Elementary botany

Preface

Untij recent years the prevalent method of teaching botany in the secondary schools, and in the first courses in many colleges, has been based on the . " analysis " of flowers. The method had its impetus in the study of systematic botany pursued with such vigor by the pioneers of the science in America. The great progress in our knowledge of the morphology and physiology of plants during the last quarter of this century has changed the whole problem of elementary instruction in botany, and led to almost universal dissatisfaction with the old method jf secondary instruction in this subject. It is now generally ognized that a study of the lower plants, like the algae, fungi, jrworts, mosses, and ferns should form a part of a course of

condary education in botany.

To meet this end a number of books have sprung into exist -

ice during the past few years. If the need for some guidance in the selection of topics, and an outline of the character of the study, could be met by nn??ibe?' alone of books, this want would be fully met in the new treatises recently published, and there would be no place for the present book. But a judicious selection of a few forms to illustrate function, process, and relationship throughout the wide range of plant life, and the training in logical methods of induction, and accuracy of drawing conclusions, is vastly more important in "its influence on the character of the pupil, even though he forget all about the plants studied, than the handling' -of. -a g^eat variety of objects, and the drawing of haphazard conclusions, which are left to the pupil in a large number of cases by the methods pursued in many of the recent elementary works,

iii

IV PREFACE.

For several years the author has been deeply interested in the teaching of elementary botany, and has had an opportunity to study methods in a practical way, in having charge of the instruction of a large class of beginners, the majority of whom had never studied the subject before. One of the great difficulties encountered in attempting to introduce the study of the lower plants is the fact that these plants are in most cases entirely unknown to the pupil. The difficulty does not lie in the attempt to introduce the study of unknown objects. But it lies rather in the attempt to study the lower plants, at the outset, in a more or less thorough manner, to learn their characters, relationships, etc., in order to group them into their natural orders. This is attempting too much for the young beginner, to whom these plants are totally unfamiliar objects.

The method followed in this book has been thoroughly tested in practical work. It is to first study some of the life processes of plants, especially those which illustrate the fundamental principles of nutrition, assimilation, growth, and irritability. In studying each one of these topics, plants are chosen, so far as possible, from several of the great groups. Members of the lower plants as well as of the higher plants are employed, in order to show that the process is fundamentally the same in all plants. Then another process is studied in a similar way, using so far as possible, especially where the lower plants are concerned, the same plant. In this way the mind is centered on this process, and the discovery to the pupil that it is fundamentally the same in such widely different plants arouses a keen interest not only in the plants themselves, but in the method which attends the discovery of this general principle. In the study of the life processes, the topics can be arranged so that they show progression of function.

At the same time it is well for the teacher to select for this study of the life processes those plants which represent well the great groups, and show gradual progression of form and structure, and also those which arc easily obtained.

A second period of the sessiofl can then be devoted to study-

PREFA CE. V

ing a few representatives of the different groups of the algae, fungi, liverworts, mosses, ferns, and the higher plants. This should be done with special reference to form, reproduction, general classification, progression, and retrogression of parts or organs, in passing from the lower to the higher plants. In taking up this study of representative forms now, if a wise selection has been made in dealing with the life processes, the same plant can be used here in most cases. These plants now are familiar to the pupil, and the mind can be centered on form, organs, reproduction, relationship, etc. In this study of general morphology it is very important that a careful study be made of some of the lower plants, and of the ferns. Here the sexual organs are well formed, and the processes of reproduction can be more easily observed. In the higher plants the sexual organs are very much reduced, and the processes more difficult to observe. It is only through a study of the lower plants that we are able to properly interpret the floral structures, and the sexual organs of the spermatophytes, and to rid ourselves of the erroneous conceptions which the prevalent method of elementary instruction has fixed so firmly on the lay mind.

