AN N: SN le \ Sn “\ Wi a na il ay ty! a) ‘ RN A | ih " i d | f h G cy i/ Hf , a ci fi il, haat - ay fe nw ‘ iN NN Mi ee fou Hi / iy if i iM Ul K A BRAZILIAN FOREST INTERIOR, WITH AIR-PLANTS AND LIANAS. HLEMENTS OF BOTANY BY J. Y. BERGEN, A.M. INSTRUCTOR IN BIOLOGY, ENGLISH HIGH SCHOOL, BOSTON LIBRARY NEW YORK BOTANICAL GARDEN Boston, U.S.A., anp LonDOoN PUBLISHED BY GINN & COMPANY 1896 * COPYRIGHT, 1896, BY J. Y. BERGEN ALL RIGHTS RESERVED LIBRARY NEW YORK BOTANICAL, GARDEN ‘PREFACE. oe ‘Tue present text-book is, for the most part, an expansion of the manuscript notes which have for some years formed _ the basis of the botany-teaching in the Boston English High School. These notes were drawn up by Mr. Samuel F. Tower and the author, for the purpose of establishing what seemed to them a suitable half-year course in botany for pupils of the entering class.in that school. ‘It will be found that this book differs from most American text-books designed for use in secondary schools, in endeavor- ing to combine in one volume the simplest possible directions for laboratory work with an outline of vegetable anatomy and physiology, and a brief statement of the principles of botani- eal classification. An account of the functions of the tissues or organs described usually follows as closely as may be the account of the parts in question. The attempt is made to discuss* plants dynamically rather than statically, to view them as contestants in the struggle for existence, and to con- sider some of the conditions of success and failure in the vegetable world. While the determination of species by means of an artifical key is illustrated, preparation for this hee is by no means the main object or even a principal ae | sre) 4 ‘" 2 end which the author has had in view. The tendency of botany-teaching seems to be more and more away from the old ideal of enabling one’s pupils to run down a species as expeditiously as possible, and teaching them how to preserve a properly ticketed memento of the chase. lv PREFACE. The illustrations drawn from nature, or redrawn expressly for this book, are mostly by Orville P. Williams or Francis M. West, recent graduates of the English High School. The woodeut of Monotropa is from a photograph kindly loaned for the purpose by its maker, Rev. R. 8. Morison. Large numbers of illustrations have been reproduced from the fol- lowing works, which are named in about the order of the extent to which they have been drawn upon: Le Maout and Decaisne’s Traité Général de Botanique. Thomé’s Structural and Physiological Botany. Tschirch’s Angewandte Pflanzenanatomie. Strasburger, Noll, Schenk, and Schimper’s Lehrbuch der Botanik. Kerner’s Pflanzenleben. Figuier’s Vegetable World. Behrens’s Tezt-book of General Botany. Sachs’s Text-book of Botany. The author is to a less extent indebted for cuts to the works of Brown, Carpenter, Darwin, Lindley, Lubbock, Potonie, Strasburger, Hartig, Host, Kny, Detmer, Martius, Baillon, and others. For most of the subject-matter of this book —though not for the order and mode of treatment — the writer is of course indebted to a multitude of sources, only a very few of which are indicated in the subjoined bibliography. Personal assist- ance has been freely rendered him by Prof. George L. Goodale, Dr. Benjamin L. Robinson, Curator of the Gray Herbarium, and Mr. A. B. Seymour of the Cryptogamic Herbarium of Harvard University. Prof. George J. Pierce of Indiana State University has given valuable aid in regard to some physiological questions. Prof. William F. Ganong of Smith College has done so much for the book that if it should prove useful its value will be largely due to his suggestive criticisms. Thanks are due for the careful proof-reading of PREFACE. Vv Prof. George G. Groff of Bucknell University, Lewisburg, Pa., Miss Anna A. Schryver of the Michigan State Normal School, Ypsilanti, Mr. Hermann von Schrenk of the St. Louis Manual Training School, and Mr. Marcus L. Glazer of the St. Cloud., Minn., High School. Part II consists of a very brief key to some of the com- moner orders of Phanerogams and descriptions of the char- acteristics of these orders with a few genera and species under each. The key is adapted (by permission) from the one in use in the elementary course in botany in Harvard University, and the descriptions were compiled by the author from the most accessible recent floras of the northern United States east of the hundredth parallel. The attempt has been made to simplify the language and condense the descriptions, but not so much as to make them hopelessly bald and unread- able. The plants chosen to constitute this greatly abbreviated flora are those which bloom during some part of the latter half of the ordinary school year, and which have a rather wide territorial range. Enough forms have been described to afford ample drill in the determination of species. Gray’s Manual of Botany or Field, Forest and Garden Botany will of course be employed by the student who wishes to become © familiar with the flora of the region here touched upon. Those species which occur in the north-eastern United States only as cultivated plants are so designated, but it has not seemed best to take the necessary space to assign precise ranges or habitats to the native or introduced plants here described. a 5 “ON TH NE. Parr I. CHAP EPER) 1. PAGES * Tue SEED AND 1TS GERMINATION ‘. . : 2 As ; 4-11 CHAPTER I. THe Parts OF THE SEEDLING; ITS DEVELOPMENT . é . eee CHAPTER III. STORAGE OF NOURISHMENT IN THE SEED . : : : : 18-25 CHAPTER IV. Roots 1 : r F : E ‘ ‘ é : : 26-37 CHAPTER V. STEMS : ; F : ‘ : ; : ; : oo-oL CHAPTER VI. STRUCTURE OF THE STEM . ‘ : ; : : : é 52-66 CHAPTER VII. Livinc Parts OF THE STEM. WorK OF THE STEM : ; 67-76 CHAPTER. VII. Bups . 77-84 CHAPTER IX. LEAVES d : : 85-93 CHAPTER X. Lear ARRANGEMENT FOR EXposuRE TO SuN AND AIR. MOve- MENTS OF LEAVES AND SHOOTS . ; c ‘ ? . 94-101 CHAPTER. XI. LEAVES OF PECULIAR ForMs AND UsEs . : : 5 . 102-107 viii CONTENTS. CHAPTER XII. PAGES Minute Srructure or Leaves; Funcrions oF LEAVES . . 108-125 “CHAPTER XIII. a * PROTOPLASM AND ITS PROPERTIES ) ; 5 5 5 . 126-146 ‘CHAPTER XIV. ‘ INELQRESCENCE, OR ARRANGEMENT OF FLOWERS ON THE Stem 131-136 CHAPTER XV. tg Tue Stupy oF TypicAL FLOWERS . y ; : ? ; lola CHARTER Savi. PLAN AND STRUCTURE OF THE FLOWER AND ITS ORGANS . 142-161 CHAPTER XVII. True Nature OF FLORAL ORGANS; DETAILS OF THEIR STRUC- TURE . : : : : : f , P ! . 152-157 CHAPTER XVIII. FERTILIZATION ; TRANSFER OF POLLEN; PROTECTION OF POLLEN 158-181 CHAPTER XIX. THE Stupy oF TypicaL FrRoITS : . 5 : : . 182-184 CHAR TE Rc Tue FRvIT. ; : ; : : : : E p . 185-196 CHAPTER XXI. THE STRUGGLE FOR EXISTENCE AND THE SURVIVAL OF THE FITrEst é : ; : : . : : : . 197-212 CHAPTER XXII. THE CLASSIFICATION OF PLANTS : : : S ; . 213-258 CHAPTER XXIII. Some Types oF FLOWERLESS PLANTS = ; : . . 219-245 Part II. KryY AND FLORA . d : : : ‘ e . ‘ 1-51 Poe MENTS OF BOTAN Y. “INTRODUCTORY. ‘‘ Botany is the science which endeavors to answer every reasonable question about plants.” } - Tue plant is a living being, provided generally with many parts, called organs, which it uses for taking in nourishment, for breathing, for protection against its enemies, and for reproducing itself and so keeping up the numbers of its own kind. The study of the individual plant therefore embraces a variety of topics, and the examination of its relation to others introduces many more subjects. ' Morphology, or the science of form, structure, and so on, deals with the plant without much regard to its character as a living thing. Under this head are studied the forms of plants and the various shapes or disguises which the same sort of organ may take in different kinds of plants, their gross structure, their microscopical structure, their classifiea- tion, and the successive stages in the history of the germs from which all but a few of the very simplest plants are formed. * Geographical Distribution, or botanical geography, discusses the range of the various kinds of plants over the earth’s sur- face. Another subdivision of botany, usually studied along with geology, describes the history of plant life on the earth from the appearance of the first plants until the present time. » 1 Professor George L. Goodale. 2. ELEMENTS OF BOTANY. ' Vegetable Physiology treats of the plant in action, how it lives, breathes, feeds, grows, and produces others like itself, and how it adjusts itself to the conditions which surround it. This division of the science also considers how the plant attacks other plants or animals (as do mildews and disease- germs respectively, for example), or how it is attacked by them, what are its diseases and how its life is terminated by these, by old age, or by external causes like frost or drought. - Many of the topics suggested in this outline cannot well be studied in the high school. There is not usually time to take up botanical geography or to do much more than men- tion the important subject of Heonomice Botany, the study of the uses of plants to man. It ought, however, to be possible for the student to learn in his high school course a good deal about the simpler parts of morphology and of vegetable physiology. One does not become a botanist — not even much of an amateur in the subject — by reading books about botany. It is necessary to study plants themselves, to take them to pieces and make out the connection of their parts, to examine with the microscope small portions of the exterior surface and thin slices of all the variously built materials or tissues of which the plant consists. All this can be done with living specimens or with those taken from dead parts of plants that have been preserved in any suitable way, as by drying or by placing in alcohol or other fluids which prevent decay. Living plants must be studied in order to ascertain what kinds of food they take, what kinds of waste substances they excrete, how and. where their growth takes place and what circumstances favor it, how they move, and indeed to get as complete an idea as possible of what has been called the behavior of plants. ‘Since the most familiar and most interesting plants spring from seeds, the beginner in botany can hardly do better than to examine at the outset the structure of a few familiar seeds, INTRODUCTORY. 3 then sprout them and watch the growth of the seedlings which spring from them. Afterwards he may study in a few typical examples the organs, structure, and functions of flowering plants, trace their life-history, and so, step by step, follow the process by which a new crop of seeds at last results from the growth and development of such a seed as that with which he began. ‘Meantime it will throw hght on the mode of growth of flowering plants to compare them with a few very simple flowerless plants. * After the whole round of vegetable life has been outlined from seed to seed, the student may learn a little about the never-ceasing struggle against unfavorable climates, poor soils, _ and the direct attacks of living enemies, — in short, the many kinds of adverse influences, such as all plants must meet and overcome in order to maintain their footing on the earth. * Finally, some idea may be gained of the relationships of plants to each other, or Systematic Botany. “CHAPTER I. - The Seed and its Germination. 1. Germination of Squash-Seed.— Soak some squash-seeds in tepid water for twelve hours or more. Plant these about an inch deep in damp sand or pine sawdust in a wooden box which has had holes enough bored through the bottom so that it will not hold water. Put the box in a warm place (not at any time over 70° or 80° Fahrenheit), and cover it loosely with a board or a pane of glass. Keep the sand or saw- dust moist, but not wet, and the seeds will germinate. As soon as any of the seeds, on being dug up, are found to have burst open, sketch one in this condition, noting the manner in which the outer seed-coat is split, and continue to make sketches at intervals of two days, until at least eight stages in the growth of the plantlet have been noted.! - Observe particularly how the sand is pushed aside by the rise of the young seedlings, and make one sketch to show what part of the plant first appears above the surface. Suggest some reason for the manner in which the sand is penetrated by the rising stem. ~ The student need not feel that he is expected to make finished draw- ings to record what he sees, but some kind of sketch, if only the merest outline, is indispensable. Practice and the study of the illustrations hereafter given will soon give some facility even to those who have had little or no instruction in drawing. Consult here Figs. 5 and 7. + 2, Examination of the Squash-Seed.— Make a sketch of the dry seed, natural size. Note the little scar at the pointed end of the seed where the latter was attached to its place of growth in the squash. Label this hilum. Describe the color and texture of the outer coating of the seed. With a scalpel or a very sharp knife cut across near the middle a seed that has been soaked in water for 24 hours. Squeeze one of the portions, held edgewise between the thumb and finger, in such a way as to separate slightly the halves into which the contents of the seed is naturally divided. Examine with the magnifying glass the section thus treated, * 1 The class is not to wait for the completion of this work (which may, if desirable, be done by each pupil at home), but is to proceed at once with the examination of the squash-seed and of other seeds, as directed in the following sections, and to set some beans to sprouting, so that they may be studied along with the germinating squashes. THE SEED AND ITS GERMINATION. 5 ~ make a sketch of it and label the shell or covering of the seed and the kernel within this. Taking another soaked seed, chip away the white outer shell, called the testa, and observe the thin, greenish inner skin, the tegmen, with which the kernel of the seed is closely covered. ‘Strip this off and sketch the uncovered kernel. Note that at one end it tapers to a point. This pointed portion, known as the caulicle, will develop after the seed sprouts into the stem of the plantlet, like that shown at fc in Fig. 1. Split the halves of the kernel entirely apart from each other, noticing that they are only attached for a very little way next to the caulicle, and ob- serve the thickness of the halves and the slight uneven- ness of the inner surfaces. These halves are called seed- leaves or cotyledons. Have ready some_ seeds which have been soaked for 24 hours and then left in a kee eon s one. — . i inati loosely covered jar on damp e Castor Bean and its Germination. : I, longitudinal section of the ri ; - blotting-paper at a tempera- |. = : enable: a = ce. ; minating seed; he, caulicle; c, cotyledon ; ture of 70° or over until they e, nourishment stored around the cotyledons ; have begun to sprout. s, testa; x, thickened knot at end of seed; Split one of these seeds WwW, primary root ; w’, secondary roots. apart, separating the cotyle- dons, and observe, at the junction of these, two very slender pointed objects, the rudimentary leaves of the plumule or first bud. +3. Examination of the Bean. — Study the seed, both dry and after 12 hours’ soaking, in the same general way in which the squash-seed has just been examined.! -,1The larger the variety of bean chosen, the easier it will be to see and sketch the several parts. The large red kidney bean or the horticultural bean will do well for this examination. 6 ELEMENTS OF BOTANY. Notice the presence of a distinct plumule, consisting of a pair of rudimentary leaves between the cotyledons, just where they are joined to the top of the caulicle. Make a sketch of these leaves as they lie in place on one of the cotyledons, after the bean has been split open. Note the cavity in each cotyledon caused by the pressure of the plumule. Place that cotyledon from which the sketch was made on the stage of the compound microscope under the lowest-power objective which the micro- scope has (say 2-inch), with light thrown on the object from above, and sketch the plumule as thus shown.! ‘4, Examination of the Pea. —There are no very important points of difference between the bean and pea, so far as the structure of the seed is concerned, but the student should rapidly dissect a few soaked peas to get an idea of the appearance of the parts, since he is to study the germina- tion of peas in some detail. Make only one sketch, that of the caulicle as seen in position after the removal of the seed-coats.? ~5. Germination of the Bean and the Pea. —Soak some beans as directed in § 3, plant them, and sketch as there directed. Follow the same directions with some peas.? 6. Germination of the Horse-Chestnut.— Plant some seeds of the horse- chestnut or the buckeye, study their mode of germination and make out the nature and peculiar modifications of the parts. Consult Gray’s Botanical Text-Book, vol. I, pp. 19, 20. '%. Conditions Requisite for Germination. — When we try to enumerate the external conditions which can affect germina- tion, we find that the principal ones are light, heat, moisture, and presence of air. A few simple experiments will show what influence these conditions exert. ‘8. Experiment 14 (a) Does Light assist Germination? (b) Does Light retard Germination ? — Put a piece of blotting-paper in the bottom *1The teacher should at this point give a short illustrated talk to explain in a general way the construction and use of the compound microscope. See Appendix A. * 2The teacher will find excellent sketches of most of the germinating seeds described in the present chapter in Miss Newell’s Outlines of Lessons in Botany, Part I, and in Gray’s Lessons in Botany. ' 3 The pupil may economize space by planting the new seeds in boxes from which part of the earlier-planted seeds have been dug up for use in sketching, ete. . # This may readily be made a home experiment. : THE SEED AND ITS GERMINATION. T of a tumbler, and add just water enough thoroughly to soak the paper. Pour out any excess. Place on the paper a few seeds (peas, barley, wheat, oats) that have been soaked for 24 hours; cover to prevent evaporation and put the tumbler in a light_place. Put the same number of other seeds of the same sort in a cup or box which will not admit light. Add a few drops of water from time to time, if the seeds or paper seem to be drying. Place the cup and tumbler side by side, so that they will have the same temperature, and watch for results. Tabulate your results something like this: No. of seeds sprouted in 24hrs. 48hrs. 72 hrs. 96 hrs. In dark, wae In light, ey ee ew eee N. B. — Take special pains to have the conditions of moisture and heat the same in the cup and in the tumbler. '9. Experiment 2. Relation of Temperature to Germination. — Arrange several vessels asin Exp. 1. Put in each vessel the same number of soaked peas.! Stand the vessels with their contents in places where they will be exposed to different, but fairly constant, temperatures and observe the several temperatures carefully with a thermometer. The following series is merely suggested, — other values may be found more convenient. Note the rate of germination in each place and record in tabular form as follows: No. of seeds sprouted in 24hrs. 48hrs. 72hrs. 96hrs._ ete. At 52 degrees, ee sa a —_- —s- ——— At 50 degrees, —— —-- — —$> ss ——— At 70 degrees, — — — —_—> Ss ———— At 90 degrees,? a a aa —_-—- —— ° 10. Experiment 3. Relation of Water to Germination. — Arrange seeds in several vessels as follows : In the first put blotting-paper that is barely moistened: on this put some dry seeds. *1Tf peas are used one year, Indian corn another year, squash-seeds another, and so on, a series of data will be obtained which may be quoted to the class after the experiment as above given has been completed. » 2 Here and elsewhere throughout the book temperatures are expressed in Fahren- | heit degrees, since with us, unfortunately, the Centigrade scale is not the familiar one, outside of physical and chemical laboratorfes. * 8 May be a home experiment. 8 ELEMENTS OF BOTANY. In the second put blotting-paper that has been barely moistened; on this put seeds that have been soaked for 24 hours. In the third put water enough thoroughly to soak the paper: use soaked seeds. In the fourth put water enough to half cover the seeds. Place the vessels where they will have same temperature and note the time of germination. Tabulate your results as in the previous experiments. “11. Experiment 4.*1 Will Seeds germinate without Air ?— Place some soaked seeds on blotting-paper in the bottom of a bottle; close tightly with a perforated rubber stopyer through which has been passed a long glass tube bent once at right angles as shown in Fig..2. Exhaust the air from the bottle by attaching the tube to an air-pump or an aspi- rator, and after considerable pumping and while the ex- haustion is going on, seal the whole air-tight by heating the tube near the bend with a Bunsen burner or alcohol lamp flame until it can be _drawn out to a thread. Fig. 2.— Soaked Peas in Stoppered Bottle, The stopper will be more ready for Exhaustion of Air. certain to prove air-tight if it has been well moistened with glycerine or vaseline before being inserted in the bottle. Place other seeds of the same kind in another bottle and stopper tightly. Place other seeds of the same kind in a third bottle ; stopper loosely. Place the three bottles side by side, so that they will have the same conditions of light and heat. Watch for results, and tabulate as in previous experiments. Most seeds will not germinate under water, but those of the sun- flower will do so, and therefore Exp. 4 may be varied in the following manner ; 1 Experiments marked thus * are to be performed by the teacher in the laboratory or class-room. THE SEED AND ITS GERMINATION. 9 ‘Remove the shells carefully from a considerable number of sunflower seeds. Try to germinate one lot of these in water which has been boiled, to remove the air, and then cooled and poured into a bottle which it fills up to the (tightly fitting) rubber stopper. In this bottle then there will be only seeds and water, no air-space. Try to germinate another lot of seeds in a bottle half filled with ordinary water. "12. Germination involves Chemical Changes. —If a ther- mometer is inserted into a jar of sprouting seeds, for instance peas, in a room at the ordinary temperature, the peas will be found to be warmer than the surrounding air. This rise of temperature is at least partly due to the absorption from the air of that substance in it which supports the life of animals and maintains the burning of fires, namely oxygen. The union of oxygen with substances with which it can combine, that is with those which will burn, is called ozvz- dation. This kind of chemical change is universal in plants and animals while they are in an active condition, and the energy which they manifest in their growth and movements is as directly the result of the oxidation going on inside them as the energy of a steam-engine is the result of the burning of coal or other fuel under its boiler. In the sprouting seed much of the energy produced by the action of oxygen upon oxidizable portions of its contents is expended in producing growth, but some of this energy is wasted by being trans- formed into heat which escapes into the surrounding soil. It is this escaping heat which is detected by a thermometer thrust into a quantity of germinating seeds. -138. Experiment 5.* Effect of Germinating Seeds wpon the Sur- rounding Air. — When Exp. 4 has been finished, insert into the air above the peas in the second bottle a lighted pine splinter, and note the effect upon its flame. Besides the proofs of chemical changes in germinating seeds just described, there are other kinds of evidence to the same effect. » 1 These are really fruits, but the distinction is not an important one at this point. 10 ELEMENTS OF BOTANY. Malt, which is merely sprouted barley with its germination permanently stopped at the desired point by the application of heat, tastes much sweeter than the unsprouted grain, and can be shown by chemical tests to have suffered a variety of changes. Germinating kernels of corn undergo great alterations in their structure (see Fig. 12). -14,. The Embryo and its Development.— The miniature plant, as it exists ready-formed in the seed, is called the embryo. In the seeds so far examined the entire contents of the seed-ccats consist of the embryo, but this is not the case with the great majority of seeds. As soon as the young plants of squash, bean, and pea have reached a height of three or four inches above the ground it is easy to recognize important differences in the way in which they set out in life. The cotyledons of the squash increase greatly in surface, acquire a green color and a generally leaf-like appearance, and, in fact, do the work of ordinary leaves. In such a case as this the appropriateness of the name seed-leaf is evident enough, — one recognizes at sight the fact that the cotyledons are actually the plant’s first leaves. In the bean the leaf-like nature of the cotyledons is not so clear. They rise out of the ground like the squash cotyledons, but then gradually shrivel away, though they may first turn green and somewhat leaf-like for a time. In the pea (as in the acorn, the horse-chestnut, and many other seeds) we have quite another plan, the underground type of germination. Here the thick cotyledons no longer rise above ground at all, because they are so gorged with nourishment that they could never become leaves; but the young stem pushes rapidly up from the surface of the soil. The development of the plumule seems to depend somewhat on that of the cotyledons. ‘The squash-seed has cotyledons THE SEED AND ITS GERMINATION. af which are not too thick to become useful leaves, and so the plant is in no special haste to get ready any other leaves. The plumule, therefore, cannot be found with the magnifying glass in the unsprouted seed, and is almost microscopic in size at the time when the caulicle begins to show outside of the seed-coats. In the bean and pea, on the other hand, since the cotyle- dons cannot serve as leaves, the later leaves must be pushed forward rapidly. In the bean the first pair are already well formed in the seed. In the pea they cannot be clearly made out, since the young plant forms several scales on its stem before it produces any full-sized leaves, and the embryo contains only caulicle, cotyledons, and a sort of knobbed plumule, well developed in point of size, representing the lower scaly part of the stem. CHAPTER II. The Parts of the Seedling ;—its Development. ‘15. Root, Stem, and Leaf. — By the time the seedling is well out of ground it, in most cases, possesses the three kinds of vegetative organs, or parts essential to growth, of ordinary flowering plants, the root, stem, and leaf. All of these organs may multiply and increase in size as the plant grows older, and their mature structure will be studied in later chapters, but some facts concerning them can best be learned by watch- ing their growth from the outset. 16. The Young Root. — Roots growing in sand or ordinary soil cling to its particles so tenaciously that they cannot easily be studied, and those grown in water have not quite the same form as soil roots. Roots grown in damp air are best adapted for careful study. Experiment 6. In what Portions of the Root does its Increase in Length take Place?-—Sprout some peas on moist blotting-paper in a loosely covered tumbler. When the roots are one and a half inches or more long, mark them along the whole length with little dots made with a very small camel’s-hair brush or a bristle dipped in water-proof India ink. Transfer the plants to moist blotting-paper under a bell glass or a battery jar and examine the roots at the end of twenty-four hours to see along what portions their length has increased; continue observations on them for several days. ive Root-Hairs. — Barley, oats, wheat, or red clover seed soaked and then sprouted on moist blotting-paper afford con- venient material for studying root-hairs. The seeds may be kept covered with a watch-glass or a clock-glass while sprout- ing. end of the cord is fastened to the tip of the stem of the plant of which the growth is to be measured and the other end has a weight G attached to it. As the plant grows the pointer Z descends on the scale. The actual rate of growth is obtained by multiplying the distance which the pointer travels over the arc by the fraction which expresses the ratio of the half-diameter of the pulley to the length of Z from arc to pivot. Contrast the mode of growth of the root and the stem and try to give a reason for that of the root. 20. The First Leaves.—The cotyledons are, as already explained, the first leaves which the seedling possesses, — even if a plumule is found well developed in the seed, it was formed after the cotyledons. In those plants which have so much nourishment stored in the cotyledons as to render these unfit ever to become useful leaves, there is little or nothing in the color, shape, or general appearance of the cotyledon to make one think it really a leaf, and it is only by studying many cases that the botanist is entitled to class all cotyle- dons as leaves in their nature, even if they are quite unable to do the work of leaves. The study of the various forms which the parts or organs of a plant may assume is called morphology; it traces the relationship of parts which are really akin to each other, though dissimilar in appearance and often in function. In seeds which have endosperm, or nourishment stored outside of the embryo, the cotyledons’ usually become green and leaf-like, as they do, for example, in the four-o’-clock and the morning-glory, but in the seeds of the grains (which contain endosperm) a large portion of the single cotyledon remains throughout as a thickish mass buried in the seed. In a few cases, as in the pea, there are scales instead of true leaves formed on the first nodes above the cotyledons, and it is only at about the third node above that leaves of the ordinary kind appear. In the bean and some - other plants which in general bear one leaf at a node along the stem, there is a pair produced at the first node above THE PARTS OF THE SEEDLING. LT the cotyledons, and the leaves of this pair differ in shape from those which arise from the succeeding portions of the stem. - 21. Classification of Plants by the Number of their Cotyledons. — In the pine family the germi- nating seed often displays more than two coty- ledons, as shown in Fig. 6; in the majority of common flowering plants the seed contains two cotyledons, while in the lites, the rushes, the sedges, the grasses, and some other plants there is but, one cotyledon. Upon these facts is based the division of most flowering plants into two great groups: the dicotyledonous plants, which have two seed-leaves, and the monocotyledonous plants, which have one seed-leaf. Other important differ- ences constantly accompany the difference in _ number of cotyledons, as will be seen later. Fia. 6. — Ger- minating Pine. c, cotyledons. CHAPTER III. Storage of Nourishment in the Seed. 22, Nourishment in the Embryo. — Squash-seeds are not used for human food, since they have medicinal properties that maké them undesirable for that purpose, but beans and peas are important articles of food. Whether the material accumulated in the cotyledons is an aid to the growth of the young plant may be learned from a simple experiment. 