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DEPARTMENT OF BOTANY 
COLLEGE OF AGRICULTURE 


Laboratory Copy. 
Compliments of the Publishers 


CORMELL UNIVERSITY LIBRARY 


I 


Cornell University 


Library 


The original of this book is in 
the Cornell University Library. 


There are no known copyright restrictions in 
the United States on the use of the text. 


http://www.archive.org/details/cu31924089570414 


LESSONS IN BOTANY 


BY 


GEORGE FRANCIS ATKINSON, Px.B. 


Professor of Botanv in Cornell University 


NEW YORK 
HENRY HOLT AND COMPANY 


1908 
EL. 


Copyright, 1900, 
BY 
HENRY HOLT & CO. 


ROBERT DRUMMOND COMPANY, v.1\TERS, NeW YORK 


PREFACE. 


Tuts abbreviated and simplified edition of my Elementary 
Botany has been prepared for the use of pupils in the secondary 
schools, where short, or half-year, courses in botany are given, 
and where, for one reason or another, my larger book cannot 
be adapted to such abbreviated courses. A large part of the 
‘matter has been rewritten, only the less technical .descriptive 
portions being retained. 

The subject-matter is arranged for three different uses: exer- 
cises for the pupils, demonstrations by the teacher, and descrip- 
tive matter for reading and reference. To clearly set apart, for 
the convenience of the teacher and pupil, the work suggested, 
for each, all the work outlined for the teacher is placed under 
the head of demonstration, whether the setting up of apparatus or 
an actual demonstration before the class; so also all the prac- 
tical work of the pupils, whether an experiment or an ordinary 
exercise, is put under the head of exercise. The demonstrations 
and the exercises each have their own consecutive numbering, 
so that the teacher can tell at a glance the subdivisions of the 
work. Where there are a sufficient number of microscopes, so 
that one can be allotted to two or three pupils, many of the 
demonstrations can be used as exercises, at the discretion of the 
teacher. All the paragraphs, whether descriptive, demonstration 
or exercise, have a separate and consecutive numbering. 

The first chapter in this abbreviated book is devoted to a 
study of how seedlings grow from the seed, and this is followed 
by a chapter on shoots, buds, etc., in order to give an oppor- 
tunity for some out-door work if the season is propitious, or for 

poet 


iv PREFACE. 


the study of material easily collected. This emphasizes the de- 
sirability of supplementing the regular laboratory course with 
the out-door work, or with observations on material suitable to be 
employed in out-door work when conditions permit. The third 
chapter then treats of protoplasm (the living substance) in the 
root hairs of seedlings, followed by a similar study in spirogyra. 
In the following chapters much the same order is used as in the 
larger book, but there has been an attempt to simplify the 
treatment. Very much of the technical matter in the larger 
book has been omitted here, and in consequence much of the 
matter which is useful for reference to those who desire supple- 
mentary reading and explanations. For this matter the larger 
Elementary Botany should be consulted. 

The studies indicated in the part on ecology are not intended 
to be pursued as a distinct and separate piece of work, but they 
may be made the basis of excursions during the progress of the 
work on physiology and morphology. It is possible to indicate 
definitely where some of these out-door studies are applicable. 
At the same time the retention of the third part as a distinct 
subdivision of the book serves to emphasize the importance of 
ecological study, or perhaps rather of the study of plant life on 
a larger scale, and some of the interesting problems connected 
with the environmental influences on plant life and plant com- 
munities. It should be recognized that plant distribution, as 
well as many of the other important problems connected with 
ecological study, cannot be carried on in the secondary schools 
with the rigid system applicable in the college or university, or 
even with the precision which the student of ecology would 
desire, since a considerable previous technical knowledge of 
plants would be necessary. The chief importance of the study 
in the secondary schools is, I believe, to get the pupil interested 
in observing living plants, and in gaining a general impression 
of the fundamental laws, and in leading the pupil to realize, in a 
measure, the great influence which environment has on living 
beings. 


PREFACE. v 


It is suggested that the teacher, at the beginning of the work, 
take some account of the time to be allotted to the different 
subjects of the course. For example, in a 20-weeks’ course, 
7 to 8 weeks could be devoted to physiology, 5 or 6 weeks 
could be devoted to general morphology; while 6 or 8 weeks 
could be devoted to the study of plant families. As the work 
progresses it can be easily seen whether or not all the exercises 
and demonstrations can be gotten in during the allotted time. 
If the time is too short in some cases, the teacher can then 
arrange to omit certain of the exercises in each chapter, so that 
as a whole the work can be completed in the desired time. 
Some of the chapters are intended for reading and reference 
only. These are indicated at the beginning of the chapters in 
question. They should not be taken into account when consid- 
ering the amount of practical work to be done by the pupil. 


CoRNELL UNIVERSITY, 
January, 1900. 


MATERIAL FOR LABORATORY ILLUSTRATION. 


HIGH SCHOOL BOTANICAL SET. 
Special net price, $20. Express extra. 


PERMANENT Mounts. 


Those on cards are protected with fly-leaf and placed together in 
a neat portfolio. 


Pond scum (Spirogyra) on card... ... cece ee ee cece cee eee 
Green felt (Vaucheria) on Card . 6... 6. cee cece eee eee ee eee 
Wheat rust (Puccinia), three stages, on card .........--....065 
Carnation rust (Uromyces) on card ......e eee cece eee eee 
Dodder (Cuscuta) on card: :.csaeies sesseeaws aided ses pees 
Mildew (Uncinula) on card...... 2... cece ee eee eee eee 
Lichéit thallus: OmCatd 5.0. 5...cieie wee cposrebn east eens auveisueyevayes a muevnisin 


CATA isait cis anh ava ae Shara Oe eseishte ted Dostana Avante 4 aos at onfelel's 
Liverwort—mature fruit (Sporogonia) carefully preserved in fluid 

for exhiblHOnie. se.c2 ces Hadar tina ee een sear eere were 
Moss (Polytrichum)—male, female, and fruiting plant on card.... 
Fern (Polypodium)—whole plant on card.........20...ee0eeee- 
Horsetail (Equisetum)—fertile and sterile plants on card........ 
Quillwort (Isoetes)—whole plant on card ... 2.0.6... 06sec eee eee 
Quillwort (Isoetes)—plant in section preserved in fluid ......... 
Pine—male and female flowers and mature scale with seed on card 
Trillium—mature plant on card... .... eee eee eect eee eee 
Toothwort (Dentaria)—plant on card ....... 6... eee eee eee eee 


Microscopic PREPARATIONS. 


Corn—cross-section of stem showing bundles................4. 
Corn—longitudinal section of stem showing bundles............ 
Sunflower—cross-section of stem showing bundles.............. 
Sunflower—longitudinal section of stem showing bundles........ 
Caladium—cross-section of leaf stalk showing bundles .......... 
Celery—cross-section of leaf stalk showing bundles............ - 
Celery—longitudinal section of leaf stalk showing bundles....... 
Ivy—cross-section of leaf... cisccwccg cores sete acdwe gene nese 
Begonia—cross-section of leaf... 21... eee eee eee eee 
Pond scum. (Spirogyra) in fruit... 2.0.0... e eee ee eee eee ee eee 
Green felt (Vaucheria) in fruity ++ coeqemaesaee ee 93 He tieg comics 
Green felt (Vaucheria)—sexual organs...........00. cece eee ee 
Black mould (Rhizopus)—rhizoids, sporangia, and columella .... 
Willow mildew (Uncinula)—perithecia crushed and stained to show 

asci and spores...... Pasar api sataresl Spehaiine diemveaubsel asd oumetne ieee 
Carnation rust—sections showing haustoria.................... 
Dodder (Cuscuta)—sections showing haustoria ................ 
Wheat rust (Puccinia)—sections of cluster cup................. 
Wheat rust (Puccinia)—sections of red rust 
Wheat rust (Puccinia)—spores of black rust 


vi 


MATERIAL FOR LABORATORY ILLUSTKATION. Vii 


Brought forward. ..... ...eesseee ee eens oe 9G Sethe Aeon $14.60 
Lichen (Peltigera)—section of thallus. ...........0-eeeeeeeeeen .40 
Liverwort (Marchantia)—section of antheridia................. 75 
Liverwort (Marchantia)— section of archegonia ................ “75 
Liverwort (Marchantia)—spores and elaters .............+5...4- -40 
Moss (Mnium)—section of antheridia............00-c ee eeeeeee “75 
Moss (Mnium)—section of archegonia ........... eee ee sees ee ee 75 
Moss capsule showing teeth (peristome) and spores.............. -50 
Fern (Polypodium)—cross-section of stem......... Lee e see eee -40 
Fern (Polypodium)—longitudinal section of stem............... -40 
Fern (Pteris)—cross-section of stem ..... 0... eee eee eee ee -40 
Fern (Pteris)—longitudinal section of stem..............0...8- -40 
Fern—sporangia and spores. ........ 0c esse eee cece eee eens -40 
Fern—germinating spores... 0.6.0... cee ee eee cee eee eee nee 50 
Fern—prothallium with sexual organs............... Riserva tata 75 
Fern—prothallium with attached embryo. . 75 
Horsetail (Equisetum)—spores and elaters -40 
Quillwort (Isoetes)—section of microsporangia...............- 75 
Quillwort (Isoetes)—section of macrosporangia................. “75 
Pine—mature pollens. 2s. csssvceee cesses wansesmee oy svesee ss -40 
Pine—fruiting scale at time of pollination ..................... -40 
Pine—prothallium with archegonia, and pollen tube in nucellus.. .75 
Trillium pollen. .acc.o. sees ciieaia om eareainarees asa eiaisansaee yea dew ate ese 440 
Trillium—section of anther ..........- ‘sepeniene adaee sik eedeals wai -40 
Trillium—section of pistil showing locules and ovules.......+--. +50 
Lilium—embryo-sac in section... 0... cc. cee ee eee eee eee eee “75 
Dentaria—section of pistil showing locules and ovules .......... -50 

$27.50 


or the entire set for $20.00. 
DuPpLicATE MATERIAL FREE WITH SET. 


Pond scum (Spirogyra) in fruit. 

Green felt (Vaucheria) in fruit. 

Wheat rust—two stages on wheat and a cluster cup to represent the stage 
on barberry. 

Powdery mildew. 

Liverwort (Conocephalus). 

Moss (Polytrichum)—male, female, and fruiting plant. 

Fern (Polypodium)—pressed plants, and sporangia in formalin, 

Horsetail (Equisetum)—sterile and fertile plants. 

Quillwort (Isoetes)—plants in formalin. 

Pine—mature male and young female cones in formalin. 


These prepared slides, and other material, for laboratory work, can 
be obtained of the Ithaca Botanical Supply Co., Ithaca, N. Y. They 
are especially adapted to illustrate Lessons IN Borany, as well as the 
author’s larger ‘‘ Elementary Botany.” 

A supplementary list of supplies representing additional topics treated 
of in ‘Elementary Botany,” can be had on application to the Ithaca 
Botanical Supply Co. 


' TABLE OF CONTENTS. 
PART I: PHYSIOLOGY. 


CHAPTER I. 


How THE SEEDLING GROWS FROM THE SEED.......0006 eeees es 


CHAPTER II. 


WINTER BUDS, SHOOTS, ETC. ...... 0. cece cee ce seen ccccaes Satis 


CHAPTER III. 


THE LIVING SUBSTANCE OF PLANTS ............000008 beleeease 
I. Protoplasm in root hairs of seedlings. 


CHAPTER IV. 


THE LIVING SUBSTANCE OF PLANTS, CONTINUED........+ saees 
II. Protoplasm in an alga: Spirogyra, 


CHAPTER V. 


THE LIVING SUBSTANCE OF PLANTS, CONCLUDED...........05.4 
III. Protoplasm in a fungus: Mucor. 


CHAPTER VI. 


How WATER MOVES IN AND OUT OF PLANT CELLS............ 
Absorption, diffusion, osmose. 


PAGES 


15-18 


19-23 


24-27 


x TABLE OF CONTENTS. 


CHAPTER VII. 


PAGES 
How PLANTS OBTAIN THEIR LIQUID FOOD.......00-.s0eeee eee 34-44 
I, Water culttiresicen aig. cociimiewads heaeass gees eee s 34-36 
I. How plants obtain food from the soil..............0+0-- 36-41 
II. Strong solutions of plant food are injurious............. 41-44 
CHAPTER VIII. 
How SOME PLANT PARTS REMAIN RIGID. .......0.eeeceeeeeeee 45-49 
CHAPTER IX. 
How WATER MOVES THROUGH THE PLANT............0000000- 50-55 
I. Root pressure or osmotic pressure... 2.0... 2.2.2 eee eee ee 50-51 
I. The loss of water by plants (transpiration).............. 51-55 
CHAPTER X. 
How WATER MOVES THROUGH THE PLANT, CONCLUDED.... 56-60 
WI. Part which the leaf plays in transpiration. 
CHAPTER XI. 
PATH OF MOVEMENT OF LIQUIDS IN PLANTS........ cesses e ee 61-69 
CHAPTER NII. 
HOw PLANTS GET THEIR CARBON FOOD. ....-.00. cece cee eeeeee 70-73 
I. The gases concerned. 
CHAPTER XIII. 
How PLANTS GET THEIR CARBON FOOD, CONCLUDED........... 74-80 


II. Starch formed by green plants. 


CHAPTER XIV. 


ROUGH ANALYSIS OF PLANT SUBSTANCE..........000000 02000 ee 81-83 


TABLE OF CONTENTS. xi 


CHAPTER XV. 


PAGES 
SOME OTHER WAYS IN WHICH CERTAIN PLANTS OBTAIN FOOD... 84-93 
CHAPTER XVI. 
RESPIRA TIONS Gy saiwraieicia dose tigulew aie sau ucennnen mae odour ental 94-101 
CHAPTER XVII. 
GROWTH os ecichisnenationenoces var nese euenenes «aw 4 eaekaeet 102-106 
CHAPTER XVIII. ! 
MOVEMENT IN PLANTS DUE TO IRRITABILITY..........000..00- 107-114 


PART II: MORPHOLOGY AND LIFE HISTORY 
OF REPRESENTATIVE PLANTS. 


CHAPTER XIX. 


SPIROGYRA pw escciss geri adntgraiad padmemagemananne cei HAY tere 115-119 


CHAPTER XX. 


THE GREEN FELT: VAUCHERIA... 1... cece cee cence en eneeee eee 120-124 


CHAPTER XXL 


FUNGI: THE BLACK MOULD......-6..- 50+ cee eee eee eee re eeee 175-128 


CHAPTER XXII. 


FUNGI, CONTINUED : WHEAT RUST (PUCCINIA GRAMINIS).......- 129-133 


CHAPTER XXIII. 


FUNGI, CONCLUDED : THE WILLOW MILDEW (UNCINULA SALICIS). 134-138 


Xi TABLE OF CONTENTS. 


CHAPTER XXIV. 


PAGES 
LIVERWoRTS : HEPATIC (MARCHANTIA POLYMORPHA).......-+. 139-148 
CHAPTER XXV. 
MossEs : MUSCI (POLYTRICHUM OR MNIUM)..........00eeeeeee. 149-154 
CHAPTER XXVI. 
FERNS: FILICINE# (THE POLYPODY OR CHRISTMAS FERN)....... 155-165 
CHAPTER XXVII. 
FERNS, CONCLUDED: THE SEXUAL STAGE OF FERNS........+-+. 166-173 
CHAPTER XXVIII. 
HorsETAILS : EQUISETINEZ (THE FIELD EQUISETUM)....+...0005 174-179 
CHAPTER XXIX. 
QUILL WORTS:: ISOETES  .iie.o dscns bn Wiameaset nae avaueiolaln. ocgse a aie WSS 180-183 
CHAPTER XXX. 
GYMNOSPERMS : THE WHITE PINE......0- see e cece ee eee ee eee 184-193 
CHAPTER XXXI. 
MoRPHOLOGY OF THE ANGIOSPERMS: TRILLIUM; DENTARIA..... 194-202 
CHAPTER XXXII. 
PROTHALLIUM AND SEXUAL ORGANS OF FLOWERING PLANTS.... 203-207 


CHAPTER XXXIII. 


SEEDS AND SEPDLINGS saa0.t0 cdg newelngreek aug nae aaGnee He 208 216 


TABLE OF CONTENTS. xiii 


CHAPTER XXXIV. 
PAGES 
THE PLANT BODY AND SOME OF ITS MODIFICATIONS...... aegis 217-220 


CHAPTER XXXvV. 


ARRANGEMENTS OF THE PARTS OF THE FLOWER..... eovscveces 221-224 


CHAPTER XXXVI. 


5 RELATIONSHIPS SHOWN BY FLOWER AND FRUIT..... Cooeene sees 225-230 


CHAPTER XXXVII. 


CLASSIFICATION (OR TAXONOMY)........+ ee eneeee eee cecesccees 23E—-235 


STUDIES ON PLANT FAMILIES. 


MONOCOTYLEDONES ..+eee.seeeees 236-249 


CHAPTER XXXVIII. 


Toric I: MoNOCOTYLEDONES WITH CONSPICUOUS PETALS (PETA- 
LOUDESE) ae 'eiice: secinisrspeeiss wed guiein eee ee se aa Sieesiewe 236-242 
Order Lilifloree : Family Lilisesas the lily family. 
Order Gynandre : Family Orchidacez ; the orchid family. 


CHAPTER XXXIX. 


Topic Il: MONOCOTYLEDONES WITH FLOWERS ON A SPADIX (SPA- 
TCT O RUA) has Se se nisueisey ode ens aa 4- succes Sragonrs wlecer Sra ane eh am eeRINS 243-246 
Family Aracez ; the arum family. 


CHAPTER XL. 


Toric III: MoNOCOTYLEDONES WITH A GLUME SUBTENDING THE 
FLOWER (GLUMIFLORA!)... 1... see cess teen eeeceee ees neee 247-249 
Family Graminee ; the grass family, 


xiv TABLE OF CONTENTS. 


DICOTYLEDONES......-eeeeseeeees 250-283 


CHAPTER XLI. 


Topic IV: DIcoTYLEDONES WITH DISTINCT PETALS, FLOWERS IN 
CATKINS OR AMENTS ; OFTEN DEGENERATE,..........00+ 250-254 
Order Amentiferze: Family Salicacez ; the willow family. 
Family Cupuliferze ; the oak family. 


CHAPTER XLII. 


Toric V: DICOTYLEDONES WITH DISTINCT PETALS AND HYPOGY- 
NOUSERLOWERS ass: ca 'vieg' are detees dee daietetn ieee damisiatetetsiers 255-261 
Order Urticiflorze : Family Ulmacez ; the elm family. 
Order Polycarpice : Family Ranunculacez ; the crowfoot 
family. 
Order Rhceadinz : Family Cruciferz ; the mustard family. 
Order Cistifloree : Family Violacez ; the violet family. 


CHAPTER XLIII. 


Toric VI: DIcoTYLEDONES WITH DISTINCT PETALS AND PERIGY- 
NOUS OR EPIGYNOUS FLOWERS ws «cceeeews cane esd edaes eed 262-264 
Order Aisculine : Family Aceracez ; the maple family, 


CHAPTER XLIV. 
Topic VI, CONTINUED.............000 Sieuaeasa usu atti ayo inerchdnar bedydecsee 265-270 
Order Rosiflorze: Family Rosacee ; the rose family. 
Family Amygdalacee ; the almond family. 
Family Pomacee ; the apple family. 
Order Leguminosz : Family Papilionacez ; the pea family. 


Topic VII: DicoTYLEDONES WITH DISTINCT PETALS AND EPIGY- 


NOUS) HEOWERS? wens jal hate A pecmeoasiedinmnradaranoas 271-273 
Order Myrtiflorze : Family Onogracez ; the evening-primrose 
family, 
SYMPETAL ABs cise se senuneseeaes 274-282 


CHAPTER XLV. 
Topic VIII: DicoTYLEDONES WITH UNITED PETALS, FLOWER 
PARTSHIN FIVE WHORLS pieinss.aa9 #04599 1G DAGe ed adda s 8 274 
Order Bicornes: Family Vacciniaceze ; the whortleberry 
family. 


TABLE OF CONTENTS. xv 


PAGES 
Topic IX: DicoTYLEDONES WITH UNITED PETALS, FLOWER PARTS 
INU EOUR, WHORLS jo) o.cjrnigecnsvesialutorers cules ates alee Sage leg Rae 275-277 
Order Tubifloree : Family Labiate ; the mint family. 
Order Personatz : Family Scrophulariacez; the figwort family. 


CHAPTER XLVI. 


Topic IX, CONTINUED, ..........0ce cece een eee eee ecsee ees 278-282 
Order Aggregate: Family Composite ; the composite family. 


PART III: ECOLOGY. 


INTRODUCTION. js. o:oxas5 cessed aieneraiessuteiby avai aanians sianvalowulaniecs cow wiberdaecahike 283-201 
Suggestions for ecological study. 


CHAPTER XLVII. 


SEED: “DISERIBUDION si wi oais sinvdee ce lacecc ste eye auseaia Riecezayeseuthels mitcerere\nbokiecs 292-299 


CHAPTER XLVIII. 


STRUGGLE FOR OCCUPATION OF LAND........ cece cee eevee eeees 300-305 


CHAPTER XLIX. 


ZONAL DISTRIBUTION OF PLANTS.......0. 00 ccc ee eee e cscs eenee 306-310 
CHAPTER L. 

SOIL FORMATION IN ROCKY REGIONS AND IN MOORS.........+. 311-327 
CHAPTER LI. 

PLANT COMMUNITIES ; SEASONAL CHANGES...... 0.000. 0seceeeee 328-336 


CHAPTER LII. 


ADAPTATION OF PLANTS TO CLIMATE. ....-2...-2-..000005 sees 337-341 


APPENDIX... cassie caeccd aie, ove 343-353 
GLOSSARY since iacn eivessancees oiace ai wien 355-360 


BOTANY. 


PART I. PHYSIOLOGY. 


CHAPTER I. 
HOW THE SEEDLING GROWS FROM THE SEED. 


1. Since the seedling plant is useful in illustrating several of 
the life processes of plants we may well begin with some studies 
of germinating seeds. We may take for the first example the 
pumpkin seedling, and then follow with several others in order 
to become familiar with the parts of the seedling plant before 
we study the life processes, 


THE PUMPKIN SEEDLING. 


Demonstration I. 


2. To prepare seeds for germination.—Soak,a handful of seeds (or more if 
the class is large) in water for twelve to twenty-four hours. Take shallow 
crockery plates, or ordinary plates, or a germinator with a fluted bottom. 
Place in the bottom some sheets of paper, and if sphagnum moss is at 
hand scatter some over the paper. If the moss is not at hand, throw the 
upper layer of paper into numerous folds. Thoroughly wet the paper and 
moss, but do not have an excess of water. Scatter the seeds among the 
moss or the folds of the paper. Cover with some more wet paper and 
kecp in a room where the temperature is about 20° C. to 25°C. The ger- 
minator should be looked after to see that the paper does not become dry. 
It may be necessary to cover it with another vessel to prevent the too rapid 
evaporation of the water. The germinator should be started about a week 
before the seedlings are wanted fer study. Some of the soaked seeds should 
be planted in soil in pots and kept at the same temperature, for comparison 
with those grown in the germinator. 


2 BOTANY. 


3. Structure of the pumpkin seed.—The pumpkin seed has 
a tough papery outer covering for the protection of the embryo 
plant within. This covering is made up of the seed coats. 
When the seed is opened by slitting off these coats there is seen 
within the ‘‘meat’’ of the pumpkin seed. This is nothing 
more than the embryo plant. The larger part of this embryo 
consists of two flattened bodies which are more prominent than 
any other part of the plantlet at this time. These two flattened 
bodies are the two first leaves, usually called cotyledons. If we 
spread these cotyledons apart we see that they are connected at 
one end. Lying between them at this point of attachment is a 
small bud. This is the plumule. The plumule consists of the 
very young leaves at the end of the stem which will grow as the 
seed germinates. At the other end where the cotyledons are 
joined is a small projection, the young root, often termed the 
radicle. 

4, How the embryo gets out of a pumpkin seedi—To see 
how the embryo gets out of the pumpkin seed we should 
examine seeds germinated in the folds of damp paper or on damp 
sphagnum, as well as some which have been germinated in earth. 
Seeds should be selected which represent several different stages 
of germination. 


Germinating seed of pumpkin, showing how the heel or “ peg ” catches on the seed coat 
to cast it off. 


5. The peg helps to pull the seed coats apart.—The root 
pushes its way out from between the stout seed coats at the 
smaller end, and then turns downward unless prevented from so 


HOW THE SEEDLING GROWS FROM THE SEED. 3 


doing by a hard surface. After the root is 2-4cm long, and the 
two halves of the seed coats have begun to be pried apart, if we 
look in this rift at the 
junction of the root 
and stem, we shall see 
that one end of the seed 
coat is caught against 
a heel, or ‘‘peg,”’ 
which has grown out 
from the stem for this 
purpose. Now if we 
examine one which is 

a little 
Symore ad- 


vanced, 
we shall see this heel 
more distinctly, and 
also that the stem is 
arching out away from 
the seed coats. As the 
stem arches up its back 
in this way it pries with 
the cotyledons against 

Fig. | the upper seed coat, 
Escape of the pumpkin seedling from the seed coats, but the lower seed coat 
is caught against this heel, and the two are pulled gradually 
apart. In this way the embryo plant pulls itself out from be- 
tween the seed coats. In the case of seeds which are planted 
deeply in the soil we do not see this contrivance unless we dig 
down into the earth. The stem of the seedling arches through 
the soil, pulling the cotyledons up at one end. Then it 
straightens up, the green cotyledons part, and open out their 
inner faces to the sunlight, as shown in fig. 3. If we dig into 
the soil we shall see that this same heel is formed on the stem, 
and that the seed coats are cast off into the soil. 


4 BOTANY. 


6. Parts of the pumpkin seedling.— During the germination 
of the seed all parts of the embryo have enlarged. This in- 
crease in size of a plant is one of the peculiarities of growth. 
The cotyledons have elongated and expanded somewhat, though 
not to such a great extent as the root and the stem. The 
cotyledons also have become green on exposure to the light. 
Very soon after the main root has emerged from the seed coats, 
other lateral roots begin to form, so that the 
root soon becomes very much branched. 
The main root with its branches makes 
up the root system of the seedling. Be- 
tween the expanded cotyledons is seen 
the plumule. This has enlarged some- 
what, but not nearly so much as the root, 
or the part of the stem which cxtends 
below the cotyledons. This part of the 
stem, i.e., that 
part below the 


cotyledons and 
extending to the fi; 
beginning of the ./ 


root, is called in Fig. 3. 
: Pumpkin seedling rising from th d. 
all seedlings the umpkin see ing rising rom the groun 


hypocotyl, which means ‘‘ below the cotyledon.”’ 


Exercise 1. 


7. Structure of a squash or pumpkin seed.—Sketch a squash or pumpkin 
seed, noting carefully the form and markings. Split off the tough papery 
seed coats (¢esta), from a seed which has been soaked in water, to observe 
the embryo. Note the large, flattened cotyledons. Spread them gently apart 
to see the attachment at the smaller ends, where they are attached to the 
short caulicle (stem). Sketch the embryo in this position showing the 
cotyledons, the plumule between them, and the short radicle projecting from 
the end where the cotyledons are attached; name the parts of the embryo. 
Make a cross-section of another seed through the middle, and observe the 
relation of the cotyledons to the seed coats; sketch. Make a cross-section 


HOW THE SEEDLING GROWS FROM THE SEED. § 


of a seed near the smaller end so that the section will cut across the 
plumule; sketch showing the positions of the different parts and the relation 
to the seed coats. ; 


Exercise 2. 


8. Structure of the bean seed.—Take beans which have been soaked in 
water. Sketch a bean, showing the form, the scar (Aé/wm) on the concave 
side, the minute pit (mzcropyle) by the side of the hilum. Remove the 
testa (seed coats) from one of the beans; note the large thick cotyledons; de- 
termine where the cotyledons are joined (or attached to the young caulicle). 
Along one side of this point of attachment note the young radicle; at the 
other end between the cotyledons note the plumule. 

Split open a bean along the line where the cotyledons meet; sketch one 
half, showing the young plumule and the venation of the leaf, and at 
the other side the young radicle. Make a cross-section of a bean and 
sketch to show the relation of the cotyledons to the seed coats, and the 
plumule between the cotyledons. 

If there is time, compare a pea seed. 


Exercise 3. 


9, Structure of the grain of corn.—Take grains of corn that have been 
soaked. Note the form, and the difference of the two sides. Sketch a 
grain of corn showing the depressed area near the smaller end. 

Make a longisection of a grain of corn through the middle line. (If neces- 
sary make several to obtain one which shows the structures well near the 
smaller end of the grain.) Sketch the section as shown by one half, observ- 
ing the following structures: 1st, the hard outer ‘‘ wall” (formed of the con- 
solidated wall of the ovary with the integuments of the ovules—see 
Chapters 32 and 33) ; 2d, the greater mass of starch and other plant food 
(the endosperm) in the centre ; 3d, a somewhat crescent-shaped body (the 
scutellum) lying next the endosperm and near the smaller end of the 
grain; 4th, the remaining portion of the young embryo lying between 
the scutellum and the seed coat in the depression. When good sections 
are made one can make out the radicle at the smaller end of the seed, 
and a few successive leaves (the plumule) which lie at the opposite end of 
the embryo shown by sharply curved parallel lines. Observe the attach- 
ment of the scutellum to the caulicle at the point of junction of the plumule 
and the radicle. The scutellum is a part of the embryo and represents a 
cotyledon. 

Dissect out an embryo from another seed, and compare with that seen in 
the section. 


6 BOTANY. 


Exercise 4. 


10. The squash (or pumpkin) seedling.—Take seedlings in different 
stages of germination which have been grown in a germinator. Make 
sketches of several different stages, showing the expanded cotyledons, the 
plumule between them, the main root, and the origin of the lateral roots, the 
hypocotyl (the portion of the stem between the root and the cotyledons). 
Note the ‘‘peg” on the hypocotyl and determine the way in which this 
organ assists the embryo in getting out of the seed coats. Compare seed- 
lings growing in the soil. 

1l. Other seedlings.—Make a similar study of the bean, pea, and corn 
seedlings, both from seeds germinated in folds of damp paper, and from 
those grown inthe soil. Sketch the different stages, and write a full descrip- 
tion and comparison, noting the points of agreement and disagreement 
between them, and the different ways in which the seedlings come up from 
the ground. 

(Consult Chapter 33). 


Material.—Seeds of the pumpkin or.squash, beans, peas, and corn. 
These should be soaked in water for about twenty-four hours before they 
are wanted for the study of the seed. 

Seedlings of the same plants in different stages of germination. Some of 
the seeds should be germinated in folds of wet paper or in moss, and some 
of them should be planted in soil in pots. These should be started about a 
week in advance of the time when they are wanted for study by the student. 
The number of seeds and seedlings which should be prepared will depend on 
the number of students in the class. A surplus of material should be pro- 
vided for. 


CHAPTER II. 


WINTER BUDS, SHOOTS, ETC. 


12. Season for study of shoots.—Either the autumn or the 
winter is an excellent time for some observations of the winter 
condition of plants, especially of the stems or shoots, as well as 
the leaves. While actual growth of the parts cannot then be 
observed, certain interesting and important peculiarities of the 
stems and leaves can then be easily studied. The exercises are 
also instructive for classes which have not had previous instruc- 
tion in nature studies. 

13. Annuals, biennials, perennials—One of the striking 
things which we observe during the winter season is the fact that 
certain plants, especially the herbs, like many weeds and culti- 
vated plants, are dead and dry. Where the plant makes its 
entire growth during the year or season, and ripens at the close, it 
is an annual. The bean, corn, squash, the ragweed, etc., are 
annuals. Other plants, like the thistle, mullein, etc., do not 
mature their fruit or seed until the second year. Such plants are 
btennials. Trees, shrubs, and many herbs as well, like the asters, 
goldenrods, etc., live from year to year, and are therefore Zeren- 
nials. In the goldenrods, in trillium, the toothwort, and other 
perennials of this kind, the larger part of the annual growth 
dies back at the close of the season, while the plant is carried 
over the winter by the shorter underground stem. 

14, Annual growth of the horse-chestnut.—In figure 4 there 
is illustrated a shoot of the horse-chestnut. Near the middle 
portion of the shoot is a ring of numerous fine scars, and 
another ring of similar scars near the lower end. These rings 
of scars mark the positions of successive annual terminal buds, 

7 


Fig. 4 

Two-year ‘ld twig 
of horse chestnut. 
showing buds and 
leaf scars. (A twig 
with a terminal bud 
should have _ bee’ 
selected for this fig- 
ure.) 


BOTANY. 


so that the portion of the shoot between two 
such adjacent rings, or above the last one, rep- 
resents the growth in length of the shoot for one 
year. At the close of the season’s growth the 
““bud’’ is formed. In the horse-chestnut the 
terminal bud is broader than the diameter of the 
shoot, and is ovate in form. 

15. We notice that there are a number of 
scales which overlap each other somewhat as 
shingles do on a roof, only they are turned in 
the opposite direction. If we begin at the base 
of the bud, we can see that the two lowest 
scales are opposite each other, and that the two 
next higher ones are also opposite each other, 
and set at right angles to the position of the 
lower pair. In the same manner successive 
pairs of scales alternate, so that the third, fifth, 
seventh, etc., are exactly over the first, and the 
fourth, sixth, etc., are exactly over the second. 
Aside from the fact that these brown scales fit 
closely together over the bud, we notice that 
they are covered with a sticky substance which 
helps to keep out the surface water. Thus a 
very complete armature is provided for the pro- 
tection of the young leaves inside. 

16. Leaf scars.—The number of leaves de- 
veloped during one season’s growth in length 
of the shoot can be determined by counting the 
broad whitish scars which are situated just 
below each pair of lateral buds. Near the 
margin of these scars in the horse-chestnut are 
seen prominent pits arranged in arow. These 
little pits in the leaf scar are formed by the 
breaking away of the fibro-vascular bundles 
(which run into the petiole of the leaf) as the 
leaf falls in the autumn. 


WINTER BUDS, SHOOTS, ETC. 9 


17. Lateral buds.—The lateral buds, it is noticed, arise in 
the axils of the leaves. Each one of these by growth the next 
year, unless they remain dormant, will develop a shoot or 
branch. Just above the junction of the upper pair of branches 
we notice scars which run around the shoot in the form of 
slender rings, several quite & 
close together. These are the 
scars of the bud scales of the 
previous year. By observing 
the location of these ring scars 
on the stem the age of the 
branch may be determined, as 
well as the growth in length 
each year. Small buds may 
be frequently seen arising in 
the axils of the bud scales, 
that is after the scales have 
fallen, so that four to ten 
small buds may be counted 
sometimes on these very nar- 
row zones of the shoot. 

18. Bud leaves.—On re- 
moving the brown scales of 
the bud there is seen a pair 
of thin membranous scales 
which are nearly colorless. 
Underneath these are young 
leaves; successive pairs lie Fig. 5. 
farther in the bud, in outline | heeqearel! wig of the American ashy 
similar to the mature leaves, annual rings. 
and each pair smaller than the one just below it. They are 
very hairy, with long white woolly fibres. These woolly fibres 
serve also to protect the young leaves from the cold or from 
sudden changes in the temperature, since they hold the air in 
their meshes very securely. 


Io BOTANY. 


19. Opening of the buds in the spring.—As the buds 
“*swell’’ in the spring of the year, when the growth of the 
young leaves and of the shoot begins, the bud scales are thrown 
backward and soon fall away as the leaves unfold, thus leaving 
the ‘‘ring scar’’ which marks the start of the new year’s 
growth in length of the shoot. 

20. Variations in different shoots.—A study of a number of 
different kinds of woody shoots would serve to show us a series 
of very interesting variations in the color, surface markings, out- 
line of the branch, arrangement of the leaves and consequently 
different modes of branching, variations in the leaf scars, the form, 
size, color, and armature of the buds, as well as great variations 
in the character of the bud scales. There are striking differences 
between the buds of different genera, and with careful study 
differences can also be seen in the members of a genus. 

21. Growth in thickness of woody stems.—In the growth of 
woody perennial shoots, the shoot increases in length each year 
at the end. The shoot also increases in diameter each year, 
though portions of the shoot one year or more old do not 
increase in length. We can find where this growth in diameter 
of the stem takes place by making a thin cross-section of a 
young shoot or branch of one of the woody plants. If we take 
the white ash, for example, in a cross-section of a one-year-old 
shoot we observe the following zones: A central one of whitish 
tissue the cells of which have thin walls. This makes a cylin- 
drical column of tissue through the shoot which we call the 
pith or medulla. Just outside of this pith isa ring of firmer 
tissue. The inner portion of this ring shows many woody 
vessels or ducts, and the outer portion smaller ducts, and a 
great many thick-walled woody cells or fibres. This then is a 
woody zone, or the zone of xylem. 

The outer ring is made up of the bark, as we call it. In this 
part are the bast cells. Between the bark and the woody zone 
is a ring of small cells distinguished from the bark and the 
woody inner portion by the finer texture of the cut surface, 


WINTER BUDS, SHOOTS, ETC. II 


This is the growing cylindrical layer of the shoot which lies 
between the bark and wood throughout the extent of the shoot 
and in fact the entire tree. It is the cambdium. 

22. Annual rings in woody stems.—If we now cut across a 
shoot of the ash which is several years old, we shall note, as 
shown in fig. 5, that there are successive rings which have a 
similar appearance to the woody ring in the one-year-old stem. 
This can well be seen without any magnification. The larger 
size of the woody ducts which are developed each spring, and 
the preponderance of the fibres at the close of each season’s 
growth, mark well the growth in diameter which takes place 
each year. 

For further details consult Chapter XI, and also the author’s 
larger ‘‘ Elementary Botany.”’ 

23. Phyllotaxy, or arrangement of leaves.—In examining 
buds on the winter shoots of woody plants, we cannot fail to 
be impressed with some peculiarities in the arrangement of these 
members on the stem of the plant. 

In the horse-chestnut, as we have already observed, the leaves 
are in pairs, each one of the pair standing opposite its partner, 
while the pair just below or above stand across the stem at right 
angles to the position of the former pair. In other cases (the 
common bed straw) the leaves are in whorls, that is, several 
stand at the same level on the axis, distributed around the 
stem. By far the larger number of plants have their leaves 
arranged alternately. A simple example of alternate leaves is 
presented by the elm, where the leaves stand successively on 
alternate sides of the stem, so that the distance from one leaf 
to the next, as one would measure around the stem, is exactly 
one half the distance around the stem. This arrangement is $, 
or the angle of divergence of one leaf from the next is 4. In 
the case of the sedges the angle of divergence is less, that is 4. 

By far the larger number of those plants which have the 
alternate arrangement have the leaves set at an angle of diver- 
gence represented by the fraction 3. 


12 BOTANY. 


24. Other angles of divergence.—Other angles of divergence 
have been discovered, and much stress has been laid on what is 
termed a law in the growth of the stem with reference to the 
position which the leaves occupy. There are, however, numer- 
ous exceptions to this regular arrangement, which have caused 
some to question the importance of any theory like that of the 
““ spiral theory’’ of growth propounded by Goethe and others 
of his time. 

25. Adaptation in leaf arrangement.—aAs a result, however, 
of one arrangement or another we see a beautiful adaptation of 
the plant parts to environment, or the influence which environ- 
ment, especially light, has had on the arrangement of the leaves 
and branches of the plant. Access to light and air are of the 
greatest importance to green plants, and one cannot fail to be 
profoundly impressed with the workings of the natural laws in 
obedience to which the great variety of plants have worked out 
this adaptation in manifold ways. 


Exercise 5, 

26. Shoots of the horse-chestnut.—Select shoots with strong terminal 
buds, and with several ring scars indicating several years’ growth. Sketch 
a shoot, showing the ring scars, the leaf scars, the lateral and terminal buds, 
the lenticels (small rough elevations scattered over the surface of the twig, 
made up of corky tissue through which air is admitted). Note that the lat- 
eral buds arise in the axils of leaves (above the leaf scars). Are there buds 
in the axils of all the leaf scars on the shoot? How do they differ in size ? 
Note that the larger and longer ones, from which the lateral branches usually 
arise, are usually situated near the terminal portion of each year’s growth 
of the shoot. There was not room for all of the buds to grow into branches 
because they would be too crowded, and would shut out light and air. In 
the struggle for existence some have outgrown others which remain dormant 
ready to start growth if by accident the main shoot should be broken just 
above them. 

Compare shoots which have borne flower-clusters for several years, and 
determine what effect this has had on the character of the branching. 

27. Buds of the horse-chestnut.—Sketch in detail a large terminal bud. 
Note the color and texture of the outer scales of the bud. Is the texture of 
the outer bud scales such as to afford protection to the tender portion of the 
bud within? Is there any other means for protection of the buds? 


WINTER BUDS, SHOOTS, ETC. 13 


Remove the scales one by one, determining the number, and their ar- 
rangement on the axis, as well as the difference in texture and form. Make 
a longitudinal section of the bud, and sketch one half to show the relation of 
the scales in the bud. Make a cross-section and sketch. 

28. Annual growth in thickness as shown by the ‘‘ annual rings.’— 
With a sharp knife make cross-sections of the shoots of different ages, and 
from the number of annual rings determine the age of the shoot. Compare 
the annual rings with the number of ring scars on the shoot and see if the 
age of the shoot determined by both means is the same. 


Exercise 6. 


29. Comparative study of other shoots.—Study in a similar way other 
shoots, taking for example the walnut or butternut, the birch, elm, dog- 
wood, peach, apple, etc. The selection may be made from trees or shrubs 
which are accessible, and for the purpose of illustrating several different 
types. 

Sketch the form of the shoot, the position of the leaf scars, of the ring 
scars, of the buds, lenticels, etc. 

Make careful notes upon these characters, as well as on the different col- 
ors, surface markings, etc. 

Determine the age of the shoots, and of the branches, the relation of the 
dormant buds to those which have developed into the lateral shoots or 
branches. Determine the effect which fruit buds have had on the branching 
of the different species. 

Make cross-sections and determine the age by the annual rings. 


Exercise 7. 


30. Comparative study of other buds.—Study the buds of several different 
shoots of trees and shrubs, for the purpose of determining the variations in 
the form of the bud scales, and the different means for the protection of the 
delicate scales within. 

Examples suggested are as follows: walnut or butternut, hickory, cur- 
rant, etc. 

Sketch the form and surface characters of the buds, and note the color, or 
other characters. 

Remove the scales one by one, note their arrangement on the shoot, their 
relation one to another in the bud. Determine the number of scales ina bud 
of the different kinds. Sketch the different forms of bud scales in each differ- 
ent kind of bud, arranging the sketches to represent the number of the scales, 
their form, and relative position on the axis, but far enough separated to 
show the details of each. 


14 BOTANY. 


Exercise 8. 


13. Comparison of leaf arrangement.—Study the arrangement of the leaves 
on several different shoots, by an examination of the leaf scars or by the buds. 
The teacher can select shoots which represent several different systems of 
phyllotaxy, for example the opposite and the alternate; among the alternate 
let the pupil determine those which have the angles of divergence repre- 
sented by the fractions }, J, 2, 3, etc. 


Exercise Q. 


82. Field observations on trees and shoots.—If the weather is favorable 
an excursion to the woods, fields, or to some park or garden would be an ap- 
propriate conclusion to these exercises, The result can be made the basis of 
a short paper by each student. For example, let the pupil observe the habit 
(that is, the general form, character of branching, etc.) of different trees ; the 
character of the bark ; any further peculiarities of buds and shoots; the dif- 
ferences between deciduous trees (those which shed all their leaves in the 
autumn, or whose leaves die), and evergreens. (In the evergreens the leaves 
remain green and attached to the trees for more than a year, for example in 
the pines for about three years. In this way while new leaves are formed 
each year, and old leaves are shed each year, there are green leaves on the 
tree at all seasons. ) 

Material (for exercises 5-8).—Shoots showing two or three years’ growth 
of the following species (or others which may be more convenient in some 
localities) : horse-chestnut, birch, dogwood, apple, peach, etc., a selection 
to represent several different types. In selecting some of the shoots it will 
be well to collect some which have borne fruit and which have fruit buds, in 
order to compare the different type of branching induced on the fruit-bearing 
shoots. (If some of the material can be collected when the leaves are present 
and preserved, such leafy shoots will be interesting for comparison, especially 
shoots of the birch, which have short lateral branches bearing only two 
leaves each year.) 


CHAPTER III. 
THE LIVING SUBSTANCE OF PLANTS. 


I, Prororptasm 1n Root Hairs or SEEDLINGS. 


33. Importance of studying protoplasm.—Now that we have 
become familiar with the parts of the seedling, have studied the 
germination of the seed, and have observed the increase in size 
and elongation of its parts we are impressed with the fact that it 
is a living thing. It is now time to inquire into the nature of 
the living substance of plants. Plant growth as well as some of 
the other life processes which we are about to study are at 
bottom dependent on this living matter. It is evident, then, 
that we should know something about it, how it appears, and 
howitacts. For with this knowledge it is easier to comprehend 
how the plant does its work as a living being. This living sub- 
stance of plants is protoplasm. ‘The student should now observe 
protoplasm in several plants. If there are not a sufficient num- 
ber of microscopes to enable the students to make and study 
their own preparations, let the teacher prepare a demonstration 
for the members of the class. 


Demonstration 2. 


34. To prepare seedlings with clean root hairs.—Begir to prepare the 
seeds several days or a week before they are wanted for study. Soak a 
handful of corn or beans, radishes, etc. (or more if there is a large class) in an 
abundance of water for 24 hours. Prepare a moist chamber by placing a 
layer of moss (sphagnum) or cotton in the bottom of a wide vessel (a crockery 
plate ora germinator with a fluted bottom). Upon this place a layer of filter 
paper. Have the sphagnum and filter paper well wetted, but not with a sur- 


15 


16 BOTANY. 


plus of water. Remove the seeds from the water and scatter them over the 
paper. Place another sheet of wet filter paper over them, and if it is necessary, 
in order to keep the seeds moist, scatter among 
them a little damp absorbent cotton. Cover 
with a glass or with an inverted vessel to pre- 


vent too rapid evaporation of the moisture. Set 
aside in a warm place, about 22°C. to 25°C. 


(about 70°-80° Fahr.). Look at the culture Fig. 6. 
every day to see that there is just the right Seedling of mses showing root 
airs, 


amount of water to keep the seeds from drying, 

and also to see that there is not a surplus of water or the seeds will rot. 
When the roots have begun to appear from the seeds remove the upper 

layer of paper and moss so that the root hairs can develop without interfer- 

ence. When the young roots just back of the tip are covered with a downy 

growth of colorless hairs, as in figure 6, they are ready for use. 


Demonstration 3. 


35. To prepare the root hairs for examination with the microscope.— 
Hold the root between the thumb and finger (or in this position between two 
thin pieces of elder pith to give it support). Then with a sharp razor, the 
blade resting on the forefinger and the edge against the root in the region of 
the root hairs, make a sliding cut across the root, Make several successive 
similar cuts in such a way as to get thin cross-sections of the root with the 
root hairs attached. Mount these sections in a drop of water on a glass slip 
and cover with a clean circle cover glass. Or with the needles tease out 
asmall portion of the root with the root hairs attached. Tease apart the 
tissues in a drop of water, being careful not to break off the root hairs, and 
mount in water on a glass slip. Place the slip under the microscope and focus 
the microscope on suitable root hairs for demonstration of the protoplasm. 
Let each pupil be seated at the microscope for a few moments to observe the 
protoplasm in the root hairs. 


Demonstration 4. 


86. Protoplasm in the root hairs.—Examining this preparation with the 
aid of the microscope we see that each thread or root hair is a continuous 
tube. It is a single plant cell which has become very much elongated and 
free by pushing out its free end some distance from the other cells of the 
outer portion of the root. Observe the boundary wall of the thread. This is 
the ce// wa//. Within this the protoplasm is seen. It is colorless and very 
granular, that is, numerous small granules of different sizes lie quite closely 
together in a colorless slimy liquid. This is the protoplasm. It does not 


THE LIVING SUBSTANCE OF PLANTS. 17 


ntirely fill the root hair. But here and there are seen strands of this sub- 
‘ance which cross the thread leaving clear spaces between. Or the clear 


daces appear as rounded vacuoles of different sizes, 
r the vacuoles are more or less elongated, These 
lear spaces in the root hair are occupied by a watery 
ibstance known as the ce// sap. 


Demonstration 5. 


37. Test for protoplasm.—Draw off the water from 
nder the cover glass by the use of filter paper, and 
tthe same time add some of the solution of iodine 
‘ith a medicine dropper. Observe that the proto- 
lasm is stained a yellowish-brown color. This is 
1e reaction of protoplasm in the presence of iodine, 


Exercise 10. 


88. Study root hairs of seedlings.—Some of the 
‘edlings prepared in demonstration 2 can be used 
y the members of the class for a study of the gross 
pearance of the root hairs, 

Make a sketch of the seedling showing what por- 
on of the root is covered by the root hairs. Why 
‘e not the root tips covered with the root hairs? 
Thy are the root hairs absent from the older portions 
“the roots? As to strength and firmness how do 
.e root hairs and rcots compare? Test this by 
indling. 

Immerse the portion of the root covered by the 
‘ot hairs for a few moments in a solution of iodine. 
o they take the stain? Will the stain all wash out 

water when immersed for a few moments ? 

Take a fresh seedling with uninjured root hairs 
id immerse the root for a few moments in a 1% 


ia 
at, 


J. 
a are eee rere rest oe" 
fo Rem ee 


Fig. 7. 
Root hairs of corn be- 
fore and after treatment 
with 5% salt solution, 


jueous solution of eosin. Rinse in water. Do the root hairs hold the 
ain? Immerse the root for a few moments in strong alcohol, or in 2% 


rmalin, and then immerse the root hairs in eosin. 
ot hairs hold the stain now? Why? 


Rinse in water. Do the 


Write out a complete account of your experiments and observations. 


18 BOTANY. 


Synopsis.—The root hairs are formed near the growing end of the young 
root. 
The root hair is a single plant cell, very long and narrow. 
The root hair is formed by the elongation of one of the outer cells of the 
root, 
Cell wall, the enclosing cellulose membrane to protect and hold 
the cell contents. 
Protoplasm. 
Nucleus, 
The  root- Granular protoplasm, arranged differently from that in spiro- 
hair cell. | gyra; a wall layer, and then stout strands and masses 
which reach across with clear rounded spaces between (the 
vacuoles), 
Cell sap, in the vacuoles. 
{ Chlorophyll absent. 
Reactions of the protoplasm; is killed, and stained yellowish brown with 
iodine; a 1% aqueous solution of eosin does not stain it; it does stain with the 
eosin when first killed with alcohol. 


Materials.—Young seedlings of radish, corn, squash, or other plants, with 
clean root hairs, grown in a germinator (see Demonstration 2), 

A solution of iodine. 

A 1% aqueous solution of eosin. 

95% alcohol (commercial strength). 

Watch glasses to receive small quantities of these solutions when the pupils 
are engaged in exercise 10, Medicine droppers. 

For the demonstrations : Micros-ope, razor, glass slips, cover-glass circles, 

_ dissecting needles. (Hereafter the microscope and accessories will not be 

listed in each case for the demonstrations ; microscope, etc., will be inserted 
instead.) 


CHAPTER IV. 
THE LIVING SUBSTANCE OF PLANTS—ContTiNuEb. 


II. Protroptasm in an ALGA: SPIROGYRA. 


39. The plant spirogyra.*—There are a number of alge 
which would serve the purpose quite as well as spirogyra, but 
we shall want to employ this plant again at a later time, and 
it is well now to become familiar with it. It is found in the 
water of pools, ditches, ponds, or in streams of slow-running 
water. It is green in color, and occurs in loose mats, usually 
floating near the surface. The name “‘ pond scum”’ is some- 
times given to this plant, along with others which are more or 
less closely related. If we lift a portion of it from the water, 
we see that the mat is made up of a great tangle of green silky 
threads. Each one of these threads is a plant, so that the 
number contained in one of these fluating mats is very great. 


Demonstration 6. 


40. To prepare spirogyra for study under the microscope.— Lift up a bit of 
this thread tangle with a needle and place it in a drop of water on a ‘‘ glass 
slip.’? With the needles tease apart the threads so that they will be scattered 
in the water. Now place over these threads in the water a clean, thin, glass 
circle. Place the preparation on the stage of the microscope and adjust for 
observation of a thread. Let the pupils first examine the plant under the 
low power of the microscope, and then under the high power. They should 


* If spirogyra is in fruit some of the threads will be lying parallel in pairs, 
and connected by short tubes. In some of the cells may be found rounded or 
oval bodies known as zygosporvs. These may be seen in figure 93 and will 
be described in another part of the book. 

19 


20 


BOTANY. 


first observe certain things about the plant enumerated in paragraphs 41 and 42, 


Fig. 8. 
Thread of spiro- 
gyra, showing long 


cells, chlorophyll 
band, nucleus, 
strands of proto- 
plasm, and the 
granular walllayer 
of protoplasm. 


so that they will be able to tell it from other minute green 
algze. When these things have been observed the protoplasm 
can be demonstrated. At one sitting each pupil can ob- 
serve the things called for in paragraphs 41-44; make 
sketches and notes. 

41. Chlorophyll bands in spirogyra.—We first 
observe the presence of bands, green in color, 
the edges of which are usually very irregularly 
notched. These bands course along in a spiral 
manner near the surface of the thread. There 
may be one or several of these spirals, according 
to the species which we happen to select for 
study. This green coloring matter of the band 
is chlorophyll, and this substance, which also oc- 
curs in the higher green plants, will be considered 
in a later chapter. At quite regular intervals in 
the chlorophyll band are small starch grains, 
grouped in a rounded mass. 

42. The spirogyra thread consists of cylind- 
rical cells end to end.—Another thing which 
attracts our attention, as we examine a thread 
of spirogyra under the microscope, is that the 
thread is made up of cylindrical segments or 
compartments placed end to end. We can see 
a distinct separating line between the ends. 
Each one of these segments or compartments 
of the thread is a ce//, and the boundary wall is 
in the form of a cylinder with closed ends. 

43. Protoplasm.—Having distinguished these 
parts of the plant we can look for the proto- 
plasm. It occurs within the cells. It is color- 
less (i.e., hyaline) and consequently requires 
close observation. Near the centre of the cell 
can be seen a rather dense granular body of an 


elliptical or irregular form, with its long diameter transverse to 


THE LIVING SUBSTANCE OF PLANTS. 21 


the axis of the cell in some species; or triangular, or quadrate 
in others. This is the mucleus. Around the nucleus is a 
granular layer from which delicate threads of a shiny granular 
substance radiate in a star-like manner, and terminate in the 
chlorophyll band by one of the groups cf starch grains. A 
granular layer of the same substance lines the inside of the cell 
wall, and can be seen through the microscope if it is properly 
focussed. This granular substance in the cell is protoplasm. 

44, Cell-sap in spirogyra.—tThe greater part of the interior 
space of the cell, that between the radiating strands of proto- 
plasm, is occupied by a watery fluid, the ‘‘ cell-sap.’’ 


Demonstration 7. 


45. Test for protoplasm in spirogyra.— Mount a few threads of spirogyra 
in a drop of weak solution of iodine for microscopic examination. 


Fig. 9. Fig. ro. 
Cell of spirogyra before treat- Cell of spirogyra after treatment 
ment with iodine. with iodine. 


The iodine gives a yellowish-brown color to the protoplasm, 
and it can be more distinctly seen. The nucleus is also much 
more prominent since it colors deeply, and we can perceive 
within the nucleus one small rounded body, sometimes more, 


22 BOTANY. 


the nucleolus. The iodine here has killed and stained the 
protoplasm. 

46. Living protoplasm resists the action of some reagents.— 
If a few living threads are placed in a 1% aqueous solution of 
eosin, and after a time washed, the protoplasm remains un- 
colored. This teaches that protoplasm in a living condition 
resists for a time the action of some reagents. (The iodine 
and eosin here used are called reagents.) But let us place 
these threads for a short time, two or three minutes, in strong 
alcohol, which kills the protoplasm. Then mount them in the 
eosin solution. The protoplasm now takes the eosin stain. 
After the protoplasm has been killed the nucleus is no longer 
elliptical or angular in outline, but is rounded. The strands 
of protoplasm are no longer in tension as they were when alive. 


Exercise 11. 


47. The alga spirogyra.—Place some of the threads in a shallow vessel 
of water. Note the appearance of the threads, their length. Determine if 
branches are present or not. If a small hand lens is convenient, spread some 
of the threads out between two glass slips, and holding the preparation toward 
a lighted window look at it through the lens. Describe what is seen. Lift 
some of the threads with the aid of a needle, and notice how long and delicate 
they are. Feel of some between the thumb and finger. Pinch some of the 
threads and again place them in the water. Write an account of the observations, 

Place some threads in asmall quantity of alcohol and let remain for 
several minutes. Does the alcohol become colored green? Why? 

Place some of the threads in a solution of iodine for a few moments. Rinse 
them in water. Do the threads hold the color? What is the color? 

Place some fresh threads in a 1% solution of eosin for a few moments. Rinse 
in water. Do the threads hold. the stain? Why? Place the same threads 
for a few moments in strong alcohol, and then in the eosin. Rinse in water. 
Do the threads now hold the color? Why? 

Write out a complete account of your experiments and observations in this 
study of the gross characters of the rlant spirogyra. 


THE LIVING SUBSTANCE OF PLANTS. 23 


Synopsis.—The spirogyra plant occurs in quiet water. 
A single cell, cylindrical, is a section of a long thread. 
Cell wall of cellulose. 
Chlorophyll band, flattened, coiled spirally around the inner side 
of the wall, colored green by the chlorophyll substance. 
Nucleus, granular, near centre of cell. 


Spirogyra Small nucleolus within nucleus. 
cell. | Protoplasm proper (cytoplasm) radiating in strands 
Protoplasm. from the nucleus ; thin wall layer next the cell 
wall, 


Cell-sap (watery substance) occupying the spaces 
| between the strands of protoplasm. 
. (Starch masses in the chlorophyll band.) 
The spirogyra thread is made up of many of these cells lying end to end. 


Reactions of protoplasm in spirogyra: 
Stains yellowish brown with iodine. 
A 1% aqueous solution of eosin does not stain the living protoplasm. 
Alcohol kills the protoplasm, so that eosin will then stain it. 
Materials.—Fresh mats of the pond-scum spirogyra, either freshly collected 
from ponds or ditches, or from an aquarium where it may be kept for a week 
or more in a fresh condition. 
' A solution of iodine. 
A 1% aqueous solution of eosin. 
95% alcohol. 
Watch glasses for receiving the solutions when the pupils are engaged in 
exercises II. Microscope, etc. 


CHAPTER V. 
THE LIVING SUBSTANCE OF PLANTS—ConcLuDeEb. 


III. ProropLtasm in A Funeus: Mucor. 


Note.—Omit or read this chapter, or where there is time, if the teacher so 
desires, it may be studied in addition to spirogyra, or as an alternate if spiro- 
gyra cannot be obtained. 


Demonstration 8. 


48. To obtain the black mould —If stock cultures of the black mould 
are not at hand it is well for the teacher to make some preparation several 
weeks beforehand for securing the mould for the cultures. 

To do this take an orange or lemon, cut in halves, and squeeze out the 
juice. Let it lie exposed in the room for a day. Then place this with some 
old bread in a moist chamber and set aside in a warm room for several days. 
In this time several moulds will appear. Some may have a blue color, others 
white, and some will probably become black. The black one is quite likely 
to be the black mould. New cultures of the black mould should now be made 
on fresh bread, or on the cut surface of baked potatoes. If they are made on 
potatoes the following method will answer; if on bread put the pieces in a 
moist chamber and sow the spores as described here for the potato cultures. 


Demonstration Q. 


49. To make cultures of the black mould.—Take some freshly baked 
potatoes. Make a cut about Icm deep entirely around them. Break them 
into halves and place these in moist chambers on damp paper with the cut 
surfaces uppermost. If a platinum needle which can be flamed is not at hand, 
take a dissecting needle, thrust it for a moment into strong alcohol. Hold it 
in the air until it is dry. Touch the moist surface of the potato with the 
needle, then touch the black heads of the fungus on the bread or fruit to catch 
some of the spores. Then touch the potato surface again, repeating this sev- 
eral times until spores have been put in a number of spots. Close the moist 


24 


THE LIVING SUBSTANCE OF PLANTS. 25 


chamber and set aside in a warm place. For several days observe the growth. 
First there appear small spots of delicate white threads. This tuft of threads 
increases in size, the threads elongate and branch, 


Demonstration 10. 


50. To prepare the myceliym of the black mould for siudy of th- proto- 
plasm.— These white threads of the mould are fungus threads. They are 
called the mycelium, The mycelium is the vegetative or growing portion of 
the mould, while the black heads are the fruiting portion. With a nee le 
carefully lift a small tuft of these threads grown in the moist chamber, place 
them in a drop of water on the glass slip and carefully tease them apart so that 
individual threads can be seen. Prepare for study under the microscope. 
When the microscope has been focussed on a suitable group of threads each 
pupil can then observe the things noted in paragraphs 51-53. 


51. Mycelium of the black mould.—Under the microscope 
we see only a small portion of the branched threads. There is 
no chlorophyll as in spirogyra. This is one of the important 
characters of the group of plants to which the black mould 
belongs. In addition to the absence of chlorophyll, we see 
that the mycelium is not divided at short intervals into cells, 
but appears like a delicate tube with branches, which become 
successively smaller toward the ends. 


Fig. tr. 
Thread of mucor, showing protoplasm and vacuoles. 


52. Appearance of the protoplasm.—Within the tube-like 
thread now note the protoplasm. It has the same general 
appearance as that which we noted in spirogyra. It is slimy, 
or semi-fluid, partly hyaline, and partly granular, the granules 
consisting of minute particles (the mécrosomes). While in 


26 BOTANY. 


mucor the protoplasm has the same general appearance as in 
spirogyra, its arrangement is very different. In the first place 
it is plainly continuous throughout the tube. We do not see 
the prominent radiations of strands around a large nucleus, but 
still the protoplasm does not fill the interior of the threads. 
Here and there are rounded clear spaces termed vacuoles, which 
are filled with the watery fluid, cell-sap. The nuclei in mucor 
are very minute, and cannot be seen except after careful treat- 
ment with special reagents. 

53. Movement of the protoplasm in mucor.—While examin- 
ing the protoplasm in mucor we are likely to note streaming 
movements. Often a current is seen flowing slowly down one 
side of the thread, and another flowing back on the other side, 
or it may all stream along in the same direction. 


Exercise 12, 

54. Study of mycelium.—Use portions of the mould which have not become 
black, These portions are the mycelium, mats of the fine colorless threads. 

Note the color of the threads, the absence of chlorophyll. To test this 
place some of the threads in strong alcohol, let stand for some time. Does 
the alcohol become colored ? 

Take some fresh threads and place them in the iodine solution. Remove 
and rinse in water. What is the color? 

Place fresh threads in some of the 1% aqueous solution of eosin, and rinse 
in water. Do the threads hold the color? Now immerse the same threads 
in strong alcohol, then rinse in water, and place in the eosin solution for a 
moment. Rinse in water. Do the threads now hold the stain? Why? 

Write out a complete account of the experiments and observations. 


Exercise 138. 

55. To obtain the mould from fruits.—-This may be made a home exercise 
if preferred. It is well whenever possible to get the pupils to do some of the 
work of preparation. 

Let each pupil take half an orange or lemon, squeeze out the juice, and 
leave it exposed in his living room through the day. At night place it 
along with some pieces of bread in a glass tumbler, first putting a wet piece 
of paper in the bottom of the tumbler. Cover the vessel with a piece of 
glass. Keep ina warm room. Each day observe what appears, keeping 
notes, and describing the appearance of the mycelium. Observe if the black 
mould appears when the growth comes to fruit. 


THE LIVING SUBSTANCE OF PLANTS. 27 


56. Protoplasm occurs in the living parts of all plants.— 
The substance we have found in the alga spirogyra, in the root 
hairs of the corn seedling, in the threads of the black mould, is 
essentially alike in all. It may be arranged differently in the 
different plants, but its general appearance is the same. It 
moves quite rapidly in the cells of some plants, but so slowly 
in others that we may not see the movement. Yet when we 
treat the protoplasm with well-known reagents the reaction in 
general is the same. It has been found by the experience of 
different investigators that the substance in plants which shows 
these reactions under given conditions is protoplasm. We 
have demonstrated to our satisfaction then that we have seen 
protoplasm in the simple alga spirogyra, in the root hairs of the 
seedling, and in the threads of the black mould. If we chose 
to make sections of the stems and leaves of the seedling, or of 
the living parts of other higher plants, we should find that 
protoplasm is present in all these living cells. We then con- 
clude that protoplasm occurs in the living parts of all plants. 

57. Summary of observations on protoplasm.—While we 
have by no means exhausted the study of protoplasm, we can, 
from this study, draw certain conclusions as to its occurrence 
and appearance in plants. Protoplasm is found in the living 
and growing parts of all plants. It is a semi-fluid, or slimy, 
granular, substance; in some plants, or parts of plants, the 
protoplasm exhibits a streaming or gliding movement of the 
granules. It is irritable. In the living condition it resists 
more or less for some time the absorption of certain coloring 
substances. The water may be withdrawn by glycerine. The 
protoplasm may be killed by alcohol. When treated with 
iodine it acquires a yellowish-brown color. 

