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UEFEKKXCK TO THE STUDY OK CANADIAN PLANTS; TO AVHIf'H IS ADDED A SELECTTOX OK EXAMINATION PAPERS BY H. B. SPOTTON, M.A., F.L.S. PniNClPAL OK HARnORD ST. COM'^< PREFACE TO REVISED EDITION. The re-arrangement of the course of study in Botany for Teachers' Certificates and for Junior Matriculation has afforded an opportunity for revising and, it is hoped, improv- ing the present text-book, to which so kind a reception was accorded on its first appearance some years ago. The principal feature of the new curriculum is the addition of certain Cryptogamous types. These are necessarily some- what more difficult of study than the Phanerogams, because their characteristics cannot be satisfactorily made out without employing high powers of the microscope ; but it is hoped that the numerous illustrations which accompany the text, and which have been gathered from various sources, will materially assist the student in this part of the work. The chapter relating to minute structure has been re- written, and, as will be seen, considerably extended. Though it is still but a sketch, it is hoped that it will serve a useful purpose in paving the way for the fuller study of the anatomy and physiology of plants with the aid of advanced works. Other changes and additions have also been made, chiefly in the chapter on Morphology. The writer need hardly add that in preparing this revision he has laid under contribution the various text-books of recognized merit which have come within his reach, and that beyond the mere presentation of the subject he lays no claim to originality. Barriey August. 1SS7. TABLE OF COMMON PLANTS EXAMINED. PHANEROGAMS. Buttercup, Hepatica, Marigold Shepherd's Purse Marsh - representing it RANUNCULACEiE. Crucifer^. Round-leaved Mallow MALVACEifi. Garden Pea LEGUMINOSiE. Great Willow-herb.. ONAGRACEiK. Sweet Brier, Strawberry, Crab- Apple, Cherry, Raspberry Rosacea. Water- Parsnip Umbelli fer.e. Dandelion Composit,«. Catnip Labiat^h. Cucumber CuCURBITACEi«. Oak CuPULIFERiC. Willow SALICACEiE. Maple SAPINDACEiE. Dog's-tooth Violet . . . LlLIACE^. Iris IP.LDACEiE. Orchis Orchidace^. Indiax Turnip, Calla ARACEiE. Timothy, Red - top. Meadow - Grass, Chess, Couch (Juass, Old-witch Grass, Barnyard Grass, Foxtail (( Gramine^. White Pine, Ground Hemlock i I Conifers. CRYPTOGAMS. Polypody r "presenting Ferns. Common Club- Moss Common Horsetail Hair-Moss Marchantia polymorpha, Parmelia parietina Common Mu.shroom Chara fh \GILIS lvcopods. Horsetails. Mosses. Liverworts. Lichens. Mushrooms. The Chara3. CONTENTS. PAUB. Introouction 1 Chapter I. — Examination of a liuttcicup t^ Chapter II. — Functions of the Organs of the Flower 11 Chaptp:r III. — Examination of Hepatica and Marsh-Mari- gold— Resemblances between their Flowers and that of Buttercup 14 CilAPTER IV. — Examination of other Common Plants with Hypogynous Stamens — Shepherd's Purse — Round- leaved Mallow 22 Chapter V. — Examination of Common Plants with Perigy- nous Stamens — Garden Pea — Great Willow-herb ?9 Chapter VI. — Examination of Common Rosaceous Plants — Sweet Brier — Strawberry — Cherry — Crab- Apple — Raspberry 35 Chapter VII. — Examination of a Plant with Epigynous Stamens — Water-Parsnip 41 Chapter VIII. — Examination of Common Plants with Epi- petalous Stamens — Dandelion — Catnip 43 Chapter IX. — Examination of Plants with Monoecious FloAvers — Cucumber — Oak 48 Chapter X.— Examination of Plants with Dia^cious Flowers — Willow — Maple 54 Chapter XI. — Characteristics possessed in common by all the Plants previously examined — Structure of the Seed in Dicotyledons 59 Chapter XII. — Examination of Common Plants continued — Dog's-Tooth Violet— Triliium— Iris— Orchis 61 Vlll CONTENTS. Chapter XIII. — Examination of Spadioeous Plants — Indian Turnip— Calla 72 Chapter XIV. — Examination of Glumaceous Plants — Timo- thy and otlier Grasses 78 Chaptkh XV. — Common Characteristics of the Plants just Examined — Structure of the Seed in Monocotyledons.. 84 Chapter XVI.— Examination of Coniferous Plants — White Pine — (iround Hemlock 87 Chapter XVII. — Morphology of Roots, Stems, and Foliage- Leave.s of Phanerogams 93 Chapter XVIII. — Morphology of Flower- Leaves — Inflor- escence—The Calyx — The Corolla -Tlie Stamens — The Pistil— The Fruit- -The Seed— Germination.... 123 Chapter XIX. — On the Minute Structure of Plants — The Cell — Tissues -- Tissue -Systems — Exogenous and Endogenous Stems 156 Chapter XX. — Food of Plants — Chemical Processes — Movements of Water — Phenomena of Growth 177 Chapter XXI. — Examination of a Fern — A Horsetail — A Club Moss. 184 Chapter XXII. — ^Examination of a Moss and a Liverwort... 190 Chapter XXIII. — Examination of a Mushroom — A Lichen —A Chara 196 Chapter XXIV. — Classification of Plants according to the Natuial System \ . . 206 I>*DEX Z.f^ THE ELEMENTS OF STRUCTURAL BOTANY. 1. The study of Botany is commonly rendered unat- tractive to the beginner hy the order in which the parts of the subject are presented to him. His patience be- comes exhausted by the long interval which must neces- sarily elapse before he is in a position to do any practicr:,! work for himself. In accordance with the usual plan, some months are spent in committing to memory a mass of terms desci'iptive of the various modifications which the organs of plants undergo ; and not until the studem. ha-s mastered these, and perhaps been initiated into the mysteries of the fibro-vascular system, is he permitted to examine a plant as a whole. In this little work, we purpose, following the example of some recent writers, to reverse this order of things, and at the outset to put into the learner's hands some comra;-;. p'-^^^+^^s, and to lead him, by his own examination of t: 3se, to a know- ledge of their various organs — to cultivate, in short, not merely his memory, but also, and chiefly, his powers of observation. • 1 Z ELEMENTS OP STRUCTURAL BOTANY. It is desirable that the beginner should provide him- self with a magnifying glass of moderate power for examining the more minute parts of specimens ; a sharp penknife for dissecting ; and a couple of fine needles, which he can himself insert in convenient handles, and which will be found of great service in separating delicate parts, and in impaling fine portions for examination with the aid of the lens. CHAPTER I, EXAMINATION OF A BUTTERCUP. 2. To begin with, there is no plant quite so suitable as our common Buttercup. This plant, which has con- spicuous yellow flowers, may be found growing in almost every moist meadow. Having found one, take up the whole plant, loosening the soil a little, so as to obtain as much of the Root as possible. Wash away the earth adhering to the latter part, and then proceed to examine your specimen. Begin- " ning with the Root (Fig. 1), the first noticeable Fig. 1 thing is that it is not of the same colour as the rest of the plant. It is Fiar. 1.— Fibrous Root oJ Buttercup. EXAMINATION OF A BUTTERCUP. 3 nearly white. Then it is not of the same form as the part of the plant above ground. It is made up of a num- ber of thread-like parts which spread out in all directions, and if you examine one of these threads through your magnifying glass, you will find that from its surface are given off many finer threads, called rootlets. These latter are of great importance to the plant ; it is largely by means of their tender extremities, and the parts adjacent to these, that it imbibes the nutritious fluids contained in the soil. Whilst you are looking at these delicate rootlets, you may perhaps wonder that they should be able to make their way through the soil, but how they do this will be apparent to you if you examine the tip of one of them with a microscope of considerable power. Fig. 2 repre- sents such a tip highly magnified. It is to be observed that the ijrowth of the rootlet does not take place at the very extremity, but immediately behind it. The extreme tip consists of harder and firmer matter than that behind, and is in fact a sort of cap or thimble to protect the growing part underneath. As the rootlets grow, this little thimble is pushed on first through the crevices of the soil, and, as you may sup- pose, is soon worn away on the outside, but it is as rapidly renewed by the rootlet itself on the inside. Another difference between the root and the part above ground you will scarcely have failed to discover : the root has no leaves, nor has it any buds. You may describe the root of the Buttercup as fibrous. Pig. 2. Fig hindTl . 2.— Extremity of rootlet ; a, tlie iuirder tip ; />, tlie growing portion b«< the tip. 4 ELEMENTS OP STRUCTURAL BOTANY. 3. Let US now look at the Stem (Fig. 3). It is upright, pretty firm, coloured green, and leaves spring from it at intervals. As there is scarcely any appearance of wood in it, we toay describe it as herbaceous. At several points along the main stem branches are given off, and you will observe that immediately h^ low the point from which every branch springs there is a leaf on the stem. The angle be- tween the leaf and the stem, on the upper side is called the axil of the leaf {axilla^ an armpit), and it is a rule to which there are scarcely any exceptions, that branches can only spring from the ax51s of leaves. The stem and all the branches of our plant termi- nate, at their upper extremi- ties, either in flowers or in flower- buds. 4. Let us now consider the Leaves. A glance wiU show you that the leaves of this plant are not all alike. Those at the lower end of the stem have long stalks (Fig. 4), which we shall henceforward speak of &,& petioles. Those a little higher up have petioles too, but they are not Fig. 3. Fig. 8.-^tem of Buttercup. EXAMINATION OF A BUTTERCUP. Fig. 4. quite so long as the lower ones, and the highest leaves have no petioles at all. They appear to be sitti'ig on the stem, and hence are said to be sessile. The lowest leaves of all, as they seem to spring from the root, may be described as radical, whilst the higher ones may be called cauline [caul is, a stem). The broad part of a leaf is its blade. In the plunt we are now examining, the blades of the leaves are almost divided into distinct pieces, which are called lobes, and each of these again is more or less deeply cut. Both petioles and blades of our leaves are covered with minute hairs, and so are said to be hairy. Hold up one of these leaves to the light, and you will o'^serve that the veins run through it in all directions, forming; a sort of ne^-work. The leaves p.ce therefore net-veined. The points along the stem from which the leaves arise are called nodes, and the portions of stem between the nodes are called internodes. 6. Let us next examine the Plowers. Each flower in our plant is at the end either of the stem or of a branch of the stem. The upper portions of the :tem and its branches, upon which the flowers are raised, are called the peduncles of the flowers. Take now a flower which has just opened. Beginning at the outside, you will And five little spreading leaves, somewhat yellowish „. Fig. 4.— Radical leaf of Buttercup. Fig. 6.— Flower of Buttercup, from the baoiL f *! > I W f 6 ELEMENTS OF STRUCTURAL BOTANY. in colour. Each of these is called a sejJul, and the live together form the calyx of the flower. If you look at a flower which is a little older, you will probably not find any sepals. They will have fallen off*, and for this reason they are said to be deciduous. So, in like manner, le leaves of most of our trees are deciduous, because they fall at the approach of winter. You will find that you can pull off" the sepals one at a time, without dis- turbing those that remain. This shows that they are not connected together. They are therefore said to be freCj and the calyx is described as 2'>olysepalous. Inside the circle of sepals there is another circle of leaves, usually five in number, bright yellow in colour, and much larger than the sepals. Each of them is called a petal, and the five together form the COrolla of the flower. Observe carefully that each petal is not in- serted in front of a sepal, but in front of the space be- tween two sepals. The petals can be removed one at a time like the sepals. They, too, are free, and the cor- olla is polypetalnus. If you compare the petals with one another, you will see that they are, as nearly as possible, alike in rize and shape. The corolla is therefore regular. 6. We have now examined, minutely enough for our present purpose, the calyx and corolla. Though their divisions are not coloured green, like the ordinary leaves of the plant, still, from their general form, you will have no diflficulty in accepting the statement that the sepals and petals are in reality leaves. It will not be quite so apparent that the parts of the flower which still remain are also only modifications of the same structure. But there is good evidence that this is the case. Let us, however, cxaniine these parts that romain. There is EXAMINATION OP A BUTTERCUP. fir^t a large number of little yellow bodies, each at the top of a little thread-like stalk. Each of these bodies, with its stalk, is called a stamen. The little body itself is the anther, and the stalk is its filament. Your Fig. 6. magnifying glass will show you that each anther consists of two oblong sacs, united lengthwise, the filament being a continuation of the line of union (Fig. 7). If you look at a stamen of a flower which has been open some time, you will find that each anther-cell has split open along its outer edge, and has thus allowed a fine yellowish dust to escape from it (Fig. 8). This dust is called pollen. A powerful magnifier will show this pollen to consist of Fig. 7. Fig. 8. grains having a distinct form. As the stamens are many in number, and free from each other, they are said to be polyandrous. 7. On removing the stamens there is still left a little raised mass (Fig. 9), which, with the aid of your needle, you will be able to separate into a number of distinct pieces, all exactly alike, and looking something like unripe seeds. Fig. 10 shows one of them very much magnified, and cut through lengthwise. These little bodies, taken separately, are called carpels. Taken together, they form the pistil. They are hollow, and Fig. 10. each of them contains, as the figure shows, a Fig. 6. — Section of a flower of Buttercup. Fig. 7. - Stamen of Buttercup. • Fig. 8.— The same, showing longitudinal opening of the anther Fig. 9. — Head of carpels of Buttercup. Fig. 10. — A single carpel cut through lengthwise to show the ovuiCc Fig. 9. I'i fi 8 ELEMENTS OP STRUCTURAL BOTAJfY. Fig. 11. little grain-like substance attached to the loM^er end of its cavity. This substance, in its present condition, is the ovule^ and later on becomes the seed. You will notice that the carpel ends, at the top, Ir a little bent point, and that the convex edge is niore or less rough and moist, so that in flowers whose anthers have burst open, a quantity of pollen will be found sticking there. This rough upper part of the carpel is called the stigma. Fig. 1 1 shows a stigma greatly magnified. In many plants the stigma is raised on a stalk above the ovary. Such a stalk is called a style. In the Buttercup the style is so short as to be almost suppressed. When the style is entirely absent, the stigma is said to be sessile. The hollow part of the carpel is the ovary. \ In our plant the pistil is not connected in any way with the calyx, and is consequently said to be free or mperioTf and, as the carpels are not united together, the pistil is said to be apocarpous. 8. Remove now all the carpels, and there remains nothing but the swollen top of the peduncle. This swollen top is the receptacle of the flower. To it, in the case of the Butter- cup, all four parts, calyx, corolla, stamens, and pistil, are attached. When p flower has all four of these parts it is said to be complete. 9. Let us now return to our statement that Fig. 12. the structure of stamens and pistils is only a modification of leaf -structure generally. The stamen Fig. 11.— Stigma of Uutiercup with aiilierlug ix)l len -grains j highly magnified. Fijf. 12.— Diagram to sliow leaf-structure of a stamen. EXAMINATION OF A BUTTERCUP. 9 looks less like a leaf than any other part of the flower. Fig. 12 will, however, serve to show us the plan upon which the botanist considers a stamen to be formed. The anther corresponds to the leaf-blade, and the filament to the petiole. The two cells of the anther correspond to the two halves of the leaf, and the cells burst open along what answers to the margin of the leafc 10. In the case of apocarpous pistils, as that of the Buttercup, the botanist considers each carpel to be formed by a leaf-blade doubled lengthwise until the edges meet and unite, thus forming the ovary. Fig. 13 will make this clear. 11. There are many facts which support this theory as to the nature of the different parts of the flower. Suffice it to mention here, that in the white Water-Lily, in which there are several circles of sepals and petals, it is difficult to say where the sepals end and the petals begin, on account of the gradual change from one set to the oth( r. And not only Fig. 13. is there a gradual transition from sepals to petals, but there is likewise a similar transition from petals to stamens, some parts occurring which are neither altogether petals, nor altogether stamens, but a mixture of both, being imperfect petals with imperfect anthers at their summits. We can thus trace ordinary leaf-forms, by gradual changes, to stamens. We shall then distinguish the leaves of plants i ^ foliaye-leaves and jfoiver-leaveSj giving the latter name exclusively to the parts which make up the flower, and the former to the ordinary leaves which grow upon the stem and its branches. Fig. 13.— Diagram to illustrate the leaf-structure of the carpel. 10 ELEMENTS OF StlltJCttJllAL BOTANY. 12. You are now to try and procure a Buttercup whose ^lowers, or some of them, have withered away, leaving only the head of carpels on the receptacle. The carpels will have swollen considerably, and will now show themselves much more dis- Fig. 14. Fig. 15. tinctly than in the flower which we have been examining. This is owing to the growth of the ovules, which have now become seeds. Remove one of the carpels, and carefully cut it through the middle lengthwise. You will find that the seed almost entirely fills the cavity. (Figs. 14 and 15.) This seed consists mainly of a hard substance called albumen^ enclosed in a thin covering. At the lower end of the albumen is situated a very small body, which is the embryo. It is this which developes into a new plant when the seed f>k« W- germinates. 13. We have seen, then, that our plant consists of several parts : (1). The Root. This penetrates the soil, avoiding the light. It is nearly white, is made up of fibres, from which numbers of much finer fibres are given off", and is entirely destitute of buds and leaves. (2). The Stem. This grows upward, is coloured, bears fouage-leaves at intervals, gives off branches from the axils of these, and bears flowers at its upper end. (3). The Leaves. These p-re of two sorts : Foliage- leaves and Floicer-leaves. The former are sub-divided Fig. 14. — Ripe carpel of Buttercup. Fig. 15.— Section of same. Fig. 16. — Section of seed showing the small embryo. All much magnified. FUNCTIONS OF THE ORGANS OF lUB FLOWER. 11 into radical and cauline, and the latter make up the flower, the parts of which are four in number, viz.: calyx, corolla, stamens, and pistil. It is of great importance that you should make your- selves thoroughly familiar with thediflferent parts of the plant, as just described, before going further, and to that end it will be desirable for you to review the pre- sent chapter carefully, giving special attention to those parts which were not perfectly plain to you on your first reading. In the next chapter, we shall give a very brief account of the uses of the different parts of the flower. If found too difiicult, the study of it may be deferred until further progress has been made in plant-examination. CHAPTER IL FUNCTIONS OP THE ORGANS OP THE PLOWBIl. 14. The chief use of the calyx and corolla, or floral envelopes, as they are collectively called, is to protect the other parts of the flower. They enclose the stamens and pistil in the bud, and they usually wither away and dis- appear shortly after the anthers have shed their pollen, that is, as we shall presently see, as soon as their services as protdctors are uo longer required. 1.5. The corollas of flowers are usually bright-coloured, and frequently sweet-scented. There is little doubt that these qualities serve to attract insects, which, in search 12 ELEMENTS OP STRUCTURAL BOTANY. f of honey, visit blossom after blossom, and, l)ringing theii hairy limbs and bodies into contact with tlie open cells of the anthers, detach and carry away quantities of X)llen, some of which is sure to be rubbed off upon the stigmas of other flowers of the same kind, subsequently visited. 16. The essential part of the stamen is the anther, and the purpose of this organ is to produce the pollen, which, as you have already learned, consists of minute (jrainSf having a definite structure. These little grains are usually alike in plants of the same kind. They are furnished with two coats the inner one extremely thin, and the outer one mucl thicker by comparison. The interior of the pollen-grain is filled with liquid matter. When a pollen-grain falls upon the moist stigma it begins to grow in a curious manner (Fig. 17). The inner coat pushes its way through tho outer one, at some weak point in the latter, thus forming the beginning of a slender tube. This slowly penetrates the stigma, and then extends itself downwards through the Fig. 17. style, until it comes to the cavity of the ovary. The liquid contents of the pollen-grain are carried down through this tube, which remains closed at its lower end, and the body of the grain on the stigma withers away. The ovary contains an ovule, which is attached by one end to the wall of the ovary. The ovule con- sists of a kernel, called the nucleus^ which is usually surrounded by two coats, through both of which there is a minute opening to the Aucleus. This opening is called the micropyhf and is Fig 18. Fig. 17. — Pollen-grain developing a tube. Fig. 18 — Section of an ovule, ehowing central nucleus coats, and micropylc I i 14 J! FUNCTIONS OF THE 0U0AN8 OF THE FLOWER. 13 m )yU always to be found at that end of tlie ovule which is not attached to tlie ovary. (Fig. 18, ?;i.) About the time the anthers discharge their pollen, a little cavity, called the emhryo-sac^ appears inside the nucleus, near the micropyle. The pollen-tube, with its liquid contents, enters the ovary, passes through the micropyle, penetrates the nucleus, and attaches itself to the outer surface of the embryo-sac. Presently the tube becomes empty, and then withers away, and, in the mean- while, a minute body, which in time developes into the embryo, makes its appearance in the embryo-sac, and from that time the ovule may properly be called a seed. 17. In order that ovules may become seeds, it is always essential that they should be fertilized in the manner just described. If we prevent pollen from reaching the stigma — by destroying the stamens, for instance — the ovules simply shrivel up and come to nothing. Now it is the business of the flower to produce seed, and we have seen that the production of seed depends mainly upon the stamens and the pistil. These organs may consequently be called the essential organs of the flower. As the calyx and corolla do not play any direct part in the production of seed, but only protect the essential organs, and perhaps attract insects, we can under- stand how it is that they, as a rule, disappear earlv Their work is done when fertilization has been accom- plished. Having noticed thus briefly the part played by each set of floral organs, we shall now proceed to the exami- nation of two other plants, with a view to comparing their structure with that of the Buttercup. 1 14 KLEMENTS OF 8TRUCTUKAL BOTANY. CHAPTER TTI. ■ t! '\ EXAMINATION OF HEPATIC A AND MAHSII-MARIGOLD — RESEM BLANCES BETWEEN THEIR FLOWERS AND THAT OF BUTTERCUP. 18. Hepatica. You may procure specimens of the Hepatica almost anywhere in rich dry woods, but you will not lind it in flower except in spring and early summer. It is very desirable that yon should liave the Fig. 19. plant itself, but for those who are unable to obtain specimens, the annexed engravings may serve as a substitute Fig. 19.— Anemone Hepatica. HKPATICA. 15 Begiiiiiiiig, LlitMi, ut tlu^ root of our new plant, you seo that it does not differ in any great measure from that of the Buttercup. It may, in like manner, ho descrihed as Jihroiis. The next point is the stem. Yttu will rememher that in the Buttercup the stem is that pari of the plant from which the leaves spring. Examining our IIei)a- tica in the light of this fact, and following the petioles of the leaves down to their insertion, we find that they and the roots appear to spring from the same place — that there is, a{>parently, 710 stem. Plants of this kind are therefore callcnl acanlesrent, that is, stenilcus^ hut it must be carefully borne in mind that the absence of the stem is only apparent. In reality there i? a stem, but it is so short as to bo almost indistinguishab.e. The leaves of the Hepatica are, of course, all radical. They will also be found to be net-veined. 19. The Flowers of the Hepatica are all upon long peduncles, which, like the loaves, appear to spring from the root. Naked peduncles of this kind, rising from the ground or near it, are called scapes. The flower-stalks of the Tulip and the Dandelion furnish other familiar examples. Let us now proceed to examine the flower itself. Just beneath the coloured leaves there are three leaflets, which you will bo almost certain to regard, at first sight, as sepals, forming a calyx. It will not be difficult, however, to con- vin.jo you that this conclusion would be incorrect. If, with the aid of your needle, you turn back these leaflets, yo;.i will readily discover, between them and the coloured portion of the flower, a very short bit of stem (Fig. 20), the upper end of which is the receptacle. As these mtmum 16 ELEMENTS OF STRUCTURAL BOTANY. Fig. 20. leaflets, then, are on the peduncle, below the receptacle, they cannot be sepals. They are simply small foliage leaves, to which, us they are found beside the flower, the name bracts is given. Our flower, then, is apparently without a calyx, and in this re- spect is different from the Buttercup. The whole four parts of the flower not being present, it is said to be iitcomplete. 20. It may be explain-jd here that there is an under- standing among botanists, that if the calyx and corolla are not both present it is always the corolla which is \v anting, and so it happens that the coloured part of the flower under consideration, though resembling a corolla, must be regarded as a ;alyx, and the flower itself, therefore, as apetalous. 21. Removj now these coloured sepals, and what is left of the flower very much resembles what was left of our Buttercup, after the removal of the calyx and corolla. The stamens are very numerous, and are inserted on the receptacle. The carpels are also numer- ous (Fig. 21), are inserted on the recep- tacle, and are free from each other {apocarpous). . And if you examine one of the carpels (Fig. 22) you will find Fig. 2L Fig. 22. that it contains a single ovule. The flower, in short, so much resembles that of the Buttercup that you will be prepared to learn that the two belong to the same Order or Family of plants, and you will do well to observe and remember such resemblances as have just been brought to your notice, when you set out to examine plants tor your Fig. 20. -Flower of Ilepatica, with i)raf*ts oe.ow. Fig. 21.— Carpels of Hepatica. Fig. 22.— Single carpel, enlarged. MARSH-MARKJOLD. 17 selves, because it is only in this way, and by slow steps, that you can acquire a satisfactory knowledge of the reasons which lie at the fourdation of the classification of plants. 22. Marsh-Marigold. This plant grows in wet places almost everywhere, and is in flower in early summer. Note the entire absence of hairs on the surface of the plant. It is therefore glabrous. The root, like that of the Buttercup and of the He patica, is fibrous. The stem is hollow and furrowed. The foliage-leaves are of two kinds, as in the Butter- cup. The radical leaves spring from the base of the stem, whilst the higher ones are cauline. The leaves are not lobed, as in the other two plants, but are in- dented on the edge. They are also net-veined. 23. Coming to the flower (Fig. 23) we find a circle, or whorl, of bright yellow leaves, looking a good deal like the petals of the Buttercup, but you will look in vain for the corres- ponding sepals. In tiiis case there ■ is no whorl of bracts to mislead you. V Are we to say, then, that there is no calyx? If we adhere to the under- standing mentioned when des(jribinlu,,its. All the members of it, whilst they may differ in certain minor characteristics, agree in all the more important respects. The minor differences, such as we have observed in our examination of the specimens, lead to the sub-division of the group into several smaller groups, but any plant exhibiting the peculiarities common to all three ir.ay be regarded as typical of the Orchrr, which is the name given to the group as a whole. These common peculiarities may be summed up with sufficient accuracy for our present pur- pose, as follows : 1. The circles of Jloiver-leaves, that is to sat/, the sepals, petals, stamens, and car]>els, are entirely distinct, and unconnected with each other. 2. The several members of each circle are also entirely separate from each other. 6. It may he added that the stamens are almost invari- ably numerous, and that the jilants are acrid to the taste 22 ELEMENTS OF HTRUCTURAL BOTANY. CHAPTER IV. EXAMINATION OF OTHER COMMON PLANTS WITH HYPOGY NOUS STAMENS — SHEPIIERD's PURSE — ROUND- LEAVED MALLOW. 28. We shall now proceed to examine some plants, the flowers of which exhibit, in their structure, impor- tant variations from the Buttercup, Hepatica, and Marsh-Marigold. Shepherd's Purse. This plant (Fig. 26) is one of the commonest of weeds. As in the Buttercup, the foliage-leaves are of two kinds, radical and cauline, the former bei.ig in a cluster around the base of the stem. The cauline leaves are all sessile, and each of them, at its base, projects backward on each side of the stem, so that the leaf somewhat resembles the head of an arrow. Such leaves are, in fact, said to be sagittate^ or arrow- shaped. The flowers grow in a cluster at the top of the stem, and, as the season advances, the peduncle gradu- ally elongates, until, at the close of the summer, it forms perhaps half of the entire length of the stem. You will observe in this plant, that each separate flower is raised on a little stalk of its own. Each of these little stalks is a 2K'dicel^ and when pedicels are present, the term peduncle is applied to the por- tion of stem which supports the whole cluster. 29. Tlie flowers (Fig. 27) are rather small, Fiff 27 and so will require more than ordinary care in their examination. The calyx is polysepalous, and of Fig. 27. — Flower of Shepherd's Purse, enlarged. aHFPHERD.S rUUSiu 2? PUf. 26.— Shepherd's Purse. I I* m. 24 ELEMENTS OF HTKUCTUliAL HOTANY. four sepals. Tho corolla is polypotaloiis, and of four petals. The stamens (Fig, 28) are six in number, and if you examine tliem attentively, you will see that two of them are shorter than the other four The stamens areconsecjuently said to be tetradynamous. But if there had been only four atamens, in two sets of two each, they would have been called pjg, 28. did/piamouL The stamens are inserted on the receptacle (hypogynous). The pistil is separate frcm the other parts of the .flcwer (superior). 30. To examine the ovary, it will be better to select a ripening pistil from the lower part of the peduncle. It is a iiat body, shaped something like a heart (Fig. 29), and having the short style in the notch. A ridge divides it lengthwise on each side. Carefully cut or pull away the lobes, and this ridge will remain, pre- senting now the appearance of a narrow loop, with a very thin membranous parti- tion stretched across it. Around the edge, on both sides of the partition, seeds are suspended from blender stalks (Fig. 30). Fig. 29. Fig. 30. There are, then, two carpels united together y and the pistil is, therefore, syncarpous. 31. Shepherd's Purse is a type of a large and important Order, the Cnic\fera% or Cress Family. Other common examples, which should be studied and compared with Shepherd's Purse, are the garden Stock {single flowers are best for examination), Water-Cress, the yellow Mustard Fig. 28. — The same, with caiyx and corolla remo\ea. Fig. 29.— Ripened pistil of Shepherd's Purse. Fig. 30.— The same, with one side removed to show the •'eeds. ii shepherd's PURdE. 25 of the wheat-fields, Radish, Sweet Alyssum of the gardens, &e. All these phint.>^, while dillering in unimportant par- ticulars, such as the colour and size of the petals and the shape of the pod, agree in presenting the following char- acters : 1. The sepals and petals are each four in number. 2. Tlie stamens are tetrad ynamous (and hypogynous). 3. The fruit is syncar/)ous, and is 2'Celled by reason of a thin partltio7i stretched between the carpels. 4. It may be added that the jdants are generally pungent to the taste^ and the flowers are almost invariably in terminal clusters, like that of Shepherd^ s Purse. SHEPHERD'S PURSE. Okgan. No. Cohesion. Polysepalous. Adhesion. Remarks. Calyx. Sepals. 4 4 Inferior. Corolla. Petals. Polypetaloiis. Hypogynous. Stamens. Filaments. Anthers. 6 2 Tetradyua- mous. Hypogynous. Two sepals with a pair of long stamens opposite each ; the other two with one short stamen opp. each. Pistil. Carpels. Ovary. Syncarpous. Superior. The two cells of the ovary separated by a thin partition. 26 ELEMENT8 OF STRUCTURAL BOTANY. 32. Mallow. Tho round-leaved Mallow (Fig. 31) grows along every wayside, and is a very common weed in cultivat- ed grounds. Pro- cure, if possible, a plant which has ripened its seeds, as well as one in flower. The root Fig. 33. of this plant is of of adifferentkind from those of the three plants first examined. It consists of a stout tapering part, de- scending deep in- Fiy. 34. Fig. 31. to the soil, from the surface of which fibres are given off irregularly. A stout root of this kind is called a tap-root. The carrot is another example. 33. The leaves are long-petioled, net-veined, and in^ dented on the edges. On each side of the petiole, at its junction with the stem, you will observe a little leaf-like attachment, to which the name stipule is given. The presence or absence of stipules is a point of some import- ance in plant-structure, and you will do well to notice it in your examinations. You have now made yourselves Fig. 31.— Round -leaved Mallow. Fig. 32. — Section of the flower. Fig. 33.— Flower with calyx and corolla removed. Fig. 34.— A ripened pistil with the persistent calyx. RODND-I.EAVED MALLOW. 27 acquainted with all the parts that any leaf has, viz., blade, petiole, and stipules. 34. Coming to the flower, observe first that the parts of the calyx are not entirely separate, as in the flowers you have already examined. For about half their length they are united together so as to form a cup. The upper half of each sopal, however, is perfectly distinct, and forms a looth of the calyx ; and the fact that there are five of these teeth shows us unmistakably that the calyx is made up of five sepals. We therefore speak of it as a (ja)iiosepalous calyx, to indicate that the parts of it are coherent. As the calyx does not fall away when the other parts of the flower disappear, it is said to be persistent. Fig. 31, rt, shows a persistent calyx. 35. At the base of the calyx there are three minute leaf-like teeth, looking almost like an outer calyx. A circle of bracts of this kind is called an involucre. The three bracts under tlie flower of the Hepatica also consti- tute an involucre. As the bracts in the Mallow grow on the calyx, some botanists sjDeak of them as an epicalyx. The corolla consists of five petals, separate from each other, but united with the stamens at their base. 36. The stamens are numerous, and as their filaments are united to form a tube, they are said to be monadelpkom. This tube springs from the receptacle, and the stamens u^e therefore hijporiynous. Fig. 32 will help you to an under- standing of the relation between the petals and stamons. Having removed the petals, split the tube of the stamens with the point of your needle. A little care will then enable you to remove t'\e stamens without injuring the : I i ' [I ; I 28 ELEMENTS OF STRUCTURAL BOTANY. pistil. The latter organ will then be found to consist of a ring of C(jherL'nt carpels, a rather stout style, and num- erous long stigmas (Fig. 33). If you take the trouble to count the carpels and the stigmas, you will find the num- bers to correspond. As the seeds ripen, the carpels separate from each other (Fig. 34). MALLOW. Okgan. No. Cohesion. Adesion. Remarks. Calyx. Sc2>als. 5 Gamosepa- lous. Inferior. Hypo{,'ynons. Three bracts f,'rowingonthe calyx. Corolla. rctals. 5 CO cc Polypetalous. Stamens. Filaments Anthers. Mouadelphous One-celled, Syucarpous. Hypogynous. Pistil. Carpels. Ovarii. Superior. Carpels as many as the stigmas. 37. Compare now the structure of the Hollyhock (single "lowers should be selected) with that of the Mallow, and write out a description. Musk-Mallow and Abutilon (a common green-house plant) may also be examined with advantage. 38. The Order (Malvacea) of which Mallow is a type is very distinctly marked by the following characteristics : 1. The sepals are always placed edge to edge (valvate) in the hud^ while the petals overlap) and are rolled together (convolute). 2. The stamens are numerous and 7nonadeJphous, and their anthers are 1 -celled. Although united at the ii ' GARDEN PEA. 39 hose with the claws of the ])etal8y they are neverthe- less inserted on the receptacle {hypngynous). 3. Tlie carpels are almost alirays united in • ig^ ichich breaks up at maturity. Jf. It may he added that the leaves are furnished with stijndes, and the juice of the jylants is mucilaginous. Fijr. 36, CHAPTER V. EXAMINATION OF COMMON PLANTS WITH PERIGYNOUS STAMENS — GARDEN PEA — GREAT WILLOW-HERB. 39. Garden Pea. In the flower of this plant, the ealyx is constructed on the same phin as in the Mallow. There are five sepals, coherent below, and spreading out into distinct teeth above (Fig. 35). The calyx is there- fore gamosepalous. Examine next the form of the corolla (Fig. 36). One dilTerenco between the corolla and those of the previous plants will strike you at once. In the flowers of the latter you will remember that each petal was precisely Fig. 38 Fig. 37. like its fellows in size and shape, and we therefore spoke of the corolla as regidar. In the Pea, on the other hand, Fig. 35.— Flower of Garden Pea. Fig, 36.— Front view of the same. Fig. 37. — Diadulphous stamens of the same. Fig. 38. —The pistil. Fig. 39.— The same cut through lengthwise. I ; I mm 30 ELEMENTS OF STRUCTURAL BOTANY. I || li one of the petals is large, broad, and open, whilst two smaller ones, in the front of the flower, are united into a kind of hood. We shall speak of this corolla, then, and all others in which the petals are unlike each other in size or shape, as irregular. ^■ As the Pea blossom bears some resemblance to a butter- fly, it is said to be papilionaceous. 