A third period of the elementary course may be employed in studying special morphology of the higher plants. Even here it seems to the author wise that the "analysis" of plants should be deferred until after a general notion of the characters and habit of several of the important families has been obtained. The pupil may be told the names of the several plants used as examples, and emphasis can be laid on ordinal and generic characters, which can then be recognized in many plants without resort to a key. The matter of determining the names of plants by the old method can, if desired, be pursued to greater advantage after this critical study of relationships has been made, even though the pupil may pursue it independently at a later time.

In the study of plants one should not lose sight of the value of observing plants in their natural surroundings. If judiciously pursued it forms at once a means of healthful recreation, of communion with the very soul of nature, and of becoming ac-

VI quainted with the haunts, the lives, the successes and failures of plants ; the influences of soil, moisture, and other environmental conditions upon plants, and, what is also important, the influence which plants exert upon their environment. Classes may be taken into the field, at different seasons of the year, to observe flower and bud formation, pollenation, seed production, seed distribution, germination of seeds and nutrition of the embryo, protection of plants against foes and extremes of weather ; the relationships of plants in colonies, and their distribution in plant formations, etc. In all this study a knowledge of some of the lower plants is important.

It is not intended that the matter in the book should be memorized for the purpose of recitations. It should be used as a guide to the practical work, and as a reference book. The paragraphs arranged in coarse print are intended in general to indicate the studies which will serve as the basis for the practical work by the student. In most cases the material for these studies can be quite easily obtained and the laboratory work is not difficult. The paragraphs in fine print are intended to further illustrate the subject by discussion and illustration of the more difficult phases of each topic. Some of these can be made the basis for demonstrations by the teacher before the class, and all will serve as a convenient means of getting at the important reference matter by the student in a single book. Suggestions on the study and the taking of notes, etc., by the student are given in the appendix.

Acknowledgments. — The author desires here to express his gratefulness to his associates m the botanical department of Cornell University who have read the manuscript and have made useful suggestions (Messrs. E, J, Durand, B. ML Duggar, K. M. Wilgand, and Professor W. W. Rowlee). Valuable suggestions were also given by Dr, J. C. Arthur, of Purdue University, who kindly read the chapters on physiology, and by Professor W, F. Ganong, o\ Smith College, who read some o\ the chapters on ecology and the tables on the homologies of the gymnosperms and angiosperms.

PREFACE. Vll

Illustrations. — The large majority of the illustrations are new, and were made with especial reference to the method of treatment followed in the text. Most of the photographs were made by the author. Others were contributed by Professor P. H. MH1, of the Alabama Polytechnic Institute, Auburn, Ala.; Professor Rowlee, Cornell University ; Mr. H. J. Webber, Washington, D. C. ; by the New Jersey Geological Survey through the courtesy of Mr. Gifford Pinchot, of New York ; by Mr. B. M. Duggar, Cornell University, and Mr. Herman von Schrenk, of the Missouri Botanical Garden.

Many of the drawings, especially those of microscopic objects, were made by the author ; others by Mr. H. Hasselbring, Cornell University, and Dr. Bertha Stoneman, now professor of botany in the Huguenot College, Wellington, Cape Colony, South Africa. The drawings to illustrate the gross characters of plants were made by Mr. W. G. Holdsworth, Michigan Agricultural College; Mr. Joseph Bridgham, Providence, R. I.; Messrs. W, C. Furlong and W. C. Baker, Cornell University ; and a few by Miss Edna Porter, Buffalo, N. Y., and by Mrs. E. L. Nichols and Mrs. J. G. Needham, Cornell University. Professor Chas. A. Davis kindly furnished the sketches from which the drawings of the transformed trillium flower were made.

Other illustrations have been obtained from the following sources: from the author's Study of the Biology of Ferns, through the courtesy of the Macmillan Co.; and from the Annals of Botany, Jahrbiicher fiir wissenschaftliche Botanik, Flora, Botanical Gazette, Vines' Student's Text Book of Botany, and Warming's Botany.

