses.

475. When the spore germinates it gives rise, not to the

Moss shoot directly, but to a many-branched filamentous

343. Protonemaof Moss: b, bud of Moss
shoot. — FRANK.

204

CRYPTOGAMS

growth called the protonema, which' spreads over the soil
and resembles a filamentous Green Alga. Finally shoots
appear as buds on the protonema (Fig. 343).

476. It will be noticed that in the Bryophytes (Liver-
worts and Mosses) the fertilization of the egg cell does
not, as in most Algse, produce an oospore which separates
from the parent and develops into a new and distinct
plant. The fertilized egg remains in position in the
archegonium and gives rise to the spore-producing organ,
or sporogonium.

FERNS AND FERN ALLIES (PTERIDOPHYTES)

477. Most of the Ferns and Fern allies of to-day are
comparatively small plants, frequently with a creeping
habit; some grow partly or wholly submerged; while
several small species are floating plants. All this is in
strong contrast with conditions in former geological times.
In the Coal period Tree Ferns (now confined to the

tropics) were widely distributed.
Certain relatives of the modern
slender, creeping Club Mosses (Fig.
357) were trees from 60 to 80 feet
in height. Similarly some Equise-
tumlike plants, now represented
mainly by species from 1 to 4 or 5
feet tall (Fig. 358) were tolerably
stout trees 30 feet high. Forests
largely composed of these Crypto-
gams formed the immense coal de-
posits of that period.

478. Ferns are still numerous, and
in some places are predominant fea-
tures of the vegetation. In the
tropics they are especially abundant

344. A tropical Tree Fern. and large (Fig. 344). In most com-
mon species the stem is a creeping

rhizome (Fig. 345), wholly or partly buried, so that all
that one sees is the foliage rising from the ground. Ferns

CRYPTOGAMS

205

have true roots, — unlike Mosses and Liverworts, which
are attached only by hairs, or rhizoids.

34U. Under side of a segment of Fern
leaf, showing sori.

345. Rhizome and leaves of the
Rock Fern.

347. Section of sorus: s, sporangia;
i, indusium ; 6, blade of the.
leaf. — WOSSIDLO.

479. Spores are borne in
small sporangia (Fig. 348),
clustered in groups on the

under sides of the leaves (Fig. 347). Each cluster, or
" fruit spot" (soms), is in many species shielded by a
membrane (indusium, i). At maturity, and on the occa-
sion of certain conditions of moisture in
the atmosphere, the sporangium splits
at one side. The top is slowly thrown
far back, and then suddenly resumes its
former place. The
spores are ejected by
the violence of the
motion.

480. The germination of the spore
results in the formation of a small,
thin, heart-shaped body called the
protliallium (Fig. 349), in shape and
habit of growth much resembling a
small thalloid Liverwort. Prothallia of common species
are from a quarter to a half inch in diameter, and may

348. A sporangium.

349. Fern prothallium:
ar, archegonia ;
an, antheridia.

206

CRYPTOGAMS

be found on bare, moist earth under Ferns ; or, better,
in greenhouses. They are attached to the soil by rhi-
zoids, most of which spring from a median thickening, the
cushion. On the under surface, mainly nearer the more
pointed end of the prothallium, hemispherical antheridia
are borne (Fig. 350, J9), in which the spiral, ciliated
antherozoids (Fig. 350, (7) have their origin. Archegonia
(Fig. 350, A) may be found on the same prothallia, nearer

the notched (younger)
extremity. In some spe-
cies, however, antheridia
and archegonia are always
borne on different prothal-
lia ; though the spores
from which the two sorts
of prothallia arise are
indistinguishable .

481. ^Fertilization of the

350. A, the archegonium with egg (e), and _ ^ ^^ ^^ ^^

prothallia are wet

canal (c) ; B, antheridium; G, an-
therozoid, very highly magnified.— the

with dew or rain, by the

entrance of an antherozoid into the archegonium and the
conjugation of antherozoid and egg cell.

482. The result is the division of the egg and the for-
mation of an embryonic Fern plant (Fig. 351), in which
the beginnings of leaf, stem, and root

can soon be made out. Commonly
only one of the several archegonia which
may be fertilized gives rise to a per-
fected Fern plant. After the establish-
ment of the latter, the prothallium dies.

483. The entire life history of the
Fern thus comprises two stages, that
of the prothallium (bearing archegonia

and antheridia), and that of the leafy, 351. prothallium with

spore-bearing plant. It will be recalled

that in some of the lowest Algae (e.g.

Vaucheria) the same individual plant gives rise to spores

young spore-
bearing plant.

CRYPTOGAMS 207

(zoospores) germinating without fusion, and gametes

destined to conjugate. In Ferns it is plainly seen that

the two sorts of reproductive cells

(spores and gametes) are not borne

at the same period, but at very dif-

ferent stages of the life cycle. The

two stages regularly alternate. This

phenomenon is known as the Alter-

nation of Generations. That form ^ Section trough a

very young Fern

(stage or generation) of the plant plant: s, stem; /,

that bears gametes (egg cell, anther- leaf ; r, root ; p, the

' prothallmm; a, a,

ozoid) is called the gametopliyte ; in remains of arche-

Ferns the prothallmm is the gameto-

phyte. That form (stage or gen-

eration) which bears spores is the sporophyte; in Ferns

the leafy plant is the sporophyte.

484. The Fern prothallium corresponds to the thallus
of a Liverwort and the protonema and shoot of a Moss ;
for these structures all bear archegonia and antheridia.
The final result of fertilization in Liverworts and Mosses
is a sporogonium, i.e. a spore-bearing body. The final
result of fertilization in Ferns is also a spore-bearing
body — the Fern " plant." Sporogonium and Fern " plant "
have the same origin ; they are therefore of the same
nature : both are sporophytes. The sporophyte of Liver-
worts and Mosses (the sporogonium) has no root, but is,
so to speak, parasitic on the parent plant, or gametophyte.
The sporophyte of Ferns has a root, as well as leaves, and
after the very first is self-supporting.1

485. Selaginella (Fig. 353) is usually a creeping plant
(a common species is ascending), with leaves dorsiventrally
arranged ; i.e. so placed that the shoot shows an upper and
an under side. Special branches are often given off below,
from which roots are sent out. The sporangia spring from

1 Alternation of generations is not confined to Bryophytes and Pterido-
phytes, though in the Pteridophytes it is easier to see than elsewhere in
the vegetable kingdom. It is foreshadowed in the Thallophytes and occurs
in all plants above them.

208

CRYPTOGAMS

leaf axils in the terminal "fruiting spikes " (Fig. 354).
They are of two kinds as concerns contents, and often as

353. Selaginella.

concerns size and color. The larger (macrosporanyia, ma,
Fig. 354) each contain four large spores, or macrospores ;
the smaller (microsporangia, mi) con-
tain large numbers of very much
smaller microspores. Macrosporangia
are found only in lower axils, or else
only in axils on one side of the spike.
Leaves with which
sporangia occur, as
here, are termed
sporophylls.

486. In the af-
ter development of
the spores Selagi-
nella departs in a
remarkable man-
ner from the Ferns. The spores of
Ferns give rise to distinct structures
(prothallia) upon which archegonia
and antheridia are produced. In
Selaginella the germination of the
spore goes no farther than the formation of a number of
cells within the original spore walls. Moreover, the nature
of these internal formations is different in the two kinds

ma-

..mi

355. Section of micro-
spore: s, cells
in which an-
therozoids ori-
ginate; p, pro-
thallial cell.

354.

Fruiting spike of
Selaginella (/),
and the same in
section magni-
fied : ma, macro-
sporangium ; mi,
microsporangium.
— GOEBEL.

CRYPTOGAMS 209

of Selaginella spores. In the microspore these cells,

filling the whole interior, compose an antheridium, with

only the slightest rudiment of a prothallium ; and

within this antheridial body are formed antherozoids.

In the macrospore a reduced prothallium appears. This

finally increases sufficiently to burst

open the spore at one end (Fig. 356) ;

and on the exposed surface several

archegonia develop. Fertilization

takes place after the spores have

fallen to the ground, when water is

present to allow the antherozoids to

make their way to the archegonia.

Then, as in Ferns, an embryonic plant

is formed, which soon develops stem, ***• The .

with prothallium
root, and leaves. (p) bearing ar-

487. Two points are to be particu-

larly noted with regard to the repro- tion.

duction of Selaginella :

(1) Spores are of two kinds as regards (a) origin, (6) size,
(c) ultimate development. For they originate in different
kinds of sporangia, are very unequal in size, and give
rise to antheridia and archegonia, respectively. This con-
dition is foreshadowed in the Ferns, of which some species
have two sorts of prothallia (§ 480). Here (in Selaginella)
the differentiation extends to the spores and sporangia.

(2) The gametophyte (prothallial structure) is reduced
so much that it is held in the original spore walls, and has
lost all independence, possessing neither chlorophyll nor
rhizoids.

488. Other Pteridophytes which one will frequently
see are Lycopodium, the Club Moss, and JEquisetum, the
Scouring Rush or Horsetail.

489. Lycopodium (Fig. 357), to be met with in woods
and old pastures and in partly shaded situations, resem-
bles Selaginella in general habit, except that the leaves are
usually arranged radially. The rhizome runs close to the
ground or in the soil, and sends up erect branches. Spo-

OUT. OF EOT. - 14

210

CRYPTOGAMS

rangia, all of one sort, are borne in leaf axils (s, Fig. 357).
The sporangia! leaves are usually grouped apart in a " fruit-
ing " spike. Spores are of one
kind, and give rise to prothallia
which in many species are fleshy,
tuberculate bodies, leading a more
or less subterranean existence.
Fertilization and the growth of
the sporophyte have much the
same history as in Ferns.

490. Equisetum, the Horsetail,
or Scouring Rush (Fig. 358),
grows preferably in
sandy soil, and often
in moist situations.
One of the common-
est species is to be
found along railroad
banks. The north-
ern species are, in
general, a foot or so
tall, though in the
spo- tropics Equisetum
giganteum, a slen-

357. Lycopodium: /, fruiting portion;
rangium in axil of a sporophyll.

der, clambering species, reaches a height of thirty feet.

491. The upright shoots spring from a running base.
The stem is clothed at the nodes by short sheaths of con-
joined scaly leaves. When branches arise they spring
from the nodes and display the same arrangement of
reduced foliage (Fig. 358).

492. The terminal portion of fertile shoots is converted
into a spore-bearing region (/), in which the leaves are
peculiarly modified (Fig. 358, B, C). They are peltate in
form, and bear on the under (or inner) side pocketlike
sporangia projecting toward the stem. The spores are
very numerous. Each one is provided with two narrow
strips of membrane (called elaters, Fig. 358, 2>), fastened
to the spore at their middle points, the four extremities

CRYPTOGAMS

211

extending like arms when dry, but curling up suddenly
when moistened by water or damp air. If a lot of the
dry spores under the microscope
is gently breathed upon, it is seen
that the elaters almost instantly
curl ; and in doing so the elaters
of neighboring spores become en-
tangled, so that the hitherto dust-
like heap becomes a coherent fluffy
mass. This entanglement of the
spores is of importance in the
economy of the plant, from the
fact that the prothallia to which
they give rise are of two kinds.
One kind bears archegonia alone,
the other only antheridia. If
archegonial and antheridial pro-
thallia were separated, evidently 353, EquisetUm: A, a shoot

fertilization of the egg Cells by bearing a fruiting cone

, , . -, (/) ; B, axis and spo-

the antherozoids could not take lophylls of the cone-

place, and new Equiseturn plants G> sectional view of a

•i-i.i i T mi sporophyll; D. a spore.

would not be produced. The pro-

thallium and its organs are so much like corresponding
structures in Ferns that no separate description need be
given here.

Relationship of Cryptogams and Phanerogams. — Suppose in the ma-
crosporangium of Selaginella only one macrospore were to mature ;
that this macrospore were to remain permanently in the sporangium ;
that the prothalliuin were to be still further reduced, so as not to burst
the macrospore wall ; that the microspore should be brought to the
macrosporangium, and put out a tube, which, penetrating into the
macrospore, should conduct the antherozoids to the archegonia; and
that the resulting Selaginella plant should develop and form its first
pair of leaves quite within the macrospore, — then we should have
an arrangement very like what actually exists in ovule, pollen, and
seed in Flowering Plants. The embryo sac of Phanerogams is
regarded as a macrospore remaining in its sporangium (nucellus of
ovule, the integuments representing the indusia of some Pterido-
phytes). The several nuclei of the sac probably represent cells of a
reduced prothalliurn, the egg cell standing for the egg cell of an arche-

D

212 MINUTE ANATOMY OF FLOWERING PLANTS

gonium. In the embryo sac of Gymnosperms (Conifers, etc.) a defi-
nite prothallial tissue is formed with rudimentary archegonia at the
summit.

The pollen grain of Phanerogams corresponds to the microspore
of Selaginella. At the time of fertilization there are three or more
cells in the pollen grain and tube. These cells — like those in the
developed microspore of Selaginella — are regarded as prothallial in
character, two of them (those which pass through the pollen tube to
the embryo sac) being equivalent to antherozoids. In some Gymno-
sperms the fertilizing bodies from the pollen are motile, like the an-
therozoids of Pteridophytes.

Thus the gametophyte of Flowering Plants is wholly within embryo
sac and pollen grain. In Liverworts the gametophyte (vegetative
thallus) is larger than the sporophyte (sporogonium). In Ferns the
proportions of the alternating generations are reversed, the gameto-
phyte being much the smaller. In Flowering Plants reduction of
gametophyte and increase of sporophyte have been carried to an
extreme. The carpels and stamens of Phanerogams are the spore-
bearing leaves, ovules (or their nucelli) and pollen sacs being spo-
rangia ; carpels and stamens are therefore often termed sporopliylls.

XVII. THE MINUTE ANATOMY OP FLOWERING

PLANTS

493. Cellular structure. — Attention has already been
called, incidentally, in several places, to the fact that plants
are made up of definite members of small size, called cells.
All new cells are formed from preexisting cells. Com-
monly this comes about by division : the original cell
divides to form two or more, each of which may increase
by independent growth, and in turn give rise by division
to new cells. The very first cell of the embryo has a
different origin, however. In fertilization, a nucleus from
the pollen tube, entering the embryo sac of the ovule,
fuses with a nucleus there found (see Fig. 164). As the
result of this union the initial cell of the new plant is
formed within the embryo sac. All future increase pro-
ceeds by division and independent growth.

494. The cell, then, is the unit of plant structure. —
It is the unit also of plant activity. Whatever activities
the plant as a whole manifests — such as growth, move-

MINUTE ANATOMY OF FLOWERING PLANTS 213

ment, absorption of food material, assimilation — these
activities are carried on by the cooperation of the cells
composing the plant. This being the case, it is important
to know something of the structure of the typical vege-
table cell.

495. Structure of the cell. —In illustration of the
typical vegetable cell, we might select cells from the apex
of a growing stem or root,
or from a leaf rudiment, or
from the young, growing
fruit. Thin sections cut
from any of these regions
would show, under the com-

pound micro-
scope, the
cells as sev-
eral angled,

359. Sectional view of young cells from

the root tip.

thin - walled components of the tissue
(Fig. 359).

496. The living substance of the cell is
protoplasm. It has been described as being
of a jellylike consistency. A better illus-
tration of the semifluid, yet cohesive, prop-
erties of protoplasm is afforded by the raw
white of egg. The fluidity varies in differ-
ent portions of the protoplasmic body of the
cell, some parts being relatively firm, oth-
ers containing a very large percentage of
water, and being, therefore, capable of
stiii'o-in •• hair more or less rapid movement in circulating
of a Nettie, currents. In some cells in which the nu-
terminal cleus ^s suspended near the center by
cell the cir- threads of protoplasm (Fig. 360), the cur-

culation of , •, , ,

protoplasm rents may be seen in the threads, passing

is indicated toward and away from the nucleus. Two

opposite currents may often be observed in

the same thread. In cells like the largest one of Fig.

362 the whole body of protoplasm, except that part

214 MINUTE ANATOMY OF FLOWERING PLANTS

directly in contact with the walls, may be in slow rota-
tion, dragging with it the nucleus. l

497. The term protoplasm includes all the living constit-
uents of the cell. " The word protoplasm is a morpho-
logical term. . . . Protoplasm is not a single chemical
substance, however complex in composition, but is com-
posed of a large number of different chemical substances,
which we have to picture to ourselves as most minute
particles, united together to form a wonderfully complex
structure. ... In this mixture of substances, the wonder-
ful vital phenomena may very frequently be observed
(contractility, irritability, etc.)." 2

Of the protoplasmic cell contents we have to distinguish
a rounded central body, the nucleus (Figs. 359, 362, n), in

many young cells occupying a
considerable portion of the cell
space; and the general mass,
aside from the nucleus, called
the cytoplasm.

The nucleus is denser than
the cytoplasm. It is made up
of definite parts, differing in
chemical constitution, definitely
arranged. Although actually
of extremely small size, the nu-
cleus is a highly organized
body. It is the controlling part
of the cell. It is the first part
to divide when new cells are to
be formed, and in division
passes through a complicated
series of changes (Fig. 361), by
which equal shares in all the essential constituents of the

Nuclear and cell division :
A,B,C, successive stages ;
n, region of the nucleus;
c, cytoplasm ; d, d, begin-
nings of daughter nuclei.
In C, the original cell has
become divided internally
into two, each with a large
nucleus (n).

— GUIGNARD.

1 Stamen hairs of Tradescantia, cells of the leaf of Elodea canadensis
or of Vallisneria spiralis, and cells of Stonewort (CTmra), are objects in
which movements of protoplasm may be studied. See Goodale, Ch. VI. j
Strasburger, p. 244.

2O. Hertwig, "The Cell," p. 13.

MINUTE AN ATOM T OF FLOWERING PLANTS 215

parent nucleus are assured to the two resulting nuclei.
Only after the nucleus of a cell has finished its division,
is the surrounding cytoplasm separated into two portions.
The production of two cells from one is completed by the
formation of a new transverse wall.

498. Many cells possess, in addition to the nucleus, pro-
toplasmic organs performing special offices in the general
work of the cell. Cells from the interior of the leaf, for
example Fig. 382, contain numerous rounded or lens-
shaped bodies, lying in the cytoplasm near the walls.
These bodies, colored green by the chlorophyll pigment
which they contain, are the
chlorophyll granules or chlo-
roplastids. They give plants
their characteristic green
color. They are active in
carbon assimilation. Simi-
lar cell organs, with red
or yellow pigment instead
of green, give color to
fruits and flowers. They
are called chromoplastids.

A thin external layer of
the cytoplasm next the cell
wall may be distinguished
by its superior clearness and
the absence of granulation.
It is very probable that this
really constitutes a sort of
membrane, possessing a closeness of structure and tenacity
above that of the rest of the cytoplasm. The remainder
of the cytoplasm is highly granular in appearance, owing
chiefly to the varying density of the protoplasm itself.
Except in their earliest stages active cells contain inter-
spaces, or vacuoles, filled with water and dissolved sub-
stances (Fig. 362). One large vacuole may fill the
greater part of the cell, the protoplasm forming a layer
next the wall. The watery contents of the vacuole or

216 MINUTE ANATOMY OF FLOWERING PLANTS

vacuoles is the cell sap. It is sometimes colored. The
red and yellow colors of healthy leaves are generally due
to colored cell sap in some of the cells, masking the
green of the chlorophyll granules. Bright colors of fruits
and flowers also are generally due partly to colored cell
sap. The cell sap may contain sugar in storage, as it does
in the root of the sugar beet and in the stem of the sugar
cane.

Certain substances belonging to the class of formed mat-
ters (non-protoplasmic) are of such frequent occurrence
and are produced in masses of such
size in the cell that they should be
briefly described.

499. Starch. — Starch is the form
in which elaborated plant food is most
commonly stored. It is laid down in
the cells of storage organs, e.g. tubers,
in rounded granules (Fig. 363). When
these are considerably magnified they
are seen to be stratified, in evidence of
the mode of deposition of the starch in successive layers.
If the granules are
closely packed to-
gether, they may
become angular in-
stead of rounded.

500. Protein gran-
ules and crystals. —
The external stor-
age cells of wheat
grains afford exam-
ples of protein gran-
ules (Fig. 364). The

Contents of these 364. Transverse section near the outside of a Wheat
Cells make Up the grain : «, the husk (pericarp, integuments) ;

,, , 6, cells with protein granules; c, starch

SO-Called gluten of cells. -TSCHIRCH.