40. Remove now the calyx-teeth and the petals, being very careful not to injure the stamens and the pistil, en- veloped by those two which form the hood. Count the stamens, and notice their form (Fig. 37). You will find ten, one by itself, and the other nine with the lower halves of their filaments joined together, or coherent. When stamens occur in this way, in two distinct groups, they are said to be diadelplums ; if in three groups, they would be triadelphous ; if in several groups, ^5r>///a(7eZ2>'/i0W6\ In iLe Mallow, you will remember, they are united into one group, and therefore we described them as monadelphous. You will, perhaps, be a little puzzled in trying to determine to what part of tlie flower the stamens are attached. If you look closely, however, you will see that the attachment, or insertion^ is not quite the same as in the Buttercup and the oilier flowers exaniined. in the present instance they are inserted upon the lower part of the calyx, and so tliey are described as ])erigynous, a term meaning " around the pistil." 41. But the pistil (Figs'. 38, 39) is not attached to the calyx. It is frec^ or supBiior. If you cut the ovary across, you will oljserve there is but one cell, and if you examine the stigma, you will iind that it shows no sign of division. You may therefore be certain that the pistil is a single larpel. !• ; GARDEN TEA. 31 You are now prepared to fill up the schedule descrip- tive of this flower. GAEDEN PEA. ORGAN. NO. COUKSION. j ADHESION. I REMARKS. Calyx. Sepals. 0 Gamosepalous Inferior. Corolla. Petals. 5 Papilioua(!e- ous. Irregular. Perigynous. The two front petals united. Stamens. Filaments. Anthers. 10 Diadelphous. Perigyuous. Pistil. Carpels. Ovary. 1 Apocai-pous. Superior. 42. The beginner will be very likely to think, from its aippearance, that the largest of tlie petals is made up of two coherent ones, but the following considerations show clearly that this is not the case. In the Buttercup, and other flowers in wh''jh the number of sepals and petals is the same, the petals do not stand before the sepals, but before the spaces between them. In the Pea-blossom this rule holds good if the large petal is considered as one, but not otherwise. Again, tiio veining of tliis petal is similar to that of a connuon leaf, there being a central rib from which the veins spring on each side ; and lastly, there are some flowers of the Pea kind — Cassia, for example — in which this particular petal is of nearly the same size and shape as the other four. V6. The Pea is a type of a highly important group of plants — the Order Letjuiniuodcc, To it belong many plants I A Tf ELEMENTS OP STRUCTURAL BOTANY. differing very widely in externul appearance — the Locust- Tree and the Clover, for example — but exhibiting in the structure of their flowers so marked a similarity that their relationship is beyond question. The characters by which the Order is distinguished are chiefly these : 1. The corolla is more or less papilionaceous, and is inserted on the base of the calyx {periyyrious). 2. The stamens, almost invariably tan in number, are also perigynous, and nearly alioays diadelphous. 3. The pistil is nearly always a legume, that is to say, it is a single carpel which splits into two pieces at maturity, like the pod of the Pea or Bean. 4» The leaves have stipules, and are nearly always com- pound, that is, of several distinct leaflets. Plants wliich may be compared with the Pea are Red Clover, White Clover, Sweet Clover, Medick, Locust-Tree, Bean, Yetch, Lupine, Sweet Pea, &c. 44. Great Willow-herb. This plant is extremely common in low grounds and newly-cleared land, and you may easily recognize it by its tall stem /'^^" and bright purple flowers. Observe the position of the flowers. In the three plants flrst examined we found the flowers at the end of the stem. In the Willow-herb, as in the Mallow, they spring from the sides of the stem, and immediately below the point from which each flower fijt. 40. springs you will And a small leaf or br^ct (Fig. 40). Flowers Fi(r. 40.— Flower of Great Willow-herb. GREAT WILLOW-HERB. 33 which arise from the axils of bracts are ^?.iCc go be axillary^ whilst tliose which are at the ends of stems are called terminal, and you may remember that flowers can only be produced in the axils of leaves and at the ends of stems and brandies. 45. Coming to the flower itself, direct your attention, lirst of all, to the position of the ovary. You will find it apparently under the flower, in the form of a tube tinged with purple. It is not in reality under the flower, because its purplish covering is the calyx, or, more accurately, the cali/x-tuhe, which adheres to the whole surface of the ovary, and expands above into four long teeth. The ovary, therefore, is inferior^ and the calyx, of course, superior^ in this flower. As the sepals unite below to form the tube the calyx is gamosepalous. The corolla consist's of four petals, free from each other, and is consequently polypetalous. It is also regular, the petals being alike in size and V shape. Each petal is narrowed Pij, 42, I ,f /^^^ ' 'it the base into what is called the daw of the petal, the broad {^iPii HS/tiM \}^ii, as in the ordinary foliage- leaf, being the blade. The stamens are eight in number (octandrous), four short and A Jr ^^<*'ii' h)ng, and are attached to \^^^^ the calyx (porigynous). 46. The pistil has its three Fi{,', 41. parts — ovary, style,and stigma — very distinctly marked. The stigma consists of four long lobes, which curl outwards after the flower opens. The Flj(. 41.— Ripened pistil of Willow-herb. Fig. 42.— CroM sectiofl o/ the same. 34 ELEMENTS OF STRUCTURAI BOTANY. i ; ' 1 style is long and slcMider. The examination of the ovary requires much care; ; you will get the best idea of its structure by taking one wliich has just burst open and begun to discharge its seeds (Fig. 41). The outside will then be seen to consist of four pieces (valves)^ whilst the centre is occupied by a slender four-winged column (Fig. 42), in the grooves of which the seeds are compactly arranged. The pistil thus consists of four carpels united together, and is therefore ' syncarpous. Every seed is furnished with a tuft of silky hairs, which greatly facili- tates its transportation by the wind. 47. The Willow-herb furnishes an excellent example of what is called 8ymi)ietrij. We have seen that the calyx and corolla are each made up of four parts ; the stamens are in two sets of four each ; the stigma is four-lobed, and the ovary has four seed-cells. A flower is symmetrical when each set of floral leaves contains either the same number of parts or a multiple of the same number. Observe that the leaves of our plant are n^ -veined. The schedule will be filled up as follows : GREAT WILLOW-HERB. ORGAN. NO. COHESION. ADHESION. BEMARKS. Calyx. Sepals. •1 Gainosepalous Polypetalous. Superior. Perigyuous. Perigyuous. Corolla. retells. •1 Stamens. Filaments. Anthtrs. 8 Octaudrous. Syncarpous, Four short and four long. Pistil. Carpels. Ovanj. 4 luferior. Seeds provided \Mth tufts of hair. ROSACEOUS PLANTS. 35 Flowers to compare with Groat Willow-herb are Fuchsia and Evening Primrose. Either of these will serve as the type if Willow-herb cannot be obtained. CHAPTER YI. EXAMINATION OF COMMON ROSACEOUS PLANTS — SWEET BRIER STRAWBERRY CHERRY CRAB-APPLE RAHPBERRY. 48. Sweet Brier. Fig. 43. As in the flowers examined in the last chapter, the sepals of Sweet Brier are not en- tirely distinct. ; their lower halves cohere to form a tube, and the calyx is therefore gamo- sepalous. Thg corolla con- sists of five sepa- rate petals of the same size and shape, and is there- fore both regular and poly}X3talous. Tlie stamens are very numerous, and separate from each other. As in the Poa and tlie Willow-lierb, so in tliis flow(T they will be Fig. 43.— Flower and leaves of Sweet Brier. 36 ELEMENTS OF STRUCTURAL BOTANY. M found to be attached to the calyx. They are, therefore^ perigynous. 49. To understand the construction of the pistil, you must make a vertical section through the roundish green mass which you will find on the under side of the flower. You will then have presented to you some such appearance as that in Fig. 44. The green mass, you will observe, is hollow. Its outer covering is simply the continua- tion of the calyx-tube. The lin- ing of this calyx-tube is the recep- ^'^- ^*- tacle of the floiver ; to it are at- tached the separate carpels which together constitute the pistil (Fig. 45), just as the carpels of the Buttercup are attj.ched to the raised receptacle of that flower. We must remind you again that whenever the ovary is enclosed in the calyx-tube, and the calyx appears to spring from the summit of the ovary, the latter is said to be inferior J and the former superior. In the case of Sweet Brier or»d similar forms, where the pistil is strictly apocarpous, and the other parts cohere at their base so as to form a tube enclosing the really free carpels, the pistil may be described as half -inferior^ and fik. 45. the calyx consequently as half-superior. 50. Strawberry. So far as calyx, corolla, and sta- mens are concerned, the flower of Strawberry very nearly resembles that of Sweet Brier. Alternating with the five calyx-lobes, however, will be found five bractlets, Fig. 44.— Vertical section throug^h the pistil. Fig. 46.— Vertical section through ripe fruit of Sweet Brier. ROSACEOUS PLANTS. '61 Fig. 46. which constitute, as in Mallow, an epicalyx. The pistil must be carefully examined. In this case there will be found a conical elevation in the centre of the flower, on the surface of which are inserted many separate carpels, much in the same way as in Buttercup. At maturity this elevated receptacle will have become greatly enlarged and pulpy, with the real fruit, the ripened carpels, dotted over its surface (Fig. 46). 51. Cherry or Plum. Here also the calyx, corolla, ind stamens are all adherent, and a hollow cup is formed, in the bottom of which (but entirely free from these parts) the pistil is developed (Fig. 47). It consists of a single carpel, in which there are at first two ovules, though gen- erally but one seed is ripened. The fruit is called a drupe, the seed being surrounded by three distinct layers: (1) a hard shell (the putamen), (2) a mass of soft pulp, and (3) the outer skin. 52. Crab- Apple. Here, as before, we have a gamo- sepalous calyx, the Jower part forming a tube. The five petals are separate and inserted on the calyx, as are also the numerous stamens. To understand the structure of the oistil, make a vertical section through the centre of the flower, and also a cross section. The cross section Fig. 46.— Vertical section of Strawberry. Fig. 47.— Vertical section through flower of Cherry. (Qray.) Fig. 47. f? I BIB 1 88 ELEMENTS OF STRUCTURAL BOTANY. (Fig. 50) will show you that in this case wo have a syncarpous pistil of five carpels, and the vortical section (Fig. 49) shows that the ovary is here truly inferior^ the calyx-tube be- ing completely adherent or adnate to it. The style is divided into five parts, cor- responding to the five car- Fig. 48. ' Flj?. 49. P®^^' 53. At maturity, wh'lst the pistil or central organ has enlarged considerably, it will be found that the calyx- tub0, which is adherent to it, has also grown very much. It is, in fact, the largely developed calyx-tube which con- stitutes the edible part of the apple, the true pistil forming the core. It is not very easy to distin- guish the line which separates these two parts of the ripe fruit, but if a ■cross- section be made through the apple a circle of greenish dots may generally be made out at the outer limit of the core. A fruit of this sort is called a pome. The witlier- ed calyx-teeth may be found in the hollow ^^=' ^^• at the end opposite the stem, as also, generally, the remains of the five styles. Fig. 48.— Flower of Crab-Apple. Fig 49.— Vertical section of ovaiy. Fig. 50. — Gross section of fruit of Crab- Apple. nOSACEOUS PLANTS. oy car- \ 54. Raspberry. Calyx, corolla, and stamens have the same arrangemert as in Strawhorry, and the pistil is likewise apocarpoiU'i, tlie numerous carpels coveriufi the surface of a raised receptacle. But here the carpels do not produce achenes. Each of them at maturity forms a fruit resembling a drupe, so that the raspberry is a mass of ilnipes heaped upon a common receptacle. 55. Let \\% now sum up our observations upon the repre- sentatives of the great Order of Rosaceous plants. We have found them to possess the following characters in common: 1. Tlie petah and the numerous stamens are inserted on the calyx (jierigi/notis). 2. Tlie pistil, except in the Apple, is apocarpous and free from the ealijx. S. It may he added that the leaves are furnished with stijmles. 56. The differences (which lead to the sub-division of the Order into subordinate groups) are chiefly in the fruit. In Sweet Brier, with which may be compared any wild Rose, the achenes are enclosed in the calyx-tube. In Straw- berry the receptacle is conical ; so also in Raspberry. In the Cherry the carpel is single, formiug a drupe. In the Apple the ovary is syncarpous and combined with the fleshy calyx. Compai witli the Apple the Hawthorn and the Mountain Ash or Rowan Tree. 57. The following are the schedules descriptive of oweet Brier and Crab-Apple. Those relating to Cherry, Strawberry, and Raspberiy should be carefully filled up by the pupil. • *0 ELEMENTS OF STRUCTURAL BOTANY. SWEET BRIER. Okgan. No. Cohesion. Gumosepalous Adhesion. Remarks. Calyx. Sepals. ,5 .5 00 00 Half-superior, Corolla. Petals. Polypetalous. Perigynous. Stamens. Polyandrous. Perigynous. Pistil. Carpels. Apocarpous. Half-inferior. Che hollow re- ceptacle lines the calyx-tube CRAB-APPLE. Organ. No. Cohesion. Adhesion. Remarks. Calyx. Sepals. 5 5 00 Gamosepa- l')us. Superior. Corolla. Petals. Polypetalous, Perigynous. Stamens. Polyandrous. Syncarpoua. Perigynous. Pistil. Carpels. 1 5 ) Inferior. Fruit consists chiefly of a fleshy enlarge- ment of the calyx-tube. I EXAMINATION OP AN UyUELLIPER. 41 CHAPTER VII. EXAMINATION O'; A PLANT WITH EPIGYNOUS STAMENS — WATER-PARSNIP. 58. Water-Parsnip. This is a common swamp plant in Canada ; but if any difficulty be experienced in procuring specimens, tlie flower of tlie common Carrot or Parsnip or of Parsley may be substituted for it, all tlieso plants being closely related, and dif- fering but slightly in the structure of their flowers. ^Notice first the peculiar appearance of the flower cluster (Fig. 51 ). There ^^ .. ^ areseveral pedicels,nearly of thesame fl \j^ length, radiating from the end of the peduncle, and from the end of each pedicel radiate in like manner a num- ber of smaller ones, each with a flower at its extremity. Such a cluster is known as an iwibel. If, as in the present case, there are groups of secondary pedicels, the umbel is compound. As the flowers are very small wo shall be obliged to use the lens all through the examination. Even with its aid you will have a little difficulty in making out the calyx, the tube of which, in this flower, ailheres to the surface of the ovary, as m Willow-herb, and is reduced above to a mere rim or border of live minute teeth. The petals are five in number, and free from each other. Observe that ea(;h of them is incurved at its extremity Fig. 52. Fig. 51. 1 Fig. 51.— Compound umbel of Water-Parsnip. Fig. 62.— Single flower of same. Fig. 53.— Vertical section of the ovaiy. r 42 ELEMENTS OF STIiUCTURAL BOTANY. t I ^' .1 i 'Fig. 52). Thoy aro inserted on a di-^k which crowns the ovar?jy as are also the five stamens, which are hence said to be epigynous. In tlie centre of tlie llower are two short styles projecting above tlie disk, and a vertical section through the ovary (Fig. 53) shows it to be two-celled, with a single seed suspended from the top of each cell. WATER PARSNIP. ORGAN. NO. COHESION. ADHESION. UEMARKS. Calyx. Sepals. 5 Gamosepalous Superior. Calyx-teeth al- most o])Holete. i Corolla. Petals. 5 Polysepalous. • Epigyuous. Petals in- curved. Stamens. 5 Pentandroiis. Epigynous. Pistil. Carpels. Syucarpous. luferior. 1 59. The Water-Parsnip is a type of the large Order UmhelUfercei wl.ich is well marked by the following characters : 1. The flowers are clustered in umbels, and these are generally comj^ound. 2. Tlie calyx is iierfecthj adherent to the ovary, so that almost none of it 2>roj 'ids above. 3. The petals and staniensi^jlue each) are epigynous. J^. The ovary is two-cdled, and is surmounted by two styles. At maturity the pistil separates into two dry carpels. A COMPOSITE FLOWER. 43 \ CHAPTKK VIIT. Fig. 54. are all radical. EXAMINATION OF COMMON PLANTS WITH KPIPETALOUS STA- MENS— DANDKIJON — CATNIP. 60. Dandelion. The cxainination of this flower will he somewliat more diflicult than that of any we have yet undertaken. Provide yourselves with specimens in flower and in seed. The root of the plant, like that of the Mallow, is a tai)-root. The stem is almost suppressed, and, as in the case of the Hepatica, the leaves They are also ndt-veined. The flowers are raised on scapes, which are hollow. At first sight the flower appears to have a calyx of many •lopals, and a corolla of many |)etals. Both of thcsa ap- pearances, however, are contrary to facts. With a sharp knife cut the flower through the middle from top to bottom (Fig. 54). It will then appear that the flower, or rather floicer-head^ is made up of a large; number of distinct pieces. With the point of your needle detach one of these pieces. At the lower end of it you have a small body resembling nn unripe seed (Fig. 55). It is, in fac^i, an ovary. Just above this there is a short bit of stalk, sur- mounted by a circle of silky hairs, and above this a yellow tube with one side greatly prolonged. This yellow tube is a corolla, and a close examination of the extremity of Fig. 55. Fig. M. — Vertical section of Dandelion flower. Fig. 55— Single floret. 44 ELEMENTS OF STRUCTURAL BOTANY. its long side will show the existence of five minute points, or teeth, from which we infer that the tube is made up of five coherent petals. As the corolla is on the ovary, it is said to be Epigynous. Out of the corolla ])rotrudes the long style, divided at its summit into two stigmas. To discern the stamens will require the greatest nicety of observation. Fig. 56 will help you in your task. The stamens are five in number. They are inserted on the tube of the corolla (epipetalous) and Fig. 56. their anthers cohere (Fig. 57), and form a ring about the style. When the anthers are united in this way, the stamens are said to be syngenesious. 61. It appears, then, that the Dandelion, instead of being a single flower, is in reality a compound of a great many llowers upon a common receptacle, and what seemed at first to be a calyx is, in reality, an involucre, made up of many i^'iy.&T. bracts. But h^ve the single flowers, or JloretSj as they are properly called, no calyx? The theory is that they have one, bu^ that it is adherent to the surface of the ovary, and that the tuft of silky hairs which we noticed is a prolongation of it. Fig. 58. Now turn to your specimen having the seeds ready to blow away. The seeds are all single ; the little bit of stalk at the top has grown into a long slender thread, and the tuft of hairs has spread out like the rays of an umbrella (Fig. 58). But though the seeds are Fig. 56.— Corolla laid open to show epipetalous stamens, ['"ig. 57.— Syngenesious anthers of Dandelion. Fig. 58.— Fruit of Dandelion. i A COMPOSITE FLOWER. 45 invariably single, it is inferred from the two-lobed stigma that there are two carpels. The following is the schedule: DANDELION. ORGAN. No. Cohesion. Adhesion. Eemarks. Calyx. Sepals. 5 Gamosepalous Superior. The number of sepals is in- fcrreil from analogy to be five. Corolla. Petals. 6 Gamopptfilons Epigynous, Stamens. 5 Syngeiips Ons. l^l)i|)etHlous. Pistil. Carpels. 2 Syncarpous. Inferior. Number of carpels in er- red from r um- ber of sti^'niaa. 62. Flowers constructed on the plan of the Dandelion are called Composite flowers. The Order (Compositie) comprises an immense number of common plants, in some of which all the corollas in the head are, as in the Dandelion, of one sort, namely, with one side prolonged into a strap, and hence called strap-shaped or ligalate. In most cases, however, the ligulate corollas form a circle round the margin of the liead only, as in Sunflower, while the central ^//^7t* is filled up with small regular gamopetalous corollas with a five-toothed border. Or it may happen, as in Thistle, that all the flowers are ref^u- lar, ligulate corollas being absent. These, liowever, are minor points, and, while serving to distinguish suboi-- dinate groups, do not interfere with the great and .-alient characters which mark the Ord«='Y as t, whole. 8o, also, J 46 ELEMENTS OF STRUCTURAL BOTANY. instead of the tuft of silky hairs (technically called the pappus) which surmounts the ovary, there may be, as in Sunflower, p few teeth-like projections, or scales, or a mere rim hardly to be distinguished at all. 63. The Order is easily recognized by the following characters : 1. Theflotvers, or floret)^, are in heads on a common re- ceptacle^ and surrounded hy an involucre. 2. The stamens are inserted on the corolla, and are united hy their anthers {synyenesiouf^J. 3. The style is 3-lohed at the aj^ex. 64. Representatives of this Family are so nunerous that it is needless to give a list. Specimens exhibiting all the variations in regard to the corollas, pappus, ^c, should be gathered and notes made of their structure. In Part IT. will be found a very full account of all the species likely to be met with, and the exercise book has a number of blank schedules specially arranged for Com- posites. 65. Catnip. Note carefully the appearance of the stem. It is square. The flowers are in axillary clusters. The calyx is a tube (Fig. 59), terminating in live sharp teeth, and you may observe that the tube is a little longer on the upper side (that is, the side tc*nards the stem) than on the lower. The corolla is somewhat peculiar. It has somewhat the appearance of a wide-open mouth, and is known as a labiate or two-lipped Fig. 59. corolla. The upper lip is erect and notched at the apex. Fig. 59.— Flower of Catnip, if ■•a A LABIATE FLOWER 47 the pex. 1 a ■ 1 ■; < The lower lip spreads outward, and consists of a large central lobe and two small lateral ones. Altogether, therefore, there are five lobes constituting the gamopetal- ous corolla. Pull out the corolla, and with the point of your needle split its tube in front. On laying it open, the stamens will be found to be inserted upon it (epipet- alous). They are four in number, two of them longer than the other two. Hence they are described as didijnamous. The anthers are peculiar in not having their lobes parallel (Fig. 60), these being wide apart at the base, in con- sequence of the expansion of the cunriective., the Fig. CO. name given to that part of the anther which unites its two lobes or cells. The pistil consists of a two-lobed stigma, a long style, and an ovary which seems at first as if made up of four distinct carpels (Fig. 61). But the two-lobed stigma will warn you against this supposition. The ovary really consists of tiro carpels, each of two deep lobes, and, as the seeds ripen, these Fig. 62. lobes form four little nutlets (Fig. 62), each containing a single seed. 66. The Catnip is a type of the Order Lahiatm (Mint Family), so called because the corollas are usually labiate. It is marked by the following characters : 1. 21ie stem is square^ and the leaves are opposite and (jenerally aromatic. 2. The corolla is more or less labiate. 3. The stamens are .nosthj didijn^imous. Fig. 60.— Front view of the same. Fig. 61.— Pistil of Catnip; Fig. 62.— Kipe ovary of four separate nutlets. "%,. Fig. Gl. I : ' ^ w^ i I .; It ^ i -I- ii ■ \ 1 ■ 1 ,|i 1 ■ I; 48 ELEMENTS OF STRUCTURAL BOTANY. 4. y^e ovary is four-lobed^ and at maturity breaks up into four nutlets. Other types are the various Mints, Sage, Thyme, ^Summer Savory, Pennyroyal, Bergaraot, Sel*-heal, Horehound, &c., many of which are of very common occurrence. CATNIP. Organ. No. Cohesion. Adhesion. Remarks. Calyx. Sepals. 5 Gamosepalous Inferior. Calyx- tube nerved. Corolla. Petals. 5 Gamopetalous Hypogynous. Two-lipped. Upper lip of two, and lower of three, lobes. Stamens. A nthers. 4 2 Didynamous. Epipetalous. Lobes of an- thers not par- allel. Pistil. Carpels. Syucarpous. Superior. The ripe ovary of four nutlets. CHAPTER IX. EXAMINATION OF PLANTS WITH MONCECIOUS FLOWERS — CUCUMBER — OAK. 67. Cucumber. You can hardly have failed to notice that only a small proportion of the blossoms on a Cuoumber vine produce cucumbers. A great many MONCECIOUS FLOWERS. 49 Itp Fis-. 63. wither away and are apparently of no use. An atten- tive inspection will show that some of hhe blossoms have oblong fleshy protuber- ances beneath them, whilst others are destitute of these attachments. Select a flower of each kind, and examine lirst the one with the protuberan'^e (Fig. 03), which latter, from its appearance, you will pro- bably have rightly giiessed to be the ovary. The situation of the ovary here, indeed, is the same as in the Willow-herb. The calyx-tube adheres to its surface, and is prolonged to some little distance above it, expanding Anally into five teeth. The corolla is gamopetalous, and is adherent to the calyx. Remove now the calyx and the adherent corolla, and there is left in the centre of the flower a short column, terminating in three stigmas, each two. lobed. TJtere are no stamens, 68. Now examine the other blossom (Fig. 6-1). Calyx y^ and corolla have almost exactly '/;■' j the same appearance as before. Remove them, and you have left three stamens growing on the calyx-tube, and slightly united by their anthers (syngenesious). Pig. 64. There is 7io pistil. I li i (■ I Fifr. 63.— Pistillnto flower of Cucumber. Fi^. 64.— Staminate flower of Cucumber. i> ^.i^^i^tlimnemh'' 50 ELEMENTS OP STRUCTURAL BOTANY. You see now why some blossoms produce cucumbers and others do not. Most of tlie blossoms have no pistil, and are termed staminate or fsfenle flowers, whilst the others are 'piMillate or fertih. Flowers in which either stamens or pistils are wanting are also called imperfect. When staminate and pistillate flowers grow on the same plant, as they do in the case of the Cucumber, they are said to be monmcious. 69. In plants of this kind the pollen of one kind of blossom is conveyed lo the stigmas of tiie other kind, chiefly by insects, which visit the flowers indiscrimin- ately in search of honey. The pollen dust clings to their hairy legs and bodies, and is prese itly rubbed ofi' upon the stigma of some fertile flower. 70. In order to describe monoecious flowers, our schedule will require a slight modification. As given below, the symbol ^ stands for "staminate flower," and the symbol ^ for "pistillate flower." CUCUMBER. Organ. Calyx. Sepals. Corolla. Petals. No. 5 Cohesion. Adhesion. Remarks. Gamosepalous Superior. 5 3 o GramopetalouH Perigynoiis. > Stamens. Syiigenesious. Perigyuous. Two anthers are2-celledand one 1-celled. t Pistil. Caipels. 9 Staineus. $ Pistil. Carpels. ! :5 Syiicarpous. Inferior. CUPULIFEROUS PLANTS. 51 our }> 71. Oak. Tlie Oaks are among our finest and most valuable forest-trees, and while everyone is familiar with Fig. 67. Fir . 65. the appearance of the acorji, as the fruit of the Oak is Fig. 6G.— Twig of White Oak with sterilo catkins. Fig. 67.— Single staminate flower. Fig. ea— Fruit and leaf of Oak. (Woocl and Steele.) \1> I I I# 62 ELEMENTS OP STRUCTURAL BOTANY. called, the fact that the flowers are not to be obtained without eff'ort on account of their distance from the ground, as well as the circumstance of their being rather incon- spicuous, may lead to their being overlooked unless special attention is directed to them. The White Oak is perhaps the best known species with us. It may be pretty well distinguished from other species by its leaves, the lobes of which (Fig. 6-) are rounded. However, for the purposes of this lesson, any other species may be used, if the White Oak is not at hand. The flowers are monoecious, the sterile ones forming long and slender drooping catkins, which are either single or, more generally, several in a cluster, from the same lateral bud (Fig. QQ). Each sterile flower (Fig. 67) consists of a perianth or calyx of a vari- able number of sepals, mostly from four to six, .and gen- erally eight stamens. The fertile flowers spring mostly from the axils of the leaves of new shoots, and they occar either singly or two or three in a cluster. Each flower consists of a syncarpous pistil of three carpels. The ovary is three-celled, or nearly so, and two ovules are formed in each cell. The flower is surrounded at the base by a scaly involucre, which, at maturity, has become quite woody, and forms in fact the cup in which the acorn rests. If you dissect an acorn you will observe that there is hut one seed in it. Although the ovary contains six ovules at starting, it always happens that all but one disappear before the fruit is matured. • The White Oak ripens its acorns the first year. The Red Oak, on the other hand, does not ripen its fruit till the autumn of the second year. 72. It will be a valuable exercise to compare flowers of the Beech with those just described. They will be found OTJPULIFEROUS PLANTS. 63 to be monoecious also ; the sterile ones in small drooping heads, with stamens and sepals variable in number, and the fertile ones from the axils of new leaves, usually two together, surrounded by an involucre of many bristle- pointed scales. These dev^elope into the familiar bristly four-valved involucre which encloses tlie pair of three- cornered nuts at maturity. Each nut is the product of one flower, and contains but one seed, although at first the ovary was (like that of the Oak) three-celled, with two ovules in each cell. These resemblances lead us to the conclusion that the Oak and the Beech are nearly related plants. They belong to the same Order '^Gupuliferoi)^ as do also the Iron wood, the Chestnut, and the Hazelnut, all of which should be examined and compared, if within reach. 73. The following are the distinguishing characters of the Order : 1, The flowers are moncecious, the sterile ones being in catkins {or^ in Beech, in close heads), the fertile single or in small clusters, with an involucre form- ing at maturity a cup or covering for the 1-seeded nut 2. The ovary is at first several-celled, hut at maturity is 1-celled and J seeded. The pupil will write out descriptions of one or more representatives of the Order, taking the description of (Jucumber for his model. \ t ' : H si-- t)4 ELEMENTS OF STRUCTURAL UOTANY. Fitr. 68. CHAPTER X. EXAMINATION OF PLANTS WITH DIO-'AJIOUS FLOWERS WILLOW MAPLE. 74. "Willow. The flowers of most kinds of Willow appear in spring or early summer before tlie leaves. They grow from the axils in long, close clusters called catkins or amnnts. Collect a few ol these fro7ri ths same tree or sliruh. You will find them to be exactly alike. If the first one you examine is covered with yellow stamens (Fig. 68), all the rest will likewise consist of stamens, and you will search in vain for any appearance of a pistil. If, on the other hand, one of your catkins is evidently destitute of sta- mens, and consists of oblong pistils (Fig. G9), then all tlie others will in like manner be found to be without stamens. Unlike our Cucumber plant, the staminate and pistillate flowers of tlie Willow are borne on different \\^wi^. These flowers are therefore said to be diwcious. As a general thing, staminate and pistillate catkins will be found upon trees not far apart. Procure one of each kind, and examine first the stami- nate one. You will probably find the stamens Fi". 70. '"• pairs. Follr " ,' any pair of lilaincuts down to Fig. 08. — Staminate catkin of Willdw, Fii,-. ,'i- otherwise the wind is tlie principal agent. Flowers which depend on insects to effect the transfer of pollen from the anther to the stigma are said to bo ento- moj)hil()ns. Those which depend upon the wind are anemophilous. The Willow belongs to the former class. 75. Maple. In early spring, while the branches are as yet bare of leaves, our Red Maples are covered with a profusion of scarlet and yellow blossoms, and the air about them is alive with busy insects gathering honey for themselves, and performing at the same time an impor- tant service for the trees in return ; for it will be found on examining a few of the trees that, like the Willow, they do not all bear the same kind of flowers. In some, the ends of the reddish twigs will present the appear- ance shown in rig.72,withnumerous stamens protruding from the scaly lateral buds. On looking into one of these buds it will be found that there are several flowers on short pedicels, each like that shown in Fig. 73, except that the number of stamens will probably be found to be somewhat variable. Observe the fleshy disk in the bottom of the calyx, upon which the stamens are inserted. These flowers with the projecting stamens are without pistils. They produce nothing but pollen, and the tree upon which you find them produces no other kind. Fig. 72. — Twig of Red Maple bearing staminate flowers. Fig. 73.— Single staminate flower. (Wood & Steele). Fig. 72. Fig. T8. THE MAPLES. 57 In other trees, the twigs will be found to resemble Fig. 74. The scaly buds are present, and the clusters of flow- ers within them as before, but the projecting stamens are wanting. If stamens are present at all, they are short and almost concealed in the calyx, as shown in Fig. 75, where two anthers are just visible over the edge of the calyx. The centre of the flower is occupied by a syncarpous pistil, having a two-celled ovary and two long styles, as shown in the figure. The flowers of tlie Maple, there- fore, being sterile or staminate upon one tree, and fertile or pistillate upon another, are, as in Willow, said to bo dioecious ; or, if we take into account the fact that some of the flowers have stamens as well as pistils, we shall more accurately describe the whole inflorescence ( or mode of flowering) as polijrjamo-dioecioiis. In Maple, as in Fig. 75. Willow, the assist- ance of insects is necessary to ensure the transfer of the pollen to the stigma. The flowers are, therefore, entomophilous. After fertilization, a wing is devel- oped from the back of each of the two carpels, and the pedicels lengthen, so that as the fruit ripens it presents the familiar aspect of hanging clusters of double samaras^ as these winged fruits are called (Fig. 76). Fig. 74.— Twig of Red Maple bearing pistillate flowers. Fig. 75.— Single pistillate flower. (Wood & Steele.) Fig. 76.— Winged fruit or samara of Maple. Pig. 74, Fig. 76. ) i! M) ^.*(T»l'l>t»ii:?»»- ^— 58 BLBMENTS OP STRUCTURAL BOTANY. I : i ■ !■ The Red Maple ripens its seeds early in the summer, and these, on falling, germinate immediately, so that by the autumn of the same year a vigorous young tree, a foot or more in height, is produced. The seeds will not germi- nate if kept over till the following spring. The Sugar Maple, on the other hand, flowers later, the leaves and flowers appearing about the same time, and the seeds do not ripen till the fall. If kept slightly moist through the winter they will germinate the following spring. 76. The several species of common occurrence should be carefully studied and distinguished. Their character- istics are given in the proper place in Part II. The Maples form a subordinate group of the natural Order Sapindacece. They are distinguished by the follow- ing characters : 1, The flowers are dioecious (or polygamo-diceciousjf and commonly unsymmetrical. 2, The ovary is tivo-lobed and two-celled, with two ovules in each cell, only one of which^ however^ is ripened. S, The fruit is a double samara. 4. The leaves are opposite. 77. From tliis type there are important deviations in other representatives of the Order. Horse-chestnut, for instance, while its flowers are unsymmetrical and some- what irregular, as in the Maples, produces a three-celled ovary, with two ovules in each cell. But avS in Maple, again, only one ovule in each cell forms a seed. The fruit, however, is not a samara, but a leathery pod which splits into three pieces at maturity, liberating the three I'lrge shining seeds. CHARACTERS COMMON TO DICOTYLEDONS. 59 nmer, by the oot or germi- r, the 5, and • moist [owing should iracter- latural follow- s)y and \h two very is Schedules descriptive of the Maple should be filled up, taking that of Willow as the model. ions in lit, for some- i-celled Maple, 3 fruit, splits h.xgQ CHAPTER XI. CHARACTERISTICS POSSESSED IN COMMON BY ALL THE PLANTS PREVIOUSLY EXAMINED — STRUCTURE OF THE* SEED IN DICOTYLEDONS. 78. Before proceeding further in our examination of plants, we shall direct your attention to some characters of those already examined, which they all possess in common. The leaves of every one of them are net-veined. Some leaves, at least, of each of them have distinct petioles and blades. The parts of the flowers we found, as a gen- eral thing, to be in Jives. In one or two instances they were in fours^ that is four sepals, four petals, and so on. 79. Now, in addition to these resem- 1 blances, there are others which do not iio immediately strike the eye, but which, nevertheless, are just as constant. One of these is to be found in the structure Fig. 77. Fig. 78. Fig. 79. of the embryo. Take a Cucumber or a Pumpkin seed, and having soaked it for some time in water, remove the outer coat. The body of the aeed will then readily split in two, except where the parts are joined at one end (Figs. 77, 78, 79). The thick lobes are called cotyledons, or seed-leaves, and as there are two, the embryo is dicotyledonous. The pointed end where the cotyledons Figs. 77, 78, 79.— Different views of Pumpkin seed, showing radicle, cotyledons, and plumule. I! I 60 ELEMENTS OF STRUCTURAL BOTANY. are attached, and from which the root is developed, is called the radidey a term meaning " little root." As it is strictly, however, u rudimentary s^em, and not a root, the term caulicle would be better. Between the cotyledons, at the summit of the radicle, you will find a minute upward projection. This is a bud, which is known as the plumule. It developes into the stem. 80. If you treat a Pea or a Bean (Figs. 80, 81) in the same manner as the Cucumber seed, you will find it to be Fig. 80. constructed on the same plan. The em- bryo of the Bean is dicotyledonous also. But you will observe that in these cases the embryo occupies the whole of the in- terior of the seed. In describing the seed of the Buttercup, it was pointed out that the embryo occupies but a very small space in the seed, the bulk of the latter consisting of albumen. Seeds like those of the Buttercup are therefore called alhujiiinous seeds, while those of the Bean and Pea are exalhuminous. But, notwithstanding this difi'erence in the structure of the seed, the eynbryo of the Buttercup, when examined under a strong magnifier, is found to be dicotyledonous like the others. In short, the dicotyledonous embryo is a character common to all the plants we have examined — common, as a rule, to all plants possessing the other characters enumerated above. From the general constancy of all these charac- ters, plants possessing them are grouped together in a vast Class, called Dicotyledonous plants, or, sliortly. Dicoty- ledons. Fig. 31. Figs. 80 and 81.— Seed of the Bean. LILIACEOUS PLANTS. 61 81. Besides the characters just mentioned, there is still another one of great importance which Dicotyledons possess in common. It is the manner of groivth of tlie stem.. In the Willow, and all our trees and shrubs with- out exception, there is an outer layer of bark on the stem, and the stem increases in thickness, year by year, by form- ing a new layer just inside the bark and outside the old wood. These stems are therefore called exogenous^ that is, outside growers. Now, in all Dicotyledonous plants, whether herbs, shrubs, or trees, the stem thickens in this manner, so thai Dicotyledons are also Exogens. CHAPTER XII. EXAMINATION OP COMMON PLANTS CONTINUED — DOGS-TOOTH VIOLET — TRILLIUM — IRIS ORCHIS. 