Above all the author is under great obligations to Professors Ikeno and Hi rase, of the Imperial ^University of Japan, Tokio, for their unparalleled courtesy in sending drawings of the spermatozoids, and of fertilization, in cycas and gingko, in advance of their publication.

Cornell University, June, 1898.

Contents

(References are to paragraphs.)

Chapter I. Protoplasm

The plant spirogyra, 4. Chlorophyll bands in spirogyra, 5. The spirogyra thread consists of cylindrical threads end to end, 6. Protoplasm, 7. Cell-sap in spirogyra, 8. Reaction of protoplasm to certain reagents, 9. Earlier use of the term protoplasm, 11. Protoplastn in miicor, 12. Mycelium of mucor, 13. Appearance of the protoplasm, 14. Movement of the protoplasm in mucor, 15. Test for protoplasm, 16. Protoplasm in nitella, 17. Form of nitella, 18. Internode of nitella, 19. Cyclosis in nitella, 20. Test for protoplasm, 21. Protoplasm in one of the higher plants, 22. Movement of protoplasm in the higher plants, 23. Movement of protoplasm in cells of staminal hair of spiderwort, 24. Cold retards the movement, 25. Protoplasm occurs in the living parts of all plants, 26 page 1

Chapter II. Absorption, Diffusion, Osmose

Osmose in spirogyra, 30. Turgescence, 31. Experiment with beet in salt and sugar solutions, 32. Osmose in the cells of the beet, 34. The coloring matter in the cell-sap does not readily escape from the living protoplasm of the beet, 35. The coloring matter escapes from dead protoplasm, 36. Osmose experiments with leaves, 37. Absorption by root-hairs, 39. Cell-sap a solution of certain substances, 40. Diffusion through an animal membrane, 41. Importance of

these physical processes in plants, 44 page 13

ix

X CONTENTS.

Chapter III. Absorption Of Liquid Nutriment

Formula for solution of nutrient materials, 46. Plants take liquid food from the soil, 50. How food solutions are carried into the plant, 51. How the root-hairs get the watery solutions from the soil, 52. Plants cannot remove all the moisture from the soil, 53. Acidity of root-hairs, 56. . .page 22

Chapter IV. Turgescence

Turgidity of plant parts, 58. Restoration of turgidity in shoots, 59. Tissue tensions, 61. Longitudinal tissue tension, 62. Transverse tissue tension, 65 page 28

Chapter V. Root Pressure

Root pressure may be measured, 67. Experiment to demonstrate root pressure, 68 page 31

Chapter VI. Transpiration

Loss of water from excised leaves, 71. Loss of water from growing plants, 72. Water escapes from the surfaces of living leaves in the form of water vapor, 73. Experiment to compare loss of water in a dry and a humid atmosphere, 74. The loss of water is greater in a dry than in a humid atmosphere, 75. How transpiration takes place, 76. Structure of a leaf, 79. Epidermis of the leaf, 80. Soft tissue of the leaf, 81. Stomata, 82. The living protoplasm retards the evaporation of water from the leaf, 83. Action of the stomata, 84. Transpiration may be in excess of root pressure, 85. Negative pressure, 86. Lifting power of transpiration, 87. Root pressure may exceed transpiration, 88. Injuries caused by excessive root pressure, 89. Demonstration of stomates and intercellular spaces, 92 page 33

CONTENTS. XI

Chapter VII. Path Of Movement Of Liquids In Plants

Place the cut ends of leafy shoots in a solution of some red dye, 94. These solutions color the tracts in the stem and leaves through which they flow, 95. Structure of the fibro-vascular bundles, 9S. Woody portion of the bundle, 99. Bast portion of the bundle, 100. Cambium region of the bundle, 101. Longitudinal section of the bundle, 102. Vessels or ducts, 103. Sieve tubes, 105. Fibro-vascular bundle in Indian corn, 107. Rise of water in the vessels, 108. Synopsis of tissues, 110 page 42

