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There are no known copyright restrictions in the United States on the use of the text. http :/Awww.archive.org/details/cu31924001719321 INTRODUCTION TO STRUCTURAL AND SYSTEMATIC Sa BOTAN Y, AND VEGETABLE PHYSIOLOGY, seria A FIFTH AND REVISED EDITION or THE BOTANICAL TEXT-BOOK, ILLUSTRATED WITH OVER THIRTEEN HUNDRED WOODCUTS. By ASA GRAY, M.D, FISHER PROFESSOR OF NATURAL HISTORY IN HARVARD UNIVERSITY. NEW YORK: IVISON, PHINNEY, & CO., 48 & 50 WALKER STREET. CHICAGO: S. C. GRIGGS & CO., 39 & 41 LAKE STREET. PHILADELPHIA: SOWER, BARNES, & CO., AND J. b. LIPPINCOTT & CO. BOSTON: BROWN, TAGGARD, & CHASE. CINCINNATI: MOORE, WILSTACH, KEYS, & CO. SAVANNAH: J. M. COOPER & CO. NEW ORLEANS: BLOOMFIELD, STEEL, & CO. ST. LOUIS: KEITH & WOODS. DETROIT: r. RAYMOND & CO. 1862. W Entered according to Act of Congress, in the year 1857, by IVISON AND PHINNEY, in the Clerk’s Office of the District Court for the Southern District of New York. University Press. Cambridge: Flectrotyped and Printed by Welch. Bigelow, & Co. PREFACE. THIS compendious treatise is designed to furnish classes in the higher seminaries of learning, colleges, and medi- cal schools, as well as private students generally, with a suitable text-book of Structural and Physiological Botany, and a convenient introduction to Systematic or Descriptive Botany, adapted to the present condition of the science. The favor with which the former editions have been re- ceived, while it has satisfied the author that the plan of the work is well adapted to the end in view, has made him the more desirous to improve its execution, and to render it a better exponent of the present state of Botany. In this view, the structural and physiological part of the work, and the chapters on the Principles of Classification and of the Natural System, have been agdin almost entirely rewritten, and such changes made as the advanced state of our knowl- edge required, or the author’s continued experience in teaching has suggested. This has been done without in- creasing the extent of this part of the volume, which, con- sidering the limited time devoted to the study in our col- leges, &c., is found to be as full as is desirable for a text- book. Being intended as a manual for instruction merely, the Illustrations of the Natural Orders, which form the prin- cipal portion of the systematic part of the work, are brief iv PREFACE, and general. Such a sketch, however amplified, could never take the place of a Flora, or System of Plants, but is de- signed merely to give a general idea of the distribution of the vegetable kingdom into families, &c., with a cursory no- tice of their structure, properties, and principal useful pro- ducts. In applying the principles of classification, and his knowledge of the structure of plants, to the investigation of the plants that grow spontaneously around him, the student will necessarily use some local Flora, such, for example, as the author’s Manual of the Botany of the Northern United States. For particular illustrations the botanist may ad- vantagcously consult the author’s Genera of the Plants of the United States illustrated by Figures and Analyses from Nature, of which two volumes have been published. About twenty-four of the wood-cuts are, by permission, selected from original sketches made for a Report on the Trees of the United States, in preparation by the author for the Smithsonian Institution. The numerous figures added to this edition are wholly of an original character. The numerals enclosed in parentheses, which abound in the pages of this work, are references to other and mostly earlier paragraphs, in which the subjects or the terms in question are treated of or explained. A full Glossary or Dictionary of Botanical Terms (com- bined with an Index) is added to the volume. In this, it is thought, the student will find explanations of all the technical botanical terms he is likely to meet with in descrip- tive works, written in the English language. The words are here accentuated, in all cases where this seemed to be needful. Harvard University, Cambridge, Sept. 1857. CONTENTS. Page INTRODUCTION. — Generau View or THE SCIENCE . PART I. STRUCTURAL AND PHYSIOLOGICAL BOTANY. CHAPTER J.—OF THE ELEMENTARY STRUCTURE OF PLANTS Sect. IL Or ORGANIZATION IN GENERAL The Elementary Constitution of Plants Their Organic Constitution . Distinctions between Minerals and Oapanized ce Individuals and Species Life . . Difference between Vegetables aif ‘Actinstls Sect. I. Or THe CeLts AND CELLULAR TISSUE OF PLANTS Cellular Structure ‘ The Cell as a Living Oger Its Formation and Growth Original Cell-Formation Cell-Multiplication Free Cell-Multiplication within a “Mothen Cell Cell-Growth Branching Cells - Cyclosis or Circulation in Cells : 1* 13 22 vi CONTENTS. Transference of Fluid from’ Cell to Cell Increase of Cell-Walls in Thickness . Markings of the Walls of Cells Dots or Pits . Disks of Coniferous Wood Bands, Rings, or Spiral Markings Gelatinous Coils ‘ = Secr. III. Or tue Kinps or TRANSFORMATIONS OF CELLU- LAR TISsvuE, Viz. Woopy Tissuz, Ducts, ETC. Parenchyma p Prosenchyma, Woody oe Bast Tissue Vascular Tissue or Vesicle, “Dotted Duets, fe Interlaced Fibrilliform Tissue Laticiferous Tissue Intercellular System Epidermal System Secr. IV. Or Tux ConTENTS oF CELLS Sap, Sugar . Starch Amyloid . : Oils, Wax, Vegetable Adis Essential Oils, Tannin, Alkaloids . Chlorophyll : Earthy Incrustations - Crystals or Raphides, Cyatdtities CHAPTER II.— OF THE GENERAL DEVELOPMENT AND MORPHOLOGY OF PLANTS Sect. I]. Phanrs or THE Lower GRADE; THEIR DEVELOP- MENT FROM THE CELL . Plants of a Single Cell . Plants of a Single Row of Cells Plants of a Single Plane or Layer of Cells Plants of a Solid Tissue of Cells Plants with a Distinct Axis and Foliage Cellular and Vascular Plants Flowerless or Cryptogamous Plants 60 61 61 65 66 67 67 68 69 CONTENTS. vii Secr. IJ. Prants or tar HigHer GRADE; THEIR DEvELor- MENT FROM THE SEED . . : , : 69 Flowering or Phenogamous Plants . . . . . 69 Organs of Vegetation and of Reproduction . : F 70 The Seed . ee a ee 0) The Development of the Embryo in Germination . ‘ 71 Number of Cotyledons : ‘i : . : - + 78 CHAPTER IIl.— OF THE ROOT, OR DESCENDING AXIS 79 Absorption by Roots; their Growth. . ‘ ; ‘ 80 Primary and Secondary Roots . . . . . . 88 Annuals, Biennials . . ‘ 3 é - é z 83 Perennials ‘ e . 3 : ; soe 84 Aerial Roots . ay she . ee ee ‘ , 85 Epiphytes, or Air-Plants . . ; ‘ , ‘ . 87 Parasites . vite a . : : e: ok : 88 CHAPTER IV.—OF THE STEM, OR ASCENDING AXIS 91 Sect. I. Irs GENERAL CHARACTERISTICS AND MopE or GrowTH : ‘ A ; ‘ - 91 Nodes and Internodes . 3 : , . ‘ Z ~ 92 Buds ‘ e : . : : - pi ‘ ‘ 93 Plan of Vegetation . . 5 . i . - 95 Phytons : . s . . . 2. & : 96 Sect. IJ. RAMIricaTIoN 3 ‘ : ‘ r . 97 Branches : 7 é ; - ‘ : a 7 97 Adventitious and Accessory Buds 4 “ : - 98 Excurrent and Deliquescent Stems . : ‘ ‘ ; 99 Definite and Indefinite Growth . 3 5 ‘ : - 100 Propagation from Buds... ete ea aR en 100 Sect. II. Tue Kinps or Stem AND BRANCHES F . 101 Herbs, Shrubs, Trees, &c. , i a : ; : 101 Stolons, Suckers, Runners . i Z “ : 2 . 102 Offsets, Tendrils . : 3 3 , : F ‘ 103 Spines or Thorns . - F 4 BD 4 . . 104 Subterranean Modifications . ‘ is : : . 105 vill CONTENTS. Rhizoma or Rootstock Tuber Corm . 3 Bulbs and Bulblets 3 Consolidated Forms of Veastation J Sect. IV. Tus Internat STRUCTURE OF THE STEM VY Secr. V. Tar Expogenovus or MonocoryLeponous STEM / Sscr. VI. Tar Exogenous or Dicoryreponovs STEM The First Year’s Growth The Wood The Bark The Cambium-Layer Annual Increase of the Woul Sap-wood and Heart-wood The Bark ; its particular Structure The Living Parts of a Tree, &c. The Plant a Composite Being. ; oakley : Comparison of Endogenous will Exogenous Structure. CHAPTER V.—OF THE LEAVES . 3 Sect. ]. Tuerr ARRANGEMENT . 3 Phyllotaxis . : : Vernafion or Practitiates ‘ : : 2 Sect. Il. Toerr Structure anp ConFORMATION Anatomy of the Leaf Stomata Development of Tkanée : The Venation and Forms of Leaves Compound Leaves c - Leaves of Peculiar cuniaiaiion or *rhansticaintion The Petiole or Leafstalk, Phyllodia, Stipules Sect. JU. Tue Duration or LEAVES; THEIR ACTION, ETC Fall of the Leaf Death of the Leaf Exhalation from the Leaves, iiss, of ihe Sap 106 107 108 109 110 111 114 116 118 119 120 122 123 124 126 129 131 132 133 133 133 143 145 145 150 153 154 163 165 170 . 172 173 174 175 CONTENTS. CHAPTER VI.—OF THE FOOD AND NUTRITION OF PLANTS Sect. I. THe Genera PoysioLocy oF VEGETATION Sect. I]. Tue Foop anp THE ELEMENTARY COMPOSITION oF PLANTS The Organic Constituents : The Inorganic or Earthy Constituents Secor. II. AsstmiLaTion, oR VEGETABLE DIGESTION, AND iTs RESULTS. Process and Results of Assimilation Effect on the Atmosphere ‘ Relations of the Vegetable to the Antinal and Mineral ings doms : : : 3 i : i é CHAPTER VII.— OF FLOWERING . Flowering an Exhaustive Process Evolution of Heat Plants need a Season of Bai CHAPTER VIUI.— OF THE INFLORESCENCE Indefinite or Indeterminate Inflorescence Definite or Determinate Inflorescence CHAPTER IX.— OF THE FLOWER Sect. I. Irs ORGANS, OR COMPONENT PARTS . Sect. I. Irs TororetTicaL STRUCTURE oR MorPHoLoGy Sect. III. Irs Symmetry Alternation of the Floral Organs Position as Respects the Axis and Bract . Sscr. IV. Taz Various MoprricaTIons OF THE FLOWER Augmentation of the Floral Circles . Chorisis or Deduplication ix 177 177 179 180 186 190 191 199 201 204 204 206 207 209 210 217 221 221 224 232 235 237 238 242 243 CONTENTS. Anteposition or Superposition . . Coalescence of Parts Adnation or Consolidation hregularity Suppression or Abortion Unusual States of the Receptacle The Disk Secor. V. Tae Frorat ENVELOPES IN ParTICULAR Their Development or Organogeny Their Mstivation or Prefloration The Calyx The Corolla Sect. VI. Tur STaMeEns. The Filament and Anther . The Pollen. ‘ 5 z Sect. VII. Tue Pistits The Simple Pistil . : ‘ é The Placenta. é - ‘ ‘ . The Compound Pistil Modes of Placentation Gynecium of Gymnospermous Plants Sect. VUI. Txt Ovute Sect. IX. FERTILIZATION AND FORMATION OF THE EMBRYO Parthenogenesis 3 a 3 4 , - Access of the Pollen . ‘ Action of the Pollen on the Btioma ‘ Origin of the Embryo CHAPTER X.— OF THE FRUIT Sect. I. Irs Srructure, TrRansrormations, &c. The Pericarp or Seed-vessel Obliteration or Alteration . Ripening, Dehiscence Sect. II. Irs Kryps 248 249 250 253 255 266 267 268 268 269 274 275 279 281 285 287 288 289 290 292 296 297 300 300 301 302 304 308 308 308 309 310 311 CONTENTS. CHAPTER XI.— OF THE SEED Secr. I. Irs Strrucrure anp Parts . The Nucleus and Albumen The Embryo Sect. II. GermMinaTION CHAPTER XII.— OF REPRODUCTION IN CRYPTO- GAMOUS OR FLOWERLESS PLANTS CHAPTER XII.— OF THE SPONTANEOUS MOVEMENTS AND VITALITY OF PLANTS . A é : Special Directions. 2 . Sensible Movements from Tritaon Spontaneous or Automatic Movements : : a Free Movements of the Sporesof Alge . . . Locomotion of Adult Microscopic Plants . . PART II. SYSTEMATIC BOTANY. CHAPTER I.— OF THE PRINCIPLES OF CLASSIFICA- TION. Individuals . Species . Varieties, Races, Hybrids or Gans beads Genera . 5 z Orders or Families, ‘Clases in ‘ Characters Binomial Neucntldade Natural and Artificial Systems CHAPTER U.—OF THE NATURAL SYSTEM OF BOT- Sketch of the Classes, &c. i: Nomenclature of Orders, Tribes, &c. 330 340 341 345 347 348 349 352 352 354 355 358 359 362 363 865 366 369 373 xii CONTENTS. CHAPTER IH.—ILLUSTRATIONS OF THE NATURAL ORDERS OR FAMILIES ‘ : CHAPTER IV.— OF THE ARTIFICIAL SYSTEM OF LINNZEUS : : é - F ‘ APPENDIX. Sians AND ABBREVIATIONS Directions FOR COLLECTING AND igcaniene oe &e. GLOSSARY OF BOTANICAL TERMS AND INDEX 373 511 517 518 521 ' THE BOTANICAL TEXT-BOOK. INTRODUCTION. GENERAL VIEW OF THE SCIENCE. 1. Botany is the Natural History of the Vegetable Kingdem. The vegetable kingdom consists of those beings (called Plants) which derive their sustenance from the mineral kingdom, that is, from the earth and air, and create the food upon which animals live. The proof of this proposition will be hereafter afforded, in the chapter upon the Food and Nutrition of Plants. The vegetable kingdom, therefore, occupies a position between the mineral and the animal kingdoms. Comprehensively considered, Botany accord- ingly embraces every scientific inquiry that can be made respect- ing plants, their nature, their kinds, the laws which govern them, and the part they play in the general economy of the world, —their relations both to the lifeless mineral kingdom below them, from which they draw their sustenance, and to the animal kingdom above them, endowed with higher vitality, to which in turn they render what they have thus derived. 2. There are three aspects under which the vegetable world may be contemplated, and from which the various departments of the science naturally arise. Plants may be considered either as indi- vidual beings; or in their relations to each other, as collectively constituting a systematic unity, that is, a vegetable kingdom; or in their relations to other parts of the creation,—to the earth, to animals, to man. 38. Under the first aspect, namely, when our attention is directed to the plant as an individual, we study its nature and structure, the 2 14 INTRODUCTION. kind of life with which it is endowed, the organization through which its life is manifested ; — in other words, how the plant lives and grows, and fulfils its destined offices. This is the province of PHYSIOLOGICAL BOTANY. This department of the science naturally divides into two branches, namely, Structural Botany and Vegetable Physiology, which arise from the different views we may take of plants. The study of their organization belongs to Srruc- TuRAL Borany, which includes every inquiry respecting their structure and parts. And this may again be divided into two branches, viz.: — 1st, VEGETABLE ANATOMY, or Puyrotony, the: study of the minute structure of vegetables as revealed by the microscope; and 2d, OrGanoGrariy, the study of the organs or conspicuous parts of plants, as to their external conformation ; in- cluding Morruoxoey (the study of forms), which relates to the conformation and the symmetrical arrangement of these organs, and the modifications they undergo, either in different species, according to the conditions of their existence, or in the same indi- vidual in the course of its development, —a department analogous to what is termed Comparative Anatomy in the animal kingdom. Thus in Structural Botany, whether we regard the external con- formation or the minute internal structure, the plant is viewed as a piece of machinery, adapted to the accomplishment of certain ends. On the other hand, the study of this apparatus in action, endowed with life, and fulfilling the purposes for which it was in- tended, and also of the forces which operate in it and by it, is the province of VEGETABLE PuysioLoecy. i 4. The subjects which Physiological Botany embraces, namely, Vegetable Anatomy, Organography, and Physiology, therefore, spring naturally from the study of vegetables as individuals, — from the contemplation of an isolated plant throughout the course of its existence, from germination to the flowering state, and the production of a seed like that, from which the parent stock origi- nated. These branches would equally exist, and would form a highly interesting study (analogous to human anatomy and_physi- ology), even if the vegetable kingdom were restricted to a single species. 5. But the science assumes an immeasurably broader interest and more diversified attractions, when we look upon the vegetable crea- tion as consisting, not of wearisome repetitions of one particular form, in itself however perfect or beautiful, but as composed of thousands Missing Page Missing Page PART I. STRUCTURAL AND PHYSIOLOGICAL BOTANY. 9. Tue principal subjects which belong to this department of Botany may be considered in the most simple and natural order by tracing, as it were, the biography of the vegetable through the successive stages of its existence,—the development of its essen- tial organs, root, stem, and foliage, the various forms they assume, the offices they severally perform, and their combined action in carrying on the processes of vegetable life and growth. Then the ultimate development of the plant in flowering and fructification may be contemplated,— the structure and office of the flower, of the fruit, the seed, and the embryo plant it contains, which, after remaining dormant for a time, at length in germination develops into a plant like the parent; thus completing the cycle of vegetable life. A preliminary question, however, presents itself. To under- stand how the plant grows and forms its various parts, and to get a clear idea of what growth is, we must first ascertain what plants are made of. Pa ra CHAPTER I. OF THE ELEMENTARY STRUCTURE OF PLANTS. Secor. I. Or ORGANIZATION IN GENERAL. 10. The. Elementary Constitution of Plants. In considering the materials of which vegetables are made, it is not necessary at the outset to inquire particularly into their chemical or ultimate com- position, that which they have in common with the mineral world. 2 * 18 THE ELEMENTARY STRUCTURE OF PLANTS. As they derive all the materials of their fabric from the earth and air, plants can possess no simple element which these do not supply. They may take in, to some extent, almost every element which is thus supplied. Suffice it for the present to say, that, of the about sixty simple substances now recognized by chemists, only four are essential to vegetation and are necessary constituents of the vege- table structure. These are Carbon, Hydrogen, Oxygen, and Nitro- gen. Besides these, a few earthy bodies are regularly found in plants, in small and varying proportions. The most important of them are Sulphur and Phosphorus, which are thought to take an essential part in the formation of certain vegetable products, Potas- stum and Sodium, Calcium and Magnesium, Silicon and Aluminum, Tron and Manganese, Chlorine, Iodine, and Bromine. None of these elements, however, are of universal occurrence, nor are they actual components of any vegetable tissue. 11. Their Organic Constitution, Although plants and animals have no peculiar elements, though the materials from which their bodies spring, and to which they return, are common earth and air, yet in them these elements are wrought into something widely different from any form of lifeless mineral matter. Under the influence of the principle of life, in connection with which alone such phenomena are manifested, the three or four simple constituents effect peculiar combinations, giving rise to a few organtzable elements, as they may be termed; because of them the organized fabric of the vege- table or animal is directly built up. This fabric is in a good degree simif@r in all living bodies; the solid parts, or t¢sswes, in all assuming the form of membranes, arranged so as to surround cavities, or form the walls of tubes, in which the fluids are contained. It is called organized structure, and the bodies so composed are called organized bodies, because such fabric consists of parts co-operating with each other as instruments or organs adapted to certain ends, and through which alone the living principle, under whose influence the structure itself was built up, is manifested in the operations which the plant .and animal carry on. There is in every organic fabric a necessary connection between its conformation and the actions it is destined to perform. This is equally true of the minute structure, or tissues, as revealed by the microscope, and of the larger organs which the tissues form in all plants and animals of the higher grades, such as a leaf, a petal, or a tendril, a hand, an eye, or a muscle. The term organ- ization formerly referred to the possession of organs in this larger ORGANIZATION. 19 sense, that is, of conspicuous parts, or members. It is now applied as well to the intimate structure of these parts, themselves made up of smaller organs through which the vital forces directly act. 12. Distinctions between Minerals and Organized Beings, In no sense can mineral bodies be said to have organs, or parts subor- dinate to a whole, and together making up an individual, or an organized structure in any respect like that which has just been spoken of, and is soon (as regards plants) to be particularly de- scribed. Without attempting to contrast mineral or unorganized with organized bodies in all respects, we may briefly state that the latter are distinguished from the former, —1. By parentage: plants and animals are always produced under the influence of a living body similar to themselves, or to what they will become, in whose life the offspring for a time participates; while in minerals there is no relation like that of parent and offspring, but they are formed directly, either by the aggregation of similar particles, or by the union of unlike elements combined by chemical affinity, independent of the influence, and utterly irrespective of the previous existence, of a similar thing. 2. By their development: plants and animals develop from a germ or rudiment, and run through a course of changes to a state of maturity; the mineral exhibits no phases in its existence answering to the states of germ, adolescence, and — maturity, has no course to run. 38. By their mode of growth: . the former increasing by processes through which foreign materials are taken in, made to permeate their interior, and deposited inter- stitially among the particles of the previously existing substance; that is, they are nourished by food;—while the latter are not nourished, nor can they properly be said to grow at all; if they increase in any way, it is merely by juxtaposition, and because fresh matter happens to be deposited on their external surface. 4, By the power of assimilation, or the faculty that plants and animals alone possess of converting the proper foreign materials they receive into their own peculiar substance. 5. Connected with assimilation, as a part of the function of nutrition, which can in no sense be predicated of minerals, is the state of internal ac- : tivity and unceasing change in living bodies; these constantly under- going decoposition and recomposition, particles which have served their turn being continually thrown out of the system as new ones are brought in. This is true both of plants and animals, but more fully of the latter. The mineral, on the contrary, is in a state of 20 THE ELEMENTARY STRUCTURE OF PLANTS. permanent internal repose: whatever changes it undergoes are owing to the action of some extraneous force, not to any inherent power. This holds true even in respect to the chemical combina- tions which occur in the mineral and in the organic kingdoms. In the former they are stable; in the latter they are less so in pro- portion as they are the more under the influence of the vital prin- ciple: as if in the state of unstable equilibrium, a comparatively slight force induces retrograde changes, through which they tend to reassume the permanent mineral state. 6. Consequently the duration of living beings is limited. They are developed, they reach maturity, they support themselves for a time, and then perish by death, sooner or later. Mineral bodies have no life to lose, and contain no internal principle of destruction. Once formed, they exist until destroyed by some external power; they lie passive under the control of physical forces. As they were formed irrespec- tive of the pre-existence of a similar body, and have no self-deter- mining power while they exist, so they have no power to determine the production of like bodies in turn. The organized being may perish, indeed, from inherent causes; but not until it has given rise to new individuals like itself, to take its place. The faculty of re- production is, therefore, an essential characteristic of organized beings. 13. Individuals. ‘The mass of a mineral body has no necessary limits; a piece of marble, or even a crystal of calcareous spar, may be mechanically divided into an indefinite number of parts, each one of which exhibits all the properties of the mass. But plants and animals exist as txdividuals; that is, as beings, com- posed of parts which together constitute an independent whole, that can be divided only by mutilation. Each owes its existence to a parent, and produces similar individuals in its turn. So each in- dividual is a link of a chain; and to this chain the natural-historian applies the name of 14. Species. The idea of species is therefore based upon this suc- cession of individuals, each deriving its existence, with all its peculi- arities, from a similar antecedent one, and transmitting its form and other peculiarities essentially unchanged from generation to generation. By species we mean abstractly the type or original of each sort of plant, or animal, thus represented by a perennial succession of like individuals: or, concretely, the species is the sum of such individuals. ORGANIZATION. 21 15. Life. All these peculiarities of organized, as contrasted with inorganic bodies, will be seen to depend upon this: that the former are living beings, or their products. The great charactcristic of . plants and animals is life, which these beings enjoy, but minerals’ do not. Of the essential nature of the vitality which so controls the matter it becomes connected with, and of the nature of the connection between the living principle and the organized structure, we are wholly ignorant. We know nothing of life except by the phenomena it manifests in organized structures. We have adverted only to some of the most universal of these phenomena, those which are common to every kind of organized being. But these are so essentially different from the manifestations of any known physical force, that we are compelled to attribute them to a special principle. We may safely infer, however, that life is not a product, or result, of the organization; but is a force manifested in matter, which it controls and shapes into peculiar forms,— into an apparatus, in which means are manifestly adapted to ends, and by which results are attained that are in no other way attainable. As we rise in the scale of organized structure from plants through the various grades of the animal creation, the superadded vital manifestations become more and more striking and peculiar. But the fundamental char- acteristics of living beings, — those which all enjoy in common, and which necessarily give rise to all the peculiarities above enumer- ated (12),—are reducible to two, viz.:—J1. the power of self- support, or assimilation, that of nourishing themselves by taking in surrounding mineral matter and converting it into their own proper substance; by which individuals increase in bulk, or grow, and maintain their life: 2. the power of self-division or reproduc- tion, by which they increase in numbers and perpetuate the species.* 16. Difference between Vegetables and Animals. The distinction be- tween vegetables and minerals is therefore well defined. But the line of demarcation between plants and animals is by no means so readily drawn. Ordinarily, there can be no difficulty in dis- tinguishing a vegetable from an animal. All the questionable * A single striking illustration may set both points in u strong light. The: larva of the fiesh-fly possesses such power of assimilation, that it will increase its own weight two hundred times in twenty-four hours; and such consequent | power of reproduction, that Linnzus perhaps did not exaggerate, when he affirmed that “three flesh-flies would devour the carcass of a horse as quickly as would a lion.”” 22 THE ELEMENTARY STRUCTURE OF PLANTS. cases occur on the lower confines of the two kingdoms, which exhibit forms of the greatest possible simplicity of structure, and of a minuteness of size that baffles observation. Even here the uncertainty may be attributable rather to the imperfection of our knowledge, than to any confusion of the essential character- istics of the two kinds of beings. If we cannot absolutely define them, or, at least, cannot always apply the definition to the actual and certain discrimination of the lowest plants from the lowest animals, we may indicate the special functions and characters of each. The essential characteristics of vegetables doubtless depend upon the position which the vegetable kingdom occupies between the mineral and the animal, and upon the general office it fulfils. Plants, as stated at the outset (1), are those organized beings that live directly upon the mineral kingdom,— upon the surrounding earth and air. ‘They alone convert inorganic, or mineral, into organic matter; while animals originate none, but draw their whole sustenance from the organized matter which plants have thus elab- | orated. Plants, having thus the most intimate relations with the mineral world, are generally fixed to the earth, or other substance upon which they grow, and the mineral matter on which they feed is taken directly into their system by absorption from without, and is assimilated under the influence of light in organs exposed to the air; while animals, endowed with volition and capable of respond- ing promptly to external impressions, have the power of selecting the food ready prepared for their nourishment, which is received into an internal reservoir or stomach. The permanent fabric of plants is composed of only three elements, Carbon, Hydrogen, and Oxygen. The tissue of animals contains an additional element, viz. Nitrogen. Plants, as a necessary result of assimilating their inorganic food, decompose carbonic acid and restore its oxygen to _the atmosphere. Animals in respiration continually recompose car- ‘bonie acid, at the expense of the oxygen of the atmosphere and the carbon of plants. These peculiarities will be explained and illus- trated in the progress of this work. Secr. IJ. Or tHe CreLyts anpD CELLULAR TisstE or PLANTs. 17. Tue question recurs, What is the organized fabric or tissue of plants, and how is vegetable growth effected? The stem, leaves, CELLULAR TISSUE. 23 and fruit appear to ordinary inspection to be formed of smaller parts, which are themselves capable of division into still smaller portions. Of what are these composed ? 18. Cellular Structure. ‘To obtain an answer to this question, we examine, by the aid of a microscope, thin slices or sections of any of these parts, such, for example, as the young rootlet of a seed- ling plant. A magnified view of such a rootlet, as in Fig. 1, pre- sents on the cross-section the appearance of a network, ithe meshes of which divide the whole space into more or less regular cavi- ties. A part of the transverse slice more highly magnified (Fig. 2) shows the structure with greater distinctness. A perpendicular slice (Fig. 8) exhibits somewhat similar meshes, showing that the cavities do not run lengthwise through the whole root without in- terruption. In whatever direction the sections are made, the cav- ities are seen to be equally circumscribed, although the outlines may vary in shape. Hence, we arrive at the conclusion, that the fabric, or tissue, consists of a multitude of separate cavities, with 1 2 4 closed partitions; forming a structure not unlike a honeycomb. This is also shown by the fact, that the liquid contained in a juicy fruit, such as a grape or currant, does not escape when it is cut in two. The cavities being called CELLs, the tissue thus constructed is termed CeLLuLar Tissur. When the body is sufficiently trans- lucent to be examined under the microscope by transmitted light, this structure may usually be discerned without making a section. FIG. 1. Portion of a young root, magnified. 2. A transverse slice of the same, more mag- nified 3. A smaller vertical slice, magnified. FIG. 4. Cellular tissue from the apple, as seen in a section. 5. Some of the detached cells from the ripe fruit, magnified. FIG. 6. Portion of a hair from the filament of the Spider Lily (Tradescantia), magnified : a, vestige of the nucleus. 24 THE ELEMENTARY STRUCTURE OF PLANTS. We may often loc _lirectly upon a delicate rootlet (as in Fig. 1), or-the petal of a flower, or a piece of thin and transparent sea-weed, and observe the closed cavities, entirely circumscribed by nearly transparent membranous walls. 19. Does this cellular tissue consist of an originally homogeneous mass, filled in some way with innumerable cavities? Or is it com- = ~Ss posed of an aggregation of little blad- OT ee ders, or sacs, which by their accumu- lation and mutual cohesion make up the root or other organ? Several cir- cumstances prove that the latter is the correct view. 1. The partition between two adjacent cells is often seen to be double; showing that each cavity is bounded by its own special walls. 7 2. There are vacant spaces often to be seen between contiguous cells, where the walls do not entirely fit together. These intercellular spaces are sometimes so large and numerous, that many of the cells touch each other at a few points only; as in the green pulp of leaves (Fig. 7). 3. When a portion of any young and tender vegetable tissue, such as an Asparagus shoot, is boiled, the elementary cells separate, or may readily be separated by the aid of fine needles, and examined by the microscope. 4. In pulpy fruits, as in the apple, the walls of the cells, which at first cohere together, spontaneously separate as the fruit ripens (Fig. 4, 5). 20. The vegetable, then, is constructed of these cells or vesicles, much as a wall is built up of bricks. When the cells are separate, or do not impress each other, they are generally rounded or spherical. By mutual pressure they be- come many-sided. In a mass of spheres each one is touched by twelve others; so, if equally impressed in every direction, the yielding cells, flattening each other at the points of contact, become twelve-sided; and in a section, whether transverse (as in Fig. 2) or longitudinal (as in FIG. 7. A magnified section through the thickness of a leaf of Illicium Floridanum, show- ing the irregular spaces or passages between the cells, which are small in the upper layer of the green pulp, the cells of which (placed vertically) are well compacted, so as to leave only minute vacuities at their rounded ends; but the spaces are large and copious in the rest of the leaf, where the cells are very loosely arranged. a, The epidermis or skin of the upper, 4, of the lower surface of the leaf, composed of perfectly combined and thick-walled cells, FIG. 8. View of a twelve-sided cell, detached entire, from tissue like that of Fig. 9. CELLULAR TISSUE. 25 Fig. 3), the meshes consequently appear six-» +d. If the organ is growing in one direction more than another, the cells commonly lengthen more or less in that direction. It is not necessary to detach a cell in order to ascertain its shape; that may usually be inferred from the outlines of the WW section in two or three directions. / 21. The shape of cells, there- fore, when they compose a tissue, depends very much upon the way WM in which they are arranged and ; press upon each other. When separate, as they are in the sim- plest vegetables, or when nearly free from each other, like the hairs on the surface of many plants, they determine their own form by their mode of growth, and assume a great variety of shapes, some of which are shown in the follow- ing illustrations. The natural and primitive form may be said to be roundish or spherical. By increased growth in one direction they become oblong or cylindrical, or, when still more extended, they become tubes. Of this kind are the hair-like prolongations on the surface of young rootlets (shown just beginning in Fig. 1, and more elongated in Fig. 135-137); and the fibres of cotton are slender hairs, consisting of single, very long cells, growing on the surface of the seed. 22. The walls of young cells are transparent and colorless. The various colors which the parts of the plant present, the green of s the foliage, and the vivid hues of the corolla, do not belong to the tissues themselves, but to the matters of different colors which the cells contain (92). As they become older, the walls often lose most of their transparency, and even acquire peculiar colors, as in the heart-wood of various trees. 23. The cells vary greatly in size, not only in different plants, but in different parts of the same plant. The largest are found in ¢ aquatics, and in such plants as the Gourd, where some of them are as much as one thirtieth of an inch in diameter. Their ordinary bd . * . diameter in vegetable tissue is between g}5 and ys'y5 of an inch. FIG. 9. Asmall portion of the tissue of pith, seen both in transverse and longitudinal section, much magnified. 3 26 THE ELEMENTARY STRUCTURE OF PLANTS. The smaller of these sizes would allow of as many as 1728 millions of cells in the compass of a cubic inch! 24. Some idea may be formed respecting the rate of their pro- duction, by comparing their average size in a given case with the known amount of growth. Upon a fine day in the spring, many “stems shoot up at the rate of three or four inches in twenty-four hours. When the Agave or Century-plant blooms in our conser- vatories, its flower-stalk often grows at the rate of a foot a day; it is even said to grow with twice that rapidity in the sultry climate to which it is indigenous. * In such cases, new cells must be formed at the rate of several millions a day. The rapid growth of Mushrooms has become proverbial. A gigantic species of Puff-ball has been known to attain the size of a large gourd during a single night: in this case the cells of which it is composed are computed to have been developed at the rate of three or four hundred millions per hour. But this rapid increase in size is owing, in great part, to the expansion of cells already formed. 25. The Cell as a living Organism. Thus far we have considered only the membrane or permanent wall of the cell,—that which makes up the tissue or fabric of plants, and which remains un- altered, and performs some of its offices even long after life has departed. But we should now regard the cell as a living thing, and consider what the wall encloses, and what operations are effected in it. For the whole life of the plant is that of the cells which compose it; in them and by them its products are elaborated, and all its vital processes carried on. 26. A young, living, vitally active cell consists, — 1st, of the membrane or permanent wall, already described; 2d, of a delicate mucilaginous film, lining the wall, called by Mohl the primordial utriele ; 3d, most commonly the centre of the cell, and sometimes the greater part of the cavity, is occupied by the nwelews, a soft solid or gelatinous body; and 4th, the space between the nucleus and the lining membrane is filled at first by a viscid liquid, called protoplasm, having an abundance of small granules floating in it. As the cell enlarges by the growth and expansion of its walls, the space between the latter and the nucleus becomes filled with watery sap, leaving the protoplasm merely as a viscid coating of the inside of the primordial utricle, and of the nucleus, if this remains. 27. The cell-membrane, or proper wall of the cell, is chemically composed of the three elements, carbon, hydrogen, and oxygen, SUP aban alee FORMATION AND GROWTI OF CELLS. 27 and has the same composition (when pure) in all plants. This sub- stance — the general material of vegetable fabric —is called Céedlu- lose. Its chemical composition is Carbon 12, Hydrogen 10, and Oxygen 10. It is insoluble in water, alcohol, ether, and dilute acids, and, like starch, it turns blue when acted upon by iodine, aided by sulphuric acid. \The primordial utricle, or delicate lining of the cell, appears to have the same composition as protoplasm. It may be regarded as an exterior portion of the mucilaginous protoplasm, which has acquired the consistence of a very soft membrane. } In addition to the three elements, carbon, hydrogen, and oxygen, pro- toplasm contains nitrogen, in considerable quantity. It is colored yellow by iodine, and is coagulated by alcohol and acids. The / substance of which it principally consists is named by chemists | Proteine, and is known among vegetable products. under various forms, viz. as diastase, gluten, fibrine, vegetable albumen, and the like. Such being the nature and the parts of the cell, we may now consider 28. Its Formation and Growth. Under this head we may briefly explain, as far as we are able,— 1st, how cells are originated; and 2d, how they are multiplied. 29. Original Cell-Formation, Cells are originated only within other cells,{or at least in matter which las been contained in and elab- orated by them.) They appear to be formed in the following man- ner. A portion of the elaborated or organizable matter, which abounds in the fluid contents of living cells, condenses into a soft solid, or half-solid and more or Jess transparent mass, usually of a globular or oval shape, the nucleus: around this nucleus a portion of protoplasm accumulates; a denser film of the same substance forms on the surface of the protoplasm, giving the mass a definite outline; this is the primordial utricle: upon this a layer of cellulose is soon deposited, making the cell-membrane. The nuclei in such cases are very minute, and either few or many of them may be formed in one parent cell, and be developed in this way into new cells, which are, at least at first, of small size as compared with the parent cell (Fig. 88). A variation of this mode occurs in many of the lower Alge, where a considerable portion of the contents of a cell con- denses into a rounded mass, the surface becomes coated with a layer of protoplasm or primordial utricle, and this with a membrane of cellulose, completing the cell. Thus, in Vaucheria the whole green contents at the end of certain branches condense into a CODD ce CE 28 THE ELEMENTARY STRUCTURE OF PLANTS. globular mass (Fig. 89), which at length is coated with cell-mem- brane, and so becomes a cell of considerable size. In Zygnema (Fig. 635) the whole contents of two cells are united, and give rise in a similar way to one new cell. 30. In the higher or flower-bearing division of plants, this process of original or free cell-formation occurs only in the sac in which the embryo is formed. The first cell of the embryo originates in this way; but all the subsequent growth is effected by a different pro- cess. In the simplest grade of plants it occurs more frequently, but only in the formation of those bodies which in them take the place and fulfil the office of seeds; that is, which serve for repro- duction. ‘ 31. It appears, therefore, that the azotized or nitrogenous mate- rial, the proteine, plays the most important part in the formation of cells. The layer of protoplasm, with its delicate coating, the primordial utricle, precedes the proper cell-membrane, and in some unexplained way causes the latter to be deposited on its sur- face. And these soft nitrogenous parts are the seat of the whole vital activity of the cell. The wall of cellulose may be regarded as a kind of protecting coat or shell, which constitutes the per- manent fabric of the plant, but is alive only so long as the living protoplasmic lining remains. 52. In a growing young cell, the walls enlarge much faster than the nucleus, and the latter soon ceases to grow at all. It is there- fore left in the centre, or else remains adherent to the wall on one side, where traces of it may often for a long time be detected; or more commonly it dissolves and disappears altogether. At length, in older cells, the liquid contents and the protoplasmic lining also disappear, and only the walls of cellulose remain as the permanent vegetable fabric. The fabric of plants, however, as has already been stated, is not built up by original cell-formation, but by 33. Cell-Multiplication, A living cell, formed in whatever manner, has the power of multiplying it-elf by dividing into two, these again into two more, and so on. By this process the single cell, which each vegetable begins with, gives rise to the embryo or rudimen- tary plantlet contained in a seed; and by it the embryo in germina- tion develops into a seedling, and the seedling into the herb, shrub, or tree. Vegetable growth accordingly consists, — Ist, of the growth or expansion of each cell up to its full size, which ordinarily is very soon attained; and 2d, of what is called their mer/smatiec multiplica- FORMATION AND. GROWTII OF CELLS. 29 tion, namely, the successive division of cells into two. This takes place only when they are young and active, and mostly before they are full-grown. It is effected by the formation of a partition across the cavity of the cell, dividing it into two (Fig. 10-14). In this way, a single cell gives rise to a row of connected cells, when the division takes place in one direction only; or to a plane or €. solid mass of such cells, when it takes place in two EY or more directions, thus producing a tissue. is 34, In this multiplication of cells by division, as in the original formation of a cell, the contents and the protoplasmic lining play the most im- Q portant part. The nucleus, when pres- ent, as it commonly is, first divides into two (Fig. 11) ; then the lining mem- brane, or primordial utricle, is gradu- ally constricted or infolded at the line of division, which, soon meeting in the centre, separates the whole contents into two parts by a delicate partition; upon this a layer of cellulose is de- posited as a permanent wall, which ‘completes the transformation of one cell into two (Fig. 21, 22). 85. Cells multiplying in this way, and remaining united, build ‘up a row or a surface of cells, or a solid tissue, ac- cording to the mode of division. But in many of the simplest plants, growing in water, the cells separate as they form, and be- come independent. A microscopic plant very common in shallow pools in early spring, forming slimy green masses, well illustrates this, as shown in Figures 15-19. At each step of this multipli- cation new cell-membranes are formed, and the old one, for instance, the wall of Fig. 15 and the common envelope of the two in Fig. 17, FIG. 10. A-young cell,—the first cell of an embryo,— with its nucleus in the centre. 11 The same, with its nucleus divided’ into two, and a cross-partition beginning to, form. 12. The partition completed, so converting the first cell into two. 18 The lower one again divided into two, making three cells inarow. 14. The fourth cell converted into four by a division i in two directions, forming seven ‘cells in all. FIG. 15. A single cell, or plant of a kind of Palmella, magnified. 16. The same dividing, and, 17, completely separated into two. 18, Each of these dividing in the opposite diss. tion, four cells are produced, 19. Each of these again dividing into four, they produce a cluster of sixteen cells, 8* 30 THE ELEMENTARY STRUCTURE OF PLANTS. and of the four in Fig. 18, forms a part of the thickness of the coat of each, or is destroyed by the distention; or else (as in the present instance) is dissolved into a jelly A slight modification of this process occurs in 36. Free Cell-Multiplication within a Mother-Cell, which is intermediate in character between original cell- formation and ordinary cell-multi- plication. JIcre the whole contents of a living cell, by constriction or infolding of the primordial utricle, divide into two or four parts (as in Fig. 81-83), and these may be again divided;—each portion has a coat of cellulose deposited over its surface, and thus so many sep- PES a arate cells are produced, lying loose in the cavity of the mother-cell, whose thin and now dead cellulose-wall, which is all that is left of it, usually disappears sooner or later, or is broken up by the growth of the new crop of cells within. In this way are formed the grains of pollen in the id anther, and the spores, or bodies which answer to secds, in the higher grades of Flowerless Plants. 37. Cell-Growih. By appropriating assimilated matter, the young cell increases in size until it attains its full growth; its walls, as they expand and enclose a greater space, not diminishing, but rather inercasing in thickness. Therefore it not merely enlarges, but grows. If it grows equally in all directions, and is not pressed upon on any side, it keeps a spherical form; if it grows more in one direction than in any other it becomes oblong or cylindrical. In this way a cell is sometimes drawn out into a slender tube; of which the fibres of cotton, and the cells of fibrous bark (Fig. 49) are good examples. In the simplest plants, cells sometimes continue to elongate almost FIG 20. The branching summit of a plantlet of Conferva glomerata, magnificd; after Mohl ‘he plant consists of a row of cells, filled with green grains floating in liquid: the long cell at the upper end is seen in the process of dividing into two, at a, by constriction of the primordial utricle. FIG. 21. A portion of the same at a, more magnified, showing the formation of the par- tition. 22. Same, with the partition completed. CIRCULATION IN CELLS. 31° indefinitely from one end, by a sort of gemmation or budding growth, while all the rest remains stationary, or while the opposite extremity is dead or decaying. Fig. 20 would represent a case of the kind, except that partitions form, as the upper end grows on, dividing the tube into a row of cylindrical cells. Sometimes a new point of growth commences on the side of a cell, so giving rise to 38. Branching Cells. The hair- like bodies that copiously appear on the surface of young rootlets furnish examples of the kind, as is shown in Fig. 1,23, 24. More : conspicuous examples are furnish- ; ed by certain Algz of the simplest structure, where the cell branches A profusely as it elongates, but the tubes are all perfectly continu- ous throughout; as in Botrydium =e (Fig. 88), where an originally spherical cell is extended and ramified below in the fashion of a root; in Vaucheria (Fig. 89), where a slender tube forks or branches sparingly; and in Bryopsis (Fig. 91), where numerous branches are symmetrically arranged in two opposite rows, like the plume of a feather. In these cases, the fully developed plant, with all its VV ERING branches, is only one proliferous aN YK WETS cell, extended from various points 1 RS ZX. SRE dy this faculty of continuous bud- LIB SK ding growth. The mycelium or = spawn of Mushrooms, and the in- as tricate threads of Moulds (Fig. 92~—94) are formed of very attenuated branching cells. And in Lichens and many Fungi, cells of this kind are densely interwoven into a filamentous tissue (Fig. 25). 39. Cyclosis or Circulation in Cells. In all young cells, probably, at least at some period, the fluid protoplasm interposed between the cell-walls and the watery sap is in a state of movement. Under 24 FIG. 28 Magnified cellular tissue from the rootlet of a seedling Maple; some of the ex- ternal cells growing out into root-hairs., 24 A few of the cells more highly magnified. FIG 25. Entangled, filamentous, branching cells from the fihrous tissue of the Reindeer Lichen (Cladonia rangiferina), magnified. : 32 THE ELEMENTARY STRUCTURE OF PLANTS. the microscope, currents, rendered more visible by the contained granules or solid atoms, are seen flowing around the cell, or around some portion of its periphery, in a circuit which returns upon itself The cause of this curious phenomenon and the object it subserves are unknown; but it is doubtless a vital circulation, and not a mechanical movement. In most plants it is not to be seen in mature cells. But it may be observed in many water-plants when full-grown, and in the hairs on the surface of a great variety of land-plants. The string of bead-like cells which compose the jointed hairs of the common Spider Lily (Tradescantia, Fig. 6) show this circulation well, under a magni- fying power of about four hundred diameters. With this power, a set of thread-like currents may be seen to move between the cell-wall and the enclosed colored contents, traversing the cell in various directions, without much regularity, ex- cept that the streamlets appear to radiate from, and return to, the nucleus. The large stinging hairs of Nettles, and the bristles on the ovary of Circea, show this circulation very well. In the latter, instead of the separate and slender stream- lets of Tradescantia, we perceive a broad and con- tinuous stream flowing up on one side of the long cell, around the summit, and down the opposite side. This circulation may be more readily ob- served in the cells of many aquatic plants. In Chara and Nitella,—— plants composed of large cells lined with grcen granules,—a magnifying power of fifty or one hundred diameters shows the circulation very well. And the leaves of Vallisneria spiralis (the Tape-grass or Eel-grass of fresh water) are still more beautiful objects, when magnified from two to four hundred diameters. Through their nearly transparent walls, a current of protoplasm, usually carrying with it some globular loose grains of chlorophyll, may be seen coursing up the entire breadth of the wall of each cell, across its summit, down the opposite side, and across the other end to complete the circuit; and often the current is strong enough to set the large nucleus, or a central mass FIG. 26. A few cells of the leaf of Naias flexilis, highly magnified, showing the circulation ; the direction of the currents indicated by arrow-heads. (Drawn by IH. J. Clark ) CIRCULATION IN CELLS: ENDOSMOSE. 33 of green grains, into revolution. The circulation is more active in the subjacent than in the superficial layer of cells, although occasion- ally conspicuous in the latter: it is stopped or retarded by lower- ing, and accelerated by raising the temperature. The motion often appears to be quite rapid; but it should be remembered that this is magnified as well as the object. Mohl states it to be very slow, not more than the ;4g of a line per second in the hairs of Tradescan- - tia. But in Vallisneria the green grains sometimes complete the circuit of a cell of the ordinary size in less than twenty seconds ;— and in the bristles on the fruit of Cireaa, which are half a line long, Mr. H. J. Clark has seen the revolution completed in about a minute. The circulation in one cell is totally independent of that in the adjacent ones. The current is commonly seen to flow in opposite directions on the two sides of a partition, or to move on one side when quiescent on the other. Cyclosis, whatever its nature may be, evidently has nothing to do with the 40. Transference of Fluid from Cell to Cell. All cells, at least when” young and living, have perfectly closed walls. There is no passage from one to another through visible openings or pores, although such openings may be formed in older parts. Nevertheless fluids do permeate cell-walls, as they do all organic membranes. And in this way water, along with other matters which the roots absorb, is carried up into the leaves even of the topmost bough of a tree;. passing in its course through many millions of apparently water-: tight partitions. However governed by forces inherent in the plant, the actual transference of fluids from one cell to another takes place in obedience to a physical law, i. e. by the process which has been named Endosmose or Endosmosis,* and which operates in dead parts ‘ * End and se are names given by Dutrochet (a French physi- ologist) to « physical process of permeation and interchange which takes place in fluids, according to the following law, briefly stated. When two liquids of unequal density are separated by a permeable membrane, the lighter liquid or the weaker solution will flow into the denser or stronger, with a force proportioned to the difference in density (endosmosis) ; but at the same time, a smaller portion of the denser liquid will flow out into the weaker (exosmosis). Thus, if the lower end of an open tube, closed with a thin mem-- brane, such as a piece of moistened bladder, be introduced into a vessel of pure water, and a solution of sugar in water be poured into the tube, the water from the vessel will shortly be found to pass into the tube, so that the column of liquid it contains will increase in height to an extent proportionate to the strength of the solution. At the same time, the water in the vessel will become 84 THE ELEMENTARY STRUCTURE OF PLANTS. as well as in living ones. The law is, that when two fluids of un- equal density are separated by an organic membrane, or by any thin and porous partition, an interchange takes place,— more or less rapidly according to the thinness of the intervening partition and the difference in the density of the fluids on the two sides, —a small quantity of the denser fluid passing into the lighter, but a much larger portion of the lighter passing into the denser; and this continues until the two fluids are brought to the same density. Hence, as the cells of a living plant always contain organizable or assimilated matter (mucilage, protoplasm, &c.), which especially abounds in young and growing parts, the cells of the rootlets are always able to imbibe the ordinary moisture which is presented to them in the soil; and by diminishing the portion of water, or in any other way increasing the density of the liquid contents of the cells of any part of the plant, a flow may be attracted into them. 41. Inerease of Cell-walls in Thickness. Up to a certain point, the walls of cells thicken as they grow by the incorporation of new matter interstittally into their substance. After attaining, for the most part rapidly, a definite size, the cell ceases to enlarge, and its wall no longer incorporates new materials. Some cells remain with exceedingly thin and delicate walls. But in most cells that make part of the permanent structure of a plant, the cell-membrane con- tinues to thicken long after it has ceased to enlarge. Then the new matter can no longer be incorporated with the old; but the thickening is now effected by iis deposition on the inner sur- face of the original membrane, between it and the protoplasmic slightly sweet ; showing that a small quantity of sirup has passed through the pores of the membrane into the water without, while a much larger portion of water has entered the tube. The water will continue to enter the tube, and a small portion of sirup to leave it, until the solution is reduced to the same strength as the liquid without. If a solution of gum, salt, or any other sub- stance, be employed instead of sugar, the same result will take place. If the same solution be employed both in the vessel and the tube, no transference or change will be observed. But if either be stronger than the other, a circulation will be established, and the stronger solution will increase in quantity until the two attain the same density. If two different solutions be employed, as, for instance, sugar or gum within the tube, and potash or soda without, a circula- tion will in like manner take place, the preponderance being towards the denser fluid, and in a degree proportionate to the difference in density. Instead of ani mal membrane, any vegetable matter with fine pores, such as a thin piece of wood, ' or even a porous mineral substance, may be substituted, with the same result. , THICKENING OF THE WALLS OF CELLS. 85 lining. Every degree of this secondary deposition occurs, from a slight increase in the thickness of the membrane to the filling up of the greater part of the cavity of the cell. Any hard wood furnishes illustrations of this. Indeed, the difference between sap- wood and heart-wood in trees is principally owing to the increase of this deposit, which converts the former into the latter; as may be seen by comparing, under the microscope, the tissue of the older with that of the newest rings of wood, taken from the same tree. Figures 196 —199 show this in a piece of oak wood. Jig. 29 represents a highly magnified cross-section of some wood- cells from the bark of a Birch, with their calibre almost obliterated in this way. It is by the same process that the stone of the peach, cherry, &c. acquires its extreme hardness. Similar indurated cells of the same kind are met with even in the pulp of some fruits, as in the gritty grains, which every one has noticed in the flesh of certain pears, especially of the poorer sorts. ‘Ow A section of a few cells of the OW kind is represented in Fig. XQ) >) 27, with their cavity much ) reduced and rendered very . irregular by this internal in- crustation. Similar cells may be found in some parts of the tissue even of such juicy fruits as the cranberry and the blueberry (Fig. 28). 42. The thickening matter, when pure, is of the same nature as the original membrane of the cell, that is, it consists of cellulose (27). But with this are mingled some mineral matters, — small quantities of which must needs be dissolved in the water which the plant imbibes by its roots, and be deposited in the cells of the FIG. 27 Magnified section of the gritty cells of the pear; the cavity almost filled with an internal deposit. 28. Similar cells found in the pulp of the blueberry (Vaccinium corym- bosum). FIG. 29. Highly magnified cross-section of a bit of the old liber of the bark of the Birch; - the tubes nearly filled with a deposit of solid matter in concentric layers. (From Link ) FIG. 80. Highly magnified wood-cells (seen in transverse and longitudinal section), from the root of the Date Palm ; showing the thickening deposit in layers, and some connecting canals or pits. (From Jussieu, after Mirbel.) 36 THE ELEMENTARY STRUCTURE OF PLANTS. wood, and especially in those of the leaves, where much of the water escapes by evaporation, — and sometimes certain coloring matters also, such as give the different tints to heart-wood, &c. Even when purified as much as possible from all admixture of foreign materials, the secondary deposit is said to differ a little from cellu- lose, or original cell-membrane, in containing a somewhat larger proportion of carbon and hydrogen: it is therefore richer in combus- tible matter. Forming as it does the principal part of the weight of wood (lignum), it has received the name of Lignine (also that of Selerogen) ; but it is only cellulose a little modified. This differ- ence in chemical composition, however, shows why the hard woods, such as hickory and oak, which abound in this lignified deposit, should be more valuable for fuel, weight for weight, than the soft woods, which have little of it; at least, when the latter are not charged with resinous matter.* 43. The section of the wall of a cell thickened by internal deposit, when moderately magnified, commonly appears to be homo- geneous and uniform. But under a high magnifying power it may often be distinguished more or less distinctly into successive con- centric layers (Fig. 27-81). However this may be, it rarely hap- pens that the thickening deposit is spread evenly over the whole inner surface of a cell. It is commonly interrupted or much thinner at some places, so as to give the diminished cavity of the cell very irregular outlines (as in Fig. 27, 28); or else it is wanting at cer- tain small and definite spots, which, being more transparent, when looked down upon from the outside appear like holes or pores (Fig. $2, 56, 57) or slits (Fig. 58, 59), according to their shape. In this way are formed the various 44. Markings of the Walls of Cells. ‘These, whether in the form of bands, spiral lines, dots, or apparent pores, all arise from the unequal * From the manner in which the thickening takes place, it would appear that the innermost layers must always be the most recent. But M. Trécul has con- vinced himself that the primary ccll-membrane sometimes produces a secondary one outside of itself, as well as on the inside, so that the original cell-wall is intermediate. And also, that, when the thickening deposit is wholly within the primary wall, the intermediate layers are occasionally sccreted in some way by the outer or inner ones, and therefore more recent than the inner. Unlikely as all this seems, M. Trécul’s investigations are entitled to great attention. His claborate memoir, upon Secondary Formations in Cells, is published in the Annales des Sciences Naturelles, 4th ser. Vol. II. 1854. MARKINGS OF THE WALLS OF CELLS. 37 distribution of the secondary deposit. They are portions of the walls which are either thinner or thicker than the rest. These markings display the greatest variety of forms, many of them of surpassing elegance. The principal kinds occur with perfect uni- formity in each species or family, and in definite parts of the plant; / so that, in a multitude of cases, the sort of plant may be as certainly identified by the minute sculpture of its cells alone, as by more con-( spicuous external characters. They are preserved even when the tissue is fossilized, and the iy external form, with every outward appearance of or- ganization, is obliterated. Through thin slices and other contrivances, the hid- den structure is revealed under the microscope, and thus the true nature of the earth’s earliest vegetation may be often satisfactorily made out. In this way, and by taking advantage of the fact, that the secondary deposits in the cells contain a good deal of mineral matter, which is left behind in the ashes, Professor Bailey was able first to dis- ° Tee eae 00C000EN- 0.66999 00000 000 9900000 O,0 CNET G) 0 x oo ee TS Tap Se peepee 2 aGe 00 9 9.000 cover vegetable structure in anthracite i se A coal.* The simplest and commonest = Es markings are those which appear as ss 2 pores or holes, but are really 45. Dots or Pits, such as those on the cells of the pith of Elder (Fig. 38), and oe, * See Silliman’s American Journal of Science and Arts, New Series, Vol. I. FIG. 81. Magnified cross-section of a small portion of heart-wood of the Plane-tree or Buttonwood (Pl identalis). 82. A corresponding longitudinal section, parallel with the circumference. a, The dotted woody tissue ; the lower ends of the two cells to which the letters are appended are divided lengthwise, so as to show the irregularly thickened calibre ; the others are mostly entire, showing the dots: in the cross-section the secondary deposit is seen to form indistinct layers, and some of the dots to form canals of lateral communication. b, Dotted ducts: the middle one in the longitudinal section is obliquely jointed. c, Medullary ia FIG. 33. Portion of four cells of the woody tissue, with both transverse and longitudinak section, highly magnified, showing the canals or deep pits in the thickened walls, and their apposition in adjoining cells: on the cross-section the layers of deposit are more plainly visible. 4 38 THE ELEMENTARY STRUCTURE OF PLANTS. upon what are called dotted ducts ; as in Fig. 32, 6, and Fig. 56, 57. All markings of this kind are thin spots, which, for some reason, have not partaken in the general thickening of the wall. Although they are not primarily pores or real perforations, yet they often be- come so with age, by the destruction of the thin primary membrane, after the cell has lost its vitality. Fig. 32 shows these dots on the wood-cells and the ducts of the Plane-tree. And Fig. 33, represent- ing some of the wood-cells more highly magnified, explains their real nature, namely, as deep pits in the thick wall. Tt will be seen that the pits of contiguous cells exactly correspond; showing that there is nothing accidental in the origin or the arrangement of these markings. They are manifestly designed for maintaining communi- cation between contiguous cells, and for the ready conveyance of the sap from cell to cell, notwithstanding the thickening of their walls. Of similar nature, although of greater size, are the so-called ©) © ©Oo0o0 008 © © 34 35 46. Dises or Circular Markings of Coniferous Wood (Fig. 34-57), These are of universal occurence in the wood of Pines, Firs, and all that family of Coniferous trees; and something very like them, if not the same, occurs in the Winter’s-Bark tree (as long ago shown by Mr. Brown), the Star-Anise, and even in the Magnolia, and other aromatic trees. They may readily be seen in a thin Pine shaving, taken parallel with the silver-grain: for in the Pine family they are nearly all found on the lateral walls of the cells, few or none being visible on the sides which look towards the bark or towards the FIG. 34. Piece of a Pine shaving, magnified, to show the discs or thin spots which appear on the cells of all Coniferous wood. 385. A separate cell of the above, more strongly magnified. FIG. 86. A small portion of five cells of White-Pine wood magnified; seen both in trans- verse and longitudinal section. «, @, discs, in transverse section: b, b, discs as looked down upon in longitudinal view. FIG. 37. A highly magnified transverse section of one complete wood-cell, connected with adjacent cells, and of a disc (a): after Mohl. MARKINGS OF THE WALLS OF CELLS. 39 pith; while the smaller dots, of the ordinary kind, as on the wood- cells of the Plane-tree (Fig. 32), are most abundant on the sides that look towards the centre and the circumference of the trunk. The nature of these disc-like markings is plainly revealed in the accom- panying microscopical dissections of White-Pine wood (Fig. 86, 87). They are thin places, which have not received the thickening deposit that has lined all the rest of the calibre, or have received it in a lesser degree. Those of contiguous wood-cells always exactly cor- respond, just as do the smaller dots or pits of ordinary wood; and the two cell-membranes separate from each other, each being some- what curved inward, thus leaving a lenticular space between them, like that between two watch-glasses put together by their edges. 47. Bands, Rings, or Spiral Markings, These are mostly definite portions of the wall more thickened than the rest; as is shown by the spiral vessel, where the secondary formation is restricted to a delicate thread, capable of being unwound (60), and particularly by the remarkably thick plate which winds around in the cells of certain Cacti, like a spiral staircase (Fig. 42, 43). The accompany- ing figures illustrate various forms of banded, reticulated, or spiral markings. 48. When the primitive walls of such banded cells remain very thin and delicate, they are apt to become obliterated at maturity, leaving the firmer fibrous markings as separate threads. This FIG. 88. A cell of the pith of Elder, marked with oblong dots, which are thin places. FIG. 39. Cells of the leaf of Sphagnum, or Peat-Moss, marked with a spiral fibre. FIG. 40-48. Spirally banded cells from species of Cactus, after Schleiden. FIG. 44. Hairs from the seed-coat of Dipteracanthus strepens ; one with a spiral band, the other with a set of rings developed on the inner surface of the tube. FIG. 45. Tissue from the lining of the anther of Cobsea scandens ; where, the delicate walls of the cells being soon obliterated, nothing but the fibrous bands with which they were marked remain. 40 THE ELEMENTARY STRUCTURE OF PLANTS. occurs in the tissue that lines the walls of the anther; and in this way the spirally marked tubes (called laters) which occur in the spore-cases of the Hepatic Mosses or Liverworts are converted into elastic spiral threads. Of a similar nature are the 49. Gelatinous Coils, or soft spiral threads, such as occur in the hairs or projecting cells which invest the coats of many seeds or seed-like fruits, and which when moistened often uncoil and are projected from the bursting cell in a striking manner. When water is applied, this is absorbed by endosmosis (40), the gelatinous threads swell, burst the cell-membrane, and gush out in the form of uncoil- ing mucilaginous fibres or bands. Good examples of the kind are furnished by the secds of Collomia and Gilia, and by hairs or papillee on the seed-like fruits of numerous species of Senecio and the allied genera. Those of Crocidium project a thick, mucilaginous, twisted band, in place of a‘thread. They may subserve a useful purpose in fixing light seeds to the ground where they lodge, by means of the moisture of the first shower they receive. 4 Sect. II. Or tue Kinps or TRANSFORMATIONS OF CELLULAR TissuE; viz. Woopy Tissvr, Ducts, ETc. 50. Tuer statements of the preceding section apply in general to the cells of which all plants are composed, irrespective of the mani- fold forms they may assume, and of some peculiar transformations they may undergo. Some of these should now be specified; as they give rise to kinds of tissue so unlike the ordinary cellular, in outward appearance at least, that they have always been distin- guished by special names. We allude particularly to Woody Tissue or Woody Fibre, and Vaseular Tissue or Vessels, of various forms. These, although formerly regarded as of independent origin, are now known to be mere modifications of one common type, the cell, and are produced in the same mode as ordinary cells. So all the statements of the foregoing section, in respect to the formation, mul- tiplication, and growth of cells, are equally applicable to these also. Some kinds differ from ordinary cells in shape alone; others result from their combination or confluence. This is shown in two ways: first, by noting the intermediate gradations which may be found be- tween every particular sort; and secondly, by watching their de- velopment and tracing them directly from their earliest condition, as PARENCHYMA AND PROSENCHYMA. 41 ordinary cells, to the peculiar forms they soon assume. In enumer- ating the kinds of vegetable tissue, we commence with cellular tissue strictly so called, or 51. Parenchyma. This is the distinctive name for ordinary mem- branous cellular tissue in general, such as that which forms the pith ,of stems and their outer bark. In the most restricted application, it belongs to such tissue when composed of angular or polyhedral cells (as in Fig. 1-3, 9, &c.); the name of Merenchyma having been proposed for the looser tissues (as in Fig. 7, and in the pulp of leaves and fruits generally), formed of rounded or ellipsoidal cells, that is, where they do not mutually impress each other into plane faces. But this distinction vanishes in the numberless intermediate states; and the name of Parenchyma is applied to both. That in which the walls touch each other, more or less, and leave interven- ing spaces where the ends or sides are rounded off, is termed by Schleiden incomplete parenchyma ; and that in which the cells are in perfect contact on every side, complete parenchy- ma. The latter is regular, when the cells are dodecahedral or cubical; elongated or prismatic, when extended longitudinally ; and tabular, when cubical cells are much flattened; one kind of which, called the muriform, because the laterally compressed cells appear in the magnified section like courses of bricks in a wall, is seen in the silver-grain of wood (Fig. 192). \\ 52. Prosenchyma is the general name for tissues formed of elongated cells, especially those with pointed or oblique extremities. Every gradation may be traced between this and parenchyma. As to length, such cells vary from fus¢form, or spindle- shaped, only three or four times longer than broad, to tubular, and to tubes so long and narrow that they are commonly called fibres. The most char- acteristic form of prosenchyma is \, 53. Woody Tissue, (Plewrenchyma of Meyer and Lindley. Woody Fibre of the older authors.) Wood, which makes up so large a part of trees FIG. 46. Some wood-cells of the Plane-tree or Buttonwood, highly magnified: u, thin spots in the walls, looking like holes ; on the right-hand side, where the walls are cut through, these (b) are seen in profile. 4% 42 THE ELEMENTARY STRUCTURE OF PLANTS. and shrubs, and some part of almost all ordinary herbaceous plants, is wanting in Mosses and plants of still lower grades, such as Lichens, Sea-weeds, and Fungi. That is, in the latter there is no formation corresponding to the wood of higher plants, although many of them exhibit, at least in certain parts, cells more or less elongated, or even drawn out into tubes or hollow fibres of greater length and tenuity than are those of ordinary wood; such, for instance, as the interlaced fibrous tissue of Lichens (Fig. 25). Nor, on the other hand, does the proper wood of trees (except in the Pine family) consist entirely of what is named woody tissue, but has some other sorts variously intermingled with it. Indeed, there are some trees whose wood is almest entirely composed of true parenchyma, or of large dotted cells; while in stone-fruits, and, many like cases, common parenchymatous cells acquire by in- ternal deposit (41) a ligneous consistence, and even greater hardness than ordinary wood (89). Nevertheless, the principal and charac- teristic component of wood in general is thick-walled prosenchyma. So that this takes the name of woody tissue even in the bark and leaves, as well as in the trunk. Fig. 32 represents some of the various elements of the wood of the Plane-tree. And Fig. 46 ex- hibits three or four wood-cells from the same tree, more highly magnified; the two right-hand ones cut through lengthwise, and one of these, at the upper end, with a piece of another, also cut across, to show the thickness of the walls. 54. This and the following figures likewise show how the wood- cells are as it were spliced together, overlapping one another by their tapering ends. Forming wood consists of oblong or prismatic cells, with their ends nearly square or merely oblique: as these young cells lengthen, the ends become more oblique, and push by each other, or become wedged together. The wood-cells repre- sented in Fig. 46 are about 554, of an inch in diameter. Those of our Linden or Bass-wood (a few of which are shown in Fig. 50, 51) are rather larger, but not more than zs45 of an inch in diameter.* Their size varies in different plants almost as much as ordinary cells do, but they are usually much smaller than parenchyma, especially in herbaceous plants. Perhaps the largest are found in the Pine family, where they are of a peculiar sort, and are often as much * Lindley states that the woody tubes of the Linden are as much as ,4, of an inch in diameter; but I find none of anything like this size, WOODY TISSUE. 43 as gdp OY gig of an inch in diameter. The density or closeness of grain in wood, however, does not depend so much on the fineness \ of the wood-cells as upon the thickness of their walls. This is much greater in proportion to their diameter than in ordinary parenchyma, and, with their slenderness, and their very compact arrangement into threads or masses which run lengthwise through the stem, conspires to give the toughness and strength which charac- terize those parts in which this tissue abounds. In old wood of the harder kinds, the walls of the cells become so thick as almost to obliterate the calibre (Fig. 198). The thickening is generally uni- form, giving rise to no markings except the pits, or small thin spots, already described (45), which appear like pores. These are of very general occurrence, and are readily seen in the wood of the Plane- tree (Fig. 32, a, 46). Markings of this kind are most conspicuous in the Dise-bearing Woody Tissue (Glandular Woody Tissue of Lindley) of the Pine Family, the nature of which has just been explained (46). On account of their markings and their unusual size, and because in the Pine family they make up the wood without jany admixture of ducts, these pecu- liar wood-cells have been thought to be rather a form of vascular tissue. But in the Star-Anise much the same kind of marking is found on undoubtedly genuine woody tissue (Fig. 47). In the Yew, on the other hand, where the discs are few, delicate spiral markings appear (Fig. 48), showing a transition be- tween the proper woody and the (9000 LVL: £0000 90000 90 009990 0 vascular tissues; as is seen by com- paring the figure with that of a spirally marked duct of Bass-wood, Fig. 50, a. “Here the thickening deposit is in two successive and dissimilar layers; the first, with circular vacuities, forming the discs, while the second or innermost bears the spiral markings. FIG. 47. Magnified woody tissue of Illicium Floridanum (longitudinal view), marked with large dots, like the discs on the wood-cells of the Pine family. FIG. 48. Magnified woody tissue from the American Yew (longitudinal view), some cells showing delicate spiral lines only ; some showing the disc-like markings or dots of ordinary Conifers ; and others with both kinds of markings. Across the base is seen a portion of a medullary ray, 44 THE ELEMENTARY STRUCTURE OF PLANTS. {I 55. Bast Tissue, or Woody Tissue of the Liber. The bast or bass, fibrous inner bark, or liber, as it is variously termed, of those plants 49 50 és that have a true bark separable from the wood of the stem, usually consists of or contains much longer, very thick-sided, and tougher, but more soft and flexible cells, than those of the wood itself. These properties are “probably given them that they may possess the strength, combined with flexibility, which their position near the circumference of a branch renders necessary.” ‘These especially adapt them to the useful purposes they so largely subserve for clothing and cordage. The textile fibres of flax, hemp, &c. are all de- rived from this woody tissue of the bark, separated from the brittle cells of the wood itself, and freed from the surround- ing thin-sided parenchyma by macera- tion (which soon decomposes the latter) and by mechanical means.