82. Dog's-tooth Violet. This plant (Fig. 82), which flowers in spring, may be pretty easily recognized by its peculiar blotched*, leaves. It may be found in rich, moist pasture lands and low copses. The name " Violet " is somewhat unfortunate, because the plant is not in any way related to the true Violets. To obtain a complete specimen requires some trouble, owing to the fact that the root is commonly six inches or so below the surface of the ground ; you must therefore insert a spade or strong trowel sufficiently deep to avoid cutting or breaking the tender stem. Having cleared away the adhering earth, you will ^md that the roots proceed from what appears to be the M k I In 5*1 < i.i 111 62 ELEMENTS OF STRUCTURAL BOTANY. swollen end of the stem. This swollen mass is coated on the outside with thin scales. A section across the middle shows it to be more or less solid, with the stem growing Fig. 82. up through it from its base. It is, in fact, not easy to say how much of this stem-like growth is in reality stem, »i I — — ' »' Fip. 82.— Doic'8- tooth Violet, I I * n LILIACEOUS PLANTS. because it merges gradually into the scape, which bears the flower, and the petioles of the leaves, which sheathe the scape. The swollen mass is called a bulb. 83. The leaves are two in number, gradually narrowing at the base into sheaths. If you hold one of them up to the light, you will observe that the veins do not, as in the leaves of the Dicotyledonous plants, form a network, but run only in one direction : namely, from end to end of the leaves. Such leaves are consequently called straight-veined. 84. In the flower there is no appearance of a green calyx. There are six yellow Fig. 83. leaves, nearly alike, arranged in two sets, an outer and an inner, of three each. In such cases, wo shall speak of the coloured leaves collectively as the peri- anth. If the leaves are free from each other we shall ^peak of the perianth as polyphyllouSi but if they cohere we shall describe it as gainophyllous. Stripping off the leaves of the perianth, we find six stamens with long upright anthers which open along their outer edgea. If the anthers be pulled off, the filaments will be found to terminate in long, sharp points. The pistil (Fig. 83) has its three parts — ovary, style, and stigma — well marked. The stigma is evidently formed by the union of three into one. The ovary, when cut across, is seen to be three-celled (Fig. 84), and is, therefore, syncarpous. Fig. 83.~Pi8til of Dog's-tooth Viulet. Fig. 84.— Cross section of the pistil. Fig. 84. 1 niil < ■ I ; hi- ! ( 64 ELEMENTS OP ST.tUCTURAL BOTANY. DOG'S-TOOTH VIOLET. Organ. No. Cohesion. Adhesion. Be MARKS Perianth. Leaves. 6 Polyphyllous. Inferior. Stamens. G Hexandrous. Hypogynous. Filaments ter minating in sharp points. Pistil. Carpels. 3 Syncarpous. Superior. Fig. 87 is-- SP- SS. Trillium. This plant (Fig. 85) may be found in flower about the same time as the one just described. The perianth of Trillium consists of six pieces in two sets, but in this case the three outer leaves are green, like a com- mon calyx. The stamens are six in number. There are three styles, curving outwards, the whole of the inner side of each being stigmatic. The ovary (Fig. 86) is six-angled, and on being cut across is seen to be three-celled. Fip. 85. Fig. 86.— Trillium. Fig. 86.— Cross section of the pistil. Fig. 87.— Net-veined leaf of Trilliun*. LILIACEOUS PLANTS. 65 86. Comparing this flower with that of Dog's-tooth Violet, we find the two to exhibit a striking resemb- lance in structure. But in one respect the plants are strikingly unlike : the leaves of the Trillium are net- veined (Fig. 87), as in the Exogens. From this circum- stance we learn that we cannot altogether rely on the veining of the leaves as a constant characteristic of plants whose parts are not in fives. TRILLIUM. Organ. No. Cohesion. Adhksion. Eemarks. Perianth. Sepals, Petals. 3 3 Polyphyllous. Inferior. * Sepals persist- ent. Stamens. 6 Hexanorous. Hyp ogy nous. Pistil. Carpels. 8 Syncarpous. Superior. The inner face of each style stigmatic. Leaves net-veined. 87. The two plants just examined are types of the natural Order Liliacece. The distinguishing characters are as follows : 1. The parts of the flower are almost invariably in sets of three^ the perianth being of two such sets, and also the stamens. The flowers are therefore sym- metrical ; they are also regular. 2. The stamens are opposite the divisions of the perianth. S, The ovary is nearly always S-celled^ and is superior. ill 1 1! I :: r it l i I' i 66 ELEMENTS OP STRUCTURAL BOTANY. The representatives of this large Order are very nu merous. From the gardens may be had lilies of various sorts, Asparagus, Star-of-Bethlehem, Tulip, Onion, Hya- cinth, &c., whilst the fields and woods supply the Bell- wort, Clintonia, Solomon's Seal, Smi- lacina, and others. As a rule the plants flower in spring and early summer. 88. Iris. For this lesson any variety of the common garden Flag will answer very well. In our marshes in early summer abundant specimens of a wild species may be obtained without much trouble, but the culti\ated plants will probably be more accessible. Note first the fleshy underground stem or root- stock, with the fibrous roots below (Fig. 88). If you have a sufficient length of this root- stock you will notice the scars upon the' older portions, show- ing where the leaves of former seasons have been sent up. The new buds ex- pand into a crowded Fig. 88. cluster of leaves, the shape and arrangement of which should be carefully observed. Cut the whole cluster across near the base, and the section will be as repre- sented in Fig. 89, the section of each leaf being V-shaped, Fij,'. 8.S.— Root-stock and leaves of Iris. (Gray.) Fijj. 89.— Cross sectiou of cluster of equitaut le» ves, (Gray.) iRid. 67 and astride the next one within. Leaves disposed in this manner are consequently said to be equitant {eques^ a horseman). As the leaf ises upward it alters in shape, becoming flat and swor :' like. Besides being equitant, these leaves, on account of their direction, are described as vertical. You will observe, t^lso, that they are straight- veined. From the centre of the cluster of leaves rises the scape which bears the flower. If your specimen has a *lower- bud unon it, as is most likely, you will notice the way in whic^ i; leaves are folded. The mode of folding here exhibited is common to a great many flowers, and is described as convolute. In the full-blown flower the perianth will be found to consist of six pieces, in two distinct sets of three each ; the outer three are considerably larger than the others, and are bent backwards or reflexed; the Fig. 90. inner ones are erect. There are three stamens, each of them beneath and close against an over-arching body, the nature of which is not at first quite manifest. Cut away the perianth and the stamens, and you will then have left the three radiating coloured arches (Fig. 90), which will be seen to unite below into a slender column. You have also left what is apparently the swollen top of the scape. This, when cut across, is found to be a three-celled ovary, which is thus, of course, inferior. The slender column above is the style, and the Fig. 90.— Pistil of Iris. (Wood and Steele.) ■f *. ll^ . ;i 1 .r 'fc;'i 1 68 ELEMENTS OP STRUCTURAL BOTANY. I I !. ■■a three pefcal-like arches are its branches. Immediately beneath the tip of each arch will be found a thin lip or plate, which is the stigma. The anthers open outioards to discharge the pollen, and this fact, in addition to the peculiar situation of the anther as regards the stigma, makes it almost impossible that self-fertilization should take place in this flower. As was the case with other flowers already examined, the Iris is honey-bearing, and, besides, exceedingly showy. The nectar is situated in a cavity at the bottom of the flower, and cross-fertilization is accomplished by the aid of insects. It will be remembered that flowers thus fertilized are Raid to be entomophilous. 89. The Crocus and Gladiolus of the gardens and the Blue-eyed Grass of our low meadows may be examined and compared with the Iris. They are all types of the natural Order /nc^acece, which you will observe difiers from Idliacece chiefly in having flowers with only three stamens and an inferior ovary. lEIS. Organ. No. Cohesion. Adhesion. Remarks. Perianth. Leaves. 6 G-amophyllous Superior. 2 sets. Outer, large and re- flexed J inner, erect. Stamens. 3 Triandrous. Perigynous. Opposite the stigmas. Pistil. Carpels. 3 Syncarpous. Inferior. Stigmas pet- al-like,arching over the ex- trorse anthers. ORCHIS. A9 90. Showy Orchis. The flower of this plant (Figs. 91, 92) is provided with floral envelopes, all coloured like a corolla. As in Dog's-tooth Violet, we shall call tho»n collectively the perianth, although they are not all alike. One of them projects forward in front o2 the flower, Fig. 91. lorming the Up, and bears underneath it a long, hollo w^ spur which, like the spurs of Columbine, j»s honey-bearmg. The remaining five converge together, forming a kina of Fisr. 91.- Showy Orchis. • i n ELEMENTS OP STRUCTURAL BOTANY. I III arch over the centre of the flower Each flower spring* from the axil of a leaf-like bract, and is apparently raised on a pedicel. What seems to be a pedicel, how ever, will, if cut across, prove to be the ovary, which in this case is inferior. Its situation is similar to the situation of the ovary in Willow- herb, and, as in that flower, so in this the calyx-tube adheres to the whole surface of the ovary, and the three outer divisions of the perianth are simply upward extensions of this tube. Notice the peculiar hvist in the ovary. The effect of this twist is to turn the lip away Fig. 92. from the scape, and so give it the appearance of being the lower petal instead of the U2)per one, as it really is. 91. The structure of the stamens and pistil remains to be examined, and a glance at the flower shows you that we have here something totally diff'erent from the common arrangement ot these organs. In the axis of the flower, immediately behind the opening into the spur, there is an upward projection known as the column. The face of this column is the stigma ; on each side of the stigma, and adhering to it, is an anther-cell. These cells, though separated by the column, constitute but a single stamen. The stamen, then, in this case is united loit, the pistil. Fig. 93. a condition which is described as gynandrous. 92. If you have a flower in which the anther-cells are bursting open, you will see that the pollen does not issue from them in its usual dust-like form, but if you use the Fig. 92. — Single flower .' Orchis. Fig. 93.— Pollen-masa of Orchis, greatly enlarged. ORCHIS. n t, IS by are sue the point of your needle carefully you may remove the con- tents of each cell in a mass. These pollen-masses are of the form shown in Fig. 93. The grains are kept together by a line tissue or web, and the slender stalk, upon which each pollen-mass is raised, is attached by its lower end to a sticky disk on the front of the stigma just above the mouth of the spur. Insects, in their efforts to reach the honey, bring their heads in contact with these disks, and, when they fly away, carry the pollen-masses with them and deposit them on the stigma of the next flower visited. In fact, it is difficult to see how, without the aid of insects, flowers of this sort could be fertilized at all. SHOWY ORCHIS. Organ. No. Cohesion. Adhesion. Eemabks. Perianth. Leaves. 6 Gamophyllous Superior,. - Stamens. 1 3 Monandrous. Gyuandrous. Pollen-grains collected in masses. Pistil. Carpels. Syncarpous. Inferior. Ovary twisted. 93. Showy Orchis is a representative of the vast Order Orchidacemi the members of which are chiefly tropical. Some of oiir handsomest Canadian wild flow- ers, however, belong to it, such as the Lady's Slipper, the Rattlesnake Plant -^ in, the beautiful little Calypso, and the Habenarias. ^ost of our orchids will be found in low and wet situations, and they flower rather early I lit! i 'i i \ il '2 ELEMENTS OP STRUCTURAL BOTANY. in the year. The most remarkable characteristics oi the Order are the gynandrous arrangement of the stamen or stamens, and the cohesion of the pollen-grains, though this latter peculiarity is exhibited also by other groups — notably, the Milkweeds. CHAPTER XIII. EXAMINATION OF SPADICEOUS PLANTS — INDIAN TURNIP — CALLA. 94. Indian Turnip. This plant may be easily met with in our woods in early summer. If you are not familiar with its appearance, the annexed cut (Fig. 94; will he^p you to recognize it. Procure several speci- mens : these will probably at first seem to you to be alike in every respect, but out of a number some are pretty sure to difier from the rest. Notice the bulb from which the stem springs, it differs from that of the Dog's-tooth Violet, and Lilies generally, in having a much larger solid part. It is called a coi'm. Between the pair of leaves you observe a curious striped sheath, having an arcliing, hood-like top, and enclosing an up- right stalk, the top of which almost touches the hood (Fig. 95), Can this be a flower? It is certainly the only thing about the plant which at all rescDibles a flower, and yet how different it is from any we have hitherto examined ! Carefully cut away the slieaths •r'w INDIAN TURNIP. 73 from all your specimens. Most, and perhaps all, of them will then present an appearance like that in Fig. 96. If none of them be like Fig. 97 it will be well to gather a few more plants. We shall suppose, however, Fig. 94. that you have been fortunate in obtaining both kinds and will proceed with our examination. Take first a specimen corresponding with Fig. 9G. Around the base of the colunm are compactly arranged many spherical green bodies, each tippod with a little point. Separate Fijf. 94.— Indian Turnip. ' , LI '•> - . ^ i ? 11 74 ELEMENTS OF STRUCTURAL BOTANY. one of these from the rest and cut it across. It will be found to contain several ovules, rnd is, in fact, an ovary, the point at the top being a stigma. In the autumn a great change will have taken place in the appearance of plants like the one we are now examining. The arched hood will have dis- appeared, as also the long naked top of the column, v/hilst the part below, upon which we are now en- gaged, will have vastly increased in size, and become a compact ball of red berries. There can be no doubt, then, that we have here a structure anal- ogous to that found in the Cucumber and the Willow, the fertile, or pistillate, flowers being clustered together separate- ly. But in the Cucumber all the flowers were observed to be furnished with calyx and corolla, and in the Willow catkins, though floral envelopes were absent, each pair of stamens and each pistil was sub- tended by a bract. In the present plant there are no floral envelopes, nor does each pistil arise from a separate bract. *^' ^^' ^^' ^^" 95. But, you will now ask, what is this sheathing hood which we find wrapped about our column of pistils? Fiy. 9j.— Spathe of Indian Turnip. Fig. 96.— Fertile spadix of the same. Fig. 97. — Steviie spadix. Fijr. 96. INDIAN TURNIP. 70 will be ules, rnd nt at the 3 autumn e taken 3f plants :araining. lave dis- ag naked the part 5 now en- creased in ct ball of no doubt, 1 96. Fig. 97. Isheathing I of pistils? lieapaduL There is no doubt that we must look upon it as a bract^ because from its base the flower-cluster springs. So that, whilst the flowers of Indian Turnip are, like those of Willow, imperfect and dicecious, the clusters differ in having but a single bract instead of a btact under each flower. 96. We must now examine one of the other specimens ; and we shall have no diflicultyin determining the nature of the bodies which, in this case, cover the base of the column. They are evidently stamens, and your magni- fy ing-glass will show you that they consist mostly of an- thers, the filaments being extremely short, and that some of the anthers are two-celled and some four-celled, all discharging their pollen through little holes at the top of the cells. INDIAN TURNIP. Organ. No. Cohesion. Adhesion. ^ Stamens. 1 Monaudrous. 0 Q Pistil. Carpels. 1 Apocarpous. 0 Flowers crowded on a spadix, and surrounded by a spathe. Leaves net- veined. 97. The column upon which, in plants like Indian Turnip, the flowers are crowded, is known as a spa^iix, and the surrounding bract as a spathe. You will observe that the leaves of this plant are net veined^ as we found them in the Trillium. I* - ! If 1" V-BXItllllMIMW'— i.i'.iiiPll ilf»<»>- }iff. a' I II ^ll 76 ELEMENTS (-F P" RUCTURAL BOTANY. 98. Mareh Galia. This plant must be looked for in low, marshy grounds, where it will be found in flower generally in the month of June. With the knowledge which you have of the structure of Indian Turnip, you Vig. 98. Fig. 99. will hardly doubt that the Calla is closely related to it. You will easily recognize the spadix and the spathe (Fig. 98), though in the present instance the spadix bears flowers to the top, and the spatho is open instead of enclosing the column. Observe, however, that the veining of the leaf (Fig. 99) is different, that of Calla being straight, like the Dog's-Tooth Violet. There is alsc/ a difference in the flowers. Those of Indian Turnip were found to be dioecious, but the spadix, in the present I ¥\g. 98.— bpailix aiul Hpathe of Marah Calla. Fig. 99.— Leaf of the sauic. oked for in flower iiowledge rnip, you ted to it. le spathe le spadix II instead that the t of Calla There is III Turnip »(' present MAKoH CALI.A, 77 case, bears both stamens pn/! pistiib, and most of the lower flovre^'-, i£ not all, are ^lerfed ; sometimes 'e iip jer ones consist of sta- mens only. Fig. 100 shows one of the perfect flowers much enlarged. The sta- mens, it will be observed, have two-celled anthers, opening lengthwise. MAESH CALLA. Fig. 100. Organ. No. Cohesion. ADHEaiON. Perianth. Wanting. Stamens. 6 Hexandrous. Hypogvnous. Pistil. ■ Carpels. 1 /. T,oc&rpous. 1 Superior. 99. These two p>n' >, Indian Turnip and Marsh Calla, are representatives . . the Order Aracece. The characters which distinguish it fi-Q very well displayed in the two type? we have selected fov examination. The great feature is the aggregation of the flowers on a spadix. Generally, though not invariably, .a spathe is also present. Among wild plants the Skunk (Jabbnge and Sweet Flag (the latter without a spathe) are common Araceous types, while the familiar green-house and wimlow plant, known as the Calla-Lily,will serve very well for examination in winter. It may be added that the plants of this Order have a very acrid juice. Fig. 100.— Perfect flower of C*ila. ilhf m r ' '!• i • ' i! \ 1 1 ii i til ']i I il *!; 78 ELEMENTS OF STRUCTURAL BOTANY. CHAPTER XIV. EXAMINATION OP GLUMACEOUS PLANTS — TIMOTHY AND OTHER GRASSES. 100. Timothy. The top of a stalk of this well- known grass is cylindrical in shape, and upon examina- tion will be found to consist of a vast number of similar pieces compactly arranged on very short pedicels about the stalk as an axis. Carefully separate one of these pieces from the rest, and if the grass has not yet come into flower the piece will present the appearance shown in Fig. 101. In this Fig. the three points in the middle are the pro- truding ends of stamens. The piece which you have separated is, in fact, a flower enclosed in a pair of bracts, and all the other pieces which go to make up the top are flowers also, and, except perhaps a few at the very sum- mit of the spike, precisely similar to this one in their structure. Fip. 101. Fiy. 102. 101. Fig. 102 is designed to help you in dissecting a flower which has attained a greater degree of development than the one shown in Fig. 101. Here the two bracts which enclose the flower have been drawn asunder. To these bracts the name glumes is applied. They are present in all plants of the Grass Family, and are often Fig. 101.— Closed flower of Timothj'. Fig. 102.— Expanded flower of the sam^. m-\ GRASSES. 79 found enclosing several flowers instead of one as in Timothy. Jn Me the glumes will be found a second pair of minute ;alF-like bracts, which are known 'a,^ palets or pales. These enclose the flower proper. 102. The stamens are three in number, with the anthers fixed by the middle to the long slender filament. The anthers are therefore versatile. The styles are two in number, bearing long, feathery stigmas. The ova^y contains a single ovule, and when ripe forms a seed-like grain^ technically known as a caryopsis. ri \ (I TIMOTHY. Organ. No. Cohesion. Adhesion. Glumes. Pftlets. 2 Stameus. 3 Triandrous. Hypogynous. Pistil. Carpels. 1 Apocarpous. Superior. 103. It will be observed that the stalk of Timothy is hollow except itt certain swollen knot-like joints. This peculiar stem of the Grasses is called a culm. Occasionally, however, it is not hollow. The leaves are long and narrow and straight-veined, and each of them at its base surrounds the culm with a split sheath. Observe also that at the i 80 ELEMENTS OP STRUCTURAL BOTANY. i'^ if i \i' junction of the blade and the sheath there is a thin appendage which is called a ligule. 104. In many grass-flowers, besides the parts described above there will be found one or two minute scales below the pistil. These are known as lodicules, and are analogous to the perianth in ordinary flowers. They are, on ac- count of their minuteness, very liable to be overlooked in a superficial examination. 105. The immense Order Graminece (Grass Family) includes all our valuable grains, and is, on the whole, the most important and useful of all the Orders. Its representatives are to be found in every part of the world, and they vary in size from the stunted growths of the polar region !i' to the tree-like Bamboo of the tropics. Wheat, Indian Corn, Barley, Oats, Rye, Fig. 104. Fig.m Sugar-cane, Rice, are all Grasses, as well as the plants which make the verdure of our meadows and pastures. The flowers of all are very similar, but the Order is sub-divided on the basis of Fig. 103.— Panicle of Red-<,op. Fig. 104.— Single flower. (Gray.) GRASSES. 81 all of -/^'' ^ fft^ modifications which will be best understood by studying a few examples. 106. Procure specimens of the common Red-top, and first compare the general aspect of the flower-cluster (Fig. 103) with that of Timothy. Instead of a dense spike we have here a loose, open inflor- y^ escence ; it is technically known as a panicle. You will see that it is an irregular branched raceme. As in Timothy, each pair of glumes encloses Fig. 106. hut one flower (Fig. 104), and we must observe that the term spihelet^ so far as Grasses are concerned, is applied to the pair of glumes and whatever is contained in them, whether one flower, or many, as is often the case. In Red-top and Timothy, the spikelets are 1-floioered. Ob- serve the very thin texture of the jmlets, and also that one of them (the lower, i.e., the one farthest from the stalk) is nearly twice as large as the other, and is marked with three nerves. Fig. 105 Fig. 105. — Common Meadow-Grass. Fig. 106.~Spikelet enlaiyed, showing the glumes at the baae. Fig. 107.— Single flower of tiame. III ( I ' :' ! ii^ I !i «2 ELEMENTS OP STRUCTURAL BOTANY. Vf 1 • s • ' I i; r I ' ii 107. Next let us inspect a specimen of the Common Meadow-Grass. The inflorescence of this very common grass (Fig. 105) is a greenish panicle. The spikelets (Fig. 106) contain from three to five flowers, and are laterally compressed. The glumes are the lowest pair of scales, and they are generally shorter than the flowers within them. Observe the delicate whitish margin of the lower palet of each flower (Fig. 107), and the thin texture of the upper one. Count also, if you can, the five nerves on the lower palet, and observe the two teeth at the apex of the upper one. In this Grass the principal thing to notice is that there are several Jlowers ivithin each pair of glumes. 108. A common pest in wheat-fields is the Grass known as Chess. It is comparatively easy of examination on account of the size of the spikelets (Fig. 108) and flow- ers. The spikelets form a spreading panicle, eachof them being on a long, slender, nod- ding pedicel, and containing from eight to tei flowers. Of the two glumes at the base of each spikelcli one is consider- ably larger than the other. The outer or lower palet of each flower is tipped with a bristle or aum (Fig. 109), while the upper palet at length becomes attached to the groove of the oblong grain. Observe that the glumes are not awned. 109. The Couch Grass is another very common weed in cultivated grounds. In this Grass the spikelets are Fig. 108. Fig. 109. fl: Fig. 108.— Spikelet of Chess. Fig. 109.— Single flower. (Gray.) OUASSES. 83 id re sessile on opposite sides of the 7.igzag peduncle, so that the whole forms a spike. Each spikelet is four- to eight- flowered, and there is hut one at each joint of the peduncle, the side of the spikelet being against the stalk. The glumes are nearly equal in size, and the lower palet of each flower closely resembles the glumes, but is sharp- pointed or awned. The grass spreads rapidly by running root-stocks, and is troublesome to eradicate. 110. Old-Witch Grass is to be found everywhere in aandy soil and in cultivated grounds. The leaves are very hairy, and the panicle very large, compound, and loose, the pedicels being extremely slender. Of the two glumes one is much larger than the other. Unless you are careful you will regard the spikelets as 1 -flowered ; observe, however, that in addition to the one manifestly pei-fect flower there is an extra palet below. This palet (which is very muchlike the larger glume)is a rudimentary Dr abortive second flower, d\d the spikelet may be described as l|-flowered. 111. Barnyard Grass is a stout, coarse plant, common in manured soil. It is from one to four feet in height, and branches from the base. The spikelets form dense spikes, and these are crowded in a dense panicle which is rough with stiff hairs. The structure of the spikelets is much the same as in Old-Witch Gras3s, l)ut the palet of the neutral flower is pointed with a rough awn or bristle. 112. In th^" common Foxtail the inflorescence is apparently a. dense, bristly, cylindrical spike. In reality, however, it is a spiked panicle, the spikelets being much the same as in Barnyard Grass, but their pedicels are prolonged beyond them into awn-like bristles. In this IMAGE EVALUATION TEST TARGET (MT-3) ,V^ /. fc 1.0 I.I 1.25 IS lis 1^ 12^ 1^ 11112.2 "^ m 2.0 14 116 Photographic Sciences Corporation 23 WEST MAIN STREET WERSTER.N.Y. 14580 (716) 873-4503 ■*'^^^. ' Cl s 1 i! \f 84 ELEMENTS OP STRUCTURAL BOTANY. piant the bristles are in clusters and are barbed upwards. The spikes are tawny-yelloiv in colour. 113. These examples, if conscientiously studied with the aid of the plants themselves, will give you a good general idea of the kinds of variation which may be looked for in the Grasses. They may be said, roughly, to consist in the presence or absence of glumes, of awns, and of the upper palet ; in the general aspect of the whole flower- cluster ; in the number of flowers in the spikelets ; and in the varying relative size of the glumes and of the palets. 114. The Order as a whole is distinguished by the following characters : 1. The sheaths of the leaves are split on the side of the culm opposite the blade, 2. The separate flowers are enclosed in glumaceous bracts called palets 3. The perianth is represented hy the lodicules. 4n The stamens are three in number^ and the pistil is syncarpous (two carpels)^ with a one-celled ovar^ producitKj a single seed^ lohich is always albuminous with the mhryo on one side. CHAPTER XV COMMON CHARACTERISTICS OP THE PLANTS JUST EXAMINBD STRUCTURE OP THE SEED IN MONOCOTYLEDONS. jil5. It is now to be pointed out that the plants examined in the last three chapters, though differing in various particulars, yet have some characters common tc all of them, just as the group ending with Maple was CHARACTERS COMMON TO MONOCOTYLEDONS. 85 found to be marked by characters possessed by all its members. The flowers of Dicotyledons were found to have their parts, as a rule, in fours or fives ; those of our second group have them in threes or dxes^ never in fives. 116. Again, the leaves of these plants are straight- veined, except in Trillium and Indian Turnip, which must be regarded as exceptional, and they do not as a rule exhibit the division into petiole and blade which was found to characterize the Exogens. 117. We shall now compare the structure of a grain of Indian Corn with that of the Cucumber or Fig. no. Fig. Hi Fig. 111. Pumpkin seed which we have already examined (page 59). It will facilitate our task if we select a grain from an ear which has been boiled. And, first of all, let us observe that the grain consists of something more than the seed. The grain is very much like the achene of the Buttercup, but differs in this respect, that the outer covering of the former is completely united with the seed-coat underneath it, whilst in the latter the true seed easily separates from its covering. Remove the coats of the grain, and what is left is a whitish, starchy-looking substance, having a yellowish body inserted in a hollow (Fig. 110) in the middle of one side. This latter body is the embryo^ and may be easily removed. All tlie rest is albumen. Fig. Ill is a front view of the embryo, aud Y'v^. 112 shows a vertical section of the same. Tlie greater part of the Figs. 110, 111, 112.— Sections of a grain of Indian Corn. (Gray.) 86 ELEMENTS OP STRUCTURAL BOTANY. embryo consists of a single cotyledon. The radicle is seeR near the base, and the plumule above. Compare an Oat (Fig. 113) with the grain of Corn and make out the corre- sponding parts. In all essential particulars they are alike. 118. Comparing the result of our observations with what we have already learned about the Cucumber seed, we find that whilst in the latter there are two cotyledons, in the present case there is but owe, and this peculiarity is common to all the plants just examined, and to a vast number of others besides, which are consequently designated MonOCOtyledon- OUS plants, or shortly Monocotyledons. The seeds of this great group may differ as to f^ the presence or absence of albumen, just as the seeds of Dicotyledons do, but in the narnr her of their cotyledons they are all alike. The Orchids, however, are very peculiar from having no cotyledons at all. 1 19. In addition to the points just mentioned, viz : the number of floral leaves, the veining of the foliage leaves, the usual absence of distinct petioles, and the single cotyledon, which characterize our second great group, there is still another, as constant as any of these, and that is, the mode of growth of the stem, which is quite at variance with that exhibited in Dicotyledonous plants. In the present group the increase in the thickness of the stem is accomplished not by the deposition of circle after circle of new wood outside tlie old, but by the pro- duction of new wood-fibres through the interior of the stem generally. These stems are therefore said to be Figr. 113. Fig. 113. — Vertical section of Oat grain; R, radicle; G, plumule; 0, cotyledon ; A, albumen (or endosperm) ; O, hairs ; T, testa. (Thomi.) •o- characters op monocotyledons. 87 endogenous^ and the plants composing the group are called Endogens, as well as Monocotyledons. The term Endogen, however, is used in quite a diherent sense hy some recent botanists, and is discarded by them as a synonym for monocotyledon, as having been given originally under a misconception as to the true mode of growth of tlie wood in stems of this kind. We shall explain more fully the structure of exogenous and endogenous stems when we come to speak of the minute structure of plants in a subsequent chapter. 120. The typical flower of the Monocotyledons is that of the Lily ; it consists of five whorls, two belonging to the perianth, two to the anthers, and one to the pistil Other flowers of the group, as we have ceen, exhibit departures from the type, chiefly in the suppression of whorls or parts of whorls. Thus in the Iris one whorl of stamens is suppressed. In this plant, also, the ovary is inferior. In the spadiceous plants the perianth is suppressed, and in the Grasses there may be suppression in all the whorls. 0, CHAPTER XVI. EXAMINATION OF CONIFEROUS PLANTS — WHITE PINE — GROUND-HEMLOCK. 121. The cone-bearing trees are so striking and importanT ;j feature in Canadian vegetation that even an elementary work like the present would be incomplete without a notice of them. They form, besides, a very distinct group i 1'?' ELEMENTS OP STRUCTURAL BOTaNY. of plants, intermediate L structure, as we shall see, between the groups upon which we have so far been Fig. 115. Fig. 114. engaged and others to which we shall presently direct attention. 122. As perhaps the commonest Canadian type of the Coniferous Group, the White Pine first demands our attention. This noble tree, in its general aspect, is familiar to every one. It produces a straight trunk, which is continued upward year after year by the develop- ment of a strong terminal bud, the new branches of each year being developed from a circle of lateral buds formed behind the apex of the stem or old branch. The general aspect of the tree, therefore, unless it is a very old one, is that of a broad-based cone or spire. The leaves are straight Fig. 114.— Leaves and cluster of staminate catkins of White Pin«. (Wood and Steele.) Fig. 115.— Pollen-grain of Pine. (Wood and Steele.) WHITE PINE. 89 li needles, and are produced in clusters of five each. In the Red Pine, on the other hand, there are but two leaves in the cluster. Other species have bundles of three each. These leaves, as is well known, are evergreen^ that is to say, they do not perish in the first autumn, but persist through the winter and until the new leaves of the following season are fully developed. 123. The flowers of the Pine must be looked for in spring just before the new leaves are put forth. They are monoecious or dioecious. The staminate flowers, consisting of a single stamen each, are produced around the bases of the new shoots, where they form dense clusters of small catkins (Fig. 1 1 4). Each anther is two-celled, and the pollen-grains (Fig. 115) are rather peculiar in shape, having, in fact, the appearance of three grains cohering together. The two outer portions, however, are only bladder-like developments of the outer coat (extine) of the real grain, which occupies the Fig. 116. centre. 124. The pistillate or fertile flowers are aggregated together upon an elongated axis, forming in fact the well- known cone of the Pine (Fig. 116). The young cones will be found to occupy lateral positions on the branches ; each of them is made up of many spirally arranged scales^ each scale being in the axil of a bract (Fig. 117). At the base of each scale, on the inside, will be found two ovules turned downwards (Fig. 118). Observe that these ovules are not enclosed in an ovary. Because of this fact the group of plants of which the Pine is a type is said to be Fig. 116.— Cone of Pine. (Wood and Steele.) do ELEMENTS OP STRUCTURAL BOTANY. if.! Fig. 117. gymnospermouSi that is, naked-seeded. All the plants previously examined, on the other hand, have their seeds enclosed in ovaries ; hence they are all angiospermous. The scales of the cone are to be regarded as open carpellary leaves, and each of them, with its pair of ovules, constitutes a fertile flower. The pollen is carried by the wind directly to the micropyle of the ovule, there being no intervening stigma; but, as the quantity of pollen produced is immense, the chances of failure to reach the ovules are very slight. At the time of pollination, the air in a pine forest is full of pollen. The yellow scum often found on water after a summer shower is chiefly Pine pollen. After fertilization the ovules develope into seeds, and the scales of the cone, which are origin- all;' >■ rather soft texture, attain a woody couciotency. This process of maturing, how- ever, in the Pine takes considerable time. The cones do not ripen until the autumn of Fig. lis. the second year, after flowering. At this time the scales diverge from the axis, and the seeds are allowed to escape, each of them being now furnished with a wing, which enables the wind more readily to waft it away. The number of cotyledons in the embryo is variable, but is always more than two ; sometimes there are as manv as twelve. The wood of the Gymnosperms is essentially like that of the Dicotyledons, and the stem thickens in the same way. Certain differencea Fig. 119. will be noticed in another place. Fig. 117.— Single scale of Pine cone with its bract. (Wood and Steele.) Fig. 118.— Inner side of the scale, showing the two nalied ovules. (Wood Fig. 119.— StaminAtA catkins of Ground Hemlook. (and Steele.) GROUND HEMLOCF n 125. It will be interesting now to compare with the structure of the Pine that of another member of the came group — the Ground Hemlock, a low shrub common enough in our Canadian woods. This, like tlio Pine, is evergreen. The leaves, however, are not needle-shaped, but flat ; and they are not clustered, but project singly from the sides of the stem. 126. The staminate flowers (Fig. 119) grow in small catkins at the ends of very short lateral shoots which bear about their bases '^ - h\ , /ii many scale-liite bracts. The stamens are somewhat differ- ent from those of Pine, being umbrella- shaped (peltate), and bearing from three to ^'^' ^^' F'»- 121. eight pollen-sacs upon the under surface. The fertile flowers are also at the extremities of short, scaly-bracted branches, but in this plant the flowers occur singly, and are not aggregated in cones. Fig. 120 shows a section of a fertile branch w'th its bracts and the single naked ovule t.t its extremity. Around the base of the ovule there is a fieshy ring or disk (shown in section at a in the figure). The pollen is conveyed by the wind directly to the micropyle, md after fertiliza- tion, and during the development of the seed, the fleshy ring upon which it rests grows upward so as to surround the seed and give the fruit a remarkable berry-like appearance (Fig. 121). This fleshy covering (which is Fig. 120.— Section of fertile branch of Ground Hemlock ; s, the apparently terminal ovule; t, its internment ; k, the nucellus ; m, the micropyle ; a a, the rudiment of the aril, which firn* ly surrounds the seed ; b b, bracts. (Prantl). Fig. 121.— The same with mature fruit, /. (Prantl). 92 ELEMENTS OP STRUCTURAL BOTANY. ;I i bright red at maturity) is a good example of what is called an aril, 127. We find, then, that although there is at first sight little in common, apparently, between the cone of the Pine and the berry-like fruit of the Ground Hemlock (Taxus haccata), yet they both have the characteristic naked ovules. 128. Among our cone-bearing trees will readily be recognized the Arbor Vita? (commonly called Cedar), the Larch or Tamarack, which, however, is not evergreen, and the various kinds of Spruce or Fir. The Juniper, also, belongs to this group, but is marked by the peculiarity that the few scales of the cone cohere together in ripening and become succulent, thus forming what looks like a berry. 129. To sum up the results of our observations upon plant-structure, we have found (1) That all the plants to which our attention has so far been directed produce flowers ; they are all, therefore, flowering or phanerogamous plants, or, briefly, phanerogams. (2) That in a large number of the plants there are ovaries enclosing the seeds. All such plants are grouped as angiosperms. (3) That in others the seeds are not enclosed in an ovary. Hence we have a group known as gymno- sperms. (4) That the angiosperms are either dicotyledonous or monocotyledonous. life ^m- tfORPHOLOGY OF ROOTS, STEMS, AND FOLIAGE-LEAVES. 