Chapter VIII. Diffusion Of Gases

Gas given off by green plants in the sunlight, in. What this gas is, 117. Oxygen given off by green land plants also, 118. Absorption of carbon dioxide, 119. The gases are exchanged in the plants, 122. A chemical change of the gas takes place within the plant cell, 123. Gases as well as water can diffuse through the protoplasmic membrane, 124

Chapter IX. Respiration

Oxygen from the air consumed during germination of seed, 127. Carbon dioxide given off during germination, 128. Respiration is necessary for growth, 130. Energy set free during respiration, 132. Respiration in a leafy plant, 133. Respiration in fungi, 134. Respiration in plants in general, 135. Respiration a breaking-down process, 136. Detailed result of the above experiment, 137. Another way of performing the experiment, 138. Intramolecular respiration, 139.. page 54

Chapter X. The Carbon Food Of Plants

Starch formed as a result of carbon conversion, 141. Iodine used as a test for starch, 142. Schimper's method of testing

Xll CONTENTS.

for the presence of starch, 143. Green parts of plants form starch when exposed to the light, 147. Starch is formed only in the green parts of plants, 148. Translocation of starch, 149. Stanch in other parts of plants than the leaves, 151. Form of starch grains, 153 page 59

Chapter XI. Chlorophyll And Formation Of Starch

Fungi cannot form starch, 155. Etiolated plants cannot convert carbon, 156. Chlorophyll and chloroplasts, 157. Form of the chlorophyll bodies, 158. Chlorophyll is a pigment which resides in the chloroplast, 159. Chlorophyll absorbs energy from sunlight for carbon conversion, 160. Rays of light concerned in carbon conversion, 161. Starch grains formed in the chloroplasts, 162. Carbon conversion in other than green plants, 164. Influence of light on the movement of chlorophyll bodies, 165 page 65

Chapter XII

nutrition; members of the plant body.

Nutrition of liverworts, 167. Riccia, 167. Marchantia, 168. Frullania, 169. Nutrition in the mosses, 170. The plant body, 171. Members of the plant body, 172. Stem series, 173. Leaf series, 174. The root, 175 page 70

Chapter XIII. Growth

Growth in mucor, 177. Formation of the gonidia, 178. The gonidia absorb water and increase in size before germinating, 179. How the gonidia germinate, 180. The germ tube branches and forms the mycelium, 181. Growth in length takes place only at the end of the thread, 1S2. Protoplasm increases by assimilation of nutrient substances, 183. Growth of roots, 184. Roots of the pumpkin, 185. The region of elongation, 186. Movement of the region of the greatest elongation, 187. Formative region, 188. Growth of the stem, 189. Force exerted by growth, 190. Grand period of growth, 191, Energy of growth, 193. Nutation, 194 page 75

CONTENTS, Xlll

Chapter XIV. Irritability

Influence of the earth on the direction of growth, 197. Influence of light on growth, 199. Influence of light on the direction of growth, 200. Diaheliotropism, 201. Epinasty and hyponastv, 202. Leaves with a fixed diurnal position, 203. Importance of these movements, 204. Influence of light on the structure of the leaf, 205. Movement influenced by contact, 206. Sensitive plants, 207. Movement in response to stimuli, 20S. Transmission of the stimulus, 209. Cause of the movement, 210. Paraheliotropism of the leaves of the sensitive plant, 211. Sensitiveness of insectivorous plants, 212. Hydrotropism, 213. Temperature, 214 page 82

Chapter XV. Spirogyra

Form of spirogyra, 220. Multiplication of the threads, 221. How some of the threads break, 222. Conjugation of spirogyra, 223. How the threads conjugate or join, 225. How the protoplasm moves from one cell to another, 226. The zygospores, 227. Life cycle, 228. Fertilization, 229. Simplicity of the process, 230. Position of the plant spirogyra, 231 page 93

Chapter XVI. Cedogonium

Form of oedogonium, 235. Fruiting stage of cedogonium, 236. Sexual organs of oedogonium; oogonium and egg y 237. Dwarf male plants, 238. Antheridium, 239. Zoospore stage of oedogonium, 240. Asexual reproduction, 241. Sexual reproduction, 242. Antheridia, 242. Oogonia, 243. CEdogonium compared with spirogyra, 244. Position of oedogonium, 245. Relatives of oedogonium, 246 page 99 xiv CONTENTS.