23. Experiment 7.* Are the Coty- ledons of a Pea of any Use to the Seedling ?1 — Sprout several peas on blotting-paper. When the plumules appear, carefully cut away the cotyledons from some of the seeds. Place on a perforated cork, as shown in Fig. 7, one or two seedlings from which the cotyle- dons have been cut, and as many which have not been mutilated, and allow the caulicles to extend into the water. Let them grow for some days, or even weeks, and note results. Fic. 7.—Germinating Peas, 24, Experiment 8.2 Does the Amount growing in Water, one of Material in the Seed have anything to do deprived of its Cotyle- with the Rate of Growth of the Seedling ?— dons. ; Germinate ten or more clover-seeds, and «about the same number of peas, on moist blotting-paper under a bell jar. .\fter they are well sprouted, transfer both kinds of seeds to fine cotton netting, stretched across wide-mouthed jars nearly full of water. The roots should dip into the water, but the seeds must not do so. Allow the plants to grow until the peas are from 4 to 6 inches high. Some of the growth in each case depends on material 1 The pea is used in a large number of the experiments here given, because it germinates at a comparatively low temperature, and the young seedlings are very hardy and thrive readily in the schoolroom. 2 May be a home experiment. STORAGE OF NOURISHMENT IN THE SEED. 19 gathered from the air and water, but most of it, during the very early life of the plant, is due to the reserve material stored in the seed. Any one who has watched the slow growth of seedling grass plants and the very rapid growth of young corn plants can appreciate the effect of an abundant supply of food in the seed in securing a rapid start for the seedling. This particular illustration is a good one, since corn is itself a kind of grass. 25. Storage of Nourishment outside of the Embryo. — In very many cases the cotyledons contain little nutriment, but there is a supply of it stored in the seed beside or around them, Figs. 1 and 8. 26. Examination of the Four-o’clock Seed; its Germination. — Examine the external sur- face of a seed! of the four-o’clock, and try the hardness of the outer coat by cutting it Branches which, like those of tle forming a bulb-seale; s, : thin sheath of leaf; 1,i, Myrsiphyllum, so _ closely resemble blade of ‘the leaf; % leaves as to be almost indistinguish- hollow interior of blade. able from them are called cladophylls. - 74. Modifiability of the Stem. —The stem may, as in the tallest trees, in the great lianas of South American forests, seen in the frontispiece, or the rattan of Indian jungles, reach a length of many hundred feet, or it may in such “stemless” om STEMS. Te, 51 plants as the primrose and the dandelion be cut down to a fraction of an inch in length. It may take on apparently root-like forms, as in many grasses and sedges, or become thickened by underground deposits of starch and other plant- food, as in the iris, the potato, and the crocus. Condensed forms of stem may exist above ground, or, on the other hand, ped * Fic. 39.—Stem of ‘ Smilax” (Myrsiphyllum). l, seale-like leaves ; Cl, cladophyll, or leaf-like branch, growing in the axil of the leaf; ped, flower-stalk, growing in the axil of a leaf. branches may be flat and thin enough closely to imitate leaves. In short, the stem manifests great readiness in adapting itself to the most varied conditions of existence. CHAPTER VI. Structure of the Stem. STEM OF DICOTYLEDONOUS PLANTS. & 75. General Structure.— Cut smooth, rather thick, sections from a twig of apple one year old. Place in focus under the magnifying glass and make a sketch to show the relative position and amount of bark, wood, and pith. From a twig of cherry a year or two old peel off the brown outer coat- ing. This is the corky layer of the bark, more distinct in the cherry tree than in the apple. Notice on the outer surface of the twig the rough oval or lens-shaped spots. These are the lenticels, spots in which the inner and more porous layers of the bark protrude through the corky layer and allow air to penetrate to the interior of the branches.! Notice the green layer or middle bark in the -peeled portion of the cherry twig, and expose this layer in the apple twig by carefully scraping off the corky layer. Cut off, as smoothly as possible, a small branch of hickory and one of white oak above and below each of the rings of scars already mentioned (§ 58), and count the rings of wood above and below each ring of scars. How do the numbers correspond ? What does this indicate ? Count the rings of wood on the cut-off ends of large billets of some of the following woods: locust, chestnut, sycamore, oak, hickory. Do the successive rings of the same tree agree in thickness ? Why ? or why not ? Does the thickness of the rings appear uniform all the way round the stick of wood? If not, the reason in the case of an upright stem (trunk) is perhaps that there was a greater spread of leaves on the side where the rings are thickest? or because there was unequal pressure, caused by bending before the wind. Do the rings of any one kind of tree agree in thickness with those of all the other kinds? What does this show ? In all the woods examined look for : (a) Contrasts in color between the heartwood and the sapwood.? 1 See Gregory’s Plant Anatomy, pp. 138-141. 2 See § 145. 3 This is admirably shown in black walnut, barberry, and osage orange. STRUCTURE OF THE STEM. 53 (b) The narrow lines running in very young stems pretty straight from pith to bark, in older wood extending only a little of the way from centre to bark, the medullary rays, shown in Fig. 40.1 ~ (c) The wedge-shaped masses of wood between these. (a) The holes which are so grouped as to mark the divisions between successive rings. These holes indicate the cross-sections of vessels or ducts (§ 82). Note the distribution of the vessels in the rings to which they belong, compare this with Figs. 40, 41, and decide at what season of the year the largest ducts are mainly produced. Cut off a grapevine several years old and notice the great size of the vessels. Examine the smoothly planed surface of a billet of red oak that has been split through the middle of the tree (quartered oak), and note the large shining plates formed by the medullary rays. Look at another stick that has been planed away from the outside until a good-sized flat surface is shown, and see how the medullary rays are here jg, 40, — Cross-Section of Oak Wood as seen with represented only by their the Magnifying Glass. edges. J, J, the annual rings.? Hi. 76. Details of Structure; Cross-Section. —Cut from shoots of the apple tree, ranging in age from one to five years, a number of sections. These should be as thin as they can be made without breaking up. It will save time to make at one time a good many sections of any woody part of the plant that is to be examined.# For examination with the lowest powers, cylinders + to 4 inch long cut smoothly from the twig to be examined, and viewed as opaque objects, will answer well. 1 These and many other important things are admirably shown in the thin wood- sections furnished for $4 per set of 24 by R. B. Hough, Lowville, N. Y. 2 The shading in fine lines at J would be rendered more naturally by dots. 3 Tf time allows, the students should cut their own sections : frequently this will be impracticable. Sections not needed for the current lesson may be put in 50 per cent alcohol or other preservative fluid in wide-mouthed bottles carefully labeled and kept for future use. For a list of sections see Appendix C. 54 ELEMENTS OF BOTANY. Examine each thin section first with a power of about 25 diameters, then with a power of from 100 to 200 diameters. With the lower power, sketch a one-year-old section, labeling in your sketch : (a) The corky layer of the bark. (b) The green layer. (c) The masses of bast fibres. (d) The wood, with the medullary rays and vessels. (e) The pith. Fie. 41. — Cross-Section of a Three-year-old Linden Twig. (Much magnified.) P, epidermis and corky layer of the bark; Phl, bast ; C, cambium layer ; JR, annual rings of wood. After examining this section with the higher power and noting par- ticularly the appearance of the wood-cells, replace it by a section of stem at least four years old. Sketch this as seen with the low power, then substitute the higher power and study the inner bark, noting especially the masses of very thick-walled bast-cells. What are the principal differences between the structure of the apple twig, so far as you have examined it, and the structure of a linden twig, as shown in Fig. 41 ? STRUCTURE OF THE STEM. 55 Make a thin section of the stem of grapevine or elder a year or two old and study the pith with a power of 50 or 100 diameters. Sketch it. Fig. 45. Fie. 42. — Portion of a Sieve-Tube, showing one whole cell and parts of two others. Fie. 43.— Longitudinal Section through Sieve-Tube of the Gourd. Z, cell-wall; h, outer coating of protoplasmic cell-contents i ; v, sieve-plate. Fig. 44. — Transverse Section of a Sieve-Plate like that shown at v. Fie. 45.— Part of Longitudinal Section of a Sieve-Tube of Linden, showing sieve- plates p on the sides of the tube (two of which are also shown on Fig. 43). (All greatly magnified.) 56 ELEMENTS OF BOTANY. 77. Sieve-Tubes. — Grouped together with the bast fibres of the stem there occur a peculiar and very important set of vessels called sieve-tubes. The student cannot easily make these out from sections of ordinary stems, but it is not diffi- cult to understand their structure in a general way. These tubes arise from the partial union of large cells which stand in rows, united end to end, as shown in Figs. 42, 43. The partitions between adjacent cells gradually become perforated with holes, forming a sieve-plate, like that shown in Fig. 44. Sometimes the walls of sieve-tubes are more or less fully covered with perforations, as shown in Fig. 45. Continuity of the Living Cell-Contents.— It was formerly supposed that cells of plants were entirely shut off from each other while living. Recently, careful investigations have shown that very generally, especially in the expanded bases of the leaf- stalks of leaves which move of their own accord and in sieve: cells, there is a direct connec- Fic. 46.— Side View of Part ofone tion of the contents of one cell] ey Pee csctiea Maple with another. The protoplasm, ox semi-fluid layer with which all active celis are lined, and in which their life and working- power resides (Chapter XIII), extends in delicate threads through the cell walls, and connects in all directions with the protoplasm of other cells. 78. Longitudinal Section of the Stem. —'The knowledge of stem-structure that can be gained from a longitudinal section . of any kind of wood depends upon the way in which the sec- tion is cut; that is, whether it is at right angles to the annual rings (radial section), or parallel to the rings (tangential sec- tion). The wood-cells, of which the student has in the cross- section seen only the cut-off ends, appearing as circular or my STRUCTURE OF THE STEM. 57 oval figures, now show the whole length of the cell, and he may study the way in which they interlock at the ends. In the radial section the medullary rays will frequently look somewhat like portions of brickwork, as shown in Fig. 46. In the tangential section, only the cut-off edges of the medullary rays will Hl: be seen, as shown in Fig. 47. 79. Separate Wood-Cells. — The com- plete outline of wood-cells and bast-cells is most easily made out by examining cells which have been separated from each other by soaking wood or bark, as the case may be, in a mixture of chlo- rate of potash and nitric acid until it can be easily picked to pieces in water and viewed under the microscope. In this way such cells as those shown in Fig. 48 may be isolated and studied. 80. Ducts of Various Forms. — In most of the hard-woods the ducts are poorly shown in the longitudinal sec- tion, since they usually become much split and broken in the process of cut- ting the section. iJ rR = = es SE ati SS —_ ve,¢ es ry SA —y Fic. 47. — Longitudinal Sec- tion of Mahogany at right angles to the Medullary Rays, showing their cut- off ends.1 (Much magni- fied.) Study and sketch some of the following, as seen under a moderately high power : Radial longitudinal section of wood of tulip tree, longitudinal section of stem of bracken fern (Pteris), stem of castor-oil plant (Fig. 49), of peduncle of banana, or of root of chicory or licorice. 81. Kinds of Tisswe.—The student has now become acquainted with a few of the many kinds of cells found in plants, and has begun to see how they are grouped together 1The apparently vacant spaces at the ends of the lens-shaped sections of the medullary rays are in most woods filled with cells, like the rest of the section, 58 ELEMENTS OF BOTANY. in masses to make up the bulk of the plant. Masses of cells which have a common work to do are called tissues. Two of the most important forms of tissue are parenchyma and prosenchyma. Parenchyma is found in the seed, in the bark (constituting the greater portion of all young bark), in the medullary rays and the pith, and in the leaf. Parenchyma cells are usually roundish or somewhat cubical or twelve-sided in shape. | From the fact that a sphere surrounded by other spheres is touched by twelve others, parenchyma cells, which begin their existence in a somewhat | globular form, often end by | growing approximately twelve- sided from the pressure of their | neighbors. Prosenchyma cells are long, often thick-walled, and interlock at the ends, so as to leave but few and small in- tercellular spaces. They form the fibrous part of bark and of most kinds of wood. 82: Uses of the Components of the Stem. — There is a marked division of labor among the various groups of cells that A ys make up the stem of ordinary Fic. 48.— 4A, B, C, D, Isolated Wood- qicotyledons, particularly in the Cells and Bast-Cells of Linden. ; : A, B, wood fibres ; C, piece of a vessel; stems of trees, and it will be D, bast fibre ; E,a partitioned, woody best to explain the uses of the Tee ee European ivy. (Much kinds of cells as found in trees, rather than in herbaceous plants. A few of the ascertained uses of the various tissues are these : D 1 See Gregory’s Plant Anatomy, Chapter IV. STRUCTURE OF THE STEM. © 59 The pith forms a large part of the bulk of very young shoots, since it is a part of the fundamental tissue amid which the fibro-vascular bundles arise. In mature stems it becomes rather unimportant, though it often continues for a long time to act as a storehouse of nourishment. The medullary rays, in the young shoot, serve as a channel for the transference of water and plant-food in a liquid form across thestem, and they often contain much stored nourishment. The vessels carry water and air through the stem. i il) ~ WINK, Sx Nv) MONOID} yy 10) ee KS H ‘ ‘ a = ICs O20), or y= plovojs'oleto} DOK OOS aoe Dh J00000 000 09099NIVOIH( c°ATIDO eee Fig. 49. — Longitudinal Section of a Fibro-Vascular Bundle of the Castor-Oil Plant. r, gs, b, p, various layers of the bark; c, cambium; ¢ J, s, s’, various kinds of vessels; h, h', hh”, h’ , wood-cells ; m, pith. (Much magnified.) The wood-cells of the heartwood are useful only to give stiffness to the stem. Those of the sapwood in addition to this work have to carry most of the water from the roots to the leaves and other distant portions of the plant. The cambium layer is the region in which the annual growth of the tree takes place, § 84. The most important portion of the inner bark is that which consists of sieve-tubes, for in these digested and elaborated plant-food is carried from the leaves toward the roots. 60 ELEMENTS OF BOTANY. The green layer of the bark in young shoots does much toward collecting and preparing the food of the plant from. air and water, but this work may be best explained in connec- tion with the study of the leaf, Chapter XII. Oy y ia as ( oe: Fic. 51. — Longitudinal Radial Section m mM through a Rapidly Growing Young Fie. 50.— Cross-Section of Fir Branch of Pine. Wood. t, t', t’, bordered pits on wood-cells; st, large 8S, aresin passage ; m, medullary pits where medullary rays lie against wood- rays. (Much magnified.) cells. (Much magnified.) Finally, the corky layer of the bark serves to a considerable extent as a protection against sudden changes of temperature and aids greatly in preventing evaporation of water on ‘its way along the stem. re geter- STRUCTURE OF THE STEM. 61 83. Stem of Conifers.1— Sketch the end of a cut-off billet of hard pine or red cedar. Study the cut surface with a magnifying glass and decide whether any of the parts readily found in the wood of the coarser- grained hard-woods are absent from coniferous wood. Under a power of 100 or more diameters it is easy to see what it is that marks off one annual ring from another. Study the section, compare it with Fig. 50, and state the difference between spring wood and fall wood. Sketch the whole moderately magnified Examine longitudinal sections, both radial and tangential, of pine, spruce, fir, or red cedar.? Sketch a radial section and a tangen- tial one, labeling the medullary rays and the cells of the wood, with their circular markings, as shown in Fig. 51. 84. The Early History of the Stem. —In the earliest stages of the growth of the stem it consists entirely of thin-walled and rapidly dividing cells. Soon, however, the various kinds of tissue which are found in the full-grown stem begin to appear. In Fig. 52 the process is shown as it occurs in the castor bean. At m, in B, is the central column of pith, surrounded by eight fibro- vascular bundles, fv, each of which contains a number of ducts arranged cross - section, A Fie. 52.—Transverse Section through the Caulicle of the Castor- Oil Plant at Various Stages. A, after the root has just appeared outside the testa of the seed; B, after the caulicle is nearly an inch long; C, at the end of germina- tion; 7, cortex (undeveloped bark); m, pith; st, medullary rays; jv, fibro-vascular bundles ; cb, layer of tissue which is to develop into cambium. (Consider- ably magnified.) in a pretty regular manner and surrounded by the forerunners of the true wood-cells. 1 That is, of the cone-bearing trees (mostly evergreens), such as the pines, spruces, cedars, larches, and so on. 2 Pine shows the large circular pits very plainly, while red cedar shows the medul- lary rays most clearly, since nearly all its red color lies in these. 62 ELEMENTS OF BOTANY. In C, the section shows a considerable advance in growth: the fibro-vascular bundles are larger and are now connected by a rapidly growing layer of tissue, cb. As growth continues, this layer becomes the cambium layer, composed of thin-walled and rapidly dividing cells, as shown in Fig. 41. ; 85. Secondary Growth. — From the inside of the cambium layer the wood-cells and ducts of the mature stem are pro- duced, while from its outer circumference the new layers of the bark proceed. From this mode of increase, the stems of dicotyledonous plants are called exogenous, that is, outside- growing. The presence of the cambium layer on the outside of the wood in early spring is a fact well known to the school- boy who pounds the cylinder cut from an elder, willow, or hickory branch until the bark will slp off and so enable him to make a whistle. The sweet taste of this pulpy layer, as found in the white pine, the slippery elm, and the basswood, is a familiar evidence of the nourishment which the cambium layer contains. With the increase of the fibro-vascular bundles of the wood the space between them, which appears relatively large in Fig. 52, becomes less and less, and the pith, which at first ex- tended freely out toward the circumference of the stem, becomes compressed into thin plates so as to form medullary rays. These are, as already stated, of use in storing the food which the plant in cold and temperate climates lays up in the summer and fall for use in the following spring, and in the very young stem they serve as an important channel for the transference of fluids across the stem from bark to pith, or in the reverse direction. On account, perhaps, of their importance to the plants, the cells of the medullary rays are among the longest-lived of all vegetable cells, retaining their vitality in the beech tree sometimes, it is said, for more than a hundred years. STRUCTURE OF THE STEM. ' 63 After the inter-spaces between the first fibro-vascular bundles have become filled up with wood, the subsequent growth must take place in the manner shown in Fig. 53. The cambium of the original wedges of wood, fe, and the cambium, 7c, formed between these wedges, continues to grow from its inner and from its outer surface, and thus causes a permanent SAX g 1 Fia. 53. — Diagram to illustrate Secondary Growth in a Dicotyledonous Stem. R, the first-formed bark ; p, mass of sieve-cells ; ifp, mass of sieve-cells between the original wedges of wood ; fc, cambium of wedges of wood ; ic, cambium between wedges; b, groups of bast-cells; fh, wood of the original wedges; ifh, wood formed between wedges; 2, earliest wood formed; MM, pith. increase in the diameter of the stem and a thickening of the bark, which, however, usually soon begins to peel off from the outside and thus soon attains a pretty constant thickness.’ 86. Grafting. — When the cambium layer of any vigor- ously growing stem is brought in contact with this layer in 1 See Gregory’s Plant Anatomy, Chapter VII. 64 ELEMENTS OF BOTANY. another stem of the same kind or a closely similar kind of plant, the two may grow together to form a single stem or branch. This process is called grafting, and is much resorted to in order to secure apples, pears, etc., of any desired kind. A twig from a tree of the chosen variety is grafted on to any kind of tree of the same species (or sometimes a related species), and the resulting stems will bear the wished-for kind of fruit. SteM oF MoNocOoTYLEDONOUS PLANTS. 87. General Structure. — Cut across a corn-stalk and examine the cut surface with the magnifying glass. Note the firm rind, composed of the epidermis and underlying tissue, the large mass of pith composing the main bulk of the stem, and the fibro-vascular bundles, or groups of wood- cells, bast-cells, and vessels. In what part of the stem are these bundles most abundant ? Split a portion of the stem lengthwise and notice whether the bundles seem to run straight up and down its length. Every fibro-vascular bun- dle of the stem passes outward through some node in order to connect with some fibro-vascular bundle of a leaf. This fact being known to the student would lead him to expect to find the bundles bending out of a vertical position more at the nodes than elsewhere. Can this be seen in the stem examined ? Observe the enlargement and thickening at the nodes, and split one of these lengthwise to see whether the tissue within it is exactly like that in the internodes. How may the difference, if any, be explained ? Compare with the corn-stalk a piece of palmetto! and notice the simi- larity of structure, except for the fact that the tissue in the palmetto which answers to the pith of the corn-stalk is much darker-colored and harder than corn-stalk pith. Compare also a piece of rattan. Cut a thin cross-section of the corn-stalk, examine with a moderately high power of the microscope, and note : (a) The rind, composed largely of hard, thick-walled fibres known as sclerenchyma fibres ; (0) The fibro-vascular bundles, most abundant near the outside, becoming much more scattered toward the centre of the stem ; (c) The pith, occupying the intervals between the fibro-vascular bundles. 1 The pieces which are sold at the druggists’ prepared for nail-brushes will serve the purpose well. ' STRUCTURE OF THE STEM. 65 Study the bundles in various portions of the section and notice particu- larly whether the relative amount of surface in each covered by ducts and by thick-walled wood-cells or sclerenchyma cells is everywhere the same. On the whole the structure of monocotyledonous stems is much simpler than that of dicotyledonous stems. The bun- dles which they contain are somewhat similar to those which the exogenous or outside-growing stems of dicotyledons form at a very early period of their growth. But while in exogens these bundles soon unite into a ring of woody tissue, with a cambium layer outside, capable of continual growth inward and outward, in the endogenous or inside-growing stems of monocotyledons this is not the case. True cambium is not formed, but the procam- bium which precedes the mature bark-cells and wood- cells is all transformed into cells of bark or of wood, which attain their full size and are then incapable of giving rise to new cells of Susela tg 2 SS any kind. Therefore, the FIG. ot) Gkcae bonton of Stem of Indian stems of such perennials as ie palms remain unchanged in ¢* Hbovasenss boniles #6 nehy me diameter year after year. : Monocotyledonous stems which do increase in diameter from year to year do so by the introduction of new bundles among the old ones. This growth by interposition of new bundles affords some justification for the name endogenous, often given to the monocotyledonous stem. 88. Distribution of Material in Monocotyledonous Stems. — The well-known strength and lightness of the straw of our ‘ 00 @ 9g0% ¢e® ° ° Z ao? * * Res 2 J 22014 © 20 005% 009°, SZ 2.9250 c0 99 © 00, 35 66 ELEMENTS OF BOTANY. smaller grains and of rods of cane or bamboo is due to their form. It can readily be shown by experiment that an iron or steel tube of moderate thickness, like a piece of gas-pipe, or of bicycle-tubing, is much stiffer than a solid rod of the same weight per foot. The oat straw, the cane (of our southern canebrakes), and the bamboo are hollow cylinders: the corn-stalk is a solid cylinder, but filled with a very light pith. The flinty outer layer of the stalk, together with the closely packed sclerenchyma fibres of the outer rind and the frequent fibro-vascular bundles just within this are arranged in a most advantageous way to secure stiffness. 89. Experiment 17. Rise of Water in Monocotyledonous Stems. — Place in red ink the ends of pieces cut from any obtainable mono- cotyledonous stem, as green brier, or young shoots of asparagus,! and watch for an hour or two the rise of the coloring-matter, by taking out pieces of stem from time to time and cutting each back from the upper end until the colored portion is reached. Examine the cut surfaces and the outside of each stem with the glass, and describe exactly the dis- tribution of the coloring-matter. 1 Tf the class is studying this subject during the autumn, fresh pieces of corn- stalk will be found to give excellent results. CHAPTER VII. Living Parts of the Stem; Work of the Stem. 90. In annual plants generally and in the very young shoots of shrubs and trees there are breathing pores which occur abundantly in the epidermis, serving for the admission of air and the escape of moisture, while the green layer of the bark answers the same purpose that is served by the green pulp of the leaf, which will be explained in Chapter XII. For a good many years, too, the spongy lenticels, which occur scattered over the external surface of the bark of trees and shrubs, serve to admit air to the interior of the stem. The lenticels at first appear as roundish spots, of very small size, but as the twig or shoot on which they occur increases in diameter the lenticel becomes spread out at right angles to the length of the stem, so that it sometimes becomes a long transverse slit or scar on the bark, as is readily seen in the cherry and the birch. But in the trunk of a large tree no part of the bark except the inner layers is alive. The older portions of the bark sometimes cling for years after they are dead and useless, except as a protection for the parts beneath against mechanical injuries or against cold. A familiar example of highly developed cork is in the bark of the cork oak, from which the ordinary stoppers for bottles are made. Trees which have been bruised or peeled so as to expose the wood require a coat of paint or coal-tar on the injured parts to keep out water and prevent decay. But in many cases, as in the shellbark hickory and the grapevine, the old bark soon falls off in strips; in birches it finally peels off in bands around the stem. 68 ELEMENTS OF BOTANY. The heartwood of a full-grown tree is hardly living, unless some of the medullary rays may retain their vitality, and so wood of this kind is useful to the tree mainly by the stiffness which it gives to the trunk and larger branches, thus prevent- ing them from being easily broken by storms. 91. Movement of Water in the Stem.