93 These conclusions may be conveniently shown in a tabular form as follows : PHANEROGAMS. ANQIOSPKHMa, (lYMNOBPERMB. DICOTYLEDONS. MONOCOTVLEDONS. CHAPTER XVTI. MORPHOLOGY OF ROOTS, STEMS, Al O FOLIAGE-LEAVES OF PHANEROGAMS. 130. Before proceeding with the examination of other selected plants illustrative of other divisions of the vegetable kingdom, we shall present in a systematic way the more important facts in connection with the Phanero- gams, dealing in turn with the organs of vegetation — the root, the stem, and the foliage-leaves — and then with the organs of reproduction as displayed in the flower. The various forms assumed by these organs, whether in diflerent plants or in different parts of the same plant, will have our attention, as also their various modes of arrangement. We shall consider, also, rather more minutely than we have hitherto been able to do, the development of the seed from the ovule, the process of pollination and of fertilization, and the subsequent germination of the seed and development of the new plant. To this study of forms the name Mo^jlinlogy has been given. It need hardly V>e said that effective morphological work can only be accomplished b^ actual 94 ELEMENTS OP STllUCTURAL UOTANY. ii contact with and inspection of the forms which are, for the time being, the objects of study. The young student must provide himself with specimens, and learn to associate the descriptive terms with the actual condition which the terms describe. Only in this way can this branch of botanical work be relieved of the element of Irudgery, and made what it ought to be — a means of developing in a high degree those powers of observation with which tiie young are so exceptionally endowed. It is believed that with proper management even the more difficult technical terms, which are derived from Latin and Greek, and specially devised for botanical purposes, will be learned without extraordinary effort. It is the writer's experience that a term is insensibly acquired and almost indelibly impressed upon the mind ij there is first created the toant of the term to describe what is seen when some new form has been the subject of obser- vation, and its peculiarities have been thoroughly grasped through the medium of the eye. With a good many of the terms there will be found no difficulty whatever, since they have the same meaning in their botanical applications as they have in their every-day use. 131. The Root. This organ is called the descending axis of the plant, from its tendency to grow downward into the soil from the very commencement of its develop, ment. Its chief use is to imbibe liquid nourishment, and transmit it to the stem, from which it is well distin- guished by the presence of the root-cap (Fig. 122, a) and the absence of leaves. The absorbing surface of a young root or rootlet is largely increased by the development of root-hairs^ the nature of which will be explained later on when we come to treat of trichomes or hair-like growths ROOTS. 95 generally. It must be mentioned here, also, that there are some exceptions to the general statement that roots do not produce buds. It is well known that new stems are sent up by the roots of Poplars and of Apple trees, for example, especially it the roots have been injured. These cases must be regarded as abnormal 132» You will remember that in our examination of some common seeds, such as those of the Pumpkin and Bean (Figs. 77-81), we found at the junction of the cotyledons a small pointed projection called the radicle. Now, when such a seed is put into the ground, under favorable circumstances of warmth ind moisture, it begins to grow or germi- natey and the radicle, which in reality is a minute stem, not only lengthens, in most Fig. 122. cases, so as to push the cotyledons upwards, but deveiopes a root from its lower extremity. All seeds, in short, when they germinate, produce roots from the extremity of the radicle, and in a direct line with it, and roots so produced are called primary roots. In Monocotyledons the primary root is but very slightly developed, the fibrous roots character- istic of these plants bursting forth from the sides oi the radicle at an early period of growth. In other plants the primary root either assumes F\g. 123. the form of a distinct central axis larger than any of its branches, and called a tap-root (Fig. 123), examples of which are furnished by the Mallow, the Carrot, and the Fig. 122. — Magnified tip of Hyacinth root ; a, the root-cap. (flooker.) Fig. 123.— Tap-root of Dandelion, II 'i? ( 'i; ^ '-n 96 ELEMENTS OP STRUCTURAL BOTANY. i.V' Fig. 124. growth. Bean, or it may branch at an early stage into numerous similc«r threads, and so form a fibrous root, as in Buttercup. 133. Tap-roots receive different names according to the particular shape they happen to assume. Thus, the Carrot (Fig. 124) is conical, because from a broad top it tapers gradually and regularly to a point. The Radish, being somewhat thicker at the middle than at either end, is spindle- shaped. The Turnip, and roots of similar shape, are napiform {napms, a turnip). These fleshy tap-roots belong, as a rule, to biennial plants, and are designed as storehouses of food for the plant's use during its second year's Occasionally fibrous roots also thicken in the same manner, as in the Peony, and then they are said to be fasciclea or clustered. (Fig. 125). 134. But you must have observed that plants some- times put forth roots in addition to those develop- ed from the embryo of the seed. The Verbena of our gardens, for example, will take root at every joint if the stem be laid upon the ground (Fig. 126). The runners of the Strawberry take root at their extremities; and nothing is more familiar than that cuttings from various plants will make roots for themselves if put into proper soil, and supplied with warmth and moisture. Fig. 124.- Tap-root of Carrot. Fig. 125.— Fascicled roots of Peony. ROOTS. 97 Ail such roots, not developed from the end of the radicle and in a straight line with it, are called secondary or adventitious roots. Under this head should, of course, be placed the fibrous roots of all Monocotyledonous plants, the true primary roots of which are but very feebly developed. So, also,all branches of primary roots should be re- garded as adven- titious. When such roots are developed from parts of the stem which are not in contact with the ground, they are Fig. 126. aenalf as, for example, the roots developed from the lower joints of the stem of Indian Corn. 135. There are a few curious plants whose roots never reach the ground at all, and which depend altogether upon the air for food. These are called epiphytes. There are others whose roots penetrate the stems and roots of other living plants, and thus receive their nourishment as it were at second-hand. These are parasitic plants. The Dodder and Beech-drops, of Canadian woods, are well-known examples. Others, again, subsist upon decomposing animal or vegetable matter, and are hence known as saprophytes. Indian Pipe and Coral-root are good examples of saprophytic plants. Both parasites and saprophytes are usually destitute of green leaves, Fig. 126.— Adventitious roots of Verbena. ['<■» 98 ELEMENTS OP STRUCTURAL BOTANY. : being either pale or brownish. The Mistletoe, however, is a green parasite. 136. Aa to duration, roots (and, consequently, the plants themselves) are either annual^ or biennial, or perennial. The plant is called an annual if its whole life, from the germination of the seed, is limited to one season. It is biennial if it flowers and ripens its seed in the second season. Between these two classes it is difficult to draw a sharp line, because, with proper care, some annuals may be induced to live for two years; and, on the other hand, some plants, as the Radish, which are properly biennial if the seed is sown in the fall, will flower and produce seed in one season if sown in the spring. Something, also, depends upon the climate in which the plant is grown, its life, in some cases, being prolonged in a more favourable situation. Perennials live on year after year, as is the case with all our shrubs and trees, and also with some herbp ceous plants, as Peony and Dahlia, which only die down to the surface of the ground in the autumn. 137. The Stem. As the root is developed from the lower end of the radicle of the embryo, so the stem is developed from the upper end, but with this important difference, that a bud always precedes the formation of the stem or any part of it or its branches. If a bud, such as that of the Lilac, be picked to pieces, it will be found to consist mostly of minute leaves closely packed together on a short bit of stem. A bud, in fact, is only a special condition of the extremity of the stem, and is not to be regarded as an organ distinct from it. As the bud unfolds, the 9tem may lengthen so as to exhibit the iuteruodeS) or ,1 •> BtEMS. 90 it may remain short, in which case the expanded leaves form a cluster or rosette, as in DarideHon. The tender leaves of the bud are not uncommonly protected from the weather by coverings in the form of tough scales, with the additional safeguard sometimes of a wax-like coating on the surface of the latter, as seen in the conspicuous buds of the Horse-Chestnut, and the cap-like coverings of those of the Spruce. 138. Between the cotyledons of the Bean (Fig. 81), at the top of the radicle, we found a minute bud called the plumule. Out of tliis bud the first bit of stem is developed (leaving out of consideration the radicle itself), and during the subsequent growth of the plant, wherever a branch is to be formed or a main stem to be prolonged, there a bud will invariably be found. The branch buds are always in the axils of leaves, and so are called axillary^ and it not uncommonly happens that several buds are found together in this situation. 139. Adventitious buds, however, are sometimes produced in plants like the Willow, particularly if the stem has been wounded. As already mentioned, they are also occasionally produced upon roots, as, for example, upon those of the Poplars. 140. The bud from which the main stem is developed, or a branch continued, is of course at the end of the stem or branch, and so is terminal. 141. Branching or Ramification. By a branch is meant an oflf-shoot similar in structure to the member from which it springs. Hence the side-shoots of roots are root-branches ; so, also, the lateral out-growths of the stem which resemble the stem itself in structure are 1^ , !■ frf " III 11 f ] r 100 ELEMENTS OF STRUCTURAL BOTANY. stem-branches. It is found that the branching of steins proceeds upon two well defined plans. 142. Monopodial Branching. This system is distin- guished by the circumstance that all the branches are the result of the development of strictly lateral buds. In other words, there is invariably a terminal bud at the apex of the stem distinct from the lateral buds produced behind the apex. Of this system there are several Fig. 130. Fig. 127. Fig. 128. modifications. If the terminal bud develops regularly, as well as the lateral ones, it is clear that we shall have a straight and well-defined trunk, easily distinguished by its vigorous growth from the branches. The Pine or the Spruce is an excellent example of this effect. Figs. 127, 128, 130.— Diagrams of various forms of monopodial branching. (Sachs.) MONOPODIAL BRANCHING. lot But if the terminal bud, though produced, ceases to grow, while the lateral buds are vigorously developed, as is well exhibited in the spring by the annual shoots of the Lilac, then it is clear that the 6 branches will overtop the original stem, J ^ p and the latter will finally become unrecog- nizable. « 143. The Pine and the Spruce and similar forms are said to be racemose or hotryose, and the Lilac, in the development of its annual shoots, is said to be cymose. Fig. 127 is a representation of the latter mode. Here 1 is the extremity of the main stem, but the terminal bud at that point has failed to grow, while two vigor- ous branches have been produced. The terminal buds of these branches (2 and 2), have in their turn failed, and the laterals immediately behind them have, as before, given rise to new shoots. This is the result, then, when both the lateral buds grow with equal vigour, and it is known as a forked cyme. 144. But sometimes one member of each pair of buds is developed far more strongly than the other. If the strong buds are developed in succession on the same side of the stem an effect will be produced like that represented in Fig. 128. This is known as a helicoid cyme. If, however, the strong buds are developed alternately on both sides of the stem, we get the form shown in Fig. 129, which is then called a scnrpioid cyme. Not un^ Fig. 129.— Diatfram to illustrate scocninjd cyme. (Sachs.) Fig. 120. 102 ELEMENTS OP STRUCTURAL BOTANY. commonly this latter form becomes straightened out, as in Fig. 130, so that the successive branches are in the same line, and look like a stem developed from the terminal bud. As the foot or support is not in this case the continuation of a single axis, but is made up of a num- ber of successive branches superposed, these forms are said to be sympodialf the prefix in this term having the same sig- nificance as in " syn- carpous" and the like, and implying that the foot is composed of several coherent parts. In these cases, then, we have a s^ympoiial monopodium. 145. Dichotomous Branching. In this system the growing point at the apex of the stem divides into two new groioing points^ both of which are, therefore, terminal and not lateral, as in the first mode. The growing points of the branches, in their turn, are each converted into two new ones, as shown in Fig. 131. As in the monopodial mode, there may be helicoid and scorpioid dichotomy, due to the superior development of the growing points on Fig. 13a Fig. 132. Fig3. 131, 132, and 133.— Diagrams to illustrate dichotomous branching. ^Sacha.) DiCHOTOMOtJS BRANCHING. 103 one side, or on alternate sides of the stem, as shown in Figs. 132 and 133. These forms are, of course, sympodiai. 146. A comparison of Figs. 127 and 131 will show that there is a superficial resemblance between the forms. On this account the forked cyme is sometimes referred to as a dichasium or false dichotomy, 147. Dichotomous branching is rare, but occurs in the roots of Club-Mosses, and in Lichens. In the phanero- gams, monopodial branching is the almost invariable rule. The flowering stems, which afford the best illustrations, will be referred to hereafter. 148. If you examine a few stems of plants at random, you will probably find some of them quite soft and easily compressible, while others will be firm and will resist compression. The stem of a Beech or a Currant is an instance of the latter kind, and any weed will serve to illustrate the former. The Beech and the Currant have looody stems, while the weeds are herbaceous. Between the Beech and the Currant the chief difference is in size. The Beech is a tree, the Currant a shrub. But you are not to suppose that there is a hard and fast line between shrubs and trees, or between herbs and shrubs. A series of plants could be constructed, commencing with an unquestionable herb and ending with an unquestionable tree, but embrac.'ng plants exhibiting such a gradual transition from herbs to shrubs and from shrubs to trees, that you could not say at what precise point in the series the changes occurred. 149. The forms assumed by stems above ground are iimnerous, and they are described mostly by terms in common use. For instance, if a stem is weak and trails 1 1 < ! Ill ■4 i t I i i m, '.i^Sti.,* / 104 KLEMKNTS OF STRUCTDRAL BOTANY. :!■ along the ground, it is trailing or prostrate ; and if, as in the runners of the Strawberry, it takes root on the lower side, then it is creeping. Such a shoot as the run- ner of the Straw- berry, which takes root at a distance from the parent pjg 134 plant, is commonly called a stolon. 150. Many weak stems raise themselves by clinging to any support that may happen to be within their reach. In some instances the stem itself winds round the support, assuming a spiral form, as i.i the Morning-Glory, the Hop, and the Bean, and is therefore distinguished as ticining. In other cases the stem puts forth thread-like leafless branches called tendrils (Fig. 134), which grasp the support, as in the Virginia Creeper and the Grape. In the Pea, the end of the extended mid-rib of the leaf is transformed into a tendril (Fig. 135). Sometimes the leaf- stalks themselves serve the same purpose, as in the Clematis or Virgin's Bower. In these cases the stems are said to climb. Our Poison Ivy climbs over logs, &c., by the aid of its aerial roots. The stems of wheat and grasses generally are known as Fig. 134. — Leaf and tendril of Grape-vine. Fig. 136— Tendril of the Pea. Fig. 135. II a UNDERGROUND STEMS. 105 ^ulms. They are jointed, and usually hollow except at the joints. 151. Besides the stems which grow above ground, there are varieties to be found below the surface. Pull up a Potato plant, and examine the underground portion (Fig. 136). It is not improbable that you will regard the whole as a mass of roots, but a very little trouble will undeceive you. Many o^ the fibres are unquestionably i'l Fig. 136. roots, but an inspection of those having potatoes at the ends of them will show you that they are quite different from those which have not. The former will be found to be furnished with little scales, answering to leaves, each with a minute bud in the axil ; and the potatoes them selves exhibit buds of the same kind. The potato, in short, is only the sivojlen end of an underground stem.. oucii swollen extremities are known as tubers, whilst the Fig. 136.— Tubere of the Potato. IP 1 1 106 ELEMENTS OF STRUCTURAL BOTANY. underground stem is called a root-stoek or rhizome^ and may almost always be distinguished from a true root by the presence of buds. The Solomon's Seal and Too<^^ i of Canadian wooas, and the Canada Thistle, are common instances of plants producing these stems. Fig. 137 shows a rhizome. 152. Take now an Onion, and compare it with a Potato. You '^' * will not find any such outside appearances upon the former as are presented by the latter. The Onion is smooth, and has no buds upon its surface. From the under side there spring roots, and this circumstance will probably suggest that the Onion must be a stem of some sort. Cut the Onion through from top to bot- tom (Fig. 138). It will then be seen to be made up of a number of coats. Strip off one or two, and ob- serve that whilst they are somewhat fleshy where the Onion is broadest, they grad\^ally become thinner to- wards the top. The long, gre^m tubes which project from the top of the Onion during its growth are, in fact, the prolongations of these coats. But the tubes are the leaves of the plant itself. The mass of our Oiiion, therefore, consists Fig. 137. — A rhizome. Fig. 138. — Vertical section of bulb of the Onion. 23 I UNDERGROUND STEMS. 107 of the fleshy bases of the leaves. But you will observe that at the bottom there is a rather flat, solid part upon which these coats or leaves are inserted, and which must consequently be a stem. Such a stem as this, with its fleshy leaves, is called a hulh. If the leaves form coats, as in the Onion, the bulb is coated or tunicated; if they do ^«- ^^- not, as in the Lilies (Fig. 139), it is scaly. 153. Tubers and bulbs, then, consist chiefly of masses of nourishing matter ; but there is this difference, that in the latter the nourishment is contained in the fleshy leaves themselves, whilst in the former it forms a mass more or less distinct from the buds. 154. The thickened mass at the base of the stem of our Indian Turnip (Fig. 94) is more like a tuber than a bulb in its construction. It is called a corm or solid bulb. The Crocus and Gladiolus of the gardens are other examples. The chief diflference between the conn and the ordinary bulb is in the relative space occupied by the stem or solid part. In the former it is very much greater than in the latter. The student should dissect specimens of Indian Turnip, Crocus, Tulip, Hyacinth, &c., when these differences will be readily apprehended. 155. In the axils of the leaves of the Tiger Lily are produced small, black, rounded bodies, which, on examination, prove to be of bulbous structure. They are, in fact, bulblets, and new plants may be grown from them. 156. Foliage-Leaves. These organs are usually more or less flat, and of a green colour. In some plants, i{ Fig. 139.— Bulb of a Lily. 108 elemp:nts op structural botany. horvever, they are extremely thick and succulent ; atid in the case of parasites and saprophytes, such as Indian Pipe and ]3eech-drops, they are usually either white or brown, or of some colour other than green. The scaly leaves of underground stems are also, of course, destitute of colour. The green colour is due to the presence of granular particles of a substance called rJiloropkyU. It is formed, as a rule, only in those parts which are exposed to the action of sunlight, and it is intimately connected with the process of assimilating nutritious matter for the plant's use during growth. Further reference will be made to it later on. 157. As a general thing, leaves are extended horizontally from the stem or branch, and turn one side towards the sky and the Ot.ier towards the ground. But some leaves are vertical^ and in the case of the common Iris (Figs. 88 and 89) each leaf is doubled lengthwise at the base,and sits astride the next one within. Such leaves are called equitant. 158. Phyllotaxis or Leaf- Arrangement. As to their arrangement on the stem, leaves are alternate when only one arises from each node (Fig. 3). If two are formed at each node, they are sure to be on opposite sides of the stem, and so are described as opposite. If, as in Mint and Maple, each pair of opposite leaves stands at right angles to the next pair above, then the arrangement is decussate. Sometimes there are several leaves at the same node, in which case they aretohorled or verticillate(Fig.liO). Fig. 140. Fig. 140»^Whorled leaves of Galium. PHYLLOTAXIS. 109 iDy. Even if the leaves are placed single and apparently irregularly at intervals along the stem, it will be found on examination that their ai rangement is governed by defi- nite laws. Take, for instance, a branch of Poplar with a number of leaves upon it. Fix ujxm any one leaf near tlie lower end of the branch, and tiien from its point of insertion draw a line, % the ncun'st ivaij^ to the insertion of the next higher leaf, and from this to the next, and so on till you reach a leaf wliich is exactly over the iii'st one. If the branch itself has not been twisted out of its noriiial . shape, it will be found that the aivth leaf is always pre- cisely over the first, the seventh over the second, the eighth over the third, and so on, and that the line joining the points of insertion of successive leaves forms a spiral round the stem. It will also be found that this spiral goes twice round the stem before passing tnrough the sixth leaf. The sixth leaf, as standing exactly over the first, begins a new set, which lasts in a similar manner till we reach the eleventh. The leaves are therefore in sets or cycles of five each, and the phyllotaxis in this case is conveniently described by the fraction f , the denominator of which gives the number of leaves in the cycle, and the numerator the number of turns in the spiral. 160. Now, if through the insertions of the leaves which are vertically over each other — that is, through those numbered 1, 6, 11, 16, etc., and then through those numbered 2, 7, 12, 17, and so on — lines be drawn, it is evident we shall have five such vertical lines on the stem. These lines mark the ranks of leaves, or orthosticliies. The number of orthostichies in any case always corresponds to the number of leaves in the cycle. «i \\ itl' no ELEMENTS OP STRUCTURAL BOTANY. 161. In the Elm, the phyllotaxis is much simpler. Here, starting with any given leaf, it will be found that the next one is exactly half way round the circumference of the stem, and the third one exactly over the first, and so on. So that the spiral completes the circuit in one turn, and the number of orthostichies is only two, the phyllotaxis being therefore described as J. The J arrange- ment is also common. The Poplar, as we see, has a f arrangement ; this is extremely common. 162. If we set down these fractions in order, thus : |^, ^f f, it will be noticed that the sum of the first two numerators gives the third numerator ; so also with the denominators. If we proceed to make other fractions in this way, the series would read ^, J, f , |, x^-i, ^^j-, ^|, and these are, as it happens, the actual cases of phyllotaxy which we commonly meet with. The cone of the White Pine furnishos a very good exercise. In this case the scales (which, of course, are leaf-forms) have a i^s arrangement. 163. The conclusion come to from a close examination of the incipient buds is, that the newer leaves are produced over the widest intervals between those next below. In short, the arrangement is that which secures to the leaves the most advantageous conditions for exposure to the light, and at tne same time economizes space. As has been aptly said, the growth of the new leaves follows the "lines of least resistance." 164. When leaves are in whorls instead of in spirals, the members of any whorl stand over the spaces of the whorl below, as might be expected. As to leaves which are clustered or fascicled, like tliose of the Piue and Larch, it may be pointed out that the clustering is due simj)ly to FORMS OP FOLIAGE-LEAVES. Ill the non-development of internodes. The clusters when carefully examined, show in some cases an alternate, and in others a whorled, arrangement. 165. As branches are produced in the axils of leaves, it is clear that the arrangement of branches will be the same as that of the leaves. It rarely happens, hov/ever, that all the buds develope into branches. Many of them fail, so that generally branches appear to have no very definite arrangement. 166. Vernation oi PrSBfoliation. These terms have reference to the mode in which the new leaves are folded in the bud. Very commonly the leaf is simply doubled lengthwise, the upper side of the leaf within ; . then its vernation is said to be conduplicate. In the Maple and Mallow the folding is fan-like, and is described as plaited. In the Cherry the leaf is coiled in a single coil beginning with one edge : this is convolute vernation ; but if the coiling is from both edges to the mid rib, it is said to be involute ; if both edges are rolled backward, it is revolute. The vernation is circinate when the leaf is coiled from the tip, as in Ferns. 167. Forms of Foliage-Leaves. Leaves present an almost endless variety in their forms, and accuracy in describing any given leaf depends a good deal upon the ingenuity of the student in selecting and combining terms. The chief terms in use will be given here. Compare a leaf of the Round-leaved Mallow with one of Red Clover (Figs. 141, 142). Each of them is furnished with a long petiole and a pair of stipules. In the blade, however, there is a difference. The blade of the former consists of a single piece ; that of the latter I i: M W^ 112 ELEMENTS OF STRUCTURAL BOTANY. is in three separate pieces, each of which is called a leaflet J but all of which, taken collectively, constitute the blade of the leaf. The leaf of the Mallow is simple ; that of the Clover is compound. Between the simple and the compound form there is every possible shade of gradation. In the Mallow leaf the lohes are not very clearly defined. In the Maple (Fig. 143) they are well Fipr. 141. Fig. 142. marked. In other cases, again, the lobes are so nearly separate that the leaves appear at first sight to be really compound, 168. You will remember that in our examinations of dicotyledonous plants, we found the leaves to be invariably net- veined. But, though they have this general character in common, they differ considerably in the details of their veining, or venation, as it is called. The two leaves employed as illustrations in the last section will Fig. 141. Simple palinately-vcined leaf of Mallow. ITig. 142.— Compound leaf of Clover. foums of foliage-leaves. 113 serve to illustrate our meaning here. In the Mallow, there are several ribs of about the same size, radiat- ing from the end of the petiole, something like the spread-out fingers of a hand. The veining in this case is therefore described as digi- tate^ or radiate^ or palmate. The leaflet of the Clover, on the other hand, is divided exactly in the middle by a single rib (the mid-rib), and Fig. 143. from this the veins are given off on each side, so that the veining, on the whole, presents thj^ appearance of a feather, and is, therefore, described as pinnate ^penna^ a feather). 169. Both simple and compound leaves exhibit these two modes of venation. Of simple pinnately-veined leaves, the Beech, Mullein, and Willow supply familiar instances. The Mallow, Maple, Grape, Cur- rant, and Gooseberry have simple radiate - veined leaves. Sweet- Brier (Fig. 43), Mountain Ash, and Rose have compound pinnate leaves, whilst those of Virginia- Fig. 144. Creeper (Fig. 144), Horse-Chest-nut, and Hemp are compound digitate. ' — . — - — -« Fig. 143.— Palmately-lobed leaf of Maple. Fig. 144.— Palmate leaf of Virginia Creeper. 1 114 ELEMENTS OF STRUCTURAL BOTANY. i i As has already been pointed out, the leaves of Mono- cotyledonous plants are almost invariably straight-veined. 170. In addition to the venation, the description of a Fig. 145. Fig. 146. simple leaf includes particulars concerning : (1) the gen- eral outline, (2) the edge or margin, (3) the point or apex, (4) the base. 171. Outline. As to outline, it will be convenient to consider first the forms assumed hy leaves without lob^s, Lanceolate Ovate Deltoid Fig. 147. Fig. 148. and whose margins are therefore more or less continuous. Such leaves are of three sorts, viz.: those in wh7ch both ends of the leaf are alike, those in which the apex is Figs. 145 to 148.— Various forms of foliage-leaves. POLlAGE-LEAVES. 115 nan'ower than the base, and those in which the apex is broader than the base. 172. In the first of these three classes it is evident that any variation in the outline will depend altogether on the Fig. 152. Fig. 153. Fig. 149. Fig. 150. Fig. 151. relation between the length and the breadth of the leaf. When the leaf is extremely narrow in comparison with its length, as in the Pine, it is acicular or needle-shaped (Fig. 145). As the width increases, we pass through the forms known as lineavy oblong^ oval, and finally orbicular, in which the width and length are nearly or quite equal (Fig. 146). Fig. 154. 173. In the second class the ditferent - forms arise from the varying width of the base of the leaf, and we thus have subulate or awl- shaped (Fig. 147), lanceolate, ovate, and deltoid leaves (Fig. 148). Figs. 149 to 154.— Various (onus of foliage leaves. I J! \-\ w m 116 ELEMENTS OP STRUCTURAL BOTANY. i f 174. In the third class, as the apex expands, we have the forms spathulate (Fig. 149), ohlanceolate — that is, the reverse of lanceolate (Fig. 150), and ohovate (Fig. 151). 175. In leaves of the second kind we frequently find the base indented, and then the leaf is cordate or heart- Fig. 155. Fig. 156. Fig. 157. shaped (Fig. 152). The reverse of this — that is, when the indentation is at the apex — is ohcordate (Fig. 153). The hastate or spear-shaped (Fig. 154), sagittate or arrow- shaped (Fig. 155), and reniform or kidney-shaped (Fig. 156) forms are modifications of the second class, and will be readily understood from the annexed figures. / If the petiole is attached to any part of the under surface of the leaf, instead of to the edge, the leaf is 2^eUate (shield-shaped) Fig. 158. (Fig. 158). 176. Leaves which are lobed are usually described by stating whether they are palmately or pinnately veined; and Figs. 155 to 158.— Various forms of foliage-leaves. FOLIAGE-LEAVES. 117 if the former, the number of lobes is generally given. If the leaves are very deeply cut, they are said to be ^>a/??ia^^/t6? ov pinnatijid , according to the veining (Fig. 1 59). If the leat is pinnatifid and the lobes point backwards towards the base, as in Dandelion, the leal is said to l)e runcinate. If the leaf is palmately lobed, and tlie lobes at the base are them- selves lobed, the leaf is pedate (Fig. 160), because it looks something like a bird's foot. If the lobes of a pinnatifid leaf are them- selves lobed, the leaf is hii>innatifid. If the i^^|i/'5 leaf is cut up into fine segments, as in \| Dicentra, it is said to be multifid. H 177. Apex. The principal forms of the Fig. 159. apex are the mucnmate (Fig. 157), when the leaf is tipped with a sharp point, as though the "mid-rib were projecting beyond the blade ; cuspidate^ when the leaf ends abruptly in a very short, but distinctly tapering, point (Fig. yf. 161); acute, or sharp; and obtuse, or blunt. It may happen that the apex does not end in a point of any kind. If it looks as though the end had been cut off square, it is truncate. If Fig.' 161 the end is slightly notched, but not sufficiently so to warrant the description obcordate, it is emanjinate. 178. Margin. If the margin is not indented in any way, it is said to be entire. If it has sharp iG^iYi, iiointing Figs. 159 to 161.— Various forms of foliage-leaves. 118 ELEMENTS OP STRUCTURAL BOTAKY. in the direction of the apex, it is serrate, and will be coarsely or finely serrate, according to the size of the teeth. Sometimes the edges of large teeth are themselves finely serrated, and in that case the leaf is doubly serrate (Fig. 162). If the teeth point outwards, that is, if the two edges of each tooth are of the same length, the leaf is dentate; but if the teeth, instead of being sharp, are rounded, the leaf is crenate (Fig. 163). The term wavy explains 179. Base. There are two or three peculiar modifica- tions of the bases of simple sessile leaves which are of considerable importance in distinguishing plants. Some- times a pair of lobes project backwards and cohere on the other side of the stem, so that the stem appears to pass through the leaf. This is the case in our common Bellwort, the leaves of which are accordingly described as perfoliate (Fig. 164). Sometimes two opposite sessile leaves grow together at the base and clasp the stem, as in the upper leaves of Honeysuckle, in the Triosteum, and in one of our species of Eupatorium. Such leaves are said to be connate or connate-perfoliate (Fig. 165). In one of our Everlastings the margin Fig. 164. of the leaf is continued on each side below the point of insertion, and the lobes grow fast to the sides of the stem, giving rise to what is called the decurrent form (Fig. 166). Figs. 162 to 164.— Various forms of foliage- leaves. Fig. 163. FOLIAGE- LEAVES. 119 The terms by which simple leaves are descnbed are applicable also to the leaflets of compound leaves, to the sepals and petals of flowers, and, in short, to any flat forms. Fig. 165. Fig. 166. 180. We have already explained that compound leaves are of two forms, pinnate and palmate. In the former the leaflets are arranged on each side of the mid-rib. There may be a leaflet at the end, in which case the leaf is odd-pinnate; or the terminal leaflet may be wanting, and then the leaf is Fig. 167. abruptly pinnate. In the Pea, thr> leaf is pinnate and terminates in a tendril (Fig. 13.^). Very frequently the primary divisions of a pinnate leaf are themselves pinnate, and the whole leaf is then twice-pinnate (Fig. 167). If Figs. 165 to 167.— Various forms of foliage-lei»'"'H. t f-M it III* w. ' ? 'i s ii'i 120 ELEMENTS OP STRUCTURAL BOTANV. the sub-division is continued through another stage, the leaf is thrice-pinnate^ and so on. Sometimes, as in the leaves of the Tomato, very small leaflets are found between f^vyj*^ the larger ones, and this form is described as interruptedly pinnate (Fig. 168). In the palmate or digitate forms the leaflets spread out from the end of the petiole, and, in describing them, it is usual to mention the number of divisions. If there are three, the leaf is tri-foliolate ; if there are five, it is quinque-foliolate. 181. In the examination of the Mallow we found a couple of small leaf-like attachments on the petiole of each leaf, just at the junction with the stem. To these the name stipules was given. Leaves which have not these appendages are exstipulate. 182. Besides the characters of leaves mentioned above, there re- main a few others to be noticed. With regard to their surface, leaves present every gradation from perfect smoothness, as in Winter- green, to ' extreme roughness or *^" ^ ' wooUiness, as in the Mullein. If hairs are entirely absent. Fig. 168. Fig. 168.— Interruptedly pinnate leaf. Fig. 169.— Leaf of Pitcher-Plant. FOTTAOE-IiEAVES. J 21 the leaf is glabrous ; if present, the degree of hairiness is described by an appropriate adverb ; if the leaf is com- pletely covered, it is villous or villose ; and if the hairs are on the margin only, as in our Clintonia, it is ciliate. Some leaves, like those of the Cabbage, have a kind of bloom on the surface, which may be rubbed off with the fingers ; this condition is described as glaucous. 183. A few plants have anomalOUS leaves. Those of the Onion are filiform. The Pitcher-Plant of our northern swamps has very curious leaves (Fig. 169), apparently formed by the turning in and cohesion of the outer edges of an ordinary leaf so as to form a tube, closed except at the top, and armed on the inner surface with bristles pointing towards the base of the leaf. 184. Finally, as leaves present an almost infinite variety in their forms, it will often be necessary in describing them to combine the terms explained above. For instance, a leaf may not be exactly linear, nor exactly lance-shaped, but may approximate to both forms. In such a case the leaf is described as lance-linear, and so with other forms. The following form of schedule may be used with advantage in writing out descriptions of leaves. Two leaves — one of Maple and one of Sweet Brier — are described by way of illustration. If a leaf is compound, the particulars as to outline, margin, apex, base, and surface will have reference to the leaflets. The exercise-book prepared to accompany this work contains a supply of blank schedules for leaf-description, with space for drawings. fii. 'I I Mi 122 ELEMENTS OF STRUt^URAL BOTAMT. LEAF SCHEDULE. Leaf of Maple. Sweet Brier. 1. Position. Cauline. Caul'ue. 2. Arrangement. Opposite. Alternate. 3, Insertion. Petiolate. Petiolate. 4. Stipulation. Exstipulate. Stipulate. 5. Division. Simple. Odd pinnate, 7 leaflets. 6. Venation. Palmate. 7. Outline. Rounditih or oval. 8. Margin. Deeply lobed. Doubly serrate. 9. Apex. Pointed. Acute. 10. Base. Cordate. Hardly indented. 11. Surface. Glabrous above ; whitish beneath. Downy above ; covered with glands beneath. INFLORESCENCB. 123 CHAPTER XVIII. MORPHOLOGY OF FLOWER-LEAVES — INFLORESCENCE — THE CALYX — THE COROLLA — THE STAMENS — THE PISTIL THE FRUIT — THE SEED — GERMINATION. 185. From an examination of the various forms presented by foliage-leaves, we proceed now to those of the floral ones, and we shall first consider the chief modifications in the arrangement of flowers as a whole^ to which the term inflorescence is applied. As the organs of which flowers are made up are strictly leaf-forms, the special stalks upon which they are produced (peduncles and pedicels) are true branches, and their development is in strict accordance with the principles enunciated in sections 141-144. As there stated, the almost invariable mode of branching in phan- erogams is monopodial, either after the hotryose type or after the cymose type. So inflorescence is found to proceed upon one or other of these two plans. 