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Te = i Np ala I Bier, og bene Cand alg Fee Ne Taba le Made Pe hot Tf ete Bete wee men ope nee ese gee renmenaseseia tet 3 pa _ ~~ Haye (Peet etheg © —wtee regan er 0h e te BRO op mye pyan an . rd 2 eS OE RE Ee oo ee SCORER — 5 phe eds deen ge 4) A ‘OCT 21 1848 ¢ Se" aN ister of Con oe Fe ee, TWO COPIES RECEIVED. one ee Cor OEE FIGE OF THE *s 61965 OC 21 1898 — NE, ‘ “ "i AN t \) ieisten ye HoRYR a ” — a ALS bab AQ x RAYG Wisba\ ) a Crca VOLUTA (see page 214). (Frontispiece.) aca a “ae : “ ao 5 ale ee el . ‘ Pea Ch, UNTIL recent years the prevalent method of teaching botany in the secondary schools, and in the first courses in many col- leges, has been based on the .‘‘analysis’’ of flowers. The method had its impetus in the study of systematic botany pur- sued 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 xf secondary instruction in this subject. It is now generally ognized that a study of the lower plants, like the alge, fungi, 2rworts, 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 guid- nee in the selection of topics, and an outline of the character of the study, could be met by zamber 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 sclection 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 draw- ing 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. great 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 : : ‘ ' ] q ' ie lV 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 in- struction of a large class of beginners, the majority of whom had never studied the subject before. One of the great diff- culties encountered in attempting to introduce the study of the lower plants is the fact that these plants are in most cases en- tirely unknown to the pupil. ‘The difficulty does not lie in the attempt to introduce the study of unknown objects. But it les rather in the attempt to study the lower plants, at the outset, in a more or less thorough manner, to learn their characters, rela- tionships, 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 prin- ciples 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 progres- sion 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 struc- ture, and also those which are easily obtained. A second period of the session’ can then be devoted to study- PREFACE. V ing a few representatives of the different groups of the alge, 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 selec- tion 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 gen- eral 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 reproduc- tion can be more easily observed. In the higher plants the sexual orgams 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 our- selves 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 with- out 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 com- munion with the very soul of nature, and of becoming ac- vi PREFACE. quainted with the haunts, the lives, the successes and failures of plants; the influences of soil, moisture, and other environ- mental 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 dis- tribution in plant formations, etc. In all this study a knowl- edge of some of the lower plants is important. It is not intended that the matter in the book should be mem- orized for the purpose of recitations. It should be used as a guide to the practical work, and as areference book. ‘The para- graphs arranged in coarse print are intended in general to indi- cate 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 fur- ther 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 in the botanical department of Cor- nell University who have read the manuscript and have made useful suggestions ( Messrs. E. J. Durand, B. M. 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, of Smith College, who read some of the chapters on ecology and the tables on the homologies of the gymnosperms and angiosperms. PREFACE. Vil 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. Mell, 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 Mis- souri Botanical Garden. Many of the drawings, especially those of microscopic objects, were made by the author; others by Mr. H. Hasselbring, Cor- nell 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 Agri- cultural College; Mr. Joseph Bridgham, Providence, R. L; 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. Pro- fessor 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 Hirase, of the Imperial University of Japan, Tokio, for their unparalleled courtesy in sending drawings of the sperma- tozoids, and of fertilization, in cycas and gingko, in advance of their publication. CORNELL UNIVERSITY, June, 1898. = 7 ‘a. —= “sr et. a : | ‘ —_ a d ; , ' - ’ - 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. Protoplasm in mucor, 12. Mycelium of mucor, 13. Appearance of the protoplasm, 14. Move- ment of the protoplasm in mucor, 15. Test for protoplasm, 16. Protoplasm in nitella, 17. Form of nitella, 18. Inter- node of nitella, 19. Cyclosis in nitella, 20. Test for proto- plasm, 21. Pyrotoplasm in one of the higher plants, 22. Movement of protoplasm in the higher plants, 23. Move- ment of protoplasm in cells of staminal hair of spiderwort, 24. Cold retards the movement, 25. Protoplasm occurs in una REELS KAT CLIT (LANES PO. oe el sic oka e ele ee ss page CHAPTER UAE. 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 x CON TEN FS. 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 car- ried 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. TZtssue tensions, 61. Longitudinal tissue tension, 62. Transverse tissue tension, 65.2... 0.2.2 $4 ee page 28 CHAPTER V. ROOT PRESSURE. Root pressure may be measured, 67. Experiment to demon- Strate\root pressure, 68.0... .2.0 3.000 eos Sa ee page 31 CHAPTER (VI. TRANSPIRATION. Loss of water from excised leaves, 71. Loss of water from growing plants, 72. Water escapes trom the surfaces of living leaves in the form of water vapor, 73. Experiment to compare loss of water in a dry and a humid atmcsphere, 74. The loss of water is greater ina dry than in a humid atmosphere, 75. How transpiration takes place, 76. Struc- — ture of a leaf, 79. Epidermis of the leaf, 80. Soft tissue of the leaf, 8r. Stomata, 82.. The living protoplasm re- tards 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. Dem- onstration of stomates and intereellular 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, g4. These solutions color the tracts in the stem and leaves through which they flow, 95. Structure of the fibro-vascu- lar bundles, 98. Woody portion of the bundle, 99. Bast portion of the bundle, 100. Cambium region of the bundle, 1or. Longitudinal section of the bundle, 102. Vessels or ducts, 103. Sieve tubes, 105. Fibro-vascular bundle in In- dian corn, 107. Rise of water in the vessels, 108. Synopsis EMRE EO Sts poe Leu wicty Goats ce us bs 0 a's Gone oh a a ew ees page 42 CHAPTER «Vill. DIFFUSION OF GASES. Gas given off by green plants in the sunlight, 111. 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 page 49 CHAPTER IX. RESPIRATION. Oxygen from the air consumed during germination of seed, 127. Carbon dioxide given off during germination, 128. Respi- ration is necessary for growth,130. Energy set free during respiration, 132. Respiration in a leafy plant, 133. Respi- ration 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 atest for starch, 142. Schimper’s method of testing sy aS Fungi cannot form starch, 155. Etiolated plants cannot convert 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,1r49. Starch in other parts of plants than the leaves, r5T, Form ef starch grains, 193. .<< «>: sae page CHAPTER 236 CHLOROPHYLL AND FORMATION OF STARCH. 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 ehloroplivll bodies; \265). ». «6... . 44.40% 20) scien page CHAPTER AM. 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. ‘Tie root, T75-.-... cd... eee page CHAPTER XITi. GROWTH. Growth in mucor, 177. Formation of the gonidia, 178. The gonidia absorb water and increase in size before germinat- ing, 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, 182. Proto- plasm 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, 59 65 70 75 CONTENTS. CHAPTER XIV. IRRITABILITY. Influence of the earth on the direction of growth, 197. Influ- ence of light on growth, 199. Influence of light on the di- rection of growth, 200. Diaheliotropism, 201. Epinasty and hyponastv, 202. Leaves witha fixed diurnal position, 203. Importance of these movements, 204. Influence of light on the structure of the leaf, 205. Movement influ- - enced by contact, 206. Sensitive plants, 207. Movement in response to stimuli, 208. Transmission of the stimulus, 209. Cause of the movement, 210. Paraheliotropism of the leaves of the sensitive plant, 211. Sensitiveness of insec- tivorous plants, 212. Hydrotropism, 213. Temperature, . PART EL MORPHOLOGY. CPAP TER, XY. SPIROGYRA. Form of spirogyra, 220. Multiplication of the threads, 22t. How some of the threads break, 222. Conjugation of spiro- gyra, 223. How the threads conjugate or join, 225. How the protoplasm moves from one cell to another, 226. The gyeospotes, 227... Life cycle, 228: Fertilization, 229... Sim- plicity of the process, 230. Position of the plant spirogyra, CHAPTER AVI: (EDOGONIUM. Form of cedogonium, 235. Fruiting stage of cdogonium, 236. Sexual organs of cedogonium; oogonium and egg, 237. Dwarf male plants, 238. Antheridium, 239. Zoospore stage of cedogonium, 240. Asexual reproduction, 241. Sex- ual reproduction, 242. Antheridia, 242. Oogonia, 243. (Edogonium compared with spirogyra, 244. Position of cedogonium, 245. Relatives of cdogonium, 246....... page XIil 82 a XIV CONTENTS. CHAPTER XVII. VAUCHERIA. Zoogonidia of vaucheria, 248. Sexual reproduction in vau- cheria, 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 I09 CHAPTER XVIII. COLEOCH ETE, The shield-shaped coleochete, 257. Fruiting stage of coleo- chete, 258. Zoospore stage, 259. Asexual reproduction, 260. Sexual reproduction, oogonium, 261; antheridium, 262. Sporocarp, 263. Comparative table for spirogyra, vaucheria, edogonium, and coleochete, 264........... page II10 CHAPTER XIX. BROWN AND RED ALG. Brown algz (pheophycee), 266. Form and occurrence of fucus, 267. Structure of the conceptacles, 268. Fertilization, 269. The red algz, 270. Gracillaria, 271. Rhabdonia, 272. Principal groups of algs,.273.... . ss s.sskeasee : < Sane page II5 CHAPTER XX. FUNGI; MOULDS; WATER MOULDS; DOWNY MILDEWS. Mucor, 275. Asexual reproduction, 276. Sexual stage, 277. Gemme, 278. Water moulds (saprolegnia), 279. Appear- ance of the saprolegnia, 280. Sporangia of saprolegnia, 281. Zoogonidia of saprolegnia, 282. Sexual reproduction of saprolegnia, 283. Downy mildews, 285............. page 120 CHAPTER XXI. FUNGI (continued); RUSTS; ASCOMYCETES. Wheat rust (Puccinia graminis), 289. Teleutospores of the black-rust form, 290. Uredospores of the red-rust form, 291. Cluster-cup form on the bafberry, 292. Spermagonia, CONTENTS. XV 293. How the cluster-cup stage was found to be a part of the wheat rust, 293a. 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. Clas- ID AO TMM S: S00 hes eek ie ida asieeees page 129 CHAPTER: AXIT. 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 coleochete, cedogonium, etc., 315. Marchantia, 316. Antheridial plants, 317. Archegonial NR oo ewig n 5.4 2 oww'n's dine bm, We ad we se awe 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 nourish- ment, 323. Development of the sporogonium, 324. Em- bryo, 325. How marchantia multiplies, 326. Buds or gemmez of marchantia, 327. Leafy-stemmed liverworts, 328. Frullania, 329. Porella, 330. Sporogonium of a foliose ENE BE ROAR air ate ure |e a ae gee page 149 CHAPTER XXIV. MOSSES. Mnium, 334. The fruiting moss plant, 336. The male and fe- male 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...-.. Puente eneenee He Nips ails Mwtere Pye sin hale © wh page 158 — XVI CONTENTS. CHAPTER. XXV. FERNS. The Christmas fern, 346. Fruit dots, 347. Sporangia, 343: Structure of a sporangium, 349. Opening of the sporan- gium 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? AOA go's noe ewe els a8 oon we aiterele.e wid Tee Oe Fi Bevel aes eee page 165 CHAPTER AW i: 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 aos. Comparison of ferns with liverworts and mosses, 375 ..page 176 CHAPTER, ARVIt 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, 985... . 65st ws 4 be Wes o5.ss 0 aly seen page 187 CHAPTER AXAVIIT. CLUB MOSSES. The clavate lycopodium, 387. Fruiting spike of Lycopodium clavatum, 388. Lycopodium lucidulum, 389. Bulbils on Lycopodium lucidulum, 390. Zhe Uittle club mosses, 392. Sporangia, macrospores and microspores, 393. Male pro- thallia, 394. Female prothalliay 395. Embryo, 396....page 191 CONTENTS. XVil CHAPTER XXIX. QUILLWORTS. Sporangia of isoetes, 398. Male prothallia, gor. Female pro- Se ROME VC, AG Wo kes isle es ee ee eee ee page 196 | CHAP LER) AXX. COMPARISON OF FERNS AND THEIR RELATIONS. Comparison of selaginella and isoetes with the ferns, 404. Gen- eral classification of ferns, 407. Table showing relation of gametophyte and sporophyte in the pteridophyta, 408..page 199 | : CHAPTER’ XXXII. GYMNOSPERMS. The white pine, 409. General aspect of the white pine, 4og. 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 macro- sporangia of the pine, 418. Pollenation, 419. Female pro- thallium of the pine, 422. Archegonia, 423. Male prothal- lia, 424. Farther growth of the male prothallium, 425. Fertilization, 426. Homology of the parts of the female CONG, 4A2]7---.-..+--+-- Says! Steg tth scav Silos n Minteh pia aie: be voysat wie eB oa )ai << > 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 gymno- sperms, 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, EE Orta ie alah Chelan an Ga nie oo eis ee a eb 8 he's page 214 > ce — XVill CONTENTS. CHAPTER: AXXAIMI. MORPHOLOGY OF THE ANGIOSPERMS. TRILLIUM; DENTARIA. Trillium, 440. General appearance, 440. Parts of the flower, calyx, 441. Corolla, 442. Androecium, 443. The stamena sporophyll, 444. Gyncecium, 445. Transformation of the flower of trillium, 446. Dentaria, 447. General appear- ance, 447. Parts of the flower, 448:........ 7) eee page 221 CHAPTER AARIV: GAMETOPHYTE AND SPOROPHYTE OF ANGIOSPERMS. Male prothallium of angiosperms, 450. Macrospore and em- bryo-sac, 453. Embryo-sac is the young female prothal- lium, 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 degen- erate, 464. Synopsis of members of the sporophyte in angiosperms, 467. Table showing homologies of sporo- phyte 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 nu- cleus, 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 ina given species throughout one phase of the plant, 474a. When fertilization takes place the number of chromosomes is doubled in the embryo, 4744. Reduction of the number of chromosomes in the nucleus, 475. Signifi- cance 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 dif- ference between the gametophyte and sporophyte, 479.page 23g CONTENTS. X1X 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 page 247 CHAPTER XXXVII. MONOCOTYLEDONS. (For lessons and topics see synopsis at close of the lessons.) Classification, 486. Species, 486. Genus, 487. Genus trillium, 488. Genus erythronium, 489. Genus lilium, 490. Family liliacez, 491. Floral formula, 492. Cohesion and adhe- PPMeenr HOOT H) Cina, AQ4 oc. . 2 es ys. oe ee wees page 251 CHAPTER “AXAVIIT. MONOCOTYLEDONS (concluded )..........+++++. 258 CHAPTER AXXIX. BUNCH) PACE PRON Gee conc o Seals o oak bik earn 262 CHAPTER AP: DIC@TYLEDONS (C0ut71027 ).. 2 ges sass ee ses 265 CHAP EER ET. BICOEVER DONS (ComriiUed).bi Fe a ie see 273 CHAPTER XLII. PILOTVERDGNS (cotcluded Foose. sus ks Je 383 SHAPER ALIS. OUTLINE OF TWENTY LESSONS IN THE ANGIOSPERMS...-. 294 CONTENTS. PAR ete. 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, 565. Leaf scars, 566. Lateral buds, 567. Bud leaves, 568 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 arrange- ment of leaves, 579. ~. 45... 225 6s eden ap te hee page CHAPTER ALY. SEEDLINGS. The common garden bean, 584. The castor-oil bean, 585. How the embryo gets out of a pumpkin seed, 586. Avrisema triphyllum, 588. Germination of the seed of ‘‘ jack-in-the- pulpit,” 588. How the embryo backs out of the seed, 589. How the first leaf appears, 591. The first leaf of ‘*‘ jack-in- the-pulpit” is a simple one, §92.............:< . see page CHAPTER XLVI. FURTHER STUDIES ON NUTRITION. Nutrition in lemna, 594. Spirodela polyrrhiza, 595. Nutrition in wolffia, 596. Nutrition in lichens, 597. Nitrogen gatherers, 599. How clovers, peas, and other legumes gather nitrogen, 599. A fungal or bacterial organism in these root tubercles, 600. How the organism gets in the roots of the legumes, 601. The root organism assimilates free nitrogen for its host, 602. Mycorhiza, 603. Nutrition of the dodder, 605. Carnivorous plants, 606. Nutrition of DSCC GIG GRRE he i g's Usk ces wma cen’ +s es oo nha en page 302 307 314 | | EE | | | | | | . : | : | | | i] CONTENTS. 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. Be- ware of the poisonous mushrooms, 617. Wood-destroying SS ere ee Ge Ae a i ae et Bae page 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, 628. The ostrich fern, 629. Dimorphism in tropi- ge ipa ci ge ie al Sn nie we Welw © 0:0 0.06 page LRAPTER.” XLEX. FORMATION OF EARLY SPRING FLOWERS. Trillium, 631. The adder tongue (erythronium), 633. Indian arene. Cote ibe s aetna ae 2 Pion whe 58 ows page CHAPTER L.. HE'TEROSPORY. POLLENATION. Origin of heterospory and the necessity for pollenation, 639. Both kinds of sexual organisms on the same prothallium, 639. Cross fertilization in moncecious prothallia,640. Ten- dency toward dioecious prothallia, 641. The two kinds of sexual organs on different prothallia, 642. Permanent sep- aration of the sexes by different amounts of nutriment supplied the spore, 643. Heterospory, 644. In the pterido- phytes water serves as the medium for conveying the sperm cell to the female organ, 645. Inthe higher plants a modification of the prothallium is necessary, 646. /ol/ena- tion, 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- XxXI 322 340 347 XxXil CONTENTS. lenation of the skunk’s cabbage, 655. Spiders have discov- ered this curious relation of the flowers and insects, 657. Pollenation of jack-in-the-pulpit, 658. Pollenation of or- chids, 660. Pollenation of canna, 664...............0. page CHAPTER, LL 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 boyer, G80. oi. eicsicss 6 sar. 3% 0's 1 page CHAP FER Li. STRUGGLE FOR OCCUPATION OF LAND. Retention of made soil, 681. Vegetation of sand dunes, 683. Reforestation of lands, 684. Beauty of old fields, 689. .page CHAPTER “ELT. SOIL FORMATION IN ROCKY REGIONS AND IN MOORS. Lichens, 690. Lichens are among the pioneers in soil forma- tion, 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? 7oo. <= coe SO ee fad Ov.» — “3 — RS ee Alle PS ee a Ae Soe a aSiaes TEOEO ES z i ( ~ Re SS ey Oe re) a = pile pe Ione ne Ds 2 A <5<- ,. : a Rs gi oe se es ee = 4 4 -, «7 See ioo8 ass 27% , = i er paar ESUe es Fig. 10. Cell from stamen hair of tradescantia showing movement of the protoplasm. nucleus is quite prominent, and its location in the cell varies con- siderably in different cells and at different times. There is a layer of protoplasm all around the nucleus, and from this the strands of protoplasm extend outward to the wall layer. The large spaces between the strands are, as we have found in other cases, filled with the cell-sap. An entire stamen, or a portion of the stamen, having several hairs attached, should be carefully mounted in water. Care should be taken that the room be not cold, and if the weather is cold the water in which the preparation is mounted should be warm, With these precautions there should be little diffi- culty in observing the streaming movement. The movement is detected by observing the gliding of the granules. ‘These move down one of the strands from the nucleus along the wall layer, and in towards the nucleus in another strand. After a little the direction of the movement in any one portion may be reversed. 25. Cold retards the movement.—While the protoplasm is moving, if we rest the glass slip on a block of ice, the move- ment will become slower, or will cease altogether. Then if we 4 Ally ——_—- I2 PHYSIOLOGY. warm the slip gently, the movement becomes normal again. We may now apply here the usual tests for protoplasm. ‘The result is the same as in the former cases. 26. Protoplasm occurs in the living parts of all plants.— In these plants representing such widely different groups, we find a substance which is essentially alike in all. Though its arrange- ment in the cell or plant body may differ in the different plants or in different parts of the same plant, its general appearance is the same. ‘Though in the different plants it presents, while alive, varying phenomena, as regards mobility, yet when killed and subjected to well known reagents the reaction is in general identical. Knowing by the experience of various investigators that protoplasm exhibits these reactions under given conditions, we have demonstrated to our satisfaction that we have seen proto- plasm in the simple alga, spirogyra, in the common mould, mucor, in the more complex stonewort, nitella, and in the cells of tissues of the highest plants. 27. By this simple process of induction of these facts concerning this substance in these different plants, we have learned an im- portant method in science study. ‘Though these facts and deduc- tions are well known, the repetition of the methods by which they are obtained on the part of each student helps to form habits of scientific carefulness and patience, and trains the mind to logical processes in the search for knowledge. 28. 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 gran- ules. Itis irritable. In the living condition it resists more or less for some time the absorption of certain coloring substances. The water may be with- drawn by glycerine. The protoplasm may be killed by alcohol. When treated with iodine it becomes a yellowish-brown color, CHAPTER: Li, ABSORPTION, DIFFUSION, OSMOSE. 29. We may next endeavor to learn how plants absorb water or nutrient substances in solution. ‘There are several very instructive experiments, which can be. easily performed, and here again some of the lower plants will be found useful. 30. Osmose in spirogyra. this plant in water for microscopic examination, and then draw Let us mount a few threads of under the cover glass a five per cent solution of ordinary table salt (NaCl) with the aid of filter paper. We shall soon see that the result is similar to that which was obtained when glycer- ine was used to extract the water from the cell-sap, and to con- tract the protoplasmic membrane from the cell wall. But the process goes on evenly and the plant is not injured. The proto- plasmic layer contracts slowly from the cell wall, and the move- ment of the membrane 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 center of the cell. If we now add fresh water and draw off the salt solution, we can see the protoplasmic membrane expand again, or move out in all directions, and occupy its former position against the inner surface of the cell wall. ‘This would indicate 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 tendency to form a vacuum in the cell, and the pressure pn the outside of the protoplasmic membrane causes it 1) 4 14, PH VSIOLOGY. to move toward the center 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 mem- brane out against the cell wall again. Fig. 13. Spirogyra from salt solution into water. Fig. or. Spirogyra before placing in salt solu- Fig. 12. tion. Spirogyra in 5% salt solution. 31. Turgescence.—Were it not for the resistance which the cell wall offers to the pressure from within, the delicate proto- ABSORPTION, DIFFUSION, OSMOSE. 15 plasmic membrane would stretch to such an extent that it would be ruptured, and the Ltd saa 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. * his? is: brought about. by the press- Before treatment with salt —+= solution. “A ure from within Fig. 15. reatment with salt solution. upon the proto- ,... , plasmic mem- brane which itself presses against : the cell wall, and causes it to Fig. 16. ee eutward. —Thisis—beauti- From salt solution placed in water. fully shown in the case of threads 5 PMR aD ir aaa ial which are recently broken. ‘The cell wall is therefore elastic; it yields to a certain extent to the pressure from within, but a point is soon reached beyond which it will not stretch, and an equilibrium then exists between the pressure from within on the protoplasmic membrane, and the pressure from without by the elastic cell wall. This state of equilibrium in a cell is /urges- cence, or such a cell is said to be /urgescent, or turgid. 32. Experiment with beet in sait and sugar solutions.— We may now test the effect of a five per cent salt solution on a portion of the tissues of a beet or carrot. Let us cut several slices of equal size and about 5mm in thickness. Immerse a few slices in water, a few in a five per cent salt solution and a few in a strong sugar solution. It should be first noted that all the slices are quite rigid when an attempt is made to bend them between the fingers. In the course of one or two hours or less, . 16 PHVSIOLOGY. if we examine the slices we will find that those in water remain, as at first, quite rigid, while those in the salt and sugar solutions are more or less flaccid or limp, and will readily bend by pres- Fig. 17. Fig. 18. Fig. 19. Before treatment with salt After treatment with salt From salt solution into water solution. solution. again. Figs. 17-19.—Osmosis in cells of Indian corn. sure between the fingers, the specimens in the salt solution, perhaps, being more flaccid than those in the sugar solution. The salt solution, we judge after our experiment with spirogyra, De See Zee 8 Fig. 20. Fig, 21. Fig. 22. Rigid condition of fresh beet Limp condition after lying in Rigid again after lying again section. salt solution. in water. Figs. 20-22.—Turgor and osmosis in slices of beet. withdraws some of the water from the cell-sap, the cells thus losing their turgidity and the tissues becoming limp or flaccid from the loss of water, * ABSORPTION, DIFFUSION, OSMOSE. 17 33. Let us now remove some of the slices of the beet from the sugar and salt solutions, wash them with water and then im- merse 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 sub- stances 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. 34. Osmose in the cells of the beet.— We should now make a section of the fresh tissue of a red colored beet for examination with the microscope, and treat this section with the salt solution. Here we can see that the effect of the salt solution is to draw water out of the cell, so that the protoplasmic mem- Bis. 23. Fig. 24. Fig. 25. Before treatment with salt After treatment with salt Later stage of the same. solution. solution. Figs. 23-25.—Cells from beet treated with salt solution to show osmosis and movement of the protoplasmic membrane. brane can be seen to move inward from the cell wall just as was observed in the case of spirogyra.* Now treating the section with water and removing the salt solution, the diffusion current is in the opposite direction, that is in- * We should note that the coloring matter of the beet resides in the cell- sap. It is in these colored cells that we can best see the movement take place, since the red color serves to differentiate well the moving mass from the cell wall. The protoplasmic membrane at several points usually clings tena- ciously so that at several places the membrane is arched strongly away from the cell wall as shown in fig. 24. While water is removed from the cell-sap, we note that the coloring matter does not escape through the protoplasmic membrane, 18 PHYSIOLOGY. ward through the protoplasmic membrane, so that the latter is pressed outward until it comes in contact with the cell wall again, which by its elasticity soon resists the pressure and the cells again become turgid. 35. The coloring matter in the cell-sap does not readily escape from the living protoplasm of the beet.—The red coloring matter, as seen in the sec- tion under the microscope, does not escape from the cell-sap through the pro- toplasmic membrane. When the slices are placed in water, the water is not colored thereby. The same is true when the slices are placed in the salt or sugar solutions. Although water is withdrawn from the cell-sap, this coloring substance does not escape, or if it does it escapes slowly and after a consider- able time. 36. The coloring matter escapes from dead protoplasm.—If, however, we heat the water containing a slice of beet up to a point which is sufficient to kill the protoplasm, the red coloring matter in the cell-sap filters out through the protoplasmic membrane and colors the water. If we heat a preparation made for study under the microscope up to the thermal death point we can see here that the red coloring matter escapes through the membrane into the water outside. ‘This teaches that certain substances cannot readily filter through the living membrane of protoplasm, but that they can filter through when the protoplasm is dead. A very important condition, then, for the suc- cessful operation of some of the physical processes connected with absorption in plants is that the protoplasm should be in a living condition. 37. Osmose experiments with leaves.—We may next take the leaves of certain plants like the geranium, coleus or other plant, and place them in shallow vessels containing water, salt, and sugar solutions respectively. The leaves should be immersed, but the petioles should project out of the water or solutions. Seedlings of corn or beans, especially the latter, may also be placed in these solutions, so that the leafy ends are immersed. After one or two hours an examination will show that the specimens in the water are still turgid. But if we lift a leaf or a bean plant from the salt or sugar solution, it will be found to be flaccid and limp. ‘The blade, or lamina, of the leaf droops as if wilted, though it is still wet. The bean seedling also is flaccid, the succulent stem bending nearly double as the lower part of the stem is held upright. This loss of turgidity is brought about by the loss of water from the tissues, and judging from the experiments on spirogyra and the beet, we con- clude that the loss of turgidity is caused by the withdrawal of some of the water from the cell-sap by the strong salt solution. 38. Now if we wash carefully these leaves and seedlings, which have been in the salt and sugar solutions, with water, and then immerse them in fresh water for a few hours, they will regain their turgidity. Here again we are led to infer that the diffusion current is now inward through the protoplasmic membranes of all the living cells of the leaf, and that the resulting turgidity of the individual cells causes the turgidity of the leaf or stem. ABSORPTION, DIFFUSION, OSMOSE. IQ 39. Absorption by root hairs.—If we examine seedlings, which have been grown in a germinator or in the folds of paper or cloths so that the roots will be free from particles of soil, we will see near the growing point of the roots that the surface is covered with numerous slender, delicate, thread- \, \ like bodies, the root hairs. Let us place a portion Nn of a small root containing some of these root a hairs in water on a glass slip, and prepare it for | examination with the microscope. We will see 7 that each thread, or root hair, is a continuous | tube, or in other words it is a single cell which has become very much elongated. The proto- plasmic membrane lines the wall, and strands of protoplasm extend across at irregular intervals, the interspaces being occupied by the cell-sap. We should now draw under the cover glass some of the five per cent salt solution. ‘The protoplasmic membrane moves away from the cell f i wall at certain points, showing that plasmolysis is i \ taking place, that is, the diffusion current is out- é, ward so that the cell-sap loses some of its water, f. { and the pressure from the outside moves the Af membrane inward. We should not allow the salt ‘ solution to work on the root hairslong. It should ad be very soon removed by drawing in fresh water e before the protoplasmic membrane has_ been % ? broken at intervals, as is a apt to be the case by the 25 iki, strong diffusion current dW ips, See 5 and the consequent mt yi Wag an co strong pressure from nee. Seer ae without. —The membrane Seedling of mache showing root ean on gg 5% of protoplasm now moves outward as the diffusion current is inward, and soon regains its former position next the inner side of the cell wall. The root hairs then, like other parts of the plant which we have _ 20 PHY STOLOG Y. investigated, have the Lower of taking up water under press- ure. 40. Cell-sap a solution of certain substances.—From these experiments we are led to believe that certain substances reside in the cell-sap of plants, which behave very much like the salt solution when separated from water by the protoplasmic membrane, Let us attempt to interpret these phenomena by recourse to diffusion experiments, where an animal membrane separates two liquids of difterent concentration. 41. Diffusion through an animal membrane.—For this experiment we may use a thistle tube, across the larger end of which should be stretched and tied tightly a piece of a bladder membrane, A strong sugar solution (three parts sugar to one part water) is now placed in the tube so that the bulb is filled and the liquid extends part way in the neck of the tube. This is im- mersed in water within a wide-mouth bottle, the neck of the tube being sup- ported 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 mem- brane in the direction of the sugar solution, so that this gains more water than it loses. 42. 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 diffuses through the animal membrane with diffi- culty. The sugar solution is also what is called a concentrated solution, i.e., it is more highly concentrated than water. ‘The water, therefore, according to a general law 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 membrane, since the diffusion currents travel through it. 43. In this experiment then the bulk of the sugar solution is increased, and the 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, and the membrane, since it permits one liquid to pass in one direc- tion more rapidly than in the other, is sometimes called a semipermeable membrane. | 44. 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 protoplasmic membrane is the diffusion membrane, or semiperme- able membrane, through which the diffusion takes place. ‘The salt solution which is first used to bathe the threads of the plant is a more highly concen- trated solution than that of the cell-sap ‘within the cell, Water therefore is ABSORPTION, DIFFUSION, OSMOSE. 21 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 protopiasmic membrane away from the wall. Now when we remove the salt solution and bathe the thread with water again, the cell-sap, being a more highly concentrated solution than water, diffuses with more difficulty 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 and sugar solutions on the leaves of geranium, on the leaves and stems of the seedlings, on the tissues and cells of the beet and carrot, and on the root hairs of the seedlings, 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 ; not only in giving the plant the power to take up solutions of nutriment from the soil, but they serve also other pur- poses, as we shall see later. CHAPTER Itt. ABSORPTION OF LIQUID NUTRIMENT. 45. We are now ready to inquire how plants obtain food from the soil or water. Chemical analysis shows that certain mineral substances 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 constitu- ents of plant food. While the proportion of the mineral ele- ments which enter into the composition of plant food may vary considerably within certain limits, the concentration of the solu- tions should not exceed certain limits. A very useful solution is one recommended by Sachs, and is as follows : 46. Formula for solution of nutrient materials: ist a re nee ae Me Meters yer I00O cc. Potassy mitratei so ssi dks kaane one ee 0.5 gr SN CHOICE 2. a5 am o's kame so i ere 0.5 * Calcium sulobate..... . 7.5 heii hanes ne 2 ee O45 Miapnesiim GUIpMAte « «ox: cs state vic sso ee Ong ** GCalcitiin phosomnte,. «<6 nibs dite op ae eaneen O53 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 algze, 47. Several different plants are useful for experiments in water cultures, as peas, corn, beans, buckwheat, etc. ‘The seeds of these plants may be germi- nated, 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. The seeds should not be kept immersed in water after they have imbibed enough to thoroughly soak and swell them, At the same time that the seeds are placed in damp paper or cloth for germination, one lot of the soaked seeds 22 oe ~~ ABSORPTION NUTRIMENT. 23 should be planted in good soil and kept under the same temperature condi- tions, 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. I, soil. No. 2, distilled water. No. 3, nutrient solution. No, 4, nutrient solution with a few drops of iron solution added. 48. 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 will 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 insert- ing 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 set- ting 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 dupli- cate series should be set up to guard against the error which might arise from variation in indi- vidual plants and from accident. Where there are several students in a class, a single series set up by several will act as checks upon one another. If glass jars are used for the liquid cultures they should be wrapped with black Culture cylinder to show position of : corn seedling ( Hansen). paper or cloth to exclude the light from the liquid, otherwise numerous minute algze are apt to grow and interfere with the experiment. Or the jars may be sunk in pots of earth to serve the same purpose. Ifcrockery jars are used they will not need covering. 49. For some time all the plants grow equally well, until the nutriment stored in the seed is exhausted. The numbers I, 3 and 4, in soil and nutri- ent solutions, should outstrip number 2, the plants in the distilled water. No. 4 in the nutrient solution with iron, having a perfect food, compares favor- ably with the plants in the soil. ee SEE ED OO ET Eh Cae 24 PHYSIOLOGY. 50. Plants take liquid food from the soil.—From these ex- periments 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. If we recur now to the experiments which were performed with the salt solution in producing plasmolysis in the cells of spirogyra, in the cells of the beet or corn, and in the root hairs of the corn and bean seedlings, and the way in which these cells become tur- gid again when the salt solution is removed and they are again bathed with water, we will have an explanation of the way in which plants take up nutrient solutions of food material through their roots. 51. How food solutions are carried into the plant.—We can J 0a; é hah TW) e Dey bt egneut® fpscaneiguies Fig. 29. Section of corn root, showing rhizoids formed from elongated epidermal cells. 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 ABSORPTION NUTRIMENT. 25 solutions are carried farther 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 heresee 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. 29. ‘The end of the hair next the root fits in between the adjacent superfi- cial cells of the root and joins closely to the next deeper 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 the inside of each cell wall. aa 52. 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 lat- ter. 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 in- side and close to the base of 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 the _ same. ‘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 sub- ) _ stances in solution in the cell-sap of the different cells, the food solutions are 7 carried along until they reach the vascular bundles, through which the solu- _ tions are carried to distant parts of the plant. Some believe that there is a __ rhythmic action of the elastic cell walls in these cells between the root hairs and the vascular bundles. This occurs in such a way that, after the cell becomes turgid, it contracts, thus reducing the size of the cell and forcing some of the food solutions into the adjacent cells, when by absorption of more food solu- _ tions, or water, the cell increases in turgidity again. This rhythmic action of Es the cells, if it does take place, would act as a pump to force the solutions _ along, and would form one of the causes of root pressure. a 53. How the root hairs get the watery solutions from the soil.—If we _ examine the root hairs of a number of seedlings which are growing in the soil _ under normal conditions, we shall see 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 | | | } ee a a a a ~~ SSS Pe om i — <== = 26 PH YVSIOLOG ¥. to know how plants can obtain water from soil which is not wet. If we at- tempt to wash off the soil from the roots, being careful not to break away the ~ ry Fig. 30. / Root hairs of corn seedling with soil particles adhering closely. 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. 54, If now we take some of the soil which is only moist, weigh it, and then permit it to become quite dry on exposure to dry air, and weigh again, we will find that it loses weight in drying. Moisture has been given off. This moisture, it has been found, forms an exceedingly thin film on the sur- face of the minute soil particles. Where these soil particles lie closely to- gether, as they usually do when massed together in the pot or elsewhere, this thin film of moisture is continuous from the surface of one particle to that of an- other. Thus the soil particles which are so closely attached to the root hairs connect the surface of the root hairs with this film of moisture. As the cell- sap of the root hairs draws on the moisture film with which they are in con- tact, the tension of this film is sufficient to draw moisture from distant parti- cles. Jn this way the roots are supplied with water in soil which is only moist. 55. Plants cannot remove all the moisture from the soil.—If we now take a potted plant, or a pot containing a number of seedlings, place it in a moder- ately dry room, and do not add water to the soil it will be found in a few days that the plant is wilting. ‘The soil if examined will appear quite dry to the sense of touch, Let us weigh somewof this soil, then dry it by artificial ABSORPTION NUTRIMENT. 27 heat, and weigh again. It has lost in weight. This has been brought about by driving off the moisture which still remained in the soil after the plant began to wilt. This teaches that while plants can obtain water from soil which is only moist or which is even rather dry, they are not able to withdraw all the moisture from the soil. 56. Acidity of root hairs.—If we take a seedling which has been grown in a germinator, or in the folds of cloths or paper, so that the roots are free from the soil, and touch the moist root hairs to blue litmus paper, the paper becomes red in color where the root hairs have come in contact. ‘This is the reaction for the presence of an acid substance, and indicates that the root hairs excrete certain acids. ‘This acid property of the root hairs serves a very important function in the preparation of certain of the elements of plant food in the soil. Certain of the chemical compounds of potash, phosphoric acid, etc., become 7 deposited on the soil particles, and are not soluble in water. The acid of the root hairs dissolves some of these compounds where the particles of soil are in close contact with them, and the solutions can then be taken up by the roots. 57. This corrosive action of the roots can be shown by the well-known experiment of growing a plant on a marble plate which is covered by soil. After a few weeks, if the soil be washed from the marble where the roots have been in close contact, there will be an outline of this part of the root system. Several! different acid substances are excreted from the roots of plants _ which have been found to redden blue litmus paper by contact. Experiments by Czapek, however, show that it is carbonic acid which has the power of dissolving these compounds, while the other acids excreted by the roots do not have this power. CHAPTER LIN. TURGESCENCE. 58. Turgidity of plant parts.—As we have seen by the experiments on the leaves, turgescence of the cells is one of the conditions which enables the leaves to stand out from the stem, and the lamina of the leaves to remain in an expanded position, so that they are better exposed to the light, and to the currents of air. Were it not for this turgidity the leaves would hang down close against the stem. 59. Restoration of turgidity in shoots.—If we cut off a living stem of geranium, coleus, tomato, or ‘‘ balsam,’’ and allow the leaves to partly wilt so that the shoot loses its turgidity, it is possible for this shoot to regain turgidity. ‘The end may be freshly cut again, placed ina vessel of water, covered with a bell jar and kept ina room where the temperature is suitable for the growth of the plant. The shoot will usually become turgid again from the water which is absorbed through the cut end of the stem and is carried into the leaves where the individual cells become turgid, and the leaves areagain expanded. Such shoots, and the excised leaves also, may often be made turgid again by simply immersing them in water, as one of the experiments with the salt solution would teach. Fig. 31. Restoration of turg dity 60. ‘Turgidity may be restored more certainly and (Sachs). ; = quickly in a partially wilted shoot in another way. The cut end of the shoot may be inserted in a U tube as shown in fig. 31, the end of the tube around the stem of the plant being made air-tight. The arm 28 TURGESCENCE. 29 of the tube in which the stem is inserted is filled with water and the water is allowed to partly fill the other arm. Into this other arm is then poured mercury. ‘The greater weight of the mercury causes such pressure upon the water that it is pushed into the stem, where it passes up through the vessels in the stems and leaves, and is brought more quickly and surely to the cells which contain the protoplasm and cell-sap, so that turgidity is more quickly and certainly attained. 61. Tissue tensions.—Besides the turgescence of the cells of the leaves and shoots there are certain tissue tensions without which certain tender and succulent shoots, etc., would be limp, and would droop. ‘There are a number of plants usually accessi- ble, some at one season and some at others, which may be used to illustrate tissue tension. 62. Longitudinal tissue tension. —For this in early summer one may use the young and succulent shoots of the elder (sambucus); or the petioles of rhubarb during the summer and early autumn; or the petioles of richardia. _Petioles of cala- dium are 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 demonstrate 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 supports the heavy expanded lamina of the leaf. 63. The ends of a portion of such a petiole or other object which may be used are cut off squarely. With a knife a strip from 2—3mm in thickness is removed from one side the full length of the object. This strip will now be found to be shorter than the larger part from which it was removed. ‘The outer tissue then exerts a tension upon the petiole which tends to shorten it. Let us remove another strip lying next this one, and another, and so on until the outer tissues remain only upon one side. ‘The object will now bend toward that side. Now remove this strip and compare the length of the strips removed with the central portion. They will be found to be much wt | 30 PHYSIOLOGY. shorter now. In other words there is also a tension in the tissue of the central portion of the petiole, the direction of which is opposite to that of the superficial tissue. The parts of the petiole now are not rigid, and they easily bend. ‘These two longitudi- nal tissue tensions acting in opposition to each other therefore give rigidity to the succulent shoot. It is only when the indi- vidual cells of such shoots or petioles are turgid that these tissue tensions in succulent shoots manifest themselves or are promi- nent. 64. 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 horizontal position by one end. It is flabby and droops downward because the longitudinal tension is removed. 65. Transverse tissue tension.—'T’o illustrate this one may take a willow shoot 3-5cm in diameter and saw off sections about 2cm long. Cut through the bark on one side and peel it off in a single strip. Nowattempt to replace it. The bark will not quite cover the wood again, since the ends will not meet. It must then have been held in transverse tension by the woody part of the shoot. CHAPTER V. BOOT PF REOOURE, 66. 