Material.—Freshly formed mycelium of the common black mould (see 
demonstration 8, which also see for culture material and vessels). 


A solution of iodine. A 1% aqueous solution of eosin. 95% alcohol. 
Watch glasses to receive small quantities of the solutions when the pupils 


are engaged in exercise 12. 
Microscope, etc. 


CHAPTER VI. 


HOW WATER MOVES IN AND OUT OF PLANT 
CELLS. 


AssoreTion, Dirrusion, OsMose. 


Demonstration 11. 


58. Osmose in spirogyra.—Mount a few threads of the alga spirogyra in 
a drop of the 5% salt solution on a glass slip, and place on a cover glass for 
microscopic examination. Let each pupil examine the preparation to ob- 
serve the protoplasm contracted away from the cell wall. The protoplasmic 
layer contracts slowly from the cell wall, and the movement of the mem- 
brane can be watched by looking through the microscope. The membrane 
contracts in such a way that all the contents of the cell are finally collected 
into a rounded or oval mass which occupies the centre of the cell. 

Now add fresh water and draw off the salt solution. The protoplasmic 
membrane expands again, or moves out in all directions, and occupies its 
former position against the inner surface of the cell wall. This indicates 
that there is some pressure from within, while this process of absorption is 
going on, which causes the membrane to move out against the cell wall. 

The salt solution draws water from the cell-sap. There is thus a ten- 
dency to form a vacuum in the cell, and the pressure on the outside of the 
protoplasmic membrane causes it to move toward the centre of the cell. 
When the salt solution is removed and the thread of spirogyra is again 
bathed with water, the movement of the water is zzward in the cell. This 
would suggest that there is some substance dissolved in the cell-sap which 
does not readily filter out through the membrane, but draws on the water 
outside. It is this which produces the pressure from within and crowds the 
membrane out against the cell wall again. 


59. Turgescence.—Were it not for the resistance which the 
cell wall offers to the pressure from within, the delicate proto- 
plasmic membrane would stretch to such an extent that it would 

28 


WATER IN PLANT CELLS. 29 
' 


be ruptured, and the protoplasm therefore would be killed. If 
we examine the cells at the ends of the threads of spirogyra we 
will see in most cases that the cell wall at the free 
end is arched outward. This is brought about by 
the pressure from within upon the protoplasmic 
membrane which itself presses against the cell wall, 
and causes it to arch outward. This is beautifully 


Fig. 14. 
Spirogyra from 
salt solution into 
water, 


Fig. 12. Fig. 13. 
Spirogyra before Spirogyra in 5% salt solution 
placing in salt solu- 
tion. 


- shown in the case of threads which are recently broken. The 
cell wall is therefore e/asc, it yields to a certain extent to the 


30 BOTANY. 


pressure from within, but a point is soon reached beyond 
which it will not stretch, and an equilibrium then tends to be 
established between the pressure from within on the protoplas- 
mic membrane, and the pressure from without by the elastic 
cell wall. This state of a cell is surgescence, or such a cell is 
said to be /urgescent, or turgid. 


Demonstration 12. 


60. Experiment to show diffusion through an animal membrane.—For 
this experiment use a thistle tube, across the larger end of which should be 
stretched and tied tightly a piece of bladder mem- 
i brane. A strong sugar solution (three parts sugar 
to one part water) is now placed in the tube so that 
i the bulb is filled and the liquid extends part way 
in the neck of the tube. This is immersed in water 
within a wide-mouth bottle, the neck of the tube 
being supported in a perforated cork in such a way 
that the sugar solution in the tube is on a level with 
the water in the bottle or jar. In a short while the 
liquid begins to rise in the thistle tube, in the course 
of several hours having risen several centimeters. 
The diffusion current is thus stronger through the 
membrane in the direction of the sugar solution, so 
that this gains more water than it loses. 


61. How diffusion takes place.—We have 
here two liquids separated by an animal 
membrane, water on the one hand which 
diffuses readily through the membrane, while 
on the other is a solution of sugar which dif- 
fuses through the animal membrane with 
difficulty. The water, therefore, not contain- 
ing any solvent, according to a general law 


Fig. 15. 


which has been found to obtain in such cases, diffuses more 
readily through the membrane into the sugar solution, which 
thus increases in volume, and also becomes more dilute. The 
bladder membrane is what is sometimes called a diffusion mem- 
brane, since the diffusion currents travcl through it. In this ex- 
periment then the bulk of the sugar solution is increased, and the 


WATER IN PLANT CELLS. 3t 


liquid rises in the tube by this pressure above the level of the 
water in the jar outside of the thistle tube. The diffusion of 
liquids through a membrane is osmosis. 

62. Importance of these physical processes in plants.—Now 
if we recur to our experiment with spirogyra we find that exactly 
the same processes take place. The proptoplasmic membrane 
is the diffusion membrane, through which the diffusion takes 
place. The salt solution which is first used to bathe the 
threads of the plant is a stronger solution than that of the cell- 
sap within the cell. Water, therefore, is drawn out of the cell- 
sap, but the substances in solution in the cell-sap do not readily 
move out. As the bulk of the cell-sap diminishes the pressure 
from the outside pushes the protoplasmic membrane away from 
the wall. Now when we remove the salt solution and bathe the 
thread with water again, the cell-sap, being a solution of certain 
substances, diffuses with more difficulty than the water, and the 
diffusion current is inward, while the protoplasmic membrane 
moves out against the cell wall, and turgidity again results. 
Also in the experiments with salt on the tissues and cells of the 
beet (see exercise 14), the same processes take place. 

These experiments not only teach us that in the protoplasmic 
membrane, the cell wall, and the cell-sap of plants do we have 
structures which are capable of performing these physical 
processes, but they also show that these processes are of the 
utmost importance to the plant, in giving the plant the power 
to take up solutions of nutriment from the soil. 


Exercise 14. 


63. To test the effect of a 5% salt solution on a portion of the tissues of a 
beet.—Select « red beet. Cut several slices about 4cm in diameter and 
about 5m thick. Grasp the slices between the thumb and forefinger and 
attempt to bend them by light pressure. They are quite rigid and bend but 
little. Immerse a few of the slices in fresh water and a few in a 5% salt solu- 
tion. In the course of an hour or less, examine the slices again. Those inthe 
water remain as at first quite rigid, while those in the salt solution are more 
or less flaccid or limp. They readily bend by pressure between the fingers. 

The salt solution, we judge after our experiment with spirogyra, with- 


32 BOTANY. 


draws some of the water from the cell-sap, the cells thus losing their turgid. 
ity and the tissues becoming limp or flaccid from the loss of water. 

64. The beet slice becomes rigid again in water.—Now remove some of 
the slices of the beet from the salt solutions, wash them with water and then 
immerse them in fresh water. In the course of thirty minutes to one hour, 
if we examine them again, they will be found to have regained, partly or 
completely, their rigidity. Here again we infer from the former experiment 
with spirogyra that the substances in the cell-sap now draw water inward ; 
that is, the diffusion current is inward through the cell walls and the proto- 
plasmic membrane. and the tissue becomes turgid again. 


Exercise 15. 
65. Turgor is lost when the protoplasm is dead.—Place some slices of a red 
beet in alcohol; also some in hot water near the boiling point. Do the alcohol 
and the the hot water become colored? Why? Determine the condition of the 


Fig. 16. Fig. 17. Fig. 18, 
Rigid condition of fresh beet Limp condition after lying in Rigid again after lying 
section, salt solution, in water. 


Figs. 16-18.—Turgor and osmosis in slices of beet. 


slices by pressure between the fingers. Are they rigid or flaccid? Why? 
Place them now in fresh cold water. After a quarter of an hour or longer does 
any change take place as regards their resistance to pressure between the 
fingers ? What is the reason for their remaining in this condition? In what 
condition must protoplasm be in order to perform the work of a diffusion 
membrane ? 
Exercise 16. 

66. Osmose experiments with leaves,—Take leaves of various plants, like 

the geranium, coleus, or seedlings of the squash, pea, or bean, etc. 


WATER IN PLANT CELLS. 33 


Immerse the leaves of some in water, and of another set in a 5% salt solution, 
The petioles of the leaves should not be immersed, for it is desirable to keep 
the cut ends out of the water or salt solution. In fifteen minutes to half an 
hour, lift the leaves and seedlings from the water and note the result, and 
compare. Those which were in the salt solution now rinse in fresh water 
and immerse for a time in water. Now note the result. Explain the results 
of this experiment from the results obtained in the previous experiments. 


Synopsis. 

( A strong salt solution draws water out of the cell-sap, and 
the protoplasmic membrane is pushed inward. The 
cell becomes fladédy. 

Remove the salt and surround the cell with water, and 
the cell-sap draws water inside again, so that the pro- 
toplasmic membrane moves out and presses strongly 
against the cell wall and the cell becomes rigid 
(‘turgid ’’) again. 

The cell-sap then is a solution of certain salts. 


Movement of water 
in a single cell. 


( The beet slice is a cell mass, or a mass of tissue. 

Placed in salt solution some of the water is drawn out 
of the cell-sap of all the cells by the salt solution ; 
the mass of cells, or the slice, becomes fladdy. 

Placed in water it becomes rigid, or turgid, again. 

The action is the same as in the single cell, but all the 
cells act in concert. 

The action is the same with leaves, and other soft cell 
masses, or plant parts. 


Movement of water 
in cell masses. 


When water and a salt, or sugar, solution are separated by an animal 
membrane, the current of water is stronger toward the salt, or sugar, solu- 
sion. The membrane holds back for a time the substance dissolved in the 
water. So the protoplasmic membrane acts in the same way when it sepa- 
rates two different liquids, where one is a stronger salt than the other, or 
where one is a salt and the other is water. 

When the protoplasm is killed it cannot act as a diffusion membrane. 


Material.—Fresh material of spirogyra. 

Fresh beets, dark red ones (winter-stored beets are good). 

Leafy shoots of some succulent plants, in a fresh condition, or seedlings. 

Common table salt, a 5% solution in water. 

95% alcohol, and hot water for exercise 15. 

Wide-mouth bottle, thistle tube, small piece of bladder membrane, and 
sugar, for demonstration 12. 

Microscope, etc. 


CHAPTER VII. 
HOW PLANTS OBTAIN THEIR LIQUID FOOD. 


I. Water CuLTuREs, 


67. How constituents of plant food are determined.—We 
are now ready to inquire how plants obtain food from the soil 
or water. Chemical analysis shows that certain mineral sub- 
stances are common constituents of plants. By growing plants 
in different solutions of these various substances it has been 
possible to determine what ones are necessary constituents of 
plant food. While the proportion of the mineral elements 
which enter into the composition of plant food may vary con- 
siderably within certain limits, the concentration of the solutions 
should not exceed certain limits. A very useful solution is one 
recommended by Sachs, and is as follows: 

68. Formula for solution of nutrient materials.—The pro- 
portions of the ingredients are here given. A larger quantity 
than 1000cc may be needed. 


WCE casts ans atiecinbastiavennanae 9 Oe Heain ami b nes 1000 cc 
Potassium mitrateicgsicucemnexacaks omnes ama 0.5 gr 
Sodium chloride ss: ncceexedunesecryes seams 0.5 * 
Calcium sulphates . cvs 4.aaeeerdwetisonse O.5 
Magnesium sulphate ...............-..0000 0.5 ‘ 
Calcium phosphate...................0000. 0.5 fF 


The calcium phosphate is only partly soluble. The solution which is not 
in use should be kept in a dark cool place to prevent the growth of minute 
alge. 


Demonstration 13. 


69. To prepare the seedlings in water cultures.—Several different plants 
are useful for experiments in water cultures ; peas, corn, or beans are very 


34 


HOW PLANTS OBTAIN THEIR LIQUID FOOD. 35 


good. The seeds of these plants may be germinated, after soaking them for 
several hours in warm water, by placing them between the folds of wet paper 
on shallow trays, or in the folds of wet cloth (see demonstration 1). At the 
same time that the seeds are placed in damp paper or cloth for germination, 
one lot of the soaked seeds should be planted in good soil and kept under the 
same temperature conditions, for control. When the plants have germinated 
one series should be grown in distilled water, which possesses no plant food; 
another in the nutrient solution, and still another in the nutrient solution to 
which has been added a few drops of a solution of iron chloride or ferrous 
sulphate. There would then be four series of cultures which should be 
carried out with the same kind of seed in each series so that the comparisons 
can be made on the same species under the different conditions. The series 
should be numbered and recorded as follows : 

No. 1, soil. 

No. 2, distilled water. 

No. 3, nutrient solution. 

No. 4, nutrient solution with a few drops of iron solution added. 

70. How to set up t.e experiment.—Small jars or wide-mouth bottles, or 
crockery jars, can be used for the water cultures, and the cultures are set up 
as follows: A cork which wiil just fit in the 
mouth of the bottle, or which can be supported 
by pins, is perforated so that there is room to 
insert the seedling, with the root projecting 
below into the liquid. The seed can be 
fastened in position by inserting a pin through 
one side, if it is a large one, or in the case 
of small seeds a cloth of a coarse mesh can 
be tied over the mouth of the bottle instead of 
using the cork, After properly setting up the 
experiments the cultures should be arranged in 
a suitable place, and observed from time to 
time during several weeks. In order to obtain 
more satisfactory results several duplicate series 
should be set up to guard against the error 
which might arise from variation in individual 
plants and from accident. Where there are Fig. 19. 
several students in a class, a single series set ee ae. ce 
up by several will act as checks upon one an- 
other. If glass jars are used for the liquid cultures they should be wrapped 
with black paper or cloth to exclude the light from the liquid, otherwise 
numerous minute algz are apt to grow and interfere with the experiment. If 
crockery jars are used they will not need covering. 


36 BOTANY. 


71. Result of the experiment.—For some time all the plants grow equally 
well, until the nutriment stored in the seed is exhausted. The numbers 1, 3 
and 4, in soil and nutrient solutions, should outstrip number 2, the plants in 
the distilled water. No, 4 in the nutrient solution with iron, having a perfect 
food, compares favorably with the plants in the soil, 


Exercise 17. 


72. Notes on the water cultures.— When the water cultures are set up the 
members of the class can take notes on them, Then from time to time for 
several months the plants should be inspected and the members of the class 
should keep a record of the results, and should not only compare the plants in 


Fig. 20. Fig. 21. Fig. 22, Fig. 23. 
Tn soil. Nutrient solu- Nutrient solu- In distilled 
tion with iron. tion without water. 


iron, 
Figures 20-23.—Comparison of growth of pumpkin seedlings, all started at the same time. 


the different jars, but should compare them with the plants growing in the 
soil which were planted at the same time. From these records let each pupil 
write a complete account of the experiment. 


II. How Pranrs osrain Foop From THE SOIL. 


73. Plants take liquid food from the soil_—From these 
experiments then we judge that such plants take up the food 
they receive from the soil in the form of a liquid, the elements 
being in solution in water. 


HOW PLANTS OBTAIN THEIR LIQUID FOOD. 37 


If we recur now to the experiments which were performed 
with the salt solution on the cells of spirogyra, in the cells of 
the beet, and the way in which these cells become turgid again 
when the salt solution is removed and they are again bathed 
with water, we will have an indication of the way in which : 
plants take up nutrient solutions of food material through their 
roots. 

It should be understood that food substances in solution 
during absorption diffuse through the protoplasmic membrane 
independently of each other and also independently of the rate 
of movement of the water from the soil into the root hairs and 
cells of the roots. When the cell-sap is poor in certain sub- 
stances which are dissolved in the surrounding water of the soil, 
these substances diffuse inwardly more rapidly. But as the 
cell-sap becomes richer in that particular food substance its 
further absorption is correspondingly diminished until the cell- 
sap becomes poorer again, as by diffusion this substance passes 
on into other cells. 

74. How food solutions are carried into the plant.—We can 
see how the root hairs are able to take up solutions of plant 
food, and we must next turn our attention to the way in which 
these solutions are carried further into the plant. We should 
make a section across the root of a seedling in the region of the 
root hairs and examine it with the aid of a microscope. We 
here see that the root hairs are formed by the elongation of 
certain of the surface cells of the root. These cells elongate 
perpendicularly to the root, and become 3mm to 6mm long. 
They are flexuous or irregular in outline and cylindrical, as 
shown in fig. 24. The end of the hair next the root fits in 
between the adjacent superficial cells of the root and joins 
closely to the next decper layer of cells. In studying the 
section of the young root we see that the root is made up of 
cells which lie closely side by side, each with its wall, its 
protoplasm, and cell-sap, the protoplasmic membrane lying on 
+he inside of each cell wall. 


38 BOTANY. 
Demonstration 14. 
75. To show the relation of the root hairs to the other cells of the root.— 


The teacher can make thin sections of young roots, with a razor, through the 
region of the root hairs, and mount them for microscopic study for demon- 


| 


| 
1 
" 


\, 
q \ 


/ 


2 


Fig. 24. 
Section of corn root, showing rhizoids formed from elongated epidermal cells. 


stration before the class. Let each member of the class sketch a portion of 
the section, to show the root hairs, their relation to the other cells of the root, 
as well as some of the characters of the tissues of the root. 

76. Action of the cell-sap.—In the absorption of the watery 
solutions of plant food by the root hairs, the cell-sap, being a 
more concentrated solution, gains some of the former, since the 
liquid of less concentration flows through the protoplasmic 
membrane into the more concentrated cell-sap, increasing the 
bulk of the latter. This makes the root hairs turgid, and at the 
same time dilutes the cell-sap so that the concentration is not so 
great. The cells of the root lying inside and close to the base of 


! 


HOW PLANTS OBTAIN THEIR LIQUID FOOD. 39 


the root hairs have a cell-sap which is now more concentrated 
than the diluted cell-sap of the hairs, and consequently gain some 
of the food solutions from the latter, which tends to lessen the 
content of the root hairs and also to increase the concentration of 
the cell-sap of thesame. This makes it possible for the root hairs 
to draw on the soil for more of the food solutions, and thus, by 
a variation in the concentration of the substances in solution in 
the cell-sap of the different cells, the food solutions are carried 
along until they reach the vascular bundles, through which the 
solutions are carried to distant parts of the plant. In this way a 
pressure is produced which causes the liquid to rise in the plant. 

77. How the root hairs get the watery solutions from the 
soil__tlf{ we examine the root hairs of a number of seedlings 
which are growing in the soil under normal conditions, we shall 


Root hairs of corn seedling with soil particles adhering closely. 


LIT) {K/ sce that a large quantity of soil readily clings to 

the roots. We should note also that unless the 

soil has been recently watered there is no free water in it; the 
soil is only moist. We are curious to know how plants can 
obtain water from soil which is not wet. If we attempt to 
wash off the soil from the roots, being careful not to break 


40 BOTANY. 


away the root hairs, we find that small particles cling so 
tenaciously to the root hairs that they are not removed. 
Placing a few such root hairs under the microscope it appears 
as if here and there the root hairs were glued to the minute 
soil particles. 

In soil most suitable for the growth of land plants the water is 
not in excess. It is in the form of a thin film surrounding the 
soil particles. Some of the soil particles being ‘‘ glued’’ to 
the root hairs, this portion of the water film is brought into 
close contact with the root hairs so that it can be absorbed. 
Plants cannot remove all the water from the soil. 


Note,—Some plant food is in solution in the water of the soil, but much 
of it is in an insoluble form (minute particles, or rocks, containing mineral 
substances), or in the form of organic matter (as leaves, stems, or other plant 
parts, or animal matter). The organic matter in the soil is in process of 
decay because certain microscopic fungi, and especially bacteria, feed upon 
it and change some of it into a form which can be taken up as food by the 
higher plant. The insoluble particles, containing mineral substances, are 
constantly being corroded by the action of certain acids, especially carbonic 
acid, which is constantly being formed in the soil. The walls of the root hairs 
are also saturated with this acid, and thus they are able to dissolve some of 
these mineral substances. This corroding action of the roots can be well 
shown by placing a small marble plate in a pot; then plant beans or peas on 
the plate, and cover with earth. In lieu of the marble plate the peas may be 
planted in clam, or oyster, shells, which are then buried in the soil of the 
pot, so that the roots from the seedlings will come in contact with the smooth 
surface of the shell, or of the marble if that is used. After the plants have 
been growing two or three weeks, remove the soil, and wash the surface of 
the marble or shell. Hold the surface now toward the window in such a 
way as to see the light reflected from the surface. The surface has been 
etched by the action of the roots. 


Demonstration 15 (or Exercise). 


78. Plants can obtain water from soil which appears dry. —Use small pots 
with well-grown seedlings. Place the pots in a dry room. Supply no water 
to the soil. From day to day observe the condition of the soil, and feel of it 
to note the condition of dryness. Can plants live and grow in a soil which 
looks and feels dry ? 

When the plants have wilted remove them from the soil. Weigh the pot 
of soil. Then place it in an ovenand bake it. Weigh again. Has it lost 


HOW PLANTS OBTAIN THEIR LIQUID FOOD. 41 


weight? Can plants remove all the moisture from the soil by absorption 
through their roots ? 


Demonstration 15a (or Exercise). 


78a. To demonstrate the action of a root hair.—Takea long potato, cut off 
the ends squarely, and bore a smooth hole 
from one end nearly through to the other 
end, being careful not to split the potato. 
Now pare off the sides to make a tube closed 
at one end. Rest the closed end in a vessel 
of water, as shown in fig. 25a, after having 
filled the tube with sugar. After five or 
six hours examine. The sugarinside of the 
potato tube draws water inward from the 
vessel, imitating the action of a root hair. 


Exercise 18. 


A a 5 Fig. 25a. 
79. Salt particles cling to root hairs.— A Potaen with venmal aly eon 


Have at hand small pots of seedlings the taining sugar, standing in vessel of 
‘i of which i Pull ai water. , section of potato tube 
soil of which is not wet. ul, or dig, Up 4 showing cavity only partly filled with 
seedling. Observe the soil clinging to the S"84"- (After MacDougal.) 
roots. Agitate it to remove as much of the soil as possible. Wash the roots 
by rinsing in water. Are all the soil particles removed? To what portions 
of the roots does most of the soil cling? Why? Compare with seedlings 
grown in a germinator free from soil. 


III. Strone Sotutions or Prant Foop are Inyurious. 


Exercise 19 (or Demonstration). 


80. To show the eftect on plants of food solutions which are too strong. — 
Potassium nitrate is one of the food substances used in the water cultures. 
It is also one of the necessary food substances from which nitrogen is 
obtained for the plant. Take strongly concentrated solutions, say a 5%, a 10%, 
and a 20% solution. Label three pots of seedlings to correspond with the 
solutions. Pour in enough of each solution to the corresponding pots to 
saturate the soil. In the course of three or four hours (or later) observe the 
result. Observe the condition of the stems at the surface of the ground. 
Explain the result in each case. Permit these to remain without watering 
for a day to see if they will revive. Pour in water and wash through 
to remove as much of the salt as possible. Set them aside for a day or two. 
Do they revive? Why? 


42 BOTANY. 


81. Food solutions which are too strong injure plants 
instead of benefiting them.—In figures 27 to 33 are shown the 
results of some experiments 
with strongly concentrated 
food solutions. In this case 
the food substance is potas- 
sium nitrate. Solutions of 
this salt of 2%, 5%, 10%, and 
20% were prepared. Three 
pots of pumpkin seedlings 
were employed. In one the 
soil (which was already quite 
moist in all of the pots) was 
saturated with the 2%, one with 
the 10%, and the other with the 
20% solution. In a few hours 
the seedlingsin pots 31 and 32 
had collapsed, while those in 
pot 30 were still rigid. The 
salt in 31 and 32, being, even 
when diluted with the water in 
the soil, stronger than the salts 

ae in the cell-sap, withdrew water 

Pumpkin seedling aemoved from soil to show from the root hairs, roots, and 

Rae Ee ree from the lower part of the 

stems, so that the plants lost their rigidity. The lower part of 

the stems was flabby. The plants were then photographed as 

shown in figures 30-32. Some of the 5% solution was then 

added to pot 30. In four hours (at 6 p.m.) two of the seed- 

lings showed signs of collapse. On the following morning 

these two had collapsed, and the photograph of the result is 
shown in figure 33. 


Synopsis.—Plants obtain their food either in a liquid or a gaseous form. 
Plants obtain their liquid food (mostly certain mineral and nitrogenous 
substances) by absorption. 


HOW PLANTS OBTAIN THEIR LIQUID FOOD. 43 


Fig. 27. Fig. 28. Fig. 29. 
2% solution potassium 10% solution potassium 20% solution potassium 
nitrate. nitrate. nitrate, 


Figures 27-29.—Pumpkin seedlings, soil watered with solution of potassium nitrate of 
lifferent strengths, Photographed immediately after the application of the solution to 
he soil. 


Fig. 30. Fig. 31. Fig. 32. 
2% solution potassium 10% solution potassium 20% solution potassium 
nitrate. nitrate. nitrate, 


Figures 30-32.—Pumpkin seedlings, soil watered with solution of potassium nitrate 
of different strengths. Photographed four hours after application of the solution to 


the soil. 


44 BOTANY. 


Plants having a root system in comparatively dry ground absorb their 
liquid food through root hairs and roots. 

Aquatic plants (plants in water) absorb liquid food through nearly the 
entire surface in contact with the water. 

The plant food must be in a very dilute solution; a strong solution injures 
the plant, and, if too strong, 
will kill the plant, because 
by the law of diffusion the 
water in the plant is removed 
to such an extent that the 
plant becomes flabby, and if 
turgor is not restored, the 
plant will die. 

Soil which is not saturated 
with water, i.e., that which 


is only moist, or even which 
may seem dry, still contains 
water which formsa thin film 
(capillary film) around the 
soil particles. 

The root hairs become 
firmly fixed to certain of the 
soil particles and are thus 
brought in close contact with 

Pot in which the 2% solution was poured. the water film which contains 
After four hours a 5% solution of potassium ni- = mineral and nitrogenous food 


trate was added. This caused two of the seed- 2 é ‘ 
lings to collapse after about ten hours. Photo- in solution. This film is con 


graphed eighteen hours after last application. tinuous from one soil particle 
to another in soil of the right texture and physical properties, and thus as 
the root hairs absorb that portion of the film in contact with them, by capil- 
larity the film draws more water through the soil from moist places. 

Materials:— Potassium nitrate, sodium chloride, calcium sulphate, mag- 
nesium sulphate, calcium phosphate, for nutrient solution as per paragraph 
68. A larger amount of potassium nitrate (saltpetre) for exercise I9. 

Wide-mouth bottles, or small crockery jars, with perforated corks to fit, for 
the water culture. 

Seedlings started ina germinator. 

Seedlings, grown in pots, two or three weeks old, for exercises 17 and 18, 

One or more long potatoes ; sugar. 

Microscope, etc. Razor. 


Fig. 33. 


CHAPTER VIII. 


, HOW SOME PLANT PARTS REMAIN RIGID. 


82. Turgidity of plant parts.—In Chapter VI we found that 
‘he turgescence of a cell depends on the absorption of water by 


Fig. 34. ‘ Fig. 35. 
ndian turnip plant just removed from the Same plant half an hour later. It is be- 
soil. It is rigid. coming limp. 


yrotoplasm. The protoplasm permits the cell-sap to draw the 

water inward by diffusion, but the protoplasmic membrane does 

ot permit the water to filter out readily, and the outward pressure 
45 


46 BOTANY. 


of the protoplasm on the elastic cell wall makes the cell turgid. 
So we found in the experiments with the slices of beet in the salt 
solution and water that the partial removal of the water from the 
beet leaves the slices limp, while they regain their rigidity if the 
salt solution is removed and the slices are placed in water. We 
should now endeavor to see if water plays any part in the rigidity 
of plant parts, as in the case of shoots, leaves, etc., and in what 
way this rigidity may be lost and regained. 


Exercise 20. 


83. Loss of turgidity in cut shoots.—From a living geranium, balsam, 
coleus, or other plant, cut a leafy shoot 15cm to 20cm long. Leave it in a 
dry room for a short while until 
it partly wilts. Grasp the shoot 
at the cut end and attempt to 
hold it erect. How does it now 
compare with its condition when 
first cut from the plant ? 

84. Restoration of turgidity 
in shoots.—Take the leafy shoot 
used in paragraph 83. (It should 
not be so wilted that any portion 
of it isdry.) Cut the end fresh 
again and place it in a vessel of 
water, and if the room is dry, 
cover the vessel and shoot with 
a tall glass cylinder or bell jar. 
Observe the result in a few hours, 
or on the following day. 


85. Longitudinal tissue 
tension.—For this in early 
summer one may use the 
young and succulent shoots 
of the elder (sambucus); 


Fig. 36. ‘i 
Same plant photographed four hours later, It or the petioles of rhubarb 


h d. ‘ 
as revive during the summer and early 


autumn; or the petioles of richardia. Petioles of caladium are 


HOW SOME PLANT PARVS REMAIN RIGID. 47 


excellent for this purpose, and these may be had at almost 
any season of the year from the greenhouses, and are thus 
especially advantageous for work 
during late autumn or winter. 
The tension is so strong that a 
portion of such a petiole 10- 
15cm long is ample to demon- 
strate it. As we grasp the lower 
end of the petiole of a caladium, 
or rhubarb leaf, we observe how 
rigid it is, and how well it sup- 
ports the heavy expanded lam- 
ina of the leaf. 


Exercise 21. 


86. To demonstrate the tissue ten- 
sion.— Take a portion of the petiole of a 
caladium, or of celery, or other plant, 
about 15¢m long. Cut the ends off 
squarely. With a knife strip off a layer 
from the outside about 2-37m in thick- 


: Fig. 37. Fig. 38. Fig. 39. 
ness, and the full length of the piece. Centre of Outside Outside strip 


i ‘ etiole, strip. attached to 
Now attempt to replace it, comparing the ? P Sone 


length of each part. Remove another Figures 37-39. Showing longitudinal 
strip lying next this one, and so on tssue/tension, 

until all the outer portion has been removed. Describe what takes place as 
the successive strips are removed. When all are removed, compare an outside 
strip with the central portion. What has happened? Is there now a greater 
difference in length between the outside strip and the central portion? What 
is the cause of this? Describe the tensions in the outside and inner portion 
of the petiole. 

Cut a section of the petiole about 8c7z long, remove strips on two opposite 
sides and split the remainder down the middle, securing two pieces with the 
center and outside portion attached. Place one of these in fresh water and 
the other in a 5 per cent salt solution and note the result. If convenient 
treat celery petioles in the same way. The flower stems of dandelions split 
into quarters are-excellent objects to compare when placed in water, and in 
a 5 per cent salt solution. 


48 BOTANY. 


Exercise 22. 


87. Transverse tissue tension.—To show this take a willow shoot 3-5cm 
in diameter and saw off sections about 2cm long. Cut through the bark on 
one side, and peel off the bark in one piece carefully, Now attempt to re- 
place it. What has happened? Describe the tension. 


Demonstration 16. 


88. Importance of tissue tension.—To demonstrate the efficiency of this 
tension in giving support, let us take a long petiole of caladium or of rhubarb. 
Hold it by one 
end in a hori- 
zontal position. 
It is firm and 
rigid, and does 
not droop, or 
but little. Re- 
move all of the 
outer portion of 
the tissues, as 
described 
above, leaving 
only the central 
portion. Now 
attempt to hold 
it in a horizon- 
tal position by 
one end. It is 
flabby and 
droops down- 


Fig. 40. 


Caladium leaf petiole rigid from longitudi- 
nal tensions. 


ward because the longitudinal ten- 
sion is removed. (See figs. 40, 41.) 

Synopsis.—When plants are re- 
moved from the soil, or plant parts 
are removed from the shoot, they 


soon become flabby and limp. Fig F ; 
. 4T 


When these partly wilted plants Same leaf, longitudinal tension partly removed 
are placed with the stems in water, by the loss of two outside strips. 


they may become rigid again by the absorption of water and the restora- 
tion of the rigidity of the cells. 


HOW SOME PLANT PARTS REMAIN RIGID. 49 


Succulent stems and petioles are often kept rigid be- 
cause of a pull, or tension, of different layers of 
cells in opposite directions. The outer layers of 

Longitudinal tissue cells tend to shorten, while the inner cells tend to 

4 lengthen. 

These opposite tensions, or pulls, make the shoot 
rigid. 

The cells of the shoots must be turgid with water or 
the tension is not present. 


tension. 


4 L 


Transverse tissue This occurs where the outer layers of tissue are 
tension, stretched transversely instead of longitudinally. 


Material.—If fresh plants cannot be obtained out-doors, use leafy shoots 
of rather succulent plants from the green-house, like the coléus plant, 
garden balsam, or leaves with long petioles like the caladium of the green- 
house, or stored celery. The shoots should not be cut from the plant until 
the pupil isready to begin the exercise. Wide-mouthed bottles, filled with 
water, and if necessary some bell jars (one large bell jar will answer for 
several students). 


CHAPTER IX. 
HOW WATER MOVES THROUGH THE PLANT. 


I. Roor Pressure, or Osmotic PRESSURE. 


89. Flow of water from pruned vines.—It is a very common 
thing to note, when certain shrubs or vines are pruned in the 
spring, the exudation of a watery fluid from the cut surfaces. 
In the case of the grape vine this has been known to continue 
for a number of days, and in some cases the amount of liquid, 
called ‘‘ sap,’’ which escapes is considerable. In many cases it 
is directly traceable to the activity of the roots, or root hairs, 
in the absorption of water from the soil. For this reason the 
term root pressure is used to denote the force exerted in supply- 
ing the water from the soil. 

90. Root pressure may be measured.—It is possible to 
measure not only the amount of water which the roots will raise 
in a given time, but also to measure the force exerted by the 
roots during root pressure. It has been found that root pressure 
in the case of the nettle is sufficient to hold a column of water 
about 4.5 meters (15 ft.) high (Vines), while the root pressure 
of the vine (Hales, 1721) will hold a column of water about 10 
meters (36.5 ft.) high, and the birch (Betula lutea) (Clark, 
1873) has a root pressure sufficient to hold a column of water 
about 25 meters (84.7 ft.) high. 


Demonstration 17. 


91. To demonstrate root pressure.—Use a potted begonia or balsam, the 
latter being especially useful. The plants are usually convenient to obtain 
from the greenhouses, to illustrate this phenomenon. Cut off rather close to 


50 


HOW WATER MOVES THROUGH THE PLANT. 51 


soil and attach a long glass tube to the cut end of the stem, still con- 
2cted with the roots, by the use of rubber tubing as shown in figure 42. A 
‘ry small quantity of water may be poured in to mois- 
n the cut endof the stem. In a few minutes the water 
>gins to rise in the glass tube. In some cases it rises 
uite rapidly, so that the column of water can readily 
2 seen to extend higher and higher up in the tube 
hen observed at quite short intervals. The height 
‘this column of water is a measure of the force exerted 
y the roots. The pressure force of the roots may be 
easured also by determining the height to which it 
ill raise a column of mercury. 


Exercise 23. 


92. To make records of the experiment.—The pupils 
in take notes on the experiment at the time it is set up. 
hen for several days let them keep a record of the 
sight of the liquid in the tube, taken at several times 
day if possible. 


Fig. 42. 
93. Variation in root pressure.—In either Experiment to 
‘ A . show root pressure, 
ise where the experiment is continued for (Detmer.) 


sveral days it is noticed that the column of water or of mercury 
ses and falls at different times during the same day, that is, the 
slumn stands at varying heights; or in other words the root 
ressure varies during the day. With some plants it has been 
rund that the pressure is greatest at certain times of the day, or at 
srtain seasons of the year. Such variation of root pressure ex- 
ibits what is termed a periodicity, and in the case of some plants 
.ere is a daily periodicity; while in others there is in addition an 
anual periodicity. With the grape vine the root pressure is 
-eatest in the forenoon, and decreases from 12-6 p.m., while 
ith the sunflower it is greatest before 10 a.m., when it begins to 
ecrease. Temperature of the soil is one of the most important 
cternal conditions affecting the activity of root pressure. 


II. Tue Loss or Water By Piants (TRANSPIRATION). 


94. Wilting of cut shoots,—We should now inquire if all the 
ater which is taken up in excess of that which actually suffices 


52 BOTANY. 


for turgidity is used in plant growth and in the increase of plant 
substance. We notice when a leaf or shoot is cut away from a 
plant, unless it is kept in quite a moist condition, or in a damp, 
cool place, that it becomes flaccid, and droops. It wilts, as we 
say. The leaves and shoot lose their turgidity. This fact suggests 
that there has been a loss of water from the shoot or leaf. It can 
be readily seen that this loss is not intheform of drops of water 
which issue from the cut end of the shoot or petiole. What 
then becomes of the water in the cut leaf or shoot ? 


Exercise 24. 


95. Loss of water from excised leaves.—Take a handful of fresh, green, 
rather succulent leaves, which are free from water on the surface, and place 
them under a’glass bell jar, which is tightly closed below but which contains 


Fig. 43. Fig. 44. 
Leafy shoots just covered with dry The same after four hours; mist 
bell jar. shows on inside of jar. 


Figures 43, 44.—Experiment to show transpiration from leaves on cut shoots, 


no water. Place this in @ brightly lighted window, or in sunlight. In the 
course of fifteen to thirty minutes notice that a thin film of moisture is ac- 
cumulating on the inner surface of the glass jar. After an hour or more the 
moisture has accumulated so that it appears in the form of small drops of 
condensed water. . Set up at the same time a bell jar in exactly the same 
way but which contains no leaves. In this jar there will be no condensed 
moisture on the inner surface. We thus are justified in concluding that the 
moisture in the former jar comes from the leaves. Since there is no visible 


HOW WATER.MOVES THROUGH THE PLANT. 53 


rater on the surfaces of the leaves, or at the cut ends, before it may have 
ondensed there, we infer that the water escapes from the leaves in the form 
£ water vapor, and that this water vapor, when it comes in contact with the 


Fig. 45. Fig. 46. 
Leaves removed to show drops of water Photographed after the water has been 
on inside of jar. wiped from inside of jar. 


irface of the cold glass, condenses and forms the moisture film, and later 
ie drops of water. The leaves of these cut shoots therefore lose water in 
1e form of water vapor, and thus a loss of turgidity results. 


Demonstration 18. 


96. Loss of water from growing plants.—Suppose we now take a small 
nd actively growing plant in a pot, and cover the pot and the soil with a 
ieet of rubber cloth which fits tightly around the stem of the plant (or the 
ot and soil may be enclosed in a hermetically sealed vessel) so that 
1e moisture from the soil cannot escape. Then place a bell jar over the 
lant, and set in a brightly lighted place, at a temperature suitable for 
rowth. In the course of a few minutes on a dry day a moisture film forms 
1 the inner surface of the glass, just as it did in the case of the glass jar 
mtaining the cut shoots and leaves. Later the moisture has condensed so 
iat it is in the form of drops. If we have the same leaf surface here as we 
ad with the cut shoots, we will probably find that a larger amount of 
ater accumulates on the surface of the jar from the plant that is still at- 
.ched to its roots. 


97. Water escapes from the surfaces of living leaves in the 
xm of water vapor.—This living plant then has lost water, 
hich also escapes in the form of water vapor. Since here there 


54 BOTANY. 


are no cut places on the shoots or leaves, we infer that the loss 

of water vapor takes place from the surfaces of the leaves and 

from the shoots. It is also to be noted that, while this plant is 
losing water from the surfaces of the leaves, it does not wilt or 
lose its turgidity. The roots by their activity and osmotic 
pressure supply water to take the place of that which is given 
off in the form of water vapor. This loss of water in the form 
of water vapor by plants is /ranspiration. 

Synopsis. 

As a result of the law of diffusion by which water from the 
soil is drawn inside the root hairs forcibly by the cell- 
sap, and is passed on through the cells of the root by 
the same law of diffusion, a pressure occurs which causes 
the liquid plant food to rise to some extent in the roots 
and stems of plants. 

The height to which water can be lifted by root pressure 
varies in different plants. 

Root pressure | Root pressure is not constant throughout the day in a 


or osmotic given plant, but varies. 
pressure. Root pressure is usually lower at night and higher toward 
midday. 


Plants then show a daily periodicity in the strength of the 
root pressure, but the periods are not coincident in all 
plants ; that is, the time of day when one plant shows 
the greatest root pressure is not necessarily the same for 
another plant. 

Some plants also show an annuai periodicity in the strength 

. of the root pressure. 

, Living plants are constantly losing water by evaporation 
(or transpiration) from the surface, unless the air is sat- 
urated with moisture. 

If plants are removed from the soil, or shoots are cut away, 
they ‘wilt,’ or become flabby, because of the loss of 
water. 

This loss of water from plants, or plant parts, can be dem- 
onstrated by placing the plant under a glass receiver. 

The water escapes in the form of invisible water vapor. 

When the plant is growing normally, the roots by absorp- 
tion of water from the soil supply water to take the 

place of that evaporated from the exposed plant surface. 


Transpiration. 4 


HOW WATER MOVES THROUGH THE PLANT. 55 


Material.—For root pressure: One or more potted plants like a begonia, 
garden balsam, etc. A long glass tube about the same diameter as that of 
the plant stem ; some rubber tubing to connect the glass with the stem, and 
to connect sections of tubing if necessary. 

For transpiration: Some succulent leaves and leafy shoots, like gera- 
nium, coleus, balsam, etc. Some small glass bell jars. A potted coleus 
plant (or balsam), some sheet rubber to cover the pot and earth closely, and 
a bell jar to cover the plant. 


CHAPTER X. 


HOW WATER MOVES THROUGH THE PLANT— 


CONCLUDED. 


III. Part wHicH THE Lear PLAYS IN TRANSPIRATION. 


Demonstration 19. 


98. Structure of a leaf.—We are now led to inquire why it is that a 
living leaf loses water less rapidly than dead ones, and why less water 
escapes from a given leaf surface than from an equal surface of water. To 
understand this it will be necessary to examine the minute structure of a 
leaf. For this purpose we will select the leaf of an ivy, though many other 


Section through ivy leaf show- 
ing communication between sto- 
mate and the large intercellular 
spaces of the leaf ; stoma closed. 


leaves will answer equally well. From a por- 
tion of the leaf we should make very thin 
cross-sections with a razor or other sharp in- 
strument. These sections should be perpen- 
dicular to the surface of the leaf, and should 
be then mounted in water for microscopic 
examination. * 

Let the pupils examine the preparations and 
make sketches of the structure of the leaf, 
naming the different kinds of cells, and de- 
scribing the function of the different groups 
of cells. (See paragraphs 99-101.) 


99. Epidermis of the leaf.—In this 
section we see that the green part of 
the leaf is bordered on what are its 
upper and lower surfaces by a row 


of cells which. possess no green color. The walls of the cells 
of each row have nearly parallel sides, and the cross walls are 
perpendicular. These cells form a single layer over both sur- 


* Demonstrations may be made with prepared sections of leaves. 


56 


HOW WATER MOVES THROUGH THE PLANT. 57 


faces of the leaf and are termed the egzdermzs. Their walls are 
quite stout and the outer walls are cusicularized. 

100. Soft tissue of the leaf.—The cells which contain the 
green chlorophyll bodies are arranged in two different ways. 
Those on the upper side of the leaf are usually long and _ pris 
matic in form and lie 
closely parallel to 
each other. Because 
of this arrangement 
of these cells they are 
termed: the padisade 


Fig 49. 
cells, and form what Stoma open. Stoma closed. 


Figures 48, 49. - Section through stomata of ivy leaf. 


is called the palisade 
layer. The other green cells, lying below, vary greatly in size in 
different plants and to some extent also in the same plant. Here 
we notice that they are elongated, or oval, or somewhat irregular 
in form. The most striking peculiarity, however, in their arrange- 
ment is that they are not usually packed closely together, but each 
cell touches the other adjacent cells only at certain points. This 
arrangement of these cells forms quite large spaces between 


them, the 
Fig. 50. 


intercellular 
spaces. If 
we_ should 

examine 

Portion of epidermis of ivy, showing irregular epidermal cells, stoma would see 
and guard cells. that the in- 

tercellular spaces are not filled with water or cell-sap, but are 
filled with air or some gas. Within the cells, on the other 


such a sec- 
tion ofa leaf 
hand, we find the cell-sap and the protoplasm. 


before it is 


mounted in 


A 


water we 


58 BOTANY. 


101. Stomata.—If we examine carefully the row of epidermal 
cells on the under surface of the leaf, we will find here and there 
a peculiar arrangement of cells shown at figs. 47-49. This 
opening through the epidermal layer is a sfoma. The cells which 
immediately surround the openings are the guard cells. The 
form of the guard cells can be better seen if we tear a leaf in 
such a way as to strip off a short piece of the lower epidermis, 
and mount this in water. The guard cells are nearly crescent 
shaped, and the stoma is elliptical in outline. The epidermal 
cells are very irregular in outline in this view. We should also 
note that while the epidermal cells contain no chlorophyll, the 
guard cells do. 


102. The living protoplasm retards the evaporation of 
water from the leaf.—If we now take into consideration a few 
facts which we have learned in a previous chapter, with refer- 
ence to the physical properties of the living cell, we will be able 
to give a partial explanation of the comparative slowness with 
which the water escapes from the leaves. The inner surfaces of 
the cell walls are lined with the membrane of protoplasm, and 
within this is the cell-sap. These cells have become turgid by 
the absorption of the water which has passed up to them from 
the roots. While the protoplasmic membrane of the cells does 
not readily permit the water to filter through, yet it is saturated 
with water, and the elastic cell wall with which it is in contact 
is also saturated. From the cell wall the water evaporates into 
the intercellular spaces. But the water is given up slowly 
through the protoplasmic membrane so that the water vapor 
cannot be given off as rapidly from the cell walls as it could if 
the protoplasm were dead. The living protoplasmic membrane 
then, which is only slowly permeable to the water of the cell- 
sap, is here a very important factor in checking the too rapid 
loss of water from the leaves. 

108. Communication through intercellular spaces.—By an 
examination of our leaf section we see that the intercellular 


HOW WATER MOVES THROUGH THE PLANT. 59 


spaces are all connected, and that the stomata, where they 
occur, open also into intercellular spaces. There is here an 
opportunity for the water vapor in the intercellular spaces to 
escape when the stomata are open. 

104. Action of the stomata.—Besides permitting the escape 
of the water vapor when the stomata are open they serve a very 
important office in regulating the amount of transpiration. 
During normal transpiration the stomata remain open, that is, 
when the amount of transpiration from the leaf is not in excess 
of the supply of water to the leaves. But when the transpiration 
from the leaves is in excess, as often happens, and the air 
becomes very dry, the stomata close, and thus the rapid trans- 
piration is checked. 

For further discussion of transpiration and root pressure see 
the author’s larger ‘‘ Elementary Botany.’’ 


Synopsis. 
( Epidermis. The epidermal cells usually lack chloro- 
phyll. 

Upper epidermis, a layer of cells over the upper 

surface of the leaf. 

Lower epidermis, a layer of cells over the 

lower surface of the leaf. 

Guard cells of the stomates (openings in the 

epidermis) contain chlorophyll. 

(Hairs of various kinds on different leaves are 

often present: see synopsis of tissues at close 
of Chapter XI.) 
Mesophyll (the cells of the leaf between the upper 
and lower epidermis) 

1. Palisade layer of cells, usually next the 
upper epidermis. Contains chlorophyll. 

2. Loose parenchyma cells, with large inter- 
cellular spaces where the air and water 
vapor can circulate. Cells contain chloro- 
phyll. 

(Vascular bundles are present in the ‘‘ veins’’ of 
the leaf: see Chapter NI.) 


Structure of a leaf 
(cross-section). 


Function of the leaf 
in transpiration. 


BOTANY. 


( The living protoplasm retards the evaporation of 
water somewhat from the cells. 

The water escapes from the cells of the middle part 
of the leaf into the intercellular spaces. From 
here it passes out through the openings (sto- 
mates), 

When transpiration is in excess of root pressure, 
the guard cells close together and shut the open- 
ing, and thus greatly retard the loss of water. 

The cuticle, a thin deposit on the outer surface of 
the epidermal cells, also retards more or less 


transpiration. 


Material.—Fresh leaves of some plant like begonia, ivy, or other leaf 
which is easy to section. Where preferred, permanently mounted slides of 
sections of leaves may be used. 


CHAPTER XI. 
.PATH OF MOVEMENT OF LIQUIDS IN PLANTS. 


105. Course of the liquids through the stems.—lIn our study 
of root pressure and transpiration we have seen that large quan- 
tities of water or solutions move upward through the stems of 
plants. We are now led to inquire through what part of the 
stems the liquid passes in this upward movement, or in other 
words, what is the path of the ‘‘sap’’ as it rises in the stem. 
This we can readily see by the following trial. 


Demonstration 20. 


106. To show the tracts through which the liquids rise.—Cut off leafy 
shoots of various plants and insert the cut ends in a vessel of water to which 
has been added a few crystals of the dye known as fuchsin to make a 
deep red color (other red dyes may be used, but this one is especially good). 
If the study is made during the summer, the ‘‘ touch-me-not ”’ (impatiens) 
will be found a very useful plant, or the garden balsam, which may also be 
had in the winter from conservatories. Almost any plant will do, however, 
but we should also select one like the corn plant (Zea mays) if in the 


summer. 


107. These solutions color the tracts in the stem and leaves 
through which they flow.—After a few hours in the case of the 
impatiens, or the more tender plants, we can see through the 
stem that certain tracts are colored red by the solution, and 
after 12 to 24 hours there ntay be seen a red coloration of the 
leaves of some of the plants used. After the shoots have been 
standing in the solution for a few hours, if we cut them 
at various places we shall note that there are several points in 


the section where the tissues are colored red. In the impatiens 
61 


62 BOTANY. 


perhaps from four to five, in the sunflower a larger number. 
In these plants the colored areas on a cross-section of the stem 
are situated in a concentric ring which separates more or less 
completely an outer ring of the stem from the central portion. 
If we now split portions of the stem lengthwise we see that these 
colored areas continue throughout the length of the stem, in 
some cases even up to the leaves and into them. 

108. Arrangement of the tracts in the corn stalk.—If we 
cut across the stem of a corn plant which has been in the solu- 


Fig. 51. 
Broken corn stalk, showing fibro-vascular bundles, 


tion, we see that instead of the colored areas being in a con- 
centric ring they are irregularly scattered, and on splitting the 
stem we see here also that these colored areas extend for long 
distances through the stem. 


Exercise 25. 


109. To demonstrate the tracts in stems and petioles.—Take leaves of a 
calla lily, or of a caladium, which grow in conservatories, and good leaves 
of stored celery, with long petioles. Other leafy shoots which are more 
accessible may be used, if desired. Place the ends of the petioles, or the 
shoots, in a solution of fuchsin, or in red ink. 1n the course of an hour (they 
may be left in a longer time if necessary) observe the petioles and leaves. 
Can any cf the color be seen without cutting into the stem? (Where the 


PART OF MOVEMENT OF LIQUIDS IN PLANTS. 63 


shoots remain inthe colored liquid for a day, or even for a less time, portions 
of the leaves will show the color.) Cut across the stems, and describe the 
location of the colored areas. Split the petioles or stems and trace the colored 
tracts. Compare their location in the calla and the celery petiole. 

110. To observe the texture of these areas in a celery petiole.—Take fresh 
but rather old celery leaves (from stored celery if in the winter). Break the 
petiole apart. Is the broken part ragged? Is there any difference in the 
texture or toughness of the petiole shown by any portions ‘stringing ’’ out? 
Describe the location of these strands. What are they? Have they any re- 
lation to the colored areas or tracts in the petiole which was in the red ink? 
Break apart in a similar way a petiole which has been in the red ink. 
Compare. The celery represents a dicotyledenous plant, 

111. The strands in a dead corn stalk.—Take a dead corn stalk (they are 
easily obtained in the autumn or winter from the fields). Cut through the 
outer harder portion of the stem. Break it. Compare carefully with the 
broken celery petiole. The corn stem represents a monocotyledonous plant. 


112. There are definite courses through which the liquids 
rise.—We thus see that instead of the liquids passing through 
the entire stem they are confined to definite courses. Now that 
we have discovered the path of the upward movement of water 
in the stem, we are curious to see what the structure of these 
definite portions of the stem is. 


Demonstration 21. 

113. Structure of the fibrovascular bundle.—Make quite thin cross-sec- 
tions of the stem it is desired to study, and mount in water for microscopic 
examination. Permanent mounts may be made in Canada balsam by those 
who understand the method. Or mounted preparations may be obtained, 
which will preserve for future use. Let each pupil examine cross and longi- 
tudinal sections of a dicotyledon and of a monocotyledon, making out 
clearly the different groups of tissues, and the kinds of ceils composing them. 
Paragraphs 114-123 may be used as a guide. The description is here made 
from the castor-oil bean, and the illustration from the sunflower to represent 
the dicotyledon, while the corn stem is used to illustrate the monocotyledon. 
It will be no disadvantage for the teacher to use other plants than those em- 
ployed here for the demonstration. 

114. The bundles in a dicotyledon.—To illustrate the structure of the 
bundle in one type we may take the stem of the castor-oil bean. On examin- 
ing these cross-sections we see that there are groups of cells which are denser 
than the ground tissue. These groups correspond to the colored areas in the 
former experiments, and are the vascular bundles cut across. These groups 


64 BOTANY. 


are somewhat oval in outline, with the pointed end directed toward the centre 
of the stem. If we look at the section as a whole we see that there is a nar- 


Fig. 52. 
Xylem portion of bundle. Cambium portion of bundle. Bast portion of bundle. 
Section of vascular bundle of sunflower stem, 


row continuous ring * of small cells situated at the same distance from the 
centre of the stem as the middle part of the bundles, and that it divides the 
bundles into two groups of cells. 

115. Woody portioa of the bundle.—In that portion of the bundle on the 
inside of the ring, i.e., toward the ‘‘pith,’’ we note large, circular, or angu- 
lar cavities. The walls of these cells are quite thick and woody. They are 
therefore called wood cells, and because they are continuous with cells above 
and below them in the stem in such a way that long tubes are formed, they 
are called woody vessels. Mixed in with these are smaller cells, some of 
which also have thick walls and are wood cells. Some of these cells may 
have thin walls. This is the case with all when they are young, and they 
are then classed with the fundamental tissue or soft tissue (parenchyma). 
This part of the bundle, since it contains woody vessels and fibres, is the 
wood portion of the bundle, or technically the xylem. 


* This ring and the bundles separate the stem into two regions, an outer 
one composed of large cells with thin walls, known as the cortical cells, or 
collectively the cortex. The inner portion, corresponding to what is called 
the pith, is made up of the same kind of cells and is called the medulla, or 
pith. When the cells of the cortex, as well as of the pith, remain thin-walled 
the tissue is called parenchyma. Parenchyma belongs to the group of tis- 
sues called fundamental. 


PART OF MOVEMENT OF LIQUIDS IN PLANTS. 65 


116. Bast portion of the bundle.—If our section is through a part of the 
stem which is not too young, the tissues of the outer part of the bundle will 
show either one or several groups of cells which have white and shiny walls, 
that are thickened as much or more than those of the wood vessels. These 
cells are dast cells, and for this reason this part of the bundle is the das¢ 
portion, or the ps/oem. Intermingled with these, cells may often be found 
which have thin walls, unless the bundle is very old. Nearer the centre of 
the bundle and still within the bast portion are cells with thin walls, angular 
and irregularly arranged. This is the softer portion of the bast, and some 
of these cells are what are called szeve tubes, which can be better seen and 
studied in a longitudinal section of the stem. 

117. Cambium region of the bundle.—Extending across the centre of 
the bundle are several rows of small cells, the smallest of the bundle, and we 
can see that they are more regularly arranged, usually in quite regular 
rows, like bricks piled upon one another. These cells have thinner walls 
than any others of the bundle, and they usually take a deeper stain when 
treated with a solution of some of the dyes. This is because they are younger, 
and are therefore richer in protoplasmic contents. This zone of young cells 
across the bundle is the camdium. Its cells grow and divide, and thus in- 
crease the size of the bundle. By this increase in the number of the cells of 
the cambium layer, the outermost cells on either side are continually passing 
over into the phloem, on the one hand, and into the wood portion of the 
bundle, on the other hand. 

118. Longitudinal section of the bundle.—If we make thin longisections 
of the vascular bundle of the castor-oil seedling (or other dicotyledon) so 
that we have thin ones running through a bundle radially, as shown in fig. 
53, we can see the structure of these parts of the bundle in side view. We 
see here that the form of the cells is very different from what is presented in 
a cross-section of the same. The walls of the various ducts have peculiar 
markings on them. These markings are caused by the walls being thicker 
in some places than in others, and this thickening takes place so regularly in 
some instances as to form regular spiral thickenings. Others have the thick- 
enings in the form of the rounds of a ladder, while still others have pitted 
walls or the thickenings are in the form of rings. 

119. Vessels or ducts. —One way in which the cells in side view differ 
greatly from an end view, in a cross-section in the bundle, is that they are 
much longer in the direction of the axis of the stem. The cells have become 
elongated greatly. It we search for the place where two of these large cells 
with spiral, or ladder-like, markings meet end to end, we shall see that the 
wall which formerly separated the cells has nearly or quite disappeared. In 
other words the two cells have now an open communication at the ends. 
This is so for long distances in the stem, so that long columns of these large 


66 BOTANY, 


cells form tubes or vessels through which the water rises in the stems of 
plants. 

120. Bast fibres,—In the bast portion of the bundle we detect the cells of 
the bast fibres by their thick walls, They are very much elongated and the 


Fig. 53. 
Longitudinal section of vascular bundle of sunflower stem; spiral, scalariform and pitted 
vessels at left; next are wood fibers with oblique cross walls; in middle are cambium cells 
with straight cross walls, next two sieve tubes, then phloem or bast cells, 


ends taper out to thin points so that they overlap, In this way they serve to 
strengthen the stem. 

121. Sieve tubes.—Lying near the bast cells, usually toward the cambium, 
are elongated cells standing end to end, with delicate markings on their cross- 
walls which appear like finely punctured plates or sieves. The protoplasm 
in such cells is usually quite distinct, and sometimes contracted away from 
the side walls, but attached to the cross-walls, and this aids in the detection. 
of the sieve tubes (fig. 53). The granular appearance which these plates 
present is caused by minute perforations through the wall so that there 
is a communication between the cells. The tubes thus formed are there- 
fore called sieve tubes, and they extend for long distances through the 
bundle so that there is communication throughout the entire length of the 
stem. (The function of the sieve tubes is supposed to be that for the down- 
ward transportation of substances elaborated in the leaves.) 

122. Bundle in the sunflower stem.—In like manner a section of the stem 
of the sunflower shows similar bundles, but the number is greater than eight. 
In the garden balsam the number is from four to six in an ordinary stem 
3-4mm diameter. Here we can see quite well the origin of the vascular 
bundle. Between the larger bundles cspecially in free-hand sections of stems 


PART OF MOVEMENT OF LIQUIDS IN PLANTS. 67 


trough which a colored solution has been lifted by transpiration, we can 
*e small groups of the minute cells in the cambial ring which are col- 
red. These groups of cells which form strands running through the stem are 
rocambium strands. The cells divide and increase just like the cambium 
alls, and the older ones thrown off on either side change, those toward the 
2ntre of the stem to wood vessels and fibres, and those on the outer side to 
ast cells and sieve tubes. 

123. Fibrovascular bundles in the Indian corn.—In fig. 54 is repre- 
mted a fibrovascular bundle of the stem of the Indian corn. The large 
lls are those of the spiral and reticulated 
ad annular vessels. This is the woody 
ortion of the bundle, or xylem. Oppo- 
te this is the bast portion or phloem, 
arked by the lighter culored tissue at 2. 
he larger of these cells are the sieve 
bes, and intermingled with them are 
naller cells with thin walls. Surround- 
g the entire bundle are small cells with 
ick walls. These are elongated and the 
pering ends overlap. They are thus 
ender and long and form fibres. In 
ch a bundle all of the cambium has 
-ssed over into permanent tissue and the 
indle is said to be closed. 

124. Rise of water in the vessels.—  Transection of fibrovascular bundle of 
uring the movement of the water or Indian corn. a, toward periphery of 


: : stem ; g, large pitted vessels ; s, spiral 
ttrient solutions upward in the stem the vessel; 7, annular vessel; /, air cavity 


ssels of the wood portion of the bundle se eg be ee hen 
certain plants are nearly or quite filled, thim-walled parenchyma, (Sachs.) 
root pressure is active and transpiration is not very rapid. If, however, on 
y days transpiration is in excess of root pressure, as often happens, the 
ssels are not filled with the water, but are partly filled with certain gases 
cause the air or other gases in the plant become rarefied as a result of the 
cessive loss of water. There are then successive rows of air or gas bub- 
2s in the vessels separated by films of water which also line the walls of 
2 vessels. The condition of the vessel is much like that of a glass tube 
rough which one might pass the ‘‘froth’’ which is formed on the surface 
soapy water. This forms a chain of bubbles in the vessels. This chain 
s been called Jamin’s chain because of the discoverer. 

125. Rise of water in the bundles is not wel understood.— Why water or 
id solutions can be raised by the plant to the height attained by some trees 
s never been satisfactorily explained. There are several theories pro- 


68 BOTANY. 


pounded which cannot be discussed here. It is probably a very complex 

process. Root pressure and transpiration both playa part, or at least can be 

shown, as we have seen, to be capable of lifting water to a considerable height. 
126. Synopsis of tissues. 

Epidermis. 


Many-celled hairs. 
Branched hairs, often stellate. 
Clustered, tufted hairs. 
Glandular hairs. 
Root hairs. 
Guard cells of stomates. 
Spiral vessels. 
Pitted vessels. 
Scalariform vessels. 
Annular vessels. 
Fibrovascular Wood fibres. 
system. Wood parenchyma. 
Cambium (fascicular). 
f Sieve tubes. 
Phloem. { Bast fibres. 
[ Bast parenchyma. 


| Simple hairs. 


Trichomes 


Epidermal : 
(hairs). 


system. 


Xylem. 


Cork. 
Parenchyma. 
Ground tissue. 
Interfascicular cambium. 
Medullary rays. 
ay Sten Bundle sheath. 
Sclerenchyma (thick-walled cells, in nuts, etc.). Collen- 
chyma (thick-angled cells, under epidermis of succulent 
stems). 


Fundamental 


e 


Demonstration 22.* 


127. Ifit is desired that the pupils examine under the microscope the dif- 
ferent elements of the epidermal and fundamental system, the teacher can 
make or procure sections to illustrate them. The pupils can then study and 
make sketches to illustrate the structures. 

Material.—Leaves of stored celery, the older ones with rather tough 
petioles, and considerable leaf surface; or caladium leaves with long petiole 


* This demonstration may well be omitted. 


PART OF MOVEMENT OF LIQUIDS IN PLANTS. 69 


rom the conservatory; old dead corn-stalks. Shoots of the garden balsam 
impatiens) are good. 

A solution of fuchsin (add a few crystals to water), or use red ink, 

For study of the vascular bundles, sections may be made of the stems or 
ietioles of the same plants, or of fresh corn stalks, of the stem of the sun- 
lower, or castor-oil bean. The teacher can make these sections either free 
and, or with a microtome; or if preferred, permanent slides to illustrate 
he structure of the vascular bundles may be obtained. 

If the pupils are to make their own sections for study, sharp razors will 
so be required. 

Microscope, etc., for demonstration 21. 


CHAPTER XII. 
HOW PLANTS GET THEIR CARBON FOOD. 


I. Tue Gasrs CoNcCERNED. 


Exercise 26. 


128. Gas given off by green plants in the sunlight.—Take some green 
alga, like spirogyra or vaucheria, which is in a fresh condition, place one 
lot in a beaker or tall glass vessel of water and 
set this in the direct sunlight or in a well lighted 
place. At the same time cover a similar vessel 
of spirogyra with black cloth so that it will be 
in the dark, or at least in very weak light. 

129. The gas is shown in the form of bub- 
bles.—In a short time we that in the first 
vessel small bubbles of gas are accumulating on 
the surface of the threads of the spirogyra, and 
now and then some free themselves and rise to 
the surface of the water. Where there is quite 
a tangle of the threads the gas is apt to become 
caught and held back in larger bubbles, which 
on agitation of the vessel are freed. 

Examine the vessel which was covered to 
exclude the light, or which was placed in the 
dark. Are bubbles of gas given off here? 


Fig. 55. 
Oxygen gas given off by Place the vessel in the light and note how soon 


spirogyra, 


bubbles begin to pass off. 


Exercise 27. 


130. Experiment with elodea.— Take one of the higher green plants, an 
aquatic plant like elodea, callitriche, etc. Place the plant in the water with 
the cut end of the stem uppermost, but still immersed, the plant being weighed 
down by a glass rod or other suitable object. If we place the vessel of water 


7O 


HOW PLANTS GET THEIR CARBON FOOD. 71 


containing these leafy stems in the bright sunlight, in a short time bubbles 
of gas will pass off quite rapidly from the cut end of the stem. 

In the stem from which the leaves have been cut are there as many bub- 
bles? What is the reason? What part of the leafy shoot gives rise to the 
greater part of the gas? 