* The length is exemplified in the accompanying figures of the two, from our Basswood (Fig. 49 —51). The difference in the thickness / of the walls in this case is also great; the cells of the soft wood hav- ing rather thin walls even when old (Fig. 52), while those of the | of bast-cells as compared with wood-cells 5h 54 55 7 * Cotton differs from linen in many respects, and is of a very different origin. It consists of hairs, or long tubular cells, growing on the seeds of the plant. These have very thin walls, which collapse so that the tube flattens, and then twists spirally, which gives them a peculiar adaptation to be spun, or drawn out together by torsion into a thread, contiguous fibres thus moderately clinging to each other as they are drawn out. But they have not such thick and tough walls as liber-cells ; so a cotton fabric is not so heavy nor so durable as linen. FIG. 49. One bast-cell, and part of another, from the bark of American Basswood. 50. Some woody tissue from the wood of the same, with, a, upper end of a spirally-marked duct. 61. A separate cell from the wood. All magnified to the same degree. FIG. 52, Transverse section of some wood-cells of the Basswood, highly magnified. 53. Similar section of some bast-cells from the bark of the same tree, equally magnified. FIG. 54,55. Ends of bast-cells from the bark of the Leather-wood (Dirca palustris), mag- nified. VASCULAR TISSUE. 45 bast (Fig. 53) are so extremely thick-walled as almost to obliterate the cavity. The disproportion in length is still greater in our Leather-wood, which has a bark of extraordinary toughness, used for thongs, while the wood is very brittle and tender. Its capillary bast-cells measure from an eighth to a sixth of an inch in length, with an average diameter of so, of an inch (so that, if the whole length of a cell, magnified as in Fig. 54, 55, were given, the figure would be from a foot to a foot and a half in length); while those of the wood itself are only the hundredth of an inch long. Among the bast-cells are found the longest cells which occur in any tissue. Still the individual cells are by no means absolutely so long as they are supposed, and have sometimes been stated, to be. Few are of such length as those of the Leather-wood, above mentioned. According to Mohl (Bot. Zeit. 1855, p. 876) there are few plants in whieh | they exceed the twelfth of an inch; but he has found them an inch long in Flax and in our common Milkweed (Asclepias Cornuti), and somewhat longer in the Nettle. 56. Woody tissue runs lengthwise through the stem, root, or other | organ; hence it is sometimes designated as Longitudinal Tissue, the Vertical or Longitudinal System of the stem, &c. It shares this name, however, with some other forms of tissue which accompany it, particularly in the wood. The cells which compose it agree in exhibiting markings of some kind on their walls, and in being larger than those of woody tissue: they are all more or less tubular, or conspire to form tubes of considerable length, and hence they have all been combined, in a general way, under the name of 57. Vascular Tissue or Vessels, Not to be misled by the name, it ; should be remembered that these so-called vessels are mere modifica- tions of cellular tissue, and are wholly unlike the veins and arteries of animals. It is much better to call them ducts, a name appropriate to their nature and office, and leading to no false inferences. Their true nature is most readily shown in the largest and most conspicu- ous kind, one which often exhibits unequivocal indications of its cellular origin, viz. | 58. Dotted Ducts, called also Pitted or Vasiform Tissue, Bothren- chyma, &c. (Fig. 56, 57). They have likewise been termed Porous Cells or Porous Vessels ; but the numerous dots that characterize them are places which have not been thickened in the manner already explained (41, 44), and not perforations, except in old cells, where the primary membrane may be obliterated. Sometimes they 46 THE ELEMENTARY STRUCTURE OF PLANTS. are continuous tubes of considerable length (Fig. 57); but occasion- ally they exhibit cross-lines at certain intervals, plainly showing that they are made up of a row of cells placed end to end, and becoming a tube by the obliteration of the intervening partitions (Fig. 56). In Fig. 32 some dotted ducts (one of them exhibiting oblique parti- tions or ends) are shown in place among the woody tissue. It is in the wood that they commonly abound. Being of greater calibre than any other cells or vessels found there, they form the pores so conspicuous to the naked eye on the cross-section of many kinds of wood, such as of Oak, Chestnut, ci an and Mahogany, as well as the lines or channels seen on the longitudinal section. Their size, compared with that of the wood-cells in the wood of the Plane-tree, is shown both in longi- tudinal and transverse section, in Fig. 31, 32. 59. Sealariform Duets (Fig. 58, 59), differ from dotted ducts only _ in the form of the markings, the thin spots being transversely clon- gated instead of cireular, and appearing like cross-bars, which have been likened to the rounds of a ladder, whence the name. This is the more striking when the ducts are pris- matic (by mutual pressure) and the cross-bars occupy nearly the whole length of cach side, as in Fig. 58. Ducts of this sort abound in the stems or stalks of Ferns. The markings are often spiral in their arrangement; as is shown in Fig. 59, by the way the duct tears into a band. Ducts of this and of the foregoing sort, where the markings are thin places, have been named by Morren and Lindley Bothrenchyma, 58 59 . meaning pttted tissue. 60. Reticulated, Annular, and Spiral Ducts (Fig. 60-65), on the - other hand (called Zrachee, from their resemblance to the windpipe, or rather to the trachew or air-tubes of insects), have been distin- guished by Morren and Lindley under the general name of Zrachen- chyma. In these the markings, at least in most cases, are thicker FIG. 56. Portion of a dotted duct from the Vine, evidently made up of a series of short cells. FIG. 57. Part of a smaller dotted duct, showing no appearance of such composition. FIG. 58. Scalariform ducts of a Fern, rendered prismatic by mutual pressure. FIG. 59. Similar duct of a Fern, torn into a spiral band. VASCULAR TISSUE. 47 places than the rest of the wall. They are elongated cells, or tubes formed by the confluence of several cells into one, with the delicate walls strengthened by the deposition on their inner 2 Ak Z surface of additional ma- Zi terial, in the form of bands, ZF . * EA sometimes branching and 2 forming network (the Je- = Kt I i ticulated duct), as in the middle of Fig. 60, or of rings (the Annular duct), \as in the middle of Fig. 61, or of a continuous spi- ral thread (Fig. 62, 63), or a number of such threads , (Fig. 64), thus forming the ®% 8 Spiral duct or Spiral vessel. The coiled thread has been generally thought to be solid. But Trécul, in a memoir already referred to (42, note), insists that it is hollow, and it really appears to be so in the thick threads or bands of certain cells in the wood of several sorts of Cactus, such as are shown in Fig. 40 ~ 48, which are well adapted for the investigation of this point. In the true Spiral Vessel the fibre is so strong and tough, in comparison with the deli- cate membrane on which it is deposited, that it may be torn out and uncoiled when the vessel is pulled asunder, the cell-wall being destroyed in the operation. This is seen by breaking almost any young shoot or leafstalk, or the leaf of an Amaryllis, and gently separating the broken ends ; when the uncoiled threads appear to the naked KK elololor Licisielel_ ‘eR 3 FIG. 71. Raphides, or acicular crystals, from the stalk of the Rhubarb: three of the cells contain chlorophyll, and two of them raphides. FIG. 72. Raphides of an Arum, contained in a large cell; and 78, the same, detached from the surrounding tissue, and discharging its contents upon the application of water. FIG. 74. Crystals from the base of an onion, one of them a hemitrope or double. FIG. 75. Crystals of the inner bark of the Locust. FIG. 76. A glomerate mass of crystals from the Beet-root. FIG. 77, 78. Crystals from the bark of Hickory. Figures 73-78, and also 69, are from sketches kindly supplied by the late Professor Bailey of West Point. 60 THE GENERAL DEVELOPMENT OF PLANTS. may be readily found in the stalks of the Rhubarb, the Four-o’clock, the Arum or Indian Turnip, and the Calla. In the latter plants, a crystal-bearing cell in the leaf may often be detached entire from the surrounding tissue: when moistened, it absorbs water by endos- mosis, becomes distended, and may sometimes be seen to eject its crystals one by one, in a curious manner, through a minute perfora- tion at one or both ends (Fig. 73). As to their composition, these crystals more commonly consist of oxalate of lime; but those of car- bonate, sulphate, or phosphate of lime are not unfrequent. 95. Cystolithes are a peculiar structure composed of crystalline mincral and of vegetable matter combined, of common occurrence in the leaves of the Fig, Hop, Mulberry, and all the Nettle family, just beneath the epidermis. They are globular or club-shaped bodies, or of various other forms, usually hanging by a short stalk in an enlarged cell: their principal mass is found to be cellulose; but their surface is studded with crystalline points of carbonate of lime. CHAPTER II. OF THE GENERAL DEVELOPMENT AND MORPHOLOGY OF PLANTS. 96. Havine ascertained what vegetable fabric consists of, we are prepared to consider how these organic materials, the cells, are com- bined to constitute a vegetable, what the parts or organs of plants are, how they are related to each other, and how they live, grow, and perform the work of vegetation. Viewing plants as individual beings, we may now proceed to study their Organography or Mor- phology (3). 97. Plants occur under the greatest diversity of forms. Some kinds are of the utmost simplicity ; and many of these are so minute, that separately they are invisible to the naked cye, and become apparent only by their aggregation in vast numbers. Others are highly complex in structure, and may attain a great size, such as gigantic trecs, some of which have flourished for a thousand years or more. But each plant or tree, however vast or complex it may become, commenced its existence as a single vegetable cell, by the PLANTS OF THE LOWER GRADE. 61 multiplication of which the whole fabric was built up. All our or- dinary herbs and trees, however, even while in the seed, have already passed beyond this stage, and consist at this time of a mass of cells, more or less distinctly wrought into the form of a plantlet ; while the germs of plants of a lower grade, at the time of their separation from the parent plant, are each no more than a single cell. Cells of this kind, destined to give rise to new individuals (i. e. for reproduc- tion), are called Spores. The name spore is from a Greek word, meaning the same as seed. 98. Plants may be distinguished, therefore, into two great Series or Grades, a lower and a higher ;— the lower or simpler grade con- sisting of those plants which directly spring from single cells or spores; the higher grade, of those which spring from seeds. Sect. I. Prants or tHe Lower GRADE; THEIR DEVELOP- MENT FROM THE CELL. 99. Tuts grade includes the simplest and minutest plants, and also many which attain a great size, and exhibit no small complexity of structure, such as Tree Ferns (Fig. 100), for instance. The very lowest kinds not only begin their existence as single cells, but continue so throughout their whole growth. The most simple possi- ble form of vegetation therefore consists of 100. Plants of a Single Cell. In these minims of the vegetable world, the plant is reduced to its lowest terms: the plant and the cell are here identical. The cell constitutes an entire vegetable with- out organs, imbibing its food by endosmosis (40) through its walls, assimilating this food in its interior, and converting the organizable products at first into the materials of its own enlargement or growth, and finally into new cells, which constitute its progeny. Thus we have an epitome of all that is essential in vegetation, even on the largest scale; namely, the imbibition of inorganic materials ; their : assimilation ; their application to the growth of the individual, or nutrition ; and the formation of new individuals, or reproduction. Every stream or pool of water abounds with such plants, often in great variety. Simple as these plants are, they are by no means restricted to one monotonous pattern: perhaps they present as great diversity of form as do the kinds of ordinary vegetation, although from their minuteness they are mostly invisible to the naked eye. 6 62 THE GENERAL DEVELOPMENT OF PLANTS, The admirable memoirs of Nageli and of Braun upon One-celled Plants, and the works of Ralfs, Kutzing, Thwaites, &c. upon the Desmidiaceze and Diatomacee, illustrate a great variety of forms. The simplest possible case is that of 101. Plants of a Single Globular Cell ; that is, of a cell which grows equally in every direction, and therefore retains the original form. The microscopic plant known as giving rise to the phenomenon of red snow furnishes a good illustration of the kind (Fig. 79, 80): and so does a more common species, Protococcus cru- entus, which forms dull-crimson patches, resembling blood-stains, on the northern side of damp rocks or old walls. Each sphere is a single cell, which, quickly attaining its growth, produces (probably by division of the contents) a number of free cells in its interior. These escape by the decay of the walls of the mother-cell, grow speedily into similar cells or plants themselves, giving rise to another generation, and perish in their turn. Fig. 81 represents another and similar one-celled plant; and Fig. 82 and 83 show its mode of propagation, namely, by division of the whole living contents into two portions, and these again into two, these four globular masses 80 83 soon acquiring a wall of cellulose, and becoming so many distinct cells or plants;— the whole process admirably illustrating a com- mon mode of cell-multiplication (36). Indeed, another microscopic plant of the kind, very common in shallow pools at the beginning of spring, was taken as the readiest example of this multiplication of cells (Fig. 18-22). This propagation causes the destruction of the mother-plant in cach generation, all its living contents being em- ployed in the formation of the progeny, and its effete wall obliter- ated by softening or decay, and by the enlargement of the contained cells. Thus the simplest vegetation goes on, from generation to generation. The softened remains of the older cells often accumu- late and form a gelatinous stratum or nidus, in which the succeeding generations are developed, and from which they doubtless derive a FIG. 79. Several individuals of the Red-Snow Plant (Protococcus nivalis) magnified. 80. An individual highly magnified, showing more distinctly the new cells or spores formed with- in it. FIG. 81. An individual of Chroococcus rufescens, after Nigeli, much magnified. 82 A more advanced individual, with the contents forming two new cells by division. 83. Another, with the contents divided into four new cells. OF THE LOWER GRADE. 63 part of their sustenance, —just as a tufted Moss is nourished in part from the underlying bed of vegetable mould which is formed of the decayed remains of its earlier growth. Other one-celled plants enlarge in one direction more than in any other, so becoming oval or oblong, and making a transition to a somewhat higher grade of vegetation, viz. 102. Plants of a Single Elongated Cell. Such plants may be con- ceived to bear the same relation to the foregoing, that ducts (57) and wood-cells (53) do to cells of parenchyma (51). For an ex- ample we may take any species of Oscillaria (Fig. 84); a form of aquatic vegetation of mi- croscopic minuteness, considered as to the size of the individuals; but these rapidly multiply in such inconceivable numbers, that, at certain seasons, they sometimes color the surface of whole lakes of a green hue, as suddenly as broad tracts of alpine or arctic snow are red- dened by the Red-Snow Plant. If the trans- verse markings of some Oscillarias answer to internal partitions, then they make a transition between one-celled plants and those formed of a row of cells. — Since cells which form part of the fabric of vegetables are sometimes branched (88), we should naturally expect. to find, as the next step in the development, 103. Planis of an Elongated and Branching Cell. Good ex- amples of the sort are furnished by the species of Vaucheria, which form one kind of the delicate and flossy green threads abounding in fresh waters, and known in some places by the name of Brook-silk. These, under the magnifying-glass, are seen to be single cells, of unbroken calibre, furnished here and there with branches (Fig. 89). The branches are protrusions, or new growing points, which shoot forth by a sort of budding, and have the power of continuous growth from the apex. In Bryopsis (Fig. 91), a beautiful small Sea-weed, the branches are much more numerous and regularly arranged; their cavity is continuous with that of the main stem, if we may so call it: in other words, the whole plant, which is by no means minute, consists of a single, repeatedly many-branched cell. And in Codium, another genus of marine Algew, we have an indefinitely FIG. 84. Two individuals of Oscillaria spiralis, magnified ; one with an extremity cut off. 64 THE GENERAL DEVELOPMENT OF PLANTS, ramified cell, intricately interlaced or compacted, and forming dense masses of considerable size and of definite shapes. 85 a 90 HOE e Oa eG 9 @ roo | O eo Og P90, 07, On ba 88 89 gL 104. While in these cases the ramifications of the cell imitate, or as it were foreshadow, the stem and branches of higher organized plants, we have in Botrydium (Fig. 88) a cell whose ramifications resemble and perform the functions of a root. This consists of an enlarged cell, which elongates and ramifies downwards, the slender branches penetrating the loose and damp soil on which the plant grows, exactly in the manner of a subdivided root. Meanwhile, a crop of spores or rudimentary new cells is produced, by original cell-forma- tion (29), in the liquid contents of the mother-cell: these, escaping when that decays or bursts, grow into similar plants, in the manner shown by iy. 86,87. The spores by which Vaucheria is propagated originate in a somewhat different way. When about to fructify, the apex of a branch enlarges, its green contents thicken, separate from those below, condense into a rounded mass, which acquires a coat of protoplasm (Tig. 89, a): the sac in which it was formed soon bursts open, and the new-born spore escapes into the water (Fig. 90). It moves about freely for some hours (678), when a coat of cellulose is formed upon its surface, converting it into a true cell, which soon FIG. 85-87. Botrydium Wallrothii in its development, and with new cells forming within : after Kiitzing: 85, the cell still spherical: 86, pointing into a tube below: 87, the tube pro- longed and branched : all much magnified, ¥1G. 88. Botrydium argillaceum, after Endlicher ; the full-grown plant, magnified. FIG. 89. Vaucheria clavata, enlarged: a, a spore formed in the enlarged apex of that branch. 90. End of the branch, more magnified, with the spore escaped from the burst apex. FIG. 91. Bryopsis plumosa ; summit of a stem with its branchlets, much enlarged. OF THE LOWER GRADE. 65 grows by elongating into a thread, one end of which fixes itself to a stone or some other solid body, while the other grows first into a simple tube, and then sends off branches like its parent. In this way, a plant composed of a single cell imitates not obscurely the upward and downward growth (the root and the stem) of the more perfect plants, or when cells like these, whether simple or branched, form cross-partitions as they grow, in the manner of the Conferva (Fig. 15) used to illustrate this mode of cell-multiplication, they give rise to 3 105. Plants of a Single Row of Cells. Most of the thread-like green Alge (Confervez), which abound in pools and brooks, are of this sort. So are the Moulds or Mildew Fungi, of which three kinds are here represented; viz. the Bread-Mould (Fig. 92), and the Cheese-Mould live upon dead or- 2 ganic matter; and . a species of Botrytis (Fig. 94). The latter, and other Moulds of the same or of other kinds, feed upon the juices of living plants, and even animals, where they commit great ravages. The too well- known potato-disease, for example, is probably caused by the attack of a species of Botrytis; a similar species has long been known as the cause of the muscardine, a fatal malady of silk-worms, and the malady which has for several years destroyed a great part of the grape-crop in Europe is caused by another parasitic plant of the same simple structure. The accompanying figures show only the perfect state of these troublesome little plants, or rather their fructi- fication. Their vegetation consists of long and branching threads (of which a small portion only is represented at the base), which penetrate and spread widely and rapidly through the vegetable, or other body they live on, and feed upon its juices. At length they break out upon the surface, and produce countless numbers of 92 FIG. 92-94. Three kinds of Mould, magnified. 92. The Bread-Mduld (Mucor, or Asco- phora). 93. The Cheese-Mould (Aspergillus glaucus). 94. Botrytis Bassiana, the species which attacks silk-worms, &c. 6* 66 THE GENERAL DEVELOPMENT OF PLANTS, spores (97), or minute rudimentary cells, which are detached from the parent plant and serve the purpose of seeds. The spores are in some cases produced (probably by original cell-formation), in an enlarged terminal cell, as in the Bread-Mould (Fig. 92); while in other cases they are naked, and arise from cell-division, as in Fig. 93, 94. 106. Plants of this simple structure (belonging chiefly to the lower Algve and Fungi) are almost as various in form and numerous in species as are the higher kinds of vegetation. Some consist of a single jointed thread; others are excessively branched; and some- times the branches are interlaced or compacted to form masses or strata of considerable size. Some of them present little or no dis- tinction among the cells they consist of, each cell performing the same office as any other, and each capable of producing spores or in some way serving for reproduction; such may well be regarded as rows of one-celled plants, more or less united. But more com- monly, even in the simplest vegetable forms, the work which the plant has to perform is divided, some parts serving for vegetation or nutrition, and others for reproduction, as we see is the case with the Moulds, &c. Even a one-celled plant may begin to have organs, or parts adapted to special purposes, as is well shown by Botrydium and Vaucheria (Fig. 85-90). As we ascend in the scale of vege- table life, more and more specialization will be found at every step. 107. A slight change in the way the cells multiply, namely, the formation of partitions in two directions instead of only one, intro. duces the next advance in vegetable development, giving rise to Wehng ante ane 96 108. Plants of a Single Plane or Layer of Cells. Figures 18 - 22 show how a plant of a single spherical cell may multiply, by repeated FIG. 95. A piece of Delesseria Leprieurei, from Iudson River, of twice the natural size. 96. A portion of the whole breadth of the same, more magnified, to show the cellular struc- ture. The cells have thick gelatinous walls; those in the middle are elongated, those towards the margins rounded. 97. A small portion still more magnified. OF THE LOWER GRADE. 67 division, into two, four, and sixteen such plants, and so on. But if these cells had merely remained in connection as they multiplied, they would have composed one plant, consisting of a stratum of cells. This is just what we have in the Dulse or Laver (Ulva, &c.) and some other simple leaf-like Alga of various kinds, such, for example, as that illustrated in Fig. 95-97. When the whole body of a plant is thus expanded and leaf-like, it forms what is called a Fronp. 108%. Not only Sea-weeds, but many Liverworts and Lichens, grow in this way. (In Lichens, &, the expanded body usually takes the name of THattus.) In most cases, however, such plants are composed of more than one layer of cells, or of a considerable number of layers. And those of thread-like forms, resembling naked stems and branches, in all the coarser and in some very delicate kinds, are made up, like the parts of ordinary vegetables, of several thicknesses of cells; that is, they are 109. Plants of a Solid Tissue of Cells, formed by cell-multiplication through division taking place in more than two directions. Sea- weeds, Lichens, and other plants of the lowest orders, forming in this way a tissue of cells, generally exhibit either leaf-like or stem- like shapes, but seldom if ever do they present both in the same plant. They may resemble leaves, or they may resemble stem and branches, or display a variety of forms intermediate between stem and leaf. But it is only when we come to the highest tribe of Liverworts, and to the true Mosses, that the familiar type of ordinary vegetation is realized in 110. Plants with a Distinct Axis and Foliage; that is, with a stem which shoots upward from the soil, or whatever it is fixed to, or ereeps on its surface; which grows onward from its apex, and is symmetrically clothed with distinct leaves as it advances. All these lower vegetables, of whatever form, imbibe their food through any or every part of their surface, at least of the freshly formed parts. Their roots, when they have any, are usually intended to fix the plant to the rock or soil, rather than to draw nourishment from it. The strong roots of the Oar-weed, Devil’s Apron (Laminaria), and other large Sea-weeds of our coast, are merely hold-fasts, or cords expanding into a disc-like surface at the extremity, which by their adhesion bind these large marine vegetables firmly to the rock on which they grow. Mosses also take in their nourishment through their whole expanded surface, principally therefore by their leaves; but the stems also shoot forth from time to time delicate rootlets, 68 THE GENERAL DEVELOPMENT OF PLANTS. composed of slender cells which grow in a downward direction, and doubtless perform their part in absorbing moisture. A Moss, there- fore, is like an ordinary herb in minia- ture, and exhibits the three general OrcGans oF VEGETATION, viz. Foot, Stem, and Leaves. 111. Cellular and Vascular Plants. While the Mosses emulate ordinary herbs and trees in vegetation and ex- ternal appearance, they accord with the lowest kinds of plants in the sim- plicity of their anatomical structure. They are entirely composed of cellu- lar tissue strictly so called, chiefly in the form of parenchyma (51); at least they have no distinct vessels or ducts (57) and no true wood in their com- position. The Mosses, along with the Lichens, Algw, Fungi, &c., were there- fore denominated CrLituLar Prawns by De Candolle. All plants of higher grade, inasmuch as vascular and woody tissues enter into their composition, when they are herbs as well as when they form shrubs or trees, he distinguished by the general name of VascuLtar Priants. 112. The strength which woody tissue imparts (54) enables plants in which it abounds to attain a great size and height; while Mosses and other cellular plants are of humble size, except when they live in water, in which some of the coarser Sea-weeds do indeed acquire a prodigious length. Although true Mosses have no wood in their composition, yet the so-called Club-Mosses have. So also have the Ferns, the highest organized family of the lower grade of plants; and although these are mostly herbs, or else plants with their more or less woody stems creeping on or beneath the surface of the ground, yet in warm climates some species rise with woody trunks into tall and palm-like trees. But even these, like the hum- FIG. 98. An individual of a Moss (Physcomitrium pyriforme), enlarged to about twelve times the natural size. 99, Tip ofa leaf, cut across, much magnified, to show that it is made up (except the midrib) of a single layer of cells. PLANTS OF THE HIGHER GRADE. 69 blest Mosses or the minutest Moulds, spring from single cells or spores (97), and not from true seeds. And the apparatus by which these spores are produced, whatever be its nature, is not a flower. Plants of the lower grade (98, 99) are therefore collectively denominated 113. Flowerless or Cryptoga- mous Plants, The first name expresses the fact that the or gans of fructification in these plants are not of the nature of real flowers. The second name, which was introduced by Linneus, and is composed of two Greek words meaning “concealed fructification,’ re- fers to the obscure nature of the organs or the processes of reproduction in these plants, which have only recently come to be understood. Some ac- count of them will be given in Chapter XII. 100 Secr. Il. Prants or tue Hicnuer Grape; THEIR DrEvELor- MENT FROM THE SEED. 114. Flowering or Phenogamous Plants,*— so called in contradis- tinction to the Flowerless or Cryptogamous, —is the general name for the higher grade of plants, to which our ordinary herbs, shrubs, and trees belong, and which may be said to exhibit the perfected type of vegetation. The lower grade begins with plants so simple as to * Sometimes written Phanerogamous. Both terms are made from the same Greek words, and signify, by « metaphorical expression, the counterpart of Cryptogamous ; that is, that the essential organs of the flower are manifest or conspicuous. FIG. 100. Sketch of a Tree Fern, Dicksonia arborescens, of St. Helena; after Dr. J. D. Hooker. 101. Polypodium vulgare, a common Fern, with its creeping stem or rootstock. 70 DEVELOPMENT OF FLOWERING OR PILENOGAMOUS be destitute of organs; and it is only in the higher Cryptogamous plants, such as Mosses and Ferns, that the familiar organs of ordi- nary vegetation appear as separate parts of the plant, viz. the root, stem, and leaves. In the higher grade (i. e. in Phanogamous Plants) these three parts are well defined, and always present, in some form or other ;—a few anomalous instances excepted, such as the common Duck-weed, for example (Fig. 102). Here stem and leaf are as it were blended, in the manner of a Liverwort, to form a flat green body, which floats on the water, exposing the upper sur- face like a leaf to the light, while one or more roots proceed from the lower, and a small and simple flower at length makes its appearance on some part of the margin. This is an extremely simplified state of a Phanogamous plant. 115. Ordinarily, not only are the root, stem, and foliage distinct and separate from each other, but also distinct from the apparatus for reproduction. So that the plant is composed of two kinds of or- gans, viz. ORGANS OF VEGETATION and Organs oF REPRODUCTION. 116. The Organs of Vegetation are the Root, Stem, and Leaves (110). These are so called because they are jointly concerned in the nutri- tion and growth of the plant, and in the performance of all its char- acteristic functions, and they are all that is so concerned. Making up as they do the entire vegetable, and repeated under varied forms throughout its whole development, they are also termed the Funpa- MENTAL OrGANS of plants. 117. The Organs of Reproduction in the simplest Cryptogamous plants are not distinct from those of vegetation; but in most plants, even of the lowest families, the cells for reproduction are different in appearance and in the mode of their formation from those which serve for vegetation. These reproductive cells, or Spores, with the apparatus for their production and protection, whatever it may be, constitute the organs of reproduction in Cryptogamous plants. In Phenogamous plants the organs of reproduction are the FLower, essentially consisting of Stamens and Pistils, and the result of their co-operation is the production of Srxrp. 118. A Seed is a body produced by the agency of a flower, which contains, within one or more coats or coverings, a ready-formed PLANTS FROM THE SEED. 71 plantlet in a rudimentary state. Flowerless or Cryptogamous plants spring from spores or single cells, which when they germinate multi- ply to produce a tissue or an aggregation of cells, that at length grows and forms a plantlet. But a seed contains a plantlet ready formed, or a germ, which is called an Emeryo. And the history of a Flowering or Phanogamous plant naturally begins with 119. The Development of the Embryo from the Seed. The embryo varies exceedingly in size, shape, and appearance in different plants ; but it is constructed upon the same general plan in all; and the development of almost any plantlet from the seed will serve to illus- trate the principal laws and processes of vegetable growth. To commence with the study of the seedling is the readiest way to un- derstand the whole vegetable structure and life. 120. The seeds of the Red or the Sugar Maple furnish good illustrations, and they are readily met with in germination, i. e. just developing the embryo into a plant. Also they areelarge enough to allow the embryo to be extracted from the seed-coats, and inspected by the naked eye, or by the aid of a common hand-glass. (Fig. 103 — 105.) Here the whole contents of the seed consist of an embryo, neatly coiled up within the seed-coats. If un- folded, or, which is better, if examined when just unfolding itself in germination, it is seen to consist of a tiny stem or axis (Fig. 104, 105, a), bear- ing a pair of small leaves on its summit. The axis is called the Rapicxe, because it was supposed to be the root; though it is really the rudiment of the stem rather than of the root, and therefore were better named the Caulicle ; but the former name is now too well established to be superseded. The two little seed-leaves (4, 6) are technically called Coryrepons: and a little bud which will pres- ently appear between them (Fig. 106, ¢), or may be discerned there in many embryos before germination (as in the Almond, Fig. 108, a) is named the PLromute. The embryo, accordingly, is a short axis or stem bearing upon one end some rudimentary leaves ; 103 FIG. 108. Embryo of Sugar-Maple as coiled up in the seed. 104,105. The same, just be- ginning to unfold and develop in germination: a, the radicle, or primary stem: 0, 6, the cotyledons or seed-leaves. 72 DEVELOPMENT OF FLOWERING OR PHENOGAMOUS or, in other words, it is a primary stem crowned with a leaf-bud. When it grows, this stem elongates throughout its whole length, so as usually to raise the budding apex above the surface of the soil, into the light and air, where its cotyledons expand into leaves; and at the same time from the opposite ex- tremity is formed the root, which grows in a downward direction, so as to pen- etrate more and more into the soil. The two extremities of the embryo are dif- ferently organized, are differently affect- ed by light and air, and grow in opposite directions. The budding end invaria- bly turns towards the light, and grows upwards into the air; the root-end turns constantly from the light, and buries it- self in the dark and moist soil. These tendencies are absolute and irreversible. If the budding end happen to lie point- ing downwards and the root end up- 106 wards, both will curve quite round as they grow to assume their appropriate positions. If obstacles inter- vene, the root will take as nearly a downward, and the stem as nearly an upward direction, as possible. These are ,only the first manifestations of an inherent property, which continues, with only incidental modifications, throughout the whole growth of the plant, although, like instinct in the higher animals, it is strongest at the commencement: and it insures that each part of the plant shall be developed in the medium in which it is designed to live angl act, — the root in the earth, and the stem and leaves in the air. The plantlet, therefore, possesses a kind of polarity; it is composed of two counterpart systems, namely, a Descending Axis, or root, and an Ascending Axis, or stem. The point of union or base of the two has been termed the crown, neck, or collar. Both the root and stem branch; but the branches are repetitions of the axis from which they spring, and obey its laws; the branches of the root tending to descend, and those of the stem to ascend. FIG. 106. A germinating embryo of Sugar-Maple, more advanced: a, the radicle elongated into the first joint of stem, bearing the unfolded cotyledons or seed-leaves, b, and between them the plumule (c), or rudiments of the next pair of leaves ; while from its lower extremity the root, d, is formed. PLANTS FROM THE SEED. 73 121. The root and the stem grow not only in opposite directions, but in a different mode. The little stem, pre-existing in the seed, grows throughout its whole length, (but most in its upper part,) so that a radicle of perhaps less than a line in length may become a stemlet two or three inches long. It is by this elongation that the seed-leaves are raised out of the soil, so as to expand in the light and air. Meanwhile a root begins to be formed at the other end of the radicle; and this lengthens by continued cell-multiplication mainly at its lower extremity, the parts once formed scarcely if at all elon- gating afterwards ; but the growth takes place continuously at the tip alone. The primary stem, bearing the pair of seed-leaves, soon completes its development, and ceases to lengthen. Then, if not before, the plumule (Fig. 106, c) begins its growth and develops into a second stemlet on the summit of the first, bearing its pair of leaves. It lengthens in the manner its predeces- sor did, and carries up the second pair of leaves to some distance above the first; then from between them springs a third joint of stem, crowned with its pair of leaves (Fig. 107); and so on, building up the whole herb or tree by this succession of similar growths or joints of stem. The root, on the other hand, grows on in a downward direc- tion continuously, is not composed of a series of joints, and bears no leaves or other organs. 122. The youngest seedling is there- fore provided with all the organs of vegetation that the full-grown plant possesses ; and even the embryo in the seed is already a miniature vege- table. It has a stem, from the lower end of which it strikes root in ger- mination ; it has leaves, and it has or soon forms a bud, which develops into new joints of stem bearing additional leaves, while beneath it sends its root deeper and deeper FIG. 107. A Seedling Maple which has developed two additional joints of stem, each with their pair of leaves. 7 74 DEVELOPMENT OF FLOWERING OR PHAHNOGAMOUS into the soil. The root absorbs materials for the plant’s nourish- ment from the soil; these are conveyed through the stem into the leaves, and there assimilated (12, 15), under the influence of the light of the sun and the air, into organic matters which serve directly for further growth, and form the fabric of new portions of stem, new leaves, and new roots, the vegetable thus increasing its size and its power at every step. 123. Once established, therefore, the plant can provide for itself, drawing the needful materials from the earth and the air, and assimilating or organizing them by its own peculiar power. But at the beginning, and until it has sent forth its root into the soil and spread out its first leaves in the light, it must be nourished and grow by means of organized matter supplied by the parent plant. This supply in the Maple was de- 108 109 110 M1 m4 posited in the seed-leaves of the embryo, and was barely sufficient to develop the radicle into a tiny stem, to form a simple root at the lower extremity, and above to expand in the light the pair of small, green seed-leaves; when the plantlet is left to its own resources. Very commonly a larger store of nourishment is pro- vided for the plant’s earliest growth. In the almond, for instance (Fig. 108), the large cotyledons are so thickened by this nourishing matter, deposited in their tissue, that they have not the appearance of leaves. It is the same in the Plum and Cherry (Fig. 111°), and in the Apple, only on a smaller scale (Fig. 110, 111); and the Beech (Fig. 112-114) and the Bean (Fig. 115-117) afford familiar FIG. 108. Embryo (kernel) of the Almond. 109. Same, with one cotyledon removed, to show the plumule, a. FIG. 110. Section of an Apple-seed, magnified, cutting through the thickness of the cotyledons. 111. Embryo of the same, extracted entire, the cotyledons a little separated. FIG. 111%. Germination of the Cherry, showing the thick cotyledons little altered, and the plumule developing the earliest real foliage. vLANTS FROM THE SEED. 75 illustrations of the kind. The ample store of nourishment in such cases enables the germinating plantlet to grow with remarkable vigor, and to develop the strong plumule with its leaves before the seed-leaves have expanded, or the root has obtained much foothold in the soil. In these instances the cotyledons are so much thickened that, although they turn greenish in the light, they only im- \ perfectly — as- ‘sume the ap- pearance and J perform the functions of or- dinary leaves ; and the earli- est real foliage consists of the leaves of the plumule. Such cotyledons serve chiefly as depositories of nourishment for the germi- N7 116 nating plant. 124. Still more strongly marked cases of this kind are presented by the Pea (Fig. 118, 119), the Chestnut and Horsechestnut, the Oak (Fig. 120, 121), &c. Here the cotyledons are excessively thickened, so as to lose all likeness to leaves and all power of ful- filling the office of foliage. Accordingly they remain unchanged within the seed-coats, supplying abundant nourishment to the FIG. 112. A Beech-nut, cut across. 113. Beginning germination of the Beech, showing the plumule growing before the cotyledons have opened or the root has scarcely formed. 114. The same, a little later, with the second joint lengthened. FIG. 115. The embryo (the whole kernel) of the Bean. 116, Same early in germination ; the thick cotyledons expanding and showing the plumule. 117. Same, more advanced in germination ; the plumule developed into a joint of stem bearing a pair of leaves. 76 DEVELOPMENT OF FLOWERING OR PHZENOGAMOUS plumule, which gives rise to the first leaves that appear. As the radicle itself scarcely if at all elongates, the cotyledons are not ele- vated in germination but remain under ground (i. e. are Aypogeous), or rest on the surface of the soil. 125. In all the foregoing illustrations the nourishment provided for the growth of the embryo into a plantlet is deposited in the tissue of the embryo itself, i. e. in the seed- leaves. In other cases it is depos- ited around the embryo; when it forms what is commonly called the Albumen of the seed. This makes up the principal bulk of the seed in the' Buckwheat, In- dian Corn (Fig. 126, 127), and most other sorts of grain. The greater the quan- tity of this, the floury part of the seed, the smaller or less developed is the embryo, or the less thick are its cotyledons. In the Morning- 121 Glory, for instance (Fig. 122-125), where the embryo is surround- ed by mucilaginous albumen, the cotyledons appear in the seed as a pair of very thin and well-formed green leaves. These absorb the nourishment required for the plantlets earliest growth from FIG. 118. Embryo ofa Pea. 119. The same in germination. FIG. 120. An acorn, divided lengthwise, showing a section of the very thick and fleshy cotyledons and the very small radicle. 121. Germination of the acorn, PLANTS FROM THE SEED. 77 the surrounding albumen, which in germination is gradually lique- fied, its starch or amyloid being transformed into dextrine and sugar (80, 82, 83). Thus nourished, the radicle rapidly lengthens into a stem, and develops a root from its lower extremity, connecting it with the 126 soil; and when the enlarging cotyledons extricate themselves from the decaying seed-coats and expand in the light as the first pair of leaves, the plantlet is already established as a complete miniature vege- table, able to nourish it- self, and make sufficient provision for its own con- tinued growth. 126. The embryo in seeds provided with albumen is sometimes very small, as in Fig. 131, or even much more minute, and with its parts so rudimentary that they are hardly or not at all discernible previous to their gradual development in germination. But sometimes it is pretty large, and with all its parts 129 obvious in the seed; as in the Morning-Glory and in Indian Corn (Fig. 122). The latter has a highly organized 124 125 FIG. 122. Seed and embryo of the common Morning-Glory, cut across; the latter seen edgewise. 123. Embryo of the same, detached and straightened, seen flatwise. 124. Germi- nating Morning-Glory. 125. The same further advanced ; its two thin seed-leaves expanded. FIG. 126. A grain of Indian Corn, seen flatwise, divided through the embryo, which is viewed lying on the albumen, which makes the principal bulk of the seed. FIG. 127. Another grain of Corn, cut through the middle in the opposite direction, divid- ing the embryo through its thick cotyledon and its plumule, the latter consisting of two leaves, one enclosing the other. FIG. 128. The embryo taken out whole: the thick mass is the cotyledon; the narrow body partly enclosed by it is the plumule; the little projection at its base is the very short radicle enclosed in the sheathing base of the first leaf of the plumule. FIG. 129. A grain of Indian Corn in germination. i qT* 78 DEVELOPMENT OF PH#NOGAMOUS PLANTS. embryo, with a strong and well-developed plumule, of several leaves enwrapped one within another; and, being amply nourished by the copious mealy albumen, it sprouts with re- markable vigor, sending up three or four leaves in rapid succession before the earliest has completed its growth, at the same time sending forth additional roots downwards into the soil. Here also, as in the Pea and the Oak, &c. (124) the germination is hypog@ous, the cotyledons remaining in the seed under ground, and the leaves which appear above ground belonging to the plumule. This is also the/: case in the Iris (Fig. 132) and \ most plants of the same class. But in the Onion the co- tyledon (which is single) lengthens, raises the seed out of the ground, and be- comes the first leaf. 127. In Indian Corn (Fig. 130), in Iris (Fig. 132), and also in the germinating Cher- 130 ry (Fig. 111°), Oak (Fig. 121), and Pea (Fig. 119), the leaves of the plumule |, succeed one another singly, that is, there is only one — upon each joint of stem: in other words, the leaves are alternate. Whereas in the seedling Beech and the Bean (Fig. 114, 117) these early leaves are in pairs, that is, are opposite. A similar difference is to be noticed in the embryo as to the 128. Number of Cotyledons, All the earlier illustra- tions are taken from plants which have a pair of cotyle- dons, or sced-leaves, belonging to the first joint of stem, that is, to the radicle. Such embryos are accordingly a2 said to be DicoryLEpoNoUs,—a name expressive of this fact. But in the Lily, Onion, Iris, Indian Corn, and the like, the embryo FIG. 130. Indian Corn more advanced in germination, and with a cluster of roots. FIG. 181. Section of a seed of Iris or Flower-de-Luce, magnified, showing the small embryo enclosed in the albumen, near its base. 132. Germinating plantlet of Iris. THE ROOT. 79 has only one cotyledon or true seed-leaf (Fig. 128, &.); the other leaves, if any are apparent, are enclosed by the cotyledon and be- long to the plumule; and the embryo with one cotyledon is ac- cordingly termed Monocotyieponous. The difference in this respect coincides with striking differences in the structure of the stems, leaves, and blossoms, and lays a foundation for the division of Flowering or Pheenogamous plants (114) into two great Classes. 129. In a few plants, such as Pines, the embryo is provided with from three to ten cotyledons, which expand into a circle of as many green leaves in germination (Fig. 133, 134): such an embryo is said to be PotycoryLeponovs, i. e. of many cotyledons. 130. Having taken this general survey of the development of Phanogamous plants from the seed, and of their common plan of growth, their further development and their morphology may best be studied by examining in succession the three universal organs of vegetation (116) of which they all consist, viz. the Root, Stem, and Leaves. 14 CHAPTER III. OF THE ROOT, OR DESCENDING AXIS. 131. THE Root is the descending axis (120), or that portion of the body of the plant which grows downwards, ordinarily fixing the vegetable to the soil and absorbing nourishment from it. As already mentioned (121), the root grows in length by continual additions of new fabric to its lower extremity, elongating from that part only or chiefly ; so that the tip of a growing root always consists of the most newly formed and active tissue. It begins, in germination, at the root-end of the radicle. That only this extremity of the radicle is root is evident from the mode in which the radicle grows, namely, FIG 1383. Section of a seed of a Pine, with its embryo of several cotyledons. 1384. Early seedling Pine, with its stemlet, displaying its six seed-leaves. . 80 THE ROOT, by lengthening throughout every part; which is a characteristic feature of the stem. 132. The root, however, does not grow from its very apex, as is commonly stated; but the new formation (by continued multiplica- tion of cells, 33) takes place just behind the apex (Fig. 185), which consists of an obtusely conical mass of older cells. As these wear away or perish, they are replaced by the layer beneath; and so the advancing point of the root consists, as inspection plainly shows, of older and denser tissue than the portion just behind it. The point of every branch of the root is capped in the same way. It follows that the so-called spongioles or spongelets of the roots, or enlarged tips of delicate forming tissue, have no ex- istence. Not only are there no special organs of this sort, but absorption evidently does not take place, to any considerable extent, through the rather firm tissue of the very point itself. 133. Absorption by Roots, As the surface of the root, like every part of a plant, consists of closed cells, it is evident that the moist- ure it so largely takes in must 136 be imbibed through the walls of the cells, by endosmose (40) ; and that the whole surface of a fresh root will take part in ab- sorption. The newer the root, however, the more actively does it absorb, the cells then having thinner walls. As they become older, the superficial layer of cells thicken their walls and form a kind of skin, or epider- mis (69), through which absorp- tion does not take place so free- 18 ly. Roots accordingly absorb mostly by their fresh tips and the adjacent parts; and these are constantly renewed by growth, and FIG. 135. The tip of the root of a seedling Maple (Fig. 106), magnified: a, the place where growth is mainly taking place, by cell-multiplication : }, the original tip of the radicle. FIG. 186, 187. Portions of the surface of the same, highly magnified, showing the nature of the root-hairs or fibrils. ITS STRUCTURE AND GROWTH. 81 extended farther into the soil. The absorbing surface of the new parts of roots is greatly increased by the 134. Root-hairs, or delicate fibrils which they bear. These are often discernible by the naked eye, as in the young seedling Maple (Fig. 106), and may almost always be plainly shown by a moderate magnifying power, as in Fig. 185; while a higher power distinctly reveals their nature, as prolongations of some of the superficial cells from a certain point into slender tubes (Fig. 136, 137), thus largely increasing the absorbing surface. As fast as the superficial cells are converted into epidermis, the root-hairs die away, fresh ones taking their place on the newer parts. 135. The advancing extremity of the root consists of parenchyma alone; but vessels and woody tissue appear in the forming root soon after their appearance in the radicle or stemlet above. The arrangement of the woody matter is generally the same as in the stem, except that the root seldom exhibits a distinct pith. The root increases in diameter in the same manner as the stem. (Chap. IV. Sect. IV., V.) 136. The growth of the root and its branches keeps pace with the development of the stem. As the latter shoots upward and expands its leaves, from which water is copiously exhaled during vigorous vegetation, the former grow onward and continually renew the tender tissue through which the absorption, required to restore what is lost by evaporation or consumed in growth, is principally effected. Hence the danger of disturbing the active roots during the season of growth. In early summer, while new branchlets and leaves are developing, and when the sap is rapidly consumed by the fresh foliage, the rootlets are also in rapid action, are extending at a corresponding rate, and their tender absorbing points are most fre- quently renewed. They cannot now be removed from the soil with- out injury, at the very time when their action is essential to restore the liquid which is continually exhaled from the leaves. But at the close of summer, as the leaves become inactive and the growth of the season is attained, the rootlets also cease to grow, the epidermis forms a comparatively firm covering quite down to the tip, and ab- sorption at length ceases. This indicates the proper period for transplanting, namely, in the autumn after vegetation is suspended, or in early spring before it recommences. 157. This elongation of roots by their advancing points alone is admirably adapted to the conditions in which they are placed. 82 THE ROOT, Growing as they do in a medium of such unequal resistance as the soil, if roots increased like growing stems, by the elongation of their whole body, they would be thrown, whenever the elongating force was insufficient to overcome the resistance, into knotted or con- torted shapes, ill adapted for the free transmission of fluid. But, lengthening only at their farthest extremity, they insinuate them- selves with great facility into the crevices or yielding parts of the soil, and afterwards by their expansion in diameter enlarge the cavity ; or, when arrested by insuperable obstacles, their advancing points follow the surface of the opposing body until they reach a softer medium. In this manner, too, they readily extend from place to place, as the nourishment in their immediate vicinity is consumed. Hence, also, may be derived a simple explanation of the fact, that roots extend most rapidly and widely in the direction of the most favorable soil, without supposing any self-determining power beyond what belongs to all growing parts. (Chap. XIII.) 138. We have taken the root of the seedling as an example and epitome of that of the whole herb or tree; as we rightly may, for in its whole development the root produces no other parts; it bears nothing but naked branches, which spring from different portions of the surface of the main root, nearly as this sprung from the radicle, and exactly imitate its growth. They and their ramifications are mere repetitions of the original descending axis, serving to multiply the amount of absorbing surface. The branches of the root, more- over, shoot forth irregularly, or at least in no order like that of the branches of the stem, which have a symmetrical arrangement, de- pendent upon the arrangement of the leaves (166). 139. To the general statement that roots give birth to no other organs, there is this abnormal, but by no means unusual exception, that of producing buds, and therefore of sending up leafy branches. Although not naturally furnished with buds, like the stem, yet, under certain circumstances, the roots of many trees and shrubs, and of some herbs, have the power of producing them abundantly. Thus, when the trunk of a young Apple-tree or Poplar is cut off near the ground, while the roots are vigorous and full of elaborated sap, thoze which spread just beneath the surface produce buds, and give rise to young shoots. The roots of the Maclura, or Osage Orange, habitually give rise to such irregular or adventitious (168) buds and branches. 140. Although the root does not produce ascending axes, or stems, IN ANNUAL AND BIENNIAL PLANTS. 83 except in certain rather unusual instances, yet stems habitually pro- duce roots, whenever circumstances favor it, namely, when they are covered by the damp and moist soil, or rest on its surface. Roots accordingly may be distinguished into primary and secondary. 141. The Primary Root is that which originates from the root end of the embryo in germination, including also its branches. If this continues as a main root, it commonly forms a tap-root. But very often the main root, is soon lost in the branches. Sometimes a cluster of roots is produced directly from the lower extremity of the radicle, as in the Pumpkin, and Indian Corn (Fig. 130). In the latter the second and the succeeding short joints of stem also send out roots. These are early instances of 142. Secondary Roots, i. e. roots emitted by other parts of the ascending axis than the radicle. Most creeping plants produce them at every joint; and most branches, when bent to the ground and covered with earth, so as to afford the moisture and darkness they require, will strike root. So, often, will separate pieces of young stems, if due care be taken; as when plants are propagated by cuttings. Cryptogamous plants, growing from spores and hav- ing no embryo stem or axis to commence with, are furnished with secondary roots only, 143. Viewed as to the duration of the plant, roots are distin- guished into annual, biennial, and perennval. 144. Annual Roots are those of a plant which springs from the seed, flowers, and dies the same year or season. Such plants always have fibrous roots, composed of numerous slender branches, fibres, or rootlets, proceeding laterally from the main or tap-root ; or else the whole root divides at once into such fibrous branches, as in all annual Grasses (Fig. 180). These multiplied rootlets are well adapted for absorption from the soil, but for that alone. The food which the roots absorb, after being digested and elaborated in the leaves, is all expended in the production of new leafy branches, and at length of blossoms. The flowering process and the maturing of the fruit exhaust the vegetable greatly (in a manner hereafter to be explained), consuming all the nourishing material which it con- tains, or storing it up in the fruit or seed for its offspring; and the exhausted plant perishes at the close of the season, or whenever it has fully gone to seed. 145. Biennial Roots are those of plants which do not blossom until the second season, and which die when they have matured their 84 THE ROOT. seed. Such plants send up no lengthened stem during the first summer, but produce a large tuft of leaves next the ground, and proceed to elaborate what they re- ceive from the roots and from the air into organic or nourishing matter, and store it up in the root, in the form of starch, vegetable jelly, and the like. The root enlarges, or becomes fleshy, as this accumulates. In biennials this accumulation generally takes place in the primary or main root, as in the Radish, Carrot, Beet, &e. This, when only moderately thickened and taper- ing downwards, is a common tap-root : when more enlarged and broadest at the crown, or junction with the ex- tremely abbreviated stem, it forms a conical root, like that of the common Beet and Parsnip: when broadest in the middle and tapering to both ends, it is spindle-shaped or fust- form, as in the Radish (Fig. 1388): when much broader than long, and abruptly contracted below, like a turnip, it is napiform. Such roots, abounding in nourishment, are appropriated by man for food. The plant itself uses this store for the same purpose. When the vegetation of these biennials is resumed, the following spring, the new shoots, fed by this abundant stock of nourishment provided for them, grow with great vigor, and produce flowers, fruit, and seed almost entirely at its expense ; and this stock being exhausted by the time the seeds are matured, when the cells of the great root will be found to be emptied of their contents and dead, the plant perishes. 146. Perennial Roots are those of plants which last year after year. In shrubs and trees the roots themselves live and grow indefinitely ; but in perennial herbs the same roots seldom survive more than a year or two, and a new set is formed annually. Here, also, a store of nourishment for the vigorous commencement of the succeeding year’s growth is not unfrequently deposited in the root. The Sweet Potato, the Peony, and the Dahlia (Fig. 159), furnish good illustra- tions of the kind. These roots are generally fasetcled or clustered ; that is, they consist of a cluster of roots from the base of the stem. FIG, 138. Fusiform root of the Radish, with some foliage. ITS STRUCTURE AND GROWTH. 85 While some of these remain slender and serve merely for absorption, others, thickened by this deposit, may become tuberous (as in Fig. 139); and buds, formed on the stem just above, draw upon this store when they start into growth in the spring. These particular roots perish when exhausted of their store; but new accumulations have meanwhile been formed in some of the roots of the season, which serve the same purpose the following spring ; and so the plant survives, year after year. 147. Some less ordinary modifica- tions of roots remain to be noticed. It has already been stated that they may spring (as secondary roots, 142) from any part of the stem, although they commonly do so only when. this rests on or is covered by the soil, which affords the darkness and moisture congenial to them. Some stems, however, strike root freely in the open air, forming 148. Aerial Roots, The Ivy of Europe, our own Poison Ivy (Rhus Toxicodendron), and the Trumpet Creeper climb by such roots, in the form of small rootlets, which attach themselves to the bark of trees, &c. These serve merely for mechanical support. Other plants produce larger aerial roots, which, emitted from the stem in the open air, descend to the ground and establish themselves in the soil. This may be observed, on a small scale, in the stems of In- dian Corn, where the lower joints often produce roots which grow to the length of several inches before they reach the ground. More remarkable cases of the kind abound in those tropical regions where the sultry air, saturated with moisture for a large part of the year, favors the utmost luxuriance of vegetation. The Pandanus or Screw-Pine (a Palm-like tree, often cultivated in our conserva- tories) affords a well-known instance. Here (Fig. 140) strong roots, emitted in the open air from the lower part of the trunk, and soon reaching the soil, give the tree the appearance of having been par- tially raised out of the ground. The famous Banyan-tree of India (Fig. 142) affords a still more striking illustration. In this the FIG. 189. Fascicled tuberous roots of the Dahlia. 8 86 aerial rootlets strike from the horizontal branches of the tree, often at a great height, at first swinging free in the air, but finally reach- BES VE 140 Nine ing and establishing themselves in the ground, where they increase in diame- ter and form acces- sory trunks, sur- rounding the origi- nal boll and sup- porting the wide- spread canopy of branches and_ foli- age. Very similar is the economy of the Mangrove (Fig. 141), which forms impenetrable thick- ets on low and mud- dy sea-shores in the tropics, and even oceurs on the coast of Florida and Lou- isiana. Here aerial roots spring not only from the main trunk, as in the Pandanus, but also from the branchlets, as in the Banyan. FIG. 140. The Pandanus, or Screw-Pine; with, 141, a Mangrove-tree (Rhizophora Mangle} FIG. 142. The Banyan-tree, or Indian Fig (Ficus Indica). EPIPHYTES OR AIR-PLANTS. 87 Moreover, this tendency to shoot in the air is shown even in the embryo, which begins to germinate while the fruit is yet attached to the parent branch, often elongating its radicle to the length of a foot or more before the fruit falls to the ground. 149. Epiphytes, or Air-Plants, exhibit a further peculiarity. Their roots not only strike in the open air, but throughout their life have no connection with the soil. These generally grow upon the trunks and branches of trees; their roots merely adhering to the bark to fix the plant in its position, or else hanging loose in the air, from which such plants draw all their nourishment. Of this kind are a “large portion of the gorgeous Orchidaceous plants of very warm and humid climes, which are so much prized in hot-houses, and which, in their flowers as well as their general aspect, exhibit such fantastic and infinitely varied forms, Some of the flowers resemble butter- flies, or strange insects, in shape as well as in gaudy coloring; such, for example, as the Oncidium Papilio (Fig. 143). To another FIG. 148. Oncidium Papilio, and, 144, Comparettia rosea; two epiphytes of the Orchis family ; showing the mode in which these Air-plants grow. 88 THE ROOT. family of Epiphytic plants belongs the Tillandsia, or Long Moss, which, pendent in long and gray tangled clusters or festoons from the branches of the Live-Oak or Long-leaved Pine, gives such a peculiar and sombre aspect to the forests of the warmer portions of our Southern States. They are called Air-plants, in allusion to the source of their nourishment; and Epiphytes, from their grow- ing upon other plants, and in contradistinction to 150. Parasites, that not only grow upon other vegetables, but live at their expense; which Epiphytes do not. Parasitic plants may be divided into two sorts, viz.:— 1st, those that have green foliage ; and 2d, those that are destitute of green foliage. They may vary also in the degree of parasitism ; some being absolutely dependent upon the foster plant for nourishment, while others, such as the Cursed Fig (Clusia rosea) of Tropical America, often take root in the soil, and thence derive a part of their support. The latter oc- curs only in 151. Green Parasites, or those furnished with green foliage, or proper digestive organs of their own. These strike their roots through the bark and directly into the new wood of the foster plant ; whence they draw the ascending, mostly crude sap, which they have to assimilate in their own green leaves. The Mistletoe is the most familiar example of this class. It is always com- pletely parasitic, being at no period connected with the earth; but the seed germinates upon the trunk or branch of the 146 FIG 145. Roots of Gerardia flava ; some of the rootlets attaching themselves parasitically to the root ofa Blueberry. (From a drawing by Mr. J Stauffer ) FIG. 146. Section of one of the attached rootlets, showing the union. PARASITIC PLANTS. 89 tree where it happens to fall, and its nascent root, or rather the woody mass that it produces in place of the root, penetrates the bark of the foster stem, and forms as close a junction with its young wood as that of a natural branch. The Cursed Fig, commonly be- ginning as a parasite, sends down aerial roots, some of which strike into the wood of the foster tree lower down, while ‘others descend to the ground and draw from it a portion of their sustenance in the ordinary manner. Some common herbaceous plants, hitherto not suspected of such habits, have recently been found to fix themselves clandestinely, under ground, by means of some of their rootlets, to the roots of neighboring plants, and furtively draw from them a portion of their sustenance. This is the case with our Comandra, as well as with the Thesiums of the Old World, and also with our Gerardias and many other plants of that family, which have long been known as uncultivable, although the cause of their being so has only lately heen detected. It would appear that this partial parasitism is necessary to their existence. Gerardia appears to im- plant its rootlets upon the bark of the roots of neighboring shrubs, and therefore to steal elaborated sap (Fig. 145, 146). 152. Pale or Colored Parasites, such as Beech-Drops, Pine-Sap, &c.pare those which are destitute of green herbage, and are usually.of a white, tawny, or reddish hue ; in fact, of any color except green. These strike their roots, or sucker-shaped discs, into the bark, mostly that of the root, of other plants, and thence draw their food from the sap already elaborated. They have accordingly no occasion for digestive organs of their own, i. e. for green foliage. The Dodder (Fig. 147) is a common plant of this kind which is parasitic above ground. Its seeds germinate in the earth; but when the slender twining stem reaches the surrounding en a0 ig FIG. 147. The common Dodder of the Northern States (Cuscuta Gronovii), of the natural size, parasitic upon the stem of an herb: the uncoiled portion at the lower end shows the mode of its attachment. 148. The coiled embryo taken from the seed, moderately magnified. / 149. The same in germination ; the lower end elongating into a root, the upper into a thread- like leafless stem. 8* 90 THE ROOT, herbage, it forms suckers, which attach themselves firmly to the surface of the supporting plant, penetrate its epidermis, and feed upon its juices ; while the original root and base of the stem perish, and the plant has no longer any connection with the soil. Thus stealing its nourishment ready prepared, it requires no proper diges- tive organs of its own, and, consequently, does not produce leaves. This economy is foreshadowed in the embryo of the Dodder, which is a naked thread spirally coiled in the seed (Fig. 148, 149), and presenting no vestige of cotyledons or seed-leaves. A species of Dod- der infests and greatly injures flax in Europe, and sometimes makes its appearance in our own flax-fields, having been introduced with the imported seed. Such parasites do not live upon all plants in- discriminately, but only upon those whose elaborate juices furnish a propitious nourishment. Some of them are restricted, or. nearly so, to a particular species; others show little preference, or are found indifferently upon several species of different families. Their seeds, in some cases, it is said, will germinate only when in contact with the stem or root of the species upon which they are destined to live. Having no need of herbage, such plants may be reduced to a stalk bearing a single flower (Fig. 965) or a cluster of flowers (Fig. 968), or even to a single blossom developed from a bud directly parasitic on the bark of the foster plant. Of this kind are the several species of Pilostyles (parasitic flowers on the shoots of Leguminous plants) in Tropical America, one species of which was recently discovered by Mr. Thurber near the southern borders of New Mexico. Here the flowers are small, only about a quarter of an inch in diameter. The most wonderful plant of this kind is that vegetable Titan, the Rafilesia Arnoldi of Sumatra (Fig. 150), which grows upon the stem of a kind of Grape-vine. It is a parasitic flower, measuring FIG. 150. Rafflesia Arnoldi; an expanded flower, and a bud, directly parasitic on the stem of a vine: reduced to the scale of half an inch to a foot. THE STEM. 91 nine feet in circumference, and weighing fifteen pounds! Its color is light orange, mottled with yellowish-white. 153. Among Cryptogamous plants, numerous Fungi are parasitic upon living, especially upon languishing vegetables ; others infest living animals; the rest feed on dead or decaying vegetable or animal matters: all are destitute of chlorophyll or anything like green herbage. It is probable that our Monotropa, or Indian Pipe, a pallid Phenogamous plant, looking like a Fungus, actually lives like one, and draws its nourishment, at least in great part, from the decaying leaves among which it grows. CHAPTER IV. OF THE STEM, OR ASCENDING AXIS. Sect. I. Irs GENERAL CHARACTERISTICS AND Mopr or GrowTu.. 154. Tux Stem is the ascending axis, or that portion of the trunk which in the embryo grows in an opposite direction from the root,. seeking the light, and exposing itself as much as possible to the air. All Phanogamous plants (114) possess stems. In those which are said to be acaulescent, or stemless, it is either very short, or concealed beneath the ground. Although the stem always takes an ascending direction at the commencement of its growth, it does not uniformly retain it; but sometimes trails along the surface of the ground, or burrows beneath it, sending up branches, flower-stalks, or leaves into the air. The common idea, that all the subterranean portion of a plant belongs to the root, is by no means correct. 155. The root gives birth to no other organs, but itself directly performs those functions which pertain to the relations of the vege— table with the soil;——its branches bind the plant to the earth; its newly formed extremities or rootlets imbibe nourishment from: it.. But the aerial functions of vegetation are chiefly carried on, not so- much by the stem itself as by a distinct set of organs which it bears,. namely, the leaves. Hence, the production of leaves is one of the: 92 THE STEM, characteristics of the stem. These are produced only at certain definite and symmetrically arranged points, called 156. Nodes, literally ‘nots, so named because the tissues are here more or less condensed, interlaced, or interrupted, as is conspicuous- ly seen in the Bamboo, in a stalk of Indian Corn, or of any other Grass. Here each node forms a complete ring, because the leaf drises from the whole circumference of the stem at that place. When the base of the leaf or leatstalk occupies only a part of the circumference, the nodes are not so distinctly marked, except by the leaves they bear, or by the scars left by their fall (Fig. 151, &c.) They are often called joints, and sometimes, indeed, the stem is actually jointed, or articulated, at these points ; but commonly there is no tendency to separate there. Each node bears either a single leaf (as in Fig. 111, 121, &c.), or two leaves placed on opposite sides of the stem (as in Fig. 107), or else three or more, placed in a ring (in botanical language, a whorl or verticil) around the stem. The naked portions or spaces that intervene between the nodes are termed 157. Internodes. The undeveloped stem is, in fact, made up of a certain number of these leaf-bearing points, separated by short in- tervals ; and its growth consists, primarily, in the successive elonga- tion of these internodes so as to separate the nodes more or less, and allow the leaves to expand. : 158. This brings to view the leading peculiarity of the stem; namely, that it is formed of a succession of similar parts, developed one upon the summit of another, each with its own independent growth. Each developing internode, moreover, lengthens through- out its whole body, unlike the root, which elongates continuously from its extremity alone (121). To have a good idea of this, we have only to observe the gradual evolution of a germinating plant, where each internode develops nearly to its full length, and ex- pands the leaf or pair of leaves it bears, before the elongation of the succeeding one commences. As already described (120, &c.), the radicle, or internode which pre-exists in the embryo, elongates, and raises the seed-leaves into the air; they expand and elaborate the material for the next joint, the leaves of which in turn prepare the material for the third, and so on. The internode lengthens principally by the elongation of its already formed cells, particularly in its lower part, which continues to grow after the upper portion has finished. ITS STRUCTURE AND GROWTH. 93 159. Buds, The apex of the stem, accordingly, is always crowned with an undeveloped portion, with rudimentary parts similar to those already unfolded, that is, with a Bup. The embryo itself may be viewed as an internode (the radicle) bearing the fundamental bud (the plumule) on its apex, from which the whole plant is de- veloped, just as an ordinary bud of a tree or shrub develops to form the growth of the season. Except that, in the latter case, the different steps follow each other more closely; for the bud usually has a considerable number of parts ready formed in miniature before it begins to grow, and has a full store of assimilated sap accumulated in the parent stem to feed upon. This is no less the case in many strong embryos highly developed in the seed, and Pati lied with abundant nourishment, either in the cotyledons, as in the Pea (Fig. 119) and Oak (Fig. 120), or in the albumen, as in Indian Corn (Fig. 126-180). The strong buds which in many shrubs and trees crown the apex of a stem when it has completed its growth for the season, often exhibit the whole plan and amount of the next year’s growth; the nodes, and even the leaves they bear, being already formed, and only re- quiring the elongation of the internodes for their full ex- pansion. This is rudely shown in the annexed diagrams, Fig. 151, 152. As the bud (Fig. 153) is well supplied with nourishment in spring by the stem on which it rests, its axis elongates rapidly ; and although the growth commences with the lowest internode, yet the second, third, FIG. 151. Diagram of the vertical section of a strong bud, such as that of Horsechestnut. FIG. 152. The axis of the same developing, the elongation beginning with the lowest inter- node, soon followed by the others in succession. FIG. 153. A year’s growth of Horsechestnut, crowned with a terminal bud: a, scars left by the bud-scales of the previous year: b, scars left by the fallen leafstalks : c, axillary buds. FIG. 154. Branch and buds (all axillary) of the lilac. 94 THE STEM, and fourth internodes, &c. have begun to lengthen long before the first has attained its full growth. The stem thus continued from a terminal bud is, if it survive, again terminated with a similar bud at the close of the season, which in its development repeats the same process. A set of narrow rings on the bark (Fig. 153, a) commonly mark the limit of each year’s growth. These are the scars left by the fall of the scales of the bud; and these, in the Horsechest- nut, and other trees with large scaly buds, may be traced back on the stem for a series of years, growing fainter with age, until they are at length ob- literated by the. action of the weather and the distention caused by the in- crease of the stem in diameter. The same is the case with the more con- spicuous leaf-scars, or marks on the bark left by the separation of the leaf- stalk, which are for a long time con- spicuous on the shoots of the Horse- chestnut (Fig. 153, 6) and the Mag- nolia (Fig. 155). 160. A bud, therefore, is nothing more than the first stage in the de- velopment of a stem, with the axis still so short that the rudimentary leaves within successively cover each other, while the whole is covered and pro- tected by the scales without. Buds vary greatly, however, in size, ap- pearance, and degree of development. Those of many shrubs and trees are minute, and hidden by the bark until their vernal growth commences, as in FIG. 155. Branch of Magnolia Umbrella, of the natural size, crowned with the terminal bud; and below exhibiting the large, rounded Jeaf-scars, as well as the rings or annular scars left by the fall of the bud-scales of the previous season. 156. A detached scale from a similar bud ; its thickened axis is the base of a leafstalk ; the membranous sides consist of the pair of stipules, ITS STRUCTURE AND GROWTH. 