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 fora number of days, and in some cases the amount of liquid, called ‘‘sap,’’ which escapes is con- siderable. 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 rvoo/ pressure is used to denote the force exerted in supplying the water from the soil. 67. 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 ro meters (36.5 ft.) high, and the birch (Betula lutea) (Clark, 1873) hasa root pressure sufficient to hold a column of water about 25 meters (84.7 ft.) high. 68. Experiment to demonstrate root pressure.—By a very simple method this power of root pressure may be demonstrated. During the summer season plants in the open may be used if it is preferred, but plants grown in pots are also very serviceable, and one may 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. ‘The stem is cut off rather close to the soil and a long glass tube is attached to the cut end of the stem, still con- nected with the roots, by tne use of rubber tubing as shown in figure 32, anda 31 a2 .3 PHYSIOLOGY. very small quantity of water may be poured in to moisten the cut end of the stem, In a few minutes the water begins to rise in the glass tube. In some cases it rises quite rapidly, so that the column of water can readily be seen to extend higher and higher up in the tube when observed at quite short intervals. The height of this column of water is a measure of the force exerted by the roots. The pressure force of the roots may be measured also by deter- mining the height to which it will raise a column of mercury. 69. In either case where the experiment is con- tinued for several days it is noticed that the column of water or of mercury rises and falls at different times during the same day, that is, the column stands at varying heights; or in other words the root pressure varies during the day. With some plants it has been found that the pressure is greatest at = certain times of the day, or at certain seasons of the year. Such variation of root pressure exhibits what Ec peb engendiae termed a periodicity, and in the case of some ure (Detmer). plants there is a daily periodicity; while in others there is in addition an annual periodicity. With the grape vine the root pressure is greatest in the forenoon, and decreases from 12-6 p.M., while with the sunflower it is greatest before io A.M., when it begins to decrease. ‘Temperature of the soil is one of the most important external conditions affecting the activity of root pressure. CHAPTER: Vi: TRANSPIRATION. 70. We should now inquire if all the water which is taken up in excess of that which actually suffices for turgidity is used in the elaboration of new materials of construction. We notice whena leaf or shoot is cut away from a plant, unless it is kept in quite amoist condition, or in a damp, cool place, that it becomes flac- cid, 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 in the form 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? 71. Loss of water from excised leaves.—Let us take a hand- ful 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 no water. Now we will place this in a brightly lighted window, or in sunlight. In the course of fifteen to thirty minutes we notice that a thin film of moisture is accumulating 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. We should 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 con- densed 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 water on the surfaces of the leaves, or at the cut ends, before it may have condensed there, 33 = 34 PHYSIOLOGY. we infer that the water escapes from the leaves in the form of waler vapor, and that this water vapor, when it comes in contact with the surface of the cold glass, condenses and forms the mois- ture film, and later the drops of water. ‘The leaves of these cut shoots therefore lose water in the form of water vapor, and thus a loss of turgidity results. 72. Loss of water from growing plants.—Suppose we now take a small and actively growing plant in a pot, and cover the pot and the soil with a sheet of rubber cloth which fits tightly around the stem of the plant (or the pot and soil may be enclosed in a hermetically sealed vessel) so that the moisture from the soil cannot escape. ‘Then place a bell jar over the plant, and set in a brightly lighted place, at a temperature suitable for growth. In the course of a few minutes on a dry day a moisture film forms on the inner surface of the glass, just as it did in the case of the glass jar containing the cut shoots and leaves. Later the mois- ture has condensed so that it is in the form of drops. If we have the same leaf surface here as we had with the cut shoots, we will probably find that a larger amount of water accumulates on the surface of the jar from the plant that is still attached to its roots. 73. Water escapes from the surfaces of living leaves in the form of water vapor.—This living plant then has lost water, which also escapes in the form of water vapor. Since here there 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 pressure sup- ply 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. 74. Experiment to compare loss of water in a dry and a humid atmosphere.—We should now compare the escape of water from the leaves of a plant covered by a bell jar, as in the last experiment, with that which“takes place when the plant is vem TRANSPIRATION. 35 exposed in a normal way in the air of the room or in the open. To do this we should select two plants of the same kind growing in pots, and of approximately the same leafsurface. ‘The potted plants are placed one each on the arms ofa scale. One of the plants is covered in this position with a bell jar. With weights placed on the pan of the other arm the two sides are balanced. In the course of an hour, if the air of the room is dry, moisture has probably accumulated on the inner surface of the glass jar which is used to cover one of the plants. ‘This indicates that there has here been a loss of water. But there is no escape of water vapor into the surrounding air so that the weight on this arm is practically the same as at the beginning of the experiment. We see, however, that the other arm of the balance has risen. We infer that this is the result of the loss of water vapor from the plant onthatarm. Now let us remove the bell jar from the other plant, and with a cloth wipe off all the moisture from the inner surface, and replace the jar over the plant. We note that the end of the scale which holds this plant is still lower than the other end. 75. The loss of water is greater in a dry thanin a humid atmosphere.—This teaches us that while water vapor escaped from the plant under the bell jar, the air in this receiver soon became saturated with the moisture, and thus the farther escape of moisture from the leaves was checked. It also teaches us an- other very important fact, viz., that plants lose water more rapidly through their leaves in a dry air than in a humid or moist atmos- phere. We can now understand why it is that during the very hot and dry part of certain days plants often wilt, while at night- fall, when the atmosphere is more humid, they revive. They lose more water through their leaves during the dry part of the day, other things being equal, than at other times. 76. How transpiration takes place.—Since the water of transpiration passes off in the form of water vapor we are led to inquire if this process is simply evaporation of water through the surface of the leaves, or whether it is controlled to any appreci- able extent by any condition of the living plant. Anexperiment 36 PHYSIOLOG Y. which is instructive in this respect we will find in a comparison between the transpiration of water from the leaves of a cut shoot, allowed to lie unprotected in a dry room, and a similar cut shoot the leaves of which have been killed. 77. Almost any plant will answer for the experiment. For this purpose I have used the following method. Small branches of the locust (Robinia pseudacacia), of sweet clover (Melilotus alba), and of a heliopsis were selected. One set of the shoots was immersed for a moment in hot water near the boiling point to kill them. The other set was immersed for the same length of time in cold water, so that the surfaces of the leaves might be well wetted, and thus the two sets of leaves at the beginning of the experiment would be similar, so far as the amount of water on their surfaces is con- cerned. All the shoots were then spread out on a table in a dry room, the leaves of the killed shoots being separated where they are inclined to cling together. Ina short while all the water has evaporated from the surface of the living leaves, while the leaves of the dead shoots are still wet on the sur- face. In six hours the leaves of the dead shoots from which the surface water had now evaporated were beginning to dry up, while the leaves of the living plants were only becoming flaccid. In twenty-four hours the leaves of the dead shoots were crisp and brittle, while those of the living shoots were only wilted. In twenty-four hours more the leaves of the sweet clover and of the heliopsis were still soft and flexible, showing that they still contained more water than the killed shoots which had been crisp for more than a day. 78. It must be then that during what is termed transpiration the living plant is capable of holding back the water to some extent, which in a dead plant would escape more rapidly by evaporation. It is also known that a body of water with a surface equal to that of a given leaf surface of a plant loses more water by evaporation during the same length of time than the plant loses by transpiration. 79. 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 leaves will answer equally well. From a portion of the leaf we should make very thin cross sections with a razor or other sharp instrument. These sections should be perpendicular to the surface of the leaf TRANSPIRATION. 37 and should be then mounted in water for microscopic examina- tion.* 80. 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 par- allel sides, and the cross walls are per- pendicular. ‘These cells form a single layer over both surfaces of the leaf and are termed the epidermis. ‘Their walls are quite stout and the outer walls are culicularized. | 81. Soft tissue of the leaf.—The cells which contain the green chloro- phyll bodies are arranged in two dif- .o. se ee ear eae ferent ways. ‘Those on the upper side semmunication between stomateand of the leaf are usually long and pris- !eaf; stoma closed. matic in form and lie closely parallel to each other. Because of this arrangement of these cells they are termed the palisade cells, and form what 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 Fig. 34. Fig. 35. Stoma open. Stoma closed. elongated, or oval, Or Figs. 34, 35.—Section through stomata of ivy leaf. 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 largespaces between them, the intercellular spaces. If we should examine such a section of a leaf before it is mounted in water we would see that the inter- * Demonstrations may be made with prepared sections of leaves, 38 PHYSIOLOGY. cellular spaces are not filled with water or cell-sap, but are filled with air or some gas. Within the cells, on the other hand, we find the cell-sap and the protoplasm. 82. 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. 33-35. This opening kh through the IEF epidermal layer is a stoma. ‘The cells which immediately surround the we openings are the guard Fig. 36. Portion of epidermis of ivy, showing irregular epidermal cells, stoma cells. ihe and guard cells. 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. 83. 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 reference 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 haye 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 mem- brane 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 + i bg 7 4 . " : TRANSPIRATION. 39 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. By an examination of our leaf section we see that the intercellular 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. 84. Action of the stomata.—Besides permitting the escape of the water vapor when the stomata are open they serve a very important office in regu- lating 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 transpiration is checked. 85. Transpiration may be in excess of root pressure.—If the supply of water from the roots was always equal to that transpired from the leaves during hot, dry days the leaves would not become flaccid and droop. But during the hot and dry part of the day it often happens that the trans- piration is in excess of the amount of water supplied the plant by root pressure. 86. Negative pressure.—This is not only indicated by the drooping of the leaves, but may be determined in another way. If the shoot of such a plant be cut underneath mercury, or underneath a strong solution of eosin, it will be found that some of the mercury or eosin, as the case may be, will be forcibly drawn up into the stem toward the roots. This is seen on quickly splitting the cut end of the stem. When plants in the open cannot be obtained in this condition, one may take a plant like a balsam plant from the greenhouse, or some other potted plant, knock it out of the pot, free the roots from the soil and allow to partly wilt. The stem may then be held under the eosin solution and cut. 87. Lifting power of transpiration.—Not only does transpiration go on quite independently of root pressure, as we have discovered from other experiments, but transpiration is capable of exerting a lifting power on the water in the plant. This may be demonstrated in the following way: Place the cut end of a leafy shoot in one end of a U tube and fit it water-tight. Partly * Fig. 37: m fill this arm of the U tube with water, and add mercury lifting ae he pase to the other arm until it stands ata level in the two Pte" arms as in fig. 37. In a short time we note that the mercury is rising in the tube, : | 40 PHYSIOLOGY. 88. Root pressure may exceed transpiration.—If we cover small actively growing plants, such as the pea, corn, wheat, bean, etc., with a bell jar, and place in the sunlight where the temperature is suitable for growth, in a few hours, if conditions are favorable, we will see that there are drops of water Tero ined oceans anes La aaa a Fig. 38. Estimation of the amount of transpiration. The tubes are filled with water, and as the water transpires from the leaf surface its movement in the tube from a to 6 can be measured. (After Mangin.) standing out on the margins of the leaves. These drops of water have exuded through the ordinary stomata, or in other cases what are called water stomata, through the influence of root pressure. The plant being covered by the glass jar, the air soon becomes saturated with mois- ture and transpiration is checked. Root pressure still goes on, how- ever, and the result is shown in the exuding drops. Root pressure is here in excess of transpiration. This phenomenon is often to be observed during the summer season in the case of low-growing plants. During the bright warm day transpiration equals, or may be in excess of, root pressure, and the leaves are consequently flaccid. As nightfall comes on the air becomes more he moist, and the conditions {* of light are such also that transpiration is lessened. Root pressure, however, is still active because the soil isstillwarm. In these cases drops of water may be seen exuding from the margins of the leaves due to the excess ' of root pressure over trans- piration. Were it not for this provision for the escape of the excess of water raised by root pressure, serious in- jury by lesions, as a result of the great pressure, might result. The plant is thus to some extent a self-regulatory piece of apparatus so far as tion are concerned. 89. Injuries caused by excessive root Fig. 39. root pressure and transpira- Guttation of tomato plants after connecting the stems by means of rubber tubes with the hydrant. pressure.—Some varieties of to- matoes when grown in poorly lighted and poorly ventilated greenhouses suffer we TRANSPIRATION. 41 serious injury through lesions of the tissues. This is brought about by the cells at certain parts becoming charged so full with water through the activity of root pressure and lessened transpiration, assisted also probably by an ac- ~ cumulation of certain acids in the cell-sap which cannot be got rid of by transpiration. Under these conditions some of the cells here swell out 4 forming extensive cushions, and the cell walls become so weakened that they burst. It is possible to imitate the excess of root pressure in the case of some plants by connecting the stems with a-system of water pressure, when very | quickly the drops of water will begin to exude from the margins of the leaves. 90. It should be stated that in reality there is no difference between trans- | ‘7 piration and evaporation, if we bear in mind that evaporation takes place more slowly from living plants than from dead ones, or from an equal surface of water. : 91. The escape of water vapor is not the only function of the stomata. The exchange of gases takes place through them as we shall later see. A large number of experiments show that normally the stomata are open when the leaves are turgid. But when plants lose excessive quantities of water on dry and hot days, so that the leaves become flaccid, the guard cells automat- ically close the stomata to check the escape of water vapor. Some water escapes through the epidermis of many plants, though the cuticularized mem- _ brane of the epidermis largely prevents evaporation. In arid regions plants are usually provided with an epidermis of several layers of cells to more - securely prevent evaporation there. In such cases the guard cells are often protected by being sunk deeply in the epidermal layer. _ 92. Demonstration of stomates and intercelluiar air spaces. _ demonstration of the presence of stomates in leaves, as well as the presence and intercommunication of the intercellular spaces, can be made by blowing - into the cut end of the petiole of the leaf of a calla lily, the lamina being immersed in water. The air is forced out through the stomata and rises as _ bubbles to the surface of the water. At the close of the experiment some of the air bubbles will still be in contact with the leaf surface at the opening of the stomata. The pressure of the water gradually forces this back into the leaf. x Other plants will answer for the experiment, but some are more suitable than @ others. A good CHAPTER VIL. PATH OF MOVEMENT OF LIQUIDS IN PLANTS. 93. In our study of root pressure and transpiration we have seen that large quantities 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. 94. Place the cut ends of leafy shoots in a solution of some of the red dyes.—We may cut off leafy shoots of various plants and insert the cut ends in a vessel of water to which have 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 con- servatories. Almost any plant will do, however, but we should also select one like the corn plant (zea mays) if in the summer, or the petioles of a plant like caladium, which can be obtained from the conservatory. If seedlings of the castor-oil bean are at hand we may cut off some shoots which are 8-1o inches high, and place them in the solution also. 95. 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 may be seen a red coloration of the 42 PATH OF MOVEMENT. 43 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 will note that there are several points in the section where the tissues are colored red. In the impatiens 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 com- pletely 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. 96. If we cut across the stem of a corn plant which has been in the solution, we see that instead of the colored areas being in a concentric ring they are irregularly scattered, and on splitting Fig. 40. Broken corn stalk, showing fibro-vascular bundles. the stem we see here also that these colored areas extend for long distances through the stem. If we take a corn stem which is mature, or an old and dead one, cut around through the outer hard tissues, and then break the stem at this point, from the softer tissue long strings of tissue will pull out as shown in fig. 40. These strings of denser tissue correspond to the areas which are colored by the dye. They are in the form of minute bundles, and are called vascular bundles. 44 PHA FSLTOLOG ¥; 97. 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. 98. Structure of the fibro-vascular bundles.—We should now make quite thin cross sections, either free hand and mount in water for microscopic examination, or they may be made with a microtome and mounted in Canada balsam, and in this condition will answer for future study. To illustrate the structure of the bundle in one type we may take the stem of the castor-oil bean., On examining 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 by hig. 41. Xylem portion of bundle. Cambium portion of bundle. sast portion of bundle, Section of vascular bundle of sunflower stem. cut across. These groups are somewhat oval in outline, with the pointed end directed toward the center of the stem. If we look at the section as a whole we will see that there is a narrow continuous ring * of small cells * 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 tissues called fundamental. PATH OF MOVEMENT. 45 situated at the same distance from the center of the stem as the middle part _of the bundles, and that it divides the bundles into two groups of cells. 99. Woody portion of the bundle.—In that portion of the bundle on the 99 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 xyZem. 100. 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¢ por- tion, or the Ai/oem. Intermingled with these, cells may often be found which have thin walls, unless the bundle is very old. Nearer the center of the bundle and still within the bast portion are cells with thin walls, angular and i 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. 101. Cambium region of the bundle.—Extending across the center 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 camdéium. Its cells grow and divide, and thus increase 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. 102. 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. 42, 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 difierent 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 rs 46 PHYSIOLOGY. places than in others, and this thickening takes place so regularly in some instances as to form regular spiral thickenings. Others have the thickenings EA : 2 g Z : | F Bo Ba ( | Z a : ne oy } yl 1 \\ Fig. 42. 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. in the form of the rounds of a ladder, while still others have pitted walls or the thickenings are in the form of rings. 103. 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. If we search for the place where two of these large cells with spiral, or ladder-like, markings meet end to end, we will 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 cells form tubes or vessels through which the water rises in the stems of plants. 104. In the bast portion of the bundle we detect the cells of the bast fibers by their thick walls. They are very much elongated and the ends taper out to thin points so that they overlap. In this way they serve to strengthen tue stem. 105. Sieve tubes. are elongated cells standing end to end, with delicate markings on their cross Lying near the bast cells, usually toward the cambium, walls which appear like finely punctured p!ates 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. 42.) The granular appearance which these plates pre- sent 1s caused by minute perforations through the wall so that there is a com- munication between the cells. The tubes thus formed are therefore called sieve tubes and they extend for long distances through the tube so that there PATH OF MOVEMENT. 47 is communication throughout the entire length of the stem. (The function of the sieve tubes is supposed to be that for the downward transportation of sub- stances elaborated in the leaves.) 106. If we section in like manner the stem of the sunflower we shall see simi- lar bundles, but the number is greater than eight. In the garden balsam the number is from four to six in an ordinary stem 3—4/z diameter. Here we can see quite well the origin of the vascular bundle. Between the larger bundles we can see especially in free-hand sections of stems through which a colored solution has been lifted by transpiration, as in our former experi- ments, small groups of the minute cells in the cambial ring which are colored. These groups of cells which form strands running through the stem are fvo- cambium strands. Thecells divide and increase just like the cambium cells, and the older ones thrown off on either side change, those toward the center of the stem to wood vessels and fibers, and those on the outer side to bast cells and sieve tubes. 107. Fibrovascular bundles in the Indian corn.—We should now make a thin transection of a portion of the center of the stem of Indian corn, in order to compare the structure of the bundle with that of the plants which we have just examined. In fig. 43 is repre- sented a fibrovascular bundle of the stem of the Indian corn. The large cells are those of the spiral and reticulated and annular vessels. This is the woody por- tion of the bundle or xylem, Opposite this is the bast portion or phloem, marked by the lighter colored tissue at z. The larger of these cells are the sieve tubes, and intermingled with them are smaller cells with thin wails. Surrounding the entire bundle are small cells with thick walls. These are elongated and the taper- ing ends overlap. They are thus slender Transection of fibrovascular bundle of and long and form fibers. In such a Indian corn. a, toward periphery, of stem; yg, large pitted vessels; s, spiral bundle all of the cambium has passed vessel; 7, annular vessel; ¢@, air cavity formed by breaking apart of the cells; 2, over into permanent tissue and is said to soft bast, a form of sieve tissue ; 4, thin- be closed walled parenchyma. (Sachs.) 108. Rise of water in the vessels.—During the movement of the water or nutrient solutions upward in the stem the vessels of the wood portion of the bundle in certain plants are nearly or quite filled, if root pressure is active and transpiration is not very rapid. If, however, on dry days transpiration is in excess of root pressure, as often happens, the vessels are not filled with the water, but are partly filled with certain gases because the air or other 48 PH VSIOLOG ¥. gases in the plant become rarefied as a result of the excessive loss of water. There are then successive rows of air or gas bubbles in the vessels separated by films of water which also line the walls of the vessels. The condition of the vessel is much like that of a glass tube through which one might pass the ‘¢froth ’’ which is formed on the surface of soapy water. This forms a chain of bubbles in the vessels. This chain has been called Jamin’s chain because of the discoverer. 109 Why water or food solutions can be raised by the plant to the height. attained by some trees has never been satisfactorily explained. There are several theories propounded which cannot be discussed here. It is probably a very complex process. Root pressure and transpiration both play a part, or at least can be shown, as we have seen, to be capable of lifting water toa considerable height. In addition to this, the walls of the vessels absorb water by diffusion, and in the small vessels capillarity comes also into play, as well as osmosis. 110. Synopsis of tissues. -Epidermis. ( Simple hairs. Many-celled hairs. Epidermal Trichomes j Branched hairs, often stellate. system. 4 (hairs) Clustered, tufted hairs. Glandular hairs. ie “Root bairs: Guard cells of stomates. Spiral vessels. Pitted vessels. 2 Scalariform vessels. Xylem Annular vessels. Wood fibers. Wood parenchyma. Fibrovascular system. Cambium (fascicular). | Sieve tubes. Phloem. / Bast fibers. Bast parenchyma. Cork. Parenchyma. (round tissue. ; Interfascicular cambium. Fundamental Medullary rays. yor: Bundle sheath. | Schlerenchyma (thick-walled cells, in nuts. ete). Collen- chyma (thick-angled cells, under epidermis of succulent stems). the surface of the water. Where there CHAPTER VIII. DIFFUSION: OF GASES. 111. Gas given off by green plants in the sunlight.—Let us take some green alga, like spirogyra, which is in a fresh con- dition, and 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 with spirogyra with black cloth so that it will be in the dark, or at least in very weak light. 112. In a short time we note 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 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. Fie If we now examine the second vessel Oxygen gas given off by spirogyra. we see that there are no bubbles, or only a very few of them. We are led to believe then that sunlight has had something to do with the setting free of this gas from the plant. 113. We may now take another alga like vaucheria and per- form the experiment in the same way, or to save time the two may be set up at once. In fact if we take any of the green 49 mit — 50 PHYSIOLOGY. algze and treat them as described above gas will be given off ina similar manner. 114. We may now 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 weighted down by a glass rod or other suitable object. If we place the vessel of water containing these leafy stems in the bright sunlight, in a short time bub- bles of gas will pass off quite rapidly from the cut end of the stem. If in the same vessel we A m= place another stem, from which the leaves have been cut, the number of bubbles of gas BIg. 45: given off will be very few. This indicates that Bubbles of oxygen gas given off from elodea in : : : kee ar large part of the gas is furnished by the (Oels. ) leaves. — = ——SS — =r — ——— ——— 115. Another vessel fitted up in the same way should be placed in the dark or shaded by covering with a box or black cloth. It will be seen here, as in the case of spirogyra, that very few or no bubbles of gas will be set free. Sunlight here also is necessary for the rapid escape of the gas. 116. We may easily compare the rapidity with which light of varying intensity effects the setting free of this gas. After cutting the end of the stem let us plunge the cut surface several times in melted paraffine, or spread over the cut surface a coat of varnish. Then prick with a needle a small hole through the paraffine or varnish. Immerse the plant in water and place in sunlight as before. The gas now comes from the puncture through the coating of the cut end, and the number of bubbles given off during a given period can be ascertained by counting. If we duplicate this experi- ment by placing one plant in weak light or diffused sunlight, and another in the shade, we can easily compare the rapidity of the escape of the gas under the different conditions, which represent varying intensities of light. We see then that not only is sunlight necessary for the setting free of this gas, but that in diffused light or in the shade the activity of the plant in this respect is less than in direct sunlight. 117. What this gas is.—If we 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 exitot the funnel. DIFFUSION OF GASES. 51 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 hiled with water may in this condition be inverted over the opening of the funnel tube. With this arrange- ment of the experiment the gas will rise in the inverted test tube, slowly displace a portion of the water, and become collected in a sufficient quantity to afford usa test. When a consider- able quantity has accumulated in the test tube, we may close the end of the tube in the water with the thumb, lift it le the water and invert. oe - The gas will rise against the thumb. A dry sete eras OF soft pine splinter should be then lighted, and (Detmer.) 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 to the mouth of the tube as the thumb is quickly moved to one side. The glowing of the splinter shows that the gas is oxygen. 118. Oxygen given off by green land plants also.—If we should extend our experiments to land plants we would 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 il is necessary to set up rather complicated 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. 119. 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 considerable quantity of oxygen and carbon dioxide. 120. If we boil spring water or hydrant water which comes froma stream containing oxygen and carbon dioxide, for about 20 52 PHYSIOLOGY. minutes, these gases are driven off. We should set this aside where it will not be agitated, until it has cooled sufficiently to receive plants without injury. Let us 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. 121. Can it be that this is because the oxygen was driven from the water in boiling? Wewill see. Let us take the vessel containing the water, or some other boiled water, and agitate it so that the air will be thoroughly mixed with it. In this way oxygen is again mixed with the water. Now place the plant again in the water, set in the sunlight, and in several minutes observe the result. No oxygen is given off. There must be then some other requisite for the evolution of the oxygen. 122. The gases are interchanged in the plants.—We will now introduce carbon dioxide again in the water. This can be done by blowing into the water through a glass tube in such a manner as to violently agitate the water for some time, when the carbon dioxide from the ‘‘ breath’’ will become mixed with the water. Now if we place the plant in the water and set the vessel in the sunlight, in a few minutes the oxygen is given off rapidly. 123. A chemical change of the gas takes place within the plant cell.—This leads us to believe then that CO, is in some way necessary for the plant in this process. 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. 124. Gases as well as water can diffuse through the proto- plasmic membrane.—Carbon dioxide then is absorbed by the plant while oxygen is given off. We see therefore that gases as well as water can diffuse through the protoplasmic membrane of plants under certain conditions. , Note. at we kill the plant, for example, by placing it fora short time in ly boiling water, oxygen will not be given off when the plant 1s placed in sunlight i in water. In other words the plant must be alive. Farther, if we introduce CO, in the water by blowing into it and have not introduced oxygen, oxygen will not be evolved. Not only must the plant be alive, it must have access to oxygen, which we will see later is very essential to the CECA PARE in: xe RE ow | RATT O Ne 126. One of the life processes in plants which is extremely interesting, and which is exactly the same as one of the life pro- cesses of animals, is easily demonstrated in several ways. 127. Oxygen from the air consumed during germination of seeds.—Let us take a half pint or a pint of peas, tie them ina bag or loose cloth, soak them in warm water for ro or 12 hours, or in cool water for about €) 24 hours. Drain off the surplus water and lower ¥ the cloth with the peas in a tall glass cylinder which holds 1 to 2 liters. This should be covered with a glass plate after vaseline has been smeared on the edges of the cylinder to make the vessel air tight. Set aside in a warm room forabout 12 hours. Now lower a lighted taper or short candle into the vessel after having carefully removed the cover. ‘The flame is extinguished. ‘This indicates that there is no Test for presence of carbon dioxide in vessel gyygen in the vessel. with germinating peas. a" (Sachs. 128. Carbon dioxide given off during ger- mination.—Now let us lower asmall vessel containing lime water into it. Very soon, almost immediately, there is formed on the surface of the lime watera film. ‘The film formed under these conditions is known to be carbonate of lime, which is formed by the union of carbon dioxide in the vessel with the lime in the water. (Note. Where there are a number of students and large vessels are not at hand, bottles of a pint capacity and a smaller number of peas will answer. ) 54 q RESPIRATION. 55 129. If we now take some of the lime water and blow our ‘‘breath’’ upon it the same film will be formed. The carbon dioxide which we exhale unites with the lime in the water, and forms carbonate of lime, just as in the case of the peas. In the case of animals the process by which 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 used up in the proc- ess, and carbon dioxide was given off. (It will be seen that this process is exactly the opposite of that which takes place in carbon conversion. ) 130. Respiration is necessary for growth.—After we have performed this experiment, if the vessel has not been open too long so that oxygen has en- tered, we may use the vessel for another experiment, or set up a new one to be used in the course of 12 to 24 hours, after all the oxygen has been con- sumed. Place some folded damp filter paper on the germinating peas in the jar. Upon this place one-half dozen peas which have just been germinated, and in which the roots are about 20-25 mm long. The vessel should be cov- ered tightly again and set aside in a warm room. A second jar with water in the bottom instead of the germinating peas should be set up as a check. Damp folded filter paper should be sup- ported above the water, and on this should be placed one-half dozen peas with roots of the same length as those in the jar containing carbon dioxide. 131. In 24 hours examine and note how much Fig. 48. growth has taken place. It will be seen that the Pea seedlings; the one ; } : at the left had no oxygen roots have elongated but very little or none in the and little growth took first jar, while in the second one we see that the oe ca lees ie roots have elongated considerably, if the experi- evident. ment has been carried on carefully. Therefore in an atmosphere devoid of oxygen very little growth will take place, which shows that normal respiration with access uf oxygen is necessary for growth. 132. 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 respiration 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 that during respiration there is a slight elevation of the temperature in the plant tissues. The plant then 56 PHYVSICLOG Y. gains 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. 133. 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 a smali vessel containing lime water. rr “ps — - eae A NL IES Oo =. Ake, Pot: 7 ‘ ~ ~~ Ke aS Oo Se pay: bee bie O° bodies are for exami- 105 106 MORPHOLOGY. nation. If they are rounded, with slender hair-like appendages over the surface, which vibrate and cause motion, they very likely are one of the kinds of reproductive bodies of vaucheria. The hair-like appendages are citia, and they occur in pairs, several of them distributed over the surface. These rounded bodies are gonzdia, and .because they are motile they are called zoogonidia. By examining some of the threads in the vessel where they occurred we may have perhaps an opportunity to see how they are produced. Short branches are formed on the threads, and the contents are separated from those of the main thread by a septum. The protoplasm and other contents of this branch separate from the wall, round up into a mass, and escape through an opening which is formed in the end. Here they swim around in the water for a time, then come to rest, and germinate by growing out into a tube which forms another vaucheria plant. It will be observed that this kind of reproduction is not the result of the union of two different parts of the plant. It thus differs from that which is termed sexual reproduction. A small part of the plant simply becomes separated from it as a special body, and then grows into a new plant, a sort of multiplication. This kind of re- production has been termed asexual reproduction. 249. Sexual reproduction in vaucheria.— The organs which are concerned in sexual reproduction in vaucheria are very readily obtained for study if one collects the material at the right season. They are found quite readily during the spring and autumn, and may be preserved in formalin for study at any season, if the material cannot be collected fresh at the time it is desired for study. Fine material for study often occurs on the soil of pots in greenhouses during the winter. While the zoogonidia are more a apt to be found in material 3 Ge which is quite green and fresh- BF ly growing, the sexual organs te yt eras are usually more abundant seek Sisk a ey. when the threads appear some- La ORES EO what ye’owish, or yellow green. 250. Vaucheria sessi- Big; 207. | lis; the sessile vauche- Fe eee ad ook om tente of thread by a Yia.——In | Gigasene i ita sexual organs are -sessile, that is they are not borne ona stalk as in some other species. The sexual organs usually occur several ina group. Fig. 107 represents a portion of a fruiting plant. VAUCHERTIA. 107 251. Sexual organs of vaucheria. Antheridium.—The antheridia are short, slender, curved branches from a main thread. A septum is formed which separates an end portion from the stalk. This end cell is the anfheridium. Frequently it is collapsed or empty as shown in fig. 108. ‘The protoplasm in Fig 108. Vaucheria sessilis, one antheridium between two oogonia. the antheridium forms numerous small oval bodies each with two slender lashes, the cilia. When these are formed the antherid- ium opens at the end and they escape. It is after the escape of these spermatozoids that the antheridium is collapsed. Each spermatozoid is a male gamete. 252. Oogonium.—The oogonia are short branches also, but they become large and somewhat oval. a se septum which separates the protoplasm from that of the main thread is as we see near the junction of the branch with the main Fig. 109. thread. The oogonium, _Vaucheria sessilis; oogonium opening and emit- Siem inthe figure, is thes bi of protoplasm; spermatonosss sperms usually turned somewhat eee!) to one side. When mature the pointed end opens anda 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 surrounded by a thick brown wall, with starchy and oily contents. ‘This is the 108 MORPHOLOG Y. fertilized egg (sometimes called here the oospore). It is freed from the oogonium by the disintegration of the latter, sinks into Fig. 110. Fertilization in vaucheria. #7, male nucleus; _/, female nucleus. Male nucleus entering the egg and approaching the female nucleus. (After Oltmans.) the mud, and remains here until the following autumn or spring, when it grows directly into a new plant. 253. Fertilization.—Fertilization is accomplished by the spermatozoids swimming in at the open end of the oogonium, Fig. 111. Fertilization of vaucheria. £7, female nucleus; #27, male nucleus. The different figures show various stages in the fusion of the nuclei. when one of them makes its way down into the egg and fuses with the nucleus of the egg. 254. The twin vaucheria (V. geminata).—Another species of vaucheria is the twin vaucheria. This is also a common one, and may be used for study instead of the sessile vaucheria if the latter cannot be obtained. The sexual organs are borne at the end of a club-shaped branch. There are usually two oogonia, and one antheridium between them which terminates the branch. Ina closely related species, instead of the two oogonia there is a whorl of them with the antheridium in the center. 255. Vaucheria compared with spirogyra.—In vaucheria we have a plant which is very interesting to compare with spirogyra in several respects. VAUCHERTA. 10Q i i _ Growth takes place, not in all parts of the thread, but is localized at the ends of the thread and its branches. This represents a distinct advance on such a plant as spirogyra. Again, only specialized parts of the plant in vaucheria _ form the sexual organs. These are short branches. Farther there is a great te difference in the size of the two organs, and especially in the size of the gametes, the supplying gametes (spermatozoids) being very minute, while the receptive gamete is large and contains all the nutriment for the fertilized egg. In spirogyra, on the other hand, there is usually no differ- - ence in size of the gametes, as we have seen, and each contributes equally in _ the matter of nutriment for the fertilized egg. Vaucheria, therefore, rep- resents a distinct advance, not only in the vegetative condition of the plant, but in the specialization of the sexual organs. Vaucheria, with other related __algze, belongs to a group known as the S7phonee, so called because the plants are tube-like or s7phon-like. CHAPTER ACVILT. COLEOGH AL he. 256. Among the green alge coleochete is one of the most interesting. Several species are known in this country. One of these at least should be examined if it is possible to obtain it. It occurs in the water of fresh lakes and ponds, attached to aquatic plants. 3 257. The shield-shaped coleochete.—This plant (C. scutata) a ¥ CW va eh a y = SK KES Fig. 112. Stem of Cm) aquatic plant Cs showing co- leochete, natural size. Fig. 113. Thallus of Coleochzte scutata. is in the form of a flattened, circular, green plate, as shown in fig. 112. It is attached near the center on one side to rushes 110 COLEOCH ATE. III and other plants, and has been found quite abundantly for sev- eral years in the waters of Cayuga Lake at its southern extremity. As will be seen it consists of a single layer of green cells which radiate from the center in branched rows to the outside, the cells lying so close together as to forma continuous plate. The plant started its growth from a single cell at the central point, and grew at the margin in all directions. Sometimes they are quite irregu- lar in outline, when they lie quite closely side by side and inter- fere with one another by pressure. If the surface is examined carefully there will be found long hairs, the base of which is en- closed in a narrow sheath. It is from this character that the genus takes its name of coleochzte (sheathed hair). 258. Fruiting stage of coleochete.—It is possible at some seasons of the year to find rounded masses ot cells situated near the margin of this green disk. These have developed from a fertilized egg which remained attached to the plant, and prob- ably by this time the parent plant has lost its color. 259. Zoospore stage.—This mass of tissue does not develop directly into the circular green disk, but each of the cells forms a zoospore. Here then, as in cedogonium, we have an- other stage of the plant in- terpolated between the fer- e. wees) / tilized egg and that stage wae, of the plant which bears the i gametes. But in coleochete f we have a distinct advance in a ee thi hat is pres- ‘ Portion of thallus is stage upon what 1s pres Fig. 114. of Coleochete ent in cedogonium for in . Portion of thallus of Co- scutata, showing ? leochzte scutata, showing four _ antheridia coleochzete the fertilized empty .cells from which formed from one ) zoogonidia have escaped, thallus cell; a sin- : ] one from each cell; zoogo- _— gle spermatozoidat €88 dev elops first into a nidia at the left. (After the right. (After several-celled mass of tissue Prmssheim.) Pringsheim.) before the zoospores are formed, while in cedogonium only four zoospores are formed directly from the egg. 260. Asexual reproduction.—In asexual reproduction any of the green cells on the plant may form zoogonida. The contents of a cell round off and I12 MORPHOLOG Y. form a single zoogonidium which has two cilia at the smaller end of the oval body, fig. 114. After swimming around for a time they come to rest, ger- minate, and produce another plant. 261. Sexual reproduction.—Oogonium.—The oogonium is formed by the enlargement of a cell at the end of one of the threads, and then the end of the L oe » bs ae Z .% 2 “ ¢ ie pp Fig. 116. Coleochete soluta; at left branch bearing oogonium (00g); antheridia (az¢); egg in oogonium and surrounded by enveloping threads; at center three antheridia open, and one spermatozoid ; at right sporocarp, mature egg inside sporocarp wall. cell elongates into a slender tube which opens at the end to form a channel through which the spermatozoid may pass down to the egg. The egg is formed of the contents of the cell (fig. 116). Several oogonia are formed on one plant, and in such a plant as C. scutata they are formed in a ring near the margin of the disk. 262. Antheridia.—In C. scutata certain of the cells of the plant divide into four smaller cells, and each one of these becomes an antheri- Fig. 118. : ; Two sporocarps - still Sporocarp ruptured by dium. In C. soluta the an- surrounded by thallus. growth of egg to form cell theridia grow out from the Thallus finally decays and mass. Cells of this sporo- sets sporocarp free. phyte forming zoospores. end of terminal cells in the Figs. 117, 118, C. scutata. form of short flasks, some- times four in number or less (fig. 116). A single spermatozoid is formed from the contents. It is oval and possesses two long cilia. After swim- DS | n ing around it passes down the tube of the oogonium and fertilizes the —«- 268. Sporocarp.