186. To understand these let us recur to our specimens of Shepherd's Purse and Buttercup. You wiM remember that in the former the peduncle continues to lengthen as long as the summer lasts, and new flowers continue to be produced at the upper end. Observe, however, that every one of the flowers is produced on the side of the stem, that as the stem lengthens new lateral buds appear, and that there is no flower on the end of the stem. The production of the flowering branches (pedicels) and the continuation of the main axis are, in fact, exactly analogous to the growth of the Spruce, as explained in Miction 142. i ' i ! i ^: IS 124 ELEMENTS OP STRUCTURAL BOTANY. You will easily understand, then, that the production of flowers in such a plant is only limited by the close of the season or by the exhaustion of the plant. Such inflorescence is, therefore, called indefinite, or inde- terminate, or axillary. It is sometimes also called centripetal^ because if the flowers happen to be in a close cluster, as are the upper ones in Shepherd's Purse, the order of development is from the outside toioards the centre. 187. If you now look at your Buttercup you will b« at once struck with the difference of plan exhibited. The main axis or stem has a /tower on the end of it, and its further growth is therefore checked. And so, in like manner, from the top downwards, the growth of the branches is checked by the production of flowers at their extremities. The mode of inflorescence here displayed is definite, or determinate, or terminal. It is also called centrifugal, because the development of the flowers is the reverse of that exhibited in the first mode. The upper, or, in the case of close clusters, the central, flowers open first. 188. In either mode the flowers are said to be solitary, if (1) single flowers are produced in the xils of the ordinary foliage-leaves (botryose), or (2) if a single flower terminates the stem, as in Tulip (terminal). 189. if indeterminate or botryose inflores- cence there are several varieties. In Shepherd's Purse we have an instance of the raceme, which may be described as a cluster in which each flower is supported on a lateral pedicel of its own, usually in the axil of a bract. If the pedicels are absent and the flowers consequently INFLORESCENCE. 125 sessile in the axils, the cluster becomes a spike^ of which the common Plantain and the Mullein furnish good examples. The catkins of the Willow (Figs. 68 and 69) and Birch and the spadix of the Indian Turnip (Figs. 96 and 97) are also spikes, the former having scaly- bracts and the latter a fleshy axis. If you suppose the Fig. 170. Fig. 171. internodes of a spike to be suppressed so that the flowers are densely crowded, you will have a heady of which Clover and Button-bush supply instances. If the lower pedicels of a raceme are considerably longer than the Fig. 170.— Plan of the simple corymb. Fig. 171.— Cotnpoutid raceme. (Gray.) 1 r I ' ' : li P f. i ■ C- r i 126 ELEMENTS OP STRUCTURAL BOTANY. upper ones, so that all the blossoms are nearly on the same level, the cluster is a corymb (Fig. 170). If the flowers in a head were elevated on separate pedicels of the same length, radiating like the ribs of an umbrella, we should have an umbel, of which the flowers of Geranium and Parsnip (Fig. 51) are examples. A raceme will be compound (Fig. 171) if, instead of a solitary flower, there is a raceme in each axil, ?ind a similar remark will apply in the case of the spike, the corymb, and the umbel. 190. The inflorescence of most Grasses is what is called a panicle. This is a compound form, and is If' f h 1 FL'. 172. usually a kind of raceme having its primary divisions branched in some irregular manner. 191. Of determinate inflorescence the chief modification is the ci/nw. This is a rather flat-topped Fiy. 172.— A cyme. (Gray.) INFLORESCENCE. 127 cluster, having something the appearance of a compound corymb, but easily distinguished by tins peculiarity : that the central blossom opens firsts then those at the ends of the first set of branches of the cluster, then those on the secondary branches, and so on until the outer buds are reached. The Elder, Dogwood, and St. John's Wort furnish good examples of the cymose structure. Fig. 172 shows a loose, open cyme. Helicoid and Scorpioid cymes have already been described in section 144. 192. Besides the two distinct modes of inflorescence just described, forms are met with which exhibit the peculiarities. of both modes. For example, the flower- cluster of the Lilac is botryose or racemose as to the production of its primary branches, but the development of the flowers on the branches is according to the cymose type. On the other hand it sometimes happens, in many of the Composites for example, that the primary branches are cymose while the secondary are botryose. In the Lilac and the Horse-Chestnut the compact mixed cluster is called a t/it/rse. Panicles, also, instead of being altogether botryose, may be of a similar mixed character. 193. In many plants of the Mint Family the flowers appear to form dense whorls at intervals about the stem. Each of these whorls, when analysed, is found to consist of two cymose clusters on opposite sides of the stem. Such whorls are, therefore, mixed, and are often spoken of as verticillasters.' 194. It has already been pointed out that cauline lea\ 3s tend to diminish in size towards the upper part of th>3 steir where the flowers are found. Such reduced 128 ELEMENTS OF STRUCTURAL BOTANY. . i^ leaves, containing flowers in their axils, are called bracts. In the case of compound flower-clusters this term is limited to the leaves on the peduncle or main stem, the term bradlet being then applied to those occurring on the pedicels or subordinate stems. In the case of the umbel and the head^ it generally happens that a circle of bracts surrounds the base of the cluster. They are then called, collectively, an involucre, and in the case of compound clusters a circle of bractlets is called an involucel. Bracts are often so minute as to be reduced to mere scales. On the other hand they are occasionally very conspicuous and showy, as, for instance, in the four white bracts resembling a flower in the^ Bunchberry. From our definition it will be evident, also, that the sjMthe surrounding the spadix in Indian Turnip is merely a bract. 195. Floral symmetry. Before dealing with the mor- phology of the separate leaf-forms which go to make up the flower, a few words are necessary in regard to the relations of the different sets of floral organs, both as to number and as to position. The leaves which constitute the flower are arranged about the axis either in whorls, when the flowers are said to be cyclic; or in spirals, after the manner of most foliage-leaves, in which case the flowers are acyclic. Occasionally the outer sets (the perianth) are in whorls, while the stamens are spirally arranged ; tlien the flowers are said to be Ikemicyclic. The spiral arrangement prevails, as a rule, where the floral organs are very numerous, as, for instance, in the Water Lily and in Buttercup ; though Columbine, with very numerous stamens, has cyclic flowers. FLORAL DIAGRAMS. 129 196. In cyclic flowers, whilst there is usually one whorl each of sepals, petals, and carpels, there are not unfrequently two whorls of stamens. If each whorl is made up of the same number of members the flower is isomerous, and will, at the same time, be monomerous, dimerous, trimerous, tetramerous, or pentamerous, accord- ing as each whorl contains one, two, three, four, or five members. If the numbers of the members in the whorls do not correspond, the flowers are heteromerous. 197. The relations of the whorls to each other in any particular case may be very conveniently exhibited by a diagram. Fig. 173, for example, shows the plan of a Lily. The dot at the top of the figure represents the position of the axis of the plant, and should always be shown in a floral diagram. The side of the flower Fig. 173. towards the stem is the posterior 3ide, the opposite one being anterior, and a plane passing through the centre of the flower and also through the stem or axis is called the median j^^ane. We have in the flower of the Lily an outer whorl of three members ; then alternately with these (and this is the usual plan in cyclic flowers) a second whorl of three members ; then the outer whorl of stamens, also three in number ; then the three inner stamens ; and, finally, the three carpels. 198. The composition of this flower may also be expressed by a formula, as follows : Ky, C;j, A.j i.;j, G(^), where K stands for calyx, C for corolla, A for anthers, G ^or gynoecium. The brackets enclosing the figure Fig. 173.— Diagiam of Lily flower. (Prantl.) L I lir. '..! II ■ fi 130 (ELEMENTS OF STRUCTURAL BOTANY. which follows G show the carpels to be united, and the placing of the figure above the short line indicates that the ovary is superior ; if inferior, the figure would be • written below the line. Fig. 174 shows the plan of a Grass-flower. Here parts which are suppressed, and the position of which can in general be easily inferred from that of those which are present, are represented by dota The Fiff. 174. formula would be : Kq, C2, A3+0, G(^\ 199. The gynoeciura is very frequently made up of fewer members (carpels) than the other whorls, and in all such cases the position of the carpels is more or less irregular. 200. Fig. 175 gives the plan of Shepherd's Purse. This shows the four sepals to be in two whorls of two sepals each ; the four petals, however, are arranged alternately with the four sepals, as if the latter were all in one whorl ; the position of the stamens indicates that the tivo posterior ones, as well as the two anterior ones, occupy the place of single stamens, and have, therefore, probably arisen from the early division of single stamens into pairs. The ^^^' ^^^• formula would be : K2+2> C4, A2+23, G(^); the expression 2^^ indicating the reduplication of the inner stamens. 201. If there is no clear distinction between the calyx and corolla, *'ie letter P (for perianth) may be used to include both ; and, finally, if the members of any whorl Fig. 174. —Diagram of a Orass-flower. (Prantl.) Fig. 175.— Diagram of flower of Shepherd'* Purse. (PnmtL) -*" THE CALYX. 131 stand opposite those of the one exterior to it, a vertical line may be placed between the symbols, thus : C5 | Ag. 202. Other methods of indicating symbolically the relations of the parts of the flower are in vogue ; the one just given is recommended by Prantl, and is sufficiently convenient. 203. It has already been mentioned that flowers are said to be irregular when the members of any whorl are of different sizes or shapes, as, for example, in the Pea ; and regular, when the opposite is true. Fig. 173 repre- sents one of these regular flowers. A moment's reflection will show that any line whatever drawn across the centre of this diagram will divide it into two exactly similar halves. The term actinomorphicy as well as " regular," is applied to all such flowers. Flowers, on the other hand, which can be cut symmetrically in one vertical plane only are zygomorphic. 204. In this book, as in most English books, the term " symmetrical " is employed to indicate that the whorls consist of the same number of members each, and it is, in fact, the same in meaning as " isomerous." The later German botanists define a symmetrical flower as "one which can be divided vertically into two halves resembling each other like an objef^t and its reflected image." We phall now proceed to consider in detail the variations in form assumed by the floral organs individually. 205. The Calyx. As you are now well aware, this term is applied to the outer circle of floral leaves. These are usually green, but not necessarily so ; in some Exogens, and in nearly all Endogens, they are of some other colour. Each division of a calyx is called a sepal, and if the sepals i n I 132 ^' ELEMENTS OP STRUCTURAL BOTANY. » V i ' III §1 •1 •■-I are entirely distinct from each other, the calyx is poty- sepalous ; if they are united in any degree, it is gamo- sepalous. A calyx is regular or irregular according as the petals are of the same or different shape and size. 206. In a gamosepalous calyx, if the sepals are not united to tlie very top, the free portions are known as calyx-teeth^ or, taken collectively, as the limb of the calyx. The united portion, especially if long, as in Willow-herb, is called the calyx-tube^ and the entrance to the tube its throat. In many plants, particularly those of the Com- posite Family, the limb of the calyx consists merely of a circle of bristles or soft hairs, and is then described as pap)pose. In other cases the limb is quite inconspicuous, and so is said to be obsolete. A calyx which remains after the corolla has disappeared, as in Mallow (Fig. 31), is persistefit. If it disappears when the flower opens, as in our Bloodroot, it is caducous; and if it falls away with the corolla, it is deciduous. We must repeat here, that when calyx and corolla are not both present, the circle which is present is considered to be the calyx, whether green or not. 207. The Corolla. The calyx and corolla, taken together, are called the floral envelopes. When both envelopes are present, the corolla is the inner one ; it is usually, though not invariably, of some other colour than green. Each division of a corolla is called a petalf and the corolla is polypetalou^ when the petals are completely disconnected ; but garaopetalous if they are united in any degree, however slight. The ievm.^ regular and irregular ^ applied to the calyx, are applicable also to the corolla, and U^a terms used in the description of leaves are applicable THE COROLLA. 133 to petals. I , however, a petal is narrowed into a long and slender portion towards the base, that portion is known as the claWy whilst the broader upper part is called the Umh (Fig. 176). The leaf -terms are then applicable to the limb. 208. Gamopetalous corollas assume various forms, most of which are described bv terms Fiii. 176. easily understood. The forms assumed depend almost entirely on the shape of the petals which, when united, make up the corolla. If these, taken separately, are linear, and are united to the top, or nearly so, the corolla will be tubular (Fig. 177). If the petals are wedge-shaped, they will, by their union, produce a funnel-shaped corolla (Fig. 178). In the campamdate or hell- shaped form, the enlargement from base to sum- mit is more gradual. If the petals are narrowed Fig. m. abruptly into long claws, the union of the claws into a tube and the spreading of the limb at right angles to the tube will produce the salver-shaped form, as in Phlox (Fig. 179). The rotate corolla differs from this in having a very short tube. The corolla of the Potato is rotate. 209. The most important irregular gamopetalous corollas are the ligulatey which has been fully described in the ^' ' examination of the Dandelion, and the labiate^ of which we found an example in Catnip (Fig. 69). The corolla of Turtle-head (Fig. 180) is another Fig. 176.— Single petal of a Pink. Fig. 177.— Tubular corolla of a Honeysuckle. Fin;. 178.— Funnel-shaped corolla of Calystegia. ,5 ) 134 ELEMENTS OF STRUCTURAL BOTANY. example. When a labiate corolla presents a wide opening between the upper and lower lips, it is said to be ringent; if the opening is closed by an upward projection of the lower lip, as in Toadflax (Fig. 181), it is said to be personate, and the projection in this case is known as the palate. A good many corollas, such as those of Toadflax, Dicentra, Snapdragon, Columbine, and Violet, have protuberances or spurs at the base. In Violet one petal only is spurred ; in Columbine the whole five are so. Fig. 179. Fig. 18a Fig. 181. 210. Estivation. This is the term applied to the mode in which the sepals and petals are folded in the bud. In general, the members of a calyx or of a corolla overlap in the bud, or they do not. If they stand edge to edge, as in the calyx of Mallow, the aestivation is valvate. If there is overlapping, and one or more of the members have both edges covered, the aestivation is imbricate; and if each member has one edge covered and the other uncovered, as in the corolla of Mallow? Evening Primrose, Phlox, &c., it is then said to be con- volute. Gamopetalous corollas are frequently plaited in the bud, and the plaits may be convolute, as in Morning Glory. ^ ^1 I I I I r I - I _ .. 'I — r I " Fig. 179.— Salver-shaped corolla of Phlox. Fig. 180.— Labiate corolla of Turtle-head. Fig. 181.— Personate oorolla of Toadflax. t THE STAMENS. 135 211. The Stamens- As calyx and corolla are called collectively the floral envelopes, so stamens and pistil are spoken of collectively as the essential organs of the flower. The circle of stamens alone is sometimes called the andrcBcium. A complete stamen consists of a slender stalk known as the filament^ and one or more small sacs called collectively the anther. The filament, however, is not uncommonly absent, in which case the anther is sessile. As a general thing, the anther consists of two oblong cells with a sort of rib between them called the connective^ and that side of the anther which presents a distinctly grooved appearance is the face^ the opposite side being the back. Fig. 182. Fig. 183. Fig. 184. The filament is invariably attached to the connective, and may adhere through the entire length of the latter, in which case the anther is adnate (Fig. 182); or the base of the connective may rest on the end of the filament, a condition described as innate (Fig. 183); or the extremity of the filament may be attached to tlie middle of the back of the connective, so that the anther swings about : it is then said to be vei'satile (Fig. 184). In all these cases, if the face of the anther is turned towards the centre of the flower, it is said to be introrse ; if tuj'ned outwards, extrorse. Figs. 182, 183, 184,— Stamens showing adnate, innate, aod versatile attach- ments of the anther. 136 ELEMENTS OP STRUCTURAL BOTANY. :: r M The cells of anthers commonly open along their outer edges to discharge their pollen (Fig. 185). In most of the Heaths, however, the pollen is discharged through a minute aperture at the top of each cell (Fig. 186), and in our Blue Cohosh each cell is provided with a lid or valve near the top, which opens on a kind of hinge (Fig. 187). Occasionally, examples of barren or abortive stamens are met with, as the fifth stamen in Turtle Head and Pentstemon. These are filaments without anthers, and are known as staminodes. 212 Stamens may be either entirely distinct from each other — in which cise they are described as diandrous, pentandroiiSy odandrous, &c., according to their number (or, if more than twenty, as indefinite) — or /^ If they may be united in various ways. If 7 1 I I ^^^^^^ anthers are united in a circle, while I I I I the filaments are separate (Fig. 57), they ^^ If are said to be syngenesious ; but if the \\ filaments unite to form a tube, while the Figs. 185, 187. 186. aiithcrs remain distinct, thev are said to be monadcl2)hous (Fig. 32) ; if they are in two groups they are diadelphous (Fig. 37) ; if in three, triadelphous ; if in more than three, polyadelplious. 213. As to insertion, when stamens are inserted on the receptacle they are hypogijnoiis ; when borne on the calyx, perigynous ; when borne on the ovary, epigynous ; and if inserted on the corolla, epipetalous. They may, however, be borne even on the style, as in Orchis, and then they are described as gynandrous. 214. If the stamens are four in number, and in two . * — - Figs. 185, 186, 187.— Anthers exhibiting different modes of dehiscence. ■■■ THE PISTIL. 137 pairs of different lengths, they are said to be didnnamons (Fig. 60) ; if six in number, four long and two sliort, they are tet rod ynamous (Fig. 28) ; and, finally, if the stamens are hidden in the tube of a gamopetalous corolla they are said to be included^ but if they protrude beyond the tube they are exserted (Fig. 177). 215. The Pistil. This is the name given to the central organ of the flower. It is sometimes also called the gynoecium. As in the case of the stamens, the structure of the pistil must be regarded as a modification of the structure of leaves generally. The pistil may be formed by the folding of a single carpellary leaf, as in the Bean (Fig. 188), in which case it is simple; or it may consist of a number of carpels, eitliei entirely separate from each other or united together in various ways, in which case it is compound. By some botanists, however, the term compound is restricted to the case of Fig. i88. united carpels. If the carpels are entirely distinct, as in Buttercup, the pistil is apocarpous ; if they are united in any degree, it. is syncarpous. A pistil of one carpel is monocarpellary ; of two, dicarpellary ; and so on, to polycariJellary. 216. The terms inferior and superior, as applied to the pistil, describe its situation upon the axis relative to that of the calyx, corolla, and stamens. It will be remembered that the end of the peduncle is usually enlarged, forming what is called the torus or receptacle. Usually the receptacle is a little higher in the centre Fig. 188.— Legume of the Bean. IE 1 -^ 1 ; U.UM 138 ELEMEI^tS OF STRtJCTUtlAL BOTANV. than at its margin, and as the gynoecium occupies this central part, its position is above that of the other floral leaves, as shown in Fig. 189. Here the pistil is superior, and the stamens and petals hypogynous. But frequently the outer part of the receptacle grows more vigorously than the centre, forming, in fact, a cup with the pistil in the bottom of it, and the stamens and petals around Fig. 189. Fig. 190. Fig. 191. its margin (Fig. 190). In this case the pistil may be described as half-inferior, and the stamens and petals as perigynous. Often the cup-shaped receptacle grows fast to the ovary all round. In other cases, the carpels, instead of being developed from the bottom of the cup, spring from the margin, thus forming a roof-like disk, around the edge of which the stamens are attached (Fig. 191). Here the stamens are epigynous, and the ovary is truly inferior. Other cases of epigyny and perigyny arise from the adnation (growing together) of the floral whorls without exceptional development of the Figs. 189, 190, 191.— Diagrams ilhistratiriK hypogynous (H), perigynous (P), and epigynous {K) flowers; a, axis; /r, calyx ; c, corolla; s, stamens; / carpels ; n, stigma ; sk, ovule. (Prantl.> THE PISTIL. 139 receptacle. The cases of the Rose, Cherry, and Apple have already been referred to (Chapter VI.). 217. In our examination of the Marsh Marigold (Figs. 24 and 25) we found an apocarpous pistil of several carpels. We found also that each carpel contained a number of seeds, and that in every case the seeds were attached to that edge of the carpel which was turned towards the centre of the flower ^ and that, as the carpels ripened, they invariably split open along that edge, but not along the other, so that the carpel when opened out presented the appearance of a leaf with seeds attached to the margins. The inner edge of a simple carpel, to which the seeds are thus attached, is called the ventral suture, the opposite edge, corresponding to the mid-rib of a leaf, being the dorsal suture. 218. If we suppose a number of simple carpels to approach each other and unite in the centre of a flower, it is evident that the pistil so formed would contain as many cells as there were carpels, the cells being separated from each other by a double wall, and that the seeds would be found ar^^anged about the centre or axis of the pistil ; and this is the actual state of things in the Tulip, whose pistil is formed by the union of three carpels. When the pistil ripens, the double walls separating the cells split asunder. To these separating walls the name dissepiment or partition is given. 219. The cells are technically known as loculi. An ovary with one cell i^ unilocular ; with two, hilocidar ; with several, multilocular. Between the unilocular and multilocular forms there are all shades of gradation. In some cases, as, for example, in Saxifrage, the carpels ^f r' I ' v 140 ELEMENTS OF STRUCTURAL BOTANY. f are united below but separate above. Sometimes, also, false partitions are formed across the loculi in the course of growth. In the Mints, for instance, there are &\ first but two loculi ; eventually, however, there are four, which completely separate at the time of ripening. 220. But it often happens that though several carpeU unite to form a compound pistil, there is but 07ie cell in the ovary. This is because the separ- ate carpellary leaves have not been folded before uniting, but have been joined edge to edge, or rather with Fig. 193. Fig. 192. their edges slightly turned inwards. In these cases the seeds cannot, of course, be in the centre of the ovary, but will be found on the loalls^ at the junction of the carpels (Figs. 192 and 193). In some plants the ovary is one-celled, and the seeds are arranged round a column which rises from the bottom of the cell (Figs. 194 and 195). This case is explained by the early obliteration of the partitions, which must at first have met in the centre of the cell. Special cases, how- ever, are found in which no trace of parti- tions has been observed, and these must consequently be explained by the actual '^* ' '^ upward growth of the axis into the centre of the ovary. 221. In all cases the line or projection to which the seeds are attached is called the placenta^ and the term placentation has reference to the manner in which the placentas are arranged. In the simple pistil the placentation is marcjinal or sutural. In the syncarpous Figs. 192, 193.— Compound onri-colled ovary of Mignorx'tte. Figs. 194, 195.— Sections of ovary of a Piiik, ohowiug free central pla* ccntation. pis th PHYLLOME AND TRICHOME. 141 Q Fig. 196. Figs. 197, 19S. pistil, if the dissepiments meet in the centre of the ovary, thus dividing it into separate cells, the placentation is central or axile ; if the ovary is one-celled and bears the seeds on its walls, the placentation is 'parietal ; and if the seeds are attached to a central column it is free central. 222. Besides the union of the ovaries there may also be a union of the styles, and even of ohe stigmas. 223. A very exceptional pistil is found in plants of the Pine Family. Here the ovules, instead of being enclosed in an ovary, are usually simply attached to the irner surface of an open carpellary leaf or scale, the scales forming what is known as a cone (Figs. 196, 197, and 198). The plants of this family are hence called gymnospermous^ or naked-seeded. 224. Nectaries. This name is given to that part of a flower which has been specially formed for the secretion of honey. The nectaries need not, however, be looked upon as separate or independent organs. Sometimes they are to be found at the base of the petals, as in Buttercup ; sometimes at the base of the stamens, as in the Grape. Very commonly they are at the bottom of deep spurs formed on one or more divisions of the perianth, as in Violet, many Orchids, and in Columbine. 225. Phyllome and Trichome. To leaf-forms, whether ordinary foliage-leaves or those special modifioa bions which make up the flower — sepals, petals, stamens. Fig. 19fi.— Acone. Fig. 197.— Sitijjle scale showing position of the two seeds on the i*^ner face. Fig. 198.— One of the winged seeds removed. ih h ; i?i!l m 142 ELEMENTS OP STRUCTURAL BOTANY I i ' 'a J '! § and carpels — the general term phyllome is applicable. The characteristic of the phyllome is that it is a lateral outgrowth of the stem or its branches. 226. The term trichome, on the other hand, is applic- able to any hair-like appendage on the surface of the plant generally, whether of root, stem, or leaf. The conmionest form of trichome is the liair. The root hairs which generally clothe the surface of young roots are of great importance as absorbing agents. Each root-hair consists of a single, delicate, tube-like cell with extremely thin walls. Other hairs may consist of several such cells placed end to end. Others, again, may branch extensively. It sometimes happens that the terminal cell of a hair produces a gummy substance which comes away with the slightest touch. The sticky surfaces of many common plants are due to the presence of such hairs, which are then described as glandular. Gummy matters are also secreted by glands close to the surface of the plant. Peltate hairs are occasionally met with, as in the leaves of Shepherdia. They give a scurfy appearance to the surface upon which they grow. Then there are hairs which secrete odorous fluids, as, for example, those upon the surface of the Sweet Brier- These probably serve to attract insects. Stiiiging hairs are also common. They contain an irritating fluid. When the point of the hair pierces the skin it is broken off*, and the fluid then escapes into the wound. 227. Besides the trichome forms just mentioned, there are also bristles, formed from hairs by the gradual thick- ening and hardening of their walls, and p77c7i:/e6', such as those of Sweet Brier (Fig. 199), which consist of many THE FRUIT. 143 Fig. 200. Fig. 199. hard-walled woody cells closely packed together. That prickles are really trichomes is shown by the fact that when the bark is stripped off they come away along with it. Spines^ on the other hand (Fig. 200), are lateral outgrowths of the stem. They are, in fact, gener- ally stunted branches, and will be found to spring originally from the axils of leaves. Occasionally the petiole of a leaf is converted into a spine, which then becomes a true phyllome. Ovules are generally regarded as trichomes since they arise from the inner surface of the carpels. 228. The Fruit. In coming to the consideration of the fruit, you must for the present lay aside any popular ideas you may have acquired as to the meaning of this term. You will find that, in a strict botanical sense, many things are fruits which, in the language of common life, are not so designated. For instance, we hardly speak of a pumpkin or a cucumber as fruit, and yet they are clearly so, according to the botanist's definition of that term. A fruit may be defined to be the ripened pistil toyetlier ivith any other organ, such as the calyx or receptacle^ which may he adherent to it. This definition will, perhaps, be more clearly understood after a few speci- mens have been attentively examined. 229. For an example of the simplest kind of fruit let Fig. 199.— Prickles of Sweet Brier. Fig. 200.— Spinea of the Hawthorn. Hii ■ < i I I »- ' V 144 ELEMENTS OP STRUCTURAL BOTANY. ■1 I |;;^ us revert to our Buttercup. As the carpels ripen, the style and stigma are reduced to a mere point. On cutting open one of these carpels wlien fully ripe, we find it contains a single seed, not quite filling the cavity, but attaclied at one point to the wall of the latter. What you have to guard against, in this instance, is the mistake of considering the entire carpel to be merely a seed. It is a seed enveloped in an outer covering which we called tlie ovary in the early stages of the flower, but which, now that it is ripe, we shall call the pericaiy. This pericarp, with the seed which it contains, is the fruit. The principal difference between the fruit of Marsh Marigold and that of Buttercup .3 that, in the former, the pericarp envelopes several seeds, and, when ripe, splits open doimi one side. The fruit of Buttercup does not thus split open. Ill the Pea, again, the pericarp encloses several seeds, but sj^lits open along both margins. The fruits just mentioned all result from the ripening of apocarpous pistils, and they are consequently spoken of as apocarpous fruits. 230. In Willow-herb, you will recollect that the calyx- tube adheres to the whole surface of the ovary. The fruit in this case, then, must include the calyx. When the ovary ripens, it splits longitudinally into four pieces (Fig. 41), and, as the pistil vms sfjncarpous, so also is the fruit. 231. In the Peach, Plum, Cherry, and stone-fruits or drupes generally, the seed is enclosed in a hard shell called iiputamen. Outside the putamen is a thick layer of pulp, and outside this, enclosing the whole, is a skin- like covering. In these fruits all outside the seeds is the pericarp. In one respect these stone-fruits resemble tho THE FRUIT. 145 fruit of the Buttercup : they do not split open in onh'r io discharge their seeds. AH fruits having this peculiarity are said to be indehiscent, whilst tliose in which tlic pericarp opens, or separates into pieces, are dehiscent- 232. In the Apple (I'ig. 50) and Pear, the seeds are contained in five cells in the middle of the fruit, and these cells are surrounded by a lirni fleshy mass, which is mainly an enlargement of the calyx. In fact, the remains of the five calyx-teeth may be readily detected at the end of the apple opposite the stem. As in Willow-herb, the calyx is adherent to the ovary, and therefore calyx and ovary togetier constitute the pericarp. These Jleshij fruits, or pomes^ a> they are sometimes called, are of course indehiscent. 233. In the Currant, as in the Apple, you will find the remains of a calyx at the top, so that this fruit, too, is inferior, but the seeds, instead of being separated from the mass of the fruit by tough cartilaginous cell-walls, as in tlie Apple, lie imbedded in the soft, juicy pulp. Such a fruit as this is a herry. The Gooseberry and the Grape are other examples. The Pumpkin and other gourds are similar in structure to the berry ; but, besides the soft inner pulp, they have also a firm outer layer and a hard rind. The name pe^m is generally given to fruits of this sort. 234. A Raspberry or Blackberry (Fig. 201) proves, on examination, to be made up of a large number of juicy little drupes, aggregated Fig. 201. upon a central axis. It cannot, therefore, be a true berry^ but may be called an aggregated fruit. Fijj. 201.— Aggregated ruit of the Raspberry. i '\\ 146 ELEMENTS OP STRUCTURAL BOTANY. r Fig. 202. 235. A strawberry (Fig. 202) is a fruit consisting chiefly of a mass of pulp, having its surface dotted all over with little carpels /'achenes), similar to those of the Buttercup. The flesh of the Strawberry is simply an enlarged recep- tacle ; so that this fruit, also, is not a true berry. 236. The fruit of ^weet Brier (Fig. 45) consists of a red fleshy calyx, lined with a hollow receptacle which bears a number of achenes. This fruit is, therefore, analogous to that of the Strawberry. In the latter the achenes are on the outer surface of a raised receptacle, while in the former they are on the inner surface of a holloiv receptacle. When other parts of the flower are combined with the ovary in fruit, as in Apple, Kose, and Strawberry, the result is sometimes described as a pseudocarp, or spurious fruit. 237. The cone of the Pine (Fig. 116) is a fri-.it which differs in an important respect from all those yet mentioned, inasmuch as it is the product, not of a single flower, but of as many flowers as there are scales. It may, therefore, be called a collective or multiple fruit. The Pine Apple is another instance of the same thing. 238. Of dehiscent fruits there are some varieties which receive special names. The fruit of the Pea or Bean (Fig. 188), whose pericarp splits open along both margins, is called a legume; that of Marsh Marigold (Fig. 25), which opens down one side only, is a follicle. Both oi these are apocarpous. " ■ — ■ ■ > Fig. 202.— Section of a Strawberrv. l-HE FRUIT. 147 239. Any syncarpous fruit having a dry dehiscent pericarp is called a capsule. The dehiscence of syncarpous or polycarpellary fruits is of several kinds. If the rupture takes jilace along the partitions the fruit will be split up into its original carpels ; this form of dehiscence is seiMcidal (Fig. 203). But the dehiscence may take place along the dorsal suture of each carpel, half- way between the partitions, so that the opening is into the loculus ; this ^ig. 203. mode is known as loculicidal (Fig. 204). Or again, the valves (separate pieces of the pericarp) may fall away, leaving the partitions standing ; this dehiscence is septifragal (Fig. 205). 240. A long and slender capsule having two cells separated by a membranous partition bearing the seed, and from which, wlien ripe, Fig. 204. the valves fall away on each side, is called a silique (Fig. 206). If, as in Shepherd's Purse (Fig. 29), the capsule is short and broad, it is called a silicle. If the capsule opens horizontally^ so that the top comes off like a lid, as in Purslane Fig. 205. (Fig. 207), it h^ pyxis. 241. Any dry, one-seeded, indehiscent fruit is called an ichene, of which the fruit of Buttercup (Fig. 14) is an Figs. 203, 204, 205.— Diagrams illustrating septicidal, loculicidal, and septi- fragal dehiscence a ij i i i I i 1 !•• (SI ii \ 148 ELEMENTS OP STRUCTURAL BOTANY. Fij?. 20(). instance. example. In Wheat the fruit differs from that of Buttercup in having a closely fitting and adherent pericarp. Such a fruit is called a carffopsis or grain. A nut is usually syncarpous, with a hard, dry pericarp. A vdnrjed fruit, such as that of the Maple (Fig. 208), is called a samara or key. 242. A fruit which splits up when ripe into several one-seeded pieces is called a schizocarp. The sumara of the Maple is a good example ; also the fruit of Catnip, which splits up at maturity into four one-seeded portions. The fruit of Mallow is another common ^'^•^^^" The separate portions in these cases are called 7Hericarps. In some le^ uminous plants the pod breaks up transversely into one- seeded portions, giving rise to the form called a loment. 243. A special schizocarp is that of Umbelliferous plants (Fig. 209). Here the Fig. 208. fruit splits into two mericarps, each attached, however, by a fibre to the axis. Such a fruit Fig. 209. is called a cremocarp. 244. The Seed. The seed has already been described as the fertilized ovule. During the formation of the carpels, the ovules arise as outgrowths from the inner surface of the ovary, mostly, as has been pointed out, upon the mavfjins of the carpellary leaves, but occasion- ally also upon the surface generally, At first the ovule Fig. 206.— Silicle of Stock. Fig. 207. -Pyxis of Purslane. Fig. 208.— Samara of Maple. Fig. 200.— Cremocarp of an Umbellifer ; a, the fibre attaching the mericarp to the axis. (Thome. ) THE SEED. T49 is p simple, soft mass with no indication whatever of the covering so manifest in ripe seeds of all kinds. Very soon, however, after the appearance of tlie body of the ovule, a circular ridge is developed upon it, and this gradually extends upwards over the surface so as to form a coat, which at length entirely covers it except at the very apex, where a minute opening is left. Very commonly, but not always, a second coat is developed exactly in the same manner, outside the first, and an opening is left in tliis coat also, precisely over the other. This minute passage through both coats to the ovule body has already been named the micropyh. The two coats are known as the }>rimine (generally, though not always, applied to the outer) and the spcuncline, and the central body is the nucleus. 245. If the ovule appears to arise directly from the placenta without the intervention of a stalk, it ••-; sessile ; but if a stalk is present, this is known as the funiculus. In the accompanying diagram (Fig. 210) whicli represents a section of the complete ovule, k is the nucleus ; ai, the primine ; m, the secundinc ; ?