Demonstration 238. 


181. To determine the kind of gas given off by green plants in the sun- 
light.—Take quite a quantity of the plants of elodea and place them under 
an inverted funnel which is immersed in water: the gas will be given off in 
quite large quantities and will rise into the narrow exit of the funnel. The 
funnel should be one with a short 
tube, or the vessel one which is 
quite deep so that a small test 
tube which is filled with water 
may inthis condition be inverted 
over the opening of the funnel 
tube. Place in the bright sun- 
light for several days. 

With this arrangement of the 
experiment the gas will rise in 
the inverted test tube, slowly 
displace a portion of the water, Fig. 56. Fig, 57. 
and become collected in a suff- Bubbles of oxygen gas — Apparatus for col- 

: ‘a given off from elodea in lecting quantity of 
cient quantity to afford us a presence of sunlight. (Oels) oxygen from elodea. 
test. When a considerable (Detmer.) 
quantity has accumulated in the test tube, we may close the end of the tube in 
the water with the thumb, lift it from the water and invert. The gas will rise 
against the thumb. A dry soft pine splinter should be then lighted, and after 
it has burned a short time, extinguish the flame by blowing upon it, when 
the still burning end of the splinter should be brought into the mouth of the 
tube as the thumb is quickly moved to one side. The glowing of the splinter 
shows ihat the gas is oxygen. 

182. Oxygen given off by green land plants also.—If we should extend 
our experiments to land plants we should find that oxygen is given off by 
them under these conditions of light. Land plants, however, will not do this 
when they are immersed in water, but it is necessary to set up rather com- 
plicated apparatus and to make analyses of the gases at the beginning and 
at the close of the experiments. This has been done, however, in a suffi- 
ciently large number of cases so that we know that all green plants in the 
sunlight, if temperature and other conditions are favorable, give off oxygen. 


72 BOTANY. 


133. Absorption of carbon dioxide.— We have next to 
inquire where the oxygen comes from which is given off by 
green plants when exposed to the sunlight, and also to learn 
something more of the conditions necessary for the process. 
We know that water which has been for some time exposed to 
the air and soil, and has been agitated, like running water of 
streams, or the water of springs, has mixed with it a consider- 
able quantity of oxygen and carbon dioxide. 


Demonstration 24. 


134. To show the result in boiled water.—Boil spring water or hydrant 
water which comes from a stream containing oxygen and carbon dioxide, for 
about 20 minutes, to drive off these gases. Set this aside where it will not 
be agitated, until it has cooled sufficiently to receive plants without injury. 
Now place some spirogyra or vaucheria, and elodea, or other green water 
plant, in this boiled water and set the vessel in the bright sunlight under the 
same conditions which were employed in the experiments for the evolution of 
oxygen. No oxygen is given off. 


Note.—It can be demonstrated that carbon dioxide is absorbed by the 
plant while the oxygen is passing off. In the case of aquatic plants the 
carbon dioxide is mixed with the water, while in the case of the land plants 
the carbon dioxide comes from the air. In the study of respiration we shall 
find that carbon dioxide is formed within the plant. Some of the carbon 
dioxide then which plants use when they are giving off oxygen comes from 
within the plant itself. For some simple experiments to demonstrate the 
absorption of carbon dioxide during this process see paragraphs 119-124 of 
the author’s larger ‘‘Elementary Botany.” 


135, A chemical change of the gas takes place within the 
plant cell.—Since oxygen is given off while carbon dioxide, a 
different gas, is necessary, it would seem that a chemical change 
takes place in the gases within the plant. Since the process 
takes place in such simple plants as spirogyra as well as in the 
more bulky and higher plants, it appears that the changes go on 


within the cell, in fact within the protoplasm. We should 
remember also that this chemical’change of the gases in plants 


can only take place in the presence of light. 


HOW PLANTS GET THEIR CARBON FOOD. 73 


Synopsis.—At temperatures suitable for growth, green plants in the sun- 
ght are constantly giving off a gas. 

In the case of water plants this gas can be seen in the form of bubbles. 

This gas is oxygen. 

At the same time that oxygen is being given off by green plants carbon 
ioxide (carbon and oxygen) is being absorbed by the plant. 

A chemical change in the carbon dioxide takes place in the plant and 
ome of the oxygen is thus liberated. 

Material.—Fresh mats of some alga, either spirogyra, zygnema, or vau- 
heria. 

Fresh shoots of one of the higher water plants like elodea (found in the 
hallow water of ponds, lakes, or streams near low ground). 

Beakers with fresh spring or hydrant water to hold the plants. A funnel 
nd large test tube for demonstration 23. The demonstration should be 
varted several days in advance. 


CHAPTER XIII. 


HOW PLANTS GET THEIR CARBON FOOD. 


CONCLUDED. 


II. SrarcH FORMED BY GREEN PLantTs. 


Exercise 28. 


136. To test for the presence of starch in green leaves.—Take green 
leaves which have been for several hours in the bright sunlight. -Boil them 
in alcohol, using great care not to set the alcohol on fire. This removes the 
chlorophyll. If it is desired not to use the alcohol, boil the leaves in water 
for a short time. Then place them in alcohol, changing the alcohol occa- 
sionally. The green color is extracted slowly by this process, It may be 
extracted more rapidly if the preparation is placed in the sunlight. When 
the leaves are decolorized, place them in a solution of iodine in potassium 
iodide. In place of this solution, a tincture of iodine purchased at drug. 
stores answers fairly well. Observe the color of the leaves. This color is 
due to the presence of starch, the starch becoming dark blue or nearly 
black when treated with iodine. 


137. Starch is formed only in the green parts of variegated 
leaves.—If we test for starch in variegated leaves like the leaf 
of a coleus plant, we shall have an interesting demonstration of 
the fact that the green parts of plants only form starch. We 
may take a leaf which is partly green and partly white, from a 
plant which has been standing for some time in bright light. 
Fig. 58 is from a photograph of such a leaf. We should first 
boil it in alcohol to remove the green color. Now immerse it 
in the potassium iodide of iodine solution for a short time. 
The parts which were formerly green are now dark blue or 
nearly black, showing the presence of starch in those portions 

74 


, 


HOW PLANTS GET THEIR CARBON FOOD, 75 


of the leaf, while the white part of the leaf is still uncolored. 
This is well shown in fig. 59, which is from a photograph of 
another coleus leaf treated with the iodine solution. 

138. Green parts of plants form starch when exposed to 
light.—Thus we find that in the case of all the green plants we 


Fig. 58. Fig. 59. 
Leaf of coleus showing green and white Similar leaf treated with iodine, the starch re- 
areas, before treatment with iodine. action only showing where the leaf was green. 


have examined, starch is present in the green cells of those 
which have been standing for some time in the sunlight where 
the process of the absorption of CO, and the giving off of oxygen 
can go on, and that in the case of plants grown in the dark, 
or in leaves of plants which have stood for some time in the 
dark, starch is absent. We reason from this that starch is the 
product of the chemical change which takes place in the green 
cells under these conditions. Because CO, is absorbed during 
this process, and because uf the chemical changes which take 
place in the formation of starch, by means of which the carbon 


76 BOTANY. 


is changed from its attraction in the molecule of carbon dioxide 
to its attraction in the molecule of starch, the process has 
been termed carbon assimilation. But since it is not truly an 
assimilatory process, and because sunlight is necessary in the 
first step of the conversion, it has also been recently termed 
photosyntax or photosynthesis. These terms, however, seem in- 
appropriate, since the sy#/hefic part of the process is not known 
to be due to the action of light. In the presence of chlorophyll 
light reduces the carbon dioxide, while the synthetic part of the 
process may not be influenced by light. For popular treatment 
the term carbon conversion was proposed in the author’s larger 
‘‘ Elementary Botany.’’ But this is also an unfortunate term, 
and he would now propose the simple term, starch formation. 
But there should be no objection to the use of the term carbon 
assimilation, or photosynthesis. 

139. Fungi cannot form starch.—If we should extend our 
experiments to the fungi, which lack the green color so charac- 
teristic of the majority of plants, we should find that starch 
formation does not take place even though the plants are 
exposed to direct sunlight. These plants then obtain carbo- 
hydrates for food from other sources, as parasites from living 
plants, and as saprophytes from dead plants, or from certain 
plant products. 


III. CHLoropHyLt AnD CHLOROPHYLL BopIEs. 


140. Form of the chlorophyll bodies.—This green substance 
of plants, the presence of which is necessary in the formation 
of starch, is chlorophyll. It usually occurs in definite bodies, 
the chlorophyll bodies. Chlorophyll bodies vary in form in 
some different plants, especially in some of the lower plants, 
This we have already seen in the case of spirogyra, where the 
chlorophyll body is in the form of a very irregular band, which 
courses around the inner side of the cell wall in a spiral manner. 
In zygnema, which is related to spirogyra, the chlorophyll 
bodies are star-shaped. In the desmids the form varies greatly. 


HOW PLANTS GET THEIR CARBON FOOD. 77 


In vaucheria, a branched thread-like alga, the chlorophyll bodies 
are oval in outline. This form of the chlorophyll body is that 
which is common to many of the green algz, and also occurs 
in the mosses, liverworts, ferns, and the higher plants. It isa 
more or less rounded, oval, flattened body. 


Demonstration 25. 


141. Chlorophyll bodies in leaves.—If it is desired to demonstrate the 
chlorophyll bodies the teacher can make free-hand sections from fresh leaves 
of a begonia, or from some other plant. In figure 60 are shown the chloro- 
phyll bodies in the leaf of the ivy. 


Fig. 60. 


Section of ivy leaf, palisade cells above, loose parenchyma, with large intercellular spaces 
in centre. Epidermal cells on either edge, with no chlorophyll bodies. 


142. Chlorophyll.—The chlorophyll is a coloring substance 
which resides in the chlorophyll body. It can be extracted from 
the body by the use of alcohol. The body is a plastid of a 
proteid nature, widely distributed in many plants. The plastid 
when not exposed to light is usually colorless, when exposed to 
light it often becomes green; while in the roots of the carrot 
and in the petals of some flowers it possesses other colors. 
When it is colorless it is called a /eucoplas/, when green a 
chloroplast, and when yellow, red, etc., a chromoplast. 

143. Where starch is first formed.—The starch is first 
formed in the chlorophyll bodies. The chlorophyll absorbs 


78 BOTANY. 


certain of the rays of light. The absorbed light is transformed 
into energy which assists in the chemical changes taking place 
in the carbonic acid (when the carbon dioxide of the air meets 
the water in the cell it forms carbonic acid) in the cell by which 
starch is built up. By mounting leaves of some mosses, or the 
prothallia of ferns in water, for microscopic examination, the 
starch grains can be seen within the chlorophyll bodies. They 
can often be seen in the chlorophyll bodies in the leaf of 
begonias when thin sections are made for observation under the 
microscope. 

144. Starch in other parts of plants than the leaves.— 
While the larger part of the starch is formed in the green leaves, 
it is often found stored in large quantities in parts of plants not 
exposed to the light. It is formed in the leaves during the day, 
and at night it is dissolved and transported to other parts of the 
plant where it may be needed for the manufacture of other 
substances used in plant growth, or it may be stored in special 
receptacles in the form of starch grains again, as in the potato 
tuber, the roots of the sweet potato, or in the thick leaves of 
the onion, etc. 


Exercise 29. 


145. To test for the presence of starch in parts of the plant where it 
is stored.—Cut a potato tuber, scrape some of the potato at the cut surface 
into a pulp. Apply a small quantity of a solution of iodine to this pulp. 
Describe the result. The color produced is the reaction for what substance ? 
Where was the starch first formed in the potato plant? How is it that later 
it is found in the tubers which are underground stems? What function for 
the potato plant does this stored starch serve ? 

If it is desired the pupils may test for starch in the enlarged roots of the 
sweet potato, the grains of corn, or in the leaves of the onion. 

Place a small quantity of corn starch (as much as will be lifted on the 
point of a small knife blade) in a test tube. Add water to the depth of two 
inches and warm over a flame, then cool by moving the end in cold water or 
by holding it under the water tap. Add to the starch water a drop or two 
of a tincture of iodine (iodine crystals dissolved in alcohol). Observe the 
blue color. Now heat over the flame; the color disappears because the 
warm water extracts the iodine from the starch grains. Now cool again. 
The blue color reappears since the starch again takes up the iodine. 


HOW PLANTS GET THEIR CARBON 00D. 79 


Demonstration 26. 


146. Form of starch grains.—Where starch is stored as a reserve mate- 
rial it occurs in grains which usually have certain characters peculiar to the 
species of plant in which they are found. They vary in size in many dif. 
ferent plants, and to some extent in form also. Scrape some of the cut sur- 
face of the potato tuber into a pulp and mounta small quantity in water, or 
make a thin section for microscopic examination. We find large starch grains 
of a beautiful structure. The grainsare oval in form and more or less irregular 
in outline, But the striking peculiarity is the presence of what seem to be 
alternating dark and light lines in the starch grain. The lines form irregu- 
lar rings, which are smaller and smaller until we come to the small central 
spot termed the ‘‘hilum”’ of the starch grain. It is supposed that these ap- 
parent lines in the starch grain are caused by the starch substance being 
deposited in alternating dense and dilute layers, the dilute layers containing 
more water than the dense ones; others think that the successive layers 
from the hilum outward are regularly of diminishing density, and that this 
gives the appearance of alternating lines. 


147. Necessity of carbon food for plants. — The starch 
formed by plants is one of the organic substances manufactured 
by plants. It is the basis for the formation of other organic sub- 
stances. Starch contains carbon, hydrogen, and oxygen, in the 
proportion of 6 molecules of carbon, 10 molecules of hydrogen, 
and 5 molecules of oxygen (C,H,,O,). The water in the starch 
is in the proportion of 2 molecules of hydrogen to 1 molecule 
of oxygen (H,O). For this reason it is called a carbohydrate. 
The most important carbohydrates in plants are starch, the 
sugars, and cellulose, the latter substance, or modifications of 
it, forming the cell walls of plants. Without carbon-food 
green plants cannot make any appreciable increase in plant 
substance, though a considerable increase in size of the plant 
may take place (see paragraph 194). Chlorophylless plants, like 
the fungi and certain parasitic or saprophytic (as the Indian- 
pipe, certain of the orchids, etc.) angiosperms, derive their 
carbon-food from the carbohydrates manufactured by the green 
plants. Animals also derive their carbohydrates through the 
medium of the green plants, either directly or indirectly. 

Nore.—For further experiments and discussion of this subject see the 
author’s larger ‘‘ Elementary Botany.” 


80 BOTANY. 


Synopsis. 

[ Carbon dioxide is absorbed by the green parts of 
plants. 

In the presence of chlorophyll in the cell, and under 
the influence of sunlight, 4 chemical change takes 
place in the carbonic acid (carbon dioxide united 
with the water in the plant-cell). 

As a result of this chemical change starch is formed 
by the union of carbon, hydrogen, and oxygen ; 
but all of the oxygen brought in by the carbon 
dioxide is not needed in the manufacture of starch. 
This portion of the oxygen is set free. 


Starch formation, by | 
green plants. 


Fungi, or other plants which lack chlorophyll cannot form starch. 

Parts of leaves, or parts of plants, which lack chlorophyll cannot form 
starch. 

Chlorophyll is the green pigment in the chlorophyll bodies (chloroplasts). 

Starch is first formed in the chlorophyll bodies, and then dissolved and 
carried to other parts of the plant, for food, or to be stored. 

Material.—Fresh leaves of ordinary plants which have been for a few 
hours in daylight (some of the seedlings which have been grown, or plants 
from the greenhouse will answer); some variegated leaves of the coleus 
plant if possible. 

For study of chlorophyll, leaves of begonia to section are good. For 
study of starch, potato tubers ; and if other objects are wanted, sweet pota- 
toes, onions, etc. 

If the pupils make their own sections of the begonia leaves, sharp razors 
will be necessary. 

Chemicals needed in the test for starch: a solution of iodine in potassium 
iodide (see appendix for formula), or an ordinary tincture of iodine ob- 
tained at drugstores ; alcohol. 

Microscope, etc., if it is desired to demonstrate the structure of starch 
grain. 


CHAPTER XIV. 
ROUGH ANALYSIS OF PLANT SUBSTANCE. 


148. Some simple experiments to indicate the nature of 
plant substance.—After these building-up processes of the plant, 
it is instructive to perform some simple experiments which indi- 
cate roughly the nature of the plant substance, and serve to 

‘ show how it can be separated into other substances, some of them 
being reduced to the form in which they existed when the plant 
took them asfood. For exact experiments and results it would 
be necessary to make chemical analyses. 


Exercise 30. 


149. The water in the plant.—Take fresh leaves or leafy shoots or other 
fresh plant parts. Weigh. Permit them to remain in a dry room until they 
are what we call ‘‘dry.’’ Now weigh. The plants have lost weight, and 
from what we have learned in studies of transpiration this loss in weight we 
know to result from the loss of water from the plant. 


Exercise 31. 


150. The dry plant material contains water.—Take dry leaves, shavings, 
or other dry parts of plants. Place them in atest-tube. With a holder rest 
the tube in a nearly horizontal position, with the bottom of the tube in the flame 
of a bunsen burner. Very soon, before the plant parts begin to ‘ burn,” 
note that moisture is accumulating on the inner surface of the test-tube. 
This is water driven cff which could not escape by drying in air, without the 
addition of artificial heat, and is called ‘‘ hygroscopic water.” 

151. Water formed on burning the dry plant material.—Light a soft-pine 
or bass-wood splinter. Hold a thistle tube in one hand with the bulb down- 
ward and above the flame of the splinter. Carbon will be deposited over the 
inner surface of the bulb. After a time hold the tube toward the window 
and look through it above the carbon. Drops of water have accumulated on 

81 


82 BOTANY. 


on the inside of the tube. This water is formed by the rearrangement of 
some of the hydrogen and oxygen, which is set free by the burning of the 
plant material, where they were combined with carbon, as in the cellulose, 
and with other elements. 


Exercise 32. 


152. Formation of charcoal by burning.—Take dried leaves, and shav- 
ings from some soft wood. Place in a porcelain crucible, and cover about 
3cm deep with dry fine earth. Place the crucible in the flame of a Bunsen 
burner and let it remain for about 15 minutes. Remove and empty the con- 
tents. Ifthe flame was hot the plant material will be reduced to a good 
quality of charcoal. The charcoal consists largely of carbon. 

158. The ash of the plant.—Place in the porcelain crucible dried leaves 
and shavings as before. Do not cover with earth. Place the crucible in the 
flame of the Bunsen burner, and for a moment place on the porcelain cover ; 
then remove the cover, and note the moisture on the under surface from the 
escaping water. Permit the plant material to burn; it may even flame for 
atime. In the course of 15 minutes it is reduced to a whitish powder, 
much smaller in bulk than the charcoal in the former experiment. This is 
the ash of the plant. 

What has become of the carbon? In this experiment the air was not ex- 
cluded from the plant material, so that oxygen combined with the carbon as 
the water was freed, and formed carbon dioxide, passing off into the air in 
this form. This it will be remembered is the form in which the plant took 
the carbon-food in through the leaves. Here the carbon dioxide met the 
water coming from the soil, and the two united to form, ultimately, starch, 
cellulose, and other compounds of carbon ; while with the addition of nitro- 
gen, sulphur, etc., coming also from the soil, still other plant substances 
were formed. 

Nore.—The ash of the plant contains, usually, potash, soda, lime, mag- 
nesium, ferric oxide, phosphoric acid, sulphuric acid, silica, chlorine. (See 
page 64 of the author’s larger ‘‘ Elementary Botany,” 2d Ed., revised.) 


Synopsis. 

The living plant contains a large amount of water. 

When the plant is dried in the air it still contains a considerable amount 
of water. 

This water of air-dried plants can only be driven off by artificial heat (at 
a temperature of 100° F. for some time). 

When all of the water is dried out of the plant, if the plant is burned so 
that the plant substance is disorganized, several different substances 
are formed. 


ROUGH ANALYSIS OF PLANT SUBSTANCE. 83 


1. Water is formed by the uniting of hydrogen and oxygen as these 
elements are freed from the plant substance by the burning. 

2. Certain gases, one of them is carbon dioxide, formed by the carbon 
from the disorganized plant substance uniting with oxygen of 
the air during the burning. 

If the dried plant material is burned while oxygen from the air is ex- 
cluded, the carbon cannot unite with oxygen to form carbon dioxide, 
but remains in the form of charcoal, which is almost pure carbon. 

When plant material is burned with access of oxygen the residuum is a 
whitish-gray powder called the ash. (See page 64 of the author’s 
larger ‘‘ Elementary Botany,’’ 2d Ed., revised.) 

Material.—Leafy shoots fresh; air-dried leaves, and some soft dry wood 

vhite pine wood, bass wood, or some similar soft wood). 

Apparatus.—Bunsen burner to supply gas-flame ; small porcelain cruci- 

es with covers; supports to hold crucibles in the flame; test tubes; thistle 

bes; some dry earth. 


CHAPTER XV. 


SOME OTHER WAYS IN WHICH CERTAIN PLANTS 
OBTAIN FOOD. 


(This chapter is for reading, or the teacher may make demon- 
strations before the class if there is time.) 

154. Nutrition of moulds.—Start some growths of the black 
mould as described in paragraph 49. Then for several days 
observe the growth. First there appear small spots of delicate 
white threads. This tuft of threads increases in size, the threads 
elongate and branch. Finally upright threads appear which 
bear the black heads (sporangia, sing. sporangium) and spores 
again. Break the potatoes open through several of these tufts. 
The threads of the mould enter the potato also. The mycelium 
in the potato or in the bread absorbs food solutions from these 
substances in the same way that root hairs absorb food solu- 
tions. The potato and the bread are largely made up of starch 
from green plants. This demonstration serves excellently to 
show how the fungi which lack chlorophyll obtain their carbo- 
hydrate food from the products of green plants (see paragraph 
147). 

155. Nutrition of the larger fungii—tlf we select some one 
of the larger fungi, the majority of which belong to the mush- 
room family and its relatives, which is growing on a decaying 
log or in the soil, we shall see on tearing open the log, or on 
removing the bark or part of the soil, as the case may be, that 
the stem of the plant, if it have one, is connected with whitish 
strands. During the spring, summer, or autumn months, 
examples of the mushrooms connected with these strands may 
usually be found readily in the fields or woods, but during the 

84 


HOW PLANTS OBTAIN FOOD. 85 


winter and colder parts of the year often they may be seen in 
forcing houses, especially those cellars devoted to the. propaga- 
tion of the mushroom of commerce. 

156. The fungus strands.—These strands are made up of 
numerous threads of the mycelium which are closely twisted 
and interwoven into a cord or strand, which is called a myce- 
lium strand, or rhizomorph. These are well shown in fig. 61, 
which is from a photograph of the mycelium strands, or 
““spawn’’ as the grower of mushrooms calls it, of Agaricus 
campestris. The little knobs or enlargements on the strands 
are the young fruit bodies, or ‘‘ buttons.’’ 

157. Mats of mycelium are sometimes very extensive.— 
While these threads or strands of the mycelium in the decaying 
wood or in the decaying organic matter of the soil are not true 
roots, they function as roots, or root hairs, in the absorption of 
food materials. In old cellars and on damp soil in moist 
places we sometimes see fine examples of this vegetative 
part of the fungi, the mycelium. But most magnificent 
examples are to be seen in abandoned mines where timber has 
been taken down into the tunnels far below the surface of the 
ground to support the rock roof above the mining operations. 
I have visited some of the coal mines at Wilkesbarre, Pa., and 
here on the wood props and doors, several hundred feet below 
the surface, and in blackest darkness, in an atmosphere almost 
completely saturated at all times, the mycelium of some of the 
wood-destroying fungi grows in a profusion and magnificence 
which is almost beyond belief. 

158. Form of the mushroom.—A good example for this 
study is the common mushroom (Agaricus campestris). 

This occurs from July to November in lawns and grassy fields. 
The plant is somewhat umbrella-shaped, as shown in fig. 62, 
and possesses a cylindrical stem attached to the under side of 
the convex cap or pileus. On the under side of the pileus are 
thin radiating plates, shaped somewhat like a knife blade. 
These are the gills, or lamella, and toward the stem they are 


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HOW PLANTS OBTAIN FOOD. 87 


rounded on the lower angle and are not attached to the stem. 
The longer ones extend from near the stem to the margin of 
the pileus, and the V-shaped spaces between them are occupied 
by successively shorter ones. Around the stem a little below 
the gills is a collar, termed the ring or annulus. 


Fig. 62. , 
Agaricus campestris. View of under side showing stem, annulus, gills, and margin of pileus, 


159. Nutrition of parasitic fungi.—Certain of the fungi 
grow on or within the higher plants and derive their food 
materials from them and at their expense. Such,a fungus is 
called a parasite, and there are a large number of these plants, 
which are known as jarasitic’ fungt. The plant at whose 
expense they grow, is called the ‘‘ hosz.’’ 

One of these parasitic fungi, which it is quite easy to obtain 
in greenhouses or conservatories during the autumn and winter, 
is the carnation rust (Uromyces caryophyllinus), since it breaks 
out in rusty dark brown patches on the leaves and stems of the 
carnation (see fig. 63). If we make thin cross-sections through 
one of these spots on a leaf, and place them for a few minutes 
in a solution of chloral hydrate, portions of the tissues of the 


leaf will be dissolved. After a few minutes we wash the sec- 
tions in water on a glass 
slip, and stain them with a 
solution of eosin. If the 
sections were carefully 
made, and thin, the threads 
of the mycelium will be 
seen coursing between the 
cells of the leaf as slender 
threads. Here and there 
will be seen short branches 
of these threads which 
penetrate the cell wall of 
the host and project into 
the interior of the cell in 
the form of an irregular 
knob. Such a branch is a 
haustorium. By means of 
this haustorium, which is 
here only a short branch 
of the mycelium, nutritive 
substances are taken by the 

fungus from the proto- 

Carnation rust Page flower stem, plasm OF cell-sap of the 

From photograph. carnation. From here it 
passes to the threads of the mycelium. These in turn supply 
food material for the development of the dark brown gonidia, 
which we see form the dark-looking powder on the spots. 
Many other fungi form haustoria, which take up nutrient 
matters in the way described for the carnation rust. 

160. Nutrition of the dodder.—The dodder (cuscuta) is an 
example of one of the higher plants that is parasitic. The stem 
twines around the stems of other plants, sending short conical 
processes termed haustoria in their tissues. By means of these 
the nutriment is absorbed from the host. The means of absorb- 


HOW PLANTS OBTAIN FOOD. 89 


ing nutriment may be demonstrated by making sections through 
both parasite and host at a point where the haustoria enter the 
stem. These should then be mounted for examination with 
the microscope. 


Fig. 64. 
Several teleutospores, showing the variations in form. 


161. Carnivorous plants, or insectivorous plants.—Examples 
of these are the well-known Venus fly-trap (Dionzea muscipula) 
and the sundew (Drosera rotundifolia). These are illustrated 
in figures 67 and 68. The lamina of the leaf of the Venus 


Fig. 65. 
Cells from the stem of arusted carnation, showing the intercellular mycelium and haus- 
toria. Object magnified thirty times more than the scale. 


fly-trap resembles a steel trap, as shown open in figure 67. 
When an insect alights on the leaf and touches one of the hairs 
(there are three prominent hairs on the upper surface of each 


90 BOTANY. 


half of the leaf), the leaf suddenly closes and captures it. It 
has been found that when the hair is touched the first time no 
movement of the leaf takes place, but when it is touched the 
second time the leaves close up suddenly. There are small 
glands on the surface of the leaf which excrete a substance that 
digests the insect, when the digested portions are absorbed by 
the leaf and are assimilated by the plant as food. The leaf of 
the sundew is quite different in form and action. In the species 


Fig. 66. 
Dodder, 


illustrated here the lamina of the leaf is rotund, and the upper 
surface is covered with numerous long glandular hairs. The 


gland is on the end of the hair, and a sticky substance is 


HOW PLANTS OBTAIN FOOD. fo} 4 


excreted by the cells of the gland, which glistening in the sun- 
light reminds one of drops of dew. For this reason the plant 
is called the sundew. When an insect alights on a leaf the 
viscid substance clings to it and holds it firmly so that it 
cannot escape. The glandular hairs then begin slowly to curve 
inward toward the centre of the leaf as shown in figure 68. 
Finally the margins of the leaf become inrolled also, so that 
the insect is held fast and close to the upper surface of the 
leaf. . Excretions from the leaf surface act as a digestive 
ferment upon the insect. 

162. Nutrition of bacteria.— Bacteria are very minute plants, 
in the form of short rods, which are either straight or spiral, 
while some are minute 
spheres. They are widely . 
distributed; some cause dis- 
eases of plants: and animals, . 
others cause decay of organic 
matter, while still others play 
an important réle in con- 
verting certain nitrogen com- 
pounds into an available form 
for plant food. They absorb ‘ f 
their food through the sur- Fig. 67. Fig. 68. 


= Leaf of Venus fly- Leaf of Drosera ro- 

face of their body. ‘They trap (Dionza ce ee oe eee 
= * _ pula), showing winge glandular hairs fold- 

may be obtained in abund petiole and toothed ing inward asa result 


ance for study in infusions es. obaistimulus: 


of plants or of meats. 

To demonstrate bacteria in, infusions take a small quantity 
of hay or of méat. Place it in water and heat at about 60° C. 
for an hour. Then set the vessel containing the infusion aside 
in a. warm room for several days.. Numbers of bacteria will be 
developed, some of them probably motile. With a good micro- 
scope they may be demonstrdted by mounting a drop of the 
infusion on a glass slip and preparing for examination with the 
microscope. 


Nitrogen gatherers. 


163. How clovers, peas, and other legumes gather ni- 
trogen.—It has long been known that clover plants, peas, 
beans, and many other leguminous plants 
are often able to thrive in soil where the 
cereals do but poorly. Soil poor in nitro- 
genous plant food becomes richer in this 
substance where clovers, peas, ete., are 
grown, and they are often planted for the 
purpose of enriching the soil. Leguminous 
plants, especially in poor soil, are almost 
certain to have enlargements, in the form 
of nodules, or ‘‘ root tubercles.’” A root 
of the common vetch with some of these 
root tubercles is shown in fig. 69. 


Fig. 69. i : 
Root of the common vetch, 1638a. A fungal or bacterial organism 


showing root tubercles, 


in these root tubercles.—If we cut one 
of these root tubercles open, and mount a small portion of the 
interior in water for examination with the microscope, we shall 
find small rod-shaped bodies, some of which resemble bacteria, 
while others are more or less forked into forms like the letter 
Y, as shown in fig. 70. These bodies are rich in nitrogenous 
substances, or proteids. They are portions of a minute organ- 
ism, of a fungous or bacterial nature, which attacks the roots 
of leguminous plants and causes these nodular outgrowths. 
The organism (Phytomyxa leguminosarum) exists in the soil 
and is widely distributed where legumes grow. 

164. How the organism gets into the roots of the legumes. 
—This minute organism in the soil makes its way through the 
wall of a root hair near the end. It then grows down the 
interior of the root hair in the form of a thread. When it 
reaches the cell walls it makes’a minute perforation, through 
which it grows to enter the adjacent cell, when it enlarges 
again. In this way it passes from the root hair to the cells of 


HOW PLANTS OBTAIN FOOD. 93 


the root and down to near the centre of the root. As soon as 
it begins to enter the cells of the root it stimulates the cells of 
that portion to greater activity. So the root here develops a 
large lateral nodule, or ‘‘root tubercle.’’ As this ‘‘ root 


Fig. 70. Fig. 71. 
Root-tubercle organism from vetch, old con- Root-tubercle organism from Medicag 
dition, : denticulata, 


? 


tubercle ’’ increases in size, the fungus threads branch in all 
directions, entering many cells. The threads are very irregular 
in form, and from certain enlargements it appears that the rod- 
like bodies are formed, or the thread later breaks into myriads 
of these small ‘‘ bacteroids. ’’ 

165. The root organism assimilates free nitrogen for its 
host.—This organism assimilates the free nitrogen from the air 
in the soil, to make the proteid substance which is found stored 
in the bacteroids in large quantities. Some of the bacteroids, 
rich in proteids, are dissolved, and the proteid substance is 
made use of by,the clover or pea, as the case may be. This is 
why such plants can thrive in soil with a poor nitrogen content. 
Later in the season some of the root tubercles dié and decay. 
In this way some of the proteid substance is set free in the soil. 
The soil thus becomes richer in nitrogenous plant food. 

The forms of the bacteroids vary. In some of the clovers 
they are oval, in vetch they are rod-like or forked, and other 
forms occur in some of the other genera. 


CHAPTER XVI. 


RESPIRATION. 


Exercise 33. 


166. Simple experiment to demonstrate the evolution of CO. during 
germination.— Where there are a number of students and a number of large 
cylinders are not at hand, take bottles of a pint capacity, place in the bottom 
some peas soaked for 12 to 24 hours. Cover with a glass plate which has 
been smeared with vaseline to make a tight joint with 
the mouth of the bottle. Set aside in,a moderately 
warm place for 24 hours. Then slide the glass plate 
a little to one side and quickly pour in a little baryta 
water so that it will run down on the inside of the 
bottle. Cover the bottle again. Note the precipitate 
of barium carbonate which demonstrates the presence 
of CO, in the bottle. Lower a lighted taper. It is 
extinguished because of the great quantity of CO,. 


Exercise 34. 


167. Comparison of respiration in plants and ani- 
mals.—Take some of the baryta water and breathe 
upon it. The same film isformed. The carbon diox. Fig. 72. 
ide which we exhale is absorbed by the baryta water Test for presence of 
and forms barium carbonate, just as in the case of the oe ea pons 
peas. In the case of animals the process by which ‘Sachs.) 
oxygen is taken into the body and carbon dioxide is given off is respiration. 
The process in plants which we are now studying is the same, and also is 
respiration. The oxygen in the vessel was partly used up in the process and 
carbon dioxide was given off. (It will be seen that this process is exactly the 
opposite of that which takes place in starch formation.) 


Exercise 35 (or Demonstration). 


168. Respiration is necessary for growth.—After we have performed the 
experiment in paragraph 166, if the vessel has not been open too long so 


94 


RESPIRATION. i 95 


that oxygen has entered, we may use the vessel for another experiment, 
»y set up a new one to be used in the course of 12 to 24 hours, after the oxy- 
yen has been consumed. Place some folded damp filter paper on the ger- 
ninating peas in the jar. Upon this place one-half dozen peas which have 
ust been germinated, and in which the roots are about 20-25mm long. See 
igures 73, 74. The vessel should be covered tightly again and set aside in a 


Fig. 73. Fig. 74. Fig. 744. Fig. 734. 


Fig. 73.—Seedlings in vessels containing an excess of carbon dioxide, and very little 
xygen. No growth takes place. 


Fig. 74.—Vessel with normal air used as a check. No excess of carbon dioxide, usual 
amount of oxygen. Normal growth takes place. 


Figures 73@ and 74a represent the condition of the peas in the experiment shown in figs. 
3 and 74,a month later. The cylinders as set up for that experiment were left fora 
nonth and then photographed. The peas in the cylinder containing normal air have 
own, producing stems which reach to the top of the cylinder, while in fig. 73a, where 
he oxygen was absent, the peas have died. At this time a test was made with a lighted 
aper; it burned brightly in the cylinder 74a, but was quickly extinguished in the cylinder 
3a. The peas having died in this jar, decomposition had taken place and other gases than 
arbon dioxide were present, but there was not sufficient oxygen to support combustion, 


varm room. A second jar with water in the bottom instead of the gcrminat- 
ng peas should be set up as a check. Damp folded filter paper should be 
upported above the water, and on this should be placed one-half dozen peas 
vith roots of the same length as those in the jar containing carbon dioxide. 


96 BOTANY. 


169. Oxygen is necessary for growth.—In 24 hours examine and note 
how much growth has taken place. It will be seen that the roots have elon- 
gated but very little or none in the first jar, while in the second one we see 
that the roots have elongated considérably, if the experiment has been carried 
on carefully, Therefore in an atmosphere devoid of oxygen or an excess of 
carbon dioxide, very little growth will take place, which shows that normal 
respiration with access of oxygen is necessary for growth. 


170. Energy set free during respiration.—From what we 
have learned of the exchange of gases during respiration we 
infer that the plant loses carbon during 
this process. If the process of respira- 
tion is of any benefit to the plant, there 
must be some gain in some direction 
to compensate the plant for the loss of 
carbon which takes place. 

It can be shown by an experiment 
Fig. 75. * that during respiration there is a slight 


P. dlings; th Ei o- 
at the tote bad Go Sayeed elevation of the temperature in the 


and little growth took + * 
place; the one atthe Heht plant tissues. The plant then gains 


ee a acai some heat during respiration. We 

have also seen in the attempt to grow 
seedlings in the absence of oxygen that very little growth takes 
place. But when oxygen is admitted growth takes place 
rapidly. The process of respiration, then, also sets free energy 
which is manifested in one direction, by growth. 


Demonstration 27. 


171. To set up the apparatus for demonstrating respiration.—Soak a 
double handful of peas for 12 to 24 hours in an abundance of cool water. 
Prepare a small quantity of baryta water, a saturated solution, and filter some 
into a short wide vial. Take a glass cylinder about 35cm high by 5¢ in 
diameter. Select a perforated rubber cork to fit very tightly when crowded 
part way in the open end of the cylinder. Prepare a long S manometer by 
bending a glass tube which is about one and one-half meters long by 67m 
inside diameter, into the form shown in figure 76. Put mercury into one 
end of the manometer as shown in the figure, and if it is desired to show the 


RESPIRA TION. 97 


experiment at a distance in the classroom, place a small quantity of a solu- 
tion of eosin -bove each column of mercury. Insert the other end of the 


manometer through the preforation in 
the rubber cork, It must fit very tightly. 
If there is another perforation plug it 
with a glass rod. Take a wide-mouthed 
small glass jar—a small glycerine jelly 
jar is good—which will go inside the 
cylinder. Break a few sticks of caustic 
potash and drop in it. Nearly fill with 
water and tie a string around the top 
so that it can be lowered into the upper 
part of the cylinder without spilling any 
of the potash solution. Prepare a sup- 
port for this by inserting a glass rod 
about 13cm long into a cork. Have all 
the parts of the apparatus and the ma- 
terial ready, and the baryta water in 
the open vial, so that the apparatus 
may be set up quickly. Have the cylin- 
der warm and set the apparatus up in a 
room where the temperature is about 
20° C. (about 68° Fahr.). Place a small 
quantity of damp paper (not wet) in the 
bottom of the cylinder. Place in the 
soaked peas to fill about 8c to 10cm. 
Upon these place the small vial of baryta 
water. Drop in the support and press 
the glass rod down far enough so that 
the jar of potash solution will enter and 
pass far enough below the mouth of the 
cylinder to be out of the way of the 
rubber cork. 

Insert the rubber cork containing the 
S manometer of mercury, placing be- 
tween it and the side of the cylinder a 
stout needle to allow the escape of air 
while the cork is pressed in tightly. 
This allows the mercury to remain at 


the same level in both arms of the tube, h 


Now remove the needle and set the 


ates 


Fig. 76. Fig. 77. 

Experiment to demonstrate respiraton. 

Fig. 76.—At beginning of experiment ; 
mercury in each arm equal No oxygen has 
been consumed in vessel. 

Fig. 77.—At close of experiment; mer- 
cury in inner arm has risen, Some oxygen 
as been consumed, 


apparatus aside where the temperature will remain at about 20° C., and let 


98 BOTANY. 


stand for about 24 hours. The apparatus should be set up quickly so that 
forming carbon dioxide will not displace the air. 
172. Carbon dioxide given off during germination while 
oxygen from the air is con- 
sumed.—In a short while 
there can be seen a whitish 
film on the baryta water in 
the vial. In less than an hour 
this film may become so thick 
that with a little agitation it 
breaks and settles as a white 
precipitate. This white pre- 
cipitate is barium carbonate. 
Some of the carbon dioxide 
given off by the peas is ab- 
sorbed by the baryta water 
forming the insoluble barium 
carbonate. Carbon dioxide is 
also absorbed by the caustic 
potash solution in the bottom 
of the cylinder. Owing to 
the slowness with which the 
carbon dioxide diffuses from 
between the peas into the 
potash solution an excess may 
be formed. This excess of 
carbon dioxide in the cylinder 
produces a pressure which is 
shown by the rise of the mer- 


cury in the outer arm of the 
Fig. 78. Fig. 79. tube. * 
Experiment to demonstrate respiration, 7 


Fig. 78.At beginning of experiment; mer- In about 24 hours observe 
cury in each arm equal, Nooxygen has been ¥ 
consumed in vessel. the experiment. If the mer- 
Fig. 79.—At close of experiment; mercury : . : : 
in inner arm has risen, Some oxygen has been CUTY 15 still higher in the outer 


consumed: arm it shows that there is still 


* When this inside pressure is produced it shows that more CO, is 


RESPIRA TION. oC 


a 


an excess of CO, in the cylinder. At any rate lift the cylinder 
with the hands in such a way as to hold firmly at the same time 
the glass tube. Lift it up and down in such a way as to spill a 
portion of the baryta water over against the wall of the cylinder, 
and to dash the potash solution into a spray. Be careful not 
to toss the mercury out of either arm of the tube. ~ If the open 
arm of the glass tube is closed with the finger (should the 
apparatus be set up as indicated in fig. 78), the cylinder may 
be inclined so as to let a portion of the potash solution run, 
among the peas to come directly in contact with the. fees 
remaining there. Now rest the cylinder on the table and 
observe the result. The mercury now, if it did not before, 
stands higher in the inner arm of the S tube, showing that some 
constituent of the air within the cylinder was consumed during 
‘he formation of the CO,. This constituent of the air must be 
oxygen, since the carbon can only come from the plant. Where 
che baryta water was spilled over an abundance of the white 
orecipitate of the barium carbonate is formed. 

If desired the experiment can be set up as shown in figure 
78, with the potash solution in the bottom of the cylinder, and 
che peas supported on a circular piece of wire netting held in 
slace between two small corks inserted ina glassrod. At the 
close of the experiment when the cylinder is being agitated the 
sscaping baryta water forms a’ large quantity of the whitish 
recipitate as it washes down the side of the cylinder. 


veing set free than oxygen is being consumed. This feature of the ex- 
xeriment demonstrates what is known as intramolecular respiration, a kind 
of respiration which can go on independently of the entrance of the onyEen 
3ee the author’s larger ‘‘ Elementary Botany ” page 58. 


100 BOTANY. 


Demonstration 28. 


178 Respiration in a leafy plant.— We may take a potted plant which 
has a well-developed leaf surface and place it under a tightly fitting bell jar. 
Under the bell jar there also should be placed 
small vessel containing baryta water. A similar 
apparatus should be set up, but with no plant, to 
serve as a check. The experiment must be set up 
in a room which is not frequented by persons, or 
the carbon dioxide in the room from respiration will 
vitiate the experiment. The bell jar containing the 
plant should be covered with a black cloth to prevent 
starch formation. In the course of ten or twelve 
hours, if everything has worked. properly, the baryta 


Fig. 80. 
Test for liberation of 
carbon dioxide from leafy water under the jar with the plant’ will shew the film 
lant during respiration. ‘ hs f 
aryta water in smaller of barium carbonate, while the other one will show 


wanials. (oachay) none. Respiration, therefore, takes place in a leafy 


plant as well as in germinating seeds. 

Synopsis.—Respiration (taking in oxygen and giving off carbon dioxide) 
occurs in all plants during growth. 

Respiration takes place actively in germinating seeds and opening buds 
and flowers. 

Respiration without access of oxygen (intramolecular respiration) takes 
place, in germinating seeds for example, in addition to normal respiration. 

Respiration in plants is the same process as in animals. 

The carbon dioxide from respiration may be detected by testing the air in 
the vessel where the plant is growing with a lighted taper (the taper is ex- 
tinguished), or by baryta water (the baryta water absorbs carbon dioxide, 
forming the insoluble barium carbonate), or by lime water (the lime water 
absorbs carbon dioxide, forming the insoluble calcium carbonate = chalk). 

Access of oxygen is necessary for the growth of most plants. (Some bac- 
teria will only grow in the absence of oxygen.) 

Respiration is a breaking-down process. (Changes take place in the pro- 
toplasm, the entering oxygen uniting with some of the carbon and oxygen of 
the protoplasm and forming CO,.) Compare this with the burning of plant 
substance. 

Respiration transforms energy in the plant, which is manifested by an 
elevation of the temperature of the plant substance, so that the plant gains 
some heat ; it is also manifested by growth. 


RESPIRATION. 101 


Comparison of respiration and starch formation. 


Carbon dioxide is taken in by the plant and oxygen 
is liberated. 

Starch is formed as a result of the metabolism, or 
chemical change. 

The process takes place only in green plants, and in 


Starch formation or the green parts of plants, that is, in the presence 
Photosynthesis. of the chlorophyll. (Exception in purple bacte- 
rium.) 
The process only takes place under the influence of 
sunlight. 


It is a building-up process, because new plant sub- 
stance is formed. : 


Oxygen is taken in by the plant and carbon dioxide 
is liberated. 

Carbon dioxide is formed as a result of the meta- 
bolism, or chemical change. 

The process takes place in all plants whether they 


Respiration. 4 possess chlorophyll or not (exceptions in anaerobic 
bacteria). 
The process takes place in the dark as well as in 
a the sunlight. 


It is a breaking-down process, because combustion 
of plant substance occurs. 


Material and apparatus.—Peas soaked for 24 hours in cold water (enough 
for class and for demonstration). 

Peas germinated, and with roots about 20mm long. <A few should be 
started 4 or 5 days in advance of the time they are wanted. 

Wide-mouthed bottles, or cylinders, with glass plates and vaseline, to 
close them, or corks (glass plates are better). 

Tapers, or soft wood splinters for flaming. 

Baryta water (saturated solution of barium hydrate in water) in tightly 
stoppered bottle. 

Watch glasses for baryta water. 

For demonstration 27: glass cylinder about 35cm high by §cwz in diameter ; 
perforated rubbor cork to fit very tightly ; S manometer made from glass 
tubing about 6m diameter; mercury ; small glass jar and vial; support 
as indicated in demonstration 27; some sticks of caustic potash ; baryta 
water ; a stout needle. : 

For demonstration 28: potted plant; bell jar to cover; baryta water. 


CHAPTER XVII. 
GROWTH. 


174, Meaning of growth.—By growth is usually meant an 
increase in the bulk of the plant accompanied generally by an 
increase in plant substance. Among the lower plants growth 
is easily studied in some of the fungi. 

175. Growth of roots —For the study of the growth of roots 
we may take any one of many different plants. The seedlings 
of such plants as peas, beans, corn, squash, pumpkin, etc., 
serve excellently for this purpose. 


Exercise 36. 


176. To study growth of roots.—The seeds, a handful or so, are soaked 
in water for about 12 hours, and then placed between layers of paper or 
between the folds of cloth, which must be kept quite moist but not very wet, 
and should be kept in a warm place. (See demonstration 2.) 

The primary or first root (radicle) of the embryo pushes its way out 
between the seed coats at the small end. When the seeds are well germi- 
nated, select several which have the root 4-5¢m long. With a crow-quill 
pen we may now mark the terminal portion of the root off into very short 
sections as in fig. 81. The first mark should be not more than Im from 
the tip, and the others not more than Im apart. Now place the seedlings 
down on damp filter paper, and cover with a bell jar so that they will re- 
main moist, and if the season is cold place them in a warm room. At 
intervals of 8 or 10 hours, if convenient, observe them and note the further 
growth of the root. Sketch the root with the marks at the beginning of the 
experiment, and at the different times the observations are taken. Where 
does the elongation take place? Determine this by the marks on the root 
which separate. Where is the region of greatest elongation? Does the 
region of greatest elongatian change ? 

102 


GROWTH. 103 


177, The region of elongation—While the root has elon- 
gated, the region of elongation zs of af the Hip of the root. Tt 
ties a little distance back from the tip, beginning at about 2mm 
from the tip and extending over an area 
represented by from 4 to 5 of the millimeter 
marks. The root shown in fig. 66 was 
marked at 10 a.m. on 
July 5. At 6p.m. of 
a=, the same day, 8 hours 
later, growth had taken 
place as shown in the 


Ecir,, 


Fig. 81. 


Root of germinating pumpkin, showing region of 
elongation just back of the tip. 


middle figure. At g a.m. on the following day, 15 hours later, the 
growth is represented in the lower one. Similar experiments 
upon a number of seedlings gives the same result: the region of 
elongation in the growth of the root is situated a little distance 
back from the tip. Further back very little or no elongation 
takes place, but growth in diameter continues for some time, 
as we should discover if we examined the roots of growing 
pumpkins, or other plants, at different periods. 

178. Movement of region of greatest elongation.—In the 
region of elongation the areas marked off do not all elongate 
equally at the same time. The middle spaces elongate most 
rapidly and the spaces marked off by the 6, 7, and 8 mm marks 
elongate slowly, those farthest from the tip more slowly than 
the others, since elongation has nearly ceased here. The spaces 
marked off between the 2-4mm marks also elongate slowly, but 
soon begin to elongate more rapidly, since that region is becom- 
ing the region of greatest elongation. Thus the region of 
greatest elongation moves forward as the root grows, and 
remains approximately at the same distance behind the tip. 


104 BOTANY. 


Exercise 37. 


179. Growth of the stem.—We may use a bean seedling growing in the 
soil. At the junction of the leaves with the stem there are enlargements. 
These are the odes, and the spaces on the stem between successive nodes 
are the zzternodes. We should mark off several of these internodes, espe- 
cially the younger ones, into sections about 57 long. Now observe these 
at several times for two or three days, or more. The region of elongation 
is greater than in the case of the roots, and extends back further from the 
end of the stem. In some young garden bean plants the region of elonga- 
tion extended over an area of 40m in one internode. 


180. Force exerted by growth.—One of the marvellous 
things connected with the growth of plants is the force which 
is exerted by various members of the plant under certain condi- 
tions. Observations on seedlings as they are pushing their way 
through the soil to the air often show us that considerable force 
is required to lift the hard soil and turn it to one side. A very 
striking illustration may be had 
in the case of mushrooms which 


sometimes make their way through 
the hard and packed soil of walks 
or roads. ‘That succulent and 
tender plants should be capable 
of lifting such comparatively 
heavy weights seems incredible 
until we have witnessed it. Very 
striking illustrations of the force 
of roots are seen in the case of 
trees which grow in 
rocky situations, where 
rocks of considerable 
Fig. 82. weight are lifted, or 


Lever auxanometer (Oels) for measuring elongation of small rifts in large rocks 
the stem during growth, 


are widened by the 
lateral pressure exerted by the growth of a root, which entered 
when it was small and wedged its way in. 


GROWTH. 105 


If the season of the year is one that will permit, make some 
observations on the force exerted by seedlings in coming through 
the hard earth; of mushrooms coming up through dry and 
hard earth; of the wedging of roots in the crevices of rocks. 
Or recali and note any observations of this, kind made in the 
past. One has only to note the immense size and weight of 
some trees to understand the force which must have been ex- 
pended during their growth in lifting up the food materials for 
these massive objects. 

181. Energy of growth.—This is manifested in the compara- 
tive size of the members of a given plant. To take the sun- 
flower for example, the lower and first leaves are comparatively 
small. As the plant grows larger the leaves are larger, and this 
increase in size of the leaves increases up to a maximum period, 
when the size decreases until we reach the small leaves at the 
top of the stem. The zone of maximum growth of the leaves 
corresponds with the maximum size of the leaves on the stem. 
The rapidity and energy of growth of the stem is also correlated 
with that of the leaves, and the zone of maximum growth is 
coincident with that of the leaves. It would be instructive to 
note it in the case of other plants, 


Exercise 38. 


182. To study zone of maximum growth.—Study the zone of maximum 
growth in several plants which may be at hand. Some plants may be ob- 
‘ained for use from conservatories. Other plants may be collected during the 
zrowing season and preserved for this purpose. Corn plants, for example, 
van be gathered at maturity in the early autumn or late summer. They 
nay be carefully pressed entire, and mounted on large sheets, or on paste- 
joard. The zones of maximum growth of the stem as well as of the leaves 
ran be studied from these preserved plants. The plants in this condition 
will serve this purpose for several years. 


For other experiments and studies on growth see the author’s 
arger ‘‘ Elementary Botany.’’ 


106 


Synopsis. 


Growth. 


4 


BOTANY. 


( An increase in the bulk or size of the plant. 


(Parts of the plant become longer and stouter.) 

Growth in length of the root takes place most actively a few 
millimeters back from the tip. 

The region of elongation of the root changes as the root be- 
comes longer. 

Growth in length is the result of the elongation of the newly 
formed cells [the formative region (z.e., where new cells are 
formed) is in the root tip]. 

The stem grows in a similar way, but the region of elongation 
extends over a greater area than in the root. 

As a result of the increase in the size of plants by growth, 
great force is exerted, sufficient to move considerable amounts 
of hard earth ; or, in the case of trees, to even split rocks, 
or to lift up during growth the entire plant material in 
trunk and branches. 

The energy of growth during the season, or during the life of 
an annual, varies. It is low at first, as manifested by the 
small size of the members, then it increases to a maximum, 
then decreases. 


Material and apparatus.—Seedlings of squash, or pumpkin, or peas, etc., 
grown in a germinator free from earth. The seeds should be started a 
week to ten days before they are wanted, so that the roots will be about 
3cm to 4em long. (See demonstration 2 for preparing seedlings.) Sev- 
eral moist chambers; large corks upon which some of the seedlings can be 


pinned. 


India ink and crow-quill pen for marking the roots. 
Seedlings grown in soil in pots with the stems just appearing above 


the soil. 


Potted begonias; entire corn plants (may be pressed and preserved dry); 
or small but mature sunflower plants (also may be preserved dry). 


CHAPTER XVIII. 
MOVEMENT IN PLANTS DUE TO IRRITABILITY. 


183. Movement in response to stimulus.—Beside the growth 
movements which take place in plant parts, the parts of plants 
show certain movements which are due to irritability. In this 
kind of movement the plant is influenced by some exciting cause, 
called a stimulus. The stimulus acts upon the irritable part of 
the plant, and in response to this movement occurs. We can 
easily study the effect of several different kinds of stimuli. 

184. Influence of the earth on the direction of growth.—In 
the germination of the seeds which we have used in some of the . 
earlier experiments it has probably been observed that the direc- 
tion which the root and stem take upon germination is not due 
to the position in which the seed happens to lie. Under normal 
conditions we have seen that the root grows downward and the 
stem upward. 


Exercise 39. 


185. To study the influence of the earth on roots.—Take seedlings grown 
in a germinator which are free from the soil. Pin several seedlings to a cork 
in such a way that the stems and roots of different ones will be lying in 
different directions. Mark off the tip of the root of several with ink, as in 
paragraph 176, Cut off the extreme tip from a few of the roots. Place the 
cork in a moist chamber, with an abundance of water or saturated ‘paper in 
the bottom. On the following day observe the positions of the roots and 
stems. Sketch and annotate. In the case of the roots marked into millimeter 
spaces determine the motor zone (region of curvature) of the root. Comparing 
these with the roots from which the tip was cut determine the perceptive zone 
(the zone which receives the stimulus). Now turn the cork in another posi- 
tion, leave for a day and note the result. 

107 


108 BOTANY. 


Exercise 40. 


186. Influence of the earth on stems and leaves.—Place rapidly growing 
potted plants horizontally. Seedlings in pots, or young plants, or potted 
hyacinths are good ones to use. In the course of a day observe the positions 
of the stems and leaves. Sketch some of them. 

187. Gravity acts as a stimulus.—Knight found that the 
stimulus which influences the root to turn downward is the force 
of gravity. The reaction of the root in response to this stimulus 
is geofropism, a turning influenced by the earth. This term is 
applied to the growth movements of plants influenced by the 
earth with regard to direction. While the motor zone lies back 
of the root tip, the latter receives the stimulus, and is the per- 
ceptive zone. If the root tip is cut off the root is no longer 
geotropic, and will not turn downward when placed in a hori- 
zontal position. Growth toward the earth is progeotropism. 
The lateral growth of secondary roots is dageotropism. 

188. The result with stems.—The stem, on the other hand, 
which was placed in a horizontal position has become again erect. 


Fig. 83. Fig. 84. : 
Germinating pea placed in a hori- In twenty-four hours gravity has caused the 
zontal position. root to turn downward. 


Figures 83, 84.—Progeotropism of the pea root. 


This turning of the stem in the upward direction takes place in the 
dark as well asin the light, as we can see if we start the experiment 
at nightfall, or place the plant in the dark. This upward growth 
of the stem is also influenced by the earth, and therefore is a case 
of geotropism. The special designation in the case of upright 
stems is negative geotropism, or apogeotropism, or the stems are 
said to be apfogeotropic. Place a rapidly growing potted plant 
in a horizontal position by laying the pot onits side. The ends 


MOVEMENT IN PLANTS DUE TO IRRITABILITY. 109 


of the shoots will soon turn upward again. Young bean plants 

fe growing in a pot began within two 
hours to turn the ends of the shoots 
upward. 


Horizontal leaves and shoots can 
be shown to be subject to the same in- 
fluence, and are therefore diageo/ropic. 

189. Influence 
of light. — Not 


Fig. 85. 
Pumpkin seedling showing apogeotropism. Seedling at the left placed hori- 
zontally, In twenty-four hours the stem has become erect. 


only is light a very important factor for plants during starch 
formation, it exerts great influence on plant growth and 
movement. 


Demonstration 29. 


190. To prepare plants grown in the dark —Three or four weeks be- 
fore these plants are wanted for study the teacher may plant a sufficient 
number of seeds (radish or other seeds) in small pots for the class to study. 
Several different kinds of seeds may be used for comparison if desired. 
Place one lot of the pots in a warm but very dark place. They may be put 
in a box, and the box can be then covered with two or three layers of black 
cloth, sufficient to shut out all light. Keep the box in a warm room, and oc- 
casionally open it to water the plants if necessary. The lot kept in the 
light should have the same temperature conditions. If preferred the pupils 
can plant the seeds, and place those to be grown in the dark in a common 
box. This is preferable if it is convenient for the pupils to do it. 


Exercise 41. 


191. Influence of light on the growth of plants.—When the plants have 
grown for about two weeks they will be ready for study. Compare the 
plants grown in the dark with those grown in the light. Which lot have 
the longer stems? What influence then does light have on growth in 


| Be) BOTANY. 


length? Which plants have the larger leaves? What influence does light 
have on the development of leaves? What is the difference in color of the 
plants? What is the cause of this? Which lot of plants have the firmer 
tissues? What is the cause of the difference in the firmness of the tissues ? 
Sketch a plant grown in the dark ; sketch one to the same scale grown in 
the light. 


Exercise 42. 


192. Influence of light on the direction of growth.—Take potted seed- 
lings and place them near a window so that they will.have a one-sided illu- 
mination. Or place: : 
them in a box which 
has a small opening 
at one side. After a 


day or two observe 
the position of the 
seedlings. Does light 
have an influence on 
the direction of 
growth? What is the 
direction with refer- 
ence to the source of 
light? Sketch one 
of the plants, and 
indicate on the ‘sheet 
the direction of the 
rays of light. Radish seedlings, grown in the 
198. Influence of dark, long, slender, not green. 
light on the position of leaves.—Take potted 
plants with a number of leaves, and place them 
near 4 window for several days or a week. Ob- 
serve the position of the leaves at the beginning Fig. 87. 
of the expenitict, and after a week’s time. What meee Senet ae pa 
is the position of the leaves with reference to the green in color. Growth re- 
source of light ? Can you tell why the leaves take ene eenen 
this position ? 


194. Retarding influence of light on growth.—We have 
only to return to the experiments performed in growing plants 
in the dark to see one of the influences which light exerts on 
plants. The plants grown in the dark were longer and more 


MOVEMENT IN PLANTS DUE TO IRRITABILITY. Ill 


slender than those grown in the light. Light then has a retard- 
ing influence on the elongation of the 
stem. 

"195. Influence of light on direction of 
growth.—wWhile we 
are growing  seed- 
lings, the pots or 
boxes. of some of 
“them should 
be placed 
_ so that the 
plants will 
> have a one- 


: . Fig. 88. a i ES 
Seedling of castor-oil bean, before and sided ily 
aftera one*sided illumination. “mination. 
This can be 


done by pledging them near an open win- 
dow, in a room with ‘a one-sided illumi- 
nation, or they may: be placed in a box 
closed on all sides but one which is facing 
the window or light. In 12-24 hours, or 
even in a much shorter time in some cases, 
the stems of the seedlings will be directed 
toward the source of light. This influence 
exerted by the rays of light is Aeotropism, a turning influenced 
by the sun or sun- 
light. 

196. Diaheliot- s 
sopism.—Horizon- 
‘al leaves and een 
shoots are diahe- 


" : Fig. 89. 
totropic as well as Dark chamber with opening at one side to show heliotropism, 
hageotropic. The (After Schleichert.) 


reneral direction which leaves assume under this influence is 
hat of placing them with the upper surface perpendicular to 


112 BOTANY. 


the rays of light which fall upon them. Leaves, then, exposed 
to the brightly lighted sky are, in general, horizontal. This 
position is taken in direct response to the stimulus of light. 


Fig. gt. 

Sunflower plant removed from 
darkness, leaves extending under 
influence of light (diaheliotro- 
pism). 


The leaves of plants with 
a one-sided illumination, 
as can be seen by trial, 
are turned with their upper surfaces 
toward the source of light, or per- 
pendicular to the incidence of the 
light rays. In this way light over- 
comes for the time being the direc- 
tion which growth gives to the leaves. 
The so-called ‘‘ sleep’’ of plants is 
of course not sleep, though the leaves 
Fig. go. __ **nod,’’ or hang downward, in many 

Sunflower plant. Epinastic i 
pense ot Jeaves induced dur- siakia There are _eny plants in 
which we can note this drooping of 
the leaves at nightfall, and in order to prove that it is not 
determined by the time of day we can resort to a well-known 
experiment to induce this condition during the day. The plant 
which has been used to illustrate this is the sunflower. Some 
of these plants, which were grown in a box, when they were 


f10VEMENT IN PLANTS DUE TO IRRITABILITY. 113 


bout 35cm high were covered for nearly two days, so that the 
ght was excluded. At midday on the second day the box was 
2moved, and the leaves on the covered plants are well repre- 
ented by fig. 90, which was made from one of them. The 
raves of the other plants in the box which were not covered 
rere horizontal, as shown by fig. 91. Now on leaving these 
ants, which had exhibited induced ‘‘sleep’’ movements, 


xposed to the light they gradually assumed the horizontal 
vosition again. 


Synopsis. 

Plants are irritable, that is, they respond to certain stimuli. 

The force of gravity stimulates the tip of the root, and 
causes the root to turn downward. 

The ‘motor zone,’’ in response to this stimulus, is co- 
incident with the region of elongation of the root. 
The perceptive zone is in the root tip. 

The force of gravity stimulates the stem to turn upwards 
(or away from the earth). 

Progeotropism (in first root). 
Geotropism. ; Diageotropism (in lateral roots). 
Apogeotropism (in stems). 

Stems( horizontal stems are diahelio- 
tropic) grow towards the light (heli- 
otropic). 

Leaves turn so as to face the light (un- 
less the light is very strong, when 
they may turn their edge toward 
the light). 

Light retards growth of stems, since 

Influence of light. stems grown in the dark are longer. 

Plants do not ‘sleep’; when the 
leaves turn downward at night it is 
because the influence of light is re- 
moved and the leaf is free to turn in 
the direction caused by growth, the 
growth being more active usually on 
the upper side of the leaf after it 

| pushes out from the bud. 


Irritability. 


114 BOTANY. 


Material and apparatus.—Seedlings, moist chambers, corks and pins, as 
in Chapter XVII. 

Seedlings in pots (beans, squash or pumpkin), rocm to 15cm high. 
Potted hyacinths if they can be obtained. 

Seedlings grown in pots in the dark (about three weeks old), others of the 
same age grown in the light. 

Some dark boxes with small opening at one side, to receive some of the 
pots of seedlings. 

If possible some sunflower plants grown in pots, plants about 20c# to 
30cm high, and tall dark boxes to cover them when desired. 

Sunflower plants should be started two or three months in advance. 
Potted oxalis, which is often grown in conservatories, is better to show in- 
duced ‘sleep ’’ movements. 


PART Il: MORPHOLOGY AND LIFE HIS- 
TORY OF REPRESENTATIVE PLANTS. 


CHAPTER XIX. 
SPIROGYRA. 


197, Convenience in studying spirogyra.—tIn our study of 
protoplasm and some of the processes of plant life we became 
acquainted with the general appearance of the plant spirogyra. 
It is now a familiar object to us. And in taking up the study 
of representative plants of the different groups, we shall find 
that in knowing some of these lower plants the difficulties of 
understanding methods of reproduction and relationship are not 
so great as they would be if we were entirely ignorant of any 
members of the lower groups. 

198. Form of spirogyra.—We have found that the plant 
spirogyra consists of simple threads, with cylindrical cells 
attached end to end. We have also noted that each cell of the 
thread is exactly alike, with the exception of certain ‘‘ hold- 
fasts’’ on some of the species. If we should examine threads 
in different stages of growth we should find that each cell is 
capable of growth and division, just as it is capable of perform- 
ing all the functions of nutrition and assimilation. The cells 
of spirogyra then multiply by division. Not simply the cells at 
the ends of the threads but any and all of the cells divide as 
they grow, and in this way the threads increase in length. 