Chapter XVII

v.w CHERIA,

Zoogonidia of vauchcria, 248. Sexual reproduction in vaucheria, 249. Vaucheria sessilis, the sessile vaucheria, 250. Sexual organs of vaucheria, Antheridium, 251. Oogonium, 252. Fertilization, 253. The twin vaucheria (V. geminata), 254. Vaucheria compared with spirogyra, 255 page 109

CHAPTER XVIII. CO] EOCHiE IK

The shield-shaped coleochaete, 257. Fruiting stage of coleoch.vte, 258. Zoospore stage, 250. Asexual reproduction, 260, Sexual reproduction, oogonium, 261; antheridium, 262. Sporocarp, 263, Comparative table for spirogyra, vaucheria, cedogonium. and coleochiete, 264 page no

CHAPTER XIX. BROWN ANP RED AXGiB

Brown algSC (phfieophycea), 266. Form and occurrence of fucus, Structure of the conceptacles, 20S. Fertilization. 209. The red algae, 270. Gracillaria, 271. Rhabdonia, 272. Principal groups of alga\ 27 3 page 115

CHAPTER XX. fungi; moulds; water moulds; downy mildews.

Muc< Asexual reproduction. 276, Sexual stage. 277.

Gemms, 278, Water moulds (saprolegnia), 270. Anpear-

of the saproleg Sporangia oi saprolegnia,

281. Zoogonidia of saprolegnia, :^:. Sexual reproduction

of sapn 53 Downy mildews, 285 pace 120

CHAPTER XXI. Wheat rus graminis), 289. leleutospores of the

t-rust too. s rm.

DO on the barberry

CONTENTS. XV

293. How the cluster-cup stage was found to be a part of the wheat rust, 293^/. Uredospores can produce successive crops, 294. Teleutospores the last stage in the season, 295. How the fungus gets back from the wheat to the barberry, 296. Synopsis of life history of wheat rust, 297. Sac fungi, 299. Fruit bodies of the willow mildew, 300. Asci and ascospores, 301. The sac fungi or ascomycetes, 302. Classification of the fungi, 304 page 129

Chapter XXII. Liverworts

Riccia, 307. Form of the floating riccia (R. fluitans), 307. Form of the circular riccia (R. crystallina), 308. Sexual organs, 309. Archegonia, 310. Antheridia, 311. Embryo, 312. Sporogonium of riccia, 313. A new phase in plant life, 314 Riccia compared with coleochaete, cedogonium, etc., 315. Marchantia, 316. Antheridial plants, 317. Archegonial plants, 319 page 140

Chapter XXIII

liverworts {continued).

Sporogonium of marchantia, 320. Spores and elaters, 321. Sporophyte of marchantia compared with riccia, 322. Sporophyte dependent on the gametophyte for its nourishment, 323. Development of the sporogonium, 324. Embryo, 325. How marchantia multiplies, 326. Buds or gemmae of marchantia, 327. Leafy-stemmed liverworts, 328. Frullania, 329. Porella, 330. Sporogonium of a foliose liverwort, 331 . page 149

Chapter XXIV

Mnium, 334. The fruiting moss plant, 336. The male and female moss plants, 337. Sporogonium, 338. Structure of the moss capsule, 339. Development of the sporogonium, 342. Protonema of the moss, 343. Table showing relation of gametophyte and sporophyte in the liverworts and mosses, 344 , , page 158

XVI CONTENTS.