1 Protein is the name given to organic substance, whether of animal or
of vegetable origin, containing nitrogen and a small proportion of other

363. Starch cells from
Potato tuber.

MINUTE ANATOMY OF FLOWERING PLANTS 217

I— J

wheat, which is, or should be, a highly nutritious element
of wheat flour. In the cells of the potato tuber are to be
found examples of proteid matter formed
into cubical crystals. These granules and
crystals are storage forms of protein.

501. Crystals of calcium compounds —
calcic carbonate and oxalate — are of very
common occurrence (Fig. 365). These are
generally considered to be waste products
of the chemical changes going on in the
cells.1 Other substances also occur in
crystalline form, but less frequently.

502. The account here given of the typi-
cal vegetable cell, as regards protoplasmic
structures and cell contents, is of course

brief and incomplete; it is meant to be 355. ceils contain-
suggestive of the extent of the subject. in& «eedie-

rm c 1-11 like crystals

Ihe nature 01 the cell has been, and will (raphides)of

long continue to be, the object of the
investigations of numerous workers.

503. Certain cells of certain plants regularly contain
more than one nucleus each. And in not a few of the
lower cryptogams great numbers of nuclei exist within
a common wall. The many-branched plant body may
in such cases consist of one continuous chamber without
internal division walls. Each nucleus represents a single
cell, but there is no corresponding division of the cyto-
plasm.

504. The cell wall. — Early investigators assigned to
the cell wall the chief importance ; but we now know that
life resides in the protoplasm, and that the wall is of
secondary importance. In many of the lower plants the
contents of certain reproductive cells break from their
walls, and swim freely forth (Fig. 285). Only after a

matters in addition to the carbon, hydrogen, and oxygen which compose
starch and sugar. Proteid substances enter directly, and as such, into
the composition of protoplasm.

1 It is quite possible that calcium oxalate is a storage form of food.

calcium oxa-
late.

218 MINUTE ANATOMY OF FLOWERING PLANTS

period of active locomotion do they settle down and
become invested with a membrane. This fact, among
others, shows the essential independence of protoplasm in
cells, and the subordinate role of the wall.

The wall is a product of the protoplasm. New walls
are formed by the conversion of a portion of the proto^
plasm into the substance of the wall. In
young cells, and many old cells, this sub-
stance is cellulose, chemically resembling
starch. It is a regular occurrence that
in certain of the cells of the plant body,
the protoplasm becomes at length wholly
converted into wall, when, of course, the
life of these particular cells is at an end.
In the later phases of this process, the
depositions may take a form differing
chemically from cellulose. We have, for
instance, in wood cells, lignified walls; in
cork cells, walls containing a fatty sub-
stance called suberin. Modified walls of
these sorts have physical properties differ-
ing from those of cellulose. For exam-
ple, the suberized walls of cork resist the
entrance of water, whereas the cellulose
366. Wood fibers in of pith and the lignified walls of wood
take water into their pores readily.

Walls are seldom, or never, evenly
face v'ieTof thickened when the depositions are con-
pits; 6, the siderable, but certain areas remain thin,
pitsinsection. eyen ftfter the completion of the thicken-
ing process. Or the greater part of the cell wall may fail
to thicken, and then the depositions take the form of
raised markings on the interior of the walls. Examples
are the annular and spiral ducts (Fig. 371).

505. Changes in the shape of the cell. — The'cells of the
growing tips of the stem and root, and young and actively
dividing cells elsewhere, are, in general, nearly isodiamet-
rical. Subsequently, many of these cells become greatly

longitudinal
section: a,
part of the

MINUTE ANATOMY OF FLOWERING PLANTS 219

changed in shape. Cells of the external layer are in
many instances flattened, in accordance with their protec-
tive function. Cells of strengthening and conducting
tissues, on the other hand, are frequently greatly elon-
gated. In the conducting tissues, elongated cells placed
end to end in rows become united into tubes or ducts,
the end walls being absorbed, wholly or in part, to allow
the passage of liquids.

506. Several of the principal modifications of cells should
now be described. We may begin with

wood fibers.

507. Wood, whether occurring in so-
called woody stems, or in succulent herba-
ceous stems, consists largely of fibrous
cells, associated, in most cases, with ducts,
or vessels. The fibrous cells are of a great
variety of form and appearance in differ-
ent plants ; but those which are termed,
in rather an indefinite way, wood fibers,
are pointed cells, several times longer
than broad, having thickened and lignified
walls, and characteristically showing in
these walls numerous pits, i.e. spots where
the walls have remained thin or become
perforated in such a way as to allow com-
munication between the cells (Fig. 366).

508. Bast fibers. — These are found in
strands in the bark. They are generally

of considerable length, compared with their diameters.
Their walls are generally much thickened, so that the
internal space, or lumen, is small, as seen in cross section
(Fig. 367). Bast fibers give strength to the inner, stringy
bark of the Basswood, the Grapevine, the Leatherwood,
and so on. They constitute the fiber of Flax, from which
linen fabric is woven.

509. Collenchyma. — The name collenchyma is given to
masses of cylindrical or prismatic cells, having walls
thickened at the corners in a peculiar manner (Figs. 368,

220 MINUTE ANATOMY OF FLOWERING PLANTS

308. Cross section of
collenchyma.

369). These walls, when seen in cross section, have a
distinctive glistening ap-
pearance. Collenchyma

— tissue composed of
such collenchymatous cells

— is one kind of strength-
ening tissue. It is to be
found near the surface
of herbaceous stems, of

petioles, and of leaves, along the midribs.
510. Grit cells, or sclerotic cells, with very

mucli thickened hard walls, are exemplified

in the rind and external flesh of the pear,

where they occur in groups. The walls

are traversed by canals, of the same nature

as the pits spoken of above (Fig. 370).

Shells of nuts also
give good illus-
trations of cells
with walls simi-
larly thickened,
and affording pro-

W:^

Q
P

k

?~

Grit cells from a pear.

369. Longitudinal
section of
collenchyma.
The lens-
shaped bod-
ies are chlo-
rophyll gran-
ules.

tection by consequent firmness.
511. Cell union, or fusion, is
illustrated in the case of many ducts, in which
it is impossible to distinguish the original cells,
placed end to end. The ducts of the wood are
tubes giving unbroken communication between
the absorbent roots and the leaves. The walls
may remain relatively thin ; in this case they are
braced internally by rings or spiral thickenings
(Fig. 371). The ducts take their names from
their markings, being designated as annular, spi-
ral, or pitted ducts, etc.

512. Milk tubes, or, in more technical lan-
guage, latex tubes, holding the milky juice of Poppies,
Dandelions, and allied plants, are formed from originally
distinct cells by the breaking down of intervening walls

371. Spiral
duct.

MINUTE ANATOMY OF FLOWERING PLANTS 221

372. Latex tubes (J).

— TSCHIBCH.

(Fig. 372). The cell fusions may take place mainly in
longitudinal directions, giving the
semblance of jointed tubes, or in all
directions, producing a dense net-
work. In the Milkweeds and the
Euphorbias the milky juice (latex)
is held in elongated, branching,
tubular sacs originating as single
cells in the embryo, and growing
with the growth of the plant until
they have pushed their way into
every part of the plant body. The
latex itself is a mixture of a con-
siderable variety of substances;
sometimes some of the ingredients
are poisonous, as, for example, mor-
phia, the active principle of opium, found in the latex
of the Poppy.

513. Tissues. — The word tissue has been frequently
used above without exact definition, yet probably without
misapprehension. Technically the term tissue means a
mass or collection of cells of the same kind. Any num-
ber of cells of a certain kind constitute a particular kind
of tissue. Thus collenchyma, a particular kind of tissue,
was described above.

514. Fibrovascular bundles are so called from the fact
that they are made up largely of fibrous cells and vessels
(ducts). In a translucent herbaceous stem like that of
the Balsam, the bundles may be seen without dissection,
as strands lying not far beneath the surface, traversing the
entire length of the stem, and giving off branches to the
leaves. In the cross section of such a stem these bundles
would be seen as several — perhaps five — areas more
opaque than the surrounding parenchyma, arranged ap-
proximately in a circle (compare Fig. 376). Upon exami-
nation with a proper power of the microscope each bundle
would be seen to consist of three parts (Fig. 373). The
inner of these consists largely of wood fibers and ducts.

222 MINUTE ANATOMY OF FLOWERING PLANTS

373. Fibrovascular bundle of a Di-
cotyledon : ph, phloem ; c,
cambium ; d, duct, and /,
fibers of the xylem.

It is called the xylem or wood portion. The outer con-
tains more rounded cells, but typically possesses bast

fibers in groups, and scat-
tered tubes. It is called
the phloem. Between xylem
and phloem is a region occu-
pied by thin-walled formative
tissue, from which, by cell
division, growth, and modi-
fication, all the elements of
both xylem and phloem are
derived. It is called the cam-
bium. The cambium, during
the active growth of the stem,
continuously forms xylem on
one side, phloem on the other.
The outside of the xylem is thus the newest, while the
innermost parts of phloem are the newest. In old, woody
stems, where the number of bundlesjsancr eased, and they
are crowded together, the cam^ji^^S^ffie^sev^ral bundles
are continuous around th
stem, forming a thin sheat
outside the wood. It is at
the cambium that the bark
of twigs, especially in spring
when growth is most active,
may easily be separated from
the wood. The phloem is
then, of course, removed with
the bark, of which it forms
the inner part.

515. Fibrovascular bun-
dles of the sort described in-
crease in thickness from year
to year, if the plant is a
perennial. They are found in dicotyledons. The charac-
teristic bundle of the monocotyledons lacks the cambium
(Fig. 374). The xylem also is much reduced. Each

374. Monocotyledonous fibrovascu-
lar bundle : ph, phloem ; d,
duct (xylem) ; p, pith cell.

MINUTE ANATOMY OF FLOWERING PLANTS 228

bundle is surrounded by a sheath of thick-walled lignified
tissue, to which it largely owes its tensile strength. Once
formed from the general formative tissue of the stem,
the bundle shows no further growth, no annual increase
of xylem and phloem.

STRUCTURE OF STEMS

516. On one or the other of two types the stems of
phanerogamous plants are constructed. In one, the wood
is made up of separate bundles, scattered here and there
throughout the whole diameter of the stem. In the other,
the wood is all collected to form a layer between a central
cellular part which has none in it, the pith, and an outer
cellular part, the bark.

517. An Asparagus shoot and a Cornstalk for herbs,
and a Rattan for a woody kind, represent the first.
To it belong all monocotyledons. A

Beanstalk and the stem of any common
shrub or tree represent the second; and
to it belong all plants with dicotyledon-
ous or polycotyledonous embryo. The
first has been called, not very properly,
endogenous, which means inside grow-
ing ; the second, properly enough, exo-
genous, or outside growing.

518. Endogenous stems, those of mono-
cotyledons, attain their greatest size and 375. structure of a

, . . . , , , • T» i Cornstalk, in

most characteristic development in .r alms
and Dragon trees. A typical endoge-
nous stem has no clear distinction of pith,
bark, and wood, concentrically arranged,
no silver grain, no annual layers, no bark
that peels off clean from the wood.

519. Exogenous stems, those of plants

coming from dicotyledonous and also polycotyledonous
embryos, have a structure which is familiar in the wood of
our ordinary trees and shrubs. It is the same in an herba-

t ran averse

and longitu-
dinal section.
The dots on
the cross sec-
tion repre-
sent cut ends
of the woody
bundles.

224 MINUTE ANATOMY OF FLOWERING PLANTS

ceous shoot as in a Maple stem of the first year's growth
(Fig. 376), except that the woody layer is commonly thin-
ner, or perhaps reduced to a circle of bundles. The wood

377

378

376. Diagram of a cross section of a very young exogenous stein, showing six
fibro-vascular bundles. 377. Same later, with bundles increased to
twelve. 378. Still later, the wood of the bundles in the form of wedges
filling the space, separated only by thin lines, or medullary rays, run-
ning from pith to bark.

all forms in a cylinder — in cross section a ring — around

a central cellular part, dividing the cellular core within,.

the pith, from a cellular bark without. As the wood
bundles increase in number and in size,
they press upon each other and become
wedge-shaped in the cross section; and
they continue to grow from the outside,
next the bark, so that they become very
thin wedges. Between the wedges are
still thinner plates (in cross section lines)
of much compressed cellular tissue, called
medullary rays, which connect the pith
with the bark. The plan of a one-year-
old woody stem of this kind is exhibited
in the diagrams.

520. When such a stem grows on from

379. Cross section of year to year, it adds annually a layer of

wood : s, s, J , \ ., ,, ,. , "

spring wood; wood outside the preceding one, between

/, fail wood.' that and the bark (Fig. 379). This is

exogenous growth, or outside growing, as the name denotes.

521. Some new bark is formed every year, as well as

new wood, the former inside, as the latter is outside of

that of the year preceding.

MINUTE ANATOMY OF FLOWERING PLANTS 225

522. The Bark of a year-old stem consists of three parts,
more or less distinct, namely, — beginning next the
wood, —

1. The liber, or fibrous bark, the inner bark (Fig. 380,
1). This contains the bast fibers, the walls of which are
commonly lignified, and other ele-
ments, as already briefly described.

In woody stems, whenever a new 3
layer of wood is formed, some new
liber or inner bark is also formed
outside of it.

2. The green or middle Bark (Fig.
380, 2). This consists mainly of
rounded parenchyma cells, contain-
ing chlorophyll granules like the
cells of the leaf. The green bark
of twigs functions as assimilating
tissue in the same way as the leaf
parenchyma.

3. The corky layer or outer bark
(Fig. 380, 3), consisting of empty,
angular cells, closely coherent, the
walls of which are suberized, or
chemically altered in such a man-
ner as to be impermeable to water.

TJ_ • ji • i • i • j_i 380. Cross section through

It IS this Which gives to the Stems bark into the wood of

or twigs of shrubs and trees the a Lilac twig: e, epi-

aspect and the color peculiar to
each, — light gray in the Ash, pur-
ple in the Red Maple, red in several
Dogwoods, etc.

Sometimes the corky layer grows
and forms new layers inside the old for years, as in the
Cork Oak, which produces the cork of commerce, the
Sweet Gum Tree, and the White and the Paper Birch.
This growth proceeds from a formative layer, called the
cork cambium, lying on the inner boundary of the cork.
The old cork, being dead and therefore incapable of

OUT. OF EOT. — 15

dermis; c, cork; p,
collenchyma; g, green
rounded cells ; /, bast
fibers ; ca, cambium ;
w, wood; 1, 2, 3, in-
ner, middle, and outer-
bark.

226 MINUTE ANATOMY OF FLOWERING PLANTS

growth, is stretched, and finally rent by the continual
enlargement of the wood within; it is weathered and
worn, and thrown off in fragments, in some trees rapidly,
in others more slowly, so that the bark of old trunks
may acquire great thickness. Similarly in Honeysuckles
and Grapevines, the layers of the inner bark or liber
loosen and die, and come off in strips when only a year
or two old.

523. The epidermis, consisting of a single layer of close-
fitting, tabular cells, with outer walls much thickened and
coated with a layer of matter impermeable by water, per-
sists only for the first year or two. It is found, therefore,
in the case of stems, only on herbaceous plants, and on the
twigs and young parts of perennials, as a rule.

ANATOMY OF LEAVES

524. In the framework of leaves — ribs, veins, and vein-
lets — all the usual elements of vascular tissue are repre-
sented. The midrib, for instance, possesses a typical
fibre-vascular bundle, with phloem and xylem portions,
derived from the branching of the fibro-vascular system
of the stem. In the veinlets, however, the conducting
elements become reduced to simple series of hollow cells
and fibers. The woody framework serves not only to
strengthen the leaves, but also to bring in sap and to
distribute it throughout every part.

525. The living cells of the leaf, making up the green
pulp, are of various forms, usually loosely arranged, so as
to give copious intercellular spaces or air passages commu-
nicating throughout the whole interior (Figs. 381, 382).
The green color is given by the chlorophyll grains, seen
through the transparent walls of the cells and through the
translucent epidermis of the leaf.

In ordinary leaves, having an upper and under surface,
the green cells form two distinct strata, of different arrange-
ment. Those of the upper stratum are oblong or cylindri-
cal, and stand endwise to the surface of the leaf, usually

MINUTE ANATOMY OF FLOWERING PLANTS 22?

rather close together, leaving scanty vacant spaces ; those
of the lower are commonly irregular in shape, most of them
with their long diameter parallel to the face of the leaf,
and are very loosely arranged, leaving many and wide air
chambers. The green color of the lower is therefore

381. Magnified section of a leaf of White Lily, to exhibit the cellular struc-
ture, both of upper and lower stratum, the air passages of the lower,
and the epidermis in section; also a little of the lower face, with
some of its stomates.

diluted, and paler than that of the upper face of the leaf.
The upper part of the leaf is so constructed as to bear the
direct action of the sunshine; the lower so as to afford
freer circulation of air, and to facilitate the escape of mois-
ture. It communicates more freely than the upper with
the external air by means of pores in the epidermis.

526. The upper cylindrical cells are known as the pali-
sade cells. The lower, irregular, or sometimes slightly,
branching cells make up the spongy parenchyma, so called.

527. The epidermis is usually composed of a single layer
of more or less flattened cells, devoid of chlorophyll, and
mostly of irregular outline (Figs. 382, 383).

The walls of the epidermis are commonly thickened
externally by the addition of a layer of a waterproof sub-
stance. This layer is easily distinguished in the cross
section from the original exterior walls of the cells. It
is termed the cuticle. The several walls of each epider-
mal cell are impregnated with the same waxy or fatty

228 MINUTE ANATOMY OF FLOWERING PLANTS

matters which give the cuticle its resistance to water.

These walls are said to be cutinized.

528. The pores of the epidermis are called stomates or

stomata (i.e. mouths). Each stomate (^stoma) is guarded,

so to speak, by two cells of
peculiar conformation, called
guard cells (Figs. 382, 383, g).

g 8

382. Section of a leaf : e, epidermis; 383. Surface view of e idermis of

c,assimilatingcellscontain- the leaf . e> ordinary epider.

ing chlorophyll granules; mal cell; gy guard cell. -

p, intercellular passages; TSCHIRCH.
g, g, guard cells of stomate.

The guard cells, unlike the rest of the epidermis, contain
chlorophyll. They are so constructed that as the quantity
of water they contain varies the slit
between them is either opened wider,
or narrowed, — or, it may be, quite
closed. The guard cells are closed
together when flaccid on account of
the wilting of the leaf.

Stomates are found on most of the
green surfaces of the plant, but most
abundantly on the leaf. Here they
are generally more numerous on the
under side.

529. Trichomes are outgrowths of
the epidermis, consisting in the sim-
plest cases of single cells, but in many

384. Trichomes (h, h) of J

the leaf. — SACHS, cases of several cells in a more or less

BEIEF OUTLINE OF VEGETABLE PHYSIOLOGY 229

complicated arrangement. Several different kinds may
spring even from the same leaf (Fig. 384). Stinging
hairs (Fig. 360) and hairs with bitter secretions are an
important means of defense to many plants.

530. The anatomy of the root resembles, in a general
way, that of the stem. There is a central conducting
and strengthening strand of wood. In the older roots of
perennial exogenous plants this becomes a cylinder of
wood surrounded by a cambium zone, from which wood
is formed annually just as in the stem. The cortex of
the older parts of many roots is bounded externally by
several layers of cork cells, preventing the passage of
water into or out of the root. Formation of new tissue
for growth in length takes place at the growing point
(Fig. 28, g) under the root cap. New lateral roots
originate from cells lying near the wood, and push their
way through the cortex to the surface. They arise in
longitudinal rows.

XVIII. A BRIEF OUTLINE OP VEGETABLE
PHYSIOLOGY1

531. Vegetable physiology deals with the processes by which the
life of plants is carried on. Such processes are the absorption of
materials ; the transfer of raw and elaborated food matters from one
part of the plant body to another ; the conversion of inorganic matters
into organic substance ; the storage of elaborated products ; respira-
tion and the consumption of food for the production' of vital energy ;
growth ; and movement.

532. Constituents of the plant body. — The chief constituent, as
concerns quantity, is water, since even in woody parts the solid por-
tions amount at most only to fifty per cent of the total weight, and
in herbaceous parts to but twenty or thirty per cent.

533. We may distinguish three ways in which water is useful to
the plant: (1) it furnishes part of the raw material out of which

1 A number of experiments in vegetable physiology and some informa-
tion as to the general function of plants have already been given in this
book. The present chapter is added for the purpose of gathering together
in coherent form the results of these previous studies. As discussions of
the most important matters will be held in the class room, following
experimentation in the laboratory, the chapter may be used for reference
rather than for ordinary assignment in lessons.