199. Conjugation of spirogyra.—Under certain conditions, 
when vegetative growth and multiplication cease, a process of 
reproduction takes place which is of a kind. termed sexual 

: 115 


116 


reproduction. 


Fig. 92. 
Thread of spiro- 
gyra, showing long 
cells, chlorophyll 
band, nucleus, 
strands of proto- 
plasm, and _ the 
granular wall layer 

of protoplasm, 


BOTANY. 


If we select mats of spirogyra which have lost 
their deep green color, we are likely to find differ- 
ent stages of this sexual process, which in the 
case of spirogyra and related plants is called 


2 


Fig. 93. 
Zygospores of spirogyra. 


conjugation. 


Demonstration 
30. 


200. To demonstrate 
the conjugation of spiro- 
gyra.—From a tangle of 
the threads on a glass 
slip, which are conjuga- 
ting, mount a few in 
water, tease the threads 
apart, place on a cover 
glass, and prepare for 
observation under the 
microscope. Let the 
pupils sketch  conju- 
gating cells, and make 
notes upon the different 
stages of the passage of 
the protoplasm, and on 
the other characters of 
the fruiting threads, as 
outlined below. 


201. Conjugation. 
—If the material is 
in the right condition 
we will see in certain 
of the cells an oval 
or elliptical body. 
If we note carefully 
the cells in which 


these oval bodies are situated, there will be seen a 
tube at one side which connects with an empty cell 
of a thread which lies near as shown in fig. 93. If 


SPIROG YRA. 117 


we search through the material we may see other threads con- 
nected in this ladder fashion, in which the contents of the cells 
are in various stages of collapse from what we have seen in the 
growing cell. In some the protoplasm and chlorophyll band 
have moved but little from the wall; in others they form a mass 
near the centre of the cell, and again in others we will see that 
the content of the cell of one of the threads has moved partly 
through the tube into the cell of the thread with which it is 
connected. 

This suggests to us that the oval bodies found in the cells 
of one thread of the ladder, while the cells of the other thread 
were empty, are formed by the union of the contents of the 
two cells. In fact that is what does take place. This kind 
of union of the contents of two similar or nearly similar cells is 
conjugation. ‘The oval bodies which are the result of this con- 
jugation are gygofes, or zygospores. When we are examining 
living material of spirogyra in this stage it is possible to watch 
this process of conjugation. Fig. 94 represents the different 
stages of conjugation of spirogyra. 

202. How the threads conjugate, or join.—The cells of two 
threads lying parallel put out short processes. The tubes from 
two opposite cells meet and join. The walls separating the 
contents of the two tubes dissolve so that there is an open 
communication between the two cells. Each one of these cells 
corresponds to a sexual organ. This process of conjugation is 
a sexual process. ‘The process here is a very simple one be- 
cause any cell of the thread without any particular change in 
size or form may become a sexual organ. The cell which loses 
its protoplasm is the supplying cell, while the one in which the 
zygospore is formed is the receiving cell. Before the movement 
of the protoplasm begins we cannot tell which is to be the sup- 
plying cell or the receiving cell. 

The passage of the protoplasm from one cell to another can 
only be seen under the most favorable conditions, and then with 
living material. It is possible, howevei, in preserved material 


118 BOVANY. 


to find cells which have the protoplasm in some of these different 
stages. When the zygospores are being studied one should 
look for some cells in these stages. 


Fig. 94. 
Conjugation in spirogyra; from left to right beginning in the upper row is shown the 
gradual passage of the protoplasm from the supplying cell to the receiving cell. 


203. The zygospore.—This zygospore now acquires a thick wall which 
eventually becomes brown in color. The chlorophyll color fades out, and a 
large part of the protoplasm passes into an oily substance which makes it 
more resistant to conditions which would be fatal to the vegetative threads. 
The zygospores are capable therefore of enduring extremes of cold and dry- 
ness which would destroy the threads. They pass through a ‘resting’ 
period, in which the water in the pond may be frozen, or dried, and with the 
oncoming of favorable conditions for growth in the spring or in the autumn 
they germinate and produce the green thread again. 

For further reading on spirogyra and its relatives see the 


author’s larger ‘‘ Elementary Botany,’’ Chapter XV. 


Synopsis. 


Spirogyra. 4 


L 


SPIROGYRA. ) @ fe) 


Vegetative stage; single unbranched threads, composed of 
cylindrical cells end to end. 
Cells all alike. 
Grows by division and elongation of all the cells. 
Sexual stage ; conjugation of like cells. 
Receiving and supplying cells, not differentiated. 
Result of conjugation, a zygospore. 
The zygospore after a period of rest produces the spirogyra 
thread again. 


Material.—Spirogyra in conjugation, showing different stages, as well as 
the zygospores. The material may be collected fresh, or it may be preserved 
in 2% formalin collected in advance or purchased from supply companies. 

Microscope, etc. 


CHAPTER XxX. 


THE GREEN FELT: VAUCHERIA. 


204, Description of vaucheria.—The plant vaucheria usually 
occurs in dense mats floating on the water or lying on the damp 
soil. The texture and feeling of one of these mats reminds one 
of ‘‘ felt,’’ and the species are sometimes called the ‘‘ green felts, ’’ 


The threads are quite 
branched. Upon exami- 
croscope we find that the 
uous, that is, there are 
spirogyra dividing the 
cells. The chlorophyll is 
scattered over the inside 
tube. These are the char- 
tive threads. A portion of 
is shown in fig. 95. Cross- 
only where reproductive 
formed, which cut them 


coarse and = are 
nation with the mi- 
threads are contin- 
no cross-walls as in 
thread up into short 
in small oval bodies 
of the wall of the 
acters of the vegeta- 
a vegetative thread 
walls are formed 
cells or organs are 
off from the re- 


Fig. 95. 
Portion of branched thread of vaucheria. 


mainder of the vegetative thread. This plant multiplies in 

several ways which would be too tedious to detail here. The 

sexual reproduction,* however, should be studied if possible, 

* Oedogonium may be studied in place of vaucheria if preferred and if 

material is more easily obtained. Vaucheria is usually more abundant and 
T20 


THE GREEN FELT: VAUCHERIA. 121 


since the organs of reproduction can be readily seen, usually 
much easier to study than in any of the plants belonging to the 
higher groups. If fresh material is not at hand, that which has 
been preserved in alcohol or formalin will serve very well. 
Often excellent material is to be found in greenhouses growing 
on the soil of pots during the winter, especially if one obtains 
from outside in the autumn some bulbs of ariseema (jack-in-the- 
pulpit) with soil near them for potting. Fresh material of 
vaucheria in fruit is found easily during the autumn or spring. 
At this time a quantity should be preserved. The sexual 
organs are usually more abundant when the threads appear 
somewhat yellowish or yellow green. 


Exercise 43. 


205. Gross characters of vaucheria.—If fresh material is at hand which 
was growing in water, note how firmly the threads are tangled together ; 
compare with spirogyra in this respect. Can you make out in this condition 
that the threads are branched? This branched condition of vaucheria is 
one of the reasons for the dense tangle of threads. Note the coarse feeling ; 
compare with spirogyra in this respect. 

If material on the soil is at hand, note that it is not necessary that all 
species grow in water. Note here also the dense tangle of threads. Lift up 
a tuft with the needle ; compare the effect on the threads with that of spiro- 
gyra when a tuft of the latter is lifted in the same way. Compare the 
‘feeling’ of the threads with that of spirogyra. 


Demonstration 31. 


206. Sexual reproduction in vaucheria.—Mount a few threads of fruiting 
vaucheria in water for microscopic study. If prepared slides are at hand 
they will answer for the demonstration. Let each pupil make a sketch of 
the sexual organs, and make notes of the form of the same ; also note the con- 
tinuity of the threads, cross-walls: only being formed in connection with the 
reproductive organs. Let them compare the different stages found in the 
formation of the ripe egg. 


both kinds of the sexual organs are more easily found and understood, those 
of oedogonium being more complicated. See Chapters XVI and XVII of 
the author’s larger ‘‘ Elementary Botany.” 


122 BOTANY. 


207. Vaucheria sessilis; the sessile vaucheria.—In this 
plant the sexual organs are sessile, that is they are not borne 
on.a stalk asin some other 
species. The sexual organs 
usually occur several in a 
group. Fig. 96 represents 
a portion of a fruiting 
plant. 

208. Sexual organs of 
vaucheria. Antheridium. 
—The antheridia arejshort, 

Fig. 96. slender, curved branches 

Young antheridium and oogonium of Vaucheria a 

sessilis, before separation from contents of thread by from a main thread. A 
ee septum is formed which 
separates an end portion from the stalk. This end cell is the 
antheridium, Frequently it is collapsed or empty as shown in 
fig. 97. The protoplasm in the antheridium forms numerous 
small oval bodies each with two slender lashes, the cilia. When 
these are formed the antheridium opens at the end and they 


Fig. 97. 
Vaucheria sessilis, one antheridium between two oogonia. 


escape. It is after the escape of these spermatozoids that the 
antheridium is collapsed. Each spermatozoid is a male gamete. 

209. Oogonium.—The oogonia are short branches also, but 
they become large and somewhat oval. The septum which 
separates the protoplasm from that of the main thread is as we 
see near the junction of the branch with the main thread. The 


THE GREEN FELT: VAUCHERTA. 123 


oogonium, as shown in the figure, is usually turned somewhat to 
one side. When mature the pointed end opens and a bit of the 
protoplasm escapes. The 
remaining protoplasm 
forms the large rounded 
egg cell which fills the wall 
of the oogonium. In 
some of the oogonia which 
we examine this egg is sur- 
rounded by a thick brown 


Fig. 98. 
Vaucheria sessilis; oogonium opening and emit- 


wall, with Ol ting a bit of protoplasm ; spermatozoids ; sperma- 
: starchy and ily tozoids entering oogonium. (After Pringsheim and 


contents. Thisis the fer- Goebel.) 


tilized egg (sometimes called here the oospore). It is freed 
from the oogonium by the disintegration of the latter, sinks 
into the mud and remains here until the following autumn 
or spring, when it grows directly into a new plant. The 
spermatozoids are very difficult to see and one should not expect 
to study them here. Fertilization is brought about by the 
spermatozoids swimming in at the open end of the oogonium, 
when one of them makes its way down into the egg and fuses 
with the nucleus of the latter. 

210. Vaucheria compared with spirogyra.—In vaucheria 
we have a plant which is very interesting to compare with 
spirogyra in several respects. In spirogyra growth takes place 
in all cells, that is in all parts of the thread, while in vaucheria 
growth is confined to the ends of the threads and the ends of 
the branches. This is a distinct advance on spirogyra. Again 
in spirogyra any part of the thread (any cell) may become one 
of the sexual organs. In vaucheria the sexual organs are 
special branches, which are short, and further, the two organs 


are different in size so that they can readily be distinguished 
long before the time for fertilization. Then in vaucheria the 


supplying cell does not give all its content to the receiving cell, 
but only a bit of the protoplasm in the form of a minute body, 
the spermatozoid. 1 


124 BOTANY. 
Synopsis. 
( Vegetative stage ; branched threads, continuous, growth con- 
fined to the ends of the threads and ends of the branches. 
Sexual stage ; fertilization of an egg by a minute sperm nu- 
cleus. 
‘i Antheridium (male organ). Contains num- 
Vauchems. 4 Setual ongans bers of small spermatozoids. 


diftcrentiated, Oogonium (female organ). Contains one egg. 


Result of fertilization is the formation of a fertilized egg 
(oospore), which after a period of rest grows into the vau- 


cheria plant again. 


Material.—Freshly collected material of one of the species of vaucheria 
which is in fruit. It can be obtained from the water of ponds or ditches, or 
it is very often found growing on soil of pots in greenhouses. If preferred 
it may be collected in advance and be preserved in 2% formalin, or it may 
be purchased of supply companies. 

Microscope, etc. 


CHAPTER XXI. 
FUNGI: THE BLACK MOULD. 


Demonstration 32. 


211. To grow the mould.—This plant may be grown by placing old bread, 
or partly decaying fruits, as bananas, or the peelings of lemons or oranges 
in a moist chamber. Set this in a warm place for about one week. Then 
the plant may be grown on potatoes as described in paragraph 49, or one 
may take the material for study directly from the bread. It should be 
studied before it becomes very old. 


Exercise 44. 


212. Mycelium.—Before the black heads of the fungus appear, note the 
delicate fluffy white tufts of threads which appear on the surface of the bread 
or other substance on which the fungus is growing. These threads are the 
mycelium, anda single thread is a mycelium thread, or ‘“‘ hypha.” 

Search on the margins of old cultures where the threads come in contact 
with paper (some sheets of paper should be placed by the sides of the cul- 
tures) or the sides of the vessels for ‘‘ runners,” long threads of mycelium 
which touch the place of support here and there. Are there tufts of upright 
threads at the points of contact which bear black heads? Try to find the 
connection of the black threads with the creeping mycelium. 

If the mycelium has not been studied in a previous chapter the teacher 
can mount some here for demonstration. Let the pupils note the branched, 
colorless threads, and that there are no cross-walls. Note the granular 
protoplasm. 

At the microscope let each pupil note the long dark-colored stalks which 
bear the rounded ‘‘heads”’ ; the latter are the sporangia. If the spores are 
mature the sporangium wall is perhaps broken and the spores more or less 
scattered. Ifso, note the remnant of the wall as a small collar below the 
enlarged end of the stalk. The enlarged end of the stalk is the ‘‘colu- 
mella.” In the younger stages of the sporangium, note the columella 
arched up within the sporangium. ‘Trace the stalks down to their attach- 

125 


126 BOTANY. 


ment with the mycelium. Is there only one at this point of attachment, or 
are there several? Are there any rhizoids present at the point of attach- 
ment? Sketch the different stages. 


213. Description of the mucor fruit.—We shall probably 
note at once that the stalks or upright threads which support 
the heads are stouter than the threads of the mycelium. 

These upright threads soon have formed near the end a cross- 


Fig. 99. 
Portion of banana with a mould (Rhizopus nigricans) growing on one end. 


wall which separates the protoplasm in the end from the 
remainder. This end cell now enlarges into a vesicle of con- 
siderable size, the head as it appears, but to which is applied 
the name of sforangium (sometimes called gonidangium, 
because it encloses the gonidia). 

At the same time that this end cell is enlarging the cross:wall 
is arching up into the interior. This forms the columella. All 
the protoplasm in the sporangium now divides into gonidia. 


FUNGI; THE BLACK MOULD. 127 


Fig. 100, 
Group of sporangia of a mucor (Rhizopus nigricans) showing rhizoids and the stolon 
extending from an older group. . 


These are small rounded or oval bodies. The wall of the 
sporangium becomes dissolved, except a small collar around 
the stalk which remains attached be- 
low the columella (fig. 101). By this 
means the gonidia are freed. These 
gonidia germinate and produce the 
mycelium again. 


Fig. ror. 
A mucor (Rhizopus nigricans) ; at left nearly mature sporangium with columella show- 
ing within ; in the middle is ruptured sporangium with some of the gonidia clinging to the 
columella; at right two ruptured sporangia with everted columella, 


128 BOTANY. 


214. To show the “runners” of the black mould.—If some 
filter paper is placed by the side of the bread or other substance 
in the moist chamber, some of the threads of the fungus may 
be induced .to grow over on to it. If the mould is the species 
illustrated in fig. 100 there may be seen ‘‘ runners’’ like those 
in the figure with clusters of the sporangia at certain points. 
Certain threads of the mycelium grow along on the paper like 
a strawberry ‘‘runner’’ does over the ground. Here and there 
the mycelium touches the paper and forms little rootlets, and 
also a group of the sporangia. It is because of this character that 
the plant is called Mucor stolonifer, the stolon bearing mould. 
Or the other name of ‘‘ rhizopus’’ is given because it is ‘‘ root- 
footed.’’ 


Synopsis. 

{ Grows on old bread, decaying fruits, vegetables, etc. 

Vegetative part; delicate whitish threads, which 
branch, and form a cottony-like mat, called the my- 
celium. 

Fruiting part ; upright stout threads bear black heads, 
called sporangia. 

Several fruiting threads in a cluster, 
with rhizoids at base. 

Sporangium. 

Sporangium wall. 

Columella. 

Spores (or gonidia), 

| Sexual stage not treated of here. 


The black mould. 


Fruiting part. 


Material,—Cultures of the black mould on bread or baked potatoes, See 
paragraph 49 for making the cultures. 

Microscope, etc. 

If conjugation of a mould is desired, it may be purchased of supply com. 
panies. 


CHAPTER XXII. 


FUNGI (Continuev): WHEAT RUST. 


(Puccinia graminis.) 


215. Importance of the rusts.—The fungi known as ‘‘ rusts ”’ 
are very important ones to study, since all the species are para- 
sitic, and many produce serious injuries to crops. 


Exercise 45. 


216. Black rust of wheat.—Dried stalks of wheat or oats with the black 
spots of this stage of the rust are excellent for the study. Sketch a portion of 
an affected stalk, showing the spots in natural size and form. With,a hand 
lens examine the spots more carefully. Observe that the black mass of color 
has burst through the epidermis of the wheat. Describe the appearance. 

217. Red rust of wheat.—This stage is found abundantly on the leaves of 
the wheat and oats, etc. Dried leaves which have been pressed are good 
for the study. Observe the color of the spots, and compare with that of the 
black-rust spots. Compare the size also. Examine with a hand lens, and 
determine whether the mass of spores making up the rust color, break through 
the epidermis. Sketch a portion of the leaf showing the characters observed. 

218. Cluster-cup stage on the barberry.—Leaves of the barberry may be 
pressed dry and preserved for study. Sketch a leaf showing the location and 
character of the spots. Describe the form and character of the spots. Ex- 
amine the spots on both sides of the leaves with a hand lens. Describe what 
you see. If leaves of the barberry with the cluster cups cannot be obtained 
some other cluster-cup fungus may be used, but it should be understood that 
the others are not connected with the wheat rust (except some growing on 
shrubs closely related to the barberry). 


Demonstration 33. 


219. To demonstrate the different stages of the wheat rust under the micro- 
scope.— Black rust: with a knife scrape out the material from a few black 
spots, tease out in water on a glass slip, and mount as usual. ed rust: pre- 

129 


130 BOTANY. 


pare in the same way from the yellow spots. Todemonstrate the cluster cups, 
good cross-sections of the leaf through a spot should be made, or prepared 
slides should be obtained. Let the pupils sketch the form of the different 
spores, and other characters, and make notes of the observations. 

To demonstrate mycelium in the tissues, use the carnation rust which can 
be obtained in winter in greenhouses where the carnations are grown (see 
Chapter XV, paragraph 159), or fresh wheat leaves may be preserved in 
alcohol for making sections. 


220, Wheat rust (Puccinia graminis)—The wheat rust is 
one of the best known of these fungi, since a great deal of study 
has been given to it. One form of the plant occurs in long 


: ee 


Fig. 102. Fig. 103. Fig. 104. Fig. 105. Fig. 106 
Wheat leaf with red Portion of leaf Black rust. Enlarged. Single 
rust, natural size, enlarged to show Natural size. sorus, 


sori. 
Figures roz, 103.—Puccinia graminis, red rust stage (uredo stage), 
Figures 104-106.—Black rust of wheat, showing sori of teleutospores, 


reddish-brown or reddish pustules, and is known as the “‘ red 
tust’’ (figs. 102, 103). Another form occurs in elongated 
black pustules, and this form is the one known as the ‘‘ black 
tust’’ (figs. 104-107). These two forms occur on the stems, 
blades, etc., of the wheat, also on oats, rye, and some of the 
grasses. 

221. Teleutospores of the black-rust form.—Scrape off some 
portion of one of the black pustules (sori), tease it out in 
water on a slide, and examine with a microscope, to see numer- 


FUNGI: WHEAT RUST. 131 


ous spores, composed of two cells, and having thick, brownish 
walls as shown in fig. 108. Usually there is a slender brownish 
stalk on one end. These spores are called /eleutospores. They 
are somewhat oblong or elliptical, a little constricted where the 
septum separates the two cells, and the end cell varies from ovate 


\Y 
Sad fi Fig. 108, 
mie Teleutospores of wheat rust, 
Ye showing two cells and the pedicel, 
Ay! 
{ 
i 
{ 
¢ 
i 
Fig. 107. Fig. 109. 
Head of wheat showing black .rust spots Uredospores of wheat rust, one 
on the chaff and awns. showing remnants of the pedicel. 


to rounded. The mycelium of the fungus courses between the 
cells, just as is found in the case of the carnation rust, which 
belongs to the same family (see Chapter XV). 

222. Uredospores of the red-rust form.—lIf we make a 
similar preparation from the pustules of the red-rust form we 
shall see that instead of two-celled spores they are one-celled. 


132 BOTANY. 


The walls are thinner and not so dark in color, and they are 
covered with minute spines. They have also short stalks, but 
these fall away very easily. These one- 
celled spores of the red-rust form are 
called ‘‘ uredospores.’’ The uredospores 
and teleutospores are sometimes found in 
the same pustule. 

It was once supposed that these two 
kinds of spores belonged to different plants, 
but now it is known that the one-celled form, 
the uredospores, is a form developed earlier 
in the season 
than the teleu- 
tospores. 

223. Cluster- 
cup form on 
the barberry. 


—On the bar- 

berry is found 

Fig. 110. Fig. 111. Fig. 12. still another 

Barberry leaf with two Single spot Two cluster 

diseased spots, natural showing cluster cups more en- form of the 

slze. cups enlarged. larged, showing wheat rust, the 
split margin. i 

Figures 153-155.—Cluster-cup stage of wheat rust. “* cluster cup ws 

stage. The 


pustules on the under side of the barberry leaf are cup-shaped, 
the cups being partly sunk in the tissue of the leaf, while 
the rim is more or less curved backward against the leaf, and 
split at several places. These cups occur in clusters on the 
affected spots of the barberry leaf as shown in fig. 111. Within 
the cups numbers of one-celled spores (orange in color, called 
zcidiospores) are borne in chains from short branches of the 
mycelium, which fill the base of the cup. In fact the wall of 
the cup (peridium) is formed of similar rows of cells, which, 
instead of separating into spores, remain united to forma wall. 
These cups are usually borne on the under side of the leaf. 


FUNGI: WHEAT RUST. 133 


For a fuller study of the wheat rust and of other fungi see the 
author’s larger ‘‘ Elementary Botany,’’ Chapters XX, XXI. 


Fig. 113. 
Section through leaf of barberry at point affected with the cluster-cup stage of the wheat 
rust; spermagonia above, zxcidia below. (After Marshall-Ward.) 


Synopsis, 


( A parasite on grains, grasses, and on the barberry. 
Vegetative part of plant; mycelium growing within the tissues 
of the host. 
Fnuiting part of the plant. 
Ist. Red rust (one-celled spores in pustules on 
blades and stems of the wheat). 
2d. Black rust (two-celled spores in pustules 
on the blades and stems of the wheat), 
3d. Cluster cup (one-celled spores in chains 


Wheat rust. i 


Four forms. 4 aan ee 
within a structure called a peridium, or 


cup on leaves and stems of barberry). 
4th. Spermagonia (small flask-shaped bodies 

accompanying the cluster cups, of un- 
L known function). 

Material.—Dried stalks of wheat or oats with the black-rust spots ; dried 
leaves with the red-rust spots ; leaves of the barberry with the clustcr cups. 
(If the barberry leaves cannot be obtained, another species of cluster cup may 
be used to illustrate the zecidial stage, but it should be remembered that other 
cluster cups are not connected with the life history of the wheat rust.) 

For satisfactory studies of the cluster-cup stage, sections through the cup 
should be made from fresh material, or sections already made may be pur- 
chased from the supply companies, \ 

Microscope, etc. 


\ 


CHAPTER XXIII. 


FUNGI (ConcLupep): THE WILLOW MILDEW. 


(Uncinula salicis.) 


224. Description of the mildew.—The willow mildew belongs 
to a very interesting group of the fungi known as the powdery 
mildews. These mildews are very common on the leaves, and 
even stems, flowers, and fruits, of various plants. It is a very 
easy matter to find them during the summer or late autumn and 
to press a number of the leaves to preserve for future study. 

The mycelium grows on the outside of the parts of the host, 
so that it gives a whitish, “‘ mildewed’’ appearance to the 
affected places. Very short branches (haustoria) from the 
mycelium enter the epidermal cells of the host and draw nutri- 
ment from vhe leaves or other parts, and supply the fungus with 
the materials for growth. This nutriment is taken at the 
expense of the host, and often considerable injury to it is thus 
done, which results in a sickly appearance of the host, or even 
in a deformity, the leaves or stems being curled or dwarfed. 
Immense numbers of small, colorless spores (gonidia) are borne 
in chains on some of the threads, and these piled up on the 
surface of the leaf give it a powdered appearance. 

After this powdery stage of the fungus has formed, 
another kind of fruit of the fungus is developed. This may be 
detected by numerous minute black specks seated on the white 
mycelium, as shown in fig. 114. Each one of these black 
specks is a fruit body. 

134 


FUNGI: THE WILLOW MILDEW. 135 


Exercise 46. 


225. The Willow Mildew.—Take dried leaves, or those freshly collected, 
which show some of the whitish mycelium, and numerous black fruit bodies. 


Fig. 114. 
Leaves of willow showing willow mildew. The black dots are the fruit bodies (perithecia) 
seated on the white mycelium. 


Observe the white mycelium. - Is it scattered unevenly over the surface of the 
leaf, or does it form more or less circular spots? Is there any difference in 


136 BOTANY. 


the color or appearance of the leaf in the spots where the mycelium is 
seated ?* Try to remove some of the mycelium with a needle, to see that 
it consists of threads which are on the surface of the leaf. 

Fruit bodies. Observe the minute black specks seated on the mycelium. 
Are all of them black, or dark in color? If there are any yellowish ones 
how do they compare with the dark ones as to size? How do they compare 
‘as to age? With a hand lens examine them more carefully. Can you see 
any dark-colored threads extending out from the fruit body? Can you see 
their form ? 


Demonstration 34. 


226. The fruit bodies.—Place a drop of water on a glass slip. Touch the 
point of a scalpel or knife to the water and then scrape the surface of the 
leaf gently where there are a number of the black bodies. The capillarity of 
the water will hold some of the fruit bodies to the point of the knife. From 
this tease off the fruit bodies with a needle into the drop of water on the 
slip. Separate them well and put on the cover glass. 

Let each pupil examine the fruit bodies under the microscope. Note the 
form of surface markings and the appendages. Sketch. 

227. The asci and spores which they contain.—Take this same prep- 
aration, crush the fruit bodies by gently pressing on the cover glass above 
them, until the fruit bodies are cracked open, and some of the sacs containing 
the spores are pressed out (see fig. 116). Let the pupils examine and sketch 
them. 

The gonidia may be demonstrated by using leaves where the fruit bodies 
are not abundant, but which possess an abundance of the mycelium (see 


fig. 115). 


228. Fruit bodies of the willow mildew.—On the mycelium 
there appear numerous black specks scattered over the affected 
places of the leaf. These are the fruit bodies (perithecia). 
When examined with a low power of the microscope, each one 
is seen to be a rounded body, from which radiate numerous 


* Ifthe leaves are not old the portions where the mycelium is seated may 
be more or less yellow, showing an injury ; but if the leaves are quite old 
and nearly ready to fall, the green color may have disappeared more rapidly 
from the unaffected parts of the leaf, for the fungus gives some stimulus to the 
leaf, and often this is manifested by the green color remaining longer in the 
affected parts of the old leaves, 


FUNGI: THE WILLOW MILDEW. 137 


filaments, the afpendages. Each one of these appendages is 


coiled at the end into the form of a little hook. Because of 
these hooked appendages this genus is called uxcizula. This 


rounded body is the perithecium. 

229. Asci and ascospores.—While we are looking at a few of 
these through the microscope with the low power, we should 
press on the cover glass with a needle until we see a few of the 


Fig. x15. Fig. 116, Fig. 117. 
Willow mildew ; bit Fruit of willow mildew, showing hooked ap- Fruit body of an- 
of mycelium with pendages, Genus uncinula, other mildew with 
erect | conidiophores, Figures 116, 117.—Perithecia (perithecium) dichotomous appen- 
dages. Genus 


bearing chain of of two powdery mildews, showing escape of 
gonidia;" gonidium at ascj containing the spores from the crushed 
left germinating. fruit bodies, 


microsphzra, 


perithecia rupture. If this 1s done carefully we see several 
small ovate sacs issue, each containing a number of spores, as 
shown in fig. 116. Such a sac is an ascus, and the spores are 
ascospores. 


138 


Synopsis. — 


Willow mildew. 


[ 


BOTANY. 


Vegetative part of the plant : mycelium on the surface of 
the host sends suckers (haustoria) into the cells of the 
host. 

Propagative stage of the plant: ‘short erect threads which 
bear chains of spores (gonidia). 

Fruiting part of the plant (perfect stage). 

Perithecium with hooked appendages. 
Perithecium contains sacs (asci). 
The sacs contain the spores (ascospores). 


Material.—Dried and pressed leaves of willow with the white mildew, also 
older stages showing the numerous black ‘* specks,’’ the fruit bodies, of the 
mildew. Other species of the mildew may be used if preferred. 

Microscope, etc. | 


CHAPTER XXIV. 
LIVERWORTS (HEPATICA£). 
(Marchantia polymorpha.) 


230. Form of marchantia.—The marchantia (M. polymorpha) 
has been chosen for study because it is such a common and 
easily obtained plant, and also for the reason that with com- 
parative ease all stages of development can be obtained. It 
illustrates also very well certain features of the structure of the 
liverworts. 

The plants are of two kinds, male and female. The two 
different organs, then, are developed on different plants. In 
appearance, however, before the beginning of the structures 
which bear the sexual organs they are practically the same. 

The plant forms a flattened, green; leaf-like body which lies 
on the damp soil or clings closely to wet rock. It is shaped 
somewhat like an irregular ribbon, the margins more or less 
wavy, and the plant is branched in a forked manner as shown 
in fig. 118. Upon the under side are numerous hair-like 
bodies, the ‘‘ rhizoids,’’ which serve the purpose of root hairs 
in absorbing food solutions, and they also attach the plant to 
the substratum. The growing point of the thallus is in the 
little depression at the free end. 

For fuller studies of the liverworts and for the sexual organs 
see the author’s larger ‘‘ Elementary Botany,’’ Chapters XXII 
and XXIII. 


Exercise 47. 

231. Male plants.—Examine both surfaces of the ‘‘thallus’”’ as the leaf- 
like body of the liverwort is called. Note where the rhizoids are attached. 
Sketch the plant, showing the rhizoids, the form of the thallus, and the um- 

139 


140 BOTANY. 


brella-shaped bodies on the upper surface. Note that the expanded part 
of this umbrella-shaped structure is crenate on the margin, giving it a lobed 
appearance, and that these lobes radiate from the centre. Search for 
little pits opening on the upper surface of these structures ; these are the 
opening of the chambers where the antheridia are borne. With a hand lens 
examine the upper surface of the thallus. Can you see that it is marked oft 
into diamond-shaped areas, with a minute opening in the centre of each? 
These openings are the stomates of the thallus. Observe that the central 
line of the thallus is thicker than the margins. This is the midrib. 


Exercise 48. 


232. Female plants.—Study these in a similar way, and compare. The 
thallus is very similar, the greater point of difference being in the umbrella- 
shaped structures. Note that the expanded portion is more deeply lobed, 
forming prominent rays. On the under surface observe the delicate hanging 
fringes. Underneath these the archegonia are borne. If material with ripe 
fruit is at hand preserved in formalin, observe the rounded capsules on short 
stalks which protrude from beneath these curtains. Sketch and describe all 
parts of the plant. 


Exercise 49. 


233. Sterile plants bearing. cups and gemmz.—Study these in a similar 
way. Note that the umbrella-shaped structures are absent. Observe the 
minute cups on the upper surface. With a hand lens note the minute flat- 
tened green bodies within the cups. These are the gemma, or buds, and 
serve as one means of propagating the plant. 


Demonstration 35. 
(May be omitted.) 


234, Sexual organs.—The teacher may make demonstrations to show the 
sexual organs, and the spores and elaters. For the antheridia section the 
antheridial receptacle, and for the archegonia section the archegonial recep- 
tacle. Unless one is familiar with methods of sectioning these structures, it 
would be better to purchase prepared sections of these organs for the demon- 
stration. See fig. 123. 


Demonstration 36. 


235. Spores and elaters.—When the fruit is ripe (see fig. 125) and the 
spores and elaters are escaping some may be mounted. They may be 
mounted in glycerine jelly. Such mounts will keep for a long time if cared 


LIVERWORTS. 141 


for, and will serve for successive years’ study. Mounts may also be made 
from material preserved in formalin, Tease out a few of the spores and 
elaters from the capsule with needles, ina drop of alcohol on the glass slip. 
Melt a bit of glycerine jelly on a cover glass and just as the alcohol is evap- 
orating from the slide lower the glycerine with the cover over them. See 
figure 126. 

Spores and elaters from some other liverwort may be used if more 
convenient, 


236. Antheridial plants.—One of the male plants is figured 
at 118. It bears curious structures, each held aloft by a short 
stalk. These are the antheridial re- 
ceptacles. Each one is circular, thick, 
and shaped somewhat like a bi-convex 
lens. The upper surface is marked by 
radiating furrows, and the margin is 
crenate. Then we note, on careful 


examination of the upper 
surface, that there are 
numerous minute open- 
ings. If we make a thin 
section of this 
structure  per- 
pendicular to 
its surface we f 
shall be able to 
unravel the mys- 
tery of its in- 
terior. Here we see, as shown in fig. 119, that each one of 
these little openings on the surface is an entrance to quite a 
large cavity. Within each cavity there is an oval or elliptical 
body, supported from the base of the cavity on a short stalk. 
This is an antheridium, and one of them is shown still more 
enlarged in fig. 120. This shows the structure of the anther- 
idium, and that there are within several angular areas, which 
are divided by numerous straight cross-lines into countless 
tiny cuboidal cells, the sperm mother cells. Each of these 


Fig, 118. 
Male plant of marchantia bearing antheridiophores. 


142 BOTANY. 


changes into a swiftly moving body resembling a serpent with 
two long lashes attached to its tail. 


ey 


Fig. 1 9. 
Section of antheridial receptacle from male plant of Marchantia polymorpha, showing 
cavities where the antheridia are borne. 


237. Archegonial plants—In fig. 122 we see one of the 
female plants of marchantia. Upon this there are also very 
curious structures, which remind one of miniature umbrellas. 


e 


Fig. 120. Fig. 120. 
Section of antheridium of mar- Spermatozoids of marchantia, 
chantia, showing the groups of uncoiling and one extended, 
sperm mother cells. showing the two cilia. 


The general plan of the archegonial receptacle is similar to that 
oi the antheridial receptacle, but the rays are more pronounced, 


LIVERWORTS. 143 


and the details of structure are quite different, as we shall see. 
Underneath the arms there hang down delicate fringed curtains. 
If we make sections of this in the same direction as we did of 
the antheridial receptacle, we shall be able to find what is 


Fig. 122. 
Marchantia polymorpha, female plants bearing archegoniophores, 


secreted behind these curtains. Here we find the archegonia, 
but instead of being sunk in cavities their bases are attached to 
the under surface, while the delicate, pendulous fringes afford 
them protection from drying. 


144 BOTANY. 


238. Sporogonium of liverworts. If the sporogonium 
(spore-case) of marchantia cannot be obtained those of any 
other liverwort may be used. 

239, Sporogonium of marchantia.—lf 
we examine the plant shown in fig. 124 
we ‘shall see oval bodies which stand out 
between the rays of the female receptacle, 
supported on short stalks. These are the 
sporogonia, or spore-cases. We can see 
that some of the spore-cases have opened, 
the wall splitting. down from the apex 
in several lines. This is caused by the 
drying of the wall. These toothlike 
divisions of the wall now curl backward, 
and we can see the yellowish mass of the 
spores in slow motion, falling here and 
there. It appears also as if there were 
twisting threads which aided the spores 
in becoming freed from the capsule. 


Fig. 123. 
Marchantia polymorpha, 240. Spores and elaters.—If we take 
archegonium with egg; J, y : 


curtain which hangs down a bit of this mass of spores and mount 
around the archegonia; .e, 


egg; v, venter of-archego- it in water for examination with the 


nium; 2, neck of ,archego- 
nium. as 


microscope, we shall-see that, besides 
the spores, there are very peculiar thread-like bodies, the mark- 
ings of which“rémind one-of' a ‘twisted rope. These are very 
long cells .froni the’ inner‘part of the spore-case, and their 
walls are marked™by spiral thickenings. : This causes them in 
drying, and also when they absorb moisture, to twist and curl 
in all sorts of ways. They thus aid in pushing the spores out 
of the capsule as it is drying. 

241. How marchantia multiplies—New plants of mar- 
chantia are formed by the germination of the spores, and 
growth of the same to the thallus. The plants may also be 
multiplied by parts of the old ones breaking away by the action 
of strong currents of water, and when they lodge in suitable 


LIVERWORTS. 145 


places grow into well-formed plants. As the thallus lives from 
year to year and continues to grow and branch the older por- 
tions die off, and thus separate plants may be formed from a 
former single one. 

242. Buds, or gemme, of marchantia.—But there is an- 
other way in which marchantia multiplies itself. If we exam- 


Fig. 124. 


Archegonial receptacles of marchantia bearing ripe sporo- 
gonia. The capsule of the sporogonium projects outside, 
while the stalk is attached to the receptacle underneath the 
curtain. In the left figure two of the capsules have burst 
and the elaters and spores are escaping. 


Fig 125. 

Section of archegonial receptacle of Marchantia polymorpha ; ripe 
sporogonia One is open, scattering spores and elaters; two are 
still enclosed in the wall of the archegonium, The junction of the 
stalk of the sporogonium with the receptacle is the point of attach- 
ment of the sporophyte of marchantia with the gametophyte. 


ine the upper surface of such a plant as that shown in fig. 127, 
we shall see that there are minute cup-shaped or saucer-shaped 


146 BOTANY. 


vessels, and within them minute green bodies. When these 
green buds free themselves from the cups they come to lie on 
one side and develop into new plants. It does not matter on 


Fig. 126. 


Etater and spore of marchantia. sf, spore; mc, mother cell of spores, 
showing partly formed spores. 


what side they lie, for whichever side it is, that will develop 
into the lower side of the thallus, and will form rhizoids, while 


the upper surface will develop the stomates. 


LIVERWORTS. 147 


Fig. 127. 
Marchantia plant with cupules and gemmz; rhizoids below. 


Synopsis. 
{ Plant body ; flattened, ribbon-like, green, with rhizoids on 
under surface ; grows in moist situations, 
Ist. Plant with buds in little cups. 
The buds escape and propagate the plant. 
2d. Male plants. 
Antheridial receptacle. 
Vegetative part. Antheridial cavities. 
Marchantia Three forms. + Antheridium. 
(A liver- 3 Spermatozoids. 
wort). 3d. Female plants. 
Archegonial receptacle. 
Archegonium. 
L Egg. 
Capsule wall. 
Fruit capsule. { Spores. 
Fruiting part. s ie 
Short stalk attaching fruit body to archego- 
L nial receptacle. 


148 BOTANY. 


Material and apparatus.—Freshly collected plants, or if these cannot be 
had, plants preserved in 2% formalin, or in alcohol, may be used. Some 
plants dry are often useful if they are not to be had in any other condition. 

Plants with the cups and gemme; male plants; and female plants. 

For the study of the fruit bodies plants must be had either fresh (but this is 
quite impossible since they ripen in June and July) or better, plants with ripe 
fruit bodies may be preserved in 2% formalin. 

For the demonstration of the sexual organs, and of the spores and elaters, 
the teacher may make sections, or purchase sections of supply companies. 
Hand lenses, or simple dissecting microscopes. 

Microscope, etc., for demonstrations 35 and 36. 


CHAPTER XXvV. 


MOSSES (MUSCI). 


(Polytrichum, or mnium.) 


243, The moss plant.—We are now ready to take up the 
more careful study of the moss plant. There are a great many 
kinds of mosses, and they differ greatly from each other in the 
finer details of structure. Yet there are certain general re- 
semblances which make it convenient to take for study almost 
any one of the common species in a neighborhood, which forms 
abundant fruit. Some, however, are more suited to a first 
study than others. 

Those mosses in which there is a marked difference between 
the male,and female plants, like polytrichum, bryum, mnium, 
etc., are most suitable for the purpose. The male plants of 
these genera have the leaves at the end of the stem in a broad 
rosette. Both male and female plants should be collected, and 
the fruiting plants also. The latter bear above the leafy portion 
a stalked capsule. Polytrichum (known as pigeon wheat moss) 
is suggested here for the practical study, while mnium is here 
used to illustrate the mosses. It will be found useful occa- 
sionally to study a plant that is different from the one fully 
illustrated in the book, since it gives the student an ORE OMRY 
for more independent work. 


Tur Piczon WueEat Moss (Potyrricnum). 


Exercise 50. 


244. The fruiting plant.—Take entire plants, those with leafy stems 
bearing the stalked capsule. Sketch the entire plant. Note the stem (axis) 
and the three rows of leaves. Search for the rhizoids at the lower end of 
the stem. What is their color? Observe the capsule, its form. 

149 


150 BOTANY. 


Among the material search for those capsules representing several different 
ages. Very young ones are often collected when there appears to be nothing 
but a slender stalk, the capsule not yet being fully developed. Search on the 
capsule for the hairy hood, known as a calypftra. Remove this; note its form. 
Now at the end of the capsule note the conic lid (the operculum). Remove 
this, or examine older capsules where the lid has fallen away. Note the 
numerous teeth. When the lid is removed, are there any small granules 
(the spores) escaping? Compare the shape of the capsules of different ages. 


Exercise 51. 


245. The male plants.—Note the broad rosette of leaves at the end of the 
stem. Compare the arrangement of the leaves here with those lower down 
onthe stem. Sketch. The antheridia (sing. antheridium) are borne in the 
centre of the rosette. ; 

246. The female plants.—Compare with the male plants: what is the 
difference in the arrangement of the leaves? Can you suggest why the 
leaves are arranged differently in the two plants ? 


Demonstration 37. 
(May be omitted when necessary.) 

247. Demonstration of spores, etc.—The teacher can prepare mounts of 
the spores, and of a portion of the mouth (peristome) of the capsule for study. 
If it is desired also leaves may be examined under the microscope. The 
leaves are made up of a single layer of cells, except at the middle line where 
the cells are several layers thick, and long and narrow. The cells in the 
middle line form the ‘‘ midrib” of the leaf. The teacher can also make 
sections through the ends of the male and female plants to demonstrate the 
sexual organs, or prepared slides representing these may be purchased for 
demonstration. 


Description oF THE Moss, Myrum. 


248, Mnium.—We will select here the plant shown in fig. 
128. This is known as a mnium (M. affine), and one or 
another of the species of mnium can be obtained without much 
difficulty. The mosses, as we have already learned, possess an 
axis (stem) and leaf-like expansions, so that they are leafy- 
stemmed plants. Certain of the branches of the mnium stand 
upright, or nearly so, and the leaves are all of the same 
size at any given point on the stem, as seen in the figure, 


MOSSES. 151 


There are three rows of these leaves, and this is true of most of 
the mosses, 
249. Habit of mnium.—The mnium plants usually form 


quite extensive and pretty mats of green in 
shady moist woods or ravines. Here and 
there among the erect stems are prostrate 
ones, with two rows of prominent leaves 
so arranged that they remind one of some 
of the leafy-stemmed liverworts. If we 
examine some of the leaves of the mnium 
we will see that the greater part of the 
leaf consists of a single layer of green cells, 
just as is the casein the leafy-stemmed 
liverworts. But along the middle line is 
a thicker layer, so that it forms a dis- 
tinct midrib. This is characteristic of 


Fig. 128. 


dl Portion of moss plant of Mnium affine, showing two 
ly A |) sporogonia from one branch. Capsule at left has just 
Yy Gal N\ shed the cap or operculum ; capsule at right is shedding 
7 ) spores, and the teeth are bristling at the mouth, Next 

to the right is a young capsule with calyptra still attached; 


next are two spores enlarged. 


the leaves of mosses, and is one way in which they are sepa- 
rated from the leafy-stemmed liverworts, the latter never having 


a midrib. 


152 BOTANY. 


250. The fruiting moss plant.—In fig. 128 is a moss plant 
‘‘in fruit,’’? as we say. Above the leafy stem a slender stalk 
bears the capsule, and in this capsule are borne the spores. 


251. Sporogonium of the moss.—The sporogonium (spore- 
case) of a moss is illustrated 


in fig. 128. The sporo- 
gonium is the portion repre- 
sented above the leafy part, 
and consists of a stalk and 


capsule. This was devel-~ 
oped from the fertilized egg. 


Fig. 129. Fig. 130. 
Female plant (gametophyte) of a moss Male plant (gametophyte) of a moss 
(mnium), showing rhizoids below, and the (mnium) showing rhizoids below and the 


tuft of leaves above which protect the antheridia at the.centre above surrounded 
archegonia. by the rosette of leaves. 


The capsule is nearly cylindrical, bent downward, and supported 
on a long slender stalk. 


MOSSES. 153 


Upon the capsule is a peculiar cap, shaped like a ladle or 
spatula, the calypira. 

252. Structure of the moss capsule.—At the free end on 
the moss capsule as shown in the case of mnium in fig. 128, 
after the remnant of the archegonium falls away, there is seen 
a conical lid which fits closely over the end. When the capsule 
is ripe this lid easily falls away, and can be brushed off, so that 
it is necessary to handle the plants with care if is desired to 
preserve this for study. 

253. Opening of the capsule——When the lid is brushed away 
as the capsule dries more, we see that the end of the capsule 
covered by the lid appears ‘‘ frazzled.’’ If we examine this end 
with the microscope we will see that the tissue of the capsule 
here is torn with great regularity, so that there are two rows of 
narrow, sharp teeth which project outward in a ring around the 
opening. If we blow our “‘ breath’’ upon these teeth they will 
be seen to move, and as the moisture disappears and reappears 
in the teeth, they close and open the mouth of the capsule, so 
sensitive are they to the changes in the humidity of the air. 
In this way all of the spores are prevented to some extent from 
escaping from the capsule at one time. 

254, The male and female moss plants.——The two plants 
of mnium, shown in figs. 129, 130, are quite different, as one 
can easily see, and yet they belong to the same species. One 
is a female plant, while the other is a male plant. The sexual 
organs, then, in mnium, asin many others of the mosses, are 
borne on separate plants. The archegonia are borne at the 
end of the stem, and are protected by somewhat narrower 
leaves which closely overlap and are wrapped together. They 
are similar to the archegonia of the liverworts. 

The male plants of mnium are easily selected, since the 
leaves at the end of the stem form a broad rosette with the 
antheridia, and some sterile threads packed closely together in 
the centre. The ends of the mass of antheridia can be seen 
with the naked eye, as shown in fig. 130. 


154 BOTANY. 


Synopsis. ‘ 
Plant body, a small leafy stem, with rhizoids. 
( Protonema (branched green threads 
which precede the leafy stem). 
Male plants with a rosette of leaves at 
the end. 
Vegetati £ 
Se eer Antheridia. 
of plant. ) : 
Spermatozoids. 
Three forms. 
Female plants, leaves closed together at 
Moss plant 
i the end. 
(Polytrichum ‘ 
ane SNe: Archegonia. 
Pets) . Archegonium contains egg. 
| Capsule wall. 

Fruit capusule. 4 ct 

Fruiting part. | Teeth at mouth. 
Stalk. | Spores. 

(The hood is not a part of the capsule, but is the remains 

lof the archegonium.) 


Material and apparatus.—The pigeon wheat moss (polytrichum) is an ex- 
cellent one to study, but one should not be confined to this if it is easier to 
collect other species which show strong differences between male and female 
plants. Male and female plants, as well as plants with fruit, some of which 
should possess the ‘‘hood,”’ should be preserved dry, or in 2% formalin. 

Free hand, or prepared, sections of the sexual organs. 

Apparatus, the same as in Chapter XXIV. 


CHAPTER XXVI. 


FERNS (FILICINEA®). 
(The polypody, or Christmas fern.) 


255. Importance of study of ferns.—In taking up the study 
of the ferns we find plants which are very beautiful objects of 
nature and thus have always attracted the interest of those who 
love the beauties of nature. But they are also very interesting 
to the student, because of certain remarkable peculiarities of 
the structure of the fruit bodies, and especially because of the 
intermediate position which they occupy within the plant king- 
dom, representing in the two phases of their development the 
primitive type of plant life on the one hand, and on the other 
the modern type. We will begin our study of the ferns by tak- 
ing that form which is the more prominent, the fern plant itself. 

256. Selection of fern for study.—There are several ferns 
which answer equally well for study. It is important to have 
the entire plant, underground stem, roots, and leaves, and what 
is of especial importance, some of the leaves should have the 
‘fruit dots.’? The common polypody (Polypodium vulgare) 
is widely distributed, and will be useful for the practical study, 
even though the Christmas fern here is used to illustrate the 
descriptive part. There should, however, be no necessity for 
limiting the study to a certain species, since in one locality 
one species can be more easily obtained, while in another 
locality another species may be more convenient to study. 


Exercise 52. 


257. The fern plant.—Take entire plants, if the common polypody, note 
the creeping stem (root-stock or rhizome), the numerous brown scales cov- 


159 


156 BOTANY. 


ering it, the bud at the anterior end covered also with brown scales. Ob- 
serve the numerous dark slender roots. 

Note the leaves, some of them perhaps plain (sterile) on the under side, 
while others have numerous circular brown or blackish dots, the fruit dots 
where the sporangia (spore-cases) and spores are borne. Describe the form 
of the leaf. Name the different parts. Sketch the entire plant. Sketch a 
portion of the under side of the spore-bearing leaf, to show the fruit dots. 
Compare the polypody with several other species of ferns if possible. 


Exercise 53. 


258. The scattering of the spores.—If the study is made at a time when 
the ferns with spores just ripe cannot be collected out doors, get some leaves 
from greenhouses. Take those leaves where the fruit dots appear quite 
black, and under the lens the sporangia appear like shiny rounded black 
bodies. Place a leaf on white paper ina dry room, with the under side 
uppermost. In the course of an hour or earlier watch for showers of spores 
which are scattered around the leaf, Sometimes in a dry room these begin 
to scatter in the course of a few minutes. The success of this exercise will 
depend on the material being in the right condition. After a little experi- 
ence in collecting it is not difficult to get the right material. 


Demonstration 38. 


259. To show the sporangia.—These can be shown from sporangia 
which are just ripe, or from older material which has been dried, or pre- 
served in formalin or alcohol. Scrape off a few of the sporangia from the 
‘(fruit dot.” Mount them in water for examination under the microscope. 

LET EACH STUDENT EXAMINE the form and structure. Sketch a sporan- 
gium seen from the side. Name the different parts, the slender stalk, the 
enlarged spore-case. In the spore-case make out a prominent row of cells 
over the back and upper part (the azzuZus), note the ‘lip cells” in front, 
one each side of the place where the sporangium opens. If there are any 
spores in this preparation note and describe them; sketch one also. If 
there are none to be seen in the preparation made for the study of the 
sporangium the teacher can mount some for study if desired. 

To see the snapping of the sporangium fresh ripe material may be 
mounted in water ; then draw under the cover glass some glycerine and 
watch the result. 


260. The Christmas fern.—One of the ferns which is very 
common in the Northern States, and occurs in rocky banks and 
woods, is the well-known Christmas fern (Aspidium acrosti- 


FERNS. 157 


choides) shown in fig. 131. The leaves are the most prominent 
part of the plant, as is the case with most if not all our native 
ferns. The stem is very short and for the most part under the 
surface of the ground, while the leaves arise 

very close together, and thus form a rosette 

as they rise and gracefully bend outward. 

je The leaf 

“ § is elongate 

and re- 
minds one 
somewhat 
of a plume 
with the 
pinne ex- 
tending in 
two rows 
[Adaeée on oppo- 
site sides 
of the midrib. These 
pinne alternate with 
one another, and at the 
base of each pinna is a 
little spur which projects 
upward from the upper 
edge. Such a leaf is said 
to be pinnate. While all 
the leaves have the same 


general outline, we notice 
eS ee = that certain ones, especi- 
Fig. 131. : ally those toward the centre 
Christmas fern (Aspidium acrostichoides). at te rosette, are — 
narrower from the middle portion toward the end. This is 
because of the shorter pinnz here. 
261. Fruit “dots” (sorus, indusium).—If we examine the 
under side of such short pinnz of the Christmas fern we see that 


158 BOTANY. 


there are two rows of small circular dots, one row on either 
side of the pinna. These are called the ‘‘ fruit dots,’’ or sori 
(a single one isa sorus). If we examine it with a low power 
of the microscope, or with a pocket lens, we will see that there 
is a circular disk which covers more or less completely very 
minute objects, usually the 
ends of the latter projecting 
just beyond the edge if they 
are mature. This circular 
disk is what is called the 
indusium, and it is a special 
outgrowth of the epidermis 
of the leaf here for the pro- 
tection of the spore-cases. 


\\ \. These minute objects un- 
al derneath are the fruit bodies, 
p eal \ which in the case of the 

ene” ferns and their allies are 
ai ( called sporangia. This in- 

K dusium in the case of the 


Christmas fern, and also in 
some others, is attached to 
the leaf by means of a short 
slender stalk which is fast- 
ened to the middle of the 
under side of this shield. 
262. Sporangia.—If we 
section through the leaf at 


Fig. 132. : 
Rhizome with bases of leaves, and roots of the one of the fruit dots, or if 


Christmas fern, 


we tease off some of. the 
sporangia so that the stalks are still attached, and examine them 
with the microscope, we can see the form and structure of 
these peculiar bodies. Different views of a sporangium are 
shown in fig. 137. The slender portion is the stalk, and the 
larger part is the spore-case proper. We should examine the 


FERNS. f59 


structure of this spore-case quite carefully, since it will help 
us to understand better than we otherwise could the remarkable 
operations which it performs in scattering the spores. 

263. Structure of a sporangium.—lIf we examine one of the 
sporangia in side vicw as shown in fig. 137, we note a promi- 
nent row of cells which extend around the margin of the dorsal 
edge from near the attachment of the stalk to the upper front 
angle. The cells are prominent because of the thick inner 
walls, and the thick radial walls which are perpendicular to the 
inner walls. The walls on the back of this row and on its sides 
are very thin and membranous. We should make this one 


Fig. 133. 
Rhizome of sensitive fern (Onoclea sensibilis\. 


carefully, for the structure of these cells is especially adapted to 
a special function which they perform. This row of cells is 
termed the annulus, which means a little ring. While this is 
not a complete ring, in some other ferns the ring is nearly com- 
plete. 

264. The lip cells.—In the front of the sporangium is another 
peculiar group of cells. Two of the longer ones resemble the 
lips of some creature, and since the sporangium opens between 
them they are sometimes termed the lip cells. These lip cells 


160 BOTANY. 


are connected with the upper end of the annulus on one side and 
with the upper end of the stalk on the other side by thin-walleq 
cells, which may be termed connec- 
tive cells, since they hold each lip cell 
to its part of the opening sporangium. 
The cells on the side of the sporangium 
are also thin-walled. If we now ex- 
amine a sporangium from the back, 
or dorsal edge as we say, it will appear 
as in the left-hand figure. Here we 
can see how very prominent the annu- 

Gane Shack ume ores lus is. It projects beyond the surface of 
dium Spinuiosam showing fruit the other cells of the sporangium. The 

spores are contained inside this case. 

265. Opening of the sporangium and dispersion of the 

spores.—If we take some fresh fruiting leaves of the Christmas 


Fig. 135. 
Four pinnze of adiantum, showing recurved margins which cover the sporangia. 


fern, or of any one of many of the species of the true ferns just at 
the ripening of the spores, and place a portion of a leaf on a piece 
of white paper in a dry room, in a very short time we shall see 
that the paper is being dusted with minute brown objects which 
fly out from the leaf. Now if we take a portion of the same 


FERNS. 161 


leaf and place it under the 1ow power of the microscope, so 
that the full rounded sporangia can be seen, in a short time we 
note that the sporangium opens, the upper half curls backward 
as shown in fig. 138, and soon it snaps quickly, to near its 
former position, and the spores are at the same time thrown for 
a. considerable distance. This movement can sometimes be 
seen with the aid of a good hand lens. 

266. How does this opening and snapping of the sporan- 
gium take place?—We are now more curious than ever to see 
just how this opening and 
how the snapping of the 
sporangium takes place. 
We should now mount 
some of the fresh sporangia 
in water and cover with a 
cover glass for microscopic 
examination. A drop of 
glycerine should be placed 
it one side of the cover 
glass on the slip so that 
the edge of the glycerine 
will come in touch with 
the water. Now as one 
looks through the micro- 
scope to watch the sporan- 
gia, the water should be 
drawn from under the cover 
glass with the aid of some 


bibulous paper, like filter Fig. 136. 

paper, placed at the edge Seiten ,fprough sores of Polypodium, vulgare 
of the cover glass on the multicellular capitate air, 

opposite side from the glycerine. As the glycerine takes the place 
of the water around the sporangia it draws the water out of the 
cells of the annulus, just as it took the water out of the cells of 


the spirogyra as we learned some time ago. As the water is 


162 BOTANY. 


drawn out of these cells there is produced a pressure from with- 
out, the atmospheric pressure upon the glycerine. This causes 
the walls of these cells of the annulus to bend inward, because, 
as we have already learned, the glycerine does not pass through 
the walls nearly so fast as the water comes out. 

267. Working of the annulus.—Now the structure of the cells 
of this annulus, as we have seen, is such that the inner walls and 
the perpendicular walls are stout, and consequently they do not 


Fig. 137. 
Rear, side, and front views of fern sporangium, d, ¢, annulus; a, lip cells, 


bend or collapse when this pressure is brought to bear on the out- 
side of the cells. The thin membranous walls on the back (dorsal 
walls) and on the sides of the annulus, however, yield readily to 
the pressure and bend inward. This, as we can readily see, pulls 
on the ends of each of the perpendicular walls, drawing them 
closer together. This shortens the outer surface of the annulus 
and causes it to first assume a nearly straight position, then curve 
backward until it quite or nearly becomes doubled on itse 


FERNS. 163 


The sporangium opens between the lip cells on the front, and the 
lateral walls of the sporangium are torn directly across. The 
greater mass of spores are thus held in the upper end of the 
open sporangium, and when the annulus has nearly doubled on 
itself it suddenly snaps back again in position. While treating 


a 


Fig. 138. 
Dispersion of spores from sporangium of Aspidium acrostichoides, showing different 
stages in the opening and snapping of the annulus. 


with the glycerine we can see all this movement take place. 
Each cell of the annulus acts independently, but often they all 
act in concert. When they do not all act in concert, some of 
them snap sooner than others, and this causes the annulus to 
"=" segments, - 42 $8 


164 BOTANY. 


268. The movements of the sporangium can take place in 
old and dried material._—lIf we have no fresh material to study 
the sporangium with, we can use dried material, for the move- 
ments of the sporangia can be well seen in dried material, pro- 
vided it was collected at about the time the sporangia are 
mature, that is at maturity, or soon afterward. We take some 
of the dry sporangia (or we may wash the glycerine off those 
which we have just studied) and mount them in water, and 
quickly examine them with a microscope. We notice that in 
each cell of the annulus there is a small sphere of some gas. 
The water which bathes the walls of the annulus is absorbed by 
some substance inside these cells. This we can see because of 
the fact that this sphere of gas becomes smaller and smaller 
until it is only a mere dot, when it disappears in a twinkling. 
The water has been taken in under such pressure that it has 
absorbed all the gas, and the farther pressure in most cases 
closes the partly opened sporangium more completely. 

269, The annulus can snap several times.— Now we should 
add glycerine again and draw out the water, watching the 
sporangia at the same time. We see that the sporangia which 
have opened and snapped once will do it again. And so they 
may be made to go through this operation several times in suc- 
cession. We should now note carefully the annulus, that is, 
after the sporangia have opened by the use of glycerine. So 
soon as they have snapped in the glycerine we can see those 
minute spheres of gas again, and since there was no air on the 
outside of the sporangia, but only glycerine, this gas must, it 
is reasoned, have been given up by the water before it was all 
drawn out of the cells. 

This movement of the annulus is a very effective provision 
for the mechanical distribution of the spores of ferns. The 
successive periods of wet and dry weather, or of damp or dry 
air, when the sporangia are mature serves to open the sporan- 
gium successively so that all the spores are scattered. This 
opening and closing probably goes on for a considerable time 


FERNS. 165 


after the dispersal of the spores; for material which has been 
dried for nearly twenty years has been used to show the 
snapping of the sporangium. The sporangia which remain on 
the leaves out-doors snap so often with the changes of the 
weather that the annulus is literally worn out. 


Synopsis. 
( Root. 
Stem. 
Petiole. 
Sterile leaves. 
Fern plant. < Lamina. 
Leaf. 4 
Petiole. 
Fertile leaves, i.e., 
spore-bearing Fruit dots (sorus). 
leaves. Indusium when 
L L Lamina. present. 
Sporangium. 
Spores. 


Material and apparatus.—Entire plants with the root stock, and some of 
the leaves with the fruit dots, may be preserved dry. 

Portions of the leaves with the fruit dots, at the time the spores have just 
matured, but have not opened, may be preserved in 2% formalin. If possi- 
ble, for the study of the opening of the sporangia obtain fresh material of 
the mature sporangia. They may often be obtained from greenhouses, and 
the leaf with the fruit dots before the sporangia have opened should be im- 
mersed in water as they are taken to the laboratory or in a very damp moist 
chamber, since the dry air of the room soon causes them to open and scatter 
the spores. 

Apparatus, the same as in Chapter XXIV. 

Glycerine. 


CHAPTER XXVII. 
FERNS—CoNcCLUDED. 


Tue SExuaL STAGE OF FERNS. 


270. THis CHAPTER IS LARGELY FOR READING AND FOR REFER- 
ENCE, though the teacher should endeavor to give demonstra- 
tions of the sexual organs, in their position on the under side 
of the prothallium, and also sections to show the structure. 
Prepared slides may be purchased for the purpose if it is not 
possible to obtain the material for making them. Prothallia 
may be grown by sowing the spores of ferns collected during the 
summer and saved in paper bags. If possible, a gardener in a 
greenhouse where ferns are grown should be consulted. Where 
they cannot be grown, it may be possible to purchase the pro- 
thallia also for study. When these can be obtained the student 
should make as careful an examination of the prothallium as 
possible before they are examined under the microscope. 


Exercise 54. 


271. Prothallium.—Note the small size of the prothallium, its form, 
color, delicate texture. Upon the under side observe the rhizoids. At 
which end of the prothallium are the rhizoids attached? With the aid of a 
hand lens can you see any other projections from the under side of the pro- 
thallium? Where are they located? Sketch a prothallium showing the 
under side and all the parts that can be seen with the aid of a hand lens, 


Demonstration 89. 


272. To show the sexual organs attached to the under surface of the 
prothallium. Mount a prothallium with the under side uppermost in water 
on a glass slip, and prepare for examination with the microscope. Study 
with the low power of the microscope. Near the sinus of the. heart-shaped 


FERNS. 167 


prothallium look for conic projections, the archegonia (see fig. 139) ; among 
the rhizoids look for smaller but more numerous, rounded projections, the 
antheridia. Compare the prothallium with the thallus of marchantia. 
Sketch a prothallium under the low power of the microscope if there is time. 
Among the prothallia search for some showing the young fern plant. 


Demonstration 40. 


273. To show the structure of the sexual organs of ferns. Make thin 
sections lengthwise of the prothallium along the middle line. These are 
best made in collodion or paraffin, and mounted in balsam. If the teacher 
has not the apparatus for making them, prepared slides may be purchased 
for the demonstration. Let the pupils sketch the structure of an antheridium 
and archegonium (see paragraphs 281 and 282), and name the parts. 

If there is time and material the teacher may demonstrate young pro- 
thallia soon after the germination of the spores. 


The following description of the sexual stage of ferns is for 
reading and study. 

For further studies on the gametophyte phase of ferns, see 
the author’s larger ‘‘ Elementary Botany,’’ Chapter XXVI. 

274, Sexual stage of ferns.—We now wish to see what the 
sexual stage of the ferns is like. Judging from what we have 
found to take place in the liverworts and mosses we would infer 
that the form of the plant which bears the sexual organs is 
developed from the spores. This is true, and if we should 
examine old decaying logs, or decaying wood in damp places in 
the near vicinity of ferns, we would probably find tiny, green, 
thin, heart-shaped growths, lying close to the substratum. 
These are also found quite frequently on the soil of pots in 
plant conservatories where ferns are grown. Gardeners also in 
conservatories usually sow fern spores to raise new fern plants, 
and usually one can find these heart-shaped growths on the sur- 
face ot the soil where they have sown the spores. We may call 
the gardener to our aid in finding them in conservatories, or 
even in growing them for us if we cannot find them outside. 
In some cases they may be grown in an ordinary room by keep- 
ing the surfaces where they are growing moist, and the air also 

- gist, by placing a glass bell jar over them. 