—After the egg is fertilized the cells of the threads near _ the egg grow up around it and form a firm covering one cell in thickness. This envelope becomes brown and hard, and serves to protect theegg. This ois the ‘fruit’ of the coleochzte, and is sometimes called a sporocarp _ (spore fruit). The development of the cell mass and the zoospores from the egg has been described above. a Some of the species of coleochzete consist of branched threads, while others _ form circular cushions several layers in thickness. These forms together with the form of our plant C. scutata make an interesting series of transi- tional forms from filamentous structures to an expanded plant body formed of a mass of cells. ¢™ a ; 7 t | ‘ a 4) a a pa y ‘ay : S rw oe 7 i gk : i > a % iy A om ad 7 Z : A - x pf eae vy weNe i? ee fn r J ‘ ga ie » 5 a Pan 4 Satul Ge es 4 COLEOCHATE. 114) i% Dee ead be MORPHOLOG Y., 114 ‘S[[99 Jo ‘winIuoZ00 spuno.ims SSeUI B WAI0 speaiy} surdojaaua 0} SMOJ jo [[eM uonez HII; pue soaps JY ‘sia}ua p10z Iq ‘s}soy ; “WINIplayy|-oyeuueds yorym jo “(a7 Au a “uk YSva WOIJIUO|Sulusdo YSnory} aqny *[[99 “SoA ‘wInIpruo3 ‘ulese oseyd ‘ZaA/- 0} FW eS bh 839|‘p1oz 0, eWs1ads|Suo] YAM ‘Ja '3aA pa apZuis wos [RIVAVS 10 -00Z d[BUIS & UIOF ‘saqeyd apn) Sdojaaep ssods|wro ry [[eMasieT jayerporq [rag |-Siejua ‘wnmo0s0Q «janoy ‘erpusyuy |Aeu [139 Auy -119 yoeduios -007 ‘a1odsooz|Aq papunor "BTTTO OM} YM) ‘TeULsIeU IO\10 ‘speary} ‘ayeyo e suULIOJ YORY |-ans) s3q ‘poyenuosayjiqy "pover}UsIITFICT eipuosooz Aq |,eurwia 7, peyourig | -03[0) “WINIpLoyUe, *sa[ Rul | yord wol1y OM, ‘urse[dojoid jo|\jizemp uo sautjaurog ‘umIpiuo0s ‘ulese aseyd ‘SoA "BIT1O Jo uMOID/ IG S}1uia pue suado!"]]a9 sAlVe}a3aA |JUO -00Z9]SUIS B WIOJ / sdojaasp =yotym ‘T[90 839 YIM SPlOzZ0}4/TJ90 aANeJaZ9A paj/ulory [eIdAas ‘padeys| {eur 1199 Auy | “peroryy| “S][99. ‘wnt a10dsooz sutioj ‘sjsoqiadieqy j-eumeads [eaAg |-sueryo ‘wnIuos0g +|-yxSIp PIpHoywuy |'eI[Id jo UMOID|yO sSuOl } [eoUIpu 1, 49 -o30py) yora ' s[jao anojz|"(a10ds 00 YiIM ‘Vrpruo0s|-rod ureyadljo " spraryy OUT seplAiqd j10) 33y ap LE eae "payenusssyid -ooz [eao Ag jo} paywmry jayduis *uise{ do} -o1d jo }1q s}itua pur’ ' ‘sproz;suado ‘youeiq [vI9) "saya suoly ‘]]99 339/-o ye ur 19ds pal-ads uo {Jao papunos -uesq [e1deds uo s][99|-10d ~~ yeuruts9} “soyouriq eu ‘sjsoyjasieyT = |-[[90-0m} [TRIG [a Frey] ‘uMIUO0Z0QC Jepusys PIPUsyUY | wosy ‘s]]aO A9YIO pure spraiyy| ‘snonuty|-ayone A, ‘A[Wo1rp aseyd| ‘(a10dsoo0 pue ‘viptu0s00z)y0 ss p U2 -u0d ‘spray ‘ ‘SaA sdojaAaq |10) 33q ‘payeUusiayiq. ‘payelUusIayiq azerpionjnu Aq jo} paywry = |/payourisg | ‘S][99| ‘T]99 Bur ‘MOI8 TROL IpUI[AD ‘Aq}Oo11p aseyd ‘sjsay|-yesn{uod jo s}u9}U09 a1} ‘aqny Aq aye8nfu0D| ‘speaiyi jo dnipue 9PlAIp jo | speaiyy| e143 *B0A sdojaAaq, jeiodsoshZ |-uq ‘“payenuesayipugq |peoryy jo Jao Auy ‘payeyjusisyipuy) jsuryeeaiq Aq |S[[92 [TV ' [duis | -o1dg “LINN ‘SHLUWV) ‘SNVDAO IVAXAS Sw ance = ol ‘NOILVO ASVHd HAIL ‘dadOTHAA SI : 5 -I'IdILIN HIMOU‘L) -y i ee saiods sivag ADL OTOR yy TV ARES a ie #0 HSVHQ ("TLAWd pe es ee ee ee ‘OTA MOH “ONOdS (‘eIpluos pur suvsi0 [enxas ay} siveq) =“ LAHAOLANVO | ‘ALWHIOATOO ‘WAINODOGD ‘VINAHOAVA ‘VUADOUIdS NOU ATAVL AALLVAVANOO “F9Z ~ « ~~ 4 = CHAPTER XIX. BROWN AND RED ALG. 265. If it is desired to extend the study of the algz to other groups, especially to some of the marine forms, examples of the brown algze and of the red algee may be obtained. ‘These are accessible at the seashore, and for inland laboratories material may be preserved in formalin (2%). 266 The brown alge (Pheophycee).*—-A good representative of one division of the brown algze and one often used for study is the genus facus. 267. Form and occurrence of fucus.—This plant is a more or less branched and flattened thallus or ‘*frond.’”’ One of them, illustrated in fig. IIg, measures 15—30cw (6-12 inches) in length. It is attached to rocks and stones which are more or less exposed at low tide. From the base of the plant are developed several short and more or less branched expansions called ‘‘holdfasts,’’ which, as their name implies, are organs of attachment. Some species (F. vesiculosus) have vesicular swellings in the thallus. The fruiting portions are somewhat thickened as shown in the figure. Within these portions are numerous oval cavities opening by a circular pore, which gives a punctate appearance to these fruiting cushions. Tufts of hairs frequently project through them. 268. Structure of the conceptacles.—On making sections of the fruiting portions one finds the walls of the cavities covered with outgrowths. Some of these are short branches which bear a large rounded terminal sac, the oogonium, at maturity containing eight egg cells. More slender and much branched threads bear narrowly oval antheridia. In these are developed several two-ciliated spermatozoids. 269. Fertilization. At maturity the spermatozoids and egg cells float out- side of the oval cavities where fertilization takes place. The spermatozoid sinks into the protoplasm of the egg cell, makes its way to the nucleus of the egg, and fuses with it as shown in fig. 125. The fertilized egg then grows into a new plant. Nearly all the brown algz are marine. * The members of the group possess chlorophyll, but it is obscured by a brown pigment. 115 116 MORPHOLOGY. 270. The red alge (Rhodophycee).—The larger number of the so-called red algz occur in salt water, though a few genera occur in fresh water. l, if Ms Xe Li Fig. 121. Oogonium of fucus with ripe eggs. \ iN \\ LN fn SS st tiny Si call, a, ELF Fig. 119. Fig. 120. Portion of plant of fucus showing Section of conceptacle of fucus, showing conceptacles in enlarged ends; and oogonia, and tufts of antheridia. below the vesicles (Fucus vescicu- losus). (Lemanea grows only in winter in turbulent water of quite large streams. Batrachospermum grows in rather slow-running water of smaller streams. Both of these inhabit fresh water.) The plants of the group possess chloro- phyll, but it is usually obscured by a reddish or purple pigment. 271. Gracillaria —Gracillaria is one of the marine forms, and one species is illustrated in fig. 126. It measures 15—20c or more long, and is pro- fusely branched in a palmate manner. The parts of the thallus are more or less flattened. The fruit is a cystocarp, which is characteristic of the rhodo- BROWN AND RED ALG. 17 phyceze (floridez). In gracillaria these fruit bodies occur scattered over > the thallus. They are somewhat flask-shaped, are partly sunk in the 4 °o o - 2CBonr O74 v 37 on £ 2 y fi * q vi j 7A. : wt VS y * MI \ ly f ; A\; vi . Ane War, % a vt wh ee. hy" fe 5 4 Ts > . a > a) oS Se oak = nt = yi eX ahog } ale © a. ZH f 25 rm he P ~ 3 s De : Ree oe : : hi! a, ‘i , he ‘ poet i Sf 2: is y, 5 or 1a, ‘ ? i cae x xs 1h . ca -7 en NV eet tn Fig. 143. Fertilization in Peronospora alsinearum; tube from antheridium carrying in the sperm nucleus in figure at the left, female nucleus near; fusion of the two nuclei shown in the two other figures. (After Berlese.) are not developed here, but a nucleus in the antheridium reaches the egg cell. It sinks in the protoplasm of the egg, comes in contact with the nu- cleus of the egg, and fuses with it. Thus fertilization is accomplished. 128 MORPHOLOGY. Downy Mildews. 285. The downy mildews make up a group of plants which are closely related to the water moulds, but they are parasitic on land plants, and some species produce very serious diseases. ‘The mycelium grows between the cells of the leaves, stems, etc., of their hosts, and sends haustoria into the cells to take up nutriment. Gonidia are formed on threads which grow through the stomates to the outside and branch as shown in figs. 137-140. The gonidia are borne on the tips of the branches. The kind of branching bears some relation to the different genera. Fig. 137 is from Peronospora alsinearum on leaves of cerastium; figs. 138 and 139 are Plasmopara viticola, the grape mildew, while figs. 140 and 141 are trom Phytophthora infestans, which causes a disease known as potato blight. The gonidia of peronospora germinate by a germ tube, those of plasmop- ara first form zoogonidia, while in phytophthora the gonidium Fig. 144. may either germinate forming a Ripe oospore of Peronospora alsinearum. thread, or each gonidium may first form several zoogonidia as shown in fig. 142. 286. In sexual reproduction oogonia and antheridia are developed on the mycelium within the tissues. Fig. 143 represents the antheridium entering the oogonium, and the male nucleus fusing with the female nucleus in fertili- zation. ‘The sexual organs of Phytophthora infestans are not known. 287. Mucor, saprolegnia, peronospora, and their relatives have few or no septa in the mycelium. In this respect they resemble certain of the alge like vaucheria, but they lack chlorophyll. They are sometimes called the alga-like fungi and belong to a large group called Phycomycetes. CHAPTER XXII. FUNGI CONTINUED (RUSTS AND SAC FUNGI). “Rusts ’”* (Uredinee). 288. The fungi known as ‘‘rusts’’ are very important ones to study, since all the species are parasitic, and many produce serious injuries to crops. 289. 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 Fig. 146. Fig. 147. Fig. 148. Fig. 149. Wheat leaf with red Portion of leaf Naturalsize. Enlarged. Single rust, natural size. enlarged to show sorus. sor. Figs. 145, 146.—Puccinia graminis, red-rust stage (uredo stage). Figs. 147-149.—Black rust of wheat, showing sori of teleutospores. reddish-brown or reddish pustules, and is known as the ‘‘ red rust’’ (figs. 145, 146). Another form occurs in elongated black pustules, and this form is the one known as the ‘‘ black rust’? 129 130 MORPHOLOG ¥. (figs. 147-150). These two forms occur on the stems, blades, etc., of the wheat, also on oats, rye, and some of the grasses. 290. Teleutospores of the black-rust form.—If we scrape off some portion of one of the black pusttiles (sori), tease it out Fig. 151. Teleutospores of wheat rust, showing two cells and the pedicel. Tig. 152. Uredospores of wheat rust, one showing remnants of the pedicel. Fig. 150. Head of wheat showing black rust spots on the chaff and awns. in water on a slide, and examine with a microscope, we will see numerous gonidia, composed of two cells, and having thick, brownish walls as shown in fig. 151. Usually there is a slender brownish stalk on one end. ‘These gonidia are called /eleu/o- spores. ‘Vhey are somewhat oblong or elliptical, a little con- stricted where the septum separates the two cells, and the end cell varies from ovate to rounded. ‘The mycelium of the fungus FUNGI* FOSTS: 131 courses between the cells, just as is found in the case ot the carnation rust, which belongs to the same family (see Part III). 291. Uredospores of the red-rust form.—If we make a simi- lar preparation from the pustules of the red-rust form we will see that instead of two-celled gonidia they are one-celled. ‘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 gonidia 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 gonidia 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 teleutospores. 292. Cluster-cup form on the barberry. —QOn the barberry is found still another Ay Cf EP Fears is a9 “SS ; 3 Aa aa tee aa form of the wheat rust, the ‘‘ cluster cup’’ a stage. The pustules on the under side of. Sea the barberry leaf are cup-shaped, the cups ee being partly sunk in the tissue of the leaf, by b *. * a 1%, eeeg while the rim is more or less curved back- An? a a \ Tx sey) ward against the leaf, and split at several places. ‘These cups occur in clusters on the affected spots of the barberry i ¥ he ave wn Fig. 153. Biel s4. oe leaf as sho Barberry leaf with two Single spot Two cluster jn fig. 154. diseased spots, natural showing cluster cups more en- ues size. cups enlarged. larged, showing Within the split margin. Figs. 153-155.—Cluster-cup stage of wheat rust. cups numbers of one-celled gonidia (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) 132 MORPHOLOGY. is formed of similar rows of cells, which, instead of separating into gonidia, remain united to form a wall. These cups are usually borne on the under side of the leaf. 293. Spermagonia.—Upon the upper side of the leaves in the same spot — occur small, orange-colored pustules which are flask-shaped. They bear inside, minute, rod-like bodies on the ends of slender threads, which ooze sate a0 N i an fi N & 00 LEZ OZ fia Fig. 156. Section of an zcidium (cluster cup) from barberry leaf. (After Marshall-Ward.) out on the surface of the leaf. These flask-shaped pustules are called spermagonia, and the minute bodies within them sfervmatia, since they were once supposed to be the male element of the fungus. Their function is not known. ‘They appear in the spots at an earlier time than the cluster cups. 2930. How the cluster-cup stage was found to be a part of the wheat rust. —The cluster-cup stage of the wheat rust was once supposed also to bea dif- ferent plant, and the genus was called @c¢dium. ‘The occurrence of wheat rust in great abundance on the leeward side of affected barberry bushes in England suggested to the farmers that wheat rust was caused by barberry rust. It was later found that the ecidiospores of the barberry, when sown on wheat, germinate and the thread of mycelium enters the tissues of the wheat, forming mycelium between the cells. This mycelium then bears the uredospores, and later the teleutospores. FUNGI: RUSTS. 133 294. Uredospores can produce successive crops of uredospores.— Tne uredo- spores are carried by the wind to other wheat or grass plants, germinate, tts AE Fig. 157. Section through leaf of barberry at point affected with the cluster-cup stage of the wheat rust; spermagonia above, zcidia below. (After Marshall-Ward.) form mycelium in the tissues, and later the pustules with a second crop of uredospores. Several successive crops of uredospores may be developed in Fig. 158. A, section through sorus of black rust of wheat, showing teleutospores. 4, mycelium bearing both teleutospores and uredospores. (After de Bary.) , one season, so this is the form in which the fungus is greatly multiplied and widely distributed. 134 MORPHOLOGY. 295. Teleutcspores the last stage of the fungus in the season.—The teleu- tospores are developed late in the season, or late in the development of the o~ = SEES a 2 = WN = * RE is ‘e8 es = & 52 ON tee a y ‘ aoe & Mrs ay ; Rh eee \) = . a a SSS SS a) fe eA “A KN EN A> << Sea a pie. \ > 2. Fi ig; T5O, Germinating uredospore of wheat rust. (After Marshall- Ward.) Fig. 160. Germ tube entering the leaf through a stoma. host plant (in this case the wheat is the host). They ‘then rest during the winter. In the spring under favor- able conditions each cell of the nates, producing a_ short teleutospore germi- mycelium called a promy- celium, as shown in figs. rO1,) noe celium is usually divided From each cell a short, pointed pro- cess This promy- into four cells. is formed called a ‘¢ sterigma.”’ Through this the protoplasm moves and forms a small gonidium on the end, sometimes called a sporidium. 296. How the fungus gets from the wheat back to the barberry.—If these sporidia from the teleutospores are carried by the wind so that they lodge on lig. Buk Teleutospore germi- nating, forming promy- celium., ligs. 161-163.—Puccinia graminis (wheat rust). Promycelium of ger- minating forming sporidia, Fig. 162. teleutospore, Fig. 163. Germinating sporidia entering leaf of barberry by mycelium. (After Marshall-Ward.) FUNGI: RUSTS. 135 the leaves of the barberry, they germinate and produce the cluster cup again. The plant has thus a very complex life history. Because of the presence of several different forms in the life cyle, it is called a polymorphic fungus. The presence of the barberry does not seem necessary in all cases for the development of the fungus from one year to another. 297. Synopsis of life history of wheat rust. Cluster-cup stage on leaf of barberry. Mycelium between cells of leaf in affected spots. Spermagonia (sing. spermagonium), small flask-shaped bodies sunk in upper side of leaf; contain ‘‘ spermatia.’’ fEcidia (sing. ecidium), cup-shaped bodies in under side of leaf. Wall or peridium, made up of outer layer of fungus threads which are divided into short cells but remain united. | ( | At maturity bursts through epidermis of leaf; margin of { cup curves outward and downward toward surface of leaf. Central threads of the bundle are closely packed, but free. Threads divide into short angular cells which separate F and become zcidiospores, with orange-colored content. AEcidiospores carried by the wind to wheat, oats, grasses, ) | etc. Here they germinate, mycelium enters at stomate, a8 . ~ , and forms mycelium between cells of the host. Uredo stage (red rust) on wheat, oats, grasses, elc. Mycelium between cells of host. Bears uredospores (1-celled) in masses under epidermis, which is later ruptured and uredospores set free. Uredospores carried by wind to other individual hosts, and | new crops of uredospores formed. Teleutospore stage (black rust), also on wheat, etc. Mycelium between cells of host. Bears teleutospores (2-celled) in masses (sori) under epidermis, which is later ruptured. Teleutospores rest during winter. In spring each cell germi- nates and producesa promycelium, a short thread, divided into four cells. 136 MORPHOLOGY. Promycelium bears four sterigmata and four gonidia (or spo- ridia), which in favorable conditions pass back to the bar- berry, germinate, the tube enters between cells into the intercellular spaces of the host to produce the cluster cup again, and thus the life cycle is completed. 298. Higher fungi divided into two series.—Of the higher fungi there are two large series. One of these is represented by the mushrooms, a good example of which is the common mushroom (Agaricus campestris). (For the study of the mushrooms see Part III, Ecology.) The large group of fungi to which the mushroom belongs is called the basidiomycetes because in all of them a structure resembling a club, or basid- ium, is present, and bears a limited number of spores, usually four, though in some genera the number is variable. Some place the rusts (uredinez) in the same series (basidium series) because of the short promycelium, and four sporidia developed from each cell of the teleutospore. Sac Fungi. 299. The other large series of the higher fungi may be rep- resented by what are popularly called the ‘‘ powdery mildews.’’ Fig. 164 is from a photograph of two willow leaves affected by one of these mildews. ‘The leaves are first partly covered witha whitish growth of mycelium, and numerous chains of colorless gonidia are borne on short erect threads. ‘The masses of gonidia give the leaf a powdery appearance. ‘The mycelium lives on the outer surface of the leaf, but sends short haustoria into the epi- dermal cells. 300. Fruit bodies of the willow mildew.—On this same mycelium there appear later numerous black specks scattered over the affected places of the leaf. These are the fruit bodies (perithecia). If we scrape some of these from the leaf, and mount them in water for microscopic examination, we shall be able to see their structure. Examining these first with a low power of the microscope, each one is seen to be a rounded body, from which radiate numerous filaments, the appendages. Each one of these appendages is coiled at the end into the form ofa little hook. Because of these hooked appendages this genus is called wncinula. ‘This rounded body is the feri/hecium. FUNGI: SAC FUNGI. 137 301. Asci and ascospores.—While we are looking at a few of these through the microscope with the low power, we should uy Y * Af sat UA ©. Ny MST aS uUK/ eH yb ‘Y ~ TA Gl Ce Fig. 164. Leaves of willow showing willow mildew. The black dots are the fruit bodies (perithecia) seated on the white mycelium. press on the cover glass with a needle until we see a few of the perithecia rupture. If this is done carefully we will see several small ovate sacs issue, each containing a number of spores, as shown in fig. 166. Such asac is an ascus, and the spores are ascospores, 138 MORPHOLOG Y. 302. The sac fungi or ascomycetes.—The large group of fungi to which this uncinula belongs is known as the sac fungi, or ascomycetes. While Fig. 165. Willow mildew; bit of mycelium with erect conidiophores, bearing chain of gonidia ; gonidium at left germinating. Fig. 166. Fruit of willow mildew, showing hooked ap- pendages. Genus uncinula. Figs. 166, 167.—Perithecia (perithecium) of two powdery mildews, showing escape of asci containing the spores from the crushed fruit bodies. Fig. 167. Fruit body of an- other mildew with dichotomous appen- dages. Genus microsphera. many of the powdery mildews have a variable number of spores in an ascus, a large majority of the ascomycetes have just 8 spores in an ascus, while Fig. 168. Contact of an- theridium and carpo gonium (carpogonium the larger cell); the beginning of fertilization. Fig. 169. Disappear- ance of contact walls of anthe- ridium and Fig. 170. carpogonium, Fertilized egg surrounded by and fusion of the enveloping threads which the two nuclei. grow up around it. Figs. 168-170.— Fertilization in spharotheca; one of the powdery mildews. (After Harper.) some have 4, others 16, and some an indefinite number. The complex struc- ture of the fruit body, as well as the usually definite and limited number of - weg - +S re 7. = ; q - . FUNGI: CLASSIFICA TION. 139 spores in an ascus, places these fungi on a higher scale than the mucors, saprolegnias, and their relatives, where the number of gonidia in a sporangium is always indefinite. 303. Leaf curl of the peach, black knot of the plum and cherry, ergot of the rye and grasses, and many other fungi are members of the ascomycetes. The majority of the lichens are ascomycetes, while a few are basidiomycetes. 304. Classification of the fungi.—Those who believe that the fungi repre- sent a natural group of plants arrange them in three large series related to each other somewhat as follows: The Basidium Type or Series. The number of gonidia on a basi- dium is limited and definite, and The Gonidium Type or Series. The ; the basidium is a characteristic number of gonidia in the sporangium | structure; ex. uredinez (rusts), is indefinite and variable. It may be ; mushrooms, etc. very large or very small, or even only - The Ascus Type or Series. The belong the lower fungi; ex., mucor, | limited and definite, and the ascus saprolegnia, peronospora, etc. is a characteristic structure; ex. leaf curl of peach (exoascus), pow- dery mildews, black knot of plum, | ! one in a sporangium. To this series | number of spores in an ascus is | black rot of grapes, etc. 305. Others believe that the fungi do not represent a natural group, but that they have developed off from different groups of the algee by becoming parasitic. As parasites they no longer needed chlorophyll, and consequently lost it. They thus derive their carbohydrates from organic material manu- factured by the green plants. According to this view the lower fungi have developed off from the lower alge (saprolegnias, mucors, peronosporas, etc., being developed off from siphonaceous algze like vaucheria), and the higher fungi being developed off from the higher algze (the ascomycetes perhaps from the rhodophycez). CHAPTER (22a): LIVERWORTS. (HEPATIC¥E? 306. We come now to the study of representatives of another group of plants, a few of which we examined in studying the organs of assimilation and nutrition. I refer to what are called the liver- worts. Two of these liverworts belonging to the genus riccia are illustrated in figs. 58, 171. Riccia. 307. Form of the floating riccia (R. fluitans).—The gen- eral form of floating riccia is that of a narrow, irregular, flattened, ribbon-like object, which forks repeatedly, in a dichotomous manner, so that there are several lobes to a single plant. It receives its name from the fact that at certain seasons of the year it may be found floating on the water of pools or lakes. When the water lowers it comes to rest on the damp soil, and rhizoids are developed from the under side. Now the sexual organs, and later the fruit capsule, are developed. 308. Form of the circular riccia (R. crystallina).—The circular riccia is shown in fig. 171. The form of this one is quite different from the floating one, but the manner of growth is much thesame. The branching is more compact and even, so that a cir- cular plant is the result. This riccia inhabits muddy banks, lying flat on the wet surface, and deriving its soluble food by means of the little rootlets (rhizoids) which grow out from the under surface. Here and there on the margin are narrow slits, which extend 140 LIVERWORTS: RICCIA. I4I nearly to the central point. ‘They are not real slits, however, for they were formed there as the plant grew. Each one of these V-shaped portions of the thal- lus is a Jobe, and they were formed in the young condition of the plant by a branching in a forked manner. Since growth took place in all direc- tions radially the plant be- came circularin form. These large lobes we can see are forked once or twice again, as shown by the seeming shorter slits in the margin. 309. Sexual organs. — In Thallus of Riccia crystallina. order to study the sexual organs we must make thin sections through one of these lobes lengthwise and_ perpendicular to the thallus surface. ‘These sections are mounted for examination with the microscope. 310. Archegonia.—We are apt to find the organs in various stages of de- velopment, but we will select one of the flask-shaped structures shown in fig. 172 for study. This flask-shaped body we see is entirely sunk in the tissue of the thallus. This structure is the female organ, and is what we term in these plants the archegonium. It is more complicated in structure than the oogonium. The lower portion is enlarged and bellied out, and is the venter of the archegonium, while the narrow portion is the neck, » We here see it in section. The wall is one cell layer in thickness. In the neck is a canal, and in the base of the venter we see a large rounded cell with a distinct and large nucleus. This cell is the egg cell. 311. Antheridia.—The antheridia are also borne in cavities sunk in the tissue of the thallus. There is here no illustration of the antheridium of this riccia, but fig. 178 represents an antheridium of another liverwort, and there is not a great difference between the two kinds. Each one of those little rect- angular sperm mother cells in the antheridium changes into a swiftly moving body like a little club with two long lashes attached to the smaller end By the violent lashing of these organs the spermatozoid is moved through the water, or moisture which is on the surface of the thallus. It moves through the canal of the archegonium neck and into the egg, where it fuses with the nucleus of the egg, and thus fertilization is effected. 142 MORPHOLOGY. 312. Embryo.—In the plants which we have selected thus far for study, the egg, immediately after fecundation, we recollect, passed into a resting state, and was enclosed by a thick protecting wall. But in riccia, and in the other plants of the group which we are now studying, this is not the case. Fig, ‘x72. Fig. 173. Archegonium of riccia, showing neck, Young embryo (sporogoni- venter, and the egg; archegonium is partly um) of riccia, within the venter surrounded by the tissue of the thallus. of the archegonium ; the latter (Riccia crystallina.) has now two layers of cells. (Riccia crystallina.) The egg, on the other hand, after acquiring a thin wall, swells up and fills the cavity of the venter. Then it divides by a cross wall into two cells. These two grow, and divide again, and so on until there is formed a quite large mass of cells rounded in form and still contained in the venter of the archegonium, which itself increases in size by the growth of the cells of the wall. 313. Sporogonium of riccia.—The fruit of riccia, which is developed from the fertilized egg in the archegonium, forms a rounded capsule still enclosed in the venter of the archegonium, which grows also to provide space for it. Therefore a section through the plant at this time, as described for the study of the archegonium, should show this capsule. The capsule then is a rounded mass of cells developed from theegg. A sin- gle outer layer of cells forms the wall, and therefore is sterile. LIVERWORTS: RICCIA. 143 All the inner cells, which are richer in protoplasm, divide into four cells each. Each of these cells becomes a spore with a thick wall, and is shaped like a triangular pyramid whose sides are of the same extent as the base (tetrahedral). ‘These cells formed in Fig. 175. Riccia glauca; archegonium containing neariy mature spo- rogonium. sg, spore-producing Pig. 174. cells surrounded by single layer Nearly mature sporogonium of Riccia crystallina ; of sterile cells, the wall of the mature spore at the right. sporogonium. fours are the spores. At this time the wall of the spore-case dis- solves, the spores separate from each other and fill the now en- larged venter of the archegonium. When the thallus dies they are liberated, or escape between the loosely arranged cells of the upper surface. 314. A new phase in plant life.—Thus we have here in the sporogenium of viccza a very interesting phase of plant life, in which the egg, after fertilization, instead of developing directly into the same phase of the plant on which it was formed, grows into a quite new phase, the sole function of which is the development ofspores. Since the form of the plant on which the sexual organs are developed is called the gamefophyte, this new phase in which the spores are developed is termed the sforo- payte. Now the spores, when they germinate, develop the gamefo- phyte, or thallus, again. So we have this very interesting condi- —— —— — Nee SS eee —S a ——— ee 144 MORPHOLOGY. tion of things, the thallus (gametophyte) bears the sexual organs and the unfertilized egg. The fertilized egg, starting as it does from a single-celled stage, develops the sporogonium (sporo- phyte). Here the single-cell stage is again reached in the spore, which now develops the thallus. 315. Riecia compared with coleochete, edogonium, etc.—We have said that in the sporogonium of riccia we have formed a new phase in plant life. If we recur to our study of coleochzte we may see that there is here possibly a state of things which presages, as we say, this new phase which is so well formed in riccia. We recollect that after the fertilized egg passed the period ot rest it formed a small rounded mass of cells, each of which now forms a zoospore. ‘The zoospore in turn develops the normal thallus (gametophyte) of the coleochzte again. In coleochzete then we have two phases of the plant, each having its origin in a one-celled stage. Then if we go back to cedogonium, we will remember that the fertilized egg, before it developed into the cedogonium plant again (which is the gametophyte), at first divides into four cells which become zoospores. These then develop the cedogonium plant. Note. Too much importance should not be attached to this seeming ho- mology of the sporophyte of cedogonium, coleocheete, and riccia, for the nu- clear phenomena in the formation of the zoospores of cedogonium and coleo- chzte are not known. ‘They form, however, a very suggestive series. Marchantia. 316. The marchantia (M. polymorpha) has been chosen for study because it is such acommon and easily obtained plant, and also for the reason that with comparative ease all stages of development can be obtained. It illustrates also very well cer- tain features of the structure of the liverworts. The plants are of two kinds, male and female. ‘The two dif- ferent 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 thallus is flattened like nearly all of the thalloid forms, and branches in a forked manner. ‘The color is dark green, and through the middle line of the thallus the texture is different from that of the margins, so that it possesses what we term a LIVERWORTS: MARCHANTIA. 145 midrib, as shown in figs. 176, 180. The growing point of the thallus is situated in the little depression at the free end. Ifwe examine the upper surface with a hand lens we see diamond-shaped areas, and at the center of each of these areas are the openings known as the stomates. 317. Antheridial plants.—One of the male plants is figured at 176. It bears curious structures, each held aloft bya short stalk. ‘These are the an- theridial recep- tacles (or male gametophores). yA UA AE GIO YM ; Each one is cir- TOV} cular, thick, and shaped some- Fig. 176. what like a bi- Male plant of marchantia bearing antheridiophores. convex lens. ‘The upper surface is marked by radiating fur- rows, and the margin is crenate. Then we note, on careful examination of the upper surface, that there are numerous minute openings. If we make a thin section of this structure perpen- Fig. 177. . Section of antheridial receptacle from male plant of Marchantia polymorpha, showing cavities where the antheridia are borne. dicular to its surface we shall be able to unravel the mystery of its interior. Here we see, as shown in fig. 177, that each one of these little openings on the surface is an entrance to quite 146 MORPHOLOGY. a large cavity. Within each cavity there is an oval or ellip- tical 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. 178. This shows the structure of the antheridium, 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, as stated in the former chapter, changes into a swiftly moving body resembling a serpent with two long lashes attached to its tail. 318. The way in which one of these sperm mother cells changes into this spermatozoid is very curious. We first note that a coiled spiral body is appear- Fig. 178. Fig. 179. Section of antheridium of mar- Spermatozoids of marchantia, chantia, showing the groups of uncoiling and one extended, show- sperm mother cells. ing the two cilia. ing within the thin wall of the cell, one end of the coil larger than the other. The other end terminates in a slender hair-like outgrowth with a delicate vesi- cle attached to its free end. This vesicle becomes more and more extended until it finally breaks and forms two long lashes which are clubbed at their free ends as shown in fig. 179. 319. Archegonial plants.—In fig. 180 we see one of the female plants of marchantia. Upon this there are also very curious structures, which remind one of miniature umbrellas. The general plan of the archegonial receptacle (or female LIVERWORTS: MARCHANTITA. 147 gametophore), for this is what these structures are, is similar to that of the antheridial receptacle, but the rays are more pro- nounced, 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 direc- Fig. 180. Marchantia polymorpha, female plants bearing archegoniophores. tion as we did of the antheridial receptacle, we will be able to find what is secreted behind these curtains. Such a section 1s figured at 184. Here we find the archegonia, but instead of being sunk in cavities their bases are attached to the under Se 148 MORPHOLOG Y. surface, while the delicate, pendulous fringes afford them pro- tection from drying. An archegonium we see is not essentially different in marchantia from what it is in riccia, and it will be interesting to learn whether the sporogonium is essentially dif- ferent from what we find in riccia. CHAPTER AAI. LIVERWORTS CONTINUED. 320. Sporogonium of marchantia.—If we examine the plant shown in fig. 181 we will see oval bodies which stand out be- Fig. 181. Archegonial receptacles of marchantia bearing ripe sporogonia 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. tween the rays of the female receptacle, supported on short stalks. These are the sporogonia, or spore-cases. We judge at once that they are quite different from those which we have studied in riccia, since those were not stalked. We can see that some of the spore-cases have opened, the wall splitting down from the apex inseveral lines. ‘This = is caused by the drying of the wall. ‘These tooth- like divisions of the wall now curl backward, and HAS. IIE LO IVAN\: arrmane NSPE ASIII CRIT NNO NLT NIOD.! z Cvelnet? a ’ ‘se 4.33.4 OW tp - P Le r LAM es yep ise Lien os E,W % is we can 5 @ e the yellowish mass of the spores in slow motion, 149 I50 MORPHOLOG Y. | : falling here and there. It appears also as if there were twisting | threads which aided the spores in becoming freed from the — capsule. % i: 4 y 5) Oh ts Oh Fig. 182. iS Section of archegonial receptacle of Marchantia polymorpha; ripe % sporogonia. One is open, scattering spores and elaters; two are uA still enclosed in the wall of the archegonium. ‘The junction of the Op stalk of the sporogonium with the receptacle is the point of attach- yA ment of the sporophyte of marchantia with the gametophyte. Y > 321. Spores and elaters.—If we take a bit O) of this mass of spores and mount it in water i for examination with the microscope, we will is | iw see that, besides the spores, there are very Bi 1 : : : i peculiar thread-like bodies, es 1 : is | the markings of which remind 2B 1 one of a twisted rope. These B ii . ‘es | are very long cells from the Bg } ‘ | inner part of the spore-case, o ! : S 1 and their walls Sy i are marked by spi- SE Ry, id Z| ral thickenings. £¥ aN S A Sas. [s¥ This causes them @, or ° ° ‘ / VE NONI NR Se indrying,andalso “Q ee Se Qs ONSEN SEN Ox On SIONS SONS es 4, LNT yy when they absorb oe 412. 103: moisture, to twist Elater and spore of marchantia. and curl in sf, spore; zc, mother-cell of spores, showing partly formed spores. all sorts of ways. ‘They thus aid in pushing the spores out of the capsule as it is drying. 322. Sporophyte of marchantia compared with riccia. — _ We must recollect that the sporogonium in marchantia is larger than in riccia, and that it is also not lying in the tissue of the \ thallus, but is only attached to it at one side by a slender stalk, LIVERWORTS: MARCHANTIA. ISI This shows us an increase in the size and complex structure of this new phase of the plant, the sporophy/e. This is one of the very interesting things which we have to note as we go on in the study of the higher plants. Fig. 184. Marchantia polymorpha, archegonium at the left with egg: archegonium at the right with young sporogonium; /, curtain which hangs down around the archegonia ; e, egg; v, venter of archegonium; xz, neck of archegonium; s/, young sporogonium. 323. Sporophyte dependent on the gametophyte for its nutri- ment.—We thussee that at no time during the development of the sporogonium is it independent from the gametophyte. This new phase of plants then, the sporophyte, has not yet become an in- dependent plant, but must rely on the earlier phase for sustenance. 324. Development of the sporogonium.—lIt will be interesting to note briefly how the development of the marchantia sporogonium differs from that of riccia. The first division of the fertilized egg is the same as in riccia, that is a wall which runs crosswise of the axis of the archegonium divides it into two cells. In marchantia the cell at the base develops the stalk, so that here there is aradical difference. The outer cell forms the capsule. But here after the wall is formed the inner tissue does not all go to make spores, as is the case with riccia. But some of it forms the elaters. While in riccia only the outside layer of cells of the sporogonium remained sterile, in marchantia the basal half of the egg remains completely sterile and 152 MORPHOLOGY. develops the stalk, ana in the outer half the part which is formed from some of the inner tissue is also sterile. Sy ty aN a Cot tS eke YR y. { | c i AV) | aK ? 19 2 Ny ¢ SO as SS on GR a + = S/ gam ——C —/ oJ RSL ae a was osZ=. SS >, 9 i = X) i KA Hy ATR Fig. 185. Section of developing sporogonia of marchantia; 7/, nutritive tissue of gametophyte ; s/, sterile tissue of sporophyte; sf, fertile part of sporophyte; wa, enlarged venter of arche- gonium. 325. Embryo.—In the development of the embryo we can see all the way through this division line between the basal half, which is completely sterile, and the outer half, which is the fertile part. In fig. 185 we see a young embryo, and it is nearly circular in section although it is composed of numerous cells. The basal half is attached to the base of the inner surface of the archegonium, and at this time the archegonium still surrounds it. The archegonium continues to grow then as the embryo grows, and we can see the remains of the shrivelled neck. The portion of the embryo attached to the base of the archegonium is the sterile part and is called the ‘ foot,”” and later develops the stalk. The sporogonium during all the stages of its development derives its nourishment from the gametophyte at this point of LIVERWORTS: MARCHANTTA. 153 attachment at the base of the archegonium. Soon, as shown in fig. 185 at the right, the outer portion of the sporogonium begins to differentiate into the cells which form the elaters and those which form spores. These lie in radiating lines side by side, and form what is termed the avchesporium. Each fertile cell forms four spores just as in riccia. They are thus called the mother cells of the spores, or spore mother cells. 326. How marchantia multiplies.—New piants of marchantia 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 places grow into well-formed plants. As the thallus lives from year to year and continues to grow and branch the older portions die off, and thus sepa- rate plants may be formed from a former single one. 327. Buds, or gemme, of marchantia.—but there is another way in which marchantia multiplies itself. If we examine the upper surface of such a Fig. 186. Marchantia plant with cupules and gemm2;; rhizoids below. plant as that shown in fig. 186, we will see that there are minute cup- shaped or saucer-shaped vessels, and within them minute green bodies. If we examine a few of these minute bodies with the microscope we will see that they are flattened, biconvex, and at two opposite points on the margin there is an indentation similar to that which appears at the growing end of the old marchantia thallus. These are the growing points of these little buds. When they free themselves from the cups they come to lie on one 154 MORPHOLOG Y. side. It does not matter on what side they lie, for whichever side it is, that will develop into the lower side of the thallus, and forms rhizoids, while the upper surface will develop the stomates. Leafy-stemmed liverworts. 328. We should now examine more carefully than we have done formerly a few of the leafy-stemmed liverworts (called foliose liverworts). 329. Frullania (Fig. 60).—This plant grows on the bark of logs, as well as on the bark of standing trees. It lives in quite dry situations. If we examine the leaves we will see how it is able to do this. We note that there are two Ble: rows of lateral leaves, which are very close together, so close in fact that they overlap like the shingles on a toa Fig. 187. Then, as the Section of thallus of marchantia. A, through the middle portion ; : B, through the marginal portion ; /, colorless layer; c/2, chlorophyll Creeping stems layer; sf, stomate; 4, rhizoids; 4, leaf-like outgrowths on under ,, side (Goebel). lie very close to the bark of the tree, these overlapping leaves, which also hug close to the stem and bark, serve to retain moisture which trickles down the bark during rains. If we examine these leaves from the under side as shown in fig. 62, we see that the lower or basal part of each one is produced into a peculiar lobe which is more or less cup-shaped. This catches water and holds it during dry weather, and it also holds moisture which the plant absorbs during the night and in damp days, ne Tag xe OND OR MYT Gee jae FOLIOSE LIVERWORTS. 155 There is so much moisture in these little pockets of the under side of the leaf that minute animals have found them good places to live in, and one frequently discovers them in this retreat. There is here also a third row of poorly developed leaves on the under side of the stem. 330. Porella.—Growing in similar situations is the plant known as porella. Sometimes there are a few plants in a group, and at other times large mats occur on the bark of a trunk. This plant, porella, also has closely overlapping leaves in rows on opposite sides of the stem, and the lower margin of each leaf is curved under somewhat as in frullania, though the pocket is not so well formed. The larger plants are female, that is they bear archego- nia, while the male plants, those which bear antheridia, are smaller and the an- theridia are borne on small lateral branches. The an- theridia are borne in the axils of the leaves. Others. of the leafy-stemmed ; ‘ : Fig. 188 liverworts live in oan : ° Thallus of a thalloid liverwort (blasia) showing lobed damp situations. margin of the frond, intermediate between thalloid and Some of these, as foliose plant. Cephalozia, grow on damp rotten logs. Cephalozia is much more delicate, and the leaves are farther apart. It could not live in such dry situations where the frullania is sometimes found. If possible the two plants should be compared in order to see the adaptation in the structure and form to their environment. 331. Sporogonium of a foliose liverwort.—The sporogonium of the leafy-stemmed liverworts is well represented by that of several genera, We may take for this study the one illustrated Hoa 156 MORPHOLOG ¥. in fig. 192, but another will serve the purpose just as well. We note here that it consists of a rounded capsule borne aloft on a long stalk, the stalk being much longer proportionately than in marchantia. At maturity the capsule splits down into four Fig. 190. Antheridium of a foliose liverwort (jun- germannia). Fig. 189. Fig. 191. Foliose liverwort, male plant showing anthe- Foliose liverwort, female plant with ridia in axils of the leaves (a jungermannia). rhizoids. quadrants, the wall forming four valves, which spread apart from the unequal drying of the cells, so that the spores are set free, as shown in fig. 194. Some of the cells inside of the capsule de- velop elaters here also as well as spores. ‘These are illustrated in fig. 196. 332, In this plant we see that the sporophyte remains attached FOLIOSE LIVERWORTS. 157 to the gametophyte, and thus is dependent on it for sustenance. This is true of all the plants of this group. ‘The sporophyte never becomes capable of an independent existence, and yet we see that it is becoming larger and more highly differentiated than in the simple riccia. Fig. 193. Opening capsule showing escape of spores and elaters. Fig. 194. Capsule parted down to the stalk. Fig. 192. Fruiting plant of a foliose liver- Fi Bia as wort (jungermannia). Leafy part ee ae is the gametophyte; stalk and cap- Four spores from Elaters, at left showing the two suleis the sporophyte(sporogonium mother cell held in spiral marks, at right a branched in the bryophytes). a group. eJater. Figs. 193-196.—Sporogonium of liverwort (jungermannia) opening by splitting into four parts, showing details of elaters and spores. CHAPTER XXIV. MOSSES (MUSCI). 300. 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 struc- ture. Yet there are certain general resemblances 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. ( Polytri- chium and funaria are good mosses to study.) 334. Mnium.—We willselect here the plant shown in fig. 197. 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 also. 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. There are three rows of these leaves, and this is true of most of the mosses. 335. ‘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 promi- nent leaves so arranged that it reminds 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 case in the leafy-stemmed liverworts. But along the middle line is a thicker layer, so that it forms a distinct midrib. ‘This is characteristic of the leaves 158 MOSSES. 159 of mosses, and is one way in which they are separated from the leafy-stemmed liverworts, the latter never having a midrib. 336. The fruiting moss plant.—In fig. 197 isa 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. The capsule then belongs to the sporophyte phase of the moss plant, and we should inquire whether the entire plant as we see it here is the sporophyte, or whether part of it is gametophyte. If a part of it is gametophyte and a part sporophyte, then where does the one end and the other begin? If we strip off the leaves at the end of the leafy stem, and make a longisection in the middle line, we should find that the stalk which bears the capsule is simply stuck into the end of the Fig. 197. YQ RZ wy AK ae. Portion of moss plant of Mnium affine, showing two 7 las\ sporogonia from one branch. Capsule at left has just shed ZX the cap or operculum ; capsule at right is shedding spores, < ee 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 dividing line, then, between the gametophyte and the sporo- j : : ‘ , ° woes leafy stem, and is not organically connected with it. This is phyte. We shall find that here the archegonium containing 160 MORPHOLOG Y. the egg is borne, which is a surer way of determining the limits of the two phases of the plant. 