230 BRIEF OUTLINE OF VEGETABLE PHYSIOLOGY

substances like starch and cellulose are formed ; (2) it is the solvent
in which all the vital chemical changes, like assimilation, are carried
on ; (3) its presence is an important factor in preserving the rigidity
of the plant body. The first of these offices has been touched upon
in the brief statement of assimilation made in the chapter on the
Leaf. The second need not be further dwelt upon. The third mav
now be more fully considered, since it concerns a first essential to the
existence of the plant, namely : —

534. The stability of the plant body. — By stability is meant the
power of the plant to keep its form, — the power, if it is an erect
plant, of keeping itself erect and outspread in proper position in all
its parts. It is a matter of common observation that plants suffering
from drought wilt and droop, sometimes even fall flat to the ground.
Wilted plants have partly or wholly lost their stability.

535. Stability is secured in part by the properties of the tissues
themselves ; the thick-walled, strengthening fibers are so disposed in
the stem as to secure the greatest rigidity. But in herbaceous and
succulent organs, firmness depends oftentimes as much, or more, upon
the condition of the living cells in regard to their supply of water.
When one of these cells has a full supply of water, the expansive sub-
stances held in solution by the cell sap (for example, sugar and acids)
are enabled to distend the cell to its full limits.1 The cell is then said
to be turgid.

In such a condition it resists the distorting stresses brought upon it
by the pulls of neighboring cells. And when all the cells of a tissue
are fully turgid, they resist, collectively, all distorting stresses. That
member of the plant body which is well watered, therefore, retains its
form and proper attitude.

536. The turgidity of cellular tissues gives rise to tensions between
different masses of tissue lying side by side in the plant body. A good
illustration of these tissue tensions is furnished by the succulent stalk
of a Rhubarb leaf. Let a portion of the fresh stalk be cut squarely

1 Dissolved substances have an expansive force, comparable in a gen-
eral way to the expansive force of gases. Sugar dissolved in cell sap presses
against the protoplasm that holds it in, just as hydrogen presses against
the walls of a balloon. The cell, in such a case, has a constant tendency
to expand. If water is at hand that can come in to occupy the additional
space to be made by expansion, then the cell expands until the outward
push of the solutions equals the resistance of the cell wall to being stretched.
The entrance of water, therefore, is the result of the expansive tendency of
the cell sap solutions. Water does not cause the swelling, only allows it.
Absorption of water by such action is called osmotic absorption.

For a clear statement of the theory of osmotic pressure, see Ostwald's
"Solutions," Eng. 4,rans. The theory, however, has received important
additions since the work named was published.

BRIEF OUTLINE OF VEGETABLE PHYSIOLOGY 231

off at the ends, and its length be exactly measured. Let the stringy
external sheath then be stripped off, and at once let both the central
cellular column and one or two of the external strips be measured. It
will be found that the pith has considerably lengthened, while the
fibrous strips are somewhat shorter than the piece of leaf stalk origi-
nally measured. Before separation, then, the pith must have been
compressed, the external tissues stretched. Tissue tensions add rigid-
ity to stems, petioles, etc. Variations in tissue tensions give rise to
curvatures of organs, such as the bending of the stem toward the
light.

537. Solid components of the plant body. — By solid components
is meant here all the matter left when water has been entirely driven
off by heat at somewhat above the boiling temperature of water.
This includes cell walls, dried living substance (protoplasm), starch,
sugar, and other formed matters in the cells, and small amounts of
mineral matters ordinarily held in solution in the juices of the plant
or deposited in the tissues in crystalline form.

538. Amongst these, the organic constituents are composed almost
solely of the four chemical elements — carbon, hydrogen, oxygen, and
nitrogen. Organic matters belonging to the class carbohydrates — as
sugar, starch, cellulose — and fats, include in their composition only
the first three of these elements; they lack nitrogen. Nitrogenous
organic compounds — as those that make up protoplasm — contain all
the four elements named, and in addition, usually a small amount of
sulphur and phosphorus.

539. The nature of the mineral matters held in the plant is found
when the dried plant has been burned and the ash has been chemically
analyzed. In burning, carbon and hydrogen are united with oxygen
from the atmosphere and pass away in a gaseous form. Organic com-
ponents of the plant body are therefore broken up. The ash that is left
is entirely inorganic. In such ash, from various plants, has been
found a large part of all the known chemical elements, including even
the rarer metals. Most of these elements occur accidentally, being
absorbed with soil water. But certain of the chemical elements are
absolutely necessary to the healthy growth of every green plant. These
are six in number; viz., sulphur, phosphorus, potassium, calcium,
magnesium, iron.

540. Source of the elements. — Thus there are, including the
four elements before named as chiefly making up organic substance,
in all ten elements which must be furnished the growing plant. Each
of these is received by the plant in a combined form. Carbon comes
from the atmosphere, combined with oxygen, as carbonic acid gas.
All the other needful substances come from the soil. Hydrogen and
oxygen come together, as water. Nitrogen is brought in under the
form of a soluble nitrate, or one of the ammonia salts, in the absorbed

232 BRIEF OUTLINE OF VEGETABLE PHYSIOLOGY

soil water. Sulphur, phosphorus, potassium, etc., are obtained in the
form of salts from the soil.

541. As regards the number of elements supplied, the root is
therefore the chief organ of absorption ; the leaf absorbs only carbonic
acid gas. l Absorption at the root may be considered under two
heads : absorption of water, and absorption of nutrient salts.

542. Absorption of water. — The manner in which the root sends
out root hairs, which become applied to the soil particles for the
purpose of absorption, has been described in an earlier chapter. What
force acts to draw water into the root hairs is not known with
certainty. It is believed by most physiologists to be the osmotic force
of the root hair cells (see page 230, footnote).

543. Aside from the scarcity or abundance of water in the soil,
the chief external circumstance affecting the rate of absorption is that
of temperature. Warmth increases absorptive activity, while cold
decreases, or even prohibits it. Sachs found that at a temperature of
from 38° to 41° F. absorption of water ceased, in spite of the fact
that the soil was saturated.

544. Absorption of nutrient salts. — The salts needed for perfect
nutrition may be swept into the plant in the absorption current. In
case the salts are bound by adhesive force to the soil particles, they
must first be loosened by the action of acids excreted by the root
hairs. When they exist in free solution in the soil water, or have
been brought into this condition by the secretions, they may pass into
the root hair quite independently of any current, by the process
known as diffusion. The dissolved particles of the salt wander
throughout the body of water in which they find themselves, through
the root-hair walls, and so on through the tissues of the plant body,
unless they meet membranes possessing pores too minute to allow
of their entrance. Those salts that are most used by the active cells
and are therefore scarcest in the general sap of the plant, diffuse
from the soil into the plant more rapidly than those that are little
used and that therefore tend to become concentrated in the sap.
Each kind of plant, according to its nature, by internally appropri-
ating more or less of this or that salt, thus controls the absorp-
tion of the different soil salts at the root. Some kinds of plants
tend to exhaust one constituent of the soil, some kinds another con-
stituent. Plants are therefore said to show selective absorption of
nutrient salts.

545. The transfer of water through the root and stem to the leaf
is accomplished by a number of forces. In the case of deciduous trees

1 Like all other parts of the plant, the leaf absorbs oxygen for respira-
tion. But we are here considering the raw materials from which food is
formed.

BRIEF OUTLINE OF VEGETABLE PHYSIOLOGY 233

in spring, before the leaves appear, the sap may press up into the
trunk and on toward the buds with considerable force. Or again, if
in an herbaceous plant evaporation of water from the leaves is checked,
the sap may press into the leaves so strongly that drops exude from
the leaf tips or from the marginal teeth — usually in those cases from
definite water pores. The drops seen at the tips of grass blades after
a warm, damp night, are of this sort. In all these cases the rise of
water in the plant is due to what is termed root pressure.

546. The phenomenon of root pressure may be observed when the
stem of a plant, such as the Sunflower, is cut off near the ground.
After a time water (sap) begins to run from the cut. If now an effort
is made to stop the outflow, a considerable force must be used before
the pressure of the sap — the so-called root pressure — is neutralized.
Hales, the earliest of exact physiological botanists, who, about 1731,
made some measurements of the root pressure of the Grapevine, found
it to be equal to the downward pressure of a column of water forty-
three feet high. A pressure of sap, equal to the pressure of eighty-five
feet of water, has been observed in a Birch. Root pressure falls to
nothing, however, when the loss of water at the leaf is going on with
any rapidity. Root pressure, therefore, cannot continuously supply
the leaves with the water they need.

547. The ascent of water in the stem has been the subject of many
investigations and much discussion. The path followed by the cur-
rent is the cavities of the ducts and fibers of the wood. The force
working to raise the water in these cavities is not, to any considerable
extent, capillarity, as was once supposed. The ultimate cause is
doubtless the evaporation of water from the leaves ; but how this
works to raise water through the stem is still a disputed question.

548. Evaporation of water from the shoot; transpiration. — Land
plants are perpetually giving off water vapor from their parts above
ground, in greater or smaller quantities according to external circum-
stances or internal peculiarities. Even in winter the twigs of trees
transpire a little. In desert plants transpiration is reduced to almost
nothing in the dry season.

549. Leaves are the especial organs of transpiration in ordinary
cases. Though their surfaces are covered with an epidermis that pre-
vents too great loss of water, the pores or stomates allow a regulated
escape of vapor which is of great importance to the plant. The inter-
cellular passages of the spongy tissue furnish communication between
the leaf cells, saturated with water, and the atmosphere without. As
long as the stomates remain open, therefore, vapor given off by the
moist walls of the cells escapes from the leaf. When the stomates
close from any cause, the exit of vapor is checked. Even then, how-
ever, some evaporation takes place through the cuticle, which is
imperfectly waterproof in most plants.

234 BEIEF OUTLINE OF VEGETABLE PHYSIOLOGY

550. The amount of water lost by transpiration varies very greatly
with the character of the plant and the conditions under which it is
placed. The early experimenter Hales, by weighing, determined the
loss from a potted Sunflower plant, three feet and a half high, to be
on the average one pound four ounces every twelve hours. From this
some idea may be formed of the very large weight of water transpired
by a full-grown tree on a warm day. It has been estimated that the
amount of aqueous vapor given off by an acre of Beech forest between
June 1 and December 1 is between 1000 and 1500 tons.

551. The object of the transpiratory activity is the acquirement of
nutrient salts from the soil and their transportation to the leaves,
where they are left by the evaporation of the water.

552. The rate of transpiration is regulated in part by the action of
the stomates. When the guard cells of a stomate are turgid the slit
between them stands wide open. If the guard cells become flaccid,
either through undue wilting of the leaf or from any other cause, the
stomatal opening becomes narrowed or closed. The guard cells are
sensitive to the influence of light; in bright sunshine the stomates
stand wider open than in diffused light, and they close on dark, stormy
days even in summer. Artificial darkness closes them — more quickly
in the afternoon than in the morning. At night the majority of plants
close their stomates, but not so as to prohibit all transpiration. The
stomatal cells are sensitive also to dryness. A draught of dry air
causes them to close, eveir though the leaves show no signs of
wilting.

553. Aside from stomatic regulation, the rate of transpiration for
any given plant depends largely upon the external circumstances of
heat, light, dampness, or dryness of the atmosphere and supply of
water at the root. Heat furnishes the energy for all evaporation ;
consequently, rise of temperature in the leaf accelerates transpiration.
Light also has a stimulating effect. Dampness of the air around the
leaf, on the contrary, retards transpiration, just as it checks ordinary
evaporation. And of course dryness of the soil acts finally to reduce
the amount of transpiration.

554. Assimilation of carbon. — Carbon is the most important of the
elements going to make up the solid parts of the plant body. How
great a proportion of the framework it forms is seen when wood is
subjected to great heat in the absence of air. Everything volatile
is then driven off; but the form remains, even the microscopic
details of structure being preserved by the carbon of the charcoal.
Carbon constitutes, by weight, about one-half of the dry substance of
ordinary plants.

555. Carbon dioxide, the source of this important element, enters
the leaf through the stomates, passes along the intercellular spaces
of the spongy tissue, becomes dissolved in the water that saturates

BRIEF OUTLINE OF VEGETABLE PHYSIOLOGY 235

the walls of the cells, and then diffuses throughout the green tissue.
Its goal is the chlorophyll granules. 1 Here, in sunlight, its particles
are torn apart, and the carbon atoms are combined with the atoms of
hydrogen and oxygen derived from the decomposition of water, to
form a carbohydrate. This carbohydrate, if not starch, is shortly
turned to starch as a rule, appearing as minute granules in the chloro-
plastids sometimes within five minutes after exposure of the plant to
light. These granules increase in size while assimilation continues;
but when assimilation ceases, as at night, the starch begins to be
dissolved, and is finally conveyed away in the form of a soluble
carbohydrate. Assimilation of carbon by aid of light is termed photo-
synthetic assimilation.

556. The conditions that must be fulfilled before assimilation will
take place are these : Carbonic acid gas must be present in the atmos-
phere, there must be light and a certain amount of heat, and the
chloroplastids must contain chlorophyll.

557. The atmosphere normally contains about .04 of one per cent
of carbonic acid gas, by weight. Increasing this proportion hastens
the rate of assimilation slightly; but if the gas is increased two
hundred fold, the formation of starch becomes only four or five times
greater. Ordinary variations in the amount of carbon dioxide would,
therefore, not perceptibly aid assimilation.

558. Light furnishes the energy of assimilation. Of the different
components of white light, the red, orange, and yellow rays are the
most effective.

559. Liberation of oxygen. — In the act of assimilation, when
carbon is taken into the material of the plant, the oxygen of the
carbon dioxide is given off. In the case of water plants this may be
seen. Let a cut branch of such a plant be exposed to light under
water. Bubbles of oxygen will be seen escaping from the cut end.
The rapidity with which these bubbles are given off may be taken as
a convenient measure of the activity of assimilation in the given plant
under the given circumstances. If, for example, the plant is exposed
to one sort or one intensity of light for a period, and the number of
bubbles rising from it per minute is found, the conditions as to light
may then be varied, and the number of bubbles per minute ascer-
tained anew ; compared with the former result, the later count will
show whether the assimilative activity of the plant is greater, or less,
under the new conditions. 2

560. The action by which substances like starch and protein gran-
ules, insoluble in the sap, are converted into soluble compounds is
digestion. In digestion, starch is changed to sugar. In the latter

1 See Fig. 382, Chap. XVII.

2 See Goodale, " Physiological Botany," p. 305, for more explicit direc-
tions. The experiments are most interesting.

236 BRIEF OUTLINE OF VEGETABLE PHYSIOLOGY

form the newly made plant food in the cells of the leaf can pass out
through the petiole to the stem, and travel to points of active growth,
or to storage cells. Digestion is accomplished by means of the so-
called ferments, or enzymes, of which diastase is a common example.
The enzymes are not consumed in the process; their mere presence
seems to be enough to induce digestion. Diastase is extracted from
germinating seeds (e.g. barley). If a solution is applied to a bit of
starch on a glass slide under the microscope, the disintegration of the
starch granules may be observed.1

561. The formation of albuminous substances. — Assimilation is
only the first step toward the formation of living substance, or proto-
plasm. The albuminous substances which compose protoplasm differ
from the carbohydrates produced by assimilation, in containing a con-
siderable proportion of nitrogen often with some sulphur and phos-
phorus. It is in the formation of these nitrogenous, or albuminous,
matters that the nutrient mineral salts are put to use. Where this
final step in the production of proteid matter is taken is not definitely
known. It may be that it is in the green tissue of the leaf, or it may
be at all growing points.

562. The transfer of organic substance, whether of carbohydrates
or of nitrogenous compounds, is largely accomplished by the diffusion
of solutions of these substances. Albuminous matters not diffusible,
as well as solutions, are carried by the so-called sieve tubes in the bark,
when the transfer takes place in a dicotyledonous stern.2 This is the
route by which nourishment designed for the root system is brought
from the leaves. If a ring of bark is removed from the trunk of a
tree, the bark above the cut grows and swells out, because of the
arrest and accumulation of nourishment in transit toward the root.

563. Storage. — Such a part of the elaborated food as is not at once
needed for growth passes into the store of reserve material.

564. Living cells perform the office of storage. In stems and roots
these cells would be those of the bark, the medullary rays, and the
living pith. In tubers and other special organs of storage, the storage
cells are particularly numerous and often of large size.

565. Carbohydrates are stored most commonly in the form of
starch, but also in the form of sugar. Reserve cellulose is another
storage condition of the carbohydrates ; in this case, the walls of the
storage cells become greatly thickened by the depositions. Food may
be stored in the form of oil and fat ; also in protein granules and
crystals.

566. Respiration. — All plants, like all animals, take in oxygen.
As plants are less active than animals, they need less oxygen ; and

1 See Enzymes, Strasburger, p. 203.

2 In the phloem of the fibrovascular bundles. For sieve tubes see
Goodale, p. 91.

BRIEF OUTLINE OF VEGETABLE PHYSIOLOGY 237

they have no special organs of respiration comparable to the lungs of
animals. Yet special contrivances exist which facilitate the passage
of oxygen from the atmosphere to every part of the plant. Inter-
cellular passages penetrating the tissues communicate externally with
the stomates, and with larger pores in the bark, called lenticels. Len-
ticels are slight outgrowths of the cork, in which the cells lie loosely
upon one another, and over which the epidermis is broken away. They
may be seen upon almost any twig. The intercellular spaces of water
plants are particularly large in order to convey to submerged parts the
oxygen taken in through the stomates of the leaf ; or at least in order
to retain the oxygen given off by assimilating cells. Oxygen also
travels through the tissues dissolved in the liquids of the cells,
by ordinary diffusion. In solution it enters the ceil where it is
needed.

567. All living cells require oxygen. The effect of excluding oxy-
gen may best be seen in those cells1 in which the protoplasm streams,
— that is, circulates in the cell more or less rapidly (Fig. 360). If
arrangements are made to supply some other gas — as carbon di-
oxide— to the cell while the circulation of the protoplasm is being
watched under the microscope, the movement is seen to lessen within
a few seconds after oxygen is driven off, and shortly to stop altogether.
If, after not too long a time, oxygen is once more admitted, the stream-
ing of the protoplasm begins again. But if the suspense is too long,
the protoplasm will be found to be dead.

568. In respiration, the oxygen absorbed by the protoplasm slowly
oxidizes it. There is, in other words, a slow burning. Of course the
protoplasm is slowly destroyed, and has to be renewed through nutri-
tion. The result of oxidation, however, is the generation of heat and
other forms of energy, which enable the cells to do their work. The
process is essentially like that by which energy is " set free " in the
burning of coal for the driving of an engine. All engines, whether
organic or inorganic, consume fuel.

569. By the oxidizing process carbonic acid gas is formed. This
gas is easy to detect experimentally,2 and when given off by the plant
furnishes the best evidence that respiration is going on. Plants respire
continuously, as long as they live. But in daytime respiration is not
easy to show, since the carbon dioxide given up by the respiring cells
is taken in by the assimilatory tissues. At night or in darkness, on
the other hand, respiration is clearly indicated by the escape of the
telltale gas.

1 Such as the new root hairs of some aquatics, the cells of the leaf of
the fresh-water Eelgrass, and cells of the alga called Chara, and young
trichomes of many plants.

2 See Experiment 12, p. 66.

238 BRIEF OUTLINE OF VEGETABLE PHYSIOLOGY

570. " The contrast between assimilation and respiration l is very
marked: one is substantially the opposite of the other. The follow-
ing tabular view displays the essential differences between them : —

CARBON ASSIMILATION

Takes place only in cells contain-
ing chlorophyll.

Requires light.

Carbonic acid absorbed, oxygen
set free.

Carbohydrates formed.

[Energy is stored.]

The plant gains in dry weight.

RESPIRATION
Takes place in all active cells.

Can proceed in darkness.
Oxygen absorbed, carbonic acid

set free.

Carbohydrates consumed.
[Energy is brought into use.]
The plant loses dry weight."

571. Resting periods. — The dormant condition of seeds and buds
has already been described. In the periods of suspended animation
respiration is reduced to its lowest limits. Some seeds may be kept
for years without loss of vitality. We must suppose that all the while
the protoplasm is to a very slight extent active, and that feeble respi-
ration is going on.