Chapter XXV

The Christmas fern, 346. Fruit dots, 347. Sporangia, 348. Structure of a sporangium, 349. Opening of the sporangium and dispersion of the spores, 351. How does the opening and snapping of the sporangium take place? 352. The movement of the sporangium can take place in old and dried material, 354. The common polopody, 356. Other ferns, 357. Opening of the leaves of ferns. 358. Longevity of ferns, 359. Budding of ferns, 360. The fern plant is*a sporophyte, 363. Is there a gametophyte phase in ferns? 364 page 165

CHAPTER XXVI. FERNS {concluded}

Gametophyte of ferns, 365. Sexual stage of ferns, 365. Spores, 367. Germination of the spores, 368. Protonema, 369. Prothallium, 370. Sexual organs of ferns, 371. Antheridia, 372. Archegonia, 373. Sporophyte, 374. Embryo, 374. Comparison of ferns with liverworts and mosses, 375 . .page 176

Chapter XXVII. Horsetails

The field equisetum, 380. Fertile shoot, 380. Sporangia, 381. Spores, 382. Sterile shoot of the common horsetail, 383. The scouring rush or shave grass, 384. Gametophyte of equisetum, 385 page 1S7

Chapter XXVIII. Club Mosses

The clavate lycopodium, 387. Fruiting spike of Lycopodium clavatum, 388. Lycopodium lucidulum, 389. Bulbils on Lycopodium lucidulum, 390. The little club mosses, 392. Sporangia, macrospores and microspores, 393. Male prothallia, 394. Female prothallia, 395. Embryo, 396. .. .page 191

CONTENTS. XVI 1

Chapter XXIX. Quillworts

Sporangia of isoetes, 398. Male prothallia, 401. Female pro-

thallia, 402. Embryo, 403 page 196

Chapter XXX. Comparison Of Ferns And Their Relations

Comparison of selaginella and isoetes with the ferns, 404. General classification of ferns, 407. Table showing relation of gametophyte and sporophyte in the pteridophyta, 408. -page 199

Chapter XXXI. Gymnosperms

The white pine, 409. General aspect of the white pine, 409. The long shoots of the pine 410. The dwarf shoots of the pine, 411. Spore-bearing leaves of the pine, 412. Male cones or male flowers, 413. Microspores of the pine, or pollen grains, 414. Form of the mature female cone, 415. Form of a scale of the female flower, 417. Ovules or macrosporangia of the pine, 418. Pollenation, 419. Female prothallium of the pine, 422. Archegonia, 423. Male prothallia, 424. Farther growth of the male prothallium, 425. Fertilization, 426. Homology of the parts of the female cone, 427 page 202

Chapter XXXII. Farther Studies On Gymnosperms

Cycas, 428. Female prothallium of cycas, 429. Microspores or pollen of cycas, 431. The gingko tree, 432. Spermatozoids in some gymnosperms, 434. The sporophyte in the gymnosperms, 435. The gametophyte has become dependent on the sporophyte, 436. Gymnosperms are naked seed plants, 437. Classification of gymnosperms, 438. Table showing homologies of sporophyte and gametophyte in the pine, 439 page 214

XV111 CONTENTS.

Chapter XXXIII

MORPHOLOGY OF THE ANGIOSPERMS. TRILLIUM; DENTARIA.

Trillium, 440. General appearance, 440. Parts of the flower, calyx, 441. Corolla, 442. Androecium, 443. The stamen a sporophyll, 444. Gyncecium, 445. Transformation of the flower of trillium, 446. Dentaria, 447. General appearance, 447. Parts of the flower, 448 page 221

Chapter XXXIV. Gametophyte And Sporophyte Of Angiosperms

Male prothallium of angiosperms, 450. Macrospore and embryo-sac, 453. Embryo-sac is the young female prothallium, 445. Fertilization, 456. Fertilization in plants is fundamentally the same as in animals, 457. Embryo, 458. Endosperm the mature female prothallium, 459. Seed, 460. Perisperm, 461. Presence or absence of endosperm in the seed, 462. Sporophyte is prominent and highly developed, 463. The gametophyte once prominent has become degenerate, 464. Synopsis of members of the sporophyte in angiosperms, 467. Table showing homologies of sporophyte and gametophyte in angiosperms, 468 page 228

Chapter XXXV

MORPHOLOGY OF THE NUCLEUS AND SIGNIFICANCE OF GAMETOPHYTE AND SPOROPHYTE.