168 BOTANY. 


275. The prothallium.—In fig. 139 is shown one of these 
growths enlarged. Upon the under side we see numerous 
thread-like outgrowths, the rhizoids, which attach the plant to 
the substratum, and which act as organs for the absorption of 
nourishment. The sexual organs are borne on the under side 
also. This heart-shaped, flattened, thin, green plant is the 


CO 


A 
Nips 


i 


WAS 


re 


Sana 


Ns 
Raga 
mat ARS 


Prothallium of fern, under side, dieiiee woes, antheridia scattered among and near 
them, and the archegonia near the sinus. 

prothalium of ferns, and we should now give it more careful 

study, beginning with the germination of the spores. 

276. Spores.—We can easily obtain material for the study of 
the spores of ferns. The spores vary in shape to some extent. 
Many of them are shaped like a three-sided pyramid. One of 
these is shown in fig. 140. The outer wall is roughened, and 
on one end are three elevated ridges which radiate from a given 
point. A spore of the Christmas fern is shown in fig. 141. 
The outer wall here is more or less winged. 


FERNS. 169 


277.. Germination of the Spores.—After the spores have been 
sown for about one week to ten days we should mount a few in 
water for examination with the microscope in order to study the 
early stages. If germination has begun, we find that here and 
there ‘are short slender green threads, in 
many cases attached to brownish bits, the 
old walls of the spores. Often one will sow 
the sporangia along with the spores, and 
in such cases there may be found a number 
of spores still within the old sporangium 
wall that are germinating, when they will 
appear as in fig. 142. Bisse. 

278. Protonema., — These short green , Spore of Pteris serru- 


lata showing the three- 


threads are called srofonemal threads, or ‘ayed elevation along the 
‘side of which the spore 


protonema, which means a Jirst thread, and oe during germi- 
it here signifies that this short thread only’ 
precedes a larger growth of the same object. In figs. 142, 143 
are shown several stages of germination of different spores. 
Soon after the short germ tube emerges from the crack in the 
spore wall, it divides by the formation of a cross-wall, and as it 
increases in length other cross-walls are formed. 
But very early in its growth we see that a slender 
outgrowth takes place from the cell nearest the 
old spore wall. This slender thread is colorless, 
and is not divided into cells. It is the first rhiz- 
oid, and serves both as an organ of attachment 
for the thread, and for taking up nutriment. 
279. Growth of the prothallium.—Very soon, 


Fig. 141. : : 
Sones ok Aap if the sowing has not been so crowded as to 


um, acrostichoides prevent the young plants from obtaining nutri- 


ospore, 


ment sufficient, we will see that the end of this 
protonema is broadening, as shown in fig. 143. This is done 
by the formation of the cell walls in different directions. It 
now continues to grow in this way, the end becoming broader 
and broader, and new rhizoids are formed from the under surface 


170 BOTANY. 


of the cells. The growing point remains at the middle of the 
advancing margin, and the cells which are cut off from either 
side, as they become old, widen out. 
In this way the ‘‘ wings,’’ or margins 
of the little, green, flattened body, are 


Fig. 142. Fig. 143. 
Germinating spores of Young prothallium of a fern (nipho- 
Pteris aquilina still in the bolus). 
sporangium, 


in advance of the growing point, and the object is more or less 
heart-shaped, as shown in fig. 139. Thus we see how the 
prothallium of ferns is formed. 

280. Sexual organs of ferns.—I{ we take one of the prothallia 
of ferns which have grown from the sowings of fern spores, or 
one of those which may be often found growing on the soil of 
pots in conservatories, mount it in water on a slip, with the 


FERNS. 171 


under side uppermost, we can then examine it for the sexual 
organs, for these are borne in most cases on the under side. 


Fig. 144. Fig. 145. 


Section of antheridia showing sperm cells, and spermato- Different views of spermatozoids; 
zoids in the one at the right. in a quiet condition; in motion 


(Adiantum concinnum). 


281. Antheridia.—If we search among the rhizoids we see 
small rounded elevations as shown in figure 139 scattered 
over this portion of the prothallium. These are the antheridia. 
If the prothallia have not been watered for a day or so, we may 
have an opportunity of seeing 
the spermatozoids coming out 
of the antheridium, for when 
the prothallia are freshly placed 
in water the cells of the antheri- 
dium absorb water. This presses 
on the contents of the antheri- 
dium and bursts the cap cell if 
the antheridium is ripe, and all 
the spermatozoids are shot out. 
We can see here that each one 
is shaped like a screw, with the 
coils at first closed. But as the Archegonium oe. Large cell in 
spermatozoid begins to move ‘hs yentr is th ogg mons vont 
this coil opens somewhat and are two nuclei of the canal cell. 
by the vibration of the long cilia which are on the smaller end it 
whirls away. In such preparations one may often see them 
spinning around for a long while, and it is only when they 
gradually come to rest that one can make out their form. 


172 BOTANY. 


282. Archegonia.—If we now examine closely, on the thicker 
part of the under surface of the prothallium, just back of the 


Fig. 147. 
Mature and open archegonium of fern (Adiantum cuneatum) with spermatozoids making 
their way down through the slime to the egg. 


‘*sinus,’’ we may see longer 
stout projections from the sur- 
face of the prothallium. These 
are shown in fig. 139. They are 
the archegonia. One of them 
in longisection is shown in fig. 
146. Itisflask- 
shaped, and 
the _ broader 
portion is sunk 
in the tissue of 
the prothal- 
lium. The egg 


is in the larger Fig. 148. Fig. 149. 
Fertilization in a fern Young plant of Pteris serrulata still 
part. The aie Sp, jppermate: attached to prothallium, 
‘ 5 zoid fusing with the nu- 
sper matozoids cleus of the egg. (After 


when they are Campbell.) 


swimming around over the under surface of the prothallium 


FERNS. 173 


come near the neck, and here they are caught in the viscid 
substance which has oozed out of the canal of the archegonium. 
From here they slowly swim down the canal, and finally one 
sinks into the egg, fuses with the nucleus of the latter, and the 
egg is then fertilized. It is now ready to grow and develop into 
the fern plant. This brings us back to the sporophyte, which 
begins with the fertilized egg. 


Synopsis. 
Flattened, green, heart-shaped growth, with rhizoids 

Sexual stage. underneath, 
Prothallium. Sexual organs, under side of prothallium. 
(Corresponds tothe wes Wall. 

vegetative part patter him, | Spermatozoids. 

of the liverwort aaa 

d : Buchgeninne | sae 
and moss.) Egg. 


Material and apparatus.—Prothallia of ferns, entire ; they are often found 
growing in soil of pots in greenhouses where ferns are grown. Or they 
may be grown by sowing the spores. : 

For demonstrations of the structure of the sexual organs the teacher can 
make sections, or permanent ones may be obtained from supply companies. 

Apparatus, same as in Chapter XXIV. 


CHAPTER XXVIII. 


HORSETAILS (EQUISETINE/). 
(The field equisetum.) 


283. Equisetum is related to the ferns.—Among the rela- 
tives of the ferns are the horsetails, so called because of the 
supposed resemblance of the branched stems of some of the 
species to a horse’s tail, as one might infer from the plant 
shown in fig. 154. They do not bear the least resemblance to 
the ferns which we have been studying. But then relationship 
in plants does not depend on mere resemblance of outward form, 
or of the prominent part of the plant. 

The field equisetum (Equisetum arvense) is a good one to 
study. If desired another one may be used for comparison, the 
scouring rush, or shave grass (E. hyemale). 


Exercise 55. 
Tue Fretp EquiseTum. 


284. Fertile shoots.—The material should show the underground stem. 
Note the underground stem, its branching, color ; the connection of the up- 
right fertile shoot with it. Note the roots. What is the color of the fertile 
shoot? Is there much chlorophyll ? 

Observe the nodes (joints) of the stem, the membranous crown (leaves) 
around each node, the character of the margin of this crown. Study the 
internodes, note the marking into ridges and furrows. What is the relation 
of the ridges and furrows of one node with those of each adjacent node? 
What is the relation of the points of the leaves with the ridges? Sketch a 
fertile shoot. 

285. The fruiting spike.—The fruiting spike at the end of the shoot. 
Observe the numerous disks which are also arranged in whorls. Tease off 


174 


HORSETAILS. 175 


some of these from the shoot. Note the short stalk ; how is this stalk at- 
tached? Describe the sacs underneath. (These are the spore-cases.) 

Sketch a spore-bearing leaf. 

If some of the spores are at hand which fall out of the spore-cases when 
the sporangia dry, examine them under a hand lens; at the same time 
breathe upon them. What happens? 

286. The sterile shoot —Compare the sterile shoots with the fertile shoots. 
Note the leaves arranged in the same way, but smaller. Note the branch- 
ing of the plant and the arrangement of the branches. Are there leaves on 
the branches? Describe them. Sketch a sterile shoot. What is the color 
of the sterile shoot? In what part of the plant does the chlorophyll lie ? 
In what part of the plant does the process of starch formation (or photo- 
synthesis) take place ? 

Compare the scouring rush (E. hyemale) if there is time. 


Demonstration 41. 


287. Spores and elaters.—Mount some of the spores of equisetum on a 
dry glass slip. Let each pupil examine them under the microscope, sketch 
and describe the form ; breathe lightly on them and watch the result. 


288. The field equisetum. Fertile shoots.—Fig. 150 repre- 
sents the common horsetail (Equisetum arvense). It grows in 
moist sandy or gravelly places, and the fruiting portion of the 
plant (for this species is dimorphic), that is the portion which 
bears the spores, appears above the ground early in the spring. 
It is one of the first things to peep out of the recently frozen 
ground. This fertile shoot of the plant does not form its 
growth this early in the spring. Its development takes place 
under the ground in the autumn, so that with the advent of 
spring it pushes up without delay. This shoot is from 10 to 
20 cm. high, and at quite regular intervals there are slight 
enlargements, the nodes of the stem. The cylindrical portions 
between the nodes are the internodes. If we examine the region 
of the internodes carefully we note that there are thin mem- 
branous scales, more or less triangular in outline, and connected 
at their bases into a ring around the stem. Curious as it may 
seem, these are the leaves of the horsetail. The stem, if we 
examine it further, will be seen to possess numerous ridges 


176 BOTANY. 


which extend lengthwise and which alternate with furrows. 
Further, the ridges of one node alternate with those of the 
internode both above and below. Likewise the leaves 
of one node alternate with those of the nodes both 
above and below. 

289. Sporangia.—The end of this fertile shoot we 
see possesses a cylindrical to conic enlargement. This 
is the /ertle spike, and we note that its surface is 
marked off into regular areas if the spores have not 
yet been disseminated. If we dissect off a few of 
these portions of the fertile spike, and examine one 
of them with a low magnifying power, it will appear 
like the fig. 151. We see here that the angular area 
is a disk-shaped body, with a stalk attached to its 
inner surface, and with several long sacs projecting” 
from its inner face parallel with the stalk and surround- 
ing thesame. These elongated sacs are 
the sporangia, and the disk which bears 
them, together with the stalk which at- 
taches it to the stem axis, is the sporo- 
PAyil, and thus belongs to the leaf series. 
These sporophylls are borne in close 
whorls on the axis. 

290. Spores.—When the spores are Hig. apr 


Peltate sporo- 


ripe the tissue of the sporangium be- phyll of equise- 
tum (side view) 


comes dry, and it cracks open and the showing sporan- 
gia on under side. 


spores fall out. In fig. 152 we see that 
the spore is covered with a very singular coil which 


fertile plant lies close to the wall. When the spore dries this un- 
of Equise- 


tum arvense, coils and thusrolls the spore about. Merely breathing 


showing § i‘ 

eee upon these Bpetes is sufficient to make them perform 

ei very curious evolutions by the twisting of these four 
coils which are attached to one place of the wall. 

They are formed by the splitting up of an outer wall of the 


spore. 


Fig. 150. 
Portion of 


HORSETAILS. 177 


291. Sterile shoot of the common horsetail.When the 
spores are ripe they are soon scattered, and then the fertile 


Fig. 152. 
Spore of equisetum Spore of equisetum with elaters un- 
with elaters coiled up. coiled. 


shoot dies down. Soon afterward, or even 
while some of the fertile shoots are still in 
good condition, sterile shoots of the plant 
begin to appear above the ground. One of 
these is shown in fig. 154. This has a 
much more slender stem and is provided 
with numerous branches. If we examine 
the stem of this shoot, and of the branches, 
we shall see that the same kind of leaves are 
present and that the markings on the stem 
are similar. Since the leaves of the horsetail 
are membranous and not green, the stem 
is green in color, and here the process of 
starch formation goes on. These green 
shoots live for a great part of the season, 
building up material which is carried down 
into the underground stems, where it goes 
to supply the forming fertile shoots in the 
fall. On digging up some of these plants 
we see that the underground stems are often 
of great extent, and that both fertile and 
sterile shoots: are attached to one 
and the same. 

292. The scouring rush, or shave 
grass.—Another common species of Fig. 154. 


eo, : Sterile plant of horsetail (Equi- 
horsetail in the Northern States grows setum arvense). 


178 BOTANY. 


on wet banks, or in sandy soil which contains moisture along 
railroad embankments. Itis the scouring rush (E. hyemale), so 
called because it was once used for polishing purposes. This 
plant like all the species of the horsetails has underground stems. 
But unlike the common horsetail, there is but one kind of aerial 
shoot, which is green in color and fertile. The shoots range as 
high as one meter or more, and are quite stout. The new 
shoots which come up for the year are unbranched, and bear 
the fertile spike at the apex. When the spores are ripe the 
apex of the shoot dies, and the next season small branches may 
form from a number of the nodes. 

293. Gametophyte of equisetum.—The spores of equisetum 
have chlorophyll when they are mature, and they are capable 
of germinating as soon as mature. ‘The spores are all of the 
same kind as regards size, just as we found in the case of the 
ferns. But they develop prothallia of different sizes, according 
to the amount of nutriment which they obtain. Those which 
obtain but little nutriment are smaller and develop only 
antheridia, while those which obtain more nutriment become 
larger, more or less branched, and develop archegonia. This 
character of an independent prothallium (gametophyte) with 
the characteristic sexual organs, and the also independent 
sporophyte, with spores, shows the relationship of the horsetails 
with the ferns. We thus see that these characters of the repro- 
ductive organs, and the phases and fruiting of the plant, are 
more essential in determining relationships of plants than the 
mere outward appearances. 


t 
C 


Synopsis, 


The field 
equisetum. 


Root. 


Shoot. 


( Underground stem cr rhizome. 


HORSETAILS. 179 


’ 


Sterile shoot (branched, green, later than the fertile 
shoot). 
Fertile shoot (early in the spring). 
Stem with nodes and internodes, crown of mem- 
branous pointed leaves at the nodes. 
Fruiting spike. 
Whorls of peltate spore-bearing leaves. 
Several sporangia on inner side of the 
sporophylls. 
Sporangium contains 
Spores each with four elaters. 


(The prothallium is not described here.) 


Material and apparatus.—Entire plants including the underground root 
stock may be preserved dry. The fertile shoots appear earlier, and should 
be collected just as they are appearing from the ground ; the sterile shoots 
should be collected later when they are well formed. 

Apparatus, the same as in Chapter XXIV. 


CHAPTER XXIX. 
QUILLWORTS (ISOETES). 


Exercise 56. 


294. The isoetes plant.—Sketch an entire plant. Only the leaves (resem- 
bling ‘ quills’) and the roots can be seen. Note the relation of the leaves, 
how they overlap. Remove a few. Describe and sketch the form. Note 
the thickened base, its shape like a spoon. 

Upon the inner side of the thickened base note the circular depression of 
a different texture. This is the spore-case. Note the thin overlapping 
membrane around the edge of the spore-case. Just above the sporangium 
note the small appendage. Observe the thin outer wall of the spore-case ; 
that through this in many cases the large spores can be seen in many of 
the spore-cases, especially the outer ones.. 

Section a plant longitudinally, or examine one that has been split into 
halves longitudinally, in order to see the attachment of the leaves, and to 
see the short stem. Note here also the spores in the spore-cases ; also the 
cross-strands of tissue dividing the spore-cases into chambers. 

Tease open several of the sporangia to expose the spores. Note the large 
spores in some ; the small spores in others. 


Demonstration 42. 


295. Two kinds of spores.—Spores of each kind may be mounted in water 
for demonstration. Let each pupil sketch and describe one of each kind. 
It is an important thing for the student to know one of the fern-like plants 
which bear the two kinds of spores, as it helps one to understand the two 
different kinds of spores in the pines and flowering plants. 


296. Habit of isoetes.—The quillworts, as they are popularly 
called, are very curious plants. They grow in wet marshy places. 
They receive their name from the supposed resemblance of the 

180 


QUILLWORTS. 181 


leaf to a quill. Fig. 155 represents one of these quillworts 
(Isoetes engelmannii). The leaves are the prominent part of the 
plant, and they are about all that can be seen except the roots, 
without removing the leaves. 

Each leaf, it will be seen, is long 

and needle-like, except the basal 

part, which is expanded, not very 

unlike, in outline, a scale of an \ / 

onion. These expanded basal 
portions of the leaves closely 
overlap each other, and the very 
short stem is completely covered 
at all times. Fig. 157 is from 
a longitudinal section of a quill- 
wort. It shows the form of the 
leaves from this view (side view), 
and also the general outline 
of the short stem, which is tri- 
angular. The stem is therefore 
a very short object. 

297. Sporangia of isoetes.— 
If we pull off some of the leaves 
of the plant we see that they are 
somewhat spoon-shaped as in 
fig. 156. In the inner surface 
of the expanded base we note a 
circular depression which seems 
to be of a different texture from 
the other portions of the leaf. 


4 
This is a sporangium. Beside J, NN 
: . TAN 
the spores on the inside of the as 
sporangium, there are strands of Fig. 155. 


. s 3 Isoetes, mature plant. 
sterile tissue which extend across : P 


the cavity. This is peculiar to isoetes of all the members of 
the class of plants to which the ferns belong, but it will be re- 


182 BOTANY. 


membered that sterile strands of tissue are found in some of 
the liverworts in the form of elaters. 

298. Microspores and macrospores.—The spores of isoetes are 
of two kinds, small ones (microspores) and large ones (macro- 
spores). When one kind of spore is borne in a sporangium 
usually all in that sporangium are of the same kind, so that certain 
sporangia bear microspores, and others bear macrospores. But 


Fig. 156. Fig. 157. 


Base of leaf of isoetes, Section of plant of Isoetes engelmanii, showing 
showing sporangium with cup-shaped stem, and longitudinal sections of the 
macrospores. (Isoetes en- sporangia in the thickened bases of the leaves. 
gelmannii). 


it is not uncommon to find both kinds in the same sporangium. 
When a sporangium bears only microspores the number is much 
greater than when one bears only macrospores. 

For a discussion of the club mosses (lycopodium and selagi- 
nella) and for a comparison of the ferns and fern-like plants, 
see the author’s larger ‘‘ Elementary Botany,’’ Chapters XXVIII 
and XXX. 


QUILLWORTS. 183 


Synopsis. 
{ Root. 


Quillwort 


(Isoetes). 4 Short stem. 


Leaves long, quill-like. 
Sporangium in base of each leaf. 
Sonie sporangia with small spores. 
L Some sporangia with large spores. 


(The prothallium is not described here.) 


Material.—Entire plants, some dried, and others preserved in alcohol. 


CHAPTER XXX. 
GYMNOSPERMS. 


THe Wuirte PINE. 


Exercise 57. 


299. The long shoots of the pine.—Take a branch which shows the long 
shoots, and several whorls of branches. Note the terminal shoot ; if in early 
summer observe the scale-like leaves borne on the long shoots. Note that 
the branches belong to the long shoots, and that they are arranged in a whorl 
at the end of each year’s growth. (This whorl is a false one.) 

800. The short branches.—On the long shoots note the short branches 
ending in a tuft of long green needle-like leaves. Note the short brownish 
scale-like leaves on the short shoots below where the needles are attached. 
In early spring if there are any pines in the vicinity note the growth of the 
long shoots, and the colorless scale leaves on them, and the appearance of the 
new green leaves on the new short shoots. How long do the green leaves 
remain on a pine ? 


Exercise 58. 


301. Mature cones.—Note the form of the cone, the scales spread apart 
when dry. (Before the seeds are ripe the scales closely overlap.) Note the 
arrangement of the scales in spirals. Remove a few scales. Note the seeds 
attached to the inner lower end of the scale, unless they have split off. 

Sketch the form of a scale showing the seeds attached. Sketch a detached 
seed, showing the wing-like appendage which splits off from the inner 
part of the scale. 

302. Young female cones.—Note the small size as compared with the 
mature cones. Observe that the scales have the same arrangement as in the 
mature cones. Sketch one. If you have an opportunity to see the young 
cones on the tree just at the time of pollination, make a note of their posi- 
tion, and the position of the scales. Some time after pollination note the 
position of the cones, say any time during the summer, and the position of 

184 


GYMNOSPERMS. 185 


the scales. Why are the cones and scales in these different positions at these 
different times ? : 

Remove several scales and study them carefully. Sketch the form of one 
showing both sides. Upon the outer side note a small appendage (cover 
scale ; if there are spruces at hand compare the difference in size of the 
cover scale of the pine and spruce). 

Upon the inner side note the two oval bodies at the two lower angles. 
These are the ovwdes, and correspond to the large sporangia. Note care- 
fully a forceps-like appendage at the lower end of each ovule ; a little de- 
pression between them. This is the place where the pollen is drawn up 
after pollination. 

Observe that the seeds are developed at this same point on the scale, and 
that the seed is formed from a later growth of the ovule and its parts. 

Observe also that the ovules and seeds of the pine are naked, that is, they 
are exposed. From this character the name of the gymnosperms, or naked 
seed plants, is derived. 


Exercise 59. 


303. The male cones.— Observe the large clusters of the male flowers, sev- 
eralcones collected together. Sketch a cluster. Sketch a separate cone. Note 
that the cone is made up of an axis and scales as in the female cone, but the 
scales are different in form, Remove several of the scales. Note the form. 

Upon the under side note the two strong convexities. Cut across scale, 
and note that there are two sacs situated here. These sacs are the spore- 
cases (small sporangia). The fine granules which escape are the small 
spores, or pollen. 

If you have an opportunity when the pollen is ripe on a pine tree, jar the 
tree to see the clouds of pollen ‘‘dust’’ escape. When the sacs on the under 
side of the scale open in drying, note the position of the slit. Sketch such 
an open scale. 


Demonstration 483. 


304. Pollen grains,—Mount a few of the pollen grains in water for exam- 
ination with the microscope. Let each pupil observe, and sketch a pollen 
grain. Observe the two large air sacs on either side of the pollen grain. Of 
what use are these air sacs to the pollen? Do insects pollinate the pines, or 
are they wind pollinated? 

If it is desired to demonstrate the prothallium, archegonia, and fertilization 
in the pine, the teacher can either prepare or purchase slides for the pur- 
pose. See the author’s larger ‘Elementary Botany,” Chapters XXI and 
XXII, for further studies of the gymnosperms, and for fertilization, etc. 


186 BOYANY. 


305. General aspect of the white pine——The white pine 
(Pinus strobus) is found in the Eastern United States. In 
favorable situations in the forest it reaches a height of about 5c 
meters (about 160 feet), and the trunk a diameter of over 
1 meter. In well-formed trees the trunk is straight and tower- 
ing; the branches where the sunlight has access and the trees 
are not crowded, or are young, reaching out in graceful arms, 
form a pyramidal outline to the tree. In old and dense forests 
the lower branches, because of lack of sunlight, have died away, 
leaving tall, bare trunks for a considerable height. 

306. The long shoots of the pine.—The branches are of two 
kinds. Those which we readily recognize are the long 
branches, so called because the growth in length each year is 
considerable. The terminal bud of the long branches, as well 
as of the main stem, continues each year the growth of the 
main branch or shoot; while the lateral long branches arise 
each year from buds which are crowded close together around 
the base of the terminal bud. The lateral long branches of each 
year thus appear to be in a whorl. The distance between each 
false whorl of branches, then, represents one year’s growth in 
length of the main stem or long branch. 

307. The dwarf shoots of the pine.—The dwarf branches are 
all lateral on the long branches, or shoots. They are scattered 
over the year’s growth, and each bears a cluster of five long, 
needle-shaped, green leaves, which remain on the tree for 
several years. At the base of the green leaves are a number of 
chaff-like scales, the previous bud scales. While the dwarf 
branches thus bear green leaves, and scales, the long branches 
bear only thin scale-like leaves which are not green. 

308. Spore-bearing leaves of the pine.—The two kinds of 
spore-bearing leaves of the pine, and their close relatives, are so 
different from anything which we have yet studied, and are so 
unlike the green leaves of the pine, that we would scarcely 
recognize them as belonging to this category. Indeed there is 
great uncertainty regarding their origin. 


GYMNOSPERMS. 187 


309. Male cones, or male flowers.—The male cones are borne 
in clusters as shown in fig. 158. Each compact, nearly cylin- 
drical, or conical mass is termed a cone, or flower, and each 
arises in place of a long lateral branch. One of these cones is 


Is \ 4 Oa | omen 


Spray of white pine showing cluster of ed just before the scattering of the pollen. 
shown considerably enlarged in fig. 159. The central axis of 
each cone is a lateral branch, and belongs to the stem series. 
The stem axis of the cone can be seen in fig. 160. It is com- 
pletely covered by stout, thick, scale-like outgrowths. These 
scales are obovate in outline, and at the inner angle of the 


188 BOTANY. 


upper end there are several rough, short spines. They are 
attached by their inner lower angle, which forms a short stalk 


bi NUL 


Fig. 3159. Fig. 160, Fig. 161. 
Staminate cone of white Section of staminate Two sporo- 
pine, with bud scales re- cone showing sporangia. phylls removed, 
moved on one side. showing open- 


ing of sporangia. 


or petiole, and continues through the inner face of the scale as 
a ‘‘ midrib.’’ What corresponds to the lamina of the scale-like 
leaf bulges out on each side below and makes the bulk of the 
scale. These prominences on the under side are the sporangia 
(micro-sporangia). There are thus two sporangia on a sporo- 
phyll (micro-sporophyll). When the spores (microspores), 
which here are usually called pollen grains, are mature each 
sporangium, or anther locule, splits down the 
middle as shown in fig. 161, and the spores are 
set free. 

310. Microspores of the pine, or pollen 


Fig. 162. ‘ : 5. ‘ 
Pollen grain of gYains.—A mature pollen grain of the pine is 


white pine. shown in fig. 162. It is a queer-looking 


object, possessing on two sides an air sac, formed by the 
upheaval of the outer coat of the spore at these two points. 
When the pollen is mature, the moisture dries out of the scale 
(or stamen, as it is often called here) while it ripens. When a 
limb, bearing a cluster of male cones, is jarred by the hand, or 


GYMNOSPERMS, 189 


by currents of air, the split suddenly opens, and a cloud of 

pollen bursts out from the numerous anther \ 

locules. The pollen is thus borne on the YI 
\ 


wind and some of it falls on the female 
flowers. 

311. Form of the mature female cone.— 
A cluster of the white-pine cones is 
shown in fig. 163. These are 

y, mature, and 
the scales have 


Fig. 163. 

White pine, branch with cluster of 
mature cones shedding theseed. A 
few young cones four months old 
are shown on branch at the left. 
Drawn from photograph. 


spread as they do when 
mature and becoming 
dry, in order that the 
Mature cone of white pine : m seeds may be set at 
at time of scattering of the \ We 
seed, nearly natural size. NY’ Ns liberty. The general 
outline of the cone is lanceolate, or long oval, and somewhat 
curved. It measures about 10-15 em long. If we remove one 


190 BOTANY. 


of the scales, just as they are beginning to spread, or before the 


Fig. 165. Fig. 166. Fig. 167. Fig. 168. Fig. 169 


Sterile scale. Scale with Seeds have Back of scale Winged 
Seeds undevel- well-developed split off from with small cover seed free 
oped, seeds, scale. scale. from scale. 


Figures 165-149.—White pine showing details of mature scales and seed. 

seeds have scattered, we shall find the seeds attached to the 
upper surface at thelower end. There are two 
seeds on each scale, one at each lower angle. 
They are ovate in outline, and shaped some- 
what like a biconvex lens. At this time the 
seeds easily fall away, and may be freed by 
jarring the cone. As the seed is detached from 
the scale a strip of tissue from the latter is 
peeled off. This forms a ‘‘ wing’’ for the 
seed. It is attached to one end and is shaped 
something like a knife blade. On the back of 
the scale is a small appendage known as the 
cover scale. 

312. Formation of the female pine cone.— 
The female flowers begin their development 
rather late in the spring of the year. They 
are formed from terminal buds of the higher 
branches of the tree. In this way the cone may 
% terminate the main shoot of a branch, or of 

Hie sae: the lateral shoots in.a whorl. After growth 
Female cones of the has proceeded for some time in the spring, 


pine at time of pollina- 
tion, about natural size. the terminal portion begins to assume the ap- 


GYMNOSPERMS. Ig! 


pearance of a young female cone or flower. These young 
female cones, at about the time that the pollen is escaping 
from the anthers, are long ovate, measuring about 6-10 mm 
long. They stand upright as shown in fig. 170. 

313. Form of a “scale” of the female flower.—I{ we 
remove one of the scales from the cone at this stage we can 
better study it in detail. It is flattened, 
and oval in outline, with a stout ‘‘rib,’’ if 
it may be so called, running through the 
middle line and terminating in a point. 
The scale is in two parts as shown ‘in fig. 
173, which is a view of the under side. 
The small ‘‘ outgrowth ’’ which appears as 
an appendage is the cover scale, for while it 
is smaller in the pine than the other portion, 
in some of the relatives of the pine it is 
larger than its mate, and being on the out- 
side, covers it. (The inner scale is some- 
times called the ovuliferous scale, because 
it bears the ovules.) 

314. Ovules, or macrosporangia, of the 


Fig. 17x. Fig. 172. g ; 
Section of female cone Scale of white pine with the Scale of white pine seen 
of white pine, showing two ovules at base of ovulif- from the outside, showing the 
young ovules (macrospo- érous scale. cover scale. 
rangia) at base of the ovu- 
liferous scales. © 


pine.—At each of the lower angles of the scale is a curious oval 
body with two curved, forceps-like processes at the lower and 


192 BOTANY. 


smallerend. These are the macrosporangia, or, as they are called 
in the higher plants, the ovules. These ovules, as we see, are 
in the positions of the seeds on the mature cones. In fact the 
wall of the ovule forms the outer coat 
of the seed, as we will later see. 


& | 815. Pollination.—At the time when 
Y i i the pollen is mature the female cones 
‘ \ i are still erect on the branches, and the 
NY \ / scales, which during the earlier stages of 
NN \\\ Mi growth were closely pressed against one 


another around the axis, are 
i now spread apart. As the 


Branch of white pine showing young female cones at time of pollination on the ends of 
the branches, and one-year-old cones below, near the time of fertilization. 


clouds of pollen burst from the clusters of the male cones, 
some of it is wafted by the wind to the female cones. It is here 
caught in the open scales, and rolls down to their bases, where 
some of it falls between these forceps-like processes at the lower 
end of the ovule. At this time the ovule has exuded a drop of 


GYMNOSPERMS. 193 


a sticky fluid in this depression between the curved processes at 

its lower end. The pollen sticks to this, and later, as this viscid 

substance dries up, it pulls the pollen close up in the depression 

against the lower end of the ovule. This depression is thus 
: known as the pollen chamber. 

Now the open scales on the young female cone close up 
again, so tightly that water from rains is excluded. What is 
also very curious, the cones, which up to this time have been 
standing erect, so that the open scale could catch the pollen, 
now turn so that they hang downward. This more certainly 
excludes the rains, since the overlapping of the scales forms a 
shingled surface. Quantities of resin are also formed in the 
scales, which exudes and makes the cone practically impervious 
to water. 

The female cone now slowly grows during the summer 
and autumn, increasing but little in size during this time. 
During the winter it rests, that is, ceases to grow. With the 
coming of spring, growth commences again and at an accelerated 
rate. The increase in size is more rapid. The cone reaches 
maturity in September. We thus see that nearly eighteen 
months elapse from the beginning of the female flower to the 
maturity of the cone, and about fifteen months from the time 


that pollination takes place. 


Material.—Several branches of the pine showing the long shoots and 
whorls of branches. (These should be had in the laboratory if the tree can- 
not be studied in the open. If fresh branches cannot be had, preserve them 
dry.) 

Mature cones collected in August just before the seeds fall away. 
Branches with the female cones, collected from the top of the tree, in early 
summer (June), preserve in alcohol. 

Branches with the clusters of male cones collected late in May or early in 
June just before the pollen is scattered. Preserve in alcohol. 

Sections to show the female prothallium, archegonium, and fertilization 
can be made by the teacher, or they may be purchased of supply companies. 

Dissecting microscope, or tripod lens ; dissecting needles. 


~CHAPTER XXXI. 


MORPHOLOGY OF THE ANGIOSPERMS: TRILLIUM; 
DENTARIA. ° 


Exercise 6O. 


316. Trillium.—Note the general habit of the plant; the short, thick, 
underground stem, which is perennial; the roots attached to this; the 
scale leaves at the anterior end around the base of the flowering stem. Note 
the flowering stem ; the whorl of three green leaves on it, and the terminal 
flower. Observe that there are no roots attached to the flowering stem. Is 
the flowering stem perennial ? 


Exercise 61. 


817. Flower of trillium.—Observe the difference in the parts of the 
flower ; two whorls of leaf-like parts on the outside. Take these up in 
order, beginning at the outside. 

Outer whorl (calyx) ; note the resemblance of each member of the calyx 
to the leaf. How do they compare in number with the whorl of leaves on 
the stem? Sketch one. Each one is a sepal. 

318. Corol'a the second whorl.—Is there any resemblance between the 
parts of the corolla and a leaf of trillium? How do the parts compare as to 
form and number with the leaves? Sketch one. Each part of the corolla 
is a petal. 

319. Third and fourth whorl (andreecium).—Note here that there are six 
members composing these two whorls, three in each. Is there any resem- 
blance between these and the leaves? Did you ever see any of these mem- 
bers (stamens) partly changed to petals or leaves in trillium? Did you ever 
see any of them partly changed in other flowers? in the water lily for ex- 
ample. Examine,a water lily when you have an opportunity. Look for 
these changes in other plants when you have an opportunity. 

Sketch a stamen, and name the parts, the slender stalk (filament), the 
more expanded part (anther) with four long sacs (anther locules, or sacs) ; 


194 


ANGIOSPERMS. 195 


if they have just opened observe the great quantity of yellow ‘‘ dust.” 
These are the pollen grains, or the small spores. (The anther sacs then must 
be the small sporangia.) 

320. The inner whorl (gynecium).—Note that the structure in the centre 
of the trillium flower ends in three slender points; cut across the larger 
part of this object below. Note that it has three chambers. What does this 
suggest? What do you find attached to the inner walls of these chambers ? 
They are the ovules. Sketch a cross-section. Is there any relation be- 
tween the three parts of this structure (pistil) and leaves? What is this 
relation? Compare the mature fruit of trillium (if at hand) with the pistil 
and ovules, 


DescripTIon oF TRILLIUM. 


321. General appearance.—As one of the plants to illustrate 
this group we may take the wake-robin, as it is sometimes 
called, or trillium. There are several species of this genus in 
the United States; the commonest one in the eastern part is 
the ‘‘ white wake-robin '’ (Trillium grandiflorum). This occurs 
in or near the woods. A picture of the plant is shown in fig. 
175. There is a thick, fleshy, underground stem, or rhizome 
as it is usually called. This rhizome is perennial, and is marked 
by ridges and scars. The roots are quite stout and possess 
coarse wrinkles. From the growing end of the rhizome each 
year the leafy, flowering stem arises. This is 20-30 cm, (8-12 
inches) in height. Near the upper end is a whorl of three ovate 
leaves, and from the centre of this rosette rises the flower stalk, 
bearing the flower at its summit. 

822. Parts of the flower. Calyx.—Now if we examine the 
flower we shall see that there are several leaf-like structures. 
These are arranged also in threes just as are the leaves. First 
there is a whorl of three, pointed, lanceolate, green, leaf-like 
members, which make up the cadyx in the higher plants, and the 
parts of the calyx are sepads, that is, each leaf-like member is a 
sepal. But while the sepals are part of the flower, so called, 
we easily recognize them as belonging to the /ea/ serves. 

328. Corolla.—Next above the calyx is a whorl of white or 
pinkish members, in Trillium grandiflorum, which are also leaf- 


196 


BOTANY, 


like in form, and broader than the sepals, being usually some- 


what broader at the free 
the corolla in the higher 
the corolla isa pefal. 
the flower, and are not 
would suggest that they 

324, Andrecium. — 
of the corolla is found 
bers which do not at first 
They are known in the 
seen in fig. 176 each 
filament), and extending 
greater part of the length 
side. This part of the 
ridges form the anther 
flower is opened, these 
in the wall along the edge 
see quantities of yellow- 
escaping from the rup- 
les. If we place some 
microscope we see that it 
ute bodies which resem- 
rounded in form, and the 


end. These make up what is 
plants, and each member of 
But while they are parts of 
green, their form and position 
also belong to the leaf series. 

Within and above the insertion 
another tier, or whorl, of mem- 
sight resemble leaves in form. 
higher plants as s/amens. As 
stamen possesses a stalk (= 
along on either side for the 
are four ridges, two on each 
stamen is the anther, and the 
sacs, or lobes. Soon after the 
anther sacs open also by a split 
of the ridge. At this time we 
ish powder or dust 
tured anther locu- 
of this under the 
is made up of min- 
ble spores; they are 


Fig. 175. , ; 
Trillium grandiflorum, outer wall is spiny. 


ANGIOSPERMS. 197 


‘They are in fact spores, the microspores of the trillium, and 
here, as in the gymnosperms, are better known as pollen. 

325. The stamen a sporophyll.—Since these pollen grains 
are the spores, we would 
infer, from what we have 
learned of the ferns and 
gymnosperms, that this 


Fig. 176. 
Sepal, petal, stamen, and pistil of Trillium 
grandiflorum. 


member of the flower which 
bears them is a sporophyll; 
and this is the case. It is in 
fact what is called the mucro- 
sporophyll, Then we see also 
that the anther sacs, since they 
enclose ‘te spores, would be the sporangia 
(microsporangia). From this it is now quite 
clear that the stamens belong also to the leaf 
series. They are just six in number, twice the 
number found in a whorl of leaves, or sepals, 
or corolla. It is believed, therefore, - 
that there are two whorls of stamens an 
in the flower of trillium. 3 

326. Gynecium.—Next above the 
stamens and at the centre of the flower 
ts a stout, angular, ovate body which terminates in three 
long, slender, curved points. This is the pistil, and at 


Fig. 177. 
4 Trillium grand- 

diflorum, with 
fe the compound 
Y pistil expanded 
into three leaf- 
like members, 
At the right 
these three are 
shown in detail. 


198 BOTANY. 


present the only suggestion which it gives of belonging to the 
leaf series is the fact that the end is divided into three parts, 
the number of parts in each successive whorl of members of the 
flower. If we cut across the 
body of this pistil and examine 


it with a low power we see that 
there are three chambers or cavi- 
ties, and at the junction of each 
the walls suggest to us that this 
body may have been formed by 
the infolding i 

of the margins 
of three leaf- 
like members, 
the places of contact having 


Abnormal 
trillium. The 
nine parts of 
the perianth 
are green, 
and the outer 
whorls of 
stamens are 


then become grown together. 
We see also that from the incurved 
margins of each division of the pistil eee, 
there stand out in the cavity oval bers. 
bodies. These are the ovules. Now the ovules, we have learned 
from our study of the gymnosperms, are the sporangia (here the 
macrosporangia). It is now more evident that this curious 
body, the pistil, is made up of three leaf-like mem- 
bers which have fused together, each member being 
the equivalent of a sporophyll (here the macrosporo- 
phyll). This must be a fascinating observation, that 
plants of such widely different groups and of such 
different grades of complexity should have members 
formed on the same plan and belonging to the same 
series of members, devoted to similar functions, and 
ae yet carried out with such great modifications that at 
lium showi& first we do not see this common meeting ground 
on the margin. which a comparative study brings out so clearly. 
327. Transformations of the flower of trillium.—If anything 
more were needed to make it clear that the parts of the flower 


TRILLIUM. 199 


of trillium belong to the leat series we could obtain evidence 
from the transformations which the flower of trillium sometimes 
presents. In fig. 178 is a sketch of a flower of trillium, made 
from a photograph. One set of the stamens has expanded into 
petal-like organs, with the anther sacs on the margin. In fig. 
177 is shown a plant of Trillium grandiflorum in which the 
pistil has separated into three distinct and expanded leaf-like 
structures, all green except portions of the margin. 


Exercise 62. 


$28. Toothwort (dentaria).—Note the general habit of the plant; the 
rather long, slender, smooth, fleshy, underground, perennial root stock 
(stem) ; the rudimentary leaves ; the roots; the growing end some distance 
ahead of the point where the annual flowering shoot arises ; compare with 
trillium in this respect. 

The flowering annual shoot; note the slender, smooth stem, the two 
opposite leaves which are three divided (trifoliate), the open raceme of 
flowers terminating the shoot. 


Exercise 63. 


829. The flower.—Compare the parts of the flower with the leaves. The 
flowers should be collected before all of them are open, since the sepals fall 
away quite easily. Note that the flower parts are in twos or multiples of 
two, while in trillium the parts are in threes or multiples of three. In each 
case the number of parts in a whorl is the same as the number of leaves in a 
whorl, so that this strengthens the view of the parts of the flower being 
homologous with the leaves. 

Illustrate and describe the different members of the flower. The pistil 
here is also a compound pistil. 

If there is time compare with other flowers like the toothwort, as the 
shepherd’s purse, mustard, etc. 


DESCRIPTION OF THE TOOTHWORT. 


330. General appearance.—For another study we may take 
a plant which belongs to another division of the higher plants, 
the common ‘“‘ pepper root,’’ or ‘‘toothwort’’ (Dentaria di- 
phylla) as it is sometimes called. This plant occurs in moist 


200 BOTANY. 


woods during the month of May, and is well distributed in the 


northeastern United 
States. <A plant is shown 
in fig. 180. It has a 
creeping underground 
rhizome, whitish in color, 
fleshy, and with a few 
scales. Each spring the 
annual flower - bearing 
stem rises from one of 
the buds of the rhizome, 
and after the ripening of 
the seeds, dies down. 

The leaves are 
situated a little above 
the middle point of 
the stem. They are 


Flower of the toothwort (Dentaria 
diphylla). 


opposite and the num- 


‘ Fig. 180. 
ber is two, each one Toothwort (Dentaria diphylla). 


TOOTHWORT. 201 


being divided into three dentate lobes, making what is called a 
compound leaf. 

331. Parts of the flower.—The flowers are several, and they 
are borne on quite long stalks (pedicels) scattered over the 
terminal portion of the stem. We should now examine the 
parts of the flower, beginning with the calyx. This we can see, 
looking at the under side of some of the flowers, possesses four 
scale-like sepals, which easily fall away after the opening of the 
flower. They do not resemble leaves so much as the sepals of 
trillium, but they belong to the leaf series, and there are two 
pairs in the set of four. The corolla also possesses four petals, 
which are more expanded than the sepals and are whitish in 
color. The stamens are six in number, one pair lower than 
the others, and also shorter. The filament is long in propor- 
tion to the anther, the latter consisting of two lobes or sacs, 
instead of four as in trillium. The pistil is composed of two 
carpels, or leaves fused together. So we find in the case of the 
pepper root that the parts of the flower are in twos, or multiples 
of two. Thus they agree in this respect with the leaves; and 
while we do not see such a strong resemblance between the 
parts of the flower here and the leaves, yet from the presence 
of the pollen (microspores) in the anther sacs (microsporangia) 
and of ovules (macrosporangia) on the margins of each half of 
the pistil, we are, from our previous studies, able to recognize 
here that all the members of the flower belong to the leaf 
series. 

332. In trillium and in the pepper root we have seen that 
the parts of the flower in each apparent whorl are either of the 
same number as the leaves in a whorl, or some multiple of that 
number. This is true of a large number of other plants, but it 
is not true of all. The trillium and the dentaria were selected 
as being good examples to study first, to make it very clear 
that the members of the flower are fundamentally leaf structures, 
or rather that they belong to the same series,of members as do 
the leaves of the plant. 


202 BOTANY. 


Material.—Entire plants of trillium and dentaria in flower, with root 
stock. Specimens either fresh or dried. Entire flowers of both plants 
when they cannot be obtained at the right season, may be preserved in ad- 
vance in formalin. A sufficient number should be prepared, depending on 
the number of pupils in the class. Mature fruit may also be preserved in 
formalin or alcohol. It will be useful to have entire plants of trillium col- 
lected in late autumn, in the winter, or early spring before the flower stalk 
rises above the ground, in order to see the condition in which the flower 
passes the winter. 


CHAPTER XXXII.* 


PROTHALLIUM AND SEXUAL ORGANS OF 
FLOWERING PLANTS. 


333. The stamens and pistils are not the sexual organs.— 
Before the sexual organs and sexual processes in plants were 
properly understood it was customary for botanists to speak 
of the stamens and pistils of flowering plants as the sexual 
organs. Some of the early botanists, a century ago, found 
that in many plants the seed would not form unless first the 
pollen from the.stamens came to be deposited on the stigma of 
the pistil. A little further study showed that the pollen 
germinated on the stigma and formed a tube which made its 
way down through the pistil and into the ovule. 

This process, including the deposition of the pollen on the 
stigma, was supposed to be fertilization, the stamen was looked 
on as the male sexual organ, and the pistil as the female sexual 
organ. We have found out, however, by further study, and 
especially by a comparison of the flowering plants and the lower 
plants, that the stamens and pistils are not the sexual organs of 
the flower. 

334, The stamens and pistils are spore-bearing leaves.—The 
stamen is the spore-bearing leaf, and the pollen grains are not un- 
like spores; in fact they are the small spores of the angiosperms. 
The pistil is also a spore-bearing leaf, the ovule the sporangium, 
which contains the large spore called an eméryo sac. In the 
ferns we know that the spore germinates and produces the green 
heart-shaped prothallium. The prothallium bears the sexual 

* This chapter is for reading and reference, but if the teacher desires to 
give demonstrations of the germinating pollen grain, and of the embryo sac, 


the following memorandum on material will be found of assistance. 
203 


204 BOTANY. 


organs. Now the fern leaf bears the spores and the spore forms 
the prothallium. So it is in the flowering plants. The staren 
bears the small spores—pollen grains—and the pollen grain 


Fig. 182. 


Diagrammatic section of a flower, Ke, calyx; X, corolla; _/, the filament, and a, the 
anther, of the stamen; %, pollen-cells, some in the anther, others on the stigma; /, the 
ovary, surmounted by the style, g, and the stigma, ~ (this ovary contains one ovule, which 
has a single coat, 7, enclosing the ovule-body, S) ; e#, the embryo-sac; £, germ-cell; fs, 
evpollen tube penetrating the style, and reaching the germ-cell through the micropyle of 
the ovule. 


forms the prothallium. The prothallium in turn forms the sex- 
ual organs. The process is in general the same as it is in the 
ferns, but with this special difference: the prothallium and the 
sexual organ of the flowering plants are very much reduced. 
335. The male prothallium is reduced to the pollen grain. 
—In fact the pollen grain is male prothallium and 
sexual organ all in one, so reduced has it become. 
A young pollen grain of trillium is shown in fig. 
183. It has two cells. The entire pollen grain 
may be considered the antheridium, the larger cell 


Fig. 183. 
Nearly mature representing the wall while the smaller cell is the 
pollen grain of tril- 7 
lium, Thesmaller generative cell. The latter corresponds to the 
cell is the genera- ese 
tive cell. central cell of the fern antheridium. In the 


angiosperms it divides to form two sperm cells. These cor- 


POLLINATION AND FERTILIZATION. 205 


respond to the spermatozoids, though they are not motile. 
Sometimes the sperm cells are formed within the pollen grain. 
At other times they are only formed 
after the pollen grain has germinated. 
In fig. 184 is a germinating pollen 
grain of peltandra, showing three 
nuclei. The generative cell has di- 
vided to form the two sperm cells. 

336. The embryo saé is the female Fie Su, 
prothallium.—Now while the small — Germmating spores 

* (pollen grains) of pel- 
spore (= the pollen grain) escapes tandra; generative 
usually from the anther, the larger vided in other “divi 

a ded to form the two 
spore (= embryo sac), borne in the sperm nuclei; vegeta- 
ovule on the pistil, never escapes com- ond fete 
pletely from the ovule, and only rarely protrudes part way. 
Inside of the nucellus, which is the central part of the ovule, a 
sac is formed which contains several nuclei. It is the embryo 
sac, or large spore, as shown in the diagram. It is also the 
female prothallium. One of these nuclei is the egg nucleus, 
but the prothallium is so reduced that there is no archegonium 
wall. The egg itself is perhaps the reduced archegonium. 

337. Fertilization.—When the pollen tube grows down the 
pistil and into the embryo sac in the ovule, as shown in the 
diagram (fig. 182), one of the sperm nuclei which it bears unites 
with the egg nucleus of the embryo sac. This is fertzization. 
The fertilized egg now grows to form the embryo. So the em- 
bryo is formed inside of the ovule. This is what makes the seed. 
The ovule with its coats contains the embryo. Since the embryo 
sac containing the egg does not escape from the ovule, the sperm 
cell must in some way be brought to it. This necessitates the 
transportation of the pollen from the stamen to the pistil. 
This transportation of the pollen from the stamen to the pistil 
is pollination. Botanists now usually distinguish in this way 
between pollination and fertilization. 

338. Difference between organ and member.—While it is 


206 BOTANY. 


not strictly correct then to say that the stamen is a sexual organ, 
or male organ, we might regard it as a male meméer of the flower, 
and we should distinguish between organ and member. It is an 
organ when we consider pollen production, but it is not a sexual 
organ. When we consider fertilization it is not a sexual organ, 
but a male member of the flower which bears the small spore. 
The fullowing table will serve to indicate these relations. 


Stamen = spore-bearing leaf = male member of flower. 

Anther locule = sporangium. 

Pollen grain = small spore = reduced male prothallium and 
sexual organ. 


So the pistil is not a sexual organ, but might be regarded as 
the female member of the flower. 


Pistil = spore-bearing leaf = female member of flower. 

Ovule = sporangium. 

Embryo sac = large spore = female prothallium containing the 
egg. 

The egg =a reduced archegonium = the female sexual 
organ. 


Fig. 185. 

A, represents a straight (orthotropus) ovule of polygonum; 3B, the inverted (anatropous) 
ovule of the lily ; and C, the right angled (campylotropus) ovule of the bean. /, funicle; 
ce, chalaza; #, nucellus; a/, outer irtegument ; 77, inner integument ; 7, micropyle ; em, 
embryo sac. 


339. Parts of the ovule.—In fig. 185 are represented three 
different kinds of ovules, which depend on the position of the 


POLLINATION AND FERTILIZATION. 207 


ovule with reference to its stalk. The funicle is the stalk of the 
ovule, the hilum is the point of attachment of the ovule with 
the ovary, the raphe is the part of the funicle in contact with 
the ovule in inverted ovules, the chalaza is the portion of the 
ovule where the nucellus and the integuments merge at the base 
of the ovule, and the micropyle is the opening at the apex of 
the ovule where the coats do not meet. 

340. In the pines and other gymnosperms the male and 
female prothallium, as regards structure and development, are 
intermediate between those of the higher plants and the ferns, 
but they are nevertheless much reduced. For a full discussion 
of the prothallium and sexual organs of the gymnosperms and 
angiosperms see the author’s larger ‘‘ Elementary Botany,’’ 
Chapters XXXI, XXXII, and XXXIV, and for pollination, see 
Chapter L. 


Material_—To show the male and female prothallium of angiosperms. 
Pollen grains of several species may be germinated in a weak solution of 
sugar in water, and these studied with the aid of the microscope, to see the 
pollen tube. 

The female prothallium (embryo sac in different stages) can be obtained 
by making sections of ovules just before and after fertilization. The lily 
is a good one to use, since there are many ovules standing at right angles 
to the pistil. Cross-sections of the pistil afford many good sections of the 
ovules where they are carefully made. Permanent slides can be purchased 


of supply companies. 


CHAPTER XXXIII. 
SEEDS AND SEEDLINGS. 


I. SEEps. 


This chapter is for reading and reference, 

341. Parts of the seed.—The seed consists of the embryo 
surrounded by the ripened ovule and certain secondary growths. 
Following fertilization as the embryo is forming in the embryo 
sac, a new growth of cells is formed also within the embryo 
sac but surrounding the embryo. This is called the endosperm. 
The young embryo derives some of its nutriment from the endo- 
sperm. In some seeds the nucellus (central part of the ovule) 
forms nutritive tissue, which may be consumed during the 
ripening of the seed, or in some seeds a portion of it remains 
outside of the endosperm, as perisperm. 

342. Outer parts of the seed— While the embryo is forming 
within the ovule and the growth of the endosperm is taking 
place, where this is formed, other correlated changes occur in 
the outer parts of the ovule, and often in adjacent parts of the 
flower. These unite in making the “‘ seed,”’ or the ‘‘ fruit.’’ 
Especially in connection with the formation of the seed a new 
growth of the outer coat, or integument, of the ovule occurs, 
forming the outer coat of the seed, known as the /es/a, while 
the inner integument is absorbed. In some cases the inner 
integument of the ovule also forms a new growth, making an 
inner coat of the seed (rosacee). In still other cases neither 
of the integuments develops into a testa, and the embryo sac 
lies in contact with the wall of the ovary. Again an additional 

208 


SEEDS AND SEEDLINGS. 209 


envelope grows up around the seed; an example of this is 
found in the case of the red berries of the ‘‘ yew’’ (taxus), the 
red outer coat being an extra growth, called an aril, 

In the willow and the milkweed an aril is developed in the 
form of a tuft of hairs. (In the willow it isan outgrowth of 
the funicle, = stalk of the ovule, and is called a funicular aril; 
while in the milkweed it is an outgrowth of the micropyle, = 
the open end of the ovule, and is called a micropylar aril.) 

343. Increase in size during seed formation.—Accompany- 
ing this extra growth of the different parts of the ovule in the 
formation of the seed is an increase in the size, so that the seed 
is often much greater in size than the ovule at the time of fer- 
tilization. At the same time parts of the ovary, and in many 
plants, the adherent parts of the floral envelopes, as in the apple; 
or of the receptacle, as in the strawberry; or in the involucre, 
as in the acorn; are also stimulated to additional growth, and 
assist in making the fruit. 

In the pine not only the ovular coat grows to form the outer 
coat of the seed, the entire ‘‘ scale’’ increases greatly in size, 
and when the fruit is mature, a portion of this scale splits off 
forming a ‘‘ wing’’ to the seed (see fig. 169). 

344. Endosperm in the ripe seed.—In many seeds when they 
are ripe there is still a large amount of the endosperm surround- 
ing the embryo (albuminous seeds). 
This is the case in the violet, as 
shown in fig. 186. Other examples 
of this kind are found in the butter- 
cup family, the grasses, the lily, 
palm, jack-in-the-pulpit, etc. When 
the seed germinates this endosperm 
is used as food by the embryo. 


° Fig. 186. 
345. Endosperm absent in the Seed of violet, external view, and 
section. The section shows the em- 
ripe seed.—In many other plants bryo lying in the endosperm, 
all of the endosperm is consumed by the embryo during its 


growth in the formation of the seed. This is the case in the 


210 BOTANY. 


rose family, crucifers, composites, willows, oaks, legumes, etc., 
as in the acorn, the bean, pea, and others. In some, as in the 
bean, a large part of the nutrient substance passing from the 
endosperm into the embryo is stored in the cotyledons for use 
during germination (exalbuminous seeds). 


346. Synopsis of the seed. 

Aril, rarely present. 

Ovular coats (oneor two usually present), the 
testa, 

Funicle (stalk of ovule), raphe (portion of funicle 

Ripened ovule.4 when bent on to the side cf ovule), mcropyle, 

hilum (scar where seed was attached to ovary). 

The seed. Remnant of the nucellus (central part of ovule) ; 

sometimes nucellus remains as 

| Perisperm in some albuminous seeds. 

Endosperm, present in albuminous seeds. 

Embryo within surrounded by endosperm when this is present, 
or by the remnant of nucellus, and by the ovular coats which 
make the ¢esta. 

See figures for parts of the ovule. 


II. SEEDLINGS. 


(For reading, unless exercises 1-4 have not yet been em- 
ployed. In that case those exercises should be taken up now.) 

347, Additional studies on seedlings.—In beginning our 
studies of the life processes of plants we used a number of seed- 
lings. We found it necessary to learn something about the parts 
of the seedling, and in fact about the parts of mature plants in 
dealing with the functions which the members of the plant per- 
form. Now, however, we are dealing more strictly with the parts 
of the plant in respect to the form of the member, and its value 
as showing relationship among plants. So that studies of seeds 
and seedlings is a part of our study of the form characters in the 
morphology of the angiosperms. Even if one choses to complete 
the practical study of the seedling under the head of the life 
processes of plants, one should now take the seeds and seedlings 
again into account in recognizing their relation to the new 


SEEDS AND SEEDLINGS. 211 


theme, and in learning the value of characters which aid us in 
assigning plants to their proper categories. 

348. The three seedlings to be studied.—For this reason 
some of the illustrations of seedlings are introduced here, as 
well as an account of their germination, and the means by which 
they obtain food stored in the seed. In connection with this 
reading the pupil can refer back to the plants studied in exer- 
cises 1-4, and the teacher is at liberty to introduce here exer- 
cises, if that seems desirable to further illustrate the subject 
where there is an abundance of time. Three seedlings are 
selected to illustrate the theme here; the common garden bean, 
the castor-oil bean, and the jack-in-the-pulpit. 

349. The common garden bean.—The seed coats are nearly 
filled with the two large cotyledons, which form the larger part 
of the embryo. After the beans have- been well soaked if one 
is split lengthwise the young root and stem with the small 
leaves will be seen lying between the cotyledons at one side. 
There is no endosperm here now, since it was all used up in 
the growth of the embryo, and a large part of its substance was 
stored up in the cotyledons. As the seed germinates the young 
plant gets its first food from that stored in the cotyledons. The 
part of the stem between the cotyledons and the root (called 
the hypocotyl in all seedlings) elongates, so that the cotyledons 
are lifted from the soil. The hypocotyl is the part of the stem 
here which becomes strongly curved, and the large cotyledons 
are dragged out of the soil as shown in fig. 187. The outer 
coat becomes loosened, and at last slips off completely. The 
plumule (the young part of the stem with the leaves) is now 
pushing out from between the cotyledons. As the cotyledons 
are coming out of the ground the first pair of leaves rapidly 
enlarge, so that before the stem has straightened up there is a 
considerable leaf surface for the purpose of starch formation. 
The leaves are at first clasped together, but as the stem becomes 
erect they are gradually parted and come to stand out nearly in 
a horizontal position. Fig. 187 shows the different positions. 


212 BOTANY. 


As the cotyledons become exposed to the light they assume a 
green color. Some of the stored food in them goes to nourish 
the embryo during germination, and they therefore become 
smaller, shrivel somewhat, and at 
last fall off. 

350. The castor-oil bean.—This 
is not a true bean since it belongs 
to a very different family of plants 
(euphorbiacez). In the germina- 
tion of this seed a very interesting 
comparison can be made with that 
of the garden bean. As the “‘ bean’”’ 
swells the very hard outer coat 
generally breaks open at the free 
end and slips off at the 
stem end. The next 
coat within, which is also 
hard and shining black, 
splits open 
at the oppo- 
site end, that 


Fig. 187. 
How the garden bean comes out of the ground. First the looped hypocotyl, then the 
cotyledons pulled out, next casting off the seed coat, last the plant erect, bearing thick 
cotyledons, the expanding leaves, and the plumule between them. 


is at the stem end. It usually splits open in the form of 
three ribs. Next within the inner coat is a very thin, whitish 
film (the remains of the nucellus, and corresponding to the 
perisperm) which shrivels up and loosens from the white mass, 
the endosperm, within. In the castor-oil bean, then, the 
endosperm is not all absorbed by the embryo during the forma- 
tion of the seed. As the plant becomes older we should note 
that the fleshy endosperm becomes thinner and thinner, and at 


SEEDS AND SEEDLINGS. 213 


last there is nothing but a thin whitish film covering the green 
faces of the cotyledons. The endosperm has been gradually 
absorbed by the germinating plant through its cotyledons and 
used for food. 


Ariszema triphyllum. 


351. Germination of seeds of jack-in-the-pulpit. — The 
ovaries of jack-in-the-pulpit form large, bright red berries with 
a soft pulp enclosing one to several 
large seeds. The seeds. are oval in 
form. Their germination is interesting, 
and illustrates one type of germination 
of seeds common among monocoty- 
ledonus plants. If the seeds are covered 
with sand, and kept in 
a moist place, they will 
germinate readily. 


Fig. 188, 
Germination of castor-oil bean. 


352. How the embryo backs out of the seed. The embryo 
lies within the mass of the endosperm; the root end, near the 
smaller end of the seed. The club-shaped cotyledon lies near 
the middle of the seed, surrounded firmly on all sides by the 
endosperm. The stalk, or petiole, of the cotyledon, like the 
lower part of the petiole of the leaves, is a hollow cylinder, and 
contains the younger leaves, and the growing end of the stem 
or bud. When germination begins, the stalk, or petiole, of the 
cotyledon elongates. This pushes the root end of the embryo 
out at the small end of the seed. The free end of the embryo 


214 BOTANY. 


Seedlings of castor-oil bean casting the seed coats, and showing papery remnant of 
the endosperm, 


Fig. 191. 
Section of germinating embryos of 
jack-in-the- pulpit, showing young 
leaves inside the petiole of the coty- 


Fig. 190. ledon. At the left cotyledon shown 
Seedlings of jack-in-the-pul- surrounded by the endosperm in the 
pit ; erabryo backing out of the seed ; at right endosperm removed to 


seed. show the club-shaped cotyledon. 


SEEDS AND SEEDLINGS. 215 


now enlarges somewhat, as seen in the figures, and becomes the 
bulb, or corm, of the baby jack. At first no roots are visible, 
but in a short time one, two, or more roots appear on the 
enlarged end. 

353. Section of an embryo.—If we make a longisection of 
the embryo and seed at this time we 
can see how the club-shaped cotyle- 
don is closely surrounded by the 
endosperm. Through the cotyledon, 
then, the nourishment from the en- 
dosperm is readily passed over to the 
growing embryo. In the hollow part 
of the petiole near 
the bulb can be seen 
the first leaf. 


Fig. 192. Fig. 193. Fig. 194. 
Seedlings of jack-in-the- Embryos of jack-in-the-pulpit still Seedling of jack-in- 
pulpit, first leaf arching out attached to the endosperm in seed the-pulpit; section of 
of the petiole of the coty- coats, and showing the simple first the endosperm and 
ledon, leaf. cotyledon, 


354. How the first leaf appears.—As the embryo backs out 
of the seed, it turns downward into the soil, unless the seed is 


216 BOTANY. 


so lying that it pushes straight downward. On the upper side 
of the arch thus formed, in the petiole of the cotyledon, a slit 
appears, and through this opening the first leaf arches its way 
out. The loop of the petiole comes out first, and the leaf later, 
as shown in fig. 192. The petiole now gradually straightens 
up, and as it elongates the leaf expands. 

355. The first leaf of the jack-in-the-pulpit is a simple one, 
—The first leaf of the embryo jack-in-the-pulpit is very different 
in form from the leaves which we are accustomed to see on 
mature plants. If we did not know that it came from the seed 
of this plant we would not recognize it. It is simple, that is it 
consists of one lamina or blade, and not of three leaflets as in 
the compound leaf of the mature plant. The simple leaf is 
ovate and with a broad heart-shaped base. The jack-in-the- 
pulpit, then, as trilllum, and some other monocotyledonous 
plants which have compound leaves on the mature plants, have 
simple leaves during embryonic development. The ancestral 
monocotyledons are supposed to have had simple leaves. Thus 
there is in the embryonic development of the jack-in-the-pulpit, 
and others with compound leaves, a sort of recapitulation of 
the evolutionary history of the leaf in these forms. 


CHAPTER XXXIV. 


THE PLANT BODY AND SOME OF ITS MODI- 
FICATIONS. 


For reading and reference. 

If it is desired to study the different kinds of stems, leaves, 
and roots, with their various modifications, the teacher can 
arrange some exercises based on the characters and examples 
given below in paragraphs 358-364. 

356. The plant body.—In the simpler forms of plant life, as 

in spirogyra and many of the alge and fungi, the plant body is 
not differentiated into parts. In many other cases the only 
differentiation is between the growing part and the fruiting part. 
In the alge: and fungi there is no differentiation into stem and 
leaf, though there is an approach to it in some of the higher 
forms. Where this simple plant body is flattened, as in the 
#sea-wrack, or ulva, it is a_ frond. The Latin word for frond is 
thallus, and this name is applied to the plant body of all the 
lower plants, the algze and fungi. The alge and fungi together 
are sometimes called the /shallophytes, or thallus plants. The 
word thallus is also sometimes applied to the flattened body of 
the liverworts. In the foliose liverworts and mosses there is an 
axis with leaf-like expansions. These are believed by some to 
represent true stems and leaves, by others to represent a flattened 
thallus in which the margins are deeply and regularly divided, 
or in which the expansion has only taken place at regular 
intervals. 