—The student has already learned ($ 50) that large quantities of water are taken up by the roots. Having become somewhat acquainted with the structure of the stem, he is now in a position to investigate the question how the various fluids, commonly known as sap, travel about in it.t It is important to notice that sap is by no means the same substance everywhere and at all times. As it first makes its way by osmotic action inward through the root-hairs of the growing plant it differs but little from ordinary spring water or well water. The liquid which flows from the cut stem of a “bleeding” grapevine which has been pruned just before the buds have begun to burst in the spring, is water with a little mucilaginous or slimy material added. The sap which is obtained from maple trees in late winter or early spring, and is boiled down for syrup or sugar, is still richer in nutritious material than the water of the grapevine, while the elaborated sap which is sent so abundantly into the ear of corn, at its period of filling out, or into the growing pods of beans and peas, or into the rapidly forming acorn or the chestnut, contain great stores of food, suited to sustain plant or animal life. 92. Experiment 18. Rise of Water in Exogenous Stems. —Cut some short branches from a grapevine and stand the lower end of each in red ink; try the same experiment with twigs of oak, ash, or other porous wood, and after some hours examine with the magnifying glass and with the microscope, using the two-inch objective, successive cross- sections of one or more twigs of each kind. Note exactly the portions 1 See the paper on The so-called Sap of Trees and its Movements, by Prof. Chas Rk. Barnes, Science, X XI, 535. LIVING PARTS OF THE STEM. 69 through which the ink has traveled. Repeat with several potatoes, cut crosswise through the middle. For the sake of comparison between roots and stems, treat any convenient root, such as a parsnip, in the same way. Examine longitudinal sections of some of the twigs, the potatoes, and the roots. In drawing conclusions about the channels through which the ink has risen (which are those through which the crude sap most readily travels), bear in mind the fact that a slow soakage of the red ink will take place in all directions, and therefore pay attention only to the strongly colored spots or lines. . What conclusions can be drawn from this experiment as to the course followed by the sap ? From the familiar facts that ordinary forest trees appar- ently flourish as well after the almost complete decay and removal of their heartwood, and that many kinds will live and grow for a considerable time after a ring of bark extend- ing all round the trunk has been removed, it may readily be inferred that the crude sap in trees must rise through some portion of the newer layers of the wood. Most dicotyledonous stems, when stripped of a ring of bark and then stood in water, as shown in Fig. 55, develop roots only at or near the upper edge of the stripped portion,’ and this would seem to prove that such stems send their building-material — the elab- orated sap —largely at any rate down through the bark. Itscourse F'!¢. 55.—A Cutting Girdled and : sending down Roots from the is undoubtedly for the most part Upper Edge of the Girdled Ring. through the sieve-cells (Figs. 42— 45), which are admirably adapted to convey liquids. In addi. tion to these general upward and downward movements of 1 This may be made the subject of a protracted class-room experiment. Strong shoots of willow should be used for the purpose. 70 ELEMENTS OF BOTANY. sap there must be local transfers laterally through the stem, and these are at times of much importance to the plant. 93. Rate of Movement of Water in the Stem. — There are many practical difficulties in the way of ascertaining exactly how fast the watery sap travels from the root to the leaves. It is, however, easy to illustrate experimentally the fact that it does rise, and to give an approximate idea of the time required for its ascent. The best experiment for beginners is one which deals with an entire plant under natural conditions. 94. Experiment 19. Wilting and Recovery. — Allow a fuchsia or a hydrangea! which is growing in a flower-pot to wilt considerably for lack of watering. Then water it freely and record the time required for the leaves to begin to recover their natural appearance and position, and the time fully to recover. The former interval of time will give a very rough idea of the time of transfer of water through the roots and the stem of the plant. From this, by measuring the approximate dis- tance traveled, a calculation could be made of the number of inches per minute which water travels in this particular kind of plant, through a route which is partly roots, partly stem, and partly petiole. Still another method is to treat leafy stems as the student in Exp. 18 treated the twigs which he was examining, and note carefully the rate of ascent of the coloring liquid. This plan is likely to give results that are too low, still it is of some use. It has given results vary- ing from 34 inches per hour for the willow to 880 inches per hour for the sunflower. A better method is to introduce the roots of the plant which is being experimented upon into a weak solution of some chemical substance which is harmless to the plant and which can readily be detected anywhere in the tissues of the plant by chemical tests. Proper tests are then applied to portions of the stem which are cut from the plant at short intervals of time. 1 Hydrangea hortensis. LIVING PARTS OF THE STEM. 71 Compounds of the metal lithium are well adapted for use in this mode of experimentation. 95. Causes of Movements of Water in the Stem.— Some of the phenomena of osmose were explained in §§ 50-54, and the work of the root-hairs was described as due to osmotic action. Root pressure (§ 55), being apparently able to sustain a column of water only 80 or 90 feet high at the most, and usually less than half this amount, would be quite insufficient to raise the sap to the tops of the tallest trees, since many kinds grow to a height of more than a hundred feet. Our Californian “big trees,” or Sequoias, reach the height of over 500 feet, and an Australian species of Eucalyptus, it is said, sometimes towers up to 470 feet. Root pressure, then, may serve to start the soil-water on its upward journey, but some other force or forces must step in to carry it the rest of the way. What these other forces are is still a matter of dis- cussion among botanists. The slower inward and downward movement of the sap may be explained as due to osmose. For instance, in the case of growing wood-cells, sugary sap from the leaves gives up part of its sugar to form the cellu- lose of which the wood-cells are being made. This loss of sugar would cause a flow of rather watery sap to take place more rapidly than usual from the growing wood to the leaves, while at the same time a slow transfer of the dissolved sugar will be set up from leaves to wood. The water, as fast as it reaches the leaves, will be thrown off in the form of vapor, so that they will not become distended with water, while the sugar will be changed into cellulose and built into new wood-cells as fast as it reaches the region where such cells are being formed. Plants in general‘ readily change starch to sugar, and sugar 1 Not including most of the flowerless and very low and simple kinds. # fbr ELEMENTS OF BOTANY. to starch. When they are depositing starch in any part of the root or stem for future use, the withdrawal of sugar from those portions of the sap which contain it most abundantly gives rise to a slow movement of dissolved particles of sugar in the direction of the region where starch is being laid up. 96. Storage of Food in the Stem. —'The reason why the plant may profit by laying up a food supply somewhere inside its tissues has already been suggested, § 70. The most remarkable instance of storage of food in the stem is probably that of sago-palms, which contain an enormous amount, sometimes as much as 800 pounds, of starchy material in a single trunk. But the commoner plants of temperate regions furnish plenty of examples of deposits’ of food in the stem. As in the case of seeds and roots, starch constitutes one of the most important kinds of this reserve material of the stem, and since it is easier to detect than any other substance which the plant employs for this purpose, the student will do well to spend the time which he devotes to the study of storage of food in the stem to looking for starch only. Cut thin cross-sections of twigs of any common hard-wood tree, in its winter condition, moisten with iodine solution, and examine for starch with a moderately high power of the microscope. Sketch the section, and describe exactly in what portions the starch is deposited. 97. Storage in Underground Stens.— The branches and trunk of a tree furnish the most convenient place in which to deposit nourishment during winter to begin the growth of the following spring. But in those plants which die down to the ground at the beginning of winter the storage must be either in the roots, as has been described in § 46, or in underground portions of the stem. Rootstocks, tubers, and bulbs seem to have been developed by plants to answer as storehouses through the winter (or in a 7 LIVING PARTS OF THE STEM. 73 countries where there is one, through the dry season) for the reserve materials which the plant has accumulated during the growing season. The commonest tuber is the potato, and this fact and the points of interest which it represents make it especially desirable to use for a study of the underground stem in a form most highly specialized for the storage of starch and other valuable products. 98. A Typical Tuber ; the Potato. — Sketch the general outline of a potato, showing the attachment to the stem from which it grew.! Note the distribution of the ‘‘eyes,’’ —are they opposite or alternate ? Examine them closely with the magnifying glass and then with the lowest power of the microscope. What do they appear to be ? If the potato is a stem it may branch, — look over a lot of potatoes to try to find a branching specimen. If such a one is secured, sketch it. Note the little scale overhanging the edge of the eye, and see if you can make out what this scale represents. Cut the potato across, and notice the faint line which forms a sort of oval figure some distance inside the skin. Place the cut surface in red ink, allow the potato to stand so for many hours, and then examine, by slicing off pieces parallel to the cut surface, to see how far and into what portions the red ink has penetrated. Refer to the notes on the study of the parsnip (§ 45), and see how far the behavior of the potato treated with red ink agrees with that of the parsnip so treated. Cut a thin section at right angles to the skin, and examine with a high power. Moisten the section with iodine solution and examine again. Make a cross-section and a lengthwise section through the stained ring from the piece left standing in red ink, and examine first with a low, then with a high power. If possible secure a potato which has been sprouting in a warm place for a month or more (the longer the better), and look for evidences of the loss of material from the tuber. 99. Experiment 20. Use of the Corky Layer. — Carefully weigh a potato, then pare another larger one and cut portions from it until its weight is made approximately equal to that of the first one. Expose both freely to the air for some days and re-weigh. What does the result show in regard to the use of the corky layer of the skin ? 1 Examination of a lot of potatoes will usually discover specimens with an inch or more of attached stem. T4 ELEMENTS OF BOTANY. 100. Morphology of the Potato. —It is evident that in the potato we have to do with a very greatly modified form of stem. The corky layer of the bark is well represented, and the loose cellular layer beneath is very greatly developed ; wood is almost lacking, being present only in the very narrow ring which was stained by the red ink, but the pith is greatly developed and constitutes the principal bulk of the tuber. All this is readily understood if we consider that the tuber, buried in and supported by the earth, does not need the kinds of tissue which give strength, but only those which are well adapted to store the requisite amount of nourishment. 101. Structure of a Bulb; the Onion.1— Examine the external appearance of the onion and observe the thin membranaceous skin which covers it. This skin consists of the broad sheathing bases of the outer leaves which grew on the onion plant during the summer. Remove these and notice the thick scales (also formed from bases of leaves as shown in Fig. 37) which make up the substance of the bulb. Make a transverse section of the onion at about the middle and sketch the rings of which it is composed. Cut a thin section from the interior of the bulb, examine with a moderate power of the microscope, and note the. thin-walled cells of which it is composed. Split another onion from top to bottom and try to make out: (a) The plate or broad flattened stem inside at the base, Fig. 36 a; (6) The central bud ; (c) The bulb-scales; (d) In some onions (particularly large, irregular ones) the bulblets or side buds arising in the axes of the scales near the base, Fig. 36 b. Test the cut surface for starch. Since the onion grows so rapidly on being planted in the spring there must be a large supply of nutritive material in the bulb. Much of this is in the form of proteid material. The proteids ($ 35) constitute a class of animal and vege- table substances, very valuable for food, of which the whites 1 Probably a bulb with narrow scales like those of the lilies would be a more inter- esting form for study, but the onion is always and everywhere obtainable. LIVING PARTS OF THE STEM. ce of eggs and the sticky part of dough made from wheat flour are good examples. Nitric acid turns proteids yellow, and the addition of am- monia afterwards turns them deeper yellow or orange. As few other substances are affected in this way by nitric acid, this change of color is a very good test to show the presence of proteids. 102. Experiment 21.* Testing an Onion for Proteids. — Test a rather thick slice of onion by heating it in a porcelain evaporating dish with a little strong nitric acid until the latter begins to boil and the onion becomes somewhat softened.! Rinse off the slice of onion in a stream of water, then pour on it a few drops of ammonia water and observe what changes of color (if any) occur. Grape sugar is an important substance among those stored for food by the plant. It received its name from the fact that it was formerly obtained for chemical examination from grapes. Old dry raisins usually show little masses of whitish material scattered over the skin which are nearly pure grape sugar. Commercially it is now manufactured on an enor- mous scale from starch by boiling with diluted sulphuric acid. In the plant it is made from starch by processes as yet imperfectly understood, and another sugar, called maltose, is made from starch in the seed during germination. . Both grape sugar and maltose (and hardly any other sub- stances) have the power of producing a yellow or orange color and throwing down an orange or reddish deposit, when they are added to a brilliant blue alkaline solution of copper, known as Fehling’s solution.” The color or deposit will not appear until the solution has been heated to boiling. 1 Do not allow the acid to touch the hands, the clothing, or any metallic object. If it is desirable to show the result of the test to one or more classes, the portion of the onion stained yellow by the acid may be placed in a small wide-mouthed bottle with ground stopper, in which it may be kept for a long time and conveniently passed from hand to hand. 2 For the preparation of the solution see Appendix B. 76 ELEMENTS OF BOTANY. 1038. Experiment 22. Testing for Grape Sugar.— Heat to boiling in a test-tube or a small beaker some weak syrup of grape sugar or some honey, much diluted with water. Add Fehling’s solution, a few drops at a time, until a decided orange color appears. Repeat the test with the water in which some slices of onion have been boiled, filtering’ the water through a paper filter and heating again to boiling before add ing the test solution.! Does the onion contain grape sugar ? 1 The deposit will in this case, even if orange at first, finally become black, prok ably owing to the presence of sulphur in the onion. ‘CHAPTER VIII. ‘Buds. 104. Structure of Buds. — While studying twigs in their winter condition, as directed in §§ 58, 59, the student had occasion to notice the presence, position, and arrangement of buds on the branch, but he was not called upon to look into the details of their structure. The most natural time to do this is just before the study of the leaf is begun, since, as every one knows, leaves spring from buds and the rudiments of leaves in some form must be found there. -105. The Horse-Chestnut Bud. — Examine one of the lateral buds on a twig in its winter or early spring condition. Make a sketch of the external appearance of the buds as seen with a magnifying glass. The scales with which it is covered will be seen to overlap each other like shingles on a roof, and the thin edges of the scales fit very closely down over those beneath. Notice the sticky coating on the scales. Are the scales opposite or alternate ? Remove the scales in pairs, placing them in ones on a sheet of paper, thus : Make the distance from 1 to 1 as much as 6 or 8 inches. How many pairs are found ? Observe as the scales are removed whether the sticky coating is thicker on the outside or the inside of each scale, and whether it is equally abundant on all the successive pairs. What is the probable use of this coating ? Note the delicate veining of some of the scales as seen through the magnifying glass. ~1The best possible time for this examination is just as the buds are beginning to swell slightly in the spring. The buckeye will do for this examination, though it is on a good deal smaller scale than the horse-chestnut. Buds may be forced to open early by standing twigs in water in a very warm, light place. 18 ELEMENTS OF BOTANY. Describe the texture, thickness, transparency, color, and so on, of each pair of scales. Inside the innermost pair are found two forked woolly objects; what are these ? Compare with Fig. 75. Their shape could be more readily made out if the woolly coating were removed. Try the effect of immersing the inner portion of the bud for a few minutes in strong sulphuric acid to dissolve and remove the down, so as to show the parts more plainly. Can you suggest a use for the woolly coating ? Examine a terminal bud in the same way in which you have just studied the lateral bud. Does it contain any parts not found in the other ? What is the appearance of these parts ? What do they represent ? If there is any doubt about their nature, study them further on a horse-chestnut tree during and immediately after the process of leafing out in the spring. For comparison study at least one of the following kinds of buds in their winter or early spring condition: Hickory, butternut, beech, ash, magnolia (or tulip tree), lilac, balm of Gilead, cultivated cherry.? Fig. 56. — Transition from Bud-Seales to Leaves in the Common Currant. "106. Nature of Bud-Scales. — The fact that the bud-scales are in certain cases merely imperfectly developed leaves is often clearly manifest from the series of steps connecting the bud-seale on the one hand with the young leaf on the other, which may be found in many opening buds, as illustrated by Fig. 56. In other buds the scales are not imperfect leaves, but the little appendages (stipules, § 117) which occur at the’ ’1The acid must not be allowed to get on the hands, the table, or the clothes, or it will cause much trouble. Remove it by rinsing in plenty of water. >2Consult the account of the mode of studying buds in Miss Newell’s Outlines, Part Il. If some of the buds are studied at home, pupils will have a better chance to examine at leisure the unfolding process. BUDS. 79 bases of leaves. This kind of bud-scale is especially well shown in the magnolia and the tulip tree. 107. Naked Buds.— All of the buds above-mentioned are winter buds, capable of living through the colder months of the year, and are scaly buds. In the herbs of temperate climates, and even in shrubs and trees of tropical regions, the buds are often naked, — is nearly or quite destitute of scaly coverings. Make astudy ofthe naked buds of any convenient herb, such as one of the common “geraniums” (pelargonium), and record what you find in it. *108. Position of Buds.— The distinc- tion between lateral and terminal buds has al- ready been alluded to. The plumule is the first terminal bud which the plant produces. Lateral buds are usu- ally axillary, as shown in Fig. 57. But not in- frequently there are several buds grouped in , | ; Fic. 57.— Alternate Leaves of Cultivated Cherry, some way about a single with Buds in their Axils, in October. leaf-axil,either one above the other, as in the black walnut, Fig. 58, or grouped side by side, as in the red maple and the cherry, Fig. 59. In these cases all the buds except the axillary one are called accessory or supernumerary buds. * 109. Leaf-Buds and Flower-Buds ; the Bud an Undeveloped Branch. — Such buds as the student has so far examined for op Pqsuulcs he 4 a appa reve ay wnih bald SS \ awe a \ 80 ELEMENTS OF BOTANY. himself are not large enough to show in the most obvious way the relation of the parts and their real nature. Fortunately, it is easy to obtain a gigantic bud which illustrates perfectly the struc- ture and arrangement of buds in general. Examine and sketch a cabbage which has been split lengthwise through the centre! and note (a) The short, thick, conical stem. (b) The crowded leaves which arise from the stem, the lower and outer ones largest and most mature, the upper and innermost ones the smallest of the series. Compare the section of the cabbage with Fig. 60. Most of the buds so far con- sidered are leaf-luds, that is, their inner parts will develop into leaves, and their central axes into stems; but some were mixed buds, that is, they con- tained both leaves and flowers in an undeveloped condition. Flower-buds contain the rudi- ments of flowers only. Sometimes, as in the black Fig, 58.—A Twig of Black Walnut. walnut, the leaf-buds and flower- sc, scar lef? by fallen leaf; justabove . bads are readily @istinpuishamre this is an ordinary bud, and still ; - : : higher up, acc, an accessory bud. by their difference in form, while in other cases, as in the culti- vated cherry, the difference in form is but slight. 1 Half of a cabbage will be enough for the entire division. BUDS. 81 The rings of scars about the twig, shown in Figs. 23 and 59, mark the place where the bases of bud-scales were attached. A little examination of the part of the twig which lies outside of this ring, as shown in Fig. 23, will lead one to the conclu- sion that this portion has all grown in the one spring and summer since the bud-scales of that particular ring dropped off. Following out this suggestion, it is easy to reckon the age of any moderately old portion of a branch, since it is equal to the number of a ee ' Fie. 60.—I1, a Twigof European * Fie. 59.— A Slowly grown Twig of Cherry, Elm. II, a Longitudinal Section of three inches long and about ten years old. the Buds of I, considerably magni- The more pointed terminal bud is a leaf-bud, __ fied. the more obtuse accessory buds, acc, are flower- a, the axis of the bud, which will buds. elongate into a shoot ; b, leaf-scars. segments between the rings. In rapidly growing shoots of willow, poplar, and similar trees, five or ten feet of the length may be the growth of a single year, while in the lateral twigs of the hickory, apple, or cherry the yearly increase may be but a fraction of an inch. Whatever the amount of this 82 ELEMENTS OF BOTANY. growth, it is but the lengthening out and development of the bud, which may be regarded as an undeveloped stem or branch, with its internodes so shortened that successive leaves seem almost to spring from the same point. -110. Vernation. — Procure a considerable number of buds which are just about to burst, and others which have begun to open. Cut each across with a razor or very sharp scalpel ; examine first with the magnify- < ASN) Se Aisinn yi ea TUDSSS Ss mee ee ATS ST or Is Sere : ) Wp (i = - \i vi el LNG = \ N p LL POS NRL ea j * Fic. 61. — Types of Vernation. 1, 2, cherry ; 3, 4, European walnut; 5, 6, snowball; 7, lady’s-mantle ; 8, wood sorrel. ing glass, and then with the lowest power of the microscope. Pick to pieces other buds of the same kinds under the magnifying glass, and report upon the manner in which the leaves are packed away. The arrangement of leaves in the bud is called vernation ; some of the principal modes are shown in Fig. 61. In the cherry the two halves of the leaf are folded together flat, with BUDS. 83 the under surfaces outward; in the walnut the separate leaflets, or parts of the leaf, are folded flat and then grouped into a sort of cone ; in the snowball each half of the leaf is plaited in a somewhat fan-like manner, and the edges of the two halves are then brought round so as to meet; in the lady’s-mantle the fan-like plaiting is very distinct ; in the wood sorrel each leaflet is folded smoothly, and then the three leaflets packed closely side by side. All these modes of ver- nation and many others have received accurate descriptive names by which they are known to botanists. -111. Importance of Vernation.— The significance of verna- tion is best understood by considering that there are two important purposes to be served; the leaves must be stowed as closely as possible in the bud, and upon beginning to open they must be protected from too great heat and dryness until they have reached a certain degree of firmness. It may be inferred from Fig. 61 that it is common for very young leaves to stand vertically. This protects them considerably from the scorching effect of the sun at the hottest part of the day. Many young leaves, as for instance those of the silver-leafed poplar, the pear, the beech, and the mountain ash, are sheltered and protected from the attacks of small insects by a coating of wool or down, which they afterwards lose. Those of the tulip tree are enclosed for a little time in a thin pouch, formed from the bud-scales,? and thus entirely shielded from direct contact with the outside air. 112. Dormant Buds. — Generally some of the buds on a branch remain undeveloped in the spring, when the other buds are beginning to grow, and this inactive condition may last for many seasons. Finally the bud may die, or some injury to the tree may destroy so many other buds as to leave the dormant ones an extra supply of nourishment, and this, with other causes, may force them to develop and to grow into branches. 1 These are in this case stipules, § 117. 84 ELEMENTS OF BOTANY. Sometimes the tree fails altogether to produce buds at places where they would regularly occur. In the lilac the terminal bud usually fails to appear, and the result is constant forking of the branches. 113. Adventitious Buds.— Buds which occur in irregular places, that is, not terminal nor in or near the axils of leaves, are called adventitious buds ; they may spring from the roots, as in the silver-leafed poplar, or from the sides of the trunk, as in our American elm. In many trees, for instance wil- lows and maples, they are sure to appear after the trees . have been cut back. Willows are thus cut back or pollarded, as shown in Fig. 62, in order to cause them to produce a large crop of slender twigs suitable for basket-making. Leaves rarely produce buds, but a few kinds do so when. they are injured; and those of the bryophyllum, a plant 225 62. Ng as formed SIR Adven- maori ee nee titious Buds on Pollarded Willows. ever, almost always send out buds from the margin when they are removed from the plant while they are still green and fresh. ‘114. Experiment 23.—Pin up a bryophyllum leaf on the wall of the room or lay it onthe surface of moist earth, and follow, day by day, the formation and development of the buds which it may produce. This plant seems to rely largely upon leaf-budding to reproduce itself, for in a moderately cool climate it rarely flowers or seeds, but drops its living leaves freely, and from each such leaf one or several new plants may be produced. CHAPTER IX. Leaves. 115. The Elm Leaf. —Sketch the leafy twig of elm that is supplied to you.! Report on the following points : (a) How many rows of leaves ? (6) How much overlapping of leaves when the twig is held with the upper sides of the leaves toward you? Can you suggest a reason for a g FIG. 63. — General Outline of Leaves. a, linear ; b, lanceolate; c, wedge-shaped ; d, spatulate ; e, ovate; /, obovate ; g, kidney-shaped ; h, orbicular ; i, elliptical. *1 Any elm will answer the purpose. Young strong shoots which extend horizon- tally are best, since in these leaves are most fully developed and their distribution along the twig appears most clearly. Other good kinds of leaves with which to begin the study, if elm leaves are not available, are those of beech, oak, willow, peach, 86 ELEMENTS OF BOTANY. this? Are the spaces between the edges of the leaves large or small compared with the leaves themselves ? Pull off a single leaf and make a very careful sketch of its under surface, about natural size. Label the broad expanded part the blade, and the stalk by which it is attached to the twig, leaf-stalk or petiole. Study the outline of the leaf and answer these questions : (a) What is the shape of the leaf, taken as a whole? (See Fig. 65.) Is the leaf bilaterally symmetrical, i.e., is there a middle line running Ve Ae Va VEG Fic. 64. — Shapes of Tip of Leaf. I, mucronate, the midrib prolonged into a hard short point; II, cuspidate, tapering into astiff point ; III, acute ; IV, rounded; 1! V, acuminate or taper-pointed ; VI, retuse, Fic. 65.—Shapes of Bases of with the rounded end slightly notched ; Leaves. VII, emarginate, deeply notched; VIII, 1, heart-shaped (unsymmetrically) ; truncate, with the end cut off rather 2, arrow-shaped ; 3, halberd- squarely. shaped. through it lengthwise, along which it could be so folded that the two sides would precisely coincide ? (b) What is the shape of the tip of the leaf? (See Fig. 64.) (c) Shape of the base of the leaf. (See Fig. 65.) (d) Outline of the margin of the leaf? (See Fig. 66.) cherry, apple. Most of the statements and directions above given would apply to any of the leaves just enumerated. If this chapter is reached too early in the season to admit of suitable material being procured for the study of leaf arrangement, that topic may be omitted until the leaves of forest trees have sufficiently matured. i Any form intermediate between III and IV would be called obtuse. LEAVES. 87 Notice that the leaf is traversed lengthwise by a strong midrib and that many so-called veins run from this to the margin. Are these veins parallel? Hold the leaf up toward the light and see how the main veins are connected by smaller veinlets. Examine with your glass the leaf as held to the light and make a careful sketch of portions of one or two veins and the intersecting veinlets. How is the course of the veins shown on the upper surface of the leaf ? ees rg ‘CHAPTER XIV. - Inflorescence, or Arrangement of Flowers on the Stem. , 164. Regular Positions for Flower-buds. — Flower-buds, like leaf-buds, occur regularly either in the axils of leaves or at the end of the stem or branch (see § 187) and are therefore either axillary or terminal. 