/?, the micropyle ; /, the funiculus. The point (c) where the two coats and the nucleus are blended together is called the chalaza. The portion of the nucleus marked em is the cavity called the embryo-sac, already referred to in Chapter II. 246. It must now be pointed out that though the ovules at the commencement of their growth are straight, as in the diagram just described, yet they do not commonly remain so. Very often the ovule l)ends over so as to appear completely inverted, in which case the funiculus grows fast to one side of the primine, becoming completely fused IV ! \-i: I 160 ELEMENTS OF STRUCTURAL BOTANt. with it, and forming what is then called the raphe. Fiff, 21] represents this condition, r being the raphe, s the chalaza, and the other letters corresponding to those in Fig. 210. Sometimes the curving of the ovule upon itself is not carried to this extreme, and an intermediate form is presented, as in Fig. 212. m IV Fig. 210. Fig. 211. If the ovule remains straight it is said to be ortlwtro- pous ; if completely inverted, anatropous ; if half bent over, camjrylotropous. 247. Pollination. The process of fertilization, by which the ovule is converted into the seed, has been briefly described in Chapter II. A few words may be added here upon pollination — the process of supplying pollen to the stigma. In very many flowers which have both stamens and pistil (and hence called hermaphrodite)^ the process is very simple. Either the anthers and stigma are so close together that the pollen cannot fail to be deposited upon the stigma immediately upon the opening of the anther, or the stigma is upon a lower level, so that the pollen drops upon it, or, in special cases, as in Figs. 210, 211, 212.— Diagrams of orthotropous, anatropous, and campylo- tropoua ovules. (Prantl.) POLLINATION 151 Impatiens and Wood Sorrel, besides the ordinary lar^e flowers, there are special small ones (known as cleistoga- •r*ioi!s flowers) whose floral enveloites do not open, thus "ompelling self-fertilization. ]>ut it is well established that in a vast number of cases the ovules in any given hower have to depend for fertilization upon the pollen of some other flower. Nature seems to have provided against self-fertilization by various contrivances. Some- times the relative positions of the antlurs and the stigma in the same flower are such as to render it impossible. Sometimes the pollen comes to maturity and is shed from the anthers before the stigma is in a suitable condition to receive it ; whilst, on the other hand, the stigma is often developed first and has withered before the opening of the anthers. (Flowers showing these peculiarities are said to be dichogamom.) When for any reason cross- fertilization has become a necessity, the conveyance of the pollen from one flower to another is ensured in various ways. When the flowers are inconspicuous, as in Grasses, the wind is the great agent, and flowers so fertilized are said to be anemophilous. In other cases the flowers, either by their brightness or their odour, attract insects in quest of honey, and these then become the carriers of the pollen. Flowers of this sort are said to be ento?nophilous, and are usually so constructed as to the situation of their honey receptacles, and the relative position of anthers and stigma, as to ensure the transfer of the pollen from the anther of one flower to its destination upon the stigma of another. The case of the Orchids has already been referred to in section 92. 248. After fertilization, the embryo, or young plantlet, as exhibited in the seed, begins its growth in that end of H' %■' 'il 152 ELEMENTS OP STRUCTURAL BOTANY. the embryo-sac which is next the raicropyle, and about, the same time, in the other end of the embryo-sac, tnero begins a deposit of matter intended for the nourishment of the embryo during the germination of the seed. This deposit has been already referred to under the name of albumen. It is also known as endosperm. As the embryo developes, this endosperm or albumen may be completely absorbed by it, so that at maturity the embryo will occupy the whole space within the seed-coats, "^ in the Bean. In this case the seed is exalbuminous. In ooher cases, as in Indian Corn, the endosperm remains as a distinct mass with the embryo embedded in it, or sometimes wrapped round it. Seeds of this kind are albuminous. Rarely this nourishing material is deposited outside the embryo- sac, in the body of the ovule. It is then known as p&risperm. 249. The ripened seed presents very different aspects in different plants. It may be resolved, however, into the nucleus and the integument (the spermoderm of some botanists). The former is made up of the embryo, together with the endosperm or perisperm, if present, while the latter consists of two layers : an outer, known as the testa^ c*nd an inner, the tegmeti. The scar showing where the seed has been attached to the placenta is called the hilum ; it is very distinct in the Bean. 250. Besides the integument just mentioned, occasionally an additional outer coat is formed, to which the term aril is applied. The fleshy red covering of the seed in our Ground Hemlock is a good example. 251. The seeds of Willow-herb, Milkweed, and many otner plants are furnished with tufts of hair-like bristles ^ ^ GERMINATION. 153 which facilitate their dispersion bj^ the wind. These tufts grow from the testa of the seed, and are not to be confounded with the pappus of the Thistle, Dandelion, 3 part ot a plant where growth is actually going on — say the point of a new rootlet. If our section is taken near enough to the point we shall fret cells which have just been formed. Such a ^-s— Fig. 217. section is very well shown in Fig. 218. Here the cells are seen to be completely filled with liquid having a F'xff. 215.— CellH from leaf of a Moss containing protoplasm and chlorophyll- granules. fig. 216.— Hair from Petunia leaf. Fig. 217.— Hairs from Geranium leaf. Fi' . 215. Fi<' 216. THE CELL. 159 granular appearance, and in the centre of each a rounded denser portion may be made out, each of these again enclosing one or more smaller bodies. This liquid which thus fills the newly-formed cells is cBWedjirotopiasni; the large rounded central mass is the nucleus, consist- ing of denser protoplasm, and the smaller enclosed masses are the nucleoli. Now let us consider Fig. 219. This is a representation of a section of the same rootlet, taken a little farther back from the point, so that the cells now in view are a little older than the first ones. They are manifestly larger ; that is to say, they have grown. The nucleus and the nucleoli can still be made out in some of thern, but the protoplasm no longer entirely fills the cell. There are now transparent spaces {vacuoles) which are filled with water, and between these the protoplasm is seen in the form of strings or bands, as well as lining the cell. pijr. 219. The water has been absorbed through the cell -wall, and after saturating the protoplasm the excess has formed the vacuoles. big. 218.— Young cells filled with protoplasm (/>) ; b, cell wall ; h, nucleus : kkf nucleolus. (Sachs ) f^ig. 219.— Cells a little older, exhibiting vacuoles («). (Sachs.) |: '! V. ■i m , i^' ii' 160 ELEMENTS OP STRUCTURAL BOTANY. Fig. 220 shows some cells from the same rootlet taken •till farther back. It is clear that the change observed n Fig. 219 has been carried to a still greater extent. In some of these cells the proto- plasm is restricted to the lining of the cell and the nucleus. iiil I , A is now to be observed that ^ rotoplasm is the es- sential part V. very living cell Through its agency all the vital processes of the plant are carried on. Every cell of every plant at some time or other contains this substance, and when at length it disappears the cells which are deprived of it no ^^ longer take any active part in the growth of the plant, but serve merely mechanical purposes, such as that of support or conduction, and are in that stage of their history filled usually with air or water. The pith of the Elder is made up of such dead cells, nj= as is also the greater part of the f wood and bark and older parts generally of all plants. 262. The most marked feature of the living protoplasm its act lint If. We may observe this property by FJjr. 220. IS Fig'. 220. — Cells still older; h^ the wall; s, vacuoles; p, protoplasm; fr, nucleus ; xy, swelling of nucleus caused b^ water used in preparation of tb$ eection. (Sachs.) THE CELL. 161 m examining plant-hairs and other parts under high powers of the microscope, when it will be seen that there are movements of two kinds. The whole mass of protoplasm has a rotary motion, sliding upon the cell-wall, down- wards on one side and upwards on the other. This is the maas-movement. Also, currents may be traced passing across the protoplasm in different directions. This is the streaming-movement. In some of the very lowest plants, where there is no cell-wall, and the whole is a mass of naked protopi sp these movements may be observed more readily b' jau-e they are less restricted. 263. There is some doubt as to the exact chemical composition of protoplasm. It is, however, a very jmplex substance belonging to a group of bodies known as albuminoids^ of which nitrogen is an important con- stituent. The consistence of protoplasm depends upon the amount of water it contains. In dry seeds, for example, it is tough and hard, but when the same seeds are soaked in water it becomes partially liquid. 264. Forms of Cells. As cells become older they tend as a rule to change their form, though sometimes we find them differing but little from their original conformation. Com- monly a cell grows more rapidly in some one direction, thus giving rise to long forms, as is ^»e- 221. the case in stems generally, and in the petioles and veins of leaves, the superior toughness and strength of which i'ig. 221.— Prosenchyma oi the wood, (Gray.) i f. litl; 162 ELEMENTS OP STRUCTURAL BOTANY. i M ill: are due to the lengthening and hardening of the cells of which they are composed (Fig 221), 265. The Oell-wall. In the portions of plants just selected for microscopic examination we have seen that the protoplasm is in every instance bounded by a wall. It has been ascertained that the wall is a chemical com- ^jound of carbon, hydrogen, and oxygen, and to this compound the name cellulose has been given. We have said that the protoplasm is the active principle through the agency of which all the vital processes of the plant are carried on. It contains at some time or other every constituent of the plant. The cell-wall is itself, therefore, a product or secretion of the protoplasm, and is at first an extremely thin film, which, however, gradually increases in thickness by the addition of further material. This new material is deposited hettoeen the molecules of the original film, and so extends not only the surface of the wall, but, by deeper deposits, the thickness also. This process of acquisition of new oaaterial is known as intussusception. 266. As the wall between two cells increases in thick- ness, a distinct middle layer is discernible in it, known as the middle lamella. This portion of the common wall is different in chemical composition from the rest, so that it may, under proper treatment, be dissolved and the cells thereby separated. 267. It is in the earlier stages of theit history, while the walls are comparatively thin, thnt the cells possess the greatest activity. By these alone is carried on the process of growth, which consists in the multiplication and enlargement of cells. THE CELL 163 ;%1 Fig. 222. annular, 268. It is seldom the case that the wall is thickened uniformly. Often numerous round thin spots are left, so that the cell has a dotted appearance (Fig. 222). When the thin spots in adjacent cells are contiguous, as they commonly are, a ready means of inter- communicatior is afforded. Sometimes the spots, instead of bein^: round, are oblong, so that the cell under the microscope presents a ladder-like appearance, and so is said to be scalanform. Then again, the thickening may take the form of spiral hands upon the inner surface ; or, instead of a continuous spiral band, we may find a series of isolated rings, when the marking is said to be Reticulated cells are also found, in which the markings, as the name implies, form a sort of network on the walls. Several of these forms are shown in Figs. 223 and 224. 269. Sometimes round thin spots will be left in the wall, and over each of these a thick-walled dome with an opening at the top will be formed. At the same time a similar dome is raised at exactly the same spot on the other side of the wall in the next cell ; and, finally, the thin par- tition between the opposite domes breaks away, permitting free communication. Thus are formed what are called bordered Fig. 223. Fig. 224 pits, which abound in the wood of Conifers. 270. When cells stand end to end, and thin spots are Fig. 222.— Dotted duct. (Gray.) Fig. 223.— Spiral and annular markings on cell-wall. (Gray.) Fig. 224.— Various markings on cell- wall. (Gray.) ■li ill I ! 164 ELEMENTS OF STRUCTURAL BOTANY. left in the cross-partitions between them, sieve-cells are formed. Here, again, the thin spots finally disappear, thus practically uniting adjacent cells. 271. It sometimes happens that the thickening takes place throughout the length of a cell but in its angles ovly. Cells of this kind, which are often found im- mediately under the surface of the stem in the higher plants, are called collenchyma cells. 272. Besides the markings on the inside, cells often shnw markings on the outside. The pollen-grains of the Mallow, for instance, are seen under the microscope to be covered with j)ointed projections. Other pollen-grains, ilso, exhibit outside markings of different sorts. 273. The thickening deposit may be so excessive in some cases as to almost completely fill up the cavity of the cell (Fig. 225). The shells of nuts and the tough coatings of seeds consist of cells of this kind ; but even in these cases the wall may be seen to be traversed by slender pores or canals, either >imple or branched, radiating from the centre of the cell. To these hardened cells the name sclerenchyma is applied. 274. The Contents of Cells. If you look at Fig. 215, or, better still, if you have the opportunity of viewing a Moss-leaf through a good microscope, you will see that in the protoplasmic lining of the cells there are numerous greenish, rounded granules. These are the bodies to which the green parts of plants owe their colour. They are called chlorophyll-granules^ and consist of protoplasmic matter in which particles of green Fig. 225.— Sclerenchyma, the cell-cavity being almost obliterated. (Qny.) Fig. 226. THE CELL. 165 colouring matter are embetUled. The colouring matter itself is cliloroi)liylI, and may be dissolved out of the granules, leaving the latter as ordinary protoplasm. Almost without exception chlorophyll re(piires the action of sunlight for its production, and the chlorophyll dis- appears from green parts when sunlight is withdrawn, as is well seen in the process of bleaching celery. In many of our brightly coloured foliage-plants the chlorophyll is concealed from view by other colouring matters. In flowers various colours are found in the protoplasm, but these, unlike chlorophyll, are produced in darkness as well as in sunlight. 275. Chlorophyll is of the utmost importance to the plant, seeing that only in the cells which contain it, and in the presence of sunlight, can the materials which the plant imbibes from the soil and the air be assimilated, that is, converted into matter which the plant can use for the purposes of growth. . 276. Now consider Fig. 214. Here are exhibited cell- contents of an entirely different aspect. The rounded bodies here visible are starch-granules, as may be easily demonstrated by adding a drop of iodine solution to the Potato section under the microscope, a characteristic blue colour being at once produced. Such granules, differing somewhat in shape in different cases, abound in the cells of tubers and n grains of all sorts, where they have been stored up for use during the process of germination. They are originally formed during sunlight in the chloro- phyll granules of the green parts. When the light is withdrawn, as at night, they are dissolved and carried in solution to other parts to promote growth or to be stored up. tii' r'l h I :«' il i'i' •f 166 Elements op structural botany. 277. If starch-granules be subjected to the action of saliva, it will be found that a portion of each granu\e is slowly dissolved out, leaving an insoluble skeleton behind. The granule, therefore, consists of two distinct parts, the more soluble portion being known as granuloses and the less soluble framework as starch-cellulose. 278. Crystals. These are of common occurrence in many plants, not only in the cell - cavities, but also imbedded in the substance of the cell-wall. They are also of various shapes, and may either occur separately or be massed together in clusters. The needle-shaped forms are known as rapliides. These crystals consist for the most part of calcium oxalate, but calcium carbonate i; also found, and may be readily distinguished from the former by tiie effervescence occasioned on the addition of hydrochloric acid. The oxalate dissolves in this acid without effervescence. Crystals may be readily observed under the microscope in thin sections of scales from the Onion bulb, Ehubarb, Indian Turnip, and many other plants. 279. In the leaves of plants of the Nettle Family it frequer^ly happens that a wart-like growth of cellulose takes piace on the inside of the cell-wall, the inwardly projecting mass being attached to the wall by a slender stalk, and having multitudes of small crystals imbedded in it. Such inward growths are called ci/stolifhii ; they may be readily seen in cross-sections of the Nettle leaf. 280. Crystalloids. Seeds, especially those of an oily nature, as they api)roach maturity and become dry, develope in their cells multitudes of small rounded bodies of an albuminous nature known as aleurone-yrains^ and i . FORMATION OF NEW CELLS. 167 these often envelope minute substances of crystalline aspect, which, liowever, under the action of potash and other re-agents, undergo such changes of form as to lead to the belief that they are not true crystals. They are called erystalloiUa, and arc to be regarded as forms of protoplasm. Occasionally crystalloids are observed without the albuminous envelope, as, for example, in the tuber of the Potato. Fig. 214 shows a cell having two or three such crystalloids of a cubical shape. The aleurone-grains in seeds containing starcli fdl the spaces between the starch-granules. In oily seeds, such as the Brazil-nut, they replace the starch. 281. Other cell-contents. Besides the important substances already enumerated as products of the proto- plasm, many others are found, such as sugar, inuline (a substance nearly related to starch, and finind in a few special plants), fixed oils (castor, olive, linseed, fe, chiefly in seeds), essential oils (turpentine, oil of lemons, and essences of different kinds), gums, resins, and various acids. 282. How new cells are formed. There are several methods l)y which new cells are produced, but in the higher plants the common method is that of cell- division. We have already stated thiit only the newer thin- walled cells are capable of exercising this function. The process is briefly as follows : in the cell about to divide, the protwplasm first separates into two portions, each containing part of the nucleus ; then a partition-wall of cellulose is developed between the two portions, thus forming two cells oat of the original one. Each part then Sf f I li'l I 168 ELEMENTS OP STRUCTURAL BOTANY. Id enlarges and divides again, and so the process goes on, When cell-division takes place in one direction only filaments or threads are formed ; if in two directions, surfaces are formed ; while division in three directions gives rise to masses. It is evident that every part of a plant, however much altered in its later history, must in its earlier stages have consisted of this thin-walled cellular suhstance, or meristem^ as it is called from its power of dividing. 283. Cell-division, then, is the method of new cell formation which prevails in the vegetative parts of the higher plants. In the production of pollen, however, and of the spores of vascular cryptogams, four new nuclei are formed in the cell, and the protoplasm collects about these, eventually secreting walls, so that four new and complete cells are formed ivithin the original one, and tliese sooner or later make their escape. This mode is known as free cell-formation. In the production of the endo- sperm cells in the embryo-sac and the spores of many of the lower plants a similar process goes on ; but here the division of the nucleus is not limited to four portions, as in the cases just mentioned, but may be carried on to an indefinite extent. 284. In some lower plants the entire contents of two adjacent cells may coalesce to form a single new cell. Tliis mode is known as cinrjagation. Also, the contents of a cell may coritract and develope a new cell-wall, a process known as tlic rejuvenescence or renewal of a cell. 285. Tissues. An aggregation of similar cells is called a tissue. Originally, every part of a plant consists ol meristem^ that is, of cells capable of dividing. Jiut ^oes on, n only 'ections, rections er much res have LUce, or g- lew cell ,s of the 3ver, and luclei are ts about new and one, and is known .he endo- [ly of the lere the rtions, as on to an ts of two new cell. contents 11 wall, a II cell. cells is consists iig. But TISSUES. 169 changes set in, as we have seen, at a very early stage, and eventually all the cells assume permanent forms, some developing in one way, others in quite a different way, according to the function of each particular part. So that in any given plant we find tissues, or groups of cells, of very various kinds, and very different arrangements of these tissues in different cases. By examining sections taken in succession from the growing point backwards, every degree of change from meristem to permanent tissue may be made out. 286. In the growing parts of all plants, in the pulp of fruits, in the pith, in the green parts of leaves, and in the entire substance of many plants of low organization, we find tissue composed of short and comparatively thin- walled cells, to which the name parencliyma has been given. On the other hand, in the substance of wood, in the inner bark, in the petioles and veins of leaves, &c., we meet with tissue consisting of long, pointed, and overlapping cells, and known as p7V)senrhf/7na. That of the wood is, Jihrons tissue, and that of the inner bark is the bat^f, specially characterized by the extraordinary length and flexibdity of the cells. Sclerenchyma and coUencJu/ma have already been referred to. In the former the cells are commonly, though not always, short; while in the latter they are usually long, but the ends are not pointed. 287. Cells have been described which are characterized by peculiar markings on their wa Is. When such cells stand end to end, the cross-partitions conmionly dis- appear, with the effect of forming long tubes, generally of larger diameter than the other calls with which they 1: m\ m 1 1 I* i' M M 170 ELEMFNTS OF :TRUC'riJHAL BOTANY. % \' are as? x^.Led. Such large cells are known as vessels, and tisL^ue formed of them is called vascular or tracheary tissue. Hence we have spiral, scalariform, annular, reticulated, and dotted vessels. These different kinds of vessels are usually found associated with fibrous tissue, and the combination of the two is known as the jibro- vascular system. 288. Many plants, such as Dandelion, Blood-root, Milkweed, and Spurge, emit a coloured or milky juice when wounded. This juice is technically called the latex. It is contained in a special tissue which is peculiar to such plants, known as laticiferous tissue. Its form differs in different cases. In some instances it consists of long tubes which may or may not branch. In others, the cells composing it form a net-work. As in the case of vessels, the latex tubes are commonly formed by the coalescence of cells originally separate, but sometimes by the continued apical growth of single cells. 289. Sieve- tissue has been already noticed. The cells are usually rather wide, and the v,,illp are not hardened, but the cross-partitions between the cells are thickened and perforated. 290. It may be added that diujle cells which resemble vessels in their markings are often spoken of as tracheids. 291. Tissue-Systems. While groups of similar cells are designated tissues, we may have also different combinr.'.i'ins of these tissues in different plants, or in different parts of 1 e same plant, and these > arious combinatif^ns are known as tissue-rystems. These are now usually ranged • a^er tlree heads: (1) The Epidermal System, includiii/; Aicae combinations i tissue which goto H,,^,. > TISSUE'S A STEMS. 171 3QQQQaQt~ form the coverings of young stems, roots, and leaves ; (2) The Fibre-vascular System, including such combina- tions as form the stringy masses which abound in the substance of the higher plants ; and (3) Tlie Fundamental Syt^tem, including the combinations of cells which have undergone little or no change of form ; in short, all the rest of the plant except the two systems first mentioned. 292. The epidermal system is most highly devel- oped in Phanerogams. Fig. 226 shows a section through the thickness of a leaf. Here it will be observed that there is a closely-packed layer of cells forming the upper sur- face, and a similar layer form- ing the lower surface. These layers constitute the epidermis or skin of the leaf. The outer part of the epidermis is usu- ally a continuous layer, and is known as the cuticle. It will be seen that the walls of these cells are much thicker than those of the cells in the body of the I'^af, and also that the epidermal cells, unlike the interior ones, have been emptied of their protoplasmic contents and are rectangular in shape. It sometimes happens that the epidermis consists of two or three layer instead of one. The outgrowths of the epidermis, included under tlie general term trickomes, have already been referred to ; they must be regarded as part of the epidermal system. Fi|^. 226. — C'ross-aeotion of a leaf, showitifj epidermis above ari> Ijelow, palisade rolls under the Aipper epidermis, and loose tit»6Ue with iutfrcellu; takes its place. These cork- cells are modificationri K.,i the cells beneath the epidermis, and they form an elicctudl protection to the tissues within. The skin of the Potato- t;uber exhibits this corky layer very clearly. The ^^peciul tissue from which the cork is developed is called phellogen, 295. In the fibro-vascmar system different plants exhibit a very di fereni arr;in<;ement of the component Fig. 227. — Stoma from the urface of a leaf, showing the cresoent-shapect guMNl-cella V TISSUE-SYSTEMS. 173 tissues. As a rule, these tissues are capable of division into two groups, in one of which the wood is developed, and in the other the bast. To the former of these group the general term xijlem is applicable, and to the latter the term phloem. The xylem is made up of the elongated vraody cells with pointed and overlapping ends, already referred to as fibrous tissue, the wide tubes (vessels) with variously marked walls, formed by the disappearance of the cross-partitions between cells placed end to end, and more or less short-celled tissue or parenchyma. The phloem is likewise made up of three constituents : the long, thick-walled, flexible cells called bast-cells, which correspond to the fibrous tissue of the xylem ; the widn thin-walled sieve-cells, corresponding to the vessels; and a certain amount of thin-walled parenchyma. 296. The fibro-vascular bundles, as they are called, have their origin in the meristem of the growing point. This meristem is at first uniform, but s"o(m groups of long cells arise in it, and these are then known as j^^'ocavihiiwi, to distinguish them from the surrounding ground- tissue. This procambium is gradually converted into the fibro-vascular bundles. 297. In dic(jtyledonous plants, the Fii? 228 fibro-vascular bundles are more or less wedge-shaped, as shown in Fig. 228. The inner part of each bundle consists of xylem and the outer of phloem, and between the xylem and tlie phloem there is a layer of meristem, known as the cambium. The soft cells of Fig. 228. — Cross-section of ayoung dicotyledonous atein, showing six bundles. 'i t m III III , ! I 174 ELEMENTS OP STRUCTURAL BOTANY. s*'* the cambium divide, and the new cells thus continually being formed become modified on the one hand into tissues which increase the thickness of the xylem, and, on the other, into tissues wliich are added to the phloem. Later on cambhim cells are formed in the ground-tissue between the bundles, thus linking together the cambium-layers of the various bundles, and forming a continuous ring. The links are tluii known as interfascicular cambium, that of the bundles themselves being the fascicular. Bundles of this kind, characterized by the cambium-layer, and so capable of continuous enlargement, are called open bundles. 298. In monocotyledons, on the other hand, there is no caml)iuin-layer, and consequently the bundle when once formed is incapable of further in- crease, and so is said to be closed. Fig. 229 is a representation of the cross-section of an ei d',^enous stem Ml which many of these cl :jsed bundles ui'e visible. Of course in such stems no bark is formed. 299. It has been explained that in the exogenous stem the xylem occupies one side of the tibro-vascular bundle, while the phloem occupies the other. In the closed bundles of Ferns and Club-Mosses, as well as of some monocotyledons, however, a different arrange- ment prevails, the xylem occupying the central part of the bundle, and the phloem forming a circle around it. The former arrangement is described as collateral, while the latter is concentric. In many of the monocotyledons, as well as in the exogens, the bundles are collateral. Fig. 229.— Cross-section of monocotyledonous stem, showing closed bundles. . TISSUE-SYSTEMS. 175 FijT. 230. each ring sliowing the limit of a year's growth. 300. Fig. 230 shows a section of an exogenous stem somewhat older than that shown in Fig. 228. Here new bundles have been formed between the earlier ones, so that the whole centre of the stem, except the pith and the lines radiating from it, is occupied by the wood. This cylinder of wood is now encircled by a ring of cambium, beyond which are the tissues of the phloem. 301. The appearance presented by the cross-section of an exogenous stem is that of a series of concentric rings. The portions of wood formed late in the summer are more compressed by the outlying tissue than those formed in spring, and hence the outer part of each year's ring appears denser, and is sharply marked off from the ring of the following year. No growth of the cambium takes place in winter. The rays which intersect these rings as fine lines consist of portions of the ground or fundamental tissue which ha^o been squeezed into their present form by the increasing fibro-vascular bundles on each side of them ; they are called mednlla^f/ raijf^, and, as the stem grows, new ones are formed from the cambium. Only the primary ones, however, extend from the pith to the bark; those formed later are shorter. 302. In roots a special arrangement of the tissues of the bundles prevails, the xylem and phloem forming alternate rays. This is the radial arrangement. 303. The fundamental or ground tissue com- prises all the parts of the plant not already included in Fig. 230.— Section of an oJder dicotyledon, the bundles now forming a ring. ^ .1 I;. \ \k ' I 111 I 17G ELEMENTS OP STRUCTURAL BOTANY. ff the epidermal and fihro-vascular systems. In the 3xogens it embraces the pitli, the medullary rays, and parenchyma generally. The collenchyma found just beneath the epidermis, sclerenchyma occurring in different parts, and laticiferous tissue are also constituents of the fundamental system, as well as the cork cells already referred to. In the monocotyledons ground-tissue in the form of parenchyma fills the space between the closed bundles of the stem ; while in many plants in which Hbro-vascular bundles are not produced, the ground- tissue constitutes the whole of the interior. 304. In exogenous stems the wood developed from the cambium is often different from that of the primary bundle as developed f lom the procambium. Pines, for example, have vessels in the primary xylem, but none in the secondary, the latter being almost entirely made up of the cells with bordered pifx, already described. 305. The bundles of the leaves are continuous with bundles in the stem. Leaves appear at first as protuber- ances on the side of the stem close to the growing point, and the upper ends of the primary bundles almost at the very beginning bend outwards towards the new leaves, the lower part being continued down the stem. In the monocotyledons these bundles first arch inwards towards the centre of the stem, and then outwards and downwards, thinning out as they descend. Hence, in a cross-section (Fig. 229) the bundles appear more crowded towards the circumference, and also smaller. Such a stem is, therefoi-e, found to be harder at the outside than at the centre. CONSTITUENTS OF PLANTS. 177 CHAPTER XX FOOD OP PLANTS — CHEMICAL PROCESSES — MOVEMENTS OF WATER — PHENOMENA OF GROWTH. 306. The materials of which the substance of a phint is made up are various, and some of them occur in far larger quantities than others. Water forms a very considerable percentage of the whole weight, but is present to a greater extent in some portions of a plant than in others. Fleshy roots, for example, may contain as much as 90 per cent, of water, while dry seeds contain only about 12 per cent. 307. The water may be expelled by careful drying, and if what is left is then burnt, what is called the organic part of the plant disappears, and a small quantity of ash remains behind. The organic part is found to consist mainly of carbon, hydrogen, oxygen, nitrogen, and sulphur ; while the inorganic part (or ash) contains very small quantities of phosphorus, iron, calcium, mag- nesium, and potassium. All these materials are obtained from the air or the soil. There is constantly present in the ?Av carbonic acid gas, a compound of carbon and oxygen, which is exhaled from the lungs of animals, and which is always, found wherever wood or coal, or carbon in any form, is being burned. This gas is absorbed directly from the air by the leaves of land-plants, and (being soluble) from the water in which they live by immersed plants. In the presence of chlorophyll and in sunlight the gas is decomposed into its carbon and oxygen. The excess of oxygen is then exhaled and the carbon chemically combined with the other elements to A k i Mi .'I \ \ II ir 1 i 'I ; 11 >%.^'V, IMAGE EVALUATION TEST TARGET (MT-3) 1.0 I.I 1.25 IM 1^ [12.5 2.2 2.0 1.4 m 1.6 7^ /) fV-^'^ "^.K^. 7 '/ -(S^ Photographic Sciences Coiporation 23 WEST MAIN STREET WEBSTER, N.Y. 14S80 (716) 872-4303 ^^ V % i\ \ .V \ o ■*■ ►.v^ ^ 178 ELEMENTS OF STRUCTURAL BOTANY. ■ I IIP* form starch for purposes of growth. The oxygen re(iuired by tlie plant is derived chiefly from the carbonic jicid gas and from watei*. Hydrogen is obtained by the decomposition of water, and nitrogen from the ammonia, which, like the car})()n (Hoxide, is carried down from the air by rain, and also from nitrates contained in the soil. Sulphur is obtained from salts (such as calcic sulphate) found in the soil, as are also, of course, all the inorganic elements. Of all these constituents of the dri/ plant, carbon is the most abundant, amounting to about half of the entire weight. 308. The inorganic elements, though small in quantity, are, nevertheless, essential. If, for example, a plant be altogether deprived of iron it will produce no chlorophyll ; while, if potassium is withheld, it will not produce starch. These facts are proved by causing seeds to grow under conditions which enable us to accurately control the supply of nutrition in the form of carefully prepared solutions of the different in^^rcdients. Several substances of connnon occurrence in the ash of plants, as silica, sodium, and some others, are in this way shown not to be essential to healtliy growth. 309. Tiie process by which the carbon, obtained from the carbon dioxide, is combined with the elements of water to form starch is called asdmilatum. As already explained, the particles of starch which are formed b^ the chlorophyll granules in sunlight are converted by combination with oxygen into soluble forms, and carried away, when the light is withdrawn, to other parts where growth is going on, or to storehouses such as tubers and seeds. This oxidisinir and convertinir process is metastasis. RSSPIHATION. 179 1 *. In consequence of having such a store of material, tubers can grow in the dark as long as the material holds out, but will not, of course, produce green leaves. Besides starch, oil is a common form of reserve material, particularly in seeds. Sugar, also, is found; as, for example, in the Sugar Beet. 310. Parasites and saprophytes, which are as a rule without chlorophyll, do not assimilate, but obtain their nourishment from the stores of other plants or from decomposing organic matter 311. The so-called cariiivorous plants, such as the Bladder-wort and the Pitcher-plant, obtain a portion of their nitrogen by entrapping insects and other small animal organisms, and absorbing them as they decomposi;. Some such plants appear to cover their prey with an acid secretion, and to go through a digestive process not altogether unlike that performed by animals. 312. Respiration. Plants, like animals, are continu- ally inhaling oxygen, and the presence of this gas is essential to their existence. The oxygen so inhaled is combined with carbon to form carbon dioxide, and this in the day-time is at once decomposed and the carbon assimilated. The absorption of oxygen and its subsecpient combination with organic matters in the plant is accom- panied by evolution of heat, a fact well illustrated in the process of malting, where damp barley is heaped together. As soon as the grain begins to sprout, oxygen is rai)itlly absorbed, and a very decided rise of temperature take;? place. The starch of the grain is oxidised and converted into sugar, and the growth is then stopped by rapid drying. The sugar, on fermenting, produces alcohol. 1 i .^^ 180 ELEMENTS OP STRUC3TURAL BOTANY. 313. Transpiration. The openings in the epidermis, called stomata, have already been described. Through these the excess of water-vapour in the plant is exhaled. it may often be observed, in hot, bright weather, that the leaves of plants droop if exposed to the sun. This is because the rate of evaporation through the stomata is greater than the rate of supply at the roots. At night, however, the stomata close and the balance being restored the plant recovers. The water which is thus supplied to the leaves appears to bo conveyed through the stem by means of the cell-ivalls of the wood-prosenchyma, since the supply is not diminisl>.ed if a ring of bark and the under- lying bast and cambium be removed. 314. But water is also supplied to the growing points, and in a different way. It is well known that if two liquids (or gases) of different density are separated by a porous diaphragm they will tend to change places, the fluid of less density passing through the diaphragm more rapidly than the other. This is the principle of osmose^ and wherever in a plant a cell-wall separates cell-contents of dillL'rent density it is found to apply. Hence, water is absorbed by freshly-formed cells, containing dense proto- [)lasm, frovn neighboring cells which are a little older and in which the protop^jsm has been diluted. These absorb from the older cells behind them, and so on. Such water is transmitted, not through the prosenchyma of the wood, but tiirough the parenchyma and ihe meristem. 