Direct division of the nucleus, 470. Indirect division of the nucleus, 471. Chromatin and linin of the nucleus, 472. The chromatin skein, 473. Chromosomes, nuclear plate, and nuclear spindle, 474. The number of chromosomes usually the same in a given species throughout one phase of the plant, 474<?. When fertilization takes place the number of chromosomes is doubled in the embryo, 474^. Reduction of the number of chromosomes in the nucleus, 475. Significance of karyokinesis and reduction, 476. The gametophyte may develop directly from the tissue of the sporophyte, 477. The sporophyte may develop directly from the tissue of the gametophyte, 478. Perhaps there is not a fundamental difference between the gametophyte and sporophyte, 479. page 239

CONTENTS. XIX

LESSONS ON PLANT FAMILIES.

Chapter XXXVI. Relationships Shown By Flower And Fruit

Importance of the flower in showing kinships among the higher plants, 480. Arrangement of flowers, 482. The fruit, 485

Chapter XXXVII. Monocotyledons

(For lessons and topics see synopsis at close of the lessons.) Classification, 4S6. Species, 486. Genus, 487. Genus trillium, 4S8. Genus erythronium, 489. Genus lilium, 490. Family liliaceae, 491. Floral formula, 492. Cohesion and adhesion, 493. Floral diagram, 494 page 251

ECOLOGY.

INTRODUCTION. page 300

Chapter XLIV

winter buds; growth of woody shoots; leaf arrangement.

Winter buds and how the young leaves are protected, 564. Twigs and buds of the horse-chestnut, 365. Leaf scars, 566. Lateral buds, 507. Hud leaves, 56S Opening of the buds in the spring, 569, Growth in thickness of woody stems, 571. Difference in the firmness of the woody rings, 575. Annual rings in woody stems. 576. Phyllotaxy or arrangement of leaves, 579 P a ge 302

Chapter XLV. Seedlings

The common garden bean. 5S4. The castor-oil bean, 5S5. How the embryo gets out of a pumpkin seed, 5S6. Arisctma 588. Germination of the seed of ** jack-in-the-pulpit," 5SS. How the embryo backs out of the seed, 5S9. How the first leaf appears, 591. The first leaf of " jack-inthe pulpit " is a simple one, 592 page 307

Chapter XLVI. Further Studies On Nutrition

\ trition in lem: Spirodela polyrrhiza. 505. Nutrition

in wolffia, 5 / . Nutrition in lichens, 597. Nitrogen

rs, ; How clovers, peas, and other legumes

gather 1 A Fungal or bacterial organism in

thes, :bercles, 600. How the organism cets in the

s of the legumes. 601. The r ganisi -<:milates

its host. 602. Mycorhiza, 603. Nutrition

of the dodder, 605. Carr plants, 606. Nutrition of

CONTENTS. xxi

CHAPTER XLVII. FURTHER STUDIES ON NUTRITION {concluded)

Nutrition of moulds, 608. Nutrition of parasitic fungi, 609. Nutrition of the larger fungi, 610. Studies of mushrooms, 613. Form of the mushroom, 613. Fruiting surface of the mushroom, 614. How the mushroom is formed, 615. Heware of the poisonous mushrooms, 617. Wood-destroying fungi, 619 page 322

Chapter XLVIII. Dimorphism Of Ferns

Dimorphism in the leaves of ferns, 624. The sensitive fern, 625. Transformation of the fertile leaves of onoclea to sterile ones, 626. The sporangia decrease as the fertile leaf expands, 62S. The ostrich fern, 629. Dimorphism in tropical ferns, 630 page 340

Chapter XLIX. Formation Of Early Spring Flowers

Trillium, 631. The adder tongue (erythronium), 633. Indian

turnip, 634 ' page 347

Chapter L

HETEROSPORY. POLLENATION.