95 Sumac, Locust, Honey-Locust (Fig. 164), &c.: in these buds the parts are few and very rudimentary, and are mostly formed as they develop. In some, they are naked, that is, are entirely destitute of protecting scales, and exhibit the forming leaves directly exposed to the air, just as they are in herbs. This occurs in many tropical trees, but not in all, and in some shrubs of cold climates, such as our Viburnum nudum and V. lantanoides. But the greater number of plants which have a winter to endure are provided with scaly buds. Those of Beech and Hickory, as well as of Horsechest- nut and Magnolia already referred to, are conspicuous and well- developed examples. The scales serve to protect the tender parts within against injury from moisture and from sudden changes in temperature during the dormant state. To ward off moisture more effectually, they are sometimes coated with a waxy, resinous, or balsamic exudation, as is conspicuous on the scales of the Horse- chestnut, Balsam-Poplar or Balm of Gilead, and Balsam-Fir. To guard against sudden changes of temperature, they are often lined, or the rudimentary leaves within invested with non-conducting down or wool. 161. The bud-scales themselves are leaves in a modified state. This is evident from their situation and arrangement, which are the same as of the proper leaves of the species, and by the gradual transitions from the former to the latter in many plants. In the turtons, or subterranean budding shoots of numerous perennial herbs, and in the unfolding buds of the Lilac and Sweet Buckeye (4Zésculus parviflora), every gradation may be traced between bud- scales and foliage, showing that no absolute line can be drawn be- tween them, but that the two are essentially of the same nature, i. e. are different modifications of the same organ. 162. Plan of Vegetation, In fact, a simple stem bears nothing but leaves in some form or other, and its branches are only repetitions of itself, following the same laws. The embryo consists of a pri- mary joint of stem crowned with a bud, the first leaves or leaf of which takes the special form of cotyledons ; the following ones de- velop as ordinary foliage, and leaf after leaf, or pair after pair, is formed and elevated upon the successive internodes as the stem is built up. At the close of the growing season, if the stem is to endure, this is terminated, as it began, by a bud; and the bud-scales, if any, are leaves developed in this peculiar form, subservient to protection alone, and borne upon nodes which are never separated 96 THE STEM. by elongation of the internodes. With the ensuing spring growth recommences, and another set of internodes, and of nodes bearing ordinary leaves, form the second year’s growth, like the first; and so, by annual increments, a simple leafy stem is developed and carried up. Not only is the whole stem growing from year to year thus composed of a succession of similar growths, each the offspring of the preceding and the parent of the next, Vv but also each annual growth itself consists of a | é lineal succession of similar parts, viz. of leaf- bearing joints of stem, developed each upon its f predecessor, and in turn surmounted by the next in the series. These s¢milar parts, which by their repetition make up the Phznogamous plant, have been termed 163. Phytons (from the Greek qurd», plant), or plant-elements. The first phyton is the radicle of the embryo, with its cotyledon or pair of cotyledons, from its base developing the root, from above expanding its leaf or pair of leaves (as already described in detail, 119- 122), and then giving birth to the next phyton, d or joint of stem and leaf, and so on, in lineal succession. So that the whole herb, shrub, or ; e tree, as to its upward growth, is a multiplica- tion of the simple plantlet it began with as it developed from the seed. Moreover, any joint , of stem, when favorably situated for the pur- pose, may produce secondary roots (142), and thus complete the vegetable individuality, hav- ing all the organs of vegetation (116). 164. The repetition of these similar parts in tor the direct line, each from the summit of its pre- decessor, builds up a simple or main stem, to which many plants are restricted during the first year’s growth, and some, such as Palms and Reeds, throughout their whole existence. Their production from new starting-points gives rise to branches. FIG. 157. Diagram of a simple-stemmed plant, like a Grass, and of the similar parts, or pbytons, @ to g, of which it is composed. RAMIFICATION. 97 Szot. II. Ramrricarron. 165. Branches spring from lateral or axillary buds. These are new growing points, which habitually appear, or at least may ap- pear, one (or occasionally two or three) in the ail of each leaf, — that is, in the upper angle which the leaf forms with the stem. (See Fig. 153, c, where the point at which the fallen leaves were attached is marked by the broad scar, 6, just below the bud.) When these buds grow, they give rise to BRANCHES; which are repetitions, as it were, of the main stem, growing just as that did from the seed; ex- cepting merely, that, while that was implanted in the ground, these proceed from the parent stem. The branches are in turn provided with similar buds in the axils of their leaves, capable of developing into branches of a third order, and so on indefinitely, producing the whole ramification of the plant. The ultimate ramifications are termed BraNcHLETS. 166. The arrangement of axillary buds depends upon that of the leaves. When the leaves are opposite (that is, two on each node, placed on opposite sides of the stem), the buds in their axils are consequently opposite ; as in the Maple, Horsechestnut (Fig. 153), Lilac (Fig. 154), &e. When the leaves are alternate, or one upon each node, as in the Apple, Poplar, Oak, Magnolia (Fig. 155), &c., the buds implicitly follow the same arrangement. Branches, there- fore, being developed axillary buds, their arrangement follows that of the leaves. When the leaves are alternate, the branches will be alternate ; when the leaves are opposite, and the buds develop regu- larly, the branches will be opposite. But the perfect symmetry of the ramification, thus provided for, is frequently obscured by the 167. Non-development of some of the Buds, As the original bud of the embryo remains for a time latent in the seed, growing only when a conjunction of favorable circumstances calls its life into action, so also many of the buds of a shrub or tree may remain latent for a long time, and many of them fail to grow at all. In our trees, most of the lateral buds generally remain dormant for the first season: they appear in the axils of the leaves early in summer, but do not grow into branches until the following spring; and even then only a part of them usually grow. Sometimes the failure occurs without appreciable order; but it often follows a nearly uniform rule in each species. Thus, when the leaves are opposite, there are 9 98 THE STEM. usually three buds at the apex of a branch; namely, the terminal, and one in the axil of each leaf; but it seldom happens that all three develop at the same time. Sometimes the terminal bud con- tinues the branch, the two lateral generally remaining latent, as in the Horsechestnut (Fig. 153); sometimes the terminal one regu- larly fails, and the lateral ones grow, when the stem annually be- comes two-forked, as in the Lilac (Fig. 154). The undeveloped buds do not necessarily perish, but are ready to be called into action in case the others are checked. When the terminal buds are destroyed, some of the lateral, that would else remain dormant, develop in their stead, incited by the abundance of nourishment, which the former would have monopolized. In this manner our trees are soon reclothed with verdure, after their tender foliage and branches have been killed by a late vernal frost, or other injury. And buds which have remained latent for several years occasionally shoot forth into branches from the sides of old stems. Such branch- es, however, more commonly originate from irregular, accidental, or, as they are named 168. Adventitious Buds. It has been already remarked, that roots, although naturally destitute of buds, do yet produce them in certain plants, especially when wounded (139). So likewise do the stems of some shrubs and trees, especially when surcharged with sap, as is commonly seen in Willows and Lombardy Poplars. Here buds break out habitually on the sides of trunks, at least when they are wounded or pollarded, or spring from the cut surface where the bark and wood join. These adventitious buds do not originate from nodes, nor affect any order in their appearance, but are wholly casual as to the point of origin. Thus the predestined symmetry of the branches is obscured or interfered with in two distinct ways; first, by the failure of a part of the regular buds to develop; and secondly, by the irregular and casual development of buds from other parts than the axils of the leaves: to which we may add, that great numbers of branches perish and fall away after they have be- gun to grow. There is still another source of irregularity, namely, the production of 169. Accessory Buds. These are, as it were, multiplications of the regular axillary bud, giving rise to two, three, or more buds, instead of one; in some cases situated one above another, in others side by side. In the latter case, which occurs occasionally in the Hawthorn, in certain Willows, in the Maples (Fig, 158), &c., the axillary bud RAMIFICATION. 99 seems to divide into three, or itself give rise to a lateral bud on each side. On some shoots of the Tartarean Honeysuckle (Fig. 160) from three to six buds appear in each axil, one above another, the lower being successively the stronger and earlier produced, and the one immediately in the axil, therefore, grows in preference: oc- casionally two or more of them grow, and superposed accessory branches result. It is much the same in Aristolochia Sipho, except that the uppermost bud is there strongest. So it is in the Butternut (Fig. 159), where the true axillary bud is mi- nute and usually remains latent, while the accessory ones are considerably remote, and the uppermost, which is much the strongest, is far out of the axil; this usually develops, and gives rise to an extra-axillary branch. 170. Exeurrent and Deliquescent Stems. Sometimes the primary axis is prolonged without interruption, by the continued evolution of a terminal bud, even through the whole life of a tree (unless acciden- tally. destroyed), forming an undivided main trunk, from which lateral branches proceed; as in most Fir- trees. Such a trunk is said to be excurrent. In other cases the mairi stem is arrested, sooner or later, either by flowering, by the failure of the terminal bud, or by the more vigorous development of some of the lateral buds; and thus the trunk is dissolved into branches, or is deliquescent, as in the White Elm and in most of our deciduous-leaved trees. The first naturally gives rise to conical FIG. 158. Branch of Red Maple, with triple axillary buds, placed side by side. FIG. 159. Piece of a branch of the Butternut, with accessory buds placed one above another : a, the leaf-scar: 6, proper axillary bud: c, d, accessory buds. FIG 160. Part of a branch of Tartarean Honeysuckle, with crowded accessory buds in each axil. 100 THE STEM. or spire-shaped trees; the second, to rounded or spreading forms. As stems extend upward and evolve new branches, those near the base, being overshadowed, are apt to perish, and thus the trunk be- comes naked below. This is well scen in the excurrent trunks of. Firs and Pines, which, when grown in forest, seem to have been branchless for a great height. But the knots in the centre of the trunk are the bases of branches, which have long since perished, and have been covered with a great number of annual layers of wood, forming the clear stuff of the trunk. 171. Definite and Indefinite Annual Growth of Branches, In the larger number of our trees and shrubs, especially those with scaly buds, the whole year’s growth is either already laid down rudi- mentally in the bud (159), or else is early formed, and the develop- ment is completed long before the end of summer ; when the shoot is crowned with a vigorous terminal bud, as in the Horsechestnut (Fig. 158) and Magnolia (Fig. 155), or with the uppermost axillary buds, as in the Lilac (Fig. 154) and Elm. Such definite shoots do not die down at all the following winter, but grow on directly, the next spring, from these terminal or upper buds, which are generally more vigorous than those lower down. In other cases, on the contrary, the branches grow onward indefinitely through the whole summer, or until arrested by the cold of autumn: they mature no buds at or near their summit; or at least the lower and older axillary buds are more vigorous, and alone develop into branches the next spring; the later-formed upper portion most commonly perishing from. the apex downward for a certain length in the winter. The Rose and Raspberry, and among trees the Sumac and Honey Locust, are good illustrations of this sort; and so are most perennial herbs, their stems dying down to or beneath the surface of the ground, where the persistent base is charged with vigorous buds, well pro- tected by the ground, for the next year’s vegetation. 172. Propagation from Buds. Buds, being, as it were, new indi- viduals springing from the original stem, may be removed and attached to other parts of the parent trunk, or to that of another individual of the same, or even of a different, but nearly related species, where they will grow equally well. This is directly accom- plished in the operation of budding. In ingrafting, the bud is transferred, along with a portion of the shoot on which it grew. Moreover, as the cut end of such shoots, when buried in moist and warm soil, will commonly, under due care, send out adventitious KINDS OF STEM AND BRANCHES. 101° roots, they may be made to grow independently, drawing their nourishment immediately from the soil, instead of indirectly through the parent trunk. This is done in the propagation of plants by cuttings. The great importance of these horticultural operations depends chiefly on the well-known fact, that buds propagate indi- vidual peculiarities, which are commonly lost in raising plants from the seed. Sect. III. Tue Kinps or Stem anp BRANCHES. 173. On the size and duration of the stem the oldest and most obvious division of plants is founded, namely, into Herbs, Shrubs, and Trees. 174. Herbs are plants in which the stem does not become woody and persistent, but dies annually or after flowering, down to the ground at least. .The difference between annual, biennial, and perennial herbs has already been pointed out (144-146). The same species is so often either annual or biennial, according to cir- cumstances or the mode of management, that it is convenient to have a common name for plants that flower and fruit but once, at whatever period, and then perish: such De Candolle accordingly designated as Monocarpic plants; while to perennials, whether herbaceous or woody, large or small, he applied the counterpart name of Potycarric plants, signifying that they bear fruit an indefinite number of times. 175. Undershrubs, or suffruticose plants, are woody plants of hum- ble stature, their stems rising little above the surface. If less decidedly woody, they are termed suffrutescent. 176. Shrubs are woody plants, with stems branched from or néar the ground, and less than five times the height of a man. Between shrubs and trees there is every intermediate gradation. A shrub which approaches a tree in size, or imitates it in aspect, is said to be arborescent. 177. Trees are woody plants with single trunks, which attain at least five times the human stature. 178. A Culm is a name applied to the peculiar jointed stem of Grasses and Sedges, whether herbaceous, as in most Grasses, or woody or arborescent, as in the Bamboo. 179. A Caudex is a name usually applied to a Palm-stem (Fig. g* 102 THE STEM. 184), to that of a Tree Fern (Fig. 100), and to any persistent, erect or ascending, root-like forms of main stems. 180. Those stems which are too weak to stand upright, but re- cline on the ground, rising, however, towards the extremity, are said to be decumbent: if they rise obliquely from near the base, they are said to be ascending. When they trail flat on the ground, they are procumbent, prostrate, or running ; and when such stems strike root from their lower surface, as they are apt to do, they are said to be creeping, or repent. They are climbing when they cling to neighboring objects for support; whether by tendrils, as the Vine and Passion-flower, by their leafstalks, as the Virgin’s Bower (Clematis), or by aerial rootlets, as the Poison Oak (Rhus); and twining, or voluble plants, when they rise, like the Convolvulus, by coiling spirally around stems or other bodies within their reach. Other modifications of the stem or branches have received particu- lar names, some of which merit notice from having undoubtedly sug- gested several operations by which the cultivator multiplies plants. 181. A Stolon is a branch which naturally curves or falls down to the ground, where, favored by shade and moisture, it strikes root, and then forms an ascending stem, capable of drawing its nourish- ment directly from the soil, and, by the perishing of the portion which connects it with the parent stem, at length acquiring an entirely separate existence. The Currant, Gooseberry, &c., multi- ply in this way, and doubtless suggested to the gardener the opera- tion of layering ; in which he not only takes advantage of and accelerates the attempts of nature, but incites it in species which do not ordinarily multiply in this manner. 182. A Sucker is a branch of subterranean origin, which, after run- ning horizontally and emitting roots in its course, at length, follow- ing its natural tendency, rises out of the ground and forms an erect stem. The Rose, the Raspberry, and the Mint afford familiar illus- trations, as well as many other species which shoot up stems “ from the root,” as is generally thought, but really from subterranean branches. Cutting off the connection with the original root, the gardener propagates such plants by division. 183. A Runner, of which the Strawberry furnishes the most familiar example, is a prostrate, slender branch, sent off from the base of the parent stem, which strikes root at its apex, and produces a tuft of leaves; thus giving rise to an independent plant capable of extend- ing itself in the same manner. RUNNERS, TENDRILS, ETC. 103 184. An Offset is a similar, but short, prostrate branch, with a tuft of leaves at the end, which, resting on the ground, there takes root, and at length becomes independ- ent; as in the Houseleek. 185. A Tendril is commonly a thread-like, leafless branch, capable of coiling spirally, by which some climbing plants attach themselves to surrounding bodies for support; as in the Grape-vine (Fig. 161). But sometimes tendrils belong to the leaves, as in the Pea; when they are slender prolongations of the leafstalk. Some tendrils cling by hooking their tips around the supporting object. Others, such as those of the Virginia Creeper (Fig. 162, 163), commonly expand the tips of the tendrils into a flat dise, — much as do many aerial rootlets (as those of Ivy) when subservient to the same office, — which firmly ad- heres to walls or the bark of trees, thus enabling the plant to ascend and cover their surface. As soon as they are attached, the tendril FIG. 161. End of a shoot of the Grape-vine, with young tendrils. FIG. 162. A portion of a stem of Ampelopsis, or Virginia Creeper, with a leaf and a tendriL FIG. 163. Ends of the latter, enlarged, showing the expanded tips by which they cling. ¢ 104 THE STEM. usually shortens itself by coiling spirally, thus drawing up the climbing shoot closer to the supporting object. 186. A Spine or Thorn is an imperfectly developed, indurated, leaf- less branch of a woody plant, attenuated to a point. The nature of spines is manifest in the Haw- thorn (Fig. 165), not only by their position in the axil of a leaf, but often by producing im- perfect leaves and buds. And in the Sloe, Pear, &c., many of the stinted branches become spinose or spinescent at the apex, tapering off gradually in- to a rigid, leafless point, thus exhibiting every gradation be- tween a spine and an ordinary branch. These spinose branch- es are less liable to appear on the cultivated tree, when duly cared for, such branches being thrown mostly into more vigor- ous growth. Inthe Hawthorn, the spines spring from the main axillary bud, while accessory buds (169), one on each side, ap- pear, and one or both grow the next season into an ordinary branch. In the Honey Locust, it is the uppermost of several ac- cessory buds, placed far above the axil, that develops into the thorn (Fig. 164). And here the spine itself branches, and sometimes be- | } | 3 comes extremely compound. Sometimes the stipules of the leaves develop into spines, as in the Prickly Ash. Sometimes the leaf it- self is developed as a spine; of which the Barberry affords a familiar example. When the spine is situated in the axil of a leaf or a leaf- scar, it is necessarily of the nature of a branch. When it bears a FIG. 164. Branching thorn of the Honey Locust (Gleditschia), an indurated branch devel- oped from an accessory bud produced above the axil. a, Three buds under the base of the leafstalk, brought to view in a section of the stem and leafstalk below. FIG. 165. Thorn of the Cockspur Thorn, developed from the central of three axillary buds ; one of the lateral buds is seen at its base. ITS SUBTERRANEAN MODIFICATIONS. 105 bud or branch in its axil (as in the Barberry, Fig. 296), it must be of the nature of a leaf. 187. The Subterranean Modifications of the Stem are scarcely less numerous and diverse than the aerial; but they may all be reduced to a few principal types. They are perfectly distinguishable from roots by producing regular buds, or by being marked with scars, which indicate the former insertion of leaves, or furnished with scales, which are the rudiments or the vestiges of leaves. All the Scaly roots of the older botanists are therefore forms of the stem or branches, with which they accord in every essential respect. So, likewise, what are popularly called Creeping roots are really subter- ranean branches; such as those of the Mint, and of most Sedges and Grasses. Some of these, such as the Carex arenaria (Fig. 166) of Europe, render important service in binding the shifting sands of the sea-shore. Others, like the Couch-Grass, are often very trouble- some to the agriculturist, who finds it next to impossible to destroy them by the ordinary operations of husbandry ; for, being furnished with buds and roots at every node, which are extremely tenacious of life, when torn in pieces by the plough, each fragment is only placed in the more favorable condition for becoming an independent plant. The Nut-Grass (Cyperus Hydra), an equally troublesome pest to the planters of Carolina and Georgia, is similarly constituted; and FIG, 166. Creeping subterranean stem of Carex arenaria. FIG. 167. Rhizoma of Diphylleia cymosa, showing six years’ growth, and a bud for the seventh : a, the bud: b, base of the stalk of the current year: ¢, scar left by the decay of the annual stalk of the year before ; and beyond are the scars of previous years. 106 THE STEM. besides, the interminable subterranean branches bear tubers, or reservoirs of nutritive matter, in their course, which have still greater powers of vitality, as they contain a copious store of food for the development of the buds they bear. The name of 188. Rhizoma or Rootstock is applied in a general way to all these perennial, horizontally elongated, more or less subterranean, root- like forms of the stem; and more particu- larly to those that are consid- erably — thick- ened by the ac- cumulation of starch or other forms of nutritive matter in their tissue, such as the so-called roots of Ginger, of the Iris or Flower-de-luce (Fig. 291), of the Calamus or Sweet Flag, and of the Blood- root. They grow after the manner of ordinary stems, advancing from year to year by the annual development of a bud at the apex, and emitting roots from the under side of the whole surface ; thus established, the older portions die and decay, as corresponding additions are made to the opposite growing extremity. Each year’s growth is often marked, as in some species of Iris (Fig. 291), by a narrowing at the place where the growth of the season is suspended, followed by an enlargement where it recom- mences; or else, as in the curious Diphylleia of 188 the Alleghany Mountains (Fig. 167), and the Polygonatum or Solomon’s Seal (Fig. 168), it is more indelibly stamped by an im- pressed circular scar (which has been likened to the impression of a seal), left annually, in autumn, by the death and separation from the perennial rootstock of the herbaceous stalk of the season which bore the foliage and blossoms. In Diphylleia the growth is so slow, and the ascending stems so thick, that the scars of successive years are FIG. 168. Rootstock of Polygonatum or Solomon’s Seal, with the terminal bud, the base of the stalk of the season, and three scars from which the latter has separated in as many former years, FIG. 169. The short and upright rootstock of Trillium erectum, or Birthroot, with its ter- minal bud. ROOTSTOCKS AND TUBERS. 107 nearly in contact (Fig. 167). In the very short and slow-growing rootstock of Trillium (Fig. 169), the base of the leaf-bearing and flowering stem of the season surrounds and covers the terminal bud. In our common Dentaria or Toothwort, and in Hydrophyllum, the base of this annual stalk or of the leafstalks partakes in the thicken- ing, and persists as a part of the rhizoma, in the form of fleshy scales or tooth-shaped processes. In other scaly rootstocks, these persist- ent bases of the leaves are thin, and more like bud-scales, and slowly decay after a year or two. All such markings are vestiges of leaves, &c., or the scars from which they have fallen or decayed away, and indicate the nodes. They show that the body that bears them belongs to the stem; and not to the root, which is wholly leafless. Root-stocks branch, just as other stems do, by the development of lateral buds from the axils of their scales or leaves. They serve as a reservoir of nourishing matter, for the maintenance of the an- nual growth, in the same manner as do thickened roots (145, 146). When such subterranean stems are thickened at the apex only, they produce 189. A Tuber, This is usually formed by the enlargement of the growing bud of a subterranean branch, and the deposition of starch, &c. in its tissue. This deposit serves for the nourishment of the buds (eyes) which it involves, when they develop the following year. The common Potato offers the most familiar example; and it is FIG. 170. Base of the stem of the Jerusalem Artichoke (Helianthus tuberosus), with its tubers. FIG. 171. A monstrous branch or bud of the Potato, above ground, showing a transition to the tuber. (From the Gardener’s Chronicle.) 108 : TIE STEM. very evident on inspection of the growing plant, that the tubers belong to branches, and not to the roots. The nature of the potate is also well shown by an accidental case (Fig. 171), in which some of the buds or branches above ground thickened and manifested a strong tendency to develop in the form of tubers. By heaping the soil around the stems, the number of tuberiferous branches is increased. The Jerusalem Artichoke also affords a familiar il- lustration of the tuber (Fig. 170). A tuber of a rounded form, and with few buds, or a rhizoma somewhat shorter and thicker than that in Fig. 109, effects a transition to 190. A Corm (Cormus), or Solid Bulb. This is a fleshy subterranean stem, of a rounded or oval figure and a compact texture; as in the Arum or Indian Turnip (Fig. 175), the Colchicum, the Crocus (Fig. 180, 181, 182), the Cyclamen,* &c. Corms have been termed solid bulbs. But the principal bulk of a true bulb consists not of stem but of leaves. * The flattened corm of Cyclamen originates from the dilatation of the radicle itself. In the Turnip, Beet, and Radish (Fig. 138), this also enlarges with the proper root, the upper part of which accordingly partakes of the nature of the stem. FIG. 172. The scaly bulb of a Lily. 178. A vertical section of the same, forming the an- nual stalk. 174 Axillary bulblets of Lilium bulbiferum. 175. Corm of Arum triphyllum. FIG. 176. A radical leaf of the White Lily, with its base thickened into a bulb-scale, cut across below to show its thickness. BULBS AND BULBLETS. 109 191. A Bulb is a permanently abbreviated stem, mostly shorter than broad, and clothed with scales, which are imperfect and thick- ened leaves, or more commonly the thickened and persistent bases of ordinary leaves (Fig. 176). In other words, it is a scaly and usually subterranean bud, with thickened scales, and a depressed axis which never elongates. Its centre or apex develops upward the herbaceous stalk, foliage, and flowers of the season, and beneath emits roots. In the bulb, the thickening by the deposition of nutri- tive matter, stored for future use, takes place in the leaves or scales it bears, instead of the stem itself, as in the preceding forms. The scales are sometimes separate, thick, and narrow, as in the Scaly bulb of the Lily (Fig. 172); sometimes broad and in concentric layers, as in the Tuntcated bulb of the Onion (Fig. 177). 192. Bulblets are small aerial bulbs, or buds with fleshy scales, which arise in the axils of the leaves of several plants, such as the common Lilium bulbiferum of the gardens (Fig. 174), and at length separate spontaneously, falling to the ground, where they strike root, and grow as independent plants. In the Onion, and other species of Allium, bulblets are often produced in place of flower-buds. These plainly show the identity of bulbs with buds. 198. All these extraordinary, no less than the ordinary, forms FIG. 177. Section of a tunicated bulb of the Onion. FIG. 178. Vertical section of the bulb of the Tulip, showing its stem (a) and buds (6, c). FIG. 179. Bulb of a Garlic, with a crop of young bulbs. FIG. 180. Vertical section of the corm of Crocus: a, new buds. FIG. 181. Vertical section of the corm of Colchicum, with the withered corm of the pre- ceding (a), and the forming one (c) for the ensuing year. 10 . 110 THE STEM. of the stem, grow and branch, or multiply, by the development of terminal and axillary buds. This is perfectly evident in the rhizoma and tuber, and is equally the case in the corm and bulb. The stem of the bulb is usually reduced to a mere plate (Fig. 178, a), which produces roots from its lower surface, and leaves or scales from the upper surface. Besides the terminal bud (c), which usually forms the flower-stem, lateral buds (4, 6) are produced in the axils of the leaves or scales. One or more of these may develop as flowering stems the next season, and thus the same bulb survive and blossom from year to year; or these axillary buds may themselves become bulbs, feeding on the parent bulb, which in this way is often con- sumed by its own offspring, as in the Garlic (Fig. 179); ; or, finally separating from the living parent, just as the bulblets of the Tiger Lily fall from the stem, they may form so many independent indi- viduals. So the corm of the Crocus (Fig. 182, 182") produces one or more new ones, which feed upon and exhaust it, and take its place; and the shrivelled remains of the old corm may be found underneath the new, the next season. The corm of Colchicum (Fig. 181) produces a new bud on one side at the base, and is consumed by it in the course of the season; the new one, after flowering by its terminal bud, is in turn consumed by its own offspring; and so on. In Fig. 181, we have at one view, a, the dead and shrivelled corm of the year preceding; 6, that of the present season (a vertical section); and e¢, 1s2@ the nascent bud for the growth of the ensuing season. Many of the forms which the stem assumes when above ground differ as much from the ordinary appearance as do any of these subterranean kinds, and, in fact, imitate their peculiarities; as, for example, the globular Melon-Cactus and Mamillaria, the colum- nar Cereus, and the jointed Opuntia or Prickly Pear. These are remarkably 194. Consolidated Forms of Vegetation, While ordinary plants are constructed on the plan of great expansion of surface, these are FIG. 182. Corm of Crocus, the few thin enveloping scales removed, showing the shrivelled vestige of the last year’s corm at the base, and buds developing into new ones on various parts of its surface. 182°. Vertical section of a similar corm, with a terminal and one lateral bud. \\ N CONSOLIDATED FORMS OF VEGETATION. 111 formed on the plan of the least possible amount of surface in pro- portion to their bulk. A green rind serves the purpose of foliage ; but the surface is as nothing compared with an ordinary leafy plant of the same amount of vegetable material. This consolidation is carried to the extreme in the Melon-Cactus, Mamillaria, and the like, of globular or corm-like shapes; their spherical figure being that which exposes the least possible part of the bulk to the air. Such plants are evidently adapted and designed for very dry regions ; and in such only are they naturally found. Similarly, bulbous and corm-bearing plants, and the like, are a form of vege- tation which in the growing season may in the foliage expand a large surface to the air and light, while during the period of rest the living vegetable is reduced to a globular or other form of the least surface; and this is protectéd by its outer coats of dead and dry scales, as well as by its subterranean situation ; — thus exhibit- ing another and very similar adaptation to a season of drought. And such plants mainly belong to countries (such as Southern Africa, and parts of the interior of Oregon and California) which have a long hot season, during which little or no rain falls, when, their stalks and foliage above and their roots beneath being early cut off by drought, the plants rest securely in their compact bulbs, filled with nourishment, and retain their moisture with great tenacity, until the rainy season returns. Then they shoot forth leaves and flowers with wonderful rapidity, and what was perhaps a desert of arid sand becomes green with foliage and gay with blos- soms, almost in a day. This will be more perfectly understood when the nature and the use of foliage shall have been more fully considered. Sect. IV. Tae Internat StRucTURE OF THE STEM IN GENERAL. 195. Having considered the various external forms and appear- ances which the stem exhibits, and its mode of increase in length, our attention may now be directed to its internal structure, and its mode of increase in diameter. 196. The stem embraces in its composition the various forms of elementary tissue that have already been described (Chap. I., Sect. IL, TLL); namely, ordinary cells, woody fibre, and vessels. At 112 THE STEM. first, indeed, it consists entirely of parenchyma (51), which pos- sesses much less strength and tenacity than woody tissue, and is therefore inadequate to the purposes for which the stem, in all the higher plants, is destined. The stem of a Moss or a Liverwort is, in fact, composed of ordinary cellular tissue alone; and is therefore weak and brittle, well enough adapted to plants of humble size, but not for those which attain any considerable height. Accord- ingly, as soon as the stems of Phanogamous plants begin to grow, and in proportion as the leaves are developed, woody mingled with vascular tissue is introduced, to afford the requisite toughness and strength, and to facilitate the rise of the ascending sap. If the wood accumulates only to moderate extent in proportion to the parenchyma, the stem remains herbaceous (174) ; if it predominates and continues to accumulate from year to year, the proper woody trunk of a shrub or tree is formed. 197. The cellular part of the stem grows with equal readiness, in whatever direction the forces of vegetation act. It grows verti- cally, to increase the stem in length, and horizontally, to increase its diameter. Into this the elongated cells that form the woody tissue and ducts are introduced vertically; they run lengthwise through the stem and branches. Hence, the latter has been called the longitudinal, vertical, or perpendicular system (56, 64); and the cellular part, the horizontal system of the stem. Or the stem may be compared to a web of cloth; the cellular system forming the woof, and the woody, the warp. 198. The diversities in the internal structure of the stem are principally owing to the different modes in which the woody or vertical system is imbedded in the cellular. These diversities are reducible to two general plans; upon one or the other of which the stems of all Flowering plants are constructed. Not only is the difference in structure quite striking, especially in all stems more than a year old, but it is manifested in the whole vegetation of the two kinds of plants, and indicates the division of Phanogamous plants into two great classes, recognizable by every eye; which, in their fully developed forms, may be represented, one by the Oak and other trees of our climate, the other by the Palm (Fig. 184). 199. The difference between the two, as to the structure of their stems, is briefly and simply this. In the first, the woody system is deposited in annual concentric layers between a central pith and an exterior bark ; so that a cross-section presents a series of rings or. ITS INTERNAL STRUCTURE. 113 circles of wood, surrounding each other and a distinct pith, and all surrounded by a separable bark. This is the plan, not only of the Oak, but of all the trees and shrubs of the colder climates. In the second, the woody system is not disposed in layers, but consists of separate bundles or threads of woody fibre, &e., running through the cellular system without apparent order; and presenting on the cross- section a view of the divided ends of these threads in the form of dots, diffused through the whole; but with no distinct pith, and no bark which is at any time readily separable from the wood. The appearance of such a stem, both on the longitudinal and the cross- section, is shown in Fig. 183; it may also be examined in the Cane or Rattan, the Bamboo, and in the annual stalk of Indian Corn or of Asparagus. That of ordinary wood of the first sort is too famil- jar to need a pictorial illustration. 200. Exogenous Structure. The stem, in the first case, increases in diameter by the annual formation of a new layer of wood, which i is deposited between the preceding layer and the bark; that is, the | wood increases by annual additions to its outside. Hence, such stems are said to be ExoGEnovus; and plants whose stems grow in this way are called Exogenous Puanrs, or briefly Exocrns; that is, as the term literally signifies, ouwtside-growers. “901. Endogenous Structure, In the second case, the new woody matter is intermingled with the old, or deposited towards the centre, which becomes more and more occupied with the woody threads as the stem grows older; and increase in diameter, so far as it depends on the formation of new wood, generally takes place by the gradual dis- tention of the whole. Accordingly, these stems are said to exhibit the EnpoGr- Nous structure or growth; and such plants are called ENDOGENOUS PLANTs, or ENDOGENS ; literally, inside- growers. 202. The two great classes of Phanogamous plants, indicated by this difference in the stem, are distinguishable even in the embryo state, by differences quite as marked as those which prevail in their whole port and aspect. The embryo of all plants that have en- dogenous stems bears only a single cotyledon; hence, Endogens are also called MonocotyLeponovus Piants (128). The embryo of FIG. 183. Section (longitudinal and transverse) of a Palm-stem. 10* 114 THE STEM. plants with exogenous stems bears a pair of cotyledons and unfolds a pair of seed-leaves in germination (Fig. 106, 125) ; hence, Exogens are likewise called DicoryLeponovs PLanTs. Srct. V. Ture Enpocenous or Monocotyieponous Stem. 203. Enpocens, or Jnside-growers, although they have many humble representatives in Northern climes, yet only attain their full characteristic devel- opment, and display their noble arbores- cent forms, under a tropical sun. Yet Palms — the type of the class —do ex- tend as far north in this country as the coast of North Caro- lina (the natural lim- it of the Palmetto, Fig. 184); while in Europe the Date and the Chamerops thrive in the warm- er parts of the European shore of the Mediterranean. The manner of their growth gives them a strik- ing appear- ance; their trunks being ~ unbranched, cylindrical columns, rising majestically to the height of from thirty to one hundred and fifty feet, and crowned at the summit with a simple cluster of peculiar foliage. Their internal structure is equal- ly different from that of ordinary wood. FIG. 184. The Chamerops Palmetto, in various stages, and the Yucca, Draconis. ENDOGENOUS STRUCTURE. 115 204. The stem of an Endogen, as already explained (199), offers no manifest distinction into bark, pith, and wood; and the latter is not composed of concentric rings or layers. But it consists of bundles of woody and vascular tissue, in the form of fibres or threads, which are imbedded, with little apparent regularity, in cellular tissue ; and the whole is enclosed in an integument, which does not strictly resemble the bark of an Exogenous plant, inasmuch as it does not increase by layers, and is never separable from the wood. The fibrous bundles which compose the wood, and which consist of a mass of woody fibres surrounding several vessels, are distributed throughout the cellular system of the stem, but most abundantly towards the circumference. Each bundle usually contains all the elements of the wood of the exogenous stem; namely, vessels, proper woody tissue, and bast-cells. The bundles often may be traced directly from the base of the leaves down through the stem, some of them to the roots in a young plant, while others, curving outwards, lose themselves in the cortical integument, or rind. As the stem increases, new bundles, springing from the bases of more recently developed leaves, are at first directed towards the centre of the stem, along which they descend for some distance, growing more slender in their course, and then, curving out- wards, mostly terminate in the rind. It is partly in consequence of the co- hesion of these obliquely descending fibres to the false bark, that the latter cannot, as in Exogens, be separated from the wood beneath. The manner in which the woody threads are consequently interwoven is shown in Fig. 185. The Palm-like Yuccas of the Southern States offer beautiful illustrations of the kind. 205. Endogenous stems, instead of having the oldest and hardest wood at the centre and the newest and softest at the circumference, as in ordinary trees, are softest towards the centre and most compact at the circumference. They increase in diameter with the increas- ing number of woody bundles (which multiply as new leaves are FIG. 185. Vertical and transverse ing of the fibres. of a young end stem, showing the curv- 116 THE STEM. produced), as long as the rind is capable of distention. In some instances, as in the arborescent Yuccas and the Dracwnas or Dragon- trees, the rind remains soft and capable of unlimited growth; but in the Palms, and in most woody Endogens, it soon indurates, and the stem consequently increases no further in diameter. The wood of the lower part of such stem is more compact than the upper, being more filled with woody bundles, and the rind is firmer, from the greater number of ligneous fibres which terminate in it, and from its proper induration. 206. Palms generally grow from the terminal bud alone, and perish if this bud be destroyed; they grow slowly, and bear their foliage in a cluster at the summit of the trunk, which consequently forms a simple cylindrical column. But in some instances two or more buds develop, and the stem branches, as in the Doum Palm of Upper Egypt, and in the Pandanus, or Screw-Pine (Fig. 140), which belongs to a family allied to Palms: in such cases the branches are cylindrical. But when lateral buds are freely devel- oped (as in the Asparagus), or the leaves are scattered along the stem or branches (as in the Bamboo, Maize, &c.), these taper up- wards, just as in Exogens. A particular comparison of the structure and growth of the Endogenous stem with the Exogenous cannot be instituted until the latter is explained in detail. Secr. VI. Tue Exocrnous or DicoryLeponovs STEM. 207. Since the Exogenous class is by far the larger in every part of the world, and embraces all the trees and shrubs with which we are familiar in the cooler climates, the structure of this kind of stem demands more detailed notice. To obtain a true and clear idea of its internal structure, we should commence at its origin and follow the course of development. 208. In the embryo, or at least at some period antecedent to germination, the rudimentary stem is entirely composed of paren- chyma. But as soon as it begins to grow, some of the cells begin to lengthen into tubes, to be marked with transverse bars or spiral lines, and thus give rise to ducts or vessels (67-60); these form a small and definite number of bundles or threads, say four equidistant ones in the first instance, as in the Sugar Maple: surrounding these, other slender cells of smaller culibre, and destitute of markings, EXOGENOUS STRUCTURE. 117 , soon appear, and form the earliest woody tissue. As the rudiments of the next internode and its leaves appear, two or four additional threads of vascular tissue appear in the stem below, in the paren- chyma between the earliest ones, and are equally surrounded with forming woody tissue. At an early stage, therefore, the developing stem is seen to be traversed by several bundles of woody tissue, with some vessels imbedded ; and these, as they increase and enlarge, run together so as to make up a woody zone (or, as seen in the cross- section, a ring), enclosing the central part of the parenchyma within it, and itself enclosed by the external parenchyma. ‘Thus a zone or layer of wood is formed, which is so situated in the original homo- geneous cellular system as to divide it into two parts; namely, a central portion, which forms the pith, and an exterior portion, which belongs to the bark. The whole is of course invested by the skin or epidermis, which covers the entire surface of the plant. The way in which the layer of wood thus originates is somewhat rudely illustrated by the annexed diagrams (Fig. 186-188). The several woody masses, or wedges, are separated from each other by lines or bands of the original cellular tissue, which pass from the pith to the bark, and which necessarily become narrower and more numerous as the woody bundles or wedges increase in size and number. These bands are the 209. Medullary Rays. These form the radiating lines that the cross-section of most exogenous wood so plainly exhibits, especially that of the Oak, Plane, &c. They consist of parenchyma, more FIG. 186. Plan of a cross-section of a forming seedling stem, showing the manner in which the young wood is imbedded in the cellular system. FIG. 187. The same ata later period, the woody bundles increased so as nearly to fill the circle. FIG. 188. The same at the close of the season, where the wood has formed a complete circle, separating the pith from the bark, except that they are still connected by narrow por- tions of the cellular system (the medullary rays) which radiate from the pith to the bark. 118 THE STEM. or less flattened by the pressure of the woody wedges, and they serve to keep up the communication between the pith and the bark. 210. The First Year's Growth of an exogenous stem accordingly con- sists of three principal parts, viz.: Ist, a central cellular portion, or Pith ; 2d, a zone of Wood; and 3d, an exterior cellular portion, or Bark. These several parts are displayed in Fig. 189-191, as they occur in a woody stem a year old. 211. The Pith (Aée- dulla) consists en- tirely of soft cellular tissue, or parenchy- ma* (51), which is at first gorged with sap. Many stems ‘expand so rapidly in diameter during their early growth, that N roa Co <> they become hollow, the pith being torn away by the disten- tion, and its remains forming a mere lin- ing to the cavity. ¢ In the Walnut and me the Poke (Phytolac- ‘= * In rare instances a few threads of woody tissue and vessels are found dis- persed through the pith, presenting a somewhat remarkable anomaly. This occurs in Aralia racemosa, and more strikingly in Oxybaphus, Mirabilis or Four-o’clock, and other Nyctaginaces. FIG. 189. Longitudinal and transverse section of a stem of the Soft Maple (Acer dasycar- pum), at the close of the first year’s growth ; of the natural size. FIG. 190. Portion of the same, magnified, showing the cellular pith, surrounded by the wood, and that enclosed by the bark FIG. 191. More magnified slice of the same, reaching from the bark to the pith: a, part of the pith ; 6, vessels of the medullary sheath ; ¢, the wood ; dd, dotted ducts in the wood 3 ee, annular ducts ; /, the liber, or inner fibrous bark ; g, the cellular envelope, or green bark ; A, the corky envelope ; 2, the skin or epidermis ; %, one of the medullary rays, seen on the trans- verse section. \ EXOGENOUS STRUCTURE. 119 ea) it is. early separated into a series of horizontal plates. As the stem grows older the pith becomes dry and light, its cells filled with air only; and then it is of no further use to the plant. 212. The Wood consists of proper woody tissue (53), among which the vascular is more or less copiously mingled, principally in the form of dotted ducts (Fig. 191, d), or occasionally some annular ducts (e), &c. The dotted ducts are of so considerable calibre, that they are conspicuous to the naked eye in many ordinary kinds of wood, especially where: they are accumulated in the inner portion of each layer, as in the Chestnut and Oak. Inthe Maple, Plane, &c., they are rather equably scattered through the annual layer, and are of a size so small, that they are not distinguishable by the naked eye. — Next the pith, i. e. in the very earliest formed part of the wood, some spiral ducts are uniformly found (Fig. 191, 6), and this is the only part of the exogenous stem in which these ordinarily occur. They may be detected by breaking a woody twig in two, after divid- ing the bark and most of the wood by a circular incision, and then pulling the ends gently asunder, when their spirally coiled fibres are readily drawn out.as gossamer threads. As these spiral ducts form \ acircle immediately surrounding the pith, they form what has been ‘termed the Mepurtary Sweats. This is no special organ, and hardly requires a special name, since it merely represents the earli- est-formed vascular tissue of the stem. 213. The vertical section in Fig, 191 divides one of the woody wedges; and therefore the medullary rays do not appear. But in ae fas |S) aS | joes [es] SL), leig [Omelet en nae TE oo LAE ILILILA eewes [= Pe Io ANTE IMM ? 192 b 193 FIG. 192. Vertical section through the wood of a branch of the Maple, a year old; so as to show one of the medullary rays, passing transversely from the pith (7) to the bark (b): mag- nified. But a section can seldom be made so as to show one unbroken plate stretching across the wood, as in this instance. FIG. 198. A vertical section across the ends of the medullary rays ; magnified. 120 THE STEM. the much more magnified Fig. 192, the section is made so as to show the surface of one of these plates, and one of the MepuLLARY Rays passing horizontally across it, connecting the pith (p) with the bark (4). These medullary rays form the stlver-grain, (as it is termed,) which is so conspicuous in the Maple, Oak, &c., and which gives the glimmering lustre to many kinds of wood when cut \ in this direction. Buta section made as a tangent to the circum- ference, and therefore perpendicular to the medullary rays, brings their ends to view, as in Fig. 193; much as they appear when seen on the surface of a piece of wood from which the bark is stripped. They are here seen to be composed of parenchyma, and to represent the horizontal system of the wood, or the woof, into which the ver- tical woody fibre, &e., or warp, is interwoven. The inspection of a piece of oak or maple wood at once shows the pertinency of this illustration. 214. The Bark, ina stem of a year old, must next be considered. At first it consists of simple parenchyma, undistinguishable from that of the pith, except that it assumes a green color when exposed to the light, from the production of chlorophyll (92) in its cells. But during the formation of the wood of the season, an analogous forma- tion occurs in the bark. The inner portion, next the wood, has ‘woody tissue formed in it, and becomes 215. The Liber, or Jnner Bark (Fig. 191, f). The fibre-like cells, which give to the inner bark of those plants that largely contain them its principal strength and toughness, are of the kind already described under the name of bast-cells or bast-tissue (55). They are remarkable for their length, flexibility, and the great thickness of their walls. They form in bundles, or in bands separated by exten- sions of the medullary rays, one accordingly corresponding to each of the woody plates or wedges; or sometimes (as in Negundo, Fig. 194, 195) they are confluent into an unbroken circle round the whole circumference. Complete and well-developed liber, like that of the Basswood, consists of three elements, viz.: 1. bast-cells or fibres ; 2. large and more or less elongated cells, with thinner walls variously marked with transparent spots, appearing like perforations, and usually traversed by an exceedingly minute net-work; and 3. cells of parenchyma. The liber has received the technical name of EnpoPeLeum (literally inner bark). In most woody stems the exterior part of the bark, in which no woody tissue occurs, is early distinguishable into two parts, an inner and an outer. The former is EXOGENOUS STRUCTURE. 121 216. The Cellular Envelope, or Green Layer (Fig. 191, 9), also called, ‘from its intermediate position, the Mrsorntaum. This is com- posed of loose parenchyma, with thin walls, much like the green pulp of leaves, and containing an equal abundance of chlorophyll. It is the only part of the bark that retains a green color. In woody stems this is soon covered with 217. The Corky Envelope, or Evrpntaum (Fig. 191, 4), which gives to the twigs of trees and shrubs the hue peculiar to each spe- ‘cies, generally some shade of ash-color or brown, or occasionally of much more vivid tints. It is this tissue, which, taking an unusual development, forms the cork of the Cork-Oak, and those corky ex- pansions of the bark which are so conspicuous on the branches of Ww \ ie FIG. 194. Portion of a transverse section, and 195, a corresponding vertical section, magni- fied, reaching from the pith, p, to the epidermis, e, of a stem of Negundo, a year old: B, the bark ; W, the wood; and C, the cambium-layer, as found in February. The references are in the text above ; except mr, portion of a medullary ray, seen on the vertical section, where it runs into the pith; dd, dotted ducts: cl, the inner part of the cambium-layer, which begins the new layer of wood. In this tree, we find a thick layer of parenchyma (/) inside of the bast- tissue, and therefore belonging to the liber. No bast-tissue is formed in it the second year. 11 122 THE STEM. the Sweet Gum (Liquidambar), and on some of our Elms (Ulmus alata and racemosa). It also forms the paper-like, exfoliating layers of Bireh-bark. It is composed of laterally flattened parenchymatous cells, much like those of the Epmeruis (69, Fig. 191, 7), which directly overlies it, and forms the skin or surface of the stem. 218. The elements of an exogenous stem of a year old, especially in a woody plant, accordingly are these, proceeding from the centre towards the circumference : — I. In the Wood : . The Pith, belonging to the cellular system (Fig. 194, 195, p). . The Medullary Sheath, ms, ) which belong to the woody or . The Layer of Wood, W, w, longitudinal system. . The Medullary Rays, mr, a part of the cellular system. II. In the Bark: 5. The Liber, 1; its bast-tissue, 6, belongs to the woody system. 6. The Outer Bark, belonging wholly to the cellular system, and composed of two parts, viz.: Ist, the Green or Cellular En- velope, ge, and 2d, the Corky Envelope, ce. 7. The Epidermis, e, or skin, which invests the whole. 219. An herbaceous stem does not essentially differ from a woody one of this age, except that the wood forms a less compact or thinner zone; and the whole perishes, at least down to the ground, at the close of the season. But a woody stem makes provision for contin- uing its growth the second year. As the layer of wood continues to increase in thickness throughout the season, by the multiplication of cells on its outer surface, between it and the bark, and when growth ceases this process of cell-multiplication is merely suspended, so there is always a zone of delicate young cells interposed between the wood and the bark. This is called the 220. Cambium-Layer, (Fig. 194,195, C). It is charged with or- we CO DD He ‘ ganizable matter (protoplasm, dextrine, &c.) in the form of a mu- cilage, which is particularly abundant in the spring when growth _; recommences. This mucilaginous matter was named Cambium by ' the older botanists; who supposed —as is still generally thought — that the bark, then so readily separable, really separated from the wood in spring, that a quantity of rich mucilaginous sap was poured out between them, and that this sap, or cambium, was organized into a tissue, the inner part becoming new wood, the outer, new bark. But delicate slices will show that there is then no more inter- ruption of the wood and inner bark than at any other season; that EXOGENOUS STRUCTURE. 123 the two are always organically connected by an extremely delicate tissue of young and vitally active cells, just in the state in which they multiply by division (83). The bark, indeed, is very readily detached from the wood in spring, because the cambium-layer is then gorged with sap; but the separation is effected by the rending of a delicate forming tissue. And if some of this apparant mucilage be scraped off from the surface of the wood, and examined under a good microscope, it will be seen to be a thin stratum of young wood-cells, with the ends of medullary rays here and there. interspersed, and appearing much as in Fig. 193, only the young wood-cells are mostly shorter. The inner portion of the éambium-layer is therefore nas- cent wood, and the outer is nascent bark. And it is by the growth of the cambium-layer, renewed year after year, that the 221. Annual Increase of the Wood of Exegenous plants is effected: As the cells of this layer multiply, the greater number lengthen ver- tically into prosenchyma or woody tissue; while some are trans- formed into ducts, and others, remaining as parenchyma, continue the medullary rays or commence new ones. In this way a second layer of wood is formed the second season, over the whole surface of the former layer and between it and the bark, and continuous with the woody layer of the new roots below and of the leafy shoots of the season above. Lach succeeding year another layer is added to the wood in the same manner, coincident with the growth in length by the development of the buds. A cross-section of an exogenous stem, therefore, exhibits the wood disposed in concentric rings between the bark and the pith; the oldest lying next the latter, and the ; youngest occupying the circumference. Each layer being the pro- duct of a single year’s growth, the age of an exogenous tree may, in general, be correctly ascertained by counting the rings in a cross- section of the trunk.* * The annual layers are most distinct in trees of temperate climates like ours, where there is a prolonged period of total repose, from the winter’s cold, fol- lowed by a vigorous resumption of vegetation in spring. In tropical trees they are rarcly so well defined ; but even in these there is generally a more or less marked annual suspension of vegetation, occurring, however, in the dry and hotter, rather than in the cooler season. There are numerous cases, moreover, in which the wood forms a uniform stratum, whatever be the age of the trunk, as in the arborescent species of Cactus ; or where the layers are few and by no means corresponding with the age of the trunk, as in the Cycas. In many woody climbing or twining stems, such as tuose of Clematis, Aristo- 124 THE STEM. 222. The Limitation of the Annual Layers results from two or more causes, separate or combined. In oak and chestnut wood, and the like, the layers are strongly defined by reason of the accumulation of the large dotted ducts, here of extreme size and in great abundance, in the inner portion of each layer, where their open mouths on the cross-section are conspicuous to the naked eye, making a strong con- trast between the inner porous, and the exterior solid part of the successive layers. In Maple and Beech wood, however, the ducts are smaller, and are dispersed throughout the whole breadth of the layer; and in coniferous wood, viz. that of Pine, Cypress, &c., there are no ducts at all, but only a uniform woody tissue of a peculiar sort (46, 54). Here the demarcation between two layers is owing to the greater fineness of the wood-cells formed at the close of the season, viz. those at the outer border of the layer, while the next layer begins, in its vigorous vernal growth, with much larger cells, thus marking an abrupt transition from one layer to the next. Be- sides being finer, the last wood-cells of the season are often flattened laterally, more or less. F 223. Each layer of wood, once formed, remains unchanged in posi- tion and dimensions. But in trunks of considerable age, the older layers generally undergo more or less change in color and density, distinguishing the wood into two parts, viz. ___ 224. Sap-wood and Ieart-wood. In the germinating plantlet and in ‘the developing bud, the sap ascends through the whole tissue, of whatever sort; at first through the parenchyma, for there is then no other tissue ; and the transmission is continued through it, especially through its central portion, or the pith, in the growing apex of the stem throughout. But in the older parts below, the pith, soon drained of sap, becomes filled with air in its place, and thenceforth it bears no part in the plant’s nourishment. As soon as wood-cells and ducts are formed, they take an active part in the conveyance of sap ; lochia Sipho, and Menispermum Canadense, the annual layers are rather obscure- ly marked, while the medullary rays are unusually broad ; and the wood therefore forms a scrics of separable wedges disposed in a circle around the pith. In the stem of one of our Trumpet-creepers (the Bignonia capreolata) the annual rings, after the first four or five, are interrupted in four places, and here as many broad plates of cellular tissue, belonging properly to the bark, are interposed, passing at right angles to each other from the circumference towards the centre, so that the transverse section of the wood nearly resembles a Maltese cross. But these are all exceptional cases, which scarcely require notice in a general view. SAP-WOOD AND HEART-WOOD. 125 for which their tubular and capillary character is especially adapted. But the ducts in older parts, except when gorged with sap, contain air alone ; and in woody trunks the sap continues to rise year after year, to the places where growth is going on, mainly through the proper woody tissue of the wood. In this transmission the new layers are most active, and these are in direct communication with the new roots on the one hand and with the buds or shoots and leaves of the season on the other. So, by the formation of new annual layers out- side of them, the older ones are each year removed a step farther from the region of growth; or rather the growing stratum, which connects the fresh rootlets that imbibe with the foliage that elabo- rates the sap, is each year removed farther from them. The latter, therefore, after a few years, cease to convey sap, as they have long 199 FIG. 196. Magnified cross-section of a portion of woody tissue of White Oak, a year old. 197. A longitudinal as well as cross section of the same, a little higher magnified. a, a, Por+ tions of one of the smaller medullary rays. FIG. 198. Magnified cross-section of woody tissue from the same stem, taken from a layer of heart-wood, 24 years old: b, ducts : a, portion of one of the minuter medullary rays, 199. Combined cross and longitudinal section of the same: a, tissue of a medullary ray. 11* 126 THE STEM. before ceased to take part in any vital operations. The cells of the older layers, also, commonly have thicker walls and smaller calibre than those of the newer, —as here shown in Fig. 198, 199, compared with Fig, 196, 197, — owing to the greater amount of thickening or- ganic materials (43) mingled with encrusting mineral matters intro- duced with the water imbibed by the roots (93) which have been de- posited upon them from within. This older, more solidified, and harder wood, which occupies the centre of the trunk, and is the part princi- pally valuable for timber, &c., is called Heart-woop, or DuRAMEN: while the newer layers of softer, more open, and bibulous wood, more or less charged with sap, receive the name of Sar-woop, or ALBUR- num. The latter name was given by the earlier physiologists in allu- sion to its white or pale color. In all trees which have the distinction between the sap-wood and heart-wood well marked, the latter acquires a deeper color, and that peculiar to the species, such as the dark brown of the Black Walnut, the blacker color of the Ebony, the purplish-red of Red Cedar, and the bright yellow of the Barberry. These colors are owing to special vegetable products mixed with the incrusting matters ; but sometimes the hue appers to be rather an alteration of the lignine with age. In the Red Cedar, the deep color belongs chiefly to the medullary rays. In many of the softer woods, there is little thickening of the cell-walls, and little change in color of the heart-wood, except from incipient decay, as in the White Pine, Pop- , lar, Tulip-tree, &c. The heart-wood is no longer in any sense a living part; it may perish, as it frequently does, without affecting the life or health of the tree. 225. The Bark is much more various in structure and growth than the wood : it is also subject to grave alterations with advancing age, on account of its external position, viz. to distention from the con- stantly increasing diameter of the stem within, and to abrasion and decay from the influence of the elements without. It is never entire, therefore, on the trunks of large trees; but the dead exterior parts, no longer able to enlarge with the enlarging wood, are gradually fissured and torn, and crack off in layers, or fall away by slow decay. So that the bark of old trunks bears but a small proportion in thick- ness to the wood, even when it makes an equal amount of annual growth. 226. The three parts of the bark (214-217), for the most part readily distinguishable in the bark of young shoots, grow indepen- dently, each by the addition of new cells to its inner face, so long as THE BARK. 127 6 it grows at all. The green layer does not increase at all after the first year ; the opaque corky layer soon excludes it from the light ; and it gradually perishes, never to be renewed. The corky layer commonly increases for a few years only, by the formation of new tabular cells: occasionally it takes a remarkable development, form- ing the substance called Cork, as in the Cork Oak. A similar growth occurs on the bark of several : " on Ss eS SS species of Elm, of our Liquid- | ——3 => SSS ambar or Sweet-Gum, &c., pro- , qpange Sn Gnar Geee ee endiy GER es aes ducing thick corky plates on the branches. In the White and Pa- per Birch, thin layers, of a very durable nature, are formed for a great number of years; each layer of tabular and firmly cohe- rent cells (Fig. 200, a) alternates a _——— oo =eaaeeaee GEES TH Rats oe a CEES eS Se Ses Se i SS TCS CB ED BEB Opes BASSO aaG Mawes | ————— MQVQasSMaesaawp Dee with a thinner stratum of delicate, ea somewhat cubical and Jess compact cells (6), which break up into a fine powder when disturbed, and allow the thin, paper-like plates to exfoliate. 227. The liber, or inner bark (215), continues to grow through- out the life of the tree, by an annual addition from the cambium- layer applied to its inner surface. Sometimes the growth is plainly distinguishable into layers, corresponding with or more numerous than the annual layers of the wood: often, there is scarcely any trace of such layers to be discerned. In composition and appearance the liber varies greatly in different plants,* especially in trees and shrubs. That of Bass-wood or Linden, and of other plants with a similar fibrous bark, may be taken as best representing the liber. Here it consists of strata of very thick-walled cells alternating with thin-walled cells. The thick-walled cells are bast-cells (55, Fig. 49, 53), are much elongated vertically, and form the fibrous portion of * The best account of the liber that has yet been given is that by Mohl, in the Botanische Zeitung, Vol. 13, p. 873 (1855), of which a French translation is published in the Annales des Sciences Naturelles, ser. 4, Vol. 5, p. 141, et seq. (1856). FIG. 200. Transverse section of a minute portion of White Birch bark, the corky layer highly magnified: a, the firm, tabular cells, 6, delicate thin-walled cells which separate the papery plates. (After Link.) 128 THE STEM. de bark. The thin-walled cells are those of ordinary parenchyma, mingled, at the inner part of each stratum, with larger and longer ones, marked (on some sides at least) with the thin and reticulated spots or punctuations already described (215). These last may be ‘termed the proper cells of the liber, as they are peculiar to this part “of the bark, are seldom if ever absent, they contain an abundance of mucilage and proteine, and in all probability they take the principal part in the descending circulation of the plant, if it may so be called, _L e. in conveying downwards and distributing the rich sap which has been elaborated in the foliage. It is evident that the bast-cells, which in Linden (Fig. 53) are seen to be almost solid, are not adapted to this purpose. 228. That bast-cells are not an essential part, is further evident -from the fact, that they are altogether wanting in the bark of some * plants, and are not produced after the first year in many others. The latter is the case in Negundo, where abundant bast-cells, like those of Bass-wood, compose the exterior portion of the first year’s liber (Fig. 194, 195, 0), but none whatever is formed in the subsequent layers. In Beeches and Birches, also, a few bast-cells are produced the first year, but none afterwards. In Maples a few are formed in — succeeding years. In the Pear bast-cells are annually formed, but in very small quantity, compared with the parenchymatous part of the liber. In Pines, at least in White Pines, the bark is nearly as homogeneous as the wood, the whole liber, except what answers to the medullary rays, consisting of one kind of cells, resembling those of bast or of wood in form, but agree- ing with the proper liber-cells in their structure and markings. Although the liber of Birch produces no bast- cells after the first year, it abounds in short cells equally solidified by in- ternal deposition, and of a gritty tex- ture, which might be mistaken for bast-cells on the cross-section (Fig. 201). A longitudinal section discloses the difference. 229. The bark on old stems is constantly decaying or falling away from the surface, without any injury to the tree; just as the heart- wood may equally decay within without harm, except by mechani- FIG. 201. Cross-section of a cluster of solidified and indurated cells from the liber of the White Birch. (After Link.) THE LIVING PARTS OF A TREE. 129 cally impairing the strength of the ‘trunk. Great differences are observable as to the time and manner in which the older bark of different shrubs and trees is thrown off, according to the struc- ture in each species. ie trees and shrubs have their trunks in- vested with the liber of, many years’ growth, although only the in- nermost layers are alive; in others it scales off much earlier. On the stems of the ie Honeysuckle, of the Nine-Bark (Spirea opulifolia), and of ae ee (except of our Muscadine Grape), the liber lives only one season, and is detached the following year, hanging loose in papery, layers in the former species, and in fibrous shreds in the latter. 230. While the newe PASTE Whod abound in crude sap, which they convey to the leaves (224), those of the inner bark abound in elaborated sap (79, 227), which they receive from the leaves and convey to the cambium-layer or zone of growth. The, proper juices and peculiar products of plants (88) are accordingly, found in the foliage and the bark, especially in the latter. In the bark, therefore, (either of the stem or of the root,) medicinal and other principles are usually to be sought, rather than in the wood. Nevertheless, as the wood is kept in connection with the bark by the medullary rays, many products which probably originate in the former are deposited in the wood. 231. The Living Parts of a Tree or Shrub, of the Exogenous kind, are obviously only these :— 1st. The summit of the stem and branches, with- the buds which continue them upwards and annually develop the foliage. 2d. The fresh tips of the roots and rootlets annually developed at the opposite extremity. 3d. The newest strata of wood and bark, and especially the interposed cambium-layer, which, annu- ally renewed, maintain a living communication between the rootlets on the one hand and the buds and foliage on the other, however dis- tant they at length may be. These are all that is concerned in the life and growth of the tree; and these are annually renewed. The branches of each year’s growth are, therefore, kept in fresh commu- nication, by means of the newer layers of wood, with the “fresh rootlets, which are aléne active in absorbing the crude food of the plant from the soil. The fluid they absorb is thus conveyed directly to the branches of the season, which alone develop leaves to digest it. And the sap they receive, having been elaborated and converted into organic nourishing matter, is partly expended in the upward growth of new branches, and partly in the formation of a new layer 130 THE STEM. of wood, reaching from the highest leaves to the remotest rootlets.* As the exogenous tree, therefore, annually renews its buds and * The layers of wood and bark, by which the exogenous stem annually in- creases in diameter, are formed by the multiplication of the cells of the cambium- laycr throughout its whole extent. That the organic material to supply this growth in ordinary vegetation descends in the bark, for the most part, and that the order of growth in the formation of wood is from above downwards, and also the general dependence of this growth upon the action of the foliage, may be inferred from a variety of facts and considerations. The connection of the wood with the leaves is shown :—(1.) By tracing the threads of soft woody Endogens, such as Yucca, directly from the base of the leaf into the stem, and thence downward to their termination, towards which they become attenuated, lose their vessels, and are finally reduced to slender shreds of woody tissue. (2.) The amount of wood formed in a stem or branch, other things being equal, is in a relation to the number and size of the leaves it bears; its amount in any portion of the branch is in direct proportion to the number of leaves above that portion. Thus, when the leaves are distributed along a branch, it tapers to the summit, as in a common Reed or a stalk of Indian Corn ; when they grow in a cluster at the apex, it remains cylindrical, as in a Palm (Fig. 184). Consequently the increase of the trunk in diameter directly corresponds with the number and vigor of the branches. The greater the development of vigorous branches on a particular side of a trec, the more wood is formed, and the greater the thickness of the annual layers on that side of the trunk. (3.) In u seedling, the wood appears in proportion as the leaves are developed., (4.) If a young branch be cut off just below a node (156), so as to leave an internode without leaves or bud, little or no increase in diameter will ordinarily take place down to the first leaf below. But if a bud be inserted into this naked internode, as the bud de- velops, increase in diameter, with the formation of new wood, recommences. That the formation proceeds from above downwards, or that the elaborated sap which furnishes the material for the growth is diffused from above downwards, appears from the effect of a ligature around exogenous stems, or of removing a ring of bark. It is a familiar fact, that, when a ligature is closely bound around a growing exogenous stem, the part above the ligature swells, and that below docs not. Every one may have observed the distortions that twining stems thus accidentally produce upon woody exogenous trunks, causing an enlargement on the upper side of the obstruction. When the stem is girdled, by removing a ring of bark so as completely to expose the surface of the wood, the part above the ring enlarges in the same manner ; that below does not, until the incision is healed. The wood of the roots is manifestly formed in a descending direction. But this is continuous with that of the stem; and its first layer, the extension of the wood of the radicle into the primary root, agrees in composition with the wood of the succeeding layers in the stem, having no spiral vessels, but only ducts. Still, whatever analogy there may be between the growth of the wood in the stem and of roots, there is no real basis for the ingenious conception of Thouars and of Gaudichaud, that wood is the roots of buds or leaves, or that it is absolutely dependent upon them for its formation. COMPOSITE NATURE OF A PLANT. 131 leaves, its wood, bark, and roots, — everything, indeed, that is con- cerned in its life and growth,— there seems to be no reason, no necessary cause inherent in the tree itself, why it may not live in- definitely. Accordingly, some trees are known to have lived for twelve hundred years or more; and others now survive which are probably above two thousand years old, and perhaps much older.* This longevity ceases to be at all surprising when we consider, that, although the tree or herb is in a certain sense an individual, yet it is not an individual in the sense that a man or any ordinary animal is. Viewed philosophically, 232. The Plant is a Composite Being, or community, lasting, in the case of a tree especially, through an indefinite and often immense number of generations. These are successively produced, enjoy a term of existence, and perish in their turn. Life passes onward continually from the older to the newer parts, and death follows, with cqual step, at a narrow interval. No portion of the tree is now living that was alive a few years ago; the leaves die annually and are cast off, while the internodes or joints of stem that bore them, as to their wood at least, buried deep in the trunk, under the wood of succeeding generations, are converted into lifeless heart-wood, or perchance decayed, while the bark that belonged to them is thrown off from the surface. It is the aggregate, the blended mass alone, that long survives. Plants of single cells, and of a definite form, alone exhibit complete individuality ; and their existence is ex- tremely brief. The more complex vegetable of a higher grade is not to be compared with the animal of the highest organization, where the offspring always separates from the parent, and the indi- vidual is simple and indivisible. But it is truly similar to the branch- ing or arborescent coral, or to other compound animals of the lowest grade, where successive generations, though capable of living inde- pendently and sometimes separating spontaneously, yet are usually developed in connection, blended in a general body, and nourished more or less in common. ‘Thus the coral structure is built up by the combined labors of a vast number of individuals, — by the suc- * The subject of the longevity of trees has been ably discussed by De Can- dolle, in the Bibliothéque Universelle of Geneva, for May, 1831, and in the second volume of his Physiologie Vegetale: also, more recently, by Professor Alphonse De Candolle. In this country, an article on the subject has appeared in the North American Review, for July, 1844. 