357. Members of the plant body.—In the higher plants there 
is usually great differentiation of the plant body, though in 

217 


218 BOTANY. 


many forms, as in the duck-weeds, it isa frond. While there 
is great variation in the form and function of the members of 
the plant body, they are reducible to a few fundamental mem- 
bers. Some reduce these forms to three, the roof, sfem, and 
leaf, while others to two, the roof and shoof, which is perhaps 
the better arrangement. Here the shoot is farther divided into 
stem and leaf, the leaf being a lateral outgrowth of the stem. 


858. Synopsis of members of the plant in angiosperms. 
Root. ( Foliage leaves. 
Perianth leaves. 
Spore-bearing leaves 
with sporangia. 
(Sporangia sometimes J 
{on shoot). 


Higher plant. Stet | 


Shoot. | 
Leaf. { 


\ Flower. 


359. The parts of the plant body as members or organs.— 
The members of the plant body can be considered from 
several standpoints. We might study them from the standpoint 
of physiology, when the members would be regarded as organs 
for performing certain kinds of work. As organs for nutrition 
the leaves serve a purpose in transpiration and in starch for- 
mation. The roots and root hairs serve as organs for absorption 
of food from the soil. The bright petals of flowers often serve 
to attract insects which aid in cross-pollination. The stamens’ 
and pistils serve a purpose in the process of reproduction. The 
stems serve as support for the plant, for the transport of food 
materials, and for bearing the leaves and flowers. So in various 
modifications of the members purposes of protection, support, 
vegetative propagation, etc., are served. 

In this sense the members of the plant body might be studied 
in Part I, in conjunction with the study of the means by which 
plants obtain their food. 

From another standpoint we might consider the great variety 
of form, and the numerous modifications, as expressions of the 
forces of evolution, inheritance, relation to environment, etc. 
(see Ecology). 


THE PLANT BODY. 219 


From still another standpoint they might be studied as indi- 
cating relationships. Their form, position, arrangement, etc., 
_ Serve to characterize certain groups of individuals so that they 
' can be distinguished from others. 

The different forms of the members are usually designated by 
special names, but it is convenient to group them in the single 
series. i 

360. Stem Series. 

Tubers, underground thickened stems, bearing buds and scale 
leaves; ex., Irish potato. 

foot-stocks, underground, usually elongated, bearing scales 
or bracts, and a leafy shoot; ex., trillium, mandrake, etc. 
Root-stocks of the ferns bear expanded, green leaves. 

Runners, slender, trailing, bearing bracts, and leafy stems as 
branches; ex., strawberry vines. 

Corms, underground, short, thick, leaf bearing and scale 
bearing; ex., Indian turnip. 

Bulbs, usually underground, short, conic, leaf and scale bear- 
ing; ex., lily. 

Thorns, stout, thick, poorly developed branches with rudi- 
ments of leaves (scales); ex., hawthorn. 

Tendrils, slender reduced stems. 

Flower axes (see morphology of the angiosperms). 

361. Leaf series.—Besides the foliage leaves, the following 
are some of their modifications: 

Flower parts (see morphology of the angiosperms). 

Bracts and scales, small, the former usually green (flower 
bracts), the latter usually chlorophylless. Bud scales are some- 
times green. 

Tendrils, modifications of the entire leaf (tendrils of the 
squash where the branched tendril shows the principal veins of 
the leaf), modification of the terminal pinnz of the leaf (vetch), 
etc. ’ 

Spines (examples are found in the cacti, where the stem is 
enlarged and green, functioning as a leaf). 


220 BOTANY. 


Other modifications occur as in the pitcher plant, insectivor- 
ous plants, etc. 

362. The root shows less modification. Besides normal 
roots, which are fibrous in most small plants and stout in the 
larger ones, some of the modifications are found in fleshy roots, 
where nourishment is stored (ex., dahlia, sweet potato, etc.); 
aerial roots (ex., poison ivy, the twining form), aerial orchids, 
etc. 


CHAPTER XXXV. 


ARRANGEMENTS OF THE PARTS OF THE 
FLOWER. 


This chapter is for reading and reference. 

363. Relations of the parts of the flower.—In some plants 
the parts of the flower are distinct, and in others they are more 
or less united. Definite terms are used to indicate these rela- 
tions of the parts of the flower. In trillium and dentaria which 
we have studied, all the sets, or whorls of parts, are free, i. e., 
no one floral set is adherenf to another. The pistils make one 
set, the stamens another, the petals another, and the sepals 
another set. These sets are all free in their zsertion on the 
receptacle of the flower. The receptacle of the flower is that 
portion of the stem where the flower parts are attached. 

Further the parts of the calyx, corolla, and andrcecium are 
distinct. That is, the parts (sepals) of the calyx, for example, 
are not united together by their edges. 

‘In the buttercup family, represented by the marsh marigold 
(figures 221, 222) all parts of the flower are both /ree and dis- 
tinct. 

364. Parts of the flower coherent.—But in both trillium and 
dentaria the parts of the gyncecium are coherent, i. e., the 
carpels (three in trillium and two in dentaria) are united into a 
single, compound pistil. 

So in any set when the parts of that set are partly or com- 
pletely united they are said to be coherent. The stamens are 
coherent by their anthers in the bell flower and in most of the 
flowers of the composite family, as in the aster (see fig. 242), 


sunflower, golden rod, etc. 
221 


222 BOTANY. 


In the morning-glory (fig. 195) the petals are coherent, form- 
ing a funnel-shaped corolla as shown in the figure. Such a 
‘corolla is also said to be gamopetalous. 
Where the sepals are coherent the 
_calyx is gamosepalous. The morning- 
slory has a gamosepalous calyx also, 
though the sepals are 
only united near the 
base. In the morn- 
ing-glory the petal 
» parts can be distin- 

guished, five in num- 
ber, but they are not so prominent 
as in the bluet (fig. 196), where there 
are four prominent petal lobes. 

Sometimes the gamopetalous corol- 
la is unequally lobed, when it may 
be ‘‘bilabiate,’’ i.e., two- 
lipped as in the dead nettle 
(fig. 197), where there are 
three petal lobes in the lower 
lip and two petal lobes in the 
upper lip. Such a flower is 


Fig. 195. z . 
Morning-glory (Convol- ‘¥ 4 also said to be «regular. 


vulus sepium). 


The gamosepalous calyx may 
also be two-lipped. 

365. Adherent.—In many plants one floral set is united with 
another, when such sets are adherent. 

This is well shown in the flowers of the evening primrose, 
where the tubes of the gamopetalous corolla and gamosepalous 
calyx are united to form a long tube. This tube is again at its 
base adherent to the outer surface of the ovary, and above, the 
stamens are adherent to the throat of the tube (fig. 198). 

366. Epigynous, perigynous, and hypogynous.—Where any 
portion of the calyx or corolla is adherent to the ovary, the 


ARRANGEMENTS OF FLOWER PARTS. 223 


flower is said to be efigynous, as in the evening primrose. 
When the stamens or petals are borne on the calyx, the flower 
is said to be perigynous, or the stamens are said to be perigy- 
nous, as in the cherry (fig. 229), apple, etc. The flower is 
Aypogynous when all the parts of the calyx, corolla, and andree- 


Fig. 196. 
The bluet (Houstonia ccerulea), 


cium are free in their insertion, that is, when they are inserted 
on the receptacle, ‘‘ under the pistil,’’ since the pistil termi- 
nates the floral axis (example, the buttercup, etc.). 

867. Floral Formula.—A formula is sometimes written to 
show at a glance the general points of agreement in the flower 


224 BOTANY. 


among the members of a family or group. The floral formula 
of the lily family is written as follows: Calyx 3, Corolla 3, 


Fig. 197. 
Spray of dead-nettle (Lamium am- 
plexicaule), leaves and flowers. 


Fig. 198. 
Section of flower of 
evening primrose. 


Androecium 6(3—-3), Gyncecium 3. The formula may be abbre- 
viated thus: Ca3,Co3,A6(3 + 3),G3. 

368. Floral diagram.—The relation of the parts of the flower 
on the axis are often represented by a diagram, as shown in 
figs. 221, 237, 244, etc. 


CHAPTER XXXVI 
RELATIONSHIPS SHOWN BY FLOWER AND FRUIT. 


369. Importance of the flower in showing kinships among 
the higher plants.—In the seed-bearing plants which we are 
now studying we cannot fail to be impressed with the general 
presence of what is called the flower. 

While the spore-bearing members, as well as the floral 
envelopes, are thus grouped into ‘‘ flowers,’’ there is a great 
diversity in the number, arrangement, and interrelation of these 
members, as is suggested by our study of trillium and dentaria. 
And a farther examination of the flowers of different plants 
would reveal a surprising variety of plans. Nevertheless, if we 
compare the flower of trillium with that of a lily for example, 
or the flower of dentaria with that of the shepherd’s purse 
(capsella), we shall at once be struck with the similarity in the 
plan of the flower, and in the number and arrangement of its 
members. This suggests to us that there may be some kinship, 
or relationship between the lily and trillium, and between the 
shepherd’s purse and toothwort. In fact it is through the 
interpretation of these different plans that we are able to read 
in the book of nature of the relationship of these plants. 


Note For REFERENCE. 


370. Arrangement of flowers.——The arrangement of the 
flowers (inflorescence) on the stem is important in showing 
kinships. The flowers may be scattered and distant from each 
other on the plant, or they may be crowded close together in 

225 


226 BOTANY. 


Nie 


Fig. 199. 


RELATIONSHIPS SHOWN BY FLOWER AND FRUIT, 227 


spikes, catkins, heads, etc. Many of the flower arrangements 
are dependent on the manner of the branching of the stem. 
Some of the systems of branching are as follows: 

371. I. Dichoromous Brancuinc.—True dichotomy (forking) 
does not occur in the shoots of flowering plants, but it does 
occur in some of the flower clusters. 

372, II. LaTeraL BRANCHING. —Two main types. 

Monopodial branching.—This occurs where the main shoot 
continues to grow more vigorously than the lateral 
branches which arise in succession around the main 
stem. Examples in shoots, horse-chestnut, pines (see 
chapter on pine). The inflorescence is termed indefinite, 
or indeterminate inflorescence, i.e., the flowers all arise 
from /a/eral buds, the main axis continuing to grow. 
Raceme,; \ateral axes unbranched, youngest flowers near 

the terminal portion of long main axis; ex., choke- 
cherry, currant, spring beauty, etc. 

Spike; main axis long, lateral unbranched axes with 
sessile and often crowded flowers; ex., plantain. 
Where the main axis is fleshy the spike forms a sfadzx, 
as in skunk’s cabbage, Indian turnip, etc.; if the 
spike falls away after maturity of the flower or fruit 
it is a ca¢/kin or ament (willows, oaks, etc.). 

OUmébel; the main axis is shortened, and the stalked 
flowers appear to form terminal clusters or whorls, as 
in the parsley, carrot, parsnip, etc. 

Head, or capitulum; the main axis is shortened and 
broadened, and bears sessile flowers, as in the sun- 
flower, button-bush, etc. 

Panicle; when the raceme has the lateral axes branched 
it forms a pancle, as in the oat. When the panicle is 
flattened it forms a corymé, as in the hawthorn. 

Sympodial branching or cymose branching.—The branches, 
or lateral axes, grow more vigorously than the main 
axis, and form for the time false axes (form cymes). 


228 BOTANY. 


The inflorescence is termed cymose, or definite, or deter- 
minate inflorescence because the growth of each axis is 
stopped by the formation of a flower. 


Fig. 200, 
Single umbel of the wild carrot. 


Zz. Monochasium,; only one lateral branch is produced 
from each relative or false axis. 

Helicoid cyme; when the successive lateral branches 
always arise on the same side of the false axis, as in 
flower clusters of the forget-me-not. 

Scorpioid cyme; when the lateral branches arise alter- 
nately on opposite sides of the false axis. 

2. Dichasium; each relative, or false, axis produces two 
branches, often forming a false dichotomy. Ex- 
amples in shoots are found in the lilac, where the 
shoot appears to have a dichotomous branching, 
though it is a false dichotomy. 

Forking cyme, flower cluster of chickweed. 

3. Plewchasium,; each relative, or false, axis produces 
more than two branches. 

873. The fruit—In some cases the single seed itself forms 
the fruit as is the case with nuts, sunflower seeds, etc. In 
other cases several seeds ripen inside of a single pistil as in the 


RELATIONSHIPS SHOWN BY FLOWER AND FRUIT. 229 


bean pod, or in several pistils united as in the apple, to form 
the fruit. In the sunflower seed and the apple other parts of 
the flower are also united with the pistil in forming the fruit. 
The fruit of the angiosperms varies greatly, and often is greatly 


Y 
ep 


Fig. 201. 
Forget-me-not. 


complicated. When the gyncecium is apocarpous (that 1s when 
the carpels are from the first distinc’) the ripe carpels are 
separate, and each is a fruit. In the symcarpous gynecium 
(when the carpels are united) the fruit is more complicated, 
and still more so when other parts of the flower than the gynoe- 
cium remain united with it in the fruit. 

Pericarp, this is the part of the fruit which envelops the 
seed, and may consist of the carpels alone, or of the 
carpels and the adherent part of the receptacle, or calyx; 
it forms the wall of the fruit. 

Endocarp and exocarp. If the pericarp shows two different 
layers, or zones, of tissue, the outer is the exocarp, and 
the inner the ezdocarp, as in the cherry, peach, etc. 


230 BOTANY. 


Mesocarp; where there is an intermediate zone it is the 
mesocarp 

I. Capsuce (dry fruits). The capsule has a dry pericarp 

which opens (dehisces) at maturity. When the capsule 
is syncarpous the carpels may separate along the line of 
their union with each other longitudinally (septczdal 
dehiscence) as in the azalea, or rhododendron; or each 
carpel may splzt down the middle line (loculicidal dehiscence) 
as in fruit of iris, lily, etc.; or the carpels may open 
by pores ( poriczdal dehiscence), as in the poppy. 

Folticle; a capsule with a single carpel which dehisces 
along the ventral, or upper, suture (/arkspur, peony). 

Legume or pod; a capsule with a single carpel’ which 
dehisces along both sutures (pea, bean, etc.). 

Stlique; a capsule of two carpels, which separate at 
maturity, leaving the partition wall persistent (tooth- 
wort, shepherd’s-purse, and most others of the mustard 
family); when short it is a silicle or pouch. 

Pyxidium or pyxts,; the capsule opens with a lid (plantain). 

II. Dry inpEHIscENT FRUITS; do not dehisce or separate into 
distinct carpels. 

Nuts; with a dry, hard pericarp. 

Caryopsis; with one seed and a dry leathery pericarp 
(grasses). 

Achene, with pericarp adherent to the seed (sunflower and 
other composites). 

III. Scuizocarp; a dry, several-loculed fruit, in which the 
carpels separate from each other at maturity but do 
not dehisce (umbelliferee, mallow). 

IV. Berry; endocarp and mesocarp both juicy (grape). 

V. Pome; mesocarp and outer portion of endocarp soft and 

juicy, inner portion of endocarp papery (apple). 

VI. Drupr, oR sTONE FRUIT; endocarp hard and stony, 
exocarp soft and generally juicy (cherry, walnut); in 

the cocoanut the exocarp is soft and spongy. 


CHAPTER XXXVII. 
CLASSIFICATION (OR TAXONOMY). 


374, Species.—It is not necessary for one to be a botanist in 
order to recognize, during a stroll in the woods where the 
trillium is flowering, that 
there are many individual 
plants very like each 
other. They may vary 
in size, and the parts may 
differ a little in form. 
When the flowers first 
open they are usually 
white, and in age they 
generally become pinkish. 
individuals they are pinkish when they 
first open. Even with these variations, 
which are trifling in comparison with 
the points of close agreement, we 
recognize the individuals to be of the 
same kind, just as we 
recognize the corn plants 
grown from the seed of 
an ear of corn as of the 
same kind. Individuals 
of the same kind, in this sense, form a sfeczes. The white 
wake-robin, then, is a species. 

But there are other trilliums which differ greatly from this 
one. The purple trillium (T. erectum) shown in fig. 202 is very 

231 


In some 


Fig. 202. 


Trillium _ erec- 
tum(purple form), 
two plants from 
one root-stock. 


232 BOTANY. 


different from it. So are a number of others. But the purple 
trillium is a species. It is made up of individuals variable, yet 
very like one another, more so than any one of them is like the 
white wake-robin. 

375. Genus.—Yet if we study all parts of the plant, the 
perennial root-stock, the annual shoot, and the parts of the 
flower, we find a great resemblance. In this respect we find 
that there are several species which possess the same general 
characters. In other words, there is a relationship between 
these different species, a relationship which includes more 
than the individuals of one kind. It includes several kinds. 
Obviously, then, this is a relationship with broader limits, and 
of a higher grade, than that of the individuals of a species. 
The grade next higher than species we call gezus. Trillium, 
then, is a genus. Briefly the characters of the genus trillium 
are as follows. 

376. Genus trillium.— Perianth of six parts: sepals 3, 
herbaceous, persistent; petals colored. Stamens 6 (in two 
whorls), anthers opening inward. Ovary 3-loculed, 3—6-angled; 
stigmas 3, slender, spreading. Herbs with a stout perennial 
root-stock with fleshy scale-like leaves, from which the low 
annual shoot arises bearing a terminal flower, and 3 large 
netted-veined leaves in a whorl. 

Note.—In speaking of the genus the present usage is to say 
trilllum, but two words are usually employed in speaking of the 
species, as Trillium grandiflorum, T. erectum, etc. 

377. Genus erythronium.— The yellow adder-tongue, or 
dog-tooth violet (Erythronium americanum), shown in fig. 203, 
is quite different from any species of trillium. It differs more 
from any of the species of trillium than they do from each other. 
The perianth is of six parts, light ycllow, often spotted near the 
base. Stamens are 6. The ovary is obovate, tapering at the 
base, 3-valved, seeds rather numerous, and the style is elon- 
gated. The flower stem or scape, arises from a scaly bulb deep 
in the soil, and is sheathed by two elliptical-lanceolate, mottled 


CLASSIFICA TION. 233 


leaves. The smaller plants have no flower and but one leaf, 
while the bulb is nearer the surface. Each year new bulbs are 
formed at the end 
of runners from a 
parent bulb. These 
runners penetrate 
each year deeper g_ 
in the soil. The Y 
deeper bulbs bear \ 
the flower stems. 
378. Genus 
lilium.—While the 
lily differs from 
either the trillium 
or erythronium, 
yet we recognize a 
relationship when 
we compare the 


perianth of six 
colored parts, the 
6 stamens, and the 
3-sided and long 
3-loculed ovary. 
379, Family Fig. 203. 


od Adder-tongue (erythronium). At left below pistil, and three 
liliaceze.—The re- stamens opposite three parts of the perianth. Bulb at the 


lationship between a 

genera, as between trillium, erythronium, and lilium, brings us 
to a still higher order of relationship where the limits are broader 
than in the genus. Genera which are thus related make up the 
family. \n the case ot these genera the family has been named 
after the lily, and is the lily family, or Zzlacea. 

380. Order, class, group.—In like manner the lily family, 
the iris family, the amaryllis family, and others which show 
characters of close relationship are united into an order which 
has broader limits than the family. This order is the lily order, 


234 BOTANY. 


or order Zihiflore. The various orders unite to make up the 
class, and the classes unite to form a group. 

381. Variations in usage of the terms class, order, etc. — 
Thus, according to the system of classification adopted 
by some, the angiosperms form a group. The group angio- 
sperms is then divided into two classes, the monocotyledones and 
dicotyledones. (It should be remembered that all systematists 
do not agree in assigning the same grade and limits to the 
classes, subclasses, etc. For example, some treat of the 
angiosperms as a class, and as the monocotyledons and dicoty- 
ledons as subclasses; while others would divide the monocoty- 
ledons and dicotyledons into classes, instead of treating each 
one as a Class or as a subclass. Systematists differ also in usage 
as to the termination of the ordinal name; for example, some 
use the word Lzhales for Liliifiore, in writing of the order.) 

382. Monocotyledones.—In the monocotyledons there is a 
single cotyledon on the embryo; the leaves are parallel veined ; 
the parts of the flower are usually in threes; endosperm is 


ox 


HH 


E} 
fe 


ANS 


ees 


my 
EeRTS: 


Fig. 204. 
A. Cross-section of the stem of an oak tree thirty-seven years old, showing the annual 
tings. v7, the medullary rays, , the pith (medulla). &. Cross-section of the stem of 
a palm tree, showing the scattered bundles. 


usually present in the seed; the vascular bundles are usually 
closed, and are scattered irregularly through the stem as shown 
by a cross-section of the stem of a palm (fig. 204), or by the 
arrangement of the bundles in the corn stem (fig. 51). Thus 


CLASSIFICATION. 235 


a single character is not sufficient to show relationship in the 
class (nor is it in orders, nor in many of the lower grades), but 
one must use the sum of several important characters. 

383. Dicotyledones. — In the dicotyledons there are two 
cotyledons on the embryo; the venation of the leaves is reticu- 
late; the endosperm is usually absent in the seed; the parts of the 
flower are frequently in fives; the vascular bundles of the stem 
are generally open and arranged in rings around the stem as shown 
in the cross-section of the oak (fig. 204). There are exceptions 
to all the above characters and the sum of the characters must 
be considered, just as in the case of the monocotyledons. 

384, Taxonomy.—This grouping of plants into species, 
genera, families, etc., according to characters and relationships 
is classification, or taxonomy. 

To take Trillium grandiflorum for example, its position in 
the system, if all the principal subdivisions should be included 
in the outline, would be indicated as follows: 

Group, Angiosperms. 
Class, Monocotyledones. 
Order, Liliiflore. 
Family, Liliacez. 
Genus, Trillium. 
Species, grandiflorum. 
In the same way the position of toothwort would be indicated 
as follows: 
Group, Angiosperms. 
Class, Dicotyledones. 
Order, Rhoeadine. 
Family, Crucifere. 
Genus, Dentaria. 
Species, diphylla. 

But in giving the technical name of the plant only two of 
these names are used, the genus and species, so that for the 
toothwort we say Dentaria diphylla, and for the white wake- 
robin, we say Zrillum grandifiorum. 


STUDIES ON PLANT FAMILIES. 


CHAPTER XXXVIII. 
MONOCOTYLEDONES. 


Topic I: Monocotyledones with conspicuous petals 
(Petaloideee). 


Orver LILIIFLoRe. 


385. The lily family (liliacee).— Trillium grandiflorum 
which we employed as a representative of the monocotyledons 
in the morphology of the angiosperms, serves as one type of the 
lily family. An exercise is added here on the ‘‘ yellow adder’s- 
tongue ’’ for those who wish to study more than one example 
of the order. There is an abundance of material from the 
members of the family if the teacher desires to extend further 
the exercises on the liliaceze. 

Yellow adder’s-tongue (Erythronium americanum). (To be 
used as an alternate for trillium if preferred.) 


Exercise 64. 


386. Entire plant.—Observe the bulb from which the flowering scape 
arises ; the small scale-like leaves overlapping it ; the two large spotted leaves 
on plants which have the flower. In the case of the nonflowering plants ob- 
serve that there is only one large leaf. If an opportunity affords for an ex- 
cursion in the woods where the plant grows, see if you can determine how 
the bulbs are formed at the ends of the ‘‘runners.” As to depth in the soil 
compare the bulbs of the flowering and nonflowering plants. 

Inflorescence.—The inflorescence is determinate, and consists of a single 
terminal nodding flower on a scape. 


236 


LILIACEAE, 237 


Flower.—Beginning with the outer whorl of members of the flower deter- 
mine the number of members in each whorl, as well as their form, relation to 
each other, and the relation of the different sets among themselves. 

Sketch a member of the calyx, corolla, and andrcecium. Sketch the pistil, 
naming the parts. Make a section of the pistil (preferably one in which the 
seeds are nearly mature) and determine the number of carpels united to form 
it. How are the number of carpels manifested in the stigma ? 

Construct a floral diagram to show the relation and number of the different 
members of the flower. 

The flower of the adder’s tongue is complete, because it possesses all the 
floral sets. It is Derfect, because it-possesses both the andrcecium and gynce- 
cium. It is regular, because all the members of the calyx, as well as those 
of the corolla, are of equal size. 

387. Other examples of the lily family.—The lily family is 
a large one. Another example is found in the ‘‘ Solomon’s- 
seal,’’ with its elongated, perennial root-stock, the scars 
formed by the falling away of each annual shoot resembling a 
seal. The onion, smilax, asparagus, lily of the valley, etc., 
are members of the lily family. The parts of the flower are 
usually in threes, though there is an exception in the genus 
Unifolium, where the parts are in twos. A remarkable excep- 
tion occurs sometimes in Trillium grandiflorum, where the 
flower is abnormal and the parts are in twos. 


OutTpoorR OBSERVATIONS ON SOME OF THE LILIACER. 


If the study of the plant families is carried on during the 
spring, excursions should be made, if possible, to the fields and 
woods at opportune times for the purpose of studying some of 
the plants in their natural surroundings. The short studies 
given here will serve to indicate some of the observations that 
can be made during these excursions. For other suggestions, 
paragraph 455, and the author’s larger ‘‘ Elementary Botany ’’ 
(Part III, Ecology) should be consulted. 

388. Trillium.—As this white flower with its setting of green 
sepals is glinting to us out of copses and woodland like so 
many new fairies, few of us realize the long task which it has 
already begun in the silent depths of the soil in order that it 


238 PLANT FAMILIES: MONOCOTYLEDONS. 


may suddenly blossom again in season, when springtime returns. 
If we remove the old scales where the flowering stem joins the 
root-stock, we see a pointed, conical, white bud, which is to 
develop into the next season’s leafy plant and blossom. From 
June to August the new leaves and flower are slowly forming, 
protected by several overlapping, thick, whitish, soft scales, 
which form a conical roof to keep out water, and to protect 
against too sudden changes in cold during the autumn and 
winter season. In September we find that leaves and sepals are 
well formed and green, the petals are already white, and within 
are the six stamens and the angular pistil, all well formed. 
Where the sun reaches these copses and warms the soil well in 
autumn, sometimes the stamens are yellowish as early as Sep- 
tember or October from the already formed pollen. In the 
cooler shades the pollen is not yet formed and the stamens re- 
main whitish in color. But with the first onset of warm weather 
in the spring, or on warm days in the winter, before the flower 
bud lifts its head from its long winter’ sleep, snugly ensconced 
among the fallen leaves or spongy humus, the pollen quickly 
forms. Now all the plant has to do is to erect its standard, 
bearing aloft the opening blossom. 

389. The ovules, begun in the autumn, are now being com- 
pleted, pollination takes place, and later fertilization, and the 
embryo begins to form in June. The pure white flowers soon 
change to pinkish, the first evidence of decline. Finally they 
wither, and during the summer the fruit and seed are formed 
on the old flower stem, while the secret formative processes of 
the new blossoms are going on anew. 

390. The adder-tongue (erythronium) comes out early in the 
spring to catch the sunlight gleaming through rifts in the wood- 
land. It is not so forbidding as its name or its ‘‘ darting ’’ 
style would suggest. The rich color of its curved petals 
nodding from the fork of the variegated leaves lends cheer and 
brightness to the gray carpet of forest leaves. We are apt to 
associate the formation of the flower with the early springtime. 


< 
S 
‘ 
: 


240 PLANT FAMILIES: MONOCOTYLEDONS. 


But after the flower perishes, the bulb, deep in the soil, slowly 
builds the next season’s flower, which is kept through the 
autumn and winter, much of the time encased in ice, waiting 
for springtime that it may rise and unfold. 


ORDER GYNANDRA. 


$91. The orchid family (orchidacee).—Among the orchids 
are found the most striking departures from the arrangement of 
the flower found in the 
simpler monocotyle- 
dons. An example of 
this is seen in the lady- 
slipper (cypripedium, 
shown in fig. 208). The 
ovary appears to be 
below the calyx and 
corolla. This is brought 
about by the adhesion 
of the lower part of the 


Fig. 206. calyx to the wall of the 


Flower of an orchid (epipactis), the inferior ovary 
twisted as in all orchids so as to bring the upper part of ovary. The ovary then 


the flower below. is mferior, while the 
calyx and corolla ‘are epigynous. The stamens ‘are united 
with the style by adhesion, two lateral perfect ones and one 
upper imperfect one. The stamens are thus gynandrous. 
The sepals and petals are each three in number. One of the 
petals, the ‘‘slipper,’’ is large, nearly horizontal, and forms 
the ‘‘lip’’ or ‘‘labellum ”’ of the orchid flower. The labellum 
is the platform or landing place for the insect in cross-pollina- 
tion. Above the labellum stands one of the sepals more showy 
than the others, the “‘ banner.’’ The two lateral ‘‘ strings’ of 
the slipper are the two other petals. The stamens are still 
more reduced in some other genera, while in several tropical 
orchids three normal stamens are present. 

There are thus four striking modifications of the orchid 


”? 


ORCHIDACEA. 241 


flower: rst, the flower is irregular (the parts of a set are differ- 
ent in size and shape); 2d, adnation of all parts with the pistil; 
3d, reduction and suppression 
of the stamens; 4th, the ovary is 
twisted half way around so that 
the posterior side of the flower 
becomes anterior. Floral dia- 
grams in fig. 207 show the posi- 
tion of the stamens in two dis- Fig. 207. 


1 3 Diagrams of orchid flowers. A, the usual 
tinct types. The number of type ; &, of cypripedium. (Vines.) 


orchid species is very large, and 
the majority are found in tropical countries. 

392. Pollination of orchids\—Some of the most marvellous 
adaptations for cross-pollination by insects are found in the 


Fig. 209. 

Section of flower of cypripedium. s¢, 
stigma: a,atthe leftstamen. The insect 
enters the labellum at the centre, passes 
under and against the stigma, and out 
through the opening 4, where it rubs 
against the pollen. In passing through 
another flower this pollen is rubbed off 
on the stigma. 


orchids, or members of the orchis family. 
Fig. 208. The larger number of the members of 
Cypripedium, this family grow in thetropics. Many of 

these in the forests are supported on lofty trees where they are 
brought near the sunlight, and such are called ‘‘ epiphytes.’’ 


242 PLANT FAMILIES: MONOCOTYLEDONS. 


A number of species of orchids are distributed in temperate 
regions. 

393. Cypripedium or lady-slipper.—One species of the lady- 
slipper is shown in fig. 208. The labellum in this genus is 
shaped like a shoe, as one can see by the section of the flower 
in fig. 209. The stigma is situated at sf, while the anther is 
situated at a, upon the style. The insect enters about the 
middle of the boat-shaped labellum. In going out it passes up 
and out at the end near the flower-stalk. In doing this it 
passes the stigma first and the anther last, rubbing against 
both. The pollen caught on the head of the insect will not 
touch the stigma of the same, but will be in a position to come 
in contact with the stigma of the next flower visited. 


Exercise 65. 


394. The orchid.—Take one of the orchids, the lady-slipper (cypripedium) 
for example, and make out the parts of the flower, and the relation of the 
different members. Study the structure of the flower with reference to the 
pollination by insects, with the aid of the text, and determine the course 
which the insect takes to effect cross-pollination. 

Material,—Entire plants in flower, including the bulb. This is usually 
buried deep in the soil, and should be collected fresh if possible. Some of 
the smaller plants, not in flower, should also be at hand. The plant flowers 
during May in the northeastern United States. It is represented in other 
sections by different species. In sections where a species of this genus cannot 
be obtained another of the orchis family may be employed. (Apparatus. Dis- 
secting microscopes, or tripod lenses (the former are better), dissecting nee- 
dles, scalpel. The apparatus will not be repeated for the following exercises.) 


CHAPTER XXXIX. 
MONOCOTYLEDONS (ConrTiNuEpD). 


Topic II: Monocotyledons with flowers on a Spadix 
(Spadicifloree). 


395. Lesson II. The arum family (aracee).—This family is 
well represented by several plants. The skunk’s cabbage 
(Spathyema foetida), the ‘‘jack-in-the-pulpit,’’ also called 
** Indian-turnip ’’ (Ariszema triphyllum), shown in fig. 210, the 
water arum (Calla palustris), and the sweet flag (Acorus cala- 
mus) are members of this family, as also are the callas and 
caladiums grown in conservatories. The parts of several of the 
species of this family, especially the corm of the Indian turnip, 
are very acrid to the taste. The floral parts are more or less 
reduced. 

396. Relatives of the arum family.—Related to the arum 
family are the ‘‘ duckweeds.’’ Among the members of this 
family are the most diminutive of the flowering plants, as well 


as the most reduced floral structures. 
Other related families are the cat-tails and palms. In the 
latter the spathe and spadix are of enormous size. The cocoa- 


nut is the fruit of the cocoanut palm. 


Exercise 66. 


INDIAN-TURNIP. 


397. Staminate plants (sometimes called male plants).—Sketch an entire 
plant showing the corm (the thickened perennial stem), the annual shoot with 
leaves and spathe. Cut away one side of the spathe to expose the long com- 
pact cluster of staminate (spadix) flowers within, Sketch the spadix, showing 
the mass of stamens as well as the sterile part of the shoot above. Dissect off 
from the axis several of the stamens. Note that the filament is very short, 
and that the anther is irregularly lobed. 

243 


244 PLANT FAMILIES: MONOCOTYLEDONS. 


398. The pistillate plants (sometimes called female plants).—Compare 
with the staminate plant. How many leaves are there? Is the number of 
leaves constant on all the pistillate plants? Cut away one side of the spathe 
and expose the spadix of pistillate flowers. Sketch. Observe that each 
flower consists of a single flask-shaped pistil, and that these are packed closely 
together. Note the delicate brush-like stigma. Search for plants which 
show both stamens and pistils on the same spadix. Where both kinds of 
flowers are present on the same spadix, on what part of the spadix does each 
kind appear? On the corm of different plants search for lateral buds, which 
are young plants. Observe that they usually arise on directly opposite sides 
of the corm ; that they easily become freed from the old corms; that they 
are young corms. Do they arise in the axils of the leaves or scale leaves 


which have fallen away ? 
Cut off a portion of the corm. Do not eat any portion but touch the 
tongue to the cut surface. The flesh of the corm is very acrid. 


DeEscrIPTION OF THE INDIAN-TURNIP. 

399. Indian-turnip.—The ‘‘ Indian-turnip,’’ or ‘‘ jack-in- 
the-pulpit ’’ (Ariseema triphyllum), loves the cool, shady, rich, 
alluvial soil of low grounds, or along streams, or on moist 
hillsides. A group of the jacks is shown in figure 210 as they 
occur in the rich soil on dripping rocks in one of our glens, 
At their feet is a carpet of moss. Often the violet sits humbly 
underneath its spreading three-parted leaves. The thin, strap- 
shaped spathe, unfolded at its base, bends gracefully over the 
spadix, the sterile end of which stands solitary in the pulpit 
thus formed. The flowers are very much reduced, i.e., the 
number of members in the sets is reduced so that they do not 
appear in threes as in the typical monocotyledons. Some of 
the members are also often reduced in size or are rudimentary. 
The plants are ‘‘ dimorphic ’”’ usually. 

400. Female plants.—The large plants usually bear the 
pistillate flowers, which are clustered around the base of the 
spadix, each flower consisting of a single pistil, oval in form, 
terminating in a brush-like stigma. The stigma consists of 
numerous spreading, delicate hairs. The open cavity of the 
short style is hairy also, and a brush of hairs extends into the 
cavity of the ovary. Into this brush of internal hairs the necks 


ARACES. 245 


of the several ovules crowd their way to the base of the style 
near its opening. Even when the stigma is not pollinated the 


Fig. 210. 
A group of jacks, 


ovary continues to grow in size, and the stigmatic brush remains 
fresh for a long time. 


* 


246 PLANT FAMILIES: MONOCOTYLEDONS. 


401. Male plants.— Excepting some of the intermediate sizes, 
one can usually select on sight the male and female plants. 
The smaller ones which have a spathe are nearly all male and 
bear a single leaf, though a few have two leaves. The male 
flowers are also clustered at the base of the spadix, and are very 
much reduced. Each flower consists only of stamens, and 
singularly the stamens of each flower are joined into one com- 
pound stamen, the anther-sacs forming rounded lobes at the 
end of the short consolidated filaments. 

402. The female plants require more food than the male 
plants.—In some plants both male and female flowers occur on 
a single spadix, the lower flowers being female, while the upper 
ones are male. The larger plants are nearly all female, and 
many, though not all, bear two leaves. In this dimorphism of 
the plant there is a division of labor apportioned to the destiny 
and needs of each, and in direct correspondence with the 
capacity to supply nutriment. The staminate flowers, being 
short-lived, need comparatively a small amount of nutriment, 
and after the escape of the pollen (dehiscence of the anthers) 
the spathe dies, while the leaf remains green to assimilate food 
for growth of the fleshy short stem (corm), where also is stored 
nutriment for the growth in the autumn and spring when the 
leaf is dead. The female plants have more work to do in 
providing for the growth of the embryo and seed, in addition 
to the growth of the corm and next season’s flower. The 
smaller female plants thus sometimes exhaust themselves so in 
seed bearing that the corm becomes small, and the following 
season the plant is reduced to a male one. 

403. Growth and death of the corm.—The new roots each 
year arise from the upper part of the corm. The stored sub- 
stances in the base of the corm are used in the early season’s 
growth, and the old tissue sloughs off as the new corm is formed 
above upon its remains. 


Material.—Freshly collected plants should be used, the entire plant; small 
ones as well as large ones. 


CHAPTER XL. 
MONOCOTYLEDONS (ConcLupep). 


Topic III: Monocotyledons with a glume subtending 
the flower (Glumiflore). 


404, Lesson III. Grass family (graminee). Oat.—As a 
representative of the grass family (graminez) one may take the 
oat plant, which is widely cultivated, and also can be grown 


Fig. 215. 

| 6 Flower of 
Fig. err. Fig. 212. Fig. 213. Fig. 214. oat, showing 
Spikelet of One glume re- Flower opened Section show- the _ upper 
oat showing moved showing showing two palets, ing ground plan paletbehind, 
two glumes, fertile flower. three stamens, and of flower. a,axis. and the two 
two lodicules at base lodicules in 

of pistil. front. 


readily in gardens, or perhaps in small quantities in greenhouses 
in order to have material in a fresh condition for study. Or we 
247 


248 PLANT FAMILIES: MONOCOTYLEDONS. 


may have recourse to material preserved in alcohol for the 
dissection of the flower. The plants grow usually in stools; 
the stem is cylindrical, and marked by distinct nodes as in the 
corn plant. The leaves possess a sheath and blade. The 
flowers form a loose head of a type known asa panicle. Each 
little cluster as shown in fig. 211 is a spikelet, and consists 
usually here of one or two fertile flowers below and one or two 
undeveloped flowers above. We see that there are several 
series of overlapping scales. The two lower ‘ones are 
‘““glumes,’’ and because they bear no flower in their axils are 
empty glumes. Within these empty glumes and a little higher 
on the axis of the spike is seen a boat-shaped body, formed of 
a scale, the margins of which are folded around the flowers 
within, and the edges inrolled in a peculiar manner when 
mature. From the back of this glume is borne usually an awn. 
If we carefully remove this scale, the ‘‘ flower glume,’’ we find 
that there is another scale 
on the opposite (inner) 
side, and much_ smaller. 
This is the ‘‘ palet.’’ 

Next above this we 
have the flower, and the 
most prominent part of 
the flower, as we see, is 
the short ‘pistil with the. 
two plume-like styles, and 
the three stamens at fig. 
213. But if we are careful 
in the dissection of the 

Fig. 216. parts we shall see, on look- 

Fr es ice ire aaa Gi, glumes ; B, palets ; ing close below the pistil 
on the side of the flower- 

ing glume, that there are two minute scales (fig. 215). These are 
what are termed the /odicules, considered by some to be merely 
bracts, by others to represent a perianth, that is two of the 


GRAMINEZ. 249 


sepals, the third sepal having entirely aborted. Rudiments of 
this third sepal are present in some of the graminez. 

405. Other members of the grass family.—To the graminex 
belong also the wheat, barley, corn, the grasses, rice, etc. It 
is one of the most important families from an economic stand- 
point, furnishing a great variety of food for man and other 
animals. The graminez, while belonging to the class mono- 
cotyledons, are less closely allied to the other families of the 
class than these families are to each other. For this reason 
they are regarded as a very natural group. 


Exercise 67. 


406. The wheat (Triticum sativum vulgare).—The wheat plant may be 
studied as an alternate for the oat plant. 

The entire wheat plant.—Study the entire wheat plant, and compare with 
the oat plant. Are the stems of the wheat single or are stools formed? 
Since a germinating grain of wheat forms at first but a single stem, how are 
the stools formed? Examine young wheat plants to determine this. 

The inflorescence.—The ‘ head’”’ of wheat forms a single spike. Sketch a 
spike. Remove a few of the spikelets, and note the jointed and zigzag char- 
acter of the axis (rachis) of the spike ; note the attachment of the spikelets. 

The spikelets.—Note the empty glumes at the base ; determine how many 
flowers there are ina spikelet. How many flowering glumes and palets are 
there to each flower? in a mature head of wheat determine how many of 
the flowers in a spikelet ripen grain, and how, many are sterile? Are there 
any of the spikelets which are completely sterile? Where are they located ? 

Using a head of wheat at the time of flowering, Spread apart the members 
of a flower with the aid of dissecting needles, , and ‘sketch the parts ‘of the 
flower, showing the glume, palet, the three stamens, and the _pistil with the | 
plumose styles. Endeavor to find the lodicules. (See the description of the 
oat flower for comparison.) 

Sketch an empty and a flowering glume to show the ‘‘ nerves’’ and awns. 
Compare the grain of wheat with a grain of corn, (See paragraph 9.) 

Material.—Entire stools of young, fresh plants (may be obtained at any 
time during autumn, winter, or spring); mature plants in flower (if they can- 
not be obtained fresh they may be dried, preserving at the same time some of 
the flowering heads in alcohol or formalin) ; ripe heads of wheat. 


CHAPTER XLI. 
DICOTYLEDONS. 


Topic IV: Dicotyledons with distinct petals, flowers 
in catkins, or aments; often degenerate. 


OrpDER AMENTIFERZ. 


407. Lesson IV. The willow family (salicacee).—The wil- 
lows represent a very interesting group of plants in which the 


Spray of willow leaves, pistillate and staminate catkins (Salix discolor). SRS 


flowers are greatly reduced. The flowers are crowded on a 
more or less elongated axis forming a caékin, or ament. The 
250 


SALICACELE. 251 


ament is characteristic of several other families also. The 
willows are dicecious, the male and female catkins being borne 
on different plants. The catkins appear like great masses of 
either stamens or pistils. But if we dissect off several of the 
flowers from the axis, we find that there are many flowers, each 
one subtended by a small bract. In the male or “sterile’’ 
catkins the flower consists of two to eight stamens, while in the 
female or “‘ fertile ’’ catkins the flower consists of a single pistil. 
The poplars and willows make up the willow family. 


Exercise 68. 

408. The willow (Salix discolor). 

The leafy shoot.— Determine the arrangement of the leaves of the willow ; 
sketch a leaf showing its form,'the character of the margin, and of the vena- 
tion. If different willows are at hand compare the color of the twigs, as well 
as the character of the twigs as to brittleness or litheness. 

The inflorescence.— What is the kind of inflorescence? Are both kinds of 
flowers borne on the same ament (catkin), or on different aments ? 

The staminate catkins.—Determine what constitutes a flower by dissect- 
ing some of them off from the axis of the catkin. What parts of the flower 
are present? How many stamens in a flower? Ifa hand lens is convenient 
use it in making out the form of the parts. Sketch a flower in its position on 
the axis of the catkin, showing also the bract at the base of the flower. De- 
scribe the character of the bract as scen under the lens. 

The pistillate catkin.—What parts of the flower are present? Compare 
with the staminate flower. Sketch a pistillate flower with the subtending 
bract to show the form of the ovary, with the divided stigma. Is the pistil 
sessile or stalked? How many carpels make up the pistil? Is there a small 
gland (nectary) present near the base of the ovary which represents the peri- 
anth? Is there a nectary on the staminate flower? 

The fruit.—Examine ripe pods of the willow. Determine what parts of 
the flower unite to form the fruit. What difference between a fruit and seed 
in the willow? What means is provided for the dissemination of the seeds ? 

Field observations on the willows.—At what time do the catkins of the 
willow appear? ‘Do they flower before the leaves appear? At time of flow- 
ering note the character and abundance of the pollen from the stamens. _ Is it 
in the form of “‘ dust,’’ or is it adhesive? How are the willows pollinated ? 
Do insects visit the willow flower? Are willows easily propagated by shoots ? 
What happens if a willow branch is stuck into damp soils ; when it is left in 
the water for some time ? 


‘ 


252 PLANT FAMILIES: DICOTYLEDONS. 


Material.—Shoots of the willow, some with leaves, some with the catkins 
(the two kinds of catkins occur on different plants). If material cannot be 
obtained fresh when wanted for study, the leafy shoots may be preserved dry, 
and the catkins in alcohol or formalin, or dry. Ripe fruit should also be at 
hand; this may be preserved dry. 


OrpER AMENTIFERE. 


409. Lesson V. The oak family (cupulifere).—A small 
branch of the red oak (Quercus rubra) is illustrated in fig. 218. 


Fig. 218. 


Spray of oak leaves and flowers. Below at right is staminate flower, at left pistillate 
flower. 


This is one of the rarer oaks, and is difficult for the beginner 
to distinguish from the scarlet oak. The white oak is perhaps 


CUPULIFERE. 253 


in some localities a more convenient species to study. But for 
the general description here the red oak will serve the purpose. 
Just as the leaves are expanding in the spring, the delicate 
sprays of pendulous male catkins form beautiful objects. The 
petals are wanting in the flower, and the sepals form a united 
calyx, with several lobes, that is, the parts of the calyx are 
coherent. In the male flowers the calyx is bell-shaped and 
deeply lobed. The pendent stamens, variable in number, just 
reach below its margin. The pistillate or female flowers are 
not borne in catkins, but stand on short stalks, either singly or 
a few in a cluster. The calyx here is urn-shaped with short 
lobes. The ovary consists of three united (coherent) carpels, 
and there are three stigmas. Only one seed is developed in the 
ovary, and the fruit is an acorn. The numerous scales at the 
base of the ovary form a scaly involucre, the czp. 

The beech, chestnut, and oak are members of the oak 
family. 

410. Other ament bearers.—The following additional fam- 
ilies among the ament bearers are represented in this country: 
the birch family (birch, alder), the hazelnut family (hazelnut, 
hornbeam, etc.), walnut family (hickory, walnut), and the 
sweet-gale family (myrica). 


Exercise 69. 


411. The oak.—(The white oak or any common one in the neighborhood.) 

The leaves.—Determine the arrangement of the leaves on the shoot. 
Sketch a leaf showing the form, outline, and venation. Compare the young 
leaves with the old ones as to texture, surface characters, etc. 

The inflorescence.—What is the kind of inflorescence? Are both kinds of 
flowers in the same inflorescence or in different inflorescences ? 

The staminate inflorescence.—Note the cluster of staminate aments. De- 
termine a single flower and sketch it to show the parts. What parts of the 
flower are present? Determine the number of parts of each set present. 

The pistillate inflorescence.—How does it differ from the staminate in- 
florescence? Sketch a pistillate flower, showing the parts. What parts of 
the flower are present ? 

The fruit (an acorn with the cup).—Sketch an acorn in the “cup.” 


254 PLANT FAMILIES: DICOTYLEDONS. 


What is the homology of the cup? i.e., to what part or series of members of 
the plant does it belong? Could the pistillate flower of the ancestors of the 
oak have been in the form of aments, and if so could the cup of the acorn 
represent the degraded and consolidated ament? If so, what part of the 
ament would now be represented in the cup? (It has also been suggested 
that the scales of the involucre which make up the cup are adventitious 
growths accompanying the development of the fruit.) 

(If the acorn has not been studied under the paragraph dealing with seeds 
and fruits, and if there is time now, remove the wall of the acorn and deter- 
mine the parts of the embryo, Are any parts of the embryo green while still 
enclosed within the acorn ? ; 

Field observations on the oaks.—Compare the time of appearance of the 
flowers and leaves of the oak. What about the abundance of the pollen? 
How are the oaks pollinated? The ament-bearing plants are usually wind 
pollinated, and for this reason there is an abundance of pollen, and always in 
the form of dust. Is there an exception to this general rule? How long 
after the flowers are formed before the acorn is ripe? 

If there is time during excursions note other ament-bearing plants. 

Material.—Mature leaves, leafy shoots, sprays of the flowers, both pistillate 
and staminate ; fruit (the acorn in the cups). 


CHAPTER XLII. 
DICOTYLEDONS (ContTINuUED). 


Topic V: Dicotyledons with distinct petals and 
hypogynous flowers. 


OrpER URTICIFLORA. 


412. Lesson VI. The elm family (ulmacee).—The elm tree 
belongs to this family. The leaves of our American elm 
(Ulmus americana) are ovate, pointed, deeply serrate, and with 
an oblique base as shown in fig. 219. The narrow stipules 


Fig. 219. 
Spray of leaves and flowers of the American elm ; at the left above is section of flower, 
next is winged seed (a samara). 


which are present when the leaves first come from the bud soon 
fall away. The flowers are in lateral clusters, which arise from 
255 


256 PLANT FAMILIES: DICOTYLEDONS. 


the axils of the leaves, and appear in the spring before the 
leaves. They hang by long pedicels, and the petals are absent. 
The calyx is bell-shaped, and 4~-9-cleft on the margin. The 
stamens vary also in number in about the same proportion. 
A section of the flower in fig. 219 shows the arrangement of the 
parts, the ovary in the centre. The ovary has either one or 
two locules, and two styles. The mature fruit has one locule, 
and is margined with two winged expansions as shown in the 
figure. This kind of a seed is a samara. 


Exercise 70. 


413. The elm (Ulmus americana). 

Leaves.— What is the arrangement of the leaves on the shoot? Sketch a 
leaf showing its attachment to the shoot, and the relation of the stipules ; 
note how easily the stipules fall away. 

The inflorescence.—Describe the inflorescence ; a single flower; sketch a 
single flower in the positiun in which it stands on the tree. Cut away the 
floral envelope on one side; determine the number of stamens; the number 
of pistils; are the pistils single or compound? Of how many carpels is it 
composed? Sketch a flower with the front part of the envelope and the front 
stamens removed. What part of the floral envelope is present? What is its 
character and form? What are the relations of the sets of the flower to each 
other? In time of appearance how do the flowers compare with the leaves ? 

Describe the mature fruit; how many seed are present? What parts of 
the flower are united in the fruit? What is the fruit called? 

Materials.—Spray of leaves and flowers; it may be necessary to collect 
them at different times. Leafy shoots should be collected while some of the 
leaves are still young in order to preserve some with the stipules, and they 
may be preserved dry and pressed. Fruits collected at the time of maturity 
may he preserved dry. 


Orver PoLycarPica. 


414, Lesson VII. The crowfoot family (ranunculacee).— 
The marsh-marigold (Caltha palustris) is a member of this 
family. The leaves are heart-shaped or kidney-shaped, and the 
edge is crenate. The bright golden-yellow flowers have a 
single whorl of petal-like envelopes, and according to custom 
in such cases they are called sépals. The number is not 


RANUNCULACEAE. 257 


definite, varying from five to nine usually. The stamens are 
more numerous, as is the general rule in the members of the 
family, but the number of the pistils is small. Each one is 
separate, and forms a little pod when the seed is ripe. The 
marsh-marigold, as its name implies, occurs in marshy or wet 
places and along the muddy banks of streams. It is one of the 
common flowers in April and 
May. 


Exercise 71. 


415. The Buttercup.—If preferred, a 
species of buttercup may be studied instead 
of the marsh-marigold, but a comparison 
with the latter is de- 
sirable. 

The entire plant. 
—Describe form and 
habit of the plant ; 
the character of the 
stem; branching ; 
the form and arrangement of the 
leaves; the character of the roots 
(these characters will depend on the 
species). 

The inflorescence.— What kind of in- 
florescence? What parts of the flower 
are present? Describe the color and 
form of members of the different sets of 
the flower. Determine the number of 


Fig. 220. 
Caltha palustris, marsh-mari- 
gold. 


Fig. 221. members in each set (approximately if not ac- 
Diagram of marsh-marigold curately) 
flower. y). 


Sketch a sepal, a petal (is a nectar gland pres- 

ent ?), a stamen, and a pistil, noting carefully the characters of each. 

Do the stamens all ripen their pollen at the same time? Is there any ad- 
vantage as regards the time of ripening of the stamens ? 

What is the relation of the members of a set among themselves? What is 
the relation of the sets to each other ? 

Is the flower perfect or imperfect ; complete or incomplete? Is it regular 
or irregular ; hypogynous, perigynous, or epigynous? Are the parts of the 
flower free and distinct, or adherent, or coherent ? 


258 PLANT FAMILIES: DICOTYLEDONS. 


If fruit is present determine the number of seed in a ripe fruit; and also 
what parts of the flower make up the fruit. 

If there is time a comparison of the flowers, fruit, and leaves of different 
species of the ranunculus will be found interesting, especially species from 
dry and wet ground as well as some of the species which grow in the 
water. 

Construct the formula for the buttercup flower; also construct the floral 
diagram. 

Material.—Entire plants, some flowering stems with flowers, some with 
fruit. Fresh material when possible. 


Tue BurrEercup (RANUNCULUS). 


416. Other crowfoots.—Many of the crowfoots or buttercups 
(ranunculus) with bright yellow flowers grow in similar situa- 
tions. The ‘‘ wood anemone’’ (anemone), small plants with 
white flowers, and the rue anemone (anemonella), which resem- 
bles it, both flower in woods in early spring. The common 
virgin’s bower (Clematis virginiana) occurs along streams or on 
hillsides, climbing over shrubs or fences. ‘The vine is some- 
what woody. ‘The leaves are opposite, petioled, and are com- 
posed of three leaflets, which are ovate, three-lobed, and usually 
strongly toothed, and somewhat heart-shaped at the base. The 
flower clusters are borne in the axils of the leaves, and therefore 
may also be opposite. The clusters are much branched, form- 
ing a convex mass of beautiful whitish flowers. The sepals are 
colored and the petals may be absent, or are very small. The 
stamens are numerous, as in the members of the crowfoot 
family. The pistils are also numerous, and the achenes in fruit 
are tipped with the long plumose style, which aids them in 
floating in the air. 

417, Character of the ranunculaceez.—Some of the charac- 
ters of the ranunculacez we recognize to be the following: The 
plants are mostly herbs, the petals are separate, and when the 
corolla is absent the sepals are colored like a corolla. The 
stamens are numerous, and the pistils are either numerous or 
few, but they are always separate from each other, that is they 
are not fused into a single pistil (though sometimes there is but 


CRUCIFERE. 259 


one pistil). All the parts of the flower are separate from each 
other, and make up successive whorls, the pistils terminating 
the series. When the seeds are ripe the fruit is formed, and 
may be in the form of a pod, or achene, or in the form of a 
berry, as in the baneberry (actza). 


Orper Ru@aDINz. 


418. Lesson VI{I. The mustard family (crucifere).—This 
is well represented by the toothwort (dentaria), which we 
studied in a former chapter. (If the toothwort has been 
studied, the shepherd’s-purse may be omitted.) 


Exercise 72. 


419. The Shepherd’s purse (Capsella bursa-pastoris).—If it is desired to 
study a species besides the toothwort the shepherd’s-purse will answer It 
is a common and widely distributed species, found in waste places and in 
fields. 

The entire plant.—Note and describe the habit and character of the plant, 
i.e., the size, character of branching, character of the root, position and ar- 
rangement of the leaves. Compare the ‘‘radicle’’ (lower) leaves with the 
“‘cauline’’ (stem) leaves as to form, and insertion. The radicle leaves are 
more or less deeply lobed or pinnatifid (pinnately cut), while the stem leaves 
are slender, ianceolate, toothed, and often auricled (with little ears) at the base. 

The inflorescence.—What is the kind of inflorescence? Determine the 
parts of the flower present, as well as the number and arrangement of the 
members of the flower. What figure do the petals make in the flower, which 
suggests the name of the family to which the shepherd’s purse and the tooth- 
wort belong ? 

The fruit.— What parts of the flower are united in the fruit? Compare the 
plant with the toothwort. 

Construct the floral diagram of the toothwort or shepherd’s purse, or of 
other cruciferous plant studied. 

Material.—Entire plants with flowers and fruit. The plant occurs from 
early spring to autumn, and can be usually obtained in a fresh condition when 
wanted. 


The exercise on the violet may be omitted unless it is desired 
to study it in connection with some field observations, and for 
the purpose of observing ‘‘ cleistogamous’’ flowers, when the 
outline here given will answer, 


260 PLANT FAMILIES: DICOTYLEDONS. 


ORDER CISTIFLORA. 


420. The violet family (violacee).—The violet family is 
represented by the common blue violet, the yellow violet, the 
pansies, heart’s ease, sweet violet, etc. 


Exercise 73. 


421. The blue violet (Viola cucullata). 

The entire plant.—Describe the character and habit of the plant, the short 
underground stem, the ‘‘ radicle’’ leaves, the erect flower scapes which bear 
the conspicuous blue flowers, and the short, curved stems beneath the soil or 
débris which bear the closed inconspicuous flowers. Sketch a leaf, showing 
the form and venation. What is the form of the leaf and the character of 
the margin ? 

The blue flowers.—Sketch a flower. Is the flower regular or irregular? 
complete or incomplete ? perfect or imperfect ? 

The calyx.—Describe the form of the calyx ; how many sepals are indi- 
cated ? 

The corolla.—How many petals are present? Remove them and note care- 
fully the form of each one and the position in the flower. In the ‘‘ spurred’’ 
one look for nectar glands. 

The stamens.—Determine the number of the stamens. Are they united 
together by their anthers? Ifso thestamens are said to be symgenecious. 
Are the stamens of different sizes? Describe the form of the different ones 
and the relation of certain peculiar ones to the spur of the corolla. 

The pistil.— Describe the form of the pistil and the relation of the stamens 
and pistils. 

The closed (cleistogamous) flowers.—These are on shorter, curved, scapes 
which hold them beneath the soil or débris. Compare them with the blue 
flowers. What parts of the flower are absent ? 

The fruit.—Make a cross-section of the fruit and determine how many car- 
pels are represented in the pistil. Note the numerous seeds. 

Pollination of violets. —If a sweet violet flower, or the flowers of the pansy 
are convenient, study the stamens and pistil of the open flowers. Remove the 
corolla, and note the position of the anthers with reference to the pistil. 
Note the peculiar enlarged stigma with an opening in front, and the lip below. 
Move a pencil into a flower, endeavoring to imitate the entrance of an insec 
and try to determine how cross-pollination takes place. Compare the blue 
flowers of the blue violet. 

The small closed flowers are called cleistogamous, and they are se//-pol/i- 


VIOLACE. 261 


nated, because being closed, and because of the position of the anthers around 
the stigma the pollen from the opening anthers comes directly in contact with 
the stigma. In the flowers of the pansy cross-pollination often takes place 


Fig. 222. 
Viola cucullata ; blue flowers above, cleistogamous flowers smaller and curved below. 
Section of pistil at right. 


through the agency of insects. While the blue flowers of the blue violet 
rarely set fruit, nevertheless pollination and fertilization do take place in some 
of the flowers, though fruit sets more abundantly in the cleistogamous flowers, 
Material.—Entire plants with the flowers ; collect some early in the season 
when the blue flowers are abundant, and some later when the small flowers 
underneath the soil or leaves are formed. Mature fruit is also desirable. 


CHAPTER XLIII. 
DICOTYLEDONS (ConrTINUED). 


Topic VI: Dicotyledons with distinct petals and 
perigynous or epigynous flowers. 
Many trees and shrubs. 
ORDER AESCULINA, 


422. Lesson X. The maple family (aceracee).—Figure 223 
represents a spray of the leaves and flowers of the sugar maple 


Fig. 223. 
Spray of leaves and flowers of the sugar maple, 


(Acer saccharinum), a large and handsome tree. The leaves 
are opposite, somewhat ovate and heart-shaped, with three to 
262 


ACERACE,. 263 


five lobes, which are again notched. The clusters of flowers 
are pendulous on long hairy pedicels. The petals are wanting. 
The calyx is bell-shaped 
and several times lobed, 
usually five times. The 
stamens are variable in 
number. The ovary is 
two-lobed and the style 
deeply forked. The fruit 
forms two seeds, each with 


Fig. 224. 

ino-li i Seeds and flowers of sugar maple. At theright is 
2 long Wing) like Expansion a pistillate flower, in the middle a staminate flower, 
as shown in the figure. and at the left the two seeds forming a samara. 


The flowers of the maple are polygamo-dicecious, that is the 


male members (stamens) and female members (carpels) may be 
in the same flower or in different flowers. 


Exercise 74. 


423. The sugar maple (Acer saccharinum),—(Another species may be 
studied if desired. ) 

Leaves.—Determine the form and arrangement of the leaves; sketch a leaf. 

Inflorescence.—Describe the character of the inflorescence; sketch a 
flower cluster. 

Flowers.—Select several different flowers, some from different trees, and 
compare them carefully to see if the members of the flower are the same in 
all. Sketch several to show the general character. 

What parts of the flower are present? Describe the form and character of 
each set of members, and their relation to each other. Determine the number 
of members in each set and their relations among themselves. Study several 
flowers to make this out. 

The fruit.—Sketch a fruit. What parts of the flower are united in the 
fruit ? 

If there is time it will be found instructive to compare the flowers of an- 
other species of maple, like the red maple, with the sugar maple. Examine 
different flowers from several different trees in order to compare the different 
sizes of the stamens and pistils in different flowers, and the facts with refer- 
ence to the presence or absence of any of the members in certain of the 
flowers. Compare the leaves of the red maple with those of the sugar maple 
also. 


264 PLANT FAMILIES: DICOTYLEDONS. 


Materials.—Leafy shoots, either fresh or pressed and dried. Flowers; 
fresh as they appear in the spring ; if they cannot be studied immediately they 
may be preserved in alcohol or in formalin. They are better fresh. 

Fruits, collected in the autumn and preserved dry. 


Omit the study of the horse chestnut, unless it is desired to 
study it instead of the maple, since it belongs to the same order. 

424. The buckeye family (hippocastanacee).—The horse 
chestnut (/Esculus hippocastanum) is largely planted in the 
Northeastern United States as an ornamental tree. It is also 
self-seeding in waste places. The family is represented in 
other places by other species, the buckeye, from which the 
family gets its common name, for example occurs in Ohio (the 
Buckeye State). 


Exercise 75. 


425. The horse chestnut (Zsculus hippocastanum). 

The leaves.—Note the form and arrangement of the leaves. Sketch a leaf 
to show its form and the parts. What kind of a leaf is it? 

The inflorescence (mixed racemose).—The flowers. What parts of the 
flower are present? Is the flower complete or incomplete ; regular or irreg- 
ular ; perfect or imperfect ? 

Describe the calyx ; the corolla; describe a petal, its form and color. 
How many petals present ? 

The stamen.—How many present ? Sketch a stamen. 

The pistil.—Describe the form of the pistil, its parts ; how many carpels 
are represented in the pistil? What is the character of the surface of the 
ovary ? 

The mature fruit.— What is the character of the surface of the mature 
fruit? Describe the form of the fruit. What parts of the flower are united 
to form the fruit? What is the difference between the fruit and a seed in the 
horse chestnut? Examine the embryo in the seed ; note its large cotyledons 
and the well developed hypocotyl. Why is the embryo not good for food for 
man? 

Construct the floral diagram of the horse-chestnut flower. 

Material.—Sprays of leaves and flowers, collected fresh. Mature fruits. 


CHAPTER XLIV. 
DICOTYLEDONS (Continuep). 


OrpDER RosiFLoRz. 


426. Lesson XI.—The rose-like flowers are an interesting 
and important group. In all the members the receptacle (the 
end of the stem which bears the parts of the flower) is an im- 
portant part of the flower. It is most often widened, and 
either cup-shaped or urn-shaped, or the centre is elevated. 
The carpels are borne in the centre in the depression, or on the 
elevated central part where the receptacle takes on this form. 
The calyx, corolla, and the stamens are usually borne on the 
margin of the widened receptacle, and where this is on the 
margin of a cup-shaped 
or urn-shaped recep- 
tacle they are said to 
be perigynous, that is, 
around the gyncecium. 
The calyx and corolla 
are usually in fives. 
There are three families, 


foll Fig. 225. 
ee Perigynous flower of spiraa (S. lanceolata). (From 
427. The rose family Warming.) 