165. Axillary and Solitary Flowers ; Indeterminate Inflores- cence. — The simplest possible arrangement for flowers which arise from the axils of leaves is to have a single flower spring from each leaf-axil. Fig. 104 shows how this plan appears in a plant with opposite leaves. As long as the stem continues to grow, the production of new leaves may be followed by that of new Fie. 104. — Axillary and Solitary Flow- ’ Fie. 105.— Raceme of Common Red Currant; p., ers of Pimpernel. peduncle; p’., pedicel; br., bract. flowers. Since there is no definite limit to the number of flowers which may appear in this way, the mode of flowering just described (with many others of the same general char- acter) is known as indeterminate inflorescence. 2 ba ELEMENTS OF BOTANY. The Raceme and Related Forms. —If the leaves along the stem were to become very much dwarfed and the flowers brought closer together, as they frequently are, a kind of flower-cluster like that of the currant (Fig. 105) or the lily of the valley would result. Such an inflorescence is called a raceme ; the main flower stalk is known as the peduncle ; the little individual flower stalks are pedicels, and the small, more or less scale-like leaves of the peduncle are bracts.’ Frequently the lower pedicels of a cluster on the general plan of the raceme are longer than the upper ones and make a somewhat flat-topped cluster, like that of. the hawthorn, the sheep laurel, or the trumpet creeper. This is called a corymb. In many cases, for example the parsnip, the sweet cicely, the gin- seng and the cherry, a group of pedicels of nearly equal length spring from about the same point. This produces a flower-cluster called the umbel (Fig. 106). -166. Sessile Flowers and Flower- Clusters. —Often the pedicels are F1G.106.—Simple Umbelof Cherry. Wanting, or the flowers are sessile, and then a modification of the raceme is produced which is called a spike, like that of the plantain (Fig. 107). The willow, alder, birch, poplar, and many other common trees bear a short, flexible, rather scaly spike (Fig. 108), which is called a catkin. The peduncle of a spike is often so much shortened as to bring the flowers into a somewhat globular mass. This is ' 1It is hardly necessary to say that the teacher will find it better in every way, if material is abundant, to begin the study of flower-clusters with the examination of typical specimens by the class. ARRANGEMENT OF FLOWERS ON THE STEM. 133 called a head (Fig. 109). Around the base of the head usually occurs a circle of bracts known as the involucre, well shown in Fig. 110. The same name is given to a set of bracts which often surround the bases of the pedicels in an umbel. 167. The Anthodium. — The plants of one large group, of which the dandelion, the daisy, the thistle, and the sunflower I Fie. 108. —Catkins of Willow. I, Staminate flowers ; LI, Pistillate flowers. Fie. 107.— Spike of Plantain. Fic. 109. — Head of Eryngo. are well-known members, bear their flowers in close involu- crate heads on a common receptacle. The whole cluster looks so much like a single flower that it is usually taken for one by non-botanical people. This kind of head has received the special name of anthodiuwm. In many of the largest and 134 ELEMENTS OF BOTANY. most showy anthodia like the sunflower and the daisy there are two kinds of flowers, the ray-flowers, around the margin, and the tubular disk-flowers of the interior of the head. This kind of cluster is well illustrated by Fig. 110. The early botanists supposed the whole flower cluster to be a single compound flower. This belief led to their naming one family of plants Composite, that is plants with compound flowers. In such anthodia as those of the thistle, the cud-weed and the - everlasting there are no ray-flowers, and in others, like those Fic. 110 .— Vertical Section of Anthodium of a Sunflower (diagram). inv., involucre; ray, ray-flower; ¢tw.-f., tubular flowers of disk; r., common receptacle. of the dandelion and the chicory, all the flowers are ray- flowers. -168. Compound Flower-Clusters. —If the pedicels of a raceme branch, they may produce a compound raceme, or panicle, like that of the oat (Fig. 111).* Other forms of compound racemes have received other names. An umbel may beGome compound by the branching of its ’ 1 Panicles may also be formed by compound cymes, see § 165. ARRANGEMENT OF FLOWERS ON THE STEM. 135 flower-stalks (Fig. 112), each of which then bears a little umbel, an umbellet. Fic. 112. —Compound Um- Fiac. 111. — Panicle of Oat. bel of Chervil. -169. Inflorescence Diagrams.— The plan of inflorescence may readily be indicated by diagrams like those of Fig. 113. A B FIG. 113. —Diagrams of Inflorescence. A, panicle; B,raceme; C,spike; D,umbel1; £, head.1 » 1In these diagrams the balls, which symbolize flowers, should be largest at the outside and diminish regularly toward the centre, to show that the outermost flowers are the oldest. 136 ELEMENTS OF BOTANY. The student should construct such diagrams for some rather com- plicated flower-clusters like those of the grape, horse-chestnut or buck- eye, hardhack, vervain, or many grasses. -170. Terminal Flowers. Determinate Inflorescence. — The terminal bud of a stem may be a flower-bud. In this case the direct growth of the stem is stopped or determined by the appearance of the flower, hence such plants are said to have a determinate inflorescence. The simplest possible case of this kind is that in which the stem bears but one flower at its summit. ‘171. The Cyme.—Very often flowers appear from lateral (axil- lary) buds, below the terminal flower, and thus give rise to a flower-cluster called a cyme. This may have only three flowers, and in that case would look very much like a three-flowered umbel. But in the raceme, corymb, and umbel the order of flowering is from below upward, or from the out- side of the cluster inward, because the lowest, or the outermost flowers, are the oldest, while in * Fig. 114.—Compound Cyme of determinate forms of inflorescence Mouse-Ear Chickweed. the central flower is the oldest, and therefore the order of blossom- ing is from the centre outwards. Cymes are very commonly compound, like those of the elder and of many plants of the pink family, such as the Sweet William and the mouse-ear chickweed (Fig. 114). They may also, as already mentioned, be panicled, thus making a cluster much like Fig. 113 A. é, the terminal (oldest) flower. \. % CHAPTER XV. The Study of Typical Flowers.! (Only one of the three flowers described to be studied by aid of these directions. ) 172. The Flower of the Trillium. — Cut off the flower stalk rather close to the flower ; stand the latter, face down, on the table, and draw the parts then shown. Label the three green leaflike parts sepals, and the three white parts which alternate with these petals. Turn the flower face up, and make another sketch, labeling the parts as before, together with the yellow enlarged extremities or anthers of the six stamens. Note the way in which the petals alternate with the sepals; i.e., each petal springs from a point just above the space between two sepals. Observe the arrangement of the edges of the petals toward the base — one petal with both edges outside the other two, one with both edges inside, the third with one edge in and one out. Note the veining of both sepals and petals, more distinct in the former.? 1The buttercup and the trillium are suggested because they are early spring flowers, of which some species may be found in most of the states east of the Missis- sippi. They are tolerably large flowers, simple in their plan, differ much in the number and shape of the floral organs, and are respectively somewhat typical of large groups. Other flowers should be studied in much detail when the class is completing Chapter XIX. The description of the flower of the trillium, as found in this chapter, is true in details only of the white variety of T. erectum, but the account given would serve as a guide for the study of any of our species. The buttercup flower here described is that of Ranunculus bulbosus, but the description will hold good in the main for any of the larger-flowered species. The tulip is perhaps the simplest polypetalous and regular flower which can be had of florists as early as May 1, and therefore in ample time to serve as an introduction (for city pupils) to the study of floral struc- tures. If the expense of procuring tulips enough for class study should make it impossible to use them, the teacher could easily make out a set of directions for the study of some such flower as the (slightly irregular) pelargoniums. Sedum acre can very easily be supplied in quantity, if arrangements are made with florists to have it ready. 2JIn flowers with delicate white petals the distribution of the fibro-vascular bundles in these can usually be readily shown by standing the freshly-cut end of the peduncle in red ink for a short time, until colored veins begin to appear in the petals. The experiment succeeds readily with apple, cherry, or plum blossoms ; with white gilliflower the coloration is very prompt. Lily of the valley is perhaps as interesting a flower as any on which to try the experiment, since the well-defined stained stripes are separated by portions quite free from stain, and the pistils are also colored. 138 ELEMENTS OF BOTANY. Pull off a sepal and make a sketch of it, natural size ; then remove a petal, flatten it out, and sketch it, natural size. Observe that the flower-stalk is enlarged slightly at the upper end into a rounded portion, the receptacle, from which all the parts of the flower spring. Note how the six stamens arise from the receptacle, three of them from points just within and above the origins of the petals, the other three from points between the petals. Remove the remaining petals (cutting them off near the bottom with a knife), and sketch the stamens, together with another object, the pistil, which stands in the centre. Cut off one stamen, and sketch it as seen through the magnifying glass. Notice that it consists of a greenish stalk, the filament, and a broader portion, the anther, Fig. 116, B. The latter is easily seen to contain a prolongation of the green filament, nearly surrounded by a yellow sub- stance. In the bud it will be found that the anther consists of two long pouches or anther-cells, which are attached by their whole length to the filament, and face inward (towards the centre of the flower). When the flower is fairly open, the anther-cells have already split down their margins, and are discharging a yellow, somewhat sticky powder, the pollen. Examine one of the anthers with the microscope, using the two-inch objective (No. 1), and sketch it. Cut away all the stamens, and sketch the pistil. It consists of a stout lower portion, the ovary, which is six-ridged or angled, and which bears at its summit three slender stigmas. In another flower, which has begun to wither (and in which the ovary is larger than in a newly-opened flower), cut the ovary across about the middle, and try to make out with the magnifying glass the number of chambers or cells which it contains. Examine the cross-section with the two-inch objective ; sketch it, and note particularly the appearance and mode of attachment of the undeveloped seeds or ovules with which it is filled. Make a vertical section of another rather mature ovary, and examine this in the same way. Using a fresh flower, construct a diagram to show the relation of the parts on an imaginary cross-section, as illustrated in Fig. 135.1 Con- struct a diagram of a longitudinal section of the flower, on the general plan of those in Fig. 133, but showing the contents of the ovary. 1It is important to notice that such a diagram is not a picture of the section actually produced by cutting through the flower crosswise at any one level, but that it is rather a projection of the sections through the most typical part of each of the floral organs. ; a THE STUDY OF TYPICAL FLOWERS. 139 173. The Flower of the Tulip.1— Make a diagram of a side view of the well-opened flower, as it appears when standing in sunlight. Observe that there are three outer flower leaves and three inner ones.? Label the outer set sepals and the inner set petals. In most flowers the parts of the outer set are greenish, and those of the inner set of some other color. In cases like the present, where the coloration is the same throughout, the name perianth, meaning around the flower, is applied to the two sets taken together. Note the white waxy bloom on the outer surface of the three outer segments of the perianth. What is the use of this? Note the man- ner in which the three inner segments of the perianth arise from the top of the peduncle, just above and alternating with the points of attachment of the three outer segments. In a flower not too widely opened, note the relative position of the three inner segments of the perianth, one wholly outside the other two, one wholly inside, the third with one edge in and one edge out. Remove one of the sepals by cutting it off close to its attachment to the peduncle, and examine the veining by holding it up in a strong light and looking through it. Make a sketch to show the general outline and the shape of the tip. Examine a petal in the same way, and sketch it. Cut off the remaining portions of the perianth, leaving about a quarter of an inch at the base of each segment. Sketch the upright, triangular, pillar-like object in the centre, label it pistil, sketch the six organs which spring from around its base, and label these stamens. Note the fact that each stamen arises from a point just above and within the base of a segment of the perianth. Each stamen consists of a somewhat conical or awl-shaped portion below, the filament, surmounted by an ovate linear portion, the anther. Sketch one of the stamens about twice natural size. Is the attachment of the anther to the filament such as to admit of any nodding or twisting movement of the former? Ina young flower, note the two tubular pouches or anther-cells of which the anther is composed, and the slits by which these open. Observe the dark-colored pollen which escapes from the anther-cells and adheres to paper or to the fingers. Examine a newly opened anther with the micro- scope, using the two-inch objective, and sketch it. Cut away all the stamens and note the two portions of the pistil, a triangular prism, the ovary, and three roughened scroll-like objects at the 1 Tulipa Gesneriana. As the flowers are rather expensive, and their parts are large and firm, it is not absolutely necessary to give a flower to each pupil, but some may be kept entire for sketching and others dissected by the class. All the flowers must be single. 2 Best seen in a flower which is just opening. 140 ELEMENTS OF BOTANY. top, the three lobes of the stigma. Make a sketch of these parts about twice the natural size, and label them. Touch a small camel’s-hair pencil to one of the anthers, and then transfer the pollen thus removed to the stigma. This operation is merely an imitation of the work done by insects which visit the flowers out of doors. Note how readily the pollen clings to the rough stigmatic surface. Examine this adhering pollen with the two-inch objective, and sketch a few grains of it, together with the bit of the stigma to which it clings. Compare this drawing with Fig. 140. Make a cross-section of the ovary about midway of its length, and sketch the section as seen through the magnifying glass. Label the three chambers shown, cells of the ovary, and the white egg-shaped objects within, ovules. Make a longitudinal section of another ovary, taking pains to secure a good view of the ovules, and sketch as seen through the magnifying glass. Making use of the information already gained and the cross-section of the ovary as sketched, construct a diagram of a cross-section of the entire flower on the same general plan as those shown in Fig. 135.3 Split a flower lengthwise,* and construct a longitudinal section of the entire flower on the plan of those shown in Fig. 133, but showing the contents of the ovary. 174. The Flower of the Buttercup. —Make a diagram of the mature flower as seen in a side view, looking a little down into it. Label the five pale greenish yellow, hairy, outermost parts sepals, and the five® larger bright yellow parts above and within these petals, and the yellow-knobbed parts which occupy a good deal of the interior of the flower, stamens. Note the difference in the position of the sepals of a newly opened flower and that of the sepals about a flower which has opened as widely as possible. Note the way in which the petals alternate with the sepals, i.e., each petal springs from a point just above the space between two sepals. In an opening flower, observe the arrangement of the edges of the petals, two entirely outside the others, two entirely inside, one with one edge in and the other out. Cut off a sepal and a petal, each close to its attachment to the flower ; 1 Notice that the word cell here means a comparatively large cavity, and is not used in the same sense in which we speak of a wood cell or a pith cell. 2 The section will be more satisfactory if made from an older flower, grown out of doors, from which the perianth has fallen. 3 Consult also the footnote on p. 138. # One will do for an entire division of the class. 5 Sometimes more. i ale THE STUDY OF TYPICAL FLOWERS. 141 place both, face down, on a sheet of paper, and sketch about twice the natural size. Describe the difference in appearance between the outer and the inner surface of the sepal and of the petal. Note the little scale at the base of the petal, inside. Strip off all the parts from a flower which has lost its petals, until nothing is left but a slender conical object a little more than an eighth of an inch in length. This is the receptacle or summit of the peduncle. In a fully opened flower, note the numerous yellow-tipped stamens, each consisting of a short stalk, the filament, and an enlarged yellow knob at the end, the anther. Note the division of the anther into two portions, which appear from the outside as parallel ridges, but which are really closed tubes, the anther-cells. Observe in the interior of the flower the somewhat globular mass (in a young flower almost covered by the stamens). This is a group of pistils. Study one of these groups in a flower from which the stamens have mostly fallen off, and make an enlarged sketch of the head of pistils. Remove some of the pistils from a mature head, and sketch a single one as seen with the magnifying glass. Label the little knob or beak at the upper end of the pistil stigma, and the main body of the pistil ovary. Make a section of one of the pistils, parallel to the flattened surfaces, like that shown in Fig. 169, and note the partially matured seed or ovule within. CHAPTER XVI. Plan and Structure of the Flower and its Organs. 175. Parts or Organs of the Flower. — Most showy flowers consist, like those studied in the preceding chapter, of four circles or sets of organs, the sepals, petals, stamens, and pistils. The sepals, taken together, constitute the calyx, the petals, taken together, constitute the corolla, Fig. 115." Some- \ oe Fic. 115.— The Parts of the Flower.? cal., calyx; cor., corolla; stam., stamens ; pist., pistil. times it is convenient to have a word to comprise both calyx and corolla; for this the term perianth is used. A flower which contains all four of these sets is said to be complete. Since the work of the flower is to produce seed, and seed-forming is due to the codperation of stamens and pistils, these are known 1 The flower of the waterleaf or Hydrophyllum, modified by the omission of the hairs on the stamens, is here given because it shows so plainly the relation of the parts. 2 Hydrophyllum Canadense, with appendages in throat of corolla and hairs on stamens omitted. STRUCTURE OF THE FLOWER AND ITS ORGANS. 143 as the essential organs, Fig. 116. The simplest possible pistil is a dwarfed and greatly modified leaf ($ 188), adapted into a seed-bearing organ. Such a pistil may be one-seeded, as in Fig. 169, or several-seeded, as in the right-hand part of Fig. 171; it is called a carpel. The calyx and corolla are known Fic. 116.— The Essential Organs. A, stamens and pistil of a tulip (the perianth removed) ; s, stamens; p, pistil; B,aseparate stamen, with its anther a discharging pollen; /, the filament ; C, pollen-grains. as the floral. envelopes. Flowers which have the essential organs are called perfect flowers. They may therefore be perfect without being complete. In cases where the perianth contains only one row of parts, it is assumed that the petals are lacking. Such imperfect flowers are said to be apetalous, Fig. 117. 176. Regular and Symmetrical Flowers. —A flower is regular if all the parts of the same set or circle are alike in size and shape, as in the stonecrop, Fig. 118. Such flowers as that of the violet, the monkshood, P : Fic. 117.—Apetalous the nasturtium, or the laburnum, Fig. 119, — Mowerof European) are irregular. Symmetrical flowers are Wild Ginger. those whose calyx, corolla, circle of stamens and set of carpels consists each of the same number of parts, or in which the 144 ELEMENTS OF BOTANY. number in every case is a multiple of the smallest number found in any set. The stonecrop is symmetrical, since it has five sepals, five petals, ten stamens, and five carpels. Roses, mallows, and mignonette are familiar examples of flowers FIG. 118.— Flower of Stonecrop. I, entire flower (magnified); I, vertical section (magnified), which are unsymmetrical because they have a large indefinite number of stamens; the Portulaca is unsymmetrical since it has two divisions of the calyx, five or six petals, and seven to twenty stamens. Fic. 119. — Irregular Corolla of Laburnum. I, side view ; LI, front view. 177. The Receptacle. — The parts of the flower are borne on an expansion of the peduncle, called the receptacle. Usually, as in the flower of the grape, Fig. 145, this is only a slight enlargement of the peduncle, but in the lotus and the magnolia the receptacle is of great size, particularly after the STRUCTURE OF THE FLOWER AND ITS ORGANS. 145 petals have fallen and the seed has ripened. The receptacle of the rose, Fig. 120, is hollow and the pistils arise from its interior surface. 178. Imperfect or Separated Flowers. —The stamens and pistils may be produced in separate flowers, which are, of course, imperfect. This term does not imply that such flowers do their work any less perfectly than others, but only that they have not both kinds of essential organs. In the very simple imperfect flowers of the willow, Fig. 121, each flower of the catkin, Fig. 108, consists merely of a pistil or a group of (usually two) stamens, springing from the axil of a small bract. Staminate and pistillate flowers may be borne on different plants, as they are in the willow, or they may be borne on the same plant, as in the hickory and the hazel, among trees, or in the castor-oil plant, Indian corn, Fie. 120.—A Rose, and the begonias. When staminate and pis- Pegs & ari tillate flowers are borne on separate plants, such a plant is said to be diewcious, that is, of-two-households ; when both kinds of flower appear on the same individual, the plant is said to be monecious, that is, of-one-household. 179. Study of Imperfect Flowers. —Examine, draw, and describe the imperfect flowers of some of the following dicecious plants and one of the monecious plants! : early meadow rue, Dicecious plants willow, poplar. walnut, oak, chestnut, Moneecious plants hickory, alder, beech, ii birch, hazel, begonia. 1¥For figures and descriptions of these or allied flowers consult Gray’s Manual of Botany, Emerson’s Trees and Shrubs of Massachusetts, Newhall’s Trees of the Northern United States, or Le Maout and Decaisne’s T'raité Général de Botanique. 146 ELEMENTS OF BOTANY. 180. Union of Similar Parts of the Perianth. — The sepals may join or cohere to form a calyx which is more or less entirely united into one piece, as in Figs. 115, 117. In this case the calyx is said to be gamosepalous, that is, of-wedded- sepals. In the same way the corolla is frequently gamo- petalous, as in Figs. 122,123. Special names are given to a large number of forms of the gamosepalous corolla, and these names are of great use in accurately describing plants; only a few of these names are here given, in connection with the figures. When the parts of either circle of the perianth are wholly i Il Fic. 122. — Bell-Shaped Fia. 121. — Flowers of Willow (magnified). Corolla of Bellflower I, staminate flower ; II, pistillate flower. (Campanula). unconnected with each other, that is, polysepalous or poly- petalous, they are said to be distinct. 181. Parts of the Stamen and the Pistil.— The stamen usually consists of a hollow portion, the anther, Fig. 127 6, borne on a stalk called the filament, Fig. 1274. Inside the anther is a powdery or pasty substance called pollen. Not infrequently the filament is lacking. The pistil usually con- sists of a small hollow chamber, the ovary, which contains the ovules or rudimentary seeds, a slender portion or stalk, called the style, and at the top of this a ridge, knob, or point STRUCTURE OF THE FLOWER AND ITS ORGANS. 147 called the stigma. These parts are all shown in Fig. 128. In many pistils the stigma is borne directly on the ovary, as in Fig. 145. 182. Union of Stamens with each Other.— Stamens may be wholly unconnected with each other or distinct, or they may cohere by their filaments into a single group, when they are said to be monadel- phous, of-one-brotherhood, Fig. 129, into two groups (diadelphous), Fig. 130, or into many groups. In some flowers the stamens are held together in a ring by their coherent anthers, Fig. 131. 183. Union of Pistils. — The pistils may be entirely separate from each other, distinct and simple as they are in the buttercup and the stonecrop, or several may join to form one compound pistil of more or less united carpels. In the latter case the union generally affects the Fre. 123. —Salver-Shaped ovaries, but often leaves the styles sep- eee a cada arate, or 1t may result in joining ovaries and styles, but leave the stigmas separate or at any rate lobed, so as to show of how many separate carpels the compound pis- til is made up. Even when there is no external sign to show the compound nature of the pistil, it can usually be recognized from the study of a cross- section of the ovary. 184. Cell of the Ovary; Placentas. —Compound ovaries are very commonly several-celled, that is, they consist of a number of separate cells’ or chambers. Fig. 132 B shows a Fic. 124. — Wheel-Shaped Corolla of Potato. 1 Notice that the word cell is here used in an entirely different sense from that in which it has been employed in the earlier chapters of this book. As applied to the - Ovary, it means a chamber or compartment. 148 ELEMENTS OF BOTANY. three-celled ovary, seen in cross-section. The ovules are not borne indiscriminately by any part of the lining of the ovary. In one-celled pistils they frequently grow in a line running along one side of the ovary, as in the pea pod, Fig. 176. The ovule-bearing line is called a placenta; in compound pistils there are commonly as many placentas as there are separate pistils joined to make the compound one. Placentas on the wall of the ovary, like those in Fig. 132 A, are called parietal placentas ; those which occur as at B, in the same figure, are Silene Sf. Sere ee OU, Sees S Fic. 125. — Tubu- Fic.127.— Parts Fic. 128.— Parts of the lar Corolla,from Fic. 126. — Labiate of a Stamen, Pistil. Head of Bache- orRingentCorolla a, filament; 5, ov., ovary ; sty., style; lor’s Button. of Dead Nettle. anther. stig., stigma. said to be central, and those which, like the form represented in C of the same figure, consist of a column rising from the bottom of the ovary, are called free central placentas. 185. Union of Separate Circles. —'The members of one of the circles of organs of which the flower is composed may join each other or become adnate, adherent, or consolidated. In Fig. 117 the calyx-tube is adnate to the ovary. In this case the parts of the flower do not all appear to spring from the receptacle. Fig. 133 illustrates three common cases as regards insertion of the parts of the flower. In I they are > STRUCTURE OF THE FLOWER AND ITS ORGANS. 149 all inserted on the receptacle, and the corolla and stamens are said to be hypogynous, that is, beneath-the-pistil. In I the petals and the stamens appear as if they had grown fast to the calyx for some distance, so that they surround the pistil, and they are therefore said to be perigynous, that is, around-the-pistil. In III all the parts are free or uncon- Fia@. 130. — Diadelphous Stamens of Sweet Pea. Fic. 129. —_Mona- delphous Stamens of Mallow. aoe | a 7 (3 f) Fic. 131. — Stamens of - a Thistle, with An- A B C thers United into a Fic. 132. — Principal Types of Placenta. Ring. A, parietal placenta; B, central placenta; a, united anthers; /, C, free central placenta; A and B, trans- filaments, bearded verse sections ; C, longitudinal section. on the sides. solidated, except the petals and stamens; the stamens may be described as epipetalous, that is, growing-on-the-petals. Sometimes some or all of the other parts seem to grow out of the ovary, and such parts are said to be epigynous, that 1s, on-the-ovary, like the petals and stamens of the white water- lily, Fig. 134. 186. Floral Diagrams.— Sections (real or imaginary) 150 ELEMENTS OF BOTANY. through the flower lengthwise, like those of Fig. 133, help greatly in giving an accurate idea of the relative position of the floral organs. Still more important in this way are cross-sections, which may be recorded in diagrams like those of Fig. 185.1 In constructing such diagrams it will often be necessary to suppose some of the parts of the flower to be raised or lowered from their true position, so as to bring iE II it FIG. 133.— Insertion of the Floral Organs. I, Hypogynous, all the other parts on the receptacle, beneath the pistil; II, Perigynous, petals and stamens apparently growing out of the calyx, around the pistil; IJ, Fic. 134.