572. Growth. — Were we to trace the inner and outer changes that
lead to the formation of a complete leaf, — taking the leaf as an
example of the organs in general, — we should find the following
course of events. First a slight prominence is to be seen close to the
tip of the stem. This elevation is caused by the rapid multiplication
of the cells at the point where the new leaf is to appear. All the cells
at this point are capable of dividing; the tissue is said to be embry-
onic. Of course division is accompanied by the increase in size of the
cells produced. As the protuberance grows, it soon shows some signs
of external shaping. Lobes appear, if the mature leaf is to be lobed
or compound. But the whole mass of cells remains embryonic in
character, and the cells are still relatively small, until the new organ
has been formed and shaped into something like a miniature of its
mature condition. Then another phase of growth sets in. Few new
cells, or none, are made, but all the cells begin to elongate and enlarge.
As a result the whole leaf expands, and it may do so very rapidly.
This phase — the phase of elongation in growth — is seen in the swift
expansion of foliage from winter buds in spring. Finally, as full size
is being attained, a third phase appears. The cells of the leaf indi-
vidually take on their characteristic forms, by final changes in shape
and in the nature of the cell walls.

573. Three phases are thus to be made out in the growth of any
organ : (1) the formative, or embryonic phase ; (2) the phase of elonga-
tion ; and (3) the phase of internal development. But it is not to be

1 From Goodale's "Physiological Botany," p. 356,

BRIEF OUTLINE OF VEGETABLE PHYSIOLOGY 239

supposed that one phase ceases altogether before another begins. We
distinguish the phases in a general way.

574. Grand period of growth. — If the elongation of a short section
of a very young growing part, as for instance a section very near the
tip of a growing root, is marked off and measured from time to time
through several days, it will be found that at first the rate of elon-
gation in the given section is low, then gradually increases to a
grand maximum, and finally declines until growth disappears. The
whole time of growth of an organ, characterized by such a general
rise and ultimate fall of the rate of growth, is termed the grand period
of growth. Within this there are minor variations, chief among which
are the daily fluctuations.

575. Daily fluctuations. — If the length of a growing stem were to
be measured at frequent intervals during the twenty-four hours, it
would be found that elongation does not go on uniformly. It is
periodic, being less rapid in the daytime than at night. The diur-
nal minimum is usually reached sometime in. the afternoon; the
maximum, commonly after midnight. This is due to the nature of
the plants themselves, not directly to the working of external causes.
For if a well-nourished growing plant is kept for .several days in the
dark, the periodic changes in growth rate still continue. All this has,
however, been induced in plant nature, in the past, by alternation of
day and night.

576. The chief external influences affecting growth are temperature
and light.

577. Temperature. — Favorable temperatures vary greatly, accord-
ing to the plant in question. Thus, in northern latitudes and on high
mountains certain species are found growing vigorously in early spring,
even through a covering of snow, at a temperature very slightly above
freezing ; while most plants of warm climates altogether cease to grow
at a temperature several degrees higher. For many common plants
the most favorable (optimum) temperature is between 70° and 85° F.

578. Light — In general, light acts against growth. Too great
light may quite prevent growth. In nature, accordingly, the rate of
elongation increases during the night, especially after midnight, and
decreases during most of the day.

579. Movement. — Transfer of substances in the plant, as of water
or food substances, and circulation of living protoplasm in cells have
been mentioned. In the descriptive chapters movements of particular
organs have been noted in detail, as the movements of roots of seed-
lings, stems, leaves, tendrils, tentacles, and floral organs. These activi-
ties have now to be briefly considered together.

580. Most movements of bending are due to unequal growth on
different sides of the organs in question. Curvatures of mature
organs, like bending of pulvini of leaves, and sudden movements like

240 BRIEF OUTLINE OF VEGETABLE PHYSIOLOGY

those of tentacles, some stamens, and leaves of the Sensitive Plant are
due to alterations in tissue tensions independent of growth.

581. Movements may be due : (1) to internal causes, or (2) to ex-
ternal influences. The first are spontaneous, the second induced.

582. Spontaneous growth movements. — Darwin showed that the
tips of growing parts of plants — stems, leaves, roots — perpetually
move in irregular elliptical curves. Since the motion is one of bow-
ing toward all points of the compass in turn, he called it circurnnutation.

583. Induced growth movements. — These are much the more strik-
ing. The exciting causes {stimuli) are chiefly : gravity, light, mois-
ture, mechanical contact, and variations of light and heat.

584. Gravity. — It has been observed from actual experiment in
the laboratory that roots of seedlings turn toward the center of the
earth, while the plumule turns toward the zenith. All turnings under
influence of gravitative force are manifestations of Geotropism. The
root is said to be positively, the shoot negatively, geotropic.

585. Light. — Plants turn, as we say, instinctively toward the light.
If one could observe the root, however, it would be found to turn away
from light. These actions are instances of Heliotropism. The shoot
is, in general, positively heliotropic, the root negatively hdiotropic.

586. Moisture. — The root seeking moisture displays Hydrotropiwn,

587. Contact. — When the revolving end of a tendril or a twining
stem strikes an object of support, growth on the touched side is re-
tarded. The effect of this stimulus is, therefore, to make the tendril
or stem encircle the support.

588. Variations of light and heat modify the rate of growth on oppo-
site sides of leaves. If the upper surface of blade and petiole grows
faster than the lower, the whole leaf is depressed ; if the lower side
grows faster, the leaf is raised. Movements of this sort are especially
noticeable in floral leaves. In warm sunshine, for example, the leaves
of the Dandelion head unfold for the visits of insects; but when, in
the afternoon, the light and warmth fall off somewhat, the bracts and
corollas of the inflorescence close up tightly. In other cases the effects
of illumination are just the reverse, for the flowers open at night,
when the nightfliers that pollinate them are abroad.

589. Movements due to change of turgidity. — These have been
described in the chapter on the leaf (sleep movements, behavior of
the Sensitive Plant, action of insectivorous leaves). Such movements,
due to changes of turgidity (apart from growth), are confined to leaves
(vegetative and floral) ; and they result from the sudden escape of
water from the swollen tissues of the pulvinus or other motile organ,
into the internal ducts or intercellular spaces.

590. Irritability. — All the movements and changes of movement
referred to in §§ 583~589, occasioned by external exciting causes
(stimuli), are manifestations of the irritability inherent in protoplasm.

APPENDIX

I. PHANEROGAMIC LABORATORY STUDIES1

Laboratory outfit. — Each pupil needs a simple microscope. This
may be an inexpensive lens, or combination of lenses, mounted over
a glass stage, and supplied with light from below by a mirror. Dis-
secting microscopes of this sort, of various degrees of excellence, are
offered by dealers. (Bausch & Lomb, manufacturers, Rochester, N.Y. ;
Queen & Co., manufacturers, Philadelphia ; Franklin Educational Com-
pany, and L. E. Knott Apparatus Company, Boston; Cambridge
Botanical Supply Company, Cambridge, Mass. ; and others.) Those
forms in which the lens is easily removed from* the holder, so as to be
used as a hand lens, have a decided advantage in examining material
that is not readily manipulated on the stage. Lenses that screw into
the holder, or frame, are not easily got out for hand use. The
best that the school can afford in the way of a dissecting microscope
is not too good. On the other hand, even a cheap lens, unmounted,
will help one to learn much.

The outfit for each pupil comprises also a pair of dissecting needles
(which may be homemade, from No. 10 cambric needles and pine
handles) ; a well-sharpened knife or scalpel; and a pair of steel forceps
with slender, roughened points. At hand should be a glass of water
and a small bottle of iodine solution (see Exercise II., 2, p. 246). The
laboratory should have glass slides and cover glasses, and one or two
sharp razors, with means of keeping the latter in good cutting condition.

The experiments call for various utensils which need not be men-
tioned here.

Notebooks should be of good size (about 8x 10 inches), so bound as
to lie flat when open on the table, and made of a good quality of
paper. J. H. Schaffner, of Ohio State University (Columbus), has
described (Jour. Appl. Micros., June, 1900) what appears to be a con-
venient notebook. Covers, sheets for notes, and sheets for drawings
are separate, of the same size, and punched alike. The whole is held
together by shoestrings. Dr. Ganong also has designed a notebook.
It may be had of the Cambridge Botanical Supply Company. The
paper on which drawings are to be made should be a rag paper, at

i For Cryptogamic studies, see II., p. 258. Additional implements are
there described.

242 APPENDIX

least as good as the grade* known as ledger 17x22 — 32. The J. L.
Hammett Company (educational supply), Boston, can furnish books
of this paper, 8x10, 100 pages, with flexible covers, at 40 cents each,
more or less, if ordered in lots. I mention this to give some notion
of the probable cost of such books.

The Laboratory Studies have been written with a view to the use
of the dissecting microscope, or hand lens, solely. But it is evident
that one or two compound microscopes may be the means of adding
greatly to the interest of the pupils. Demonstrations of the minute
structure of the higher plants, in the course of the study of the chap-
ter on that subject, demand the compound instrument. How far one
may profitably go into the study of cellular structure depends upon
circumstances, such as the age of the pupils and the time at their dis-
posal. Personally, I believe that, especially if the teacher has used
the compound microscope much, he will be likely to underestimate
the difficulties of gaining true impressions of the structure as it exists
in three dimensions, from sections necessarily showing but one plane
at a time. .

Material. — The material for study, when not named and described
in the exercises themselves, is specified in the Appendix.

Material in stock. — Dried and pressed specimens, supplementary to
the laboratory and the text, should be mounted on stiff board of con-
venient size. Herbarium paper is too flexible and too large for hand-
ing around. The collecting instinct is strong, arid the successive
classes in botany may be called upon to build up such a collection as
is desired, in the case of schools in or near the open country. Valu-
able suggestions as to collecting and mounting illustrative material
is given by Dr. Ganong in the " Teaching Botanist."

Material not dried may be preserved in formaline (formaldehyde)
of 4%. As sold, this preservative is of 40%. It is cheaper, when
dilute, than alcohol, but the fumes are disagreeable and harmful, so
that material to be worked over should be well soaked and freed from
formaline. Alcohol is the best preservative. Fifty per cent may be
strong enough to keep material for general morphological work ; but
70% is better.

Study and drawing. — The aim of laboratory work in botany is to
win an insight into the life of plants as revealed in structure, or as
manifested by living plants under observation in the experiments.
Structure is the record of past and present natural history. It repays
thoughtful consideration. The simple drawing of the material pre-
sented is by no means an adequate method of dealing with it. It ig
common to see students draw assiduously and well, while passing on
from one subject to the next, with little or no comprehension of the
meaning of the forms. It is not unusual to see careful drawings, on
which much time has been put, which illustrate accidental, abnormal,

PHANEROGAMIC LABORATORY STUDIES 243

or inconsequential features merely. Such drawing is, of course, a
waste of time. The corrective is such study of the material as will
insure an understanding of its meaning before the drawing is begun.
When the essential points have been grasped, they are fixed in the
memory by drawing.

It is true that drawing is a help in studying objects; for the strict
heed one must pay to their forms in order to represent them exactly
leads to the discovery of facts that would otherwise escape notice.
The work of the pencil serves as a score by which we keep account of
the degree to which the eye has exhausted the details of the object.
The practice of drawing thus acts as a means of increasing the power
of attention to the manifold separable aspects of anything we wish to
examine, — that is, the analytical power. Yet, in general, in order that
the drawing may be done intelligently, a certain amount of prelimi-
nary study is necessary. This requires time ; but the time so spent
is likely to be well employed.

The attempt has been made in this book, by brief discussions pre-
ceding the exercises and by suggestive questions, to direct the pupil's
mind toward the quarter where the most essential points are to be
looked for in many cases. When questions are asked they are in-
tended to be answered, sooner or later, in the written notes of study.

For the record of laboratory work should consist of notes illustrated by
properly labeled drawings. The notes should be as full as is con-
sistent with time limitations.

In examining the material, even when the desired observations may
be fairly well made with the naked eye, pupils should be reminded to
make free use of the hand lens, or the microscope lens used as such.
Very many things are thus rendered striking and memorable that
otherwise would fail of making much impression. For example, the
delicacy of the veining of the cotyledons of Ricinus in the embryo is
far better seen by aid of the lens than with the eye alone, though the
cotyledons themselves are well above the microscopic range. And
this delicate veining suggests more forcibly than the mere external
form of the embryo how highly organized and perfected the young
plant already is.

Drawings should be in outline with little or no shading as a rule.
Every line should be distinct and definite, and represent an exact
observation made upon the object. General impressions are not
sought. Artistic " effects " are out of place in scientific drawings.
Every part should be labelled.

Experiments. — The best general manual of experiments in vege-
table physiology is probably that of Detmer ("Practical Plant Physi-
ology "), translated by Moor, published by The Macmillan Company,
New York, 1898. List price, $3.00. From this source the teacher
will gain idea^s for additions to the experiments suggested in this

244 APPENDIX

book ; and, further, will there find clear and authoritative statements
of physiological theory. The book is more than a manual of experi-
mental procedure.

Experiments sometimes fail to convince the pupil of the truth
which it is sought to illustrate. Doubts should not be put aside or
left unsatisfied when it is possible that some further test — which,
oftentimes, the pupil himself is able to suggest — may settle the ques-
tion without recourse to the statements of the authorities. A little
experimenting along an original line, that is, a line original as far as
the pupil is concerned, is often of very great value : it awakens and
stimulates the scientific spirit strongly in some cases.

Books of reference. — The following will be useful to the teacher
who wishes to extend, by reading, a scanty knowledge of botany:
"Gray's Structural Botany"; American Book Company, New York.
"Goodale's Physiological Botany"; American Book Company, New
York. Strasburger (and others), " Text-book of Botany," translated
by Porter ; The Macmillan Company, New York.

This list might, of course, be indefinitely extended.

Ganong's " The Teaching Botanist " is a manual for the teacher,
containing outlines of a course of study, pedagogical suggestions,
a list of books of reference, etc., etc.; the book is highly recom-
mended to teachers in secondary schools. Published by Macmillan,
New York.

Chapter I. — In approaching a series of studies on a given topic we
may adopt either of two courses. First, we may, without delay or
preliminary consideration, proceed to the actual study of the material,
leaving all general views aside until the laboratory work has been
completed and the summarization is to be made. Or, secondly, we
may seek to gain at least some general idea of the direction and aim
of our investigations before they are actually begun. If the teacher
chooses the former method he will pass over the questions asked at the
beginning of Chapter I., and will not necessarily emphasize the head-
ings of the several exercises. If the second method is pursued, then
the teacher will talk over the proposed work on the subject of seeds
with the class before the first exercise. It will probably be found that
amongst them the pupils already know a good deal of the natural his-
tory of seeds. And this knowledge may be made the basis of inter-
esting suggestions of study. There may be a doubt on the part of
some pupils as to whether the seed has a complete plant in it. This
may then be left for investigation. But all will doubtless admit that
the seed contains at least the starting-point of a new plant, if no
more. Assuming this, the idea of the resting state (see text on
Seeds, Chapter II.) may perhaps be hinted at. This conception,
together with the idea of the feebleness of the young plantlet at the
start as opposed to the dangers and difficulties that surround it, and

PHANEROGAMIC LABORATORY STUDIES 245

the need of rapid development, may suggest certain of the structural
features which might be expected in the seed. Questions at least may
be raised, growing out of the general conceptions already formed from
incidental observation, which will unify and illuminate the whole
series of studies on the seed.

Because I have found that this second method, that of approaching
laboratory work with an idea to work out, adds to interest and intel-
ligent appreciation, I have prefaced the chapter with several questions
which it is the aim of the exercises to answer. While the teacher
may make use of them by requiring the pupils to read them in
advance, it would be much better to draw from the class the princi-
ples of the subject, using a recitation period for the purpose, and
formulating some general scheme of work to cover the subject of
seeds and their germination. Of course under the guidance of the
teacher the resulting outline will assume the general form in which
the laboratory studies have been cast by the writer, providing Chap-
ter I. is to be used for laboratory directions to the pupil.

I would suggest that, similarly, at the beginning of each of the
chapters of laboratory studies, time enough be taken to gain an out-
look over the whole of the field about to be entered. In the prepara-
tory conferences interesting points may sometimes be introduced by
illustrative material, even in cases where closer, more detailed study
is later to be given to similar material.

Exercise I. — Castor Bean. Material from seedsmen. The Castor
Bean should not be eaten, as it contains poisonous principles which
may do harm. Let the seeds be boiled in water for five minutes for
softening, after removing a little of the testa to allow the water to
penetrate. — White Lupine. Lupinus albus, of the seedsmen. Soak 1
day in water. — Indian Corn. The flat-fruited Southern or Western
variety of Indian Corn, soaked for a day or two. For the sprouted
condition sow in soil, damp sawdust, wet sphagnum, or between sheets
of wet blotting paper, after soaking in water. Allow from a week to
10 days. If the proper stage of development is reached before the
class is ready for the study, keep the material back by placing in a
cool room (above 32° Fahr.). In estimating the time required to
grow material for class use, one should remember that, in general,
moderately high temperatures (70°-80°) accelerate, while low temper-
atures retard, germination and growth.

A teacher writes : " In the summer I boil some corn on the ear. I
carefully remove the kernels and preserve them in about 60% alcohol.
They can be used at any time."

In the directions for drawing, the numbers in parentheses indicate
magnification in diameters.

Exercise II. — i. Soak the Four-o'clock seeds 1 day. The Sun-
flower and the Peanut are suggested as having large exalbuminous

246 APPENDIX

seeds. The exalbuminous seed of the Norway Maple is interesting on
account of the very small store of food in the embryo. The " grain "
of Indian Corn, the "seeds" of Four-o'clock and Sunflower, the "pea-
nut" (including shell), and the key of the Maple are fruits. This
fact need not be brought forward, as the distinction between fruit and
seed will be made plain in the chapter on fruit. In the case of the
Peanut the question will arise, how much is a single seed ? Refer to
the like case of peas in a Pea pod. — 2. The iodine used may be pre-
pared by dissolving the crystals in alcohol, or, better, in a strong
aqueous solution of iodide of potassium, which may be had from supply
companies and probably from druggists. In testing for starch, if the
iodine is too strong, the characteristic blue tint will be obscured.
Use the reagent diluted. In the Castor Bean, Flax, and Cotton, a con-
siderable part of the food takes the form of oil. In this connection it
will be well to present facts concerning the uses of oily seeds, and of
seeds in general. Or, better, the subject may be assigned, as a whole
or in parts, to one or more pupils for special reports. In the Date, the
reserve matter is in the form of " reserve cellulose."

A test for proteid matters in seeds may be made as follows : Crush
the kernel of the given seed on a glass slide. Add a few drops of
concentrated nitric acid, and allow to act for a few minutes. If pro-
teid matter is present in quantity, a yellow or orange color appears,
which becomes more intense after the acid has been washed off and
strong ammonia water added. Contrast the color reaction in the
kernel of Sunflower seed with that in pulp of Potato, when treated
with nitric acid and ammonia ; also again when treated with iodine.
The compound microscope may be used in tests with iodine, and for
detection of oil.

Exercise III. — Experiment i. This may well be a demonstration
largely prepared by the teacher. The Beans should be ready after 2
days' soaking. The department of physics or of chemistry will sup-
ply some sort of simple hydrogen generator. One may be made of
flask, cork, and glass tubing, in the way described by elementary
chemistries. Fill the generator flask pretty well up with the acid
solution, in order to have as little air in the generator as possible.
(For the physiology of seeds and germination, see Goodale's "Physi-
ological Botany," Ch. XV.) — Experiment 2. Several pupils may work
together on such experiments as this. The gas given off by the
sprouting Corn is the same as that from the human lungs, namely
carbonic acid gas. Respiration is the same in both plants and ani-
mals, as regards the intake (oxygen) and the exhaled product (carbon
dioxide) . (See " Respiration " Goodale, p. 367.) — Experiment 3. The
thermometer used should be graduated in half degrees or finer ; or, at
least, the degree divisions should be long. Subdivisions of the spaces
may with care be estimated down to tenths by the eye. Of course, the

PHANEROGAMIC LABORATORY STUDIES 247

rise of temperature found in this experiment is the direct result of the
respiratory activity (oxidation) detected in Experiment 2. This ex-
periment also is suitable for a group of three or four students.

Exercise IV. — For pupils in groups. Of course this exercise may
be extended somewhat, at the option of the teacher — perhaps as
supplementary work for fast working and interested individuals. It
is likely that several different temperatures may be obtained in differ-
ent parts of the building. And if steam heat is used, it may be
possible to arrange matters so that minimum, maximum, and optimum
temperatures of germination can be approximately determined.

Exercise V. — For the facts and theory of the response of growing
parts to various external stimuli, see the text-books under Geotropism,
Heliotropism, etc.; Goodale, pp. 392-396, Strasburger's "Text-book of
Botany " (Porter), 1898, pp. 251 et seq.