(rosace#).—In this family there are five types, represented by 

the following plants and illustrations: rst. In spiraa (fig. 225) 

the receptacle is cup-shaped. There are five carpels, united at 

the base, but free at the ends. 2d. In the strawberry the 

receptacle is conic and bears the carpels (fig. 226). The conic 

receptacle becomes the fleshy fruit, with the seeds in little pits 
265 


266 PLANT FAMILIES: DICOTYLEDONS. 


over the surface. 3d. The raspberries, blackberries, etc., 
represented here by the flower- 
ing raspberry (Rubus odoratus), 
fig. 227. 4th. This is repre- 
sented by the roses. The re- 
ceptacle is urn-shaped and con- 
stricted toward the upper por- 
tion, with the carpels enclosed 


Fig. 226. 
Flower of Fragaria vesca with columnar jn the base (fig. 228). 5th. 


receptacle. (From Warming.) Fe 
Here the receptacle is cup- 


shaped or bell-shaped and nearly closed at the mouth as in the 
agrimony. 

428. Lesson XII. The almond or plum family (amygdala- 
cewe).—The members of this family are trees or shrubs. The 
common choke-cherry (fig. 
229) will serve to represent 
one of the types. The 
flowers of this species are 
borne in racemes. The 
receptacle is cup-shaped. 
WwW Only one seed in the single 


K—@ 


: Fig. 227. Fig. 228, 
Flowering raspberry (Rubus odoratus). Perigynous flower of rosa, with 
contracted receptacle. (From 
Warming.) 


carpel (sometimes two carpels) matures as the calyx falls away. 


ROSIFLOREA. 267 


The outer portions of the ovary become the fleshy fruit, while 
the inner portion becomes the hard stone with the seed in the 
centre. Such a fruit is a drupe. 

The floral formula for this family is as follows: 


Cas5,Co5,A15—20 or 30,G1. 


429. Lesson XIII. The apple family (pomacee).—This 
family is represented by the apples, pears, quinces, june-berries, 


Choke-cherry (Prunus virginiana), Leaves, 


Y flower raceme, and section of flower at right. 


hawthorns, etc. The members are trees or shrubs. The 
receptacle is somewhat cup-shaped and hollow. The perianth 
and stamens are at first perigynous, but become epigynous 


268 PLANT FAMILIES: DICOTYLEDONS. 


(upon the gyncecium) by the fusion of the receptacle with the 
carpels. The floral formula is thus Ca5,Cos,A10-5-5 or 


Fig. 230. 
Flower of pear. (After Warming.) 


10-10-5,G1-5. The carpels are united, but the styles are free. 
In fruit the united carpels fuse more or less with the receptacle. 

Omit either the strawberry, or the apple, as an exercise, if 
desired. 


Exercise 76. 


480. The strawberry (Fragaria vesca). 

Describe the appearance of the entire plant. What different stems are 
there? What purpose does each kind of stem serve? Sketch and describe a 
leaf. 

The inflorescence.— What is the kind of inflorescence ? 

The flower.—Determine the parts of the flower present. Describe each 
set of members of the flower, naming the kind of calyx and corolla. Are the 
sets of members free? Are the members of each set distinct? To take the 
flower as a whole in its young condition (just opening) what is the relation as 
regards position and elevation of the different sets to each other? Is the 
flower perigynous or hypogynous ? : 

What is the end of the stem called to which the parts of the flower are 
attached ? 

Do all the flowers of the strawberry form fruit? When you have deter- 
mined this, determine the reason if you can. 

The fruit.— What parts of the flower are united to form the fruit? What 
is such a fruit called? What part of the flower forms the fleshy part of the 
fruit? What parts of the flower are united in the seed? What is such a 
seed called ? 


LEGUMINOS4:. 269 


How does seed distribution come about in such plants as the strawberry? 
How are strawberry plants usually propagated ? 
Materials.—Entire plants with runners: flowers ; fruit. 


Exercise 77. 

431. The apple (Pyrus malus). 

Leaves.—Determine the arrangement of the leaves on the shoot ; sketch a 
leaf. 

The inflorescence.—Determine the kind of inflorescence. 

The flower.—Study several flowers to compare the variation in the number 
of the parts or members of the flower. What parts of the flower are present ? 

Make a long section of the flower and sketch showing the parts and their 
relation to each other. 

Determine the number of members in each set ; the relation of the members 
of a set to each other ; the relation of the sets among themselves. Give the 
names which are applied to these relations. 

The fruit.—What parts of the flower are united in the fruit? Make 
longitudinal and cross-sections of an apple, name the parts and show from 
which part of the flower each part of the fruit comes. What is the fruit of an 
apple-tree called ? 

Materials.—Spray of leaves and flowers ; mature fruit. 


OrpDER LEGUMINOSA. 


432, Lesson XIV. The pea family (papilionacee).—This 
family is well represented by the common pea. The flower is 
butterfly-like or papilionaceous, and the showy part is made up 


Fig. 231. 
Details of pea flower ; section of flower, perianth removed to show the diadelphous 
tamens, one single one, and nine in the other group. (From Warming.) 


270 PLANT FAMILIES: DICOTYLEDONS. 


of the five petals. The petals have received distinct names here 
because of the position and form in the flower. At fig. 232 the 
petals are separated and shown in their corresponding positions, 
and the namesare there given. The flower 
is irregular and the parts are in fives, except 
the carpel, which is single. The calyx is 
gamosepalous (coherent), the corolla poly- 
petalous (distinct). The ten stamens are 
in two groups, one separate stamen and 
nine united; they are thus diadelphous 
(two brotherhoods). The fruit forms a pod 
or legume, and at maturity splits along 
Fig. 232. both edges. 

ard ee nee, %08 There are three families in the legume- 
petals forming ‘keel: bearing plants: 1st, including the locusts, 
cassias, etc.; 2d, the pea family, including peas, beans, clovers, 
ground-nuts, or peanuts, vetches, desmodium, etc.; 3d, in- 
cluding the sensitive plants like mimosa. 


Exercise 78. 

433. The pea (Pisum sativum). 

The entire plant.—Describe the entire plant, the branching, the means for 
support (compare different cultivated varieties in respect to size, habit, and 
means for support if practicable). 

The leaf.—Sketch a leaf; name the different parts; what kind of a leaf 
isit? Does the leaf serve any purpose for the mechanical support of the 
plant? How? 

The inflorescence.—What is the kind of inflorescence ? 

The flower. —Is it regular or irregular ? 

The calyx.—Describe the calyx. How many sepals are indicated? Are 
the sepals distinct or coherent? What name is applied to this kind of a calyx? 

The corolla. —What are the relations of the petals to each other? What 
term is applied to indicate this relation ? Sketch a flower, and name the differ- 
ent parts of the corolla; what name is given to such a flower ? 

The stamens (remove the corolla); how many stamens are there ? What 
is their relation to each other? What terms are used to indicate such a re- 
lation of stamens to each other ? 

The pistil.—How many carpels in the pistil? Is it simple or compound? 
Sketch a young pistil, naming the parts, 


MYRTIFLORA. 271 


The fruit.—What parts of the flower are united in the fruit? Describe the 
fruit. What is such a fruit called? How are the seeds freed? What is the 
difference between a fruit and a seed in the pea plant ? 

The clover (trifolium..—If it is desired to study a clover, study one in a 


similar way. 

Nitrogen gatherers. — The pea, 
clovers, etc., are often called nitrogen 
gatherers (see Chapter XV). During 
an excursion let the pupils dig up dif- 
ferent leguminous plants, like the pea, 
clover, lupine, etc., and search for the 
“‘tubercles’’ on their roots, compar- 
ing the form of the tubercles on the 
different kinds of plants. 

Pollination. — If the flowers of cy- 
tisus from a conservatory are at hand 
attempt to press the point of a pencil 
in between the parts of the keel in the 
case of flowers where these parts are 
still closed ; describe the action of the 
stamens in throwing the pollen. How 
could cross-pollination be brought 
about in such a flower by the visits of 
insects ? 

Study the common lupine (Lupinus 
perennis) in the same way. Study the 
pea flower with the same ‘object in 
view; has the pea flower become 
adapted to self-pollination ? 

Material.—Sprays of leaves and 
flowers ; fruit. Material can usually 
be obtained fresh early in the spring 
and for some time later. 


P/E Fig. 233. 
Section of flower 
of (Fnothera. 


Topic VII: Dicotyledons with distinct petals and 
epigynous flowers. 


OrDER MyrTIFLORA. 


(The study of the evening primrose may be omitted.) 
434, Lesson XV. The evening-primrose family (onogracez). 
—In the evening-primrose (cenothera) the flowers are arranged 


272 PLANT FAMILIES: DICOTYLEDONS. 


Fig. 234. 
Evening primrose (Ginothera biennis) showing flower buds, flow d 
(From Kerner and Oliver.) - : ie eit ce 


eo 


ONOGRACEA. 273 


in a loose spike along the end of the stem, each one situated in 
the axil of a leaf-like bract. The flowers of the family are very 
characteristic, as shown here. They are sessile in the axil of 
the bract, and the calyx forms a long tube by the union of the 
sepals, only the end of the tube being divided into the indi- 
vidual parts, showing four lobes. On the edge of the open end 
of the calyx tube are seated the four, somewhat heart-shaped, 
yellowish petals, and here are also seated the eight stamens. 
The four carpels are united into a single pistil within the base 
of the calyx tube and united with it, so that the calyx tube 
seems to be on the end of the pistil. The flowers soon fade 
and fall away from the pistil, and this grows into an elongated 
four-angled pod. Since the lower flowers on the stem are the 


older, we find nearly mature fruit and fresh flowers, with all 


intermediate grades, on the same plant. 

The plants grow by roadsides and in old fields. They are 
from 10cm to a meter or more high (one to five feet). The 
leaves are lanceolate or oblong, toothed and repand on the 
margin. In many of the species of the family the parts of the 
flower are in fours as in the evening primrose, but in others the 
number is variable. 


CHAPTER XLV. 
DICOTYLEDONS (ConrtiNnuED). 


SYMPETALA. 


435. In the remaining families the corolla is gamopelalous, 
that is, the petals are coherent into a more or less well-formed 
tube, though they may be free at the end. For this reason 
they are known as the sympefale. 


Topic VIII: Dicotyledons with united petals, flower 
parts in five whorls. 


Orper BIcornegs. 


436. Lesson XVI. The whortleberry family (vacciniacee). 
—(This study may be omitted.)—The common whortleberry, 
or huckleberry (Gaylussacia resinosa), flowers in May and June. 
The shrubs are from 30cm to 1 meter (1-3 feet) high, and are 
much branched. The leaves are ovate, and when young.are 
more or less clammy from numerous resinous dots, from which 
the plant gets its specific name (resinosa). The flowers are 
borne on separate shoots from the leaves of the same season, 
and hang in one-sided short racemes as shown in fig. 235. 
The calyx is short, five-lobed, and adheres to the ovary. The 
corolla is tubular, at length cylindrical with five short lobes, 
and is whitish in color. The stamens are ten in number, and 
the compound ovary has a single style. The fruit is a rounded 
black, edible berry or drupe, with ten seeds. 

274 


LABIATA. 275 


Topic IX: Dicotyledons with united petals, flower 
parts in four whorls. 


OrpDER TUBIFLORA. 


487. Lesson XVII. The mint family (labiate).—The mint 
family contains a large number of genera and takes its common 
name from the mints, of which there are several species belong- 
ing to the genus mentha. In the figure of the ‘‘ dead-nettle ’’ 


Fig. 235. Fig. 236. 
Whortleberry (Gaylussacia re- Spray of dead-nettle (Laminum am- 
sittosa). plexicaule), leaves and flowers. 


(Lamium amplexicaule), which is also one of the members of 
this family, we see that the lobes of the irregular corolla are 
arranged in such a manner as to suggest two lips, an upper and 
a lower one. From this character of the corolla, which obtains 
in nearly all the members, the family receives its name of 
Labiate. The calyx is five-lobed. The stamens, four in 
number, arise from the tube of the corolla, and converge in 


276 PLANT FAMILIES: DICOTYLEDONS. 


pairs. The ovary is divided: into four lobes, and at the 
maturity of the seed these form four nutlets. The leaves are 


oe rounded, crenate on the margins, the lower 
fy ones petioled and heart-shaped, and the upper 
Ou ones sessile and clasping around the stem 
weg beneath the flower clusters. From the clasp- 


ing character of the upper leaves the plant 


= derives its specific name of amplexicaule. The 


_ Fig-237- == plant occurs in waste places and is rather 
Diagram of lamium 
flower. common. 


Of the two exercises given below one may be omitted. 


Exercise 79. 


488. The catnip (Nepeta cataria).—While the ‘‘dead nettle’’ is used 
here to illustrate the mint family other species may be studied instead. The 
exercise is written for the catnip (Nepeta cataria), « very common weed 
occurring from July to September. If fresh material is not at hand when the 
study is made, dried entire plants, and the flowers in formalin may be used, 
unless it is preferred to use fresh material of some other available species. 
In that case the dead nettle here illustrated, and the exercise, will serve as a 
guide for the study. 

The entire plant.—Note the habit, the character of the branching, the 
shape of the stem, the character of the surface. Note the form and arrange- 
of the leaves. Is the plant annual, biennial, or perennial ? 

The inflorescence.—What is the inflorescence? The flower; the parts 
present, the calyx, form and relation of parts ; the corolla ; form, relation of 
parts ; into what two parts is the corolla divided? the name of the two parts? 
the number of petals in each part? Note the stamens, number, size, position 
in the flower. The pistil; sketch a pistil showing the nutlets, the long style. 

To study the stamens remove a corolla, split it open down one side and 
spread it out on a glass slip and mount in water; or pin it toa cork. Ex- 
amine with a good hand lens, or with the lower power of the microscope. 

Construct the floral diagram. 

Cross-pollination by insects.—Study the adaptations of the flower for this 
purpose. The lower lip is the landing place, and the upper lip is the “ ban- 
ner.’’ If there are color markings on any portion of the flower which serve 
to guide the insect in entering the flower, describe them and note the location. 
With a needle imitate the entrance of an insect into the flower and determine 
the way in which cross-pollination takes place. 


SCROPHULARIACE:. 277 


Compare if possible other members of the mint family in the study of cross- 
pollination. 

Material.—Entire plant with flowers and ripe fruit. If fresh plants are 
not at hand, those that have been pressed and dried may be used for the 
study of the entire plant and of the leaves. The flowers may be preserved in 
formalin. 


ORDER PERSONATA. 


Exercise 80. 


439. The figwort family (scrophulariacer).—Zoad flax (Linaria vul- 
garis).—The toad flax is widely distributed, growing in waste places as a 
weed from June to October. i: 

The entire plant.—Note the short, pale green perennial root stock ; the 
longer erect annual stem ; is it simple or branched? Leaves, form and ar- 
rangement. 

The inflorescence.—The kind of inflorescence. The flower.—What parts 
of the flower are present? Describe the different parts. The calyx.—How 
many sepals indicated? what is the form of the calyx? The corolla.—Form. 
How many petals indicated? Describe the form of the corolla and its parts. 
The stamens.— How many, their position, size? What is the significance of 
the difference in the size of the stamens? The pistil.—Form, parts ; form of 
the ovary ; how many carpels present in the pistil ? 

Study the adaptation of the flower for cross-pollination by the aid of insects ; 
the lower lip of the corolla as a landing place ; since insects are supposed to 
be attracted by bright colors, what portion of the flower serves thus to direct: 
the insect ? 

Note the spur on the corolla, and the nectar inside ; what kinds of insects 
visit this flower? Imitate with the end of a pencil the entrance of an insect 
in a flower and endeavor to make out how cross-pollination takes place. 

Seed distribution.— Examine ripe seed pods, dry some of them, and then 
take some of the dry ones and place in water. Describe the action of the 
pod in scattering the seeds, and the causes. : 

Other members of the family are interesting to compare with the toad flax, 
as the beard tongue (Penstemon pubescens), turtle head (Chelone glabra), 
monkey flower (Mimulus ringens), etc. 

Material.—Entire plants with the underground stems. Flowers and 
fruit. If fresh material cannot be had at the time of the study, dried plants 
(pressed) will answer for the study of the entire plant. Flowers may be pre- 
served in formalin ; fruits dry. 


CHAPTER XLVI. 
DICOTYLEDONS (ConcLupep). 


OrpDER AGGREGATE. 


440. Lesson XX. The composite family (composite).—In 
all the composites, the flowers are grouped (aggregated) into 
“‘heads,’’ as in the sunflower, where each head is made up of 
a great many flowers crowded closely together on a widened 
receptacle. The family is a large one, and is divided into 
several sections according to the kinds of flowers and the differ- 
ent ways in which they are combined in the head. In the 
asters there is one common type illustrated in fig. 238 by the 
Aster nove-anglia. In the aster, as is well shown in the 
figures, the head is composed of two kinds of flowers, the 
tubular flowers and the ray flowers. In the tubular flowers the 
corolla is united to form a slender tube, which is five-notched 
at the end, representing the five petals. In the ray flowers the 
corolla is extended on one side into a strap-shaped expansion. 
Together these strap-shaped corollas form the ‘‘ rays’’ of the 
head. The corolla is split down on one side, which permits 
the end then to expand and form the ‘‘strap.’’ This is a 
ligula, or more correctly speaking a false igula. In fact the 
ray flower is d:/adcate. By counting the ‘‘teeth’’ of the false 
ligula there are found only three, which indicates that the strap 
here is made up of only three parts of the 5-merous corolla. 
The two other limbs of the corolla are rudimentary, or sup- 
pressed, on the opposite side of the tube. True ligulate flowers 
are found in the chicory, dandelion, or in the hieracium, where 
the five points are present on the end of the ligula. 

278 


COMPOSITE. 279 


441. The pappus and syngenecious stamens.—The calyx 
tube in the aster, as in all of the composites, is united with the 
ovary, while the limb is free. 
In the aster, as in many 
others, the limb is divided 
into slender bristles, the pap- 
pus. (In some of the com- 
" posites the pappus is in the 
form of scales.) The stamens 
are united by their anthers 
into a tube (syngenecious) 
which closely surrounds the 
style. (In ambrosia the an- 
thers are sometimes distinct. ) 
The style in pushing through 
brushes out some of the 
pollen from the anthers and 
bears it aloft as in the bell- 
flower, but the stigmatic sur- 
face is not yet mature and 


Fig. 239. 
Head of flowers of Aster nove-angliz. 


There 


Tig. 33. 
Aster nove-angliz. 
expanded, so that close pollination cannot take place. 
The ovary is com- 


are usually no stamens in the ray-flowers, 
posed of two carpels, as is shown by the two styles, but there 
is only one locule, containing an erect, anatropous, ovule. 


280 PLANT FAMILIES: DICOTYLEDONS. 


The floral formula for the composite family then is as follows: 
Ca5, Cos, As, Gz. 


Fig. 240. Fig, 241. Fig. 242. Fig. 243. 


Ray flower of Aster Tubular flower Tubular flower Syngenecious 
nove-angliz. of aster. opened to show syn- stamens opened to 
genecious stamens, show style and two 

stigmas, 


442. Other composites.——The rattlesnake-weed (Hieracium 
venosum) is an example of another type, with only one kind 
of flower in the head, the true ligulate flower. The hawk- 
weed, or devil’s paint-brush (H. aurantia- 
cum) is a related species, which is a 
troublesome weed. The dandelion and 
prickly lettuce are also members of the 
ligulate-flowered composites. A number of 

: the-composites have only tubular flowers, as 
gen as in the thoroughwort (eupatorium) and ever- 
Bowers (Vines) lasting (antennaria). 

443, The composites are the most highly developed plants. 
—tThe extent to which the union of the parts of the flower has 
been carried in the composites, and the close aggregation of 
the flowers in a head, represent the highest stage of evolution 
reached by the flowers of the angiosperms. 


COMPOSIT. 281 


Exercise 81. 


444, The aster (Aster nove-anglie).—(Some other species may be selected 
if it is more convenient.) See Exercise 82. 

The entire plant.—Describe the entire plant; the character of the stem; 
the position of the leaves; their form on different portions of the stem; their 
attachment to the stem. Compare the ‘‘radicle’’ leaves with the stem leaves. 

The inflorescence.—Describe the inflorescence, and the position of the 
flower heads. 

A single head of flowers.— Describe the involucre. What different kinds 
of flowers are present? What is the position of each kind on the head? De- 
termine the approximate number of each kind of flowers ina head. 

The ligulate flowers.—Remove one from the head and sketch it, showing 
the different parts. How many petals are indicated in the strap? How 
many petals are in the tubular portion of the ligulate flower? Is this a true 
ligula? Why? Is the calyx present, and what represents it? Split open 
the corolla tube, and determine whether or not the stamens are present. Is 
the pistil present in the ligulate flower ? 

The tubular flowers.—Describe the corolla. How many petals are indi- 
cated in the corolla tube? What is such a corolla called? 

The stamens.—Split open the corolla tube down one side, and sketch to 
show the position of the stamens, and their relation to each other. Split open 
the anther column, spread it out, and sketch to show the relation of the 
stamens to each other, and the pistil within. 

Material.—Entire plants in flower ; also some of the mature fruit heads: 


Exercise 82. 


445. The goldenrod (solidago).—(As an alternate if desired, for Exer- 
cise 81.) 

If it is desired to study the goldenrod instead of the aster, it will be well 
to make a comparison with the aster, and the account of the aster here given 
will serve as a guide for the study of the goldenrod. ‘The daisy is also a 
good one to compare with the aster, and the outline for the study of the aster 
here given will answer for the basis of such a study. 


Exercise 83. 


446. The dandelion (Taraxacum dens leonis). 

The entire plant —Note the very short stem (the plant is sometimes said to 
be acaulescent, but it has a short stem). Note the thick root; the position of 
the leaves (often called radicle leaves because of their position on the short 
stem so near the roots). Sketch a leaf to show its form, 


282 PLANT FAMILIES: DICOTYLEDONS. 


The inflorescence.— What is the kind of inflorescence? Note the leafless 
stem (flowering scape) which bears the head of flowers. Cut across the 
stem and split it, and then describe its character. 

The involucre.—How many whorls of bracts are there in the involucre? 
Comparing plants in flower and at different stages of maturity, describe the 
different positions of the involucre. 

The flowers.—Are all the flowers strap-shaped ? Note the ligula. Why 
is it a true ligula? Describe and sketch a single flower. 

The calyx.—What represents the calyx? Describe the free portion, or 
limb. Wheat is the insertion of the calyx ? 

The corolla.— What represents the corolla, and how many petals are in- 
dicated ? 

The stamens.—What is the relation of the stamens to each other? What 
is the name applied to such stamens? Sketch a few of the stamens to show 
their relation to each other. 

The pistil.—-How many carpels are represented in the pistil? What is 
the indication of this? What is the relation of the different sets of the flower 
to each other, and what is their insertion? Give the names applied to these 
different relations. 

The fruit.—Comparing the different stages of the ripening seed, describe 
the changes which take place in the different parts of the flower and head. 
What parts of the flower are united in the fruit? What is such a fruit called? 
How many seeds in the fruit ? 

Seed distribution.— How are seeds of the dandelion adapted for seed dis- 
tribution? Take a head of ripe seeds, and blow upon it. Note how the 
seeds float; observe which end falls first upon the ground (see chapter on 
seed distribution in Ecology). 

Cross-pollination.—In some of the composites, as in the daisy, or in the 
sunflower, determine what provision is present for cross-pollination. Do all 
the flowers ‘*blossom’’ at the same time in a single head? Which ones 
blossom first? Do the stamens ripen and emerge from the throat of the 
corolla at the same time as the stigma in the same flower? Why? Com- 
pare the dandelion in these respects. 

Material.—Entire plants, with flowers (they can be obtained all through 
the spring); heads of fruit in different stages of maturity. 


ECOLOGY. 
INTRODUCTION. 


447. Life processes in the individual plant.—In studying 
the phenomena of plant life which relate to the methods of 
absorption and transportation of food to different parts of the 
plant, and the internal processes of metabolism concerned in 
the building up of new plant material, and the formation of 
waste, as well as certain of the growth phenomena and irritable 
properties, we have been dealing largely with the individual 
plant. A study of these life processes we term physiology. 
They relate to the zmmediate conditions of existence and well 
being of the plant. 

448. Form in members of the plant body.—Beyond the very 
simple plants of the lower groups, and a few reduced forms 
among the higher plants, the plant body becomes more or less 
bulky or enlarged, and each cell is so situated that it is unable 
to participate equally in a number, or all, of the life processes. 

’ The plant body therefore becomes more or less differentiated 
into parts, which from the standpoint of physiology are organs 
for the performance of distinct functions. This leads us in 
the complex plant body to recognize form as an important cor- 
relative of function in many cases. The immense variation 
which has, through time, taken place in the development of 
plants has resulted in a great diversity of form even in the 
same members 6f the plant body. Within certain limits, how- 
ever, the form of the plant parts among the individuals of a 
species is the same, and they are inherited by, or handed down 
to, the offspring. 

283 


284 ECOLOGY. 


449, Form as indicating relationship.—Where the form of 
a member is a constant peculiarity of the plants of one kind, 
differences in form among other plants indicate that there are 
other kinds, or species, of plants. So that aside from the rela- 
tion which the members of the plant, as organs, bear to the 
immediate life functions, the form of the members becomes the 
measure of the value of relationships among kinds. The study of 
form in this connection we term morphology. 

450. Relation of physiology and morphology.— While physi- 
ology and morphology are regarded as distinct subjects, still we 
see how they are interrelated when we consider the details of 
one or the other subject. It is in the broader concept that the 
two subjects are fundamentally different. 

451. Form and function in a broader sense than the indi- 
vidual.—Just as the individual life processes relate chiefly to 
the immediate conditions of existence of the plant, and as the 
individualized form of the members relates to the immediate 
conditions of relationship; so the life processes in general, on 
a grand scale or as affected by seasons, or mutual relations, as 
well as form on a grand scale, relate to more extended condi- 
tions of existence, and to relationships, the measure of which 
is not the form of the plant itself, but the form of the plant 
community, showing a relationship of different kinds under like 
conditions of existence. In this sense we are concerned with 
those ‘processes and forms which are influenced by, or lay hold 
on, environment. By the environment is meant all the sur- 
rounding objects, conditions, and forces operating in nature, 
either temporary, seasonal, or permanent. 

452. Mutual and environmental relationships——While we 
are engaged with the study of the life processes concerned 
in nutrition and growth of plants, with the details of form, struc- 
ture, and systematic relationship, we should not overlook the 
mutual relationships which exist among plants in their natural 
habitat, and the phenomena of growth recurring with the 
seasons, and influenced by environment, or due to inherent 


INTRODUCTION. 285 


qualities. By a study of the life histories of plants, their habits 
and behavior under different conditions of environment, we 
shall broaden our concept of nature and cultivate our esthetic, 
observational, and reasoning faculties. The subject is too 
large for full treatment within the limits of a part of an elemen- 
tary book. The way here can only be pointed out, and the few 
examples and illustrations, it is hoped, will serve to open the 
book of nature to the young student, and lead him to study 
some of the problems which are presented by every region. 
This study of plants, in their mutual and environmental rela- 
tionships, is ecology. 

453. Some of the factors of environment.—In carrying on 
studies of this kind one should bear in mind the factors which 
influence plants in these relationships, that is, what are called 
the ecologic factors; in other words, those agencies which make 
up the environmental conditions of plants, all of which play a 
greater or lesser réle in the habit or status of the plant con- 
cerned, and which, acting on all plants concerned, give the 
peculiar color or physiognomy to the plants of a region or of a 
more restricted community. 

Such factors are climate, with its modifying meteorological 
conditions; texture, chemistry, moisture content, covering, 
topography, exposure, etc., of the soil; influence of light and 
heat; of animals, of plants themselves, and so on. 

454. Suggestions for outdoor studies. — For beginning 

classes, where only a small part of the time is available, excur- 
sions can be made from time to time during the year for this 
purpose, taking certain subjects for each excursion. For 
example, in the autumn one may study means for the dissemi- 
nation of seeds, protection of seeds, plant formations, zonal 
‘distribution of plants, formation of early spring flowers, etc. ; 
in the winter, twigs and buds, protection of plants against the 
cold; and in the spring, opening of the buds and flowers, 
pollination, etc., and further studies on plant societies, relation 
of plants to soil, topography, etc. 


286 ECOLOGY. 


455. Topics for ecological study.—Some of the topics for 
ecological’ study and observation which can be taken up by 
beginning classes are suggested here. ‘The order in which they 
may be taken up for study may be dependent to a large extent 
on the time of the year at which the study is made, and also 
upon the nearness of the school to the supply of material. But 
in any place, even in large cities, there are abundant supplies 
of material for several topics, and by foresight preparation can 
be made in advance for others. 


Stupies 1n PERENNIAL SHooTs, the annual growth as determined 
by the ring scars, or position of branches. 

Trees. 

Trees with the main shoot continued through as a central 
trunk, as in the pines, spruces, larches, etc. 

Trees with a deliquescent trunk, where the main shoot is 
lost by continual branching, as in the elm, etc. 

External character of the bark of different trees, and the 
variation in character of the bark of certain species at 
different ages. 

Branching of shoots, different types of, in trees, shrubs. 

Underground shoots, as in certain ferns like the brake, sensi- 
tive fern, where long horizontal shoots are formed, or in 
the mandrake, the toothwort, etc. 

Creeping shoots or runners, or trailing shoots as in the poly- 
pody, the strawberry plant, the clematis, grape vine, club 
mosses, and others. 

Perennial underground shoots which bear aerial annual 
shoots, as in trillium, the mandrake, jack-in-the-pulpit, 
blood-root, etc. Many of these shoots also contain stored 
nutriment for the growth of the annual shoot. 

Stupies or Lear ARRANGEMENT can be made from the bare 
shoots by observing the positions of the leaf scars. 

Stupies oF Bups anp Bup Formation, protection of buds dur- 
ing the winter, opening of the buds. 


INTRODUCTION. 287 


STupDIEs IN THE ReEtation or Prants To Licur. 

Direction of shoots with reference to the source of light; 
compare shoots which have illumination equally on all 
sides with those which are lighted on one side only. 

Direction of branches with reference to the source of light; 
compare the branching of a tree which has grown in an 
open field with one of the same species which has grown 
in, the forest (in the forest the lower limbs die away when 
they are quite small because the overgrowth of foliage at 
the top of the trees shuts out the light); compare also the 
branching of trees at the edge of a forest, or at the edge of 
a clump of trees where one side is strongly lighted and the 
other side is shaded by the adjacent trees. 

Leaf position with reference to access of light can be studied 
during the season when the shoots are clothed with foliage. 
Compare positions of leaves on trees when the foliage is 

dense; the leaves are nearly on the periphery of the tree, 
or at the ends of the branches. Sometimes even in the 
same species, when the foliage is thin at the ends of the 
branches, a great development of leaves and young 
shoots through the centre of the tree takes place. 
Compare ‘position of leaves with reference to position of 
sun at different times of day. On some species the 
leaves are strongly turned, to face the sun, while on 
others the upper leaf surface faces the field of diffused 
light. Compare the compass plant (Lactuca scariola). 
Compare positions of leaves on prostrate stems, and on the 
upright branches of the same. 
Compare the lengths of petioles when leaves are clustered 
at the base of the shoot, or on a short shoot. 
Compare the positions of the flowers on trees and other 
plants with varying density of foliage. 
Stupizs IN THE ReExvaTion or Pants TO Water. (Water is 
one of the most important factors in influencing plant life.) 
During the growing season observe the effect on different 


288 


ECOLOGY. 


plants in the variation of water-supply; for example in dry 

periods when the soil becomes dry, observe how much 

more quickly some plants wilt than others on bright days. 

Observe the difference in the character of the leaves of 

these different plants, and determine what peculiarity of the 

leaf in the one case favors the loss of water, while in the 
other case water is conserved, or the leaf does not lose 
water readily. 

With reference to the adaptations of plants to the giving 
off of water, or of conserving water, Shimper divides 
them into three classes: 

1. The Xerophytes; plants which love dry places, or 
usually grow in dry places. They possess means 
for conserving water, or for checking rapid trans- 
piration. The plants are either perennial or 
annual, and the leaves are not easily wilted. In 
some of the plants the leaves are absent, or rudi- 
mentary or reduced to spines, as in the cacti. 
The larger number of the xerophytes occur in dry 
regions. 

Xerophytic structures. Some of the xerophytic 
structures are thick and succulent stems, or 
leaves; leaves with a thick cuticle, with a thick- 
ened epidermis; covering for the leaf, or stem, in 
the form of hairs or scales; narrow thick leaves; 
inrolled edges of leaves; the stomates are often 
protected by being sunk in deep cavities. 

2. The Hygrophytes; plants which love damp situations, 
or grow in damp or wet situations. They possess 
means for giving off water, or for ready transpira- 
tion; there is a large water content usually in the 
tissues. Hygrophytes are perennial or annual. 
The leaves are easily wilted. 

3. The Tropophytes; the plants usually grow in tem- 
perate regions. They possess means for conserv- 


INTRODUCTION. 289 


ing water at some seasons and for losing water at 
others. The plants are all perennial. The peren- 
nial parts are xeropHhytic, while the annual parts 
are hygrophytic. Examples: trees and shrubs 
which possess foliage leaves in summer and in the 
winter the shoots are devoid of leaves. The plants 
are thus enabled to /urz from one condition to 
another. (The first part of the word /ropophyte 
means to /urn, while the latter part means Plant.) 

Compare such plants as trillium, jack-in-the-pulpit, 

etc., with underground perennial shoots, and aerial 

annual shoots. 

The pines, spruces, etc., are protected from rapid 
transpiration during the winter by having 
narrow and thick leaves, and also by some in- 
ternal changes in the leaf as winter comes on. 

This division of plant forms into classes as xerophytes, hygro- 
phytes, and fropophyfes is often very marked in wide regions, 
The coastal plains and the mountain regions of the tropics are 
characterized by hygrophytes; the steppes, deserts, polar 
regions, and alpine regions of the temperate zones by xero- 
phytes; while the greater part of the North Temperate zone is 
characterized by tropophytes. 

Between these classes there are intermediate forms which 
break down any attempt to draw a hard and fast line between 
them; yet such a classification, even if it is arbitrary, is con- 
venient. Also the plants of one class may occur in regions 
where another class is dominant. For example, the touch-me- 
not (impatiens) is a hygrophyte, and it occurs in the region 
dominated by the tropophytes. The parsley (portulaca), the 
mullein (verbascum) are xerophytes, and they also occur in the 
same region; while the heaths, the labrador tea, etc., which 
occur in sphagnum moors are also xerophytes, and yet occur 
in the region dominated by the tropophytes. (See Chapter 
LIL.) 


290 ECOLOGY. 


STUDIES IN THE RELATION oF PLanTs To SoIL. 

Observations can be made on the plants occurring on differ- 
ent kinds of soil, as sandy, clay, loam, rocky soil, poor or 
rich soil, in waste places, uncared parts of fields or gardens, 
etc. 

One very important condition of the soil is its varying 
physical condition of texture, and the presence of 
various chemical substances, which influence greatly the 
character of the vegetation; but this subject could not 
well form one for study by young students, since a 
knowledge of the constituents of the soil would be 
necessary. 

Warming divides plants into four classes: 

1. Mesophytes, those plants which occupy a middle posi- 

tion with reference to the water-supply. 

2. Hydrophytes, those plants which grow in damp or wet 

situations. 

3. Xerophytes, those plants which grow in dry situa- 

tions. 

4. Halophytes, those plants which grow in soil or water 

which contains an excess of certain salts. 

Some soils contain such an abundance of certain salts that only 
certain plants grow there. These plants are known as halo- 
phytes (salt loving). The salt lands in the great Salt Lake 
basin, the alkaline lands of California, Nebraska, and Dakota 
may be cited as examples. Certain families of plants, like the 
goose-foots, are peculiarly adapted to growing in such soil, 
though there are plants from a number of families which are 
found in such situations. The great amount of salt in the soil 
renders the absorption of water difficult by the plant, so these 
plants are provided with means for checking transpiration, or 
they would wilt. In this respect the halophytes resemble the 
xerophytes, and the structures for checking rapid transpiration 
are similar. ‘The plants growing in the salt water are also 
halophytes, and those which have parts that are constantly out 


INTRODUCTION. 291 


of the water, also possess xerophytic structures for the purpose 

of checking transpiration, 

STUDIES OF PLANTS IN THEIR RELATION TO ANIMALS. 

Studies in cross-pollination by the aid of insects would come 

under this head. 

StupiEs In Porination brought about in other ways. 

Stupigs or Nutrition as shown in parasitic plants, in sym- 
biosis, etc. (See Chapter XV.) 

STuDIES IN THE RELaTion oF Lire Historrgs of plants to sea- 
sonal changes as suggested in Chapter XXXVIII. Com- 
pare in this respect plants which flower at different seasons of 
the year. 

STUDIES IN THE STRUGGLE BETWEEN PxantTs for the occupation 
of the land. (See Chapter XLVIII.) 

Stupies In Soi, Formation by plants. (See Chapter L.) 

Stupies in Zona, Distrisution of plants and in plant com- 
munities. (See Chapter XLIX.) 

STUDIES IN THE ReELaTIon oF Prants To CLimaTE. (See 
Chapter LIT.) 

456. Suggestions.—Brief discussions of a few of these topics 
are given here to suggest how such studies may be carried on- 
with young pupils. For a fuller discussion of the topics 
enumerated above, the student is referred to the author’s larger 
‘* Elementary Botany’’ and to the works dealing more largely 
with the subject of ecology cited in the Appendix. But it 
should be borne in mind that the beginning student cannot in 
a few excursions make any systematic ecological study, since 
some special knowledge of botany would be necessary as a 
foundation. Some of the general truths, however, can be 
observed. 


CHAPTER XLVII. 
SEED DISTRIBUTION. 


457. Means for dissemination of seeds.—During late summer 
or autumn a walk in the woods or a field often convinces us of 
the perfection and variety of means with which plants are pro- 
vided for the dissemination of 
their seeds, especially when we 
discover that several hundred 
seeds or fruits of different plants 


Fig. 245. Fig. 246. 
Bur of bidens or bur-marigold, show- Seed pod of tick-treefoil (desmodium); at 
ing barbed seeds. the right some of the hooks greatly magnified. 


are stealing a ride at our expense and annoyance. The hooks 

and barbs on various seed-pods catch into the hairs of passing 

animals and the seeds may thus be transported considerable 

distances. Among the plants familiar to us, which have such 

contrivances for unlawfully gaining transportation, are the 
292 


SEED DISTRIBUTION. 293 


ibeggar-ticks or stick-tights, or sometimes called bur-marigold 
(bidens), the tick-treefoil (desmodium), or cockle-bur (xan- 
thium), and burdock (arctium). 

458. Dissemination by water.—Other plants like some of 
the sedges, etc., living on the margins of streams and of 
lakes, have seeds which are provided with floats. The wind 
or the flowing of the water transports them often to distant 
points. 

459. Dissemination by animals.—Many plants possess at- 
tractive devices, and offer a substantial reward, as a price for 


Fig. 247. 
Seeds of geum showing the hooklets where the end of the style is kneed. 


the distribution of their seeds. Fruits and berries are devoured 
by birds and other animals; the seeds within, often passing 
unharmed, may be carried long distances. Starchy and albumi- 
nous seeds and grains are also devoured, and while many such 
seeds are destroyed, others are not injured, and finally are 
lodged in suitable places for growth, often remote from the 
original locality.. Thus animals willingly or unwillingly become 
agents in the dissemination of plants over the earth. Man in 


294 ECOLOGY. 


the development of commerce is often responsible for the wide 
distribution of harmful as well as beneficial species. 

460. Mechanisms for ejecting seeds;—Other plants are more 
independent, and mechanisms are employed for violently eject- 
ing seeds from the pod or fruit. The unequal tension of the 
pods of the common vetch (Vicia sativa) when drying causes 
the valves to contract unequally, and on a dry summer day the 
valves twist and pull in opposite directions until they suddenly 


Fig. 248. 
Touch-me-not (Impatiens fulva) ; side and front view of flower below ; above unopened 
pod, and opening to scatter the seed. 


snap apart, and the seeds are thrown forcibly for some distance. 
In the impatiens, or touch-me-not, as it is better known, when 
the pods are ripe, often the least touch, or a pinch, or jar, sets 
the five valves free, they coil up suddenly, and the small seeds 
are whisked for several yards in all directions. During autumn, 
on dry days, the pods of the witch hazel contract unequally, 
and the valves are suddenly spread apart, when the seeds, as 
from a catapult, are hurled away. 

Other plants have learned how useful the ‘‘ wind ’’ may be if 


SEED DISTRIBUTION. 295 


y) 66 


the seeds are provided with “‘ floats, 


parachutes,’’ or winged 


devices which buoy them up as they are whirled along, often 


Fig. 249. 
Lactuca scariola, 


are unbidden as well as unwelcome guests. 


in fig. 249. 


miles away. In 
late spring or early 
summer the pods 
of the willow burst 
open, exposing the 
seeds, each with a 
tuft of white hairs 
making a mass of 
soft down. Asthe 
delicate hairs dry, 
they straighten out 
in a loose spread- 
ing tuft, which frees 
the individual seeds 
from the compact 
mass. Here they 


/ are caught by cur- 


rents of air and 
float off singly or 
in small clouds. 
461. Theprickly 
lettuce.—In late 
summer or early 
autumn the seeds 
of the prickly let- 
tuce (Lactuca sca- 
tiola) are caught 
up from the road- 
sides by the winds, 
and carried to 
fields where they 
This plant is shown 


296 ECOLOGY. 


462. The wild lettuce.—A related species, the wild lettuce 
(Lactuca canadensis) occurs on roadsides and in the borders of 
fields, and is about one meter in height. The heads of small 
yellow or purple flowers are arranged in a loose or branching 
panicle. The flowers are rather inconspicuous, the rays pro- 
jecting but little above the apex of the enveloping involucral 
bracts, which closely press together, forming a flower-head 
more or less flask-shaped. 

At the time of flowering the involucral bracts spread some- 
what at the apex, and the tips of the flowers are a little more 
prominent. As the flowers then wither, the bracts press closely 
together again and the head is closed. As the seeds ripen the 
bracts die, and in drying bend outward and downward, hugging 
the flower stem below, or they fall away. The seeds are thus 
exposed. The dark brown achenes stand over the surface of 
the receptacle, each one tipped with the long slender beak of 
the ovary. The ‘‘ pappus,’’ which is so abundant in many of 
the plants belonging to the composite family, forms here a 
pencil-like tuft at the tip of this long beak. As the involucral 
bracts dry and curve downward, the pappus also dries, and in 
doing so bends downward and stands outward, bristling like the 
spokes of a fairy wheel. It is an interesting coincidence that 
this takes place simultaneously with the pappus of all the seeds 
of a head, so that the ends of the pappus bristles of adjoining 
seeds meet, forming a many-sided dome of a delicate and 
beautiful texture. This causes the beaks of the achenes to be 
crowded apart, and with the leverage thus brought to bear upon 
the achenes they are pried off the receptacle. They are thus in 
a position to be wafted away by the gentlest zephyr, and they 
go sailing away on the wind like a miniature parachute. As 
they come slowly to the ground the seed is thus carefully 
lowered first, so that it touches the ground in a position for 
the end which contains the root of the embryo to come in con- 
tact with the soil. 

463. The milkweed, or silkweed.—The common milkweed, 


SEED DISTRIBUTION. 297 
or silkweed (Asclepias cornuti), so abundant in rich grounds, 
is attractive not only because of the peculiar pendent flower 


Fig. 250. 
Milkweed (Asclepias cornuti); dissemination of seed. 


clusters, but also for the beautiful floats with which it sends its 
seeds skyward, during a puff of wind, to finally lodge on the 
earth. 

464. Means for floating the seeds.—The large boat-shaped, 
tapering pods, in late autumn, are packed with oval, flat- 
tened, brownish seeds, which overlap each other in rows 
like shingles on a roof. These make a pretty picture as 
the pod in drying splits along the suture on the convex 
side, and exposes them to view. The silky tufts of numerous 
long, delicate white hairs on the inner end of each seed, in 


298 ECOLOGY. 


drying, bristle out, and thus lift the seeds out of their en- 
closure, when they are borne, buoyant as vapor, bearing the 
embryo plant, which is to take its place as a contestant in 
the battle for existence. 


Fig. 251. 
Seed distribution of virgin’s bower (clematis). 


465. The virgin’s bower.—The virgin’s bower (Clematis 
virginiana), too, .clambering over fence and shrub, makes a 


SEED DISTRIBUTION. 299 


show of having transformed its exquisite white flower clusters 
into grayish-white puffs, which scatter in the autumn gusts into 
hundreds of arrow-headed, spiral plumes. The achenes have 
plumose styles, and the spiral form of the plume gives a curious 
twist to the falling seed (fig. 251). 


CHAPTER XLVIII. 
STRUGGLE FOR OCCUPATION OF LAND. 


466. Retention of made soil.—In the struggle of plants for 
existence, there are a number of species which stand ready to 
tush in where new opportunities present themselves by changed 
conditions, or by newly made soil. The permanent drainage of 
ponds or marshes brings changed conditions, and the flora there 
undergoes remarkable transformations. The deposits of the 
washings of streams in protected places along the shores, or at 
their mouths, where deltas or lateral plateaus are made by the 
accumulations of soil scoured off the banks of the stream, or 
washed off the fields during rains, make new ground. With 
such banks of newly made ground are deposited seeds carried 
along with the soil, or dropped there by the wind, by birds, or 
other agencies of seed distribution. 

467. Vegetation of sand dunes.—Along the sandy beaches 
of lakes, or of the ocean, drift piles of the fine sand are formed,” 
which often are moved onward by the wind. The surface par- 
ticles are moved onward to the leeward of the drift, and so on. 
The form and location of the sand dune gradually changes. 
Such drifts sometimes slowly but surely march along over soil 
where a rich vegetation grows, and over valuable land. Even 
on these sand dunes there are certain plants which can gain a 
foothold and grow. When a sufficient number obtain a foot- 
hold in such places they retain the sand and prevent the move- 
ment of the dune. 

468. Reforestation of lands.— When by the action of fire or 
wind, or through the agency of man, portions of forests are 

300 


if 


30 


OCCUPATION OF LAND 


Foose 


fA 3 me 
ee ae 


302 ECOLOGY. 


partially or completely destroyed, a new set of conditions is 
presented over these areas. One of the most important is that 
light is admitted where before towering trees permitted but a 
limited and characteristic undergrowth to remain. Hundreds 
of forms, which for years have been dormant, are now awakened 
from their long sleep, and new and recent importations of seeds, 
which are constantly rushing in, spring into existence to fill the 
gap, multiply their numbers, and make more sure the perpetua- 
tion of their kind. 

469. The weaker ones are overcome.—The earliest to appear 
are not always the ones to endure the longest, and a battle 


Pie a ma in Alabama, eee a teense and trees. (Photograph by 
royal takes place during years for supremacy. The weaker 
ones are gradually overcome by the more vigorous, and a new 
crop of trees, which often springs up in such places, finally 
usurps again the domain, in the name of the same or of a 
different species. 

470. Feral plants in neglected fields.\—Domestic plants pro- 


OCCUPATION OF LAND. 303 


ected by man occupy cultivated fields. When cultivation 
eases, or the crop is removed, or the fields are neglected, 
wundreds of species of feral plants, which are constantly spring- 
ag up, now flourish, bear seed, and take more or less complete 


Fig. 254. 
ibandoned field, Alab , self reforested by pines. (Photograph by Prof. P. H. Mell.) 


ossession of the soil. Impoverished land, abandoned by man, 
ecomes nurtured by nature. Weeds, grass, flowers spring up 
. great variety often. Some can thrive but little better than 
1e abandoned crops, while others, peculiarly fitted because of 
ne or another adapted structure or habit, flourish. Crab-grass 


304 ECOLOGY. 


and other low-growing plants often cover and protect the soil 
from the direct rays of the sun, and thus conserve moisture. 


Fig. 255. 
Self-sown white pine in abandoned orchard ; trees 9-20 years old. ‘Near Ithaca. (Photo- 
graph by the author.) : : 


The clovers which spring up here’and there, by the aid of the 
minute organisms in their roots, gather nitrogen. The meli- 
lotus,’ the passion flower, and other deep-rooted plants reach 
down’ to virgin soil and lift up plant food. Each year plant 


4 4 


OCCUPATION OF LAND. 305 


remains are added to, and enrich, the soil. In some places 
grasses, like the broom-sedge (andropogon), succeed the weeds, 
and a turf is formed. 

471. Trees follow weeds and grasses.—Sceeds of trees in the 
mean time find lodgment. During the first few years of their 
growth they are protected by the herbaceous annuals or peren- 
nials. In time they rise above these. Each year adds to their 
height and spread of limb, until eventually forest again stands 
where it was removed years before. In the Piedmont section 
of the Southern States such a view as is presented in fig. 253 
represents how abandoned fields are taken by the broom-sedge, 
to be followed later by pines, and later by a forest as shown in 
fig. 254. 

472. Self-sown white pines—In New York State many 
abandoned hillsides are being reforested slowly by nature with 
the white pine. Fig. 255 represents a group of self-sown pines 
ranging from three to six meters high (10~20 feet), growing up 
in an abandoned orchard near Ithaca. In this reforestation of 
impoverished lands, man can give great assistance by timely 
and proper planting. 


CHAPTER XLIX. 
ZONAL DISTRIBUTION OF PLANTS. 


473, On the margins of lakes or ponds, where the slope is 
gradual from the land into the water, one often has an oppor- 
tunity to study the relation 
of various plants to different 
conditions of soil and water. 
In rowing near the south 
shore of Lake Cayuga, I have 
often been impressed with 
the definite areas occupied 
by certain plants. Figure 
257 is from a photograph, 
taken from the boat, of the 
shore distribution of these 
plants. The most striking 
feature here is the grouping 
of certain kinds of plants in 
definite lines or zones. Here 
the limitations of the zones 
. are quite distinct, so that the 
transition from one zone to 
another is quite abrupt, 
though there is some mixture 
of the kinds at the zone of 
transition, or fension line. 

Fig. 256. 474, Zonal arrangement. 

Sagittaria variabilis, —This arrangement of plants 

under such environmental influences is termed ‘‘ zonal distribution 

of plants.’’ The slope where this photograph was taken is so 
306 


ZONAL DISTRIBUTION OF PLANTS. 307 


308 ECOLOGY. 


symmetrical that plants suited by their long habit of growing at 
certain depths of water, or in soil of a certain moisture content, 
are readily drawn into zones parallel with the shore line. 


Fig. 258. 
Sagittaria variabilis, 


Several zones can be readily made out in this region; two of 
them at least do not show in the picture since they are sub- 
merged. 

475. Submerged zones in the foreground.—If we treat of the 


ZONAL DISTRIBUTION OF PLANTS. 309 


two submerged zones, the first one is in the rear of the point 
from where the photograph was taken, and consists of extensive 
areas of chara in four to five meters of water. The second zone 


Fig. 259. 
Sagittaria heterophylla. Often forms a zone just outside of the Sagittaria variabilis, 


then is in the water shown in the foreground of the picture. 
The plants here are also submerged, or only a small portion 
reaches the surface of the water, and so the zone does not 


310 ECOLOGY. 


show. In this zone occurs the curious Vallesneria spiralis, 
with its corkscrew flower stem, and various potamogetons. 

476. The visible zones.—In the third zone, or the first one 
which shows in the picture, are great masses of the arrow-leaf 
(sagittaria) so variable in the form of its leaves. Next is the 
fourth zone, made up here chiefly of bullrushes (scirpus), and 
occasionally are clumps of the cattail flag (typha). Behind 
this is the fifth zone, only to be distinguished at this distance 
by the bright flower heads of the boneset (Eupatorium perfolia- 
tum) and joepye-weed (Eupatorium purpureum), and the blue 
vervain (Verbena hastata), which occurs on the land. Willows, 
make a compact and distinct sixth zone, while at the right, the 
oaks on the hillside beyond form a seventh zone, and still 
farther back is a zone of white pines, making the eighth. 


CHAPTER L. 


SOIL FORMATION IN ROCKY REGIONS AND 
IN MOORS. 


Lichens. 


477. The lichen, parmelia.—Many of the lichens are small 
and inconspicuous. They often appear only as bits of color 
on tree trunk or rock. One of the conspicuous ones on stones 
lying on the ground is the grayish-green thallus of Parmelia 
contigua (fig. 260). Its pretty, flattened, forking lobes ra- 
diate in all directions, advancing at the margin, and covering 
year by year more and more of the stone surface. Numerous 
cup-shaped fruit bodies (apothecia) are scattered over the 
central area. The thallus clings closely to the rock surface by 
numerous holdfasts from the under side, which penetrate minute 
crevices of the rock. The lichen derives its food from the air 
and water. By its closely fitting habit it retains in contact with 
the rock certain acids formed by the plant in growth, or in the 
decay of the older parts, which slowly disintegrate the surface 
of the rock. These disintegrated particles of the rock, mingled 
with the lichen débris, add to the soil in those localities. 

478. Lichens are among the pioneers in soil making.—The 
habit which many lichens have of flourishing on the’ bare rocks 
fits them to be among the pioneers in the formation of soil in 
rocky regions which have recently become bared of ice or snow. 
The retreat of glaciers from peaks long scoured by ice, or the 
unloading of broken rocks along its melting edge, exposes the 
rocks to the weathering action of the different elements. Now 

311 


312 ECOLOGY. 


the lichens lay hold on them and invest them with fantastic 
figures of varied color. Disintegrating rock, débris of plants 
and animals, join to form the virgin soil. Certain of the blue- 
green alga, as well as some of the mosses, are able to gain a 
foothold on rocks and assist in this process of soil formation, 


Fig. 260. 
Rock lichen (Parmelia contigua). 


A view of rocks thrown down by the melting and retreating 
edge of a glacier in Greenland is shown in fig. 261. These 
rocks at the time the photograph was taken had no plant life 
onthem., At other places in the vicinity of this glacier, rocks 


SOIL FORMATION: ROCK DISINTEGRATION. 313 


longer uncovered by ice were being covered by plant life. One 
‘of the Greenland rock lichens is shown in fig. 262. 

479. Other plants of rocky regions,—Certain of the higher 
plants also find means of attachment to the bare rocks of the 


Fig. 261. 
Edge of glacier in Greenland, showing freshly deposited rocks. (From Prof. R.S. Tarr.) 


arctic and mountain regions. The roots penetrate into narrow 
crevices in the rock, and are able to draw on the water which is 
elevated by capillarity. Such plants, however, which live on 
bare rocks, whether in the arctic or in mountain regions, have 


314 ECOLOGY. 


leaves which enable them to endure long periods of drought. 
These plants have either succulent leaves like certain of the 
stone-crops (sedum), or small thick leaves which are closely 
overlapped as in the Saxifraga oppositifolia. 

Few of us, unfortunately, can make the trip to the arctic 
regions to study these interesting plants which play such an 


Fig. 262, 
Rock lichen (umbilicaria) from Greenland. 


important réle in the economy of nature. Rocky places, how- 
ever, or loose stones are common nearer home. Observation 
of their flora, and the means by which such plants derive nutri- 
ment, store moisture, or protect themselves from drought, will 
well repay outdoor excursions, 


SOIL FORMATION: ROCK DISINTEGRATION. 315 


Fig. 263, 
Atoll moor, showing central pond, elevated ring. and ditch at original shore line. 


Near Tthaca 


(Fram nhatooranh hw the anthor \ 


316 ECOLOGY. 


480. Filling of ponds by plants——Not only are plants im- 
portant agencies in the formation of soil in rocky regions, they 
are slowly but surely playing a part in the changes of soil and 
in the topography of certain regions. This is very well marked 
in the region of small ponds, where the bottom slopes gradually 
out to the deeper water in the centre. Striking examples are 
sometimes found where the surface of the country is very 
broken or hilly with shallow basins intervening. In what are 
termed morainic regions, the scene of the activity of ancient 
glaciers, or in the mountainous districts, we have opportunities 
for studying plant formations, which slowly, to be sure, but 
nevertheless certainly, fill in partly or completely these basins, 
so that ‘the water is confined to narrow limits, or is entirely 
replaced by plant remains in various stages of disintegration, 
upon which a characteristic flora appears. 

481. A plant atoll.—In the morainic regions of central New 
York there are some interesting and striking examples of the 
effects of plants on the topography of small and shallow basins. 
These formations sometimes take the shape of “‘ atolls,’’ though 
plants, and not corals, are the chief agencies in their gradual 
evolution. Fig. 263 is from a photograph of one of these plant 
atolls about 15 miles from Ithaca, N. Y., along the line of the 
E. C. & N. R. R. near a former flag station known as Chicago. 
The basin here shown is surrounded by three hills, and is 
formed by the union of their bases, thus forming a pond with 
no outlet. 

482. Topography of the atoll moor.—The entire basin was 
once a large pond, which has become nearly filled by the 
growth of a vegetation characteristic of such regions. Now 
only a small, nearly circular, central pond remains, while 
entirely around the edge of the earlier basin is a ditch, in many 
places with from 30-60¢em. of water. There is a broad zone of 
land then lying between the central pond and the marginal 
ditch. Just inside of the ring formed by the ditch is an elevated 
ring extending all around, which is higher than any other part 


SOIL FORMATION: ROCK DISINTEGRATION. 317 


of the atoll. On a portion of this ring grow certain grasses and 
carices. The soil for some depth shows a wet peat made up of 
decaying grasses, carices, and much peat moss (sphagnum). 
In some places one element seems to predominate, and in other 
cases another element. On some portions of the outer ring are 
shrubs one to three meters in height, and occasionally small 
trees have gained a foothold. 

Next inside of this belt is a broad, level zone, with Carex 
filiformis, other carices, grasses, with a few dicotyledons. 
Intermingled are various mosses and much sphagnum. The 
soil formation underneath contains remains of carices, grasses, 
and sphagnum. This intermediate zone is not a homogeneous 
one. At certain places are extensive areas in which Carex 
filiformis predominates, while in another place another carex, 
or grasses predominate. 

483. A floating inner zone.—But the innermost zone, that 
which borders on the water, is in a large measure made up of 
the leather-leaf shrub, cassandra, and is quite homogeneous. 
The dense zone of this shrub gives the elevated appearance to 
the atoll immediately around the central pond, and the 
cassandra is nearly one meter in height, the ‘‘ ground ’’ being 
but little above the level of the water. As one approaches 
this zone, the ground yields, and by swinging up and down, 
waves pass over a considerable area. From this we know that 
underneath the mat of living and recent vegetation there is 
water, or very thin mud, so that a portion of this zone is 
** floating. ’’ 

The inner, or cassandra, zone is more unstable, that is, it is 
all ‘‘ afloat,’’ though firmly anchored to the intermediate zone. 
The roots of the shrubs interlace throughout the zone, firmly 
anchoring all parts together, so that the wind cannot break it 
up. Between the tufts of the cassandra are often numerous 
open places, so that the water or thin mud on which the zone 
floats reaches the surface, and one must exercise care in walk- 
ing to prevent a disagreeable plunge. No resistance is offered 


ECOLOGY. 


318 


(‘royyne a3 Aq yderdojoyg) 


*puod [esque9 03 YIP [eujsAeUl WoIy pur] apEUL Jo SouOZ PoyBAI]a OA} BUIMOYS ‘100U []OJe JO SPs 9UQ 
*boz “SI 


SOIL FORMATION: ROCK DISINTEGRATION. 319 


to a pole two or three meters long in thrusting it down these 
holes. Giasses, carices, mosses, sphagnum, and occasionally 
moor-loving dicotyledons occur, anchored for the most part 
about the roots of the cassandra. Standing at the inner margin 
of the cassandra zone, one can see the mud, resembling a black 
ooze, formed of the titrated plant remains, which have floated 
out from the bottom of the older formations. In some places 
this lies very near the surface, and then certain aquatic plants 
like bidens, and others, find a footing. Upon this black ooze 
the formation can continue to encroach upon the central pond. 
Agitated by the wind, more and more of the ooze passes out- 
ward, so that in time there isa likelihood that the pond will 
cease to exist, yielding, as it has in other places, the right of 
possession to the contentious vegetation. 

484, How was the atoll formed ?—In the early formation of 
the atoll, it is possible that certain of the water-loving carices 
and grasses began to grow some distance (three to four meters) 
from the shore, where the water was of a depth suited to their 
habit. The stools of these plants gradually came nearer the 
surface of the water. As they approach the surface, other 
plants, not so strong-rooted, like mosses, sphagnum, etc., find 
anchorage, and are also protected to some extent from the 
direct rays of sunlight. Partial disintegration of the dead plant 
parts and mingling with the soil gradually fill on the inside of 
the zone, so that the depth of the water there becomes less. 
Now the zone of the carices can be extended inward. 

The continued growth of the sphagnum and the dying away 
of the lower part of the plant add to the bulk of the plant 
remains in the zone, and finally quite a firm ground is formed, 
shutting off the shallow water near the shore from the deeper 
water of the pond. As time goes on other plants enter and 
complicate the formation, and even make new ones, as when 
the cassandra takes possession. 

The original pond here was rather oblong, and one end possi- 
bly much shallower than the other, so that it filled in much 


320 ECOLOGY. 


more rapidly, leaving the central pond at the east end. Over 
a portion of the west end there is an extensive cassandra forma- 
tion, with some ledum (labrador tea), but separated from the 
circular cassandra zone by an intermediate zone. In this end- 
cassandra formation other shrubs, and white pines five to fifteen 
years old, are gaining a foothold, and in a quarter of a century 
or more, if left undisturbed, one may expect considerable 
changes in the flora of this atoll. It is possible that a rise of 
the water for a number of years when the earlier zones were 
floating accounts for the circular elevation and atoll forma- 
tion, or that the dense shade from forest trees years ago may 
have checked the growth of plants in the margin, thus leaving 
a marginal depression. 

485. A black-spruce moor.—A somewhat similar but more 
advanced plant formation occurs east of Freeville, N. Y., and 
about nine miles distant from Ithaca. The centre of the basin, 
which was perhaps shallower than the former one, has become 
completely filled, and all of the central formation is more 
elevated than the margin by the shore of the basin. All around 
the margin in wet weather the ground is more or less sub- 
merged, while all the central portion is so elevated that the 
numerous stools or hummocks of grasses like eriophorum, with 
its white tufts sparkling in the sunlight like a firmament of 
stars, shrubs like cassandra, pyrus, nemopanthes, etc., support 
one in walking above the water which rises in the intervening 
spaces. Sphagnum, polytrichum, and other mosses grow, 
especially in the stools of the other plants, where they now are 
shaded by the larger growth, and in drier seasons catch the 
water which trickles down during rain. 

Years ago the forest encroached on this formation, and trees 
of the hemlock-spruce, black spruce, larch, etc., ot consider- 
able size gained a footing, first along the margin, then along 
the more elevated zone a short distance within. The black 
spruce trees spread all over the centre of the formation, attain- 
ing a height of one to six or eight meters, while the trees of the 


SOIL FORMATION: ROCK DISINTEGRATION. 321 


marginal zone 
where they first 
entered, and the 
ground is some- 
what more eleva- 
ted, attained a 
much greater 
height. 

486. Fall of 
the trees on the 
marginal zone 
when the wind 
break was re 
moved.—T hese 
large trees of the 
marginal zone, 
though they were 
rooted to a great 
extent in loose 
soil, nevertheless 
were protected 
from winds by the 
forests on the sur- 
rounding hills. 
When, however, 
these hills on three 
sides were cleared 
or cultivation the 
vind had full 
weep, and many 
f the large trees 
vere uprooted by 
he force of the 
ales. This view 
3; supported by the 
ict that the west- 


‘Soz Sty 
“peep [1e Ajavou a1jua0 aya ur aonidg ‘durems sonids yor 


322 ECOLOGY. 


ern hill is still covered by forest, and large spruce trees of the 
marginal zone are still standing, though several were up-rooted 
September, 1896, during a fierce southeastern gale, the wind 
from this direction having full play upon them. 

487. Dying of the spruce of the central area.—This removal 
of the forests from the surrounding hills very likely had its 
influence in hastening the melting of the winter snows on the 
hills, so that excessive quantities of water from this source 


Fig. 266. 
Dying black spruce in moor. (Photograph by the author.) 


rushed quickly down into the swamp, flooding it at certain 
seasons much higher than the normal high-water mark during 
former times, when the hills were forest-covered. Also during 
rains the water would now rush quickly down into the swamp, 
flooding it at these times. This greater quantity of water has 
had its effect, probably, in causing many of the young spruces 
over the centre of the formation to die off. 


SOIL FORMATION: ROCK DISINTEGRATION. 323 


488. Effect of fire——This may also have been hastened by 
fires which would now more often sweep over the swamp during 
dry seasons. In partial evidence of this are many young spruce 
trees with scars near the ground where the bark has been 
destroyed. This gives admittance to wood-boring insects which 
farther aid in the process of weakening and debilitating the 
trees. The dying off of the lower limbs of these marsh spruces 
suggests the action of fire, as well as excessive moisture at 
times. Many of them now present only a small convex top of 
living branches. It is interesting to observe the gradation in 
this respect in different trees. 

489. Weird aspect of dead spruces.—The weird aspect pre- 
sented by a clump of these dying young spruce trees is height- 
ened also by the changes in the form of the branches as they 
die. The living branches have a graceful sigmoid sweep with 
their free ends curving upwards as in many conifers, As the 
branches die, the free ends curve downward more and more, all 
gradations being presented in a single tree. A group of such 
dying spruce trees is shown in fig. 266. Some have been long 
dead; only the knotted, weather-beaten trunks still remain 
tottering to their final condition. Others with leafless, dried, 
sprawling branches go swirling with every wind, while a few 
struggle on in the presence of these untoward conditions. 