— White Water-Lily. The corolla hypogynous, stamens epi- inner petals and the stamens grow- petalous. ing from the ovary. them into such relations that all could be cut by a single section. This would, for instance, be necessary in making a diagram for the cross-section of the flower of the white water-lily, of which a longitudinal section is shown in Fig. 134.? Construct diagrams of the longitudinal section and the transverse section of several large flowers, following the 1For floral diagrams see Thomé’s Botany, Le Maout and Decaisne’s Traité Général de Botanique, or Eichler’s Bliithendiagramme. 2 It is best to begin practice on floral diagrams with flowers so firm and large that actual sections of them may be cut with ease and the relations of the parts in the section readily made out. The tulip is admirably adapted for this purpose. STRUCTURE OF THE FLOWER AND ITS ORGANS. 151 method indicated in Figs. 133 and 135, but making the longi- tudinal.section show the interior of the ovary.’ I 1} Ill FIG. 135. — Diagrams of Cross-Sections of Flowers. I, columbine ; II, heath family ; ILI, iris family. In each diagram the dot along- side the main portion indicates a cross-section of the stem of the plant. In IJ, every other stamen is more lightly shaded because some plants of the heath family have 5 and some 10 stamens. 1 Among the many excellent early flowers for this purpose may be mentioned trillium, blood-root, dog-tooth violet, marsh marigold, buttercup, tulip tree, horse- chestnut, Jeffersonia, May-apple, cherry, apple, crocus, tulip, daffodil, primrose, wild ginger, cranesbill, locust, bluebell. CHAPTER XVII. True Nature of Floral Organs; Details of their Structure. 187. The Flower a Shortened and Greatly Modified Branch. Fic. 136. — Transitions from Petals to Sta- mens in White Water-Lily. E, F, G, H, various steps between petal and stamen. bracts end and the sepals begin. —TIn Chapter IX, the leaf- bud was explained as being an undeveloped branch, which in its growth would develop into a real branch (or a prolongation of the main stem). Now since flower-buds appear regu- larly either in the axils of leaves or as terminal buds, there is reason to regard them as of similar nature to leaf-buds. This would imply that the receptacle corresponds to the axis of the bud shown in Fig. 60, and that the parts of the flower correspond to leaves. There is plenty of evidence that this is really true. Sepals frequently look very much like leaves, and in many cactuses the bracts about the flower are so sepal-like that it is im- possible to tell where the The same thing is true of as: TRUE NATURE OF FLORAL ORGANS. 153 sepals and petals in such flowers as the white water-lily. In this flower there is a remarkable series of intermediate steps ranging all the way from petals, tipped with a bit of anther, through stamens with a broad petal-like filament to regular stamens, aS 1s shown in Fig. 156, E, F, G, H. The same thing is shown in many double roses (Fig. 157). In com- pletely double flowers all the essential organs are transformed by cultivation into petals. In the flowers of the cultivated double cherry the pistils occasionally take the form of small leaves, and some roses turn wholly into green leaves. Summing up, then, we know that flowers are altered and shortened branches: (1) because flower-buds have the same JON Fic. 137. — Transitions between Petals and Stamens in a Rose. kinds of origin as leaf-buds ; (2) because all the intermediate steps are found between bracts on the one hand and stamens on the other ; (3) because the essential organs are found to be replaced by petals or even by green leaves. 188. Mode of Formation of Stamens and Pistils from Leaves. — It is hardly possible to state, in a book for begin- ners, how stamens stand related to leaves. The simple pistil or carpel is supposed to be made on the plan of a leaf folded along the midrib until its margins touch, hke the cherry leaf in Fig. 61. But the student must not understand by this statement that the little pistil leaf grows 1**The anther answers exactly to the spore-cases of the ferns and their allies, while the filament is a small specialized leaf to support it.” For a fuller statement, see Potter’s Warming’s Systematic Botany, pp. 236, 237. £54 ELEMENTS OF BOTANY. at first like an ordinary leaf and finally becomes folded in. What really occurs is this: the flower-bud, as soon as it has developed far enough to show the first rudiments of the essential organs, contains them in the form of minute knobs. These are developed from the tissues of the plant in the same manner as are the knobs in a leaf-bud, which afterwards become leaves ; but as growth and development progress in the flower-bud, its contents soon show themselves to be sta- mens and pistils (if the flower is a perfect one). The united leaf margins near the tip would form the stigma, and the placenta would corre- spond to the same margins, rolled shghtly inwards, ex- tending along the inside of the inflated leaf pouch. Place several such folded leaves upright about a com- mon center, and their cross- section would be much like that of B in Fig. 132. Evi- dence that carpels are really I, by longitudinal slits in the anther-cells formed in this Mayes be (pine); II, by uplifted valves (barberry); gained from the study of SS eta: ofeach anther- such fruits as that of the monkshood (Fig. 171), in which the ripe carpels may be seen to unfold into a shape much more leaf-like than that which they had while the pistil was maturing. 189. The Anther and its Contents. — Some of the shapes of the anthers may be learned from Figs. 116, 129, 136, 188 and 155.1 The shape of the anther and the way in which it opens depend largely upon the way in which the pollen is to be dis- Fig. 138.— Modes of Discharging Pollen. 1 See Kerner and Oliver, vol. I, pp. 86-95. TRUE NATURE OF FLORAL ORGANS. 155 charged and how it is carried from flower to flower. The commonest method is to have the anther-cells split length- wise, as in Fig. 138, I. A few anthers open by trap-doors like valves, as in II, and a larger number by little holes at the top, as in III. The pollen, in many plants with inconspicuous flowers, as the evergreen cone-bearing trees, the grasses, rushes, and sedges, is a fine, dry powder. In plants with showy flowers it is often somewhat sticky or pasty. The forms of pollen- grains are extremely various. That of the tulip (Fig. 116), and the kinds shown in Fig. 139 will serve as examples of some of the shapes which the grains assume; IV in the latter figure is perhaps as common a form as any. Each pollen-grain consists mainly of a single cell, and is covered by a moderately thick outer wall and a thin inner one. Its contents is a thickish protoplasm, full of little opaque particles and usually containing erains of starch and little drops of oil. The larger knobs on the outer coat, as at k (Fig. 139, I Fig. 139, — Pollen-Grains. aad-t1), marktheispots at which, 1 hazel; I, coltefooh; IU, ike ; 5 ; ginger; IV, hepatica; V, pine; the inner coat of the grain is $s, air-sacs, (All magnified 300 finally to burst through the outer —_—iameters.) one, pushing its way out in the form of a slender, thin-walled tube.? 190. Experiment 32. Production of Pollen Tubes. — Place a few drops of suitably diluted syrup? with some fresh pollen in a concave cell ground in a microscope slide; cover with thin glass circle ; place under 1 See Kerner and Oliver, vol. II, pp. 95-104. 2 See Appendix B, 156 ELEMENTS OF BOTANY. a bell glass, with a wet cloth or sponge, to prevent evaporation of the syrup, and set aside in a warm place, or merely put some pollen in syrup in a watch crystal under the bell glass. Examine from time to time to note the appearance of the pollen tubes. ‘Try several kinds of pollen if possible, using syrups of various strengths. The following kinds of pollen form tubes readily in syrups of the strengths indicated : ahip'~. : ; ; : ; : ; 1 to 3 per cent. Narcissus : : ; , ; : . ds tod Ae Cytisus Canariensis (called Genista by florists) 1a. 4% Chinese primrose : ‘ : ; : 10 es Sweet pea ! : ; : : nee 3 IG tp 1h Tropezolum ! : ; : : ; ; fi Fic. 141. — Part of Stigma of Thorn Fie. 140.— Stigma of Thorn Apple. Vertical section (magni- Apple (Datura) with Pollen fied), showing pollen tubes making (magnified). their way toward the ovary. 191. Microscopical Structure of the Stigma and Style. — Under a moderate power of the microscope the stigma is seen to consist of cells arranged rather loosely over the surface, and secreting a moist liquid to which the pollen-grains adhere (Fig. 140). Beneath these superficial cells and running down 1The sweet pea pollen and that of Tropzolum are easier to manage than any other kinds of which the author has personal knowledge. If a concaved slide is not available, the cover-glass may be propped up on bits of the thinnest broken cover- glasses. From presence of air or some other reason, the formation of pollen tubes often proceeds most rapidly just inside the margin of the cover-glass. TRUE NATURE OF FLORAL ORGANS. th7 through the style (if there is one), there are found long cells sometimes with intermediate spaces, through which latter the pollen tubes readily find their way (Fig. 141). When no such intercellular spaces exist, the pollen tube proceeds through the cell walls, which it softens by means of a substance which it exudes for that purpose. 192. Structure of the Ovule.— The details of the micro- scopic anatomy of the ovule are rather complicated. It is enough for our present purpose to state that the young ovule, _ before it has begun to form an embryo, usually exists as a roundish or egg-shaped mass, with a small opening leading into its apex. This opening leads to a sac inside the ovule, filled with soft protoplasmic material, containing cells and known as the embryo sac. Minute cells occur at the apex of the ovule (Fig. 142), and it is from their growth and development that the embryo is at length produced. CHAPTER XVIII. Fertilization; Transfer of Pollen, Protection of Pollen. 193. Fertilization. — By fertilization in flowering plants the botanist means the union of a nucleus from a pollen-grain with that of a cell at the apex of the embryo sac (Fig. 142). This pro- cess gives rise toa cell which contains material derived from the pollen and from the ovule cell. In a great many plants the pollen, in order to accomplish the most successful fertilization, must come from another plant of the same kind, not from the individual which bears the ovules that are being fertilized. Pollen tubes begin to form soon after pollen-grains lodge on the stigma. The time required for the process to begin varies in different kinds of plants, requiring in many cases twenty-four hours or more. The length of time needed for the pollen tube to make its way through the style to the ovary depends upon the length of the style and other condi- tions. In the crocus, which has a style several inches long, the descent takes from one to three days. Finally the tube penetrates the opening at the apex of the ovule m, in Fig. 142, reaches one of the cells shown at e, and transfers a nucleus into this egg-cell. The latter is thus enabled to divide and grow rapidly into anembryo. This the cell does by forming cell walls and then increasing by con- tinued subdivision in much the same way in which the cells at the growing point near the tip of the root, or those of the cambium layer subdivide.* 194. Nature of the Fertilizing Process.— The necessary feature of the process of fertilization is the union of the essen- tial contents of two cells to form a new one, from which the 1 See Kerner and Oliver, vol. I, pp. 401-420. FERTILIZATION. 159 future plant is to spring. This kind of union is found to occur in many flowerless plants (Chapter XXIII), resulting in the production of a spore very unlike a seed in most re- spects, but capable of growing into a complete plant lke that which produced it. 195. Number of Pollen Grains to each Ovule. — Only one pollen tube is necessary to fertilize each ovule, but so many pollen- grains are lost that plants produce many more of them than of ovules. The ratio, however, varies greatly. In the night- blooming cereus there are about 250,000 pollen- grains for 30,000 ovules, or rather more than 8 to 1, while in the common garden wistaria there are about 7,000 pollen grains to every _ovule, and in Indian corn, the cone- bearing evergreens, and a multitude of other plants, many times more than 7,000 to1. These differ- ences depend, as will be > 0 weirs faze ott 2 *FiG. 142. — Diagrammatic Representation of Fer- tilization of an Ovule. i, inner coating of ovule; o, outer coating of ovule ; p, pollen tube, proceeding from one of the pollen-grains on the stigma; c, the place where the two coats of the ovule blend. (The kind of ovule here shown is inverted, its open- ing m being at the bottom, and the stalk fad- hering along one side of the ovule.) a toe, embryo sac, full of protoplasm; a, so-called antipodal cells of embryo sac; 7, central nu- cleus of the embryo sac ; e, nucleated cells, one of which receives the essential contents of the pollen tube; f, funiculus or stalk of ovule ; m, opening into the ovule. seen presently, upon the mode in which the pollen is carried from the stamens to the pistil. 160 ELEMENTS OF BOTANY. 196. Cross-Fertilization and Self- Fertilization. — It was long supposed by botanists that the pollen of any perfect flower needed only to be placed on the stigma of the same flower to insure satisfactory fertilization. But in 1857 and 1858 the ereat English naturalist, Charles Darwin, stated that certain kinds of flowers were entirely dependent for fertilization on the transference of pollen from one plant to another, and he and other botanists soon extended the list of such flowers until it came to include most of the showy, sweet-scented or other- wise conspicuous kinds. It was also shown that probably nearly all attractive flowers, even if they can produce some seed when self-fertilized, do far better when fertilized with pollen from the flowers of another plant. This important fact was established by a long series of experiments on the number and vitality of seeds produced by a flower when treated with its own pollen, or self-fertilized, and when treated with pollen from another flower of the same kind, or cross-fertilized.” 197. Wind-Fertilized Flowers.* — It has already been men- tioned (§ 189), that some pollen is dry and powdery, and other kinds are more or less sticky. Pollen of the dusty sort is light, and therefore adapted to be blown about by the wind. Any one who has been much in cornfields after the corn has ‘“‘tasseled”” has noticed the pale yellow dusty pollen which flies about when a cornstalk is jostled, and which collects in considerable quantities on the blades of the leaves. Corn is moncecious, but fertilization is best accomplished by pollen blown from the “tassel” (stamens) of one plant being carried to the “silk” (pistils) of another plant. This is well shown by the fact, familiar to every observing farmer’s boy, that solitary cornstalks, such as often grow very luxuriantly in an unused barnyard or similar locality, bear very imperfect 1 See Darwin’s Cross and Self-Fertilization in the Vegetable Kingdom (especially Chapters I and II). 2 On dispersion of pollen see Kerner and Oliver, vol. II, 129-287. 3 See Miss Newell’s Botany Reader, Part II, Chapter VII. FERTILIZATION. 161 ears or none at all. The common ragweed, another moncecious plant, is remarkable for the great quantities of pollen which shake off it on to the shoes or clothes of the passer-by, and it is wind-fertilized. So, too, are the monecious pines, and these produce so much pollen that it has been mistaken for showers of sulphur, falling often at long distances from the woods where it was produced. The pistil of wind-fertilized flowers is often feathery and thus adapted to catch flying pollen-grains (Fig. 148). Other char- acteristics of such flowers are the inconspicuous character of their flow- ers, Which are usually green or green- ish, the absence of odor and of nectar, the regularity of the corolla, ‘Fue. 143. — Pistil of a Grass. and the appearance of the flowers 4@, ovary; 6, feathery stigma, adapted for wind-fertiliza- before the leaves or their occurrence Han on stalks raised above the leaves. Pollen is, in the case of a few aquatic plants, carried from flower to flower by the water on which it floats. 198. Insect-Fertilized Flowers. — Most plants which require cross-fertilization depend upon insects as pollen-carriers,* and it may be stated as a general fact that the showy colors and markings of flowers and their odors, all serve as so many advertisements of the nectar (commonly but wrongly called honey), or of the nourishing pollen which the flower has to offer to insect-visitors. | Many insects depend mainly or wholly upon the nectar and the pollen of flowers for their food. Such insects usually visit during the day only one kind of flower, and therefore carry but one kind of pollen. Going straight from one flower to another with this, they evidently waste far less pollen than the wind or water must waste. It is therefore clearly advantageous to flowers to develop such adaptations as fit 1A few are fertilized by snails ; many more by humming-birds and other birds. 162 ELEMENTS OF BOTANY. them to attract insect-visitors, and to give pollen to the latter and receive it from them. 199. Pollen-Carrying Apparatus of Insects..— Ants and many beetles which visit flowers have smooth bodies, to which little pollen adheres, so that their visits are often of little value to the flower, but many beetles, all butterflies and moths and most bees have bodies roughened with scales or hairs so as to hold a good deal of pollen entangled. In the common honey-bee (and in many other kinds) the greater part of the insect is hairy, and there are special collecting baskets, formed by bristle-like hairs, on the hind-legs, Fig. 144. It is easy to see the load of pollen’ accumulated in these baskets, after such a bee has visited several flowers. Of course the pollen which the bee packs in the baskets and carries off to the hive, to be stored for food, is of no use in fertilization. In fact such pollen is in one sense entirely wasted. Fig. 144. — Right Hind-Leg of a Honey-Bee. But since such bees a (Seen from behind and within.) have these collecting ti (below), the tibia seen from the outside, baskets are the most in- showing the collecting basket, formed of : ane ae dustrious visitors to flow- ers, they accomplish an immense share of the work of fertilization by means of the pollen-grains which stick to their hairy coats. 200. Nectar and Nectaries. — Nectar is a sweet liquid which flowers secrete for the purpose of attracting insects. After partial digestion in the crop of the bee, nectar becomes 1 See Miiller’s Fertilization of Flowers, Part II. — FERTILIZATION. 163 honey. Those flowers which secrete nectar do so by means of nectar-glands, small organs whose structure is something like that of the stigma, situated usually near the base of the flower, as shown in Fig. 145. Sometimes the nectar clings in droplets to the surface of the nectar-glands ; sometimes it is stored in little cavities or pouches called nectaries. The pouches at the bases of columbine petals are among the most familiar of nectaries. 201. Odors of Flowers. —The acuteness of the sense of smell among insects is a familiar fact. Flies buzz about the wire netting which covers a piece of fresh meat or a dish of syrup, and bees, wasps, and hornets will fairly besiege the window-screens of a kitchen where preserving is going on. Many plants find it possible to attract as many insect-visitors as they need without giving off any scent, but small flowers, like the mignonette, and night- blooming ones, like the four-o’-clock abe tie en eee and the evening primrose, are sweet- of the Grape (magnified), with scented to attract night-flying moths. # Boney-gland between each pair of stamens. It is interesting to observe that the majority of the flowers which bloom at night are white, and that they are much more generally sweet-scented than flowers which bloom during the day. A few flowers are carrion- scented (and purplish or brownish colored) to attract flies. 202. Colors of Flowers. — Flowers which are of any other color than green display their colors to attract insects, or occasionally birds. The principal color of the flower is most frequently due to showy petals, sometimes, as in the marsh marigold, it belongs to the sepals, and not infrequently, as in some cornels and Euphorbias, the involucre is more brilliant and conspicuous than any part of the flower strictly so-called. 164 ELEMENTS OF BOTANY. Different kinds of insects are especially attracted by different colors. In general, dull yellow, brownish or dark purple flowers, especially if small, seem to depend largely on the visits of flies. Red, violet, and blue are the colors by which bees and butterflies are most readily enticed. The power of bees to distinguish colors has been shown by a most interesting set of experiments in which daubs of honey were put on slips of glass laid on separate pieces of paper, each of a different color, and exposed where bees would find them.} ' 203. Nectar Guides.—In a large number of cases the petals of flowers show decided stripes or rows of spots, of a color different from that of most of the petal. These com- monly lead toward the nectaries, and there is no doubt that such markings point out to insect-visitors the way to the nectaries. Following this course, the insect not only secures the nectar which he seeks, but perhaps leaves pollen on the stigma and becomes dusted with new pollen which he carries to another flower. 204. Facilities for Insect Visits. — Regular polypetalous flowers have no special adaptations to make them singly accessible to insects, but he open to all comers. They do, however, make themselves much more attractive and afford especial inducements in the matter of saving time to flower- frequenting insects by being grouped. This purpose is undoubtedly served by dense flower-clusters, especially by heads like those of the clovers and by the peculiar form of head found in so-called compound flowers, like the sunflower and the bachelor’s button (Fig. 165). In many such clusters the flowers are specialized, some as in Fig. 110, carrying a showy strap-shaped corolla, to serve as an advertisement of the nectar and pollen contained in the inconspicuous tubular 1 See Lubbock’s Flowers, Fruits, and Leaves, Chapter I. On the general subject of colors and odors in relation to insects, see Miiller’s Fertilization of Flowers, Part LV. FERTILIZATION. 165 flowers. Irregular flowers probably always are more or less adapted to particular insect (or other) visitors. The adapta- tions are so numerous that many volumes could be filled with a description of them;—here only a very few of the simpler ones will be pointed out. Where there is a droop- ing lower petal (or, in the case of a gamopetalous corolla, a lower lip), this serves as a perch upon which flying in- sects may alight and stand while they explore the flower, as the beetle is doing in Fig. 146. In Fig. 147 one bumble-bee stands with his legs par- tially encircling the lower lp of the dead nettle flower, while another perches on the sort of grating made by the stamens of the horse-chestnut Fic. 146. — A Beetle on the Flower of the Twayblade. (Enlarged four times.) flower. The honey-bee entering the violet clings to the beautifully bearded portion of the two lateral petals, while it sucks the nectar from the spur beneath. Fic. 147. — Bees visiting Flowers. At the left a bumble-bee (European) on the flower of the dead nettle; above a similar bee in the flower of the horse-chestnut ; below, a honey-bee in the flower of a violet. 166 ’ ELEMENTS OF BOTANY. 205. Protection of Pollen from Unwelcome Visitors. —It is usually desirable for the flower to prevent the entrance of small creeping insects, such as ants, which carry little pollen and eat a relatively large amount of it. The means adopted Fig. 148. Flowers protected from Unwelcome Visitors. I, enchanter’s nightshade, magnified five times; II, gooseberry, natural size; III, tellima, magnified two times; IV, speedwell, magni- fied four times; V, bearberry, magnified six times; VI, hound’s-tongue, magnified four times; VII, nodding campion, natural size, at midnight. to secure this result are many and curious. In some plants, as the com- mon catchfly, there is a sticky ring about the peduncle, some distance below the flowers, and this forms an effectual bar- rier against ants and like insects. Very frequently the calyx-tube is covered with hairs, which are sometimes sticky, as in Fig. 148, I, Il, and VII. How these thickets of hairs may appear to a very small insect can per- haps be more easily real- ized by looking at the considerably magnified view of the hairs from the outer surface of mullein petals, shown in Fig. 149.1 Sometimes the recurved petals or divisions of the corolla stand in the way of creeping insects, as in III and VII. In other cases the throat of the corolla is much narrowed, as in V, or closed 1 On protection of pollen see Kerner and Oliver, vol. II, pp. 95-109. FERTILIZATION. 167 by hairs, 2 in IV, or by appendages, kin VI. Those flowers which have one or more sepals or petals prolonged into spurs, like the nasturtium and the columbine, are inaccessible to most insects except those which have a tongue, or a sucking- SS} HA Z7 . % f~ ZF EK i EA CYT i—— eax = XA KI —x— 4 — =~ | \ SS . WZ a a / \ ‘“y Vig Fig. 149. — Branching Hairs from the Outside of the Corolla of the Com- mon Mullein (magnified). dr, a gland. tube long enough to reach to the nectary at the bottom of the spur. The large sphinx moth, shown in Fig. 150, which is a common visitor to the flowers of the evening primrose, is an S SS wu? 47 Fia. 150. — A Sphinx Moth, with a Long Sucking-Tube. example of an insect especially adapted to reach deep into long tubular flowers. 168 ELEMENTS OF BOTANY. A little search among flowers, such as those of the colum- bine or the foxglove, will usually disclose many which have had the corolla bitten through by bees, which are unable to get at the nectar by fair means and so steal it. 206. Bird-Fertilized Flowers. —Some flowers with very long tubular corollas depend entirely upon birds to carry their pollen for them. Among garden flowers the gladiolus, the scarlet salvia and the trumpet honeysuckle are largely dependent upon humming-birds for their fertilization. The h CRY | SS WW Vig = Ty) \\ Ges S b 3 Wii pr UY) Li AY ee Fic. 151. — Flower-Frequenting Bird, with a Flower. I, head of a sword-beak ; II, a datura flower, visited by it. (Both two- thirds natural size.) wild balsam or jewel-weed and the trumpet-creeper are also favorite flowers of the hoamming-bird. In Fig. 151 the head of a flower-visiting bird and a flower frequented by it are shown. 207. Prevention of Self-Fertilization. — Dicecious flowers are of course quite incapable of self-fertilization. Pistillate moncecious flowers may be fertilized by staminate ones on the same plant, but this does not secure so good seed as is secured by having pollen brought to the pistil from a different plant. FERTILIZATION. 169 In perfect flowers self-fertilization would commonly occur unless it were prevented by the action of the essential organs or by something in the structure of the flower. In reality flowers which at first sight would appear to be designed to secure self-fertilization are almost or quite incapable of it. Frequently the pollen from another plant prevails over that which the flower may shed on its own pistil, so that when both kinds are placed on the stigma at the same time it is the foreign pollen which causes fertilization. But apart from this fact, there are several means of insuring the pres- ence of foreign pollen, and only that, upon the stigma, just when it is mature enough to receive pollen tubes. 208. Stamens and Pistils maturing at Different Times. —If the stamens mature at | a different time from the yg. 152,— Flower of Clerodendron in pistils, self-fertilization is as Two Stages. In the upper figure (earlier stage) the effectually prevented as though stamens are mature, while the pistil is the plant were dicecious. This still undeveloped and bent to one side. In the lower figure (later stage) the unequal maturing or dichog- stamens have withered and the stigmas amy occurs in many kinds of have separated, ready for the reception flowers. In some, the figwort gal cepa . and the common plantain, for example, the pistil develops before the stamens, but usually the reverse is the case. The Clero- dendron, a tropical African flower, illustrates in a most strik- ing way the development of stamens before the pistil. The insect-visitor, on its way to the nectary, can hardly fail to brush against the protruding stamens of the flower in its 170 ELEMENTS OF BOTANY. earlier stage (above), but it cannot deposit any pollen on the stigmas which are unripe, shut together and tucked aside, out of reach. On flying to a flower in the later stage the pollen II Ul IV Fig. 153.— Provisions for Cross-Fertilization in the High Mallow. I, essential organs as found in the bud ; II, same in the staminate stage, the anthers discharging pollen, pistils immature; III, intermediate stage, stig, the united stigmas ; LV, pistillate stage, the stigmas separated, stamens withered. just acquired will be lodged on the prominent stigmas and Fig. 154.— Stamens and Pistils of Round-Leafed Mallow (the stig- mas curled round among the sta- mens to admit of self-fertilization). thus produce the desired cross-fertilization. Closely related flowers often differ in their plan of fertilization. The high mallow, a plant cultivated for its purplish flowers, which has run wild to some extent, is admirably adapted to secure cross-fertilization with its own pollen, since when its stamens are shed- ding pollen, as in Fig. 153, II, the pistils are incapable of receiving it, while when the pis- tils are mature, as at IV, the stamens are quite withered. In the common low mallow of our door-yards and waysides, insect ferti- lization may occur, but if it does not the curling stigmas finally come in contact with FERTILIZATION. Fit the projecting stamens and receive pollen from them, as is indicated in Fig. 154. 