132 THE STEM. cessive labors of a great number of generations. The surface or the recent shoots alone are alive; and here life is superficial, all under- neath consisting of the dead remains of former generations. The arborescent species are not only lifeless along the central axis, but are dead throughout towards the bottom: as, in a genealogical tree, only the later ramifications are among the living. It is the same with the vegetable, except that, as it ordinarily imbibes its nourish- ment mainly from the soil through its roots, it makes a downward growth also, and, by constant renewal of fresh tissues, maintains the communication between the two growing extremities, the buds and the rootlets, 233. Individuality being imperfectly realized in the vegetable kingdom, the question as to what in the Phenogamous plant best answers to the animal individual is speculative, rather than practical, and may be more appropriately noticed in another place. (Part IT. Chap. I.) 234. Comparison of Endogenous with Exogenous Structure. The woody bundles of an exogenous stem (Fig. 186-188) continue to grow on the outer side as long as the plant lives. In woody trunks they at once become wedges with the point next the pith, and growth pro- ceeds indefinitely by the stratum of perpetually renewed tissue on the outer face between the wood and the bark. Each wedge is separated from its neighbor on both sides by an interposed medul- lary ray, and is composed of wood on the inner side, liber on the outer, and cambium or forming tissue between. Now each thread or bundle of endogenous wood (204) is composed of similar or anal- ogous parts, sometimes irregularly intermixed, but more commonly similarly disposed. That is, the section of one of these threads ex- hibits woody tissue and one or two spiral vessels on its inner border, answering to the proper wood, and very thick-walled elongated cells on its outer border, of the same nature as the bast-cells of Exogens; and between the two is a stratum of cells of parenchyma mixed with elongated and punctuated cells answering to the proper cells of the inner part of the liber. The portion of each endogenous thread, therefore, which looks towards the centre of the trunk, answers to the wood, and its outer portion to the liber or inner bark, of the ex- ogenous stem; and the parenchyma through which the threads are interspersed answers to the medullary rays and pith together. The main difference between the endogenous woody threads and the ex- ogenous woody wedges is, that there is no cambium-layer in the THE LEAVES. 133 former between the liber and the wood, and therefore no provision for increase in diameter. The bundles are therefore strictly limited, while those of Exogens are unlimited in growth. In Exogens the woody bundles or wedges, symmetrically arranged in a circle, be- come confluent into a zone in all woody and most herbaceous stems, which continues to increase in thickness. In Endogens the woody bundles are unchanged in size after their formation, but new and distinct ones are formed in the growing stem with each leaf it de- velops, and interspersed more or less irregularly among the older bundles. CHAPTER V. OF THE LEAVES. Sect. I. Tarr ARRANGEMENT. (PHYLLOTAXIS, ETC.) 235. Tux situation of leaves, as well as their general office in the vegetable economy, and several of their special adaptations, has already been stated. Leaves invariably arise from the nodes (156), just below the point where buds appear. So that wherever a bud or branch is found, a leaf exists, or has existed, either in a perfect or rudimentary state, just beneath it; and buds (and therefore branch- es), on the other hand, are or may be developed in the axils of all leaves, and do not normally exist in any other situation. The point of attachment of a leaf (or other organ) with the stem is termed its insertion. The subject of the arrangement of leaves on the stem has received the name of 236. Phyllotaxis (from two Greek words, signifying leaf-arrange- ment). 237, As to their general position, leaves are either alternate, oppo- site, or verticillate. They are said to be alternate (127, and Fig. 121, 157, 204) when there is only one to each node, in which case the successivé leaves are thrown alternately to different sides of the stem. They are said to be opposite when each node bears a pair of leaves, in which case the two leaves always diverge from each other as widely as possible, that is, they stand on opposite 12 134 THE LEAVES. sides of the stem and point in opposite directions (127, Fig. 107, 210, &.). They are verticillate, or whorled, when there are three or more leaves in a cirele (verticil or whorl) upon each node ; in which case the several leaves of the circle diverge from each other as much as possible, or are equably distributed around the whole circumfer- ence of the axis (Fig. 134, 211). The first of the three is the simplest as well as the commonest method, occurring as it does in almost every Monocotyledonous plant (where it is plainly the normal mode, 128), and in the larger number of Dicotyledonous plants likewise, after the first or second nodes (Fig. 111*, 121). It should therefore be first examined. 238. Alternate Leaves, This general term s for the case where leayes are placed one after » another, obviously comprises a variety of modes as to the particular position of succes- 4 sive leaves. There is, first, the case to which the name is most applicable, viz. where the leaves are alternately disposed on exactly op- 2 posite sides of the stem (as in Fig. 157) ; the second leaf being on the side farthest from the first, while the third is equally distant from } the second, and is consequently placed directly All aooomeneeny Over the first, the fourth stands over the second, and so on throughout. Such leaves are accordingly distichous or two-ranked.* They form two vertical rows: on one side are the Ist, 3d, 5th, 7th, &c.; on the op- posite side are the 2d, 4th, 6th, 8th, and so on. This mode occurs in all Grasses, in many other Monocotyledonous plants, and among the Dicotyledonous in the Linden. A second mode is 239. The tristichous or three-ranked ar- rangement, which is seen in Sedges (Fig. * In the course of the summer the leaves of Baptisia perfoliata, which are really five-ranked, often appear to be monostichous, or one-ranked; but this is owing to a torsion of the axis. FIG. 202. Piece of astalk, with the sheathing bases of the leaves, of a Sedge-Grass (Carex Crus-corvi), showing the three-ranked arrangement. 203. Diagram of the cross-section of the same, showing two cycles of leaves. * THEIR ARRANGEMENT. 135 202) and some other Monocotyledonous plants. Taking any leaf we please to begin with, and numbering it 1, we pass round one third of the circumference of the stem as we ascend to leaf No. 2; another third of the circumference brings us to No. 3; another brings us round to a point exactly over No 1, and here No. 4 is placed. No.5 is in like manner over No. 2, and so on. They stand, therefore, in three vertical rows, one of which contains the numbers 1, 4, 7, 10; another, 2, 5, 8,11; the third, 3, 6, 9,12, and soon. If we draw a line from the insertion of one leaf to that of the next, and so on to the third, fourth, and the rest in succession, it will be perceived that it winds around the stem spirally as it ascends. In the first or dis- tichous mode, the second leaf is separated from the preceding by half the circumference of the stem; and, having completed one turn round the stem, the third begins a second turn. In the tristichouss each leaf is separated from the preceding and succeeding by one third of the circumference, there are three leaves in one turn, or cycle, and the fourth commences a second cycle, which goes on in the same way. That is, the angular divergence, or are interposed between the insertion of two successive leaves, in the first is 4, in the second 4, of the circle. These fractions severally represent, not only the angle of divergence, but the whole plan of these two modes ; the numerator denoting the number of times the spiral line winds round the stem before it brings a leaf directly over the one it began with ; while the denominator expresses the number of leaves that are laid down in this course, or which form each cycle. The two- ranked mode (3) is evidently the simplest possible case. The three- ranked (4) is the next, and the one in which the spiral character of the arrangement begins to be evident. To this succeeds 240. The pentastichous, quincuncial, or five-ranked arrangement. (Fig. 204, 205). This is much the most common case in alternate- leaved Dicotyledonous plants. The Apple, Cherry, and Poplar afford ready examples of it. Here there are five leaves in each cycle, since we must pass on to the sixth before we find one placed vertically over the first. To reach this, the ascending spiral line has made two revolutions round the stem, and on it the five leaves are equably distributed, at intervals of 2 of the circumference. The fraction 2 accordingly expresses the angular divergence of the suc- cessive leaves; the numerator indicates the number of turns made in completing the cycle, and the denominator gives the number of leaves in the cycle, or the number of vertical ranks of leaves on such 186 THE LEAVES. astem. If we shorten the axis, as it was in the bud, or make a horizontal plan, we have 205 the parts disposed as in the diagram, Fig. 206, the low- er leaves being of course the exterior. 241. The etght-ranked arrangement, the next in order, is likewise not un- common. It is found in the Holly, the Callistemon of our conservatories, the Aconite, the tuft of leaves at the base of the common Plantain, &c. In this case the ninth leaf is placed over the first, the tenth over the second, and so on; and the spiral line makes three turns in laying down the cycle of eight leaves, each separated from the preceding by an are, or an- gular divergence, of 3 of the circumference. 242. All these modes, or nearly all of them, were pointed out by Bonnet as long ago as the middle of the last century ; but they have recently been extended and generalized, and the mutual relations of the various methods brought to light, by Schimper, Braun, and others. If we write down in order the series of fractions which represent the simpler forms of phyllotaxis already noticed, as determined by observation, viz. 4, 4, 2, $, we can hardly fail to perceive the relation that they bear to each other. For the numerator of each is composed of the sum of the numerators of the two preceding fractions, and the denominator of the sum of the two preceding denominators. Also the numerator of each fraction is the denominator of the next but one preceding. Extending this series, we obtain the further terms, 45, 3, 42, 24, &e. Now these numbers are verified by observation, and, with some abnormal excep- tions, this series 3, 4, 2, 2, 45, 28, $2, 24, comprises all the varia- FIG. 204. A branch exhibiting the five-ranked arrangement of leaves. FIG. 205. Diagram of the same: a spiral line is drawn ascending the stem and passing through the successive scars which mark the position of the leaves from 1 to6. It is madea dotted line where it passes on the opposite side of the stem, and the scars 2 and 5, which fall on that side, are made fainter. 206. A plane, horizontal projection of the same; the dotted line passing from the edge of the first leaf to the second, and so on to the fifth leaf, which completes the cycle ; as the sixth would come directly before, or within, the first. THEIR ARRANGEMENT. 137 tions of the arrangement of alternate leaves that actually occur. These higher forms are the most common where the leaves are crowded on the stem, as in the rosettes of the Houseleek (Fig 207), and the scales of the Pine-cones (for the ar- rangement extends to all parts that are modifi- cations of leaves), or where they are numerous and small in proportion to the circumference of the stem, as the leaves of Firs, &c. In fact, when the internodes are long and the base of the leaves large in proportion to the size of the stem, it is difficult, and often impossible, to tell whether the 9th, 14th, or 22d leaf stands ex- actly over the first. And when the internodes are very short, so ‘that the leaves touch one another, or nearly so, we may readily per- ceive what leaves are superposed; but it is then difficult to follow the succession of the intermediate leaves. The order, however, may be deduced by simple processes. 243. Sometimes we can readily count the number of vertical ranks, which gives the denominator of the fraction sought. Thus, if there are eight, we refer the case to the 3 arrangement in the regu- lar series; if there are thirteen, to the 35; arrangement, and so on. Commonly, however, when the leaves are crowded, the vertical ranks are by no means so manifest as two or more orders of oblique series, or secondary spirals, which are at once seen to wind round the axis in opposite directions, as in the Houseleek (Fig. 207; where the numbers, 1, 6,11 belong to a spire that winds to the left; 1, 9,17 to another, which winds to the right; and 3, 6, 9, 12 to still another, that winds in the same direction): they are still more ob- vious in Pine-cones (Fig. 208, 209). These oblique spiral ranks are a necessary consequence of the regular ascending arrangement of parts with equal intervals over the circumference of the axis: and if the leaves are numbered consecutively, these numbers will neces- sarily stand in arithmetical progression on the oblique ranks, and have certain obvious relations with the primary spiral which origi- nates them ; as will be seen by projecting them on a vertical plane. 244, Take, for example, the quincunical (2) arrangement, where, as in the annexed diagram, the ascending spiral, as written on a plane surface, appears in the numbers 1, 2, 3, 4, 5, 6, and so on: FIG. 207. An offset of the Houseleek, with the rosette of leaves unexpanded, exhibiting the 5-18 arrangement ; the fourteenth leaf being directly over the first. 12* 138 THE LEAVES. the vertical ranks thus formed, beginning with the lowest (which 6 we place in the middle column, that it 13 may correspond with the Larch-cone, Fig. n 208, where the lowest scale, 1, is turned 8 directly towards the observer), are neces- 8 sarily the numbers 1, 6,11; 4,9, 14; 2, 7, .3 + * +] 19; 5, 10, 15; and 3, 8, 13. But two *1 + | parallel oblique ranks are equally apparent, ascending to the left; viz. 1, 8,5, which, if we coil the diagram round a cylinder, will be continued into 7, 9, 11, 13,15; and also 2, 4, 6, 8, 10, which runs into 12, 14, and so on, if the axis be further prolonged. Here the circumference is occupied by two secondary left-hand series, and we notice that the common difference in the sequence of numbers is two: that is, the number of the parallel sec- ondary spirals is the same as the common difference of the numbers on the leaves that compose them. Again, there are other parallel secondary spiral ranks, three in number, which ascend to the right ; viz. 1, 4, 7, continued into 10,13; 3, 6, 9,12, continued into 15; and 5, 8, 11,14, &e. ; where again the common difference, 3, accords with the number of such ranks. This fixed relation enables us to lay down the proper numbers on the leaves, when too crowded for directly following their succession, and thus to ascertain the order of the primary spiral series by noticing what numbers come to be super- posed in the vertical ranks. We take, for example, the very simple cone of the small-fruited’ American Larch (Fig. 208), which usually completes only two cycles; for we see that the lowest, one interme- diate, and the highest scale, on the side towards the observer, stand in a vertical row. Marking this lowest scale 1, and counting the parallel secondary spirals that wind to the left, we find that two occupy the whole circumference. From 1, we number on the scales of that spiral 3, 5, 7, and so on, adding the common difference 2, at each step. Again, counting from the base the right-hand secondary spirals, we find three of them, and therefore proceed to number the lowest one by adding this common difference, viz. 1,4,7,10; then, pass- ing to the next, on which the No. 3 has already been fixed, we carty on that sequence, 6, 9, &c.; and on the third, where No. 5 is already fixed, we continue the numbering, 8, 11, &e. This gives us, in the vertical rank to which No. 1 belongs, the sequence 1, 6, 11, showing FIG. 208. A cone of the small-fruited American Larch (Larix Americana), with the scales numbered, exhibiting the five-ranked arrangement, as in the annexed diagram, THEIR ARRANGEMENT. 139 that the arrangement is of the quincuncial (?) order. It is further noticeable, that the smaller number of parallel secondary spirals, 2, agrees with the numerator of the fraction in this the 2 arrangement; and that this number added to that of the parallel secondary spirals which wind in the opposite direction, viz. 3, gives the denominator of the fraction. This holds good throughout; so that we have only to count the number of parallel secondary spirals in the two direc- tions, and assume the smaller number as the numerator, and the sum Vertical Projection Vertical Projection of the By of the 8 Arrange- Arrangement. ment. 27 25 26 a 25 23 24 22 23 , 21 22 20 21 19 20 13 19 1 as 16 8 i 15 5 7" 15 13 i 1B 13 2 TT 12 10 n 9 10 3 9 . 8 Gi 6 7 6 5 ri 5 8 4 3 2 2 1 1 of this and the larger number as the denominator, of the fraction which expresses the angular divergence sought. For this we must FIG 209. A cone of the White Pine, on which the numbers are laid down, and the leading higher secondary spirals are indicated: those with the common difference 8 are marked by dotted lines ascending to the right; two of the five that wind in the opposite direction are also marked with dotted lings: the set with the common difference 3, in one direction, and that with the common difference & in the other, are very manifest in the cone. 140 THE LEAVES. take, however, the order of secondary spirals nearest the vertical rank in each direction, when there are more than two, as there are in all the succeeding cases. 245. A similar diagram of the 2 arrangement introduces a set of secondary spirals, in addition to the two foregoing, ascending in a near- er approach to a vertical line, and with a higher common difference, viz. 5. There are accordingly five of this sort, viz. those indicated in the diagram by the series 1, 6, 11,16; 4, 9, 14, 19, 24; 2, 7, 12, 17, 22; 5,10, 15, 20, 25; and 3, 8,18, 18,23. The highest obvious spiral in the opposite direction, viz. that of which the series 1, 4, 7, 10, 13 is a specimen, has the common difference 3, and gives the numerator, and 38-+ 5 the denominator, of the fraction 3. The next case, >5;, which is exemplified in the rosettes of the Houseleek (Fig. 207) and in the cone of the White Pine (Fig. 209), introduces a fourth set of secondary spirals, eight in number, with the common difference cight, viz. that of which the series 1, 9, 17, 25 is a repre- sentative. The set that answers to this in the opposite direction, viz. 1, 6, 11, 16, 21, 26, with the common difference 5, gives the numerator, and 5-+ 8 the denominator, of the fraction ;. We may here compare the diagram with an actual example (Fig. 209): a part of the numbers are of course out of sight on the other side of the cone. The same laws equally apply to the still higher modes. 246. The order is uniform in the same species, but often various in allied species. Thus, it is only 2 in our common American Larch; in the European species, ~. The White Pine is ;5, as is also the Black Spruce ; but other Pines with thicker cones exhibit in differ- ent species the fractions 38, 42, and 24. Sometimes the primitive spiral ascends from left to right, sometimes from right to left. One direction or the other generally prevails in each species, yet both directions are not unfrequently met with, even in different cones of the same tree. 247, When a branch springs from a stem or parent axis, the spi- ral is continued from the leaves of the stem to those of the branch, so that the leaf from whose axil the branch arises begins the spire of that branch. When the spire of the branch turns in the same direction as that of the parent axis, as it more commonly does, it is said to be homodromous (from two Greek words, signifying like course): when it turns in the opposite direction, it is said to be heterodromous (or of different course). 248. The cases represented by the fractions 4, 4, and 2 are the THEIR ARRANGEMENT. 141 most stable and certain, as well as the easiest to observe. In the higher forms, the exact order of superposition often becomes uncer- tain, owing to a slight torsion of the axis, or to the difficulty of observing whether the 9th, 14th, 22d, 35th, or 56th leaf is truly over the first, or a little to the one side or the other of the vertical line. Indeed, if we express the angle of divergence in degrees and minutes, we perceive that the difference is so small a part of the circumference, that a very slight change will substitute one order for another. The divergence in 78, = 138° 24’. In all those beyond, it is 187° plus a variable number of minutes, which approaches nearer and nearer to 80’. Hence M. Bravais considers all these as mere alterations of one typical arrangement, namely, with the angle of divergence 137° 80’ 28”, which is irrational to the circumference, that is, not capable of dividing it an exact number of times, and con- sequently never bringing any leaf precisely in a right line over any preceding leaf, but placing the leaves of what we take for vertical ranks alternately on both sides of this line and very near it, approach- ing it more and more, without ever exactly reaching it. These forms of arrangement he therefore distinguishes as curviserial, be- cause the leaves are thus disposed on an infinite curve, and are never brought into exactly straight ranks. The others are correspondingly termed rectiserial, because, as the divergence is an integral part of the circumference, the leaves are necessarily brought into rectilineal ranks for the whole length of the stem. 249, A different series of spirals sometimes occurs in alternate leaves, viz. }, 1, 2, 5 and still others have been detected; but these are rare or exceptional cases. 250. Opposite Leaves (237, Fig. 210). In these, almost without exception, the second pair is placed over the intervals of the first, the third over the intervals of the second, and so on. More commonly, as in plants of the Labiate or Mint Family, the successive pairs cross each other exactly at right angles, so that the third pair stands directly over the first, the fourth over the second, &c., forming four equidistant vertical ranks for the FIG. 210. Opposite leaves of the Strawberry-bush, or Euonymus Americanus. 142 THE LEAVES. whole length of the stem. In this case, the leaves are said to be decussate. In other cases, as in the Pink Family, often the succes- sive pairs deviate a little from this line, so leaves. that we have to pass several pairs before we reach one exactly superposed over the pair we start with. This indicates a spiral ar- rangement, which falls into some one of the modes already illustrated in alternate leaves» only that here each node bears a pair of 251. Verticillate or Whorled Leaves (Fig. 211) follow the same modes of arrangement as op- posite leaves. Sometimes they decussate, or the leaves of one whorl correspond to the intervals of that underneath, making twice as many vertical ranks as there are leaves in the whorl ; sometimes they wind spirally, so that each leaf of the whorl belongs to as many parallel spirals, analogous to the secondary spirals in the case of alternate leaves. 252. The opposition or alternation of the leaves is generally constant in the same species, and often through the same family ; yet both modes occasionally occur on the same stem, as in the common Snap- dragon and the Myrtle. All Exogens, having their cotyledons opposite, necessarily commence with that mode (Fig. 103-125); many retain it throughout ; others change to alternation, either directly in the primordial leaves (Fig. 111%, 121), or at a later period. In Endogens, on the contrary, the first leaves are necessarily alternate (128), and it is seldom that they afterwards exhibit opposite or whorled leaves. The Pine in germination commences with a whorl of leaves (Fig. 1383, 184); but the subsequent ones are alternate. The Pine, however (Fig. 212), and the Larch, bear what are termed 253. Fascicled Leaves. These are really the leaves of an axil- lary bud. They remain in a tuft or cluster because the axis of FIG. 211. Verticillate or whorled leaves of a Galium or Bedstraw. FIG. 212. Piece of a branchlet of Pitch Pine, with three leaves in a fascicle or bundle, in the axil of a thin scale (2) which answers to a primary leaf. The bundle is surrounded at the base by a short sheath, formed of the delicate scales of the axillary bud. VERNATION OR PRAFOLIATION. 148 the bud does not lengthen. This is plainly seen in the spring leaves of the Barberry and of the Larch (Fig. 213), crowded on short spurs, some of which soon elongate into ordinary shoots with scattered alternate leaves. Their nature is Jess evident in Pines, on account of the peculiar character of the leaves of the main axis, from whose axil the tuft of two, three, or five leaves arises, the primary leaf in this case being a thin and chaffy scale (Fig. 212, a) which soon falls off, while the actual foliage all be- longs to the axillary clusters. So in the common Barberry the prop- er leaves of the lengthened stems are chiefly in the form of spines (Fig. 296), and the actual foliage appears in fascicles in their axils. 254, As regards their general position on the stem, leaves are said to be radical, when they are borne on the stem at or below the sur- face of the ground, so as apparently to grow from the root, as those of the Bloodroot, Plantain, Primrose, and of the acaulescent (154) Violets: those that arise along the main stem are termed cauline ; those of the branches, rameal ; and those which stand upon or at the base of flower-branches are called floral ; the latter, moreover, are generally termed bracts. 255. With respect to succession, those leaves which manifestly exist in the embryo are called seminal; the first or original pair receiving the name of cotyledons (120), and usually differing wide- ly in appearance from the ordinary leaves which succeed them. The earliest ordinary leaves are termed primordial. These, as well as the cotyledons, usually perish soon after others are developed to supply their place. 256. As pertaining to the arrangement of leaves, we should here notice the modes in which they are disposed before expansion in the bud; namely, their 257. Vernation or Prafoliation, ‘The latter is the most character- istic name, but the former, given by Linnzus (literally denoting their spring state), is the more ancient and usual. Two things are included under this head : — 1st, the mode in which each leaf con- sidered separately is disposed; 2d, the arrangement of the several FIG. 213. Piece ofa branchlet of the Larch, with two fascicles of leaves. 144 THE LEAVES. leaves of the same bud in respect to each other. This last is evi- dently connected with phyllotaxis, or their position and order of succession on the stem. As to the first, leaves are for the most part either bent or folded, or rolled up in vernation. Thus, the upper part may be bent on the lower, so that the apex of the leaf is brought down towards the base, as in the Tulip-tree, when the leaves are inflexed or reclinate in vernation; or the leaf may be folded along its midrib or axis, so that the right half and the left half are applied together, as in the Oak and the Magnolia, when the leaves are conduplicate ; or each leaf may be folded up a cer- tain number of times like a fan, as in the Maple, Currant, and Vine, when they are said to be plicate or plaited. The leaf may be rolled either parallel with its axis, or on its axis. In the latter case it is spirally rolled up from the apex towards the base, like a crosier, or ctrcinnate, as in true Ferns (Fig. 100), and among Phenoga- mous plants in the Drosera or Sundew. Of the former there are three ways; viz. the whole leaf may be laterally rolled up from one edge into a coil, with the other edge exterior, when the leaves are said to be convolute, as in the Apricot and Cherry ; or both edges may be equally rolled towards the midrib; either inwards, when they are ¢nvolute, as in the Violet and the Water-Lily ; or else out- wards, when they are revolute, as in the Rosemary and Azalea. Fig. 214-219 are Linnean diagrams of sections of leaves, illustrating the principal modes of vernation. 258. Considered relatively to each other, leaves are valvate in vernation when corresponding ones touch each other by their edges aut a5 216 only, without overlap- ping: they are ¢mbri- cated when the outer successively overlap the inner, by their edges at least, in which 6O E9 case the order of over- lapping exhibits the a7 218 phyllotaxis, or order of succession and po- ae sition. In these cases the leaves are plane or convex, or at least not much bent or rolled. FIG. 214. Conduplicate; 215. Plicate or plaited; 216. Convolute; 217. Revolute; 218. Involute ; and, 219. Circinate, vernation. THEIR STRUCTURE AND CONFORMATION. 145 When leaves with their margins involute are applied together in a circle without overlapping, the vernation is ixduplicate. When, in conduplicate leaves, the outer successively embrace or sit astride of those next within, the vernation is eguitant, as the leaves of the Iris at their base (Fig. 296); or when each receives in its fold the half of a corresponding leaf folded in the same manner, the vernation is half-equitant or obvolute. These terms equally apply to leaves in their full-grown condition, whenever they are then so situated as to overlie or embrace one another. They likewise apply to the parts in the flower-bud, under the name of estivation or prefloration. Chap. IX. Sect. V. Sect. Il. Terr Srructure ann ConroRMATION. 259. Anatomy of the Leaf. The complete leaf consists of the Buiave (Lamina or Limb, Fig. 229, 6), with its Pretroie or Leaf- stalk, p, and at its base a pair of StipuLEs, sf. Of these the latter are frequently absent altogether, and in many cases where they originally exist they fall away as the leaf expands. The petiole is very often wanting; when the leaf is sessile, or has its blade rest- ing immediately on the stem that bears it (as in Fig. 210, 211). Sometimes, moreover, there is no proper blade, but the whole organ is cylindrical or stalk-like. It is the general characteristic of the leaf, however, that it is an expanded body. Indeed, it may be viewed as a contrivance for increasing the green surface of a plant, so as to expose to the light and air the greatest practicable amount of paren- chyma containing the green matter of vegetation (chlorophyll, 92), upon which the light exerts its peculiar action. Leaves as foliage, accordingly, are what we are now principally to consider, 260. In a general, mechanical way, it may be said leaves are defi- nite protrusions of the green layer of the bark, expanded horizon- tally into a thin lamina, and stiffened by tough, woody fibres (con- nected both with the liber, or inner bark, and the wood), which form its framework, ribs, or veins. Like the stem, therefore, the leaf is made up of two distinct parts, the cellular and the woody. ‘The cellular portion is the green pulp or parenchyma: the woody, is the skeleton or framework which ramifies among and strengthens the former. The woody or fibrous portion fulfils the same purposes in the leaf as in the stem, not only giving firmness and support to the 13 146 THE LEAVES. delicate cellular apparatus, but also serving for the conveyance and distribution of the sap. The subdivision of these ris, or veins, of the leaf, as they are not inappropriately called, continues beyond the limits of unassisted vision, until the bundles or threads of woody dissue are reduced to very delicate fibres, ramified throughout the green pulp. 261. The cellular portion of the leaf consists of thin-walled cells of loose parenchyma, containing grains of chlorophyll, to which the green color of foliage is entirely owing. The cells are not heaped promiscuously, but exhibit a regular arrangement; upon a plan, too, which varies in different parts of the leaf, according to the different conditions in which it is placed. 262. Leaves are almost always expanded horizontally, so as to present one surface to the ground and the other to the sky; and the parenchyma forms two general strata, one belonging to the upper and the other to the lower side. The microscope displays a manifest difference in the parenchyma of these two strata. That of the upper stratum is composed of one or more compact layers of oblong cells, placed endwise, or with their long diameter perpen- dicular to the surface ; while that of the lower stratum is very loosely arranged, leaving numerous vacant spaces between the cells; and when the cells are oblong, their longer diameter is parallel with the epidermis. This is shown in Fig. 7, which represents a magnified section through the thickness (perpendicular to the surface) of a leaf of the Star-Anise of Florida; where the upper stratum of parenchyma consists of only a single series of perpendicular cells. Also in Fig. 220, which represents a similar view of a thin slice of a leaf of the Gar- den Balsam. Fig. 221 repre- sents a piece cut out of a leaf of the White Lily ; where the upper stratum is composed of only one compact layer of ver- tical cells. The parenchyma is alone represented ; the woody por- tion, or veins, being left out. The more compact structure of the FIG 220. Magnified section through the thickness of a leaf of the Garden Balsam : a, sec- tion of the epidermis of the upper surface ; 5, of the upper stratum of parenchyma ; c, of the lower stratum ; d, of the epidermis of the lower surface. (After Brongniart.) THEIR ANATOMICAL STRUCTURE. 147 upper stratum shows why the upper surface of leaves is of a deeper green than the lower. 263. The object which this arrangement subserves will appear evident, when we consider that the spaces between the cells, filled with air, communicate freely with each other throughout the leaf, and also with the external air by means of openings in the epider- mis (presently to be described) ; and when we consider the powerful action of the sun to promote evaporation, especially in dry air; and that the thin walls of the cells, like all vegetable membrane, allow of the free escape of the contained moisture by transudation. The compactness of the cells of that stratum which is presented immedi- ately to the sun, and their vertical elongation, so that each shall expose the least possible surface, obviously serve to protect the loose parenchyma beneath from the too powerful action of direct sunshine. This provision is the more complete in the case of plants which retain their foliage through a season of drought in arid re- gions, where the soil is usually so parched during the dry season, that, for a long period, it affords only a scanty supply of moisture to the roots. Compare, in this respect, a leaf of the Lily (Fig. 221), where the upper stratum contains but a single layer of barely oblong cells, with the firm and more enduring leaf of the Oleander, the © OF ae *« ie ovo o ote beg 09 Ris oa es leew D271 ope ely % Hs at, Saver are) 22h upper stratum of which consists of two layers of long and narrow vertical cells as closely compacted as possible (Fig. 222). So dif FIG. 221. A magnified section through the thickness of a minute piece of the leaf of the White Lily of the gardens, showing also a portion of the under side with some breathing-pores, 148 THE LEAVES. ferent is the organization of the two strata, that a leaf soon perishes if reversed so as.to expose the lower surface to direct sunshine. 264, A further and more effectual provision for restraining the perspiration of leaves within due limits is found in the Epidermis, or skin, that invests the leaf, as it does the whole surface of the vege- table (69), and which is so readily detached from the succulent leaves of such plants as the Stonecrop and the Live-for-ever (Sedum) of the gardens. The epidermis is composed of small cells belonging to the outermost layer of cellular tissue, with the pretty thick-sided walls very strongly coherent, so as to form a firm membrane. Its cells contain no chlorophyll. In ordinary herbs that allow of ready evaporation, this membrane is made up of a single layer of cells; as in the Lily, Fig. 221, and the Balsam, Fig. 220. It is composed of two layers in cases where one might prove insufficient ; and in the Oleander, besides the provision against too copious evaporation, already described (263), the epidermis consists of three com- pact layers of very thick-sided cells (Fig. 222). It is generally thick, or hard and impermeable, in the firm leaves of the Pitto- sporum, Laurustinus, and other plants, which will thrive, for this very reason, where those of more delicate foliage are liable to per- ish, in the dry atmosphere of our rooms in winter. FIG 222. Magnified section through a part only of the thickness of a leaf of the Oleander, showing the epidermis of the upper surface, formed of three layers of thick-walled cells and the two very compact layers of cylindrical cells standing endwise. FIG. 223. Magnified slice of the epidermis and superficial parenchyma of a Cactus, after Schleiden ; exhibiting the epidermis (a) greatly thickened by a stratified deposition in the cells : and some cells of the parenchyma likewise nearly filled with an incrusting deposit. The depo- sition in such cases is always irregular, leaving canals or passages which nearly connect the adjacent cells. Several of the cells contain crystals (94). FIG. 224 Similar section from another species of Cactus, passing through one of the sto- mata, and the deep intercellular space beneath it, THEIR ANATOMICAL STRUCTURE. 149 265. In such firm leaves, especially, the walls of the epidermal cells are soon thickened by internal deposition (44), especially on the superficial side. This is well seen in the epidermis of the Aloe, and in other fleshy plants, which bear severe drought with impunity: in Fig. 223, it is shown, at a, in the rind of a Cactus, in which the green layer of the whole stem answers the purpose of leaves. Sometimes an exterior layer of this superficial deposit in the epidermis may be detached in the form of a continuous, ap- parently structureless membrane, which Brongniart and succeeding authors have called the Curicyr. That it may shed water readily, the surface of leaves is commonly protected by a very thin varnish of wax, or else with a bloom of the same substance in the form of a whitish powder, which easily rubs off (85), as is familiarly seen in a Cabbage-leaf. 266. A thickening deposit sometimes takes place in the cells of parenchyma immediately underneath the epidermis, especially in the Cactus Family, where the once thin and delicate walls of the cells become excessively and irregularly thickened (Fig. 223, 224), so as doubtless to arrest or greatly obstruct exhalation through the rind. Something like this choking of the cells must commonly occur with age in most leaves, particularly those that live for more than one season (311). : 267. But the multiplication of these safeguards against exhalation might be liable to defeat the very objects for which leaves are prin- cipally destined. Evaporation from the parenchyma of the leaves is essential to the plant, as it is the only method by which its exces- sively dilute food can be concentrated. Some arrangement is requi- site that shall allow of sufficient exhalation from the leaves while the plant is freely supplied with moisture by the roots, but restrain it when the supply is deficient. It is clear that the greatest demand is made upon the leaves at the very period when the supply through the roots is most likely to fail; for the summer’s sun, which acts so powerfully on the leaves, at the same time parches the soil upon which the leaves (through the rootlets) depend for the moisture they exhale. So long as their demands are promptly answered, all goes well. The greater the force of the sun’s rays, the greater the speed at which the vegetable machinery is driven. But whenever the supply at the root fails, the foliage begins to flag and droop, as is so often seen under a sultry meridian sun; and if the exhaustion pro- ceeds beyond a certain point, the leaves inevitably wither and perish. 13* 150 THE LEAVES. Some adaptation is therefore needed, analogous to a self-acting valve, which shall regulate the exhalation according to the supply. Such an office is actually fulfilled by 268. The Stomata, Stomates, or Breathing-pores (70). Through the orifices which bear this name, exhalation principally takes place, in all ordinary cases, where the epidermis is thick and firm enough to prevent much escape of moisture by direct transudation. The stomata (Fig. 225 — 228) are always so situated as to open directly into the hol- low chambers, or air-cavities, which pervade the parenchyma (Fig. 221), especially the lower stratum, so as to afford free communication between the external air and the whole interior of the leaf. The perforation of the epi- 225 dermis is between two (or rarely four) delicate and commonly crescent-shaped cells, which, unlike the rest of the epidermis, usually contain some chlorophyll, and in other re- spects resemble the parenchyma beneath. When moistened these guardian-cells change their form, becoming more crescentic as they become more turgid, thereby separating in the middle and opening a free communication between the outer air and the interior of the leaf. As they become drier, they shorten and straighten, so as to bring the sides of the two into contact and close the orifice.* The use of this mechanism will be readily understood. So long as the leaf * They expand and contract most in the direction of their length; and the elongation and increased curvature when moist draws in the concave side and so enlarges the aperture. The mechanism of the opening and shutting of sto- mata has been recently investigated by Mohl (in Bot. Zeitung for 1856, p. 697, —an abstract of the memoir is given by C. F. Stone in Amer. Journal of Sci- ence for March, 1857), — and these facts verified. The peculiar change of the guardian-cells in form seems not entirely susceptible of mechanical explanation, and is partly controlled (like other vegetable movements) by the light of the sun; but it mainly depends upon endosmose. Mohl has clearly shown that, while the guardian-cells themselves act so as to open the stomate in moisture and close it in dryness, the adjacent cells of the epidermis in swelling when moist tend to close the stomate, and their contraction when dry to open it ;— so that the actual position at any time is a resultant of nicely adjusted opposing forces. FIG. 225. A highly magnified piece of the epidermis of the Garden Balsam, with three stomata (after Brongniart). : THEIR STOMATA OR BREATHING-PORES. 151 is in a moist atmosphere, and is freely supplied with sap, the sto- mates remain open, and allow the free escape of moisture by evap- oration. But when the supply fails, and the parenchyma begins to be exhausted, the guardian-cells, at least equally affected by the dry- ness, promptly collapse, and by closing these thousands of apertures check the drain the moment it becomes injurious to the plant. 269. As a general rule, the stomata wholly or principally belong to the epidermis of the lower surface of the leaf: the mechan- ism is too delicate to work well in direct sunshine. The posi- tion of the stomata, and the loose texture of the lower pa- renchyma, require that this sur- face should be shielded from the sun’s too direct and intense action ; and show why leaves soon perish when artificially reversed, and pre- vented from resuming (as otherwise they spontaneously will) their natural position, This general arrangement is variously modified, however, under peculiar circumstances. The stomata are equally distributed on the two sides of those leaves, of whatever sort, which grow in an erect position, or present their edges, instead of their surfaces, to the earth and sky (294), and have the parenchyma of both sides similarly constituted, sustaining consequently the same relations to light. In the Water-Lilies (Nymphza, Nuphar), and other leaves which float upon the water, the stomata all belong to the upper surface. All leaves which live under water, where there can be no evaporation, are destitute, not only of stomata, but usually of a distinct epidermis also. 270. The number of the stomata varies in different leaves from 800 to about 170,000 on the square inch of surface. In the Apple, there are said to be about 24,000 to the square inch (which is under the average number, as given in a table of 36 species by Lindley) ; so that each leaf of that tree would present about 100,000 of these orifices. When the stomata are not all restricted to the lower sur- face, still the greater portion usually occupy this position. Thus, the leaf of Arum Dracontium is said to have 8,000 stomata to a square inch of the upper surface, and twice that number in the ta SS FIG, 226, Magnified view of the 10,000th part of a square inch of the epidermis of the lower surface of the leaf of the White Lily, with its stomates. 227. A single stomate, more magnified. 228. Another stomate, widely open. — 152 THE LEAVES. same space of the lower. The leaf of the Coltsfoot has 12,000 stomata to a square inch of the lower epidermis, and only 1,200 in the upper. That of the White Lily has from 20,000 to 60,000 to the square inch on the lower surface, and perhaps 3,000 on the up- per. In this plant, and in other true Lilies, they are so remarkably large (Fig. 221, 226 — 228) that they may be discerned by a simple lens of an inch focus. In most plants they are very much smaller than this. : 271. Succulent or fleshy plants, such as those of the Cactus tribe, Mesembryanthemums, Sedums, Aloes, &c., are remarkable for holding the water they imbibe with great tenacity, rather in consequence of the thickness of the epidermis, or from the deposit which early ac- cumulates in the superficial cells of the parenchyma (266), than from the want of stomata. The latter are usually abundant,* but they seem to open less than in ordinary plants, except in young and growing parts. Hence the tissue becomes gorged as it were with fluid, which is retained with great tenacity, especially during the hot season. They are evidently constructed for enduring severe droughts ; and are accordingly found to inhabit dry and sunburnt places, such as the arid plains of Africa, — the principal home of the Stapelias, Aloes, succulent Euphorbias, &c.,—or the hottest and driest parts of our own continent, to which the whole Cactus family is indigenous. Or, when such plants inhabit the cooler temperate regions, like the Sedums and the common Houseleek, &c., they are commonly found in the most arid situations, on naked rocks, old walls, or sandy plains, exposed to the fiercest rays of the noonday sun, and thriving where ordinary plants would speedily perish. The drier the atmosphere, the greater their apparent reluctance to part with the fluid they have accumulated, and upon which they live during the long period when little or no moisture is yielded by the soil or the air, Their structure and economy fully explain tneir tolerance of the very dry air of our houses in midwinter, when or- dinary thin-leaved plants become unhealthy or perish. 272. Sometimes the leaves of succulent plants merely become obese or misshapen, like those of the Ice-plant and other species * The thickened epidermis of the fleshy leaves of the Sea-Sandwort (Hon- kenya) is provided with an abundance of large stomata, on the upper as well as the lower face. But this plant, though very fleshy, grows in situations where its roots are always supplied with moisture. THEIR DEVELOPMENT, ETC. “158 of Mesembryanthemum, &c.: sometimes they are reduced to tri- angular projections or points, or are perfectly confounded with the green bark of the stem, which fulfils their office, as in the Stapelia and most Cacti. 273. The Development of Leaves. At their first appearance, each leaf is a minute papilla or projection of parenchyma on the nascent axis : as it grows, this shapes itself into the blade, and is eliminated from the axis, The petiole, if any, is later formed, and by its growth raises the blade from the stem. Commonly the apex of the blade first appears, and the formation proceeds from above down- wards. The sheath at the base (as in most Monocotyledons), or the stipules (259, which principally belong to Dicotyledons), are at first continuous with the blade, or divided from it by a mere con- striction : the formation and elongation of the petiole soon separate them. The stipules, remaining next the axis or source of nourish- ment, undergo a rapid development early in the bud, so that, at a certain stage, they are often larger than the body of the leaf, and they accordingly form in such cases the teguments of the bud. Divided or lobed and compound leaves are simple at the commence- ment, but the lobes are very early developed ; they grow in respect to the axis of the leaf nearly as that grew from the axis of the plant, and in the compound leaf at length isolate themselves, and are often raised on footstalks of their own. Commonly the upper lobes or leaflets are first formed, and then the lower: but in those of the Walnut and Ailanthus, and other large compound leaves, the formation proceeds from below upwards, and new leaflets continue to be produced from the apex, even after the lowermost are nearly full grown. In the earliest stage leaves consist of parenchyma alone: the fibro-vascular tissue which makes the ribs, veins, or framework appears later. . 274, At the points on the surface of the developing leaf where stomata are about to be formed, one of the epidermal cells early ceases to enlarge and thicken with the rest, but divides into two (in the manner formerly described, 33), forming the two guardian-cells of the stomate: as they grow, the two constituent portions of their common partition separate, leaving an interspace or orifice between. In some cases, each new cell divides again, when the stomate is formed of four cells in place of two. 275. The Forms of Leaves are almost infinitely various. These afford some of the readiest, if not the most certain, marks for 154 THE LEAVES. characterizing species. Their principal modifications are therefore classified, minutely defined, and embodied in a system of nomen- clature which is equally applicable to other parts of the plant, and which as an instrument is indispensable to the systematic botanist. The numerous technical terms which have gradually accumulated from the infancy of the science, and have multiplied with its increas- ing wants, are mostly quite arbitrary, or have been suggested by real or fancied resemblances of their shapes to various natural or other objects. This arbitrary nomenclature, which formerly severe- ly tasked the memory of the student, was reduced by De Candolle to a clear and consistent system, based upon scientific principles, and of easy application. The fundamental idea of the plan is, that the almost infinite varieties in the form and outline of leaves may be deduced from the different modes and degrees in which the woody skeleton or frarhework of the leaf is expanded or ramified in the parenchyma. Upon this conception the following sketch is based ; in which all the more important terms of the nomenclature of leaves are mentioned and defined. It should be kept in mind, however, that this is not to be taken as an explanation of the actual formation of leaves; but rather as an account of the mutual adap- tation and correspondence of their outlines and framework. For the parenchyma is developed, and the form of the leaf more or less determined, before the framework has an existence. The latter, therefore, cannot have given rise to the outline or shape of the organ. The distribution of the veins or fibrous framework of the leaf in the blade is termed its 276. Venation, The veins are distributed throughout the lamina in two principal modes. Either the vessels of the petiole divide at once, where they enter the blade, into several veins, which run parallel with each other to the apex, connected only by simple transverse veinlets (as in Fig. 230); or the petiole is continued into the blade in the form of one or more principal or coarser veins, which send off branches on both sides, the smaller branch- lets uniting with one another (anastomosing) and forming a kind of network; as in Fig. 229. The former are termed parallel- veined, or commonly nerved leaves; the veins in this case having been called nerves by the older botanists, —a name which it is found convenient to retain, although of course they are in no respect analogous to the nerves of animals. The latter are termed reticu- lated or netted-veined leaves. THEIR VENATION. 155 277. Parallel-veined or nerved leaves are characteristic of En- dogenous plants; while reticulated leaves are almost universal in 230 Exogenous plants. We are thus furnished with a very obvious, al- though by no means absolute, distinction between these two great classes of plants, independently of the structure of their stems (198). 278. In reticulated leaves, the coarse primary veins (one or more in number), which proceed immediately from the apex of the petiole, are called ribs ; the. branches are termed veins, and their subordinate ramifications, veinlets. Very frequently, a single strong rib (called the midrib), forming a continuation of the petiole, runs directly through the middle of the blade to the Apex (Fig. 229, 238, &e.), and from it the lateral veins all diverge. Such leaves are termed feather-veined or pinnately veined ; and are subject to vari- ous modifications, according to the arrangement of the veins and vein- lets; the primary veins sometimes passing straight from the midrib to the margin, as in the Beech and Chestnut (Fig. 238) ; while in other cases they are divided into veinlets long before they reach the margin. When the midrib gives off a very strong primary vein or branch on each side above the base, the leaf is said to be triple- ribbed, or often tripli-nerved, as in the common Sunflower (Fig. FIG. 229. A leaf of the Quince, of the netted-veined or reticulated sort: 6, blade: Pp, petiole or leaf-stalk : st, stipules. FIG. 280. Parallel-veined leaf of the Lily of the Valley. 156 THE LEAVES. 241) ; if two such ribs proceed from each side of the midrib, it is said to be guintuple-ribbed, or guintupli-nerved. 23 232 279. Not unfrequently the vessels of a reticulated leaf divide at the apex of the petiole into three or more portions or ribs of nearly equal size, which are usually divergent, each giving off veins and veinlets, like the single rib of a feather-veined leaf. Such leaves are termed radiated-veined, or palmately-veined ; and, as to the number of the ribs, are called three-ribbed, five-ribbed, seven-ribbed, &e. (Fig. 244, 247, 253). Examples of this form are furnished by the Maple, the Gooseberry, the Mallow family, &c. Occasionally the ribs of a radiated-veined leaf converge and run to the apex of the blade, as in Rhexia and other plants of the same family, thus resem- bling a parallel-veined or nerved leaf; from which, however, it is distinguished by the intermediate netted veins. But when the ribs are not very strong, such leaves are’ frequently said to be nerved, although they branch before reaching the apex. 280. According to the theory of De Candolle (275), the shape which leaves assume may be viewed as dependent upon the dis- tribution of the veins, and the quantity of parenchyma; the gen- eral outline being determined by the division and direction of the veins; and the form of the margin, (whether even and continuous, or else interrupted by void spaces or indentations,) by the greater or FIG. 281-244, ‘Various forms of simple leaves. THEIR FORMS. 157 less abundance of the parenchyma in which the veins are distrib- uted. This view is readily intelligible upon the supposition that a 25 2aT 248 leaf is an expansion of soft parenchyma, in which the firmer veins are variously ramified. Thus, if the principal veins of a feather- veined leaf are not greatly prolonged, and are somewhat equal in length, the blade will have a more or less elongated form. If the veins are very short in proportion to the midrib, and equal in length, the leaf will be near (as in Fig. 240); if longer in proportion, but still equal, the leaf will assume an oblong form (Fig. 242), which a slight rounding of the sides converts into an oval or ellip- tical outline. If the veins next the base are longest, and especially if they curve forward towards their extremities, the leaf assumes a lanceolate (Fig. 289), ovate (Fig. 241), or some intermediate form. On the other hand, if the veins are more developed beyond the mid- dle of the blade, the leaf becomes obovate (Fig. 232), or cuneiform (Fig. 285). In radiated or palmately veined leaves (Fig. 245-253), where the primary ribs are divergent, an orbicular or roundish out- line is most common. When some of the ribs or their ramifications are directed backwards, a recess, or sinus, as it is termed, is pro- duced at the base of the leaf, which, ‘taken in connection with the general form, gives rise to such terms as cordate or heart-shaped (Fig. 244), reniform or kidney-shaped (Fig. 245), &c., when the posterior portions are rounded; and those of sagittate or arrow- headed (Fig. 252), and hastate or halberd-shaped (Fig. 250), when FIG 245-253. Forms of simple, chiefly radiated-veined leaves. 14 158 THE LEAVES. the angles or lobes at the base diverge. The margins of the sinus are sometimes brought into contact and united, when the leaf be- comes peltate or shield-shaped (Fig. 248); the blade being attached to the petiole, not by its apparent base, but by some part of the lower surface. Two or three common species of Hydrocotyle plainly exhibit the transition from common radiated leaves into the peltate form. Thus, the leaf of H. Americana (Fig. 247) is round- ish-reniform, with an open sinus at the base, while in H. inter- rupta and H. umbellata (Fig. 248), the margins have grown to- gether so as to obliterate the sinus, and an orbicular peltate leaf is produced. In nerved leaves, when the nerves run parallel from the base to the apex, as in Grasses (Fig. 237), the leaf is necessa- rily linear, or nearly so; but when they are more divergent in the middle, or towards the base, the leaf becomes oblong, oval, or ovate, &e. (Fig. 248). In one class of nerved or parallel-veined leaves, the simple veins or nerves arise from a prolongation of the petiole in the form of a thickened midrib, instead of the base of the blade, constitut- ing the curvinerved leaves of De Candolle. This structure is almost universal in the Ginger tribe, the Arrowroot tribe, in the Banana, and other tropical plants; and our common Pontederia, or Pickerel-weed (Fig. 236), affords an illustration of it, in which the nerves are curved backwards at the base, so as to produce a cordate outline. 281. As to the margin and particular outline of leaves, they ex- hibit every gradation between the case where the blade is enttre, that is, with the margin perfectly continuous and even (as in Fig. 243), and those where it is cleft or divided into separate portions. The convenient hypothesis of De Candolle connects these forms with the abundance or scantiness of the parenchyma, compared with the divergence and the extent of the ribs or veins; on the supposition that, where the former is insufficient completely to fill up the framework, lobes, incisions, or toothings are necessarily produced, extending from the margin towards the centre. Thus, in the white and the yellow species of Water Ranunculus, there appears to be barely sufficient parenchyma to form a thin covering for each vein and its branches (Fig. 251, the lowest leaf); such leaves are said to be jfiliformly dissected, that is, cut into threads ; the nomenclature in all these cases being founded on the conven- ient (but incorrect) supposition, that a leaf originally entire is cut into teeth, lobes, divisions, &c. If, while the framework remains the same as in the last instance, the parenchyma be more abun- THEIR FORMS. 159 dantly developed, as in fact happens in the upper leaves of the same species when they grow out of water, and is shown in the same figure, they are merely cleft or lobed. If these lobes grow together nearly to the ex- tremity of the principal veins, the leaf is only toothed, serrated, or crenated; and if the small re- maining notches were filled with parenchyma, the leaf would be en- tire. The study of the development of leaves, however, proves that the parenchyma grows and shapes the outlines of the organ in its own way, irrespec- tive of the framework, which is, in fact, adapted to the parenchyma rather than the parenchyma toit. The principal terms which designate the mode and degree of division in simple leaves may now be briefly explained, without further reference to this or any other theory. 282. A leaf is said to be serrate, when the margin is beset with sharp teeth which point forwards towards the apex (Fig. 254) ; dentate, or toothed, when the sharp salient teeth are not directed towards the apex of the leaf (Fig. 255); and crenate, when the teeth are rounded (Fig. 248, 256). A slightly waved or sinuous margin is said to be repand (Fig. 257) ; a more strongly uneven margin, with alternate rounded concavities and convexities, is termed sinuate (Fig. 258). When the leaf’ is irregularly and sharply cut deep into the blade, it is said to be incised (Fig. 259) ; when the portions (or segments) are more definite, it is said to be lobed (Fig. 260, 264); and the terms two-lobed, three-lobed (Fig. 264), five-lobed, &c., express the number of the segments. If the incisions extend about to the middle of the blade, or somewhat deeper, and especially if the sinuses are acute, the leaf is said to be cleft (Fig. 261, 265) ; and the terms two-cleft, three-cleft (Fig. 265), &c. (or in the Latin form, bifid, trifid, &c.), designate the number of the segments: or when the latter are numerous or indefinite, the leaf is termed many-cleft, or multifid. If the segments extend nearly, but not quite, to the FIG. 254-259, Forms of leaves as to the toothing of their margins. 160 THE LEAVES. base of the blade or the midrib, the leaf is said to be parted (Fig. 262, 266): if they reach the midrib or the base, so as to interrupt 260 261 262 263 264 the parenchyma, the leaf is said to be divided (Fig. 263, 267) ; the number of partitions or divisions being designated, as before, by the terms two-, three-, five-parted, or two-, three-, five-divided, &c. 283. As the mode of division always coincides with the arrange- ment of the primary veins, the lobes or incisions of feather-veined, are differently arranged from those of radiated or palmately veined leaves: in the latter, the principal incisions are all directed to the base of the leaf; in the former, towards the midrib. These modi- fications are accurately described by terms indicative of the vena- tion, combined with those that express the degree of division. Thus, a feather-viened (in the Latin form, a pinnately veined) leaf is said to be pinnately cleft or pinnatifid (Fig. 261), when the sinuses reach half-way to the midrib; pinnately parted, when they extend almost to the midrib (Fig. 262); and pinnately divided, when they reach the midrib, dividing the parenchyma into separate portions (Fig. 263). A few subordinate modifications are in- dicated by special terms: thus, a pinnatifid or pinnately parted leaf, with regular, very close and narrow divisions, like the teeth of a comb, is said to be pectinate ; a feather-veined leaf, more or less pinnatifid, but with the lobes decreasing in size towards the base, is 265 266 FIG. 260-267. Pinnately and palmately lobed, cleft, parted, and divided leaves. THEIR FORMS. 161 termed lyrate, or lyre-shaped (Fig. 278); and a lyrate leaf with sharp lobes pointing towards the base, as in the Dandelion (Fig, 279), is called runcinate. A palmately veined leaf is in like man- ner said to be palmately lobed (Fig. 264), palmately cleft (Fig. 265), palmately parted (Fig. 266), or palmately divided (Fig. 267), ac- cording to the degree of division. The term palmate was originally employed to designate a leaf more or less deeply cut into about five spreading lobes, bearing some resemblance to a hand with the fingers spreading ; and it is still used to designate a palmately lobed leaf, without reference to the depth of the sinuses. A palmate leaf with the lateral lobes cleft into two or more segments is said to be pedate (Fig. 249), from a fancied resemblance to a bird’s foot. By desig- nating the number of the lobes in connection with the terms which indicate their extent and their disposition, botanists are enabled to describe all these modifications with great brevity and precision. Thus, a palmately three-parted leaf is one of the radiated-veined kind, which is divided almost to the base into three segments (Fig. 266) ; a pinnately five-parted leaf is one of the feather-veined kind cut into five lobes (two on each side, and one terminal), with the sinuses ex- tending almost to the midrib: and the same plan is followed in de- scribing cleft, lobed, or divided leaves. 284. The segments of a lobed or divided leaf may be again di- vided, lobed, or cleft, in the same way as the original blade, and the same terms are employed in describing them. Sometimes both the primary, secondary, and even tertiary divisions are defined by a single word or phrase; as bipinnatifid (Fig. 280), tripinnatifid, bipinnately parted, tripinnately parted, twice palmately parted, &c. 285. Parallel-veined or nerved leaves would naturally be ex- pected to present entire margins, and this they almost universally do when the nerves are convergent (Fig. 230, 243). Such leaves are often lobed or cleft when the principal nerves diverge greatly, as in the Dragon Arum; but the lobes themselves are entire. 26! 275 SN 8 269 270 271 272 273 274 6 286. There are a few terms employed in describing the apex of a leaf, which may be here enumerated. When a leaf tapers to a FIG. 268-276. Forms of the apex of leaves. 14* 162 THE LEAVES. narrowed or slender apex, it is said to be acuminate (Fig. 268) : when it terminates in an acute angle, it is said to be acute (Fig. 269): when the apex is an obtuse angle, or rounded, it is termed obtuse (Fig. 270) : an obtuse leaf, with the apex slightly indented or depressed in the middle, is said to be retuse (Fig. 272), or, if more strongly notched, emarginate (Fig. 273): an obovate leaf with a wider and more conspicuous notch at the apex is termed obcordate (Fig. 274), being a cordate or heart-shaped leaf inverted. When the apex is, as it were, cut off by a straight transverse line, the leaf is said to be truncate (Fig. 271): when abruptly terminated by a small and slender projecting point, it is mucronate (Fig. 276): when tipped with a stronger and rigid projecting point, or cusp, it is cuspi- date (Fig. 275). 287. All these terms are equally applicable to expanded sur- faces of every kind, such as petals, sepals, &c.: and those terms which are used to describe the modifications of solid bodies, such as stems and stalks, are equally applicable to leaves when these affect similar shapes, as they sometimes do. 288. The whole account, thus far, relates to Srurte Leaves, namely, to those which have a blade of one piece, however cleft or lobed, or, if divided, where the separate portions are neither raised on SN eae FIRSTS? FIG. 277-287. Various forms of lobed and compound leaves. COMPOUND LEAVES. 163 stalklets of their own, nor articulated (by a joint) with the main petiole, so that the pieces are at length detached and fall separately. The distinction, however, cannot be very strictly maintained ; there are so many transitions between simple and 289. Compound Leaves. These have the blade divided into entire- ly separate pieces ; or, rather, they consist of a number of blades, borne on a common petiole, usually supported on stalklets of their own, between which and the main petiole an articulation or joint is formed, more or less distinctly. These separate blades are called Leariets: they present all the diversities of form, outline, or division which simple leaves exhibit; and the same terms are em- ployed in characterizing them. Having the same nature and origin as the lobes or segments of simple leaves, they are arranged in the same ways on the common petiole. Compound leaves accordingly occur under two general forms, the pinnate and the palmate (other- wise called digittate). 290. The pinnate form is produced when a leaf of the pinnately veined sort becomes compound; that is, the leaflets are situated along the sides of the common petiole. There are several modifica-. tions of the pinnate leaf. It is abruptly pinnate, when the leaflets are even in number, and none is borne on the very apex of the petiole or its branches, as in Cassia (Fig. 290), and also in the Vetch tribe, where, however, the apex of the petiole is generally prolonged into a tendril (Fig. 287, 289). It is d¢mpart-pinnate, or pinnate with an oddSleaflet, when the petiole is terminated with a FIG. 288-290. Simply pinnate leaves of various forms. 164 THE LEAVES. leaflet (Fig. 281, 288). There are some subordinate modifications ; such as lyrately pinnate, when the blade of a lyrate leaf (Fig. 278) is completely divided, as in Fig. 285; and ¢tnterruptedly pinnate, when some minute leaflets are irregularly intermixed with larger ones, as is also shown to some extent in the figure last cited. The number of leaflets varies from a great number to very few. When reduced to a small number, such a leaf is said to be pinnately seven-, or five-, or tri-foliolate, as the case may be. A pinnate leaf of three or five leaflets is often called ternate or guinate ; which terms, how- ever, are equally applied to a palmately compound leaf, and also, and more appropriately, to the case of three or five simple leaves growing on the same node. A pinnately trifoliolate leaf (Fig. 286) is readily distinguished by having the two lateral leaflets attached to the petiole at some distance below its apex, and by the joint which is observable at some point between their insertion and the lamina of the terminal leaflet. Such a leaf may even be reduced to a single leaflet ; as in the Orange (Fig. 283) and the primordial leaves of the common Barberry. This is distinguished from a really simple leaf by the joint at the junction of the partial with the general petiole. 291. The palmate or digitate form is produced when a leaf of the palmately veined sort becomes compound ; in which case the leaflets are necessarily all attached to the apex of the common petiole, as in the Horsechestnut and Buckeye (Fig. 277), and the common Clover (Fig. 304). Such leaves of three, five, or any definite number of leaflets, are termed palmately (or digitately) trifoliolate, five-folrolate, &c. £ , eS are $ CG a s z é4 | SE 3 2 a r 8 3 3 eo | # 3 3 i 3 £ 3 3 ee | 8 ° ° 8 $ i) e a 4 a | &__|_ & E i ae ee Carbon, 38.10' 4275| 44.80, 43.72] 45.80] 46.06] 47.53| 48.48 46.10 Hydrogen, | 5.10/ 5.77| 5.10) 6.00, 5.00] 6.09| 4.69) 5.41] 5.80 Oxygen, 80.80: 43.58! 30.50) 44.88) 35.57] 40.53) 87.96| 38.79) 43 40 Nitrogen, 4.50! 1.66| 2.30); 1.50; 2.31) 4.18] 206] 0.35) 2.27 Ashes, 21.50' 6.24; 17.30, 390) 11.32) 3.14) 7.76) 6.97] 243 100.00 100.00 100.90 100.00 ' 100.00] 100.09'19* 901100.00 100.00 uw 188 THE FOOD AND NUTRITION OF PLANTS. numerous weeds which grow chiefly around dwellings, and follow the footsteps of man and the domestic animals, flourish only in a soil abounding in nitrates (their ashes containing a notable quantity either of nitrate of potash or of lime); why the Vine requires alka- line manures, to replace the large amount of tartrate of potash which ' the grapes contain; and why Pines and Firs, the ashes of which ' contain very little alkali, will thrive in thin or sterile soils, while the Beech, Maple, Elm, &c., abounding with potash, are only found in strong and fertile land. 340. Where vegetation is undisturbed by man, all these needful earthy materials, which are drawn from the soil during the growth of the herbage or forest, are in time restored to it by its decay, in an equally soluble form, along with organic matter which the vegetation has formed from the air. But in cultivation, the prod- uce is carried away, and with it the materials which have been slowly yielded by the soil. “A medium crop of Wheat takes from one acre of ground about 12 pounds, a crop of Beans about 20 pounds, and a crop of Beets about 11 pounds, of phosphoric acid, besides a very large quantity of potash and soda. It is obvious that such a process tends continually to exhaust arable land of the mineral substances useful to’vegetation which it contains, and that a time must come, when, without supplies of such mineral matters, the land would become unproductive from their abstraction. ..... Tn the neighborhood of large and populous towns, for instance, where the interest of the farmer and market-gardener is to send the largest possible quantity of produce to market, consuming the least possible quantity on the spot, the want of saline principles in the soil would very soon be felt, were it not that for every wagon-load of greens and carrots, fruit and potatoes, corn and straw, that finds its way into the city, a wagon-load of dung, containing each and every one of the-e principles locked up in the several crops, is returned to the land, and proves enough, and often more than enough, to replace all that has been carried away from it.”* The loss must cither be made up by such equivalent return, or the land must lie fallow from * Boussingault, Economie Rurale: from the Engl. Trans., p. 493. Further: “Tt may be inferred that, in the most frequent case, namely, that of arable lands not sufficiently rich to do without manure, there can be no continuous [independent] cultivation without annexation of meadow ; in other words, one part of the farm must yield crops without consuming manure, so that this may replace the alkaline and earthy salts which are constantly withdrawn by suc- THEIR EARTHY CONSTITUENTS. 189 time to time until these soluble substances are restored by further disintegration of the materials of the soil: or meanwhile the more exhausting crops may be alternated with those that take least from the soil and most from the air; or with one which, like clover, although it takes up 77 pounds of alkali per acre, may be consumed on the field, so as to restore most of this alkali in the manure for the succeeding crop. 341. It has been asserted that the advantage of preceding a wheat crop by one of Leguminous plants (such as Peas, Clover, Lucerne, &c.), or of roots or tubers, is owing to-the fact, that these leave the phosphates, &c. nearly untouched for the wheat which is to follow, and which largely abstracts them. The results of Bous- singault’s experiments and analyses show that these products are far from having the deficiency of phosphates which was alleged. “For example, beans and haricots take 20 and 13.7 pounds of phosphoric acid from every acre of land; potatoes and beet-root take 11 and 12.8 pounds of that acid, exactly what is found ina crop of wheat. Trefoil is equally rich in phosphates with the sheaves of corn that have gone before it.”* His further re- cessive harvests from another part. Lands enriched by rivers alone permit of a total and continued export of their produce without exhaustion. Such are the fields fertilized by the inundations of the Nile ; and it is difficult to form an idea of the prodigious quantitiés of phosphoric acid, magnesia, and potash, which, in a succession of ages, have passed out of Egypt with her incessant exports of corn.”? — p. 503. * Boussingault, /. c., p. 497. —Subjoined is u table, from the same work, of the percentage of Mineral Substances taken up from the soul by various plants grown at Bechelbronn. ‘Acids. = eee mers ga | 28 Substances which 3 |e Z ad as: yielded the Ashes. | 5 a g $ a se l¢ FT 9° a =I og 4 2\/e/28) 8 |g)8)3/ ¢ | 2/32) 88 algje|a [Alf] 2\ 3 |e |3*|é Potatoes, 13.4) 7.11113) 27 | 1.8) 5.4/51.5|traces| 5.6) 0.5 | 07 Mangel-Wurzel, |16.1; 1.6, 6.1] 5.2 | 7.0) 4.4/39.0] 6.0 | 8.0] 25 } 4.2 Turnips, 140 10.9] 6.0} 2.9 |10.9) 4.3)33.7) 4.1 6.4) 1.2 | 5.5 Potato-tops, 11.0, 22/10.8) 1.6 | 2.3) 1.8/44.5\traces|13 0} 5.2 | 76 Wheat, 0.0, 1.0/47.0|traces| 2.9)/15.9/29.5|traces| 1.3; 0.0 | 2.4 Wheat-straw, 00} 1.0} 3.1) 0.6 | 8.5} 50] 9.2] 0.3 |67.6| 1.0 | 3.7 Oats, 17) 1.0)14.9] 0.5 | 3.7| 7.7|/12.9) 0.0 |53.3] 1.3 | 3.0- Oat-straw, * 3.2, 4.1) 3.0] 4.7 8.3) 28/245} 44 |40.0) 2.1 29 Clover, 25.0 2.5| 6.3] 2.6 |246] 63/266] 05 | 53} OF | 0.0 Peas, 0.5, 4.7/30.1} 1.12 |101}11.9/35.3) 2.5 | 1.5/traces} 2.3 French beans, 3.3, 13/268) 0.1 | 5.8/11.5/49.1] 00 | 1.0/traces| 1.1 Horse beans, 10 1.6134.2} 0.7 | 5.1] 8.6145.2| 00 | O5jtraces} 3.1 190 THE FOOD AND NUTRITION OF PLANTS. searches seem to show that these crops exhaust the soil less than the cereal grains, in part at least, on account of the large quantity of organic matter, rich in nitrogen, which they leave to be incor- porated with the soil. The theory of rotation in crops, founded by De Candolle on the assumption that excretions from the roots of a plant accumulate in the soil until in time they become injurious to that crop, but furnish appropriate food for a different species, is entirely abandoned as an explanation; and even the fact that such excretions are formed, at least to any considerable extent, is not made out. That they could accumulate and remain in the soil without undergoing decomposition is apparently impossible. Sect. III. AssimiLarion, on VEGETABLE DIGESTION, AND ITS REsULrts. 842. We have reached the conclusion, that the universal food of plants is rain-water, which has’ absorbed some carbonic acid gas and nitrogen (partly in the form of ammonia or of other compounds) from the air, or dissolved them from the remains of former vegeta- tion in the soil, whence it has also taken up a variable (yet more or less essential) quantity of earthy matter. 843. This fluid, imbibed by the roots, and carried upwards through the stem, receives the name of sap or crude sap (79). Upon its introduction into the plant, this is at once mingled with some elaborated sap or soluble organized matter it meets with; thus becoming sweet in the Maple, &c., and acquiring different sensible properties in different species. This latter is already elab- orated food, and may therefore be immediately employed in vegeta- ble growth. But the crude sap itself is merely raw material, unor- ganized or mineral matter, as yet incapable of forming a part of the living structure. Its conversion into organized matter constitutes the process of 344. Assimilation, or what, from an analogy with animal life, is usually termed Vegetable Digestion. To undergo this important change, the crude sap is attracted into the leaves, or other green parts of the plant, which constitute the apparatus of assimilation, where it is exposed to the light of the sun, under which influence alone can this change be effected. Under the influence of solar light, the fabric is itself constructed, and the chlorophyll, or green f ASSIMILATION. 191 matter of plants, upon which, or in connection with which, the light exerts its wonderful action, is first developed. When plants are made to grow in insufficient light, as when potatoes throw out shoots in cellars, this green matter is not formed. When light is with- drawn, it is soon decomposed; as we see when Celery is blanched by heaping the soil around its stems. So, also, the naturally green- less leaves of plants parasitic upon the roots or stems of other species (152) have no direct power of assimilation, but feed upon and grow at the expense of already assimilated matter. But all green parts, such as the cellular outer bark of most herbs, act upon the sap in the same manner as leaves, even supplying their places in plants which produce few or no leaves, as in the Cactus, &c. Under the influence of light, an essential preliminary step in vegetable digestion is accomplished, namely, the concentration of the crude sap by the evaporation or exhalation of the now superfluous water, the mechan- ism and consequences of which have already been considered (313). 