337. The male and female moss plants. —The two plants of mnium shown in figs. 198, I99 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, as in 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. Fig. 108. Fig. 199. Female plant (gametophyte) of a moss Male plant (gametophyte) of a moss (mnium), showing rhizoids below, and the (mnium) showing rhizoids below and the tut of leaves above which protect the arche- antheridia at the center above surrounded by gonia. the rosette of leaves. 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 center. The ends of the mass of antheridia can be seen with the naked eye, as shown in fig. 199. When the antheridia MOSSES. 161 are ripe, if we make a section through a cluster, or if we merely tease out some from the end with a needle in a drop of water on the slide, then prepare for examination with the microscope, we will see the form of the antheridia. They are somewhat clavate or elliptical in outline, as seen in fig. 201. Be- tween them there stand short threads composed of several cells containing chlorophyll grains. These are sterile threads (paraphyses). 338. Sporogonium.—lIn fig. 197 we see illustrated a sporogonium of mnium, which is of course developed from the fertilized egg cell of the archegonium. There is a nearly cylindrical capsule, bent downward, and supported on a long \\ at Hs A esi Ale Ee e stage sa: =s rb ety sus ne niet AF ao cuitan 4a rd ea} ai ree a He = AsO) ‘e ca EL LT s sin ni AA) HA 0 | rt a a nan ae Pets % 0 A cH BASE ("Bet POX Jo oe, sr \ NR ae ee at | \ PRS A Ne. Be a ys ‘ ¥ wwe! Manly \2or ces: we rE » h RBH | ESB NCR HR q DONS HO OD Seas ae ee @ PD aaoe eS Ea AH hho aa at ey Bees) aH (7 f ny ees A ECS RAH Nee: Hee Ge es RS? Yo ; AAR ee ee A ei we HH REN cote fT ; yi: ie AB ie erecagse ta Hy a eet ee EIN etl a RY, A RD EEC EEE ES ba Bi: SUD ounce aestnceg zeeaaeei Oni gali4 A KOH NS ! A RATER NE CE CCCET ECAR 8 oy aedecer glean TARA] gasneeere sty Ts x ig ' me Se ROO Fig. 200. Section through end of stem of female plant of mnium, show- ing archegonia at the center. One archegonium shows the egg. On the sides are sections of the protecting leaves. slender stalk. spatula. Fig. 201. Antheridium of mnium with jointed paraphysis at the left; spermato- zoids at the right. Upon the capsule is a peculiar cap,* shaped like a ladle or This is the remnant of the old archegonium, which, for a time sur- rounded and protected the young embryo of the sporogonium, just as takes place in the liverworts. In most of the mosses this old remnant of the arche- gonium is borne aloft on the capsule as a cap, while in the liverworts it is thrown to one side as the sporogonium elongates. * Called the calyptra. 339. Structure of the moss capsule.—At the free end on the moss capsule 162 MORPHOLOGY. as shown in the case of mnium in Fig. 197, after the remnant of the arche- gonium 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 it is desired to preserve this for study. 340. 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 micro- scope 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 If we blow our ‘‘breath”’ upon these teeth they will be seen to move, and as the ff moisture disappears and reappears in the teeth, they close and open the mouth of the capsule, so sensi- tive 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 opening. Rl Up the capsule at one time. NW i “ 341. Note. If we make a sec- WE {) ri i ! tion longitudinal of the capsule of Nit We oy) HE mnium, or some other moss, we find \y. as oe Ui; that the tissue which develops the a itl iN g spores is much more restricted Hy . than in the capsule of the liver- 4 ii i worts which we have studied. The \ | i: ) spore-bearing tissue is confined to WT a single layer which extends around the capsule some distance from the Fig. 202. outside of the wall, so that a central Two different stages of young sporogonium of cylinder is left of sterile tissue. a moss, still within the archegonium and wedg- This is the columella, and is pres- ing their way into the tissue of the end of the stem. h, neck of archegonium ; /, young sporogonium. ent in nearly all the mosses. Each t f tl hyt This ae 1 SEE SEE of the cells of the fertile layer divides into four spores. 342. Development of the sporogonium.—The egg cell after fertilization divides by a wall crosswise to the axis of the archegonium. Each of these cells continues to divide for a time, so that a cylinder pointed at both ends is formed. ‘The lower end of this cylinder of tissue wedges its way down through the base of the archegonium into the tissue of the end of the moss stem as shown in fig. 202. This forms the foot through which the nutrient MOSSES. 163 materials are passed from the gametophyte to the sporogonium. The upper part continues to grow, and finally the upper end differentiates into the mature capsule. 343. Protonema of the moss.—When the spores of a moss germinate they form a thread-like body, with chlorophyll. This thread becomes branched, and sometimes quite extended tangles of these threads are formed. This is called the protonema, that is fxs¢ thread. The older threads become finally brown, while the later ones are green. From this protonema at certain points buds appear which divide by close oblique walls. From these buds the leafy stem of the moss plant grows. Threads similar to these protonemal threads now grow out from the leafy stem, to form the rhizoids. These supply the moss plant with nutriment, and now the protonema usually dies, though in some few species it persists for long periods. MORPHOLOG Y. 164 ‘aynsdeo paz -Tepads ATysty ay Jo *sarods| *** * sdojadAap}‘-oza ‘y}90} ‘pry “ejour yt Swmntuodsaysie|-njoo ‘s1aAe_ [e1aAes (‘wmniu ay} St e[Jawanyoo|jo arnsdeo jo [[em|-oSo10ds sdo punoie s][99 Jo 19/4] VIS st s[nsded pa|-jaAeq) *3de -Aej [eoupuryAd = |-y[eys Joyredayiuaj}g = paz 48g *s19}e[9 pue S19} "satodg|***''*''*** sdol-eja ‘saaAey [e1aAes (‘uni -jaAep (umpodsjjo afnsdeo jo [Tem|-oZo10ds sdo -ayoie) + aynsdeo|‘y]e}S st atnsdeo pa)-[eAeq) “dda jo yaed yexyuad, §|-y[eIS JO Wed ajl4193g | peziyijAey *s19}e[9 pue ‘sarodg}**tstetetsss+sdo] ‘siazeya ‘sxaAey [ere (‘uIn1u -eAdp (umtods|-Aas jo aynsdvo jo [1e%;-08010ds sdo -ayoue) aynsdvo|‘4[e}s st aynsdeo pa-jeAeq “38a joyred peyusg $[-y[esjoywedosusyg |pozyniag ee eee (‘winiu *sa10dG}++++*+*++ sdojaaap "s]20,-08010ds sdo sseul [eijued |-odo10ds jo [eA peZzt[yaay ‘ALAHd ‘HLAHGOL | LUV AILYAT|] ‘“LAVd AIIYALG | -ONOdS AO -HNVS dO ONINNIOAG | ONINNIDAG (*JUIUIYSLINOU 10F 31 UO UspUsdap pue oyAydojoures 0) pa—peny) ALAHdOXOdS | (‘90U9}sTx9 JUSpusdaepul uv spray] *zur{d 9y} jo red yusuIwOIg) “FTLAHAOLANVD (‘uniuoZays1e jo jyueuulol sl umr1uoso0i0ds uo ‘yued punoy veijdéjed)/ayeur jo wia3s jo ‘yuertd oaz[eweyipuo ye ‘sproz uo ‘339 Y}IM Yoea|-oyeurtads = yy ‘eu -was Aq coon ‘syuerld ayeusy awos UJ) ‘WN puede ‘ese}s [eu] ‘930 2) -1wos010ds udAd\-au0j01d 191j1e9 UB UO! ‘WAHD Jo ‘saAvay ‘sixe/aui0g ‘(eluueWiesunN[| -INLATOg WOLJ CUWIIU0}!0} I[IWIS) SaARIT JO|\‘VINVNOAY yaaa y [etl ey acy -o1d jo yyMmois Aq|\smo. £ ‘stxe Ayeay jus} SWAIN] *sjurld yuo1ayIp u— ‘Suryoueiq Ag |-redde yy jurig ‘SASSOJ] ajeut jo nes ‘sjuerd eyeuay pue a ‘yue[d ayeursy uo|jo sjixe ut ‘sproz el lat gly nl itd cad ERA: 9UWI099q BARY SNI[VY}|-1aNOg ‘VIZ jo sulgivut ‘uWla}ys) -OlvPdad ‘syed 1apjo Jo|pue sadreay juored) 10) VINNVW Aeme Sutfp Aq |-de yym jued y -MHONOL ‘339 YUM Yoea|-oyeursods YIM ‘eruosayo1y |‘eIprsa9sy}yUy ‘sjueld JusiazfIp ud ‘339 ue} so10ydojowed YUM yoea ‘(a10yd/ayeut 10 ‘sa10yd -OLUOSIYIAL/-OLp1i9sy}yUe 10) a10ydoyowies|uo0 sui0g ‘sp1oz a[eulsy UO BUIOQ)-OyeuIIods YM ‘eiuosoyoiy |‘erpr19yyUuy ‘sor0yd -OJoUIeS Avaq sjuRd ‘euiues Aq puvia;euUoy pue dseUl ‘sjueyd yusrayip |‘syaed sapjo jo|‘payzoy ‘ayl-uoqqu ‘VIL uo sapse}dacat [eloads uo auiog =jAeme Suikp Ag |‘pousyey sniyeyy | -NYHOUVIT "yora ‘Sp1oz ut 839 yyWM!-oyeutrods YM | ts: ihe ; ‘syed sapro | BRE SUSE | ees jo Aeme ButAp) ‘repos Apivau 10 “SN[[eY} JO YIMOIS preM |pue Burpouriq ‘peysoy ‘axt[-uoqqu -dn ‘Sulpunoiins Aq pasisuwy |Aq sauitjewo0s “WIDDIA ‘peus}yey sniley yy | | = Sie ee OES) } ‘NOLL -VOTIdILIN JN FAIL VLADAA ‘ADVLS “SNVDUO TVAXA O S FAILVLAOT A ' ——— > ‘SUSSOW GQNV SLYOMUAATT AHL NI ALAHdOAOdS GNV ALAHdOLANVS HAO NOILVIAA ONIMOHS WIAVL ‘PPE CHAPTER XXV: PERNS. 345. 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 re- markable peculiarities of the structure of the fruit bodies, and especially because of the intermediate position which they occupy within the plant kingdom, 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 taking that form which is the more promi- nent, the fern plant itself. 346. 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 acrostichoides) shown in fig. 203. 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. ‘The leaf is elongate and reminds one somewhat of a plume with the pinnz extending in two rows on opposite 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 that certain ones, especially those toward the center of the rosette, are much narrower from the 165 166 MORPHOLOGY. middle portion toward the end. This is because of the shorter pinne here. 347. Fruit ‘dots’ (sorus, indusium).—If we examine the under side of such short pinnze of the Christmas fern we see that there are two rows of small circular dots, one row on either side of ,the pinna. ‘These are called “tie mes dots,’’ or sori (a single one is asorus). IEf we examine it with a low power of the mi- croscope, or with a p 0 Giese lens, we willseethat there 157 cire Wie disk which C0 Yi more “Os eless com- pletely very minute objects, usual- ly the ends Grime latter projecting just be- yond the edge if they are mature. ‘This circular disk is what is called the zdu- stum, and it is a special outgrowth of the epidermis of the leaf here forsame protection of the spore- \ \} SS SY ». NS NS As SWAY So, a My Wy S Ss cases. ‘These minute ob- Hig. 203. jects underneath are the Christmas fern (Adiantum acrostichoides). : ; : ; fruit bodies, which in the case of the ferns and their allies are called sporangia. ‘This indusium in the case of the Christmas fern, and also in some others, is attached to the leaf by means of a short slender stalk FERNS. 167 which is fastened to the middle of the under side of this shield, as seen in cross section in fig. 209. 348. Sporangia.—If we section through the leaf at one of the fruit dots, or if we tease off some of the sporangia so that the stalks are still attached, and examine them with the mi- croscope, we can see the form and structure of these peculiar bodies. Different views of a sporangium are shown im fig.: 210,~ .- The slender portion is the stalk, and the larger part is the spore-case proper. We should examine the structure of this spore-case quite care- fully, since it will help us to understand better than we otherwise could the remark- able operations which it performs in scattering the iy) ih Ay? wi -< (de BAN Wl 3) Vic WV CAN . ® MA spores. 349. Structure of a spo- rangium. — If we examine one of the sporangia in side view as shown in fig. 210, Fig. 204. we note a prominent row of ee with bases of leaves, and roots of the cel]s 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 out carefully, for the structure of these cells is especially adapt- ed to a special function which they perform. This row of cells 168 MORPHOLOGY. is termed the annulus, which means a little ring. While this is not a complete ring, in some other ferns the ring is nearly complete. 350. In the front of the sporangium is another peculiar group Fig, 205. Rhizome of sensitive fern (Onoclea sensibilis). of cells. Two of the longer ones resemble the lips of some crea- ture, and since the sporangium opens between them they are sometimes termed the lip cells. ‘These lip cells 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-walled cells, which may be termed connective cells, a since they hold each lip cell to its part ONO 4 of the opening sporangium. The cells ao on the side of the sporangium are also owe \ thin-walled. If we now examine a ae sporangium from the back, or dorsal ‘ig. 206. $ : 4 Under side of pinna of Aspidium edge as we Say, it will appear as in the spinulosum showing fruit dots (sori). left-hand figure. Here we can see how very prominent the annulus is. It projects beyond the surface of the other cells of the sporangium, ‘The spores are contained inside this case. FERNS. 169 351. Opening of the sporangium and dispersion of the spores.—If we take some fresh fruiting leaves of the Christmas 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 it on a piece of white paper in a dry room, in a very short time we will 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 leaf and place it under the low power of the microscope, so that the full rounded sporangia can be seen, in a short time we will note that the sporangium opens, the upper half curls backward as Fig. 207. Four pinnz of adiantum, showing recurved margins which cover the sporangia. shown in fig. 211, and soon it snaps quickly, to near its former position, and the spores are at the same time thrown for a consid- erable distance. ‘This movement can sometimes be seen with the aid of a good hand lens. 3592. 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 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 at 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 microscope to watch the 170 MORPHOLOG Y. sporangia, the water should be drawn from under the cover glass with the aid of some bibulous paper, like filter paper, placed at the =e Oa! DO Ge P4 ws MO SSR LER IAL Se% rf ACY} Rs ~ . past san =e 2. OeKe 2 2 Sess Neve; Fig. 208. Section through sorus of Polypodium vulgare sate different stages of sporangium, and one multicellular capitate hair. as the water comes out. edge of the cover glass on the opposite side from the glycerine. As the glycer- ine 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 drawn out of these cells there is produced a pressure from without, the atmospheric pressure upon the glycerine. ‘This causes the walls of these cells of the annulus to bend in- ward, because, as we have already learned, the glycer- ine does not pass through the walls nearly so fast 353. Now the structure of the cells of this annulus, as we have seen, is such that the inner walls and the perpendicular Fig. 209. Section through sorus and shield-shaped indusium of aspidium. walls are stout, and consequently they do not bend or collapse when this pressure is brought to bear on the outside of the cells. FERNS. 171 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 itself. ‘The sporangium I) Fig. 210. Rear, side, and front views of fern sporangium. d, ¢, annulus; «, lip cells. 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 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 snap in segments. 354. The movements of the sporangium can take place in old and dried material.—If we have no fresh material to study 172 MORK AOLOUG TY: 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 Fig. 211. : Dispersion of spores from sporangium of Aspidium acrostichoides, showing different stages in the opening and snapping otf the annulus. 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 FERNS. Lf 3 dot, when it disappears ina 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. 395. 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 succession. 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. 356. The common polypody.—We may now take up a few other ferns for study. Another common fern is the polypody, one or more species of which have a very wide distribution. The stem ofthis fern is also not usually seen, but is covered with the leaves, except in the case of those species which grow on the surface of rocks. The stem is slender and prostrate, and is covered with numerous brown scales. The leaves are pinnate in this fern also, but we find no difference between the fertile and sterile leaves (except in some rare cases). The fruit-dots occupy much the same positions on the under side of the leaf that they do in the Christmas fern, but we cannot find any indusium, In the place of an indusium are club-shaped hairs as shown in fig, 208, The en- larged ends of these clubs reaching beyond the sporangia give some protection to them when they are young. 357. Other ferns.—We might examine a series of ferns to see how different they are in respect to the position which the fruit dots occupy on the leaf. The common brake, which sometimes covers extensive areas and becomes a trouble- some weed, hasa stout and smooth underground stem (rhizome) which is often I2 to 20 cm beneath the surface of the soil. ‘There is a long leaf stalk, which bears the lamina, the latter being several times pinnate. ‘The margins of the fertile pinnz are inrolled, and the sporangia are found protected underneath in this long sori along the margin of the pinna, ‘The beautiful maidenhair fern and its relatives have obovate pinnz, and the sori are situated in the same posi- tions as in the brake. In other ferns, as the walking fern, the sori are borne along by the side of the veins of the leaf. : 358. Opening of the leaves of ferns.—The leaves of ferns open in a peculiar manner. ‘The tip of the leaf is the last portion developed, and the growing 174 MORPHOLOGY. leaf appears as if it was rolled up as in fig. 204 of the Christmas fern. As the leaf elongates this portion unrolls, 359. Longevity of ferns.—Most ferns live from year to year, by growth adding to the advance of the stem, while by decay of the older parts the stem shortens up behind. ‘The leaves are short-lived, usually dying down each year, and a new set arising from the growing end of the stem. Often one can see just back or below the new leaves the old dead ones of the past season, and farther back the remains of the petioles of still older leaves. 360. Budding of ferns. — A few ferns produce what are called bulbils or bulblets on the leaves. One of these, which is found throughout the greater part of the eastern United States, is the bladder fern (Cystop- teris bulbifera), which grows in shady rocky places. The long graceful delicate leaves form in the axils of the pinne, especially near the end of the leaf, small oval bulbs as shown in fig. 212. If we examine one of these bladder-like bulbs we see that the bulk of it is made up of short thick fleshy leaves, smaller ones ap- pearing between the outer ones at the smaller end of the bulb. ‘This bulb contains a stem, young root, and several pairs of these fleshy leaves. They easily fall to the ground or rocks, where, with the abundant moisture usually present in localities where the fern is found, the bulb Fig. 212. 5 Cystopteris bulbifera, young plant growing STOWS until the roots attach the plant from bulb. At right is young bulb in axil of ¢, the soil or in the crevices of the pinna of leaf. rocks, A young plant growing from one of these bulbils is shown in fig, 212. 361. Greenhouse ferns.—Some of the ferns grown in conservatories haye similar bulblets. Fig. 213 represents one of these which is found abundantly on the leaves of Asplenium bulbiferum. These bulbils have leaves which are very similar to the ordinary leaf except that they are smaller. The bulbs are also much more firmly attached to the leaf, so that they do not readily fall away. 362. Plant conservatories usually furnish a number of very interesting ferns, and one should attempt to make the acquaintance of some of them, for FERNS. 175 here one has an opportunity during the winter season not only to observe these interesting plants, but also to obtain material for study. In the tree ferns which often are seen growing in such places we see examples of the massive trunks and leaves of some of the tropical species. 363. The fern plant is a sporophyte.—We have now studied the fern plant, as we call it, and we have found it to represent the spore-bearing phase of the plant, that is the sporophyle (cor- responding to the sporogoniuin of the liverworts and mosses). 364. Is there a ga- metophyte phase in ferns ?—But in the spor- ophyte of the fern, which we should not forget is the fern plant, we have a striking advance upon the sporophyte of the liverworts and mosses. In the latter plants the sporophyte remained attached to the gameto- phyte, and derived its nourishment from it. In the ferns, as we see, the sporophyte has a root of its own, and is Fig. 213. attached to the soil. Bulbil growing from leaf of asplenium (A, bulbiferum). Through the aid of root hairs of its own it takes up mineral solutions. It possesses also a true stem, and true leaves in which carbon conversion takes place. It isable to live independently, then. Does a gametophyte phase exist among the ferns? Or has it been lost? If it does exist, what is it like, and where does it grow? From what we have already learned we should expect to find the gametophyte begin with the germination of the spores which are developed on the sporophyte, that is on the fern plant itself. We should investigate this and see. = , CHAPTER) 2A Vi- FERNS CONTINUED. Gametophyte of ferns. 365. 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 Cer, Patan -aceeeaeos Cy CRBS Pe LY TR SITAR TN AEBS TEP OREN ER, Ce, CBN PEAY AEE, AREVE Geek RRS ROD, ABET See yene es LEER DOYKUD " TOT AAAS OTRO AE AES EEN CY LATER Sod srasstN 2) AA A) (} WEBER BOY NT ) SOA TATE LYS Yrs BIER XS 7] Le iL dy, Oa Seath ESN SS \) Mp ec ees et UYU] 0 ETRY aoe Maeserace CX) ETT \] OX BESSON | AR OP oi ierassenne sess viet (cates QRS Sys () Ione Moses CORY I 8, CHOOT EN ne sci: oR Sa, ry ory & Cen re gS re eT QL OLA PET M% () &) (\ JA ahaa LSS ANRC GA Hh 8 tal Opa aeeee ns: ee a NN iN Og ede ee asi; ofO2—g 2 : Sai Aa ener ee sere: CY ao OF oe Ren ol rameter ees BEE SE we =e Vereee YRULD ESS A) WS Seis aeae Wey ym, oO Soeee Sey HY RED LY SY. SEY Be Lay OO Fig. 214. Prothallium of fern, under side, showing rhizoids, antheridia scattered among and near them, and the archegonia near the sinus. that the form of the plant which bears the sexual organs is de- veloped from the spores. ‘This is true, and if we should examine old decaying logs, or decaying w6od in damp places in the near 176 _ 5 FERNS. 177 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 surface of 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 Fig. 215. : Spore of Pteris serru- by keeping the surfaces where they are lata showing the three- ; - f : rayed elevation along growing moist, and the air also moist, by _ the side of which the : 2 spore wall cracks during placing a glass bell jar over them. germination. 366. In fig. 214 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 GOnegns - ate borne on the under side also, rae SS — > and we will studyrtivem Laver; Phare heart-shaped, flattened, thin, Fig. 216. Fig. 217. Spore of Adiantum Spore crushed to remove exospore and green plant 1S acrostichoides with show endospore. x winged exospore. the prothallium of ferns, and we should now give it more careful study, be- ginning with the germination of the spores. 367. 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. 215. The outer wall is roughened, and on one end are three elevated ridges which radiate from a given 178 MORPHOLOGY. point. A spore of the Christmas fern is shown in fig. 216. The outer wall here is more or less winged. At fig. 217 is a spore of the same species from which the outer wall has been crushed, showing that there is an inner wall also. If possible we should study the germi- nation of the spores of some fern. 368. Germination of the spores. —After the spores have been sown for about one week to ten days we should Fig. 218. Gee at bate oseennee ce Oe few in water for examination ere eae at ee with the microscope in order to study the early stages. If germination has begun, we will 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 sporan- gium wall that are ger- minating, when they will appear as in fig. 219. 369. Protonema.— These short green threads are called profonemal threads, or profonema, which means a first thread, and it here signifies that this short thread only pre- cedes a larger growth of the same object. In figs. 219, 220 are shown several stages of germination of different spores. Soon after Fig. 219. : 5 Gettivaling “apne log COE 'SROrt perm tube emerges from the Pteris aquilina still in the ; . ees : . ae je seseuilici tai: crack in the spore wall, it divides by the FERNS. 179 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 rhizoid, and serves both as an organ of attachment for the thread, and for taking up nutriment. 370. Prothallium.—Very soon, if the sowing has not been so crowded as to prevent the young plants from obtaining nutriment sufficient, we will see that the end of this protonema is broadening, as shown in fig. 220. 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 of the cells. The growing point remains at the mid- dle of the advancing margin, and the cells which are cut off from either side, as they become old, Fig. 220. widen out. In this way the Wipes Weoiiatisnteent-ateey. faapho: Swings,” or wargins of. the >. little, green, flattened body, are in advance of the growing point, and the object is more or less heart-shaped, as shown in fig. 214. Thus we see how the prothallium of ferns is formed. 371. Sexual organs of ferns.—If we take one of the prothal- lia of ferns which have grown from the sowings of fern spores, or one of those which may be often found growing on the soil 180 MORPHOLOGY. of pots in conservatories, mount it in water on a slip, with the under side uppermost, we can then examine it for the ; : j ebmtes Fig. 221. Male prothallium of a fern (niphobolus), in form of an alga or protonema. Spermato- zoids escaping from antheridia. sexual organs, for these are borne in most cases on the under side. 372. Antheridia.-—If we search among the rhizoids we will see small rounded elevations as shown in fig. 214 or 222 scat- Male prothallium of fern (niphobolus), showing opened and unopened antheridia ; 39, sec- tion of unopened antheridium; 40, spermatozoids escaping ; 41, spermatozoids which did not escape from the antheridium. ia | FERNS. ISI tered over this portion of the prothallium. These are the an- theridia. If the pro- thallia have not been watered for a day or so, we may have an opportunity of see- ing the spermato- zoids coming out of the antheridium, for when the prothallia Section of antheridia ea silt cells, and spermato- are freshly placed in zoids in the one at the right. ; water the cells of the antheridium ab- sorb water. ‘This presses on the con- tents of the antheridium 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 Fig. 224. i Different views of spermatozoids; first close. But as the spermatozoid 42, 43, in a quiet condition; 44, in ‘ E : motion (Adiantum concinnum). begins to move this coil opens some- what and 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. 373. Archegonia.—If we now examine closely on the thicker part of the under surface of the prothallium, just back of the oe “te Archegonium of fern. Large cell in the sinus, we may see longer venter is the egg, next is the ventral canal cell, and in the canal of the neck are two stout projections from the surface nuclei of the canal cell. of the prothallium. These are shown in fig. 214. ‘They are 182 MORPHOLOGY. the archegonia. One of them in longisection is shown in fig. 225. It is flask-shaped, and the broader portion is sunk in the Fig. 226. Mature and open archegonium of fern (Adiantum cuneatum) with spermatozoids making their way down through the slime to the egg. tissue of the prothallium. ‘The egg is in the larger part. The spermatozoids when they are swimming around over the under surface of the pro- thallium come near the neck, and here they are caught in the viscid substance which has oozed out of the canal of the arche- gonium. From here they slowly swim down the canal, and finally one sinks into | Fig. 227. the egg, fuses with the nucleus of the latter, od? ( ilizati j = ay @ ® «8 € Way aoe and the egg is then fertilized. It is now zoid fusing with the nu- cleus of the egg. (After Teady to grow and develop into the jie plant. This brings us back to the sporo- Campbell.) phyte, which begins with the fertilized egg. Sporophyte. 374. Embryo.—The egg first divides into two cells as shown in fig. 228, then - into four. Now from each one of these quandrants of the embryo a definite part of the plant develops, from one the first leaf, from one the stem, from one the root, and from the other the organ which is called the foot, and which FERNS. 183 attaches the embryo to the prothallium, and transports nourishment for the embryo until it can become attached to the soil and lead an independent ex- istence. During this time the wall of the archegonium grows somewhat to accommodate the increase in size of the embryo, as shown in figs. 229, 230. But soon the wall of the archegonium is ruptured and the embryo emerges, the root attaches itself to the soil, and soon the prothallium dies. The embryo is first on the under side of the prothallium, and the first leaf Fig. 228. Two-celled embryo of Pteris serrulata. Remnant of archegonium neck below. and the stem curves upward between the lobes of the heart-shaped body, and then grows upright as shown in fig. 231. Usually only one embryo is formed on a single prothallium, but in one case I found a prothallium with two well- formed embryos, which are figured in 232. 375. Comparison of ferns with liverworts and mosses.—In the ferns then we have reached a remarkable condition of things as compared with that which we found in the mosses and liverworts. In the mosses and liverworts @ iene 184 MORPHOLOGY. the sexual phase of the plant (gametophyte) was the prominent one, and consisted of either a thallus or a leafy axis, but in either case it bore the sexual organs and led an independent existence; that is it was capable of ob- taining its nourishment from the soil or water by means of organs of absorp- tion belonging to itself, and it also performed the office of carbon conversion. 376. The spore-bearing phase (sporophyte) of the liverworts and mosses, - on the other hand, is quite small as compared with the sexual stage, and it is Fig, 229. Young embryo of fern (Adiantum concinnum) in enlarged venter of the archegonium. 5S, stem; ZL, first leaf or cotyledon; A, root; /, foot. completely dependent on the sexual stage for its nourishment, remaining at- tached permanently throughout all its development, by means of the organ called a foot, and it dies after the spores are mature. 377. Now in the ferns we see seyeral striking differences. In the first place, as we have already observed, the spore-bearing phase (sporophyte) of FERNS. 185 the plant is the prominent one, and that which characterizes the plant. It also leads an independent existence, and, with the exception of a few cases, r does not die after the development of the spores, but lives from year to year and develops successive crops of spores. There is a distinct advance here in * the stze, complexity, and permanency of this phase of the plant. 378. On the other hand the sexual phase of the ferns (gametophyte), while it still is capable of leading an independent existence, is short-lived (with very few exceptions). It is also much smaller than most of the liverworts and Fig. 230. Embryo of fern (Adiantum concinnum) still surrounded by the archegonium, which has grown in size, forming the “‘ calyptra.’’ JZ, leaf; 5S, stem; A, root; #, foot. - mosses, especially as compared with the size of the spore-bearing phase. The gametophyte phase or stage of the plants, then, is decreasing in size and __ durance as the sporophyte stage is increasing. We shall be interested to see if this holds good of the fern allies, that is of the plants which belong to the same group as the ferns. And as we come later to take up the study of the higher plants we must bear in mind to carry on this comparison, and see if this progression on the one hand of the sporophyte continues, and if the _ retrogression of the gametophyte continues also. ad MORPHOLOG Y. AS) LN SSS \\ < J iN i A Swarasee SIN \ chr Me v My \ ited ANA NN \ ot g\ ‘ BADR ANS. 6 0 WM, LAY ME iy? =A: i s, i} | “G; ( \AAAA be 4 oath uly fh yy. TL, AA KTA Sa 4 Fig. 232. Fig. 231. Young plant of Pteris serrulata still T'wo embryos from one prothallium of attached to prothallium. Adiantum cuneatum, CHAPTER AAV AE. HORSETAILS. 879. Among the relatives of the ferns are the MSR horsetails, so called because of the supposed resem- blance of the branched stems of some of the species Qagsaga 's tail, as ight infer from the plant SSigee to a horse’s tail, as one might infer from the plant Sey . ry §0)¢ «© shown in fig. 239) They do not bear the least re- WERy semblance to the ferns which we have been study- i ing. But then relationship in plants does not depend | | on mere resemblance of outward form, orof the promi- & nent part of the plant. 380. The field equisetum. Fertile shoots.—Fig. 233 represents the common horsetail (Equisetum ar- vense). It grows in moist sandy or gravelly places, and the fruiting portion of the plant (for this species is dimorphic), that is the portjon 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 Io 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 inter- oe a ak : : fertile plant of nodes carefully we note that there are thin mem- xouisctum ar- branous scales, more or less triangular in outline, and \9rsgsrow'ns connected at their bases into a ring around the stem. attene aaa 187 188 MORPHOLOG Y. Curious as it may seem, these are the leaves of the horsetail. The stem, if we examine it farther, will be seen to possess numer- ous ridges which extend lengthwise and which alternate with furrows. Farther, 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. 381. Sporangia.—The end of this fertile shoot we see pos- sesses a cylindrical to conic enlargement. ‘This is the fertile 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 por- tions of the fertile spike, and examine one of them with a low magnifying power, it will appear like the fig. 234. We see here that the angular area is a Fig. 234. disk-shaped body, with a stalk attached to its inner CP sc git ella surface, and with several long sacs projecting from A eee its inner face parallel with the stalk and surrounding cages ae the same. These elongated sacs are the sporangia, and the disk which bears them, together with the stalk which attaches it to the stem axis, is the sforophy//, and thus belongs to the leaf series. These sporophylls are borne in close whorls on the axis. ‘ 382. Spores.—When the spores are ripe the tissue of the sporangium becomes dry, and it cracks open and the spores fall out. If we look at fig. 235 we will see that the spore is covered with a very singular coil which lies close to the wall. When the spore dries this uncoils and thus rolls the spore about. Merely breathing upon these spores is sufficient to make them perform 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. 383. Sterile shoot of the common horsetail.—When the spores are ripe they are soon scattered, and then the fertile shoot dies down. Soon afterward, or even while some of the fertile shoots are still in good condition, sterile shoots of the HORSETAILS. 189 plant begin to appear above the ground. One of these is shown in fig. 237. ‘This has a much more slender stem and is pro- Fig. 235. Fig. 236. Spore ot Pg ath Spore of equisetum with elaters un- with elaters coiled up. coiled. vided with numerous branches. If we ex- amine the stem of this shoot, and of the branches, we will 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 this per- forms the function of carbon conversion. 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. 384. The scouring rush, or shave grass. —Another common species of horsetail in the Northern States grows on wet banks, or in sandy soil which contains moisture along railroad embankments. It is the scouring rush (E. hyemale), so = called because it was once used for ! polishing purposes. ‘This plant like Fig. 237. Sterile plant of horsetail (Equi- il the species of the horsetails has semeavent, oe 190 MORPHOLOG Y. 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 un-_ branched, 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. 385. Gametophyte of equisetum.—The spores of equisetum have chloro- phyll 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 pro- ‘thallium (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 reproductive organs, and the phases and fruiting of the plant, are more essential in deter- mining relationships of plants than the mere outward appearances. CHAPTER XXVIII. CLUB MOSSES. 386. What are called the ‘‘ club mosses’’ make up another group of interesting plants which rank as allies of the ferns. They are not of course true mosses, but the general habit of some of the smaller species, and especially the form and size of the leaves, suggest a resem- SB oS CS \ blance to the larger of the moss plants. a a LX ~—/7 is 387. The clavate lycopodium.—Here is one of the club mosses (fig. 238) which has a wide distribution and which is well entitled to hold the name of club because of the form of the up- right club-shaped branches. As will be seen from the illustration, it has a prostrate stem. This stem runs for considerable distances on the surface of the ground, often partly buried in the leaves, and sometimes even buried beneath Va!) ya the soil. ‘The leaves are quite small, are flat- | Zag tened-awl-shaped, and stand thickly over the Y stem, arranged in a spiral manner, which is the usual arrangement of the leaves of the club mosses. Here and there are upright branches i which are forked several times. The end of pz one or more of these branches becomes prow === duced into a slender upright stem which is ee a Ra - seers ine > . tum, branch bearing two nearly leafless, the leaves being reduced to pe ce at right mere scales. The end of this leafless branch SPorephyll with open sporangium; single then terminates in one or several ‘cylindrical Spore near heads which form the club. —. CA RES oo ae Cx Css IgI 192 MORPHOLOGY. 388. Fruiting spike of Lycopodium clavatum.—This club is the fruiting spike or head (sometimes termed a s/roddus). Here the leaves are larger again and broader, but still not so large as the leaves on the creeping shoots, and they are paler. If we bend down some of the leaves, or tear off a few, we will see that in the axil of the leaf, where it joins the stem, there is a somewhat rounded, kidney-shaped body. ‘This is the spore-case or spo- rangium, as we can see by an examination of its contents. There is but asingle spore-case for each of the fertile leaves (sporophyll). When it is mature, it opens by a crosswise slit as seen in fig. 238. When we consider the number of spore-cases in one of these club- shaped fruit bodies we see that the number of spores developed ina large plant is immense. In mass the spores make a very fine, NW, soft powder, which is used for some A, . 3 . . A i kinds of pyrotechnic material, and for Oe = A) various toilet purposes. — Se he 389. Lycopodium lucidulum.—Another com- mon species is figured at 239. This is Lycopo- dium lucidulum, ‘The habit of the plant is quite different. It grows in damp ravines, woods, and moors. ‘The older parts of the stem are prostrate, while the branches are more or less ascending, It branches in a forked manner. The leaves are larger than in the former species, and they are all of the same size, there being no appreciable difference between the sterile and fertile ones. The characteristic club is not present here, but the spore-cases occupy certain regions of the stem, as shown at 239. Ina single season one region of the stem may bear spore-cases, and then a sterile portion of the same stem is Fig. 239. Lycopodium lucidulum, bulbils in axils of leaves near the top, sporangia in axils of leaves series of spore-cases higher up. developed, which later bears another below them. At right is a bulbil enlarged. : , ‘ ‘ 390. Bulbils on Lycopodium lucidulum.—There is one curious way in which this club moss multiplies. One may see frequently among the upper leaves small wedge-shaped or heart- shaped green bodies but little larger than the ordinary leaves. These are little an —— Gtr) Lae CLUS MOSSES. 193 buds which contain rudimentary shoot and root and several thick green leaves, When they fall to the ground they grow into new lycopodium plants, just as the bulbils of cystopteris do which were described in the chapter on ferns. 391. Note.—The prothallia of the species of lycopodium which have been studied are singular objects. In L. cernuum a cylindrical body sunk in the earth is formed, and from the upper surface there are green lobes. In L. phlegmaria and some others slender branched, colorless bodies are formed which according to Treub grow as a saphrophyte in decayed bark of trees. Many of the prothallia examined have a fungus growing in their tissue which is supposed to play some part in the nutrition of the prothallium, The little club mosses (selaginella). 392. Closely related to the club mosses are the selaginellas. These plants resemble closely the general habit of the club mosses, but are generally smaller and the leaves more delicate. Some species are grown in conservatories for ornament, the leaves of Fig. 240. Fig. 245. Fig. 242. Fig. 243. Selaginella with Fruiting spike Large spo- Small spo- three fruiting spikes. showing large and _ rangium. rangium. (Selaginella apus.) small sporangia. such usually having a beautiful metallic lustre. The leaves of some are arranged as in lycopodium, but many species have the leaves in four to six rows. Fig. 240 represents a part of a selaginella plant (S. apus). The fruiting spike possesses similar leaves, but they are shorter, and their arrangement gives to the spike a four- sided appearance. | i 194 MORPHOLOGY. 393. Sporangia.—On examining the fruiting spike, we find as in lycopodium that there is but a single sporangium in the axil of a fertile leaf. But we see that they are of two different kinds, small ones in the axils of the upper leaves, and large ones in the axils of a few of the lower leaves of the spike. The mucro- spores are borne in the smaller spore-cases and the macrospores in the larger ones. Figures 241-243 give the details. There are many microspores in a single small spore-case, but 3-4 ma- crospores in a large spore-case. 394. Male prothallia.—The prothallia of selaginella are much reduced structures. The microspores when mature are already divided into two cells. When they grow into the mature pro- thallium a few more cells are formed, and some of the inner ones form the spermatozoids, as seen in fig. 244. Here we see that Fig. 244. Details of microspore and male prothallium of selagine!la; rst, microspore: 2d, wall re- moved to show small prothallial cell below; 3d, mature male prothallium still within the wall; 4th, small cell below is the prothallial cell, the remainder is antheridium with wall and three sperm cells within; 5th spermatozoid. After Beliaieff and Pfeffer. the antheridium itself is larger than the prothallia. Only an- theridia are developed on the prothallia formed from the microspores, and for this reason the prothallia are called made prothalha, In fact a male prothallium of selaginella is nearly all antheridium, so reduced has the gametophyte become here. 395. Female prothallia.—The female prothallia are devel- oped from the macrospores. ‘The macrospores when mature have a rough, thick, hard wall. The female prothallium begins to develop inside of the macrospore before it leaves the sporangium. The protoplasm is richer near the wall of the spore and at the LLL TLE CLUS - MOSSES. 195 upper end. Here the nucleus divides a great many times, and finally cell walls are formed, so that a tissue of considerable ex- tent is formed inside the wall of the spore, which is very different from what takes place in the ferns we have studied. As the prothallium matures the spore is cracked at the point where the three angles meet, as shown in fig. 246. ‘The archegonia are developed in this exposed surface, and several can be seen in the illustration. 396. Embyro.—After fertilization the egg divides in such a way that along cell called a suspensor is cut off from the upper side, > we f= Qt ; ; ous ; Na Zo 5 So ia =, BP a, oS CZ “tne Rpgie e tf fae LB. Aaeces FL MEER I SS 5 = - Whe oN gh a =—— fs = PN Mage ALP ME DEANS RS , “pk. WY 5 ——T a “ KES Sis 5: Vit ped ee y “ > py =! Fig. 245. Section of mature macrospore Mature female prothallium of Fig. 247. of selaginella, showing female selaginella, just bursting open Seedling of sela- prothallium and _ archegonia. the wall of macrospore, exposing _ ginella still attached After Pfeffer. archegonia. After Pfeffer. to the macrospore. After Campbell. which elongates and pushes the developing embyro down into the center of the spore, or what is now the female prothalluum. Here it derives nourish- ment from the tissues of the prothallium, and eventually the root and stem emerge, while a process called the ‘‘ foot ’’ is still attached to the prothallium, When the root takes hold on the soil the embyro becomes free. Isoetes, mature plant, sporophyte stage. r e Te wae CHAPTER XXIX. QUILLWORTS: (ISOBRTEa 397. 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 leaf to a quill. Fig. 248 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, ex- cept the basal’ part, which is expanded, not very unlike, in out- line, a scale of an onion. ‘These expanded basal portions of the leaves closely overlap each other, and the very short stem is com- pletely covered at all times. Fig. 250 is from a longitudinal sec- tion of a quillwort. It shows the form of the leaves from this view (side view), and also the general outline of the short stem, which is triangular. ‘The stem is therefore a very short object. 196 QOUILLWORTS. 197 398. 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. 249. In the inner surface of the expanded base we note a circular depression which seems to be of a different text- big. 249. Fig. 250. Base of leaf of isoetes, Section of plant of Isoetes engelmanii, showing cup- showing sporangium with shaped stem, and longitudinal sections of the sporan- macrospores. (Isoetes en- gia in the thickened bases of the leaves. gelmannii.) ure from the other portions of the leaf. This is a sforangium. Beside the spores on the inside of the sporangium, there are strands of sterile tissue which extend across 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 remembered that sterile strands of tissue are found in some of the liverworts in the form of elaters. 399. The spores of isoetes are of two kinds, small ones (microspores) and large ones (macrospores), so that in this respect it agrees with selaginella, though it is so very different in other respects. When one kind of spore is borne in a sporan- a a ii 198 MORPHOLOG ¥Y. gium usually all in that sporangium are of the same kind, so that certain sporangia bear microspores, and others bear macrospores. But it is not uncommon to find both kinds in the same sporan- gium. Whena sporangium bears only microspores the number is much greater than when one bears only macrospores. 400. If we examine some of the microspores of isoetes we see that they are shaped like the quarters of an apple, that is they are of the bilateral type as seen in some of the ferns (asplenium). 401. Male prothallia.—lIn isoetes, as in selaginella, the microspores de- velop only male prothallia, and these are very rudimentary, one division of the spore having taken place before the spore is mature, just as in selagi- nella. 402. Female prothallia.—These are developed from the macrospores. The latter are of the tetrahedral type. The development of the female prothal- lium takes place in much the same way as in selaginella, the entire prothal- lium being enclosed in the macrospore, though the cell divisions take place after it has left the sporangium. When the archegonia begin to develop the macrospore cracks at the three angles and the surface bearing the arche- gonia projects slightly as in selaginella. 403. Embryo.—The embryo lies well immersed in the tissue of the pro- thallium, though there is no suspensor developed as in selaginella. CHAPTER XXX. COMPARISON OF FERNS AND THEIR RELATIVES. 404. Comparison of selaginella and isoetes with the ferns.—On compar- ing selaginella and isoetes with the ferns, we see that the sporophyte is, as in the ferns, the prominent part of the plant. It possesses root, stem, and leaves. While these plants are not so large in size as some of the ferns, still we see that there has been a great advance in the sporophyte of selagi- nella and isoetes upon what exists in the ferns. There is a division of labor between the sporophylls, in which some of them bear microsporangia with microspores, and some bear macrosporangia with only macrospores. In the ferns and horsetails there is only one kind of sporophyll, sporangium, and spore in a species. By this division of labor, or differentiation, between the sporophylls, one kind of spore, the microspore, is compelled to form a male prothallium, while the other kind of spore, the macrospore, is compelled to form a female prothallium. This represents a progression of the sporophyte of a very important nature. 