209. Movements of Floral Organs to aid in Fertilization. — Besides the slow movements which the stamens and pistil make in such cases as those of the Clerodendron and the mallow, already described, the parts of the flower often admit of considerable and rather quick movements to assist the insect-visitor to become dusted or smeared with pollen. In some flowers whose stamens perform rapid movements when an insect enters, it is easy to see how directly useful the motion of the stamens is in securing cross-fertilization. Fic. 155. —Two Flowers of Common Sage, one of them visited by a bee. The stamens of the laurel, Kalmia, throw little masses of pollen, with a quick jerk, against the body of the visiting insect. Barberry stamens spring up against the visitor and dust him with pollen. The common garden sage matures its anthers earlier than its stigmas. In Fig. 155, A, the young flower is seen, visited by a bee, and one anther is shown pressed closely against the side of the bee’s abdomen. The stigma s¢ is hidden within the upper lip of the corolla. In B, an older flower, the anthers have withered and the stigma is now lowered so as to brush against the body of any 172 ELEMENTS OF BOTANY. bee which may enter. A little study of Fig. 156 will make clear the way in which the anthers are hinged, so that a bee striking the empty or barren anther-lobes a knocks the pollen- Fie. 156.— Flower and Stamens of Common Sage. A, p, stigma; a, anthers. B, the twostamens in ordinary position ; /f, filaments ; m, connective (joining anther-cells); a. a’, anther-cells. C, the anthers and connectives bent into a horizontal position by an insect pushing against a. bearing lobes a! into a horizontal position, so that they will he closely pressed against either side of its abdomen. Fig. 157.— Dimorphous Flowers of the Primrose. I, I, short-styled form ; III, IV, long-styled form, natural size; a, throat of the corolla; S,s, stamens; G, g, styles. 210. Flowers with Stamens and Pistils each of Two Lengths. —The flowers of bluets, partridge-berry, the primroses and a few other common plants secure cross-fertilization by hay- FERTILIZATION. 173 ing essential organs of two forms, Fig. 157. Such flowers are said to be dimorphous (of-two-forms). In the short-styled flowers, I, II, the anthers are borne at the top of the corolla tube a, S, and the stigma, g, stands about half-way up the tube. In the long-styled flowers, III, IV, the stigma G is at the top of the tube and the anthers, S, are borne about half- way up. An insect, pressing its head into the throat of the corolla of I or II would become dusted with pollen which would be brushed off on the stigma of a flower like III or IV. On leaving a long-styled flower, IV, the bee’s tongue would be dusted over with pollen, some of which would necessarily be rubbed off on the stigma of the next short-styled flower that was visited. Cross-fertilization is insured, since all the flowers on a plant are of one kind, either long-styled or short- styled, and since the pollen is of two sorts, each kind sterile on the stigma of any flower of similar form to that from which it came. Trimorphous flowers, with long, medium, and short styles, are found in a species of loosestrife.? 211. Studies in Insect Fertilization. —The student cannot gather more than a very imperfect knowledge of the details of cross-fertilization in flowers without actually watching some of them as they grow, and observing their insect-visitors. If the latter are caught and dropped into a wide-mouthed stoppered bottle containing a bit of cotton saturated with chloroform, they will be painlessly killed and most of them may be identified by any one who is familiar with our common insects. The insects may be observed and classified in a general way into butterflies, moths, bees, flies, wasps, and beetles, without being captured or molested. Whether these out-of-door studies are made or not, several flowers should be carefully examined and described as regards their arrange- ments for attracting and utilizing insect-visitors (or birds). The following list includes a considerable number of the most accessible flowers of spring and early summer, about which it is easy to get information from books. 1 See Miss Newell’s Reader in Botany, Part I1, pp. 60-63. 174 ELEMENTS OF BOTANY. List oF InsEcT-FERTILIZED FLowers,} i: 1. Flax. f Linum usitatissimum Miill. 2. Missouri currant Ribes aureum . See Mill. 8. Snowberry . Symphoricarpus racemosus Mill. 4. Lilac Syringa Persica . Miill. 5. Periwinkle Vinca minor Mill. 6. Mignonette Reseda odorata Mill. 7. Pansy Viola tricolor . > ja = iS 8. Dead nettle Lamium album : . Lubbock. 9. Bleeding heart Dicentra (Diclytra) spectabilis Mill. 10. Columbine . Aquilegia vulgaris - . : Mill. 11. Monkshood Aconitum Napellus . Mill. 1. : 12. Larkspur Delphinium elatum, D. consolida Mill. 13. Herb Robert . Geranium Robertianum Mill. 14. Pink. Dianthus (various species) Mill. 15. Fireweed Epilobium angustifolium . 3 (Gray 16. Nasturtium Tropeolum majus Newell, Lubbock 17. Lily of the valley Convallaria majalis . Mill. 18. Heal-all. Brunella (Prunella) vulgaris . Mill. 19. Ground ivy Nepeta Glechoma . Miill., Newell. 20. Lousewort . Pedicularis Canadensis Miill., Newell. 21. Snapdragon Antirrhinum majus . . Malk 220 Tris: . 2 Tris versicolor . 3 Newell. 25. Bellflower . Campanula rapunculoides . Mill. 24. Horse-chestnut Aisculus Hippocastanum . Newell. Lane 25. Yarrow. Achillea millefolium Miill. 26. Ox-eye daisy . Chrysanthemum Leucanthemum . Miill. 27. Dandelion . Taraxacum officinale Miill., Newell. 1 The plants in this list are arranged somewhat in the order of the complexity of their adaptations for insect fertilization, the simplest first. It would be well for each student to take up the study of the arrangements for the utilization of insect- visitors in several of the groups above, numbered with Roman numerals. The teacher will find explanations of the adaptations in the works cited by abbrevia- FERTILIZATION. Efd List cr Insect-FERTILIZED FLowerRs — concluded. LY. oeemrverry . . . . berverisvulgaris. . . . . . . Lubbock. 29. Mountain laurel. . Kalmialatifolia. . . ... =. . Gray. V. 30. White clover. . . Trifoliumrepens. ... .. . . Mild. mi. Redclover . . . Trifolium pratense . . .-./. .». Mull. ez. Locust. . . ... Robinia Pseudacacia ... -.. . . Gray. eee Wistaria - . . . Wisteria Sinensis . . . . . . s Gray. SRE ec saat oY OE SNE OPEEER, aE Pee... . . . Phaseolua vulgaris... . . . . « Gray. er. Ground-nut . . . Apiostuberosa. ... ... . . . Gray. VI. 08. Partridge-berry . . Mitchella repens . . he Ee Pee | 09. Primrose . . . . Primula grandiflora, P. officinalis Lubbock. 40. Loosestrife . . . LythrumSalicaria . ... . . . Gray. VIL. 41. Milkweed. . . . Asclepias Cornuti . . . . Miill., Newell. VIII. 42. Lady’s-slipper . . Cypripediumacaule. . . . . . Newell. 212. Protection of Pollen from Rain. — Pollen is very gen- erally protected from being soaked and spoiled by rain or dew either by the natural position of the flower preventing rain from entering, as in the case with most gamopetalous, nodding flowers, or by changes in the position of the flower, and by its opening in sunny weather and closing at night or during tions at the right. Mill. stands for Miiller’s Fertilization of Flowers; Lubbock, for British Wild Flowers, Considered in Relation to Insects; Gray, for Gray’s Structural Botany ; and Newell, for Miss Newell’s Outlines of Lessons in Botany, Part II. 176 ELEMENTS OF BOTANY. rain. Sometimes the flower both changes its position and closes, as is the case with the herb Robert and the sweet scabious, Fig. 158. The adaptations of flowers to protect their pollen from being wetted can best be made out by actually examining the same flower in sunshine and during rain. <> = : : SF =: ge ; WS Se % - ; f y), He J Ee eg) Sy 4 i ee eS abe, Se AYN TS Fic. 158. — Protection of Pollen from Moisture. I, herb Robert insunny weather ; II, sweet scabious in sunny weather ; II, sweet scabious during rain ; IV, herb Robert during rain. 213. Detailed Study of Flowers. — Now that the student has learned something of the adaptations of flowers to insect-visitors, he is able to carry on such studies as those of Chapter XV in more detail. After making a careful examination of the flower as a whole and of its parts, FERTILIZATION. 177 in various stages of maturity, he may investigate its adaptations for insect fertilization and its mode of protecting its pollen from creeping insects and from rain. It will be particularly interesting to compare the various degrees of perfection with which closely related flowers attain these results. Several flowers should be worked out pretty fully and the results of the examination of each recorded in a written account and a series of sketches. Out of the many possible studies of this kind the following are suggested : The flower of the pea, the bean, or the locust, consulting Figs. 159, 160, 161. Fia. 160.— I, Diagram of Flower of Sweet Pea. II, Vertical Section of Flower (magnified). III, Calyx (magnified). 178 ELEMENTS OF BOTANY. The flower of the peach, the plum, or the rose, consulting Figs. 162 and 163. Fic. 161. — 1, Stamens and Pistil of Sweet Pea (magnified), Ll, Fruit. III, Part of Fruit, showing one seed. Fiac. 162. — Flower oi Pear. ——— Gallo’ uy} 125) b= I I 1 IV Fic. 163.— I, Vertical section of Flower of Pear. II, Ovary, transverse section. III, Entire Seed (magnified). IV, Seed, vertical section (magnified). FERTILIZATION. 179 The flower of the ox-eye daisy, or the dandelion, consulting Figs, 110, 131, 164, 165, 166 Fie. 164. — Flower-Cluster of Bachelor’s Button (Centaurea Cyanus). The flower of the crocus, the blue-eyed grass, or the iris, consulting Figs. 167 and 168.1 1 For descriptions and illustrations that will aid in the work of this section the teacher is referred to Gray’s Structural Botany, Gray’s Field, Forest,and Garden Botany, Le Maout and Decaisne’s Traité Général de Botanique, and Miss Newell’s Outlines of Lessons in Botany, Part II. ELEMENTS OF BOTANY. EY. 180 ye Vv I II Ir FiaG. 165. — Bachelor’s Button. I, a tubular flower (magnified), anth, the united anthers; II, fruit (magni- fied) ; III, fruit, vertical section (magnified); IV, a neutral ray-flower ;+ V, ring of anthers. v Tit i i I Fic. 166. — Bachelor’s Button. I, vertical section of the receptacle ; II, style and forked stigma (magnified) ; III, corolla, united anthers and stigma (magnified); IV, pistil (magnified), pap, pappus, ach, achenium; V, tubular flower cut vertically (magnified), showing anther-tube, traversed by the style. 1 This is not precisely homologous with theray-flowers of Helianthus and most rayed Composite, but is an enlarged and conspicuous tubular flower. FERTILIZATION. 181 Fia. 167. — Iris. I, flower ; LI, seed, longitudinal section ; III, flower with limb of perianth removed ; stig, stigma, ov, ovary. E Fic. 168. — Iris. Til I, flower, longitudinal section, ov, ovary; IJ, diagram, showing stigmas opposite the stamens ; III, capsule, splitting between the partitions. CHAPTER XIX. The Study of Typical Fruits. 214. A Berry, the Tomato.1— Study the external form of the tomato, and make a sketch of it, showing the persistent calyx and peduncle. ; Cut a cross-section at about the middle of the tomato. Note the thick- ness of the epidermis (peel off a strip) and of the wall of the ovary. Note the number, size, form, and contents of the cells of the ovary. Observe the thickness and texture of the partitions between the cells. Sketch. Note the attachments of the seeds to the placentas and the gelatinous, slippery coating of each seed. Rub off this coating and then note the wing-like margin around the seed. The tomato is a typical berry, but its structure presents fewer points of interest than are found in some other fruits of the same general char- acter, so the student will do well to spend a little more time on the examination of such fruits as the orange or the lemon. 215. A Hesperidium, the Lemon. — Procure a large lemon which is not withered, if possible one which still shows the remains of the calyx at the base of the fruit. Note the color, general shape, surface, remains of calyx, knob at portion formerly occupied by the stigma. Sketch the fruit about natural size. Examine the pitted surface of the rind with the magnifying-glass and sketch it. Remove the bit of stem and dried-up calyx from the base of the fruit; observe, above the calyx, the knob or disk on which the pistil stood. Note with the magnifying glass and count the minute whitish raised knobs at the bottom of the saucer-shaped depression left by the removal of the disk. : Make a transverse section of the lemon, not more than a fifth of the way down from the stigma end and note: (1) The thick skin, pale yellow near the outside, white within. (2) The more or less wedge-shaped divisions containing the juicy pulp of the fruit. These are the matured cells of the ovary ; count these. (3) The thin partitions between the cells. 1 Fresh tomatoes, not too ripe, are to be used, or those which have been kept over from the previous summer in formalin solution. The very smallest varieties, such as are often sold for preserving, are as good for study as the larger kinds. THE STUDY OF TYPICAL FRUITS. 183 (4) The central column or axis of white pithy tissue. (5) The location and attachment of any seeds that may be encountered in the section. Make a sketch to illustrate these points, comparing it with Fig. 181. Study the section with the magnifying glass and note the little spherical reservoirs near the outer part of the skin, which contain the oil of lemon which gives to lemon-peel its characteristic smell and taste. Cut with the razor a thin slice from the surface of the lemon-peel, some distance below the section, and at once examine the freshly cut surface with a magnifying glass to see the reservoirs, still containing oil, which, how- ever, soon evaporates. On the cut surface of the pulp (in the original cross-section) note the tubes in which the juice is contained. These tubes are not cells, but their walls are built of cells. Cut a fresh section across the lemon, about midway of its length and sketch it, bringing out the same points which were shown in the previous one. The fact that the number of ovary cells in the fruit corresponds with the number of minute knobs in the depression at its base is due to the fact that these knobs mark the points at which fibro-vascular bundles passed from the peduncle into the cells of the fruit, carrying the sap by which the growth of the latter was maintained. Note the toughness and thickness of the seed-coats. Taste the kernel of the seed. Cut a very thin slice from the surface of the skin, mount in water, and examine with a medium power of the microscope. Sketch the cellular structure shown and compare it with the sketch of the corky layer of the bark of the potato tuber. Of what use to the fruit is a corky layer in the skin? (See § 250 for further questions. ) 216. A Legume, the Bean-Pod.1— Lay the pod flat on the table and make a sketch of it, about natural size. Label stigma, style, ovary, calyz, peduncle. Make a longitudinal section of the pod, at right angles to the plane in which it lay as first sketched, and make a sketch of the section, showing the partially developed seeds, the cavities in which they lie, and the solid portion of the pod between each bean and the next. Split another pod, so as to leave all the beans lying undisturbed on one-half of it and sketch that half, showing the beans lying in their -1 Any species of bean (Phaseolus) will answer for this study. Specimens in the condition known at the markets as ‘‘shell-beans” would be best, but these are not obtainable in spring. Ordinary “‘string-beans” will do. 184 ELEMENTS OF BOTANY. natural position and the funiculus or stalk by which each is attached to the placenta ; compare Fig. 176. Make a cross-section of another pod, through one of the beans, sketch the section and label the placenta (formed by the united edges of the pistil leaf), and the midrib of the pistil leaf. Break off sections of the pod and determine, by observing where the most stringy portions are found, where the fibro-vascular bundles are most numerous. Examine some ripe pods of the preceding year,! and notice where the dehiscence, or splitting open of the pods occurs, whether down the pla- cental edge, ventral suture, the other edge, dorsal suture, or both. 217. An Akene, the Fruit of Dock. — Hold in the forceps a ripe fruit of any of the common kinds of dock,? and examine with the magnifying- glass. Note’ the three dry, veiny, membranaceous sepals by which the fruit is enclosed. On the outside of one or more of the sepals is found a tubercle or thickened appendage which looks like a little seed or grain. No use is known for this. Of what use are the sepals, after drying up? Why do the fruits cling to the plant long after ripening ? Carefully remove the sepals and examine the fruit within them. What is its color, size, and shape? Make a sketch of it as seen with the magnifying glass. Note the three tufted stigmas, attached by slender threads to the apex of the fruit. What does their tufted shape indicate ? What evidence is there that this seed-like fruit is not really a seed ? Make a cross-section of a fruit and notice whether the wall of the ovary can be seen, distinct from the seed coats. Compare the dock-fruit in this respect with the fruit of the anemone, shown in Fig. 169. Such a fruit as either of these is called an akene. 2 Which may be passed round for that purpose. They should have been saved and dried the preceding autumn. 2Rumex crispus, R. obtusifolius, or R, verticillatus. This should have been gathered and dried the preceding summer. CHAPTER XX. The Fruit.! 218. What Constitutes a Fruit. —I1t is not easy to make a short and simple definition of what botanists mean by the term fruit. It has very little to do with the popular use of the word. Briefly stated, the definition may be given as follows: The fruit consists of the matured ovary, together with any intimately connected parts. Botanically speaking, the bur of beggar’s ticks, Fig. 179, the three-cornered grain of buckwheat, or such true grains as wheat and oats are as much fruits as is an apple or a peach. The style or stigma sometimes remains as an important part of the fruit in the shape of a hook, as in the common hooked crowfoot; or in the shape of a plumed appendage, as in the virgin’s bower, often called wild hops. The calyx may develop hooks, as in the agrimony or plumes, as in ‘ . : Fig. 169. — Fruit of the thistle, the dandelion, lettuce, and many Wand Avance other familiar plants. In the apple, pear, I, akene cut verti- and very many berries, the calyx becomes ina, Putte enlarged and pulpy, often constituting the main bulk of the mature fruit. The receptacle not infre- quently, as in the apple, forms a more or less important part of the fruit. 219. The Akene.— The one-celled and one-seeded pistils of the buttercup, strawberry, and many other flowers ripen into a little fruit called an akene, Fig. 169. Such fruits, from their small size, their dry consistency, and the fact that 1See Gray’s Structural Botany, Chapter VII, also Kerner and Oliver, vol. I, pp. 427-438. 186 ELEMENTS OF BOTANY. they never open, are usually taken by those who are not botanists for seeds. In the group of plants to which the daisy, the sunflower and the dandelion belong, the akenes consist of the ovary and the adherent calyx-tube. The limb of the calyx is borne on the summit of many akenes, sometimes in the form of teeth, sometimes as a tuft of hairs or bristles, Fig. 174. 220. The Grain. — Grains, such as corn, wheat, oats, barley, rice and so on have the interior of the ovary completely filled by the seed, and the seed-coats and the wall of the ovary are firmly united, as Fig. 170.— Chestnut, a Single Fruit. shown in Fig. 9. 221. The Nut.— A nut, Fig. 170, is larger than an akene, usually has a harder shell and commonly contains a seed which springs from a single ovule of one cell of a compound ovary, which develops at the expense of all the other ovules. The chestnut-bur is a kind of involucre, and so is the acorn- cup. The name nut is often incor- rectly apphed in popular language, for example, the so-called Brazil-nut is really a large seed with a very hard testa. 222, Indehiscent and Dehiscent Fie. 171.—Group of Follicles Fruits. — All of the fruits so far n¢ & Sings Rolie ae considered in the present chapter are indehiscent, that is, they remain closed after ripening. Dehis- cent fruits when ripe open in order to discharge their seeds. The three classes which immediately follow belong to this division. 223. The Follicle. —One-celled, simple pistils, like those es Ar ATA “4 " tT WY RAY jue La - aidhaityine \ ‘I IS R Melons THE FRUIT. 187 of the marsh marigold, the columbine, and a good many other plants, often produce a fruit which dehisces along a single suture, usually the ventral one. Such a fruit is called a follicle, Fig. 171. 224. The Legume. — A legume is a one-celled pod, formed by the maturing of a simple pistil, which dehisces along both of its sutures, as already seen in the case of the bean pod, and illustrated in Fig. 176. 225. The Capsule. — The dehiscent fruit formed by the I Il Fic. 172. — Winged Fruits. I, elm ; I, maple. ripening of a compound pistil is called a capsule. Such a fruit may be one-celled, as in the linear pod of the celandine, Fig. 176, or several-celled, as in the fruit of the poppy, the. -morning-glory and the Jamestown weed, Fig. 176. 226. Dry Fruits and Fleshy Fruits.—In all the cases discussed or described in §§ 213-219 the wall of the ovary (and the adherent calyx when present) ripen into tissues which are somewhat hard and dry. Often, however, these parts become developed into a juicy or fleshy mass by which 188 ELEMENTS OF BOTANY. the seed is surrounded. Hence a general division of fruits into dry fruits and fleshy fruits. 227. Winged or Tufted Fruits and Seeds. — The fruits of the ash, box-elder, elm, maple, Fig. 172, and many other trees are provided with an expanded membranous wing. Some seeds, as those of the catalpa and the trumpet-creeper are similarly appendaged. The fruits of the dandelion, the thistle, the fleabane, Fig. 174, and many other plants of the group to which these belong, and the seeds of the willow, the milkweed, the willow-herb, Fig. 175, and other. plants, bear a tuft of hairs, sometimes silky and in other cases plumed or feathery. The student should be able from his own observations on the falling fruits of some of the trees and other plants above mentioned to answer some such questions as the fol- lowing : What is the use of the wing- like appendages ? of the tufts of hairs ? Which set of contrivances seems to be the more success- ful of the two in securing this object ? What particular plant of the ones available for study seems to have attained this object most perfectly ? What is one reason why many plants with tufted seeds, such as the thistle and the dande- lion, are extremely troublesome weeds ? A few simple experiments, easily devised by the student, may help him to find answers to the questions above given. Fia. 173.— Fruit-Cluster of Linden; peduncle joined to the bract, forming a wing. 1 See Kerner and Oliver, vol, II, pp. 833-875. Ot] ads — N a8 cele G e ae 50) sae I ry ss yes rit << £& _ Sa « ~ anna t [-] s ees Fic. 205. — Longitudinal Section of the Summit of a very Small Antheridium- Bearing Plant of Funaria hygrometrica, a Moss. a, young antheridium ; }, nearly mature antheridium ; c, appendages growing among the antheridia; d, leaves cut through the midrib; e, leaves cut through the blade. (Magnified 300 diameters.) SOME TYPES OF FLOWERLESS PLANTS. 239 295. Other Reproductive Apparatus. —The student cannot, with- out spending a good deal of time and making himself expert in the examination of mosses, trace out for himself the whole story of the reproduction of any moss. It is sufficient here to give an outline of the process. The protonema develops buds, one of which is shown in Fig. 206, and the bud grows into an ordinary moss plant. This plant, in the case of the pigeon-wheat moss, bears organs of a somewhat flower-like nature, Fig. 205, which contain either antheridia, Fig. 204, organs which produce fertilizing cells called antherozoids, or archegonia, Fig. 205, organs which produce odspheres (§ 275), but in this moss antheridia and archegonia are not produced in the same ‘‘ moss-flower.’’? The plants therefore correspond to dicecious ones among flowering plants. After the fertilization of the odsphere, by the penetration of anthero- zoids to the bottom of the flask-shaped archegonium, the development of the odsphere into an urn begins, the latter rises on its slender stalk, while the upper part of the archegonium is carried with it and persists for a time as the hood, Fig. 202, c. MOSSES. 296. Mosses have Specialized Organs.—In his examina- tion of a moss the student at once recognizes it as a distinct advance from the kind of plant hfe exemplified by any of the eryptogamous types which he has previously studied. Root, stem, and leaf, as found in flowering plants, are represented by organs of similar function, though not of similar structure to true roots, stems, and leaves. The principle of physiological division of labor, so characteristic of the higher plants, is fairly exemplified in mosses. Although destitute of true flowers, they possess flower-like organs which may be either moncecious or dicecious. — 297. Alternation of Generations. — In mosses, as in the simpler liverworts, below them, and the more complex ferns, above them, the reproductive process includes what is known as an alternation of generations. That is to say, the organs of reproduction produce a spore which does not grow directly into a new individual like the parent. The fertilized odsphere 240 ELEMENTS OF BOTANY. produces the urn or spore-capsule, and this is really a new plant. It remains attached to the parent plant and is nour- ished by it, does not grow to any considerable size, but develops a great number of spores in its interior. These spores when fully formed are set free, germinate, and produce a thread- like protonema, which at length grows into the fully developed moss plant. The two generations, then, are the moss, with its rather complicated reproductive apparatus, and the urn, FIG. 206. B, protonema of Funaria hygrometrica, a moss; h, a well-developed primary shoot ; A, rudiment of a leaf-bearing axis, or ordinary moss plant, like Fig. 202 ; w,aroot-hair. (Magnified about 90 diameters.) destitute of such apparatus but filled with spores which are merely the product of continued cell-division in the interior of the spore-capsule. 298. Nutrition in Mosses. — Mosses, like the higher plants, draw their food supply partly in a liquid form from the earth and partly in a gaseous form from the air. It is interesting to notice, in passing, that one of the best plants with which SOME TYPES OF FLOWERLESS PLANTS. 941 to illustrate the process of setting free oxygen, which accom- panies fixation of carbon (§ 149), is an aquatic moss.’ THE STUDY OF A FERN.? 299. Conditions of Growth. —If the specimens studied were col- lected by the class, the collectors should report exactly in regard to the soil and exposure in which the plants were found growing. Do any ferns occur in surroundings decidedly different from these ? What kind of treatment do ferns need in house culture ? 300. The Underground Portion. —Dig up the entire underground portion of a plant of lady-fern. Note the color, size, shape, and append- ages of the rootstock. If any are at hand which were collected in their late winter or early spring condition, examine into the way in which the leafy parts of the coming season originate from the rootstock, and note their peculiar shape. This kind of vernation is decidedly characteristic of ferns. Observe the number and distribution of the roots along the rootstock. Bring out all these points in a sketch. 301. The Frond. —Fern leaves are technically known as fronds. Observe how these arise directly from the rootstock. Make a somewhat reduced drawing of the entire frond, which consists of a slender axis, or rhachis, along which are distributed many leaflets or pinne, each composed of many pinnules. Draw the under side of one of the pinne, from near the middle of the frond, enlarged to two or three times its natural size, as seen through the magnifying glass. Note just how each pinnule is attached to its secondary rhachis. Examine the under side of one of the pinnules (viewed as an opaque object without cover-glass) with the lowest power of the microscope, and note : (a) The ‘‘fruit-dots’’ or sori (already seen with the magnifying glass, but now much more clearly shown). (b) The membranous covering or indusiwm of each sorus. Observe how this is attached to the veins of the pinnule. In such ferns as the common brake (Pteris) and the maiden-hair (Adiantum) there is no separate indusium, but the spore-cases are covered by the incurved edges of the fronds. 1 Fontinalis. 2 The outline here given applies exactly only to Asplenium filix-femina. Any species of Asplenium or of Aspidium is just as well adapted for study. C 'ystopteris is excellent, but the indusium is hard to find. Polypodium vulgare is a simple and 942, ELEMENTS OF BOTANY. (c) The coiled spore-cases or sporangia, lying partly covered by the indusium. How do these sporangia discharge their spores ? Make a drawing, or several drawings, to bring out all these points. Examine some of the sporangia, dry, with a power of about 50 or 75 diameters, and sketch. Scrape off a few sporangia, thus disengaging some spores, mount the latter in water, examine with a power of about 200 diameters, and draw. 302. Life History of the Fern. — When a fern-spore is Sown on damp earth it gradually develops into a minute, flattish object, called a prothallium, Fig. 208. It is a rather tedious process to grow prothallia from spores, and the easiest way to get them for study is to look for them on the earth or on the damp outer surface of the flower-pots in which ferns are growing in a greenhouse. All stages of germination may readily be found in such localities. Any prothallia thus obtained for study may be freed from particles of earth by being washed, while held in very small forceps, in a gentle stream of water from a wash-bottle. The student should then mount the prothallium, bottom up, in water in a shallow cell, cover with a large cover-glass, and examine with the lowest power of the microscope. Note: (a) The abundant root-hairs, springing from the lower surface of the prothallium. (6) The variable thickness of the prothallium, near the edge consisting of only one layer of cells. (c) (In some mature specimens) the young fern growing from the prothallium, as shown in Fig. 208, B. The student can hardly make out for himself, without much expendi- ture of time, the structure of the antheridia and the archegonia, by the cooperation of which fertilization takes place on much the same plan as that already described in the case of mosses. The fertilized odsphere of the archegonium gives rise to the young fern, which grows at first at the expense of the parent prothallium but soon develops roots of its own and leads an independent existence. The mature fern makes its living, as flowering plants do, by absorption of nutritive matter from the soil and from the air, and its abundant ' chlorophyll makes it easy for the plant to decompose the supplies of carbonic acid gas which it takes in through its stomata. generally accessible form, but has no indusium. Pteris aquilina is of world-wide distribution, but differs in habit from most of our ferns. The teacher who wishes to go into detail in regard to the gross anatomy or the histology of ferns as exemplified in Pteris will find a careful study of it in Huxley and Martin’s Biology, or a fully illustrated account in Sedgwick and Wilson’s Biology. : ‘ [7 ae a og Bee SW \ SS.) = AYA 3. ey —— SRS) ce, { p/! y Ea poe oS nae Fic. 207. —A Fern (Aspidium Filizx-mas). 