Exercise VI. — Experiment 6. For an account of the green coloring
matter (chlorophyll) see Goodale, pp. 286 et seq. It would be inter-
esting to compare the behavior of Pine seedlings with those of com-
mon garden plants in respect to the development of chlorophyll in
darkness. It may take a month to get the pine started.

When the results of the experiments on germination are in, the
teacher will, of course, discuss the teachings of the experiments with
the class, making them points of departure for the giving of a greater
or less amount of related information. The time taken by the seeds
mentioned to germinate and come to the various desired stages of
development will depend on the temperature of the room. The fol-
lowing data will give some idea of the time required. Squash, 1 inch
deep, came up in 6 days in a warmish place. Onion, £ in. deep, was
looping up well in 9 days in warmth. White Lupine, 1^ in. deep, came
up in 7 days in a rather cool place. The plants were erect and had
spread leaves in 14 days. Pea, 1 in. deep, was coming up freely in 6
days. Morning Glory was up and had cotyledons spread in 5 days.
The seeds may be sown at intervals during two weeks or so in boxes
of soil or wet sphagnum. Several pots may be sown to show the
manner in which the young plants come out of the ground.

Supplementary Topics. — i. This will require the compound micro-
scope. Spiranthes cernua, or Maiden's Tress, is markedly poly-
embryonic. The embryos are produced without fertilization. (See
Rhodora, December, 1900.) The embryos are seen at a glance, the seed-
coats being transparent. Spiranthes cernua blooms in September and
October. Mount seeds first in alcohol. — 2. The Larch and Spruce
seeds named germinate readily in 10 or 12 days.

Chapter III. — Discuss the subject of winter buds. Some such line
of thought as the following is suggested : Why do trees like the
Maple, Elm, etc., lose their leaves in winter? (Two reasons, at least.
For xerophytic conditions in winter, see p. 65.) When does preparation

248 APPENDIX

for the new leaves, to replace the fallen ones, begin? Of what advan-
tage would it be to have the new ones ready for unfolding at the first
moment of warm spring weather ? If leaf rudiments were formed in
the fall, what arrangements would be made for their protection ? A
number of different devices for shielding the tender young leaves 01
leaf rudiments will probably come to mind. Later, in the laboratory,
it will be seen whether in nature these devices have, in effect, been
realized. A cursory examination of twigs bearing buds may be made
in class at the time of this discussion.

Exercise VII. — Illustration 3. Alternatives are the Hobblebush
(Viburnum lantanoides), V. Lantana, V. cotinifolium, V. furcatum, and
the Butternut (Juglatu cinerea).

Exercise IX. — Illustration 2. " Dutchman's Pipevine " (Aristolochia
Sipho}.

Exercise X. may be a written exercise to be handed in.

Exercise XI. — The development of buds is a very interesting subject
for study. The chief difficulty is to get buds to grow well indoors.
Many buds refuse to develop at all in the early winter, but make some
growth later in the year. If the subject is taken up in the spring,
material may be got from the trees, and cut branches may be forced.
A damp atmosphere favors development. In March I have forced
Lilac, Rose, and Am. Larch to unfold enough for study, in 8 days;
Acer platanoides (Norway Maple) — excellent example of scale de-
velopment— in about 20 days; and Buttonwood (Platanus occiden-
talis) in 14 days. The latter gives a good illustration of the stipular
nature of some bud scales, as its scales grow.

Exercise XIII. — The White or Silver Maple and the Rock or Sugar
Maple, both illustrate the superior development of the horizontal buds
and branchlets. The material should be selected for the purpose.
Sometimes the vertical shoots will be decidedly the stronger; such
examples would be interesting.

Chapter V. Exercise XIV. — The Shepherd's Purse is a common
weed, widely distributed, appearing very early in spring in yards and
by roadsides. Its root is much better for general morphology than
the fleshy roots of vegetables. Dandelion is fairly good. If root hairs
do not show well, grow a few seeds of any kind in sand, and call
especial attention to their manner of clinging to the sand, even when
the plantlet is pulled up.

Exercise XV. — The Trumpet Flower (Tecoma radicans) is best.
English Ivy (Hedera Helix) may be used.

Exercise XVI. — Sweet Potato is suggested. Carrot includes short-
ened stem. Dahlia will serve.

Supplementary Subjects. — i. Material may probably be obtained
from some greenhouse. The function of the roots is commonly mis-
understood. Vapor of water is not condensed by them, except as dew.

PHANEROGAMIC LABORATORY STUDIES 249

(See Rhodora, March and April, 1900 ; American Gardening, March 17
and 24, 1900.) — 2. The material is best preserved in alcohol. — 3. Many
herbaceous, geophilous plants show contraction. Examples must be
sought in the teacher's own locality. — 4. Grow seedlings in barely
moist sphagnum, in which saturated pieces of sponge are buried.
First sprout the seeds in water. Place them above and at one side of
the sponge or sponges, at varying distances and in different directions.
This experiment is suggested by Dr. R. H. True. — 5. With a fine
brush and India ink mark across the tip of the growing primary root
of a lately sprouted Bean, at intervals of 1 mm., for a distance of
1.5 cm. Put the seedling into a thistle tube, or glass funnel, with the
root running down into the tube. Over it place wet cotton, and cover
the top of thistle tube or funnel. Rest this apparatus in the mouth of
a jar or other receptacle containing a little water, the supporting jar
or bottle to be closed after the tube or funnel is admitted, so that the
water will not be lost by evaporation. In 24 hours, note the region
where elongation has taken place : measure the spaces. Repeat this
observation after 24 hours more. — 6. Place a young Tropseolum
plant under a bell jar, and leave for a day or two in a fairly warm
place. Drops of sap are seen on the margin of the leaf. These are
forced up by "root pressure." (See Goodale, pp. 264-268, also
Chapter XVIII. of this book.)

Chapter VII. Exercise XVIII. — Balsam (Jmpatiens) is better than
Begonia, though the latter is commoner in cultivation. Young shoots
of the Pipevine (Aristolochia SipTio) may be got at the proper season
and preserved for use. The Asparagus meant is the garden species,
the young shoots of which may be had from the market and preserved.
Indian Corn is equally good, or better. Permanently mounted cross
sections of both stems may be used. If the pupils cut their own, the
scalpels must be very sharp, and should be wet when cutting.

Exercise XIX. — This exercise may be omitted at the discretion of
the teacher. If taken, the block of wood may be of Oak, about 1£ inch
in each dimension, cut so that two faces are at right angles to the
grain, two are vertical-radial, and two vertical-tangential in the tree.
The surfaces should be accurately cut in the given planes, and
smoothly finished.

Exercise XX. — The Balsam is the best stem for this exercise ; it
may be had from greenhouses, or grown in the schoolroom from seed.
Other growing plants may be used. A solution of red ink may be
used, but is inferior to eosin (from supply companies). One ounce
eosin will color three quarts of water.

Exercise XXI. — Experiment 9. The more freely the plant used is
growing, the better for this experiment. "Nasturtium " = Tropceolum.
On geotropism see Goodale and Strasburger, as before cited. —
Experiment 10. Other growing flower scapes may be found. The

250 APPENDIX

Dandelion will answer, if young. Shepherd's Purse I have found
especially sensitive to light. Discuss geotropism and heliotropisni
with class after these experiments.

Exercise XXII. — Illustration i. Grass rhizomes will do. Iris is ex-
cellent, as it shows how the plant is propagated by lateral as well as ter-
minal buds. Useful examples of rhizomes1 will be found in any piece of
woods, under or in the leaf mold. Subterranean stems (Uvularia,
Smilacina, Polygonatum, Sanguiuaria, etc.) are particularly interesting.
Keep in alcohol, rather than dry. For comparison with rhizomes intro-
duce such a caudex as Plantain. Also subterranean things like Trillium,
Jack-in-the-pulpit (beware of tasting). — Potato tuber. Artichoke
(from seedsmen or the market) may be substituted with advantage.
New potatoes from the garden have scales ; others may not have. —
Houseleek. May be ordered several months in advance from com-
mercial growers. As an alternative, Strawberry (pressed or alco-
holic) is suggested. — Asparagus. From florists : the large decorative
species known as Asparagus Sprengeri is the best. — Crocus. From
seedsmen, at about 1 cent each. Gladiolus and Montbretia are as
good but cost about 2 cents each. — Flowering Quince. The common
Thorn, or the Honey Locust (Gleditschia) may be used. — Boston
Ivy. Or the Grape ; in which case the tendrils coil, without disks.
The Virginia Creeper (Ampelopsis quinquefolia) is figured in the text;
otherwise it would do for the present study. In all these cases the
tendril is, originally, the termination of the main stem, but is finally
turned aside by the growth of a lateral bud, which carries on the
growth of the vine. The effect is to make the tendril seem to spring
laterally, from opposite a leaf. The twisting of tendrils involves an
interesting question. (See the text.) Why the double twist, often
seen ? Hold both ends of a string fast then twist it by rolling at its
middle; is the twist of entire string single or double?

Chapter IX. Exercise XXIII. — Experiment 1 1. Tropceolum is meant.
Several pupils may work « together. Chlorophyll is extracted more
rapidly by alcohol in a test tube immersed in hot water. Then, to
swell starch grains, boil the bleached leaf in water. For carbon
assimilation, or photosynthesis, see Goodale, Ch. X., also the con-
cluding chapter in this book. For the liberation of oxygen as a
measure of assimilation, and directions for a most valuable experi-
ment (easy to perform if material is available), see Goodale, p. 305.

In connection with the given experiments on assimilation in the
leaf, the observation of starch may be made if compound microscopes
are to be had. Use starch from potato, and perhaps from the pea
also. Starch being insoluble in water, the question arises how the
food which takes the form of starch can pass from one part of the
plant to another through the membranes of the plant body. (See
Digestion, § 560.) Observe digestion with the compound microscope.

PHANEROGAMIC LABORATORY STUDIES 251

Use potato starch. Apply a solution of | teaspoonful diastase (drug-
gists or supply companies) in 1 teaspoonful water — a few drops on a
slide. Observe, after 15 minutes, the erosion and disintegration of
many of the grains.

Experiment 12. Respiration takes place in all living members of
the plant. (See the final chapter of the text, this book.) — Experi-
ment 13. A Geranium (Pelargonium}, a Sunflower seedling, or a
Fuchsia, is easily got. The experiments on transpiration (which sub-
ject see in Goodale, Strasburger, and this book) are easily extended,
so as to test the effect of a number of conditions. (See Ganong for
further suggestions.) Convenient balances are the " Harvard trip
scales " (apparatus dealers). The sheet rubber is a grade or two
heavier than that used by dentists.

Experiments 13, 14, 15, and 16 are all on the same activity of the
leaf, transpiration. It will be well to have only one or two prepara-
tions of each experiment, and have all the experiments going on at
once, prepared simultaneously by different groups of pupils. The
essential features of manipulation are seen at sight, and the results
are obvious, so that the whole class may take notes from apparatus
prepared by two or three pupils solel}^ The importance of transpira-
tion in drawing water from the soil, and with water the nutrient
soil salts, should be discussed when the results are all in. Stomatal
regulation may be brought up in connection with the results of Ex-
periments 15 and 16, in' which it is seen that the vapor escapes from
the under surface largely. — Experiment 17. Young potted Tropae-
olums, a month or two old. On heliotropism, or turning occasioned
by light, see Goodale, p. 392, or Strasburger, p. 251. The chapter on
physiology, in this book, may be referred to. — Experiment 18. Seed-
lings of Mimosa pudica may be grown to suitable size in 3 or 4 weeks.
Seeds from seedsmen. Oxalis seeds also from seedsmen, or plants
from growers. On "sleep" movements, see Goodale, p. 409, and
Strasburger, p. 270. The irritability of plants is a most interesting
subject of study.

Exercise XXIV. — Of greenhouse material, Hibiscus or Abutilon is
very good for all points in this exercise. Geranium (Pelargonium)
and German Ivy (Senecio scandens) have stipules. The veining does
not show so well. Of outdoor things, Apple and Quince have stipules.
Selections of the best leaves to illustrate types of venation, compound-
ing, etc., should be made in the summer, and the leaves pressed. But
for Exercise XXIV. fresh material is needed.

Exercises XXVI. and XXVII. — The assortment of leaves given the
pupil will include parallel- and net-veined examples ; and of the latter,
some pinnate, some palmate. Several examples of each category
should be provided. Let some be lobed, divided, etc., so as to suggest
the origin of compounding. Pinnately lobed, palmately lobed forms,

252 APPENDIX

etc., suggest corresponding compound forms. This is meant to be an
exercise in systematic grouping on lines of possible evolution of leaf
forms. Can transitional forms between pinnate ancl palmate be
found? The material will be selected by the teacher from the flora
of the particular locality.

Exercise XXVIII. — Onion. Onion "sets" from the seedsman;
inexpensive. — Acacia. This is interesting in connection with the
natural conditions under which the phyllodineous Acacias grow.
Pressed material may be used, derived, of course, from some green-
house. Phyllodia with leaflets may be found on some species, even in
the adult condition (e.g. A. mebanoxylon). See phyllodes, Ch. X.

Chapter X. The special uses of the leaf, treated in §§ 146-153,
may with great advantage be illustrated by living material. Seeds
of Cobcea macrostemma may be bought and the plant raised in the
schoolroom, if the temperature is favorable. Drosera binata may
perhaps be obtained from florists or from a botanic garden. D.
rotundifolia rests in winter. A Wardian case will keep Droseras,
Sarracenias, and Dionaeas in good condition for observation.

Chapter XI. Exercises XXIX-XXXII. — Scilla siberica is good for
these exercises. Order in the fall, for spring use, from florists. Cost
small. Tulips can be had from Christmas onward. At wholesale
from commercial growers they cost about 2 cents each, though more at
times. Hyacinths, not so good, 5-10 cents a spike, November to May.
The above are mentioned as available for city schools. Scilla is common
everywhere in gardens in early spring. Bulbs, $1 per 100. Of wild
material for the first flower studied. Dogtooth Violet (Erytlironinin}
and Trillium are also good. The Liliacece, in general, are excellent.

Exercise XXXIII. — The principles of anthotaxy had best be taken
up in the course of the general study of the flower, for the sake of
economy of material, rather than as the subject of a separate study.
For the benefit of city schools, some information as to kinds, prices,
etc., of flowers may be proffered. Azaleas, Christmas to Easter, cheap.
Swainsonia (leguminous, racemose), all year, 50 cents dozen spikes.
Candytuft (cruciferous, racemose), all year, 25 cents dozen spikes.
Nasturtium, all year, 25 cents dozen. Begonia (cymose, unisexual),
any time, cheap. Primula, 25 cents pot. Bouvardia (umbellate), 25
cents dozen heads, all year. Crassula quadrifida, compound cymose.
Oxalis, good, cymose. Eupatoriuui, Stevia, and Chrysanthemum frute-
scens, composite heads. The above are suggested In case winter
material must be used. Buy of wholesale dealers, or growers.

Exercise XXXIV. — The material must be gathered at the flowering
season of the tree chosen (Larch, Spruce, Fir, Pine), in spring, and
preserved in alcohol, unless used at once. The fresh, fertile cone
(here for convenience called a "flower," but also spoken of as an
inflorescence) is very beautiful in form and color.

PHANEROGAMIC LABORATORY STUDIES 253

Further work on the flower will be directed toward illustration of
the principles of floral structure and biology, given in the following
chapter of text. The extent and exact character of this study are left
to the discretion of the teacher in view of the material obtainable.

Systematic Botany. — With regard to the study of Systematic
Botany, when this forms a part of the school course, the following
suggestions may prove helpful.

In many schools it has been the custom to require each pupil to
determine or 'analyze" a certain number of plants, perhaps a hun-
dred or more. While this exercise has value, it may be doubted
whether the pupil ordinarily receives from it information or training
commensurate with the time it requires. Through the recognition in
recent years of a greater and greater number of species the accurate
identification of plants has become a matter so technical as to require
a degree of attention and precision rarely possessed by elementary
pupils. Nevertheless, the teacher should spare no effort to impart by
direct instruction or incidental suggestions as clear ah idea as possible
of the general classification and relationships of the plants studied in
the laboratory. Experience shows that pupils grasp without difficulty
the more obvious features which distinguish the larger families. Thus
it requires but a few moments to show that nearly all grasslike plants
may be divided into three great families, the true grasses with round
stems and split leaf sheaths, the sedges with triangular stems, and the
rushes with regular 6-parted flowers. Copious illustrative material
(readily obtained even by city teachers) should be given to the pupils
to exercise their discriminative powers after or during any such instruc-
tion as this. Similarly, it requires but a few moments to show how
most of the remaining monocotyledons may be divided into Liliacece
with superior ovary and six stamens, Amaryllidacece with inferior ovary
and six stamens, Iridacece with inferior ovary and three stamens, and
Orchidacece with inferior ovary and one or two stamens. In like
manner the leading families of dicotyledons will be found to possess
such characteristic features as the peculiar inflorescence of the Umbel-
liferce, the dense heads of the Composites, the square stems, opposite
leaves, and aromatic qualities of the Labiatce, or sheathing stipules of
the Polygonacece. Indeed a very few exercises, in which the pupil is
encouraged to sort for himself, along such simple lines as these, great
piles of mixed flowering plants (including the commonest dooryard
weeds), will enable him to determine at sight the twelve to twenty
more important families, which include four fifths of the flowering
plants he is likely to meet in after life. A similar discrimination of
plants in fields and woods should, whenever practicable, supplement
laboratory exercises. The pupil will, naturally, make many mistakes
at first, being inclined, perhaps, to place a Potentilla in the Ranun-
cuiacece, a Datura in the Convolvulacece, or even a clover in the Com-

254 APPENDIX

positce; but such errors may be turned to good account by a tactful
teacher, since they lead very naturally to the consideration of impor-
tant floral differences.

When a general knowledge of plant families has been obtained,
the pupil's attention may well be directed to such large and well-
marked genera as Lilium, Ranunculus, Delphinium, Lepidium,
Prunus, and the like, and he should be led to contrast these with
others of the same families. Similarly, species of two or three simple
genera should be considered as such.

After this introduction to classification, the use of keys and the
manual will be readily grasped by pupils who are to pursue the sub-
ject further, and it may be suggested to teachers that greater enthu-
siasm in the study of local flora can be stimulated if the subject is
optional than if it is made obligatory. Special care should be exer-
cised to direct the attention of the pupil to those plants which, owing
to their inconspicuous flowers, are likely to be overlooked or thought
too difficult for study. Many small flowers, such as those of Mollugo,
Acer, Galium, etc., will be found relatively simple and instructive, while
those of the far more showy Fringed Polygala, Lady's Slipper, Canna,
and the like, are, from their irregularity, perplexing and discouraging
to the beginner. The successful examination of the flower of a plan-
tain, rush, or grass, obtained in the neighborhood of the schoolhouse
will train the pupil's powers of observation far more effectively than
the dissection of many showy greenhouse flowers.

The teacher's success in this work will be in a general way pro-
portionate to his own knowledge of plants, their names, and relation-
ships. He is, therefore, urged to acquaint himself so far as possible
with the plants of his region by the use of the manual. While a
knowledge of his local flora will help him greatly, an ignorance of the
names and affinities of common plants will expose him to frequent
mortifying experiences when questioned by his pupils and others.

The importance of a school herbarium, even if it be small and
comprise but a few hundred of the commonest plants, can scarcely be
overestimated. Explicit directions for the collecting, labeling, and
caring for the herbarium specimens will be found in Gray's " Struc-
tural Botany," pp. 370-381, or W. W. Bailey's " Botanizing" (Preston
& Rounds Co., Providence). Until the teacher has gained some ex-
perience in identifying species, he will do well to send to some large
botanical establishment for determination, duplicates of such plants
as he is placing in the herbarium. There are several botanical estab-
lishments (for example the Gray Herbarium of Harvard University,
Cambridge, Mass.) where well-prepared dried specimens of native
plants will ordinarily be identified free of charge, provided the speci-
mens may be retained. Each specimen must show, in the case of small
species, the whole plant, of larger ones, 10 or 12 inches of stem bearing

PHANEROGAMIC LABORATORY STUDIES 255

leaves and flower* or fruit. Each must also be accompanied by a label
stating* the place and date of collection and the name of the collector.
The labels should, furthermore, bear distinctive numbers by means of
which the specialist, who examines the specimens, can report to the
teacher their scientific names in such a manner that they can be readily
applied to the duplicating specimens which the teacher has retained
under the same numbers.

Chapter XIII. — Fruits make most interesting material for compara-
tive studies. Preface the laboratory work by a classroom discussion.