345. We have now to consider the further agency of light in vege- table digestion itself, namely, its action in the leaf upon the concen- trated sap. Here it accomplishes two unparalleled results, which es- sentially characterize vegetation, and upon which all organized exist- ence absolutely depends (1,16). These are, — Ist. The chemical © decomposition of one or more of the substances in the sap which contain oxygen gas, and the liberation of this oxygen at the ordi- nary temperature of the air. The chemist can liberate oxygen gas from its compounds only by powerful reagents, or by great heat. 2d. The transformation of this mineral, inorganic food into organte matter, —the organized substance of living plants, and consequently of animals. These two operations, although separately stated, are in fact but different aspects of one great process. We contemplate the first, when we consider what the plant gives back to the air; the second, when we inquire what it retains as the materials of its own growth. The concentrated sap is decomposed ; the portion not required in the growth of the plant is returned to the air; and the remaining elements are at the same time rearranged, so as to form peculiar organic products. 346. The principal material given back to the air, in this pro- cess, is oxygen gas,* that element of our atmosphere which alone * A small proportion of nitrogen gas is likewise almost constantly exhaled from the leaves ; but this appears to come from the nitrogen which the water on 192 THE FOOD AND NUTRITION OF PLANTS. renders it fit for the breathing and life of animals. That the foliage of plants in sunshine is continually yielding oxygen gas to the sur- rounding air has been familiarly known since the days of Ingenhouss and Priestley, and may at any moment be verified by simple experi- ment. The readiest way is, to expose a few freshly gathered leaves to the sunshine in a glass vessel filled with water, and to collect the air-bubbles which presently arise while the light falls upon them, but which cease to appear when placed in shadow. This air, when examined, proves to be free oxygen gas. In nature, diffused day- light produces this effect ; but in our experiments, direct sunshine is generally necessary to show it. What is the source of this oxygen gas, which is given up to the air just in proportion to the vigor of assimilation in the leafy plant, or, in other words, to the consumption of crude sap? 347. This will be manifest on comparing the materials with the general products of vegetation, — what the plant takes as its food, with what it makes of it, in growth. Suppose the plant is assimi- lating its food immediately into its fabric, viz. into Cellulose, or the substance of which its tissue consists (27). This matter, when in a - pure state, and free from incrusting materials, has a perfectly uni- ‘form composition in all plants. It is composed of carbon, hydrogen, and oxygen, the latter two existing in the same proportions as in water.* It may therefore be said to consist of carbon and the ele- ments of water. These materials are necessarily furnished by the plant’s food. The mineral food of the plant, from which its fabric is made (829), is carbonic acid and water. If this be decomposed in vegetation, and the carbonic acid give up its oxygen, carbon and the elements of water remain, —the very composition of cellulose or vegetable tissue. Doubtless, then, the oxygen which is rendered to the air in vegetation comes from the carbonic acid which the plant took from the air (828). 348. This view may be confirmed by direct experiment. We imbibed by the roots had absorbed from the air (326), and which passes off un- altered from the leaves when this water is evaporated, or from nitrogen in the air which the rootlets directly absorb. In the course of vegetation, no more nitrogen is given out than what is thus taken in, and probably not so much. So that the exhalation of nitrogen may be left out of the general view of the changes which are brought about in vegetation. * Cellulose is chemically composed of 12 equivalents of Carbon, 10 of Hy- drogen, and 10 of Oxygen, viz. Ciz, Hio, O10. ASSIMILATION, 193 have seen that many plants must, and all may, imbibe the whole or { a part of their food directly from the air into their leaves (330). All leafy plants evidently obtain a part of their carbonic acid in this way. It is accordingly found, that. when a current of carbonic acid is made slowly to traverse a glass globe containing a leafy plant ex- posed to full sunshine, some carbonic acid disappears, and an equal bulk of oxygen gas supplies its place. Now, since carbonic acid gas contains just its own bulk of oxygen, it is evident that what has thus been decomposed in the leaves has returned all its oxygen to the air. Plants ‘take carbonic acid from the atmosphere, therefore (directly or indirectly) ; they retain its carbon; they give back its oxygen.* 349. But cellulose, being the final, insoluble product of vegetation appropriated as tissue, can hardly be directly formed in the first in- stance. The substances from which it must originate, and which actually abound in the elaborated sap, are Dextrine or Vegetable Mucilage (79, 83), Sugar (80), &c. The first of these is probably directly produced in assimilation. Its chemical composition is the same as that of pure cellulose: it consists, not only of the same three elements, but of the same elements in exactly the same pro- portion. Dextrine, vegetable mucilage, &c. are the primary, as yet unappropriated materials of vegetable tissue, or unsolidified cellu- lose, and their production from the crude sap is attended with the evolution of the oxygen which was contained in the carbonic acid of the plant’s food, as already stated. Nor would the result in any respect be altered if Starch were directly produced. This substance is merely dextrine, which, instead of being immediately appropriated in growth, is condensed into solid grains, and in that compact and * At least, the result is as 7f the oxygen exhaled were all thus detached from the carbon of the carbonic acid. Just this amount is liberated, and the facts obviously point to the carbonic acid as its real source. But, on the other hand, it appears unlikely that a substance which holds oxygen with such strong affinity as carbon should yield the whole of it under these circumstances : and water is certainly decomposed, with the evolution of oxygen, in the formation of a class of vegetable products soon to be mentioned ; besides, Edwards and Colin have shown that water is directly decomposed during germination. Still, as no one supposes that the residue after the liberation of oxygen is carbon and water, but only the three elements in the proportions which would constitute them, it amounts to nearly the same thing whether we say that the oxygen of the carbonic acid, or an amount of oxygen equivalent to that of the carbonic acid, der ived anes from it and partly from the water, is liberated in such cases. Ry Bs 17 194 THE FOOD AND NUTRITION OF PLANTS. temporarily insoluble form accumulated as the ready prepared ma- terials of future growth (82). Notwithstanding the difference in their properties and chemical reactions, these and other general ternary products (79) are strictly tsomeric ; that is, they consist of the same elements, combined in the same proportions; and physi- ‘ologically they are merely different states of one and the same thing. Dextrine is the most soluble state, and is probably that originally formed in assimilation in the foliage: starch, amyloid (83), &c. are temporarily solidified states; and cellulose is the ultimate and usu- ally permanent insoluble condition. Accordingly, whenever the ma- terials of growth are supplied from accumulations of nourishment, as especially from the seed in germination, (123 — 125), from fleshy . roots (145), rootstocks, tubers, &c. (188~194), the starch or ita equivalent is dissolved in the sap, being spontaneously reconverted, : into dextrine and sugar, and attracted in a liquid state into the)! growing parts, where, transformed into cellulose, it becomes a por- tion of the permanent vegetable fabric. 350. If, however, we suppose sugar to be a direct product of the assimilation of carbonic acid and water, the amount of oxygen gas exhaled will be just the same as before. For this has the same elementary composition as dextrine, starch, and cellulose, with the addition of one or two equivalents of water according to the kind.* And when formed as a transformation of dextrine, then the latter has only to appropriate some water. In the origination of all these products, therefore, the same quantity of carbonic acid is consumed, and all its oxygen restored to the air.t It is more and more evident, * The formula for cane-sugar is C12, Hu, O11; for grape-sugar, Ci2, Hie, Ore. + Since all these neutral ternary substances are identical, or nearly so, in ele- mentary composition, and since, with the same amount of carbon, derived from the decomposition of carbonic acid, the plant can form them all, it will no longer appear surprising that they should be so readily convertible into each other in the living plant, and even in the hands of the chemist. But the chemistry of organic nature exceeds the resources of science, and constantly produces trans- formations which the chemist in his laboratory is unable to effect. The latter can change starch into dextrine, and dextrine into sugar ; but he cannot reverse the process, and convert sugar into dextrine, or dextrine into starch. In the plant, however, all these various transformations are continually taking place. Thus, the starch deposited in the seed of the Sugar-canc, Indian Corn, &e. is changed into sugar in germination; and the sugar which fills the tissue of the stem at the time of flowering is rapidly carried into the flowers, where a portion is transformed into starch and again deposited in the newly-formed seeds. And ASSIMILATION. 195 therefore, that, by just so much as plants grow, they take carbonic acid from the air, they retain its carbon, and return its oxygen. 351. In the production of that modification of cellulose called ’ Lignine (42), which abounds in wood (if this be really a simple product, and not a mixture), not only must a larger amount of car- bonic acid be decomposed, but a small portion of water also, with - the liberation of its oxygen. For the composition attributed to it shows that it contains less oxygen than would suffice to convert its, hydrogen into water.* 352. The whole class of fatty substances, including the Ocls, Wax, Chlorophyll (84, 88, 92), &e., contain, some of them no oxygen at all (such as caoutchouc and Pine-oil), and all of them less, oxygen than is requisite to convert their hydrogen into water. In their direct formation, if this be supposed, not only all the oxygen of the carbonic acid has been given out, but also a portion belonging to the water. If formed by a further deoxidation of neutral ternary pro- ducts, the same result is attained as respects the liberation of oxy- gen gas, but by two or more steps instead of one. The Resins, doubtless, are not direct vegetable products, but originate from the alternation and partial oxidation of the essential oils. Balsams, which exude from the bark of certain plants, are natural solutions of resins in their essential oils, as rosin, or Pine-resin, in the oil of tur- pentine. 853. An opposite class, the Vegetable Acids (86), contain more oxygen than is necessary for the conversion of their hydrogen into water, but less than the amount which exists in carbonic acid and water. Indeed, the most general vegetable acid, the oxalic (which may be formed artificially by the action of nitric acid on starch), has no hydrogen, except in the atom of water that is connected with it. Acids are sometimes formed in the leaves, as in the Sorrel, the although the chemist is unable to transform starch, sugar, &c. into cellulose, yet he readily effects the opposite change, by reconverting woody fibre, &c. (under the influence of sulphuric acid) into dextrine and sugar. The plant does the same thing in the ripening of fruits, during which a portion of tissue is often transformed into sugar. Starch-grains and cellulose can never be formed arti- ficially, because they are not merely organizable matter, but have an organic structure. * According to Payen, lignine, separated as much as possible from cellulose, consists of Carbon 53.8, Hydrogen 6.0, and Oxygen 40.2 per cent, = Css, Ha, Oxy. 196 THE FOOD AND NUTRITION OF PLANTS. Grape-vine, &c., but usually in the fruit. If produced directly from the sap, as they may be in acid leaves, only a part of the oxygen in the carbonic acid which contributes to their formation would be ex- haled. But if formed from sugar, or any other of the general pro- ducts of the proper juice, the absorption of a portion of oxygen from the air would be required for the conversion; and this absorption takes place (at least in some cases) when fruits acquire their acidity. Even their formation by the plant, therefore, is attended by the lib- eration of oxygen gas, though in less quantity than in ordinary vege- tation. 354. There is still another class of vegetable products of uni- versal occurrence, and, although comparatively small in quantity in plants, yet of as high importance as those which constitute their permanent fabric; namely, the neutral quaternary organic com- pounds, of which nitrogen is a constituent (79). These, also, are mutually convertible bodies, related to each other as dextrine and sugar are to starch and cellulose, and playing the same part in the animal economy that the neutral ternary products do in the vege- table, i. e. forming the fabric of animals. The basis or type of these azotized products has received the name of Proteine (27): hence they are sometimes collectively called proteine compounds. In their production from the plant’s food, the ammonia, or other azotized matter it contains, plays an essential part; and oxygen gas is restored to the air from the decomposition of all the carbonic acid concerned and of a part of the water.* 355. In living cells the proteine forms the protoplasm, or vitally active lining, which may be said to give origin to the vegetable structure, since the cellulose is deposited under its influence to form the permanent walls or fabric of the cells, as has already been explained (26-36). When the cells have completed their growth * The chemical changes have been tabulated thus : — The materials : From which are formed the product : Cc HN. O. Cc. H. N. O. 74 of Water, 74 74 lof Proteine, 48 386 6 14 94 of Carbonic acid, 94 188 4 of Cellulose, 48 40 40 2of Carbonate of | =: 212 of Oxygen lib- ammonia, 2 2 6 4 erated, 212 96 76 6 266 96 76 6 266 Besides, proteine either contains or is naturally combined with a small quan- tity of sulphur and phosphorus (10). ASSIMILATION. 197 and transformation, the protoplasm abandons them, the portion which is not decomposed being constantly attracted onwards into forming and growing parts, where it incites new development. For this azotized matter has the remarkable peculiarity of inducing chemical changes in other organic products, especially.the neutral ternary bodies, causing one kind to be transformed into another, or even the decomposition of a part into alcohol, acetic acid, and finally into carbonic acid and water (as in germination, &c.),— itself remaining the while essentially unaltered. 356. The constant attraction of the protoplasm from the com- pleted into the forming parts of the plants explains how it is, that so small a percentage of azotized matter should be capable of playing such an all-important part in the vegetable economy. It does its work with little loss of material, and no portion of it is fixed in the tissues. At least, the little that remains in old parts is capa- ble of being washed out, showing that it forms no integral part of the fabric. This explains why the heartwood of trees yields barely a trace of nitrogen, while the sap-wood yields an appreciable amount, and the cambium-layer and all parts of recent formation, such as the buds, young shoots, and rootlets, always contain a notable proportion of it. This gives the reason, also, why sap-wood is so liable to decay (induced by the proteine), the more so in proportion to its newness and the quantity of sap it contains, while the completed heart-wood is so durable. The azotized matter rapidly diminishes in the stem and herbage during flowering, while it accumulates in the forming fruit, and is finally condensed in the seeds (which have a larger per- centage than any other organ), ready to subserve the same office in the development of the embryo plant it contains.* 357. When wheat-flour, kneaded into dough, is subjected to the prolonged action of water, the starch is washed away, and a tena- cious, elastic residue, the Gluten of the flour, which gives it the capability of being raised, remains. This contains nearly all the proteine compounds of the seed, mixed with some fatty matters (which may be removed by alcohol and ether) and with a little cellulose. The azotized products constitute from eight to thirty per cent of the weight of wheat-flour: the proportion varies greatly * The cotyledons of peas and beans, according to Mr. Rigg, contain from 100 to 140 parts, and the plumule about 200 parts, of nitrogen, to 1,000 parts of carbon. 17* 198 THE FOOD AND NUTRITION OF PLANTS. under different circumstances, but it is always largest when the soil is well supplied with manures that abound in nitrogen. The gluten of wheat is a mixture of four isomeric quaternary products, distin- guished by chemists under the names Fibrine (identical in nature with that which forms the muscles of animals), Albumen (of the same nature as animal albumen), Case¢ne (identical with the curd of milk), and Glutine. Jn beans and all kinds of pulse, or seeds of Legu- minous plants, the azotized matter principally occurs in the form of Legumine, which is nearly intermediate in character between albu- men and caseine. 358. Comparing now these principal products of assimilation in plants with the inorganic materials from which they must needs be formed, it may clearly be perceived that the principal result of vege- tation, as concerns the atmosphere, from which plants draw their food, consists in the withdrawal of water, of a little ammonia, and of a large proportion of carbonic acid, and of the restoration of oxygen. The latter is a constant effect of vegetation and the measure of its amount. As respects the fabric of the plant, the sole consequences of its formation upon the air are the withdrawal of a small quantity of water, and of a large amount of carbonic acid gas, and the resto- ration of the oxygen of the latter. In the formation of its azotized materials, a portion of ammonia or of some equivalent compound of nitrogen is also withdrawn. It is true, indeed, that leaves decom- pose carbonic acid only in daylight ; and that they sometimes give a quantity of carbonic acid to the air in the night, especially when vegetation languishes, or even take from it a little oxygen. But this does not affect the general result, nor require any qualification of the general statement. The work simply ceases when light is withdrawn. The plant is then merely in a passive state. Yet, whenever exhalation from the leaves slowly continues in darkness, the carbonic acid which the water holds necessarily flies off with it, during the interruption to vegetation, into the atmosphere from which the plant took it. So much of the crude sap, or raw mate- rial, merely runs to waste. Furthermore, it must be remembered that the decomposition of carbonic acid in vegetation is in direct op- position to ordinary chemical affinity ; or, in other words, that all organized matter is in a state corresponding to that of unstable equilibrium. Consequently, when light is withdrawn, ordinary chemical forces may perhaps to some extent resume their sway, the oxygen of the air combine with some of the newly deposited carbon INFLUENCE OF VEGETATION ON THE ATMOSPHERE. 199 to reproduce a little carbonic acid, and thus demolish a portion of the rising vegetable structure which the setting sun left, as it were, in an unfinished or unstable state. This is what actually takes place in a dead plant at all times, and whenever an herb is kept in pro- longed darkness ; chemical forces, exerting their power uncontrolled, demolish the whole vegetable fabric, beginning with the chlorophyll (as we observe in blanching Celery), and at length resolve it into the carbonic acid and water from which it was formed. But this must all be placed to the account of decomposing, not of growing vegetation ; and even if it were a universal phenomenon, which is by no means the case,* would not affect the general statement, that, by so much as plants grow, they decompose carbonic acid and give its oxygen to the air; or, in other words, purify the air. 359. Every six pounds of carbon in existing plants have withdrawn twenty-two pounds of carbonic acid gas from the atmosphere, and replaced it with sixteen pounds of oxygen gas, occupying the same bulk. To form some general conception of the extent of the influ- ence of vegetation upon the air we breathe, therefore, we should compute the quantity of carbon, or charcoal, that is contained in the * Tt is stated that many ordinary plants, when in full health and vigorous vegetation, impart no carbonic acid to the air during the night. — See Pepys, in Philosophical Transactions, for 1843.— Plants deteriorate the air only in their \ decay, and in peculiar processes, distinct from vegetation and directly the re- verse of assimilation; as in germination, for instance, where the proteine in- duces the decomposition of a portion of the store of assimilated matter, in order that the rest may be brought into a serviceable condition. The evolution of carbonic acid by plants, therefore, when it occurs, is no part of vegetation. And it is by a false analogy that this loss which plants sustain in the night has been dignified with the name of vegetable respiration, and vegetables said to vitiate the atmosphere, just like animals, by their respiration, while they purify it by their digestion. If, indeed, this were a constant function, in any way contributing to maintain the life and health of the plant, it might be properly enough compared with the respiration of animals, which is itself a decomposing operation. But this is not the case. And herein is a characteristic difference between vegetables and animals: the tissues of the latter require constant interstitial renewal by nutrition, new particles replacing the old, which are removed and restored to the mineral world by respiration: while in plants there is no such renewal, but the fabric, once completed, remains unchanged, ceases to be nourished, and conse- quently soon loses its vitality; while new parts are continually formed farther on to take their places, to be in turn abandoned. Plants, therefore, having no : decomposition and recomposition of any completed fabric, cannot properly be said to have the function of respiration. 200 THE FOOD AND NUTRITION OF PLANTS. forests and herbage of the world, and add to the estimate all that exists in the soil, as vegetable mould, peat, and in other forms; all that is locked up in the vast deposits of coal (the product of the vegetation of bygone ages); and, finally, all that pertains to the whole existent animal kingdom ;— and we shall have the aggregate amount of a single, though the largest, element which vegetation has withdrawn from the atmosphere. By multiplying this vast amount of carbon by sixteen, and dividing it by six, we obtain an expression of the number of pounds of oxygen gas that have in this process been supplied to the atmosphere. 360. Rightly to understand the object and consequences of this immense operation, which has been going on ever since vegetation began, it should be noted, that, so far as we know, vegetation is the only operation in nature which gives to the air free oxygen gas, that indispensable requisite to animal life. There is no other pro- vision for maintaining the supply. The prevailing chemical ten- dencies, on the contrary, take oxygen from the air. Few of the materials of the earth’s crust are saturated with it; some of them still absorb a portion from the air in the changes they undergo; and none of them give it back in the free state in which they took it,—in a state to support animal life,—by any known natural process, at least upon any considerable scale. Animals all con- sume oxygen at every moment of their life, giving to the air carbonic acid in its room; and when dead, their bodies consume a further por- tion in decomposition. Decomposing vegetable matter produces the same result. Its carbon, taking oxygen from the air, is likewise restored in the form of carbonic acid. Combustion, as in burning our fuel, amounts to precisely the same thing; it is merely rapid decay. The carbon which the trees of the forest have been for centuries gathering from the air, their prostrate decaying trunks may almost as slowly restore to the air, in the original form of carbonic acid. But if set on fire, the same result may be accom- plished in a day. All these causes conspire to rob the air of its life-sustaining oxygen. The original supply is indeed so vast, that, were there no natural compensation, centuries upon centuries would elapse before the amount of oxygen could be so much reduced, or that of carbonic acid increased, as to affect the existence of the present races of animals. But such a period would eventually arrive, were there no natural provision for the decomposition of the carbonic acid constantly poured into the air from these various RELATIONS OF THE VEGETABLE AND ANIMAL KINGDOMS. 201 sources, and for the restoration of its oxygen. The needful com- pensation is found in the vegetable kingdom. ‘While animals con- sume the oxygen of the air, and give back carbonic acid which is injurious to their life, this carbonic acid is the principal element of the food of vegetables, is consumed and decomposed by them, and its oxygen restored for the use of animals. Hence the perfect adap- tation of the two great kingdoms of living beings to each other ;— each removing from the atmosphere what would be noxious to the other ;—each yielding to the atmosphere what is essential to the continued existence of the other.* 861. The relations of simple vegetation, under this aspect, to the mineral kingdom on the one hand, and the animal kingdom on the other, are simply set forth in the first part of the diagram placed at the close of this chapter. 362. But, besides this remotely essential office in purifying the air, the vegetable kingdom renders to the animal another service so immediate, that its failure for a single year would nearly depop- ulate the earth; namely, in providing the necessary food for the whole animal kingdom. It is under this view that the great office of vegetation in the general economy of the world is to be contem- plated. Plants are the sole producers of nourishment. They alone transform mineral, chiefly atmospheric materials, they condense air, into organized matter. While they thus produce upon a vast scale, they consume or destroy comparatively little; and this never in proper vegetation, but in some special processes hereafter to be con- sidered (370). Often when they appear to consume their own pro- ducts, they only transform and transfer them, as when the starch of the potato is converted into new shoots and foliage. 863. Animals consume what vegetables produce. They them- selves produce nothing directly from the mineral world. The herbivorous animals take from vegetables the organized matter which they have produced;—a part of it they consume, and in respiration restore the materials to the atmosphere, from which * It is plain, however, that, while the animal kingdom is entirely dependent on the vegetable, the latter is independent of the former, and might have existed alone. The decaying races of plants, giving back their carbon to the air and to the soil by decay, would furnish food for their successors. And since all the carbonic acid which animals render to the air in respiration they have derived from their vegetable food, this would in time have found its way back to the air, for the use of new generations of plants, without the intervention of animals. At most, they merely expedite its return. 202 THE FOOD AND NUTRITION OF PLANTS. plants derived them, in the very form in which they were taken, namely, as carbonic acid and water. The portion they accumulate in their tissues constitutes the food of carnivorous animals; who consume and return to the air the greater part during life, and the remainder in decay after death. The atmosphere, therefore, out of which plants create nourishment, and to which animals as they con- sume return it, forms the necessary link between the animal and vegetable kingdoms, and completes the great cycle of organic exist- ence. Organized matter passes through various stages in vege- tables, through others in the herbivorous animals, and undergoes its final transformations in the carnivorous animals. Portions are con- sumed at every stage, and restored to the mineral kingdom, to which the whole, having accomplished its revolution, finally returns. 3864. Moreover, plants not only furnish all the materials of the animal fabric, but furnish each principal constituent ready formed, so. that the animal has only to appropriate it. The food of animals is of two kinds ;— 1. that which serves to support respiration and maintain the animal heat; 2. that which is capable of forming a portion of the animal fabric, of its flesh and bones. The ternary vegetable products furnish the first, in the form of sugar, vegetable jelly, starch, oil, &c., and even cellulose; substances which, contain- ing no nitrogen, cannot form an integral part of the animal frame, ‘but, conveyed into the blood, are decomposed in respiration; the carbon and the excess of hydrogen combining with the oxygen of the air, to which they are restored in the form of carbonic acid and water. Any portion not required by the immediate demands of res- piration is stored in the tissues in the form of fat, (which the animal may either accumulate directly from the oily and waxy matters in its vegetable food, or produce by an alteration of the starch and sugar,) as a provision for future use: a deficiency of such materials subjects the tissues themselves, or the proper supporting food, to im- mediate decomposition in respiration. The quaternary or azotized products furnish the proper materials of the animal frame, the fibrine, caseine, albumen, &c. being directly appropriated from the vegetable food to form the blood, muscles, &c.; while a slight trans- formation of them gives origin to gelatine, of which the sinews, carti- lages, and the organic part of the bones, consist. The earthy por- tion of the bones, the iron in the blood, and the saline ingredients of the animal body, are drawn from the earthy constituents (336) of the plants upon which the animal feeds. The animal merely ap- 203 RELATIONS OF THE THREE KINGDOMS OF NATURE. ble materials, ganizal tes and accumulates these already or changing them, it may be, little by little, as he destroys them, but rendering them all back (those of the first class through the lungs, propria’ of the second through the kidneys) finally to the earth and air, from hich, the vegetable took them. 365. The general relations of vegetation to the mineral and ani- jon in w which, and in the condit oined diagram. y b, mal kingdoms are exhibited in the su ‘aIOW { NaDXxO oR 8 see Pe er ‘+ Ngoax0 aIov OINOTUVO ( Nosavy ore a pue waomury Jo 08 Nowayp Noauvg DINO@UVO aoqiey 07 paajosar AT[eUg NIOAXO| PUB ‘vag se pournyer — ‘07 NUOAXO NIDXXO i “UG AA ngp0udaq| (pang) eurest spine TINTED pus enjojorg = 4} AH napouasy § UELVAL (smoutg) ouryE[ay - NIDOULIN ‘(aposnyq]) OULIqQL yy NADOULIN]| NIDOULIN, VINOANY } xsoouasH ‘neunq[y Nasouasyy] — Na00uaAyy VINONWY ‘uoynjabay aaduog ‘TT *aIoV NIOXIKO . . . . . . eo. . . oe eo. . eo. eo. . . oe . . NIDIXO : aiov 0} UIA ‘are 0g} 03 poeudnjzel UOTE] ‘ ‘ 4 Napoudx |” HB -ng ‘qorezg ‘asornype9 NIDOUCATT gee: amv | naoxxo| 108 UE Pus sreutae Aq poutnsao) NID1x0 Napsxo $ UDLVAL ‘omgng aqopebe, " ‘NOGONTY IVESNIPL ‘HOGONIY TVNINY ‘WOGDNIY TIAVIGNTA ‘KOGDNIY, TVWINITY ‘TUNLVN JO SWOGONIY FUT, AHL JO SNOILVTIRY TVOLO, FHL ONILVALSATI KVUOVIG. 204 FLOWERING AND ITS CONSEQUENCES. CHAPTER VII. OF FLOWERING AND ITS CONSEQUENCES. 366. Prants have thus far been considered only as respects their Organs of Vegetation, — those which essentially constitute the vegetable being, by which it grows, deriving its support from the surrounding air and soil, and converting these inorganic mate- Tials into its own organized substance. As every additional supply of nourishment furnishes materials for the development of new branches, roots, and leaves, thus multiplying both those organs which receive food and those which assimilate it, it would seem that, apart from accidents, the increase and extension of plants would be limited only by the failure of an adequate supply of nourishment. After a certain period, however, varying in different species, but nearly con- stant in each, a change ensues, which controls this otherwise indefi- nite extent of the branches. A portion of the buds, instead of elon- gating into branches, are developed in the form of FLowers ; and nourishment which would otherwise contribute to the general in- crease of the plant, is devoted to their production, and to the matu- ration of the frudt and seeds. 367. Flowering an Exhaustive Process, Plants begin to bear flowers at a nearly determinate period for each species ; which is dependent partly upon constitutional causes, and partly upon the requisite sup- ply of nutritive matter in their system. For, since the flower and fruit draw largely upon the powers and nourishment of the plant, while they yield nothing in return, fructification is an exhaustive process, and a due accumulation of food is requisite to sustain it.* * When the branch of a fruit-tree, which is sterile or does not perfect its blos- soms, is ringed or girdled (by the removal of » narrow ring of bark), the elab- orated juices, being arrested in their downward course, are accumulated in the branch, which is thus enabled to produce fruit abundantly ; while the shoots that appear below the ring, being fed by the much weaker ascending sap, do not blossom, but push forth into leafy branches. So the flowers of most trees and shrubs that bear large or fleshy fruit are produced from lateral buds, resting directly upon the wood of the previous year, in which a quantity of nutritive matter is deposited. So, also, a seedling shoot, which would not flower for several years if Jeft to itself, blossoms the next season when inserted as a graft into an older trunk, from whose accumulated stock it draws. FLOWERING AN EXHAUSTIVE PROCESS. 205 Annuals flower in a few weeks or months after they spring from the seed, when they have little nourishment stored up in their tissue ; and their lives are destroyed by the process (144): biennials flower after a longer period, rapidly exhausting the nourishment accumu- lated in the root during the previous season, and then perishing (145); while shrubs and trees do not commence flowering until they are sufficiently established to endure it. The exhaustion con- sequent upon flowering, however, is often exhibited in fruit-trees, | which, after producing an excessive crop (especially of late fruits, , such as apples), sometimes fail to bear the succeeding year. When the crop of one year fails, the nourishment which it would have ap- propriated accumulates, and the tree may bear more abundantly the following season, and so on alternately from year to year. 368. The actual consumption of nourishment in flowering may be shown in a variety of ways; as by the rapid disappearance of the farinaceous or saccharine store in the roots of the Carrot, Beet, &c. when they begin to flower, leaving them light, dry, and empty; and by the rapid diminution of the sugar in the stalks of the Sugar- cane and of Maize at the same period. The stalks are therefore’ cut for making sugar just before the flowers expand, when they | contain the greatest amount of saccharine matter. 369. The consequences of this exhaustion upon the duration of plants are further illustrated by the facility with which annuals may be changed into biennials, or their life prolonged indefinitely by preventing their flowering ; while they perish whenever they bear flowers and seed, whether during the first or any succeeding year.. Thus, a common annual Larkspur has given rise to a double-flowered variety in the gardens, which bears no seed, and has therefore be- come a perennial. Cabbage-stumps, which are planted for seed, may be made to bear heads the second year by destroying the flower- shoots as they arise ; and the process may be continued from year to year, thus converting a biennial into a kind of perennial plant. The effect of flowering upon the longevity of the individual is strikingly shown by the Agave, or Century-plant,—so called because it flow- ers in our conservatories only after the lapse of a hundred, or at least a great number of years ; although, in its native sultry climate, it generally flowers when five or six years old. But whenever this occurs, the sweet juice with which it is filled at the time (which by fermentation forms pulque, the inebriating drink of the Mexicans) is consumed at a rate answering to the astonishing rapidity with which 18 206 FLOWERING AND ITS CONSEQUENCES. its huge flower-stalk shoots forth (24), and the whole plant inevita- bly perishes when the seeds have ripened. So, also, the Corypha, or Talipot-tree, a magnificent Oriental Palm, which lives to a great age and attains an imposing altitude (bearing a crown of leaves, each blade of which is often thirty feet in circumference), flowers only once ; but it then bears an enormous number of blossoms, suc- ceeded by a crop of nuts sufficient to supply a large district with seed ; and the tree perishes from the exhaustion. 370. Flowering and fruiting, then, draw largely upon the plant’s resources, while they give back nothing in return. In these opera- tions, as also in germination, vegetables act as true consumers (like animals, 363), decomposing their own products, and giving back carbonic acid and water to the air, instead of taking these materials from the air. It is in flowering that they actually consume most. In fruiting, although a large quantity of nourishment is taken from the plants, this is mostly accumulated in the fruit and seed, in a con- centrated form, for the future use of the new individual in the seed. 371. The real consumption of nourishment by the flower is shown by the action of flowers upon the air, so different from that of leaves. While the foliage withdraws carbonic acid from the air, and re- stores oxygen (846, 358), flowers take a small portion of oxygen from the air, and give back carbonic acid. While leaves, therefore, purify the air we breathe, flowers contaminate it; though, of course, only to a degree which is relatively and absolutely insignificant. This process is necessarily attended by the 872. Evolution of Heat, When carbon is consumed as fuel, and by the oxygen of the air converted into carbonic acid, an amount of heat is evolved directly proportionate to the quantity of carbon consumed, or of carbonic acid produced. Precisely the same amount is more slowly generated during the gradual decomposition of the same quantity of vegetable matter by decay, —a heat which is employed by the gardener when he makes hot-beds of tan, decay- ing leaves, and manure,—or by the breathing of animals, which maintains their elevated temperature (364). The conversion of a given amount of carbon and hydrogen into carbonic acid and water, under whatever circumstances it may take place, and whether slowly or rapidly, generates in all cases the very same amount of heat. Now, since flowers consume carbon and produce carbonic acid, acting in this respect like animals, they ought to evolve heat in proportion to that consumption. This, in fact, they do. The evolution of heat EVOLUTION OF HEAT. 207 in blossoming was first observed by Lamarck, about seventy years ago, in the European Arum, which, just as the flowers open, “ grows hot, as if it were about to burn.” It was afterwards shown by Saus- } sure in a number of flowers, such as those of the Bignonia, Gourd, and Tuberose, and the heat was shown to be in direct proportion to the consumption of the oxygen of the air, or, in other words, of the carbon of the plant. The increase of temperature, in these cases, was measured by common instruments. But now that thermo-elec- tric apparatus affords the means of measuring variations inappre- ciable by the most delicate thermometer, the heat generated by an ordinary cluster of blossoms may be detected. The phenomenon is most striking in the case of some large tropical plants of the Arum family, where an immense number of blossoms are crowded together and muffled by a hooded leaf, or spathe (390), which confines and rever- berates the heat. In some of these, the temperature rises at times to twenty or even fifty degrees (Fahrenheit) above that of the sur- rounding air. This increase of temperature occurs daily, from the time the flowers open until they fade, but is most striking during the shedding of the pollen. At night, the temperature falls nearly to that of the surrounding air; but in the course of the morning the heat comes on, as it were like a paroxysm of fever, attaining the maximum, day after day, very nearly at the same hour of the after- noon, and gradually declining towards evening. In ordinary cases, the heat of flowering is more than counterbalanced by the vaporiza- tion of the sap and the absorption of solar heat by the foliage; so that the actual temperature of a leafy plant in summer is lower than that of the atmosphere. 873. We have remarked that the principal consumption takes place in the flower ; and that a store is laid up in the fruit and seed. But much even of this store is consumed when the seed germinates ; and in germination, as is seen in the malting of barley, a large amount of organic matter is decomposed into carbonic acid and water, and a proportionate quantity of heat is evolved. By a not very violent metaphor it may be said, therefore, that the fabled Phoe- nix is realized in the Century-plant (369), which, after living a hun- dred years, consumes itself in producing and giving life to its off- spring, who literally rise from its ashes. 374. Plants need a Season of Rest. When plants are in luxuriant growth, rapidly pushing forth leafy branches, they are not apt to produce flower-buds. Our fruit-trees, in very moist seasons, or 208 FLOWERING AND ITS CONSEQUENCES. when cultivated in too rich a soil, often grow luxuriantly, but do not blossom. The same thing is observed when our Northern fruit-trees are transported into tropical climates. On the other hand, whatever checks this continuous growth, without affecting the health of the individual, causes blossoms to appear earlier and more abundantly than they otherwise would. It is for this reason that transplanted fruit-trees incline to blossom the first season after their removal, though they may not do so again for several years. A state of com- parative rest seems needful to the transformation by which flowers are formed. It is in autumn, or at least after the vigorous vegeta- tion of the season is over, that our trees and shrubs, and most peren- nial herbs, form the flower-buds of the ensuing year. 375. The requisite annual season of repose, which in temperate climates is attained by the lowering of the temperature in autitea and winter, is scarcely less marked in many tropical countries, where winter is unknown. But the result is there brought about, not by cold, but by heat and dryness. The Cape of Good Hope, the Canary Islands, and the southern and interior parts of California, may be taken as illustrations. In the Canaries, the growing season is from November to March,—the winter of the northern hemi- sphere ;—— their winter also, as it is the coolest season, the mean temperature being 66° Fahr. But the rains fall regularly, and vegetation is active; while in summer, from April to October, it very seldom rains, and the mean temperature is as high as 73°. During this dry season, when the scorching sun reduces the soil nearly to the dryness and consistence of brick, ordinary vegetation almost completely disappears ; and the Fig-Marigolds, Euphorbias, and other succulent plants, which, fitted to this condition of things, alone remain green, not unaptly represent the Firs and other ever- greens of high northern latitudes. The dry heat there brings about the same state of vegetable repose as cold with us. The roots and bulbs then lie dormant beneath the sunburnt crust, just as they do in our frozen soil. When the rainy season sets in, and the crust is softened by moisture, they are excited into growth under a dimin- ished temperature, just as with us by heat; and the ready-formed flower-buds are suddenly developed, clothing at once the arid waste with a profusion of blossoms (194). The vegetation of such regions consists mainly of succulents, which are able to live through the drought and exposure; of bulbous plants, which run through their course before the drought becomes severe, then lose their THE INFLORESCENCE. 209 foliage, while the bud remains quiescent, safely protected under ground until the rainy season returns ; and of annuals, which make their whole growth in a few weeks, and ripen their seeds, in which state the species securely passes the arid season. 376. These considerations elucidate the process of forcing plants, and other operations of horticulture, by which we are enabled to obtain in winter the flowers and fruits of summer. The gardener accomplishes these results principally by skilful alterations of the natural period of repose. He gives the plant an artificial period of rest by dryness at the season when he cannot command cold, and then, by the influence of heat, light, and moisture, which he can always command, causes it to grow at a season when it would have been quiescent. Thus he retards or advances, at will, the periods of flowering and of rest, or in time completely inverts them. CHAPTER VIII. OF THE INFLORESCENCE. 377. Inflorescence is the term used to designate the arrangement of flowers upon the stem or branch. The flower, like the branch, is evolved from a bud. Flower-buds and leaf-buds are often so similar in appearance, that it is difficult to distinguish one from the other before their expansion. The most conspicuous parts of the flower are so obviously analogous to the leaves of a branch, that they are called in common language the leaves of the flower. Such a flower as the double Camellia appears as if composed of a rosette of white or colored leaves, resembling, except in their color and texture, the clusters of leaves which are crowded on the offsets of such plants as the Houseleek (Fig. 207). We therefore naturally regard a flower-bud as analogous to a leaf-bud; and a flower, con- sequently, as analogous to a short leafy branch. 378. This analogy is confirmed by the position which flowers oc- cupy. They appear at the same situations as ordinary buds, and at no other; that is, they occupy the extremity of the stem or branch, and the axil of the leaves (159, 165). Consequently, the arrange- 18 * 210 THE INFLORESCENCE. ment of the leaves governs the whole arrangement of the blossoms, as well as that of the branches. ‘The almost endless variety of modes in which flowers are clustered upon the stem, many of them exhibiting the most graceful of natural forms, all implicitly follow the general law which has controlled the whole development of the vege- table from the beginning. We have, throughout, merely buds termi- nating the stem and branches, and buds from the axil of the leaves. 379. The simplest kind of inflorescence is, of course, that of a solitary flower,—a sin- gle flower-stalk bearing a single flower; as in Fig. 806 and Fig. 327. The flower is solitary in both these instances ; but in the latter case it oc- cupies the summit of the stem, that is, it stands in the place of a terminal bud; in the former it arises from the axil of a leaf, or represents an axillary bud. These two cases exhibit, in their great- est simplicity, the two plans of inflorescence, to one or the other of which all flower-clusters belong. 380. We begin with the second of these plans; in which the flowers all spring from axillary buds; while the terminal bud, de- veloping as an ordinary branch, continues the stem or axis indefi- nitely. For the stem in such case may continue to elongate, and produce a flower in the axil of every leaf, until its powers are ex- hausted (Fig. 307). This gives rise, therefore, to what is called 381. Indefinite or Indeterminate Inflorescence. The primary axis is here never terminated by a flower; but the secondary axes (from axillary buds) are thus terminated. The various forms of indefi- nite inflorescence which in descriptive botany are distinguished by special names, as might be expected, run into one another through intermediate gradations. In nature they are not so absolutely fixed as in our written definitions ; and whether this or that name should be used in a particular case is often a matter of fancy. The sub- joined account of the principal kinds will at the same time bring to view the connection between them. 382. The principal kinds of indefinite inflorescence which have received distinctive names are the Raceme, the Corymb, the Umbel, the Sprke, the Head, the Spadix, the Cathin, and the Panicle. (FIG. 806. A flowering branch of Moneywort, Lysimachia nummularia. INDETERMINATE INFLORESCENCE. 211 883. Before illustrating these, one or two terms, of common oc- currence, may be defined. A flower which has no stalk to support it, but which sits directly on the stem or axis it proceeds from, is said to be sessile. If raised on a stalk, this is called its PepunciE. If the whole flower-cluster is raised on a stalk, this keeps the name of peduncle, or common pedunele (Fig. 307, p) ; and the stalk of each particular flower, if it have any, takes the name of PrpicrL or partial peduncle (p'). The portion of the general stalk along which flowers are disposed is called the azts of in- florescence, or, when covered with sessile flowers, the rhachis (backbone), and sometimes (as when thick and covered with crowded flowers) the receptacle. The leaves of a flower-cluster generally are termed Bractrs. But when we wish particularly to distin- guish their sorts, those on the peduncle, or main axis, and which have a flower in their axil, take the name of Bracts (Fig. 807, b); and those on the pedicels or partial flower-stalks, if any, that of Bracriets or Bracteousgs (6’). The bracts are often reduced to aminute size, so as to escape ordinary notice: they very frequently fall off when the flower-bud in their axil expands, or even earlier; and sometimes, as in the greater part of the Mustard family, they altogether fail to appear. 384. A Raceme (Fig. 307, 308, 315) is that form of flower-cluster in which the flowers, each on their own footstalk or pedicel, are arranged: along a common stalk or axis of infloresence; as in the Lily of the Valley, Currant, Choke-Cherry, Barberry, &c. The lowest blossoms of a raceme are of course the oldest, and therefore open first, and the order of blossoming is ascending, from the bot- tom to the top. The summit, never being stopped by a terminal flower, may go on to grow, and often does so (as in the Snowberry, Shepherd’s Purse, &c.), producing lateral flowers one after another throughout the season. In the raceme, the axis of inflorescence is more or less elongated, and the pedicels are about equal in length. 385. A Corymb (Fig. 309, 319) is the same as a raceme, except that the lower pedicels are elongated, so as to form a level-topped or slightly convex bunch of flowers ; as in the Hawthorn, &c. FIG. 807. A Raceme, with a general peduncle (p), pedicels (p’), bracts (5), and bractlets (b'). 212 THE INFLORESCENCE. 386. An Umbel (Fig. 810) differs from a corymb only in having all the pedicels arising from the same apparent point, so as to resem- ble the rays of an umbrella;—the general peduncle, in this case, bearing several flowers without any perceptible elongation of the axis of infloresence. The Primrose and the Milkweed afford familiar examples of the simple umbel. 387. A corymb being evidently the same as a raceme with a short main axis, and an umbel the same ‘as a corymb with a still shorter axis, it is evident that the outer flowers of an umbel or corymb correspond to the lowermost in the raceme, and that these will first expand, the blossoming pro- ceeding regularly from the base to the apex, or (which is the same thing) from the circumference to the centre. This mode of development uniformly takes place when the flowers arise from axil- lary buds; on which account the indefi- nite mode of inflorescence is also called the centripetal. 388. In all the foregoing cases, the flowers are raised on stalks, or pedicels. ‘When these are wanting, or so short as at not to be apparent, a Spike or Head is produced. 389. A Spike is the same as the raceme, except that the flowers are sessile ; as in the Plantain (Fig. 311) and Mullein. It is an in- FIG. 808, Araceme. 309. Acorymb. 310. An umbel. FIG. $11. Young spike of Plantago major. 812. Catkin of White Birch. INDETERMINATE INFLORESCENCE. 2138 determinate infloresence, with the primary axis elongated, and the flowers destitute of pedicels or with only very short ones. Two varieties of the spike have received independent names, viz. the Spadix and the Ament. 390. A Spadix is a fleshy spike enveloped by a large bract or mod- ified leaf, called a Sparue, as in Calla palustris (Fig. 313), the Indian Turnip (Fig. 314), and the Skunk Cabbage (Fig. 1205). 313 34 391. An Ament, or Catkin, is merely that kind of spike with scaly bracts borne by the Birch (Fig. 312), Poplar, Willow, and, as to one of the two sorts of flowers, by the Oak, Walnut, and Hickory, which are accordingly called amentaceous trees. Catkins usually fall off in one piece, after flowering or fruiting, especially sterile catkins. 392. The Head, or Capitulum, is a globular cluster of sessile flowers, like that of Clover, the Button-Bush (Fig. 320), and the balls of the Buttonwood or Plane-tree. It is a many-flowered centripetal in- florescence, in which neither the primary axis mor the secondary axes are at all lengthened. We may view it either as an umbel without any pedicels, or as a spike with a very short axis. Gen- erally it is of the latter character, as is evident in a Clover-head, where what was first a head frequently elongates into a spike as it grows older. FIG. 318, 314. Spadix of Calla and of Arum, with the spathe. 815. A raceme of Cherry. 817. A cyme. 818. Panicle of Meadow-Grass. 319. A corymb. 214 THE INFLORESCENCE. 393. The base both of the head and the umbel is frequently fur- nished with a number of imperfect leaves or bracts, crowded into a 320 32k 322 cluster or whorl, termed an InvotucrEr. The involucre assumes a great variety of forms ; sometimes resembling a calyx; and some- FIG. 320. Head of flowers of the Button-bush, Cephalanthus occidentalis. FIG. 821. Plant of Cornus Canadensis, with its four-leaved involucre around a cluster of small flowers. 322. A separate flower enlarged. FIG. 828. Flowering branch of Cichory, with two heads of ligulate flowers. INDETERMINATE INFLORESCENCE. 215 times (as in Cornus Florida, or the common Dogwood, and C. Cana- densis, Fig. 821) becoming petal-like, and much more showy than the blossom itself. Here it is at once distinguished from the calyx or corolla by its including a number of flowers. Sometimes, how- ever, as in the Mallow and Hibiscus, the involucre forms a kind of outer calyx to each flower. 394. The axis, or rhachis (882), of a head is called its Rrcep- TACLE. Frequently, instead of being globular or oblong, it is flat or depressed, and dilated horizontally, so as to allow a large number of flowers to stand on its level or merely convex surface; as in the Sun- flower, Aster, Marigold, Dandelion, and Cichory (Fig. 823). Here, as in Fig. 821, a set of bracts form an involucre, surrounding the dense head of flowers. And as the involucre considerably resembles a calyx, while the outer flowers, often of a peculiar sort, are readily mistaken for petals, the head in these and similar plants was called a compound flower by the older botanists. Fig. 324 rep- resents a section through a head of such flowers in a Co- reopsis; and Fig. 325is a slice of the same, more enlarged, displaying some of the sepa- rate flowers. In Coreopsis, as in the Sunflower, Yarrow, &c., each blossom of the head is subtended by its bract (6); and the bracts in such cases are called Palee or Chaff. 895. The Fie presents a case of very singular inflorescence FIG. 324. Vertical section of a head of flowers of a Coreopsis. FIG. 325. A slice of Fig. 824, more enlarged, with one tubular perfect flower (a) left stand- ing on the receptacle, and subtended by its bract or chaff (b); also one ligulate and neutral ray- flower (c), and part of another: d, section of bracts or leaves of the involucre. 216 THE INFLORESCENCE. (Fig. 590-592), where the flowers apparently occupy the inside instead of the outside of the axis, being enclosed within the fleshy receptacle, which is hollow and nearly closed at the top. So that while a Sunflower, or the like, is an inflorescence imitating a blos- som, a fig is an inflorescence imitating a fruit. Indeed, it is much like a mulberry (Fig. 593) or a pine-apple, turned inside out. 396. The foregoing are all forms of simple inflorescence; the ramification not passing beyond the first step; the lateral buds being at once terminated by a single flower. But the lateral flower- stalks may themselves branch, just as ordinary branches give rise to branchlets: then the inflorescence becomes compound. If the branches of a raceme are prolonged, and bear other flowers on pedi- cels similarly arranged, a compound raceme is produced ; or if the flowers are sessile, a compound spike is formed. A corymb, the branches of which are similarly divided, forms a compound corymb ; and an umbel, where the branches (often called rays) bear smaller umbels at their apex, is termed a compound um- bel ; as in the Caraway, Parsnip, and almost all the species of the family Umbelliferae, which is so named on this account. 397. For these secondary umbels, a good Eng- lish name has been employed by Dr. Darlington, that of Umbetiters. Their involucre, when they have any, is distinguished from that of the principal umbel by the name of InvoLucEL. 398. When the inflorescence is compound, it is readily seen that the different kinds of inflores- cence may be combined; the first ramification following one plan, and the subdivision another. The combination is usually expressed by a de- scriptive phrase, as “spikes racemose, or ra- cemed,” “heads corymbose,” &c. The combina- tion of the raceme and the corymb or the cyme gives rise to a form of inflorescence which has a technical name, viz.: — 399. The Panicle. This is formed when the secondary axes of a raceme branch in a corymbose manner, as in most Grasses (Fig. 318, 326), or when those of a corymb divide in the manner of araceme. And the name is applied to almost any open FIG. 326. A panicle. (Compare with Fig. 307.) DETERMINATE INFLORESCENCE. 217 and more or less elongated inflorescence which is irregularly branched twice, thrice, or a greater number of times. 400. A Thyrsus, or Thyrse, is a compact panicle of a pyramidal, oval, or oblong outline ; such as the cluster of flowers of the Lilac and Horsechestnut, a bunch of grapes, &c. 401. Definite or Determinate Inflorescence. In this class, the flowers all represent terminal buds (880). ‘The primary axis is directly terminated by a single flower-bud, as in Fig. 327, and its growth is of course arrested. Here we have a solitary terminal flower. Further growth can take place only by the development of secondary axes from axillary buds. These may develop at once as peduncles, or as leafy branches ; but they are in either case arrested, sooner or later, by a flower-bud, just as the primary axis was (Fig. 828). If further development ensues, it is by the production of branches of the third order, from the axils of leaves or bracts on the branches of the second order (Fig. 829); and so on. Hence this mode of inflo- rescence is said to be definite or determinate, in contradistinction to the indeterminate mode, already treated of, where the primary or leading axes elongate indefinitely, or merely cease to grow from the failure of nourishment, or some other extrinsic cause. The most common and most regular cases of determinate inflorescence occur in opposite-leaved plants, for obvious reasons; and such are accordingly chosen for the subjoined illustrations. But the Rose, Potentilla, and Buttercup furnish familiar examples of the kind in alternate-leaved plants. 328 329 402. The determinate mode of inflorescence assumes forms which may closely imitate those of the indeterminate kind, already de- scribed, and with which they have been confounded. When, for ex- ample, all the secondary axes connected with the inflorescence are arrested by terminal flowers, without any onward growth except FIG. 827-3829, Diagrams of regular forms of determinate or centrifugal inflorescence. 19 218 THE INFLORESCENCE. what forms their footstalks or pedicels, and these are nearly equal in length, a raceme-like inflorescence is produced, as in Fig. 330; or when the flowers have scarcely any pedicels, the spike is imitated. These are distinguished from the true raceme and spike, however, by the reverse order of development of the blossoms ; the terminal one opening earliest, and the others expanding in succession from above down- wards ; while the blossoming of the raceme proceeds from below upwards. Or when, by the elongation of the lower secondary axes, a corymb is imitated, the flowers are found to expand in succession from the centre of each ramification, beginning in the centre of the cluster, while the contrary occurs in the corymb. That is, while the order in indeterminate inflorescence is centripetal (387), that of the determinate mode is centrifugal. When the determinate inflorescence as- sumes the flattish or convex form, which it more com- monly does, it has a distinctive name, viz. : — 403. The Cyme. This is a flat-topped, rounded or expanded in- florescence, whether simple or compound, of the determinate class ; of which those of the Laurustinus, Elder, Dogwood, and Hydrangea (Fig. 420) are fully developed and characteristic examples. In com-' pound and compact cymes, such as those of the Laurustinus, Dogwood, &e., the leaves or bracts are usually minute, rudimentary, or abor- tive, and all the numerous flower-buds of the cluster are fully formed before any of them expand; and the blossoming then runs through the whole cluster in a short time, commencing in the centre of the cyme, and then in the centre of each of its branches, and thence pro- ceeding centrifugally. But in the Chickweeds (Fig. 331), in Hy- pericum, and many similar plants, the successive production of the branches and the evolution of the flowers, beginning with that which arrests the growth of the primary axis, go on gradually through the whole summer, until the powers of the plant are exhausted, or until all the branchlets or peduncles are reduced to single internodes, or pedicels destitute of leaves, bracts, or bractlets, when no further de- velopment can take place. Such cases enable us to study the deter- minate inflorescence to advantage, and to follow the successive steps of the ramification by direct observation. 404. A Cymule (Cymula) is a diminutive cyme, or a branch or cluster of a compound cyme. FIG. 330. Definite inflorescex -e imitating a raceme. DETERMINATE INFLORESCENCE. 219 405. The Fascicle is a very compact cyme, with upright or ap- pressed branches ; as in the Sweet William. 406. A Glomerule is a cyme condensed into a kind of head. It is to the cyme what the head is to the corymb or umbel. g 407. There are several abnormal modifications of definite inflo- rescence, arising from irregular development, or the suppression of parts, such as the non-appearance sometimes of the central flower, or often of one of the lateral branches at each division; as in the ultimate ramifications of Fig. 331, where one of the lateral pedicels is wanting. When this deviation is completely manifested, that is, when one of the side branches regularly fails, the cyme is apparently converted into a kind of one-sided raceme, and the flowers seem to expand from below upwards, or centripetally. .The diagram, Fig. 332, when compared with Fig. 331, explains this anomaly. The place of the axillary branch which fails to develop at each ramifica- tion is indicated by the dotted lines. Cases like this occur in several Hypericums, and in some other opposite-leaved plants. An analogous case oc- curs in many alternate-leaved plants; where the stem, being terminated by a flower, is con- tinued by a branch from the axil of the uppermost leaf or bract; this, bearing a flower, is similarly prolonged by a secondary branch; that by a third, and so on; as is shown in the diagram, Fig. 3338. Such forms of inflo- FIG. 331. The open, progressively developed cyme of Alsine Michauxii. FIG. 332, 383. Plan of two modifications of helicoid cymes or faiov racemes. 220 THE INFLORESCENCE. rescence, which we may observe in Drosera, Sedum, and Hounds- tongue, imitate the raceme so nearly, that they have commonly been considered as of that kind. They are distinguishable, however, by the position of the flowers opposite the leaf or bract, or at least out of its axil; while in the raceme, and in every modification of cen- tripetal inflorescence, the flowers necessarily spring from the axils. But if the bracts disappear, as they commonly do in the Forget-me- not, &c., the true nature of the inflorescence is not readily made out. The undeveloped summit is usually ezrcinate, or coiled in a spiral manner (Fig. 219), gradually unrolling as the flowers grow and expand, and becoming straight in fruit On account of this coiled arrangement, such cymes or false racemes are said to be helicoid, or scorpioid. 408. The cyme, raceme, head, &c., as well as the one-flowered peduncle, may arise, either at the extremity of the stem or leafy branch (terminal), or in the axil of the leaves (axillary). The case of a peduncle opposite a leaf, as in the Poke, the Grape-vine, &c., is just that illustrated in Fig. 353, except that in these cases the peduncles bear a cluster of flowers instead of a single one. The tendrils of the Vine (Fig. 161) occupy the same position, and are of the same nature. In a growing Grape-vine, it is evident that the uppermost tendril really terminates the stem; and that the latter is continued by the growth of the axillary bud, situated between the petiole and the peduncle; the branch thus formed, assuming the direction of the main stem, and appearing to be its prolongation, throws the peduncle or tendril to the side opposite the leaf. 409. The extra-axillary peduncles of most species of Solanum, &c. are terminal peduncles, which have become lateral by the evolution of an axillary branch, with which the peduncle or the petiole is united for some distance. Such peduncles sometimes come from extra-axillary accessory buds (169). 410. In the Linden (Fig. 742) the peduncle appears to spring from the middle of a peculiar foliaceous bract. But this is rather a bractlet, inserted on the middle of the peduncle, and decurrent down to its base. 411. A peduncle which arises from the stem at or beneath the surface of the ground, as in Bloodroot, the Primrose, the so-called stemless Violets, &c., is called a radical peduncle, or a SCAPE. 412. A combination of the two classes of inflorescence is not un- usual, the general axis developing in one way, but the separate THE FLOWER. 221° flower-clusters in the other. Thus the heads of the Sunflower and of all the so-called compound flowers (394) are centripetal, the flowers expanding regularly from the margin or circumference to the centre ; while the branches that bear the heads are developed in the centrifugal mode, the central heads being earliest to come into blos- som. This is exactly reversed in all Labiate (plants of the Mint tribe); where the stem grows on indefinitely, producing axillary clusters in the form of a general raceme or spike, which blossoms from below upwards ; while the flowers of each cluster form a cyme, and expand in the centrifugal manner. These cymes, or cymules (404), are usually close and compact, and being situated one in each axil of the opposite leaves, the two together frequently form a clus- ter which surrounds the stem, like a whorl or verticil (as in the Catnip and Horehound): hence such flowers are often said to be whorled or verticillate, which is not really the case, as they evidently all spring from the axils of the two leaves. The apparent verticil of this kind is sometimes termed a VERTICILLASTER. 413. True whorled flowers occur only in some plants with whorled leaves, as in Hippuris and the Water Milfoil. CHAPTER IX. OF THE FLOWER. Sect. I. Irs Oreans, on Component Parts. 414. Havine glanced at the circumstances which attend and con-- trol the production of flowers, and considered the laws which govern their arrangement, we have next to inquire what the flower is com- posed of. 415. The Flower (117) assumes an endless variety of forms in different species, so that it is very difficult properly to define: it. The name was earliest applied, as it is still in popular language generally applied, to the delicate and gayly colored leaves or petals,. so different from the sober green of the foliage. But the petals, and all these bright hues, are entirely wanting in many flowers, while ordinary leaves sometimes assume the brilliant coloring of the 19* 222 THE FLOWER. blossom The stamens and pistils are the characteristic organs of the flower ; but sometimes one or the other of these disappear from a particular flower, and both are absent from full double Roses, Camellias, &c., in which we have only a regular rosette of delicate leaves. This, however, is an unnatural state, the conse- $34 quence of protracted cultivation. 416. The flower consists of the organs of re- production of a Phanogamous plant (114), and their envelopes. A complete flower consists of (: A SYS the essential organs of reproduction (viz. stamens ©. % and pistils), surrounded by two sets of leaves o&GS 9. or envelopes which protect them. The latter Mo, ) are of course extertor or lower than the former, = ‘which in the bud they enclose. pees 417. The Floral Envelopes, then, are of two 335 sorts, and occupy two circles, one above or within the other. Those of the lower circle, the exterior envelope in the flower-bud, form the CaLtyx: they commonly exhibit the green color and have much the appear- ance of ordinary leaves. Those of the inner circle, which are commonly of a more delicate texture and brighter color, and form the most showy part of the blossom, compose the CoroLita. The (\ several parts or leaves of the corolla are Y called Perans: and the leaves of the ™ a Sse calyx take the corresponding name of Srpats. One of the five sepals of the flower represented in Fig. 334 is separately shown in Fig. 336; and one of the petals in Fig. 837. The calyx and corolla, taken together, or the whole floral envelopes, whatever they may con- sist of, are sometimes called the Pertantu (Perianthium or Peri- gonium). 418. The Essential Organs of the flower are likewise of two kinds, and occupy two circles or rows, one within the other. The first of FIG. 334. The complete flower of a Crassula. 335. Diagram of its cross-section in the bud, showing the relative position of its parts. The five pieces of the exterior circle are sections of the sepals ; the next, of the petals; the third, of the stamens through their anthers; the in- nermost, of the five pistils. ; FIG. 836. A sepal; 337, a petal; 338, a stamen; and 839, a pistil from the flower repre- sented in Fig. 384. ITS ORGANS OR PARTS. 223 these, those next within the petals, are the Sramens (Fig. 338). A stamen consists of a column or stalk, called the Frrament (Fig. 340, a), and of a rounded body, or case, termed the AN- THER (8), filled with a powdery substance called Pot- LEN, which it discharges through one or more slits or openings. The older botanists had no general term for the stamens taken collectively, analogous to that of corolla for the entire whorl of petals, and of calyx for the whorl of sepals. A name has, however, recently been pro- posed for the staminate system of a flower, which it is occasionally convenient to use; that of ANDR@CIUM. 419. The remaining, or seed-bearing organs, which occupy the centre or summit of the flower, to whose protection and perfection all the other parts of the flower are in some way subservient, are termed the Pistixs. To them collectively the name of Gynzcrum has been applied. One of them is separately shown in Fig. 339. This is seen more magnified and cut across in Fig. 842; and a dif- ferent one, longitudinally divided, so as to exhibit the whole length of its cavity, or cell, is represent- ed in Fig. 341. 420. A pistil is distinguished into three parts; namely, the Ovary (Tig. 341, a), the hollow portion at the base which con- tains the OvuLes, or bodies des- tined to become seeds ; the StyLe (2), or columnar prolongation of the apex of the ovary; and the Srie¢ma (c), a portion of the sur- face of the style denuded of epidermis, sometimes a mere point or a small knob at the apex of the style, but often forming a single or double line running down a part of its inner face, and assum- ing a great diversity of appearance in different plants. FIG. 340. A stamen, with the anther (b) discharging its pollen: a, the filament. FIG. 841. Vertical section of a pistil, showing the interior of its ovary, a, to one side of which are attached numerous ovules, d: above is the style, 6, tipped by the stigma, c. FIG. 342. A Pistil of Crassula, like that of Fig. 839, but more magnified, and cut across through the ovary, to show its cell, and the ovules it contains. At the summit of the style is seen a somewhat papillose portion, destitute of epidermis, extending a little way down the in- ner face: this is the stigma. 340 224 THE FLOWER. 421. All the organs of the flower are situated on, or grow out of, the apex of the flower-stalk, into which they are said, in botanical lan- guage, to be ¢nserted, and which is called the Torus, or RecePTac.e. This is the axis of the flower, to which the floral organs are attached (just as leaves are to the stem); the calyx at its very base; the petals just within or above the calyx; the stamens just within the petals ; and the pistils within or above the stamens (Fig. 343). 422. Such is the struct- ure of a complete and regu- lar flower ; which we take as the type, or standard of comparison. The calyx and corolla are termed pro- tecting organs. In the bud, they envelope the other parts : the calyx sometimes forms a covering even for the fruit; and when it retains its leaf-like texture and color, it as- similates the sap of the plant with the evolution of oxygen gas, in the same manner as do true leaves: the corolla elaborates honey or other secretions, for the nourishment, as is supposed, of the stamens and pistils. Neither the calyx nor corolla is essential to a flower, one or both being not unfrequently wanting. The stamens and pis- tils are, however, essential organs, since both are necessary to the production of seed. But even these are not always both present in the very same flower; as will be seen when we come to notice the diverse forms which the blossom assumes, and to compare them with our pattern flower. Sect. UT. Tar Turoreticat Structure or GreneraL Mor- PHOLOGY OF THE FLOWER. 423. To obtain at the outset a correct idea of the flower, it is needful here to consider the relation which its organs sustain to the organs of vegetation. Taking the blossom as a whole, we have recognized, in the chapter on Inflorescence (377), the identity of flower-buds and leaf-buds as to situation, &c. Flowers, consequently, FIG. 348. Parts of the flower of a Stonecrop, Sedum ternatum, two of each sort, and the receptacle, displayed: u, sepal: b, petal: c, stamen: d, pistil. ITS THEORETICAL STRUCTURE. 225 are at least analogous to branches, and the leaves of the flower are analogous to ordinary leaves. 424. But the question which now arises is, whether the leaves of the stem and the leaves and the more peculiar organs of the flower are not homologous parts, that is, parts of the same fundamental nature, although developed in different shapes that they may sub- serve different offices in the vegetable economy ;— just as the arm of man, the fore-leg of quadrupeds, the wing-like fore-leg of the bat, the true wing of birds, and even the pectoral fin of fishes, all repre- sent one and the same organ, although developed under widely dif- ferent forms and subservient to more or less different ends. The plant continues for a considerable time to produce buds which de- velop into branches. At length it produces buds which expand into blossoms. Is there an entirely new system introduced when flowers appear? Are the blossoms formed upon such a different plan, that the general laws of vegetation, which have sufficed for the interpre- tation of all the phenomena up to the inflorescence, are to afford no further clew? Or, on the contrary, now that peculiar results are to be attained, are the simple and plastic organs of vegetation — the stem and leaves — developed in new and peculiar forms for the ac- complishment of these new ends? The latter, doubtless, is the cor- rect view. The plant does not produce essentially new kinds of organs to fulfil the new conditions, but adopts and adapts the old. Notwithstanding these new conditions and the successively increas- ing difference in appearance, the fundamental laws of vegetation may be traced from the leafy branch into and through the flower. That is, the parts of the blossom’ are homologous with leaves, are leaves in other forms than that of foliage. 425. The student will have observed, that in vegetation no new organs are introduced to fulfil any particular condition, but the com- mon elements, the root, stem, and leaves, are developed in peculiar and fitting forms to subserve each special purpose. Thus, the same organ which constitutes the stem of an herb, or the trunk of a tree, we recognize in the trailing vine, or the twiner, spirally climbing other stems, in the straw of Wheat and other Grasses, in the colum- nar trunk of the Palm, in the flattened and jointed Opuntia, or Prickly Pear, and in the rounded, lump-like body of the Melon- Cactus. So, also, branches harden into spines in the Thorn, or, by an opposite change, become flexible and attenuated tendrils in the Vine, and runners in the Strawberry; or, when developed under 226 THE FLOWER. ground, they assume the aspect of creeping roots, and sometimes form thickened rootstalks, as in the Calamus and Solomon’s Seal, or tubers, as in the Potato. But the type is readily seen through these disguises. They are all mere modifications of the stem. The leaves, as we have already scen, appear under a still greater variety of forms, some of them as widely different from the common type of foliage as can be imagined ; such, for example, as the thickened and obese Jeaves of the Mesembryanthemums ; the intense scarlet or crimson floral leaves of the Euchroma, or Painted-Cup, of the Poinsettia of our conservatories, and of several Mexican Sages; the tendrils of the Pea tribe; the pitchers of Sarracenia (Fig. 300), and also those of Nepenthes (Fig. 301), which are leaf, tendril, and pitcher combined. The leaves also appear under very different aspects in the same individual plant, according to the purposes they are intended to subserve. The first pair of leaves, or cotyledons, when gorged with nutritive matter for the supply of the earliest wants of the embryo plant, as in the Almond, Bean, Pea, &e. (Fig. 108-120), would seem to be peculiar organs. But in some of these cases, when they have discharged this special office in ger- mination, by yielding to the young plant the store of nourishment with which they are laden, they imperfectly assume the color and appearance of foliage; while in other cases, as in the Convolvulus (Fig. 123) and the Maple (Fig. 104), they are green and foliaceous from the first. As the stem develops, the successive leaves vary in form or size, according to the varying vigor of vegetation. In our trees, we trace the last leaves of the season into bud-scales ; and in the returning spring we may often trace the scales of opening buds through intermediate states back again into true leaves (161). 