1, general view of the plant; a, young fronds unrolling; 2, cross-section of the rootstock, showing fibro-vascular bundles, @ a; 3, a pinnule with fruit-dots ; a a, indusium ; 4, spore-cases ; 4, vertical section through 3 @; 5, vertical section at right angles to that of (4), showing: a, section of pinnule of leaf; b, section of indusium ; ¢c, spore-cases ; 6, a single spore-case, with its stalk, a, and its elastic ring, c, discharging spores at d. (lis reduced to about } natural size; 2, 3, are slightly magnified ; 4 is more magnified ; 5, 6 are considerably magnified.) 244 ELEMENTS OF BOTANY. FERNS. 303. Structure, Form, and Habits of Ferns. —The structure of ferns is much more complex than that of any of the groups of cryptogamous plants discussed in the earlier portions of the present chapter. ‘They are possessed of well defined fibro-vascular bundles, they form a variety of parenchymatous cells, the leaves have a distinct epidermis and are provided with stomata. Great differences in size, form, and habit of growth are found among the various genera of ferns. ‘The tree ferns of * Fic. 208. — Prothallia of a Fern (Aspidium Filiz-mas). A, lower side of prothallium; ar, archegonia; an, antheridia; rh, root-hairs ; B, prothallium producing a young fern plant; b, the first leaf; w, the root, (Magnified about 8 diameters.) South America and of many of the islands of the Pacific ocean sometimes rise to a height of forty feet, while the most minute species of temperate and colder climates are not as large as the largest mosses. Some species climb freely, but most kinds are non-climbing plants of moderate size, with well developed rootstocks, which are often, as in the case of SOME TYPES OF FLOWERLESS PLANTS. 245 the bracken-fern, or brake,’ and in Osmunda, very large in , proportion to the parts of the plant visible above ground. 304. Hconomic Value of Ferns. — Ferns of living species have little economical value, but are of great interest, even to non-botanical people, from the beauty of their foliage. During that vast portion of early time known to geologists as the Carboniferous Age the earth’s surface in many parts must have been clothed with a growth of ferns more dense than is now anywhere found. These ferns, with other flower- less herbs and tree-like plants, produced the vegetable matter out of which all the principal coal-beds of the earth have been formed. 305. Reproduction in Ferns. — The reproduction of ferns is a more interesting illustration of alternation of generations than is afforded by mosses. The fruiting plant is the minute prothallium, and the non-fruiting plant, which we commonly call the fern, is merely an outgrowth from the fertilized odsphere, and physiologically no more important than the urn of a moss, except that it supplies its own food instead of living parasitically. Like this urn, the fern is an organism for the production of unfertilized spores, from which new plants endowed with reproductive apparatus may grow. 306. Lelation ¢f Reproduction in Ferns to that in Flowering Plants. — Botanists have been able to trace out in great detail the true relation which such forms of reproduction as occur in mosses and in ferns bear to that of flowering plants. Stated in the merest outline their conclusions are that the nucleated ovule cell or egg-cell (e, Fig. 142) which is fertilized by the pollen tube corresponds to the odsphere, and that part of the contents of the pollen-grain corresponds to the antherozoid.? 1 Pteris aquilina. 2See Strasburger, Noll, Schenk, and Schimper, Lehrbuch, pp. 364-367, and Potter’s Warming’s Systematic Botany, pp. 234-250. val rs ae y 4 “a ne RA cen ah os Hi if o ash) af fl . bd a . oe tn rt ‘APPENDIX A. - THE USE OF THE COMPOUND MICROSCOPE. The Instrument. — For elementary class work, a low-priced but | strong and well-made instrument is needed. Several of the German makers furnish excellent instruments for use in such a course as that -here outlined. The author is most familiar with the Leitz micro- scopes, which are furnished by Wm. Krafft, 411 West 59th St., New York City, or by the Franklin Educational Co., 15 and 17 Harcourt St., Boston. The Leitz Stand, No. IV, can be furnished duty free (for schools only), with objectives 1, 3, and 5, eye-pieces I and III, for $24.50. If several instruments are being provided, it would be well to have part of them equipped with objectives 3 and 7, and eye-pieces Land Ill. The best form of camera lucida for this microscope costs (duty free) $7.80. - The American manufacturers, Bausch & Lomb Optical Company, Rochester, N. Y., and No. 130 Fulton Street, New York City, have this year produced a microscope of the Continental type which is especially designed to meet the requirements of the secondary schools for an instrument with rack and pinion coarse adjustment and serviceable fine adjustment, at a low price. They furnish this new stand, “ AAB,” to schools and teachers at “duty-free” rates, the prices being, for the stand with two eye-pieces (any desired power), 2-inch and 4-inch objectives, $25.60, or with 2-inch, 2-inch and 41-inch objec- tives, and two eye-pieces, $29.20. - Stand « A,” the same stand as the « AAB,” without joint and with sliding tube coarse adjustment (as in the Leitz Stand IV), and with three eye-pieces and 2-inch and 14-inch objectives, is furnished for $20.40. Stand « A,” with two eye-pieces, 2-inch and 21-inch objec- tives, $20.40. Class Use of the Microscope. —If the class works in a special laboratory in small divisions (not more than twelve), the teacher can examine the preparation of the object, the focusing of the instrument, 248 ELEMENTS OF BOTANY. and the sketch which the pupil is making, —all while the work is going on. But if the class unfortunately consists of from twenty- five to forty pupils, in an ordinary recitation room, a good deal of ingenuity will be needed to secure results of any value. The microscopes with the prepared objects should be placed upon the desks or tables which are best lighted. If there are several instruments it will usually be found preferable to use all of them during any given recitation upon preparations of the same object, but to have some provided with lower and others with higher powers. It is important to have a card attached to each microscope stating what object is upon the stage and what magnifying power is given by the combination in use. The class may sometimes be divided and half, or less than half, be allowed to work with the microscope while the rest are engaged in written or oral recitation, or in examining the gross anatomy of the seed, root, stem, etc. Each student should be required to take his note-book to the microscope and draw while at the instrument. Several of the best sketches may be put on the board toward the end of the hour, and a composite drawing finally made, embodying the best portions of each. A still better plan is to have posted at the last a drawing which the instructor has prepared beforehand (best with the aid of the camera lucida, or from a photo-micrograph), and if desirable to have this copied by the class. The object sought should be to make the pupils see as much as possible for themselves, but to make sure before leaving the object that they see it as it really is. Magnifying Power.— The lowest magnifying power which will show the desired structure is to be preferred, both because this admits of the best illumination and because an average focusing which will suit most of the eyes in the class can be secured with objectives of Z-inch or longer focus, but not with higher powers. Constant use should be made of the 11-inch or 2-inch objective to give general views of the object. A double nose-piece with 2-inch and 4-inch, or l-inch and 14-inch objectives attached will save much time and trouble. The class may best be made to understand the meaning of the APPENDIX A. 249 term magnifying power by examining the same simple object as seen : with several powers. For instance, a letter of ordinary print (e.g., the finest used in this book), may be examined with the naked eye and with the magnifying glass. Then sketches on cardboard may be handed round to show the size of the object, drawn with the camera lucida as seen under the 2-inch objective, with others drawn to scale, to show the effect of all the other magnifying combinations which the microscopes belonging to the school afford. For further suggestions in regard to the manipulation and use of the microscope the teacher is referred to any of the standard works on the subject. The little book of Charles H. Clark, cited in the bibliography (Appendix D), is compact and usable. An important adjunct to the microscopical work (or, if need be, a partial substitute for it) consists in the use of photomicrographs of the most important tissues. The mounted silver-prints, or unmounted blue-prints, may be numbered and given out to the division for study at the desk after the structure in question has been studied with the micro- scope. Ample time should be given for careful examination of the pictures thus given out, and then the members of the division may be questioned individually on the photographs, or a written exercise may be set, in which all shall write as fully as possible about a designated number of the photomicrographs examined. The teacher will find that the prints differ just enough from the somewhat dia- grammatic or idealized cuts usually given in books to afford an admirable opportunity for the pupil to exercise his powers of observa- tion and discrimination in making out the exact nature of the several tissue elements to be found in each photograph. APPENDIX B. APPARATUS AND REAGENTS. » Requisites for each Student. — Every member of the class should have : Two or three mounted needles. (Prepared by forcing fine needles, eye foremost, into round slender sticks, e.g., old penholders.) A sharp penknife or a scalpel. A pair of small steel forceps. A good magnifying glass ; Coddington lenses are excellent, but rather expensive. The ordinary tripod magnifier which costs at wholesale 30 or 40 cents will answer fairly well. A large note-book of unruled paper for drawing. A drawing pencil. ‘A ruled note-book for record of experiments, ete. General Equipment of Apparatus. — Compound microscopes, as described in Appendix A. It is desirable to have one for the use of each member of the division. Usually it is not possible to secure nearly as many instruments as this. Much good work may be done with only one or two microscopes, but in this case the microscopical work will have to be done partly out of the regular class hour and part of it must be carried along while the class as a whole is doing other than microscopical work. A set of photomicrographs of some of the most important tissues described in the text, or of similar ones. Walmsley, Fuller, & Co., 134-136 Wabash Avenue, Chicago, will supply photomicrographs of botanical slides. Mr. W. H. Walmsley of this firm, who bears a national.reputation for such work, has undertaken to prepare a set of 24 negatives to illustrate the set of *1 An achromatic doublet, made by Leitz, superior to the Coddington lens, can be imported duty free for $2. It magnifies 8 times. APPENDIX B. 25% microscopic preparations described on pages 256, 257. The subjects chosen are slides 1, 2, 3, 4, 5, 7, 8, 9, 11, 13, 14, 16, 17, 20, 21, 22. A price-list of these photo-micrographs, together with many hundreds of others on botanical subjects, will soon be issued by Mr. Walmsley, who will meantime furnish the set above mentioned to teachers who wish them. Among the other botanical photomicrographs which Mr. Walmsley has in stock are those of starches, pollen, sections of woods and stems, ovaries (sections), spiral and annular vessels, leaf- sections, stomata, leaf-scales and hairs, mosses (entire), algze (marine and fresh-water), fungi. Miss E. M. Drury, 119 St. Botolph Street, Boston, will also furnish photomicrographs of the set of 24 above mentioned (from Mr. Walmsley’s negatives). Her prices will be: for unmounted blue- prints, $0.85 per dozen; for mounted silver-prints, $2.00 per dozen. A small balance. The hand-scale with 5-inch beam and set of weights from .01 gram to 20 grams, furnished by Eimer & Amend of 205-211 Third Avenue, New York, for about $2, is good enough. A trip-scale. ; The «Harvard trip-scale,” furnished by the Fairbanks Scale Co., for about $5.70, is well adapted for weighing potted plants for tran- spiration experiments, etc. A cylindrical graduate of 250 to 500 cubic centimeters capacity. One or two large bell glasses. Inexpensive one and two quart battery jars for use in cultivating potted plants, — for transpiration experiments. (Earthen flower-pots are not so good, because they permit too much evaporation through their sides.) Six or eight-quart dishes for germination experiments. Wide-mouthed bottles. Glass cylinders of about 300 cubic centimeters capacity for water cultures. A section-knife, or a razor, flat-ground on one side, hollow-ground on the other. An Arkansas oilstone. Watch-glasses. Glass-stoppered reagent bottles. 252 ELEMENTS OF BOTANY. Assorted corks and rubber stoppers. Microscope slides. Thin glass covers. Thin sheet rubber, such as is used by dentists, in pieces about 24 inches square (this is not needed if the teacher prefers to use sheet lead in the transpiration experiment; see page 115). : General Reagents and other Supplies. — Alcohol, commercial, 95%. Alcohol, absolute, a few ounces only. Hematoxylin solution.} Canada balsam. Caustic potash solution, one part of solid caustic potash in 20 parts distilled water. Nitric acid, concentrated. Red ink.? Potassium chlorate. Fehling’s solution, test for grape sugar. This reagent may best be bought of the wholesale druggist or dealer in chemicals. It may be prepared by dissolving 34.64 grams pure crystallized cupric sulphate in 200 cubic centimeters water and mixing the solution with 150 grams neutral potassic tartrate, dissolved in about 500 cubic centimeters of a 10-per-cent solution of sodium hydrate. The whole is then to be diluted with water to 1 litre and 100 cubic centi- meters glycerine added. | Millon’s reagent for proteids. Prepared by dissolving 1 part by weight of mercury in 2 parts of nitric acid of sp. gr. 1.42 and then diluting with twice its volume of water. . Preservative fluid, prepared by dissolving 20 parts by weight of chrome alum and 5 parts formalin in 975 parts of water. This serves to preserve (although it may discolor) portions of leaves, stems, rootstocks, roots, fruits, etc., which it is desirable to keep in a moist condition, and is much cheaper than alcohol. One part formalin to 40 of water by volume makes a still better preservative 1 Tt is cheaper to buy this than to make it. ~ 2 As considerable quantities of this are to be used (especially if it is issued to the class for home work), if it cannot be bought very cheaply the instructor may make it for himself by dissolving eosin in water. Eosin costs by the pound from $1.65 to $2. An ounce will make as much as two quarts of red ink. APPENDIX B. 2538 fluid, since it does not alter the natural colors of most objects kept in it. Pure glycerine. Glycerine and distilled water, equal parts. Carbolic acid crystals. Carbolic acid, 2-per-cent solution. Iodine solution, prepared by dissolving 4 grams potassium iodide in 40 cubic centimeters distilled water, adding 1 gram iodine, and, when it is entirely dissolved, diluting the solution to 1000 cubic centimeters. ; Syrups of various strengths for pollen-tube production, made by dissolving ordinary granulated sugar in boiling-hot distilled water. ' The water should be weighed cold, then heated in a flask and the weighed amount of sugar added. It will be found less troublesome to weigh out the required amounts in this way than to make a satu- rated solution and dilute it. Syrups of 2, 5, 10, 15, 25, and 30 per cent sugar will furnish range enough for experiment. If they are kept in glass-stoppered bottles which have been rinsed out with chromic acid solution and then with distilled water, the syrup will keep for months. Ammonium nitrate, 4-per-cent solution. This may be added in small quantities to potted plants as a fertilizer. Ether, commercial, for extraction of oil from seeds. (Benzine is cheaper and will answer nearly as well.) Sand, pine-sawdust, blotting-paper, for germination of seeds. Grafting-wax. Botanical apparatus and laboratory supplies of every description, including material for study, will be furnished by the Cambridge Botanical Supply Co., 1284 Massachusetts Ave., Cambridge, Mass. APPERDEX "GC, MATERIAL FOR STUDY. Chapter I.—Squash-seeds, beans, peas, sunflower-seeds. Chapter II, — Barley, red-clover-seed, seedlings of several kinds, 2-6 inches high, growing in earth, sand, or sawdust. Chapter III. — Sprouted peas, clover-seed, four-o’clock-seed, Indian corn, boiled green corn in alcohol, bean seedlings 3 weeks old, ground flaxseed, soaked corn, corn meal, flour, oatmeal, buckwheat flour, rye flour, sunflower-seeds, peanuts, Brazil nuts. Chapter IV. — Cuttings of Wandering Jew (Tradescantia zebrina), corn-stalks with roots, water-hyacinth, microscopic sections of roots, parsnips, dahlia roots or sweet potatoes, begonia leaves. Chapter V.— Twigs of horse-chestnut, hickory, beech, etc., with winter buds, potatoes, onions, rootstocks of iris, sweet flag, or sedges (best in preservative fluid). Chapter VI. — Apple twigs, fresh or in preservative fluid, hickory or white-oak twigs of three or more years old, set of Hough’s thin sections (footnote, p. 53), billets of as many kinds of native wood as are obtainable (with the ends planed smooth and split through the pith), cylinders from three or four year old hickory, or elm twigs, thin sections (see list at end), corn-stalk (in preservative fluid), palmetto, rattan, bamboo, asparagus. Chapter VII.— Fresh shoots of grapevine, twigs of oak, ash, or elm, fuchsia growing in a flower-pot, microscopic sections (see list at end), potatoes, onions. Chapter VIII.— Twigs with winter buds of horse-chestnut, hickory, beech, tulip tree, lilac. A cabbage, a Bryophyllum leaf. Chapter [X.— Leafy twigs of elm and maple, a variety of netted- veined and some parallel-veined leaves. 1 See list at end of Appendix C. APPENDIX CG. 255 Chapter X. — Potted plants of oxalis and sensitive plants, sun- flower seedlings a foot or more high to show movement of leaves to secure sunlight. Chapter XI.— Droseras and Sarracenias, potted and growing under bell glass, a cactus, a houseleek or an aloe, an Echeveria or a Cotyledon. Chapter XII. — Fresh lily leaves, microscopical preparations (see list at end), fresh hydrangea or cucumber leaves, potted hydrangeas and rubber plants (§ 144), leaves of lettuce, hydrangea, maple, hickory, or cucumber (§ 145), Elodea, Fontinalis, Spirogyra, ete. (foot- note to § 149), growing nasturtium plants, early summer and late fall leaves of trees in alcohol. Chapter XIII.— Fresh flowers of any species of Tradescantia, or living Chara or Nitella in water. Chapter XIV.— Flower-clusters of various kinds. Chapter X V. — Flowers of trillium, tulip, or buttercup. Chapter XVI. — Imperfect flowers, as those of willow, poplar, walnut, birch, hazel, begonia. Chapter XVII. — Fresh pollen of Cytisus, sweet pea, or nastur- tium, mounted slide of pollen (see list at end). Chapter XVIII.— Flowers of hazel, alder, pine grasses (wind- fertilized), insect-fertilized flowers from list in § 211. Chapter XI X.— Fruits of tomato, lemon, bean, dock. Chapter XX.—Fruits of ash, elm, or maple, of milkweed, of burdock, cocklebur, or beggar’s ticks (Bidens), of cherry, or straw- berry. Chapter X XIII. — Protococcus (or Pleurococcus). Living speci- mens are best, but mounted slides will answer. Living Spirogyra, mounted slides of Spirogyra in conjugation, desmids (fresh or mounted), growing yeast, black mould growing, a mounted slide of zygospores of Mucor, Polytrichum in various stages of growth, a mounted slide of some moss protonema, whole fern plants (including rootstocks), fruiting fern fronds, fern prothallia (fresh, or mounted for the microscope). '1 Professor Byron D. Halsted, Rutgers College, New Brunswick, New Jersey, will furnish sets of 100 weeds and of 100 weed-seeds and fruits at $10 per set; $20 for the two sets. 1. ELEMENTS OF BOTANY. List of Slides. Starch in cotyledons of bean. 2. Do. three weeks after germination. 3. Rootlet of «Chinese sacred lily,” Narcissus Tazetta, variety orientalis (longitudinal section). 4, Rootlet of barley. 5.2 Cross-section of exogenous root in its winter condition (starch). 6.2 Do. of small parsnip. (ie Cross-section, longitudinal tangential section, and longitudinal radial section of apple wood (all on one slide). 8. Do. of grapevine. 9. Do. of sassafras. 10. Macerated wood cells and bast fibres. 11. Three sections of white pine (on one slide). 12. Longitudinal section of chicory or dandelion root (ducts, parenchyma). 13. Do. rootstock of Pteris (ducts, parenchyma). 14. Do. stem of Ricinus (ducts, parenchyma). 15. Section of elder pith. 16. Cross-section of young stem of clematis. 17. Cross-section of Indian corn stem. 18. ? Do. of ash twig in winter (storage of starch). 19. Lily leaf, cross-section and under epidermis (one slide). 20. Hydrangea leaf, lower epidermis. | 21. Ficus elastica cross-section and lower epidermis (one slide). 22. Cross-section of leaf of rhododendron. 23. Cross-section of leaf of beech. 24. Pollen. 25. Protococcus. 26. Spirogyra in conjugation. 1 This set of thirty-one mounted slides and the accompanying unmounted sections in alcohol will be furnished for $6 (or if mailed for $6.20) by Miss E. M. Drury, 119 St. Botolph St., Boston. Miss Drury will also furnish other botanical slides to order at prices varying (for most preparations) from 25 to 35 cents per slide. 2 Fifty thin sections of each of these objects will be furnished in alcohol, They may be soaked in water for a few minutes, then moistened with dilute iodine solution . and examined under the microscope for starch. 27. 28. 29. 30. dl. APPENDIX C. Zygospore formation of Mucor Syzigites. Protonema of a moss. Leaf of a moss (Mnium). Prothallium of a fern. Do. beginning to grow a young fern plant. 257 ‘APPENDIX. D. -REFERENCE BOOKS.! ‘Only a few of the books which the author regards as the most’ useful guides to elementary study and research in their several departments are here named. Both pupil and teacher will find it desirable to consult some of them frequently throughout the whole course of the botanical work. The starred titles (**) indicate books which will aid the teacher, but which the ordinary high-school pupil could hardly use. Where it is possible to discriminate, the best book, that is the book which combines accuracy, fullness, newness, and simplicity of statement to the highest degree, is placed first in its own list. ~ General Works. Kerner and Oliver, Natural History of Plants. Blackie & Son, London, 1895. Henry Holt & Co., New York, 1895. Strasburger, Noll, Schenk, and Schimper, Lehrbuch der Botanik,** zweite Auflage. Gustav Fischer, Jena, 1896.? Vines, Students’ Text-Book of Botany,** 2 vols. Macmillan & Co., New York, 1895. Behrens, Text-Book of Generali Botany. Pentland, Edinburgh. The Kerner and Oliver is a costly book, but is almost indispens- able, since it goes over the greater part of the field of botany in a full and accurate, yet thoroughly simple and interesting way. The only criticism that can be urged against it is on the score of occasional fanciful statements, in regard to theories as yet unproved. The work by Strasburger and others is perhaps the best recent ' 1 The author has been much aided in the preparation of this list by the one con- tained in Spalding’s Introduction to Botany. ' 2 A translation of this book will be issued by Macmillan & Co. The author has been obliged in the present book to refer to the first German edition of the Lehrbuch, since the second edition has not reached him in season to be cited. APPENDIX D. 259 summary of botany in a moderate-sized octavo volume. Behrens’s” Botany is less recent, but very suggestive. All four books are profusély illustrated. | Laboratory Manuals. Darwin and Acton, Practical Physiology of Plants. Macmillan & Co., New York, 1894. Detmer, Das Pflanzen-physiologische Practicum,** zweite Auflage. Fischer, Jena, 1895. MacDougal, Experimental Plant Physiology. Henry Holt & Co., New York, 1895. Strasburger, Practical Botany, Macmillan & Co., New York, 1889 ; or better, Kleines Botanisches Practicum,** zweite umgearbeitete Auflage, Fischer, Jena, 1895. Spalding, Introduction to Botany. D. C. Heath & Co., Boston, 1895. Huxley and Martin, Elementary Biology (extended by Howes and Scott). Macmillan & Co., New York, 1892. Clark, Practical Methods in Microscopy. D. C. Heath & Co., Boston, 18938. Newell, Outlines of Lessons in Botany, Part I and Part II (2 vols.). Ginn & Co. The first three of the books above mentioned are devoted to experiments in vegetable physiology. Detmer’s is the best for those who can read German. Strasburger’s book is devoted to vegetable histology and is excellent, though the translation by Hillhouse (of Strasburger’s larger work) is less satisfactory than the Kleines Botanisches Practicum. Spalding’s Introduction is not wholly a laboratory manual, though largely so. It supplies admirable directions for getting acquainted with plant life and structure at first hand. Huxley’s Biology is partly devoted to animals, partly to plants. It gives excellent directions for the laboratory study of some of the lower forms of plant life. Structural and Physiological. Gray, Structural Botany. American Book Co. Gregory, Elements of Plant Anatomy. Ginn & Co., 1895. 260 ELEMENTS OF BOTANY. De Bary,** Comparative Anatomy of the Phanerogams and Ferns. Oxford, Clarendon Press, 1884. Bessey, Botany. Henry Holt & Co., New York, 1888. Thomé, Structural and Physiological Botany. John Wiley & Sons, New York, 1891. Sachs, Lectures on The Physiology of Plants. Macmillan & Co., Oxford, Clarendon Press, 1887. Gray’s Structural Botany is written in an exceedingly clear and readable style. It is not brought down to date and it gives little histology; it is well supplemented by De Bary’s work, and these two books, with the masterly lectures by Sachs, furnish a very full account of vegetable structure and life. Vines, Physiology of Plants, Cam- bridge, University Press, 1886, is more to be depended on in its chemical statements than the work of Sachs. Either Bessey’s or Thomé’s book furnishes a brief summary of anatomy and physiology. » Morphological. Goebel, Outlines of Classification and Special Morphology of Plants.** Oxford, Clarendon Press, 1887. Pax, Morphologie der Pflanzen.** Enke, Stuttgart, 1890. » Systematic. Warming and Potter, Handbook of Systematic Botany.** Mac- ‘millan & Co., New York, 1895. Engler and Prantl, Die Natiirlichen Pflanzenfamilien.** Engel- mann, Leipzig. Le Maout and Decaisne, Traite Général de Botanique.** Firmin Didot Freres, Fils & Cie, Paris. Vines, Student’s Text-Book (see above). Strasburger, Noll, Schenk, and Schimper, Lehrbuch (see above). The first-named book in the list is clear, ably written, and sufficient for all ordinary purposes. Engler and Prantl’s work in several volumes is a very large and elaborate one, not yet completed, with a wealth of illustrations. Le Maout and Decaisne’s treatise is not modern, but is abundantly illustrated and will be found useful. APPENDIX D. 261 The work of Vines and that of Strasburger and others both contain outlines of systematic botany. ‘Floras, Ete. Gray, Field, Forest, and Garden Botany. New edition by L. H. Bailey. American Book Co., 1894. Gray, Manual of Botany. Sixth edition, revised. American Book Co. Gray, Synoptical Flora of North America. American Book Co. Chapman, Flora of the Southern United States. American Book Co. Coulter, Manual of the Botany of the Rocky Mountain Region. American Book Co. Miller and Whiting, Wild Flowers of the Noriheastern States. G. P. Putnam’s Sons, 1895. (Fully illustrated.) Sargent, The Silva of North America** (in 12 vols., of which 8 have appeared ; very fully illustrated). Houghton, Mifflin & Co., Boston. Cryptogamic Botany. Eaton, Ferns of North America.** Cassino, Boston, 1879. Underwood, Our Native Ferns and their Allies. Henry Holt & Co., New York. Macdonald, Microscopical Examination of Drinking Water. Lind- say and Blakiston, Philadelphia, 1875. De Bary, Comparative Morphology and Biology of the Fungi, Myce- tozoa, and Bacteria.** Oxford, Clarendon Press, 1887. Bennett and Murray, Handbook of Cryptogamic Botany. Longmans, Green & Co., London and New York, 1889. Goebel, Outlines of Classification, etc.** (See above.} Warming and Potter, Handbook, etc.** (See above.) The number of monographs on special topics in cryptogamic botany is too great to admit, in an elementary book, of even the mere mention of the most important titles. In the list above given, the works of Bennett and Murray and of Goebel are the only general ones, and in the former mention is made of a good many of the best special treatises on cryptogamic botany. 262 ELEMENTS OF BOTANY. ’ Relation of Plants to their Environment. Miller, The Fertilization of Flowers. Macmillan & Co., London, 1883. Darwin, Jnsectivorous Plants. D. Appleton & Co., New York. Darwin, The Power of Movement in Plants. D. Appleton & Co., New York. Darwin, Animals and Plants under Domestication. D. Appleton & Co., New York. Geddes, Chapters in Modern Botany. Scribners, New York, 1893. Lubbock, Flowers, Fruits, and Leaves. Nature Series, London. Kerner, Natural History of Plants. (See above.) Wiesner, Biologie der Pflanzen.