Exercise XXXV. — Wild Indigo. Any leguminous pod is suitable.
Wild Indigo (Baptisia tinctoria) is common on dry, sandy soil. Even
Pea pods and Bean pods will do. A teacher offers the following sug-
gestion. "By collecting pods just as they are about to open, and
preserving in formaline, one may keep them indefinitely. When the
class is ready for the study of seed dispersal, the pods may be taken
from the liquid, when they will open just as naturally as in the fall."
— Violet. Alcoholic material, if fruit is out of season. — Checkerberry.
The fleshy part is calyx and receptacle. — Rose Hip. The cup is hol-
lowed receptacle. The " seeds " are the several achenes.

Exercise XXXVI. — Outgrowth of the Testa. Put the Milkweed
and Trumpet Creeper seeds in glass " sample " tubes or small vials,
and seal them up for class study.

Exercise XXXVII. — Illustration i. Staphylea. — Illustration 2.
Rumex crispus, though any Rumex will do. — Illustration 3. Bidens,
known as " Beggar's Ticks." The subject of this exercise is one that
may well be studied further, either in the laboratory from materials
which the fields supply in greatest variety, or in the field itself.

If the course in botany begins in the fall and extends throughout
the year, the fruits studied in the field, or at least collected for study
by the pupils, will in an interesting way introduce the work on seeds.

256 APPENDIX

II. CRYPTOGAMIC LABORATORY STUDIES

The following additional utensils and reagents will be needed: —

Compound microscopes. — Many of the studies in Cryptogams may
be profitably carried out with good hand lenses, supplemented by the
figures of the descriptive text. But compound instruments will, of
course, be provided when possible. Even a single instrument will be
a great gain. The aim should be to have one for each pupil in the
laboratory division. The following makes are recommended as trust-
worthy; there are others: Bausch & Lomb (Rochester, N. Y., New
York, Chicago) ; Leitz (William Krafft, 411 West 59th St., New York) ;
Reichert (Richards & Co., 46 Park Place, New York); Zeiss (of
dealers, e.g. Franklin Educational Co., Boston, and Eimer & Amend,
New York).

Two eye pieces (2-inch and 1-inch) and two objectives (f and \ inch),
with double nose piece, should be had, at least. For many details in the
arrangement of the laboratory and equipment, the teacher should see
some laboratory where these matters have been worked out. For the
theory and use of the microscope, see " The Microscope," Gage, Corn-
stock Pub. Co., Ithaca, N. Y. Practical rules for pupils are given by
Peabody (see under Bacteria, p. 257).

Razors, flat on one side, are needed if pupils make sections them-
selves ; together with strops for sharpening (get a barber to hone
razors), pith for holding objects sectioned, and cheap camel's-hair
brushes for removing sections from razor to slide.

Alcohol (commercial, diluted one half) may be kept on the table in
2-ounce bottles with pipettes fitted into the corks. Bottles for potash,
glycerine, and iodine, are made with ground glass stoppers drawn out
into droppers (1-ounce " dropping bottles " of dealers), for 15-20 cents
each. Put two 1-inch pieces of stick potash into bottle, and fill up
with water. Use glycerine one third strength, and tinge with eosin.
Prepare aqueous iodine as before directed (with KI).

Plants for study. — Material may be bought of supply companies
(Cambridge Botanical Supply Co., Cambridge, Mass.; Geo. M. Gray,
Wood's Roll, Mass.; Ithaca Botanical Supply Co., Ithaca, N. Y.).
Slides may be bought of dealers in microscopical accessories. Material
collected by the teacher is best preserved in 70 % alcohol. When the
habitats of plants recommended for study are not mentioned in the
descriptive text, they are given below, together with the times for col-
lecting, the dates giveu being applicable to New England.

Books. — Strasburger's text-book will give the main facts on
Cryptogams. Bennett and Murray's "Handbook of Cryptogamic
Botany " (Longmans, Green & Co., New York, .$5.00) gives fuller de-
tails. On Algae, see George Murray's "Introduction to the Study of

CRYPTOGAM 1C LABORATORY STUDIES 257

Seaweeds." For a full treatment of Fungi, see l)e Bary's "Compara-
tive Morphology and Biology of the Fungi, Mycetozoa, and Bacteria"
(Clarendon Press, 1887). For names of many common fleshy Fungi,
refer to W. H. Gibson's " Our Edible Toadstools and Mushrooms "
(Harper Bros.) ; for Lichens, to Schneider's " Guide to the Lichens "
(Bradlee Whidden, Boston) ; for Mosses, to A. J. Grout's " Mosses
with a Hand Lens " (Grout, 360 Lenox Road, Brooklyn, N. Y.) ; for
Ferns, Lycopodiums, etc., Gray's " Manual."

346. Nostoc. — Alternative, Oscillatoria, found on surface of mud
where covered with (especially foul) water, also on the surface of
pools, also as a slippery coating on rocks in rapidly flowing streams.
Easier to find than Nostoc. The former (as well as Nostoc) often in
greenhouses. It is an open question whether the cell or the chain is
the " individual."

347. Pleurococcus. — See descriptive text.

348. Spirogyra. — Conjugating material may be sought in late April
and May. Examine with the lens floating masses turning yellowish. —
The cells treated with glycerine are plasmolyzed, when the protoplasmic
contents is driven away from the walls. Emphasize the separability
of wall and protoplasm.

352. Vaucheria. — On pots in greenhouses. It is said that material
showing both kinds of reproduction mentioned in text, may be
obtained by throwing mats of the plant into jars half full of water
about six weeks before use, and placing the jar in strong light.

355. Ectocarpus. — Sporangia may be found intercalated in the fila-
ments, as well as at the ends of branches. Gametangia = pleurilocular
sporangia.

356. Rockweed (Fucus). — Abundant on rocks between tide marks;
in " fruit " more or less throughout the year. At its best, perhaps, in
summer and autumn. Break open the fruiting portions and examine
with hand lens. — Wet the razor with alcohol. Make many sections
before removing any from razor, then, on the slide, select the thinnest
for study.

359. Polysiphonia may be found epiphytic on Ascophyllum. The
latter is the dark (almost black) Rockweed, with thick narrow fronds
without midrib, in which are elongated, bean-shaped bladders. In
buying Polysiphonia specify tetraspores.

361. Nemalion. — The fronds are made up of essentially independent
filaments. — Batrachospermum may be used as alternative. It grows
on stones in running brooks. The carpogonia and antheridia are
found early in the season (April).

362. Bacteria. — This subject is of the highest practical importance,
and, if possible, should be treated with considerable fullness. Dwell
on the relation of cleanliness, in household and person, to health.
The laboratory studies should, if possible, be extended in some such

OUT. OF BOX. — 17

258 APPENDIX

lines as those drawn by J. E. Peabody in " Laboratory Exercises in
Anatomy and Physiology" (Holt & Co., New York ; 60 cents). The
study of Bacteria given by Peabody is highly to be recommended. By
all means see also Journal of Applied Microscopy for February, 1891
(Vol. IV., p. 1164).

363. Yeast. — Use fresh yeast cake.

366. Rhizopus. — Use fresh, moist bread. Let each pupil place a
piece 1 inch square or so on the bottom of a plain tumbler, or, better,
a small crystallizing dish, covering to keep moist, two or three days in
advance of use. — For zygospores — hard to get in Rhizopus — Sporo-
dinia may be used. It is found growing as yellowish, smoky tufts of
mold on fleshy fungi in woods. Zygospores may be found on the
under side of the pileus of the fleshy fungus. Preserve in alcohol.

369. Saprolegniaceae. — Allow from four days to a week, according
to temperature, for the molds to develop. Or, better, throw in some
of the killed seedlings (Tomato, or other small things) and insects on
several successive days, beginning a week in advance of use. Zob'spo-
rangia are more abundant on young material. The zoospores swim
away at once in some species, and will not be found near by in a
quiescent state.

372. Peziza, on logs and sticks in woods in summer.

375. Microsphaera alni, in late summer and in September. Press
the leaves. Uncinula, another fungus of the same group, is common
on Willow leaves ; another form is on the under side of Horse-chestnut
leaves (August, September). — The asci are essentially like those of
Peziza.

377. Toadstool. — Fresh horse dung in bowls, under cake covers (to
keep moist), will give Coprinus in about two weeks. Make several
lots to be sure of material. Various molds will come up before
Coprinus. Wash these down by sprinkling with water after a week.
Take the young heads of Coprinus before they open out, in order to
section across gills. Or get other material in summer and keep in
alcohol.

379. Lichen. — Physcia stellaris, or any expanded form found on tree
trunks. For comparison of habit show such a form as Cladonia
cristatella, common in pastures, distinguished by bright scarlet apo-
thecia. If time and microscopes permit, study the structure of the
thallus further. What are the " green bodies," and what is the nature
of the other elements ?

381. Marchantia. — In fruit (spores) in early summer. Lunularia,
known by its crescent-shaped cupiiles, will serve for the living habit
and the gemmae of this kind of Liverwort. It is common in green-
houses.

386. Moss. — Folytrichum commune may be found in good condition
(sex organs) in May. The fertile shoots are known by the flowerlike

CRYPTOGAMIC LABORATORY STUDIES 259

arrangement of the leaves at the summit. The sporogonia are mature
later. Preserve in alcohol, if necessary. Other mosses (e.g. Mnium)
will serve. The protonerna may be found in greenhouses and on soil
where moss is growing.

390. Fern. — Prothallia are easiest got in greenhouses. They may
best be grown (by the florist) on potsherds. The smaller prothallia
are likely to have antheridia alone. For the spores, use preferably
some Aspidium, taken when the sori are youngish. If necessary
preserve this material in alcohol. In the Maidenhair Fern the sori
are covered by the recurved leaf margin — not an indusium. — If
smallish prothallia, which have not been wet for some time, are placed
in a drop of water on a slide, the aniherozoids are likely to be seen ;
use a low power of the compound microscope.

396. Selaginella, from greenhouses, in fruit in early spring (some
species at other times). 5. rupestris is found in dry situations (as
bare hilltops) at the edge of ledges in poor soil. It looks at a
distance like a stiff, coarse moss.

400. Lycopodium is the " ground pine " used for Christmas decora-
tions. In fruit in late summer.

402. Equisetum arvense is common on railroad banks, the fertile
shoots appearing in early May, the vegetative shoots later.

INDEX AND GLOSSARY

Abortive. Imperfectly developed. 128.

Absorption, by root, 232 ; selective, 232.

Acaulescent. Stemless, or apparently so. 56.

Accumbent (cotyledon). Having the edges
against the radicle.

Achene. A small, dry, hard, 1-celled, 1-
seeded, indehiscent fruit. 149.

Acicular. Slender, needle-shaped.

Actinomorphic, 128.

Aculeate. Prickly, beset with prickles.

Acuminate. Tapering at the end. 94.

Acute. Terminating in a sharp or well-de-
fined angle. 94.

Adaptation, types of, 64.

Adnate. United, as the inferior ovary with
the calyx tube. Adnate anther, one at-
tached for its whole length to the inner or
outer face of the filament. 135.

Adnation, 115.

Adventive. Kecently or Imperfectly natural-
ized.

^Estivation. Arrangement of parts of peri-
anth in bud. 138.

A late. Winged.

Albumen, 18.

Albuminous seeds, 18.

Albuminous substances, formation of,!236.

Algae, blue-green, 170 ; brown, 17T ; green,
171 ; red, 180 ; unicellular, 157.

Alternate. Not opposite to each other, as se-
pals and petals, or as leaves on stem. 90.

Alternation of generations, 207.

Alveolate. Honeycombed; having angular
depressions separated by thin partitions.

Ament. A catkin, or peculiar scaly unisexual
spike. 141.

Amphitropous (ovule or seed). Half inverted
and straight, with the hilurn lateral. 138.

Amplexicaul. Clasping the stem.

Anastomosing. Connecting by cross veins
and forming a network.

Anatomy of phanerogams (ch. xvii.), 212.

Anatropous (ovule). Inverted and straight,
with micropyle next the hilum. 138.

Androecium, 109.

Androgynous (inflorescence). Composed of
both staminate and pistillate flowers.

Angiospermous. Having seeds borne wilhin
a pericarp.

Angiosperms, 107.

Annual. Of only one year's duration. 44.

Anther, 108.

Antheridial tubes, 189.

Antheridium, 176, 179, 203.

Antherozoids, 176, 178, 179. 200, 206.

Anthesis. Time of expansion of a flower.

Apetalous. Without petals. 129.

Apiculate. Ending in a short, pointed tip.

Apothecium, 190.

Arachnoid. Cobwebby ; of slender entangled
hairs.

Archegouium, 201, 203, 206.

Arcuate. Moderately curved.

Areolate. Marked out into small spaces;
reticulate.

Aril, 152. Arilate, having an aril.

Aristate. Having an awn, or slender, bristle-
like termination. 94.

Articulate. Jointed ; having a node or joint.

Ascent of sap, 233.

Ascomycetes. 190.

Ascus, 190, 191.

Aspergillus, 192.

Assimilation, 234; carbon, 72; (Exp. 11),
66.

Assurgent. Ascending.

Attenuate. Slenderly tapering; becoming
very narrow.

Auriculate. Having an ear-shaped append-
age. 93.

Awl-shaped. Narrowed upward from the
base to a slender or rigid point.

Awn. A bristle-shaped appendage.

Axil, 29.

Axile placentation, 105.

Axillary. Situated in an axil. 29.

Baccate. Berrylike ; pulpy throughout.
Bacteria, 160, 184 ; practical study, 256.
Barbed. Furnished with rigid points or

bristles, usually reflexed like the barb of

a fishhook.

Barbellate. Finely barbed.
Bark, anatomy of, 225 ; falling of old layers,

226.

Basidiomycetes, 163, 194.
Basidium, 195.
Bast fibers, 219.
Batrachospermum, 180.
Berry, 149.

Bidentate. Two-toothed.
Biennial. Of two years' duration. 45.
Bifid. Two-cleft.
Big Trees, 63.
Bilabiate. Two-lipped.
Bilocellate. Having two secondary cells.
Biloculate. Two-celled.
Bladderwort, 89.
Blade, 73.

Blue-green Alga?, 170.
Books of reference, 244. 255.
Bract. A more or less modified leaf sub-

261

262

INDEX AND GLOSSARY

tendiug a flower, or belonging to an in-
florescence. 120, 140.

Bracteate. Having bracts.

Bracteolate. Having bractlets.

Bractlets. Secondary bracts, as on a pedicel
of a flower.

Bread Mold, 160, 168.

Brown Algae, 158.

Bryophytes, 198.

Buds, accessory, 29 ; adventitious, 33 ; ax-
illary, 29; comparative vigor, 26; discus-
sion introducing study of, 247 ; dormant
condition, 30 ; general structure, 23 ; grow-
ing, 27 ; laboratory studies, 23 ; latent, 32 ;
mixed, 30 ; naked, 81 ; nondevelopment, 25,
32 ; protection, 27, 28, 31 ; time taken to
unfold, 248 ; unfolding, 25 ; winter, 29.

Bulb, 60.

Bulbiferous. Bearing bulbs.

Bulblets, 58.

Caduceous. Falling off early.

Calcarate. Produced into, or having, a spur.

Calcium oxaiate, 217.

Callus. A hard protuberance, or callosity.

Calyculate. Having brae ts around calyx, imi-
tating an outer calyx.

Calyptra, 203.

Calyx, 100, 110.

Cambium, 222 ; of cork, 225.

Campanulate. Bell-shaped ; cup-shaped ;
with a broad base. 132.

Campylotropous (ovule or seed). So curved
as to bring apex and base nearly together.
138.

Canaliculate. Longitudinally channeled.

Canescent. Hoary, with gray pubescence.

Capitate. Shaped like a head ; collected into
a head or dense cluster.

Capsule. A dry, dehiscent fruit composed of
more than one carpel. 151.

Carbon assimilation, 234.

Carbon dioxide, source of, 234.

Carinate. Having a keel or a projecting longi-
tudinal medial line on the lower surface.

Carpel. A simple pistil, or one member of a
compound pistil. 104.

Carpogonium, 181.

Carpospore, 182.

Caruncle, 152.

Carunculate. Having a caruncle.

Caryopsis. A grain, as of grasses ; a seed-
like fruit with a thin pericarp adnate to the
contained seed. 150.

Catkin. An ament. 141.

Caudate. Having a slender taillike appendage.

Caudex. The persistent base of an otherwise
annual herbaceous stem.

Caulescent. Hav'ng a manifest stem.

Caulicle, 17.

Cauline. Belonging to the stem.

Cell, 212; changes in shape. 218; of ovary,
105; of stamens, 136; typical, 173.

Cell fusion, 220.

Cell sap, 216.

Cellular structure of plants, 116.

Cellulose, 218.

Cell wall, 217.

Cespitose. Growing in tufts ; forming mats
or turf.

Chaff. A small, thin scale or .bract, becoming
dry and membranous.

Chaffy. Having or resembling chaff.

Chaloza, 137, 153.

Chlorophyll, 23, 72.

Chlorophyll granules, 215.

Chloroplastids, 215.

Chromatophore, 173.

Cilium, 172.

Ciliate. Marginallv fringed with hairs.

Ciliolate. Minutely ciliate.

Cinereous. Ash color.

Circinate. Coiled from the top downward, as
the young frond of a fern.

Circumscissile. Dehiscing by a regular trans-
verse circular line of division.

Clavaria, 195.

Clavate. Club-shaped ; gradually thickened
upward.

Claw, 132.

Cleistogamous. Fertilized in the bud, with-
out the opening of the flower. 119.

Cleft. Cut about to the middle. 95.

Climbers, 53.

Club Moss, 167.

Coalescence. The union of parts or organs
of the same kind. 114.

Cochleate. Spiral like a snail shell.

Collenchyma, 219.

Columella. The persistent axis of some
capsules, spore cases, etc.

Coma. i. tuft of hairs. 152.

Comose. Furnished with a coma.

Commissure. The surface by which one
carpel joins another, as in the Urnbelliferse.

Complete (flower), 128.

Components of plant body, 231.

Compound. Composed of two or more simi-
lar parts united into one whole. Compound
leaf: one divided into separate leaflets. 82,
96.

Compressed. Flattened laterally.

Conceptacle, 179.

Conduction of sap in leaf, 69.

Conduplicate. Folded together lengthwise.

Confluent. Eunning into each other;
blended into one.

Coniferous. Cone bearing.

Coniferous flower, 102.

Conjugation, 172, 182.

Connate. United congenitally.

Connective. The portion of a stamen which
connects the two cells of the anther. 108.

Connivent. Coming into contact ; con-
verging.

Convolute. Rolled up longitudinally.

Cordate. Heart-shaped, with the point up-
ward. 93.

Coriaceous. Leathery in texture.

Cork, 225.

INDEX AND GLOSSARY

263

Conn. The enlarged fleshy base of a stem,
bulblike, but solid. 60.

Corolla. The iiiner perianth, of distinct or
connate petals. 100, 110.

Coronifortn. Shaped like a crown.

Corrugate. Wrinkled or in folds.

Corticium, 195.

Corymb. A flat-topped or convex open flower
cluster, in the stricter use of the word,
equivalent to a contracted raceme, and
progressing in its flowering from the
margin inward. 140.

Corymbose. In corymbs, or corymblike.

Costate. Eibbed ; having one or more longi-
tudinal ribs or nerves.

Cotyledons. The foliar portion or first leaves
(one, two, or more) of the embryo as found
in the seed. 17.

Cotyledons, sleep of, 75.

Crateriform. Having the form of a shallow
bowl.

Creepers, 57.

Crenate. Dentate with the teeth much
rounded. 95.

Crenulate. Finely crenate.

Cristate. Bearing an elevated appendage re-
sembling a crest.

Cross-fertilization, 118 ; agencies for, 120.

Crossing, effect of, 127.

Crown. An inner appendage to a petal, or to
the throat of a corolla. 132.

Crustaceous. Of hard and brittle texturei

Cryptogams, 13; laboratory studies, 157;
(ch. xvi.), 168; relationship to phanero-
gams, 211.

Cucullate. Hooded or hood-shaped ; cowled.

Culm. The peculiar stem of .sedges and

Cuneate. "Wedge-shaped; triangular, with
the acute angle downward. 93.

Cupules, 200.

Cuspidate. Tipped with a cusp, or sharp
and rigid point. 94.

Cuticle, 227.

Cutleria, 178.

Cyme. A usually broad and flattish deter-
minate inflorescence, i.e. with its central
or terminal flowers blooming earliest. 142.

Cymose. Bearing cymes, or cymelike.