405. On comparing the gametophyte of selaginella and isoetes with that of the ferns, we see that there has been a still farther retrogression in size from that which we found in the independent and large gametophyte of the liverworts and mosses. In the ferns, while it is reduced, it still forms rhizoids, and leads an independent life, absorbing its own nutrient materials, and assimilating carbon. In selaginella and isoetes the gametophyte does not escape from the spore, nor does it form absorbing organs, nor develop assimilative tissue. The reduced prothallium develops at the expense of food stored by the sporophyte while the spore is developing. Thus, while the gametophyte is separate from the sporophyte in selaginella and isoetes, it is really dependent on it for support or nourishment. 406. The important general characters possessed by the ferns and their so-called allies, as we have found, are as follows: The spore-bearing part, which is the fern plant, leads an independent existence from the prothallium, and forms root, stem, and leaves. The spores are borne in sporangia on the leaves. The prothallium also leads an independent existence, though in isoetes and selaginella it has become almost entirely dependent on the sporo- 199 200 | MORPHOLOGY. phyte. The prothallium bears also well-developed antheridia and arche- gonia. The root, stem, and leaves of the sporophyte possess vascular tissue. All the ferns and their allies agree in the possession of these char- acters. The mosses and liverworts have well-developed antheridia and archegonia, and the higher plants have vascular tissue. But no plant of either of these groups possesses the combined characters which we find in the ferns and their relatives. The latter are. therefore, the fern-like plants, or pleridophyla. ‘The living forms of the pteridophyta are classified as fol- lows into families or orders. 407. | Pteridophyta. Ophioglossacee. Marattiaceze. ? Heterosporous (Isoetaceze (Isoetes). ( Osmundaceeze. | Schizeeaceze. | Gleicheniacee. Class I. Filicales. ~Hymenophyl. 3 laceeze. Cyatheacee. Polypodiacez. _ Polypodium, Ono- Leptosporangiatee. clea, Aspidium, Homosporous. Eusporangiate.... Homosporous. ete. Salviniaceze. Heterosporous. } Mareiiiaeenas . Equisetacee. a ae Bip panepetae: (Equisetum). 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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 50 meters (about 160 feet), and the trunk a diameter of over 1 meter. In well-formed trees the trunk is straight and towering; 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 tothe tree. In oldand dense forests the lower branches, because of lack of sunlight, have died away, leaving tall, bare trunks for a considerable height. 410. The long shoots of the pine.—The branches are of twokinds. 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 togethér 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. 411. 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 erowth, 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. 202 GYMNOSPERMS: WHITE PINE. 203 412. 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. 413. Male cones, or male flowers.— The male cones are borne in clusters as shown in fig. 251. Each compact, nearly cylindri- Fig. 251. Spray of white pine showing cluster of male cones just before the scattering of the pollen. cal, or conical mass is termed a cone, or flower, and each arises in place of a long lateral branch. One of these cones is shown 204 MORPHOLOGY. considerably enlarged in fig. 252. 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. 253. It is completely covered by stout, thick, scale-like outgrowths. These scales are obovate in outline, and at the inner angle of the upper end Fig. 252. Figes3. Fig. 254. 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. there are several rough, short spines. They are attached by their inner lower angle, which forms a short stalk or petiole, and continues through the inner face of the scale as a ‘‘ mid- rib.’’ 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 sporophyll (microsporophyll). When the spores (microspores), which here are usually called pollen grains, are mature each sporangium, or anther locule, splits down the middle as 5 shown in fig. 254, and the spores are set free. ge) 414. Microspores of the pine, or pollen grains.—A mature pollen grain of the pine is Fig. 255. ! mink ‘ : Pollen grain of shown in fig. 255. It is a queer-looking object, white pine. possessing on two sides an air sac, formed by the upheaval of the outer coat of the spore at these two points. —————— sr rrt—C tststi“‘Cs—CSSOCtC is v _ GYMNOSPERMS: WHITE PINE. 205 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 by currents of air, the split suddenly opens, and a cloud of pollen bursts out from the numer- ous anther locules. The pollen is thus borne on the wind and some of it falls on the female flowers. Wi hi} NiAs SN oi iii S Ip i Pen if! egal Fey hf f See” White pine, branch with cluster of mature cones shedding the seed. A few young cones four months old are shown on branch at the left. Drawn from photograph. 415. Form of the ma- ture female cone.—A cluster of the white- . = fair DiBe.cones fs shown in Fig. 257. Mature cone of white pine at time of scattering of the seed, nearly natural size. SS fe ac6. “Ehese are mature, and the scales have spread as they do when mature and becoming dry, in order that the seeds may be set at liberty. ‘The general out- 206 MORPHOLOGY. line of the cone is lanceolate, or long oval, and somewhat curved. It measures about 1o-15cm long. If we remove one a ees 7 : | ni bial PERN Ah | My ric 4 wn ‘i N \ Nee ANA mt ‘ arly Fig. 258. Fig. 259. Fig. 260. Fig. 262. Sterile scale. Scale with Seeds have Back of scale Winged Seeds undevel- well-developed split off from with small cover seed free from oped. seeds. scale. scale. scale. Figs. 258-262.—White pine showing details of mature scales and seed. of the scales, just as they are beginning to spread, or before the seeds have scattered, we shall find the seeds at- tached to the upper surface at the lower end. There are two seeds on each scale, one at each lower angle. ‘They are ovate in outline, and shaped somewhat likea biconvex lens. At this time the seeds easily fall away, and may be freed by jarring the cone. AS th@wsecces detached from the scale a strip of tissue from the latter is peeled off. This formsa ‘‘ 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. 416. 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 the lateral shoots ina whorl. After growth has proceeded Female cones of the for some time in the spring, the terminal portion begins pine at time of pollina- tion, about natural size. to assume the appearance of a young female cone or GYMNOSPERMS: WHITE PINE. 207 flower. These young female cones, at about the time that the pollen is escaping from the anthers, are long ovate, measuring about 6-10 long. They stand upright as shown in fig. 263. 417. Form of a “scale” of the female flower. —If we remove one of the scales from the cone at this stage we can better study f\.. 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. 266, which is a view of the under side. ‘The small ‘‘ out- growth’’ 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 outside, covers it. (The inner scale is sometimes called the ovu- liferous scale, because it bears the ovules. ) 418. Ovules, or macrosporangia, of the pine.—At each of the lower angles of the 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- _ erous scale. cover scale. rangia) at base of the ovu- liferous scales. scale is a curious oval body with two curved, forceps-like pro- cesses at the lower and smaller end. These are the macro- sporangia, 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 208 MORPHOLOGY. mature cones. In fact the wall of the ovule forms the outer coat of the seed, as we will later see. 419. Pollination.—At the time when the pollen is mature the female cones are still erect on the branches, and the scales, which during the earlier stages of growth were closely pressed against : one another around the axis, are now spread apart. As the 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 £7 => a — = =. Fig. 267. 3ranch 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. this time the ovule has exuded a drop of 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 GYMNOSPERMS: WHITE PINE. 209 end of the ovule. This depression is thus known as the fodlen chamber. 420. Now the open scales on the young female cone close up again, so tightly that water from rains isexcluded. 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. 421. 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 : ; é Fig. 268. size is more rapid. The cone reaches Macrosporangium of pine : . (ovule). zzz¢, integument; ~, nu- maturity in September. We thus see cellus; », macrospore. (After Hoffmeister. that nearly eighteen months elapse from ~~ aaa the beginning of the female flower to the maturity of the cone, and about fifteen months from the time that pollination takes place. 422. Female prothallium ofthe pine.—To study this we must make careful longitudinal sections through the ovule (better made with the aid of a micro- tome). Such a section is shown in fig. 269. The outer layer of tissue, which at the upper end (point where the scale is attached to the axis of the cone) stands free, is the ovular coat, or ¢ztegument. Within this integument, near the upper end, there is a cone-shaped mass of tissue, which farther down continues along next the integument in a thinner strip. This mass of tissue is the zzcel/us, or the macrosporangium proper. The elliptical mass of tissue within this, shown in fig. 271 is the female prothallium, or what is usually here called the exdosperm. The conical portion of the nucellus fits over the 210 , MORPHOLOG Y. prothallium, and is called the nucellar cap. Only one end of the endosperm (prothallium) is shown in fig. 271. 423. Archegonia.—In the upper end of the endosperm (prothallium) are several archegonia, and they aid us in determining what portion is the female 4 i ie % trout £2 53 Fig. 269. Section of ovule of white pine. 7v/, integ- ument; fc. pollen chamber; 7, pollen tube ; n, nucellus; #z, macrospore Cavity. prothallium. The nucellus is of course formed before the prothallium. The latter arises from a cell (macro- spore) near the center of the nucellus. This cell is larger, and has a larger nucleus than its fellows (see fig. 268). The prothallium here is formed much in the same way as in selaginella, where we recollect it begins to de- velop before the macrospore has Fig. 270. Upper portion of nucellus of white pine. fx, pellen-grain remains; sfc, sperm Cells ; vn, vegetative nucleus; AZ, pollen tube. reached its full size, and where the archegonia begin to form before it leaves dD the macri sporangium. ' 424. Male prothallia.—By the time the pollen is mature the male pro- thallum is already partly formed. In fig. 255 we can see two well-formed cells. Other cells are said to be formed earlier, but they become so flattened that it is difficult to make them out when the pollen grain is mature. At this stage of development the pollen grain is lodged at the mouth of the ovule, re) and is drawn up into the pollen chamber. 425. Farther growth of the male prothallium.—During the summer and autumn the male prothallium makes some farther growth, but this is slow. The larger cell, called the vegetative cell, elongates by the formation of a tube, forming a sac, known as the pollen tube. It is either simple or branched. Inside of this sac the cells of the prothallium are protected, and farther GYMNOSPERMS: WHITE PINE. Zit division of the cells takes place here, just as the female prothallium develops in the cavity of the nucellus, from the macrospore. The nucleus of the vege- tative cell passes down the cavity of this tubularsac. The antherid cell, which is the smaller cell of the pollen grain, in the pine, divides by a cross wall into a so-called stalk cell, and a mother sperm cell, the latter corresponding to the central cell of the an- Fig. 271. Section through upper part of nucellus and Fig. 272. endosperm of white pine, showing upper por- tion of archegonium, the entering sperm cells, and track of pollen tube; zc, nucellus: //, pollen tube; sfc, sperm cells. Last division of the egg in the white pine cutting off the ventral canal cell at the apex ofthearchegonium. zd, endosperm; Axch, archegonium. theridium, there being no wall formed. The sperm mother cell also passes down the tubular sac, and divides again into two sperm cells, as shown in fig.270. About this time, or rather a little earlier, with the pollen tube part way through the nucellar cap, winter overtakes it, and all growth ceases until the following spring. 426. Fertilization.—In the spring the advance of the pollen tube con- tinues, and it finally passes through the nucellar cap about the time that the archegonia are formed and the egg cell is mature, as shown in fig. 271. The pollen tube now opens and the sperm cells escape into the archegonium, and later one of them fuses with the egg nucleus. The fertilized egg is now ready to develop into the embryo pine. 427. Homology of the parts of the female cone.—Opinions are divided as to the homology of the parts of the female cone of the pine. Some consider the entire cone to be homologous with a flower of the angiosperms. The en- 212 MORPHOLOGY. tire scale according to this view is a carpel, or sporophyll, which is divided into the cover scale and the ovuliferous scale. This division of the sporophyll is considered similar to that which we have in isoetes, where the sporophyll YY «<3 > oe ; oO Pind sa 0 oe” 30°? CN Se) we “2% Lf - t- =~ *~ - > io eee Oe re te 3 ? oa, - "Fr: 7 ue Noe SES on « Ef OE Sakti aks os ate s yd : toe Fig. 273. Fig. 274. Fig. 275. Fig. 276. Archegonium of Picea Archegonium of Picea Embryo of Pine seedling just vulgaris, sperm cell ap- vulgaris showing fusion white pine re- emerging from _ the proaching the nucleus of of sperm nucleus with moved from. ground. egg cell. egg nucleus. seed, showing several coty- ledons. Figs. 273, 274.—Fertilization in picea. (After Strasburger.) has a ligule above the sporangium, or as in ophioglossum, where the leaf is divided into a fertile and a sterile portion. A more recent view regards each cone scale as a flower, the ovuliferous scale composed of three united carpels arising in the axil of a leaf, the cover scale. Two of the carpels are reduced to ovules, and the outer integument is expanded into the lateral portion of the scale, while the central carpel is sterile and ends in the point or mucro of the scale. GYMNOSPERMS: WHITE PINE. a — ee — Pige 277. White-pine seedling casting seed coats. 213 CHAPTER XXXII. FURTHER STUDIES ON GYMNOSPERMS. Cycas. 428. In such gymnosperms as cycas, illustrated in the front- ispiece, there is a close resemblance to the members of the fern Fig. 278. Macrosporophyll revoluta. group, especially the ferns themselves. This is at once suggested by the form of the leaves. The stem is short and thick. The leaves have a stout midrib and humerous narrow pinne. In the center of this rosette of leaves are numerous smaller leaves, closely overlapping like bud scales. If we remove one of these at the time the fruit is forming we see that in general it conforms to the plan of the large leaves. ‘There are a midrib anda number of narrow pinne near the free end, the entire leaf being covered with woolly hairs. But at the lower end, in place of the pinnze, we see oval bodies. These are the macrosporangia (ovules) of cycas, and correspond to the macrosporangia of selaginella, and the leaf is the macrosporophyll. 429. Female prothallium of cycas.—In figs. 279, 280 are shown mature ovules, or macrosporangia, of cycas. In 280, which is aroentgen-ray photograph of 279, the oval prothallium can be seen. So in cycas, as in selaginella, the female prothallium is 214 FURTHER STUDIES ON GYMNOSPERMS. 215 developed entirely inside of the macrosporangium, and derives the nutriment for its growth from the cycas plant, which is the RAN “ : KS SS SAN Fig. 279. Fig. 280. Macrosporangium ot Cycas revoluta Roentgen photograph of same, show- ing female prothallium. sporophyte. Archegonia are developed in this internal mass of cells. ‘This aids us in deter- mining that it is the prothal- hum. In cycas it is also called endosperm, just as in the pines. 430. If we cut open one of the mature ovules, we can see the en- dosperm (prothallium) as a whitish mass of tissue. Immediately sur- rounding it at maturity is a thin, papery tissue, the remains of the nucellus (macrosporangium), and outside of this are the coats of the ovule, an outer fleshy one and an inner stony one. 431. Microspores, or pollen, of cycas.—The cycas plant illustrated in the frontispiece is a female plant. hig. 281. Male plants also exist which have A sporophyll (stamen) of cycas; sporangia in é groups on theunder side. 4, group of sporangia; small leaves in the center that bear ¢, open sporangia. (From Warming.) aes 216 MORPHOLOGY. only microsporangia. These leaves, while they resemble the ordinary leaves, are smaller and correspond to the stamens. Upon the under side, as shown in fig. 281, the microspo- rangia are borne in groups of three or four, and these contain the microspores, or pollen grains. The ar- rangement of these microsporangia on the under side of the cycas leaves bears a strong resemblance to the arrangement of the sporangia on the under side of the leaves of some ferns, 432. The gingko tree is another very interesting plant belonging to this same group. & It is a relic of a genus which Fig. 282. ' rag TS ese olia, show- \ ot thick stem, fern-like leaves, and cone of male flowers. flourished in the remote past, and it is interesting also because of the re- semblance of the leaves to some of the ferns like adiantum, which sug- gests that this form of the leaf in gingko has eget Wee ie Y been inherited from some ee fern-like ancestor. 433. While the resem- blance of the leaves of someof the gymnosperms to those of the ferns sug- gests fern-like ancestors for the members of this group, there is stronger evidence of such ances- try in the fact that a pro- thallium can well be de- Fig. 283. Two spermatozoids in end of pollen tube of cycas. (After termined in the ovules. drawing by Hirase and Ikeno.) The endosperm with its well-formed archegonia is to be considered a prothallium. 434. Spermatozoids in some gymnosperms.—But within the past two years it has been discovered in gingko, cycas, and zamia, all belonging to this FURTHER STUDIES ON GYMNOSPERMS. 217 group, that the sperm cells are well-formed spermatozoids. In zamia each one is shaped somewhat like the half of a biconvex lens, and around the con- vex surface are several coils of cilia. After the pollen tube has grown down through the nucellus, and has reached a depression at the end of the prothallium (endosperm) where the archegonia are formed, the spermatozoids are set free from the pollen tube, swim around in a liquid in this depression, and later fuse with the egg. In gingko and cycas these spermatozoids were first discovered by Ikeno and Hirase in Japan, and later in zamia by Webber in this country. In figs. 283-286 the details of the male prothallia and of fertilization are shown. 435. The sporophyte in the gymnosperms.— In the pollen grains of the gymnosperms we easily recognize the characters belonging to the spores in the ferns and their allies, as well as in Fig. 284. the liverworts and mosses. They belong to the _ !«ttilization in cycas, small ; spermatozoid fusing with the same series of organs, are borne on the same larger female nucleus of the egg. ‘ . The egg protoplasm fills the phase or generation of the plant, and are practi- archegonium. (From drawings - cally formed in the same general way, the bY H'tase and Ikeno.) variations between the different groups not being greater than those within a single group. ‘These spores we have recognized as being the product of the sporophyte. We are able then to identify the sporophyte as that phase or generation of the plant formed from the fertilized egg and bearing ultimately the spores. We see from this that the sporophyte in the gymnosperms is the prominent part of the plant, just as we found it to be in the ferns. The pine tree, then, Fig. 285. as well as the gingko, cycas, yew, hemlock- _ Spermatozoid of gingko, show- spruce, black spruce, the giant redwood of Cali- ing cilia at one end and tail at : the other (After drawings by fornia, etc., are sporophytes. Murase and Ikeno.) While the sporangia (anther sacs) of the male flowers open and permit the spores (pollen) to be scattered, the sporangia of the female flowers of the gymnosperms rarely open. The macrospore is developed within sporangium (nucellus) to form the female prothallium (endosperm). 436. The gametophyte has become dependent on the sporophyte.— In this respect the gymnosperms differ widely from the pteridophytes, though we see suggestions of this condition of things in isoetes and selaginella, where the female prothallium is developed within the macrospore, and even in sela- ginella begins, and nearly completes, its development while still in the spo- rangium, . e ; 218 | MORPHOLOGY. In comparing the female prothallium of the gymnosperms with that of the fern group we see a remarkable change has taken piace. The female pro- Fig. 286. Gingko biloba. A, mature pollen grain; 2, germinating pollen grain, the branched tube entering among the cells of the nucellus; x, exine (outer wall of spore); /, pro- thallial cell; /, antheridial cell (divides later to form stalk cell and generative cell); /3, vegetative cell; a, vacuoles; Ne, nucellus. (After drawings by Hirase and Ikeno.) pt thallium of the gymno- — sperms is very much reduced in size. Espe-— cially, it no longer leads an independent existence from the sporophyte, as is the case with nearly all the fern group. It remains enclosed within the macrosporangium (in cycas if not fertilized it sometimes grows outside of the macrosporangium and becomes green), and derives its nourishment through it from the sporo- phyte, to which the latter remains organically con- nected. This condition of the female prothallium of the gymnosperms necessitated a special adaptation of the male prothallium in order that the sperm cells may reach and fertilize the egg cell. Fig. 287. Gingko biloba, diagrammatic representation of the relation of pollen tube to the arche- gonium in the end of the nucellus. 7, pollen tube; 0, archegonium. (After drawing by Hirase and Ikeno.) 437. Gymnosperms are naked seed plants.—‘The pine, as we have seen, has naked seeds. ‘That is, the seeds ‘are not enclosed within the carpel, but FURTHER STUDIES ON GYMNOSPERMS. 219 are exposed on the outer surface. All the plants of the great group to which the pine belongs have naked seeds. For this reason the name ‘‘ gymnosperms”? has been given to this great group. 438. Classification of gymno- sperms.—The gingko tree has until recently been placed with the pines, yew, etc., in the class conifere, but the discovery of the spermatozoids in the pollen closely allied with the conifer, Fig. 288. Fig. 289. See Spermatozoids_ of Spermatozoid of zamia tube suggests that it is not zamia in pollen tube showing spiral row of fg, pollen grain; a,a, cilia. (After Webber.) spermatozoids. (After and that it represents a class Webber.) coordinate with them. Engler arranges the living gymnosperms as follows : Class 1. Cycadales; family Cycadacez. Cycas, zamia, etc. Class 2. Gingkoales ; family Gingkoacez. Gingko. Class 3. Coniferz; family I. Taxacez. Taxus, the common yew in the eastern United States, and Torreya, in the western United States, are examples. family 2. Pinaceze. Araucaria (redwood of California), firs, spruces, pines, cedars, cypress, etc. ‘Class 4. Gnetales. Welwitschia mirabilis, deserts of southwest Africa ; Ephedra, deserts of the Mediterranean and of West Asia. Gnetum, climbers (Lianas), from tropical Asia and America. MORPHOLOG Y. 220 ee sn][aonNN = uniduviods puy P9°S 1 uuedsopuy = ayAydojoures jo sureulad UT oiquy: = ayfydorods Sunox f -” * “ay4ydorods Suno ‘jusuINSe}UI pu snypoonu ul OAIquia oUIg = ayAydosods Suno x ‘Te9 wep = (pozynsay) 33 | ‘[[99 Wass IO ‘[[ao [BUIIIeIN| 337y | ‘wuodsopua ut ‘ejnosndioyg = (suvSi10 [enxas o]vUlay) BIUOSIYIIY | ‘snqjaonu ur ‘wuodsopuy = (uiniSuvsods ut) wniyeyjoid ayeuta.f ‘(snyjaonu ur survutes) tedsopua pur ovs-oAiquia sdojaa -ap YIYM sNyfeonu jo dajyUso Ut [Jao ese = (uimiSuviods ut sureuia1) s10dsos9 vy ‘g[NAO = JusuINSa}UI Aq pataaod snjpaonN = ‘(aTWOS 19A09 JO [IxB UT) Q]LIajs auO [eAyUID ay} fa[woS SNosajI[NAO oyur payun sjadivo se1y} 10 *(Y}MOId]NO Axeyjadievo pue a[vos 19A09) aywos snosoflNAgQ, = {[Aydosodsos9e Jy ‘s[[Ja0 daljeoUaS 10 ‘s[[ao [eULaIeG = sjjao utieds OM} ULIOJ 0} S9PIAIP UWMIPLayjUR jo [[9d [e1VUI (uv8i0 [enxas a[ewW) WNIPLayjue Jo [[99 [e.QUV9 pue [[99 [VIS WAOJ 0} SAPLArp [[90 WNIpPLoyUy ‘ureas uarod jo [[a0 [jewgG = [joo WnIpLoyjUy ‘urvis uazjod jo [99 aanRIsaA = (¢ [Jem WHIplayjue jo yzed) []a0 adv] ‘ureis uayjod amjeyy = UINIployjue AreJUIWIpPNA YIM UINITTeU} -o1d ayeur Areyusupns st a1odsosotut aanjzey{ 1 -+-9yAygdojoures § o[eulay yuotmnSoajur Aq pataaod wmnisuvsodsos9v Jy }- 2:8 6, as ayAydoiodg ~ *[[90 dal}VIIUIL) nee © ‘ayX{ydojowes FPN —_—S— “Orr ‘ulvis UZT]JOg = a10dsor91 yy ae sae gs ise wnisuviodsoriy | 2... sre +++ +93 Kydosodg usuIR}IS = {Aydosodsoss1yy ‘SQUOD JTVUIIJ puv IVY = yaed Suireaq-a10dg ‘2023 Ig = ay4ydosods ‘SWUAT, NOWWOD ‘SHLAHdOGINALG NI CASA ASOHL OL ONIGNOdSANNOD SWAT TL, ‘“ANId AHL NI ALAHAOLANVD UNV ALAHdOWOdS AO SHTOO'IONOH ONIMOHS HIAVL ‘68FP CHAPTER XXXIII. MORPH@LOGY OF THE ANGIOSPERMS: TRILLIUM; DENTARIA. Trillium. As one of the plants to illustrate 440. General appearance. 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. 290. 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—30cm (8--12 inches) in height. Near the upper end is a whorl of three ovate leaves, and from the center of this rosette rises the flower stalk, bearing the flower at its summit. 441. Parts of the flower. Calyx.—Now if we examine the flower we will 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 ca/yx in the higher plants, and the parts of the calyx are sepals, 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/ series. 221 222 MORPHOLOGY. 442. Corolla.—Next above the calyx is a whorl of white or pinkish members, in are also leaf-like in form, being usually somewhat make up what is the and each member of the they are parts of the their posi- also belong to the leaf 443. Andrecium. — the corolla is form and tion of of members which do not form. ‘They are known As seen in fig. 291 each ament), and extending ereater part of the length side. ‘This part of the ridges form the anther Trillium grandiflorum, which and broader than the sepals, broader at the free end. These corodla in the higher plants, corolla is a pefal. But while flower, and are not green, tion would suggest that they series. Within and above the inser- found another tier, or whorl, at first sight resemble leaves in in the higher plants as s/amens. stamen possesses a stalk (= fil- along on either side for the are four ridges, two on each stamen is the anther, and the sacs, or lobes. Soon after the flower is i opened, these an- ther sacs openalso bya split in the wall along the edge of the A ridge. At this time we see quantities of is ee yellowish powder or dust escaping fromthe — Trillium grandiflorum. ruptured anther locules. If we place some of this under the microscope we see ANGIOSPERMS: TRILLIUM. 223 that it is made up of minute bodies which resemble spores ; they are rounded in form, and the outer wall is spiny. ‘They are in fact spores, the microspores of the trillum, and here, as in the gymnosperms, are better known as pollen. Fig. 291. Sepal, petal, stamen, and pistil of Trillium grandiflorum. 444. The stamen a sporo- phyll.—Since these pollen grains are the spores, we would infer, from what we have learned of the ferns and gym- nosperms, that this member of the flower which bears them is a sporophyll ; and this is the case. It is in fact what is called the microsporophyll. Then we see also that the anther sacs, since they enclose the 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 in the flower of trillium. 445. Gynecium.—Next above the stamens and at the center of the flower is a stout, angular, ovate body which terminates in three long, slender, curved points. This is the pistil, and at Fig. 292. Trillium gran- diflorum, with the compound pistil expanded into three leaf- like members. At the right these three are shown in detail. al a, in ww . —_— 224 MORPHOLOGY. 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 wy body may have been formed by the Yon \S ANN \ infolding of the margins of three & leaf-like members, the places of pe = contact having then become grown together. We see also that from the. ,mcurved margins of each division of the Fig. 293. Abnormal trilllum. The nine parts of the perianth are green, and the outer whorls of stamens are expanded into petal - like members, pistil there stand out in the cavity oval 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 members which have fused together, each mem- ber 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 yet carried out with such great modifications that at first we do not see this common meeting ground Fig. 294. Which a comparative study brings out so clearly. ciamanstormed ~~ 446. Transformations of the flower of trillium.— se owns If anything more were needed to make it clear that the parts of the flower of trillium belong to the leaf series we could obtain evidence from the transformations which on the margin. ANGIOSPERMS: DENTARIA. 225 the flower of trilllum sometimes presents. In fig. 293 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. 292 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. Dentaria. 447. 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 diphylla) as it is sometimes called. This plant occurs in moist woods during the month of May, and is well distributed in the northeastern United States. A plant is shown in fig. 295. 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 opposite and the number is two, each one being divided into three dentate lobes, making what is called a compound leaf. 448. Parts of the flower.—The flowers are several, and they are borne on quite long stalks (pedicels) scattered over the ter- minal portion of the stem. We should now examine the parts of the flower beginning with the calyx. This we can see, look- ing 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 sta- mens are six in number, one pair lower than the others, and also 226 MORPHOLOGY. shorter. The filament is long in proportion to the anther, the’ 4 ‘y (9 y, VL, sub Sy we & Neue) W L) ae D YA ‘ \\ latter consisting of two lobes or sacs, instead of fouras intrilhum. ‘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 Fig. 296. they agree in this respect ; . Flower of the toothwort (Dentaria with the leaves; and diphylla). ; while we do not see o) such a strong resem- | A Prt os S ¥ = AIEESSaagp- " { = FZ — blance between the — = Le Wwe SFI ah! RY NTC i Vi Prive \ ( parts of the flower ipo \< SA s here and the leaves, Qey \ Z yet from the pres- Fig. 295. ence of the pollen Toothwort (Dentaria diphylla). ANGIOSPERMS: DENTARIA. 227 (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. 449. 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 num- ber. This is true of a large number of other plants, but it is not true of all. A glance at the spring beauty (Claytonia virginiana, fig. 349) and at the anemone (or Isopyrum biternatum, fig. 355) will serve to show that the number of the different members of the flower may vary. ‘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. CHAPTER XXXIV. GAMETOPHYTE AND SPOROPHYTE OF ANGIO- SPERWNS. 450. Male prothallium of angiosperms.—The first division which takes place in the nucleus of the pollen grain occurs, in the case of trillium and many others of the angio- sperms, before the pollen grain is mature. In the case of some specimens of T. grandiflorum in which the pollen was formed during the month of October of the year before flowering, the divi- Fig. 297. Nearly mature sion of the nucleus into two nuclei took place ollen grain of tril- : Hum. The smalier SOON after the formation of the four cells from cell is the genera- Bh a ‘ tive cell. the mother cell. ‘The nucleus divided in the young pollen grain is shown in fig. 297. After this takes place the wall of the pollen grain becomes stouter, and minute spiny projections are formed. 451. The larger cell is the vegetative cell of the prothallium, while the smaller one, since it later forms the sperm cells, is the generative cell. This generative cell then corresponds to the central cell of the antheridium, and the vegetative cell perhaps corresponds to a wall Mi Fig. 298. cell of the antheridium. If this is so, then the — Germinating spores male prothallium of angiosperms has become (Pollen grains) of pel- c tandra ; generative reduced to a very simple antheridium. ‘The nuclets in one undi- f 4 : vided, in other divided farther growth takes place after fertilization. to form the two sperm nuclei; vegetative nu- cleus in each near the the two sperm cells at the maturity of the pollen grain. In some plants the generative cell divides into g pollen grain. In other cases the generative cell divides in the pollen tube after the germination of the pollen grain. For study of the pollen tube the pollen may be germinated in a weak solution of sugar, or on the cut surface 228 GAMETOPAYVTE AND SPOROPAYTE. 229 of pear fruit, the latter being kept in a moist chamber to prevent drying the surface. 452. In the spring after flowering the pollen escapes from the anther sacs, and as a result of pollination is brought to rest on the stigma of the pistil. Here it germinates, as we say, that is it develops a long tube which makes its way down through the style, and in through the micropyle to the embryo sac, where, in accordance with , what takes place in other hy , plants examined, one of the sperm cells unites with the egg, and fertilization of the egg is the result. 453. Macrospore and embyvro sac. | —In trillium the three pistils or carpels are united into ‘/ one, and in’ den- taria the two carpels are also united into one compound carpel. Simple carpels are found in _ | many plants, for example in the ranunculaceee, the =<] buttercups, colum- bine, etc. ‘These simple carpels bear a | greater resemblance to a leaf, the mar- gins of which are folded around so that they meet and enclose the ovules or sporangia. 454. If we cut across the com- pound pistil of tril- lium we find that the infoldings of the three pistils meet to Fig. 299. Section of pistil of trillium Fig. 300. : showing position of ovules Mandrake (Podo- form three partial (macrosporangia phyllum peltatum). partitions which extend nearly to the center, dividing off three spaces. In these spaces are the ovules which are attached to the infolded margins. If we make cross sections of a pistil of the May- 230 MORPHOLOGY. apple (podophyllum) and through the ovules when they are quite young, we will find that the ovule has a structure like that shown in fig. 301. At m isacell much larger than the surround- ing ones. ‘This is the macrospore. ‘The tissue surrounding it is called here the nucellus, but because it contains the macrospore it must be the macrosporangium. ‘The two coats or integuments of the ovule are yet short and have not grown out over the end of the nucellus. This macrospore increases in size, forming first a cavity or sac in the nucellus, the eméryo sac. The nucleus divides Fig. jor. Young ovule (macrosporangium) of podophyllum. ~~, nucellus containing the one-celled stage of the macrospore; 7.z/¢, inner integument; v.zz/, outer integument. several times until eight are formed, four in the micropylar end of the embryo sac and four in the opposite end. In some plants it has been found that one nucleus from each group of four moves toward the middle of the embryo sac. Here they fuse to- gether to form one nucleus, the exdosperm nucleus or definitive nucleus shown in fig. 302. One of the nuclei at the micropylar end is the egg, while the tWo smaller ones nearer the end are the GAMETOPHYTE AND SPOROPHYTE. 231 synergids. The egg cell is all that remains of the archegonium in this reduced prothallium. The three nuclei at the lower end are the an/ipodal cells. Fig. 302. Podophyllum peltatum, evule containing mature embryo sac; two synergids and egg at left, endosperm nucleus in center, three antipodal cells at right. 455. Embryo sac is the young female prothallium.—In figures 303, 305 are shown the different stages in the develop- ment of the embryo sac in lilium. | The embryo sac at this stage is the young female prothallium, and the egg is the only remnant of the female sexual organ, the arche- gonium, in this reduced gameto- phyte. 456. Fertilization. — Before fertilization can take place the pollen must be conveyed from Bees soy. the anther to the stigma. (For Macrospore (one-celled stage) of lilium. the different methods of pollination see Part III.) When the pollen tube has reached the embryo sac, it opens and the sperm cell is emptied into the embryo sac near the egg. ‘The sperm nucleus now enters the protoplasm surrounding the egg nucleus. The male nucleus is usually smaller than the female nucleus, and sometimes, as in the cotton plant, it grows to near or quite the 232 MORPHOLOGY. size of the female nucleus before the fusion of the two takes place. In figs. 306 and 307 are shown the entering pollen tube with the sperm nucleus, and the fusion of the male and female nuclei. 457. Fertilization in plants is fundamentally the same as in animals.—In all the great groups of plants as represented by spirogyra, cedogonium, vaucheria, peronospora, ferns, gymno- Fig. 304. Two- and four-celled stage of embryo-sac of lilium. The middle one shows division of nuclei to form the four-celied stage. (Easter lily.) sperms, and in the angiosperms, fertilization, as we have seen, consists in the fusion of a male nucleus with a female nucleus. Fertilization, then, in plants is identical with that which takes place in animals. 458. Embryo.—After fertilization the egg develops into a short row of cells, the swspensor of the embryo. At the free end the embyro develops. In figs. 309 and 310 is a young embryo of trillium, 459. Endosperm, the mature female prothallium.—During the development of the embryo the endosperm nucleus divides > GAMETOPAHYTE AND SPOROPAYTE. 233 into a great many nuclei in a mass of protoplasm, and cell walls are formed separating them into cells. endosperm, and it surrounds the embryo. It is the ma/ure female prothalhum, belated in its growth in the angiosperms, usually de- veloping only when fertilization takes place, and its use has been assured. 460. Seed. As the embryo Fig. 305. Mature embryo sac (young pro- thallium) of lilium. #z, micropylar end; 5, synergids; /, egg; Px, polar nuclei; Azz, antipodals, (Easter liiy.) the end. This mass of cells is the Vy om, OUT ’ ae ~ ope tee aa es we ey oe ce ee Sage a See meee Sypris eS ee U4 id, i Se he ae . akan . . Seah " . e . . eekeoge he ee a, ke So. See ve “72 Ma 4 i i] : ys FO el SH oe, Fig. 306. Section through nucellus and upper part of embryo sac of cotton at time of entrance of pc llentube. £, ege: S, synergids; ?, pollen tube with sperm cell in (Duggar.) ee 234 MORPHOLOG ¥. is developing it derives its nourishment from the endosperm (or in some cases perhaps from the nucellus). At the same time AY AIT} VG Hi SAN nivel At i! HH YH A eee ae whacky pt, KEY t Bay es SEP BSOry ¥ ee oni pt eemate nu- EET cleus fusing. (Duggar.) DNR ARES f HIE TSS the integuments increase ASST . peace’ Ky in extent and harden as » PEN Ne the seed is formed. i zeaniae etna Wo si . Oa WATT d 461. Perisperm. — In ESPN ST | UTM most plants the nucellus is “-? RYT ‘ : SOC iG all consumed in the devel- a Nd LS ! <4 4 ee yA AM UA, k opment of the endosperm, ee NS oii it so that only minute frag- ‘ PANN SSSA EM SESH ments of disorganized cell PRES ‘ a iM f walls remain next the in- Se asceseri iy Qeenrees4) LAY) ner integument. Insome SSNS ants vl IH) plants, however, (the water- Fig. 308. lily family, the tat od oie Diagrammatic section of ovary and ovule at time ; i of fertilization in angiosperm. /, funicle of cvule; family, etc. , ) si portion of mn, nucellus; #2, micropyle; 4, antipodal cells of the nucellus remains in- ¢™bryo sac; e, endosperm nucleus; 4, egg cell and synergids ; az, outer integument of ovule; 7z, inner tact in the mature seed. imtegument. The track of the pollen tube is shown down through the style, walls of the ovary to the In such seeds the remain- ™'cropylar end of the embryo sac. ing portion of the nucellus is the perisperm. 462. Presence or absence of endosperm in the seed.—In many of the angiosperms all of the endosperm is consumed by the embryo during its growth in the formation of the seed. This is the case in the 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 pass- GAMETOPHVTE AND SPOROPHYTE. 235 ing from the endosperm into the embryo is stored in the cotyle- dons for use during germination. In other plants the endosperm Fig. 309. Fig. 310. Section of one end of ovule of trillium, showing Embryo en- young embryo in endosperm. larged. is not all consumed by the time the seed is mature. Examples of this kind are found in the buttercup family, the violet, lily, palm, Fig. 311. Fig. 312. Seed of violet, external view, and Section of fruit of pepper (Piper section. The section shows the embryo nigrum), showing small embryo lying lying in the endosperm. in a small quantity of whitish endo- 7 sperm at one end, the perisperm oc- cupying the larger part of the interior, surrounded by pericarp. jack-in-the-pulpit, etc. Here the remaining endosperm in the seed is used as food by the embryo during germination. 463. Sporophyte is prominent and highly developed.—In the angiosperms then, as we have seen from the plants already studied, the trillium, dentaria, i MORPHOLOGY. etc., are sporophytes, that is they represent the spore-bearing, or sporophytic, stage. Just as we found in the case of the gymnosperms and ferns, this stage is the prominent one, and the one by which we characterize and recognize the plant. We see also that the plants of this group are still more highly special- ized and complex than the gymnosperms, just as they were more specialized and complex than the members of the fern group. From the very simple — condition in which we possibly find the sporophyte in some of the alge like spirogyra, vaucheria, and coleochete, there has been a gradual increase in size, specialization of parts, and complexity of structure through the bryo- phytes, pteridophytes, and gymnosperms, up to the highest types of plant structure found in the angiosperms. Not only do we find that these changes have taken place, but we see that, from a condition of complete dependence of the spore-bearing stage on the sexual stage (gametophyte), as we find it in the liverworts and mosses, it first becomes free from the gametophyte in the mem- bers of the fern group, and is here able to lead an independent existence. The sporophyte, then, might be regarded as the modern phase of plant life, since it is that which has become and remains the prominent one in later times. 464. The gametophyte once prominent has become degenerate.—On the other hand we can see that just as remarkable changes have come upon the other phase of plant life, the sexual stage, or gametophyte. ‘There is reason to believe that the gametophyte was the stage of plant life which in early times existed almost to the exclusion of the sporophyte, since the characteristic thallus of the algze is better adapted to an aquatic life than is the spore-bearing state of plants. At least, we now find in the plants of this group as wellas in the liverworts, that the gametophyte is the prominent stage. When we reach the members of the fern group, and the sporophyte becomes independent, we find that the gametophyte is decreasing in size, in the higher members of the pteri- dophytes, the male prothallium consisting of only a few cells, while the fe- male prothallium completes its development still within the spore wall. And in selaginella it is entirely dependent on the sporophyte for nourishment, 465. As we pass through the gymnosperms we find that the condition of things which existed in the bryophytes has been reversed, and the gameto- phyte is now entirely dependent on the sporophyte for its nourishment, the female prothallium not even becoming free from the sporangium, which remains attached to the sporophyte, while the remnant of a male prothallium, during the stage of its growth, receives nourishment from the tissues of the nucellus through which it bores its way to the egg-cell. 466. Inthe angiosperms this gradual degradation of the male and female prothallia has reached a climax in a one-celled male prothallium with two sperm-cells, and in the embryo-sac with no clearly recognizable traces of an archegonium to identify it as a female prothallium, The development of the endosperm subsequent, in most casesyto fertilization, providing nourishment v r 4 ue vs i ME OPH YTE DD SPOROPRYTE. Foliage leaves, Perianth leaves, Spore-bearing leaves with sporangia, | (Sporangia sometimes on shoot.) MORPHOLOG ¥. 238 SS jo pue waadsopua jo sul | "P2295 *snoyo -nu wuitedsopud jo SuOoIsIArp Auewt fq padojaaop ‘wasdsopuy ‘snojonu wuedsopua | Suryeut ‘pasny toyonu avjod om 7, ‘]]99 ulead 10 ‘][9O [eUID}e I oes OAIQUI ‘ovs-oAIGUId JO 9}8}S IvoTONUIUL) ~ 10 1 Aq patoaood ‘snijIonN : ote jedieg “eusC tS eld *s][99 DATJBIOUIS 10 ‘ST[IO [BUAOIeT Oqn} YIM UleIS UsT[OgJ "[[90 dATBIOUIL) ‘[[99 9atyRI039 A, ‘ureis UdT[Og ‘IMO} 10 OM} ATTeNSN fovs UdT[Og ‘yuoWL [TY ; UdWIB}S ioyuy *sjodieo pue suouirys ‘yueld r9y stp] ‘SWUaT, NOWWOD “SNMAdSOIDNV NI ALAHAOLAWVD GNV ALAHdOUOdS AO SHIDOTONOH ONIMOHS ATAVL TREN ES Bula) aj4ydosods pjo jo sjied mou pus siAqdojoures Jo sjuemuror \)\\j the mother cells, and in the divisions of the antherid cell to form the generative Fig. 320. Fig. 321. Second division of Chromosomes uniting Q- nuclei in pollen mother at poles to form the cell of potoper ee nuclei of the four spores. cells or sperm cells, there are always twelve chrom somes so far as has been chromosomes at poles. (After Mottier.) found. In the development of the egg of lilium from the macrospore there are also twelve chromosomes. GAMETOPHYTE AND SPOROPHYTE. 243 When fertilization takes place the number of chromosomes is doubled in the embryo.—In the spermatozoid of osmunda then, as well as in the egg, since these are developed on the game- tophyte, there are twelve chromosomes each. ‘The same is true in the sperm-cell (generative cell) of lilium, and also in the egg- cell. When these nuclei unite, as they do in fertilization, the paternal nucleus with the maternal nucleus, the number of chro- mosomes in the fertilized egg, if we take lium as an example, is twenty-four instead of twelve; the number is doubled. The fertilized egg is the beginning of the sporophyte, as we have seen. Curiously throughout all the divisions of the nucleus in the em- bryonic tissues of the sporophyte, so far as has been determined, up to the formation of the mother cells of the spores, the number of chromosomes is usually the same 475. Reduction of the number of chromosomes in the nu- cleus.—If there were no reduction in the number of chromosomes Fig. 322. Karyokinesis in sporophyte cells of podophyllum (twice the number of chromosomes here that are found in the dividing spore mother cells). ‘at any point in the life cycle of plants, the number would thus become infinitely large. A reduction, however, does take place. 244 MORPHOLOGY. This usually occurs, either in the mother cell of the spores or in the divisions of its nucleus, at the time the spores are formed. In the mother cells a sort of pseudo-reduction is effected by the chromatin band separating into one half the usual number of nu- clear segments. So that in lilium during the first division of the — nucleus of the mother cell the chromatin band divides into twelve segments, instead of twenty-four as it has done throughout the sporophyte stage. Soin podophyllum during the first division in the mother cell it separates into eight instead of into sixteen. Whether a qualitative reduction by transverse division of the spirem band, unaccompanied by a longitudinal splitting, takes place during the first or second karyokinesis is still in doubt. 476. Significance of karyokinesis and reduction.