315. It Is a matter of common observation that the stems of many plants " bleed " if cut in the spring. This is due to the upward pressure of the water with which the roots are charged at that time, and it takes place in the IS GROWTH. 181 >','. absence of transpiration. When the leaves are formod and transpiration se^s in actively, the root-pressure is relieved and the stems will no loiiLjer bleed imraedia,tely on being wounded. In some plants the excessive root- pressure even causes drops of water to exude from the leaves. 31 G. We may observe, then, three distinct movements of water in the plant: (1) the rapid movement to make up for the loss by transpiration, (2) the slow movement to su})ply the growing cells with requisite moisture, and (3) the movement due to root- pressure. 317. Growth. Growth has already been refeiTed to as consisting in the formation and subsequent enlargement of new cells, accompanied in many cases by change of form. It has also been mentioned that the enlargement is the result of the introduction of new particles of vegetable material into the spaces between the molecules of the parts already formed — a process known as intussus- ception. It is now generally admitted that each of the molecules of which the plant-body is made up is enveloped in a sheath of water. We know that the presence of water is essential to >^iowth ; when it is absorbed by a growing cell the immediate effect is to stretch ihe cell, as it were, to its utmost capacity ; in other words, to separate the molecules as far as possible and so increase the amount of water between tliem, thus making it possible to inter- pose new molecules of solid matter. The use of the water, also, as a vehicle for conveying the new material is obvious. This iiew material, the presence of wliich is essential to growth, is commonly supplied to the growing points from older parts which serve tlie jjurposoof storehouses, as seeds and tubers, or of manufactories, as the leaves. M^'A I ■'I 111 I if * i ' r. 1 'i K \u 182 KLEMENTS OF STRUCTLRAL BOTANY. 318. Stems and roots, as a rule, exhibit three distinct regions according to ine stage of development at which they have arrived. Tliere is, first, the growing point, the cliief characteristic of which is lie rapid formation of new cells by division ; secondly, the elongating part, chiefly characterized by the growth of the cells in length, there being practically no further division here ; and, thirdly, the fully developed part, in which there is no further division or enlargement, though the cells may continue to discharge various important functions. 319. Growth, whilst dependent upon an adequate supply of water and of new material, is also largely affected by external conditions, such as temperature and light. Growth may be stopped altogether by either too low or too high a temperature, and between the limits within which any given plant is found to be capable of growth there will be found a particular degree of temperature more favourable to growth than any other either above it or below it. This may be called the optimum. The effect of tempera- ture differs considerably according to the amount of water present in the part afl'ected, dry seeds, for instance, resist- ing a temperature, either high or low, to which soaked seeds would at once succumb. 320. Light is essential to assimilation, but seeds and tubers, as well as many of the lower plants which are without clilorophyll, such as Mushrooms, will grow in the absence of light as long as the stock of assimilated material upon which they draw is not exhausted. The growth which takes place in the cambium-layer of dicotyledons and in roots is another example of increase in size in the absence of light. The assimilated material GROWTH. 183 in all these cases, however, has been previously elaborated elsewhere. 321. Light is found to exercise a retarding influence upon growth. A plant, for instance, in a window will bend towards the light, because the cells on the side nearest the window grow more slowly than those which are shaded, thus causing curvature of the stem and petioles. 322. Gravitation a)so affects growth, as we i .ow that the stem and root, or axis of the plant, are usually in the line of the radius of the earth at the place of growth. If a seedling plantlet be laid with the stem and root horizontal, the stem will curve upward and the root downward in the endeavour to restore the vertical direction. 323. The twining movement of the stems of many plants is due to inequality of growth at successive points in the sides of the stems. Leaves unfold from the bud because the growth on the upper side at the time of unfolding is more rapid than on the under side. These movements are called nutatioii^^ and are not due to the external action of light, but entirely to internal causes. The movements of tendrils, however, are affected by contact with the object which they grasp. 'rlN I:: 1:1 I i !f 184 1 il ELEMENTS OP STRUCTURAL BOTANY. CHAPTER XXI. EXAMINATION OF A FERN A HORSETAU -A CLUB-MOSS. lil!!: 324. We snail now proceed to tlie examination of some common plants which will be found to be typical of groups differing in important respects from the phanerogams. Ferns. Fig. 231 is a representation of our com- mon Polypody, You may find it in almost any shaded rocky place. Running horizontally beneath the surface you will find the stem of the plant, which in this case is, therefore, a rhizome. A portion of the rhizome is shown in the lower part of the figure, with fibrous roots on the under side. From the upper side are developed the leaves, which, as you see, have long petioles, and if you find one which is still in the bud you will observe that it is rolled up lengthwise, as shown in Fig. 232. The vernation is, therefore, circinate^ and this is the case in nearly all the Ferns. On examining the back of the leaf (Fig. 231 shows the back) we observe rows of brownish dots on each side of the middle veins of the upper lobes. Fig. 233 is an enlarged view showing the position of these dots at the extremities of the veinlets. When we put one of these dots under the microscope it is seen to be a cluster of minute, stalked bodies, such as that shown in Fig. 234. These bodies are further found to be sacs filled with extremely fine dust, and the dust consists of multi- tudes of rounded particles all exactly alike. They are, in short, .spores, and the sacs in wnich they are contained are the spore-cases, or sporangia ; while the clusters of sporangia are the fruit-dots^ or sori. Around each spor- angium there is an elastic jointed ring which breaks at FERNS. 185 maturity, and by its elasticity ruptures the spore-case, 'vhich then discharges its spores, as shown in Fig. 234. The leaf of the Fern, then, is something more than an ordinary foliage- leaf, and is known as the frond. The petiole is called the s^^jpe, while the mid-rib is the rhachis. 325. A spore under proper conditions developes a slender thread-like cell which eventually gives rise to a thin, flat, green expansion, resembling that shown in Fig. 235. This is called the pro- thallium. From the under sur- face root-hairs are produced as shown in the figure. On the same surface, among the root- hairs, arise mi- Figr. 231. * nute projections Fig, 231.— Root-stock and frond of Polypody. Fig. 232.— Circinate vernation of the frond. Fig. 233.— Magnified view of the sori. Fig. 234,— Sporangium discharging spores ; greatly magnified. u Fig. 232. .1 |l| . 1 'ii 186 ELEMENTS OF •^^'"CTrRAL BOTANY. of tissue in which are developed cells corresponding toth^ pollen-grains of phanerogams. These projections are the antheridia; tliey contain cells in wh'ch are fertilizing bodies known as antherozoiih. Also on the under suiface of the prothallium, rear the notch, we find structures analogous to the embryo-sac of the phanerogamous ovule. These are the archegonia. They are mostly flask-shaped bod' ies, having a germ-cell — th€ oosphere — in the lower end. The antherozoids, on escap- ing from the antheridia, make their way down the necks of the archegonia, and coming in contact with the As a result of this fertilization, a plant is developed in all respects li'^^ *l?e one which originally bore the spores on its fronds. Fijr. 236. oospheres fertilize them. 326. It is manifest, then, that we have here two distinct generations : first, the spore produces the prothallium which bears the antheridia and archegonia ; secondly, the interaction of these gives rise to a plant which bears the spores. This phenomenon is spoken of as the alternation of generations. 327. The stems and roots of Ferns are found to contain vascular bundles which, like those of monocotyledons, are closed. Fig. 235.— Prothallium of a Fern, under side ; h, root^hairs; an, antheridia} ar, arohegonia. Mag^nifled 10 times. (Prantl.) THE HORSETAILS. 187 328. From the ticcount here given of the mode of reproduction in the Ferns, it will be evident tliat the Gymnosperms occupy an intermediate position between them and the Angiosj)erms. For a description of other common Ferns differing in detail from the Polypody, the student is referred to Part IL 329. The Horsetails. At the end of Part IT. will be found a description of the coumion Horsetail, with an illustration of the fertile stem, or rather Tbranch, because both the pale spore-bearing branch and the later green shoots with whorled branches are sent up from an under- ground stem or rhizome. The spores, upon germination, give rise to prothallia bearing antheridia and archegonia precisely as in the Ferns. The prothallium is usually small, flat, and irregularly branched or lobed, developing the antheridia at the projecting ends of the lobes, and the archegonia in the angles between them ; or, in other cases, the prothallia may be dioecious. Fertilization of the germ-cell, which occupies a cavity at the base of the arche- gonium, takes place exactly as in the Ferns, and, as a result of fertilization, the germ-cell developes into a spore- bearing plant similar to the original one. Here, therefore, we have again exhibited an alternation of generations. Other species of Equisetum of common occurrence, instead of produjcing a special fertile branch, develope sporangia at the extremities of the ordinary leafy stems. 330. These plants, like the Ferns, exhibit, fibro- vascular bundles, and the epidermis is especially characterized by the excessive amount of silica contained in it, some of the species being used for scouring or polishing by reason of this property. ^ I . '. I: ft ,;:l p' flii: I. 1^ t' i I^« ELEMENTS OP STRUCTURAL BOTANY. .it ' .s •. m I Fig. 236. 331. The curious elaters (Fig. 236) attached to the spores douhtless assist theiu to escape from the spore-cases, and subsequently aid in dispersing them. 332. The Olub-Mosses. Fig. 237 is a representation of a branch of Lyc(}))odiuin claratum, one of our com- mon Club-Mosses. The creeping stem lies flat upon the ground, and often attains a great length, sending up at intervals erect branches with crowded linear-awl-shaped leaves, some of which, like the one shown in the figure, are terminated by a slender peduncle bearing one or more cylindrical spikes. These are the fertile branches, and the leaves upon them, or at all events upon the slender upper part, are very much smaller than upon the ordinary sterile branches. It is to be observed that the stems and roots of these plants branch dichoiomously (145,. 333. The sporangia are produced in the axils of the leaves of the terminal spike. One of these leaves, greatly magnified, with its attached sporangium, is shown in Fig. 238. The sporangium opens by a slit at the top to discharge the spores. 334. It is only quite recently that the -'>8. 237. prothJlium has been detected. It is described in the case observed as a " yellow is! i-v/hite Fif?. 236. — Spore of Equisetum with elaters ; highly magnified. Vig,^T.—iit&ncholLyeopodiuiuclavatuuii natural size. (Thom(.) CHARACTBR8 OF PTKKIDOPHYTES. 189 irregular lobed body, sparingly furnished on its under sur- face with small root-liairs." The antheridia and archegonia appear to be produced on the upper sur- face^ and tliese by their interaction, give rise to the new plant which bears the spores, just as in the Ferns and Horse- tails ; so that again there is an alternation of generations. 335. It is a fact of great interest that Fig. 238. in some plants nearly related to the Clul)- Mosses, two I'inds oC spores — large and small — are produced In separate sporangia. Tlie large ones develope prothallia upon wliieh archegonia are formed, and the smaller others upon which antheridia appear. 330. Tlic three plants just considered, while evidently differing in certain details of structure and in general aspect, nevertheless have a number of characters in common : 1. Then (f'il^^G in their mode of reproduction^ tohich is bi/ spores^ these bodies being quite unlike the skeds with which wc are now familiar^ and which, you trill recollect, always contain the embryo of the netv plant. 2. They all exhibit an alternation of generations, 3. They all have true roots. Jf. The three tissue-systems — the epidermal, the fihro- vascular, and the fundamental — though not all developed to so high a degree as in the Phanerogams^ still can be very clearly made o'd in both roots and stems. The Jihro-vascular bundles are always closed, as in 7no7iocotyledfms, and are, as a general rule^ concentric (299). Fig. 238. — Leaf of Lycopodium bearing sporangium ; greatly magnified, (Thom^.) It; .] 190 ELEMENTS OF STRUCTURAL BOTANY. 2 337. Plants with these common characteristics constitute a group called Pteridophytes or Vascular Crypto- gams, " cr^'ptogam " being a general term applicable to all plants which do not produce true flowers, as " phanerogam " applies to all those which do. CHAPTER XXII. EXAMINATION OF A MOSS AND A LIVERWORT. 338. Mosses. Fig. 239 is a representation of the common Hair-Moss (^Pohjtnchuin commune)^ which may be found in early summer almost anywhere. It grows in dense masses, and upon examination it will be found that while many of the stems resemble that sliown in Fig. 239, the upper extremities of others form rosettes, as in Fig. 240, whilst others again terminate in ordinary vegetative buds. 339. Let us first examine a specimen as represented in Fig. 239. There is, it will be observed, a well-marked stem, or leaf-bearing axis, upon which the crowded minute leaves are sessile. In the Mosses they always are so, and they are found, upon examination with a good microscope, to consist as a rule of only one layer of cells, being therefore mucl simpler in structure than those of the plants we have so far been engaged upon. It is also to be noticed that tlie leaves of Mosses are without stomata. 340. Observe now that oui* Moss has no true roots. It is, however, fixed to the soil upon which it grows by numerous root-hairs or rhizoifU EXAMINATION OP A MOSS. 191 341. The slender scape-like stalk which rises above the leaves is technically called the mta, or bristle ; in the left-hand part of the figure (c) the upper end of the seta is covered by a hairy cap, the cal}/])tra. In the right-hand por- tion the calyptra has been re- moved, disclosing a rJ.t\e pod, variously spoken of as the theca, or urn, or capsule, or sporangium. Fig. 241 is an enlarged view. This capsule is closed at the top by a circular lid, the operculum., which falls away when the cap- sule is mature, thus allowing the escape of the sjmres, which are produced in it. The spores are developed upon the surface of a central column which rises from the bottom of the capsule, and which is known as the columella. The opening through which the spores escape is called the stoma, and a good lens reveals the fact that around the stoma there is a circle (sometimes two) of minute teeth, known collectively as the peristome. In the Moss now be- fore us the peristome consists of sixty-four teeth. In other Mosses the number varies, being always, however, seme power of 2 ; either 4, or 8, or 16, or 32, or 64. Occasionally the teeth are altogether absent. Fiff. 23ft.— Two fertile stems of a Aloss {Poli/frichum commune) of the natural size ; at c the calyptra is seen enveloping the capsule. (Wood and SteeleX Fig, 239. t 192 ELEMENTS OP STRUCTURAL BOTANY. Fig. 240. 342. We shall now consider the mode of reproduction in the Mosses. Let us commence with the spore. This, upon meeting with proper conditions, bursts its outer coat (the exospore), and the inner coat (the endospore) is then pro- truded as a slender tube. This continues to grow by repeated divi- sion, until at length, in most cases, a tangled thread-like mass of vege- tation is produced, to which the name ^;n;^owema has been given. After the lapse of several days minute buds are developed at differ- iint points upon the proton ema, and these are found to consist of whorls of scaly leaves. This is the beginning of the development of the ordinary Moss-plant. Upon the plants thus arising from the buds are developed antheridia and archegonia, the former in the axils of tij3 leaves forming the rosettes shown in Fig. 240, and the latter at the apex of other stems, as shown in Fi«. 239. The antheridia ire seen under the microscope bo be club-shaped bodies, containing a mass of cells in which the antherozoids are formed. The archegonia are flask-shaped bodies, with a lower expanded portion and a long neck above. Fig. 242 shows the apex of a fertile Fit?. 240.— Apex of sterile stem, showinj? rosette of perlgonial leaves, in the ixils of which are tlio antluiridia ; greatly enlarged. Fig. 241.— Knlargod view of capsule, showing peristorao and detached oper- jv.i 111. (Wood and Steele.) Fig. 241. EXAMINATION OF A MOSa 193 stem with several archegonia in the centre, and Fig. 243 shows a single archegonium very highly magnified. The antherozoids upon being set free make their way down the necks of the archegonia, and unite their substance with that of special cells in the lower end (one in each archegonium). These cells, as a consequence of being thus fertilized, become sur- rounded by a thin coat and immediately begin to grow up- wards, developing the slender stalks (seta?) with the capsules at the summit, and surmounted by the calyptra, which is, in fact, nothing but the wall of the archegonium whijh is torn away at its base and carried upwards. Then the spores ore developed around the columella, and the round of life of the plant is com- pleted. As in the Ferns, we have here also exhibited an alternation of generations, the one generation being that arising from the Fig. 243. development of the spore and resulting in the production of the antheridia and the archegonia ; tiie other being that arising from the fertilization of the Fig. 242. — Enlarged view of apex of the fertile stem of a Moss; a, archegonia; b, leaves. Fig. 243. —Very highly magnified view of an archegonium; 6, the ^ixsf^ h, the neck ; m, the mouth ; the germ-cell is seen at the bottom of the Hwjk- shaped cavity. (Sachs.) i p! ii 194 ELEMENTS OP STRUCTURAL BOTANY. ■i -« special cells in the archegonia, and resulting in the production of spores. 343. Liverworts. Figs. 244 and 245 are representa- tions of portions of a very common Liverwort, Marehantia yobjmwpha. It may be found growing along the borders of marshes and in wet places generally, often with inter- mingled moss. It is of a deep green colour, and usually spreads over a consid- erable extent of sur- face. There is no ap- pearance of leaves, the plant-body lying flat upon the surface upon which it grows, and putting forth root-hairs on the under side. Fife'. 244. From the upper side arise peculiar stalked bodies of two sorts, as shown in the figures ; the one consisting of flattened or slightly convex disks, and the other being star-shaped. These stalked bodies contain the reproductive organs. In cavities on the upper surface of the flattened disks are produced the antheridia, from the cells of which are liberated the antherozoids. On the under surface of the rays of the star-shaped bodies are produced clusters of flask-shaped archegonia, each with a germ-cell at its base, and fertilization takes place in the manner already described in the account of the Moss. As a result of fertilization a capsule is developed which produces spores, Fig. 244. — Portion of a Liverwort Chiarchantia pnliftnorpha), showing the thallus and several stalked disks which boar the antheridia ; natural size. (Thora6.) feXAMlNATION OF A LIVERWORT. 195 pretty much as in the Mosses, though in Marchantia the stalk of the capsule is very short, and the whole is surrounded by a loose sheath which grows up from the base and at length completely encloses it. The spores on germinating develope into plant -bodies such as we have described, so that the alternation of generations is here also well marked. 344. Other Liverworts more nearly resemble the Mosses in form, having leafy stems, from the summit of which arise slender stalks with capsules at the upper end. These capsules, however, do not open by a stoma, but are four- valved, and -at maturity the valves split asunder, allowing the escape of the spores. In the leaves of these latter forms there are no veins of any kind. Forms in which the plant-body is a flat expansion, as in Marchantia^ are distinguished as thalloid^ while t^ie leafy forms are said to be foliose. 345. It remains to be added that Marchantia and other Liverworts reproduce themselves by buds as well as by spores. These buds (gemmoi) are formed in little cup- shaped receptacles which appear on the upper surface of the plant-body. They consist of simple masses of tissue, which fall away when fully grown, and immediately develope into new plants. Fi|?. 246.— Thallus with star-shaped ••oneptac'" hearing archegonia ; natural lijce. (Tbom^.) Fig. 245. [; j.i It li ■ ■ J ; »■ 196 ELEMENTS OP STRUCTURAL BOTANY. ^ 346. The Mosses and Liverworts constitute a distinct group of plants called BryophyteS. It will be evident from the preceding descriptions that in the matter of reproduction they do not differ materially from the Pteri- dophytes. They are, however, distinctly separated from them by the siinpler orf/anization of their tissues. The Bryophytes have no true roots, but only root-hairs or rhizoids. The whole plant-body is, as a rule, composed of thin-walled parenchyma, and only in a few cases is there any appearance of a development of a fibro-vascular system, and that only of the vaguest possible kind. There is, however, a well-defined epidermal system, and stomata are not uncommon. !5 1 CHAPTER XXIIL EXAMINATION OF A MUSHROOM — A LICHEN — A OHARA. 347. Mushroom. Fig. 246 is a representation of the Common Mushroom of the natural size, while Fig. 247 shows the several stages of its growth. At A is seen a matted fibrous mass, which is the underground portion of the plant. It is called the mycelium; at several places on it rounded outgrowths of diflferent sizes are visible. These eventually develope into the overground part of the Mushroom. At // is shown a vertical section tlirough one of these outgrowths at an early stage ; at I in this figure you will observe two dark dots ; these are the open ends of a channel which forms a complete ring EXAMINATION OP A MUSHROOM. 197 i • iM in the interior. A t / //they aro nuicli more distinct, and here is also manifest a diflerence between the upper and lower sections, which is still more marked at IV and F. The upper spreading portion is called the pilcii.s ; at T' the lower edge of the pileus is still attached by a circular membrane to the stalk. In this staire the membrane is '^^^^^^^ Fig. 246. called the veil ; later on, as seen in Fig. 246, it is torn away from the pileus and now forms the anmdii.s, or ring, about tlie stalk. Upon the under side of the pileus are produced a great many vertical, thin plates, called lamdUf, or (iills. If we make a vertical section through the pileus so as to cut across a number of the lamelUe, they will Fig. 246.— The Common Mushroom {Ayaricus campeatris); a, the pileus ; b, the lamellffi ; c, the annul us. (Thom^.) •J II It :, .■ i 198 KLEMENTS OP STKI^CTURAL BOTANY. present tl»o appearanco sliowii at A, Fig. 248, and if we magnify one of these cross-sections it will appear as at i>, Fig. 247. wliers there is seen an outer layer of cells standing on end. The whole of both surfaces of the lamellae is covered with such cells, and this special layer is the Fig. 247.— Various stages in the development of a Mushroom. (Sachs.) ill i)i EXAMINATION OP A MUSHROOM. 199 hymenium. At (7, the left hand portion of the figure shows a number of these long cells much more highly Fig. 248. magnified, some of them narrowed in at the top ko a« to form slender points, upon each of whicli is a i-ounded body. Fij?. 248.— Greatly enlarged views of sections of the lamella; of a Mushroom. (Suehs.) 11 : rii • I ilHi ■s ^00 KLEMENTS OK STRUCTURAL BOTAW. These rounded bodies are the sporcH : the nanowed ends of the cells arc caller' ■''•r'njniata, and the projecting cells which bear tliera specially known as hafthlia. The spores are formed by the simple narrowing in of the outer ends of the Imsidia. The mycelium is, therefore, the vegetative part of the Mushroom, while the stalked pileus above the surface is the fructification. The mycelium is developed directly from the spore, but so far there have not been dis- covered any indications of the interaction of sperm- cells and germ-cells such as characterize the Bryophytes and Pteridophytes 348. You will note the entire absence of green colouring- matter. The Mushrooms produce no chlorophyll, and, consequently, are incapable of assimilation. They are always found growing upon decaying organic matter, as the leaf-soil of forests and meadows, &c. 349. The Mushrooms are representatives of a brge class of plants called Fungi, all the members of which are destitute of chlorophyll. The cells of which they are made up are generally in rows so as to form long threads which are known as Jujphce, and these may be either loosely interwoven, as in ordinary Moulds, or firmly compacted together, as in the Mushroom. 350. As just mentioned, Mushrooms are saproohytic in their habits ; but there are also Fungi which are parasitic, such as Rust and Smut. To the Ifungi belong such organisms as tlie Yeast-plant, and the Bacteria which are found in putrefying matter, and are the cause of, or are associated with, diseases of various kinds. IS a ti EXAMINATION OP A LICHEN. 20\ .^.5/. Lichens. These plants may be found growing >n the bark of trees, on old fences, on rocks, or on the ground. They differ widely in external ajjpearance, sometimes growing erect and imitating a stem and branches, as in Fig. 249 ; sometimes forming flat expansions which adhere to the surface upon which they grow, as in Fig. 250. Some species are yellow, others red, others grey. A very common one is that represented in \?iS^ ^'g« 250. It may be found upon many Fig. 249. tree-trunks, and will be easily recognized by the yellow disks which dot its surface. 352. The flat part of the Lichen is the thallus, or vegetative portion, while the yellow, cup-shaped disks (the apothecia) contain the fructifica- tion. Fig. 251 shows a section of the apothecium, and also the lobing of the margin of the thallus. Fig. 252 ^'^r.^so. is a very highly magnified view of a section of a thallus, showing it to be largely made up tA of cells, or hyphce, similar to those ^ of the Mushroom. But in the Fig. 251. Lichen there are visible, in addi- tion, large numbers of spherical green cells (g g in the Fig.) known as gonidia^ which either occupy well-marked Fig 249.— A fniticose Lichen (Cladonia digitata) of the natural size ; 6, the cup ; c, the thallus ; the rounded bodies at the summit are the apothecia. (Thomd.) Fig. 250.— A foliaceous Lichen growing on a stone ; natural size. (Gray.) Fig. 251.— Section of an apothecium. (Gray.) U ::»: vl.- ? 202 ELEMENTS OF STRUCTURAL BOTANY. layers, as in tlie present instance, or are scattered through the body of the thallus. The presence of these gonidia may be said to be the distinguishing feature of the Lichens. Their true relation and function were for a long time doubtful, widely dilFerent opinions being held, but Pijr. 252. it is now generally admitted that the gonidia are them- selves chlorophyll-hearing plants^ and that the remainder of the Lichen is a true Fungus, parasitic upon the gonidia. Fig. 252. — Very hiarhly magnified view of section of the thallus of a Lichen : r, rhizoids ; in, spurious tissue of hyphae ; g, green gonidia ; o, boundary cells of upper side ; u, boundary cells of under side. (Sachs.) \\\ i I OHARA. 203 The (juesfcion as to the origin of the gonidia is not yet settled. 353. The structure of the apothecium is very well shown in Fig. 253. From the hyphae are developed large, club-shaped, vertical cells (the cusci) which penetrate between the narrower vertical branches of the hy^^hae (the paraiihyse^). In the asci arise the spores (technically, ascoxpores), usually eight in each, and these when mature are discharged from the asci, and give rise oo new plants. The ascospores are formed in the asci by the process known as free cell-formation (283). The protoplasm in the asci collects about as many different points as there are spores to be formed, and a wall is then secreted about each. This mode, which is characteristic of a large number of Fungi, is quite distinct from that which prevails in the Mushrooms, where, as we have seen, the spores are formed by abstnetion. 354. Ohara. Fig. 254 represents a Chara of the natural size. It grows almost everywhere in fresh waters, and is quite readily distinguished from other thread-like — - - — ' 1 Fi^. 253. — Very hiplily ma<,'nified view of section o an apotbeoiura, showing the club-soaped asci. (Thow&) i : '!! ill! 204 ELEMENTS OP STRUCTURAL BOTANY. aquatics by the whorls of so-called leaves which encircle the stem, and also by the general gritty nature of the plant. A very offensive odour is emitted by the plant in the course of decay. Its green colour shows at once the presence of chlorophyll. On the branches you may observe num- bers of minute, more or less rounded, bodies ; Fig. 255 is an enlarged view of one of them. Here, at ft, is shown a large central nucleus (the nucule) enclosed in a spiral covering. This spiral consists of five long cells side by side, all of which wind about the central body, and have their ends projecting above it. The nucule is a row of cells of which the highest is the germ-cell, and the whole answers, in fact, to the archegonium of the Bryophytes and Pteridophytes. It is, in this plant, called the carpo- gonium. Just below it is a globular body made up of eight triangular shield - shaped segments arranged about a central cavity. From the inner end of each segment several coiled filaments of many cells each project into the cavity. At maturity the shields separate, and the fila*- FJg. 264. ments eventually break up into their Fig. 251^ CAam /ray t/u; natural size. (Thomd.) <. CHARA. 205 constituent cells, each of which then liberates an anthero- zoid. The antherozoids make their way down the necks of the carpogonia and fertilize the germ-cells. The spiral cells then harden, and form a firm coat for the spore within. As the plant decays in the autumn, these seed- like sporocarps^ as they are now called, drop off and fall to the bottom of the water, where they eventually ger- minate. On germination, they first produce a simple form to which the name pro-embryo has been given, and from which arises the plant- body which bears the antheridia and carpogonia. There is, therefore, displayed in this case an alternation of genera- tions. 355. Chara belongs to a group of plants known as AlgSB. They grow either in the water or upon damp surfaces. Tliey differ from the Fungi principally in developing chlorophyll, so that they are able to assimilate. In colour, the AlgSB are often green, but in other cases the chlorophyll is obscured by the presence of other colours, such as brown and red. In the lowest forms of both Algse and Fungi reproduction takes place by simple division of the cells. In higher forms the entire contents of two similar adjacent cells coalesce to form a new one, from which the new plant springs. This is the process of conjugation (284). In still higher forms, as in Chara, reproduction takes place by fertilization. Fig. 265.- Highly magnified view of part of the fertile thailus of Chara, (Thoni6.) *:i Pig. 255. 206 ELEMENTS OF STRUCTURAL BOTANY. 35G. The Algre, Fungi, and Lichens together consti- tute a great group called Thallophytes. The Lichens from their peculiar constitution were once regarded as transitional between the Algje and the Fungi, and by some the Charas are looked upon as links between the Alg{« and the Bryophytes. Some further reference will be made to the Thallo- phytes in the next chapter, in which is given a brief outline of the classification of plants generally. CHAPTER XXIV. CLASSIFICATION OF PLANTS ACCORDING TO THE NATURAL SYSTEM. 357. Hitherto our examination of plants has been confined to a few selected specimens, and we have examined these chiefly in order to become acquainted with some variations in the details of growth, as exem- plified by them. Thus we have found plants which agree in exhibiting two cotyledons in the embryo, and others, again, which are monocotyledonous. Some members of the former group were found to exhibit two sets of floral envelopes, others only one, and others, again, were entirely without these organs. And so on through the various details. We now set out with the vegetable world before us — a world populated by forms almost infinite in number and variety. If, therefore, our study of these forms is to be carried on to advantage, we shall have to resolve upon some definite plan or system upon which to proceed; otherwise we shall merely dissipate our energies, and our results will be without meaning. Just as, in our study CLASSIFICATION. 207 of language, we find it convenient to classify words into what we call parts of speech, and to divide and sub-divide these again, in order to draw finer distinctions, so, in our study of plants, it will be necessary to arrange them first of all in comprehensive groups, on the ground of some characteristic possessed by every member of each group. Just as, in Latin, every noun whose genitive case is found to end in w is classed with nouns of the first declension, so in Botany every plant presenting certain peculiarities will be placed in a group along with all the other plants presenting the same peculiarities. 358. Some hints have already been given you as to the kind of resemblances upon which classification is based. For instance, an immense number of plants are found to produce seeds with a dicotyledonous embryo, while an immense number of others have monocotyledon- ous embryos. This distinction, therefore, is so pro- nounced, that it forms the basis of a division into two very large groups. Again, a very large number of dicotyledonous plants have their corollas in separate petals ; many others have them united, whilst others again have no petals at all. Here, then, is an opportunity to sub-divide the Dicotyledons into polypetalous, gamo- petalous, and apetalous groups. And so we go on, always on the plan that the more widely spread a peculiarity is found to be, the more comprehensive must be the group based on that peculiarity ; and so it happens, that the smallest groups of all come to depend upon distinctions which are, in many cases, by no means evident, and upon which botanists often find themselves unable to agree. 359. As our divisions and sub-divisions will necessarily be somewhat numerous, we shall have to devibe a special I i; 208 f i ELEMENTS OF STRUCTURAL BOTANY. name for each kind of group, in order to avoid confusion of ideas. We shall, then, to begin with, draw a broad line of distinction between those plants which produce flowers of some kind, and those which do not, and to each of these great groups we shall give the name Series. We thus have the Flowering, or, to use the Greek term. Phanerogamous, Series, and the Flowerless or CryptOgamouS Series ; or we may speak of them briefly as Phanerogams and Cryptogams. Then, leaving the Cryptogams aside for the moment, we may break up the Phanerogams into two great OlaSSeS, Dicotyledons and Monocotyledons, for reasons already explained. By far the greater number of Dicotyledons produce seeds which are enclosed in a pericarp of some kind ; but there is a remarkable group of plants (represented in Canada only by the Pines and their immediate relatives) which dispense with the pericarp altogether, and whose seeds are consequently naked. So that we can make two Sub~claSSeS of the Dicotyledons on the basis of this difference, and these we shall call the Angiospermous Sub-class and the Gymnospermous (naked-seeded) Sub-class. The first of these may be grouped in three Divisions, the Poly2)efalous, Gamopetalous, and A^etalous, and the Monocotyledons also in three, the Spadiceoiis, the Petaloideous, and the Glnmaceom, types of which we have already examined in the Marsh Calla (spadiceous), Trillium (petaloideous), and Timothy (glumaceous), and the distinctions between which are sufliciently obvious. The Cryptogams are divided into three great Classes, viz.: Pteridophytes, embracing Ferns, Horsetails, and Club-mosses ; Bryophytes, embracing CLASSIFICATION. 209 Mosses and Liverworts ; and ThallophyteS, embracing Lichens, Seaweeds (Alga»), and Mushrooms (Fungi). 360. So far, then, our classification is as follows : o M M H H Series I. Phanero- gams. Class I.— Dicotyle- dons Class n.— Mono- cotyledons . . /^Sub-class l-Angiospermk Polypetalou^ Division. Oamopetalous do. Apetalous do. V.Sub-cla88 2-Gymnosperms (Spadiceous Division. < Petaloideovts do. \Glumaceoii8 do. Series n. Cryptogams. C Class III.— Pteridophytes. < Class IV — Bryophjrtes. V Class. V.--Thallophytes. 361. The above is very nearly the arrangement adopted by Gray, but many botanists prefer another arrangement as follows : » O > Group I. Phanerogams. f Class I.— Dicotyledons. 4.— Angiosperms. < Class 11.— Monocotyledons. B.— Gymnosperms. Class 111.— Oymnospenns. ( Class lY.— Ferns, ■s Class v.— Horsetails. VClass Vl. —Club-Mosses. y Class Yll.— Mosses. V Class YUl.— Liverworts. y Class IX..— Fungi. \ Class X.—Al(jce. In this arrangement the last three Groups constitute the Cryptogams, and the Gymnosperms are raised to the rank of a sub-flivision of the Phanerogams, insteau ot Group II. Pteridophytes. Group III. Bryophytes. Group IV. Thallophytes. 1;i 210 ELEMENTS OF STRUCTURAL BOTANY. ^!l '1 ! being a sub-division of the Dicotyledons. The Lichens, also, are included in the Fungi. 362. The whole question of botanical classification is still in an unsettled state. For further information in regard to the various modes that have been put forward, the student must consult larger works. In the second part of this book, whilst the classification of Gray (who follows Bentham and Hooker) is followed in a general way, those who prefer the second arrangement of the Phanerogams as given above may easily make the requisite change. 