426. The analogies of vegetation would therefore lead us to ex- pect, that in flowering the leaves would be wrought into new forms, to subserve peculiar purposes. In the chapter on Inflorescence, we have already learned that the arrangement and situation of flowers upon the stem conform to this idea. In this respect, flowers are absolutely like branches. The aspect of the floral envelopes favors the same view. We plainly discern the leaf in the calyx, and again, more delicate and refined, in the petals. In numberless in- stances, we find a regular transition from ordinary leaves into sepals, and from sepals into petals. And, while even the petals are occa- sionally green and herbaceous, the undoubted foliage sometimes assumes a delicate texture and the brightest hues (425). ‘The per- ITS THEORETICAL STRUCTURE. 227 fect gradation of leaves or bracts into sepals is extremely common. The transition of sepals into petals is exemplified in almost every case where there are more than two rows of floral envelopes ; as in the Magnolia, and especially in the White Water-Lily, various kinds of Cactus, the Illicium, or Star-Anise of the Southern States, and the Calycanthus, or Carolina Allspice, which present several series of floral envelopes, all nearly alike in color, texture, and shape ; but how many of the innermost are to be called petals, and how the re- mainder are to be divided between sepals and bracts, is entirely a matter of arbitrary opinion. In fact, the only real difference be- tween the calyx and corolla is, that the former is the outer, and the latter an inner series of floral envelopes. Sometimes the gradation extends one step farther, and exhibits an evident transition of petals into stamens; showing that these are of the same fundamental nature as the floral envelopes, which are manifestly traceable back to leaves. The White Water-Lily (Fig. 844) exhibits this latter transition, as evi- dently as it does that of sepals into petals. Here the petals occupy sev- eral whorls; and while the exterior are nearly undis- tinguishable from the calyx, the in- ner are reduced in- to organs which are neither well-formed petals nor stamens, but intermediate be- tween the two. They are merely petals of a smaller size, ‘with their summits contracted and transformed into imperfect anthers, containing a few grains of pollen: those of the series next within are more reduced in size, and bear perfect anthers at the apex; and a still further reduction of the lower part of the petal completes the transition into stamens of ordinary appearance. 427. By regular gradations, therefore, the leaf may be traced to FIG. 344. A sepal, petals, bodies intermediate between petals and stamens, and true sta- mens, of the White Water-Lily. 228 THE FLOWER. the petal and the stamen. But we could not expect to meet with intermediate states between a stamen and a pistil, except as a mon- strosity. The same organ could not fulfil such antagonistic offices. Nevertheless, stamens changing into pistils are occasionally found in monstrous blossoms. Cases of the kind are not very rare in Wil- lows, where anthers are found either half changed or else perfectly transformed into pistils, and bearing ovules instead of pollen. In gardens some stamens of the common Poppy have been found changed into perfect pistils, and imperfect attempts of the kind are more frequently to be detected in the large Oriental Poppy. Two Apple-trees in Ashburnham, Massachusetts, have long been known, which annually produce flowers in which the petals are replaced by five small foliaceous bodies, resembling sepals, and in place of sta- mens there are ten separate and accessory pistils, inserted on the throat of the calyx. 428. This transformation of one organ into another is called met- amorphosis. Assuming green foliage to be the natural state of leaves, the sepals and petals are said to be transformed or metamor- phosed leaves ; and the stamens and pistils are still more metamor- phosed, losing as they ordinarily do all appearance of leaves. Still, if these organs be, as it were, leaves developed in peculiar states, under the controlling agency of a power which has overborne the ordinary forces of vegetation, they must always have a tendency to us 26 develop in their primitive form, when the causes that govern the production of blossoms are interfered with during their formation. They may then reverse the spell, and revert into some organ below them in the series, as from stamens into petals, or pass at once into the state of ordinary leaves. That is, organs which from their position should be stamens or pistils may develop as petals or floral leaves, or else may revert at once to the state of ordinary leaves. Such cases of retrograde metamorphosis frequently occur in cultivated flowers. 429. Thus we often meet with the actual reconversion of what FIG. 345. A small leaf in place of a pistil from the centre of a flower of the double Cherry. 346. An organ intermediate between a leaf and a pistil, from a similar flower. FIG. 847. Leaflet of a Bryophyllum, developing buds along its margins, ITS THEORETICAL STRUCTURE. 229 should be a pistil into a leaf in the double Garden Cherry, either completely (Fig. 345), or else incompletely, so that the resulting organ (as in Fig. 846) is something intermediate between the two. The change of what should be stamens into petals is of common oc- currence in what are called double and semi-double flowers of the gardens ; as in Roses, Camellias, Carnations, &c. When such flow- ers have many stamens, these disappear as the supernumerary petals increase in number; and the various bodies that may be often ob- served, intermediate between perfect stamens (if any remain) and the outer row of petals, — from imperfect petals, with a small lamina tapering into a slender stalk, to those which bear a small’ distorted lamina on one side and a half-formed anther on the other, — plainly reveal the nature of the transformation that has taken place. Car- ried a step farther, the pistils likewise disappear, to be replaced by a rosette of petals, as in fully double Buttereups. 430. In full double Buttercups we may often notice a tendency in the inner petals to turn green, that is, to retro- grade still farther into foli- aceous organs. And there is a monstrous state of the Strawberry blossom, well known in Europe, in which all the floral organs revert into green sepals, or imper- fect leaves. Fig. 348 ex- hibits a similar retrograde metamorphosis in a flower of the White Clover, where the calyx, pistil, &c. are still recognizable, although partially transformed into leaves. And the ovary, which has opened down one side, bears on each edge a number of small and imperfect leaves ; much as the ordinary leaves, or rather leaflets, of Bryophyllum are apt to develop rudimentary tufts of leaves, or leaf-buds, on their margins (Fig. 347), which ‘may grow into little plantlets, by which the species is often propagated. This retrograde metamorphosis of FIG. 848. A flower of the common White Clover reverting to a leafy branch ; after Turpin. 20 230 THE FLOWER. a whole blossom into foliaceous parts has been termed chlorosts, from the green color thus assumed. ; 431. A somewhat different proof that the blossom is a sort of branch, and its parts leaves, is occasionally furnished by monstrous flowers in the production of a leafy branch from the centre of a flower, or of one flower out of the centre of another (as rose-buds out of roses). Here the receptacle or axis of the flower resumes the ordinary vegetative growth, as in Fig. 849, 850. In wet and warm. springs, some of the flower- buds of the Pear and Apple are occasion- ally forced into vege- tation, so as com- pletely to break up the flower and change it into an ordinary leafy branch. This proves that the recep- tacle of a flower is of the nature of the stem. 432. An analogous kind of monstrosity, viz. the development of buds— either into leafy branches or into blossoms (Fig, 551) — in the axils of petals, or even of stamens or pistils, fur- nishes additional evidence that these bodies are of the nature of leaves; for, whatever bears a bud or branch in its axil must represent a leaf. 433. The irresistible conclusion from all such evidence is, that the flower is one of the forms — the ultimate form — under which branches appear; that the leaves of the stem, the leaves or petals of the flower, and even the stamens and pistils, are all forms of a common FIG. 349. Retrograde metamorphosis of a flower of the Fraxinella of the gardens, from Lindley’s Theory of Horticulture ; an internode elongated just above the stamens, and bearing a whorl of green leaves. FIG. 850. A monstrous pear, prolonged into a leafy branch ; from Bonnet. FIG. 851. A flower of False Bittersweet (Celastrus scandens), producing other flowers in the axils of the petals; from Turpin. ITS THEORETICAL STRUCTURE. 231 type, only differing in their special development. And it may be added, that in an early stage of development they all appear nearly alike. That which, under the ordinary laws of vegetation, would have developed as a leafy branch, here developes as a flower; its several organs appearing under forms, some of them slightly, and others extremely, different in aspect and in office from the foliage. But they all have a common nature and a common origin, or, in other words, are homologous parts (424). 434, Now, as we have no general name to comprehend all those organs which, as foliage, bud-scales, bracts, sepals, petals, stamens, &c., successively spring from the ascending axis or stem, having ascer- tained their essential identity, we naturally take some one of them as the type, and view the others as modifications or metamorphoses of it. The leaf is the form which earliest appears, and is the most general of all the organs of the vegetable; it is the form which is indispensable to normal vegetation, since in it, as we have seen, as- similation is effected, and all organic matter is produced ; it is the form into which all the floral organs may sometimes be traeed back by numerous gradations, and to which they are liable to revert when flowering is disturbed and the vegetative forces again prevail. Hence the leaf may be properly assumed as the type or pattern, to which all the others are to be referred. When, therefore, the floral organs are called modified or metamorphosed leaves, it is not to be supposed that a petal has ever actually been a green leaf, and has subsequently assumed a more delicate texture and hue, or that sta- mens and pistils have previously existed in the state of foliage ; but only that what is fundamentally one and the same organ develops, in the progressive evolution of the plant, under each or any of these various forms. When the individual organ has developed, its destiny is fixed. 435. The theory of vegetable morphology may be expressed in other and more hypothetical or transcendental forms. We have preferred to enunciate it in the simplest and most general terms. But, under whatever particular formula expressed, its adoption has not only greatly simplified, but has thrown a flood of light over the whole of Structural Botany, and has consequently placed the whole logic of Systematic Botany upon a new and philosophical basis. Our restricted limits will not allow us to trace its historical develop- ment. Suffice it to say, that the idea of the essential identity of the floral organs and the leaves was distinctly propounded by Lin- 282 THE FLOWER. neeus,* about the middle of the last century. It was newly taught by Caspar Frederic Wolff, about twenty years later, and again, after the lapse of nearly twenty years more, by the celebrated Goethe, who was entirely ignorant, as were his scientific contemporaries, of what Linneus and Wolff had written on the subject. Goethe’s curious and really scientific treatise was as completely forgotten or overlooked as the significant hints of Linneus had been. Jn ad- vance of the science of the day, and more or less encumbered with hypothetical speculations, none of these writings appear to have ex- erted any appreciable influence over the progress of the science, until it had reached a point, early in the present century, when the nearly simultaneous generalizations of several botanists, following different clews, were leading to the same conclusions. Ignorant of the writings of Goethe and Wolff, De Candolle was the first to de- velop, from an independent and original point of view, the idea of symmetry in the flower; that the plan, or type, of the blossom is regular and symmetrical, but that this symmetry is more or less in- terfered with, modified, or disguised by secondary influences, such as suppressions, alterations, or irregularities, giving rise to the greatest diversity of forms. The reason of the prevailing symmetrical ar- rangement of parts in the blossom has only recently been made apparent, in the investigation of phyllotaxis (256) ; from which it appears that the general arrangement of the leaves upon the stem is carried out in the flower. Sect. TI. Tuer Syaaerry or tur FLower. 436. A Symmetrical Flower is one which has an equal number of parts in each circle or whorl of organs; as, for example, in Fig. 834, where there are five sepals, five petals, five stamens, and five pistils. It is not less symmetrical, although less simple, when there are two or more circles of the same kind of organ; as in Sedum (Fig. 361), where there are two.sets of stamens, five in each; in the Barberry, where there are two or more sets of sepals, two of petals, and two of stamens, three in each set, &e. A complete flower * “Principium flora et foliorum idem est. Principiam gemmarum et folio- rum idem est. Gemma constat foliorum rudimentis. Perianthium sit ex con- natis foliorum rudimentis,” ete. Philosophia Botunica, p. 301. ITS SYMMETRY. 233 (as already defined, 416) is one that possesses ‘both sorts of floral envelopes, calyx and corolla, and both essential organs, viz. stamens and pistils. 437. The simplest possible complete and symmetrical flower would be one with the ca- lyx of a single sepal, a corolla of a single petal, a single stamen, and a single pistil; as in the annexed diagram (Fig. 852), which represents the elements of a simple stem (Fig. 157), ter- minated by an equally simple flower. Tach constituent of the blossom represents a phyton (163), with its stem part reduced to a mini- mum, and its leaf part developed in a peculiar way, according to the rank it sustains and the office it is to fulfil. ‘That there are short inter- nodes between consecutive organs in the flower is usually apparent on minute inspection of its axis, or receptacle ; and some of them are con- spicuously prolonged in certain cases. But they are commonly so short that the organs are brought into juxtaposition, just as in a leaf- bud, and the higher or later-formed parts are interior or enclosed by the lower. 438. Perhaps the exact case of a flower at once so complete and so simple is not to be met with, the organs of the flower, or some of them, being generally multiplied. Thus we find a circle or whorl of each kind of organ, and often two or three circles, or a still larger and apparently indefinite number of parts. In fact, the floral organs usually occur in twos, threes, fours, or fives; and the same number is apt to prevail throughout the several circles of the flower, which therefore displays a sym- is 352 metrical arrangement, or a manifest tendency towards it.* * Terms expressive of the number of parts which compose each whorl of kind of organ — which are sometimes very convenient to use — are formed of FIG. 352 Diagram of a plant, with a distichous arrangement of the phytons, carried through the complete flower, of the simplest kind, consisting of, a, a sepal; b,a petal; c,a etamen ; and d, a pistil: br is the bract or uppermost proper leaf. 20 * 234 THE FLOWER. 439. Having already noticed the symmetrical arrangement of the foliage (236-251), and remarked the transition of ordinary leaves into those of the blossom (426), we naturally seek « ( 4 to bring the two under WU the same general laws, “ ad and look upon each floral 4 W whorl as answering ei- , ther to a cycle of alter- 7 nate leaves with their =e an anrenneenennnnn ni respective internodes undeveloped, or to a pair or verticil of opposite or verticillate leaves. Thus, the simplest com- bination, where the organs are dimerous, or in twos, may be compared with the alternate two- ranked arrangement (238), the calyx, the corolla, stamens, &c. each consisting of one cycle of two ‘elements ; or else with the case of opposite leaves (250), when each set would answer to a pair of leaves. So, likewise, the organs of a trimerous flower (viz. one with its parts in threes, as in Fig. J SQ 853) may be taken either as cycles of alternate a leaves of the tristichous mode (289), with the axis shortened, which would throw the parts into successive whorls of threes, or else as proper verticils of three leaves ; while those of a pentamerous or quinary flower (with the parts in fives, as in Fig. 854) would answer to the cycles of the 2 arrangement (240) of alternate leaves, or to proper five-leaved verticils. So the whorls of a tetra- merous flower are to be compared with the case of decussating op- the Greek numerals combined with pépos, a part. Thus a flower with only one organ of each kind, as in the diagram, Fig. 352, is monomerous ; a flower or a whorl of two organs is dimerous (Fig. 373); of three (as in Fig. 353), trimerous ; of four, tetramerous (Fig. 405) ; of five (as in Fig. 334), pentamerous ; of six, hex- amerous ; of ten, decamerous, &c. These words are often printed with figures, as 2-merous, 3-merous, 4-merous, 5-merous, and so on. FIG. 853. Parts of a symmetrical trimerous flower (Tilleea muscosa): a, calyx ; b, corolla; c, stamens ; d, pistils. FIG. 854. Ideal plan of a plant, with the simple stem terminated by a symmetrical penta- merous flower; the different sets of organs separated to some distance from each other, to show the relative situation of the parts; one of each, namely, a, a sepal, 6, a petal, c, astamen, and d, a pistil, also shown, enlarged. ALTERNATION OF THE FLORAL ORGANS. 235 posite leaves, combined two by two, or with quaternary verticillate leaves (251) ; either of which would give sets of parts in fours. 440. The Alternation of the Floral Organs. We learn from obser- vation that, as a general rule, the parts of the successive circles of the flower alternate with each other. The five petals of the flower represented in Fig. 334, for ex- ample, are not opposed to the five sepals (that is, /, 7—\ situated directly above or before them), but alter- | Ss) nate with them, that is, or stand over the intervals \\ O oO between them; the five stamens in like manner al- ternate with the petals, and the five pistils with the stamens, as is shown in the diagram, Fig. 835. The same is the case in Fig. 353, the several organs of a flower with its parts in threes; and in fact this is the rule, the few exceptions to which have to be separately accounted for. 441. This comports with the more usual phyllotaxis in opposite and verticillate leaves, where the successive pairs decussate, or cross each other at right angles (251), or the leaves of one verticil several- ly correspond to the intervals of that underneath, making twice as many vertical ranks as there are parts in the whorl. The alternation of the floral organs is therefore most readily explained on the assump- tion that the several circles are true decussating verticils. But the inspection of a flower-bud with the parts imbricated in wstivation (494) shows that the several members of the same set do not origi- nate exactly in the same plane. The five petals, for example, in the cross-section of the pentamerous blossom shown in Fig. 835 (and the same arrangement is still more frequently seen in the calyx), are so situated, that two are exterior in the bud, and therefore in- serted lower on the axis than the rest, the third is intermediate, and two others are entirely interior, or inserted higher than the rest. In fact, they exactly correspond with a cycle of alternate leaves of the quincuncial or five-ranked arrangement, on an extremely abbreviated axis, or on a horizontal plane, as is at once seen by comparing the ground plan, Fig. 835, with Fig. 206. Compare also Fig. 855 with Fig. 203. Also, when the parts are in fours, two are almost always exterior in the bud, and two interior. Moreover, whenever the floral envelopes, or the stamens or pistils, are more numerous, £0 as to occupy several rows, the spiral disposition is the more manifest. It is most natural, accordingly, to assume that the calyx, corolla, FIG. 355. Cross-section of the flower-bud of Fig. 853, to show the alternation of parts. 236 THE FLOWER. stamens, &c. of a pentamerous flower are each a depressed spiral or cycle of the 2 mode of phyllotaxis, and those of the trimerous flower are similar spirals of the 4 mode. But then the parts of the suc- cessive cycles should be superposed, or placed directly before each other on the depressed axis, as leaves are; whereas, on the contrary, they almost always alternate with each other in the flower. 442. To reconcile this alternation with the laws of phyllotaxis in alternate leaves, Prof. Adrien de Jussieu has advanced an ingenious hypothesis. He assumes the 5 spiral arrangement as the basis of the floral structure both of the trimerous and pentamerous flower, (at least when the envelopes are imbricated in the bud,) this being the one that brings the successive parts most nearly into alternation, either in threes or in fives; as will readily be observed on inspection of the tabular projection of that mode, given on page 139. The dif- ference between the position of parts in regular alternation, whether in threes or fives, and that assigned by an accurate spiral projection of the 75; mode, is very slight as respects most of the organs, and in none does the deviation exceed one thirteenth of the circumference ; —a quantity which becomes nearly insignificant on an axis so small as that of most flowers. Moreover, if the interior organs of a regular and symmetrical flower were thus to originate in the bud nearly in alternation with those that precede them, they would almost necessa- rily be crowded a little, as they develop, into the position of least pres- sure, and thus fall into these intervals with all the exactness that is actually found in nature. For in living bodies, endowed as they are with plasticity and a certain power of adaptation to circumstances, the positions assumed are not mathematically accurate; and the effect of unequal pressure in the bud in throwing the smaller parts more or less out of their normal position may be observed in almost any irregular flower. Moreover, in all the forms of phyllotaxis from 5; onwards, it is doubtful whether what we term vertical ranks are exactly superposed. In tracing them upward to some extent, we perceive indications of a curviserial arrangement, where the superposition is continually approximated, but is never exactly at- tained (248). Lestibudois* has revived the older hypothesis of Jussieu, and others; viz. that a second spiral is introduced with the petals and continued in the pistils. And Schimper and Braun im- agine a change of half the angular divergence (prosenthesis) to occur * In Annales des Sciences Naturelles, ser. 4, Vol. 2, p. 226. POSITION IN RESPECT TO THE BRACT AND AXIS. 237 in passing from one cycle to the next ;—— which is rather describing the anomaly in other words than explaining it. 443. Whether we regard the floral circles as decussating verticils, or as cycles of alternate leaves in some way altered as to their suc- cession, we cannot fail to discern an end attained by such arrange- ment, namely, a disposition of parts which secures the greatest econ- omy of space on an abbreviated axis, and the greatest freedom from mutual pressure. 444. Position of the Flower as respects the Axis and subtending Braet. All axillary flowers are situated between a leaf and the stem, or, which is the same thing, between a bract. and the axis of inflores- cence. These two fixed points enable us to indicate the relative position of the parts of the floral circles with precision. That part of the flower which lies next the leaf or bract from whose axil it arises is said to be anterior, or inferior (lower): that which is dia- metrically opposite or next the axis is posterior, or supertor (upper).* AY F\ (& It is important to notice the relative position of parts in this re- spect. This is shown in a proper diagram by drawing a section of the bract in its true position under the section of the flower- bud, as in Fig. 358: the position of the axis is necessarily dia- metrically opposite, and its section is sometimes indicated by a dot or small circle. In an axillary flower with the parts in fours, one of * As if these were not terms enough, sometimes the organ, or side of the flower, which looks towards the bract, is likewise called exterior, and the organ or side next the axis, interior ; but these terms should be kept to designate the relative position of the members of the floral circles in zestivation (494). FIG. 356. Diagram ofa Cruciferous flower (Erysimum) ; 2, the axis of inflorescence. (The bract is abortive in this, as in most plants of this family.) FIG. 357. Diagram of a flower of a Rhus, with the axis, a, and the bract, b, to show the relative position of parts. FIG. 358. Diagram of a flower of the Pulse tribe: @, the axis, and 4, the bract.. 238 THE FLOWER. the sepals will be anterior, one posterior, and two lateral, or right and left; as in the annexed diagram of a Cruciferous blossom (Fig. 356); while the petals, alternating with the sepals, consist of an anterior and a posterior pair; and the stamens, again, stand before the sepals. An axillary flower of five parts will have either one sepal superior or posterior and two inferior or anterior (as in Rhus, Fig. 857), or else, vice versd, one inferior and two superior, as in Papilionaceous flowers (Fig. 358): in both cases the two remaining sepals are lateral. The petals will consequently stand one superior, two inferior, and two lateral, in the last-named case; and one in- ferior, two superior, and two lateral, in the former. In terminal flowers (401), the position of parts in respect to the uppermost leaves or bracts should be noted. Sect. IV. Tue Various Mopirications OF THE FLOWER. 445. Tux complete and symmetrical flowers, with all their organs in the most normal state, that have now been considered, will serve as the type or pattern, with which we may compare the almost num- berless variety of forms which blossoms exhibit, and note the char- acter of the differences observed. We proceed upon the supposi- tion, that all flowers are formed upon a common plan,—a plan essentially the same as that of the stem or branch, of which the flower is a modified continuation, — so that in the flower we are to expect no organs other than those that, whatever their form and office, answer either to the axis or to the leaves; so that the differ- ences between one flower and another are to be explained as cir- cumstantial variations of one fundamental plan, — variations for the most part analogous to those which occur in the organs of vegeta- tion themselves. Having assumed the type which represents our conception of the most complete, and at the same time the simplest flower, we apply it to all the cases which present themselves, and especially to those blossoms in which the structure and symmetry are masked or obscured; where, like the disenchanting spear of Ithuriel, its application at once reveals the real character of the most disguised and complicated forms of structure. 446. Our pattern flower consists of four circles, one of each kind of floral organ, and of’ an equal number of parts, successively alternat- ing with one another. It is complete, having both calyx and corolla, ITS VARLOUS MODIFICATIONS. 239 as well as stamens and pistils (416) ; symmetrical, having an equal number of parts in the successive whorls (486) ; regular, in having the different members of each circle all alike in size and shape; it has but one circle of the same kind of organs ; and, moreover, all the parts are distinct or unconnected, so as to exhibit their separate origin from the axis or receptacle of the flower. This type may be presented under either of the four numerical forms which have been illustrated. That is, its circles may consist of parts in twos (when it is binary or dimerous), threes (ternary or trimerous), fours (qua- ternary or tetramerous), or fives (quinary or pentamerous). The first of these is the least common; the trimerous and the pentame- rous far the most so. The last is restricted to Dicotyledonous plants, where five is the prevailing number; while the trimerous flower largely prevails in Monocotyledonous plants, although by no means wanting in the Dicotyledonous class, from which Fig. 353 is taken. 447. The principal deviations from the perfectly normaf or pattern flower may be classified as follows. They arise, either from, — Ist. The production of additional circles of one or more of the floral organs (regular multiplication or augmentation) ; 2d. The production of a pair or a cluster of organs where there should normally be but one, that is, the multiplication of an organ by division (abnormal multiplication, also termed deduplication or chorists) ; 3d. The anteposition (or opposition, instead of alternation) of the parts of successive circles ; 4th. The union of the members of the same circle (coalescence) 3 C-/’' 5th. The union of adjacent parts of different circles (adnation) ; 6th. The unequal growth or unequal union of different parts of the same circle (¢rregularity) ; or, 7th. The non-production or abortion of some parts of a circle, or of one or more complete circles (suppression or abortion). 8th. To which may be added, the abnormal development of the receptacle or axis of the flower. 448. Some of these deviations interfere with the symmetrical structure of the flower; others merely render it irregular, or dis- guise the real origin or the real number of parts. These deviations, moreover, are seldom single; but two, three, or more of the kinds fre- quently co-exist, so as to realize almost every conceivable variation. 449. Several of these kinds of deviation may often be observed 240 THE FLOWER. even in the same natural family of plants, where it cannot be doubt- ed that the blossoms are constructed upon a common plan in all the species. Even in the family Crassulacemw, for example, where the flowers are remarkably symmetrical, and from which our pattern flowers, Fig. 334 and 353, are derived, a considerable number of these di- versities are to be met with. In Crassula, we have the completely symmetrical and simple pentamerous flower (Fig. 359, 360), viz. with a calyx of five sepals, a corolla of five petals alter- nate with the former, an andreecium (418) of five stamens alternating with the petals, and a gynecium (419) of five pistils, which are alter- nate with the stamens; and all the parts are regular and symmetrical, and also distinct and free from each other ; except that the sepals are somewhat united at the base, and the petals and ato) stamens slightly connected with the inside of the calyx, instead of arising directly from the recep- tacle or axis, just beneath the pistils. Five is the prevailing or normal number in this family. Nevertheless, in the related genus Tillea, most of the species, like ours of the United States, have their parts in fours, but are otherwise similar, and one common European species has its parts in threes (Fig. 853) ; that is, one or two members are left out of each circle, which of course does not in- terfere with the symmetry of the blossom. So in the more conspic- uous genus Sedum (the Stonecrop, Live-for-ever, Orpine, &c.), some species have their parts in fives ; others in fours; and several, like our S. ter- natum, have those of the first blossom in fives, but all the rest in fours. But Sedum also illustrates the case of reg- ular augmentation (447, Ist) in its an- dreecium, which consists of twice as many stamens as there are members in the other parts; that is, an addi- eh tional circle of stamens is introduced (Fig. 861), the members of which may be distinguished by being shorter or a little later than FIG. 359. Flower ofa Crassula. 860. Cross-section of the bud, FIG. 861. Flower of a Sedum or Stonecrop. ITS VARIOUS MODIFICATIONS. 241 those of the primary circle, and by their alternation with these, which brings them directly opposite the petals. A third genus (Rochea) exhibits the same pentamerous and normal flower as Cras- sula, except that the contiguous edges of the petals slightly cohere about half their length, although a little force suffices to separate them: in another (Grammanthes, Fig. 362), the petals are firmly united into a tube for more than half their length, and so are the sepals likewise; illustrating the fourth of the deviations above enumerated (447). Next, the allied genus Cotyledon (Fig. 363) exhibits in the same flower both this coalescence of similar parts, and an additional circle of stamens, as in Sedum. It likewise pre- sents the next order of deviations, in the union (adnation) of the base of its stamens to the base of the corolla, out of which they ap- parently arise, as is seen in Fig. 364, where the corolla is laid open and displayed. The pistils, although ordinarily exhibiting a strong tendency to unite, are perfectly distinct in all these cases, and in- deed throughout the order, with two exceptions; one of which is seen in Penthorum, where the five ovaries (Fig. 865) are united below into a solid body, while their summits, as well as the styles, are separate. The same plant also furnishes an example of the non- production (or seppression) of one set of organs, that of the petals ; which, although said to exist in some specimens, are ordinarily want- ing altogether. Another instance of increase in the number of parts occurs in the Houseleek (Sempervivum), in which the sepals, petals, and pistils vary in different species from six to twenty, and the sta- mens from twelve to forty. 362 363 364 sp altar 450. Some illustrations of the principal diversities of the flower, FIG. 362. Flower of Grammanthes. 368. Flower of a Cotyledon. 9864. The corolla laid open, showing the two rows of stamens inserted into it. 365, The five pistils of Penthorum, united. 866. A cross-section of the same. 21 242 THE FLOWER. as classified above (447), may be drawn at random from different families of plants ; and most of the technical terms necessarily em- ployed in describing these modifications may be introduced, and explained, as we proceed. The multiplication of parts is usually in consequence of the 451. Augmentation of the Floral Circles, An increased number of circles or parts of all the floral organs occurs in the Magnolia family ; where the floral envelopes occupy three or four rows, of three leaves in each, to be divided between the calyx and corolla, while the stamens and pistils are very numerous, and compactly arranged on the elongated receptacle. The Custard-Apple family, which is much like the last, has also two circles in the corolla, three petals in each, a great increase in the number of stamens, and, in , our Papaw (Fig. 654), sometimes only one circle of pistils, viz. three, sometimes twice, thrice, or as many as five times that number. The Water-Lily, likewise, has all its parts augmented, the floral envelopes and the stamens especially occupying a great number of rows; and the pistils are likewise numerous, although their number is disguised by being united into one body. When the sepals, petals, or other parts of the flower are too numerous to be readily counted, or even exceed twelve, especially when the number is inconstant, as it commonly is in such cases, they are said to be tndefinite ; and a flower with numerous stamens is also termed polyandrous. 452. When such multiplication of the floral circles is perfectly regular, the number of the organs so increased is a multiple of that’ which forms the basis of the flower; but this could scarcely be de- termined when the numbers are large, as in the stamens of a Butter- cup, for example, nor is there much constancy when the whorls of any organ exceed three or four. The doubling or trebling of any or all the floral circles does not interfere with the symmetry of the flower ; but it may obscure it (in the stamens and pistils especially), by the crowding of two or more circles of five members into what appears like one of ten, or two trimerous circles into what appears like one of six. The latter case occurs in most Endogenous plants. 453. The production of additional floral circles may account for most cases of increase of the normal number of organs, but not for all of them. It must, we think, be admitted that certain parts of the blossom are sometimes increased in number by the production of a double organ, or a pair or a group of organs which occupy the place of one; namely, by what has been termed > CHORISIS OR DEDUPLICATION. 243 454. Chorisis or Deduplication, The name dédoubdlement of Dunal, which has been translated deduplication, literally means unlining ; the original hypothesis being, that the organs in question unline, or tend to separate into two or more Jayers, each having the same structure. We may employ the word deduplication, in the sense of the doubling or multiplication of the number of parts, without adopting this hypothesis as to the nature of the process, which at best can well apply only to some special cases. The word chorisis (xépiors, the act or state of separation or multiplication), also pro- posed by Dunal, does not involve any such assumption, and is ac- cordingly to be preferred. By regular multiplication, therefore, we mean the augmentation of the number of organs through the de- velopment of additional circles ; which does not alter the symmetry of the flower. By chorisis we denote the production of two or more organs in the place of one, in a manner analogous to the division of the blade of a leaf into a number of separate blades, or leaflets. 455. Chorisis, or the division of an organ into a pair or a cluster, may take place in two ways. In one case the parts or organs thus produced stand one before the other ; in the other case they stand side by side. The first is named transverse chorisis ; the second, collateral chorisis. Both must evidently disturb ‘or disguise the normal ja eset symmetry of the blossom. 456. Collateral Chorisis is that in respect to which there is least doubt as to the nature of the process. We have a good example of it in the tetradynamous stamens (519) of the Mustard or Cress family (Fig. 406). Here, in a flower with a symmetrical tetramerous calyx and corolla, we have six stamens; of which the two lateral or shorter ones are alternate with the adjacent petals, as they normally should be, while the four ee are in two pairs, one pair before each remaining interval of the petals ; as is shown in the annexed diagram (Fig. 867). That is, on the anterior and on the posterior side of the flower we have two stamens where there normally should be but a single one, and where, FIG. 367. Diagram ofa (tetradynamous) flower of the order Cruciferee. FIG. 368. Flower of Streptanthus hyacinthoides, from Texas (the sepals and stamens re- moved), showing a forked or double stamen in place of the anterior pair. 244 THE FLOWER. indeed, there is but one in a few plants of this family. Now it oe- casionally happens that the doubling of this stamen is, as it were, arrested before com- pletion, so that in place of two stamens we have a forked fila- ment bearing a pair of anthers; as fre- quently happens in some species of Strep- tanthus (Fig. 368). Here the two stamens in place of one may be compared with a compound leaf of two leaflets. In the re- lated Fumitory fam- ily three stamens reg- ularly appear in the place of one. The circles of the flower are in twos through- out; viz. there is, first, a pair of small scale-like sepals; alternate with these, a pair of petals, which, in Dicentra, &c. (Fig. 369-3871), are saccate or spurred below ; alternate and within these is a second pair of petals (Fig. 372) ; pan alternate with these are two clusters of (=~ three more or less united stamens, which GO 2 plainly oceupy the place of two single ee — stamens. The arrangement of parts is shown in the annexed diagram (Fig. ~~ _—- 373) ; where the lowest line indicates the ve = subtending bract, and therefore the anterior side of the blossom; the two short lines in the same plane represent the sepals; the two FIG. 369. Dicentra Cucullaria (Dutchman’s-Breeches), with its kind of bulb, a leaf, and a scape in flower; reduced in size. 870. A flower of the natural size. 371. The same, with the parts separated, except the sepals, one of which is seen at the base of the pistil. 372. The inner pair of petals, with their tips coherent. FIG. 373. Diagram (cross-section) of the similar flower of Adlumia. 3874. One of the sta- mens increased into three by chorisis (the lower part of the common filament is cut away). CHORISIS OR DEDUPLICATION. 245 next within, the lateral and exterior petals; those alternate and within these, the inner circle of petals ; and alternate with these are the anthers of the two stamen-clusters. The centre is occupied by a section of the pistil, which consists of two united. The three sta- mens are lightly connected in Dicentra (Fig. 371); but in Corydalis and Adlumia there is only one strap-shaped filament on each side, which is three-forked at the tip, each fork bearing an anther (Fig. 374). We have a similar case in some Hypericums and in Elodea (Fig. 375), except that, while the floral envelopes are in fives, the circles within them are commonly in threes. The three members of the andreecium are normally placed, alter- nating with the three members of the gynacium within, and also with three glands, which probably replace another circle of stamens. Now each real DN stamen is here multiplied into three, united below; so that the whole compound body may be viewed as homologous with a compound trifoliolate leaf (289). If this be so, then each cluster of numerous stamens in the common St. Johns- wort may be regarded as answering to one stamen greatly multiplied in the same way, and as analogous to a sessile decompound leaf. And the same may be said of each stamen-cluster in the, Linden (Fig. 383). The actual development of the cluster, from a protu- berance which in the forming flower-bud occupies the place of a single stamen, has been traced by Duchatre, Payer, &e. in this and other cases. @&) 457. Thus far we are sustained by a clear analogy in the organs of vegetation. As the leaf frequently develops in the form of a lobed, divided, or compound leaf, — that is, as a cluster of partially or completely distinct organs from a common base,—so may the stamen, or even the pistil, become compound as it grows, and give rise to a clus- ter, instead of completing its growth as a solitary organ: and it appears that the organogeny is strikingly sim- ilar in the two cases. Nor is it very unusual for petals to become divided or deeply lobed in the same manner; as, for example, those FIG. 875. Diagram (cross-section) of'a flower of Elodea Virginica. 376. One of the three stamen-clusters, consisting of a trebled stamen, enlarged. FIG. 377. A petal of Mignonette, enlarged. 21* 246 THE FLOWER. of Mignonette (Fig. 877). Jn certain cases an analogous division takes place in the opposite direction, so that the parts or lobes are situated one before the other. An indication of this is also mani- fest in the petals of Mignonette, the lower part or broad claw of which is slightly extended at its summit, on each side, beyond the origin of the many-cleft limb or blade. Division in this direc- tion has been termed 458. Transverse or Vertical Chorisis. ‘The most familiar case is that of the crown, or small and mostly two-lobed ap- pendage on the inside of the blade of the petals of Silene (Fig. 878) and of many other Caryo- phyllaceous plants. This is more like a case of real dédoublement or unlining, i. e. a partial sepa- ration of an inner lamella from the outer, and perhaps may be so viewed. Stamens sometimes bear a similar and more striking appendage, as in Larrea, for example (Fig. 379), and most other plants of the Guaiacum family ; also in the Dodder (Fig. 1044). Let it be noted that in all such cases the appendage occupies the inner side of the petal or stamen, and that it is commonly two-lobed. Again, before each petal of Parnassia (Fig. 381), although slightly if at all united with it, is found a body which in P. palustris is somewhat petal-like, with a considerable number of lobes, and in P. Caroliniana is divided almost to the base into three lobes, which look much like abortive stamens. The true stam- 378 ineal circle, however, oc- cupies its proper place within these ambiguous bodies, alternate with the petals. We cannot doubt that the former are of the same nature as the scale of the stamens in Larrea, and the crown of the petals FIG. 378. A petal of Silene Pennsylvanica, with its crown or appendage. FIG. 379. A stamen of Larrea Mexicana, with a scale-like appendage cohering with its base on the inner side. FIG. 380. Diagram (cross-section) of the flower of Parnassia Caroliniana. 381. A petal, with the appendage that stands before it. CHORISIS OR DEDUPLICATION. 247 of Silene; and we incline to consider the accessory body in such cases as homologous with the stipules of the leaf.* 459, It may also be noticed, that, while in collateral chorisis the increased parts are usually all of the same nature, like so many similar leaflets of a compound leaf, in what is called transverse cho- risis there is seldom such a division into homogeneous parts ; but the original organ remains, as it were, intact, while it bears an append- age of some different appearance or function on its inner face, or at its base on that side. Thus the stamens of Larrea, &c. bear * For fuller illustrations of these theoretical points, the student is referred to the figures and text of The Genera of the United States Flora Illustrated, espe- cially to Vol. 2, — An able writer in Hooker’s Journal of Botany and Kew Garden Miscellany, Vol. 1, p. 360, (with whom we are in accord as to the nature of col- lateral chorisis,) “being totally at a loss to find anything analogous in the ordinary stem-leayes ” to this transverse or vertical multiplication of parts, in- clines to consider such appendages as those of the petals of Silene, Sapindus, Ranunculus, &c. as deformed glands, and the stamens thus situated, whether singly or in clusters, as developments of new parts in the axil of the petals, &. It appears to us, however, that the leaves do furnish the proper analogue of such appendages as those of Fig. 378-381, and the similar petaloid scales of Sapindacez, Erythroxyles, and the like, in the ligule of Grasses, and the stip- ules. The former occupies exactly the same position. The latter form an essential part of the leaf, and usually develop in a plane parallel with that of the blade, but between it and the axis; particularly when they are of consider- able size, and serve as teguments of the bud, as, for example, in Magnolia (Fig. 156). The combined intrapetiolar stipules of Melianthus furnish a case in point, to be compared with the two-lobed internal scale of the stamens in Lar- rea, the two-cleft adnate appendage of the petals in Caryophyller, Sapindus, &c.; and instances of cleft or appendaged stipules may readily be adduced to show that such bodies are as prone to multiplication by division as other foliar parts. The supposition of a.true axillary origin of the organs in question, therefore, appears to be gratuitous, and it would certainly introduce necdless complexity into the theory of the flower. Nor does it throw any light upon their morphology to call such appendages of petals “deformed glands ”’ ; a term which is much too vague to have any assignable morphological value. In Linum true stipules are reduced to glands. At present, therefore, we think that the same general name may properly enough be employed both for the collateral and the vertical multiplication of organs, where two or more bodies occupy the place of one, carefully distinguishing, however, the two different cases. Some special term is needful for discriminating between such multiplication and that by the regular augmentation of floral organs through the development of addi- tional circles, and none the less so, because we recognize, in one or both kinds of chorisis, modes of division which are common to the floral organs and to the foliage. 248 THE FLOWER. a scale-like appendage; the petals of Sapindus, Cardiospermum, &e., a petaloid scale quite unlike the original petal; the petals of Parnassia, a cluster of bodies resembling sterile filaments united below. 460. The Anteposition or saperposition of parts which normally alternate in the flower has in some cases been regafded as a case of transverse chorisis; but it is susceptible of a simpler explanation. The principal case that occurs is that of the stamens, or the outer- most circle of stamens, being placed directly before the petals (in ordinary botanical lan- guage opposite the petals). The Vine (Fig. 384-386) and the Buckthorn families are good examples of this anomaly, as also is Clay- tonia in the Purslane fam- ily. And in Linden and many of its allies a cluster of stamens (Fig. 382, 883) stands be- 384 385 fore each petal, the American Lindens having also a petal-like scale in the centre of every cluster. The clusters must be viewed as multiplications of single stamens by collateral chorisis. The position of the stamens before the petals in these cases, as well as that of the numerous petals in certain double Camellias, arranged through- out in five vertical ranks, is most readily explained by supposing a re- turn to the regular 2 or five-ranked phyllotaxis of leaves (240). 461. In the genuine Geranium (Fig. 421) the position of the outer of the two sets of stamens before the petals evidently results from the abortion of an exterior circle (486) ; and perhaps this is the case in the Primrose family also. In the Barberry family there is an apparent anteposition of the sepals, petals, and stamens through- FIG. 382. Diagram of the flower of the American Linden, in a cross-section of the bud. 883. A cluster of stamens with the petal-like body in the middle. FIG. 384. Flower of the Grape, casting its petals before expansion. 385. The same, with- out the petals: both show the glands distinctly, within the stamens. 386. Diagram of the flower. ° COALESCENCE OF ITS PARTS. 249 out. But this arises from the symmetrical augmentation of each set of organs into two circles, which in the expanded flower appear like one. In the flower-bud of the Barberry the calyx is seen to consist of two alternating circles of sepals, three in each; the corolla, of two circles of petals, three in each ; the three exterior petals alternating as they should with the inner circle of sepals, and the three interior ones alternating with these. But when the flower opens, the six petals, spreading apparently as one whorl, are necessarily opposed to the six sepals; and the six stamens in two circles, which are still more confluent into one whorl, are equally opposed to these, taken six and six ; although they really alternate in circles of three. In other words, decussating verticils of threes necessarily form six vertical ranks (251, 441). It is just the same in the Lily, Crocus, and most Monocotyledonous plants; where the perianth is composed of six similar leaves in two circles, and the andrecium of six stamens in two circles, giving a regular alternation in threes; although, when taken by the casual observer as composed of two circles of six, it gives the appearance of six stamens before as many petals. 462. The Coalescence or union of the parts of the same whorl or set of organs is so frequent, that few cases are to be found in which it does not occur, to a greater or less extent, in some portion of the flower. When the sepals are thus united into a cup or tube, the calyx is said to be monosepalous, or, more correctly, gamosepalous ; when the petals are united, the corolla is said to be monopetalous, or gamopetalous. The latter is the appropriate term, as it denotes that the petals are combined ; but the former is in common. use, al- though etymologically incorrect, as implying that the corolla consists of asingle petal. The current names, in these cases, were given long before the structure was rightly understood. So, also, such a calyx or corolla is said to be entzve, when the sepals or petals are united to their very summits ; or to be toothed, lobed, cleft, or parted, according to the degree in which the union is incomplete ; this lan- guage being employed just as in the case of the division of leaves (281). On the other hand, when the sepals are not united, the calyx is said to be polysepalous ; and when the petals are distinct, the corolla is said to be polypetalous; that is, composed of several petals. 463. The union of the stamens with each other may occur either by their filaments, as in the Pea and most of the Pulse family, or by their anthers, as in the Sunflower and the whole Composite family, or 250 THE FLOWER. by both the filaments and the anthers, as in Lobelia and the Gourd. An account of the modes of such union, and of the terms employed to express them, may be found in Section VI. The union of the pistils is still more common than that of stamens, and is illustrated in Section VII. 464. The terms union, cohesion, and the like, must not be under- stood to imply that the organs in question were first formed as distinct parts, and subsequently cohered. This is seldom the case. The union is congenital; the members of a gamosepalous calyx, a gamopetalous corolla, &¢. showed their union from the earliest period. The language we use has reference to our idea of these parts, as answering each to a single leaf. We might more cor- rectly say that the several leaves of the same cirele have failed to ~ isolate themselves as they grew. The same remark applies to the analogous case of 465. Adnation, or Consolidation, the union of different circles of floral organs with one another. This may take place in various de- grees. It presents the appearance of one circle or set of parts grow- ing out of another, as the corolla out of the calyx, the stamens out of the corolla, or all of them out of the pistil; and therefore disguises the real origin of the floral organs from the receptacle or axis, in successive series, one within or above the other (421). The con- sideration of the flower as respects such consolidation, or its ab- sence, gives rise to three terms which are much used in descrip- tive botany, and which the student should thoroughly understand, viz. hypogynous, perigynous, and epigynous. 466. The first of these terms applies to the case in which there is no adnation or consolidation of unlike parts. That is, when the calyx, corolla, and stamens are borne (i. e. inserted) on the receptacle, they are said to be hypogynous (from two Greek words meaning under the pistil), as in Buttercup, Flax (Fig. 887), &e. The floral organs in such cases are also said to be free ; which is the term opposed to FIG. 387. Vertical section of a flower of the Common Flax, showing the normal or hypo- gynous insertion of parts. CONSOLIDATION OR ADNATION. 251 the adhesion of one organ to another, as that of dist/nct is to the cohesion of the parts of the same whorl or set of organs. Thus, the stamens are said to be distinct, when not united with each other, and to be free, when they contract no adhesion to the petals, sepals, or pistils; and the same language is equally applied to all the floral organs. The word connate (born united) is applied either to the congenital union of homogeneous parts (as when we say that the two leaves of the upper pairs of the Honeysuckle are connate, Fig. 294, the sepals or stamens are connate into a tube, or the pistils into a compound pistil), or to the coalescence of heterogeneous parts (as that of the petals with the calyx, or of both with the pistil). But the word adnate belongs to the latter case only. 467. When such consolidation takes place, and the petals and stamens (which almost always accompany each other), or either of them, are inserted on the calyx, i. e. are adnate with the base of the calyx (as in the Cherry, Fig. 388, or Purslane, Fig. 389), they are said to be perigynous (liter- ally, placed around the pis- til). The real origin of the parts must be the same as in the former case, that is, the parts really belong to the re- ceptacle, in successive circles, one above or within the other, first the sepals, then the pet- als, within these the stamens, and within or above these the pistils ; but the true origin or position of some of the parts is here obscured by the adnation, at their base at least, of parts which are normally separate. In Fig. 388, the petals and stamens are adnate to the lower part of the calyx, but all are free from the pistil. But in Fig. 389, all four organs are consolidated below, as far as to the middle of the ovary. , FIG. 888. Vertical section of a flower of the Cherry, to show the perigynous insertion of the petals and stamens. FIG. 889. Similar section of the flower of the Purslane, showing an adnation of parts with the lower part of the overy. 252 THE FLOWER. 468. In the Apple, Hawthorn (Fig. 390), and many other plants, the consolidation extends farther, and the calyx is adnate to, i. e. invests and coheres with the whole surface of the ovary, which accordingly appears to be under the rest of the flower, instead of the upper- most and innermost part, as it properly is. The earlier botanists called the flower, or calyx, in such cases, supe- rior, and the ovary and fruit inferior ; and when no such consolidation occurs, the flower, or calyx, &e. was said to be tnferior, and the ovary superior. But these terms should be superseded by the equivalent and much more appropriate expressions of calyx adherent, in the one case, and calyx free, in the other; or by that of ovary coherent with the calyx, and ovary free from the calyx, which is the same thing in other words.* More commonly the corolla and the stamens are adnate to the calyx beyond where these parts all separate from the pistil; in which case they are still perigynous, or borne on the calyx. In some such cases, as in the Evening Primrose and Fuchsia, the tube of the calyx is prolonged far beyond the ovary, and the petals and stamens are inserted on it just below where it separates into its distinct lobes. 469. In other flowers the petals and the stamens are distinct at the line where the calyx separates from the top of the ovary, or are borne on the edge or face of a thickened disc (489) which crowns its summit, as in Aralia (Fig. 410), the Ivy, and all that family, in the whole Parsley family, the Cornel family, the Cranberry (Fig. 391), and the like. The stamens, &c., being then apparently borne on the ovary, are said to be epigynous (from two Greek words meaning “on the pistil”). * A favorite view at present is that the calyx in many cascs (as in the Rose, Apple, &c.) actually begins at the place where it is distinct from the parts with- in, and that the so-called tube is the summit of the peduncle hollowed out, or developed around the pistils. This view can be correct in certain cases only, and the difference between it and the current view is really not so great as it seems. FIG. 390. Flower of Ifawthorn vertically divided, to show the calyx adnate to the ovary. ITS IRREGULARITY. 253 470. In some few plants the stamens continue this adnation a little further, and cohere with the style, either with its base only, as in some species of Asarum, or with its whole length, as in Cypripedium (Fig. 468) and the whole Orchis family. Then the flower is said to be gynandrous ; —from two Greek words equivalent in mean- ing to stamens and pistil com- bined (519). 471. Vrregularity, The flower is trregular when the parts of its different circles, or of one or more of them, are not all alike in number, shape, or size. Irregularity may be the re- sult, therefore, either of the abortion or dis- appearance of some parts, or of their wn- equal development or unequal union. The latter case may be first considered. 472. The Pea tribe affords a familiar illustration of ¢rregular flowers arising from the unequal size and dissimilar form of the floral envelopes ; especially of the corolla, which, from a fancied resemblance to a butterfly in the flower of the Pea, Locust (Fig. 392), &c., has been called papilionaceous. The petals of such a corolla are dis- tinguished by separate names ; .}»the upper one, which is usually - most conspicuous, being termed the vexillum, standard, or banner (Fig. 892’, a); the two lateral (6) are called wings (ale), and the two lower (c), which are usually somewhat united along their anterior edges, and together FIG. 891. Flower of Cranberry divided lengthwise, showing the petals and stamens epi~ gynous. FIG. 392. Front view of a flower of the common Locust-tree (Robinia Pseudacacia). FIG. 392’. Corolla of the same, the petals displayed. 22 254 THE FLOWER. form a body in shape resembling the keel, or rather the narrow prow, of an ancient vessel, are named the carina or keel. The calyx of the same blossom is slightly irregular by the unequal union of parts, the two upper sepals being united higher than the other three. In Baptisia these two sepals are coalescent to the tip, or nearly so, causing the calyx to ap- pear as if formed of four sepals instead of five In most Lupines, not only are the two upper sepals coa- lescent into one body near- ly or quite to the tip, but the three remaining ones are likewise united into one body, on the lower side of the flower, thus giving the calyx the appearance of consisting of two petals in place of five. The ir- regularity of papilionaceous flowers likewise affects the stamens, which, although of symmetrical number, viz. ten, or two circles, are in most cases unequally coalescent, nine of them being united by the cohesion of their filaments for the greater part of their length, while the tenth (the posterior) stamen is distinct ; as is illustrated in the sec- tion on the stamens (518). But in Amorpha (Fig. 395), which belongs to the same tribe of plants, the ten stamens are united barely at their base; and there is a complete return to regularity in those of Baptisia (Fig. 394) and Sophora, which are perfectly distinct or separate. The Violet (Fig. 397) offers another very familiar form of irregu- lar flowers; the irregularity belonging FIG. 898. Papilionaceous flower of Baptisia, 394. The same, with the petals removed, showing the ten distinct stamens. FIG. 895. Flower of Amorpha, 395’, The same, with the solitary petal removed, showing the slightly monadelphous stamens. FIG. 396. Flower of Viola sagittata, 397. Its sepals and petals displayed. SUPPRESSION OR ABORTION OF PARTS. 255 mainly to the corolla, the lower petal of which is prolonged back- ward into a sac or spur. ‘The Larkspur and Monkshood (Fig. 398- 402) are irregular both in the calyx and the corolla, not only by a diversity in the size and shape of homologous parts, but also by the suppression of some of them. We may therefore consider them under the next head. 473, Of irregular monopetalous flowers the most common form is the dilabiate or two-lipped, as in the corolla of the Sage, Snap- dragon, and most of the large families to which they belong (Fig. 460): this, like the calyx of the Lupine, described above, arises from the unequal union of the parts. The same is the case with the two-lipped corolla of the Woodbine and other Honeysuckles, only here, instead of two lobes or petals forming the upper lip and three the lower, four petals enter into the composition of the upper lip, leaving only one for the lower (Fig. 861). The Trumpet Honeysuckle returns nearly to regularity again, the whole five petals being coalescent into a tube to near the top, leaving an al- most equally five-lobed border. The corollas of Germander (Fig. 996) and of Lobelia (Fig. 902) are further irregular by a want of union on the upper side of the blossom: and the ligudate or open and strap-shaped corolla of Coreopsis (Fig. 325, ¢) and other Com- posite evidently answers to such a regular monopetalous corolla as a, split down on one side and outspread. 474. Suppression or Abortion, that is, the complete or the partial obliteration of some member, is a common cause of irregularity. The term suppression is used when parts which belong to the plan of the blossom do not actually appear in it. The term abortion is applied not only to such disappearance, but to partial obliteration, as where a stamen is reduced to a naked filament, or to a mere rudi- ment or vestige, answering to a stamen and occupying the place of one, but incapable of performing its office. Such obliteration, whether partial or complete, may affect either a whole circle of organs or merely some of its members. The former interferes with the completeness of a flower, and may obscure the normal order of its parts. The latter directly interferes with the symmetry of the blossom, and may be first considered. 475. Suppression of some Parts of a Circle of Organs. The Larkspur and Aconite or Monkshood furnish good examples of flowers which are both irregular and symmetrical. The calyx of the Larkspur (Fig. 398, 399) is irregular by reason of the dissimilarity of the five 256 THE FLOWER. sepals, one of which, the uppermost and largest, is prolonged. poste- riorly into a long and hollow spur. Within these, and alternate with 399 400 them as far as they go, are the petals, only four in number, and these of two shapes, the two upper ones having long spurs which are re- FIG. 398. Flower of a Larkspur. 899. The five sepals (outer circle) and the four petals (inner circle) displayed. 400. Ground-plan of the calyx and corolla. FIG. 401. Flower of an Aconite or Monkshood 402. The five sepals and the two small and curiously-shaped petals displayed: also the stamens and pistils in the centre. 403. Ground-plan of the calyx and corolla; the dotted lines, as in Fig. 400, representing the sup- pressed parts. SUPPRESSION OR ABORTION OF PARTS. 257 ceived into the spur of the upper sepal ; the two lateral ones having a small but broad blade raised on a stalk-like claw; and the place which the fifth and lower petal should occupy (marked in the ground plan, Fig. 400, by a short dotted line) is vacant, this petal being sup- pressed, thereby rendering the blossom unsymmetrical. In Aconite, (Fig. 401, 402) the plan of the blossom is the same, but the upper- most and largest of the five dissimilar sepals forms a helmet-shaped or hood-like body ; and as to the petals, three are wanting altogether (their places are shown by the dotted lines in the ground plan, Fig. 403) ; the two upper ones, which extend under the hood, only re- main, and these are so reduced in size and so anomalous in shape that they would not ordinarily be recognized as petals. One of them enlarged is exhibited in Fig. 404. Petals, &c. of this and other extraordinary forms were termed by Linneus Wectarves, an unmeaning or mislead- ing name, as they are no more likely to secrete honey than ordinary petals are. 476. The papilionaceous corolla (472) becomes strikingly unsymmetrical by suppression in Amorpha (Fig. 3895). Here the corolla is uniformly reduced to a solitary petal (the standard), the other four petals being totally obliterated. This obliteration is foreshadowed in Ery- thrina herbacea of the Southern States, and other species, in which all the petals except the standard are small and inconspicuous. While the blossom of the common Horsechestnut, although irregular, is symmetrical, so far as respects the calyx and corolla, that of our nearly related Buckeyes gener- ally wants one of the five petals, a vacant place on the anterior side of the flower indicating its absence. 477. The suppression or abortion of some of the stamens requisite to the symmetry of the blossom is very common. According to the ordinary view, the six stamens of the flowers of the Mustard family (Fig. 405, 406), where the sepals and petals are in fours, is explained by supposing that, out of two circles of stamens, four in each, two stamens of the outer circle are FIG. 404, One of the petals of an Aconite or Monkshood, enlarged. FIG. 405. Flower of Mustard. 406. Its six stamens and the pistil, enlarged. 22 * 258 THE FLOWER. suppressed. But we incline to the opinion that this sort of flower is rendered unsymmetrical, not by the suppression of two short sta- mens, but by the chorisis or division of the two stamens each into a pair (456, Fig. 368). 478. Most flowers which are irregular by the unequal union of aay the petals, especially those with a d- : ne Ba i aN 7 labiate corolla (473, 511), are likewise ' . | \ A ies unsymmetrical by the abortion of one f ¢ i or more of the stamens. In the Cat- nip, Balm, &c., and in the Snapdragon, Monkey-flower, Foxglove, and the like, as also in Gerardia (Fig. 407), where the corolla is only slightly ir- regular, four stamens occupy their proper places alternate with its lobes, but the fifth stamen is altogether want- ing. In its place, however, the corolla of the Figwort, belonging to the same family as the Snapdragon and Ge- rardia, bears a small scale, and that of Chelone and Pentstemon (Fig. 408) bears an antherless filament, which, from its position, must be the wanting stamen, in an abortive state; and in one species it has actually been found with a perfect or an imperfect anther, completing the symmetry of the flow- er. The four perfect stamens in these cases are of unequal length, two of them being longer than the other two (i. e. they are didynamous, 520). The two shorter stamens also disappear in many such plants, as in Gratiola or Hedge-Hyssop, — sometimes leaving vestiges in their place, and sometimes not; also in Sage, Horse-Mint, and the like. Here three stamens out of five are suppressed. So they commonly FIG 407. Corolla of Gerardia purpurea laid open, with the four stamens the place which the fifth should occupy indicated by a cross FIG. 408. Corolla of Pentstemon grandiflorus laid open, with its four stamens, and a sterile filament in the place of the fifth stamen. FIG. 409. Corolla of Catalpa laid open, with two perfect stamens and the vestiges of three abortive ones. SUPPRESSION OR ABORTION OF PARTS. 259 are in the blossom of Catalpa (Fig. 409), but their vestiges remain in the form of small sterile filaments, two of which, however, occa- sionally bear anthers, either perfect or rudimentary. 479. The suppression of a portion of the pistils required to com- plete the symmetry of the flower is exceedingly common. The tendency to obliteration seems to increase as we advance towards the centre of the blossom, owing, doubtless, to the greater pressure exerted on the central parts of the bud, and the progressively di- minished space the organs have to occupy on the conical receptacle. Thus, while the corolla, when present at all, almost always consists of as many leaves as the calyx, the members of the stamineal circle or circles are frequently fewer in number, and the pistils are still more commonly fewer, excepting where the axis is prolonged for the reception of numerous spiral cycles. Thus, the pistils, which present the symmetrical number in Sedum, and all plants of that family (Fig. 834, 835, 355, 361), are reduced to two, or rarely three, in the allied Saxifrage family, while the other floral circles are in fives. So, in the Wild Sarsaparilla (Fig. 410) and Spikenard, the flowers are pentamerous throughout, although the ovaries of the five pistils are united into one; but they are reduced to three in the Ground-nut, and to two in the Ginseng, belonging to the same genus, as also in all Umbelliferous plants. Although the pistils are in- definitely augmented in the Rose, Strawberry, and the greater part of Rosaceous plants, or are of the normal number five in Spirea, yet there are only two in Agrimonia, one or rarely two in Sangui- sorba, and uniformly one in the Plum and Cherry (Fig. 888), although the flowers of the whole order are formed on the pentame- rous, or sometimes the tetramerous plan, and with a strong tendency to augmentation of all the organs. And the Pulse family has, almost without exception, five members in its floral envelopes, and ten, or two circles, in its stamens, but only a single pistil (Fig. 358). 480. Suppression of one or more whole Circles. A complete flower, as already remarked (416), comprises four whorls or sets of organs ; namely, calyx, corolla, stamens, and pistils. When any of these four circles or kinds of organs are wanting, the flower is said to be 7n- complete. The non-production of any one or more of the whorls is not uncommon. The calyx, however, is seldom if ever wanting when the corolla is present, or rather, when the floral envelopes con- sist of only one whorl of leaves, they are called calyx, whatever be their appearance, texture, or color, unless it can somehow be shown 260 THE FLOWER. that an outer circle is suppressed.* For since the calyx is fre- quently delicate and petal-like (in botanical language petaloid or colored), and the corolla sometimes greenish or leaf-like, the only real difference between the two is, that the calyx represents the outer, and the corolla the inner serics ; and even this distinction becomes more or less arbitrary when either, or both, of these or- gans consist of more than one circle. The apparent obliteration of the calyx in some cases is owing to the entire cohesion of the tube with the ovary, and the reduction of the free portion, or limb, to an obscure ring or border, either slightly toothed or entire, as in Aralia (Fig. 410), Fedia (Fig. 882), Cornus, the fertile flowers of Nyssa, &c. In Composite, the partially obliterated limb of the 410 calyx, when present at all, consists of scales, teeth, bristles, or a ring of slender hairs (as in the Thistle), and receives the name of pappus. 481. The petals, however, are frequently absent ; when the flower is said to be apetalous, as in the Anemone (Fig. 411), Clematis, Caltha, &c., in the Crowfoot family, other genera of which are furnished with both calyx and corolla; and as in some species of Buckthorn, while others have manifest although small petals. They are constantly wanting in a large number of families of Ex- ogenous plants, which on this account form the division Apetale. When the calyx is present while the corolla is wanting, the flower is said to be monochlamydeous, that is, with a perianth (417) or floral envelope of only one kind; as in the cases above mentioned. *In our Northern Zanthoxylum the monochlamydeous perianth which is present may, however, be justly held to be the corolla, and not the calyx, be- cause the five stamens alternate with it, just as they do with the undoubted petals of Z. Carolinianum ; in this case, therefore, we may say that the calyx, and not the corolla, is suppressed. ‘Sce Crenera Illustrata, Vol. 2, p. 148, tab. 156." FIG. 410. Flower of Aralia nudicaulis, vertically divided ; the limb of the calyx obsolete. FIG. 411, Flower of Anemone Pennzylvanica ; apetalous, the calyx petaloid. SUPPRESSION OR’ ABORTION OF PARTS. 261 482. In some flowers, moreover, as in the Lizard’s-tail (Fig. 412), both the calyx and the corolla are entirely wanting, and the blossom is achlamydeous, i. e. destitute of any perianth or floral envelopes whatever. Having the es- sential organs, viz. the stamens and pistils, how- ever, this flower also is perfect (hermaphrodite, or bisexual), although ¢ncomplete. 483. The abortion of all the stamens or all the pis- tils of a flower is common enough, as well in flowers that have as in those that have not complete floral envelopes ; but whenever either of these essential organs are abortive or wanting in some blossoms, they are present in others of the same species, either on the same or on different individuals. Flowers of this kind having stamens only or pistils only are said to be separated, diclinous, or untsexual. And the flower which has the stamens but no pistils, or only imperfect ones, is said to be staminate, sterile, or male ; while that provided with pistils, but with no stamens, or only im- perfect ones, is pis- tillate, fertile, or fe- male. Not to multi- ply examples, in Smi- lax and in Menisper- mum (Fig. 418, 414) we have good instan- ces of separated flow- ers in which the abor- tion is confined to the stamens or the pistils, the floral envelopes being present and FIG. 412. Flower of Lizard’s-tail (Saururus cernuus), magnified. FIG. 413. A staminate flower of Menispermum or Moonseed. 414. A, pistillate flower of the same. The latter has six abortive stamens: the former, mere vestiges of pistils. FIG. 415. A catkin of staminate flowers of Salix alba, 416. A single staminate flower de- tached and enlarged (the bract turned from the eye), 417. A pistillate catkin of the same species. 418 A detached pistillate flower, magnified, 262 THE FLOWER. complete. And in the Willow (Fig. 415-418) we have separated flowers extremely simplified by abortion. The flowers are crowded in catkins, each one in the axil of a bract: the staminate flowers consist of a few stamens merely, in this species of only two (Fig. 416), and the pistillate, of a pistil merely (Fig. 418). That is, the flowers are wholly destitute of calyx and corolla (unless a little glandular scale on the upper side should be a rudimentary perianth of a single piece), and in one set of blossoms the stamens are also suppressed ; in another, the pistils. The stamens vary in number in different species, from two to five. If there were only one of the latter, an instance would be afforded of flowers reduced, not merely to one kind of organ, but to a single member. Now there is one species of Willow, which ap- pears to have its sterile blossoms reduced to a solitary stamen. It has therefore been named Salix monandra. But on in- spection this seemingly single stamen is found to consist of two united with each other quite to the top (Fig. 419). Here, as in many other cases, the normal condi- tion of the flower is not only much altered by the sup- pression of most of the organs, but disguised by the coa- lescence of those that remain. 484. In separated flowers the two kinds of blossoms may be borne either upon different parts of the same individual, or upon entirely different individuals. The flowers are said to be monecious when both kinds are borne on the same plant; as in Indian Corn, the Birch, the Oak, Beech, Hazel, Hickory, &e. : and they are called diéweous when borne by different individuals; as in the Willow and Poplar, the Sassafras, the Prickly Ash, the Hemp and Hop, Moonseed (Fig. 413, 414), &e. Occasionally, while some of the flowers are staminate only, and others pistillate only, a por- tion are perfect, the different kinds occurring either on the same or different individuals ; as in most Palms, in many species of Maple, &ce.: plants with such flowers are said to be polygamous. 485. In some of the blossoms of certain plants both stamens and pistils are wanting. This is the case with those that occupy the margin of the cymes of the Hobblebush and some other Viburnums, and of Hydrangea (Fig. 420), or even with the whole cluster in cultivated monstrous states, as in the Snowball or Guelder-Rose of the gardens (Viburnum Opulus). Here the enlarged corollas FIG 419 Astaminate flower of Salix purpurea (or monandra), with the stamens coalescent (monadelphous and syngenesious), so as to appear like a single one, SUPPRESSION OR ABORTION OF PARTS. 263 make the whole blossom. Such flowers, being neither staminate nor pistillate, are said to be neutral. In so-called compound flowers (394) the strap-shaped marginal flowers are sometimes neutral, as in Coreopsis (Fig. 324, 8325), Mayweed, and Sunflower. In some Grasses and other plants such neutral flowers want the floral en- velopes also, or are reduced to an abortive rudiment. 