—The pre- cision with which the chromatin substance of the nucleus is di- vided, when in the spirem stage, and later the halves of the chromosomes are distributed to the daughter nuclei, has led to the belief that this substance bears the hereditary qualities of the organism, and that these qualities are thus transmitted with cer- tainty to the offspring. In reduction not only is the original number of chromosomes restored, it is believed by some that there is also a qualitative reduction of the chromatin, 1.e. that each of the four spores possesses different qualitative elements of the chromatin as a result of the reducing division of the nucleus during their formation. The increase in number of chromosomes in the nucleus occurs with the beginning of the sporophyte, and the numerical reduc- tion occurs at the beginning of the gametophyte stage. ‘The full import of karyokinesis and reduction is perhaps not yet known, but there is little doubt that a profound significance is to be attached to these interesting phenomena in plant life. 377. The gametophyte may develop directly from the tissue of the sporophyte.—If portions of the sporophyte of certain of the mosses, as sections of a growing seta, or of the growing capsule, be placed on a moist substratura, under favorable condi- tions some of the external cells will grow directly into protonemal threads. In some of the ferns, as in the sensitive fern (onoclea), Dw Ure Sas AND SPOLOPAYTE. 245 when the fertile leaves are expanding into the sterile ones, proto- nemal outgrowths occur among the aborted sporangia on the leaves of the sporophyte. Similar rudimentary protonemal growths sometimes occur on the leaves of the common brake (pteris) among the sporangia, and some of the rudimentary spo- rangia become changed into the protonema. In some other ferns, as in asplenium(A. filix-foemina, var. clarissima), prothallia are borne among the aborted sporangia, which bear antheridia and archegonia. In these cases the gametophyte develops from the tissue of the sporophyte without the intervention or necessity of the spores. ‘This is apospory. 478. The sporophyte may develop directly from the tissue of the gametophyte.—In some of the ferns, Pteris cretica for example, the embryo fern sporophyte arises directly from the tissue of the prothallium, without the intervention of sexual organs, and in some cases no sexual organs are de- veloped on such prothallia. Sexual organs, then, and the fusion of the spermato- zoid and egg nucleus are not here necessary for the development of the spo- rophyte. ‘This is apfogamy. Apogamy occurs in some Bi ee: other species of ferns, and I RM in in other groups of plants as well, though it is in general a rare occurrence except in certain species, where it may be the general rule. 479. Perhaps there is not a fundamental difference between gametophyte and sporophyte.—This development of sporo- phyte, or leafy-stemmed plant of the fern, from the tissue of the gametophyte is taken by some to indicate that there is not sucha great difference between the gametophyte and sporophyte of plants as Others contend. In accordance with this view it has been . ois @ 5 ede 7" “On A . >» 0% on! TRAE “Gol val ail "7 Ld - Aig i pe % a ‘bal J ees 7 ion ; ; bs hes 1%, bi 246 | MORPHOLOG ¥. suggested that the leafy-stemmed moss plant, as well as the leafy stem of the liverworts, is homologous with the sporophyte or leafy stem of the fern plant; that it arises by budding from the’ protenema; and that the sexual organs are borne then on the sporophyte. | LESSONS ON PLANT FAMILIES. CHAPTER: XXXVI. Seen tiQONSHIPS SHOWN BY FLOWER AND FRUIT. 480. 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 pres- ence of what is called the flower, and that the flower has its culmi- nating series in the spore-bearing members of the plant (stamens and carpels). Aside from the very interesting comparison of the changes which have taken place in passing from the simple and generalized sporophyte of the liverworts and mosses to the com- plex and specialized sporophyte of the higher plants, we should now seek to interpret the various kinds of aggregations of the spore-bearing members, here termed stamens and carpels. In the part of the book which deals with ecology we shall see how the grouping of these members of the plant is an advantage to it in the performance of those functions necessary for fruition. 481. 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 com- pare the flower of trillium with that of a lily for example, or the flower ot dentaria with that of the bitter-cress (cardamine), we shall at once be struck with the similarity in the plan of the 247 248 MORPHOLOGY. flower, and in the number and arrangement of its members. This suggests to us that there may be some kinship, or rela- tionship between the lily and trilhum, and between the bitter- cress 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. As we found in the case of the ferns that the most important characters of rela- tionship among genera and species are found among the spore- bearing leaves, so here the characters pertaining to the stamens and carpels are the principal guide posts, though the floral en- velopes are only second in importance, and leaves also frequently demand attention. Bearing these facts in mind, we can inquire of the plants themselves about some of the attributes of their families and tribes. NOTE FOR REFERENCE. 482. Arrangement of flowers.—The arrangement of the flowers (inflores- cence) 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 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: 483. I. DICHOTOMOUS BRANCHING. occur in the shoots of flowering plants, but it does occur in some of the flower True dichotomy (forking) does not clusters. 484. I]. LATERAL BRANCHING. Monopodial branching.—This occurs where the main shoot continues to Two main types. grow more vigorously than the lateral branches which arise in succes- sion around the main stem. Examples in shoots, horse-chestnut, pines (see chapter on pine). Examples in flower clusters (from indetermi- nate inflorescence). Raceme, lateral axes unbranched, youngest flowers near the terminal portion of long main axis; ex. choke-cherry, currant, 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 sfadix, as in skunk’s cabbage, Indian turnip, ete.; if the spike falls away after maturity of the flower or fruit it is a ca¢- kin or ament (willows, oaks, *etc. ). he LESSONS ON PLANT FAMILIES. 249 Umbel; 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 capitulwm,; the main axis is shortened and broadened, and bears sessile flowers, as in the sunflower, button-bush, etc. Panicle; when the raceme has the lateral axes branched it forms a panicle, as in the oat. When the panicle is flattened it forms a corymb. 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). 1. Monochastum, only one lateral branch is produced from each rela- tive or false axis. flelicoid 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 alternately on op- posite sides of the false axis. 2. Dichastum, each relative, or false, axis produces two branches; often forming a false dichotomy. Examples in shoots are found in the lilac, where the shoot appears to have a dichotomous branch- ing, though it is a false dichotomy. forking cyme, flower cluster of chickweed. 3. Pletochasium, each relative, or false, axis produces more than two branches. 485. The fruit.—The fruit of the angiosperms varies greatly, and often is greatly complicated. When the gyncecium is apfocarpous (that is when the carpels are from the first dvstzmzct) the ripe carpels are separate, and each isa fruit. In the syncarpous gynectzm (when the carpels are united) the fruit is more complicated, and still more so when other parts of the flower than the gyncecium remain united with it in the fruit. fericarp, 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 exdocarf, as in the cherry, peach, etc. Mesocarp,; where there is an intermediate zone it is the mesocarp. I. CAPSULE (dry fruits). The capsule has a dry pericarp which opens (dehisces) at maturity. Whenthecapsule is syzcarpous the carpels may separate along the line of their union with each other longitudinally (septecidal dehiscence); or each carpel may split down the middle line 250 MORPHOLOG Y. (loculictdal dehiscence) as in fruit of iris; or the carpels may open by pores (foricidal dehiscence), as in the poppy. Follicle; 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.). Silique; a capsule of two carpels, which separate at maturity, leaving j the partition wall persistent (toothwort, shepherd’s-purse, and most r others of the mustard family); when short it is a silicle or pouch. Pyxidium or pyxis, the capsule opens with a lid (plantain). II, DRY INDEHISCENT 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 com- | posites. Ill. SCHIZOCARP; a dry, several-loculed fruit, in which the carpels separate from each other at maturity but do not dehisce (umbelliferze, 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. DRUPE, 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. MONOGOTTLEDONsS. Topic I: Monocotyledons with conspicuous petals (Petaloidez). Lesson |. Lity FAmILy (LILIACE#). CLASSIFICATION. 486. Species.—It is not necessary for one to be a botanist in order to recognize, during a stroll in the woods where the tril- lium 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. dividuals they are pinkish when they firstopen. Even with these variations, which are trifling in comparison with the points of close agreement, we recog- nize the individuals to be of the same kind, just as we recognize the corn plants grown from the seed of an ear of =~ Fig. 324. corn as of the same kind. % aerate form), 4 two plants from Individuals of the same one root-stock. kind, in this sense, form a sfeczes. The white wake-robin, then, In some in- is a species. 251 252 | MONOCOT YVYLEDONS. But there are other trilliums which differ greatly from this one. The purple trillium (T. erectum) shown in fig. 324 is very dif- ferent 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. 487. Genus.—Yet if we study all parts of the plant, the per- ennial 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 genus. ‘Trillium, then, isa genus. Briefly the characters of the genus trillium are as follows. 488. Genus trillium.—Perianth of six parts: sepals 3, her- baceous, persistent ; petals colored. Stamens 6 (in two whorls), anthers opening inward. Ovary 3-loculed, 3—6-angled ; stig- mas 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 trillium, but two words are usually employed in speaking of the species, as ‘Trillium grandiflorum, ‘Tl. erectum, etc. 489. Genus erythronium.— The yellow adder-tongue, or dog-tooth violet (Erythronium americanum ), shown in fig. 325, 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 yellow, 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 elongated. The flower stem, or scape, arises from a scaly bulb deep in the soil, and is sheathed by two elliptical-lanceolate, mottled leaves. il PLANT FAMILIES: LILIACEE. 253 The smaller plants have no flower and but one leaf, while the bulb is nearer the surface. Each year new bulbs are form- ed at the end of run- ners from a parent, bulb. These run- \ ners penetrate each \ year deeper in the mae 6lLhe:§6ddeeper bulbs bear the flow- er stems. 490. Genus lili- um.—W hile the lily differs from either the trillium or ery- thronium, yet we recognize a_ rela- tionship when we compare the peri- anth of six colored parts, the 6 stamens, and the 3-sided and Fig. 325. Adder-tongue (erythronium). At left below pistil, and three lon g ae loculed stamens opposite three parts of the perianth. Bulb at the right. ¢ iy em ae em ee ovary. 491. Family liliacee.—The relationship between 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. In the case of these genera the family has been named after the lily, and is the lily family, or Zz/acee. ‘his grouping of plants into species, genera, families, etc., according to characters and relationships is c/assification, or taxonomy. The lily family isa 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 resem- 254 MONOCOTVLEDONS. bling 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. 492. Floral formula.—A formula is sometimes written to show ata glance the general points of agreement in the flower among the members of a family or group. The floral formula of the lily family is written as follows : Calyx 3, Corolla 3, Andrcecium 6(3-3), Gynoecium 3. The formula may be abbreviated thus: Ca3,Co3, A3,G3. ' 493. Adhezion and cohesion.—In the lily family all the sets, or whorls of parts, are free; that is, no floral set is adherent to another. Farther, the parts of the calyx, corolla, and androecium are dstinct. But the parts of the gynoecium are coherent, i.e. the three carpels are united into a single com- pound pistil. In the floral formula this cohesion of the parts of a set is represented by a small bracket over the figure, as in the gyncecium of the lily family. 494. Floral diagram.—The relation of the parts of the flower on the axis are often represented by a diagram, as shown in fig. 326 for the water- plantain family. 495. Note.—In the following lessons on plant families practical exercises may be conducted, employing representative plants in the several important families. Sketches should be made of the form of the leaves, their relation to the stem; stipules; parts of the flower, and other salient and important characters. Floral formulas and diagrams may be made. Brief notes and descriptions, made from the specimens them- selves and not from the books, should be appended. The plants chosen here need not be insisted upon, for Fig. 326. others equally good may be found. The studies Diagram of alisma presented are offered as suggestions to indicate the flower. (Vines.) : ; . : way in which relationships may be detected, and a familiarity with the characters of the families may be obtained. Several of these lessons are chosen among the monocotyledons, to which the lily family also belongs. 496. Water-plantain family (alismaceew).—If we wish to begin with a more simple and primitive family, the water-plantain family will serve the purpose. The common water plantain (Alisma plantago) is an example. It occurs in ditches and muddy shores of. streams and lakes. The flowers are in a loose panicle and are inconspicuous. The leaves resemble those of the PLANT FAMILIES: ORCHIDACE. yj plantain, hence the common name of water-plantain. The flower is regular (all parts of a set are alike), and all the parts are distinct and free. This represents a simpler and more primitive condition than exists in the lily family, where the carpels are united. The floral formula is as follows : Ca3,Co3,A6,G6 — x ; i.e. the parts are in threes or multiples of three. The stamens are in pairs in front of the sepals, and really represent but three sta- mens, since it is believed each one has divided, thus making three pairs. No stamens stand in front of the petals in the water plantain, but in the European genus Auvfemus one stamen in addition stands in front of each sepal. 497. The arrow leaf (genus sagittaria) occurs in wet ground, or on the margins of streamsand ponds. ‘The leaves are very variable, and this seems to depend to some extent on the depth of the water. Several forms of this plant are shown in figs. 493-495. The flowers are moncecious or dicecious. 498. The orchid family (orchidacee).—Among the orchids are found the most striking departures from thé arrangement of the flower which we found in the simpler monocoty- ledons. An example of this is seen in the lady- slipper (cypripedium, shown in fig. 464). The ovary appears to be below the calyx and corolla. This is brought about by the adhesion of the lower part of the calyx to the wall of the ovary. The ovary then is zzferior, while the calyx and corolla are epigynous. The stamens are united with the style Fig. 327. Flower of an orchid (epipactis), the inferior ovary by adhesion, two lateral twisted as in all orchids so as to bring the upper part of the flower below. perfect ones and one upper imperfect one. The stamens are thus gymandrous. 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 polli- nation (see Part III, Pollination). 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. 499. There are thus four striking modifications of the orchid flower: Ist, 256 MONOCOTYLEDONS. the flower is irregular (the parts of a set are different 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 diagrams in fig. 328 show the posi- Fig. 328. Fig. 329. Diagrams of orchid flowers. 4, the usual Diagram of flower type; 4, of cypripedium. (Vines.) of canna. tion of the stamens in two distinct types. The number of orchid species is very large, and the majority are found in tropical countries, 500. Kelated to the orchids are the iris family, in which the stigma is ex- panded into the form of a petal, and the canna family. In the canna the flower is irregular (see figs. 407, 408) and the ovary is inferior, (See chap- ter on pollination, Part I], for description of the canna flower.) CHAPTER XXXVIII. MONOCOTYLEDONS CONCLUDED. Topic Il: Monocotyledons with flowers on a spadix (Spadiciflorz.). 501. Lesson II. The arum family (aracee).—This family is well represented by several plants. The skunk’s cabbage (Spathyema fcetida) illustrated in figs. 455-457 is an interest- ing example. ‘The flowers are closely crowded around a thick stem axis. Such an arrangement of flowers forms a ‘‘ sfadix.’’ The spadix is partly enclosed in a large bract, the ‘‘ spathe.’’ ' The sepals and stamens are four in number, and the pistil has a four-angled style. The corolla is wanting. (See chapter on pollination, Part III, for farther characters of the flower. ) 502. The ‘‘ jack-in-the-pulpit,’’ also called ‘‘ Indian turnip ’’ (Ariszema triphyllum), shown in fig. 458, the water arum (Calla palustris), and the sweet flag (Acorus calamus) are members of this family, as also are the callas and caladiums grown in con- servatories. 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. 503. 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. (For description and illustration of three of these duckweeds, see chapter on nutrition in Part III.) Other related families are the cat-tails and palms. In the iatter the spathe and spadix are of enormous size. ‘The cocoa- nut is the fruit of the cocoanut palm. 257 4 ‘ 258 MONOCOTYLEDONS. Topic III: Monocotyledons with a glume subtending the flower (Glumiflore). 504. 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 readily in gardens, or perhaps in small quantities in greenhouses in order to have material in a fresh condition for study. Or we may have recourse to material preserved in alcohol for the dis- ; : a ; Flower of Fig. 330. Fig. 331. Fig. 332. Fig. 333. oat, show- ial, Spikelet of One glume re- Flower opened Section show- ingthe upper | oat showing moved showing showing two palets, ing ground plan _ paletbehind, ih two glumes. fertile flower. three stamens, and _ of flower. a,axis. and the two Pa two lodicules at base lodicules in t of pistil. front. it section 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 as a panicle. Each little Nis cluster as shown in fig. 330 is what is a spikelet, and consists i usually here of one or two fertile flowers below and one or two ! undeveloped flowers above. We see that there are several es series of overlapping scales. The two lower ones are ‘‘ glumes,’’ PLANT FAMILIES: GRAMINEA. 259 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.’’ 505. Next above this we have the flower, and the most prom- inent part of the flower, as we see, is the short pistil with the two plume-like styles, and the three stamens at fig. 332. But if we are careful in the dissection of the parts we will see, on looking close below the pistil on the side of the flowering glume, that there are two minute scales (fig. 334). These are what are termed the /odicules, considered by \\ some to be merely bracts, by others to representa pe- - rianth, that is two of the sepals, the third sepal hav- ing entirely aborted. Ru- diments of this third sepal Fig. 335. p Diagram ot oat spikelet. G7, glumes; B, palets: are present in some of the 4, abortive flower. g ; B, palets; graminee. 506. To the graminez belong also the wheat, barley, corn, the grasses, etc. The graminez, while belonging to the class monocotyledons, 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. 507. The sedge family (cyperacez). Carex.—As a representative of the sedges a species of the genus carex may be studied. If plants of Carex lupulina are taken from the soil carefully we will find that there is an under- 260 MONOCOTYLEDONS. ground stem or root-stock which each year grows a few inches, forms new attachments by roots to the soil, and thus the plant may spread from year to year. This underground stem, as seen, has only scaly leaves. The upright stems reach a height of two to three feet, and are prominently three-angled, as are most of the species of this large genus. The leaves are three-ranked, and consist of a long sheathing base and a long narrow blade. The flowers, as we see, are clustered at the end of the stem, or sometimes additional ones arise in the axils of the leaves lower down on the stem. The staminate flowers form a slender, short spike, terminat- ing the stem, while the pistil- late flowers form several spikes arising as branches. \ WY) Fig. 336. Flowers of Carex lupulina; staminate flower spike above, three pistillate flower spikes below. Details of pistillate and staminate il flowers shown at the right. The flowers are very much reduced here, and each of the pistillate flowers consists of one pistil which is surrounded by a flask-shaped scale, the ferz- gynium. These perigynia can be distinctly seen upon the spike. At the apex of the perigynia the three styles emerge. Just below each perigynium PLANT FAMILIES: CYPERACE-. 261 is a slender scale, the primary bract, from the axil of which the pistillate flower arises. Fig. 337. Two carex flowers. Fig. 338. Fig. 339. Pistil of carex. Section of pistil. For the study of the flowers one must select material at the time the male flowers are in bloom. In fig. 340 is represented a portion of the staminate spike of Carex laxiflora. As seen here each staminate flower consists of three stamens. These stamens arise in the axil of a bract. Figure 337 represents a portion of the pistillate spike of the same species at the time of flowering. The fact that the parts, or members, of the flower are in threes suggests that there may be some relationship be- tween the carex and the monoco- tyledons already studied, even though each flower has become so reduced in the number of its members. 508. In the bulrush (scirpus), another genus of this family, the flowers are perfect and complete (having all parts of the flower), Fig. 340. Two male flowers of Carex laxiflora. with the parts in threes or some multiple of three, Here there is a more obvious resemblance to the monocotyledenous type. | CHAPTER XXKIX. | | DICOTYLEDONS. Topic IV: Dicotyledons with distinct petals, flowers in catkins, or aments; often degenerate. 509. Lesson IV. The willow family (salicacee).—The wil- lows represent a very interesting group of plants in which the ENA yy \N\ \ x ra Y XQ\ Y » Wy Rd Wy SF — oe w' HA f { Yj) . ZB =o Z = =< a“) hs: PK => 4 N / “a J A\ \ KK SS ame) Q ~ ie 4, / K y | iM = A OF nt hed \ \ Hie ‘ Lif TARY Vy Fig. 34.. Spray of willow leaves, pistillate and staminate catkins (Salix discolor). flowers are greatly reduced. The flowers are crowded on a more or less elongated axis forming a catkin, or ament. ‘The ament is characteristic of several other families also. The willows are dicecious, the male and female catkins being borne 262 PLANT FAMILIES: CUPULIFERA. 263 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’ cat- kins 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. 5910. Lesson V. The oak family (cupulifere).—A small branch of the red oak (Quercus rubra) is illustrated in fig. 342. Fig. 342. 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 in 264 DICOT YLEDONS. 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 expand- ing in the spring, the deli- cate sprays of pendulous male catkins form beauti- ful objects. The petals are wanting in the flower, andthe sepals form a united Branch of the butter- nut. Cluster of female flowers at the top, show- ing the two styles of each pistil, catkins below. 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 Te stamens, variable in number, just reach below its ee margin. ‘The pistillate or female flowers are not ip 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 cup. 511. The beech, chestnut, and oak are members of the oak family. 512. The following additional families among the ament bearers are represented in this country: the birch family (birch, ae mrs), “Mik £0 gv), ‘ .*) Fou) alder), the hazelnut family (hazelnut, hornbeam, etc. ), walnut family (hickory, walnut), and the sweet-gale family (myrica). > CHAPTER XL. DICOTYLEDONS CONTINUED. Topic V: Dicotyledons with distinct petals and hypogynous flowers. URTICIFLORZ. 513. The nettle family (urticaceze).—The nettle family receives its name from the members of one genus in which the stinging nettles are found (urtica). The dicecious nettle (U. dioica) has opposite, petioled leaves, which are ovate, with a heart-shaped base. The margins of the leaves are Fig. 345. Urtica, diagram of male flower. Fig. 344. The dicecious nettle ( Urtica dioica), Fig # P showing leaves, fiower clusters, and below staminate flower at the right Urtica, diagram of and pistillate flower at left. female flower. deeply serrate, and the lower surface is downy. The stems and petioles of the leaves are armed with stinging hairs. 514. The greenish flowers are borne in dense clusters in the form of branched racemes which arise from the axils of the leaves. The staminate 2605 266 DICOTYLEDONS. flowers have four small sepals and four stamens. The fertile flowers (pistil- late) have also four sepals. The pistil has a two-loculed ovary; one of the locules is the smaller, and later disappears, so that the fruit is a one-seeded achene. The parts of the flower are in twos, since the four sepals are in two pairs. 515. Lesson VI. The elm family (ulmacee).—'lhe elm tree belongs to this family. The leaves of our American elm (U]mus americana) are ovate, pointed, deeply serrate, and with an ob- lique base as shown in fig. 347. The narrow stipules which are | ae pa Ky ( Lae big > Ee J )% Jk AN 4 AON Fi Cgpagrll Uf LNG Wj 4 ‘ 7. <7/ Wf, Z. s Ma ‘. va \\\ RAQKQ Fig. 347. Spray of leaves and flowers of the American elm; at the left above is section of flower, next is winged seed (a samara). present when the leaves first come from the bud soon fall away. The flowers are in lateral clusters, which arise from 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. 347 shows the arrangement of the parts, the ovary in the center. ‘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. PLANT FAMILIES: POLYGONIFLORA. 267 POLYGONIFLOR&. 516. Buckwheat family (polygonacez).— Besides the common buckwheat, from which this family gets its name, the knot- weeds are good representatives. Fig. 348 is of the arrow-leaved knot- weed, or arrow- | leaved tear-thumb, so called because of the arrow-shaped leaves and from the __- prominent recurved ' prickles on the four- angled stem. The plant occurs in low grounds often in large clumps, and the slender branch- ed stem is support- ed to some extent by neighboring plants. The flowers are in lke. \ a WW vi AA ‘gi RIES ' : Pa ZASOSP f: SLE re —~ Lf e, ; S~ rah ang Sed —~ 7 s Fig. 348. Polygonum sagittatum, portion Fig. 349. of plant. Spring beauty (Claytonia virginiana). i 268 DICOTYLEDONS. oval clusters borne on slender, long peduncles which arise from the axils of the leaves. Petals are wanting, and the calyx is usually five-parted, with the margin colored. The stamens are mostly eight, and the styles three on the compound ovary. There is a singie seed developed in the ovary which in ripening forms a three-angled achene like a buckwheat grain. The species of dock, and of field, or sheep, sorrel (rumex) also belong to this — family. CURVEMBRY£. 517. The purslane family (portulacacez).—The little spring beauty (Clay- tonia virginica), shown in fig. 349, is a member of this family. It occurs in moist places. The stem arises from a deeply buried tuber, and bears, about midway, two long, narrow, fleshy, thick leaves. The upper part of the stem bears a raceme of pretty rose-colored flowers. The sepals are two. The petals are five in number, and the stamens of the same number are inserted on little claws at the base of the petals. The ovary has a long style, three-cleft at the apex, and in fruit it forms a three-valved pod. The ovule in claytonia and other members of the family is curved, and conse- quently the embryo is curved. 518. In some other related families, like the goosefoot family, the embryo Fig. 350. Curved embryos of Russian thistle (Salsola soda). (Warming.) is also curved. In fig. 350 is shown the embryo of the Russian thistle (Salsola kali), a member of this family. POLYCARPIC. 519. 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 sepals. The number is not definite, varying from _ The vine is somewhat woody. The PLANT FAMILIES: RANUNCULACE. 269 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, oc- curs in marshy or wet places and along the muddy Fig. 351. banks of streams. Caltha er marsh-mari- It is one of the common flowers in April and May. 520. Many of the crowfoots or buttercups (ranunculus) with bright yellow flowers grow in similar situations. The ‘‘ wood anemone’’ (anemone), small Fig. 352. == plants with white flowers, and the rue- Diagram of marsh marigoid ; ; flower. anemone (anemonella), which resembles it, both flower in woods in early spring. The common virgin’s bower (Clematis virginiana) occurs along streams or on hill- sides, climbing over shrubs or fences.’ leaves are opposite, petioled, and are composed 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 Fig. 353. branched, forming a convex mass of ?!28t#™ of aquilegia flower. (Vines ) beautiful whitish flowers. ‘The sepals are colored and the petals 270 DICOTVLEDONS. 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. Q\ | if: \ig2@ aly f° SH Fig. 354. Fig. 355. Clematis virginiana ; below at right are pis- Isopyrum biternatum. tillate and staminate flowers. 521. Some ofthe characters 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 some- times there is but 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 banebefry (actza). PLANT FAMILIES: RANUNCULACE. ey 922. The following families are related to the crowfoot family. The water- lily family, the magnolia family, and the barberry family with the May-apple as an example (see figure 300). In all there is a relationship shown by the separate and _— usually numerous carpels. —_To- gether they form a large group, the polycarpice. Sguirrel-corn (Dicentra canadensis). RHCEADINA. 523. The poppy family (papaveracee). —One of the commonest of the members of this family in the eastern United States is the bloodroot (Sanguinaria canadensis). It occurs in open woods in April and May. It derives its name from the abundant red juice (latex) in the perennial root-stock, The low annual shoot bears usually a Fig. 356. single white flower, and one leaf, some- Bloodroot (sanguinaria). Details ot times more. The floral formula is as fol- fiower at left. ; : : lows: Ca2,Co8(or 10),A 0 .G2., 524. The fumitory family (fumariacew).—To this family belong the singu- lar plants, ‘‘ dutchman’s breeches’’ and ‘‘ squirrel-corn’’ (dicentra), They occur in rich woods in April and May. In the squirrel-corn (D. canaden- sis) there is a slender underground stem which bears here and there, as shown 272 DICOL TV LED ONS: in fig. 357, small yellow tubers resembling grains of corn, The leaves are compound, and the lobes are finely dissected. The flower scape bears a slender raceme of curious pendulous, greenish-white flowers, sometimes tinged with rose color. The details are shown in the figure. The stamens are six in number, arranged in two groups of three (being in two groups they are © diadelphous). 525. Lesson VIII. The mustard family (crucifere ).—This is well represented by the toothwort (dentaria), which we studied in a former chapter. These three families (poppy, fumitory, and mustard) are closely related as shown by the regular flowers, which are usually in twos (dimerous) or in fours (tetramerous ). Fig. 358. Diagram of cruciferous flower. GRUINALES. 527. Lesson IX. The gera- nium family (geraniacee ). —The wild cranesbill has a perennial underground root- stock. From this in the iS iia shispadel leita rer Branch of ince see maculatum) hairy stem. ‘The leaves are showing upper leaves, flowers, and pods. deeply parted into about five wedge-shaped lobes, which are again cut. The peduncles bear several purple flowers (fig. 359). The floral formula is as follows: Ca5,Cos5,A10,G5. ‘lhe wood- sorrel (oxalis), the balsam or jewelweed (impatiens), sometimes called ‘‘ touch-me-not, ? are members of the same family. CHAPTER. Xi DICOTYLEDONS. CONTINUED. Topic VI: Dicotyledons with distinct petals and perigynous or epigynous flowers. Many trees and shrubs, ZESCULINA. 528. Lesson X. The maple family (aceracee).—Figure 360 represents a spray of the leaves and flowers of the sugar maple We | ea, KN \s yy Z os J ip Ss Fig. 360a. 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 five 273 —-———--5 274 DICOTYLEDONS. lobes, which are again notched. The clusters of flowers are pen- dulous on Jong hairy pedicels. The petals are wanting. The Seeds and flowers of sugar maple. At the right is a pistillate flower, in the middle a staminate flower, and at the left the two seeds torming a samara. calyx is bell-shaped and several times lobed, usually five times. The sta- mens are variable in number. The ovary is two-lobed and the style ! deeply forked. ‘The fruit forms \ wo seed: with 9 u pus seeds, oy ith a a aN)” a wing-like expansion as shown NY Wye | \ y) H | in the figure. The flowers of the maple are polygamo-dice- cious, that is the male members (sta- mens ) and female members (carpels ) may be in the same flower or in dif- ferent flowers. SAXIFRAGINA. 529. The saxifrage family (sax- ifragacee ). — The early saxifrage (Saxifraga virginiensis) is a small plant 10o—25cm high, and grows on rocky and dry hillsides (fig. 361). | Fig. 361. The ovate or heart-shaped leaves Early saxifrage (Saxifraga virginiensis). have crenate margins, and are clustered near the ground. The scape bears a branched cluster of flowers at the summit. Floral formula Cas5,Cos5,At1o,G2. PLANT FAMILIES: ROSIFLORZ. 275 ROSIFLORA. 530. 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 important part of the flower. It is most often widened, and either cup-shaped or urn-shaped, or the center is elevated. ‘The carpels are borne in the center 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 recep- tacle, and where this is on the margin of a cup-shaped or urn- shaped receptacle they are said to be perigvnous, that is, around the gyn- cecium., ‘The calyx and corolla are usually in ‘fives. There are three families, as follows. 531. The rose fam- : ; Fig. 362. epee fosacere )-—Tn this Perisynous flower of spirxa (S. lanceolata). (From family there are five eae ae types, represented by the following plants and _ illustrations: ist. In spirea (fig. 362) the receptacle is cup-shaped. There s areive carpels,) united ,at.. the base iis. free. -at,. the... .ends. 2d. In the strawberry the re- ceptacle is conic and bears the carpels (fig. 363). The conic receptacle becomes the fleshy ig. 363. eat —Peceitan as fruit, with the seeds in little pits Flower of Fragaria_vesca_ with columnar receptacle (From Warming.) over the surface. 3d. The rasp- berries, blackberries, etc., represented here by the flowering raspberry (Rubus odoratus), fig. 364. 4th. This is represented by the roses. The receptacle is urn-shaped and constricted : 276 DICOT VLEDONS. toward the upper portion, with the carpels enclosed in’ the base (fig. 3Gaas cup-shaped or bell-shaped and nearly closed at the mouth as in the agrimony. Fig. 364. Fig. 365. Flowering raspberry (Rubus odoratus). Perigynous flower of rosa, with contracted receptacle. (From Warming.) 532. Lesson XII. The almond or plum family (amygdala- cee ).—The members of this family are trees or shrubs. The common choke-cherry (fig. 366) will serve to represent one of the types. The flowers of this species are borne in racemes. The receptacle is cup-shaped. Only one seed in the single carpel (sometimes two carpels) matures as the calyx falls away. The outer portions of the ovary become the fleshy fruit, while the inner portion becomes the hard stone with the seed in the center. Sucha fruit is a drupe. The floral formula for this family is as follows: Cas,Cos5,A15—20 or 30,G1. | 533. Lesson XIII. The apple family (pomacee ).—This fam- ily is represented by the apples, pears, quinces, june-berries, haw- thorns, etc. ‘The members are trees or shrubs. The receptacle is somewhat cup-shaped and hollow. ‘The perianth and stamens 5th. Here the receptacle is — PLANT FAMILIES: POMACE. 207 are at first perigynous, but become epigynous (upon the gynce- cium) by the fusion of the receptacle with the carpels. The floral Fig. 366. Choke-cherry (Prunus virginiana). Leaves, flower raceme, and section of flower at right. formula is thus Ca5,Co5,A10—5—5 or 10-10-5,Gi1-—5. The carpels m- Fig. 367. Flower of pear. (After Warming.) are united, but the styles are free. In fruit the united carpels fuse more or less with the receptacle, 278 DICOTYLEDONS. LEGUMINOSZ. 534. Lesson XIV. The pea family (papilionacee ).—This family is well represented by the common pea. ‘The flower is Fig. 368. Details of pea flower; section of flower, perianth removed to show the diadelphous stamens, one single one, and nine in the other group. (From Warming.) butterfly-like or papelionaceous, and the showy part is made up of the five petals. The petals have received distinct names here because of the position and form in the flower. At fig. 369 the petals are separated s_/f. and shown in their corresponding posi- t tions, and the names are theregiven. ‘The flower is irregular and the parts are in fives, except the carpel, which is single. The calyx is gamosepalous (coherent), the corolla polypetalous (distinct). The ten stamens are in two groups, one separate stamen and nine united; they are thus Fin. ‘sty. diadelphous (two brotherhoods). The _ Corolla of pea. S, stand- ard; lV’, wings; shoots would serve to show us a series of very interesting .¢ “jorse - chestnut. variations in the color, surface markings, outline of the showing budsand leaf _. scars. (A twig with branch, arrangement of the leaves and consequently dif- a terminal bud should ; : : es Melt A Prs§ have been selected for ferent modes of branching, variations in the leaf scars, the this figure.) Ayrou } 304 ECOLOG Y. 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. 571. Growth in thickness of woody stems.—In the growth of woody per-_ ennial shoots, the shoot increases in length each year at the end. The shoot also increases in diameter each GC L, 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 cen- tral one of whitish tissue the cells of which have thin walls. This makes a cylindrical column of tissue through the shoot which we call the pith or medulla. Just outside of this pith is aring 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. 572. 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 Fig. 400. cells with thin and delicate walls, and Three-year-old twig of the American ash, with the cells are richer in protoplasm. sections of each year’s growth showing annual rings. If the section is stained, these cells are apt to show a deeper color than either the wood zone or the bast zone. This is, as we will recollect from our study of the bundle in stems, the cam- bium zone, or the growing part of the older portions of the stem. 573. We may wish to know why these portions of the bundle here form a continuous or apparently a continuous ring in the stem of a woody plant. In the study of the sunflower stem, and also of impatiens, attention was called to the increase in the number of the bundles as the stem increased in age, WINTER BUDS, SHOOTS, ETC. 208 If we happened to examine quite old portions of these stems, we would have observed that a large part or the entire portion of the thin-walled tissue, sep- arating the woody portions of adjacent bundles, had changed to thick-walled or woody tissue, so that there is here in the older portions of the sunflower plant a continuous ring of xylem. This is the case also to some extent with the bast tissue. We already have noticed that the cambium ring in these stems is a continuous one, although the cambium between the bundles of the sunflower plant was not so active as that in the bundle proper. There is, however, a difference between the tissue lying between adjacent bundles and that of the bundle itself. | 574. The bundles in the ash stem and in other woody stems lie very closely side by side, so that at first it might appear as if they were continu- ous. We note, however, that there are radiating lines which extend from the pith out toward the bast. These run between the bundles. These radiat- ing lines are formed by the tissue lying between the bundles becoming squeezed into thin plates, which extend up and down between the bundles. They are termed the medullary rays,* since they radiate from the pith or medulla. ‘These are shown well in a section of an oak stem. 575. Difference in the firmness of the woody ring.—We have already noted that the inner portion of the wood zone contains more and larger ducts than the outer zone, and that in the outer portion of the same zone the woody fibres predominate. The ducts are formed during the early spring growth, and later in the season the development of the fibres predominates. 576. Annual rings in woody stems.—lIf we now cut across a shoot of the ash which is several years old, we will note, as shown in fig. 400, 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. 577. While the thickened walls of all the cells give strength to the wood, the different kinds of cells vary in the percentage of strength which they give. Thus the bast cells which have very thick walls are yet more flexible than the wood fibres, as can be seen if one strips off some of the bark of the basswood tree. Again, the woody fibres give more strength to wood than the same diameter of wood vessels, because they are much more firmly bound together, and the ends are long and tapering, and are spliced over each other where cells below and above meet. In the case of the wood vessels the ends do not taper out so much, or in some cases they meet ad- jacent cells below or above squarely. 578. Wood then which has a large number of wood vessels compared with the fibres, or in which the size of the vessels is great, is not so strong as * Rays, or radiating plates, of tissue appear also in the bundle, 306 ECOLOGY. wood which has a large percentage of fibrous elements, and in which the ducts are comparatively small. Wood with numerous large vessels is also more spongy, and therefore lighter than woods with a close fibrous struc- ture. We should find it an exceedingly interesting study if we made a comparative examination of the growth and strength of the different woods. 579. Phyllotaxy, or arrangement of leaves.—In our study of the organs which utilize carbon for food, and in examining buds on the winter shoots of woody plants, we could not fail to be impressed with some peculiarities in the arrangement of these members on the stem of the plant. Even in the liver- worts and mosses we note that where there is any indication of leaf-like expansions on a central axis there is a general plan of arrangement of these leaf-like structures over successive zones of the axis. 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 casés (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 ex- ample of alternate leaves is presented by the elm (fig. 347), 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 1/2, or the angle of diver- gence of one leaf from the next is 1/2. In the case of the sedges the angle of divergence is less, that is 1/3. By far the larger number of those plants which have the alternate arrangement have the leaves set at an angle of divergence represented by the fraction 2/5. 580. 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, numerous excep- tions 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. 581. Asa result, however, of one arrangement or another we see a beauti- ful adaptation of the plant parts to environment, or the influence which envi- ronment, 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 work- ings of the natural laws in obedience to which the great variety of plants have worked out this adaptation in manifold ways. — a nm $< i _ —__ e CHAPTER XLV. SOL ING. 582. An interesting period in the life of plants is during germination, when the embryo plant comes out of the seed and lifts its leaves and stem above the ground. In the germinating corn plant the young leaves are wrapped around one another and enclose the stem, form- ing a long, slender, pointed sheath, if it may be so called. As this pushes its way through the soil it stands erect, with the pointed end uppermost. Because of its form and the compactness with which the leaves are wrapped together, it easily wedges its way through the soil, with no harm to the tender leaves and stem. 583. The pea seedling comes out of the ground ina very different way. By the swelling of the two thick cotyledons the outer coat of the seed is cast partly off, the root emerges on one side, and the short stem is curved between the cotyledons in the form of an arch. The cotyledons re- main in the soil, while the arched stem, as it elongates, pushes its’ way through the soil. The leaves of Fig. gor. How the garden bean comes out of the grounds 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. 397 308 ECOLOGY. the pea are broader and shorter than the leaves of the corn, and cannot well form a long pointed covering for the stem. If the stem remained straight the friction of the leaves against the soil would tear them while they are so — tender. But lifted out as they are, suspended from the bent stem, they are — unharmed. . q 584. The common garden bean.—The bean also in swelling cracks open the outer coat, the root emerges from underneath the coat in the region of the scar (hilum) on the concave side, while the minute plumule lies curved between the edges of the cotyledons near one end. In the case of the bean, 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 hypo- cotyl 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. gor. The outer coat becomes loosened, and at last slips off com- pletely. ‘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 car- bon conversion. The leaves are at first clasped together, but as the stem becomes erect Fig. 402. Germination of castor-oil bean. they are gradually parted and come to stand out nearly in a horizontal posi- tion. Fig. 401 shows the different positions, and we see that the same pro- vision for the protection of the leaves is afforded as in the case of the pea. 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 germina- tion, and they therefore become smaller, shrivel somewhat, and at last fall off. 585. The castor-oil bean.—'This is not a true bean since it belongs to a very different family of plants (euphorbiacez). In the germination 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 } | | SEEDLINGS. 309 free end and slips off at the stem end. The next coat within, which is also hard and shining black, splits open at the opposite end, that 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 correspond- ing 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 formation of the seed. As the plant becomes older we should note that the fleshy endosperm becomes thinner and thinner, and at 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. 586. How the embryo gets out of a pumpkin seed.—We should not fail to germinate some seeds of a pumpkin or squash. Some of the seeds should Fig. 403. Seedlings of castor-oil bean casting the seed coats, and showing papery remnant of the endosperm. be sown in the soil, and some on damp sphagnum covered with moist paper, or between the folds of a damp cloth, first soaking them for ten to twelve 310 , ECOLOG ¥. hours. The pumpkin seed is the one we have selected for this study. It will be instructive first to examine those which have been germinated in the — Germinating seed of pumpkin, showing how the heel or ‘‘ peg’ catches on the seed coat to cast it off. folds of moist cloth and paper, so that they can readily be observed at all stages, without digging them up from the soil, ee Fig. 40s. Escape of the pumpkin seedling from the seed coats. 587. The root pushes its way out from between the stout seed coats at the smaller end, and then turns downward unless prevented from so 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 will SS 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 more ad- vanced, we will see this heel more distinctly, and also that the stem (hypo- cotyl) is arching out away ~ from the seed coats, Ag SEEDLINGS. 