Cytoplasm. General mass of the protoplasmic
cell, aside from the nucleus. 214.

Deciduous. Not. persistent ; not evergreen.

Decompound. More than once compound
or divided. 98.

Decumbent, declining, but with the sum-
mit ascending.

Decurrent (leaf). Extending down the stem
below the insertion.

Decussate. Alternating in pairs at right
angles. 91.

Definite. Of a constant number, not exceed-
ing twenty.

Deflexed. Bent or turned abruptly down-
ward.

Dehiscent, Dehiscence, 151. Opening regu-
larly by valves, slits, etc., as a capsule or
anther. 151.

Deliquescent trunks, 33.

Deltoid. Shaped like the Greek letter A.

Dentate. Toothed, usually with the teeth
directed outward. 82, 9*.

Denticulate. Minutely dentate.

Depressed. Somewhat flattened from above.

Determinate (inflorescence), 139, 142.

Diadelphous (stamens). Combined in two
sets. 135.

Diandrous. Having two stamens. 185.

Dicarpellary. Composed of two carpels.

Dichotomous. Forking regularly by pairs.

Dicotyledonous. Having two cotyledons.

Dicotyledons, 17 ; fibrovascular bundles of,
222; plan of flower, 110; stem structure,
47 ; stem, anatomy of, 223.

Didyinous. Twin ; found in pairs.

Didynamous (stamens). In two pairs of
unequal length. 135.

Diffuse. "Widely or loosely spreading.

Digestion, 235; (Exp.), 250.

Digitate. Compound, with the members
borne in a whorl at the apex of the sup-
port.

Dimerous (flower). Having all the parts in
twos.

Dimorphous. Occurring in two forms. 123.

Dioecious. Unisexual, with the two kinds
of flowers on separate plants. 119, 129.

Discoid. Eesembling a disk. Discoid head,
in Composite, one without ray flowers.

Disk. A development of the receptacle at or
around the base of the pistil. In Com-
posite, the tubular flowers of the head as
distinct from the ray.

Dissected. Cut or divided into numerous
segments. 79.

Dissemination, 145, 153 ; agents of, 153 ; by
animals, 155 ; by ejection, 156 ; by water,
155 ; by wind, 153.

Dissepiment. A partition in an ovary or
fruit.

Distichous. In two vertical ranks.

Distinct. Separate ; not united ; evident.

Divaricate. Widely divergent.

Divided. Lobed to the base. 96.

Dodder, 41.

Dormant condition, seeds, 19.

Dorsal. Upon or relating to the back or
outer surface of an organ.

Drawing, 242.

Drupaceous. Kesembling or of the nature
of a drupe.

Drupe. A fleshy or pulpy fruit with the in-
ner portion of the pericarp (1-celled and
1-seeded, or sometimes several-celled) hard
or stony. 149,

Drupelet. A diminutive drupe.

Echinate. Beset with prickles.
Ecology. That part of botany which treats
of plants in their relations to their sur-

264

INDEX AND GLOSSARY

roundings. Of buds, 33 ; of flowers, 118,
127; of fruits, 153.

Ectocarpus, 158, 178.

Effuse. Very loosely spreading.

Egg cell, 176," 178, 179, 181, 189, 201.

Elater, 210.

Elements composing plants, 231.

Emarginate. Having a shallow notch at the
extremity. 94.

Embryo, 7, 16 ; food for, 19 ; of conifers, 12 ;
origin of, 118.

Embryo sac, 118, 211.

Endocarp. The inner layer of a pericarp. 149.

Endogens, 223.

Endosperm, 18.

Entire. "Without toothing or division.

Enzymes, ferments, 236.

Ephemeral. Lasting only for one day.

Epidermis, 226, 227.

Epigynous. Growing on the summit of the
ovary or apparently so. 130, 134.

Epipetalous. Upon the petals. 134.

Epiphytes, 16 ; roots of, 39, 40.

Equisetum, 167, 210.

Erose. As if gnawed.

Exalbuminous. Without albumen. 18.

Excurrent. Running out, as a nerve of a
leaf projecting beyond the margin. Ex-
current trunks, 33.

Exfoliating. Cleaving off in thin layers.

Exocarp. The outer of two layers of peri-
carp. 149.

Exogenous. Growing by annular layers near
the surface ; belonging to the Exogens.
223.

Experiments, manual of, 243.

Exserted. Projecting beyond an envelope,
as stamens from a corolla.

Extrorse. Facing outward. 136.

Falcate. Scythe-shaped; curved and flat,
tapering gradually.

Farinaceous. Containing starch ; starchlike.

Farinose. Covered with a meallike powder.

Fascicle. A close bundle or cluster. 143.

Fastigiate (branches). Erect and near to-
gether.

Fat, in seeds, 19.

Fermentation by Yeasts, 186.

Ferments, 236.

Fern (laboratory study), 165.

Ferns, 204.

Ferruginous. Eust color.

Fertile. Capable of producing fruit, or pro-
ductive, as a flower having a pistil, or an
anther with pollen.

Fertilization, in Vaucheria, 176 ; of the ovule,
118.

Fibrillose. Furnished or abounding with
fine fibers.

Fibrous. Composed of or resembling fibers.
Fibrous tissue : a tissue formed of elon-
gated thick-walled cells.

Fibro-vascular. Composed of woody fibers
and ducts. 221.

Filament. The part of a stamen which sup-
ports the anther ; any threadlike body. 108.

Filamentous. Composed of threads.

Filiferous. Thread bearing.

Filiform. Thread shaped ; long, slender, and
terete.

Fimbriate. Fringed.

FimbriUate. Having a minute fringe.

Fistular. Hollow and cylindrical.

Flaccid. Without rigidity ; lax and weak.

Flexuous. Zigzag; bending alternately in
opposite directions.

Floccose. Clothed with locks of soft hair or
wool.

Floret, 126.

Flower (ch. xii.), 103; arrangement of or-
gans, 101; coniferous, 102; ecology, 118;
general morphology, 103 ; laboratory stud-
ies, 99; terminology, 128; winter study, 252.

Foliaceous. Leaflike in texture or appear-
ance.

Follicle. A fruit consisting of a single car-
pel, dehiscing by the ventral suture. 150.

Follicular. Like a follicle.

Food, for buds, 32 ; of young plant, 8 ; stored
in seed, 18; translocation, 236; supply
(exp. study), 13.

Foramen, 137.

Forests, seeds in soil of, 19.

Formaline, 242.

Fornicate. Arched over, as the corona of
some Borraginaceae, closing the throat.

Free. Not adnate to other organs.

Frond. The leaf of Ferns and some other
Cryptogams.

Fruit, ecology of, 153; laboratory studies,
144; nature of, 147; origin, 144.

Fruits, aggregate, 148 ; drupaceous, 148 ; in
relation to dissemination, 145 ; kinds, 147 ;
multiple, 148; self-burying, 154; stone,
148.

Fugacious. Falling or fading very early.

Fungi, 183 ; Sac Fungi, 190.

Funicle. The free stalk of an ovule or seed.
137.

Funnel-form, 132.

Fuscous. Grayish brown.

Fusiform. Spindle-shaped ; swollen in th»
middle and narrowing toward each end.

Galea. A hooded or helmet-shaped portion
of a perianth, as the upper sepal of Aconi-
tum, and the upper lip of some bilabiate
corollas.

Galeate. Helmet-shaped ; having a galea.

Gamete, 176, 179, 188, 207.

Gametophyte, 207.

Gamopetalous. Having the petals of the
corolla more or less united. Ill, 131.

Gamophyllous. Composed of coalescent
leaves, sepals, or petals.

Gemma, 200.

Gemmiparous. Producing gemmse.

Geniculate. Bent abruptly, like a knee.

Geotropism (Exp. 5), 11, 49, 240.

INDEX AND GLOSSARY

265

Germination, 9 ; conditions, 19 ; heat of

(Exp. 8), 10 ; influence of temperature, 11 ;

of Horse-chestnut, 22 ; time required, 247.
Gibbous. Protuberant or swollen on one

side.
Glabrate. Somewhat glabrous, or becoming

glabrous.
Glabrous. Smooth; not rough, pubescent,

or hairy.
Gland. A secreting surface or structure ;

any protuberance or appendage having the

appearance of such a structure.
Glandular. Bearing glands or of the nature

of a gland.
Glaucous. Covered or whitened with a

bloom.

Glochidiate. Barbed at the tip.
Glomerate. Compactly clustered.
Glomerule. ~ A cymose head. 143.
Glutnaceous. Furnished with or resembling

glumes.

Glume. One of the chaffy bracts of the in-
florescence of Grasses.
Granular. Composed of small grains.
Grit cells, 220.
Growth and reproduction, 174 ; annual, 33 ;

conditions, 239 ; fluctuations, 239 ; grand

period, 239; of stems, 52; phases, 238;

of root (Exp.), 35.
Guard cells, 228.
Guttation (Exp.), 35, 249.
Gymnospermous. Bearing naked seeds,

without an ovary.
Gymnosperms (Coniferce), 102; pistils of,

106.
Gynandrous. Having the stamens borne

upon the pistil, as in Orchidaceae. 134.
Gynobase. An enlargement or prolongation

of the receptacle bearing the ovary.
Gynoaciuin, 109.

Habit. The general appearance of a plant.

Halophytes, 65.

Hastate. Like an arrow head, but with the

basal lobes pointing outward nearly at

right angles, 93.

Heliotropism, 240 ; (Exp.), 49, 68.
Herb. A plant with no persistent woody

stem above ground.
Herbaceous. Having the characters of an

herb ; leaflike in color and texture.
Herbaria, 253.
Heterocyst, 170.

Heterogamous. Bearing two kinds of flowers.
Hilum. The scar or point of attachment of

the seed. 137,153.
Hirsute. Pubescent w!th rather coarse or

stiff hairs.
Hispid. Beset with rigid or bristly hairs or

with bristles.

Hispidulous. Minutely hispid.
Homogamous. Bearing but one kind of

flowers.

Hormogonia, 171.
Horsetail (Equisetum), 167.

Hyaline. Transparent or translucent.

Hybrid. A crossbreed of two species.

Hydnum, 195.

Hydrophytes, 65.

Hydrotropism (Exp.), 85, 240, 249.

Hymenium, 191, 195.

Hypha, 183.

Hypogynous. Situated on the receptacle be-
neath the ovary and free from it and from
the calyx ; having the petals and stamens
so situated. 130, 134.

Imbricate. Overlapping, either vertically or
spirally, where the lower piece covers the
base of the next higher, or laterally, as in
the aestivation of a calyx or corolla, where
at least one piece must be wholly external
and one internal. 139. •

Immersed. Growing wholly under water;
wholly covered by the involucral leaves, as
sometimes the capsule in Hepaticae.

Imperfect (flower), 128.

Incised. Cut sharply and irregularly, more
or less deeply. 95.

Included. Not at all protruded from the
surrounding envelope.

Incomplete (flowers), 129.

Incubous (leaf). Having the tip or upper
margin overlapping the lower margin of
the leaf above.

Incumbent (cotyledons). Lying with the
back of one against the radicle.

Indefinite (stamens). Inconstant in number
or very numerous.

Indehiscent. Not opening by valves, etc. ;
remaining persistently closed. 148.

Indigenous. Native and original to the
country.

Induplicate. Valvate with margins project-
ing inwards. 138.

Indurated. Hardened.

Indusium, 205.

Inequilateral. Unequal-sided.

Inferior. Lower or below; outer or ante-
rior. Inferior ovary: one that is adnate
to the calyx, 130.

Inflated. Hollow and distended.

Inflorescence. The flowering part of a plant,
and especially the mode of its arrange-
ment. 101, 139.

Innate (anther), 135.

Insectivorous plants, 86.

Inserted. Attached to or growing out of.

Integuments (teguments), 137.

Intercrossing, agencies, 120.

Internode. The portion of a stem between
two nodes.

Intramarginal. Within and near the margin .

Introrse. Turned inward or toward the
axis. 136.

Involucel. A secondary involucre, as that of
an umbellet in Umbelliferae, 142.

Involucellate. Having an involucel.

Involucral. Belonging to an involucre.

Involucrate. Having an involucre.

266

INDEX AND GLOSSARY

Involucre. A circle or collection of bracts

surroundiug a flower cluster or head, or a

single flower.

Involute. Eolled inward. 138.
Iodine, in test for starch, 9 ; preparation, 246.
Irregular (flower). Showing inequality in

the size, form, or union of its similar parts.

129.
Irritability, 240.

Keel. A central dorsal ridge, like the keel of
a boat ; the two anterior united petals of a
papilionaceous flower. 133.

Kidney-shaped. Crescentic with the ends
broad and rounded ; reniform.

Labiate. Lipped ; belonging to the Labiatae.
133.

Laboratory outfit, 241, 255.

Lacerate. Irregularly cleft as if torn.

Laciniate. Slashed ; cut into narrow pointed
lobes.

Lamella. A thin flat plate or laterally flat-
tened ridge. 194.

Lanceolate. Shaped like a lance head, broad-
est above the base and narrowed to the
apex. 92.

Lateral. Belonging to or borne on the side.

Latex tubes, 220.

Leaf, 71 ; activities of (Exps.), 66 ; anatomy,
266 ; assimilation in (Exp. 11), 66, 72 ; 'con-
duction in (Exp. 20), 69 ; form and quali-
ties, 72 ; heliotropism (Exp. 17), 68 ; labora-
tory studies, 66 ; office, 71 ; parts, 73 ; res-
piration (Exp. 12), 66; sleep movements
(Exp. 18), 68; special uses, 70; stability
(Exp. 21), 69; structure, 69; tendril, of
Cobsea, 84 ; venation, 70.

Leaflet. A single division of a compound
leaf.

Leaves, aquatic, 79, 80 ; arrangement, 89 ;
bladeless, 76; climbing, 83 ; compound, 70,
82, 96 ; disposition in relation to light, 74 ;
division, 96 ; duration, 89 ; equal illumina-
tion, 81 ; for storage, 83 ; insectivorous, 86 ;
lobing, 96; metamorphosed, 70; netted
veined, 78 ; palmately veined, 78 ; parallel
veined, 77 ; pinnately veined, 78 ; shapes,
78; shedding of, 89; special conformation,
83; special uses, 83; spinelike, 83; terms
used in description, 92.

Legume. The fruit of the Leguminosae,
formed of a simple pistil and usually dehis-
cent by both sutures. 150.

Leguminous. Pertaining to a legume or to
the Leguminosae.

Lepidote. Beset with small scurfy scales.

Liber, 225.

Lichens, 163, 196.

Ligulate. Furnished with a ligule. 133.

Ligule. A strap-shaped corolla, as in the
ray flowers of Composita? ; a thin scarious
projection from the summit of the sheath
in Grasses.

Limb. The expanded portion of a gamo-

petalous corolla, above the throat; the ex-
panded portion of any petal, or of a leaf.

131.
Linear. Long and narrow, with parallel

margins.
Lip. Each of the upper and lower divisions

of a bilabiate corolla or calyx ; the peculiar

upper petal in Orchids.
Liverworts, 1(54, 198.
Lobe. Any segment of an organ, especially

if rounded. 96. •
Loculicidal. Dehiscent into the cavity of a

cell through the dorsal suture. 151.
Loment. A legume constricted, and at

length breaking, between the seeds. 150.
Longevity of trees, 63.
Lunate. Of the shape of a half moon or

crescent.

Lycopodium, 167, 209.
Lyrate. Pinnatifid with a large and rounded

terminal lobe, and the lower lobes small.

Macrosporangium, 208.

Macrospore, 208^

Marcescent. Withering, but persistent.

Marchantia, 164, 198.

Material, illustrative, 242, 252.

Medullary rays, 224.

Membranaceous, Membranous. Thin and

rather soft and more or less translucent.
Meniscoid. Concavo-convex.
Mericarp. One of the achenelike carpels of

Umbelliferae.
Merous. In composition, having parts ; as,

2-merous, having two parts of each kind.
Mesophytes, 65.
Micropyle. The point upon the seed at

which was the orifice of the ovule. 153.
Microscopes, compound, 242, 255; dealers

in, 241 ; simple, 241.
Microsphaera, 162, 191.
Microsporangium, 208.
Microspore, 208.

Midrib. The central or main rib of a leaf.
Mildews, powdery, 191.
Mistletoe, 41.
Monadelphous (stamens). United by their

filaments into a tube or column. 134.
Monandrous, 135.
Moniliform. Kesembling a string of beads ;

cylindrical with contractions at intervals.
Monocotyledonous. Having but one coty-
ledon.
Monocotyledons, 17 ; fibrovascular bundles

of, 222; floral plan, 110; stem structure,

47, 223.
Monoecious. With stamens and pistils in

separate flowers on the same plant. 119,

129.

Morphology, 14.
Mosses, 202.
Movements, 239 ; due to change of turgidity,

240 ; induced, 240 ; spontaneous. 240.
Mucilaginous, Slimy ; containing mucilage.
M ucro. A short and small, abrupt tip.

INDEX AND GLOSSARY

267

Mucronate. Tipped with a mucro. 94.
Multifid. Cleft into many lobes or seg-
ments.

Mummy cases, seeds from, 19.
Muricate. Kough, with short, hard points.
Muriculate. Very finely muricate.
Mycelium, 183.

Naked. Bare ; without the usual covering
or appendages. 129.

Nectar glands, 125.

Nectar, protection of, 125.

Nectary. Any place or organ where nectar
is secreted. 125.

Nectariferous. Producing nectar.

Nemalion, 159.

Nerve. A simple or unbranched vein or
slender rib. 78.

Node. The place upon a stem which nor-
mally bears a leaf or whorl of leaves.

Nodose. Knotty or knobby.

Nostoc, 157, 170.

Notebooks, 241.

Nucellus, 137.

Nucleus, 116, 173, 214.

Nut. A hard, indehiscent, 1-celled, and
1-seeded fruit, though usually resulting
from a compound ovary. 150.

Nutlet. A diminutive nut.

Nutrient salts absorbed, 232.

Obcompressed. Compressed dorsiventrally

instead of laterally.
Obconically. Inversely conical, having the

attachment at the apex.
Obcordate. Inverted heart-shaped, 94.
Oblanceolate. Lanceolate, with the broadest

part toward the apex, 92.
Oblique. Unequal-sided or slanting.
Oblong. Considerably longer than broad,

and with nearly parallel sides. 92.
Obovate. Inverted ovate. 93.
Obovoid. Having the form of an inverted

egg.

Obsolete. Not evident ; rudimentary.
Obtuse. Blunt or rounded at the end. 94.
Ocrea. A legging-shaped or tubular stipule.
Ocreate. Having sheathing stipules.
Ochroleucous. Yellowish white.
Officinal. Of the shops ; used in medicine or

the arts.
Offsets, 58.
Oil in seeds, 9.
Oogonium, 176, t79, 189.
Oospore, 176, 179, 189.
Oosporic reproduction, 182.
Opaque. Dull ; not smooth and shining.
Operculate. Furnished with a lid.
Operculum. A lid ; the upper portion of a

circumscissile capsule. 203.
Orbicular. Circular. 92.
Orchids, roots of, 40.
Orthotropous (ovule or seed"). Erect, with

the orifice or micropyle at the apex. 137.
Oscillatoria, 170, 256.

Osmosis, 230.

Oval, 92.

Ovary. The part of the pistil that contains
the ovules. 104.

Ovate. Egg-shaped ; having an outline like
that of an egg, with the broader end down-
ward. 92.

Ovoid. A solid with an oval outline.

Ovule, 136 ; fertilization of, 118.

Ovules, 103 ; study of, 99.

Ovuliferous. Bearing ovules.

Oxidation, source of vital heat, 20.

Oxygen, in germination (Exp. 1), 10, 19;
liberated, 235; required by cells, 287;
taken up by embryo, 20.

Palate. A rounded projection of the lower
lip of a personate corolla, closing the throat.

Paleaceous. Chaffy.

Palet. The upper thin chaffy or hyaline bract
which, with the glume, incloses the flower
in Grasses.

Palisade cells, 227.

Palmate (leaf). Eadiately lobed or divided.
78.

Palmately. In a palmate manner.

Panicle. A loose, irregularly compound in-
florescence with pedicellate flowers. 142,
143.

Panicled, Paniculate. Borne in a panicle ;
resembling a panicle. 142, 143.

Papilionaceous (corolla). Having a stand-
ard, wings, and keel, as in the peculiar
corolla of many Leguminosae. 132.

Papillose. Bearing minute nipple-shaped
projections.

Pappus. The modified calyx limb in Com-
posite, forming a crown of very various
character at the summit of the achene. 149.

Parasitic. Growing on and deriving nour-
ishment from another plant. 16, 41.