486. The suppression or abortion of a whole circle of organs in a symmetrical flower does not destroy its symmetry, if we take note of the absent members. Thus a monochlamydeous flower, with a single full circle of stamens, usually has the latter placed opposite the leaves of the perianth, that is, of the calyx, the corolla or in- tervening circle having failed to appear. But when, with the abor- tion of the primary circle, say of the stamens, we have an augmenta- tion of one or more additional circles of the same kind of organ, the law of alternation appears to be violated; the stamens that are present, or the outer circle of them, standing before the petals, in- stead of alternate with them. It is customary to assume this ex- planation for all cases of the anteposition of the stamens to the pet- als, whether in the Primrose family, in Claytonia, in the Vine (Fig. FIG. 420. Cyme of Hydrangea arborescens, with the large marginal flowers neutral 264 THE FLOWER. 384), or the Buckthorn, &c. But more probable explanations for some such cases have already been given (459, 460). It can no longer be deemed sufficient to assume the obliteration of a normal floral circle, and the production of a second one, when no traces of the former can be detected and no clear analogy shown with some strictly parallel instance. Yet we may confidently apply this view when we do find traces of obliterated organs, as in the Geranium family, for example. The pentamerous flower of Geranium exhibits ten stamens, plainly occupying two rows, the five of the exterior circle shorter than the others. One set of these stamens alternates with the petals, the other is opposed to them. But on close exami- nation, we perceive that it is the ¢nner circle of stamens that alter- nates with the petals ; those of the outer circle stand directly before them. This is a not uncommon case where there are just twice as many stamens as there are petals or sepals. In this instance the explanation of the anomaly is furnished by ga the five little bodies, called by the vague and ( an ~ convenient name of glands, which stand on 00 9 ( WA the receptacle between the petals and the sta- \ CO a) mens, and regularly alternate with the former. soy, They accordingly occupy the exact position of the original stamineal circle: wherefore, as aes situation is the best indication of the nature of organs, we may regard them as the abortive rudiments of the five proper stamens, here obliterated. In the annexed diagram (Fig. 421) these are accordingly laid down in the third circle, as five small oval spots, slightly shaded. The actual stamens consequently belong to two augmented circles, those of the exterior and shorter set of which (represented by the larger, unshaded figures), normally alternating with the glands, are of course opposed to the petals, and those of the inner and larger set, normally alternating with the preceding, neces- sarily alternate with the petals. This view is further elucidated by the closely allied genus Erodium, where all the parts are just the same, except that the five exterior actual stamens are shorter still, and are destitute of anthers; that is, the disposition to suppression, which has caused the obliteration of the primary circle of stamens and somewhat reduced the second in Geranium, has in Erodium FIG. 421. Diagram (cross-section) of the flower of Geranium maculatum, exhibiting the relative position of parts, especially the glands alternate with the petals, and the two rows of stamens within them. SUPPRESSION OR ABORTION OF PARTS. 265 rendered the latter abortive also, leaving those of the third row alone to fulfil their proper office. And in a South African genus, Monso- nia, five stamens actually occur in the place of these glands, making fifteen real stamens, or three circles. The general plan of the flower is the same in the Flax family, except that the glands which answer to the outer rank of stamens are still less conspicuous, and those of the next circle are reduced to small abortive filaments, or to minute teeth in the ring formed by the union of all the filaments into a cup at the base, leay- ing five perfect stamens, which, though they alternate with the petals indeed, belong to a third circle (Fig. 422, 423). Ina few species of Flax, this second circle of stamens is perfectly obliterated, so that no vestige is to be seen. 487. The complete suppression of two or three of the circles be- longing to the complete flower, and of a part of the members of what remains, reduces a blossom to the last degree of simplicity. Among the simplest of perfect flowers are those of Callitriche (Fig. 1136 — 1188), which have neither calyx nor corolla; and only one stamen, as is expressed in the annexed diagram (Fig. 424); yet the four- lobed pistil shows that the blossom was o : ; constructed on the & dB 2 0) o plan of four. And Z ee ee even this stamen is suppressed in cer- tain blossoms, and the pistil in others. In Euphorbia (also to be illustrated under the family to which it belongs, Fig. 1143) the flowers are always separated, and the staminate blossom is reduced to a single stamen, the pistillate to a single three-lobed pistil (Fig.425). And in the Willow, as already noticed (438), the pair of stamens which represents one sort of blossom, and the single pistil which repre- sents the other, are widely separated, being borne on distinct trees. FIG. 422. Flower of Linum perenne. 423. Its stamens and pistils enlarged. FIG. 424. Diagram of a perfect flower of Callitriche, with no floral envelopes, one stamen, and a four-celled pistil. FIG. 425. Diagram of the monecious flowers of Euphorbia: a, the pistillate flower re- duced to a mere three-celled pistil; and b, one of the staminate flowers reduced to a single stamen. FIG. 426. Diagram of the dicecious flowers of the Willow: a, one of the pistillate flowers reduced toa solitary pistil; 6, a staminate flower reduced to a pair of stamens. 23 266 THE FLOWER. 488. Unusual States of the Receptacle ‘The receptacle (421) is commonly small, short, and inconspicuous, being merely the extrem- ity of the flower-stalk upon which the sev- eral organs are inserted (Fig. 843). Some- times, however, it is remarkably enlarged or elongated. A striking instance of an en- larged receptacle is found in Nelumbium, where it is dilated into a large top-shaped body, nearly enclosing the pistils in sep- arate cavities (Fig. 427). Whenever the pistils of a flower are very numerous, the receptacle is more or less enlarged for their insertion, as in Magnolia, the Raspberry and Blackberry, &e. In the Strawberry the enlarged and conical receptacle (Fig. 428), bearing the pistils on its surface, becomes the edible portion in fruit. In the Rose (Fig. 429) the receptacle is deeply concave, instead of convex, being urn- shaped, invested by the adnate tube of the calyx, and bearing the petals and stamens on its bor- der and the numerous pistils on its whole hol- low surface (Fig. 429). It is much the same in Calycanthus (Fig. 814 —- 819). In Geranium, and many allied plants, the receptacle is prolonged between the ovaries, and coheres with their styles (Fig. 430); these, however, separating at maturity (Fig. 431). In Umbelliferous plants a similar but more slender prolongation of the receptacle is extended upwards between the contiguous faces of the two united ovaries which form the fruit 430 FIG. 427. The enlarged, top-shaped receptacle of Nelumbium, bearing the pistils, im- mersed in hollows of its upper face. FIG. 428. Longitudinal section of a young strawberry, enlarged. FIG. 429. Similar section of a young Rose-hip. FIG. 430. Gynacium of Geranium maculatum, or Cranesbill, enlarged. FIG. 431. The same at maturity, with the five pistils splitting away from the long beak or receptacle and hanging from its top by their styles. THE RECEPTACLE, DISK, ETC. 267 in that family. Occasionally one or more of the internodes between successive floral circles elongate; as between the calyx and the corolla in Pinks, and especially in Silene, forming a stalk within the calyx, on which the rest of the flower is raised (Fig. 432) ; while in many Gentians the inter- : node above the circle of : stamens is developed, rais- J ing the pod on a stalk of its \ Va own. This is a common case in the Caper family ; in which the genus Gynan- : dropsis (Fig. 433) exhibits a remarkable development of the whole receptacle. It is enlarged into a flattened disk, where it bears the pet- als, and is then prolonged into a conspicuous stalk which bears the stamens,— or rather, to which the bases of the stamens are adnate, — and then into a shorter and more slender stalk for the pistil; thus separating the four circles or sets of organs, like so many whorls of verticillate leaves. The general name for this kind of stalk, as contradistinguished from the pedicel or stalk of the flower, is the Stipr ; and whatever organ or set of organs is thus elevated is said to be stipitate. Whenever it is necessary to particularize the portion of the receptacle thus devel- oped, the stipe is termed the Anthophore when it appears just above the calyx, and elevates the petals, stamens, and pis- tils; the Gonophore, when it supports both the sta- mens and pistils; and the Gynophore, Gynobase, or Carpophore, when it bears the gynacium alone. The stalk which sometimes supports each simple pistil of the gynecium (as in Coptis or the Goldthread) is called a Thecaphore. This, however, does not belong to the receptacle at all, but to the pistil itself, and is ho- mologous with the leafstalk. 489. A Disk is a part of the receptacle, or a growth from it, en- larged under or around the pistil. Like the other parts of the flower, 432 FIG. 432. Section of a flower of Silene Pennsylvanica, showing the stipe or anthophore. FIG. 433. Flower of Gynandropsis, with a remarkably elongated receptacle. FIG. 484. Disk of the Orange, underneath the pistil (hypogyuous). 268 THE FLOWER. it is hypogynous (466), when free from all union either with the pis- til or the calyx, as in the Rue and the Orange (Fig. 434). It is perigynous (467), when it adheres to the base of the calyx, as in the Buckthorn (Fig. 435, 436); and where the calyx is adnate to the ovary, as in the Apple, Hawthorn (Fig. 3890), &e., there is commonly a disk in- terposed between the two. The disk is sometimes expanded on the summit of such an ovary, when it is said to be epigynous (469), as in Cornus, and all Umbelliferous plants. ‘ Secr. V. Tue Frorat ENvrLores 1X PARTICULAR. 490. Their Development, or Organogeny, first requires a brief notice. The flower-bud is formed in the same way as the leaf-bud; and what has been stated as to the formation of the leaves of the branch (273) equally applies to the leaves of the flower. The sepals are necessarily the earliest to appear, which they do in the form of so many cellular protuberances, at first distinct, inasmuch as then their tips only are eliminated from the axis. Each one may complete its development separately, like an ordinary leaf, when the sepals re- main distinct. Or the lower and later-climinated portions of the forming organs of the circle coalesce as they grow into a ring, which, farther developed in union, forms the cup or tube of the gamophyl- lous calyx: In some cases, it would appear that the sepals may at first grow separately, and afterwards, though only at a very early period, coalesce by the cohesion of their contiguous parts. The sey- eral parts of an irregular calyx are at first equal and similar; the irregularity appears in their subsequent unequal growth. The pet- als or parts of the corolla originate in the same way, a little later than the sepals. Their coalescence in the gamopetalous corolla is congenital; the ring which forms its tube appearing nearly as early as do the slight projections which become its lobes and answer to the summits of the component petals. The rudiments of the petals are visible earlier than those of the stamens: but their growth is at first FIG. 485. Flower of a Buckthorn, showing a large perigynous disk. 436. Vertical section of the same. ESTIVATION OR PRASFLORATION. 269 retarded, so that the stamens are earlier completed, and their anthers surpass them, or often finish their growth, while the petals are still minute scales: at length they make a rapid growth, and enclose the organs that belong above or within them. Unlike the sepals in this respect, the base of the petal is frequently narrowed into a portion which corresponds, more or less evidently, to the petiole (the claw), and which, like the petiole, does not appear until some time after the blade or expanded part; the summit being al- ways the earliest and the base the latest portion formed. As the envelopes of the flower grow and expand, those of each circle adapt themselves to each other in various ways, and acquire the relative positions which they occupy in the flower-bud. Their arrangement in this state is termed 491. Their Hstivation or Prefloration, ‘The latter would be the preferable term; but the former is in common use ; the word Zsti- vation (literally the summer state) having been devised for the purpose by Linneus;— for no obvious reason except that he had already applied the name of Vernation (the spring state) to express the analogous manner in which leaves are disposed in the leaf-bud. The same terms are employed, and in nearly the same way, in the two cases, but with some peculiarities. As to the disposition of each leaf taken by itself, the corresponding terms of vernation (257), wholly apply to wstivation. The arrangement in the bud of the several members of the same floral circle in respect to each other, is of much importance in systematic botany, on account of the nearly constant characters that it furnishes, and also in structural botany, from the aid it often affords in determining the true relative super- position or succession of parts on the axis of the flower, by observ- ing the order in which they overlie or envelope each other.. 492. The various forms of wstivation that have been distinguished. by botanists may be reduced to three essential kinds,.namely, the imbricative, the contorted or convolutive, and the valvular:* 493. Imbricative estivation, in a general sense, comprises all the modes of disposition in which some members of a floral circle are exterior to the others, and therefore overlie or enclose them in. * We should properly say of the estivation that it is dmbricative, convolutive,, valvular, &c., and of the calyx and corolla, or of the sepals, &c., that they are imbricate or imbricated, convolute, valvate, &c. in xstivation; but such precision: of language is seldom attended to. 23 * 270 THE FLOWER. the bud. This must almost necessarily occur wherever the parts are inserted at distinguishably different heights, and is the natural result of a spiral arrangement. The name is most significant when successive leaves are only partially covered by the preceding, as in Fig. 207. Here they manifestly break joints, or ave disposed like tiles or shingles on a roof, as the term dmbricated denotes. It is therefore equivalent to the spiral arrangement: and, on the other hand, we properly apply the term ¢mbricated to any continuous succession of such partly overlying members; as when we say of appressed and crowded leaves that they are imbricated on the stem, or thus express the whole arrangement of the scales of a bud (Fig. 153), or a bulb (Fig. 172), or of a catkin or cone (Fig. 209). The alternation of the petals with the sepals, &c. necessarily renders the floral envelopes likewise imbricated in the bud, taken as a whole. But in proper estivation, what we have to designate is the arrangement of the parts of the same floral circle (say the five sepals or the five petals) in respect to each other. 494, Now when the sepals or the petals are three in number, 7™\ and are regularly imbricated in 4 the bud, as in Fig. 487, the three ; Le \ leaves are arranged just as in three-ranked phyllotaxis (238, 438 Fig. 208); that is, with the first petal exterior to the others, the second is covered by the first on one side while it covers the third on the other. When they are five (as in the calyx of Geranium, Fig. 439), they are disposed just as in five-ranked or quincuncial phyllotaxis with the axis shortened (240, Fig. 206); viz. two leaves om are exterior, two wholly interior, and one (the if \ 437 third) with one edge covered by No. 1 on one side while it covers No. 5 with its other edge. So that this, the regular mode of imbrication when . ) the parts are in fives, is termed quineuncial es- tivation, or the parts are said to be guincuncially FIG. 487. Diagram of a three-leaved (trimerous) calyx and corolla, both imbricated in astivation. FIG 488. Diagram of the vestivation of three petals (or one circle of the petals) of Magno- Jia, similarly imbricated, but strongly enwrapping, each making nearly a circle. FIG. 489. Diagram of the imbricative sestivation of the calyx and the convolutive scstiva- tion of the corolla of Geranium ; the sepals numbered. ZSTIVATION OR PREFLORATION. 271 imbricated. We have here the advantage of being able to number the successive sepals, or petals, since the third leaf is not only recog- nizable by its intermediate position, but also indicates the direction in which the spiral turns (Fig. 206 and Fig. 439). 495. It must be recollected, in the comparison, that the parts of successive cycles are superposed in the foliage, while those of the ‘floral circles alternate. Regular imbrication in the 4-merous flower gives two outer and two inner members in estivation (as in the calyx of Cruciferous blossoms, Fig. 867), on the principle of two decussating pairs of leaves (441); or it may sometimes be refer- able to a modification of some alternate spiral arrangement. 496. The degree of overlapping depends upon the breadth of the parts and the state of the bud; it naturally grows less and less as the bud expands and is ready to open. It is from the full-grown flower-bud, just before anthesis (or the opening of the blossom), that our diagrams are usually taken ; in which the parts are represented as moderately or slightly overlapping. The same overlapping car- ried to a greater extent will cause the outer leaf to envelope all the rest, and each succeeding one to envelop those within ; as shown in Fig. 438 from one circle of petals of a Magnolia taken in an early state of the bud. To this, however, has not improperly been applied the name of convolute, from its similarity to the convolute vernation of the leaves of the branch (257), similarly rolled up one within the other. But it is practically inconvenient, and wrong in principle, to designate different degrees of the very same mode by distinct names ; furthermore, it is to the next general mode of estivation that the name of convolute is more commonly applied, at least in recent sys- tematic botanical writings. 497. There are numerous cases of imbricative estivation, espe- cially in irregular flowers, where the overlapping of parts does not altogether accord with what must needs be their order of succes- sion on the axis. In the 5-merous calyx and corolla of all truly papilionaceous flowers, for example, one edge of the sepal or the petal No. 2 is placed under, instead of over, the adjacent edge of No. 4, in consequence of which three, instead of only one, of the leaves have one edge covered and the other external; as is shown in Fig. 358. Since, in the corolla of this kind of blossom, the ex- terior petal, here the vexillum (472), is the larger, and at first em- braces all the rest, this modification of imbricative eestivation has received the name of vewillary. As nearly the same thing occurs 272 THE FLOWER. in the Violet, it is probably caused by some slight dislocation that takes place during the early growth of organs in the irregular blos- som. It is not restricted to irregular flowers, however, but occurs as a casual variation, or perhaps more frequent- Fe ly than the quincuncial, in the regular corolla Seo of the Linden (as is shown in Fig. 440). A Uzi slight obliquity in the position of the petal No. ANE yy 2, assumed at an early period, would account i ey for the whole anomaly. That this suggests SZ the true explanation is almost demonstrated by the varying estivation of the corolla of the Linden; in which the same bunch of blossoms often furnishes in- stances of regular quincuncial imbrication, of the modification here referred to, and of a similar disposition of the fifth petal, throwing one of its edges outwards also. If the first petal were also to par- take of this slight obliquity, the imbricative would be completely conyerted into what is variously named 498. The contorted, twisted, or convolutive sstivation (Fig. 439, 441, the corolla, and 442). In this mode, the leaves of the circle are all, at least apparently, inserted at the same height, and all occupy the same relative position: one edge of each, being directed ob- liquely inwards, is covered by the adjacent leaf on that side, while the other covers the corresponding margin of the contiguous leaf on the other side. This is owing to a torsion or twisting of each member on its axis early in its development ; so that the leaves of the floral verticil, instead of forming ares of a circle, or sides of a polygon © 441 having for its centre that of the blossom, severally assume an oblique direction, by which one edge is carried partly inward and the other outward. This contorted wstivation is rare in the calyx, but com- FIG. 440. Diagram of the plan and sestivation of the flower of the Linden. FIG. 441. Diagram of the imbricated calyx of Wallflower (two outer and two inner sepals), and within the strongly contorted or convolute corolla. 442. Corolla of the latter more open. 448. Cross-section of the plaited tube of the corolla of Campanula. 444. Similar section of the plaited and supervolute corolla of Convolvulus. ZESTIVATION OR PRA‘FLORATION. 273 mon enough in the corolla. When this obliquity of position is strong, the petals themselves are usually oblique, or unequal-sided, from the lesser growth of the overlapped side. This is well seen in the pet- als of most Malvaceous plants, and in those of the St. Johnswort. In the Pink, however, and in many other instances, the petals are symmetrical, although strongly convolute in zstivation. When the petals are broad, this convolute arrangement is frequently conspicu- ous in the fully expanded flower, as well as in the bud. The con- volution in the bud is often so great, that the petals appear as if strongly twisted or rolled up together, each being almost completely “overlapped by the preceding, so that they become convolute nearly in the sense in which the term is used in vernation ; as in the Wall- flower (Fig. 441, 442). Although there is some diversity of usage, the terms convolute and contorted in wstivation are now for the most part employed interchangeably, or nearly so. 499. The valvular or valvate estivation is that in which the parts of a floral cirele are placed in contact, edge to edge, throughout their whole length, without any overlapping, as in the calyx of the Mal- low and Linden, Fig. 440. Here the members of the circle stand in an exact circle, no one being in the least degree lower or exteriar. The edges of the sepals or petals in this case are generally abrupt, or as thick as the rest of the organ; by which mark the valvate es- tivation may commonly be recognized in the expanded flower. 500. By inflexion of the edges, the valvate estivation passes by gradations into the induplicate (Fig. 445), and this, when the margins are in- So) rolled, into the ¢nrolute (Fig. 446), as is (3 a exemplified by the calyx of different spe- 9) 445 446 cies of Clematis. On the other hand, the valvate calyx of many Malvaceous plants has the margins projecting outwards into salient ridges, or is redupli- cate, in zstivation. 501. In the Mignonette, and some other flowers, the sstivation is open ; that is, the calyx and corolla are not closed at all over the other parts of the flower in the bud. 502. The form of the tube of the calyx or corolla in the bud sometimes has to be considered. Sometimes it is plicate, or plaited lengthwise ; and the plaits may be turned either inwards, as in the FIG. 445. Diagram of the valvate-induplicate wstivation of the calyx of Clematis Virgini- ana. 446. Same of Clematis Viticella, the margins involute. 274 THE FLOWER. corolla of Gentians, or outwards, as in that of Campanula (Fig. 443). When these plaits are laid over one another in a convolute manner, as in the unopened corolla of the Morning-Glory (Fig. 444) and Stramonium (Fig. 447, 448), the cstivation is said to be supervolute. 503. The direction of the spire or the overlap- ping of parts may be either from left to right, or from right to left; and this direction is generally uniform. In indicating the direction, it is most natural to suppose the observer to stand before the flower-bud. DeCandolle, indeed, supposes the © observer to occupy the centre of the flower, which would reverse the direction ; but the former is the prevalent view. The direction is frequently re- versed in passing from the calyx to the corolla, sometimes with remarkable uniformity ; while again the two occur almost indifferently in many cases. The hind of wstivation, although often the same both in the calyx and corolla, —as in Parnassia (Fig. 3881) and Elodea (Fig. 375), where both are quincuncially imbricated,— is as frequently different ; and the difference is often characteristic of families or genera. Thus, the calyx is valvate and the corolla convolute in all Malvacew ; the calyx imbricated and the corolla convolute in Hypericum, in the proper Pink tribe, &c. Solitary exceptions now and then occur in a family. Thus, the corolla in Rosacex is imbri- cated, so far as known, except in Gillenia, where it is convolute. In general it may be said, that the estivation of the corolla is less con- 448 stant than that of the calyx. 504. The Calyx. In treating of the general structure and diver- sities of the flower, we have already noticed the principal modifi- cations of the calyx and corolla, as well as many of the terms em- ployed to designate them; which need not be here repeated. 505. The number of sepals that enter into the composition of a calyx is indicated by adjectives formed from the corresponding Greek numerals prefixed to the name; as, disepalous, for a calyx of two sepals; trisepalous, of three sepals; tetrasepalous, of four ; pen- tasepalous, of five; hexasepalous, of six sepals; and so on, Very commonly, however, the Greek word for leaves, phylla, is used in FIG 447. Summit of the unexpanded corolla of Datura meteloides. 448. Transverse sec- tion of the same. THE CALYX AND COROLLA. 275 such composition ; and the calyx is said to be diphyllous, triphyllous, tetraphyllous, pentaphyllous, hecaphyllous, &c., according as it is com- posed of two, three, four, five, or six leaves or sepals respectively. These terms imply that the leaves of the calyx are distinct, or nearly so. When they are united into a cup or tube, the calyx was by the earlier botanists incorrectly said to be monophyllous (literally one- leaved) ;—-a term which we continue to use, guarding, however, against the erroneous idea which its etymology involves, and bearing in mind that the older technical language in botany is founded upon external appearance, and not the real structure, as we now under- stand it. The correct term, calyx gamophyllous, is now coming into use: this literally expresses the true state of the case, and is equiva- lent to the phrase sepals united ; the degree of coalescence being in- dicated by adding “at the base,” “to the middle,” or “to the sum- mit,” as the case may be. Still, in botanical descriptions, it is usual and ordinarily more convenient to regard the calyx as a whole, and to express the degree of union or separation by the same terms as those which designate the degree of division of the blade of a leaf (281 — 287) : as, for example, Calyx jive-toothed, when the sepals of a pentaphyllous calyx are united almost to the top ; five-cleft, when united to about the middle; jfive-parted, when they are separate almost to the base; and jive-lobed, for any degree of division less than five-parted, without reference to its particular extent. 506. The united portion of a gamophyllous calyx is called its tube ; the distinct portions of the sepals are termed the teeth, seg- ments, or lobes, according to their length as compared with the tube ; and the orifice or summit of the tube is named the throat. The calyx is said to be enétre, when the leaves of the calyx are so com- pletely confluent that the margin is continuous and even. The terms regular and irregular (446, 471) are applied to the calyx or corolla separately, as well as to the whole flower. The counterpart term to calyx monophyllous or monosepalous, is polyphyllous or polysepalous (viz. of many leaves or sepals). This is equivalent to the phrase sepals distinct ; and does not mean, as the etymology might lead one to suppose, that they are unusually numerous. 507. The Corolla has corresponding terms applied to its modifica- tions. When its petals are distinct or unconnected, it is said to be polypetalous ; when united, at least at the base, monopetalous, or more properly gamopetalous, as already explained. Various de- grees of such union are shown in Fig, 450-460. he united por- 276 THE FLOWER. tions in the latter case form the tube of the corolla; the distinct parts are the lobes, segments, &c.; and the orifice is called the throat, just as in the calyx. The number of parts that compose the corolla is designated in the manner already mentioned for the calyx; viz. a corolla of two petals is dipetalous ; of three, tripetalous ; of four, tetrapetalous ; of five, pentapetalous ; of six, hexapetalous ; of seven, heptapetalous ; of eight, octopetalous ; of nine, enneapetalous ; of ten, decapetalous. 508. Frequently the petals (and rarely the sepals) taper into a stalk or narrow base, analogous to the petiole of a leaf, which is called the claw (unguis) ; and hence the petal is said to be wngutcu- late ; as in Cruciferous flowers (Fig. 405), the Pink family (Fig. 432), and Gynandropsis (Fig. 433), &c.; the expanded portion, like that of the leaf, being distinguished by the name of the lamina, limb, or blade. 509. Some kinds of polypetalous flowers receive particular names, from the form or.arrangement of their floral envelopes, especially of the corolla. They may be divided into the regular and the irregular, —terms which have already been defined (446, 471). Among the regular forms we may mention the rosaceous flower, like that of the Rose, Apple, &c., where the five spreading petals have no claws, or very short ones ; the diliaceous, of which the Lily is the type, where the claws or base of the petals or sepals are erect, and gradually spread towards their summits ; the caryophyllaceous, as in the Pink and its allies (Fig. 449), where the five petals have long and narrow FIG. 449. Corolla of Soapwort, of five separate, long-clawed or unguiculate petals. FIG. 450. Flower of Gilia or Ipomopsis coronopifolia ; the parts answering to the claws of the petals of the last figure here all united into a tube. FIG. 451. Flower of the Cypress-Vine ; the petals a little farther united into a five-lobed spreading border. FIG. 452. Flower of the small Scarlet Morning-Glory, the five petals it is composed of per- fectly united into a trumpet-shaped tube, and a nearly entire spreading border. THE COROLLA. 277 claws, which are enclosed in the tube of the calyx ; and the cruciate, or cruciform, which gives its name to the Mustard family, where the four unguiculate petals, diverging equally from one another, are necessarily disposed in the form of a cross, as in the Mustard (Fig. 405). Among the ¢rregular poly peta- lous flowers, which are extremely varied in different families, the paptlionaceous or but- terfly-shaped corolla of the Pulse family is the most familiar, and has already been illustrated (471, Fig. 392). 510. Several forms of the gamopetalous corolla, or gamophyl- lous calyx, have been distinguished by particular names. These are likewise divided into the regular, where their parts are equal in size, or equally united; and the ¢rregular, where their size or de- gree of union is unequal (471). Among the former are the cam- panulate or bell-shaped, as the corolla of the Harebell (Fig. 456), which enlarges gradually and regularly from the base to the summit ; 463 454 dl 459 460 the infundibuliform, or funnel-shaped, where the tube enlarges very gradually below, but expands widely at the summit, as in the corolla of Morning-Glory (Fig. 1035 and 452) ; zubular, where the form is somewhat cylindrical throughout, as in Trumpet Honeysuckle ; hypo- crateriform (more correctly hypocraterimorphous), or salver-shaped, FIG. 453. Rotate or wheel-shaped and five-parted corolla of the Bittersweet (Solanum Duleamara). FIG. 454. Wheel-shaped and five-cleft corolla of the common Potato. FIG. 455. The almost entire and open bell-shaped corolla of a Ground Cherry (Physalis). FIG. 456. Campanulate corolla of the Harebell, Campanula rotundifolia. 457. Salver- shaped corolla of Phlox. 458. Labiate (ringent) corolla of Lamium ; aside view. 459, Per- sonate corolla of Antirrhinum. 460. Personate corolla of Linaria, spurred at the base. 24 278 THE FLOWER. where the limb spreads at right angles with the summit of the more or less elongated tube, as in the corolla of Cypress-Vine (Fig. 451) and Phlox (Fig. 457); and rotate, or wheel-shaped, when a hypo- crateriform corolla has a very short tube, as in the Forget-me-not, Bit- tersweet (Tig. 455), and Potato (Fig. 454). 511. The principal irregular gamopetalous or gamophylous forms that have received a separate appellation are the ligulate or strap- shaped, which has already been explained (473), and the labiate or bilabiate. The latter, as already stated, is produced by the unequal union of the sepals or petals (475), so as to form an upper and a lower part, or two lips, as they are called, from an obvious resemblance to the open mouth of an animal (Fig. 458-460). ‘This variety is al- most universally exhibited by the corolla of the Sage or Mint family (which is therefore called Labiatiz), as well as of several related families ; and the calyx is frequently bilabiate also, as in the Sage. And since, in the corolla of these families, two of the five petals enter into the composition of the upper lip, and three into that of the lower, this is necessarily inverted in the bilabiate calyx, three of the sepals combining to form the upper lip, and two to form the lower. 512. When the upper lip is arched, as in the corolla of Lamium (Fig. 458), it is sometimes called the galea, or helmet. When the two lips are thus gaping and the throat open, the corolla is said to be ringent. When the mouth is closed, or partly so, by an elevated portion or protuberance of the lower lip, called the palate, as in the Snapdragon and Toadflax (Fig. 459, 460), the corolla is said to be personate, or masked. 513. In the Snapdragon, the base of the corolla is somewhat pro- tuberant, or saccate, on the anterior side; in the Toadflax, the pro- tuberance is extended into a hollow spur. A projection of this kind is not uncommon, in various families of plants. One petal of the | Violet is thus spurred or calcarate (Fig. 397) ; so is one of the outer petals in the Fumitory, and each of them in Dicentra (Fig. 370). So, also, one of the sepals is spurred or strongly sac-shaped in the Jewel- weed (Impatiens), and the Larkspur (Tig. 398) ; and all five petals take this shape in the Columbine. A monster of the Toadflax is occasionally found, in which the four remaining petals of the five which enter into its composition, affect the same irregularity, and so bring back the flower to a singular abnormal state of regularity. This was called by Linneus Peloria ; a name which is now used to designate the same sort of monstrosity in different flowers. THE STAMENS. 279 514. The petals are sometimes furnished with appendages on their inner surface, such as the crown at the summit of the claw in Silene (Fig. 378, 449), and the scales similarly situated on the gamopetalous corolla of the Comfrey, &c. These appendages some- times represent a circle of sterile and metamorphosed stamens ; but more commonly they seem really to belong to the petal. 515. As to duration, sometimes the floral envelopes are caducous, i. e. falling off when the blossom opens, as the calyx in the Poppy fam- ily and the corolla-of the Grape-Vine (Fig. 884). More commonly they are dec¢duous, or fall after expansion, but before the fruit forms. When they remain until the fruit is formed or matured, they are persistent, which is often the case with the calyx, especially when it has a green color and foliaceous texture. When they persist in a dry or withering state, as the corolla of Heaths, Campanula, &c., they are said to be marcescent. 516. Besides serving as organs of protection, the sepals, when green, assimilate sap, and act upon the air like ordinary foliage (344, 345). The petals, like other uncolored (that is greenless) parts, do not evolve oxygen, but abstract it from the air, and give off carbonic acid; in other words, they decompose assimilated matter, —a pro- cess which appears to be needful in flowering, and to subserve some important end at the time (868-373). The tissue of a petal is much the same as that of a leaf, except that it is much more delicate and the fibro-vascular system is generally reduced to slender bundles of a few spiral vessels, &c., which form its veins. Scot. VI. Tue STAMeEnNs. 517. The Stamens have already been considered in a general way (418). Before describing their structure more particularly, the principal terms which relate to their number, connection, and _posi- tion may be mentioned. Most of these terms were devised by Lin- nzus as names of the classes of his Artificial System of classification (Part II. Chap. IV.), founded mainly upon characters furnished by the stamens. Their number in a flower is accordingly expressed by the names of the eleven or twelve earlier Linnean classes (990), put into adjective form. Thus, a flower with one stamen is said to be monandrous ; with two, diandrous ; with three, triandrous ; with four, tetrandrous ; with five, pentandrous ; with six, hexandrous ; 280 THE FLOWER. with seven, heptandrous ; with eight, octandrous ; with nine, ennean- drous ; with ten, decandrous ; with twelve, dodecandrous. When more than twelve, and inserted on the calyx, they are ¢socandrous, or when inserted on the receptacle, polyandrous. 518. As to their union with each other, this may take place in various ways. Sometimes the filaments are combined, while the anthers are distinct. When thus united by their filaments into one set, they are said to be monadelphous ; asin the Lupine, &e. (Fig. 462) and Mallow. When united by their filaments into two sets, they are diadel- phous, as in most plants of the Pulse family, where nine stamens form one set and the tenth is soli- tary (Fig. 461); and in Dicentra (Fig. 369 — 371), where the six stamens are equally com- bined in two sets. When united or ar- ranged in three sets or parcels, they are said to be triadelphous, as in the com- mon St. Johnswort; or if in several, polyadelphous ; as in Linden. When stamens are united by their anthers into a tube or ring, they are said to be syn- genesious (Fig. 463, 464). This occurs in the whole vast order of Composita. Here the five filaments are distinct; whereas in Lobelia, and also in the Melon and Gourd (Fig. 465, 466), both the filaments and the anthers are united; that is, the stamens are monadelphous as well as syngenesious. 519. As to insertion, stamens are hypogynous (466) when borne on the receptacle, that is, when not adnate to any other organ; FIG. 461. Diadelphous stamens (9 and 1) of a Pea. 462. Monadelphous stamens of a Lupine. FIG. 463. Five syngenesious stamens of a Composita. 464. The same, laid open. FIG. 465. Column of stamens, at once triadelphous and syngenesious, of the Gourd: the floral envelopes cut away. 466. A cross-section of the united anthers, nearly the natural size. 467. A sinuous anther of the Melon. THE STAMENS. 281 perigynous (467) when borne on or adnate to any part of the calyx; epipetalous, when borne on the corolla, as in the greater number of * monopetalous flowers; and epigynous (469), when borne on the ovary. In some cases the adnation proceeds further, and the stamens are inserted on, i. e. are consolidated with, the style, as in the Orchis family; then they are said to be yynandrous (Fig. 468). 520. There are two cases in which inequal- ity in the length of the filaments is expressed by a technical term. Namely, the stamens are said to be didynamous when, being only four in number, they are in pairs, and one pair is longer than the other; as in Gerardia (Fig. 407), and in most flowers with a bilabiate corolla. And they are tetradynamous when, being six in number, two are shorter than the remaining four, as in Mus- tard and all that family of plants with Cruciferous flowers (Fig. 406). 521. A stamen consists of its filament and its anther (418). The filament, being a mere stalk or support of the anther, is not an essential part ; it is to the anther what the petiole is to the blade of a leaf. Sometimes, therefore, it is wanting, when the anther is sessile. The anther is essential to a perfect stamen. But sometimes a stamen, or what stands in the place of one, is destitute of an anther, i. e. is sterdle, as in Fig. 408; and also the upper one in Fig. 468, st.. which is a sterile filament enlarged into a petal-like body. The true nature of the organ is known by its position. 522. The Filament, although usually slender and stalk-like, assumes a great variety of forms: it is sometimes dilated so as to resemble a petal, except by its bearing an anther ; as in the transition states be- tween the true petals and stamens of the Water-Lily (Fig. 344). The filament is anatomically composed of a central bundle of spiral yes- sels or ducts, which represent the fibro-vascular system of the leaf, in the same state as in the petiole, enveloped by parenchyma; the outer stratum of which forms a delicate epidermis. 523. The Anther, which is the essential part of the stamen, is usu- ally borne on the apex of the filament; and commonly consists of two lobes, or cells (thece), placed side by side, and connected by a prolongation of the filament, called the connectivum, or connective. FIG, 468. Stamens and style of a Cypripedium, united into one body or column: a, a, anthers: sc. a sterile stamen: stig. the stigma. 24* 282 THE FLOWER. 524. The attachment of the anther to the filament presents three principal modes. 1st. When the base of the connective exactly corresponds with the apex of the filament and with the axis of the anther, the latter is termed innate, and rests firmly upon the summit of the filament, as in Fig. 469. 2d. When the lobes of the anther adhere for their whole length to a prolonga- tion of the filament, or to a broad connective (whichever it be called), so as to appear lateral, it is said to be adnate; as in Magnolia, Lirio- dendron (Fig. 470), &c. Here the anther must be either extrorse or in- trorse. It is tntrorse, or turned tn- aa a wards, when it occupies the inner side of the connective, and faces the pistils, as in Magnolia; but when the anther looks away from the pistils and towards tle petals or sepals, it is said to be extrorse, or turned outwards, as in Iris, Liriodendron, and Asarum (Fig. 472). 3d. When the anther is fixed by a point near its middle to the apex of the filament, on which it lightly swings, it is said to be versatile ; as in all Grasses, in the Lily, and in the Evening Primrose (Fig. 471), &c. In this case, as in the preceding, the anther is said to be tnérorse, or cncumbent, when it is turned towards the pistil, which is the most common way ; and extrorse, when it faces outwards. 525. The connective is often inconspicuous or wholly wanting, so that the lobes of the anther are directly in contact on the apex of the filament; but it is commonly evident. It is often produced into an appendage at the tip of the anther, as in Magnolia and Liriodendron (Fig. 470), the Papaw (Fig. 956, where it forms a rounded top), and Asarum (Fig. 472). Appendages or processes from the back of the connective are seen in the stamens of the Violet and of many Ericaceous plants. aa 526. Each of the two cells or lobes of the anther is marked with a lateral line or furrow, running from top to bottom; this is the FIG. 469. A stamen of Isopyrum biternatum, with an innate anther 470. Stamen of Lirio- dendron, or Tulip-tree, with an adnate extrorse anther. 471. Stamen of nothera glauca, with the anther fixed by its middle and versatile. FIG. 472. Astamen of Asarum Canadense, with an adnate anther. THE ANTHER. 283 suture, or line of dehiscence, by which the anther opens at maturity to discharge the pollen (Fig. 473). This line is for the most part exactly lateral in innate anthers ; but it looks more or less evidently, and often directly, inward in introrse, and outward in extrorse anthers. In certain cases the cells of the anther open only at the summit, by a pore or hole, as in Py- rola (Fig. 474) and most Ericaceous plants. Inthe Whortleberry family each cell or lobe is commonly pro- longed into a tube, which opens only at the apex (Fig. 391). Inthe Bar- berry (Fig. 475), and in nearly all plants of the Barberry family, the whole face of each anther-cell sepa- rates by a continuous line, forming a kind of door, which is attached at the top, and turns back, as if on a hinge: in this case the anthers are said to open by valves. In the Sassafras (Fig. 1114), and many other plants of the Laurel family, each lobe of the anther opens by two such valves, like trap-doors. 527. Sometimes the anthers are one-celled by the suppression of one lobe, being dimidiate, or reduced as it were to half-stamens, as in Gomphrena or Globe-Amaranth (Fig. 478). But most one-celled anthers are the result of the confluence of the two cells into one. A comparison of the two-celled anther of Pent- stemon pubescens, where the two cells diverge below and are somewhat united at the top (Fig. 476) with the kidney-shaped one-celled anther of a Mallow, opening by a continuous line all round the margin (Fig. 477), shows how this result is brought about. 528. As to anatomical structure, each lobe of the full-grown anther consists of an, epidermal membrane, lined with a delicate fibrous tissue, and surrounding a cavity filled with pollen. This 476 477 FIG. 478. A stamen, with its anther, 5, opening in the normal manner down the whole length of the outer side of each cell: @, the filament. FIG. 474. Stamen of a Pyrola; each cell of the anther opening by a terminal orifice. FIG. 475. Stamen of a Barberry ; the cells of the anther opening by an uplifted valve. FIG. 476. A stamen of Pentstemon pubescens ; anther-cells slightly confluent. FIG. 477. Stamen of Mallow; the two cells confluent into one, opening round the margin, FIG. 478. Anther of Globe Amaranth, of only one cell; the otucr cell obliterated. 284 THE FLOWER. fibrous lining (a little of which is shown in Fig. 45, from the anther of Cobra) is composed of simple or branching threads or bands, which formed the thickening deposit on the walls of Iarge paren- chymatous cells; all the membrane between the bands becoming ob- literated as the anther approaches maturity, the latter alone remain, as a set of delicate fibres. This fibrous layer gradually diminishes in thickness as it approaches the line of dehiscence of the cell, and there it is completely interrupted. These very elastic and hygro- metrie threads lengthen or contract in different ways, according as the anther is dry or moist, and are thought to favor the egress of the pollen. The outer stratum of the wall of the anther in dry- ing contracts more than the inner, and so opens the cell, in many cases turning the walls inside out after dehiscence, as in Lilies and Grasses. 529. Of all the floral organs, the anther shows least likeness to aleaf. Nevertheless, the early development is nearly the same. Like the leaf, the apex is earliest formed, appearing first as a solid protuberance, and the anther is completed before the filament, which answers to the leafstalk, makes its appearance. At first, the anther is of a greenish hue, although at maturity the cells assume a differ- ent color, more commonly yellow. A transverse section of the form- ing anther shows four places in which the transformation of the paren- chyma into pollen commences, which answer to the centre of the four divisions of the parenchyma of a leaf, viz. the two sides of the blade, each distinguished into its upper and its lower stratum. So that the anther is primarily and typically four-celled ; each lobe being divided by a portion of untransformed tissue, stretching from the connective to the opposite side, which corresponds to the margin of the leaf and the line of dehiscence. This appearance is presented by a large number of full-grown anthers: but the par- tition usually disappears before the anther opens, when each lobe becomes single celled. The normal anther is consequently considered as two-celled. In Meni- spermum and Cocculus, however, the anther is strongly i four-lobed externally, and each lobe forms a distinct 479 cell at maturity. 530. Viewed morphologically, therefore, the filament answers to FIG. 479. Plan of a stamen as answering to o leaf; the upper part of the anther cut away, and the summit of a leaf represented above it. THE POLLEN. 285. the petiole of a leaf; the anther, to the blade. The connective represents the midrib; the lobes or cells of the anther represent the two symmetrical halves of the blade ; and the line of dehiscence is normally along the margins of the transformed leaf. What in the leaf would be cells of parenchyma develop as 531. Pollen, This usually powdery substance consists of grains, of definite size and shape, uniform in the same plant, but often very different in different species or families. The grains are commonly single cells, globular or oval in shape, and of a yellow color. But in Spiderwort they are oblong; in the Cichory and Thistle tribes many-sided (Fig. 485); in the Musk-plant spirally grooved (Fig. 480); in the Mallow family (Fig. 483) and the Squash and Pump- kin, beset with bristly projections, &c. The pollen of Pine (Fig. 486), as well as that of the Onagraces (Fig. 487, 489), is not so: simple, but appears to consist of three or four blended cells ; that of all true Ericacez evidently consists of four grains or cells united. (Fig. 488). The most extraordinary shape is that of Zostera, or’ the Eel-grass of salt-water, in which the grains (destitute of the outer coat) consist of long and slender threads, which, as they lie side by side in the anther, resemble a skein of silk. 532. Pollen-grains are usually formed in fours, 4 by the division of the living contents of mother _ cells first into two, and these again into two parts, which, acquiring’ a coat of cellulose, become specialized cells (36). As the pollen completes its growth, the walls of the mother cells are usually oblit-: erated. But sometimes the enclosing cells persist, and collect the FIG. 480-489. Forms of pollen: 480, from Mimulus moschatus : 481, Sicyos: 482, Echi-- nocystis: 488, Hibiscus: 484, Lily: 485, Cichory: 486, Pine: 487, Circa: 488, Kalmia : 489, Evening Primrose. 286 THE FLOWER. pollen-grains into coherent masses of various consistence, as is re- markably the case in the Orchis and Milkweed families (Fig. 543, &c.). Such pollen-masses are sometimes termed pollinia. 533. The threads, resembling cobweb, that are loosely mixed with the pollen of the Evening Primrose, are the vestiges of obliterated mother cells. 534. Pollen-grains have two coats. The outer coat, called the extine, is comparatively thick, and often granular or fleshy. This is later formed than the inner, and by a kind of secretion from it: to it all the markings belong. The inner coat, or tntine, which is the proper cell-membrane, is a very thin and delicate, transparent and colorless membrane, of considerable strength for its thickness. The pollen of Zostera and of some other aquatic plants is destitute of the * outer coat (531). 535. The cavity enclosed by the coats is filled with a viscid liquid, rich in protoplasm, which often appears slightly turbid under the higher powers of ordinary microscopes, and, when submitted to a magnifying power of about three hundred diameters, is found to contain a multitude of minute particles (foville), the larger of which are from the four-thousandth to the five-thousandth of an inch in length, and the smaller only one fourth or one sixth of this size. The smaller exhibit the constant molecular motion of all such mi- nute particles when suspended in a liquid and viewed under suffi- cient magnifying power. When wetted, the grains of pollen prompt- ly absorb water by endosmosis (87), and are distended, changing their shape somewhat, and obliterating the longitudinal folds, one or more in number, which many grains exhibit in the dry state. Soon the more extensible and elastic inner coat inclines to force its way through the weaker parts of the outer, especially at one or more thin points or pores ; sometimes forming a projection of considerable length, when the absorption is slow and the exterior coating tough. Tf the absorption continues, the distention soon overcomes the resist- ance of the elastic inner coat, which bursts, and the contents are dis- charged. 536. When fresh, living pollen falls upon the stigma, however, which is barely moist, it does not burst, but the inner membrane is slowly projected, often through particular points, clefts, or openings of the outer eoat, in the form of an attenuated transparent tube (Fig. 537 — 547), filled with its fluid contents, and which penetrates the naked and loose cellular tissue of the stigma, and buries itself in THE PISTILS. 287 the style. This is not a mechanical protrusion, but a true growth, the materials for which are supplied by nourishment imbibed from the stigma and style. Its further course and the office it subserves will be considered after the structure of the pistil is made known. (Sect. TX.) Sect. VII. Tue Pistits. 537. The Pistils (419) occupy the centre of the flower, and ter- minate the axis of growth. Linneus established the orders of his Artificial System mainly upon the pistils, and this introduced a se- ries of terms expressive of their number in a flower, analogous to those used for the number of stamens (517). Thus a flower with a single pistil is said to be monogynous ; with two, digynous ; with three, trigynous ; with four, tetragynous ; with five, pentagynous ; and so on: when more numerous or indefinite, the flower is polygynous. 538. It is comparatively seldom that the pistils are exactly equal to the petals or sepals in number ; they are sometimes more numer- ous, and arranged in several rows upon the enlarged or prolonged receptacle, as in the Magnolia, the Strawberry, &c., and perhaps more frequently they are reduced to less than the symmetrical num- ber, or to a single one. Yet often what appears to be a single pistil is not so in reality, but a compound organ, formed by the union of two, three, or a greater number of simple pistils; these organs being subject to coalescence in the same way as the stamens (518) and the petals (507, 462). 539. A simple and complete pistil, as already described (420), is composed of three parts: the Ovary, or seed-bearing portion ; the Sryxr, or tapering portion, into which the apex of the ovary is pro- longed ; and the Streaa, usually situated at the summit of the style, consisting of a part, or sometimes a mere point, of the latter, divested of epidermis, with its moist cellular tissue exposed to the air. The ovary, which contains the ovules, or bodies which are to become seeds, is of course a necessary part of* the pistil; the stigma, which receives from the anthers the pollen (531) by which the ovules are fertilized, is no less necessary ; but the intervening style is no more essential to the pistil than the filament is to the stamen, and is there- fore not uncommonly wanting. In the latter case, the stigma is sessile upon the apex of the ovary. In Tasmannia it actually occu- pies the side of the ovary for nearly its whole length, and is sepa- 288 THE FLOWER. rated from the line to which the ovules are attached only by the thickness of the walls: it is nearly the same in our Schizandra (Fig. 493), another plant of the Magnolia family. The style some- times proceeds from the side, or even from near the apparent base of the ovary ; as in the Strawberry (Fig. 428). 540. When the pistil is single, or when several coalesce into one, it will necessarily terminate the axis, and appear to be a direct con- tinuation of it. When there are two pistils in the flower, they al- ways stand opposite each other (so that if they coalesce it is by their inner faces) ; and are either lateral as respects the flower, that is, one on the right side and the other on the left, in a plane at right angles to the bract and axis (444), as in the Mustard family, the Gentian family, and a few-others ; or, more commonly, anterior and posterior, one before the axis and the other before the bract of the axillary flower. When they accord in number with the sepals or petals, they are either opposed to or alternate with them; and the two positions in this respect are sometimes found in nearly related genera, so as to baffle our attempts at explaining the cause of the difference. In Pavunia, for example, the five pistils are opposite the petals; in Malvaviscus and Hibiscus, alternate with them. In Sida (when five) they stand opposite the petals ; in Abutilon, opposite the sepals. 541. Pistils oceur under such a diversity of forms, and exhibit such various complications, that the plan of their structure and the distinction between simple and compound pistils require to be well understood. Commencing, therefore, with the most natural forms, and proceeding gradually to the more complex or disguised, we first consider 542. The Simple Pistil, and the way in which it answers to a leaf. A simple pistil answers to a single leaf. A compound pistil answers to two or more leaves combined, just as a monopetalous corolla answers to two or more petals, or leaves of the flower, united into one body. As to its morphology, the botanist regards a simple pistil as consisting of the blade of a leaf, curved inwards until its margins meet and unite, forming in this way a closed case, or pod, which is the ovary. So that the upper face of the altered leaf answers to the inner surface of the ovary, and the lower, to its outer surface. And the ovules are borne on what answers to the united edges of the leaf. The tapering summit, rolled together and prolonged, forms the style, when there is any; and the edges THE SIMPLE PISTIL. 289 of the altered leaf turned outwards, either at the tip or along the inner side of the style, form the stigma. This will be clearly un- derstood on comparing Fig. 842 and Fig. 491, which are pistils transversely divided, with Fig. 490, a leaf curved inwards until its margins nearly meet, and with Fig. 492, a simple pistil of Caltha or Marsh-Marigold which has matured, split open along the inner side to discharge the seeds it bore, and spread out into the shape of a leaf. 543. The line formed by the union of the margins of the leaf is called the Inner or Ventral Suture, and always looks towards the axis of the flower. This is a true suture, or seam, as the word denotes. The opposite line, answering to the mid- rib, is sometimes apparent as a thickened line, and is termed the Outer or Dorsal Suture. The ovules or young seeds are borne (in all ordinary cases at least) on the inner sutung, or some part of it; that is, on what answers to the united margins of the infolded and transformed leaf. The part in the cell of the ovary to which the ovules are attached, and which is commonly more or less enlarged or projecting when the ovules are numerous, is named 544. The Placenta. As this corresponds with the ventral suture, and is in fact a part of it, or a cellular growth from it, it always belongs next the axis of the flower; as is evidently the case when two, three, or more pistils are present. Each placenta necessarily consists of two parts, one belonging to each margin of the transformed leaf. It therefore is frequently two-lobed, or of two diverg- ing lamelle (Fig. 842). This shows why the ovules are apt to occupy two longitudinal rows, as in FIG. 490. A leaf infolded, to illustrate the theory of the formation of the pistil. FIG. 491. Pistil of Isopyrum biternatum, cut across; the inner or ovule-bearing side turned towards the observer. FIG. 492. Ripe pistil of Caltha palustris, after opening and discharging the seeds. FIG. 493. Vertical section of a pistil of Schizandra coccinea; a side view. 494. Pistil of Hydrastis. 495. Pistil of Actea rubra, cut across, so as to show the interior of the ovary (the ventral suture turned towards the observer). 25 290 THE FLOWER. the figure last cited, and in Fig. 491, 495, &c., one row belonging to each margin of the leaf. A simple pistil, accordingly, can have only one placenta; but that is structurally double. 545. So a single pistil can have only one style and one stigma. But as the stigma answers to the margins of the apex of the leaf, this must also be double in its nature. And this is evidently the case in the Peony and Isopyrum (Fig. 491), in the Tulip, as well as in Fig. 493 — 495, and in almost all cases in which the stigma extends down the inner face of the style, as it frequently does. Such unilateral stigmas we accordingly take to be the typical form ; and say that, while the united margins of the transformed leaf which compose the ventral suture are turned inwards into the cell of the ovary to bear the ovules, in the simple style they are exposed external- ly to form the stigma. Where the stigma is terminal, or occupies only the apex of the style, we suppose that these margins are in- folded in the style also, and form in its interior the loose conducting tissue through which a communication is established between the stigma and the interior of the ovary. 546. The ovary of a simple pistil obviously can have but one cavity or cell; except from some condition out of the natural order of things. But the converse does not hold true: all pistils of a sin- gle cell are not simple. Many compound pistils are one-celled, as will presently be explained. 547, A leaf or member of the gynacium then, when separate, forms a simple pistil; when combined with others, it makes part of a compound pistil. It is convenient to have a name which shall desig- ‘nate a single pistil-leaf, whether occurring as a distinct simple pistil, or as an element of a compound pistil. For this purpose the name of Carpe. has been devised. A carpel is either a simple pistil, or is one of acircle of leaves which compose a compound pistil. When the pistils are distinct from each other, they are said to be apocarpous ; when united into one body, syncarpous. This union produces a 548. Compound Pistil, All degrees of union of the carpels may be observed, from the coalescence of the lower part of their ovaries, their summits remaining separate (as in Fig. 496), or from the com- plete union of the ovaries into one body, the styles remaining sepa- rate (as in Fig. 497), to the complete coalescence of the styles also (Fig. 498), and even of the stigmas (Fig. 499), into one body. It is evidently the same as if two or more pistils (in Fig. 497 — 499, three THE COMPOUND PISTIL. 291 pistils) were pressed together as they grew and consolidated more or less completely into one. And in this, the most normal case, we have as the result compound pistils 549. With two or more Cells and Axile Placent#, For it is evident that, if the contiguous parts of a whorl of three or more closed car- pels cohere, the resulting compound ovary will have as many cavi- ties, or cells, as there are carpels in its composition, and the placente (one in the inner angle of each carpel) will all be brought together in the axis of the compound pistil. And the partitions, or DissEp- IMENTS, which divide the compound ovary into cells, manifestly consist of the united contiguous portions of the walls of the carpels. These necessarily are ——\ composed of two layers, one belonging to each Le carpel; and in ripe pods they often split into the two layers. True dissepiments must always Ws 2g) be equal in number to the carpels of which the \ 2 compound pistil is composed. 550. In certain cases, indeed, there are addi- tional partitions, or false dissepiments. ‘These are commonly projec- FIG. 496. Pistil of a Saxifrage, composed of two carpels or simple pistils united below, but distinct above ; cut across both above and below. FIG. 497. Pistil of common St. Johnswort, of three united ovaries; their styles distinct. FIG. 498. The same of another species of St. Johnswort (Hypericum prolificum), the styles also united into one, which, however, split apart in the fruit. FIG. 499. Pistil of Tradescantia or Spiderwort, even the three stigmas united into one. The ovary in all cut across to show the internal structure. FIG. 500. Cross-section of a flower of Flax; each of the five cells of the ovary partly divided by aon imperfect false partition from the back. 292 THE FLOWER. tions or growths from the dorsal suture ; whether in a simple pistil (as that of most species of Astragalus, Fig. 805), or from the back of each proper cell of a compound pistil, as in the Service-berry, the Blueberry, and the common Flax (Fig. 500). 551. We have considered only the case of compound pistils of two or more cells in the ovary. But compound pistils also not unfre- quently occur 552. With only one Cell. And of these there are two kinds to be noticed, those with exile, and those with partetal placente. That is, in the first, the ovules are borne in the axis or centre of the ovary, either at the base or on a column which occupies the centre; in the second, they are borne on some part of the parietes or walls of the ovary. The first, viz. 553. With a Free Central Placenta, is found in the Primrose, Purslane 501 (Fig. 889), and Pink families (Fig. 482, 501, 502). In the Pink family this evidently results from the ob- literation of the dissepiments (as many as there are styles or stigmas) ; and vestiges of these may be de- tected at an early stage, and sometimes at the base of the full-grown ovary; while certain plants of the same family, of otherwise identical structure, retain the par- titions even in the ripe pod. In other instances, as in Dionwa, Thrift, &e., this is doubtless a modification of parietal placentation, with ovules produced only at the bottom. This brings us to the case of compound one- celled pistils 554. With Parietal Placente, that is, with the placenta borne on the sides or parie- tes of the ovary, as in the Poppy, Caper, Cistus or Rock-Rose (Fig. 507), Violet, Sun- dew (Fig. 510), and Currant families, and many others. To comprehend this per- 503 504 505 FIG. 501. Vertical section through the compound tricarpellary ovary of a plant of Spergu- laria rubra, showing the free central placenta. 502. Transverse section of the same. FIG. 503-505. Diagrams illustrating parietal and free central placentation. 508. Cross- section of a tricarpellary ovary, with a free central placenta, produced by the obliteration of the dissepiments. 604. Section of an ovary with three strictly parietal placente. 6505. Same, except that there are incomplete partitions, THE COMPOUND PISTIL. 293 fectly, we have only to imagine two, three, or any number of pistil- leaves (like Fig. 490), arranged in a circle, to unite with one another by their contiguous edges, either without any intro- flexion or infolding at all (Fig. 504), or ‘at least without their infolded edges having reached the cen- tre and united there (Fig. 505, 506). The combina- tion is accordingly much like that by which petals unite to form a monopetalous corolla, only the edges of the pistil-leaves are always turned in, where they bear the ovules. Such an ovary may well be compared with the valvate un- opened calyx of Clematis, the” margins of the sepals more or less turned in- wards (Fig. 445). Every gradation is found between axile and parietal pla- centation, especially in the St. Johns- 506 wort family (Fig. 508, 509) and in the Gourd family. 555. An ovary with parietal placente is necessarily one-celled ; except it be divided by an anomalous partition, such as is found in Cruciferous plants, and in the Trum- pet Creeper. 556. It will be seen that parietal placente are necessarily double, like the placenta of a simple ovary, or of each carpel of a compound several- celled ovary ; but with this difference, that in these the two portions belong to the two margins of the same carpel; while in parietal placente they are formed from the coalescent margins of two adjacent carpels. 557. The number of carpels of which a compound ovary consists is indicated by the number of true dissepiments when these exist; or by the number of placentw, when these are parietal; or by the number of styles or stigmas, when these are not wholly united into one body. Thus a simple pistil has a single cell, a single placenta, * 608 509 FIG. 506. Plan of a one-celled ovary with three parietal placentz, cut across below ; the upper part showing the top of the three leaves it is composed of, approaching, but not united. FIG. 507. Ovary of Helianthemum Canadense, cut across, showing the ovules on three parietal placentz. FIG. 508. Transverse section of the ovary of Hypericum graveolens; the three large placente meeting in the centre, but not cohering. 509. Similar section of a ripe pod of the same ; the placentz now evidently parietal. : 25 * 204 THE FLOWER. and a single style. A pistil of two carpels may be two-celled, with two placentz, two styles, or two stigmas, &c.* * There are, however, some exceptions which qualify these statements : — 1. Each placenta being a double organ (556), it occasionally happens that, the two portions are separated more or less, as in Orobanchaceous plants, where a dicarpellary ovary appears on this account to have four parictal placenta ; either approximate in pairs (as in our Cancer-root, Conopholis), or equidis- tant (as in Aphyllon). 2. Analogous to this is the case where the two constituent elements of the stigma (the only essential part of the style) separate into two half-stigmas, as is partially seen in Fig. 494, 495. The stigma, no less than the placenta, belongs to the margins of the infolded leaf (545), these margins being ovul/ferous in the ovary and stigmatiferous in the style ; as Mr. Brown, the most profound botanist of this or any age, has clearly shown. These two constituent portions of the style or stigma, occasionally separate, either entirely or in part, as in Euphorbiaceous plants, in Grasses, and especially in Drosera (Fig. 510), where there are consequently twice as many nearly distinct styles as there are parietal placenta in the compound ovary If the two component parts of the style of each carpel were reunited into one, in the usual manner, their number would equal the placenta, and their position would be alter- nate with the latter. But since, in parietal placentation, each halfplacenta is confluent (not with its fellow of the same carpel, but) with the contiguous halfplacenta of the adjacent carpel, it were surely no greater anomaly for the clements of such ha/fstigmas as those of Drosera to follow the same course. This is precisely what takes place in Parnassia, and in other cases where the stigmas are opposite the parietal placente ; — cases which were thought to be very anomalous, merely on account of the adoption of a false principle (that of the necessary alternation of the stigmas and placente), but which are really no more extraordinary than parictal placentation itself 8. Furthermore, the production of ovules is not always restricted to what answers to the margins of the carpellary leaves. Jn the Poppy, the whole sur- face of the long, imperfect partitions is covered with ovules; in Butomus, they are borne over the whole internal face of each carpel, and in Water-Lilies over the whole surface, except the inner angle of each cell, where alone they normally belong. Reduced to two in the allied Water-Shicld (Brasenia, Fig. 684), the ovules grow from the dorsal suture, or the midrib of the carpellary leaf alonc ! And in the allied Cabomba itself we usually find its three ovules, one’on the dorsal and one on the ventral suture, and the third on some variable part of the face of the cell in the vicinity of either suture. In Obolaria, Bartonia (Centau- rella, Michz.), and in several species of Gentian, a compound one-celled ovary is ovutiferous over the whole face of the cell ! All placentation is very differently explained by those who adopt the hypoth- FIG. 510. Pistil of Drosera filiformis, with three deeply two-parted styles: the ovary cut across, showing three parietal placentez. THE COMPOUND PISTIL. 295 558. When the styles are separate towards the summit, but united below, they are usually described as a single organ; which is said to be parted, cleft, lobed, &c., according to the extent of cohe- sion. This language was adopted, as in the case of leaves (281) and floral envelopes (462), long before the real structure was under- esis of Schleiden, Endlicher, and others. According to this new view, since buds regularly arise from the axils of leaves and from the extremity of the stem or axis, and only in some exceptional and abnormal cases from the margins or surface of leaves, so ovules, which are viewed as a form of buds, are considered to arise from the receptacle, either from the axis of the flower, like terminal buds, or from the axils of the carpellary leaves, like axillary buds. Thus, placents are supposed to belong to the stem, and not to the carpellary leaves ; and a one-celled ovary, with one or more ovules arising from the base of the cell, would nearly represent the typical state of the gynzcium. This theory, which the intelligent student may easily apply in detail, offers a ready explana- tion of free central placentation, especially in such cases as Primula, &c., where not a trace of dissepiments is ever discoverable. But in Caryophyllacex the dissepiments are often manifest. In applying it to ordinary central placenta- tion, we have to suppose the cohesion of the inflexed margins of the carpellary Icaves with a central prolongation of the axis or receptacle which bears the placente. But in parietal placentation, the advocates of this theory are driven to the violent supposition that the axis divides within the compound ovary into twice as many branches as the carpels in its composition, and that these branches regularly adhere, in pairs, one to each margin of all the carpellary leaves. Its application is attended with still greater difficulties in the case of simple and uncombined pistils, where the ovules occupy the whole inner suture, which must be taken as the typical state of the gynecium ; but to which the new hypothesis can be adapted only by supposing that an ovuliferous branch of the axis enters each carpel, and separates into two parts, one cohering with each margin of the metamorphosed leaf. This view, however, not only appears absurd, but may be disproved by direct observation, as it has been most completely by those monstrosities in which an anther is changed into a pistil, or even one part of the anther is thus transformed and bears ovules, while the other, as well 4s the filament, remains unchanged ; — a case where the ovules are far removed from anything which can possibly belong to the axis. We may further remark, that even the appearance of a placenta or ovuliferous body in the apparent axil of a carpellary leaf no more proves that the body in question belongs to the axis, than that the appendage before the petals of Parnassia and the American Lin- den represents a branch instead of a leaf. As to the terminal naked ovule of the Yew, where the structure, on any view, is reduced to the greatest possible simplicity, it is surely as probable that it answers to the earliest formed, or foliar, portion of the ultimate phyton, here alone developed, as to the cauline part, which so seldom appears in the flower. The most important of these points are clucidated by Mr. Brown, in Plante Javanice Rariores, pp. 107-112, in two notes, which apparently are not sufficiently studied by botanists. 296 THE FLOWER. stood: but, as it involves an erroneous idea, the expressions, Styles distinct ; united at the base; united to the middle, or summit, &c., as the case may be, should be employed in preference. 559. A few casual exceptions occur to the general rule that ovules and seeds are both produced and matured within an ovary, namely, in a closed carpellary leaf or set of combined carpellary leaves. In the Blue Cohosh (Caulophyllum thalictroides) the ovules rupture the ovary soon after flowering, and the seeds become naked; and in Mignonette they are imperfectly enclosed, the ovary being open at the summit from an early period. In all such cases, how- ever, the pistil is formed and the ovules are fertilized in the ordi- nary way. 560. Gynacium of Gymnospermous Plants, A far more remarkable exception is presented by two natural families, viz. Coniferae (Pines, Firs, &e.) and Cycadacea vs (Cyeas, Zamia). Here the pistil, as likewise the | whole flower, is reduced to UY the last degree of simplici- 612 54 ty; each fertile flower con- sisting merely of an open carpellary leaf, in place of an ordinary pistil, in the form of a scale (Fig. 511 — 518, 515, 516), or of some other shape, and bearing two or more ovules upon some part of its upper surface. At the time of blossoming, these pistil-leaves of the forming cone diverge, and the pol- len, abundantly shed from the staminate blossoms, falls directly upon the exposed ovules, Afterwards the scales close over each other until the seeds are ripe. In the Yew there is no carpel or pistil-leaf at all; but the fertile blossom consists of a solitary naked ovule, borne on the extremity of a FIG. 611. Scale, i. e. open pistil, from the cone of a Larch, at the time of flowering, or a little later ; the upper side seen, with its pair of naked ovules. FIG. 512. Similar view of a Larch scale, when the seeds are partly grown. 513. A maturo scale, one of the seeds in its place, the other fallen (reduced in size). 514. A seed detached, with its wing. FIG 515. Branchlet of the American Arbor-Vite, considerably larger than in nature, ter- minated by its pistillate flowers, each consisting of a single scale (an open pistil), together forming a small cone. 516. One of the scales or pistils removed and more enlarged, the inside exposed to view, showing a pair of naked ovules on its base. THE OVULE. 297 short branch, and surrounded by a few small bracts. As the ovules are here naked and exposed to the direct contact of the pollen, and the seeds are not enclosed in anything answering to a pod, these have received the name of Gymnosrpermous Piants, that is, plants with naked seeds. Sect. VIII. Tur Ovure. 561. Ovures (420, 543) are bodies borne by the pistil, which, on being fertilized and having an embryo developed in them, become seeds. To their formation, fertilization, and protection all the other parts of the blossom are subservient. They vary greatly in num- ber, from one (solitary) in each carpel or cell to a multitude. When few and uniform in number, they are said to be definite ; when too numerous to be readily counted, indefinite. 562. As to situation and direction, they are erect when they arise from the very bottom of the cell (Fig. 518); ascending, when fixed above its base and rising obliquely upwards (Fig. 517); horizontal, when they project from the side of the cell, without turning either up- wards or downwards (Fig. 342) ; pendulous, when they hang or turn ‘obliquely downwards (Fig. 887) ; and suspended when hanging perpendicularly from the very summit of the cell (Fig. 519). These terms apply to the seed as well as to the ovule. 563. An ovule is at first a minute projection of the placenta (Fig. 530), of soft and homogencous parenchyma; but it soon acquires a definite form and structure. Jt may be either sessile, or raised on a stalk, the Funrcutts, Poposperm, or seed-stalk. The point of attachment, which in the seed forms the scar, is called the Hitvm. 