Origin of heterospory and the necessity for pollenation, 639. Both kinds of sexual organisms on the same prothallium, 639. Cross fertilization in monoecious prothallia, 640. Tendency toward dioecious prothallia, 641. The two kinds of sexual organs on different prothallia, 642. Permanent separation of the sexes by different amounts of nutriment supplied the spore, 643. Heterospory, 644 In the pteridophytes water serves as the medium for conveying the sperm cell to the female organ. 645. In the higher plants a modification of the prothallium is necessary, 6^6. Pollenation ^ 649. Self pollenation or close pollenation, 649. Wind pollenation, 650 Pollenation by insects, 651. Pollenation of the bluet, 653. Pollenation of the primrose, 654. Pol-

XXll CONTENTS.

lenation of the skunk's cabbage, 655. Spiders have discovered this curious relation of the flowers and insects, 657. Pollenation of jack-in-the-pulpit, 658. Pollenation of orchids, 660. Pollenation of canna, 664 page 351

Chapter LI. Seed Distribution

Means for dissemination of seed, 672. The prickly lettuce, 676. The wild lettuce, 677. The milk-weed or silk-weed, 678. The virgin's bower, 680 page 368

Chapter LII. Struggle For Occupation Of Land

Retention of made soil, 681. Vegetation of sand dunes, 683.

Reforestation of lands, 0S4. Beauty of old fields, 6S9. .page 374

Chapter LIII. Soil Formation In Rocky Regions And In Moors

Lichens, 690. Lichens are among the pioneers in soil formation, 691. Other plants of rocky regions, 692. Filling of ponds by plants, 694. A plant atoll, 695. Topography of the atoll moor, 696. A floating inner zone, 698. How was the atoll formed ? 700. A black-spruce moor, 703. Fall of the trees of the marginal zone when the windbreak was removed, 704. Dying of the spruce of the central area, 705. Other morainic moors, 70S. The bald cypress (taxodium), 711 P a £ e :^ s "

Chapter LIV. Zonal Distribution Of Plants

On the margins of lakes and ponds, 712. On the banks of a

stream, 716 page 400

CHAPTER LV. PLANT COMMUNITIES; SEASONAl chances

Plants of widely different groups may exist in the same community, 720. Seasonal succession in plant communities,

CONTENTS. xxill

722. The landscape a changing panorama, 725. Refoliation of bare forests in the spring, 726. The summer tints are more subdued, 728. Autumn colors, 729. Fall of the leaf, 730 page 410

Chapter LVI. Adaptation Of Plants To Climate

Some characteristics of desert vegetation. 731. Some plants of temperate regions possess characters of desert vegetation, 735. Alpine plants with desert characters, 737. Low stature of alpine plants a protection against wind and cold, 738. Some plants of swamps and moors present characters of arctic or desert vegetation, 739. Hairs on young leaves protect against cold, 740 page 419

BOTANY.

Chapter I

1. In the study of plant life and growth, it will be found convenient first to inquire into the nature of the substance which we call the living material of plants. For plant growth, as well as some of the other processes of plant life, are at bottom dependent on this living matter. This living matter is called in general protoplasm.

2. In most cases protoplasm cannot be seen without the help of a microscope, and it will be necessary for us here to employ one if we wish to see protoplasm, and to satisfy ourselves by examination that the substance we are dealing with is protoplasm.

3. We will find it convenient first to examine protoplasm in some of the simpler plants ; plants which from their minute size and simple structure are so transparent that when examined with the microscope the interior can be seen.

For our first study we will take a plant known as spirogyra, though there are a number of others which would serve the purpose quite as well, and may quite as easily be obtained for study.

*For apparatus, reagents, collection and preservation of material, etc., see Appendix.