311 the stem arches up its back in this way it pries with the cotyledons against the upper seed coat, 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 between the seed coats. In-the case of seed which are planted deeply in the soil we do not see this con- trivance unless we dig down into the earth. The stem of the seedling arches through the soil, pull- ing 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. 406. If we dig into the soil we will see that this same heel is formed on the stem, and that the seed coats are cast off into the soil, Fig. 406. Pumpkin seedling rising from the ground. Ariszema triphyllum. 588. 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 Fig. 408. Section of germinating embryos of jack-in-the-pulpit, showing young leaves inside the petiole of the coty- Fig. 407. ledon. At the lett cotyledon shown Seedlings of jack-in-the-pul- surrounded by the endosperm in the pit; embryo backing out of the seed; at right endosperm removed to seed. show the club-shaped cotyledon. several large seeds, ‘The seeds are oval inform. Their germination is inter- esting, and illustrates one type of germination of seeds common among ‘. oe ¢ 312 ECOLOG ¥. monocotyledonous plants. If the seed are covered with sand, and kept in a moist place, they will germinate readily. 589. 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 smal! end of the seed. “The dree*end of the embryo now enlarges somewhat, Fig. 409. Fig. 410. Fig. 411. 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. 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. Ps Soowt vee ‘ i‘ yt SEEDLINGS. $13 590. If we make a longisection of the embryo and seed at this time we can _ see how the club-shaped cotyledon is closely surrounded by the endosperm. Through the cotyledon, then, the nourishment from the endosperm is readily passed over to the growing embryo. In the hollow part of the petiole near the bulb can be seen the first leaf. 591. How the first leaf appears.—As the embryo backs out of the seed, it turns downward into the soil, unless the seed is 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. 409. The petiole now gradually straightens up, and as it elongates the leaf expands. 592. 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 trillium, 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 com- pound leaves, a sort of recapitulation of the evolutionary history of the leaf in these forms, CHAPTER XLVI. FURTHER STUDIES ON NUTRITION 593. In our former studies on nutrition we found that such plants as the corn, pea, bean, éetc., obtain their liquid food through the medium of root hairs. The liverworts and mosses obtain theirs largely through similar outgrowths, the rhizoids, while a majority of the algze, being bathed on all sides by water, absorb liquid food through any part of the surface. We will find it instructive to study some of the different ways in which diverse plants obtain their liquid food. 594. Nutrition in lemna.—A water plant is illustrated in fig. 412. This is the common duckweed, Lemna trisulca. It is very peculiar in formand in | Fig. 412. | Fronds of the duckweed (Lemna trisulca). . its mode of growth. Each one of the lateral leaf-like expansions extends out- wards by the elongation of the basal part, which becomes long and slender. | Next, two new lateral expansions are formed on these by prolification from near | . 314 | . t 4 ; | } eee *.. Somme ; pre rs) NUTRITION: WOLFFTA. 315 the base, and thus the plant continues to extend. The plant occurs in ponds and ditches and is sometimes very common and abundant. It floats on the surface of the water. While the flattened part of the plant resembles a leaf it is really the stem, no leaves being present. ‘This expanded green body is usually termed a *: frond.’’ A single rootlet grows out from the under side and is destitute of root hairs. Absorption of nutriment therefore takes place through this rootlet and through the under side me the ‘‘ frond.”’ 595. Spirodela polyr- rhiza.—This is a very curious plant, closely re- wre lated to the lemna and } i\ | sometimes placed in the ji | same genus. It occurs Fig. 413. | / in similar situations, and 5P!rodela polyrrhiza. it | is very readily grown in aquaria. It reminds | one of a little insect as seen in fig. 413. There are several rootlets on the under side of the frond. Absorption of nutriment takes place 596. Nutrition in wolffia.—Perhaps the most curious of these modified water plants is the little wolffia, which contains the smallest specimens of the Fig. 414. Pig. 455, . Fig. 416. Young frond of wolffia Young frond of wolffia Another species of growing out of older one. separating fromolderone. wolffia, the two fronds still connected. flowering plants. Two species of this genus are shown in figs. 414-416. The plant body is reduced to nothing but a rounded or oval green body, which 316 ECOLOG Y. represents the stem. No leaves or roots are present. The plants multiply by ‘‘ prolification,”” the new fronds growing out from a depression on the under side of one end. 597. Nutrition of lichens.—Lichens are very curious plants which grow on rocks, on the trunks and branches of trees, and on the soil. They form leaf-like expansions more or less green in color, or brownish, or gray, or they occur in the form of threads, or small tree-like formations. Sometimes the plant fits so closely to the rock on which it grows that it seems merely to paint the rock a slightly different color, and in the case of many which occur on trees there appears to be to the eye only a very slight discoloration of the bark of the trunk, with here and there the darker colored points where fruit bodies Fig. 417. Frond of lichen (peltigera), showing rhizoids. are formed. ‘The most curious thing about them is, however, that while they form plant bodies of various form, these bodies are of a ‘dual nature” as regards the organisms composing them. The plant bodies, in other words, are formed of two different organisms which, woven together, exist apparently as one. A fungus on the one hand grows around and encloses in the meshes of its mycelium the cells or threads of an alga, as the case may be. If we take one of the leaf-like forms known as peltigera, which grows on | damp soil or on the surfaces of badly decayed logs, we see that the plant body is flattened, thin, crumpled, and irregularly lobed. The color is duil greenish on the upper side, while the under side is white or light gray, and mottled with brown, especially the older portions. Here and there on the under surface are quite long slender blackish strands. These are composed entirely of fungus threads and serve as organs of attachment or holdfasts, and for the purpose of supplying the plant body with mineral sybstances i NUTRITION: LICHENS. 317 which are in solution in the water of the soil. If we make a thin section of the leaf-like portion of a lichen as shown in fig. 418, we shall see that it is composed of a mesh of colorless threads which in certain definite portions contain entangled green cells. The colorless threads are those of the fungus, while the green cells are those of the alga. These green cells of the alga per- form the function of chlorophyll bodies for the dual organism, while the threads of the fungus provide the mineral constituents of plant food. The alga, while it is not killed in the embrace of the fungus, does not reach the per- AD sf wae ae i pa Ea Fig. 418. Lichen (peltigera), section of thallus; dark zone of reunded bodies made up largely of the algal cells. Fungus cells above, and threads beneath and among the algal cells. fect state of development which it attains when not in connection with the fungus. On the other hand the fungus profits more than the alga by this association. It forms fruit bodies, and perfects spores in the special fruit bodies, which are so very distinct in the case of so many of the species of the lichens. These plants have lived for so long a time in this close associa- tion that the fungi are rarely found separate from the algze in nature, but in a number of cases they have been induced to grow in artificial cultures sep- arate from the alga. This fact, and also the fact that the algz are often found to occur separate from the fungus in nature, is regarded by many as an indication that the plant body of the lichens is composed of two distinct or- ganisms, and that the fungus is parasitic on the alga, EE ee ee ee me ce NE (ede Be ot a , oS aed Lee _ f 4 ’ : 318 | ECOLOG Y. 598. Others regard the lichens as autonomous plants, that is, the two or- ganisms have by this long-continued community of existence become unified into an individualized organism, which possesses a habit and mode of life SN a Nt .G i; ni oD Nc Sot aL pe Me re — ° s da CAG ny “, “ ! SF (Be / tf ps - - ve ss, : ip (“Ls i hams -e) —<—— 4 J Figs aes ao se Pe ~ % < = . Gp ‘e “[< m . = ~ . ; a OD ond Of, o4/ ~— = 4 ¢ “4 OAT +" Nees | 7 oy 74, ® 98 = Ft ; a | (7a "aan = : } ) CE ee. ee MAT CRN SEARED & . BTA tee , f= eg . 4 - .. () f/ f LGED MO SSO «if ~S SS —_, “ae Sy CSRS Fig. 4109. Section of fruit body or apothecium of lichen (parmelia), showing asci and spores of the fungus. distinct from that of either of the organisms forming the component parts. This community of existence between two different organisms is called by some mutualism, or symdbtosis. Nitrogen gatherers. 599. How clovers, peas, and other legumes gather nitrogen.—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 nitrogenous 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, espe- cially in poor soil, are almost certain to have en- largements, in the form of nodules, or ‘root tubercles.”’ A root of the common vetch with some of these root tubercles is shown in fig. 420. 600. A fungal or bacterial organism in these root tubercles.__If we cut one of these root tuber- cles open, and mount a small portion of the in- terior in water for examination with the micro- Fig. 420. Root of the common vetch, showing root tubercles, scope, we will find small rod-shaped bodies, NUTRITION: NITROGEN GATHERERS. 319 some of which resemble bacteria, while others are more or less forked into forms like the letter Y, as shown in fig. 421. These bodies are rich in nitrogenous substances, or proteids. They are portions of a minute organism, of a fungus or bacterial nature, which attacks the roots of leguminous plants Fig. 421. Fig. 422. Root-tubercle organism from vetch, old con- Root-tubercle organism from Medicago dition. denticulata. and causes these nodular outgrowths. The organism (Phytomyxa legumi- nosarum) exists in the soil and is widely distributed where legumes grow. 601. 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 the root and down to near the center 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 tubercle”’ increases in size, the fungus threads branch in all directions, entering many cells. The threads are very irregular in form, and from cer- tain enlargements it appears that the rod-like bodies are formed, or the thread later breaks into myriads of these small ‘‘ bacteroids.” 602. 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 sub- stance 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 die 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. 320 | ECOLOGY. Mycorhiza. 603. Many others of the higher plants have fungi associated with their roots. Such roots are mycorhiza. In some genera of the orchids the roots form a compact mass resembling coral growth, as in the coral-root orchid. The curious Indian-pipe (monotropa) has roots which form a large closely branched mass of thickened short roots. In these cases the fungus lives in Fig. 423. Dodder. the cells of the root and some of the threads of the fungus extend to the outside into the soil, and perhaps partly serve as absorbent organs since the: root hairs are very rare or altogether absent on such roots. The Indian- pipe plant possesses no chlorophyll, the fungus in its roots probably assimi- lates carbonaceous food from decaying organic matter in the soil, and gives ying org nM 8 *“ it up to its host. \ eos, 604. Mycorhiza with the fungus 7” the roots are endotropic mycorhiza. The root tubercles of the legumes also belong to this class, Ectotropic my- —————— NUTRITION: MYCORHIZA. 221 corhiza have the fungus on the outside of the roots. These often occur on the roots of the oak, beech, hornbeam, etc., in forests where there is a great deal of humus from the decaying leaves and other vegetation. The young growing roots of the oak, beech, hornbeam, etc., become closely covered with a thick felt of the mycelium, so that no root hairs can develop. The root is also thickened. The fungus serves here as the absorbent organ for the tree. It also acts on the humus, converting it into available plant food and transferring it over to the tree. 605. 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 haustoria in their tissues. By means of these the nutri- ment is absorbed, 606. Carnivorous plants.—Examples of these are the well-known venus fly-trap and the common sundew. | 607. 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 diseases of plants and animals, others cause decay of organic matter, while still others play an important rd6le in converting certain nitrogen compounds into an available form for plant food. They absorb their food through the surface of their body. They may be obtained in abundance for study in infusions of plants or of meats. CHAPTER XLVIL. FURTHER STUDIES ON NUTRITION CONCLUDED. 608. Nutrition of moulds.—Jn our study of mucor, as we have seen, the Fig. 424. Carnation rust on leaf and flowerstem. From photo- graph. growing or vegetative part of the plant, the mycelium, lies within the substratum, which contains the food materials in solution, and the slender threads are _ thus bathed on all sides by them. The mycelium absorbs the watery solutions throughout the entire system of ramifica- tions. | When the upright fruiting threads are devel- oped they derive the materials for their growth directly from the mycelium with which they are in connection. The moulds which grow on de- caying fruit or on other organic matter derive their nutrient materials in the same way. The portion of the mould which we usually see on the surface of these sub- stances is in general the fruit- ing part. The larger part of the mycelium lies hidden within the subtratum. 609. Nutrition of para- sitic fungi.—Certain of the fungi grow on or within the higher plants and derive their food materials from them and at their ex- pense. Such a fungus is called a parasite, and there are a large number 322 NUTRITION: FUNGI. 323 of these plants which are known as farasitic fungi. The plant at whose expense they grow is called the ‘ hos?/.”’ One of these parasitic fungi, which it is quite easy to obtain in green- houses or conservatories during the autumn and winter, is the carnation rust (Uromyces caryophyliinus), since it breaks out in rusty dark brown patches on the leaves and stems of the carnation (see fig. 424). If we make thin cross sections through one of these spots on a leaf, and place them for a epee bain Fig. 425. Several teleutospores, showing the variations in form. 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 sections in water on a glass slip, and stain them with a solution of eosin. Ifthe sections were care- Fig. 426. Cells from the stem of a rusted carnation, showing the intercellular mycelium and haustoria. Object magnified 30 times more than the scale. fully made, and thin, the threads of the mycelium will be seen coursing be- tweengthe cells of the leaf as slender threads. Here and there will be seen short e 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 hawstorium. By means of this haustorium, which is here S$ SP Se ——— a ES BR 324 | ECOLOGY. only a short branch of the mycelium, nutritive substances are taken by the fungus from the protoplasm or cell-sap of the 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. In the case Reeaniar S Ses ag Sa a CES Se aS: GANS oe —— = = SS & = < oe x = 4, =S— oe. SU + ——— Te Aye pate «< a a a yo — —- . . eT ~ Ob Se orate sere . << —— sa ~~? 334 ECOLOGY. to the stem as a collar, or a portion of it remains clinging to the margin of the cap. When the buttons are very young the gills are white, but they soon become pink in color, and Fig. 441. Amanita phalloides; white form, showing pileus, stipe, annulus, and volva. very soon after the veil breaks the gonidia mature, and then the gills are dark brown. 617. Beware of the poisonous mushroom.—The number of species of mushrooms, or toadstools as they are often called, is very great. Besides the common mushroom (Agaricus campes- NUTRITION: MUSHROOMS. 335 tris) there are a large number of other edible species. But one should be very familiar with any species which is gathered for food, unless collected by one who certainly knows what the plant is, since carelessness in this respect sometimes results fatally from eating poisonous ones. 618. A plant very similar in structure to the Agaricus campes- tris is the Lepiota naucina, but the spores are white, and thus the gills are white, except that in age they become a dirty pink. This plant occurs in grassy fields and lawns often along with the Fig. 442. Amanita phalloides; plant turned to one side, after having been placed in a horizontal position, by the directive force of gravity. common mushroom. Great care should be exercised in collect- ing and noting the characters of these plants, for a very deadly poisonous species, the deadly amanita (Amanita phalloides) is perfectly white, has white spores, a ring, and grows usually in wooded places, but also sometimes occurs in the margins of lawns. In this plant the base of the stem is seated in a cup-shaped struc- ture, the volva, shown in fig. 441. One should dig up the stem carefully so as not to tear off this volva if it is present, for with the absence of this structure the plant might easily be mistaken for the lepiota, and serious consequences would result, 330 ECOLOG V. 619. Wood-destroying fungi.—Several thousand different species of mushrooms are known in different countries. A large number of them grow in the soil, deriving their nutriment from decaying organic matter in the soil. Others grow in decaying logs and plant parts. Still quite a large number of the mush- rooms and their relatives are able to grow in the woody portions of the trunks of living trees, causing decay of the trunks. — Still others are parasitic. ‘The wood-destroying fungi not only do great damage in destroying the usefulness of some timber trees for lumber, but they often so weaken the tree trunk or roots of the tree that the trees are broken down during gales. 620. The mycelium enters the tree at wounds in the trunk, limbs, or roots. A limb of a tree broken during a heavy wind, or by falling trees, or by the weight of snow, makes an infection court for the mycelium. A falling tree may bruise and knock off the bark from a sound standing tree and thus open a way for the entrance of the wood-destroying mycelium. The roots of trees are sometimes injured by the wheels of passing vehicles. In some cases I have known fungi to enter through such injuries. Shade trees are also similarly injured as well by the gnawing of animals when allowed to stand near them. Severe pruning of many large limbs of trees often renders them lable to injury from the attacks of wood-destroying fungi, since the small amount of leaf surface remaining is too little for the manufacture of the necessary plant food for repair of the wounds. . GEN = Pig * 5 ae 2 se *, , 4 > = 2 est x a? » x at ~ « oe Woe ‘COLOG sy. a ee Sy ee Sl > s , ne ; het le a ed EARLY SPRING FLOWERS. 349 _ 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. 633. The adder-tongue (erythronium) comes out early in the spring to catch the sunlight gleaming through rifts in the woodland. 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. 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. 634. Indian-turnip.—The ‘‘ Indian-turnip,”’ or ‘‘ jack-in-the- pulpit ’’ (Ariszema triphyllum), loves the cool, shady, rich, allu- vial soil of low grounds, or along streams, or on moist hillsides. A group of the jacks is shown in figure 457 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, and the plants are ‘‘ dimorphic ”’ usually. 635. Female plants.—The large plants usually bear the pistil- late flowers, which are clustered around the base of the spadix, each flower consisting of a single pistil, oval in form, terminat- ing 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 of the several ovules crowd their way to the base of the style near its opening. Even when the stigma is not pollenated the ovary continues to grow in size, and the stigmatic brush remains fresh for a long time. a b» se» Bead = ae |e _ 350 ECOLOGY. 636. Male plants.—Excepting some of the intermediate sizes, one can usually select on sight the male and female plants. The 1 smaller ones which have a spathe are nearly all male and beara 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 compound stamen, the anther-sacs forming rounded lobes at the end of the short consolidated filaments. 637. 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 com- paratively 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 them- selves so in seed bearing that the corm becomes small, and the following season the plant is reduced to a male one. 638. The new roots each year arise from the upper part of the corm. The stored substances 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. _ > ee ee) oe at “oS ~ CHAVIER Te POLLENATION. Origin of heterospory, and the necessity for pollenation. 639. Both kinds of sexual organs on the same prcthallium.—In the ferns, as we have seen, the sexual organs are borne on the prothallium, a small, leaf-like, heart-shaped body growing in moist situations. In a great many cases both kinds of sexual organs are borne on the same prothallium. While it is per- haps not uncommon, in some species, that the egg cell in an archegonium may be fertilized by a spermatozoid from an antheridium on the same pro- thallium, it happens many times that it is fertilized by a spermatozoid from another prothallium. This may be accomplished in several ways. In the first place antheridia are usually found much earlier on the prothallium than are the archegonia. When these antheridia are ripe, the spermatozoids es- cape before the archegonia on the same prothallium are mature. 640. Cross fertilization in monecious prothallia.—By swimming about in the water or drops of moisture which are at times present in these moist situa- tions, these spermatozoids may reach and fertilize an egg which is ripe in an archegonium borne on another and older prothallium. In this way what is termed cross fertilization is brought about nearly as effectually as if the prothailia were dicecious, i.e. if the antheridia and archegonia were all borne on separate prothallia. 641. Tendency toward diecious prothallia.—In other cases some fern pro- thallia bear chiefly archegonia, while others bear only antheridia. In these cases cross fertilization is enforced because of this separation of the sexual organs on different prothallia. These different prothallia, the male and female, are largely due to a difference in food supply, as has been clearly proven by experiment. 642. The two kinds of sexual organs on different prothallia.—In the horse- tails (equisetum) the separation of the sexual organs on different prothallia has become quite constant. Although all the spores are alike, so far as we can determine, some produce small male plants exclusively, while others produce 351 352 . #ECOLOG Y. large female plants, though in some cases the latter bear also antheridia. It | has been found that when the spores are given but little nutriment they form — male prothallia, and the spores supplied with abundant nutriment form female prothallia. 643. Permanent separation of sexes by different amounts of nutriment sup- — plied the spores.—This separation of the sexual organs of different prothallia, which in most of the ferns, and in equisetum, is dependent on the chance supply of nutriment to the germinating spores, is made certain when we come to such plants as isoetes and selaginella. Here certain of the spores receive more nutriment while they are forming than others. In the large sporangia (macrosporangia) only a few of the cells of the spore-producing tissue form spores, the remaining cells being dissolved to nourish the growing macro- spores, which are few in number. In the small sporangia (microsporangia) all the cells of the spore-producing tissue form spores. Consequently each one has a less amount of nutriment, and it is very much smaller, a micro- spore. The sexual nature of the prothallium in selaginella and isoetes, then, is predetermined in the spores while they are forming on the sporophyte. The microspores are to produce male prothallia, while the macrospores are to produce female prothallia. 644. Heterospory.—This production of two kinds of spores by isoetes, selaginella, and some of the other fern plants is eterospory, or such plants are said to be heterosporous. Heterospory, then, so far as we know from liy- ing forms, has originated in the fern group. In all the higher plants, in the gymnosperms and angiosperms, it has been perpetuated, the microspores being represented by the pollen, while the macrospores are represented by the em- bryo sac; the male organ of the gymnosperms and angiosperms being the antherid cell in the pollen or pollen tube, or in some cases perhaps the pollen grain itself, and the female organ in the angiosperms perhaps reduced to the egg cell of the embryo sac. 645. In the pteridophytes water serves as the medium for conveying the sperm cell to the female organ.—TIn the ferns and their allies, as well as in the liverworts and mosses, surface water is a necessary medium through which the generative or sperm cell of the male organ, the spermatozoid, may reach the germ cell of the female organ. The sperm cell is here motile. This is true in a large number of cases in the alge, which are mostly aquatic plants, while in other cases currents of water float the sperm cell to the female organ. 646. In the higher plants a modification of the prothallium is necessary. —As we pass to the gymnosperms and angiosperms, however, where the primitive phase (the gametophyte) of the plants has become dependent solely on the modern phase (the sporophyte) of the plant, surface water no longer serves as the medium through which a motile sperm cell reaches the egg cell to fertilize it- The female prothallium, or macrospore, is, in nearly all PGLLENA TION :"HETEROSPOR Y. 353 Cases, permanently enclosed within the sporangium, so that if there were motile sperm cells on the outside of the ovary, they could never reach the egg to fertilize it. 647. But a modification of the microspore, the pollen tube, enables the sperm cell to reach the egg cell. The tube grows through the nucellus, or first through the tissues of the ovary, deriving nutriment therefrom. 648. But here an important consideration should not escape us. The pol- len grains (microspores) must in nearly all cases first reach the pistil, in order that in the growth of this tube a channel may be formed through which the generative cell can make its way to theegg cell. The pollen passes from the anther locule, then, to the stigma of the ovary. This process is termed pollenation. Pollenation. 649. Self pollenation, or close pollenation.—Perhaps very few of the ad- mirers of the pretty blue violet have ever noticed that there are other flowers than those which appeal to us through the beautiful colors of the petals. How many have observed that the brightly colored flowers of the blue violet rarely ‘‘set fruit’’? Underneath the soil or débris at the foot of the plant are smaller flowers on shorter, curved stalks, which do not open. When the anthers dehisce, they are lying close upon the stigma of the ovary, and the pollen is deposited directly upon the stigma of the same flower. This method of pollenation is se/ffollenation, or close pollenation. These small, closed flowers of the violet have been termed ‘‘ c/erstogamous,’’? because they are pollenated while the flower is closed, and fertilization takes place as a result. But self pollenation takes place in the case of some open flowers. In some cases it takes place by chance, and in other cases by such movements of the stamens, or of the flower at the time of the dehiscence of the pollen, that it is quite certainly deposited upon the stigma of the same flower. 650. Wind pollenation.—The pine is an example of wind pollenated flowers. Since the pollen floats in the air or is carried by the ‘‘ wind,” such flowers are anemophilous. Other anemophilous flowers are found in other conifers, in grasses, sedges, many of the ament-bearing trees, and other dicotyledons. Such plants produce an abundance of pollen and always in the form of ‘¢dust,’’ so that the particles readily separate and are borne on the wind. 651. Pollenation by insects.—A large number of the plants which we have noted as being anemophilous are moncecious or dicecious, i.e. the stamens and pistils are borne in separate flowers. The two kinds of flowers thus formed, the male and the female, are borne either on the same individual (monce- cious) or on different individuals (dicecious). In such cases cross pollenation, 354 | ECOLOG Y. i.e. the pollenation of the pistil of one flower by pollen from another, is sure to take place, if it is pollenated at all. Even in moncecious plants cross pollenation often takes place between flowers of different individuals, so that ny Ny S SS le : Ni Sl INS Ny , \i\) 4 & XY) A "f Fig. 451. Viola cucullata; blue flowers above, cleistogamous flowers smaller and curved below. Section of pistil at_right. more widely different stocks are united in the fertilized egg, and the strain is kept more vigorous than if very close or identical strains were united. 652. Butthere are many flowers in which both stamens and pistils are pres- ent, and yet in which cross pollenation is accomplished through the agency of insects. | 653. Pollenation of the bluet.—In the pretty bluet the stamens and styles of the flowers are of different length as shown in figures 452, 453. The stamens of the long-styled flower.are at about the same level as the stigma of the short-styled flower, while the stamens of the latter are on _ 4 > a é 4 oi * ua aw ee POLLENATION: HETEROSPORY. 355 about the same level as the stigma of the former. What does this interesting relation of the stamens and pistils in the two different flowers mean? As the butterfly thrusts its ‘‘tongue’’ down into the tube of the long-styled flower | Fig. 452. | Dichogamouis flower of the bluet (Houstonia ccerulea), the long-styled form. for the nectar, some of the pollen will be rubbed off and adhere to it. When now the butterfly visits a short-styled flower this pollen will be in the right ° position to be rubbed off onto the stigma of the short style. The positions of : : Fig. 453. Dichogamous flower of bluet (Houstonia coerulea). the short-styled form. the long stamens and long style are such that a similar cross pollenation will be effected. 654. Pollenation of the primrose.—In the primroses, of which we have examples growing in conservatories, that blossom during the winter, we have almost identical examples of the beautiful adaptations for cross polle- nation by insects found in the bluet. The general shape of the corolla is A i terete 356 ECOLOG Y. the same, but the parts of the flower are in fives, instead of in fours as in- the bluet. While the pollen of the short-styled primulas sometimes must fall on the stigma of the same flower, Darwin has found that such pollen is a illisgaBe ea rel iN > "he — Se - \\ Ne « ww’ aN fe ji | { bee s ‘ i} ' i }) |, \ | Fig. 454. Dichogamous flowers of primula. not so potent on the stigma of its own flower as on that of another, an ad- ditional provision which tends to necessitate cross pollenation. In the case of some varieties of pear trees, as the bartlett, it has been found that the flowers remain largely sterile not only to their own pollen, or pollen of the flowers on the same tree, but to all flowers of that variety. However, they become fertile if cross pollenated from a different variety of pear. 655. Pollenation of the skunk’s cabbage.—In many other flowers cross pollenation is brought about through the agency of insects, where there is a difference in time of the maturing of the stamens and pistils of the same flower. The skunk’s cabbage (Sphathyema fcetida), though repulsive on account of its fetid odor, is nevertheless a very interesting plant to study for several reasons. Early in the spring, before the leaves appear, and in many cases as soon as the frost is out of the hard ground, the hooked beak of the ¥ , i 5") i } large fleshy spathe of this plant pushes its way through the soil. If we cut away one side of the spathe as shown in fig. 456 we shall have — — Se = the flowering spadix brought closely to view. In this spadix the pistil of each crowded flower has pushed its style through between the plates of armor formed by the converging ends of the sepals, and stands out alone with the brush-like stigma ready for pollenation, while the stamens of all the flowers of this spadix are yet hidden beneath. The insects which pass from the spadix of one plant'to another will, in crawling over the projecting stigmas, rub off some of the pollen which has been caught while visiting a plant where the stamens are scattering their pollen. In this way cross pollen. ation is brought about. Such flowers, in which the stigma is prepared ou POLLENATION: HETEROSPORY. Fig. 455. Skunk’s cabbage. = 358 (Photograph by the author.) ~* Fig. 456. Proterogyny in skunk’s cabbage. nt a zs POLLENATION : HETEROSPOR Y. Fig. 457. Skunk’s cabbage; upper flowers proterandrous, lower ones proterogynous. 360 | ECOLOG Y. for pollenation before the anthers of the same flower are ripe, are proter- ogynous. 656. Now if we observe the spadix of another plant we may see a condi- tion of things similar to that shown in fig. 457. In the flowers in the upper part of the spadix here the anthers are wedging their way through between 4 the armor-like plates formed by the sepals, while the styles of the same flowers are still beneath, and the stigmas are not ready for pollenation. Such flowers are proterandrous, that is, the anthers are ripe before the stigmas of the same flowers are ready for pollenation. In this spadix the upper flowers are proterandrous, while the lower ones are proterogynous, so that it might happen here that the lower flowers would be pollenated by the pollen falling on them from the stamens of the upper flowers. This would be cross pol- lenation so far as the flowers are concerned, but not so far as the plants are concerned. In some individuals, however, we find all the flowers proter- androus. | 657. Spiders have discovered this curious relation of the flowers and in- sects.—On several different occasions, while studying the adaptations of the flowers of the skunk’s cabbage for cross pollenation, I was interested to find that the spiders long ago had discovered something of the kind, for they spread their nets here to catch the unwary but useful insects. I have not seen the net spread over the opening in the spathe, but it is spread over the spadix within, reaching from tip to tip of either the stigmas, or stamens, or both. Behind the spadix crouches the spider-trapper. The insect crawls over the edge of the spadix, and plunges unsuspectingly into the dimly lighted chamber below, where it becomes entangled in the meshes of the net. Flowers in which the ripening of the anthers and maturing of the stigmas occur at different times are also said to be dichogamous. 658. Pollenation of jack-in-the pulpit.—The jack-in-the-pulpit (Ariszema triphyllum) has made greater advance in the art of enforcing cross pollena- tion. The larger number of plants here are, as we have found, dicecious, the staminate flowers being on the spadix of one plant, while the pistillate flowers are on the spadix of another. In a few plants, however, we find both female and male flowers on the same spadix. 659. The pretty bellflower (Campanula rotundifolia) is dichogamous— and proterandrous (fig. 459). Many of the composites are also dichoga- mous. 660. Pollenation of orchids.—But some of the most marvellous adapta- tions for cross pollenation by insects are found in the orchids, or members of the orchis family. The larger number of the members of this family grow . in the tropics. Many of these in the forests are supported in lofty trees where they are brought near the sunlight, and such are called ‘‘ epiphytes.” A number of species of orchids are distributed in temperate regions, POLLENATION: HETEROSPORY. 301 661. Cypripedium or lady-slipper.—One species of the lady-slipper is shown in fig. 465. The labellum in this genus is shaped like a shoe, as one Fig. 458. A group of jacks. can see by the section of the flower in fig. 465. 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 =a 4 .~———- | | | . ce th OO A A A A EE AN OR 1 a q " “i, ote! ae. ; i Yi 362 } ECOLOGY. 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 Fig. 459. Proterandry in the bell-flower (campanula). Left figure shows the syngencecious stamens surrounding the immature style and stigma. Middle figure shows the immature stigma being pushed through the tube and brushing out the pollen; while in the right-hand figure, after the pollen has disappeared, the lobes of the stigma open out to receive pollen from another flower. the insect, will not touch the stigma of the same flower, but will be in posi- tion to come in contact with the stigma of the next flower visited. | 662. Epipactis.—In epipactis, shown in fig. 466, the action is similar to that of the blue iris. Fig. 460. Kalmia latifolia, showing position of anthers before insect visits, and at the right the scattering of the pollen when disturbed by insects. Middle figure section of flower. 663. In some of the tropical orchids the pollinia are set free when the insect touches a certain part of the flower, and are thrown in such a way that the disk of the pollinium strikes the insect’s head and stands upright. By the time the insect reaches another flower the pollinium has bent downward sufh- POLLENATION: HETEROSPORY. 363 ciently to strike against the stigma when the insect alights on the labellum. In the mountains of North Carolina I have seen a beautiful little orchid, in which, if one touches a certain part of the flower with a lead-pencil or other suitable object, the pollinium is set free suddenly, turns a complete somer- sault in the air, and lands with the disk sticking to the pencil. Many of the Spray of leaves and flowers of cytisus. | orchids grown in conservatories can be used to demonstrate some of these peculiar mechanisms. _ 664. Pollenation of the canna.—In the study of some of the marvellous | adaptations of flowers for cross pollenation one is led to inquire if, after all, plants are not intelligent beings, instead of mere automatons which respond Fig. 462. Flower of cytisus grown in conservatory. Same flower scattering poller. to various sorts of stimuli. No plant has puzzled me so much in this respect as the canna, and any one will be well repaid for a study of recently opened flowers, even though it may be necessary to, rise early in the morning to unravel the mystery, before bees or the wind have irritated the labellum. The canna flower is a bewildering maze of petals and petal-like members. 364 ECOLOGY. The calyx is green, adherent to the ovary, and the limb divides into three, lanceolate lobes. The petals are obovate and spreading, while the stamens have all changed to petal-like members, called staminodia. Only one still shows its stamen origin, since the anther is seen at one side, while the fila- _ ment is expanded laterally and upwards to form the staminodium. \ i; b Ps” } UG th f, F | f) fh / / ? Fig. 463. Spartium, showing the dusting of the pollen through the opening keels on the under side of an insect. (I*'rom Kerner and Oliver.) 665. The ovary has three locules, and the three styles are usually united | into a long, thin, strap-shaped style, as seen in the figure, though in some — cases three, nearly distinct, filamentous styles are present. The end of this | strap-shaped style has a peculiar curve on one side, the outline being some- POLLENATION: HETEROSPORY. 365 times like a long narrow letter S. It is on the end of this style, and along the crest of this curve, that the stigmatic surface lies, so that the pollen 5 ie "i ‘ NG if) 7 i! NAAN \, yy G/ a YP 4 4 yf} Fig. 465. Section of flower of cypripedium. sv, stigma; @, at theleft stamen. The insect enters the labellum at the center, 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. must be deposited on the stigmatic end or margin in order that fertilization may take place. Fig. 464. 666. If we open carefully,canna-flower buds [seopeamm. which are nearly ready to open naturally, by unwrapping the folded petals and staminodia, we will see the anther-bearing Fig. 466. Epipactis with portion of perianth removed to show details. 7, labellum: s¢, stigma; ~ rostellum ; #, pollinium. When the insect approaches the flower its head strikes the disk of the pollinium and pulls the pollinium out. At this time the pollinium stands up out of the way of the stigma. By the timé the insect moves to another flower the pollinia have moved downward so that they are in position tu strike the stigma and leave the pollen. At the right is the head of a bee, with two pollinia (a) attached. , 366 a ECOLOGY. staminodium is so wrapped around the flattened style that the anther lies closely pressed against the face of the style, near the margin opposite that on which the stigma lies. 667. The walls of the anther locules which le against the style become changed to a sticky substance for their entire length, so that they cling firmly to the surface of the style and also to the mass of pollen within the locules. The result is | that when the flower opens, and this staminodium unwraps itself from the embrace of the style, the mass of pollen is left there de- posited, while the empty anther is turned around to one side. 668. Why does the flower de- posit its own pollen on the style ? Some have regarded this as the act. of pollenation, and have concluded, therefore, that cannas are neces-— sarily self pollenated, and that cross pollenation does not take place. But why is there such evi- dent care to deposit the pollen on Fig. 467. the side of the style away from the Canna flowers with the perianth removed to .. : eee ar show the depositing of the pollen of the style by Stigmatic margin: we visit the Sei sean ag cannas some morning, when a number of the flowers have just opened, and the bumblebees are humming around seeking for nectar, we may be able to unlock the secret. 669. We see that in a recently opened canna flower, the petal which directly faces the style in front stands upward quite close to it, so that the flower now is somewhat funnelshaped. This front petal is the Zabe//um, and is the landing place for the bumblebee as he alights on the flower. Here he comes humming along and alights on the labellum with his head so close to the style that it touches it. But just the instant that the bee attempts to crowd down in the flower the labellum suddenly bends downward, as shown in fig. 468. In so doing the head of the bumblebee scrapes against the pollen, bearing some of it off. Now while the bee is sipping the nectar it is too far below the stigma to deposit any pollen on the latter. When the bum- blebee flies to another newly opened flower, as it alights, some of the pollen of the former flower is brushed on the stigma, 670. One can easily demonstrate the sensitiveness of the labellum of | recently opened canna flowers, if the labellum has not already moved down in response to some stimulus. Take a lead-pencil, or a knife blade, or even FI POLLENATION: HETEROSPORY. 307 the finger, and touch the upper surface of the labellum by thrusting it between the latter and the style. The labellum curves quickly downward. 671. Sometimes the bumblebees, after sipping the nectar, will crawl up over the style in a blundering manner. In this way the flower may be pol- Fig. 468. Pollenation of the canna flower by bumblebee. Canna flower. Polien on style, sta- men at left. lenated with its own pollen, which is equivalent to self pollenation. Un- doubtediy self pollenation does take place often in flowers which are adapted, to a greater or less degree, for cross pollenation by insects. CHAPTER tah SEED DISTRIBUTION: 672. Means for dissemination of seeds.—During late summer or autumn a walk in the woods or afield often convinces us of the perfection and variety of means with which plants are provided for the dissemination of their seeds, especially when we discover that several hundred seeds or fruits of different plants 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 beggar-ticks or stick tights, or sometimes called {} YE) tae oe ny) fos Pet iy Fig. 469. Fig. 470. Bur of bidens or bur-marigold, show- Seed pod of tick-treefoil (desmodium); atthe ing barbed seeds. right some of the hooks greatly magnified. bur-marigold (bidens), the tick-treefoil (desmodium), or cockle-bur (xanthi- um), and burdock (arctium). 673. 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. : 368 SEED DISTRIBUTION. 369 674. Many plants possess attractive devices, and offer a substantial _reward, as a price for the distribution of their seeds. Fruits and berries are devoured by birds and other animals ; the seeds within, often passing un- harmed, may be carried long distances. Starchy and albuminous seeds and Fig. 471. Seeds of geum showing the hooklets where the end of the style is kneed. 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 the development of commerce is often responsible for the wide distribution of harmful as well as beneficial species. 675. Other plants are more independent, and mechanisms are employed for violently ejecting 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 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 the seeds are provided with ‘:floats,’”’ ‘‘ parachutes,’’ or winged devices which buoy them bs ——————— Meo ae 370 | ECOL GGA « up as they are whirled along, often 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. As the delicate hairs dry, © Fig. 472. Touch-me-not (Impatiens fulva); side and front view of flower below; above unopened pod, and opening to scatter the seed. they straighten out in a loose spreading tuft, which frees the individual seeds from the compact mass. Here they are caught by currents of air and float off singly or in small clouds. 676. The prickly lettuce.—In late summer or early autumn the seeds of the prickly lettuce (Lactuca scariola) are caught up from the roadsides by the winds, and carried to fields where they are unbidden as well as unwel- come guests. This plant is shown in fig. 473. 677. The wild lettuce.—A related species, the wild lettuce (Lactuca cana- densis) 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 projecting 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 somewhat 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 down- ward, hugging the flower stem below,‘or they fall away. The seeds are SEED DISTRIBUTION. 371 thus exposed. The dark brown achenes stand over the surface of the recep- tacle, each one tipped with the long slender beak of the ovary. The ‘‘ pap- pus,” which is so abundant in many of the plants belonging to the composite family, forms here a pencil-like tuft at the Pi t/ : tip of this long beak. Wier ye As the involucral bracts i yt Wit ms dry and curve down- Q & ey eps dy a a? ward, the pappus also » SX SP Si yay a Nt x, dries, and in doing so “A os > SV fe ty pas bends downward and \ 2 AA IP yi stands outward, brist- ues ling like the spokes of a fairy wheel. Itisan 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 ad- joining 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 ai) WR REN bear upon the achenes 2B 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 Fig. 473. : Lactuca scariola. is thus carefully low- ered first, so that it touches the ground in a position for the end which contains the root of the embryo to come in contact with the soil. 372 ECOLOGY. 678. The milkweed, or silkweed.—The common milkweed, or silkweed (Asclepias cornuti), so abundant in rich grounds, is attractive not only Fig. 474. Milkweed (Asclepias cornuti); dissemination of seed. because of the peculiar pendent flower 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. 679. The large boat-shaped, tapering pods, in late autumn, are packed with oval, flattened, 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 ofeach seed, in drying, bristle out, and thus lift the seeds out of their enclosure, where they are lifted like fairy balloons, buoyent as vapor, they go bearing the precious burden of an embryo plant, which is to take its place as a contest- ant in the battle for existence. 