Parenchyma, spongy, 227.

Parietal. Borne on or pertaining to the wall
or inner surface of a capsule. 105.

Parted. Cleft nearly but not quite to the
base. 95.

Partial. Of secondary rank.

Pectinate. Pinnatifid with narrow, closely
set segments ; comblike.

Pedate. Palmately divided or parted, with
the lateral segments 2-cleft.

Pedicel. The support of a single flower. 140.

Pedicellate. Borne on a pedicel.

Peduncle. A primary flowerstalk, support-
ing either a cluster or a solitary flower. 140.

Pedunculate. Borne upon a peduncle.

Peltate. Shield-formed and attached to the
support by the lower surface. 80, 93.

Penicillium, 192.

Pentadelphous. Of 10 stamens. 185.

Perennial. Lasting year after year. 45.

Perfect (flower). Having both pistil and
stamens. 128.

Perfoliate (leaf). Having the stem appar-

. ently passing through ^t.

268

INDEX AXD GLOSSARY

Perianth. The floral envelope, consisting of
the calyx and corolla (when present), what-
ever their form. 100, 110.

Pericarp. The matured ovary. 147.

Perigynium. The inflated sac which incloses
the ovary in Carex.

Perigynous. Adnate to the perianth, and
therefore around the ovary and not at its
base. 130, 134.

Persistent. Long-continuous, as a calyx
upon the fruit, leaves through winter, etc.

Personate (corolla). Bilabiate, and the throat
closed by a prominent palate. 133.

Petal. A division of the corolla. 110.

Petaloid. Colored and resembling a petal.

Petiolate. Having a petiole.

Petiole, the footstalk of a leaf, 73; move-
ments of, 75 ; sleep movements, 75 ; uses,
74.

Petiolule, 75.

Peziza, 162, 190.

Phaenogamous. Having flowers with stamens
and pistils and producing seeds. 13.

Phloem, 222.

Photosynthesis (Exp. 11), 66, 72.

Photosynthetic assimilation, 235.

Phyllocladiurn, 63.

Phyllodium. A somewhat dilated petiole
having the form of and serving as a leaf-
blade. 76.

Phyllotaxy, 89.

Physiology (ch. xviii.), 229.

Pileus, 194.

Pilose. Hairy, especially with soft hairs.

Pinna (pi. Pinnae). One of the primary di-
visions of a pinnate or compoundly pinnate
frond or leaf.

Pinnate (leaf). Compound, with the leaflets
arranged on each side of a common petiole.
78, 97.

Pinnatifid. Pin nately cleft. 96.

Pinnule. A secondary pinna ; oneofthepin-
nately disposed divisions of a pinna.

Pistil, 99, 104.

Pistillate. Provided with pistils, and, in its
more proper sense, without stamens. 129.

Pitcher Plants, 87.

Pitted. Marked with small depressions or
pits.

Placenta, 104.

Placentation, types of, 105.

Plasmolysis (§ 350), 158, 256.

Pleurococcus, 157, 171.

Plicate. Folded into plaits, usually length-
wise.

Plumose. Having fine hairs on each side,
like the plume of a feather, as the pappus-
bristles of Thistles.

Plumule. The bud or growing point of the
embryo. 18.

Pod Any dry and dehiscent fruit.

Pollen, 100; grain, 116, 212; growth of, 117;
of Pines, 120 ; tube, 117.

Pollination by insects, 121 ; by water, 120 ;
by wind, 120.

Polliniferous. Bearing pollen.

Pollinium (pi. Pollinia). A mass jf waxy
pollen or of coherent pollen grains, as in \
Asclepias and Orchids. 136.

Polliuoid, 1S1.

Polyadelphous. Having many stamens. 135.

Polycotyledonous embryo, 17.

Polygamous. Having flowers, some of them
perfect, some staminate or pistillate only.
129.

Polypetalous. Having separate petals. 111.
131.

Polyporus, 196.

Polysiphonia, 159.

Pome. A kind of fleshy fruit, of which the
apple is the type. 149.

Porose. Pierced with small holes or pores.

Posterior. In an axillary flower, on the side
nearest to the axis of inflorescence.

Praemorse. Appearing as if bitten off.

Preserving material, 242, 255.

Prickle. A small spine or more or less slen-
der sharp outgrowth from the bark or rind.

Procumbent. Lying on the ground.

Proliferous. Producing offshoots.

Propagation, by gemmae, 200 ; vegetative (by
stems), 58.

Prostrate. Lying flat upon the ground.

Proteid matter, in seeds, 19 ; test for, 246.

Protein granules, 216.

Proterandry, 119.

Proterogynous. Having the stigma ripe for
the pollen before the maturity of the an-
thers of the same flower. 119.

Prothalliuin, 205, 208, 209.

Protonema, 204.

Protoplasm, 116, 173, 213, 214.

Pseudaxillary. Terminal, but becoming ap-
parently axillary by the growth of a lateral
branch.

Pseudo-costate. False ribbed, as when a
marginal vein or rib is formed by the con-
fluence of the true veins.

Pteridophytes, 204.

Puberulent. Minutely pubescent.

Pubescent. Covered with hairs, especially if
short, soft, and downy.

Pulvinus, 75 ; action of, 240.

Punctate. Dotted with depressions or with
translucent internal glands or colored dots.

Puncticulate. Minutely punctate.

Pungent. Terminating in a rigid sharp
point ; acrid.

Putamen. The shell of a nut ; the bony part
of a stone fruit.

Quadrate. Nearly square in form.

Eaceme. A simple inflorescence of pediceled
flowers upon a common, more or less elon-
gated axis.

Eacemose. In racemes, or resembling a
raceme.

Eadiate. Spreading from or arranged around
a common center ; bearing ray flowers.

INDEX AND GLOSSARY

269

Kadical. Belonging to or proceeding from
the root or base of the stem near the
ground.

Eadicle. The initial root of the embryo.
Less properly, the stem of the embryo ;
below the cotyledons (caulicle). 20.

Kameal. Belonging to a branch.

Ramification. Branching.

Raphe, 153.

Eay. The branch of an umbel ; the marginal
flowers of an inflorescence when distinct
from the disk.

Receptacle. The more or less expanded or
produced portion of an axis which bears
the organs of a flower (the torus), or the
collected flowers of a head. 112.

Recurved. Curved downward or backward.

Red Algae, 159.

Reduplicate, 188.

Reflexed. Abruptly bent or turned down-
ward.

Regular. Uniform in shape or structure.
128.

Reniform. Kidney-shaped. 93.

Repand. With a slightly uneven and some-
what sinuate margin. 95.

Reproduction, 174 ; asexual, 183 ; carpospo-
ric, 1S2 ; oosporic, 182 ; sexual, 183 ; zygo-
sporic, 182.

Resiniferous. Producing resin.

Respiration (Exp. 2), 10, 236 ; in leaves, (Exp.
12), 66 ; in germination, 20.

Resting periods, 238 ; in buds, 80 ; seeds, 19.

Reticulate. In the form of network; net-
veined. 77.

Retrorse. Directed back or downward.

Retuse. With a shallow notch at a rounded
apex. 94.

Revolute. Rolled backward from the mar-
gins or apex.

Rhachis. The axis of a spike or of a com-
pound leaf. 70.

Rhizome. Any prostrate or subterranean
stem, usually rooting at the nodes and be-
coming erect at the apex. 50, 59.

Rhizopus, 160, 186.

Rhombic, Rhomboidal. Somewhat lozenge-
shaped ; obliquely four-sided.

Rib. A primary or prominent vein of a leaf.
77.

Ringent. Gaping, as the mouth of an open
bilabiate corolla. 133.

Rockweed, 158, 178.

Root, anatomy, 229 ; conduction (Exp. 7), 85 ;
geotropism, 11 ; gross anatomy, 84; grow-
ing point, 89 ; laboratory studies, 84 ; pri-
mary, 36 ; origin, 36.

Root cap, 39.

Root hairs, 22 ; action of, 88.

Root pressure, 233 ; (Exp.), 35 ; (Exp.), 249.

Roots, absorption, 37 ; adventitious, 87 ;
aerial, 39 ; as holdfasts, 42 ; climbing, 85,
42 ; duration of, 44 : for storage, 43 ; func-
tions, 37 ; growth (Exp.), 249 ; origin of
new, 229 ; parasitic, 40 ; storage, 85.

Rootstock. Same as Rhizome. 59.

Rostrate. Having a beak or spur.

Rosulate. In the form of a rosette.

Rotate (corolla). W heel- shaped ; flat and
circular in outline. 181.

Rotund. Rounded in outline.

Rudiment. A very partially developed or-
gan ; a vestige.

Rudimentary. But slightly developed.

Rufous. Reddish brown.

Rugose. Wrinkled.

Runcinate. Sharply incised, with the seg-
ments directed backward.

Runner. A filiform or very slender stolon.
58.

Rusts, 192.

Saccate. Sac-shaped.

Sac, embryo, 118 ; pollen, 108 ; fungi, 190.

Sagittate. Shaped like an arrowhead, the

basal lobes directed downward. 93.
Salver-shaped (corolla). Having a slender

tube abruptly expanded into a flat limb.

131.

Samara. An indebiscent, winged fruit. 150.
Sap, ascent of (Exp. 8), 49, 288.
Saprolegniaceae, 188.
Saprophytes, 39.
Scabrous. Rough to the touch.
Scape. A peduncle rising from the ground,

naked or without proper foliage.
Scapose. Bearing or resembling a scape.
Scarious. Thin, dry, and membranaceous,

not green.
Sclerotic cells, 220.
Scorpioid (inflorescence). Circinately coiled

while in the bud. 143.
Seed, 152; appendages, 155; ecology, 158;

origin, 15 ; processes leading to formation

of, 116 ; study of, 7, 145.
Seed coats, how removed by seedling, 22.
Seedlings, development, 12, 20.
Seed plants, 14.
Seed rudiments (ovules), 15.
Seeds, dispersal, 158; ejected, 155; from

mummy cases, 19 ; in forest soil, 19 ; rest-
ing state, 19 ; store of food, 19 ; vitality,

19.
Segment. One of the parts of a leaf or other

like organ thaj is cleft or divided, 96.
Selaginella, 166, 207.
Self-fertilization. 118 ; prevented, 119.
Sensitive Plant (Exp. 19), 68.
Sepal. A division of a calyx. 110.
Septicidal (capsule). Dehiscing through the

partitions and between the cells. 151.
Septifragal. The valves breaking from the

septa in dehiscence. 151.
Septum. Any kind of partition.
Sequoias, 63.

Serrate. Having teeth pointing forward. 94.
Serrulate. Finely serrate.
Sessile. Without footstalk of any kind.
Setaceous. Bristlelike.
Setose. Beset with bristles.

270

INDEX AND GLOSSARY

Setulose. Having minute bristles.

Sexual reproduction. 183.

Sheath. A tubular envelope, as the lower
part of the leaf in Grasses.

Sheathing. Inclosing as by a sheath.

Shoot, 14 ; metamorphosed (§§ 87-99), 58.

Shrub. A woody perennial, smaller than a
tree.

Sieve tubes, 238.

Silicle. A short silique.

Silique. The peculiar pod of Cruciferae.

Silky. Covered with close-pressed, soft, and
straight pubescence.

Simple. Of one piece ; not compound.

Sinuate. With the outline of the margin
strongly wavy. 95.

Sinus. The cleft or recess between two
lobes. 80.

"Sleep of Plants," 76.

Sleep movements, 75; of leaf (Exp. 18), 68.

Smooth. Without roughness or pubescence.

Sorus (pi. Sori). A heap or cluster, applied
to the fruit dots of Ferns. 205.

Spadix. A spike with a fleshy axis. 126,
141.

Spathe. A large bract or pair of bracts in-
closing an inflorescence. 126.

Spatulate. Gradually narrowed downward
from a rounded summit. 93.

Spermatophytes, 14.

Spicate. Arranged in or resembling a spike.

Spiciform. Spikelike.

Spike. A form of simple inflorescence with
the flowers sessile or nearly so upon a more
or less elongated common axis. 141.

Spikelet. A small or secondary spike.

Spine. A sharp woody or rigid outgrowth
from the stem.

Spinose. Spinelike, or having spines.

Spirogyra, 157, 173.

Spongy parenchyma, 227.

Sporangium. A spore case. 205.

Spores, 181, 182, 187, 191, 201, 205.

Sporidia, 194.

Sporocarp. The fruit cases of certain Cryp-
togams containing sporangia or spores.

Sporogonium, 201.

Sporophylls, 212.

Sporophyte, 207.

Spur. A hollow saclike or tubular extension
of some part of a blossom, usually nectar-
iferous.

Squamula. A reduced scale, as the hypogy-
nons scales in Grasses.

Squarrose. Having spreading and project-
ing processes, such as the tips of involucral

Squarrulose. Diminutively sqnarrose.

Stability of plant body, 230.

Stamen. One of the pollen-bearing or fer-
tilizing organs of the flower. 108.

Stamens, study of, 100.

Staminate (flower). Possessing stamens and
no pistil. 129.

Staminodium. A sterile stamen,, or any

structure without anther corresponding to
a stamen.

Standard. The upper dilated petal of a pa-
pilionaceous corolla.

Starch, 216; formation (Exp. 11), 66; in
seeds, 19 ; observation, in laboratory, 250 ;
test, 9.

Stellate, Stelliforrn . Star-shaped.

Stem, 51 ; anatomy, 223 ; ascent of sap (Exp.
8), 49 ; characteristic features, 46 ; endog-
enous, 223 ; exogenous, 223 ; geotropism
(Exp. 9), 49; growth in, 48; heliotropism,
49 (note) ; internal structure, 46 ; labora-
tory studies, 45.

"Stemless" plants, 56.

Stems, as foliage, 61 ; creeping, 57 ; for prop-
agation, 58 ; growth of, 52 ; twining,
53.

Sterile. Unproductive, as a flower without
pistil, or stamen without an anther.

Stigma, 104, 107.

Stigmatic. Belonging to or characteristic of
the stigma.

Stimulus, 240.

Stipe. The stalklike support of a pistil;
the leaf stalk of a Fern ; the stalk of a Toad-
stool. 194.

Stipitate. Having a stipe.

Stipular. Belonging to stipules.

Stipulate. Having stipules.

Stipules, 73 ; as thorns, 73 ; of Acacias, 73 ;
of the Pea, 69.

Stolon. A runner, or any basal branch that
is disposed to root. 58.

Stoloniferous. Producing stolons.

Stomates, 199, 228 ; action, 233.

Storage, 236 ; in leaves, 70.

Striate. Marked with fine longitudinal lines
or ridges.

Strict. Yery straight and upright.

Strigose. Beset with appressed sharp straight
and stiff hairs.

Strobile. An inflorescence marked by im-
bricated bracts or scales, as in the Hop and
the Pine cone.

Strophiole. An appendage at the hilum of
certain seeds.

Style, 104.

Stylopodium. A disklike expansion at the
base of a style, as in Umbelliferae.

Sub-. A Latin prefix, usually signifying
somewhat or slightly.

Subulate. Awl-shaped.

Succulent. Juicy, fleshy.

Suffrutescent. Slightly or obscurely shrubby.

Suffruticose. Very low and woody ; diminu-
tively shrubby.

Sugar, in seeds, 19.

Sulcate. Grooved or furrowed.

Sundew, 86.

Superior (ovary). Free from the calyx, 130.

Suspended (ovule). Hanging from the apex
of the cell.

Suture. A line of dehiscence.

Syconium, 151.

INDEX AXL> GLOSSARY

271

Symbiosis, 197.

Symmetry, deviations from, through light

adjustment (§ 113), 74.
Sympodium, 143.
Syngenesions, 135.

Synonym. A superseded or unused name.
Systematic botany, 253.

Teguments, 137.

Teleutospore, 194.

Temperature, influence on germination, 11.

Tendrils, 54; sensitiveness, 55.

Tension of tissues, 230.

Terete. Cylindrical.

Terminal. At or belonging to the apex.

Ternate. In threes. 98.

Testa, 152 ; outgrowths of, 145.

Tetradynamous. Having four long and two

shorter stamens. 135.
Tetraspore, 181.
Tetragonal. Four-angled.
Text-books, 244, 255.
Thallophytes, 169.
Thallus. In Cryptogams, a cellular expansion

taking the place of stem and foliage. 169.
Throat. The orifice of a gamopetalous co-
rolla.
Thyrse. A contracted or ovate, and usually

compact, panicle. 143.
Thyrsoid. Resembling a thyrse.
Tissues, 221.
Tissue tension, 230.
Topics, supplementary, 12, 33, 35.
Tomentose. Densely pubescent, with matted

wool.
Torose. Cylindrical, with contractions at

intervals.

Torulose. Diminutive of Torose.
Torus. The receptacle of a flower.
Transfer of plant food, 236.
Transfer of water in plant, 232.
Translocation of organic substances (trans-
fer), 233, 236.

Transpiration (Exps. 13, 14, 15, 16), 66, 67.
Trees, Big, of California, 63 ; longevity of, 63.
Triandrous. Having three stamens. 135.
Trichogyne, 181.
Trichomes, 28, 229.

Trifoliolate. Having three leaflets. 98.
Trigonous. Three-angled.
Trimorphous. Occurring under three forms.
Triquetrous. Having three salient angles,

the sides concave or channeled.
Truncate. Ending abruptly, as if cut off

transversely. 94.
Tuber. A thickened and short subterranean

branch, having numerous buds or eyes. 50,

59.

Tubercle. A small tuber or tuberlike body.
Tuberiferous. Bearing tubers.
Tuberous. Having the character of a tuber ;

tuberlike in appearance.
Tumid. Swollen.
Tunicated. Having concentric coats, as an

onion.

Turbinate. Top-shaped ; inversely conical.
Turgidity (§ 108), 73, 230 ; changes of, 240.
Twiners, 53.

Ulothrix, 172.

Umbel. An inflorescence in which a cluster

of peduncles or pedicels spring from the

same point. 140.
Umbellate. In or like an umbel.
Umbonate. Bearing a stout projection in

the center ; bossed.
Undulate. With a wavy surface; repand.

95.
Unguiculate. Contracted at base into a

claw.

Unifoliolate, 98.
Unisexual. Of one sex, either staminate or

pistillate only. 128.
Urceolate. Hollow and cylindrical or ovoid,

and contracted at or below the mouth, like

an urn.

Uredospore, 198.
Utricle. A small, bladdery, 1-seeded fruit;

any small, bladderlike body.

Vacuoles, 215.

Valvate. Opening by valves, as a capsule ;
in aestivation, meeting by the edges without
overlapping. 138.

Valve. One of the pieces into which a cap-
sule splits. 151.

Vascular. Furnished with vessels or
ducts.

Vaucheria, 158, 175.

Vegetative propagation, 58, 200.

Veinlets, 77.

Veins. Threads of fibro-vascular tissue in a
leaf or other organ, especially those which
branch (as distinguished from nerves).
77.

Venation, 70 ; of leaf, 76.

Ventral. Belonging to the anterior or inner
face of an organ ; the opposite of dorsal.

Ventral suture, 114.

Venus' s Flytrap, 88.

Vernation. The arrangement of leaves in the
bud.

Verrucose. Covered with wartlike eleva-
tions.

Versatile (anther). Attached near the mid-
dle, and turning freely on its support. 135.

Verticfflate. Disposed in a whorl. 90.

Vesicle. A small bladder or an air cavity.

Vesicular, Vesiculoser Composed of or
covered with vesicles. ^

Villous. Bearing long and soft hairs.

Virgate. Wand-shaped; slender, straight,
and erect.

Vitality of seeds, 19.

Water, in germination, 20.

Water Mold, 161, 188.

Whorl. An arrangement of leaves, etc., in

a circle round the stem, 90.
Wing. Any membranous or thin expansion

272

INDEX AND GLOSSARY

bordering or surrounding- an organ ; the

lateral petal of a papilionaceous corolla.
"Wood, annual layers, 224 ; structure of, 48,

219.
Woolly. Clothed with long tortuous or

matted hairs.

Xerophytes, 65.
Xylene, 222.

Yeast, 160.
Yeasts, 186.

Zoosporangia, 178.
Zoosporangium, 189.
Zoospores, 172, 175, 179, 189.
Zygoinorphic, 129.

Zygospores, 172, 174, 183; of Sporodinia,
357.

f UNIVERSITY J

14 DAY USE

RETURN TO DESK FROM WHICH BORROWED

LSbirairy

This book is due on the last date stamped below, or

on the date to which renewed.
Renewed books are subject to immediate recall.

MAR 1 9 1959

•r

General Library

/