363. Each of the Divisions is sub-divided into a number of Families or Orders ; each Order into a number of Genera ; and each Genus into SpecieS. The names of the Orders as a rule have the ending -acem^ as : Ranuncidacecej Rosacece. These names are adjectives agreeing with the noun Plantce understood, so that they mean " Rosaceous plants," " Ranunculaceous plants," (fee. 364. A species is the sum of all the individual plants whose resemblances in all essential respects are so great as to warrant the belief that they have sprung from one common stock. De Candolle has this statement : " We unite under the designation of a si)ecies all those indi- viduals that mutually bear to each other so close a resemblance as to allow of our supposing that they may have proceeded originally from a single being or a single pair." We may also speak of each one of these individual plants as a species. For example, you may say, after finishing the first lesson of this book, that you have examined a species of Buttercup. Mere differences of ■' \ CLASSIPICATIOM. 211 colour or size are not sufficient to constitute different species. The Balsams of our gardens, for instance, are of various colours, and the plants vary greatly in size, yet they all belong to one species. These minor differ- ences, which are mainly the result of care and cultivation, give rise to varieties. These are of great interest to the horticulturist, but the study of species is the great end and aim of the botanist. 365. Those Species which are considered to resemble each other most nearly are grouped into Genera, and the Genera, in like manner, into Orders ; but these particular groupings are more or less artificial, and are subject to continual alteration in consequence of our imperfect knowledge. As year by year new facts are brought to light, modifications in arrangement take place. In the Classification of common plants which constitutes the Second Part of this work, the Divisions spoken of above are placed in the order named. In the Polypetalous Division, those Orders are put first which embrace plants with hypogynous stamens and apocarpous pisiilsj the parts of the flowers being consequently separate; then those with similarly inserted stamens, but syncarpous pistils; then those with j^erigy nous stamens; and, generally, we proceed from plants whose flowers have all thei" parts separate to those exhibiting more or less cohesion and adhesion^ and finally to those having one or more parts of the flower wanting. 366. In looking up the name of a plant, it will be your object to determine the Genus to which it belongs, and also the Species. The name of every plant consists of two parts : its Genus first, and then its Species. The name of '■i 'i 212 ELEMENTS OF STRUCTURAL BOTANY. i If the Genus is a Latin noun, and that of the Species generally a Latin adjective agreeing with the noun. The Buttercup, for example, which we examined at the outset, belongs to the Genus Ranunculns. In this Genus are included many Species. The particular one examined by us is known as acris; so that the full name of the plant is Ranunculus acris. In like manner, the name of the plant popularly called Marsh-Marigold is Caltha palustris. 367. Tlie Key which is prefixed to the Classification will enable you to determine without much difficulty the Order to which a plant belongs, but nothing more. Having satisfied yoursel vestas to the Order, you must turn to the page on which that Order is described, and, by carefully comparing the descrijjtions there given with the characters exhibited by your plant, decide upon its Genus, and, in the same manner, upon its Species. THE HERBARIUM. 368. Those who are anxious to make the most of their botanical studies will find it of great advantage to gather and preserve specimens for reference. A few hints, therefore, on this subject will not be out of place. It will, of course, be an object to collectors to have their specimens exhibit as many of their natural characters as pos^^ible, so that, although dried and pressed, there will be no difficulty in recognizing them ; and to this end neatness and care are the first requisites. Specimens should be collected when the plants are in ilower, and, if possible, on a dry day, as the flowers aie THE IIEUBARIUM. 213 thpD ip better condition than if wet. If the plant is small, the whole of it, root and all, should be taken up ; if too large to be treated in this way, a flower and one or two of the leaves (radical as well as cauline, if these be different) may be gathered. As many of your specimens will be collected at a distance from home, a close tin box, which may be slung over the shoulder by a strap, should be provided, in which the plants may be kept fresh, particularly if a few drops of water be sprinkled upon them. Perhaps a better way, however, is to carry a portfolio of convenient size — say 15 inches by 10 inches — made of two pieces of stout paste- board or thin deal, and having a couple of straps with buckles for fastening it together. Between the covers should be placed sheets of blotting-paper or coarse wrapping-paper, as many as will allow the specimens to be separated by at least five or six sheets. The advantage of the portfolio is, that the plants may be placed between the sheets of blotting-paper and subjected to pressure by means of the straps as soon as they are gatliered. If carried in a box, they should be transferred to paper as soon as pos- sible. The specimens should be spread out with great care, and the crumpling and doubling of leaves guarded against. The only way to prevent moulding is to place plenty of paper between the plants, and change tlio. jtaper frequently; the frequency depending on the amount of moisture con- tained in the specimens. From ten days to a fortnight will be found sufficient for the thorough drying of almost any plant you are likely to meet with. Having made a pile of specimens with paper between them, as directed, they should be placed on a table or floor, covered by a flat i m \ b- . 2U ELEMENTS OP STRtJCTUUAL BOTANY. i ! I >i i- Ijoard, and subjected to pressure by placing vveignos uu the top ; twenty bricks or so will answer very well. 369. It is of great importance that the sheet of paper within which the plant is first placed should not be interfered with during the drying process. The directions as to frequent changes refer only to the sheets not immediately in contact with the plant. These, to ensure the best results, should be changed once a day for the first few days ; less frequently thereafter. Gray recom- mends ironing with hot irons in order to remove more rapidly the moisture from fleshy leaves, and in any case to warm the driers in the sun before putting them between the plants. When the specimens are thoroughly dry, the next thing is to mount them, and for this purpose you will require sheets of strong white paper ; a good quality of unruled foolscap or cheap drawing paper will be suitable. The most convenient way of attaching the specimen to the paper is to take a sheet of the same size as your paper, lay the specimen carefully in the centre, wrong side up, and gum it thoroughly with a very soft brush. Then take the paper to which the plant is to be attached, and lay it carefully on the specimen. You can then lift paper and specimen together, and, by pressing lightly with a soft cloth, ensure complete adhesion. To render plants with stout stems additionally secure, make a slit with a penknife through the paper immediately undor- neath the stem ; then pass a narrow band of paper round the stem, and thrust both ends of the band through the sht. The ends may then be gummed to the back of tho sheet. nii THE HERBARIUM. 215 The specimen having been duly mounted, its botcanical name should be written neatly in the lower riglit-hand corner, together with the date of its collection and the locality were found. Of course only one Species should be mounted on each sheet ; and when a sufficient number have been prepared, the Species of the same Genus should be placed in a sheet of larger and coarser paper than that on which the specimens are mounted, and the name of the Genus should be written outside on the lower corner. Then the Genera of the same Order should be collected in the same manner, and the name of the Order written outside as before. The Orders may then be arranged in accordance with the classification you may be using, and carefully laid away in a dry place. If a cabinet, with shelves or drawers, can be specially devoted to storing the plants, so much the better. i-^li IKDEX AND GLOSSARY. As The numbers refer to Sections unless Figures are specified i i Al)rnptly pinnate, 180. Absorption by roots, 2. AljHtriction, '^'>'d, Ar-aulesoent ; ajtpareutly witliout a Htem, 18. AccesHory ' "uits : 8iich as consist chiefly of an enlargement of some organ, such as tlie calyx or receptacle, not t)rgiinieally united with the ])istil, 2.'{5. Aclienium or Achene, 64, 66, 241. Achlamydeous : having neither calyx nor corolla, 74. Acicular, Fig. 145. Acorn, 71. Actinomorphic flowers, 203. Acuminate : with a long tapering [)oint. Acute: sharp-pointed, 177. Acyclic flowers, 196. Adherent: a terra applied to the union of unlike parts, e. g., sta- mens witli corolla, &c., 26. Adnate, 62, 211. Adventitious: occurrin^ . ;itof the natural position. Adventitious roots, i;}4. Adventitious buds, 139. Aerial roots, 134. i^^^stivation : the folding of the floral envelopes in the bud, 210. Aggregated fruits, 234. Air-plants (epiphytes), 87. Albumen (of the seed): solic nour- ishing matter distinct from th-j \ embryo, 12, 80, 1 17, 248. Albuminoids, 263. Albuminous seeds, 80, 248. Aleurone-grains, 280. Algffi, 365. Alternate (leaves), 158. Alternation of generations, 326, 329, 334, 342, 343. Ament or Catkin, Figs. 68, 69. Amplexicaul: clasping a stem. Anatropous : a term ai)plied to ovules when inverted, so that the micropyle is close to the point of attiiclunent, 240. Andr(i3cium : the circle of stamens collectively, 211. Androus : an ending of adjectives des(;riptive of stamens, e. g., monandrous, polyandrous, &c. Aneniophilous, 74, 247. Angiospermous : applied to plants whose seeds are enclosed in an ovarv, 124, 129. Annual : a plant whichfgrows from the seed, flowers, and dies in the same season, 136. Annular vessels, 268, 287. Annulus, 847. Anterior. 197. Anther: tlie essential part of a stamen containing the pollen, 6, 211. Antheridium, 325. Antherozoid, 325. Apeta ous: without a corolla; hav- ing only one set of floral en- velopes, 20. Apex of leaves, 177. Apocarpous : ap{)lied to pistils when the carpels are free from each other, 7, 21, 216, 229. Apothecium, 352, 353. Appendage : anything attached or added. Appressed : in contact, but not united. Aquatic : growing in the water, whether completely or only partially immersed. Arborescent : resembling a tree. Archegonium, 325. Aril, 126, 250. Arrow-shaped, Fig. 155. "^■^"^^»«L. T (■ ; INDKX AND GLOSSARY. t>17 Asfenr^iiif,': risinpf upwards in a slanting direction ; applied cliicriy to weak stems. A scending axis: the stem of a plant. Asci, 8'j3. Asoidium: a pitcher-sliaped leaf, Fig. 169. Ascospore, 353. Ash of plants, 307, Assimilation, 275, 309. \uriculate ; same as anricled, hav- ing rounded lobes at the base ; applied mostly t^>*J^te, S16. Bordered pits, ibfc?. Botryose, 143. Botryose infloreicoLce, 185, 189. Bracts, 19, 44, 194. Bracteate : subten^e^ by a bract. Bractlets : secondary oracts grow- ing on pedicels. 194. Branches, 3, 132, 141. Hraiuhing, Modes of, 141. Breatliing-porea (stomates), 293^ 313. Bristles, 227. Bryophytes, 346. Bud: an undeveloped stem oi bnnich, 137. Buds on roots, 131, 139. Bull., H2, 91, l.")2. Bulbiferous : producing bulbs. Bulblets, 155. Bulbous : like a bulb in shape. Bundles, 296. Caducous, 206. Calcium, 307. Calcium carbonate, 278. Calcium oxalate, 278. Calyptra, 341. Calyx, 6, 13, 205. Calyx-teeth, 206. Calyx-tube, 206. Cambium layer, 297. Campanulate, 208. Campylotropous, 246. Capillary: ^ne and hair-like. Capituluin: same as head, 189. Capsule, 239,341. Carbon, 307. Carbon dioxide, 307. Carbonic acid, 307. Carina, or keel : the two coherent petals in the front of a flower of the Pea kind. Fig. 36. Carnivorous j)lants, 311. Carpel 7. Carpellary : relating to a carpel, e.g., a carpellary leaf, &c. Carpogonium, 354. Cartilaginous: tough. Caryopsiri, 102,241. Catkin, 71,74, 123, 189. Caulescent: with an evident stem. Caulicle : another name for the radicle, 79, 252. Cauline : relating to the stem, e.g., cauline leaves, &c., 4, 13, 28. Cell-contents, 260, 274. Cell-division, 282. Cell-formation, 282. Cells, 259. Cellulose. 265. I 'V s"^ 218 INDEX AND GLOSSARY. Cell-wall, 269:265. Centrifugal inflorescence, 187. Centripetal inflorescence, 186. Chalaza: the part of an ovule where the coats are united to the nucleus, 245. Chlorophyll, 156, 274, 307. Ciliate, 182. Circinate : curled up like the youiif? frond of a Fern, 166, 324. Circulation in cells, 262. Circumcissile : opening like a pyxis, Fig. 207. Classification, 357. Claw (of a petal), 45, 207. Cleistogamous flowers, 247- Climbing stems, 150. Closed bundles, 298. Club-s}iai)ed: with the lower part more slender than the upper, as the style of Dog's-tooth Violet, Fig. 82. Clustered, 133, 164. Coats of tlu' ovule, 244. Coherent: a term applied to tlie union of like parts, 26. Cohesion, 26. CoUaleral bundles, 299. Collective fruits, 237. Collenchynia, 271, 286, 303. Colour of flowers, 274. Columella, 341. Column, 91. Coma : a tuft of hairs, such as that on the seed of Dandelion, Fig. 68. Complete, 8. Compound or Composite flowers, 62. Compound leu , 43, 167. Compound pihLil,216. Compound spike, corymb, &c,,l89. Concentric bundles, 299. Conduplicate vernation, 16(5. Cone, 124, 223. Conical, 133. Coniferous : bearing cones. Conjugation, 284, 365. Connate : grown together. Connate-perfoliate, Fig. 165. Connective, 65, 211. Convolute : rolled inward from oi > edge, 38, 88, 166, 210. Cordate, 176. Cork, 294, 303. Corm, 94, 164. Corolla, 5, 13, iT), 207. Corymb, 189. Corymbose : like a corymb. Cotyledons, 78, 117, 252. Creeping, 149. Cremocarp, 243. Crenate, Fig. 163. Cross-fertilization, 247. Cruciform: cross-shaped, as tl»« flowers of Shepherd's Purse, &('.. Cryptogams, 369. Crystalloids, 280. Crystals, 278. Culm, 103, 1.50. Cuneaie : wedge-shaped. Currents of water, 315, 316. Cuspidate, Fig. 161. Cuticle, 292. Cycle, 159. Cyclic flowers, 196. Cyme, 191. Cymose : like a cyme, 143, 185. Cystoliths, 279. Decandrous : with ten separate stamens. Deciduous, 6, 206. Decompound : applied to leaves whose blades are divided and sub-divided. Decumbent: applied to stemrf which lie on the ground but turn upward at the extremity. Decurrent, Fig. 166. Decussate : a^'plied to the arrange- ment of leaver, when successive pairs of oppos'te leaves are at right angles, as in the plants of the Mint Family, 158. Definite infloresceute, 187, 191. Deflexed : bent down. Dehiscence of autherf=, Figs. 185, 186, 187. Dehiscent, 231. Deliquescent: applied to stems which dissolve into branches. Deltoid, Fig. 148. Dentate, 178. Depauperate : unnaturally sdaII. Depressed : flattened down. 185, terns 7m11. INDEX AND GLOSSARY. 219 Descciidiug axis : the root, 131. Determinate inflorescence, 187,191. Diadelphous : applied to stamens, 40, 212. Diandrous: with two separate stamens, 212. Dicarpellary, 215. Dicliasium, 146. Dichlamydeous : having both sets of floral envelopes. Dichogamous, 247. Dichotomous branching, 14."), 332. Dicotyledonous, 78. Dicotyledons, 80. Didynanious (stamens), 25), 65, 214. Digitate, 168. Dimerous flowers, 196. Dioecious, 74. Disk : in flowers of the Composite Family, the centre of the head as distinguished from the bor- der, 62; a fleshy enlargement of the receptacle of a flower, 58, 75, 126. Dissected : finely cut. Dissei)iment, 218. Distinct : not coherent, (see Cohe- rent). Divergent : separating from one anothei-. Dodecandrous : with 12 distinct stamens. Dorsal suture, 217. Dotted ducts. Figs. 222, 287- Double flowers : abnormal flowers in which stamens and carpi^ls have been transformed into petals. Downy : covered with soft hairs. Drupe, 51, 231. Drupelet : a little drupe. Ducts, 287. Earthy constituents of plants, 307. Elater, 331. Elementary constituents of plants, 307. Elliptical: same as oval, Fig. 146. Emarginate, 177. Embryo, 12, 78, 117. Embryo-sac, 16, 245. Eniersed: r\ised above the sitr- face of water. Endocarp : "When the walls of a pericarp form two or more lay- ers of dissimilar texture, the outer layer is called tlie Epicarp, the middle one Mesocarp, and the innermost Endocarp." — Gray. Endogen, 119. Endo:.(enous growth, 119. Endospore, 342. Endosperm, 248. Enneandrous: with nine distinct stamens. Entire, 178. Entoniophilous, 74, 75, 88, 247. Ephetneral : lasting one day only. E{)icalyx, 35, 50. Epicarp : see Endocarp. Epidermal system, 291, 292. Epidermis, 292. Epigynous : inserted on the ovary, 58, 60, 213, 216. Epipetalous: inserted on the cor- olla, 60, 65, 213. Epiphytes, 135. Equitant (leaves), 88, 157. Essential organs, 17, 211. Evergreen : retaining foliage dur- ing winter, 122, 125. Exali)uminouH, 80, 248. Exciirrent : said of main stems wliich are distinct and well- marked to the top, as in the Pine and Fir ; the reverse of deUcpu^sj'ent. Exogen, 81. Exogenous growth, 81." Exospore, 342. Exserted: protruding, 214. Exstipulate, 181. Extine, 123. Extrorse, 211. False dichotomy, 146. Families, 363. Fascicle : a close bundle, either of leaves or flowers. Fascicled (roots), 133; (leaves), 164. l"'asci(ular cambiutn, 297. Feather-veined: same as piuuately- veined, 168. * * Fertile-flower, 68. Fertilization, 17. 1- K i I I n. Ill /^ 4 : i% I 220 INDEX AND GLOSSARY. Fibrous : thread-like, 2, 18, 22. Fibrous tissue, 286. Fibro-vascular system, 287, 291, 295. Filament, 6, 211. Filiform, 183. Fimbriate: fringed. Fleshy fruits, 232. Flora : a description of the plants of a district ; a collective name for the whole of the species of a district. P'loral diagram, 197. Floral envelopes, 14, 207. Floral formula, 198. Floral symmetry, 195. Floret, 61. Flower: the part of a phanero- gamous ])lant in which the sta- mens and i)i8til are situated. Flower-head, 60. Flower-leaves, 11. Flowering plants, 359. Flowerless plants, 359. Foliaceous : like a leaf in appear- ance. Foliage-leaves, 11, 156. Foliolate : having leaflets. Foliose (Liverwort), 344. Follicle, 238. Foot, 144. Forked cyme, 143. Free, 5, 7, 41. Free cell-formation, 283, 353. Free-central placentatiou, 221. Frond, 324. , Fruit, 228. Fruit-dots, 324. Fugacious : falling away early. Fundamental tissue, 291, 303. Funiculus, 245. Funnel-shaped, Fig. 178. Furcate: forked. Fusiform : same as spindle-shaped, 133. Galea: an arching petal or sepal, as the two upper ones in Catnip, Fig. 59. Gamopetalous, 207. GamophyllouH, 84. Gamosepalous, 34, 205. Gemmro, 345. Genera : plural of genus. Genus, 363. Germ : same as embryo. Germ-ceJls, 347. Germination, 132, 254. Gibbous : swollen on one side. Gillb, 347. Glabrous, 22, 182. Gladiate : sword-shaped. Glands : applied generally to celh or hairs on the surfaces of plants in which resinous or oilj' mat- ters are secreted ; but the term is also used to describe any pro jection, tne use of which is not clear, 226 Glandular : bearing glands, 226. Glaucous, 182. Globose : like a globe or sphere. Glumaceous : l)earing or resemi\ ling glumes, 114, 359. Glumes, 101 Gonidia, 352. Gourd, 233. Grain, 102, 117,241. Granules : particles. Granulose, 277. Gravitation, 322. Ground-tissue, 303. Growing point, ^45. Growth, 317. Gum, 281. Gymnospermous, liI4 2?3. Gymnosperms, 124, 121/, oS9. Gynandrous, 91, 2li3. Gynoecium, 199, 215. Habitat : a term applied to thr region most favourable to f\.(t growth of a plant : tha pla.( t where it grows naturally. Hairs, 226. Hairy, 4. Halberd-shaped, Fig. 154. Half-inferior, 49, 216. Half- superior, 49. Hastate, Fig. 154. Head,. 189. Heart-shaped, 175. Helicoid cyme, 144. He^icycli.! flowers, 195. Heptandrous : with seven distinct stamens. Hi H< H. If \ I ■^ !t INDEX AND GLOSSARY. 221 Herb, 148. Herbacetnis, 3, 80, 13(5, 148. Herbarium : a Ixitanist's eollectiou of dried plants, 308. Hermaplirodite, 247. Heteronierous flowers, 100. Hexandrous : with six distinct stamens. Hilum, 249. Hirsute : rough with hairs. Hispid : covered with stiff liuirs. Hoary: densely covered with tine grayish hairs. Hortus siccus : same as herbarium. Hybrids : plants resulting fri>ni the crossing of nearly related species. Hydrogen, 307. Hymenium, 347. Hyphas, 340, 35'2. Hypogyuous, 24, 20, 213. Imbricate : overlajjping like the shingles on a roof, 210. Immersed : wholly under water. Imperfect, 68. Included, 214 Incomplete, 10. Incurved (petals), Fig. 52. Indefinite, 2G, 212. Indefinite inflorescence, 180, 180. Indehiscent, 231. Indeterminate inflorescence, 180, 180. Indigenous : naturally growing in a country. Inferior : undox-neath ; farthest from the axis; the ovary is in- ferior when the calyx adheres to it throughout; tlie calyx is in- ferior wlien free fiom the ovary, 45,40,52,88,210. Inflorescence, 75, 185. Innate, 211. Inorganic elements, 307. Inserted: attached tv Insertion: tlie jioiiit or manner of attacliment, 40, 212. Integument, 24'.>. Intercellular space, 203. Interfascicular cambium, 2^)7. , Internodes, 4. Interruptedly piunate, Fig. 108. Intine, 123. Introrse, 211. Intussusception, 205, 317. Inuline, 281. Involucel, 104. Involucre, 35, 61, 71, 72, 104. Involute : rolkd inward from both edges, 100. Iron, 3U7, 308. Irregular, 30, 205, 207. Isomerous : having the parts equal in number, 100. Joints : a name sometimes given to the nodes of a stem. Keel, see Carina. Kernel, 16. Key-fruit, 241. Ki(lney- shaped, Fig. 156. Labellum (or lip), 90. Labiate, 65, 209. Lamelhe, 347. Lanceolate, Fig. 148. Latex. 288. Laticiferous tissue, 288, 303. Leaf, 4, 13. Leaf-arrangement, 158. Leaf-green, see Chloi-ophyll. Leaflet, 107 Leaf-sclndule, 184. Leaf-stalk, 4 Leaf-tendni, 150. Ltgume, 43, 238. Leguminous : producing or relat- ing to legumes. Light, 320,321. Ligneous : woody. Ligulate, 62, 200. Ligule: a strap-shaped (corolla ; in Grasses, a scab^like projection between tlie l)lades of a leaf and the sheath, 103. Limb, 207. Linear, Fig. 140. Lip, 00. Lobe, 4, 107. Loculicidal (dehiscence): splitting midway between the partitions, 230. Loculus, 219. i |;'! i ''■ ■ b m 222 INDEX AND GLOSSARY. J'' Ifi j m Lodicnle, 104. Tjoment : a jointed legume, 242. Lyrate : pinnately-lobed, with the termiiml ]()he much larger than the otliex's. Magnesium, 307. Marcescent : withering persistent. Margin of leaves, 178. Marginal : relating to the margin, 221. Markings (on cells), 208. Mass-movement of Protoplasm, 262. Median plane, 197. Medullary rays, 301. Membranous : thin, like a mem- brane. Mericarp, 242. Meristem, 282,23.5. Mesooarp : see Endocarp. Metastasis, 3u'.t. Mirropyle, 16, 244. Middle lamella, 266. Mid-rib, 168, Mixed inflorescence, 192. Monadelphous, 36, 40, 212. Moiiandrous : with a single stamen. Monooarpellary. 215 Monochlamydeons : with only one set of floral envelopes. Monoeotyledonous, 118. Monocotyledons, 118. Monoecious, 68. 71- Monomerous flowers, 196. Monopodia! branching, 142. Morpliology, 130. Mucronate, 177. Multifid, 176. Multilocnlar, 219. Multiple fruits, 237. Mycelium, 347. Naked flowers : those which are destitute of calyx and corolla. Naked seeds : those not enclosed in an ovary, 127. Nai)iform, 133. Natural system of classificatioji, 867, (fee. Naturalized: introduced from other countries, V;ut growing spontaneously from seed. Nectary : that in which nectar is secreted, 88, 224. Needle-shaped, 122. Net-veined, 4, 18. Neutral flowers : those having neither stamens nor pistil. Nitrogen, 307. Nodding : lianging with the toji downward, like the flower in Fig. 82. Nodf, 4. Normal : regular ; according to rule, Nucleolus, 260. Nucleus (of an ovule), 16, 244, 249; (of a cell), 2C0. Nucule, 354. x^Tut, 241. Nutati(ms, 323. Nutlet: a small nut or nut-like body, 65. Obcordate, 175. Gblanceolate, 174. Oblique : haviiig the sides unequal. Obliteration (of partitions), 220. Oblong, Fig. 146. Obovate, 174. Obsolete, 206. Obtuse, 177. Ochrea : a tube formed by the union of both edges of a pair of stipules. Ochreate : having ochrea?. Octandrous : having eight separ- ate stamens, 45. Odd-pinnate, 180. Offset : a short, prostrate branch, rooting at the end. Oils, 281, 309. Open bundles, 297. Operculum, 341. Opposite, 158. Optimum temperature, 319, Orbicular, Fig. 146. Orders, 363. Organic elements, 307. Organs : the jjarLs or members cr' a living body. Organs of Reproduction the part of the flower. '^' INDEX AND GLOSSARY. 223 Organs of Vegetation : root, stem, and leaves. Orthostichies, 160. Orthotropous : applied to ovules when straight, so that tlie nii- cropyle is as far as possible from the point of attachment, 24G. Osmose, yi4. Outline of leaves, 171. Oval, Fig. 146. Ovary, 7, 25. Ovate, Fig. 148. Ovoid: egg-shaped. Ovule, 7, 16. Oxygen, 307. Palate, 209. Palet, 101. Palmate, 168. Palmately-lobed, 176. Palmatifid, 176. Panicle, 106, 190. Papilionaceous, 39. Pappose, 206. Pappus: a circle of bristles or hairs representing the limb of the calyx in floweis of the Com- I)osite Family, 62. Parallel-veined: same as straight- veined, 83. Paraphyses, 353. P;irasites, 135, l56, 310. Parenchyma, 286. Parietal : on the walls, 221. Parted: almost completely cut through. Pectinate: pinnatifid with lobes like the teeth of a comb. Pedate, Fig. 160. Pedicel, 28, 58. Peduncle, 5, 28. Peltate. 126, 175. Pentamerous flowers, 196. Pentandrous : with five distinct stamens Pepo, 233 Perennial: a plant which cou- t-'nues to grow year after year, Ihf. Perfect: having both stamens and pistil. Perfoliate, 179. Perianth, 84, 90. Pericarp, 229. Perigynous. 40. 48, 213, 216. Perisperm, 248. Peristome, 341. Permanent tissue, 285. Persistent, 34, 206. Personate, 209. Petal, 5, 2U7. ' Petaloideous, 359. Petiolate : having petioles. Petiole, 4. Phanerogamous or PliH?nogamoua, 129, 359. Phellogen, 294. Phloem, 295. Phosphorus, 307. Phyllome, 225. Pliyllotaxis, 158. Pileus, 347. Pilose: having long, soft hairs. Pinna: a i)rimary division of a pinnately-compound leaf. Pinnate, 168. IMnnatelv-lobed, 176. rinnatifid, 176. Pinnule: n secondary division of a pinnately-compound leaf. Pistil, 7, 13, 215. Pistillate: liaving a pistil, 68, 70. Pitcher-shaped (leaf). Fig. 169. Pith, 300. Placenta, 221. Placentation, 221. Plaited, 166, 210. Plumose : feathery. Plumule, 79, 117, 138, 252. Pod : a dehiscent fruit, 25. Pollen, 6, 16. Pollen-masses, 92. Pollen-tube, HJ. Pollination, 124, 247. PoUinia: pollen-masses, Fig. 93. Polyadelphous, 40, 212. Polyandrous: with numerous dis- tinct stamens, 6, 24. Polycarpellary, 215. Polygamous: liaving perfect as well as imperfect fiowers. Polygamo-dicpcious, 76. Polypetalous : having separate petals, 5, 207. I : 1 t i : m \ m 224 INDEX AND GLOSSARY. Polyphyllous, 84. Rejuvenescence, 284. Polysepalous : having separate Reniform, Fig. 156. sepals, 5, 205. Resin, 281. Pcme, 63, 232. Respiration, 312. Posterior: next the axis, 197. Reticulated cells, 268, 287. Potassium, 307, 308. Retuse: slightly notched at the Prsefloration, see ^Estivation. apex. Proefoliation : the disposition of Revolute : relied back, 166. leaves in the bud, 1()(). Rhachis : an axis, 324. Prifikles, 227. Rliizoid, 340. Primary roots, 132. Rhizome, 151. Primine, 244. Kingent, 209. Procambium, 2flG. Root, 2, 13, 131. Procumbent : lying on the ground. Root-cap, 131. Proembryo, 3G4. Root-hairs, 131, 226. Prosenchyma, 286. Rootlet, 2. Prostrate ">49. Root- pressure, .316. Prothalli 325. Root-stock, 88, 151 Protonema 2. Rotate, 208. Protoulitsm, ^ ' Rudimentary : imperfectly devel- Pscudocarp, 23i. oped. Pteiidophytes, 337. Rugose : wrinkled. Pul)escent: covered with fine down. Runcinate : with teeth pointing Punctate: having transparent dots. backwards, as in the leaf of like the leaves of St. John's \Vort. Dandelion, 176. Putamen, 51,231. Runner, 134. Pyxis, 240. Quinquefoliolate : having five leaf- lets, 180. Sagittate, 28, 175. Salver-shaped, Fig. 179. Samara, Figs. 76, 2C8. Saprophytes, 135, 156, 310. Raceme, 189. Sarcocarp : the flesh of a drupe. Racemose : like a raceme, 143. Scabrous: rough. Radial bundles, 302. Scalariform cells, 268, 287. Radiate, 1(38. Scales, 74, 124, 137, 194. Radical: pertaining to tlie root. Scandent: climbing. 4,13,18,00. Scape, 19, 60, 88. Radical leaves, 4, 28. Scar, 88. Radicle, 79, 117, 132, 252. Schizocarp, 242. Ramification, i41. Scion : a young shoot. Raphe, 240. Sclerenchyma, 273, 286, 303. Raphidcs, 278. Scorpioid cyme, 144. Ray: this marginal florets of a Secondary roots, 134. Composite tlo\ver,as distinguish- Secundine, 244. ed from the disk. Seed, 12, 214. Receptacle, 8. Seed-leaves, 78. Recurved : cui'ved backwards. Seed-vessel, see Ovary. Reduplication, 200. Self-fertilization, 88. Reflcxed : bent backwards, 88. Sepal, 5, 205. Regular: with i)arts "' tiie .-.iinu Septicidal (dehiscence'): splitting size and shape, 5, 205 207. epeu along the partitions, 239, * 1 at Se Se Se Sh Sh INDEX AND GLOSSARY. oor, Beptifragal, 239. Septum ; a partition. Series, 359. Serrate, 178. Sessile, 4, 28, 211. Seta, 341. Setaceous : like a bristle. Sheath : a tube surrounding a stem, 103. Sheathing : surrounding like a sheatli. Shield-shaped, see Peltate. Shoot: a newly-formed brauc:h. Shrub, 148. Sieve-tubes, 270, 289. Silica, 308, 330. Silicle, 240. Silique, 240. Simple (leaves), 167; (pistil), 21-5. Sinuate : wavy on the margin. Sodium, 308. Solitary, 188. Sori, 324. Spadiceous, 359. Spadix, 97, 98, 189. Spathe, 97, 98, 194. Spathulate, 174. Species, 363, 364. Sperm-cells, 347- Spermoderm, 249. Spike, 100, 189. Spikelet, a secondary spike, 106. Spindle-shaped, 133. Spine, 227. Spiral markings, 268, 287. Spores: the reproductive bodies in Cryptogams which correspond to the seeds of Phanerogatns, 324, 341, 347. Sporangium, 324,341. Sporocarp, 354. Spur, 90, 209. Stamen, 6, 13,211. Staminate (flower); having no pistil, but only stamens, 68, 70. Staminode, 211. Standard: the broad upper petal of a papilionaceous corolla. Starch, 276. Starch-cellulose, 277. Stem, 3, 13, 137. Stemless, 18. Sterile (flower): having no pi8til,68. Sterigma, 347. Stigma, 7. Stigmatic : bearing the stigma. Stinging-hairs, 226. Stipe, 324. Stipulate: having stipules. Stipule, 33, IHl. Stolon: a short branch which droops to the ground and takes root, 149. Stoma (of Moss), 341. Stomata, 293, 313. Stone, see PutameJi. Stone-fruit, see Drupe. Straight- veined, 83. Strap-shaped, see Ligulate. Streaming of protoplaaiw, 2('>'2. Striate: marked lengthwise with lines or furrows. Strobile : same as Cone. Style, 7. Subulate, Fig. 147. Succulent: juicy; fleshy. Sucker: an imderground branch, at length emerging and forming a stem. Sugar, 309. Sulphur, 307. Superior, 7, 41, 45, 49, 216. Suppression : absence of parts. Surface oi leaves, 182. Susj)endod : hung from above. Suture, 217. Symmetrical, 47, 204. Sympodial, 144, 145. Syncarpous, 30, 215, 230. Syngenesious, 60, 68, 212. Tap-root, 32, 132. Teeth (of calyx , 34. Tegmen, 249". Temperature, 31i). Tendril, 150. Terete: cylindrical. Terminal: at the end of a stem ->:. branch, 44, 122, 110, 187. Ternate : in threes. Testa 249. Tetradynamous.29, 214. Tetrameruus flowers, 196. i; ; ) ■>i f-Vr 226 INDEX AND GLOSSART. Tetrandrous : having four distinct stamenB. Thalamiflorous : having the sta- mens inserted on the receptacle. Thalamus : the receptacle. Thalloid (Liverwort), 344. rhallophytes, 36G. Th alius, 352. Theca, 341. Thread-shaped, see Filiform. Throat (of calyx), 206. Thorn, see Spine. Thyrse, 192. Tissue, 285. Tissue-systems, 291. Tomentose : woolly. Toothed, see Dentate, 112. Torus : same as receptacle, 216. Tracheary tissue, 287. Traclieids, 290. Trailing, 149. Transpiration, 313. Tree, 148. Triadelphous, 40, 212. Triandrous; having three distinct stamens. Trichomes, 131, 226, 292. Triennial : lasting three years. Trifoliolate : having tliree le iflet'^, 180. Trimerous flowers, 196. Truncate, 177. Trunk: the main stem. Tuhe, 34, 128. Tuber, 151. Tuberous : like a tuber. Tubular, 208. Tunicated, 92. Twining, 150. Two-lipped, see Labiate. Types, 27. Umbel, 58, 189. Umbellet : a secondary umbel. Unguiculate : liaving a claw. Unilocular, 219. Urn, 341. Vacuoles, 260. Valvate : edge to edge, but hot overlapping, 38, 210. Valve, 46. Valved : having valves. Varieties, 364. Vascular cryptogams, 337. Vascular tissue, 287. Veil, 347. Veins : the finer parts (^f the framework of a leaf. Venation, 168. Ventral suture, 217. Vernation, same as Praefoliation, 166. Versatile, 102, 211. Vertical leaves, 88, 157. Verticillate, 158. Verticillaster, 193. Vessels, 287. Villose, 182. Volatile oils, 281. v Water i,\ the plant, 306, 315, 316. Wavy: with altei-nate rounded hollows auu projections, 178. Wedge-shaped : like a wedge, the broad part being the apex. Wheel-shaped, see Rotate. Whorl : a circle of three or more leaves at the same node, 23, 120, 158. Wing, 75, 124, 241. Woody stems, 148. Xylem, 295. Zygomorphic flowers, 203. (i^^^^^(^^ APPENDIX. . 66. Refer to their botanical orders, genera, etc.: the plum, pear, orange, pumpkin, cucumber, can-ot. 67. Describe the structure and mode of growth of exogenous and endogenous sterna. ■' ! ' . EXAMINATION PAPERS. 233 68. Give the meanings of apocarpous and syncarpous, and name two allied genera which may be distingumhed by the difference these terms express. 69. Where, in plants, are stomata most abundant ? What is their chief function ? Describe chlorophyll and explain its physiological importance. 70. By what means is fertilization effected (1) in Phanerogams, and (2) in Cryptogam s ? 71. How would you distinguish a root from a stem ? Enumerate the most important varieties of roots, giving examples. 72. Make a drawing of the leaf of the sugar maple {Acer Sacchari- mim) and of the beech {Fagus ferniginea), and describe them with special reference to form, parts, and venation. 73. Fill the accompanying Floral Schedule with an exact descrip- tion of the specimen before you. Classify, if you can. FIEST CLASS CERTIFICATES. 1. What are the cotyledons ? Describe their functions, (tc. State their value in systematic botany. 2. Describe the difference in structure and modes of growth of exogenous and endogenous stems. 3. Describe the circulation in plants. " In the act of making vegetable matter, plants purify the air for animals." Explain this fully. 4. What are Phsenogamous plants? Define Raceme, Corymb, Head, Panicle, Ament. 5. Give the characters of (a) the classes Exogens and Endogens; (b) the Mint and Lily families. 6. To wnat family do the Cedar, Clover, Mustard, and Dandelion respectively belong? 7. Why does a botanist consider the tuber of the potato an under- ground stem. 8. Give the philosophical explanation of the nature of a flower considered as to the origin and correspondence of its different parts. 9. Draw a spathulate, an obcordate, a truncate, a ^)almately- divided and an odd-pinnate leaf. 10. Explain the constitution of a pome or apple-fruit. 11. What organs appear in the more perfect plants, and in what divisions are they comprised ? 12. Give the function of the flower, itfl origin, and its essential and accessory parts. 13. Describe the nature and chief varieties of roots, and distinguish between them and underground stems. i • i I i ! 234 EXAMINATION PAPEM 14. " As to the Apex or Poiut loaves are Pointed, Acute, Obtue6, Truncate, Ketuse, Eraargiuate, Obcordate, Cuspidate, Mucronate." Sketch these different forms. 15. " There is no separate set of vessels, and no open tubes for the sap to rise through in an unbroken stream, in the way people generally suppose." Comment on this passage. 16. The great series of Flowering Plants is divided into two classes. Describe these classes. 17. Give the cniet characteristics of the order Gruciferce (Cress Family), and name some common examples of this order. 18. State the difference between definite and indefinite inflores- cence, and give examples of the latter. 19. Of wnat does the food of plants consist? In what form is it found in the soil? How is it introduced into the plant? What inference may be drawn respecting the culture of the plant? 20. Distinguish weak climbing stems according to the mode in which they support themselves, the direction of their growth, and the nature of their clasping organs. 21. Name the three classes of Fluwerless Plants, and give an example of each. 22. Explain the terms Spore, Capsule, Bract, Stipule, Albumen, and Epiphyte. 23. What are tendrils, and of what organs are they supposed to be modifications ? 24. Give the characters of the Cress Family, and name as many plants belonging to it as you can. 25. Tell wliat you know about, the minute structure and the chemical composition of vegetable tissue. 26. Describe the origin of tlie different kinds of placentas ; and of the different parts of the ^ruit of the plum, the oak, and the maple. 27. Describe fully the process by which it is supposed that water is carried up from the roots of plants. 28. Give the meaning of the terms stomate, indehiscenty thyrae, glume, pyxis. Distinguish epiphytes ixova. parasites. 29. Describe any plant yoii have examined ; if you can, tabulate your description. 80, Name all the families of monopetalous dicotyledons which you remember, and give the characters of any one of them. 81. Describe tlie following: primordial cell (utricle), protoplasm, cyclosis, mode of plant growth. 32. Describe the process of reproduction in a phanerogamic plant, 33. How are the pulse family— order Leguminosa; — distinguished? Show the utility of the plants of tiiis order. 34. What is ,^stivatioii ? Describe the different kinds, and men- tion a natural order of which each is characteristic. 35. Describe the course of the sap through the root and trunk of an exogenous tree. "1^ EXAMINATION PAPERS 235 36. Enumerate the chief nitrogenous and non-nitrogenous sub- stances which are found in plants. 37. Fill in the accompanying Floral Schedule with a full and accurate description of the specimen under observation. McGILL UNIVERSITY. 1. Describe the germination cf a plant. 2. Explain the differences in the structure of the embryo. 3. Explain the functions of the Root. 4. Describe the structures in a leaf, and explain their action on the air. 5 Mention the several parts of the stamen and the pistil, and explain their uses. 6. Describe an Acheue, a Samara, a Drupe, and a Silique. 7. Describe the differences in the stems of Exogens and Endogens, and the relations of these to the other parts of the plant and to cL ssification. 8. Explain the terms Genera, Species, Order. 9. What is an excurreut stem, an axillary l)ud, bud scales ? 10. Explain the terms primordial utricle, 'parenchyma, proto- plasm, as used in Botany. 11. What are the functions of the nucleus in a living cell ? 12. Explain the movements of the sap in plants. 13. Describe the appearance under t)ie microscope of raphidea, spiral vessels, and disc-bearing wood-celts. 14. Describe the structure of the bark of an Exogen. 15. Describe freely the anatomy of a leaf. 16. Describe shortly the parts and structures denoted by the following terms : spine, aerial root, phijUodium, cambium, stipule, rhizoma. 17. Give examples of phcenogams, cryptogams, exogens, and endogens, properly arranged. 18. Describe the principal forma of indeterminate inflorescence. 19. In what natural families do we find siliqiics, didynamous stamens, labiate corollas, or pappus-bearing achenes. Describe these structuv 20. State the characters of any Canadian exogenous order, with examples. 21. Describe the cell-walls in a living parenchymatous cell. 22. Describe the tibi'o- vascular tissues in an I'iXogenous stem. 23. Describe the appearance of stomata and glandular hairs under the microscope. 24. J)e^ne prosenohy^na, corm, cyclosis, thallus, M i i a ii I' ■| ; i If 1 1 236 EXAMINATION PAPERS. 25. Explain the sources of the Carbon and Nitrogen of the plant, and the mode of their assimilation. 26. Describe the pericarp, stating its normal structure, and naming some of its modifications. 27. Explain the natural system in Botany, and state the gradation of groups from the species upward, with examples. ONTARIO COLLi