490. Other morainic moors—In other basins, where the 
hills on all sides are still forest-clad, more equable temperature 
and moisture conditions are conserved. This permits plants to 
flourish here which in the exposed basins are disappearing from 
the formations or-only leading a miserable existence. . This is 
strikingly true of some sphagnum formations. In the atoll _ 
formation described the evidence suggests that sphagnum 
formerly played a more active part in the evolution of that type 
of moor than has been the case since the hills were denuded of 
their trees. So also in the spruce moor, sphagnum probably 
was at one time a prominent factor in the formation of the early 
vegetation. But excessive drought during certain seasons, and 


324 


ECOLOGY. 


full exposure to the sun and wind, have served to lessen its 
influence and importance. But where protected from the 


Fig. 267. 
Two fruiting plants of sphagnum. 
(From Kerner and Oliver,) 


wind, to a large extent from the 
heat of the sun, and supplied with 
a suitable moisture condition, the 
sphagnum flourishes. It grows 
either alone in shallow water, en- 
croaching more and more on the 
centre of the basin, or follows after 
and anchors among water-loving 
grasses and carices. In some cases 
it may thus largely cover such earlier 
formations. An examination of the 
sphagnum plant shows us how well it 
is adapted to flourish under such con- 
ditions. The main axis of the plant 
bears lateral branches nearly at right 
angles, but with a graceful downward 
sweep at the extremity. These pri- 
mary lateral branches bear secondary 
branches, which arise, usually several, 
from near the point of attachment 
to the main axis. They hang down- 
ward, overlap on those below, and’ 
completely cover the main axis or 
stem. The leaves of sphagnum are 
peculiarly adapted for the purpose of 
taking up quantities of water. Not 
all the cells of the leaf are green, 
but alternate rows of cells become 
broadened, lose their chlorophyll, 
and their protoplasm collapses on the 
inner faces of the cell walls in such 


a way as to form thickened lines, giving a peculiar sculpturing 
effect to them. Perforations also take place in the walls. These 


SOIL FORMATION: ROCK DISINTEGRATION. 325 


empty cells absorb large quantities of water, and by capillarity 
it is lifted on from one cell to another. These pendent branches, 
then, which envelop the sphagnum stem, lift water up from the 


Fig. 268. 
Where isoetes grows A small morainic basin near Ithaca. (Photograph by the author.) 


moist substratum to supply the leaves and growing parts of the 
plant which are at the upper extremity. 

491. Increase each year.— Year by year the extension of the 
sphagnum increases slowly upward by growth of the ends of the 


326 ECOLOGY. 


individual plants, while the older portions below die off, partly 
disintegrate, and pass over into the increasing solidity and bulk 
of the peat. It thus happens sometimes that the centres of 


Ee 


Fig. 269. 
Cypress knees, Mississippi. (Photograph by H. von Schrenk.) 

such basins or moors are more elevated than the margins, 
because here a greater amount of water exists in the depths 
which is pumped up for use by the plants themselves. Such a 
formation is sometimes called a ‘‘ high moor.’’ 

492. Change in form.—Because of the peculiar topographic 
features of these basins, together with the conditions of mois- 
ture, etc., changes in their form are quite readily observed. 


, 


SOIL FORMATION: ROCK DISINTEGRATION. 327 


But no less important are the influences of plants on soil con- 
ditions on the hills, and in more level areas. Old plant parts, 
and plant remains, by decay add to the bulk, fertility, and 
changing texture and physical condition of the soil. 

493. The bald cypress (Taxodium distichum).—Very char- 
acteristic are the formations presented by the forests of the bald 
cypress of the South, which grows in swampy or marshy places. 
The ‘‘knees’’ on the roots of this cypress make grotesque 
figures in the cypress forest. These take the form of upright, 
columnar outgrowths, broader at the base or point of attach- 
ment to the horizontal root, and possess a fancied resemblance 
to a knee. These knees are said to occur at points on the 
horizontal root above and opposite the point where a root 
branch extends downward into the soft marsh soil. They thus 
give strength to the horizontal root at the point of attachment 
of the branch which penetrates into the soft soil, and during 
gales they hold these root branches more rigidly in position 
than would be the case if the horizontal root could easily bend 
at this point. The knees thus are supposed by some to 
strengthen the anchor formed by the root in the loose soil. 
Their development may be the result of mechanical irritation 
at these points on the horizontal root, brought about by the 
strain on the roots from the swaying of the tree. Others regard 
them as organs for aerating the portions of the root system 
which are usually submerged in water or wet soil, and in this 
sense the knees are sometimes termed pneumatophores. The 
knees catch and hold floating plant remains during floods, and 
by the decay of this débris the fertility of the soil is increased. 


CHAPTER LI. 
PLANT COMMUNITIES: SEASONAL CHANGES. 


494, Relations of plants.—One of the interesting subjects 
for observation in the study of the habits and haunts of plants 
is the relation of plants to each other in communities. In the 
topography of the moors, and of the land near and on the 
margins of bodies of water, we have seen how the adaptation 
of plants to certain moisture conditions of the soil, and to 
varying depths of the water, causes those of a like habit in this 
respect to be arranged in definite zones. Often there is a pre- 
dominating species in a given zone, while again there may be 
several occupying the same zone, more or less equally sharing 
the occupation. Many times one species is the dominant form, 
while several others exist by sufférance. 

495. Plants of widely different groups may exist in the 
same community.—So it is that plants of widely different rela- 
tionships have become adapted to grow under almost identical 
environmental conditions. The reed or grass growing in the 
water is often accompanied by floating mats of filamentous algz 
like spirogyra, zygnema; or other species, as cedogonium, coleo- 
chete, attach themselves to these higher lords of creation; while 
desmids find a lodging place on their surface or entangled in 
the meshes of the other alge. Chara also is often an accom- 
paniment in such plant communities, and water-loving mosses, 
liverworts, and fern-like plants as marsilia. Thus the widest 
range of plant life, from the simple diatom or monad to the 
complex flowering plant, may, by normal habit or adapted 
form, live side by side, each able to hold its place in the com- 
munity. 

328 


PLANT COMMUNITIES: SEASONAL CHANGES. 329 


In field or forest, along glade or glen, on mountain slope or 
in desert regions, similar relationships of plants in communities 
are manifest. The seasons, too, seem to vegetate, blossom, 
and fruit, for in the same locality there is a succession of differ- 
ent forms, the later ones coming on as the earlier ones dis- 
appear. 

496. Seasonal succession in plant communities. — The 
wooded slopes in springtime teem with trillium, dentaria, 


Fig. 270. 
Azalea (Rhododendron nudicaulis). 


podophyllum, and other vernal blossoms, while on the steeper 
hillsides the early saxifrage is to be found. In the rocky por- 
tions of the glen, which is aiso a favorite lodgment for this 
pretty, white saxifrage, the wild columbine loves to linger and 
dangle its spurred flowers, The lichen-colored ledge is wreathed 


330 ECOLOGY. 


Fig. 271. 
Walking fern, climbing down a hillside. 


PLANT COMMUNITIES: SEASONAL CHANGES. 331 


with moss and fern. On the partly sunlit slopes the clusters of 
azalea are radiant with blossoms, while here and there the shad- 
bush, or service-berry (amelanchier), with its mass of white 
flower-sprays, overhangs some cliff, and the cockspur thorn 
(crateegus) vies with it in the profusion of floral display. Near 
by sheets of water pour themselves unceasingly on the rocks 
below, scattering spray on the thirsty marchantia. Out from 
the steep slopes above rise the graceful sprays of the yew (taxus), 


Fig. 272. 
Spray of kalmia flowers. 


shaded by the towering hemlock spruces. The ‘‘ walking-fern ’’ 
here, holding fast above, climbs downward by long graceful 
strides. 

497. Change in color with the season.—But the scene shifts, 
and while these flowers cast their beauty for the season, others 
put on their glory. The flowering dogwood spreads its decep- 


332 ECOLOGY. 


tive bracts as a halo around the clusters of insignificant flowers. 
The laurel (kalmia) with its clusters of fluted pinkish blossoms 
is a joy only too brief. Smaller and less pretentious ones 
abound, like the whortleberries, amphicarpza, bush-clover 
(lespedeza), sarsaparilla, and so on. 

498. Autumn plants.—In the autumn the glen is clothed 
with another robe of beauty. With the fall of the ‘‘ sere and 
‘yellow leaf,’’ golden-rod and aster still linger long in beauty 


Fig. 273. 
Spray of witch-hazel (hamamelis) with flowers; section of flower below. 


and profusion. When the leaves have fallen the witch-hazel 
(hamamelis) begins to flower, and the snows begin to come 
before it has finished spreading its curled yellow petals. 

499. The landscape a changing panorama.—tIn our tem- 
perate regions the landscape is a changing panorama; forest 
and field, clothed with a changing verdure, don and doff their 
foliage with a precision that suggests a self-regulating mechan- 
ism, 

In the glad new spring the mild warmth of the sun stirs the 
dormant life to renewed activity. With the warming up of the 
soil, root absorption again begins, and myriads of tiny root 
hairs pump up watery solutions of nutriment and various salts, 


PLANT COMMUNITIES; SEASONAL CHANGES. 333 


These are carried to the now swelling buds where formative 
processes and growth elongate the shoot and expand the leaf. 
Buds long wrapped in winter. sleep toss back the protecting 
scales. In a multitude of ways the different shrubs and trees 


Fig. 274. 
Opening buds of hickory. 


now discard the winter armature which has served so good a 
purpose, and tiny bud leaves show a multitude of variations 
from simple bud scale to perfect leaf, a remarkable diversifica- 
tion in which the plant from lateral members of the stem forms 


334 ECOLOGY. 


organs to serve such a variety of purpose under such diametri- 
cally opposed environmental conditions. 
500. Refoliation of bare forests in spring.—There is a 


Fig. 275. 
Austrian pine, showing young growth of branches in early spring. 


certain charm watching the refoliation of the bare forests, when 
the cool gray and brown tints are slowly succeeded by the light 


PLANT COMMUNITIES: SEASONAL CHANGES. 335 


yellow-green of the young leaves, which presents to us a warm- 
ing glow of color. Then the snow-clad fields change to gray, 
and soon are enveloped in a living sea of color. The quiet 
hum of myriads of opening buds and flowers in harmony with 
the general awakening of nature, and the trickling streamlets 
which unite into the gurgling brooks, makes sweet music to 
our attentive minds. 

501. Contrast of color in evergreens.—The evergreens dis- 
play a striking contrast of color. The leafy, fan-shaped 
branches of the hemlock-spruce (tsuga) are fringed with the 
light green of the new growth. The pines lift up numbers of 
cylindrical shoots, with the leaf fascicles for a time sheathed in 
the whitened scales, while the shoots are tipped with the brown 
or flame-colored female flowers, reminding one of a Christmas 
tree lighted with numerous candles. The numerous clusters of 
staminate flowers suggest the bundles of toys and gifts, and one 
inquires if this beautiful aspect of some pines when putting on 
their new growth did not suggest the idea of the Christmas tree 
at yule time. 

502. The summer tints are more subdued.—As summer time 
draws on the new needles of the pine are unsheathed, the light 
green tints of the forest are succeeded by darker and subdued 
colors, which better protect the living substance from the 
intense light and heat of midsummer. The physiological 
processes for which the leaf is fitted go on, and formative 
materials are evolved in the countless chlorophyll bodies and 
transported to growing regions, or stored for future use. In 
transpiration the leaf is the terminus of the great water current 
started by the roots. Here the nutrient materials, for which 
the water serves as a vehicle, are held back, while the surplus 
water evaporates into the air in volumes which surprise us when 
we know that it is unseen. 

503. Autumn colors.—As summer is succeeded by autumn, 
a series of automatic processes goes on in the plant which fits 
it for its long winter rest again. Long before the frosts appear, 


336 ECOLOGY. 


here and there the older leaves of certain shrubs lose more or 
less of the green color and take on livelier tints. With the 
disintegration of the chlorophyll bodies, other colors, which in 
some cases were masked by the green, are uncovered. In other 
cases decomposition products result in the formation of new 
colors. These coloring substances to some extent absorb the 
sun’s rays, so that much of the nitrogenous substances in the 
leaf may not be destroyed, but may pass slowly back into the 
stem and be stored for future use. 

504, Fall of the leaf.i—The gorgeous display of color, then, 
which the leaves of many trees and shrubs put on is one of the 
many useful adaptations of plants. While this is going on in 
deciduous trees, the petiole of the leaf near its point of attach- 
ment to the stem is preparing to cut loose from the latter by 
forming what is called a separative layer of tissue. At this 
point the cells in a ring around the central vascular bundle 
grow rapidly so as to unduly strain the central tissue and 
epidermis, making it brittle. In this condition a hght puff of 
wind whirls them away in eddies to-the ground. The frosts of 
autumn assist in the separation of the leaf from the stem, but 
play no part in the coloration of the leaf. 

As the cold weather of autumn and winter draws slowly on, 
these trees and shrubs cast off their leaves, and thus get rid of 
the extensive transpiration surface, or in some cases the dead 
leaves may cling for quite a long period to the trees. However, 
in the death and fall of the leaves of these deciduous trees and 
shrubs, or the dying back of the aerial shoots of perennial 
herbaceous plants, there is a most useful adaptation of the 
plant to lay aside, for the cold period, its extensive transpira- 
tion surface. For while the soil is too cool for root absorption, 
should transpiration go on rapidly, as would happen if the leaf 
surface remained in a condition for evaporation, the plants 
would lose all their water and dry up. 


CHAPTER LII. 
ADAPTATION OF PLANTS TO CLIMATE. 


505. Some characteristics of desert vegetation.—One of the 
important factors in plant form and distribution is that of 
clmate, which is modified by varying conditions, as tempera- 
ture, humidity of the air, dryness, etc. In desert regions where 
the air and soil are very dry, and plants are subject to long 
periods of drought, there is a very characteristic vegetation, and 
a variety of forms have become adapted to resist the drying ° 
action of the climate. 

Some of the plants, especially the larger ones, have very suc- 
culent stems or trunks, or they are more or less expanded but 
thickened, while the leaves are reduced to mere spines or hairs, 
as in the cacti. If plants in desert regions had thin and broadly 
expanded leaves, transpiration would be so rapid, and so great, 
as to kill them. In these succulent stems there is a propor- 
tionately small surface area exposed, so that transpiration is 
reduced. The chlorophyll resides here in the stems, and they 
function as foliage leaves in many other plants do. 

Other plants of the desert, which do not have succulent 
stems, are provided with closely appressed and small, thick, 
scale-like leaves. The leaves in many of these plants have an 
epidermis of several layers of cells, so that transpiration does 
not take place so rapidly. In addition to this the stomata are 
sunk in pits, or cavities, so that the guard cells are not so 
exposed to the drying action of currents of air at the surface. 

In still other cases the leaves and stems are covered with a 
dense felt of hairs which serves as a cushion to protect them 

337 


338 ECOLOGY. 


from the direct rays of the sun, and also from the fierce blast» 
of dry air which frequently sweep over these regions. The hairs 
are so close, and so interwoven, that the air caught in the 
interstices is not easily displaced, and the leaves are not then 
subject to the drying effects of the passing winds. 

506. Some plants of temperate regions possess characters of 
desert vegetation.—Even in temperate regions in localities 
where the climate is more equable, certain plants, strangely, are 
similarly modified, or provided with protecting armor. The 
common purslane (portulaca) is an example of a succulent 
‘plant, and we know how well it is able to resist periods of 
drought, even when cut free from the soil. With the oncoming 
of rains it revives, and starts new growth, while in wet weather 
cutting it free from its roots scarcely interferes with its growth. 

Similarly the common mullein (Verbascum thapsus), the 
leaves and stems of which are so densely covered with stellate 
hairs, is able to resist dry periods. One can see how efficient 
this panoply of trichomes is by immersing the leaves in water. 
It is very difficult to remove the air from the interstices of the 
interwoven trichomes so as to wet the epidermis. 

507. Alpine plants with desert characteristics.—Alpine 
plants (those on high mountains), as well as arctic plants, are 
similarly modified, having usually either succulent stems and 
leaves, or small, thick and appressed leaves, or leaves covered 
with numerous hairs. Cassiope, occurring on mountain sum- 
mits of the northeastern United States, and far northward, has 
numerous needle-shaped, closely imbricated leaves. The plants 
need the protection afforded them by these peculiarities in 
these alpine and arctic regions because of the dry air and winds, 
as well as because of the bright sunlight in these regions. 
Because of the bright sunlight in alpine and arctic regions 
many of the plants are noted for the brilliant colors of the 
flowers. 

508. Low stature of alpine plants a protection against 
wind and cold.— Another protection to plants from winds and 


ADAPTATION TO CLIMATE. 339 


Fig. 276. 
Birch trees from Greenland, one third natural size. 


340 ECOLOG ¥. 


‘Fig. 277. 
Willows from Greenland, one third natural size, 


ADAPTATION TO CLIMATE. 341 


from the cold in such regions is their low stature. Many of the 
herbaceous plants have very short stems, and the leaves lie close 
to the soil, the plants and flowers sometimes half covered with 
the snow. The heat absorbed by the soil is thus imparted to 
the plant. Trees in such regions (if the elevation or latitude 
is not beyond the tree line) have very short and crooked stems, 
and sometimes are of great age when only a foot or more high, 
and the trunk is quite small. In figure 276 are shown some 
birch trees from Greenland, one third natural size, the entire 
tree being here shown. Similarly figure 277 represents some 
of the arctic willows, one third natural size. 

509. Some plants of swamps and moors present characters 
of arctic or desert vegetation—Many of the plants of our 
swamps and moors have the characters of arctic or of desert 
vegetation, i.e., small, thick leaves, or leaves with a stout 
epidermis. The labrador tea (Ledum latifolium), an inhabitant 
of cold moors or mountain woods, has thick, stout leaves with 
a hard epidermis on the upper side, and the lower side of the 
leaves is densely covered with brown, woolly hairs. Transpira- 
tion is thus lessened. ‘This is necessitated because of the cold 
soil and water of the moor surrounding the roots, which under 
these conditions absorb water slowly. Were the leaves broad 
with a thin and unprotected epidermis, transpiration would be 
in excess of absorption, and the leaves would wither. Cassan- 
dra, or leather-leaf, and chiogenes, or creeping snowberry, are 
other examples of these shrubs growing in cold moors. 

510. Hairs on young leaves protect against cold and wet. 
—Hairs on young leaves in winter buds afford protection from 
cold and from the wet. The young leaves of the winter buds 
of many of our ferns are covered with a dense felt of woolly 
hairs. In species of osmunda this is very striking. The leaves 
are quite well formed, though small, during the autumn, and 
the sporangia are nearly mature. The hairs are so numerous, 
and so closely matted together, that they can be torn off in the 
form of a thick woolly cap. 


APPENDIX. 
COLLECTION AND PRESERVATION OF MATERIAL. 


Spirogyra may be collected in pools where the water is 
present for a large part of the year, or on the margins of large 
bodies of water. To keep fresh, a small quantity should be 
placed in a large open vessel with water in a cool place fairly 
well lighted. In such places it may be kept several months in 
good condition. : 

Some species of vaucheria occur in places frequented by 
cedogonium or spirogyra, while others occur in running water, 
or still others on damp ground. Frequently fine specimens of 
vaucheria in fruit may be found during the winter growing on 
the soil of pots in greenhouses. ‘The jack-in-the-pulpit, also 
known as Indian turnip, growing in damp ground I have found 
when potted and grown in the conservatory yields an abundance 
of the vaucheria, probably the spores of the alga having been 
transferred with the soil on the plants. When material cannot 
be obtained fresh for study, it may be preserved in advance in 
formalin or alcohol. 

Wheat rust.—The cluster-cup stage may be collected in 
May or June on the leaves of the barberry. Some of the 
affected leaves may be dried between drying-papers. Other 
specimens should be preserved in 2% formalin or in 70% alcohol. 
If the cluster cup cannot be found on the barberry, other species 
may be preserved for study. 

The uredospore and teleutospore stages can usually be found 
abundantly on wheat and oats, especially on late-sown oats 

343 


344 APPENDIX. 


minute black specks on the surface of the leaf. The leaves 
should be preserved dry after drying under pressure. 


Liverworts. 


Marchantia.—The green thallus (gametophyte) of marchan- 
tia may be found at almost any season of the year along shady 
banks washed by streams, or on the wet low shaded soil. Plants 
with the cups of gemme are found throughout a large part of 
the year. They are sometimes found in greenhouses, especially 
where peat soil from marshy places is used in potting. In May 
and June male and female plants bear the gametophores and 
sexual organs. These can be preserved in 2$% formalin or in 
70% alcohol. If one wishes to preserve the material chiefly for 
the antheridia and archegonia a small part of the thallus may be 
preserved with the gametophores, or the gametophores alone. 

In July the sporogonia mature. When these have pushed out 
between the curtains underneath the ribs of the gametophore, 
they can be preserved for future study by placing a portion of 
the thallus bearing the gametophore in a tall vial with 24 for- 
malin. Plants with the sporogonia mature, but not yet pushed 
from between the curtains on the under side, can be collected in 
a tin box which contains damp paper to keep the plants moist. 
Here the sporogonia will emerge, and by examining them day 
by day, when some of the sporogonia have emerged, these plants 
can be quickly transferred to the vials of formalin before the spo- 
rogonia have opened and lost their spores, In this condition the 
plant can be preserved for several years for study of the gross 
character of the sporogonia and the attachment to the gameto- 
phyte. From some of the other plants permanent mounts in 
glycerine jelly may be made of the spores and elaters. 

Riccia.—Riccia occurs on muddy, usually shaded ground. 
Some species float on the surface of the water. It may be pre- 
served in 2% formalin or 70% alcohol. 

Cephalozia, ptilidium, bazzania, jungermannia, frullania, and 
other foliose liverworts may be found on decaying logs, on the 


COLLECTION AND PRESERVATION OF MATERIAL. 345 


trunks of trees, in damp situations. They may be preserved in 
formalin or alcohol. Some of the material may also be dried 
under pressure. 

Mosses are easily found and preserved. Male and female 
plants for the study of the sexual organs should be preserved in 
formalin or alcohol. In all these studies whenever possible living 
material freshly collected should be used. 


Ferns. 


For the study of the general aspect of the fern plant, polypo- 
dium, aspidium, onoclea, or other ferns may be preserved dry 
after pressure in drying sheets. A portion of the stem with the 
leaves attached should be collected. These may be mounted on 
stiff cardboard for use. The sporangia and spores can also be 
studied from dried material, but for this purpose the ferns should 
be collected before the spores have been scattered, but soon after 
the sporangia are mature. But when greenhouses are near it is 
usually easy to obtain a few leaves of some fern when the sporangia 
are just mature but not yet open. To prevent them from opening 
and scattering the spores in the room before the class is ready to 
use them, immerse the leaves in water until ready to make the 
mounts; or preserve them in a damp chamber where the air is 
saturated with moisture. 

For study of the prothallia of ferns, spores should be caught 
in paper bags by placing therein portions of leaves bearing ma- 
ture sporangia which have not yet opened. They should be 
kept in a rather dry but cool place for one or two months. 
Then the spores may be sown on well-drained peat soil in pots, 
and on bits of crockery strewn over the surface. Keep the pots 
in a glass-covered case where the air is moist and the light is 
not strong. If possible a gardener in a conservatory should be 
consulted, and usually they are very obliging in giving sugges- 
tions or even aid in growing the prothallia. 

Lycopodium, equisetum, selaginella, isoetes, and other pteri- 
dophytes desired may be preserved dry and in 70% alcohol. 

Pines.—The ripe cones should be collected before the seeds 


346 APPENDIX. 


scatter, and be preserved dry. Other stages of the development 
of the female cones should be preserved either in 70% alcohol or 
in 24% formalin. The male cones should be collected a short 
time before the scattering of the pollen, and be preserved either 
in alcohol or formalin. 

Angiosperms.—In the study of the angiosperms, if it is de- 
sired to use trillium in the living state for the morphology of the 
flower before the usual time for the appearance of the flower in 
the spring, the root-stocks may be collected in the autumn, and 
be kept bedded in soil in a box where the plants will be sub- 
jected to conditions of cold, etc., similar to those under which 
the plants exist. The box can then be brought into a warm 
room during February or March, a few weeks before the plants 
are wanted, when they will appear and blossom. If this is 
not possible, the entire plant may be pressed and dried for the 
study of the general appearance and for the leaves, while the 
flower may be preserved in 24% formalin, of course preserving a 
considerable quantity. Other material for the study of the plant 
families of angiosperms may be preserved dry, and the flowers 
in formalin, if they cannot be collected during the season while 
the study is going on. 

Demonstrations.—Upon some of the more difficult subjects in 
any part of the course, especially those requiring sections of the 
material, demonstrations may be made by the teacher. The ex- 
tent to which this must be carried will depend on the student’s 
ability to make free-hand sections of the simpler subjects, upon 
the time which the student has in which to prepare the material 
for study, and the desirability in each case of giving demostra- 
tions on the minuter anatomy, the structure of the sexual organs 
and other parts, in groups where the material should be killed~ 
and prepared according to some methods of precision, now used 
in modern botanical laboratories. The more difficult demonstra- 
tions of this kind should be made by the instructor, and such 
preparations once made properly can be preserved for future 
demonstrations. Some of them may be obtained from persons 
who prepare good slides, but in such cases fancy preparations of 


COLLECTION AND PRESERVATION OF MATERIAL. 347 


curious structures should not be used, but slides illustrating the 
essential morphological and developmental features. Directions 
for the preparation of material in this way cannot be given, in 
this elementary book, for want of space. 

Method of taking notes, ete.—In connection with the prac- 
tical work the pupil should make careful drawings from the 
specimens ; in most cases good outline drawings, to show form, 
structure etc., are preferable, but sometimes shading can be 
used to good advantage. It is suggested that the upper 2/3 of 
a sheet be used for the drawings, which should be neatly made 
and lettered, and the lower part of the page be used for the 
brief descriptions, or names of the parts. The fuller notes and 
descriptions of the plant, or process, or record of the experi- 
ment should be made on another sheet, using one, two, three, 
or more sheets where necessary. Notes and drawings should be 
made only on one side of the sheet. The note-sheets and the 
drawing-sheets for a single study, as a single experiment, should 
be given the same number, so that they can be bound together 
in the cover in consecutive order. Each experiment may be 
thus numbered, and all the experiments on one subject then 
can be bound in one cover for inspection by the instructor. 
For example, under protoplasm, spirogyra may be No. 1, mucor 
No. 2, and so on. In connection with the practical work the 
book can be used by the student as a reference book ; and dur- 
ing study hours the book can be read with the object of arrang- 
ing and fixing the subject in the mind, in a logical order. 

The instructor should see that each student follows some well- 
planned order in the recording of the experiments, taking notes, 
and making illustrations. Even though a book be at hand for 
the student to refer to, giving more or less general or specific 
directions for carrying on the work, it is a good plan for every 
teacher to give at the beginning of the period of laboratory 
work a short talk on the subject for investigation, giving general 
directions. Even then it will be necessary to give each indi- 
vidual help in the use of instruments, and in making prepara- 
tions for study, until the work has proceeded for some time, 
when more general directions usually answer. 


348 APPENDIX. 


APPARATUS AND GLASSWARE. 


The necessary apparatus should be carefully planned and be 
provided for in advance. The microscopes are the most expen- 
sive pieces of apparatus, and yet in recent years very good mi- 
croscopes may be obtained at reasonable rates, and they are 
necessary in any well-regulated laboratory, even in elementary 
work. 

Microscopes. If the students are provided with microscopes 
the number will depend on the number of students in the class, 
and also on the number of sections into which the class can be 
conveniently divided. Ina class of 60 beginning students I have 
made two sections, about 30 in each section; and 2 students work 
with one microscope. In this way 15 microscopes answer for the 
class of 60 students. It is possible, though not so desirable, to 
work a larger number of students at one microscope. Some can 
be studying the gross characters of the plant, setting up appa- 
ratus, making notes and illustrations, etc., while another is en- 
gaged at the microscope with his observations. 

The writer does not wish to express a preference for any pat- 
tern of microscope. It is desirable, however, to add a little to 
the price of a microscope and obtain a convenient working 
outfit. For example, a fairly good stand, two objectives (2/3 
and 1/6), one or two oculars, a fine adjustment, and a coarse 
adjustment by rack and pinion, and finally a revolver, or nose- 
piece, for the two objectives, so that both can be kept on the 
microscope in readiness for use without the trouble of removing 
one and putting on another. Such a microscope, which I have 
found to be excellent, is Bausch & Lomb’s AAB (which they 
recommend for high schools), costing about $25.00 to $28.00. 
I have compared it with some foreign patterns, and the cost of 
these is no less, duty free, for an equivalent outfit. Of course, 
one can obtain a microscope for $18.00 to $20.00 without some 
of these accessories, but I believe it is better to have fewer 
microscopes with these accessories than more without them. 


APPARATUS AND GLASSWARE. 349 


Of the foreign patterns the Leitz (furnished by Wm. Krafft, 
411 W. soth St., N. Y.) and the Reichert are good, while Queen 
& Co., Philadelphia, Pa., and Bausch & Lomb, Rochester, 
N. Y., furnish good American instruments. 

Glass slips, 3 X 1 inch; and circle glass covers, thin, 3/4 in. 
diameter. 

Glass tubing of several different sizes, especially some about 
5mm inside diameter and 7mm outside measurement, for root- 
pressure experiments. 

Rubber tubing to fit the glass tubing, and small copper wire 
to tighten the joints. 

Watch glasses, the Syracuse pattern (Bausch & Lomb), are 
convenient. ® 

U tubes, some about 2zomm diameter and 10-15cm long. 
Corks to fit. 

Small glass pipettes (‘‘medicine droppers’’) with rubber 
bulbs. 

Wide-mouth bottles with corks to fit. Reagent bottles. (Small 
ordinary bottles about 1ocm x 4cm with cork stoppers will an- 
swer for the ordinary reagents. The corks can be perforated 
and a pipette be kept in place in each ready for use. Such 
bottles should not be used for strong acids.) 

A few medium glass cylinders with ground top, and glass 
plates to cover. 

Small vials with corks for keeping the smaller preparations 
in. 

Small glass beakers or tumblers. 

A few crockery jars for water cultures. 

Fruit jars for storing quantities of plant material. 

Glass graduates; 1 graduated to r1ooocc, 1 graduated to 
100ce. 

Funnels, small and medium (6 and 10 m in width). Test 
tubes. Bell jars, a few tall ones and a few low and broad. 
Thistle tubes. Chemical thermometer. 

Balance for weighing. A small hand-scale furnished by 


350 APPENDIX. 


Eimer & Amend, 205-211 3d Ave, N. Y., is fairly good 
($2.00). 

Wax tapers or soft-wood splinters. 

Glass cylinder, perforated rubber cork for demonstration 27 
(see Chapter XVI). 

Small porcelain crucibles with covers, and protected wire 
triangles to support the porcelain dishes while heating. 

Apparatus stand, small, several, with clamps for holding test 
tubes, U tubes, etc. 

Agate trays, very shallow, several centimeters long and wide. 
Agate pans, deep, for use as aquaria, etc., with glass to cover. 

Mercury, for manometer in demonstration of respiration. 

Sheet rubber, or prepared vessels for enclosing pots to pre- 
vent evaporation of water from surface during transpiration 
experiments. 

Litmus paper, blue, kept in a tightly stoppered bottle. 
Filter paper for use as absorbent paper. Lens paper (fine 
Japanese paper) for use in cleaning lenses; benzine for first 
moistening the surface, and as an aid in cleaning. 

For materials for culture solution, see Chapter VII. 


REAGENTS. 


Glycerine, alcohol of commercial (95%) strength, formalin or 
formalose of 40% strength, iodine crystals, eosin crystals, 
fuchsin crystals, potassium iodide, potassium hydrate, potash 
alum, barium hydrate, caustic potash sticks, vaseline. It is 
convenient also to have on hand some ammonia, sulphuric 
acid, nitric acid, and muriatic acid in small quantity. 


REAGENTS READY FOR USE AND FOR STORING PLANT MATERIAL IN, 


Alcohol. Besides the 95% strength, strengths of 30%, 504, 
and 70%, for killing material and bringing it up to 704% for 
storage. 


APPARATUS AND GLASSWARE. 351 


Formalin. Usually about a 24% is used for storing material, 
made by taking 974 parts water in a graduate and filling in 24 
parts of the 40% formalin. 

Salt solution 5%; sugar solution 15% (for osmosis). 

Iodine solution. _Weak—to 300¢¢ distilled water add 2 grams 

iodide of potassium; to this add 
I gram iodine crystals. 
Strong—use less water. 
Eosin. Alcoholic solution. Distilled water 5o0cc, alcohol 
50¢c, eosin crystals 4 gram, potash alum 4 grams. 
Aqueous solution. Distilled water 1ooce, eosin 
crystals 1 gram. 


STUDENT LIST OF APPARATUS. 


One scalpel. 

One pair forceps, fine points. 

Two dissecting needles (may be made by thrusting with aid 
of pincers a sewing needle in the end of a small soft pine stick). 

Lead-pencils, one medium and one hard. 

Note paper; a good paper, about octavo size, smooth, un- 
ruled, with two perforations on one side for binding. Several 
manila covers or folders to contain the paper, perforated also. 
Enough covers should be provided so that notes and illustrations 
on different subjects can be kept separate. 


REFERENCE BOOKS. 


The following books are suggested as suitable ones to have 
on the reference shelves, largely for the use of the teacher, but 
several of them can with profit be consulted by the students 
also. There are a number of other useful reference books in 
German and French, and also a number of journals, which 
might be possessed by the more fortunate institutions, but 
which are too expensive for general use, and they are not listed 


here. 


352 APPENDIX. 


Kerner and Oliver, Natural History of Plants. 4 vols., 8vo. 
Henry Holt & Co., New York, 1895. 

Strasburger, Noll, Schenck and Schimper, A Text Book of 
Botany, translated by Porter. The Macmillan Co., New York, 
1898. 

Vines, Student’s Text Book of Botany. The Macmillan Co., 
New York, 1895. 

Atkinson, G. F., Elementary Botany (larger edition). Henry 
Holt & Co., New York, 1898. 

Atkinson, The Biology of Ferns. The Macmillan Co., New 
York, 1894. 

Britton and Brown, Illustrated Flora of the Northern States 
and Canada. Charles Scribner’s Sons, New York. 

MacDougal, D. T., Studies in Plant Physiology. Asa Gray 
Bulletin, Vol. VII, 1899. 

MacDougal, Experimental Plant Physiology. Henry Holt 
& Co., New York, 1895. 

Spalding, Introduction to Botany. D. C. Heath & Co., 
Boston, 1895. 

Bessey, Essentials of Botany. Henry Holt & Co., New 
York, 1896. 

Goebel, Outlines of Classification and Special Morphology of 
Plants. Oxford, Clarendon Press, 1887. 

Warming and Potter, Hand Book of Systematic Botany, 
Macmillan & Co., New York, 1895. 

DeBary, Comparative Morphology and Biology of the Fungi, 
Mycetozoa, and Bacteria. Oxford, Clarendon Press, 1887. 

Underwood, Our Native Ferns and their Allies. Henry Holt 
& Co., New York, 1888. 

Bailey, Lessons in Plants. Macmillan & Co., New York, 
1898. 

Gray, Lessons and Manual of Botany. American Book Co., 
New York. 

Miiller, The Fertilization of Flowers. Macmillan & Co., 
New York. 


APPARATUS AND GLASSWARE. 353 


Darwin, Insectivorous Plants. D. Appleton & Co., New 
York. 

Darwin, The Power of Movement in Plants. D. Appleton 
& Co., New York. 

Darwin, Cross and Self Fertilization in the Vegetable King- 
dom. D. Appleton & Co., New York. 

Warming, Oekologische Pflanzengeographie. Gebriider Born- 
trager, Berlin. 

Schimper, Pflanzengeographie. G. Fischer, Jena. 

Macmillan, Mimosate Plant Life. 

Coulter, Plant Relations. D. Appleton & Co., New York. 

Papers by Macmillan in the Bulletin of the Torrey Botanical 
Club and Minn. Bot. Studies, by Shaler in the 6th, roth, and 
12th Annual Reports of the United States Geological Survey, 
and by Ganong in Trans. Roy. Soc. Canada, sec. ser. vol. 3, 
1897-98, should be consulted by those interested in ecology. 


Where materials cannot be readily collected in the region for 
class use, they can often be purchased of supply companies. 

The Cambridge Botanical Supply Co., Cambridge, Mass., 
supplies plant material of several groups for study, as well as 
apparatus and paper. 

The Ithaca Botanical Supply Co., Ithaca, N. Y., will supply 
plants for study in various groups, and upon order will prepare 
permanent slides for demonstration of the more difficult topics, 
such as the structure of the sexual organs of liverworts, mosses, 


ferns, etc. 


GLOSSARY OF TERMS USED IN THIS BOOK. 


Achene, a dry indehiscent fruit, one-seeded and with the pericarp adherent, 
230. 

Adherent, term used when one floral set is joined to another, 221, 222. 

Ament, a spike which falls away after the maturing of the flower, 227. 

Anatropous, said of ovules which are so bent on the stalk that they are in- 
verted, 206. 

Andrecium, the stamens taken collectively, 196. 

Antheridium, the male sexual organ, that is, the organ or structure which 
bears the sperm cells, 122, 141, 142, 171, 173. 

Apocarpous, term used when all of the pistils or carpels in the flower are 
separate from each other, 229. 

Apogeotropism, a turning away from the earth, said of stems to indicate the 
direction of growth with reference to the earth, 108. 

Archegonium, the female sexual organ of bryophytes, pteridophytes, and 
gymnosperms; it contains the egg, 143, 144, 172, 173. 

Aril, a secondary outgrowth of the ovular coat in some seeds, 209. 

Bracts, small undeveloped leaves, 219. 

Bulb, a short underground stem covered with more or less thickened leaves, 
219, 

Calyx, the sepals taken collectively, 195. 

Campylotropous, said of an ovule bent at right angles to its stalk, 206. 

Capitulum, a flower head, formed by the close association of several flowers 
sessile on a shortened axis, 227. 

Capsule, a dry fruit with a pericarp which opens at maturity, 230. 

Carbohydrate, said of substances containing carbon, hydrogen, and oxygen, 
the two latter in the proportions in which they exist in water (H,O), 79. 

Carbon dioxide, a compound of carbon and oxygen in the proportion of CO,, 
72; 73) 82, 83, 94-Iol. 

Caryopsis, an indehiscent fruit of one seed and a dry, leathery pericarp, 
230. 

Catkin, see Ament, 227. 

Chalaza, that part of the ovule which is attached to the funicle or stalk, 207, 
210. 

Chlorophyll, the green pigment in the chlorophyll bodies which gives the 
green color to leaves, 20, 76, 77. 

355 


356 GLOSSARY OF TERMS USED IN THIS BOOK. 


Chlorophyll body, the proteid body in protoplasm which contains the pig- 
ment chlorophyll, 76, 77. 

Chloroplast, said of the chlorophyll-bearing body, 77. 

Chromoplast, the proteid body in the protoplasm of carrots, and the petals 
of certain flowers which contains a pigment, 77. 

Coherent, suid of the members of one floral set when they are united, 221. 

Conjugation, a process of fertilization during which the sexual cells become 
yoked or united, 115, 118. 

Corm, a short thick underground fleshy stem, 219. 

Corolla, the petals taken collectively, 195. 

Cotyledon, the first leaf, or leaves, on the embryo plant, 211-216. 

Cyme, said of flower clusters, where the uppermost flower opens first, a de- 
terminate inflorescence, 228. 

Cymose, a kind of branching present in cymes, 228. 

Diadelphous, two brotherhoods, said of stamens when they are grouped or 
joined in two definite clusters, 270. 

Diageotropic, said of stems and leaves which grow in a horizontal direction, 
109. 

Diageotropism, turning sideways, or parallel with the surface of the earth— 
term used in reference to stems which grow in a horizontal direction, 
108. 

Diaheliotropism, term used to denote the direction of growth which stems 
take when they grow perpendicular to the direction of light rays, 111. 

Dichasium, a false dichotomous branching, 228. 

Dichotomous, said of an axis where a true forking occurs as the axis branches, 
227. 

Distinct, said of the members of a floral set when they are separate from 
each other, 221. 

Drupe, a stone fruit with a fleshy pericarp, 230. 

Ecology, a study of organisms in their mutual and environmental relations, 
283. 

Embryo, the young plant in the seed of gymnosperms and angiosperms, 205, 
208, 216. 

Embryo-sac, the macrospore in angiosperms, the central cavity in the nucel- 
lus of the ovule containing the egg, and other nuclei, in which the em- 
bryo and the endosperm are formed, 203, 205, 206. 

Endoocarp, the inner zone of tissue of the pericarp, 229. 

Endosperm, the tissue developed in the embryo-sac from the definitive, or 
endosperm, nucleus after fertilization in angiosperms, 208, 215. 

Epigynous, said of flowers where any portion of the calyx or corolla is joined 
to the ovary, 222, 223, 227. 

Exocarp, the outer zone of tissue of the pericarp, 229. 


GLOSSARY OF TERMS USED IN THIS BOOK. 357 


Fertilization, the union of two nuclei, one a sperm nucleus and the other an 
egg nucleus, 123, 172, 173, 205, 206, 208. 

Follicle, a capsule with a single carpel which opens along the ventral or up- 
per suture, 230. 

Free, said of floral sets where no one set is joined to another set, 221. 

Frond, a nearly obsolete term sometimes applied to the leaves of ferns, but 
more frequently to the flattened body of certain seaweeds, 217. 

Fruit, the mature part of the flower which contains the seed, 228, 230. 

Fungi, plants devoid of chlorophyll, possessing mycelium as the structural 
unit (except certain unicellular forms), 125-138. 

Funicle, the stalk of the ovule, 207-210. 

Gamopetalous, said of the corolla when the petals are more or less united, 
222. 

Gamosepalous, said of the calyx when the sepals are more or less united, 
222. 

Geotropism, term used to express the property of stems and roots when in- 
fluenced by the earth in direction of growth, 108. 

Gynandrous, said of stamens when they are united with the pistil, 243. 

Gynecium, the pistils taken collectively, 197. 

Head, same as capitulum, 227. 

Heliotropism, a turning influenced by light, said of stems, roots, and leaves 
when their position is influenced by light, 111. 

Hilum, the scar on the seed where it was attached to the wall of the ovary, 
207, 210. 

Hygrophyte, term used to denote plants which grow in damp situations, and 
which easily wither when the water supply is checked, 288, 289. 

Hypha, a single mycelium thread, 125. 

Hypocotyl, the part of the seedling between the cotyledons and the root, 211. 

Hypogynous, said of flowers when no floral set is united with the ovary, 222, 
223. 

Inflorescence, the relation of flowers on an axis or its branches, 225-228. 

Insertion, term used in speaking of the position or attachment of the parts 
of the flower, 221. 

Integument, the coat or coats of the ovule, 208. 

lrregular, said of flowers where the different members of one or more sets 
are of different size, 222. 

Legume, the fruit of the pea, bean, etc., 230. 

Leucoplast, the colorless proteid body in protoplasm of chlorophyll-bearing 
plants, which under favorable circumstances may become green with 
chlorophyll, or become a chromoplast, or may act as a centre for the 
formation of starch grains where starch is stored, as in the potato tuber, 


ete., 77: 


358 GLOSSARY OF TERMS USED IN THIS BOOK. 


Ligula, the strap-shaped corolla of the flower of certain composites, 278. 

Loculicidal, said of capsules which split down the middle line when ripe, 230. 

Lodicule, a reduced member of the perianth in grasses, 247, 248. 

Macrosporangium, a sporangium which contains the large spores, macro- 
spores, or megaspores, 198, 201. 

Macrospores, the large spores which develop only female prothallia, found in 
certain pteridophytes, in the gymnosperms, and possibly in the angio- 
sperms, 182, 188. 

Mesocarp, an intermediate zone of the pericarp, when it is present, 230. 

Micropyle, the opening in the free end of the ovule, 209, 210. 

Microsomes, term used for the small granules in protoplasm, 25. 

Microspores, the small spores in the sporangium in those plants where the 
spores are differentiated in size as in certain pteridophytes, in the gym- 
nosperms and angiosperms (in the two latter the pollen grains are the 
microspores), 182, 201. 

Monochasium, a kind of branching where one lateral branch is produced 
from each relative or false axis, 228. 

Monopodial, said of the branching of shoots when the main shoot grows 
more rapidly than the lateral shoots, 227. 

Mycelium, the vegetative part of most fungi, 25, 84-89, 125, 131, 134. 

Nucellus, the central part of the ovule, 208, 210, 212. 

Nucleus, a special organ in protoplasm, of a more dense structure than the 
remainder of the protoplasm, 21. 

Nut, an indehiscent fruit with a dry hard pericarp, 230. 

Oogonium, the female sexual organ of certain low alge, as vaucheria, and 
of certain fungi; contains the egg, 122, 123. 

Orthotropous, a straight ovule, 206. 

Ovule, the macrosporangium of the gymnosperms and angiosperms, 191; oc- 
curs usually within or upon the carpel, and at maturity contains the 
embryo, if that is formed, 191, 198, 201, 205, 206, 207, 210. 

Panicle, a raceme with the lateral axes branched, 227. 

Pericarp, the part of the fruit which envelops the seed and which forms the 
wall of the seed, 229, 230. 

Perigynous, said of flowers where the stamens or petals are borne on the 
calyx, 222, 223, 265, 266. 

Perisperm, the remnant of the nucellus within the seed, when it is not en- 
tirely consumed in the formation of the seed, 208, 210, 212. 

Perithecium, the closed or nearly closed fruit body of certain ascomycetous 
fungi, 136-138. 

Phyllotaxy, term used to denote arrangement of leaves on the axis, 11. 

Pistil, the member of the flower which contains the ovules, 197, 198, 203, 
206. 


GLOSSARY OF TERMS USED IN THIS BOOK. 359 


Pleiochasium, an inflorescence where each relative or false axis produces 
more than two branches, 228. 

Pneumatophore, term applied to special organs of aeration, 327. 

Pollination, the passage of the pollen from the stamens to the stigma of the 
pistil, 192, 205, 241, etc. 

Pome, the fruit of the apple, 230. 

Poricidal, said of capsules which dehisce by a terminal pore, 230. 

Progeotropism, a turning toward the earth, said of roots which grow toward 
the earth, 108. 

Prothalliam, the sexual stage of the pteridophytes, gymnosperms, and angio- 
sperms, 166, 170, 203-207. 

Protonema, thread-like growth proceeding from the germinating spore of 
bryophytes, and some pteridophytes, 169. 

Protoplasm, the living substance of plants and animals, 15-27. 

Pyxidium, pyxis, a capsule which opens with a lid, 230. 

Raphe, the part of the stalk of the ovule which is joined to the ovule where 
the ovule is bent upon its stalk, 207, 210. 

Respiration, an interchange of gases by the plant during growth, by which 
oxygen is consumed and carbon dioxide is liberated, 94-101. 

Rhizome, an underground root-stock, 200. ~ 

Runners, prostrate stems which take root here and there, 219. 

Samara, a winged seed, 256. 

Schizocarp, a dry several-loculed fruit in which the carpels separate from 
each other at maturity but do not dehisce, 230. 

Septicidal, applied to a syncarpous capsule in which the carpels separate 
along the line of their union, 230. 

Silique, a capsule of two carpels which separate at maturity, leaving the par- 
tition wall persistent, 230. 

Spadix, a spike in which the main axis is fleshy, 227. 

Sperma‘ozoid, a motile sperm cell, 122, 123, 142, 171, 172. 

. Sperm cell, the male cell which contains the nucleus for union with the egg 
nucleus; it may be motile or non-motile, 204, 205. 

Spike, an inflorescence with a long main axis, and with sessile flowers on it 
or on very short lateral axes, 227. 

Spikelet, a short lateral flower-branch in the grasses, 247, 249. 

Sporangium, a spore case containing spores. 

Sporogonium, the entire structure which is the product of the fertilized egg 
in the bryophytes, 144, 145, 152. 

Sporophyll, term applied to leaves in the pteridophytes, gymnosperms, and 
angiosperms which bear sporangia, 176, 188, 197. 

Stamens, the members of the flower which bear the pollen grains or micro- 


spores, 201, 203, 206. 


360 GLOSSARY OF TERMS USED IN THIS BOOK. 


Sympodial, said of types of branching where the lateral axes grow more rap- 
idly than the main axis, 227. 

Syncarpous, said of the gyncecium when the carpels are united, 229, 230. 

Testa, the outer coat of the seed, 208, 210. 

Thallophytes, plants of low organization in which the plant body is a frond 
or thallus, especially the algae and fungi, 217. 

Tropophytes, plants, especially of the North Temperate Zone, which have 
hygrophytic structures during the summer season, and during the win- 
ter season change to xerophytic habit, 288, 289. 

Tubers, underground thickened stems, 219. 

Umbel, said of an inflorescence where the main axis is shortened and the 
terminal flowers appear to form terminal clusters, 227. 

Xerophytes, plants adapted to grow in dry situations, or in situations where 
they absorb water with difficulty, 288, 289. 

Xylem, the woody elements of the fibrovascular bundle, 64-68. 

Zygospore, zygote, a resting spore, formed by the sexual union of two equal 
or nearly equal cells, 117, 118. 


INDEX. 


Absorption, 28-33, 39-41 

Acer, 262 

Aceraceze (a-cer-a'ce-2), 262 

Achene, 230 

Acorus (a'co-rus), 243 

Adder-tongue, 233, 236, 238 

Adherent, 221, 222 

Adiantum, 160 

Esculineze (2es-cu-lin’ze), 262 

Aésculus (zs’cu-lus), 264 

Agaricus campestris 
cam-pes'tris), 85-87 

Aggregate (ag-gre-ga’tze), 278 

Almond family, 266 

Ament, 227 

Amentiferze (a-men-tifer-z), 


(a-gar'i-cus 


250- 
254 

Amygdalaceze (a-myg-da-la'ce-z), 
266 


Anatropous, 206 

Andreecium (an-dree'ci-um), 196 

Angiosperms, 194-206, 235 

Antheridium (an-ther-id’i-um), 122, 
I41, 142, 171, 173 

Apocarpous (ap-o-car'pous), 229 

Apogeotropism (ap-o-ge-ot/ro-pism), 
10! 

Apple, 269 

Apple family, 267 

Araceze (a-ra'ce-2), 243 


Archegonium (ar-che-go’ni-um), 
143, 144, 172, 173 
Aril, 209 


Ariszema (ar-i-see’ma), 243-246 
Arum family, 243 

Asclepias (as-clep’i-as), 297 
Ash, 82 

Aspidium (as-pid’/i-um), 155-164 
Aster, 278-280 

Atoll moor, 315-320 


Atoll, plant, 315-320 
Azalea (a-za'le-a), 329 


Bacteria, nutrition of, 91 

Bald cypress, 327 

Berry, 230 

Bicornes (bi-cor’nes), 274 

Bidens (bi’dens), 292 

Black mould, 24-26, 125-127 

Black rust, 129-131 

Blue violet, 260 

Bluet, 223 

Bracts, 219 

Branching (dichotomous, monopo- 
dial, sympodial, cymose), 227 

Buckeye family, 264 

Buds, 7-13 

Bulbs, 219 

Buttercup, 257, 258 

Bur-marigold, 292 


Calla, 245 

Caltha, 256, 257 

Calyx, 195 

Campylotropous, 206 

Capitulum, 227 

Capsella, 259 

Capsule, 230 

Carbohydrates, 79 

Carbon dioxid, 72, 
101 

Carbon food of plants, 70-80 

Carnation rust, 87-89 

Carnivorous plants, 89-91 

Caryopsis (ca-ry-op’sis), 230 

Castor oil bean, 212 

Catkin, 227 

Catnip. 275 

Cat tails, 243 

Cell sap, 21, 31 


82, 83, 94, 


361 


362 


Chalaza (cha-la’za\, 207, 210 

Chlorophyll, 20, 76, 77 

Chlorophyll bodies, 76, 77 

Chloroplast (chlo‘ro-plast), 77 

Choke cherry, 266, 267 

Christmas fern, 155-164 

Chromoplast, 77 

Cistiflorze (cis-ti-flo’rze), 260 

Class, 233, 235 

Classification, 231-235 

Claytonia, 226 

Clematis, 298 

Cluster cup, 129, 130 

Coherent, 221, 222 

Composite, 278 

Composite family, 278 

Conjugation, 115-118 

Convolvulus (con-vol'vu-lus), 221 

Corms, 219 

Corolla, 195 

Cotyledon (cot-y-le’don), 211-216 

Crow-foot family, 256-258 

Cruciferze (Cru-cif er-z), 259 

Cupuliferze (cu-pu-lifer-z), 252 

Cyme (forking, helicoid, scorpioid), 
228 

Cypress knees, 326 

Cypripedium (cyp-ri-pe’di-um), 240- 
242 


Dandelion, 281 

Dehiscence, 230 

Dentaria (den-ta’ri-a), 199-202 

Desmodium, 292 

Diadelphous (di-a-del’phous), 270 

Diageotropism (di-a-ge-ot’ro-pism), 
108, diageotropic, 109 

Diagram (floral), 224 

Diaheliotropism (di-a-he-li-ot’ro- 
pism), ILI 

Dichasium (di-cha’si-um), 228 

Dicotyledones (di-cot-y-led’o-nes), 
234, 235, 250-282 

Diffusion, 28-33 

Dioncea (di-o-nce’a), 89, 91 

Distinct, 221 

Dodder, nutrition of, 88, 90 

Drosera (dros’e-ra), 89, 91 

Drupe, 230 

Duckweeds, 243 


Ecology (e-col’o-gy), 283-340 
Elm family, 255 


INDEX. 


Embryo, 205, 208, 216 
Embryo-sac, 203, 205, 206 
Endocarp, 229 
Endosperm, 208-215 
Epigynous, 222, 223, 267 
Epipactis (ep-i-pac’tis), 240 
Equisetinz, 174 
Equisetum, 174-179 
Erythronium (er-y-thro’ni-um), 232, 
233, 236, 238 
Evening primrose, 271, 272 
Exocarp, 229 


Family, 233-235 

Ferns, 155-173 

Fertilization, vaucheria, 123 ; ferns, 
172, 173; angiosperms, 205, 206, 
20 

Fibro-vascular bundles, 62-68 

Figwort family, 277 

Filicineze (fil-i-cin’e-z), 155 

Follicle, 230 

Forget-me-not, 229 

Formula (floral), 223 

Fragaria (fra-ga'ri-a), 266 

Free, 221 

Frond, 217 

Fruit, 228, 230 

Fungi, 125-138 

Funicle, 207-210 


Gamopetalous (gam-o-pet’a-lous), 
222 

Gamosepalous (gam-o-sep’a-lous), 
222 


Garden bean, 211 
Gaylussacia (gay-lus-sa’ci-a), 274, 
275 

Genus, 232 

Geotropism (ge-ot’ro-pism), 108 

Geum (ge’um), 293 

Glumifloree (glu-mi-flo’ree), 247 

Graminez (gram-in’e-z), 247 

Grass family, 247 

Green felt, 120-124 

Group, 235 

Growth, 102-106 

Gymnosperms 
184-193 

Gynandre (gy-nan‘drz), 240 

Gynandrous (gy-nan‘drous), 240 

Gyncecium (gyn-ce’ci-um), 197 


(gym’no-sperms), 


INDEX. 


Hamamelis (ham-a-me'lis), 332 

Hawkweed, 280 

Head, 227 

Heliotropism (he-li-ot'ro-pism), III 

Hickory, opening buds, 333 

Hieracium (hi-er-a’ci-um), 280 

Hilum, 207, 210 

Hippocastanacez (hip-po-cas-tan-a’- 
ce-z), 264 

Horse chestnut, 264 

Horsetails, 174-179 

Houstonia, 223 

Huckleberry (whortleberry), 274, 27 5 

Pea (hy’gro- phyteyh * 288, 
269 

Hypha, 125 

Hypocoty]l (hy-po-cot’yl), 211 

Hypogynous, 222, 223 


Impatiens, 294 

Indian turnip, 243-246 

Inflorescence, 225-228 

Insectivorus plants, 89, 91 

Insertion, 221 

Integument, 206, 208 

Irregular, 222 

lrritability (movement due to), 107— 
113 

Isoetes (i-so’e-tes), 180-183, 325 


Jack-in-the-pulpit, 213, 243-246 


Kalmia (kal’mi-a), 331 
Kinship, 225 


Labiatee (la-bi-a’tee), 275 
Lactuca (lac-tu’ca), 295, 296 
Lady slipper, 240-242 
Lamium, 224, 275 

Leaf, 219 ; structure of, 56-59 
Legume, 230 

Leguminosz (leg-u-min-o'sz), 269 
Leucoplast (leu’co-plast), 77 
Lichen, 311, 313 

Ligule, 278 

Liliacez (lil-i-a'ce-2), 234, 240 
Liliiflor (lil-i-i-flo’rae), 236. 
Lilium, 233 

Liverworts, 139-148 
Loculicidal, 230 

Lodicule, 247, 248 


363 


Macrosporangia, macrosporangium 
(mac-ro-spor-an'gium), 198, 201 

Macrospores (mac’ro-spores), isoetes, 
182; pine, 188 

Marchantia (mar-chan'ti- a), 139-148 

Marsh marigold, 256, 257 

Mentha (men’tha), 275 

Mesocarp, 230 

Micropyle (mi’cro-pyle), 209, 210 

Microsomes (mi’cro-somes), 25 

Microspores (mi’cro-spores), isoetes, 
182; pine, 188; trillium, 197 

Mildew (willow), 134-138 

Milkweed, 296, 297 

Mint family, 275 

Mnium (mni’um), 150-154 

Monochasium (mon-o-cha’si-um), 228 

Monocotyledones (mon-o-cot-y-led’o- 
nes), 213, 216, 234, 235, 236-249 

Morning glory, 221 

Mosses, 149-154. 

Mucor, 24-26, 125-127 

Mushroom, 85-87 

Mustard family, 259 ; 

Mycelium (my-ce’li-um), 25, 84-89, 
125, 131, 134 

Myrtiflore (myr-ti-flo’re), 271 


Nepeta (nep’e.ta), 276 

Nettle (dead), 224, 275 

Nitrogen (how obtained by clovers, 
etc.), 92, 93 

Nucellus, 208, 210, 212 

Nucleus, 21 

Nut, 230 

Nutrition, 84-93 


Oak family, 252 


C£nothera (ce-no’the-ra), 271, 272 

Onoclea (on-o-cle’a), 159 

Onogracez (on-o-gra’ce-z), 271 

Oogonium (0-0-go ‘ni-um), 122, 123 

Orchidaceze (or-chid-a’ce-z), 240~ 
242 

Order, 233-235 

Orthotropous (or-thot’ro-pous), 206 

Osmose, 30-32 

Osmotic pressure, 50, 51 

Ovule, 191, 198, 201, 205-207, 210 

Oxygen, 71-73, 82, 83, 94-101 


Palm (cocoanut), 243 
Panicle, 227 


364 


Papilionaceze 
269 

Parasitic fungi (nutrition of), 87, 88 

Parmelia (par-me'li-a), 311, 312 

Pea, 270 

Pea family, 269 

Peltandra (pel-tan’dra), 205 

Pericarp, 229, 230 

Perigynous, 222, 223, 265, 266 

Perisperm, 208, 210, 212 

Perithecium (per-i-the’ci-um), 136- 
138 

Personatz (per-so-na’te), 277 

Petaloideze ( pet-a-loi’de-z), 236 

Phyllotaxy, 11 

Pistil, 197, 198, 203, 206 

Pisum (pi’sum), 270 

Plant substance, 81, 83 

Pleiochasium (plei-o-cha’si-um), 

Plum family, 266 

Pollination, 192, 193, 205, 241 

Polycarpicze (pol-y-car'pi-cze), 256 

Polypodium (pol-y-po’di-um), 155 

Polytrichum, 149 

Pomacez, 267 

Pome, 230 

Pneumatophore (pneu-mat’o-phore), 
327 

Poricidal, 230 

Prickly lettuce, 295 

Primrose, 224 

Progeotropism 
108 

Prothallium (pro-thall’i-um), 203-207 ; 
ferns, 166-170 

Protonema (pro-to ne’ma), 169 

Protoplasm (pro'to-plasm), 
movement of, 26 

Prunus, 267 

Pteris (pter’isi, 170 

Puccinia (puc-cin i-a), 129, 130 

Purple trillium, 231, 232 

Pyrus, 269 

Pyxidium, pyxis, 230 


(pa-pil-i-o-na'ce-a), 


(pro-ge-ot’ro-pism), 


15-27; 


Quercus (quer’cus), 252 
Quillwort, 180-183 


Raceme, 227 
Ranunculaceze 
256-258 
Raphe, 207, 210 
Raspberry, 206 


(ra-nun-cu-la’ce-2), 


INDEX. 


Rattlesnake-weed, 280 

Red rust, 129-132 

Reforestation, 300-304 
Relationships, 225, 232 
Respiration, 94-101 

Rhizome, 200 

Rhizopus (rhi'zo-pus), 126-128 
Rhododendron (rho-do-den’dron), 


329 
Rheeadinze (rhoe-a-din'ze), 259 
Root, 220 
Root hairs, 15-18, 39-44 
Root pressure, 50, 51 
Root-stock, 219 
Rosacez (ro-sa’ce-2), 265 
Rose family, 265 
Rosiflorze (ro-si-flo’rae), 265 
Rubus, 266 
Runners, 219 


Sagittaria, 306, 309 

Salicaceze (sal-i-ca'ce-z), 250 

Salix, 251 

Samara, 256 

Sand dunes, 300, 301 

Schizocarp, 230 

Schrophulariacez (schroph-u-la-ri-a’- 
ce-2), 277 

Sea-wrack, 217 

Seed, 208, 210 

Seed distribution, 292 

Seed (germination), 1-6 

Seedlings, 210, 216 

Septicidal, 230 

Sexual organs ; vaucheria, 122-124; 
ferns, 170-173; angiosperms, 205- 
207 

Shepherd’s purse, 259 

Silique, 230 

Silkweed, 296, 297 

Skunk’s cabbage, 243 

Solomon’s seal, 237 

Spadiciflore (spa-di-ci-flo’rae), 243 

Spadix, 227 

Spathyema (spath-y-e’ma), 243 

Species, 231 

Spermatozoids (sper-mat'o-zoids), 
122, 123, 142, 171, 172 

Sperm cell, 204, 205 

Sphagnam, 324 

Spike, 227 

Spikelet, 247-249 

Spines, 219 


INDEX. 


Spirzea (spi-rze’a), 265 

Spirogyra, 19-23, 115-119 

Sporangium (spor-an‘gi-um), mucor, 
126; fern, 158-163; equisetum, 
176; isoetes, 181; pine, 188, I91 

Sporogonium (spor-o-go’ni-um), 144, 
145, 152 

Sporophyll, equisetum, 176; pine, 
188; trillium, 197 

Spring beauty, 226 

Spruce moor, 320-324 

Stamens, 201, 203, 206 

Starch, 70-80 

Stem, 219 

Stomates, 58, 59 

Strawberry, 265, 268 

Sundew, 90, 91 

Sweet flag, 243 

Sympetalz (sym-pet’a-le), 274 

Syncarpous (syn-car’pous), 229, 230 


Taraxacum (tar-ax’a-cum), 281 

Taxodium (tax-o’di-um), 327 

Taxonomy (tax on’o-my), 231-235 

Taxus, 209 

Tendrils, 219 

Testa, 208, 210 

Thallophytes, 217 

Thallus, 217 

Thorns, 219 

Tissues (syopsis of), 68 

Tissue tension, 46-48 

Toad flax, 277 

Touch-me-not, 294 

Transpiration, 51-54, 56-59 

Trillium, 194 

Trillium erectum, 231, 232 

Tropophytes (trop’o-phytes), 
289 


288, 


365 


Tubers, 219 

Tubiflorze (tu-bi-flo’ree), 275 
Turgescence, 28-30, 45-49 
Turgidity, 45-49 

Turgor, 28-30, 45-49 


Ulmaceze (ul-ma’ce-z), 255 
Ulmus, 255 

Ulva, 217 

Umbel, 227 

Uncinula (un-cin’u-la), 134-138 
Unifolium (u-ni-fo’li-um), 237 
Uromyces (u-ro-my’ces), 87, 88 
Urticiflorze (ur-ti-ci-flo’re), 255 


Vacciniacez (vac-cin-i-a’ce-), 274 
Vaucheria (vau cher'i-a), 120-124 
Venus fly-trap, 89, 91 

Viola, 260 

Violaceze (vi-o-la’ce-2), 260 

Violet family, 260 

Virgin’s bower, 298 


Wake robin, 232 
Walking fern, 331 
Wheat rust, 129-133 
White pine, 184-193 
Whortleberry, 274 
Wild lettuce, 296 
Willow family, 250 
Witch hazel, 332 


Xerophytes (xer’o-phytes), 288, 289 
Yew, 209 


Zonal distribution, 306 
Zygospore, zygote, 117, 118 


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