680. The virgin’s bower.— he virgin’s bower (Clematis virginiana), too, clambering over fence and shrub, makes a show of having transformed its SHEL DISFRILOUTION. 373 exquisite white flower clusters into grayish-white puffs, which scatter in the autumn gusts into hundreds of arrow-headed, spiral plumes. The achenes Fig. 475. Seed distribution of virgin’s bower (clematis). have plumose styles, and the spiral form of the plume gives a curious twist to the falling seed (fig. 474). CHAPTER git STRUGGLE FOR OCCUPATION “OF Ean 681. Retention of made soil.—In the struggle of plants for existence, there are a number of species which stand ready to rush 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 Fig. 476. Made soil at mouth of stream, being overgrown by plants. Ithaca, N. Y. 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. 682. Figure 476 is from a photograph taken at the mouth of one of the streams emptying into Cayuga Lake. At the left is 374 > iv Bast aa ee - he OCCUPATION OF LAND. Varatatian an ff eandA Aune 1? Naw. Tercayw Cornet Fig. 477. LDhetacvanh hy Mr idteid Dinshot NT GenlJoniog Gaeta)? 2. eee i | 376 | ECOLOGY. a newly made bank of soil. The species of bidens were here among the first to start in the soft black mud. These are fol- lowed later by grasses, by species of the arrowhead (sagittaria), pickerel-weed (pontederia), etc. The loose soil becomes per- meated by a mass of roots, and year by year becomes more firm. — 683. 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 parti- cles 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 a Se i ey ee ee ‘ : 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. Whena sufficient number obtain a foothold — in such places they retain the sand and prevent the movement | of the dune. 684. Reforestation of lands.—When by the action of fire or wind, or through the agency of man, portions of forests are partially or completely destroyed, a new Set of conditions is pre- sented over these areas. One of the most important is that light. is admitted where before towering trees permitted but a lmited 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 perpetuation of their kind. 685. The earliest to appear are not always the ones to endure the longest, and a battle royal takes place during years for su- premacy. ‘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. 686. Domestic plants protected by man occupy cultivated fields. When cultivation ceases, or the crop is removed, or the fields are neglected, hundreds of species of feral plants, which — ‘Ga a: * < OCCUPATION OF LAND. 377 are constantly springing up, now flourish, bear seed, and take - more or less complete possession of the soil. Impoverished land, abandoned by man, becomes nurtured by nature. Weeds, grass, flowers, spring up in great variety often. Some can thrive but little better than the abandoned crops, while others, peculiarly fitted because of one or another adapted structure or habit, flour- Fig. 478. ary field, in Alabama, growing up to broom-sedge and trees. (Photograph by Prof. P. H. Mell.) ish. Crab-grass and other low-growing plants often cover and protect the soil from the direct rays of the sun, and thus conserve moisture. The clovers which spring up here and there, by the aid of the minute organisms in their roots, gather nitrogen. The melilotus, the passion flower, and other deep-rooted plants reach down to virgin soil and lift up plant food. Each year plant 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. 687. Seeds of trees in the mean time find lodgment. During the first few years of their growth they are protected by the 4 ry 378 | ECOLOGY. herbaceous annuals or perennials. 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 Fig. 479. Abandoned field, Alabama, self reforested by pines. (Photograph by Prof. P. H. Mell.) presented in fig. 478 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. 4709. 688. In New York State many abandoned hillsides are being reforested slowly by nature with the white pine. Fig. 480 rep- resents a group of self-sown pines ranging from three to six OCCUPATION OF LAND. 379 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. Fig. 480. Seif-sown white pine in abandoned orchard; trees 9-20 years old. Near Ithaca. (Photo- graph by the author.) 689. Beauty of old fields—During one season from my win- dow I beheld a marvellously beautiful sight. The scene was located in a portion of an old field on a hillside, in a rapidly erowing part of the city. New buildings had sprung up all 380 | ECOLOG Y. around, and this was waiting sale or improvement. But there were innumerable seeds of a great variety of plants in that vacant lot. They sprang into growth to occupy the land, and a great tangle of luxuriant vegetation was the result. Burdock, tower- ing pigweeds, grasses, beggar-ticks, mullein, St. John’s wort, masses of giant goldenrods, blue-rayed asters, occupied every inch of the ground in a grand medley of kind and color. Through this mass, briers and blackberry bushes pushed their thorny sprays, laying hold on you if you attempted entrance. Children plucked the beautiful flowers, but the flowers they cared not, neither took they thought for the future day when they must give way under the influence of man to stone walls and a plain greensward, so joyous were they in the mere thought of existence and radiant beauty. | a CHAPTER. LI. SOIL FORMATION IN ROCKY REGIONS AND IN MOORS. Lichens. 690. 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. 481). Its pretty, flattened, forking lobes radiate 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 scat- tered over the central area. ‘The thallus clings closely to the rock surface by numerous holdfasts from the under side, which pene- trate 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 disinte- grate the surface of the rock. These disintegrated particles of the rock, mingled with the lichen débris, add to the soil in those localities. 691. 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 the lichens lay hold on them and invest them with fantastic 351 382 ECOLOG ¥. figures of varied color. Disintegrating rock, débris of plants and animals, join to form the virgin soil. Certain of the blue- green algze, as well as some of the mosses, are able to gain a foothold on rocks and assist in this process of soil formation. Fig. 481. 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. 481. These rocks at the time the photograph was taken had no plant-life on them. At other places in the vicinity of this glacier, rocks longer uncov- ered by ice were being covered by plant life. One of the green- land rock lichens are shown in fig. 483. SOIL FORMATION: ROCK DISINTEGRATION. 383 §92. Other plants of rocky regions.—Certain of the higher plants also find means of attachment to the bare rocks of the arctic and mountain regions. ‘The roots penetrate into narrow crevices in the rock, and are able to draw on the water which is Fig. 482. Edge of glacier in Greenland, showing freshly deposited rocks. (From Prof. R. S. Tarr.) elevated by capillarity. Such plants, however, which live on bare rocks, whether in the arctic or in mountain regions, have leaves which enable them to endure long periods of drought. These plants have either succulent leaves like certain of the stone- | § + } 384 ECOLOG Y. crops (sedum), or small thick leaves which are closely overlapped as in the Saxifraga oppositifolia. 693. Few of us, unfortunately, can make the trip to the arctic regions to study these interesting plants which play such an im- portant rdle in the economy of nature. Rocky places, however, Fig. 453. Rock lichen (umbilicaria) from Greenland. or loose stones are common nearer home. Observation of their flora, and the means by which such plants derive nutriment, store moisture, or protect themselves from drought, will well repay out- door excursions. 694. Filling of ponds by plants.—Not only are plants im- poitant agencies in the formation of soil in rocky regions, they WM MOORS. 7 . SOIL FORMATION Fig. 484. rom Atoll moor, showing central pond, elevated ring, and ditch at original shore line. Near Ithaca. (From photograph by the author.) 386 | ECOLOGY. 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 center. Striking examples are some- times 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 study- ing 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 charac- teristic flora appears. | 695. A plant atoll.—In the morainic regions of central New York there are some interesting and striking examples of the ef- fects 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 ev- olution. Fig. 484 is froma 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. 696. 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 asmall, nearly circular, central, pond remains, while entirely around the edge of the earlier basin is a ditch, in many places with from 30-60cm. 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 of the atoll. Ona 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 Ld ww SOIL FORMATION: MOORS. 387 some portions of the outer ring are shrubs one to three meters in height, and occasionally small trees have gained a foothold. 697. Next inside of this belt is a broad, level zone, with Carex filiformis, other carices, grasses, with a few dicotyledons. Inter- mingled are various mosses and much sphagnum. ‘The soil for- mation 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. 698. A floating inner zone.—But the innermost zone, that which borders on the water, is ina large measure made up of the leather-leaf shrub, cassandra, and is quite homogeneous. ‘The dense zone of thisshrub 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 consid- erable 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.’”’ 699. 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 walking to prevent a disagreeable plunge. No resistance is offered to a pole two to three meters long in thrusting it down these holes. Grasses, 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 bot- tom of the older formations. In some places this hes very near ——* “Sob “31q et: * ‘ew ae hy x ECOLOGY: 388 ee — a — sete ae SOIL FORMATION: MOORS. 389 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 outward, so that in time there is a likelihood that the pond will cease to exist, yielding, as it has in other places, the right of possession to the conten- tious vegetation. 700. 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 fills 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. 701. 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. 702. The original pond here was rather oblong, and one end possibly much shallower than the other, so that it filled in much 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 —— ee ee eee — 390 | ECOLOGY. Fig. 486. Spruce in the center nearly all dead. Black spruce swamp. for a number of years when the earlier zones were floating accounts for the circular ele- vation and _ atoll formation. 703. Sara SX - > = d =r ee ee a A EO AE oo Fig. 495. } Sagittaria heterophylla. Often forms a zone just outside of the Sagittaria variabilis. zone does not show. In this zone occurs the curious Vallesneria spiralis, with its corkscrew flower stem, and various potamoge- tons. 715. In the third zone, or the first one which shows in the picture, are great masses of the arrow-leaf (sagittaria) so variable ZONAL DISTRIBUTIO ‘96h “31 N ° = | p — a. n ~ ay ion c S. ie) 3 ° al 42) — pp =] of y nw eo) =] =t ~ n = ° — o 2) > Q pe) < i=) oe » - » nn id WM o o —_ o * wy (royyne oy} Aq ydesdozoyq) (aoyyne oy} Aq ydessojyoyg) 7x9} 99g ‘aye eSnXed wor yaaI1-) [TR 0} souesjuq "LOY “314 HCOLOGY. 4o4 ZONAL DISTRIBUTION OF PLANTS. 405 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 perfoliatum) and joepye-weed (Eupato- Fig. 498. Bank of joepye-weed, Eupatorium purpureum. (Photograph by author.) rium purpureum ), and the blue vervain (Verbena hastata), which occurs on the land. Willows make a compact and distinct sixth zone, while at the right, shown in figure 496 taken alongside this view, the oaks on the hillside beyond form a seventh zone, and still farther back is a zone of white pines, making the eighth. 716. On the banks of a stream emptying into this end of the lake, after pursuing its sinuous course through wooded flats, are living pictures, which present a wealth of beauty in color and harmony of association and environment, charming to behold > 406 ECOLOGY. and delightful to study. At the entrance (figure 497) a broad sweep of typha margins a projecting arm of the land which affords a quiet nook for the repose of mats of green algze, of such sorts Fig. 499. Pontederia, showing leaves and flower spike. as spirogyra, cedogonium, cladophora, etc., floating on the placid water in the foreground. Slender stems of zizania rise like shooting stars among the flags, with scirpus crowding near, while masses of the flowers of thesthoroughwort are sheltered by LONAL DISTRIBUTION OF PLANTS. 407 overhanging willows. On the left, pond-weeds (Potamogeton natans) and the yellow water lily, or spatter-dock (nuphar), Fig. 500. Yellow water lily on jutting arm in stream. (Photograph by the author.) float their leaves and flowers on the quiet water, while the small yellow flowers of the mud plantain (Heteranthera graminifolia) glitter in the sunlight. The arrow-leaf (Sagittaria heterophylla, —E—eEE———— ! 408 ECOLOGY. and variabilis) stand to their necks in the water. The shore near by is lined with sedges. Beyond these on the banks are masses of the white and purple eupatorium, with a goodly sprinkling of the swamp milkweed, its blossoms ablaze with color, while a long bank of willows forms a background of satis- fying green. 717. Rowing up the stream, one passes in review minor for- mations, which exhibit less regularity of distribution and fewer individuals of one species. Pontederia still lingers along near the shore, nearly touching the feet of the purple eupatorium on the bank. The yellow water lly, in groups here and there, points out the shailows, or traces the jutting arms of the shore, which in the distance seem to intercept the course, and the wavelets on the water toss into fantastic figures the mirrored shrubs and trees. In the quiet nooks the sunlight blazes down upon umbels of the blue cornel and the pendent fruit clusters of the trailing nightshade. Banks of goldenrod are massed on one hand, and here and there stand gorgeous clusters of the arrow-leaved polygonum and of the yellow touch-me-not, while every now and then the sickly, blighting form of the cuscuta holds its victims in a crushing embrace. 718. Successions of waves running along the sunny shore throw lights and shadows, which chase each other up the trunks of overhanging trees in the form of rings of sunlight and ‘shade, and then throw a quivering, shimmering light over the foliage. Fallen trees stretch their weather-beaten and bleached trunks over the stream, and their mirrored ghosts dance in the waves at your approach, while the towering elms beyond, smothered in the foliage and embrace of the poison ivy, add to the weird beauty of the scene, Oe — ee a ZONAL DISTRIBUTION OF PLANTS. 409 Fig. sor. Elms in background covered by poison ivy. (Photograph by the authorw CTA Cr 2a PLANT COMMUNITIES: SEASONAL CHANGES. 719. 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 con- ditions 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 predominating 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 sufferance. 720. 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 alge like spirogyra, zygnema ; or other species, as eedogonium, coleo- cheete, 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 algee. Chara also is often an accompaniment 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 community. 721. In field or forest, along glade or glen, on mountain slope or in desert regions, similar relationships of plants in 410 e 45 ~ Spe alaliel Beartae § 4 PLANT COMMUNITIES: SEASONAL CHANGES. 4I!I communities are manifest. ‘The seasons, too, seem to vegetate, blossom, and fruit, for in the same locality there is a succession of different forms, the later ones coming on as the earlier ones disappear. 722. Seasonal succession in plant communities.—The wooded slopes in springtime teem with trillium, dentaria, pod- ophyllum, and other vernal blossoms, while on the steeper hill- sides the early saxifrage is to be found. In the rocky portions Fig. 502. Azalea (Rhododendron nudicaulis). of the glen, which is also 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 with noss 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- ECOLOG ¥. Fig. 503 Walking fern, climbing down a hillside, 412 Cie ee ttre) oa epee Spee ae ae Set ett ese PLANT COMMUNITIES: SEASONAL CHANGES. 413 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 yew (taxus), shaded by the towering hemlock spruces. ‘The ‘‘ walking-fern’’ here, holding fast above, climbs downward by long graceful strides. 723. But the scene shifts, and while these flowers cast their beauty for the season, others put on their glory. ‘The flowering Fig. 504. Spray of kalmia flowers. dogwood spreads its deceptive bracts as a halo around the clus- ters of insignificant flowers. The laurel (kalmia) with its clus- ters of fluted pinkish blossoms is a joy only too brief. Smaller and less pretentious ones abound, like the whortleberries, am- phicarpea, bush-clover (lespedeza), sarsaparilla, and so on. 724. In the autumn the glen is clothed with another robe of beauty. With the fall of the ‘‘sere and yellow leaf,’’ golden- 5 | .* } 1 | : j - | 1 " " AI4 ECOLOGY. rod and aster still linger long in beauty and profusion. When the leaves have fallen the witch-hazel (hamamelis) begins to Fig. 505. Spray of witch-hazel (hamamelis) with flowers ; section of flower below. flower, and the snows begin to come before it has finished spreading its curled yellow petals. 725. The landscape a changing panorama.—lIn our temper- ate 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 mechanism. 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. ‘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. Ina multitude of ways the different shrubs and trees 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 diversification in which the plant from lateral members of the stem forms organs to serve such a variety of purpose under such diametrically opposed environ- mental conditions. - PLANT COMMUNITIES: SEASONAL CHANGES. 415 726. Refoliation of bare forests in spring.—There is a cer- tain charm watching the refoliation of the bare forests, when the cool gray and brown tints are slowly succeeded by the light yel- low-green of the young leaves, which presents to us a warming Fig. 506. Opening buds of hickory. 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 atten- tive minds. A416 ECOLOG Y. 727. The evergreens display a striking contrast of color. The leafy, fan-shaped branches of the hemlock-spruce (tsuga) are Fig. 507. Austrian pine, showing young growth of branches in early spring. 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 A PLANT COMMUNITIES: SEASONAL CHANGES. 417 of a Christmas tree lighted with numerous candles. The numer- ous 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. 728. 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 sub- dued colors, which better protect the living substance from the intense light and heat of midsummer. ‘The physiological pro- cesses 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. 729. 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, here and there the older leaves of certain shrubs lose more or less of the green color and take on livelier tints. With the dis- integration 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. 730. Fall of the leaf.—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 attachment to the stem is preparing to cut loose from the latter by forming what is called aseparative layer of tissue. At this point the cells 418 | ECOLOGY. in a ring around the central vascular bundle grow rapidly so as to unduly strain the central tissue and epidermis, making it brit- tle. In this condition a light putf of wind whirls them away in eddies to the ground. ‘The frosts of autumn assist in the separa- tion 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 same cases the dead leaves may cling for quite a long period to the trees. However 4 ‘SS . ou in the death and fall of the leaves of these deciduous trees and a 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 transpiration sur- face. 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 LVI. ADAPTATION OF PLANTS TO CLIMATE. 731. Some characteristics of desert vegetation.—One of the important factors in plant form and distribution is that of climate, which is modified by varying conditions, as temperature, hu- midity 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. 732. Some of the plants, especially the larger ones, have very succulent 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 proportion- ately 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. 733. 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. 734. In still other cases the leaves and stems are covered with a dense felt of hairs which serves as a cushion to protect them 419 atural size, one third n 5. ) 50 and Fic. Birch trees from Greenl x b ° S O = 420 ° ‘% . ADAPTATION TO CLIMATE. 421 from the direct rays of the sun, and also from the fierce blasts of dry air which frequently sweep over these regions. ‘The hairs are so close, and so interwoven, that the air caught in the inter- stices is not easily displaced, and the leaves are not then subject to the drying effects of the passing winds. 735. 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 (portulacca) 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. 736. 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 inter- woven trichomes so as to wet the epidermis. 737. 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 summits of the northeastern United States, and far northward, has numer- ous 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. 738. Low stature of alpine plants a protection against wind and cold.—Another protection to plants from winds and from the cold in such regions is their low stature. Many of the her- baceous plants have very short stems, and the leaves lie close to Py N = = = =] os fo] Bi = S - e £) N ibe 2) . 1S) =e Ry mS Vv ie) = O E © & wn Z 2) } se WwW 422 ADAPTATION TO CLIMATE. 423 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 508 are shown some birch trees from Greenland, one third natural size, the entire tree being here shown. Similarly figure 509 represents some of the arctic wil- lows, one third natural size. - 739. 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. ‘Transpiration 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 unpro- tected epidermis, transpiration would be in excess of absorption, and the leaves would wither. Cassandra, or leather-leaf, and chiogenes, or creeping snowberry, are other examples of these shrubs growing in cold moors. 740. 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 hairsare so numerous, and so closely mat- ted together, that they can be torn off in the form of a thick woolly cap. we APPENDIX. COLLECTION AND PRESERVATION OF MATERIAL. Spirogyra may be collected in pools where the water is pres- ent 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 ina cool place fairly well lighted. In such places it may be kept several months in good condition. Mucor may be obtained by placing old bread, etc., or horse | dung, in a moist covered vessel. In the course of a week there should be an abundance of the mycelium and gonidia. From this material cultures may be made, if desired, in nutrient gela- tin or nutrient agar. Saprolegnia, or water mould, can be used for a study of pro- toplasm. Collect several dead house flies from window sills of neglected rooms. Immerse them in alcohol, then rinse in water to remove the alcohol. ‘Then throw them in vessels of water containing freshly collected algz from several different places. In the course of a week there should be a tuft of whit- ish threads of the water mould surrounding the fly. Nitella is obtained in rather deep pools or ponds, or in slow- running water, at a depth of one to three feet usually. Stamen hairs or tradescantia can usually be obtained in greenhouses from flower buds just ready to open or just after opening. (Edogonium is often found in floating mats in ponds, or on the margins of slow-running streams, or of lakes. F requently it is attached to other aquatic plants. Fruiting plants can be 425 426 | APPENDIX. detected by certain of the cells being rounded and broader than — others, and some of them at least usually containing the spores, — a single spore nearly or quite filling the large cell, or oogonium. When it cannot be studied fresh it may be preserved in 2% formalin or in 70% alcohol, first placing it successively in 2 5 and 50% alcohol for a few hours. 7 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 as described for cedogonium. Coleochete scutata is not so common as the cedogonium, spirogyra, or vaucheria. But it may be sometimes found with the small circular green disks adhering to rushes, grasses, or other aquatic plants in large ponds or on the margins of lakes. When found it is well to make permanent mounts of material killed in formalin, either in glycerine or glycerine jelly. 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 which ripen in autumn. ‘The affected leaves and stems may be pre- served dry. The powdery mildews are common during summer and au- tumn on a variety of leaves of shrubs, herbs, and trees. They can be recognized by the mildéwed spots, or by the numerous a ee ee ee ee COLLECTION AND PRESERVATION OF MATERIAL. 427 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 23% 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 2% 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 ial i4 i aa va f ht iat { Ay ro 1 i a 428 APPENDIX. 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 mrt with moisture. For study of the prothallia of ferns, spores should be one 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 ptet dophytes desired may be preserved dry and in 70% alcohol. Pines.—The ripe cones should be collected before the seeds COLLECTION AND PRESERVATION OF MATERIAL. 429 scatter, and be preserved dry. Other stages of the development of the female cones should be preserved either in 70% alcohol or in 23% 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.—lIn 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 A30 APPENDIX. 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 msed 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 workhas proceeded for some time, APPARATUS AND GLASSWARE. 431 when more general directions usually answer. ‘The author does not believe it a good plan for the student to have written, minute, directions for preparing the plants and experiments. General directions and specific help where there is difficulty, until the student learns to become somewhat independent, seems to be a better plan. 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. The number of compound microscopes 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. In a 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 ee 432 APPENDIX. 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. Of the foreign patterns the Leitz (furnished by Wm. Krafft, 411 W. sgth St., N. Y.) and the Reichert are gaod, 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 zomm diameter and to—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 tocm * 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. ) 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 tooocc, 1 graduated to 100CC. Funnels, small and medium (6 and tocm in width), Test CCT APPARATUS AND GLASSWARE. A33 tubes. A few petrie dishes. 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 Eimer & Amend, 205-211 3d Ave., N. Y., is fairly good ($2.00). For pot experiments, the ‘‘ Harvard trip-scale,’’ Fairbanks Scale Co. (about $6.00). 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. Paraffin or wax, for sealing joints in setting up transpiration apparatus. Mercury, for restoration of turgidity, and for lifting power of transpiration. Sheet rubber, or prepared vessels for enclosing pots to prevent evaporation of water from surface during transpiration experi- ments. | 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 III. REAGENTS. Glycerine, alcohol of commercial (95%) strength, formalin or formalose of 40% strength, chloral hydrate crystals, iodine crys- tals, eosin crystals, fuchsin crystals, potassium iodide, potassium hydrate, potash alum, 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%, 50%, and 70%, for killing material and bringing it up to 70% for storage. Atte APPENDIX. Formalin. Usually about a 244 is used for storing material, made by taking 974 parts water in a graduate and filling in 2} parts of the 40% formalin. Salt solution 5% ; sugar solution 15% (for osmosis). Iodine solution. Weak—to 300cc distilled water add 2 grams iodide of potassium ; to this add zr gram iodine crys- tals. Strong—use less water. Eosin. Alcoholic solution. Distilled water s5occ, alco- hol 50cc, eosin crystals 4 gram, potash alum 4 grams. ’ Aqueous solution. Distilled water 1oocc, eosin crystals I gram. | Chloral hydrate ; aqueous solution, nearly sat. sol. Schimper’s solution. Chloral hydrate 5 parts, water 2 parts, iodine to make a strong color. STUDENT LIST OF APPARATUS. Several glass slips 3 X 1 inch, and more circle glass covers, thin and ? inch diameter. 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, unruled, 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 dif- ferent 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 sev- ." » . os) 5 Oe oe REFERENCE BOOKS. 435 ‘ eral of them can with profit be consulted by the students also. There are a number of other useful reference books in Ger- man 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. Kerner and Oliver, Natural History of Plants. Blackie & Son, London, 1895. Henry Holt & Co., New York, 1895. Strasburger, Noll, Schenck & Schimper, A Text Book of Bot- any, translated by Porter. The Macmillan Co., New York, 1898. : Vines, Student’s Text Book of Botany. The Macmillan Co., New York, 1895. Atkinson, The Biology of Ferns. The Macmillan Co., New York, 1894. MacDougal, Experimental Plant Physiology. Henry Holt & Co., New York, 1895. Spalding, Introduction to Botany. D. C. Heath & Co., Bos- ton, 1895. Bessey, Essentials of Botany. Henry Holt & Co., New York. Goebel, Outlines of Classification and Special Morphology of Plants. Oxford, Clarenden Press, 1887. _ Warming & Potter, Hand Book of Systematic Botany. Mac- millan & Co., New York, 1895. DeBary, Comparative Morphology and Biology of the Fungi, Mycetozoa, and Bacteria. Oxford, Clarenden Press, 1887. Underwood, Our Native Ferns and their Allies. Henry Holt & Co., New York. 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. Darwin, Insectivorous Plants. _D. Appleton & Co., New York. 4360 APPENDIX. 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. 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., supphes 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. INDEX. Absorption, 13 Aceracee (A-cer-ace-2), 273, 275, 298 Acer saccharinum (A’cer_ sac- cha-ri’num), 275 Adder tongue, formation of flower, 349 Adiantum (A-di-an’tum), 169, 173 Adiantum concinnum, spermato- zoids of, 181; embryo, 184, 185 Adiantum cuneatum, fertiliza- tion, 182; embryo, 186 fEcidiospore (£-cid’i-o-spore), 131 fEcidium (4£-cid’i-um), 132 fEsculine (Es-cu-lin’), 273, 297 Agaricus campestris (A-gar’i- cus cam-pes'tris), 136, 326-331 Agaricus melleus, 338 Aggregatz, 290, 299 Alga, Alge, 2 Alismacee (A-lis-ma’ce-z), 254, 255 Alisma plantago, 254 Amanita phalloides (Am-a-ni’ta phal-loi’des), 334, 335 Almond (family), 276 Amygdalaceze (A-myg-da-la’- ce-z), 276, 295, 298 Anemophilous, 353 Angiosperms, comparative table of, 238 Angiosperms, morphology of, 221-236 Antheridiophores, 145 Antheridium, of vaucheria, 107; cedogonium, IOI, 102; coleo- chete, 112; saprolegnia, 123; erysiphe, 138; liverworts, 141, ea... 340; mosses; -2ho0;./ 61: ferns, 180, 181; sélaginella, 194; isoetes, 198 Antipodal cells, 231, 233 Apogamy, 245 Apogeotropic (Ap-o-ge-ot’ro- pic), 83 Apogeotropism (Ap-o-ge-ot’ro- pism), 83 Apospory, 245 Apple, 276 Aracee (A-ra’ce-), 257, 294, 296 Archegonia (Ar-che-go’ni-a) of liverworts, I41, 142, 155, 156; mosses, 160,. 161% ferns,*; 17b: E31, 182: selaginella, 195; iso- etes,198; gymnosperms, 210,211 Archegoniophore, 147 Archesporium (Ar-che-spor’i- um), 153, 239 Arisema triphyllum (Ar-i-se’ma tri-phyl’/lum), 257; germination of, and..embryo, $11,313; pol- lenation of, 360, 361 Asclepias cornuti (As-clep’i-as cor-nu'ti), dissemination of seed; 372 Ascomycetes (As-co-my-ce’tes), 138, 139 Ascospore, 137-139 Ascus (pl. Asci), 137-139 Ash (American), 304 Aspidium acrostichoides, 165, 172, 177 Aspidium spinulosum, 168 Asplenium bulbiferum, 174, 175, 239 Aster nove-angliz, 290, 291 Atoll, made by plants, 386 Azalea, 4II Bacteria, nutrition of, 321 Bald cypress, 395, 396 Basidiomycetes (Ba-sid-i-o-my- ce’tes), 136, 139 Bast, 44; fibres, 48; parenchyma, 48 Batrachospermum (Ba-tra-cho- sper’mum), 116 437 Sena . i = oa ——— ——— ope, £2) Seg ees mens 438 INDEX. Bean, germination of, 307, 308 Beet, osmose in, 15, 16, 17, 18 Bell flower, 289 Bicornes, 283, 284, 298 Bidens, seed of, 368 Bindweed, 284 Black rust, 129 Black spruce moor, 390 Blasia, 155 Bloodroot, 271 Blue-green alge, 118 Bluet, pollenation of, 354, 355 Borage, 285 Boraginacee (Bor-ag-i-na’ce-z), 285, 299 Buckwheat, 267 Bur marigold, seeds of, 368 Brown alge, 115, 118 Bryony, tendril of, 88 Butomus, 255 Callithamnium, I19 Caltha palustris, 268, 269 Cambium, 44, 48 Campanula, 289; pollenation of, 362 Campanulacee, 289, 299 Campanuline, 28g, 299 Canna, pollenation of, 363-367 Caprifoliacez (Cap-ri-fo-li-a’ ce-z), 288, 296, 299 Carbon conversion, 59, 61, 67, 68; rays of light concerned in, 67 Carbon dioxide, absorption of, 51; loss of P§4 Carbon, food of plants, 59-64 Carex laxiflora, 261 Carex lupulina, 260 Carnation rust, 323, 324 Castor oil bean, germination of, 308, 309 Cattails 257 Cell," Cell sap, 3 Cephalozia (Ceph-a-lo’zi-a), 155 Chetophora (Che-toph’o-ra), 103 Champia, I1g Chiamydospores (Chlam-yd’o- spores), of mucor, 123 Chlorophycee (Chlo-ro-phy’ce- ze), 118 Chlorophyll, 2. 65-69; band, 2; bodies, 66; movement of chlo- rophyll bodies, 68, 69 Chloroplastid, 67 Chloroplasts, 66, 68; formed in, 68 Choke cherry, 270,;2777 Christmas fern, 165-167 Chromatin, 240 Chromatin skein, 241 Chromoplasts, 68 , Chromosomes, 241-243 \ Claytonia virginiana, 267 Cleistogamous, 353, 354 Clematis virginiana, 269, 270: disseminatlon of seed, 372, 373 Closterium, 98 Cosmarium, 98 Club mosses, IgI-195 Cluster cup, 131, 1925a95 Coleochete (Co-le-o-che te), 110— 113 Coleochete scutata, IIO, I12 Coleochete soluta, 112 Columella, of rhizopus, 121, 123 Compositz, 290, 296, 2a9 Conferva, 103 Confervoidee (Confers a 103, 118 Conjugate (Con-ju-ga te), 98, 118 Conjugation, 94, 96 Contorte, 287.° ” Convolvulacee ce-z), 284, 299 Convolvulus (Con-vol’vu-lus), 284, 285 Cortex, 44 Crucifere 295, 297 Cupulifere (Cu-pu-lif’er-z), 263, 294, 296 Curvembryz 268, 297 Cuticularized, 37 Cyanophycee (Cy-an-o-phy’ce- ze), 118 : Cycas, 214-217 a also frontis- piece. ) Cyclosis (Cy-clo’ 'sis), 9 Cyperacez (Cy-per-a’ce-z), 259- 261, 296 Cypress knees, 396 Cypripedium, 361, 365 Cytisus (Cy-ti’sus), scattering of pollen, 363 Cystocarp, 116-119 Cystopteris bulbifera, 174 starch (Con-vol-vu-la’ (Cru-cif’er-z), 272, (Curv-em’'bry-ze), 4 i 5] + . 6 4 ¢ INDEX. 439 Cystopus candidus, haustoria of, 324 Cytoplasm (Cy’to-plasm), 5 Daucus carota, 281 Dentaria, 221, 225, 227 Desert vegetation, characters of, 419 Desmids, 98 Desmodium (Des-mo'di-um), dis- semination of seeds, 368 Diadelphous (Di-a-del’phous), 272 Diageotropism (Di-a-ge-ot’ro- pism), 83 Diaheliotropic (Di-a-he-li-ot’ro- pic), 84, 86 Diaheliotropism (Di-a-he-li-ot - ro-pism), 84, 86 Dicentra canadensis (Di-cen’tra can-a-den’sis), 271 Dichogamous (Di-chog’a-mous), 360 Dicotyledons, 262-293 Diffusion, 13 Dioneza muscipula (Di-o-ne’a mus-cip’u-la), go Dipsacacee (Dip-sa-ca’ce-z), 289, 296, 299 Dipsacales (Dip-sa-ca’les),289,299 Dodder, nutrition of, 321 Dorsiventral, 88 Downy mildews, 128 Drosera (Dros’e-ra), 90 Duck weeds, 314, 315 Ecology (sometimes written eco/- ogy), 300-423 Elaters, 150 Embryo, of angiosperms, 232, 235 Embryo sac, 229-233 Endosperm, 209-211, 234, 235 Epidermal system, 48 Epigynous, 255 Epinastic (Ep-i-nas tic), 86 Epinasty (Ep-i-nas ty), 86 Epipactis, pollenation of, 362, 365 Equisetum arvense, 187-189; gametophyte of, Igo Equisetum hyemale, 189 Erica, 284 Erythronium americanum (Er-y- thro’ni-um), 252, 253; forma- tion of flower, 349 Etiolated plants (E-ti-o-la'ted), 65 Euastrum (Eu-as‘trum), 98 Eupatorium purpureum (Eu-pa- to’ri-um pur-pu’re-um), 405 Evaporation, 35, 36 Evening primrose, 279, 280 Ferns, 165-186; dimorphism of, 340-345 Fertilization, in fucus, II5, 117; cedogonium, 102; peronospora, 127 ; saprolegnia, 125; spiro- gvra, 97; spherotheca, 138; vaucheria, 108; picea, 212; an- giosperms, 231-234; cycas, 217 Fibro-vascular system, 48, IIo Figwort (family), 285 Flagellates, 119 Floridee, I17 Forget-me-not, 286 Fragaria vesca, 275, 276 Frullania, 72, 154, 155 Fucus, I15, 116, 118 Fumariacee (Fu-ma-ri-a’ce-z), 271 Fumitory, 271 Fundamental system, 48 Fungi, 56, 65; classification of, 139; nutrition of, 332-337; res- piration in, 56; wood destroy- ing, 336, 337 Gametangium um), 97 . Gamete (Gam‘ete), 95-97, 107, IO Gametophore (Gam-e’to-phore), 145, 147 Gametophyte (Gam-e’to-phyte), 143, 144, 159, 164, 175, 176, 199; of angiosperms, 228; signifi- cance of, 239-246 (Gam-e-tan’gi- Gamopetalous (Gam-o-pei’a- lous), 284 Gamosepalous (Gam-o-sep’a- lous), 278, 283 Gases, diffusion of, 49-53 Gaylussacia resinosa (Gay-lus- sa’ci-a), 283, 284 Gemme of mucor, 22; of mar- chantia, 153 Gentian, 287 Gentiana crinita, 287 Gentianaceez, 287, 299 & —— " | 4 ‘n94 4 ait tani PTE a ant Si Hid? aed W 5 | bit i haet 4 j Wik | i ati de wi 4 il ' * eo. i] 5) i ae Ty " 4 5 pam * ++ 3 Z a ~ —_ ~ ~ 7 ne Pe — ra =~ =>) ~- SS eS See haps és Sr lt a te as yy engl SS 3 li a OEE LO OL vo ——i ee ee eS a rR 7a S ~~ pe it f ‘} tae i baal | be mee} S “4 Lie Oe Wil || See ae Pee ee SY, ee) ON 442 INDEX. Perigynous, 275 Perisperm 234 Perithecium, 136-138 Peronospora alsinearum (Per-o- nos’po-ra al-sin-e-a’rum), 125, 27. 125 Peronospora calotheca, hausto- ria of, 324 Personate, 285, 299 Petaloidez (Pet-al-oi’de-z), 251, 296 : Pheophycee (Phez-o-phy’ce-z), Lif, até Phloem (Phlo’em), 45, 47, 48 Photosyntax, 61 Photosynthesis, 6i Phycomycetes (Phy-co-my-ce’- tes), 128 Phyllotaxy, 306 Phytophthora infestans (Phy- toph’tho-ra in-fes'tans), 126, 127; Fas ; Picea vulgaris, 212; fertilization in, 212 Pine, new growth, 416 Pine, white, 202-213 Pines, reforestation by, 378, 379 Pinus strobus, 202-220 Piper nigrum endosperm and perisperm of, 235 Plant body, 72, 73; members of, The; teal series, 7A: stem series, 73; Toot, 74 Plant communities, 410 Plasmolysis (Plas-mol’y-sis), 19 Plasmopora viticola (Plas-mop’o- ra vi-ti'co-la), 125, 126, 128 Platycerium alcicorne, 345 Pleurococcus' (Pleu-ro-coc’cus), 118, 1109 Plum (family), 276 Plumule, 308 Podophyllum peltatum, 229-231 ; karyokinesis in, 240-243 Pollen, of pine, 204; of cycas, 215; of trillium, 223 Pollenation, 351-367; of pine, 206, 208 Polycarpice (Pol-y-car’pi-cz) 268, 297 Polygonaceze (Po-lyg-o-na’ce-z), 207, 297 Polygoniflore, 267, 297 Polygonum sagittatum, 267 = ——— ee Polymorphic, 135 Polypetalous, 278 Polypodium vulgare, 170, 239 Polyporus (Pol-yp’o-rus), 338 Pomacee, 276, 295, 298 Pontederia, 406 Poppy (family), 271 Porella, 155 Portulacacee, 268, 297 Potential energy, 67. Powdery mildews, 136 Primrose, 355, 356 Primula, 284; pollenation of, 356 Primulacee, 284, 299 Primuline, 284, 299 Procambium strands, 47 Progeotropism (Pro-ge-ot ro- pism), 82, 83 Promycelium (Pro-my-ce li-um), 134-136 Proterandrous, 360 Proterandry, 362 Proterogynous, 360 Prothallium, of ferns, 176-182; of pine, 209, 210; of cycas, 214, 215; of angiosperms, 228-233 Protococcoidee (Pro-to-coc-coi’- de-z), 118, 119 Protococcus (Pro-to-coc’cus), 118, 119 Protonema (Pro-to-ne’ma), 163, 178, 180 Protoplasm, I-12; movement of, 7—-II Prunus virginiana, 277 Pteridophyta (Pter-i-doph’y-ta), 200, 201 Pteris aquilina, 178 Pteris cretica, 245 Pteris serrulata, spores of, £77; embryo of, 183, 186 Puccinia graminis, 129-136 Pumpkin, roots of, 77, 78 Pumpkin seed, germination of, 309-311 Purslane, 268 Pyrenoid, 2 Pyrolacez, 283, 299 Pyrola elliptica, 283 Quercus rubra, 263 Quillworts, 196-198 Ranunculacee, 268, 294, 297 INDEX. 443 Rattlesnake-weed, 292 Red alge, 116, 119 Red rust, 129 Red-snow plant, 118, Irt9 Reforestation of lands, 376, 379 Respiration, 54-58; intramolecu- lar, 58 Rhabdonia (Rhab-do’ni-a), 117, 11g Rhizoids (Rhi’zoids), 71, 72 Rhizome, of trillium. 22! Rhizomorphic (Rhi-zo-mor’phic), 325 Rhizopus nigricans (Rhi’zo-pus ni’gri-cans), 120-123 Rhododendron nudicaulis, 411 Rhodophycee (Rho-do-phy’ce- =), 170, 119, 139 Rhoeadinez, 271, 297 Rock lichens, 382-384 Root hairs, 24; absorption by, 19, 25, 26; acidity of, 27; corrosive action of, 27 Bee “itessure, 31, 32, 30, 40; periodicity of, 32; variation of, 32 Root tubercles, 318 Rosa, 276 Rosacez, 275, 295, 298 Rose (family), 275 Rosiflore, 275, 298 Rubiales, 288 Rubus odoratus, 275, 276 Russian thistle, 268 Rusts, 129 Sac fungi, 136-138 Sagittaria, 255 Sagittaria heterophylla, 402-404 Sagittaria variabilis, 400, 404 Salicacez, 262, 294, 296 Salsola soda, 268 Sand dunes, vegetation of, 376 Sanguinaria canadensis, 271 Saprolegnia, 123-126 Saxifraga virginiensis, 274 Saxifragacez, 274, 298 Saxifraginz, 274, 298 Scorophulariacee, 285. 299 Seeds, distribution of, 368, 373 Selaginella, 193-195, 199-201 Sensitive fern, dimorphism of, 340-346 Sensitive plants, 89, go ‘ Silkweed, dissemination of seeds, 372 Silphium laciniatum, 88 Siphonee (Si-pho’ne-z), tog, 118 Skunk’s cabbage, 356, 357 Soil formation, 381-388 Solanacez, 285, 299 Sorus, of ferns, 166, 170, 173 Spadiciflore, 257, 296 Spadix, 257 Spartium, scattering of pollen, 364 Spathe, 257 Spathyema foetida, 257 Spectrum, bands in, 67; absorp- tion bands of, 67 Spermagonia, 132 Spermatia, 132 Spermatozoids in gymnosperms, 216-219 Sperm cells, 146 Spherella nivalis ni-va'lis), 118 Spherotheca 138 Sphagnum in moors, 385-394 ; Structure of leaves, 394 Spiderwort, II Spirodela polyrrhiza, 315 Spirogyra, 2, 93-98 Sporangium, of ferns, 167-175 spores, of riccia, 143; of ferns, 169-172 ; of equisetum, 188 Sporidium, 134, 136 SpMrIcarp, Tis, 173 Sporogonium (Spor-o-go’ni-um) of. riccia;. 42: of amarchantia, 149, 150; of foliose liverworts, 155-157; of mosses, 161, 162 Sporophyte (Spor’o-phyte), 143, 144, 150, 152, 156, 157, 159, 164, 175, 182, 199; of angiosperms, 228 ; significance of, 239-246 Squirrel corn, 271 Staghorn fern, 345 Starch, 59; test for, 59, 60; trans- location of, 61; where found, 60, 61, 63 Starch grains, form of, 63 Staurastrum (Stau-ras’trum), 98 Sterigma, 134 Stoma (pl. Stom’a-ta), 38 ; action of, 39; demonstration of, 41 Strobilus, 192 (Sphe-rel’la (Sphez-ro-the’ca), ; } ( - - { | | a : ms | i} { a} ii! : : 1} j wy “ } | ti i ae | / Ab. 7 / H | i BE 7 | | Sy : a] ; \) } i : i | “~ - \ 5 Ue ‘ : : hil } An ini Ab iat 4 j 4 1 } i 47 an | r ri #) Ja .) ¥ su | ; | eb ) } \ | a : f } 4 if wa ¥ , F f : | ¥ ; J j . - ? j Pint ab i aa} | ; . 4 ‘a > it | 2, 4 4 | ‘ ; ip r h " ' My Bi ‘ 4 wie ¥ } ‘ ial > e - A44 | INDEX. Sundew, go Symbiosis, 318 Sympetale, 283, 298 Synergids (Syn-er’gids), 231, 233 Taxodium distichum, 395 Deasel;' 286 Teleutospore, 130, 135 Temperature, 9gI, 92 Tensions, tissue, 29, 30 Tetraspores, I17 ) Tissues, synopsis of, 48 Touch-me-not, dissemination of seed, 3'70 Transpiration, 33-41 Trichomes, 48 Trillium erectum, 251 Trillium grandiflorum, 221-224; formation of flower, 347, 348 Tubiflore, 284, 299 Turgescence, 14, 28 Turgescent, I5 Turgid, 15 Turgidity, 28 ; restoration of, 28 Twin flower, 289 Ulmacee, 266, 294, 297 Umbelliflore, 281, 298 Uncinula, 136, 138 Unifolium, 254 Uredinez(U-re-din'e-z), 129-136, 139 Uredospore, 131, 135 Uromyces caryophyllinus, 323 Urtica, 265 Urticacez, 265, 297 Urticiflorz, 265, 297 Vascular bundle, 43; structure of, 44-47 Vaucheria, 105-109 Vaucheria geminata, 108 Vaucheria sessilis, 106-107 Vessels, 45, 46 Vetch, root tubercles of, 318, 319 | Vicia sativa, dissemination of seed, 369 | Viola cucullata, 354 Violet, endosperm and embryo, 235; pollenation of, 353, 354 Virgin’s bower, 269, 270; dis- semination of seed, 372, 373 Volva, 334, 335 Wake robin, 221 Walking fern, 173, 413 Water moulds, 123-126 Water plantain, 254 Water vapor, 34 Wheat rust, 129 Whortleberry, 283 Wild carrot, 281, 282 Willow, 262 Witch hazel, 414 Wolffia, 315 Wood fibres, 48; parenchyma, 48 Xanthidium, 98 Xylem, 44, 45, 47, 48 Yellow water lily, 407 Zamia, 219 Zamia integrifolia, 216 Zonal distribution of plants, 400-408 Zoogonidium (Zo-o-go-nid’i-um), TOI, 102, 105, 106 Zoospores, IOI, 103, een eae Zygnema (Zyg-ne’ma), 98 Zygomorphic, 289 Zygospore (Zy’go-spore), 2, 95. 97, 98, 122 Zygote (Zy’gote), 95, 122 = P ‘ SS _— 4 — Tape ae — — a - —— a hee eer a ee cme — — ee —— SS SE Te rar i a ne atl ———— : . er eee —— ~ ¢ ad 2 a gen = - ~ — —— : eee _ —— ———— -_ 2 7 ——+ ew =x = — — —- July, 1898. 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Cloth. $15.00 ze. ams gE ne « ag me Se - Ee 5 PED Be The Nation: *“*The author evidently planned at the outset to take every attractive oe ome ee SS ae | been attained. He has succeeded in constructing a popular work on the phenomena of a vegetation which is practically without anyrival. The German edition has been accepted . from the first as a useful treatise for the instruction of the public 3 in fact, some of its illus- trations have been taken bodily from the volumes by museum curators, to enrich exhibi- ehh i tion cases designed for the people. With two exceptions, the full-page colored plates Mal de leave little to be desired, and might well find a place in every public museum in which 5) aa ae botany hasa share. Most of the minor engravingsare unexceptionable. They are clear, aa and almost wholly free from distracting details which render worthless so many iflustra- tions in popular works on natural history. Professor Kerner’s style in German is seldom aah reature of plants of all grades, and place these attractive features in the very best light. wal For this purpose he has skillfully employed a brilliant style of exposition, and he has not tii a | hesitated to use illustrationsin black and in color with the freest hand. The purpose has i ; ~ 7 RRR A eee TT bial obscure—it is what one might fairly call easy reading; but itis no disparagement to him hia and his style tostate that the translation is clearer than the original throughout. . . In the . first two issues the author was engaged chiefly with thestudy of the structure of the plant, } Hi and its adaptation to itssurroundings. In thisconcluding volume he considers the plant Ke NI from the point of view of its relation to others. Therefore he begins witha full and ab- rm, ae ait sorbingly interesting account of reproduction in the vegetable kingdom, and then passes to x) an examination of species. . . With this book, there is no excuse for even busy people to fi ae be ignorant of how the other half, the plant-half, lives.” ; al. Atal Botanical Gazette: ‘‘ Kerner’s work in English will do much toward bringing modern Ve Phin Bal botany before the intelligent public. Weneed more of this kind of teaching that will ( Ha Od bring those not professionally interested in botany to some realization of itsscope and . : eat @ great interest.” Professor J. E. Humphrey: “tought to sell largely here to colleges and public libra= ries, as well as to individuals, and [ can heartily commend it.’ Hs 8 John M. Macfarlane, Professor in University of Pennsylvania; “It is a work that a PAPDUIR! # deserves a wide circulation.”’ aL —« Professor John M. Coulter in The Dial: ‘* It is such books as this that will bring » . ty botany fairly before the public asa subject of absorbing interest ; that will illuminate the be a botanical lecture-room ; that will convert the Gradgrind of our modern laboratory into a f wee student of nature.” . New York Times: ‘‘ A magnificent work, with its careful text and superb illustrations. iy | The whole processof plant life is explained, and all the wonders of it.” | The Critic: ‘‘In wonderfully accurate but easily comprehended descriptions, it opens ei ; to the ordinary reader the results of botanical research down to the present time.”’ ti The Outlook: ‘*. . . For the first time we have in the English languagea great work , . upon the living plant, profound, in a sense exhaustive, thoroughly reliable, but in language Lhe Wa simple and beautiful enough to attract a child. . . The platesare most of them of unusual . beauty. 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