** Wien, 1889. Ludwig, Lehrbuch der Pflanzenbiologie.** Enke, Stuttgart, 1895. APPENDIX E. THE NOTE-BOOK. A good deal of the effectiveness of any course in botany which includes some laboratory work will depend on the way in which the note-book is kept. It is better to have two books, one unruled, for drawing, the other ruled, for written notes.1_ All drawings and sketches should be made in such a way as to bring out (as far as the pupil understands them) the characteristic features of the organ or structure which is under investigation. A sketch in which a good deal of detail is omitted will, therefore, often be of more value than one in which the attempt is made to represent everything. Shading is in general to be avoided. The student will need constant admonition not to conven- tionalize what he sees, or to try to give general impressions. He would, if unguided, very likely represent the cross-section of conifer- ous wood, magnified 150 or 200 times, by a set of cross-hatchings, with the lines crossing at oblique angles, thus forming a set of very regular, diamond-shaped figures. The best antidote to this tendency is to confront the conventionalizer at every turn with a camera lucida drawing of the thing which he has just sketched, or (better still) with a photomicrograph. The written notes should be kept in an orderly way; and the book which contains them needs to be indexed, day by day, as the work progresses. , The writer feels convinced, as the result of a good many years of experience, that it is a mischievous practice to require pupils of secondary-school age to take any notes from rapid dictation. Matter which cannot be furnished in cyclostyle or hektograph copies to every pupil should be dictated orally, very slowly, or else posted * 1An excellent note-book in which the pages are alternately ruled and blank, as recommended by Prof. W. F. Ganong of Smith College, is furnished by the Cam- bridge Botanical Supply Co. 264 ELEMENTS OF BOTANY. on the board, or in a typewritten copy, to which the pupils may have © free access during study-hours. Frequent and unexpected examinations of the note-books by the teacher will do more than anything else to make pupils exact and painstaking in their record of work done. Much importance should be given to the valuation of the note-book in judging of the owner’s progress in his work. It is an unpardonable fault in the teacher to allow the notes to become mechanical, and it is therefore, in the writer’s opinion, inadmissible to allow any set form of record to be followed through- out the study of any tissue or organ. ‘The observations of the pupil may well be grouped in an orderly fashion during his first studies of leaves, for example, by following in the record some such form as that given in any of the best plant-analysis blanks, but it would be ° absurd to stretch the learner’on such a Procrustes’ bed more than once. It will go far toward training the pupil into a scientific habit of mind if he is required in his notes and in his recitations to distinguish clearly the sources of his knowledge. He should be able to state whether a given piece of information was derived from his own experiment or personal study of an object or a phenomenon, from an experiment performed by the teacher in the presence of the class, from outside reading, or from study of the text-book. Both note-books should throughout present constant evidence of the care with which their owner has kept account of the way in which he became possessed of the subject-matter which he enters in them. Drawings copied from the blackboard or from any book or photo- graph should be carefully labeled in such a way as to distinguish them from original ones. INDEX AND GLOSSARY. Parr I. Accessory fruits, 195. Acuminate, 86. Acute, 86. Adaptations to conditions of exist- ence, 204-212. Adaptiveness in plants, 210-212. Adherent, 148. Adnate, 148. Adventitious buds, 84. Adventitious roots, 26. Aerial roots, 26, 27. Age of trees, 44. Aggregate fruits, 194. Air cavity, 109-111. Air, relation to germination, 8. Akene, 184-186. Albuminous substances, 24. Algze, 224-226. Alternate, 41, 94. Alternation of generations, 239, 240. Althea leaf, 110. Ameceba, 128. Anatomy of plants (see under root, stem, leaf, flower, fruit, struc- ture of). Anemone, fruit of, 185. Angiosperms, 216. Animals, defenses against, 207-210. Animal food, need of, 106, 107. Annual, 43. Annual ring, 53. Anther, 146, 154, 155. Antheridia, 239. Antherozoids, 239. Anthodium, 133. Antipodal cells, 159. Apetalous, having no corolla, 148. Apple, wood and bark, 53, 54. Aquatic roots, 28. Archegonia, 259. Arctic willow, 206, 207. Arrangement of leaves, 94-98. Arrow-shaped, 86. Ash, branching of, 40. Aspidium, 241. Assimilation, 122. Autumn leaves, coloration of, 125. Axillary bud, 79. Axillary flowers, 131. Bachelor’s button, flowers and fruit, 179, 180. Bacilli, 233. Bacteria, 233. Bark, 52. Bast, 54. Bast-bundle, 54. Bast-cell, 54. Bean, 5, 6. 266 Bean-pod, study of, 183, 184. Bees, 162, 164, 165. Beet, 32. Beet leaf, 109. Begonia leaf, osmose in, 36. Bell-shaped, 146. Berry, 194. Berry, study of, 182. Biennial, 32, 33. Birch, branching of, 44. Bird-fertilized flowers, 168. Birds plant seeds, 189. Black walnut, twig of, 80. Bladder-wrack, 225, 226. Bleeding, 68. Botany, definition of, 1. Bract, 132. Branching, alternate, 41. Branching, opposite, 40, 41. Branch-spine, 208. Breathing-pore, 109, 110, 113, 114. Bryophytes, 216. Buckwheat, 19, 22. ' Buds, 77-84. - Bud, horse-chestnut, 77, 78. - Buds, naked, 79. Bud-scales, 78. Bulb, 49, 74. Bulblets, 74.- Burs, 189-191. Buttercup, study of flower of, 140, 141. Cabbage, a bud, 80. Cactus, 49, 50. Calyx, 142. Cambium, 59, 62. Capsule, 187. Carbon, fixation of, 117-119. Carbonic acid gas, 117-119. INDEX. Carnivorous plants, 104-107. Carpel, 148, 153, 154. Carpellary, pertaining to a carpel. Carrot, 32, 33. Castor bean, 5. Castor-oil plant, bundle of, 59. Castor-oil plant, early history of stem, 61. Catkin, 152, 133. Caulicle, 5, 15. Cell, 126. Cell-contents, 126. Cell-contents, continuity of, 56. Cell-division, 220. Cell wall, 126. Cellulose, 123. Centaurea, flowers and fruit, 179, 180. Central placenta, 149. Chemical changes in leaves before falling, 124, 125. Cherry twig, 39. Chestnut fruit, 186. Chlorophyll, 111, 119. Chlorophyll bodies, 111. Cilium, 128. Circulation of protoplasm, 129, 130. Cladophyll, 50. Classification, 213-218. Cleft, deeply cut, like the hop leaf, Fig. 52, or the leaf of the com- pass-plant, Fig. 86. Clerodendron, 169. Climbing plants, 45, 46. Climates, unfavorable, 203. Cohesion, 146, 147. Coloration of autumn leaves, 125 Colors of flowers, 163, 164. Common receptacle, 133, 134. fibro-vascular INDEX. Composit, 134. Compound leaves, 92, 95. Compound pistil, 147. Compound umbel, 154, 135. Condensed stems, 48, 49. Cone, 195. Conifers, wood of, 60, 61. - Conjugating cell, 228, 224. Conjugation, 225, 224. Consolidated, 148. Continuity of protoplasm, 56. Cork, 52, 67. Cork, use of, 60, 73. Corm, 49. Corn, aerial roots of, 27. Corn, germination of, 20, 21. Corn, grain of, 20. Corn-stalk, structure of, 64, 65. Corolla, 142. Corymb, 132. Cotyledon, 5. Cotyledons, thickened, use of, 18. Crenate, 87. Cross-fertilization, 160. Cryptogamous, 216. Cryptogamous groups, 216. Cuspidate, 86. Cutting leaves, 209. Cuttings, 26, 54. Cuttings rooting, 26. Cyme, 136. Cymose, arranged in cymes, Fig. 114. Cypress, 44. Daily movements of leaves, 98, 99. Dandelion, 44. Darwin, Charles, 160. Deciduous, 124. Defenses against animals, 207-210. 267 Defenses against weather, 205-207. Definite annual growth, 48. Dehiscent fruits, 190. Dehiscence, 184. Dehiscence of capsules, 191. Deliquescent stem, 41. Dentate, 87. Desert plants, 48, 206, 207. Destruction of individuals, causes of, 203, 204. Determinate inflorescence, 136. Deutzia leaves, 96, 97. Diadelphous, 147. Diagrams, floral, 149, 151. Dichogamy, 169, 170. Dicotyledonous, 17. Dicotyledonous stems, rise of water in, 59. Dimorphous flowers, 172, 175. Dicecious, 145. Discharge of pollen, 154, 155. Disk-flowers, 134. Distinct, 146. Distribution of material in mono- cotyledonous stems, 65, 66. Dispersal of seeds, 200-202. Dock fruit, study of, 184. Dodder, 28, 29. Dormant buds, 83. Dorsal suture, 184. Double flowers, 153. Drosera, 104, 105. Drupe, @ stone-fruit, 193, 196. Dry fruits, 185-191. Duct, 31, 538, 57, 59. ‘ Egg, osmose in, 35, 36. Elliptical, 85. Eln, 42. Elm bud, 81. 268 Elm fruit, 187. Elm leaf, 85, 86. Elm, twig of, 81. Emarginate, 86. Embryo, 10. Embryo sac, 158. Endosperm, 16, 19, 20. Energy, source of, in plants, 123. Endogenous, 65, Epidermis, 67, 108-110. Epigynous, 149. Epipetalous, 149. Equitant, leaves astride of those within them, thus appearing in a cross-section like the diagram, << Essential organs, 148. Evergreen, 124. Excretion of water, 123, 124. Excurrent stem, 41. Existence, struggle for, 197-205. Exogenous, 62. Explosive fruits, 191. Fall of the leaf, 124, 125. Family, 214, 215. Family, subdivisions of, 215. Fascicled roots, 29. Fehling’s solution, 76. Fermentation, 229. Fern, study of, 241-248. Ferns, 244, 245. Fertilization, 158, 159. Fertilization, diagrammatic repre- sentation of, 159. Fibrous roots, 29. Fibro-vascular bundle, 61, 64. Fig, transpiration in, 114, 115. Filament, 146. Fir wood, 60. INDEX. Fission, 220. Fittest, survival of, 211, 212. Fixation of carbon, 117-119. Fleshy fruits, 191-195. Fleshy roots, 32, 33. Floral diagrams, 150, 151. Floral envelopes, 143. Floral organs, movements of, 171, 172. Flower, nature of, 152, 153. Flower, organs of, 142, 143. Flower, plan of, 143, 144. Flower-buds, 80, 131. Flowerless plants, 219-245. Flowers, colors of, 163, 164. Flowers, odors of, 163. Flytrap, Venus’, 106. Follicle, 186, 187. Food, storage of, in stem, 72. Four-o’-clock seed, 19. Free, 149. Free central placentation, 148. Frond, 241. Frost, action of, 125. Fruit, 185-196. Fruit-dots, 241. Fruits, study of, 182-184. Fruits, uses of, 188, 191-193. Fucus, 225, 226. Fungi, 252-255. Funiculus, the stalk on which an ovule is borne, 159, 184. Gamopetalous, 146. Gamosepalous, 146. Genus, 218. Germination, 4-9. Germination, chemical changes during, 9. Germination, conditions of, 6-9. INDEX. Grafting, 63, 64. Grain, 186. Gray, Asa, 44. Gourd-cell, 55. Grape sugar, test for, 75, 76. Green layer of bark, 52, 60. Groups, natural, 216. Growth, measurement of, in stem, 15, 16. Growth, secondary, 62, 63. Guard-cells, 114. Gymnosperms, 216. Hairs, 113, 209. Halberd-shaped, 86. Hastate, 86. Haustoria, 28. Head, 133. Heart-shaped, 86. Heartwood, 59. Herb, 43. Herbaceous, herb-like, Hesperidium, 182, 194. Hilum, 4. Honey-bee, leg of, 162. Honey-gland, 163. Horse-chestnut bud, study of, 77, 78. Horse-chestnut leaf, 95. Horse-chestnut twig, 38. Host, 28, 29. Hot springs, plants in, 204. Hybrid, 214. Hydrangea, transpiration in, 114- 116. Hydrogen, 119. Hyphe, 231. Hypogynous, 149. Imperfect flowers, 145. 269 Increase, rate of, 199, 200, 204, 205. Indefinite annual growth, 43. Indehiscent fruits, 186-189. Indeterminate inflorescence, 131, Indian corn, germination of, 20. Indian corn, structure of stem, 64, 65. Indian pipe, 120, 121. India-rubber plant, transpiration in, 114-116. Indusium, 241. Inflorescence, 131-136. Inflorescence, diagrams of, 135. Insect fertilization, 161-175. Insect fertilization, studies in, 173- 175. Insectivorous plants, 104-107. Insects, pollen-carrying apparatus of, 162. Insect-traps, leaves as, 104-107. Intercellular spaces, 109-111. Internode, 15, 39. Involucre, 133. Iodine a starch-test, 21, 22. Ipomeea, rate of increase of, 199, 200. Tris, flowers and fruit, 181. Tris, rootstock of, 48. Iron, 122. Ivy, aerial roots of, 26. Kidney-shaped, 85. Labiate, 148. Lady-fern, 241. Lanceolate, 85. Leaf, 85-125. Leaf, accumulation of mineral matter in, 117. 270 Leaf-arrangement, 40. Leaf-bases, 86. Leaf-buds, 80. Leaf disguises, 107. Leaf, fall of, 124, 125. Leaf-like stems, 49. Leaf-margins, 87. Leaf-outlines, 85. Leaf-spine, 102. Leaf-stalk, 86. Leaf-tendril, 103, 104. Leaf-tips, 86. Leaf-trace, 111, 112. Leaves, arrangement of, 94-98. Leaves as insect-traps, 104, 105. Leaves, movements of, 98-101, 108, 104. Leaves, functions of, 112-125. Legume, 183. Lemon, study of, 182, 183. Lenticel, 52, 67. Liana, 45, 50. Lichens, 234, 235. Light, 118, 119. Light, effect on germination, 6, 7. Light, movements towards, 100, 101. Lily leaf, 108, 109. Lime, 117. Linden bark, 54. Linden fruit, 188. Linden wood, structure of, 54. Linear, 85. Living parts of the stem, 67. Lobed, having rounded segments, like the oak leaf in Fig. 77. Mahogany wood, structure of, 57. Mallows, fertilization in, 170, 171. Malt, 10. INDEX. Maltose, 75. Maple fruit, 187. Maple leaf, 88, 89. Maple, seedling, 15. Maple wood, structure of, 56. Medullary ray, 31, 53, 59, 62. Melon-cactus, 50. Metabolism, 122, 128. Midrib, 87. Millon’s reagent, 25. Mineral matter accumulated in the leaf, 117. Mistletoe, 28. Monadelphous, 147. Monocotyledons, 17. Monocotyledonous, 17. Monocotyledonous stem, 65, 66. Monocotyledonous stems, rise of water in, 66. Moneecious, 145. Monotropa, 120, 121. Morning-glory, rate of increase of, 199, 200. Morphology, 1, 16. Moss, study of, 255-239. Mosses, 239-241. Moths, 167. Mould, black, study of, 250-232. Movements of floral organs, 171, 172. Movements of leaves, 98-101. Movement of water in plants, 68-72. Movements toward light, 100, 101. Mucronate, 86. Mulberry, 195. Multiple fruits, 195. Multiple primary roots, 29. Multiplication of cells, 220. 5 INDEX. Mycelium, 231. Myrsiphyllum, 50, 51. Naked buds, 79. Nasturtium leaves, starch in, 121. Natural selection, 212. Nectar, 162, 163. Nectar-glands, 163. Nectar-guides, 164. Nectaries, 163. Netted-veined, 87, 88. Nitric acid, test for proteids, 24. Nitrogen, 122. Nocturnal position, 98, 99. Node, 15, 39. Nourishment, storage of, 17-25. Nucleus, 128. Nut, 186. Nutrient substances, 122. Nutrition of plants, 119-123. Oak, leaf-arrangement of, 94. Oak wood, 53. Oat, germination of, 21. Obovate, 86. Obtuse, 86. Odors of flowers, 163. Oil, 24. Oil, testing seeds for, 24. Onion, structure of, 74. _ Onion, tests of for food-materials, 75, 76. Odsphere, 226. Opposite, 40. Orbicular, 85. Order, 214, 215. Osmose, 35-37, 71. Ovary, 146. Ovate, 85. Ovule, 157-159. 271 Ovule, structure of, 159. Oxidation, 9. Oxygen, 118. Oxygen-making, 118. Palisade cells, 108. Palmate, 88. Pampas region, 205. Panicle, 134. Panicum, 201. Papilionaceous corolla, one which is more or less like a butterfly in shape, Fig. 119. Parallel-veined, 90, 91. Parasite, 28. Parasitic roots, 28, Parenchyma, 58. Parietal placenta, 148. Parsnip root, study of, 32. Pea, 4, 6, 8, 10, 18. Pear, flowers and fruit, 178. Pedicel, 132. Peduncle, 132. Pepo, 193, 194. Perennial, 33, 34. Perfect, 148. Perianth, 139. Pericarp, 193. Perigynous, 149. Petal, 137. Petiole, 86. Phanerogamous, 216. Phanerogamous groups, 216. Phosphorus, 122. Physiology, vegetable, 2. Pigeon-wheat moss, study of, 255- 239. Pine, seedling, 17. Pine wood, 60. Pinnate, 87, 89. 272 Pistil, 143. Pistillate, containing pistils but not stamens. Pistil, parts of, 146, 147. Pitcher plant, 104, 105. Pith, 54. Pod, 187. Poisonous seeds, 25. Placenta, 147, 148. Plumule, 5. Pollarded trees, 84. Pollen, 146, 155, 156. Pollen-carrying apparatus, 162. Pollen, discharge of, 154, 155. Pollen-grains, 155. Pollen-grains, number of per ovule, 159. Pollen, protection of, 166, 167. Pollen, protection of from rain, 175, 176. Pollen tube, 155, 156. Pollen tubes, 156-158. Polypetalous, 146. Polysepalous, 146. Polytrichum, 2385-289, Pome, 193. Pondscum, study of, 221-224. Potash in hay, 117. Potato, 47, 73, 74. Potato seedling, 47, 49. Potato tuber, 73, 74. Prickly leaves, 103. Prickle, 208, 209. Primary root, 26, 29. Primrose, fertilization in flowers of, 172, 178. Procambium, 65. Prosenchyma, 58. Protection of pollen, 166, 167. Proteids, 24, 74, 75. INDEX. Proteids, tests for, 24, 25, 75. Prothallium, 242. Protonema, 238. Protococcus, study of, 219-221. Protoplasm, 36, 37, 122. Protoplasm, characteristics of, 128-130. Protoplasm, circulation of, 129, 150. Protoplasm, continuity of, 56. Pteridophytes, 216. Race, 214. Raceme, 152. Radial section, 56. Raspberry, 195. Ray, medullary, 31, 53. Ray-flowers, 134. Receptacle, 144, 145. Reflexed, turned down or under. Regular flowers, 143. Reproduction in alge, 225, 226. Reproduction in ferns, 245. Reproduction in flowering plants, 158-160. , Reproduction in fungi, 235. Reproduction in Mosses, 256-239. Resin-passage, 60. Respiration, 128, 124. Retuse, 86. Rhachis, 241. Rhizopus, 230-252. Ring, annual, 55. Ringent, 148. Rise of water in stems, 66, 68, 69. Rockweed, 225, 226. Root, 26-87. Root-cap, 14, 15. Root-climbers, 45. Root-hair, 12, 15, 35-87. Root pressure, 37, 71. INDEX. Roots, absorption through, 34, 35. Roots, growth of, 12. Roots, propagation by, 34. Rootstock, 47, 48. Roots, storage of nourishment in, 32, 33. Roots, structure of, 30-32. Root-system, 33, 34. Rotation of protoplasm, 129. Russian thistle, 201, 202, 205. Sage, fertilization in flowers of, 171, 172. Sago-palm, 72. Salver-shaped, 147. Sap, descent of, 69. Sap, rise of, 58, 68, 69, 116. Saprophytes, 121. Sapwood, 59. Scalloped, 87. Scape, a naked or merely bracted peduncle, rising from the ground, as in the dandelion. Sclerenchyma, 64. Secondary growth, 62, 63. Secondary root, 26. Sedge, rootstock of, 48. Section, wood, 53, 54, 56, 57, 59, 60. Seed, 4-25. Seeds, dispersal of, 200-202. Seed-leaf, 5. Seedling, parts of, 12. Selection, natural, 212. Self-fertilization, 160. Sepal, 137. Separated flowers, 145. Sequoia, 44. Series, plants form a, 217. Serrate, 87. Sessile, not stalked, as leaves with- 2738 out petioles, or anthers without Silaments. Shrub, 43. Sieve-plate, 55, 56. Sieve-tube, 55, 56. Silica, 117. Simple leaves, 91. Simple pistil, 147. Sinuate, 87. Sleep of leaves, 98, 99. Slime-moulds, 126-128. *¢ Smilax,’ 50, 51. Sori, 241. Spatulate, 87. Species, 213. Spike, 132, 133. Spine, 207, 208. Spiral vessel, 59. Spirogyra, study of, 221-224. Spore, 126-128. Squash-seed, 4, 5. Stamen, 1438. Stamen, parts of, 146. Staminate, containing stamens but not pistils. Standard, one of the petals in a papilionaceous flower (the large upright one shown in Fig. 195). Starch, 21-23, 72. Starch disappears during germina- tion, 25. Starch-making, 119-121. Starch, testing seed for, 21, 22. Stem, 38-76. Stem, early history of, 61, 62. Stem, functions of cells of, 58, 59. Stemless plants, 44. Stem, modifiability of, 50, 51. Stem, monocotyledonous, 64-66. Stems, storage of food in, 72. 274 Stem, structure of, 52-64. Stigma, 144, 146. Stigma, structure of, 156, 157. Stinging hair, 129, 209. Stipules, 90. Stomata, 109, 110, 115, 114. Stone-fruit, 191, 193. Storage of food in the stem, 72, 73. Strawberry, 195. Struggle for existence, 197-205. Sugar, formed during germination, 10. Sundew, 104, 105. Survival of the fittest, 211, 212. Style, 146. Sugar, 75, 76. Suture, 184, 187. Sweet pea, flowers and fruit, 177, 178. Symmetrical, 143, 144. Tangential section, 56. Taper-pointed, 87. Taproot, 30. Tegmen, 5. Temperature, relation to germina- tion, 7. Tendril, 46. Tendril climbers, 46. Terminal flowers, 156. Terminal bud, 81. Testa, 5. Thallophytes, 216. Thistle, Russian, 201, 202, 205. Three-ranked, leaves forming three rows up and down the stem, as in sedges. Tickle-grass, 201. Tissue, 58. Tomato, study of, 182. INDEX. Transition from stamens to petals, 152, 153. Transpiration, 113-116. Tree, 43. Trillium, study of flower of, 137, 138. Trimorphous flowers, 1753. Tropzolum leaves, starch in, 121. Truncate, 86. Trunk, 41, 42. Tuber, 47. Tulip, study of flower of, 139, 140. Twiners, 46. Two-ranked, leaves forming tw) rows up and down the stem, as in grasses. Types of flowerless plants, 219- 245. Types, order of appearance of, 217. Umbel, 132. Umbellet, 135. Underground stems, 46-48. Unicellular plants, 219, 220. Union of pistils, 147. Union of stamens, 147. Urns of mosses, 236. Urn-shaped, widened at the bottom, with a narrower mouth, like the corolla of the bearberry, Fig. 148, V. Vacuole, 227. Variety, 214. Vegetable physiology, 2. Vein, 90. Venation, 90, 91. Ventral suture, 184. Venus’ flytrap, 106. INDEX. Vernation, 82, 83. Vertically placed leaves, 99, 100. Vessel, 31, 53, 59. Water, absorption by roots, 54-37. Water, amount transpired, 113-116. Water, excretion of, 125, 124. Water, movement of, 66, 68-72. Water roots, 28. Weapons of plants, 208-210. Weather, protection from, 175, 176, 205-207. Wedge-shaped, 85. Weeds, 197-199. Weeds, study of, 198. Wheat-grain, section of, 28. Wheel-shaped, 147. 275 Whorled, arranged in a circle around the stem; for example, leaves borne three or more at a node. Willow, Arctic, 206, 207. Willow, adventitious buds of, 84. Wilting, 70, Wind-fertilization, 160, 161. Winged fruits, 188. Wood-cell, 57, 58. Wood of linden, 54. Wood, structure of, 52-64. Yeast, study of, 226-230. Zoospores, 221. Zygospores, 223. oe. Ve 23: PRS ow : reduc G pees Sy ee Pe kus ps paises ats jee iy. eee peer saKoRea yy LOS feats part “eg oe Mie: ees | 19) tease ae SE RES an abe seid pees ay ante mee. <3 < ae a ? i g 4 Pikied » a . © SAG ge. er oy a a] Sere as % ot gtk PAP? II. KEY AND FLORA. EMBRACING A FEW ,OF THE COMMONEST SPRING FLOWERS OF THE NORTHERN AND MIDDLE STATES. “ee ae CEG a) enn EAR. LL ee ‘In order to determine an unknown species, the student is first to make a careful examination of the plant in hand. After noting in a general way the appearance of the root, stem, and leaf, including a cross-section of the stem, he should study the number, coherence, and adnation of the parts of the flower, then make and draw a cross-section and a length- wise section of it. Irregularities in calyx or corolla, pecu- liarities in the shape, structure, or operation of the essential organs, such for instance as anthers discharging through chinks in the end, should be noted. Next, the inquirer should look carefully through the Key to the Families. He is first to decide whether the plant in question is a Gymnosperm or an Angiosperm ; if not a conif- erous tree or shrub it will of course belong to the latter division. He is then to settle the question whether it is a Monocotyledon or a Dicotyledon, then under what division of the group the plant comes, and finally, to decide upon its Family. Turning now to the page at which the family is described, a rapid inspection of the characteristics of the genera will make it evident to which one the species under examination belongs. It may not infrequently prove that none of the genera described agree with the plant studied, and in that case the student must either consult a larger flora or rest satisfied with having determined the family to which his specimen belongs.1 The identification of the species, after 1 ]t will greatly simplify matters if the teacher selects for examination only such Species as are here described. - 4 ELEMENTS OF BOTANY. the genus has been reached, presents no difficulty in a little flora like the present one. The author does not believe in spending much of the time of a class upon identifying species, but would rather recom- mend comparative studies of as many plants of a group as are accessible, and making these studies thorough enough to bring out fully the idea of the Family, the Genus, and the Species.!. The descriptions in Part II of this book may be used as a check on the cruder ones which the pupil is first to frame for himself. 1 The teacher will find abundant suggestions for such a course in Spalding’s Introduction to Botany, pp. 152-260. KEY TO SOME FAMILIES OF PHANEROGAMS. GYMNOSPERMS. Ovules not enclosed in an ovary. Trees or shrubs usually with needle-shaped, or scale-like, evergreen leaves and moneecious or dicecious flowers in catkins, the pistillate ones usually ripening into cones (Conifer), Pine Family, 7. ANGIOSPERMS. Ovules in an ovary. MONOCOTYLEDONS. Flowers generally on plan of 3 (never of 5). GLUMACEOUS DIVISION. Flowers rudimentary, enclosed in husk-like bracts. Byacts for each flower 2 (Graminez), stems cylindrical or nearly so, Grass Family, 9. Bract for each flower 1 (Cyperacez), stems triangular, Sedge Family, 10. SPADICEOUS DIVISION. Flowers clustered on a spadix (Aracez), Arum Family, 11. PETALOIDEOUS DIVISION. Flowers having a true perianth ; not on a spadix. Ovary free from perianth, stamens 6 (Liliacez), Lily Family, 12. Ovary adnate to perianth. Stamens6. . . . (Amaryllidacee), Amaryllis Family, 15. Stamens 3 . (Iridacez), Iris Family, 15. Stamens lor (rarely)2 . . (Orchidacez), Orchis Family, 16. DICOTYLEDONS. Flowers generally on plan of 5 or 4. APETALOUS. Flowers without corolla (sometimes also calyx wanting). Flowers in catkins. Dicecious trees or shrubs ; fruit, a pod (Salicacez), Willow Family, 17. Flowers in catkins. Moneecious trees or shrubs; fruit, a nut (Cupu- liferee), Oak Family, 18. Flowers not in catkins. (Here occur a few apetalous genera of certain polypetalous families.) Stipules sheathing the stem at the nodes (Polygonacee), Buck- wheat Family, 19. Stipules not sheathing the stem, or absent ; plants usually with a milky acrid juice (Euphorbiacee), Spurge Family, 31. [Here come also Elms, some Maples, ete.] ELEMENTS OF BOTANY. POLYPETALOUS. Flowers having distinct petals. Stamens on receptacle (hypogynous). Numerous, and all floral organs distinct (Ranunculacee), Crowfoot Family, 22. 4 long and 2 short (sometimes fewer) ; petals 4 (Crucifere), Mustard Family, 24. Few and definite; flowersregular . . . . (Caryophyllacee), Pink Family, 20. 5; flowersirregular . . . . (Violacew), Violet Family, 32. Numerous and with the filaments united . . . . (Malvaceze), Mallow Family, 51. Stamens on calyx (perigynous). Carpels fewer than sepals ; leaves without stipules (Saxifragacee), Saxifrage Family, 26. Carpels 2 or more (genus Prunus only one); leaves with stipules (Rosacez), Rose Family, 27. Carpel1 . . . . . . (Leguminosz), Pulse Family, 29. Stamens on ovary (epigynous) (Umbelliferze), Parsley Family, 54. [Near this come Evening Primroses, Cornels, and Gourds.] GAMOPETALOUS. Petals united into a cup or tube. (A few have also dis- tinct petals.) Ovary free from calyx. Corolla regular. Ovary deeply 4lobed . (Borraginacez), Borage Family, 39. Ovary 2celled, filled with ovules (Solanacee), Nightshade Family, 42. {Near this are Morning-glories, Phloxes and Gentians.] Ovary 1-celled, stamens opposite corolla-lobes (Primulacez), Prim- rose Family, 38. Corolla irregular. Ovary deeply 4lobed . . . . (Labiate), Mint Family, 40. Ovary entire, 2-celled (Scrophulariacee), Figwort Family, 43. Corolla regular or irregular. Ovary usually with as many cells as the corolla has lobes, anthers opening by a hole at the apex of each cell (Ericacez), Heath Family, 36. Ovary adnate to calyx. Stamens distinct, on corolla; leaves opposite, without stipules (Capri- foliaceze), Honeysuckle Family, 46. Stamens distinct, on corolla, leaves opposite, with stipules, or whorled withoutthem . . . (Rubiacee), Madder Family, 44. Stamens distinct, not on corolla (Ericacee), Heath Family, 36. Stamens united by their anthers; flowers in heads (Compost Composite Family, 48. CLASS I.—GYMNOSPERMS. Plants destitute of a closed ovary, style or stigma ; ovules generally borne naked on a carpellary scale, which forms part of a cone. Cotyledons often several (Fig. 6). CONIFERE, PINE FAMILY. y Trees or shrubs with wood of peculiar structure (Figs. 50, 51) destitute of ducts, with resinous and aromatic juice, leaves generally evergreen and needle-shaped or awl-shaped, and flowers destitute of floral envelopes, moncecious or dicecious, the staminate ones commonly in catkins, the pistillate ones in cones. I. PINUS, PINE. Sterile flowers spirally arranged in inconspicuous catkins, borne at the base of the young shoot of the season, each flower consisting of a single, nearly sessile anther (Fig. 209, 2). Fertile flowers in catkins which consist of spirally arranged carpel-scales, each scale springing from the axil of a bract and bearing at its own base two ovules (Fig. 209, 5). Fruit a cone, formed of the thickened carpellary scales, ripening the second autumn after the flower opened. Primary leaves, thin and chaffy bud-scales, from the axils of which spring the bundles of 2—5 nearly persistent, needle-like, evergreen leaves, from 1-15 in. long (Fig. 209, d). a. (P. stroBus), WHITE Pine. A tall tree, 75-160 ft. high, much branched and spreading when growing in open ground, but often with few or no living branches below the height of 100 ft. when growing in dense forests. Leaves clustered in fives, slender, 3—4 in. long, smooth, and pale or with a whitish bloom. Cones 5—6 in. long, not stout. The wood is soft, durable, does not readily warp, and is therefore very valuable for lumber. 8 ELEMENTS OF BOTANY. b. (P. r1iGgipA), NORTHERN Pircu Pine. A stout tree, 30-80 ft. high, with rough scaly bark. Leaves in threes, 3-5 in. long, stiff and flattened. Cones ovate-conical, 2-3 in. long, their scales tipped with a short, abruptly curved spine. Wood hard, coarse and resinous, mainly used for fuel. Fie. 209.—Scotch Pine (P. sylvestris). 1, a twig showing: a, staminate catkins ; b, pistillate catkins ; c, a cone; d, needles. 2, an anther, a, side view ; b, outer surface. 3, a carpel-scale, a, inner surface ; b, outer surface. 4, a cone-scale, a seed-wing and a seed. 5, section of a seed, showing the embryo. (1) is natural size ; the other parts of the figure are magni- fied by the amount indicated by comparison with the vertical line alongside each. c. (P. sy_vestris), Scorcn Pre (wrongly called Scotch Fir). A medium-sized tree, with the older bark reddish and scaly. Leaves in twos, 13-23 in. long. Cones rather small and tapering (Fig. 209, c). Cultivated from Europe. ANGIOSPERMS. 8) I. LARIX, LARCH. Catkins short, opening in early spring, before the leaves ; the fertile ones, while in flower, of a beautiful crimson color. Fruit a small cone, with thin scales. Leaves, none of them scaly, but all needle-shaped, soft, deciduous, very numerous, in little brush-like bundles. a. (L. AMERICANA), AMERICAN LArcH, TAMARACK, HACKMa- TACK (wrongly, but quite generally, called Cypress and Juniper). . ee in Arithmetic (in one vol.) . .80 | Wenrworth & Reed’s First Steps Completes: ; all vie, 3h h a Aiea five rs faa MRE TY RLS a babs imine tos cits sh Ts Viste tata ae es ~ er 399 York Botanical Gna unary QK47 —_ s of botan TW iii) 3 518 eM i aN + ‘4 5 i a) Wy as i or i is ¢ es i \S MOQ \ NS . . \ . . : SY XV XG \N \ WN