564. It consists of a kernel or nzcleus, and usually of one or two coats. The nucleus is the essential part of the organ; in it the embryo is formed, and the coats become the integuments of the seed. The ovule of the Mistletoe consists of a naked nucleus only, there being no integument. The ovule of the Walnut has only one FIG. 517. Ovary of a Buttercup, divided lengthwise, to display its ascending ovule. 518. ded Same of Buckwheat, with an erect ovule. 519, Same of A , With a susp ovule. 298 THE FLOWER. coat: this appears as a circular ring around the base of the forming nucleus, which gradually becomes cup-shaped, and at length covers it like a sae, remaining open, however, at the summit. This ea 693 orifice is called the Foramen, or Micropyte. In far the greater number of cases, a second envelope is formed out- side of the first, beginning in the same way, though always later than the inner one, which, however, it eventually over- takes and encloses. Mirbel named the exterior coat of the ovule the Priming, and the in- terior the SecuNDINE, — names which are attended with the objec- tion that the secundine or inner coat is actually older than the primine or exterior coat. Both sacs are open at the apex, and the summit of the nucleus points directly towards the apertures. The orifice or foramen of the primine or exterior integument is called the ExosTome (or outer orifice) ; that of the interior or secundine, the Enposromx (or inner orifice). The coats of the ovule and the nucleus are distinct and unconnected, except at the base, or point of attachment to the funiculus, where they are all confluent: this point of union receives the name of the Cuauaza (Fig. 521, d). Through the funiculus and chalaza the ovule derives its nourish- ment from the placenta; through the opening at the summit, the nucleus receives the tubular prolongation of the pollen, which incites the formation of the embryo. : 565. Ovules occur under four principal forms, viz. the orthotro- pous or straight, the campylotropous or curved, the amphitropous or half-inverted, and the anatropous or inverted. The simplest, al- though the least common of these, is 566. The Orthotropous Ovule, also termed atropous (viz. not turned). It is the form which this organ assumes in the Buckwheat family (Fig. 518), and several others, and is likewise shown in Fig. 520, 526, and a longitudinal section of it in Fig.521. Here no change in FIG. 520. An orthotropous ovule. 621. Longitudinal section of the same, more magnified: a, the primine; }, the secundine; c, the nucleus; @, the chalaza, 522. An amphitropous ovule. 623. Three anatropous ovules, with long funiculi, attached to a portion of the placenta. 524. One of the same, more highly magnified, exhibiting its cellular structure. 525. A campy- lJotropous ovule. THE OVULE. 299 the direction of parts occurs during growth; but the base or chalaza (Fig. 526, ec) is manifestly the point of attachment, the orifice (f) is at the opposite end, and the ovule is straight and symmetrical. 567. The Campylotropous Ovule (Fig. 525, 527) is one which grows unequally, and consequently curves upon itself, so as to bring the apex round to the vicinity of the base, the chalaza (c) and the orifice (f) being at length brought nearly into contact at the point of at- tachment. Campylotropous or curved ovules are found in the Mig- nonette, in all Cruciferous and Caryophyllaceous plants, and in many others. 568. The Anatropous Ovule (Fig. 517, 519, 523, 524, 529) is far the most common form. It is best described by likening it to an orthotropous ovule which as it grew had inverted itself on its funicu- lus or support, so that, while the body remains straight, its orifice or apex is brought down to the funiculus and points to the placenta, while the chalaza occupies the apparent or geometrical apex, i. e. the summit or point directly opposite the place of attachment. The ovule, thus inverted on its support, coheres with it for its whole length, and accordingly has a ridge or ‘cord, more or less manifest, along one side (Fig. 529, r), connect- ing the Ailum, or place of attachment, and where the seed separates from its insertion (/), with the chalaza (ce). This cord or ridge, which morphologically is merely a continuation of the stalk or support of the ovule adhe- rent to its face on one side, or incorporated with it, is called the Ruaruer. It is a distinguishing mark of an anatropous ovule, which is also recognizable by its’ being straight and by having the orifice close to the point of attach- ment. The rhaphe itself is often so incorporated with the coat of FIG. 526. Orthotropous ovule of Buckwheat: c, hilum and chalaza ;_/f, orifice. FIG. 527. Campylotropous ovule of a Chickweed : c, hilum and chalaza ; /, orifice. FIG. 528. Amphitropous ovule of Mallow : /, orifice ; 4, hilum ; 7, rhaphe ; ¢, chalaza. FIG 529. Anatropous ovule of a Violet ; the parts lettered as in the last. FIG. 580. Vertical section of a pistil of Magnolia Umbrella, from a young flower-bud, mag- nified, showing the forming ovule, here a simple protuberance. 800 FERTILIZATION. the ovule or the seed as to be externally undistinguishable. The seeds of Magnolia offer good illustrations of this. The mode of formation and the internal structure of anatropous or inverted ovules will be apparent on inspection of Fig. 530-5386. 531 532 569. The Amphitropons Ovule (Fig. 522, 528), also called heterotro- pous, differs from the anatropous in having a short rhaphe (Fig. 528, r), extending from the chalaza (c) only about half-way to the orifice (f). It is attached accordingly by the middle of one side, and has the chalaza at one end and the orifice at the other. It may be regarded as a half-anatropous or half-inverted ovule; and all gra- dations occur between this and the anatropous form, into which it would pass by the cohesion of the side of the ovule with the support a little farther down. Amphitropous ovules are general in the Mal- low and the Primrose families. As such an ovule stands with its axis at right angles with the funiculus, if there be any, it is also said to be transverse. 70. Most of these terms apply to seeds as well as to ovules; and the general structure of the seed may be known beforehand from that of the ovules. We are now prepared to contemplate the pro- cess by which an ovule becomes a seed. Srecr. IX. FerrriizaTtion and Formation or THE Empryo. 571. In order to the formation of the embryo (118), the ovules require to be fertilized by the pollen. Cases of parthenogenesis, i. e. of the formation of perfect seed without the agency of pollen, doubtless do sometimes occur, and have been noted in several FIG. 581. A similar side-view of the ovule of the last, a week or two later, and more mag- nified ; showing the nucleus encircled by the coats in formation, as two rings or shallow cups one Within the other. 632 The same, a few days later, more advanced and beginning to turn. 533. The same, further advanced. 534. The same, soon after, with the inversion almost complete, and the outer coat covering the inner, except at the orifice. 535. The completed anatropous ovule rom 4 full-grown flower-bud. 536. A longitudinal section of the same, displaying the rhaphe, the two coats, and the nucleus. THE ACCESS OF THE POLLEN. 801 dicecious plants. More than half a century ago, Spallanzani found that the pistillate blossoms of Hemp may produce fertile seed with- out the concurrence of pollen; and recently Naudin and Decaisne have confirmed the fact by experiment, and from seeds produced without fertilization have raised a second generation of plants, the pistillate individuals of which, kept from all access of pollen, have themselves ripened seeds with perfect embryos.* Two or three dicecious Euphorbiaceous plants are known to produce good seed under the same circumstances, and Naudin has shown it freely to occur in Bryony. Still these are very exceptional cases, and are all confined, so far as known, to dicecious plants. Ordinarily the access of pollen of the species to the ovules is necessary to the production of the embryo. 572. The Access of the Pollen to the pistil is secured in a great variety of ways and adaptations. In hermaphrodite blossoms the relative length and position of the stamens and stigmas are com- monly so adjusted that the pollen may fall directly upon the . stigma, the anthers being usually higher than the stigmas when the flower is upright, and shorter when it is nodding. Sometimes poylen is projected upon the stigma by transient and often sudden mo,yements, either mechanical, as in Kalmia, or spontaneous and vitayl, as in the Barberry (to be mentioned in another place). Some- time. fertilization takes place in the bud, where the parts are in appcpsition, or the anthers are kept in contact with or proximity to. the ee as in papilionaceous flowers by the enclosing keel-petals,. and jin the Fumitory family by a close-fitting little sac formed of the d spoon-shaped tips of the two inner petals confining the an-. to the stigma. Very often the pollen is conveyed from the antifers to the stigma by insects, searching for honey or nectar; and theite are many species in which fertilization seems absolutely to depend upon the agency of insects; such, for instance, as those of Axistolochia, Asclepias or Milkweed, and many plants of the Orchis family. In dicecious and many moncecious plants, with widely sep- arated blossoms, fertilization is mainly dependent upon insects, pass~ ing from flower to flower, and upon winds and currents. And the immense quantity of pollen which many such plants produce com-- pensates for the greater distance of the passage, and greatly dimin- ishes the chance of failure. The air of a Pine forest in flowering- * Comptes Rendus, Vol. 43, 1856, and Hooker’s Journal of Botany, 1857, p. 53. 26 302 FERTILIZATION. time is almost loaded with pollen, some of which is often wafted by the winds for many miles. 573. The pollen of Pines and other Gymnospermous plants falls directly upon the naked and exposed ovules (560). On all others, the ovules, being secluded in a closed ovary, can be fertilized only through the stigma. In these, accordingly, we have first to con- sider. 574. The Action of Pollen on the Stigma. The loose papilla, or often the short projecting hairs of the stigma, and the moist surface, serve to retain the grains of pollen on the stigma when they have once reached it. Absorbing some of this moisture, and nourished by it, the grains of pollen which are favorably situated soon begin to grow, or, as we may say, to germinate. The thin inner mem- brane (534) extends, breaks through the thicker, but weak or brittle, outer coat at some point (or rarely at two or three places), and lengthens into a delicate tube, filled with the- liquid and molecular matter that the grain contains. This tube (Fig. 5387 — 540), remain- ing closed at the extremity, penetrates the loose tissue of the stigma, and is prolonged downwards into the style, gliding along the inter,’. spaces between the very loosely disposed cells of the moist conduet- ing tissue (541), which extends from the stigma to the cavity of the ovary, and at length reaches the placenta, or some other part of the lining of f the ovary, and its extremity appears in ¢ the cell. This prolongation into a tube, often many hundred times the diameter off the pollen-grain, is a true growth, after the njan- ner of elongating cells (87 — 97), nourisshed by the organizable moisture of the style which it imbibes in its course. Now ‘the orifice of the ovules, or a projection ‘of the nucleus beyond the orifice, is at tlais time brought into contact with, or close proximity to, that portion of the walls of the ovary from which the pollen-tubes project; and a pollen-tube thus enters the orifice of each ovule, and reaches the nucleus, in which the nascent embryo, 537 538 539 ey FIG. 537. A pollen-grain of Datura Stramonium, emitting its tube. 588. Pollen-grain of a:Conyolvulus, with its tube. 6539. Other pollen-grains, with their tubes, less strongly mag: nified. 640. A pollen-grain of the Evening Primrose, resting on a portion of the stigma, into which the tube emitted from one of the angles penetrates ; the opposite angle also emitting a pollen-tube. THE ACTION OF THE POLLEN. 303 subsequently appears. In. Gymnospermous plants (560, 573), the pollen-grains grow at the orifice of the naked ovule, and immediately penetrate its nucleus, just as they do the stigma in ordinary plants. 575. Pollen-tubes may be readily inspected under the microscope in many plants; in none more readily than in the Asclepias, or Milkweed, one of the plants in which this subject was so admirably investigated by Mr. Brown. In that family, the pollen-grains of each cell of the anther (Fig. 541) cohere in a mass; and these pollen-masses, dislodged from their cells (Fig. 542, 543), usually by the agency of insects, and brought into proximity with the base of the stigma, protrude their tubes in great abundance. They may be seen to penetrate the base of the stigma, as in Fig. 544, and sepa- rate grains with their tubes may be detached from the mass (Fig. 546, 547); but to trace their course down the style (as in Fig. 545), and to their final destination, requires much skill in manipulation and the best means of research. 576. The formation of the pollen-tube commences in some cases almost immediately upon the applica- tion of the pollen to the stigma; in others it is not per- ceptible until after the lapse of from ten to thirty-six hours or more. The rate of the growth of the pollen-tube down the style is also very various in dif- ferent plants. In some species, a week or more elapses before they have passed through a style even of a few lines in length. In others, a few FIG. 541. A back view of a stamen of the common Milkweed (Asclepias), the appendage cutaway. 542. A stamen more magnified, with the two pollen-masses cohering by their cau- dicles, each toa gland from the summit of the stigmatic body, to which a pollen-mass from an adjacent anther is already adherent. 643. A pair of detached pollen-masses (each from a dif- ferent anther) suspended by their caudicles from the gland. 544. Some of the pollen-masses, with their tubes penetrating the stigma (after Brown). 645. A section through the large stig- matic body and a part of the summit of one of the styles, showing the course of the pollen- tubes. 546, 547. Pollen-grains with their tubes, highly magnified. (The structure of these singular flowers will be more fully explained under the order Asclepiadacee.) 304 FERTILIZATION. hours suffice for their passage through even the longest styles, such as those of Colchicum, Mirabilis or Four-o’clock, and Cereus grandi- florus. After the pollen-tubes have penetrated the stigma, the latter dries up, and its tissue begins to wither or die away, as likewise does the body of the pollen-grain, its whole contents being trans- ferred to the pollen-tube, the lower part of which may still be in a growing condition. 577. Before the pollen-tube has reached the ovule, or more com- monly even before the pollen is applied to the stigma, a cavity ap- pears in the interior of the nucleus of the ovule, near its apex. This probably results from the special growth of a particular cell, which expands into a bladder or closed sac, at length commonly oc- cupying a considerable part of the nucleus, — sometimes remaining enclosed in its tissue towards its summit or orifice, sometimes dis- placing the upper part of the nucleus entirely, or even projecting through the micropyle. This is the sac of the amnios of Mr. Brown, the embryo-sae (sac embryonatre) of the French botanists. In this sac the embryo is formed. 578. Origin of the Embryo, From the latter part of the seven- teenth century, when the relative functions of the stamens and the pistils, and something of the structure of the ovule, were demon- strated by Malpighi, Grew, &e., until about the year 1837, it was almost universally supposed that the embryo was a product of the ovule, in some way incited or fertilized by the pollen. One writer, viz. Samuel Morland, had indeed propounded the crude hypothesis, that a pollen-grain itself, descending bodily through the style, was received into the orifice of the ovule, and became the embryo. The absurdity of this view was soon made evident. But how the pollen acted was wholly unknown until Amici, in 1823, discovered pollen- tubes, penetrating the stigma, and Brongniart, Brown, Amici himself, and Schleiden, within the ensuing twelve or fourteen years, had demonstrated their universality, and traced these slender tubes into the ovary, and even to the nucleus of the ovule. Then commenced a spirited controversy, which has only just now been brought to a close. For Professor Schleiden, in the year 1837, advanced the view that the extremity of the tube of the pollen, entering the nucleus of the ovule, there developed into the embryo, — thus anew deriving the embryo or new plant substantially from the pollen instead of the ovule. This view has recently been abandoned by its indefatigable author and his most able supporter, Schacht, having been thoroughly dis- ORIGIN OF THE EMBRYO. 805 proved in all points by a series of elaborate investigations made by Mirbel, Amici, Giraud, Moll, Hofmeister, Unger, Tulasne, Henfrey; and Radlkofer. So that — passing by the whole history of this long discussion, and merely appending some references to the more im- portant publications upon the subject * — we need only state here, in the most general terms, the principal facts which are now held to be established, viz. :— 579. The pollen-tube terminates on the outer surface of the embryo-sac, or sometimes, perhaps, forces its way into it. Ordina- rily its extremity becomes firmly adherent to the surface of the embryo-sac, and it appears to remain closed. Henfrey, indeed, is led to suppose that the membrane of the pollen-tube and that of the embryo-sac are absorbed at the point of contact, and that the former thus discharges its contents into the cavity of the latter; but this is merely an unproved inference, suggested by the analogy of what is now known of the process of fecundation in Cryptogamous plants. At present it appears most probable that the contents of the pollen- tube are drawn into the embryo-sac by endosmosis. However this may be, shortly after reaching the embryo-sac the pollen-tube be- comes empty, and: decays or withers away. Meanwhile the body which by its development is to give rise to the embryo appears in the embryo-sac independent of the pollen-tube. According to most investigators it generally appears before the pollen-tube has entered the ovule. (The high authority of Tulasne, however, is thus far * Schleiden first published his famous theory in Wiegmann’s Archiv, 1837, and in Acta Nova Acad. Nat. Cur., Vol. 19. It was extended and defended in his systematic works, —and especially by Schacht in Trans. Netherlands Insti- tute, 1850, in Bot. Zeitung, 1855 (transl. in Ann. Sci. Nat. of that year), in his Beitriige Anat. g Phys., in his work on the microscope, of which an English translation by Dr. Currey was published in 1855, and in the Regensberg Flora, 1855 (Ann. Sci. Nat. 1855). See also Deecke in Bot. Zeitung, 1855 (Ann. Sci. Nat., 1. c.). On the other side of the question the most important of the recent publications, since the appearance of Mohl’s Principles of the Anatomy and Physiology of the Vegetable Cell, in the English translation (1852), and the article Ovule in the Alicrographic Dictionary by Henfrey, are: Hofmeister, in Flora, May, 1855, and Mohl, in Bot. Zeitung, June, 1855 (both reproduced in Ann. Sci. Nat., ser. 4, Vol. 8, 1855); Tulasne, in Ann. Sci. Nat., ser. 4, Vol. 4, 1855, being the complement of his great memoir published in the same journal (ser. 3, Vol. 12, 1849) ; Radlkofer, Die Befruchtung der Phanerogamien, Leipsic, 1856 ; Henfrey, Development of the Ovule of Santalum album, &c., in Trans. Linn. Soc., Vol. 22, part 1, 1856. 26 * 306 FERTILIZATION. opposed to the pre-existence.) It is a small mass or globule of pro- toplasmic matter, either loose in the cavity of the embryo-sac near the place to which the pollen-tube is applied externally, or else ad- herent to the interior surface of the wall of the embryo-sac in this immediate vicinity, or sometimes separated from the embryo-sac by’ an interposed globule, or by a pair of such globules. This body, the rudiment of the future embryo, has been. termed the embryonal or germinal vesicle. This is not yet a cell; for it has no covering or wall of cellulose. But it soon becomes one when a pollen-tube reaches the embryo-sac, the first known result of fertilization being that a coat of cel- lulose is deposited upon its surface. This newly-formed cell grows by cell-multiplication (83), either pro- ducing a mass of cells, as shown in Fig. 10 - 14, or else in the first place developing into an elongated cell or a thread-shaped. chain of cells (the suspensor), the lower cell of which divides in all directions, forming a mass, which as it grows shapes itself into the embryo (Fig. 649-553), The radicle or root-end of the em- bryo is always that by which it is attached to the suspensor (which ordinarily soon disappears) or to the summit of the embryo-sac, the coty- “thy ledons occupying the opposite ex- “lbp ZATRRUAI ta LOT J 548 ihe i tremity. The radicle accordingly is ‘always directed to the orifice or micropyle of the ovule and seed. 580. Through the fertilization of as many germinal vesicles, two or more embryos are frequently found in the same seed, in the Orange, the Onion, and many other plants. There are generally FIG. 548. Magnified pistil of Buckwheat; the ovary and ovule divided lengthwise : some pollen on the stigmas, one grain distinctly showing its tube, which has penetrated the style, reappeared in the cavity of the ovary, entered the mouth of the orthotropous oyule (0), and reached the embryo-sac (s), near the embryonal vesicle (v). FORMATION OF THE EMBRYO. 307 two embryos in the seed of the Mistletoe ; and there is usually a plurality of embryos in Pines and other Gymnospermous plants (560), though all but one 519 550 551 552 553 are more commonly abor- tive or rudimentary. There are other striking peculiar- ities in the fecundation of Pines, &c., which, however, cannot be readily explained without entering into more detail than is here advisable.* In Pines and their allies, moreover, the embryo is not developed until a long time after the application of the pollen, and the filling of the embryo-sac with the cellular tissue which forms the basis of the albumen of the seed ; the fruit and seed of true Pines, as is well known, not maturing un- til the year after that in which the blossoms appear. 580’. The further development and the structure of the embryo and the seed must be considered after the Fruit, of which it consti- tutes a part. * See Hofmeister, Untersuchungen, &c.: Researches into the Fertilization, &c. of the higher Cryptogamia and the Conifers (Leipsic, 1851), with scven plates devoted to the embryology of Conifer. FIG. 549. Diagram of the suspensor and forming embryo at its extremity. 550. The same, with the embryo a little more developed. 551. ‘he same, more developed still, the cotyledons faintly indicated at the lower end. 552. Same, with the incipient cotyledons more manifest. 558. The embryo nearly completed. 7 ' FIG 654-556. Forming embryo from a half-grown seed of Buckwheat, in three stages. 557. Same, with the cotyledons fully developed. 308 THE FRUIT. CHAPTER X. : OF THE FRUIT. Sect. I. Irs Structurr, TRANSFORMATIONS, AND DEHISCENCE. 581. Tue fertilized ovary, increased in size, and usually under- going some change in texture and form, becomes 582. The Pericarp, or Seed-vessel. The pericarp and the seeds it contains together constitute the Fruit; a term which has a more extensive signification in botanical than in ordinary language, being applied to all mature pistils, of whatever form, size, or texture. To the fruit likewise belongs whatever organs may be adnate to the pistils (468). Such incorporated parts, like the fleshy calyx of the Apple and Quince (Fig. 809, 812), sometimes make up the principal bulk of the fruit. 583. Indeed, the calyx, when wholly free from the pistil, sometimes becomes greatly g, and is thickened and pulpy after flowering, transformed into what appears like a berry ; as in Gaultheria (Fig. 913), where the real fruit is a dry pod within; and in Strawberry Blite (Fig. 1099), where the fleshy calyxes of a head of flowers each surround a small seed- like fruit, and together form a false multiple fruit, resembling a strawberry. 584. Even the strawberry itself is not a fruit in the strict botanical sense: that is, the edible substance is not a ripened pistil, nor a cluster of pistils, but is the receptacle or ex- tremity of the flower-stalk, greatly enlarged and replete with delicious juice ; the true fruits being the minute and seed-like ripened ovaries scattered over its surface ; as plainly appears from a comparison of Fig. 558 with 559. Moreover, a mulberry, FIG. 558. Vertical section of a forming strawberry, enlarged. FIG. 559. Similar section of one half of a ripe strawberry, and of some of the small seed- like fruits, or achenia, on its surface. ITS STRUCTURE AND TRANSFORMATIONS. 809 a fig, and a pine-apple consist of the ripened products of many flowers, crowded on an axis or common receptacle, which makes a part of the edible mass. 585. Under the general name of fruit, therefore, even as the word is used by the botanists, things of very different structure or. of dif- ferent degrees of complexity are confounded. We must distinguish, therefore, between simple fruits, resulting from a single flower, and a multiple frutt, resulting from the parts of more than one flower combined or collected into a mass. We must also distinguish be- tween true fruits, formed of a matured pistil, either alone or with a calyx, &c. adnate to it, and fruits, so called, of which the pericarp does not form an essential part. 586. Obliteration or Alteration. The pericarp, being merely the pistil matured, should accord in structure with the latter, and con- tain no organs or parts that do not exist in the fertilized ovary. Some alterations, however, often take place during the growth of the fruit, in consequence of the abortion or obliteration of parts. Thus, the ovary of the Oak consists of three cells, with a pair of ovules in each; but the acorn, or ripened fruit, presents a single cell, filled with a solitary seed. Jn this case, only one ovule is matured, and two cells and five ovules are suppressed. The ovary of the Horsechestnut and Buckeye is similar in structure (Fig. 777 —780), and seldom ripens more than one or two seeds ; but the abortive seeds and cells may be detected in the ripe fruit. The ovary of the Birch and of the Elm is two-celled, with a single ovule in each cell: the fruit is one-celled, with a solitary seed; one of the ovules or young seeds being uniformly abortive, while the other in enlarging thrusts the dissepiment to one side, so as gradually to ob- literate the empty cell; and similar instances of suppression in the fruit of parts actually extant in the ovary are not uncommon. On the other hand, there are sometimes more cells in the fruit than properly belong to the pistil. For instance, the ovary of Datura Stramonium is two-celled; but the fruit soon becomes spuriously four-celled by a false partition connecting éach placenta with the dorsal suture. So the compound ovary of Flax when young is five- celled, but with a strong projection from the back of each cell (Fig. 500) which at maturity divides the cell into two, thus rendering the fruit ten-celled. And some legumes are divided transversely into several cells, although the ovary was one-celled with a continu- ous cavity in the flower. 310 THE FRUIT. 587. Ripening, The pericarp sometimes remains herbaceous in texture, like the pea-pod, or becomes thin, dry, and membranaceous, like the pod of the Bladder-Senna. In such cases it is furnished with stomates, continues to have chlorophyll in its cells, and acts upon the air like an ordinary leaf. In other plants the pericarp thickens, and either becomes hard and dry, like a nut, or else fleshy or pulpy, like a berry (gooseberry, grape, &c.). Sometimes the outer portion softens into flesh or pulp, while the inner portion hard- ens, thus forming a stone-fruit, like the cherry and peach. 587’. Most fleshy or pulpy fruits are tasteless or slightly bitter during their early growth; at which period their structure and chemical composition are similar to that of leaves, consisting of cel- lular with some woody tissue ; and their action upon the atmosphere is likewise the same (346). In their second stage, they become sour, from the production of acids (353); such as tartaric acid in the grape ; the citric, in the lemon, orange, and the cranberry ; the malic, in the apple, gooseberry, &c. At this period they exhale very ° little oxygen, or even absorb that substance from the surrounding air. The acid increases until the fruit begins to ripen, when it grad- ually diminishes, and sugar is formed. In the third stage, or that of ripening, the acids, as well as the fibrous and cellular tissues, gradu- ally diminish as the quantity of sugar increases ; the latter being produced partly at the expense of the former. A chemical change, similar to that of ripening, takes place when the green fruits are cooked ; the acid and the mucilaginous or other products, by the aid of heat reacting upon each other, are both converted into sugar. Mingled with the saccharine matter, a large quantity of vegetable jelly (83) is also produced in most acidulated pulpy fruits, ex- isting in the form of pectine and pectic acid. These arise from the reaction of the vegetable acids during ripening upon the dex- trine and other ternary products accumulated in the fruit. 588. When the walls of a pericarp form two or more layers of dissimilar texture, the outer layer is called the Epicarp, the middle one, Mesocarp, and the innermost, Endocarp. A stone-fruit or drupe, like the peach, consists of two layers, viz. the outer or fleshy layer, which is therefore termed the Sarcocarp, and the inner, or endocarp, the shell or stone, which is also termed the Putamen. 589. Fruits also may be divided into the indehiscent or closed, and the dehiscent or those that open. TF leshy fruits generally, stone- fruits, and many dry fruits, especially one-seeded ones, such as nuts, ITS KINDS. 3811 achenia, &e., remain indehiscent ; while most pods or capsules dehisce at maturity. 590. Some pods burst irregularly when ripe and dry; others open and shed their seeds by definite pores, as the Poppy, or by larger holes, chinks, or valves, as the Campanula, Snapdragon, &c.; or by a transverse line cutting off the top of the pod, as in Henbane and Purslane. These are modes of trregular dehiscence. But 591. Dehiscenee, when regular and normal, is effected by a vertical separation or splitting, viz. by the opening of one or both sutures of the ovary (543), or, in a fruit resulting from a compound ovary (548), by the disjunction of the united parts. The several modes of dehis- cence will be characterized under the kinds of fruit in which they occur (607-614). Sect. II. Tur Kinps or Frouir. 592. THe various kinds of fruits have been minutely classified and named ; but the terms in ordinary use are not very numerous. A rigorously exact and particular classification, discriminating be- tween the fruits derived from simple and from compound pistils, or between those with and without an adnate calyx, becomes too recon- dite and technical for practical purposes. It is neither convenient nor philosophical to give a substantive name to every variation of the same organ. For all ordinary purposes it will suffice to char- acterize the principal kinds under the four classes of Simple, Aggre- gate, Accessory or Anthocarpous, and Multiple Fruits. 593. Simple Fruits are those which result from the ripening of a single pistil, whether with or without a calyx or other parts adnate to it. This division comprises most of the kinds of fruit which have distinctive names, and those of the other classes are mainly aggre- gations or combinations of these. : 594. Simple Fruits may be conveniently divided into Mleshy fruits, Stone fruits, and Dry fruits. The leading kind of the first division is 595. The Berry (Bacea), an indehiscent fruit which is fleshy or pulpy throughout. The grape, gooseberry, currant, cranberry, and tomato are familiar examples. 596. The Hesperidium (orange, lemon, and lime) is merely a berry with a leathery rind. 312 THE FRUIT. 597. The Pepo, or Gourd-fruit, is also a modification of the berry, with a hard rind, which occurs in the Gourd family. The cucum- ber, melon, and squash are familiar illustrations. A Pepo is an indehiscent, externally firm and internally pulpy fruit, composed usually of three carpels, and with an adnate calyx. In the ovary it is either one-celled with three broad and revolute parietal placenta, or these placents, borne on slender dissepiments, meet in the axis, enlarge, and spread, unite with their fellows on each side, and are reflected to the walls of the pericarp, next which they bear their ovules (Fig. 560, 561). As the fruit enlarges, the seed-bearing placente usually cohere with the walls, and the partitions are oblit- erated, giving the appearance of a peculiar abnormal placentation, which only the study of the ovary readily explains. 598. A Pome, such as the apple, pear, and quince (Fig. 809, 812), is a fruit composed of two or more carpels, cither papery, cartilagi- nous, or bony, usually more or less involved in a pulpy expansion of the receptacle or disk, and the whole invested by the thickened and succulent tube of the calyx. It may be readily understood by comparing a rose-hip with an apple. The calyx makes the princi- pal thickness of the flesh of the apple, and the whole of 560 561 that of the quince. \ 599. The Drupe, or Stone- Fruit, is a one-celled, one or two seeded indehiscent fruit, with the inner part of the peri- | = 3 carp (endocarp, or putamen, 388 oe 588) hard or bony, while the outer (exocarp, or sarcocarp) is fleshy or pulpy It is the latter which in these fruits so readily takes an increased development in cultivation. The name is strictly FIG. 560. Section of the ovary of the Gourd. 561. Diagram of one of its constituent carpels. FIG 562. Vertical section of a peach. 563 An almond; where the exocarp, the portion of the pericarp that represents the pulp of the peach, remains thin and juiceless, and at length separates by dehiscence from the endocarp, or shell. ITS KINDS. 813 applicable only to fruits produced by the ripening of a one-celled pistil; as the plum, peach (Fig. 562), &c.; but it is extended in a general way to such fruits with two or more bony cells enclosed in pulp, as that of the Dogwood, &c. 600. The raspberry and blackberry (Fig. 564) are composed of a great number of miniature stone- fruits, or drupelets, as they might be called, in struc- ture resembling cherries (Fig. 565), aggregated upon - an elongated receptacle, 601. Dry Fruits may be either dehiscent or indehis- cent (589). Of indehiscent dry fruits one of the simplest kinds is 602. The Achenium, or Akene (Fig. 566-573). This includes all one- seeded, dry and hard, indehiscent and seed~ like, small fruits, such as are popularly taken for naked seeds. But that they are true pistils or ovaries ripened is evident from the styles or stigmas they bear, or from the scar left by their fall; and a section brings to view the seed within, provided with its own proper integuments. The name has been restricted to the seed- like fruits of simple pistils, as those of the Buttercup (Fig. 566, 567), Anemone, Clematis, and Geum (where the persist- FIG. 564. Magnified vertical section of half of a blackberry. 565. Section of one of the grains, or drupelets, more magnified. FIG. 566. Achenium of a common Buttercup, enlarged. 567. Vertical section of the same, showing the seed within. FIG. 568. Achenium of Mayweed (no pappus). 569. That of Cichory (its pappus a shal- low cup). 570. Of Sunflower (pappus of two deciduous scales). 571. Of Sneezeweed (Hele- nium). with its pappus of five scales. 572. Of Sow-Thistle, with its pappus of delicate downy hairs. 578. Of the Dandelion, its pappus raised on a long beak. 27 314 THE FRUIT. ent style usually remains on the fruit as a long tail), and the minute grains of the strawberry (Fig. 559). But it may be extended, as is now generally done, to all such one-celled seed-like fruits result- ing from a compound ovary, and even when invested with an adnate calyx-tube. Of this kind is the fruit of all Composite (Fig. 568 - 573). Here the tube of the calyx is incorporated with the surface of the ovary, and its limb or border, obsolete in some cases (Fig. 568), in others appears as a crown (Fig. 569), cup, a set of teeth or of scales (Fig. 570, 571), or as a tuft of bristles or hairs (Fig. 572, 573), &e., called the pappus. In the Lettuce and Dandelion (Fig. 573), the achenium is rostrate, i.e. its summit is extended into a slender beak. 603. A Utricle is the same as an achenium, only with a thin and bladdery loose pericarp, like that of Goosefoot and Amaranth (Fig. 574, 575). The thin coat commonly bursts irregularly, discharging the seed. In the true Amaranths it opens by a circular line, and the upper part falls as a lid, converting the fruit into a small pyxis (619). 604. A Caryopsis or Grain differs from the last in hav- ing the seed completely filling the cell, and its coat firmly consolidated throughout with the very thin peri- carp, as in wheat, Indian corn, and other cereal grains (Fig. 622-624). Of all fruits this is the kind most likely to be mistaken for a seed. 605. A Nut is a hard, one-celled and one-seeded, indehiscent fruit, like an achenium, but larger, and usually produced 575 from an ovary of two or more cells with one or more ovules in each, all but a single ovule and cell having disappeared during its growth (586); as in the Tazel, Beech, Oak (Fig. 576, 1166), Chestnut, Cocoa-nut, &c. The nut is often enclosed or sur- rounded by a kind of involucre, termed a Cupule ; as the cup at the base of the acorn, the bur of the chestnut, and the leaf-like covering of the hazel-nut. 606. A Samara or Key-fruit is a name applied to a nut, or achenium, having a winged apex or margin; as in the Birch, Elm (Fig. 578), FIG. 574. Utricle of Chenopodium album, or common Goosefoot. 575. Utricle, or pyxis, of an Amaranth FIG. 676. Acorn (nut) of White Oak, with its cup or cupule. ITS KINDS. 315 ‘and Ash (Fig. 577). The fruit of the Maple consists of two such fruits belonging to one flower, united by their bases (Fig. 787). 607. Dehiscent Fruits, or Pods, are distinguishable into those consisting of a simple pistil, and those resulting from a compound pistil. 608. Of those originating from simple pistils, the principal kinds are the Follicle and the Legume. These may be taken as the type, of simple fruits. 609. A Follicle is a pod formed of a simple pistil, and dehiscent by the ventral or inner suture alone; as in the Milkweed, Larkspur, Columbine, Peony, and Marsh-Marigold (Fig. 579). When it opens widely, the pistil may be said to revert to its natural state of a leaf, and it often looks much like one, as in Fig. 492. : 610. A Legume isa pod formed by the ripen- 579 ing of a simple pistil which dehisces by both sutures, and so divides into two valves or pieces, as in the Bean and Pea (Fig. 580). This being the ordinary fruit of the Pulse family, accordingly named Leguminose (or Leguminous plants), the name has been extended to it in descriptive: botany, in all cases, whatever thy form, and whether dehiscent or not. The legume will be found to exhibit no small diversity in this large fam- ily (799). Among its forms is one termed 611. A Loment. This is a legume divided transversely into two or more one-seeded joints, which usually fall apart at maturity (Fig. 581). Commonly these joints remain closed, as in Desmodium; sometimes they split into two valves, as in Mimosa. 612. A Capsule is the pod, or dehiscent fruit, of any compound pistil. When regularly dehis- cent, as already stated (591), the pod splits lengthwise into pieces or valves. 613. A capsule, necessarily consisting of two or more carpels or _ FIG. 577. Samara of White Ash. 578. Samara of American Elm. FIG. 579. Follicle of Caltha palustris, the Marsh-Marigold. FIG. 580. Legume of a Sweet Pea, already dehiscent, 681. Loment of a Tick-Trefoil or 4 Desmodium. 316 THE FRUIT. simple pistils united into one body, will normally dehisce in one of two ways. Namely, cither the carpels will separate at the line of junction, thus resolving the pod into its constituent elements; or else, these parts remaining united, each cell will open on the back by a splitting of the dorsal suture. The former constitutes G14. Septicidal Dehiscence (Fig. 582, 584), so named because the capsule splits through the septa or partitions (dissepi- ments), each one separating into its two constituent layers, one belonging to each carpel. This occurs in Azalea and its allies, in St. Johnswort, &c. The car- pels, thus becoming separate, in these cases open down their inner suture, like a follicle, and discharge the seeds. 583 When the cells are only one-seeded, after separating septicidally, they often remain closed and fall away separately, : \ asin Mallow, Vervain (Fig. /~ 985), &c. Such closed or a a nearly closed cells or car- pels of a compound pistil eat = are termed cocct. ‘ 615. Loculicidal Dehis- sat cence is that in which the splitting opens into the loculaments (in Latin, local’) or cells; that is, each carpel dehisces by its dorsal suture (Fig. 588, 585), as in Iris, the Lily, Hibiscus, Evening Prim- rose, &c. The dissepiments here are necessarily borne on the mid- dle of the valves. 616. In the Violet, &c. we have the loeulicidal, and in several kinds of St. Johnswort the septicidal, plan of dehiscence in one- celled capsules; the placenta (answering to the partitions) being borne in the former upon the middle of the valves; while in the latter each placenta is split in two, and one half borne on each mar- gin of a valve. FIG. 582. Dehiscent capsule of Elodea, enlarged, showing septicidal dehiscence. FIG. 583. Dehiscent capsule of Iris, showing loculicidal dehiscence ; the lower part cut across, showing the dissepiments borne on the middle of the valves. FIG. 584. Diagram (in cross-section) of septicidal, and, 585, of loculicidal, dehiscence. ITS KINDS. 317 617. Septifragal Dehiscence is a modification of either the loculicidal or the septicidal, in which the valves fall away, leaving the dissepi- ments behind attached to the axis. Fig. 586 is a diagram representing this in a case of loculicidal opening. Fig. 587; from the common Morn- ’ ing-Glory, is this modifica- 586 587 tion of the septicidal mode. 618. Instead of splitting into separate pieces, the sutures of the pericarp sometimes open for a short distance at their apex only, as in Cerastium and some other Chickweeds, in Tobacco (Fig. 1050), and in the Primrose (Fig. 948) ; or by mere pores, as in the Poppy. The pod of the Snap- dragon opens by the bursting of a hole towards the top of each cell, not corresponding, perhaps, with any suture. Another anomalous mode of dehiscence, namely, the evreumerssile, characterizes 619. The Pyxis or Pyxidium, a pod which opens by a circular hor- izontal line cutting off the upper part as a lid. The fruits of the Plantain, Henbane, Amaranth (Fig. 575, which is otherwise a utricle), Pimpernel, and Purslane (Fig. 588)-are of this kind. 620. A Silique is a slender two-valved capsule, with two parietal placente, from which the valves separate in dehiscence; as in plants of the Cruciferous or Mustard family (Fig. 589), to the fruit of which the term prop- erly belongs. Usually a false partition is stretched across between the two placentae, rendering the pod two-celled in an anomalous manner. 621. A Silicle or Pouch is merely a short silique, its length not more than twice its breadth ; as that of Shep- herd’s-Purse, Candytuft, &e. J % 622. Ageregate Fruits are those in which a cluster of Y carpels, all belonging to one flower, are crowded on the 589 receptacle into one mass, as in the raspberry and blackberry taken as a whole (Fig. 564), where the constituent fruits, or ripened carpels, FIG. 586. Septifragal modification of loculicidal, and, 587, of septicidal, dehiscence. FIG. 588. Pyxis or pod of Purslane, the top separating as a lid. FIG. 689. Silique of Cardamine, in dehiscence. 27 *. 318 THE FRUIT. are little drupes ; also the cone-like fleshy fruit of Magnolia, where the component carpels are a sort of drupaceous follicles, at length opening on the back and summit; and the dry cone of the Tulip-tree, where each carpel forms a sort of samara. None of these aggregate fruits have special names in ordinary use. In descriptive botany it is sufficient to state the kind of fruit the carpels themselves form, and their mode or degree of aggregation. 623. Accessory or Anthocarpous Fruits are those of which the most conspicuous portion, although often appearing like a pericarp, neither belongs to the pistil nor is organically united with it. The apparent berry of Gaultheria, in which a succulent free calyx invests a dry pod and appears to form the real fruit (Fig. 912-914) has already been adverted to (583); and the calyx of Shepherdia is similar, forming what appears to be the sarcocarp of a drupe, although it is really free from the achenium it encloses. So, also, the apparent achenium or nut of Mirabilis, or Four-o’clock, is the thickened and indurated base of the tube of a free calyx, which contracts at the apex and encloses the true pericarp as a utricle or thin achenium, but does not cohere with it. The rose-hip, a hollow calyx-tube lined with a hollow receptacle (Tig. 429), and the strawberry (Fig. 428, 558, 559), consisting of a conical enlarged reccptacle bearing many minute achenia, may also be regarded as forms of anthocar- pous fruit. 624. Multiple or Collective Fruits are those which result from the geregation of several flowers into one mass. The simplest of these are those of the Partridge-Berry (Mitchella) and of some species of Honeysuckle (Fig. 859), consisting of the ovaries of two blossoms united into one double berry. The more usual sorts are such as the pine-apple, mulberry, and the fig. These are, in fact, dense forms of inflorescence, with the fruits or floral envelopes matted together or coherent with each other; and all or some of the parts become succulent. The grains of the mulberry (Fig. 593, 594) are not the ovaries of a single flower, like those of the blackberry which it super- ficially resembles (Fig. 564), but belong to as many separate flow- ers; and the pulp of these pertains to the floral envelopes instead of the pericarp. So that the mulberry is an anthocarpous (623) as well as a multiple fruit. The pine-apple is very similar; only the ovaries or pericarps never ripen any seeds, but all are blended, with the floral envelopes, the bracts, and the axis of the stem they thickly cover, into one fleshy and juicy mass. The fig (Fig. 590-592) ITS KINDS. 319 ‘ differs from the pine-apple in having this succulent axis or receptacle on the outside. It may be compared with such an anthocarpous fruit as a rose-hip (Fig. 429). It results from a multitude of flow- ers concealed in a hollow flower-stalk, if it may be so called, which becomes pulpy and edible when ripe; and thus the frut seems to grow directly from the axil of a leaf, without being preceded by a blossom. The minute flowers concealed within, or some of them, ripen their ova- ries into very small achenia, which are commonly taken for seeds. The principal form of multiple fruit which has received a substantive name is 625. The Strobile or Cone, a scaly multiple fruit, resulting from the FIG. 590. A young fig. 591. Vertical section of the same, enlarged. 592. A small slice of the same, more magnified, showing the flowers on the inside. FIG 5938. A young mulberry. 694. One of the grains, magnified, showing it to be a pis- tillate flower, with a succulent calyx embracing the ovary 695. The same, less magnified, the succulent calyx cut away. FIG. 596. Strobile or Cone of a Pitch Pine, Pinus rigida. 597. Inside view of one of the scales, showing one of the seeds, and the place from which the other, 598, has been detached. 320 THE SEED. ripening of some sort of catkin. The name is applied to the fruit of the Hop, where the large and thin scales are bracts; but it more especially belongs to the Pine or Fir cone, the peculiar fruit of Co- niferee (Fig. 596), the scales of which are open carpels (560), bear- ing two or more naked seeds upon their upper or inner face (Fig. 597). A more or less fleshy and closed cone, such as that of Taxo- dium, and especially that of Juniper (Savin, Red Cedar, &c.), which at maturity imitates a berry, has been termed a GALBALUS. CHAPTER XI. OF THE SEED. Secr. I. Irs Srrucrure anp Parts. 626. The Seed, like the ovule (561), of which it is the fertilized and matured state, consists of a Nucreus, or kernel, usually en- closed within two INTEGUMENTS. 627. Its Integuments, &. The outer, or « proper seed-coat, corresponding to the ex- terior coat of the ovule, is variously termed the Erisrerm, SPERMODERM, or more com- (©) monly the Testa (Fig. 599, 6). It varies greatly in texture, from membranaceous or papery to crustaceous or bony (as in the Papaw, Nutmeg, &c.), and also in form, being sometimes closely applied (conformed) to the nucleus, and in other cases loose and cellular (as in Pyrola, Fig. 927, and Sullivantia, Fig. 843), or ex- panded into wings (as in the Catalpa and Trumpet-Creeper, Fig. 601), which render the seeds buoyant, and facilitate their dispersion by the wind; whence winged seeds are only met with in dehiscent fruits. The wing of the seed of Pines (Fig. 598) is a part of the surface of the scale or carpel to which it is attached, and which separates with it. For the same purpose, the testa is sometimes 599 600 FIG. 599. Vertical magnified section of the (anatropous) seed of the American Linden: a, the hilum ; , the testa; ¢, the tegmen; d, the albumen; e, the embryo, 600. Vertical section of the (orthotropous) seed of Helianthemum Canadense: a, the funiculus. ITS STRUCTURE AND PARTS. 321 provided with a tuft of hairs at one end, termed a Coma; as in Epilobium and Milkweed (Fig. 602). In the Cotton-plant, the whole surface of the seed is covered with long wool. It should likewise be noticed, that the integument of numerous small seeds is furnished with a coating of small hairs containing spiral threads (one form of which is represented in Fig. 44), and usually appressed and con- fined to the surface by a film of mucilage. When the seed is moistened, the mucilage softens, and these hairs spread in every direction. They are often ruptured, and the extremely attenuated elastic threads they contain uncoil, and are protruded in the greatest abundance and to a very considerable length. This minute mechanism subserves an obvious purpose in fixing these small seeds to the moist soil upon which they lodge, when dis- persed by the wind. Under the microscope, these threads may be observed on the seeds of most Polemoniaceous plants, and on the achenia of Labiate and Composite plants, as, for example, in many species of Senecio, or Groundsel. In Peony the testa becomes fleshy or baccate ; in Magnolia it imitates a drupe. 628. The inner integument of the seed, called the TeGMen or Enpopevura, although frequently very obvious (as in Fig. 599, ec), is often indistinguishable from its being coherent with the testa, and is sometimes altogether wanting. 629. The stalk of the seed, as of the ovule, is called the Fu- nicuLus (Fig. 600, a). The scar left on the face of the seed, by its separation from the funiculus at maturity, is termed the Hitum. The chalaza and rhaphe, when present, are commonly obvious in the mature seed, as well as in the ovule (564-568), and the name and relations of these several parts in the seed are the same as in the ovule. Also the terms orthotropous, anatropous, campylotropous, &e., originally applied to the ovules, are extended to the seeds which result from them ; so that we may say, Seeds anatropous, as well as Ovules anatropous, &c. 630. Aril or Arillus. Some seeds are furnished with a covering, (usually incomplete and of a fleshy texture,) wholly exterior to their proper integuments, arising from an expansion of the apex of the FIG. 601. The winged seed of Trumpet-Creeper. FIG. 602. Seed of Milkweed (Asclepias Cornuti), with its coma or tuft. 322 THE SEED. seed-stalk, or funiculus, or of the placenta itself when there is no manifest seed-stalk. This is called the Ari. It forms the pulpy envelope of the seed ‘of Podophyllum, Euonymus, and Ce- lastrus, or it appears as a mere lateral scale in Turnera, or as a tough and lacerated body, known by the name of mace, in the Nutmeg. In the White Water-Lily it is a thin and delicate cellular bag, open at the end (Fig. 603). The Aril does not appear in the ovule, but is developed subse- quent to fertilization, during the growth of the seed. Of the same or similar nature is the CAruNCLE found at the hilum in Polygala, forming a loose lateral appendage. Strictly speaking, it is to be distinguished from the StropHioLe (like that of Euphor- bia), which is a cellular growth from the micropyle; but the two are not well discriminated. An analogous cellular growth takes place on the rhaphe of the Bloodroot, of the Prickly Poppy, and of Dicen- tra, forming a conspicuous crest on the whole side of the seed. 631. The Nucleus, or Kernel of the seed, consists of the ALBUMEN, when this substance is present, and the Eusryo. 632. The Albumen, which has also been termed the Perisperm or the Endosperm, has already been described (125) as the floury part of those seeds in which an amount of nourishment for the germi- nating plantlet is stored up outside of the embryo. This was called by Gertner the albumen of the seed, from some fancied anal- ogy with the white of an egg as to situation or function ;— an un- fortunate term, on account of its liability to be confounded with the quaternary chemical substance of the same name (357), one of the forms of proteine. Being in general use, the term cannot now well be discarded. 633. The Albumen of the seed consists of whatever portion of the tissue of the ovule persists, and becomes loaded with nutritive mat- ter accumulated in its cells, sometimes in the form of starch- grains principally, as in wheat and the other cereal grains; some- times as a continuous, often dense, incrusting deposit, as in the cocoa- nut, the date, the coffee-grain, &c. When it consists chiefly of starch-grains, and may readily be broken down into a powder, it is said to be farinaceous, or mealy, as in the cereal grains generally, in buckwheat, &e. When a fixed oil is largely mixed with this, it becomes ozly, as in the seed of the Poppy, &c. ; when more compact, but still capable of being readily cut with a knife, it is fleshy, as in FIG. 603. A seed of the White Water-Lily, with its sac-like arillus, magnified. THE ALBUMEN AND EMBRYO. 323 the Barberry, &e.; when it chiefly consists of mucilage or vegetable jelly, as in the Morning-Glory and the Mallow, it is said to be muci- laginous ; when it hardens more, and becomes dense and tough, so as to offer much resistance to the knife, as in the Coffee, the Blue Cohosh, &c., it is corneous, that is, of the texture of horn. Between these all gradations occur. Commonly the albumen is a uniform deposit. But in the nutmeg, as also in the seeds of the Papaw (Fig. 658), and of all plants of the Custard-Apple Family, it presents a wrinkled or variegated appearance, owing to numerous transverse divisions, which are probably caused by inflections of the innermost integument of the seed: in these cases the albumen is said to be rum7- nated. ‘The albumen may originate from new tissue formed either within the embryo-sac (579), which is probably the more common case ; or in the nucleus of the ovule exterior to the embryo-sac, which is certainly the case in the Water-Lily and its allies, and in Saururus; for here the thickened embryo-sac persists within or at one extremity of the copious albumen; or both kinds may coexist. When this is the case, the outer albumen may be distinguished as the perisperm, and the inner as the endosperm. 634, Seeds provided with albumen (as in Fig. 599, 600, 605, 606, 609, 610-616, 622, &c.) are said to be albuminous ; those destitute of it (as in Fig. 607, 629, 110, 120, &c.) are exalbuminous. The comparative amount of the albumen, and its relation to the embryo in various seeds, may be seen on inspection of many of the subjoined figures. 609 635. The Embryo, or Germ, being an initial plantlet or individual, is of course the most important part of the seed : to its production, protec- FIG. 604. Seed of a Violet (anatropous), enlarged: a, hilum or scar; b, rhaphe; c, chalaza. FIG. 605. Vertical section of the same, showing the straight embryo in the axis of themealy albumen. FIG. 606. Vertical section of the (orthotropous) seed of Buckwheat, showing the embryo folded round in the mealy albumen. FIG. 607. Vertical section of the (anatropous) seed of Elodea Virginica, the embryo com- pletely filling the coats. FIG. 608. Seed of Delphinium tricorne (anatropous), enlarged; a, the hilum; 6, the rhaphe; ¢, the chalaza. 609. Vertical section of the same: c, the chalaza; d, the testa; e, the tegmen ; /, the albumen ; g, the minute embryo near the hilum, a. 3824 THE SEED. tion, and support all the other parts of the fruit and flower are sub- servient. It becomes a plant by the mere development of its parts: it therefore possesses, in a rudimentary or undeveloped state, all the essential organs of vegetation, namely, a root, stem, and leaves. Its general structure and development have already been explained in considerable detail (118 — 130). 636. In albuminous seeds it is naturally the smaller and its parts the less developed in proportion to the amount of albumen, and the several organs are developed or even formed in germina- 614 tion. In exalbumi- nous seeds, where the embryo con- stitutes the whole kernel, its several parts are ordina- rily conspicuous, although they are often more or less disguised by thickening; as the cotyledons in the Almond (Fig. 108) and Cherry (Fig. 111), and especially in the Pea (Fig. 118), the Acorn (Fig. 120), the Horsechestnut (Fig. 630), and the like. 637. The parts of the embryo, as already illus- trated (120) are the Radicle, the Cotyledons, and the Plumule. The radicle is the axis, or rudimen- tary stem,— the first internode of the axis (121, 157), from the lower extremity of which the root is produced, while the other bears the cotyledons, i.e. the leaves of the first node; and the plumule is the bud which crowns the summit of the radicle. 638. Owing to the mode of its formation (580), the radicle of the 6lL 613 FIG. 610. Vertical section of the seed of a Peony, showing a small embryo near the base of the copious albumen. 611. The embryo, detached, and. more magnified. FIG. 612. Section of a seed of Barberry, with a straight embryo in the axis of the albu- men. 613. Its embryo, detached. a FIG. 614. Section of a Potato-seed, showing the embryo coiled in the albumen. 615. Its embryo, detached. FIG 616. Section of the seed of Mirabilis or Four-o’clock, showing the embryo coiled round the outside of the albumen. 617. Its embryo, detached, and partly spread out. FIG 618. Embryo of the Pumpkin, with its short radicle and large and flat cotyledons, seen flatwise. 619. A vertical section of the same, viewed edgewise. THE EMBRYO. 825 embryo is always near to and points towards the micropyle of the seed, viz. to what was the orifice of the ovule; and if the embryo be straight (as in Fig. 605), or merely partakes of the curvature of the seed, the cotyledons point to the opposite extremity of the seed, that is, to the chalaza. The position of the radicle as respects the hilum varies with the different kind of seed. In the orthotropous form, as in Helianthemum (Fig. 600) and Buckwheat (Fig. 606), the radicle necessarily points directly away from the hilum. In the anatropous form, as in the seed of the Lin- den (Fig. 599) and Violet (Fig. 604, 605), the extremity of the radicle is brought to the immediate vicinity of the hilum; and so it is, although in a different way in the campylotropous seed (Fig. 620, 621); while in the amphitro- pous, the radicle points away from the hilum laterally, at a right angle to the funiculus. As the nature of the ovule and seed may usually be ascertained by external inspection, so therefore the situa- tion of the embryo within, and of its parts, may often be inferred without dissection. But the dissection of seeds is not generally a difficult operation. 639. The position of the embryo as respects the albumen, when that is present, is various. Although more commonly. in the axis, it is often excentric, or even external to the albumen, as in all Grasses and cereal Grains (Fig. 622-624), in Polygonum (Fig. 1111), &c. When external or nearly so, and curved circularly around the albu- men, as in Goosefoot, Chickweed (Fig. 621), and Mirabilis (Fig. 616), it is said to be pertpheric. When bent or folded in such a FIG. 620. Campylotropous seed of the common Chickweed (Stellaria media), magnified. FIG. 621. Section of the same, showing the embryo coiled around the outside of albumen. FIG. 622. Vertical section of a grain of Indian Corn, passing through the embryo: c, the cotyledon ; 7, the plumule ; r, the radicle. (A highly magnified portion of the albumen, which makes up the principal bulk of the grain, is shown in Fig. 70, p. 54.) 628. Similar section of agrain of Rice. 624. Vertical section of an Oat-grain: a, the albumen; c, the cotyledon; p, the plumule ; and 7, the radicle of the embryo. 28 326 THE SEED. way that the radicle lies along the edges of the cotyledons, the latter are said to be accumbent (Fig. 700); or when the radicle rests against the back of one of them, or in proximity to it (Fig. 705), they are txcumbent. 640. The direction of the embryo with respect to the pericarp is also particularly noticed by systematic writers; who employ the terms ascending, or radicle superior, when the latter points to the apex of the fruit; descending, or radicle inferior, when it points to its base ; centripetal, when tle radicle is turned towards the axis of the fruit; centrifugal, when turned towards the sides ; and vague, when it bears no evident or uniform relation of the kind to the pericarp. 641. As to the number of its cotyledons, or the degree of com- plexity or simplicity of the embryo, the principal types have already been considered (128). The plan of the embryo in Exogenous plants is to have a pair of opposite cotyledons ; that is, the embryo is dicotyledonous, and such plants are denominated DicotyLEepDo- Nous PLants. 642. A modification of this plan occurs in Pines and most other Conifers, in which the cotyledons are increased to three, four, six, or even to fifteen, in a whorl (Fig. 1383, 134); and this embryo of highest complexity is called polycotyledonous. 'The embryos of some Leguminous or Cruciferous plants are occasionally found, with three cotyledons, as an accidental deviation. 643. But in all Endogenous plants only one cotyledon appears, i. e. only one seed-leaf on the primary node ; if two or more rudi- mentary leaves are present, they are alternate, and all but the first belong to the plumule. Here the em- bryo is monocotyledonous, and hence Endogens are also termed Monocorty- LEDONOUS PrLants. The monocoty- ledonous embryo does not usually pre- sent a manifest distinction into radicle, ’ cotyledons, and plumule, as the dicoty- ledonous ; but often appears like a ho- mogeneous and undivided cylindrical or club-shaped body, as in Iris 627 FIG. 625. Seed of Triglochin palustre; the rhaphe, leading to the strong chalaza at the summit, turned towards the eye. 626. The embryo detached from the seed-coats, showing the longitudinal chink at the base of the cotyledon; the short part below is the radicle: 627. Same, with the chink turned laterally, and half the cotyledon cut away, bringing to view the plumule concealed within. 628 A cross-section through the plumule, more magnified. THE EMBRYO. 827 (Fig. 131) and Triglochin (Fig. 626). In the latter, however, close inspection reveals a vertical slit or chink just above the radicular extremity, through which the plumule is protruded in germination. If the embryo be divided parallel with this slit, the plumule is brought into view; as in Fig. 627. If a horizontal section be made at this point (as in Fig, 628), the cotyledon is found to be wrapped around the enclosed plumule, sheathing it, much as the bud and the younger parts of the stem are sheathed by the bases of the leaves in most monocotyledonous plants. The plumule is more manifest in Grasses, especially in the cereal grains, and more complex, ex- hibiting the rudiments of several concentric leaves, or of a strong bud, previous to germination (Fig. 622-624, and 126-128). In many cases, however, no distinction of parts is apparent until ger- mination commences ; as in the Onion, Iris (Fig. 131), &e. 644. In several Dicotyledonous plants one cotyledon is smaller than the other, viz. the inner one, when the embryo is coiled or folded. And in all the species of Abronia this cotyledon is wanting, so that the embryo becomes tech- nically monocotyledonous. In the Dodder, a genus of leafless parasitic plants of the Convolvu- lus family, the embryo also is entirely destitute of cotyledons (Fig. 148). Here these organs aye suppressed in an embryo of considerable size; but in most such parasites, the embryo is very minute, as well as reduced to the greatest degree of simplicity, and seems to remain until germination in a very rudimentary state. 645. Sometimes the two cotyle- dons of a dicotyledonous embryo are consolidated, or more or less coherent by their contiguous faces into one mass, when they are said to be conferruminate, as in the Horsechestnut, Buckeye (Fig. 629, 630), and the Chestnut. In these, as in other embryos with very thick cotyledons, the latter are 629 63) FIG. 629. Section of the seed ofa Buckeye. 630. A Buckeye in germination. 328 THE SEED. necessarily hypogg@ous in germination (124, 126), that is, they re- main underground, enclosed within the coats of the seed, yielding their abundant store of nourishment to the radicle and the plumule; and the first leaves that appear are those of the plumule. Sect. II]. GERMINATION. 646. Germination is the initial act of growth, by which the embryo in a seed develops into a plantlet. The steps of the early growth have already been sufficiently explained in an early part of this vol- ume (119-182). 647. The seeds of some plants (such as the Red Maple) germi- nate shortly after falling to the ground; those of most other plants not until the next year, or even later. How long seeds may retain the power of germinating is uncertain, and is extremely variable in different species and families. ‘Those of many plants under ordinary circumstances can rarely be made to grow after two or three years; some will germinate pretty well after several years keeping; and the seeds of certain Leguminous plants have been known to germi- nate when sixty years old. But the current accounts of wheat, &e. being raised from grain taken from ancient mummies, circumstan- tially authenticated as some of them appear to be, must be received with the greatest. misgiving, if not with entire incredulity. One of the most probable caves of germination of ancient seeds on record is that given by Dr. Lindley, of some Raspberries, “ raised in the gar- den of the Horticultural Society from seeds taken from the stomach of a man, whose skeleton was found thirty feet below the surface of the earth, at the bottom of a barrow which was opened near Dorches- ter. He had been buried with some coins of the Emperor Hadrian ; and itt ts therefore probable that the seeds were sixteen or seventeen hundred years old.” Most seeds, when buried deep in the soil, where they are subject to a uniform and moderate temperature, and removed from the influence ’of the air and light, may be in a favorable state for the preservation of vitality, and would be likely to germi- nate when brought to the surface after a considerable interval. But the possibility of mistake or of collusion must be more thoroughly eliminated before a case of such extraordinary tenacity of life, under conditions in some respects very unfavorable, can be considered as well established. GERMINATION. 3829 648. The conditions requisite to germination are exposure to moisture and to a certain amount of heat, varying from 50° to 80° (Fahrenheit) for the plants of temperate climates, to which must be added a free communication with the air. Direct light, so essential to subsequent vegetation, is unnecessary, and generally unfavorable, to germination. The degree of heat required to excite the latent vitality of the embryo is nearly uniform in the same species, but widely different in different plants; since the common Chickweed will germinate at a temperature not far above the freezing-point of water, while the seeds of many tropical plants require a heat of 90° to 110° (Fahrenheit) to call them into action, and are often exposed toa considerably higher temperature. Seeds are in the most favorable condition for germination in spring or summer, when loosely covered with soil, which excludes the light while it freely admits the air, moistened by showers, and warmed by the rays of the sun. The water which is slowly absorbed softens all parts of the seed; the embryo swells, and bursts its envelopes, or the elon- gating radicle is protruded from them, and all the parts grow or unfold in the manner already described, each organ in its proper medium, the root being developed in the soil, and the stem and leaves in the air. 649. The nourishment which the embryo requires during germi- nation is furnished by the starch, &c. of the albumen (632), when this substance is present in the seed; or by starchy or other nutri- tive matter accumulated in its own tissue (636, 123). But as starch is insoluble in cold water, certain chemical changes are necessary to bring it into a fluid state, so that it may nourish the embryo. These — changes are incited by the proteine or neutral azotized products (854), which are largely accumulated in the seed, either in the ' albumen or in the embryo itself, and which take the initiative in all; the transformations of vegetable matter (27). In the germinating seed, just as in growth from a bulb or tuber, the changes essentially consist in the transformation of the starch, first into dextrine, or gum, and thence into sugar, a part of which is destroyed by resolu- tion, first into acetic acid, and finally into carbonic acid and water, with the abstraction of oxygen from the air, and the evolution of heat (349, 8370 — 373), while the remainder is rendered directly sub- servient to the growth of the plantlet. The reason why light, so essential to subsequent growth, impedes or prevents incipient ger- mination, becomes evident when we remember that it incites the 28 * 3830 REPRODUCTION IN decomposition of carbonic acid, and the fixation of carbon by the plant (344-3850); while germination is necessarily attended by an opposite transformation, namely, the destruction of a portion of or- ganized matter, with the evolution of carbonic acid.* In germina- tion, as in any other act in which matter is transformed or trans- ferred, there is a certain expenditure of force and loss of organized material. The plantlet is obliged to decompose and destroy a part of the starch or other material provided for its initial growth, in order that it may transform the rest into dextrine and sugar, and this again into cellulose or the material of the new cells formed in its growth. 650. The study of the seed, and of the development of the em- bryo it contains into a plantlet, completes the cycle of vegetable life in the higher grade of Phenogamous plants, and brings us back to our starting-point (118, 119). CHAPTER XII. OF REPRODUCTION IN CRYPTOGAMOUS OR FLOWERLESS PLANTS. 651. Tue lower grade of Cryptocamots or FLOWERLEss Prants (Chap. II. Sect. I.) would now require, to be considered, both as to the vegetation and their reproduction. But the plan of structure in each principal Cryptogamous family is so peculiar, and the organs of fructification especially so diverse, that their morphology cannot be presented under one common type, as in Phe- nogamous vegetation. Each great family or group would have to be separately treated, and with much fulness of illustration, to make * Sceds may casually germinate while attached to the parent plant, especially such as are surrounded with pulp, like those of the Cucumber and Melon. The process is liable to commence in wheat and other grain, when protracted warm and rainy weather occurs at the period of ripening ; and the albumen becomes glutinous and sweet, from the partial transformation of the starch into dextrine and sugar. In the Mangrove, which forms dense thickets along tropical coasts, germination habitually commences in the pericarp while the fruit remains on the tree; and the radicle, piercing the integuments which enclose it, clongates in the air; such a plant being, as it were, viviparous. CRYPTOGAMOUS OR FLOWERLESS PLANTS. 331 the subject intelligible to the unpractised student. This can hardly be done in so elementary a work as the present, but requires a sepa- rate treatise. The student who has intelligently studied the present volume up to the present point, is prepared for the more difficult study of the structure of Cryptogamous plants, in the only general work of the kind that has yet appeared in the English language, viz. Berke- ley’s Introduction to Cryptogamic Botany. An enumeration of the Cryptogamous orders, with a brief notice of their structure and sub- ordinate divisions, may be found in the systematic part of the pres- ent work. A slight sketch of their grades of development as to vegetation has already been given (97-113). We here attempt to present merely a very brief and general account of their plan of reproduction, divested as far as possible of technical terms. 652. Taken collectively, we distinguish this lower series of the vegetable kingdom by negative characters only ; saying that these plants do not bear true flowers (consisting essentially of stamens and pistils), and accordingly do not produce seeds, or bodies consisting of a distinguishable embryo plantlet, developed in an ovule through fertilization by pollen. Their spores (97), or the bodies produced in their fructification by which they are propagated, and which there- fore answer to seeds, are single cells, at least in most cases. These, as they germinate in the soil, or whatever medium they live in, un- dergo a development at the time of their germination which has been compared with that of the embryonal vesicle (679) during its devel- opment into the embryo in the ovule; and by growth directly give rise to the plant. 653. It was once thought probable, that these spores were pro- duced, and were capable of developing into the plant without being fertilized by other cells answering to pollen; or at least that this was the case in all the lower orders, such as Alge and Fungi, and in some of the highest, such as Ferns. But the sagacious Linnzus, by nam- ing them Cryptogamous plants (i. e. plants with concealed organs ‘of reproduction) seems to have recorded his belief that they were really bisexual, or furnished with two sorts of organs, the fertilizing and | fertilized. A series of important discoveries, for the most part of! recent date, have proved this to be so,— have made known a true fecundation in numerous species of every Cryptogamous order, and in their lowest as well as their highest forms, thus leaving no doubt of its universality. The apparatus and the processes of reproduction, however, are wonderfully varied in the diferent groups of Cryp-! 3832 REPRODUCTION IN togamous plants. A few examples may be adduced, illustrative of the principal modes, beginning with the simplest plants. 654. Reproduction in Plants of a Single Cell (100). All such simple one-celled plants as Protococcus and the like (Fig. 79 — 83, 18 - 22), Desmidiaceew and Diatomacex, are freely propagated by cell-multi- plication (83 — 36), — the division of their protoplasm or whole living mass into bodies which directly become new cells like the parent, — or by original cell-formation in their interior (29). This is non- sexual reproduction, and essentially answers to the well-known prop- agation of Phanogamous plants by buds, bulbs, offsets, &e. It is probable that this may not go on indefinitely in any plant. At any rate, not only do all the higher plants propagate in a different way, viz. by flowers, producing seeds, but probably all plants of the lower grade also have a sexual reproduction in some form or other. It is certainly the case in many one-celled plants, and in others almost equally simple in structure. As in Phanogamous plants, sexual reproduction essentially depends upon the mingling of the materials of two distinct cells (as the pollen-cell and the embryonal vesicle, 579); and these cells in the lowest forms of vegetation represent individual plants. The simplest mode of such reproduction in the lowest plants, and that longest known, is what has been termed 655. Conjugation. This is the mode in which two vast tribes of microscopic one-celled aquatic plants, the Desmidiaces and Diato- macer, are reproduced. They mudti- ply rapidly, and apparently without limit, by successive division into two equal parts, which separate, each be- coming like the original. But at length y two of these individuals, being en- dowed with the power of movement, come into contact; the firm or often silicious cell-wall ruptures or gives way in a definite manner at the place of junction, and the whole contents of the two conjugating cells or individu- als are commingled into one mass of protoplasm, &c.; this soon has a coat of cellulose formed around it, 631 632 633 Gul FIG. 631. Magnified individual of Closterium acutum, after Ralfs. 632. Two individuals more magnified, in conjugation ; their cells opening one into the other, and the contents min- gled ; in 633, condensing ; in 634, collected and formed into a spore. CRYPTOGAMOUS OR FLOWERLESS PLANTS. 333 and is now a spore, which when it grows begins a new series of in- dividuals developed by successive division. 656. In Alge consisting of a Single Row of Cells one tribe presents the same mode of reproduction, and the various species of Zygnema or Spirogyra, found in almost every pool of fresh water at different times in spring and summer, afford the readiest illustrations of conjugation, which low powers of the microscope suffice to exhibit. These green threads when magnified are seen to consist of single rows of cylindrical cells joined end to end. The cells being all alike and equally capable of conjugation, each is as it were an individual. At a certain season, a protuberance appears on the corresponding parts of certain cells of two adjacent threads; the budding growth continues until the two come into contact; the intervening walls are then absorbed, opening a free communication between the cavities of the two cells; mean- while the green matter and protoplasm, before arranged in some definite shape in each species (more commonly in one or more spiral bands), break up into a granular mass floating in the water of the cell; this all passes over from one cell to the other, — sometimes to the one plant and sometimes to the other in adjacent cells, — and is mingled with the similar contents of the cell which receives it; and the united product is condensed into a green protoplasmic mass, which, acquiring a coat of cellulose, be- comes a new cell or spore, in due time germinating into a new plant. 657. In reproduction by conjugation, the two cells or individuals concerned are alike; one is as much the fertilizer or the fertilized as the other. But the clear distinction of sexes which all the higher Cryptogamous no less than Phanogamous plants exhibit, is also mani- fested in those of the simplest structure, viz. in plants consisting of single cells, or of rows or clusters of similar and essentially inde- pendent cells. That is, even these afford examples of FIG. 635. Magnified view of two conjugating filaments of Zygnema, showing all the stages of the process by which the cells from two filaments form each a corresponding protuberance, these come into contact, the intervening walls are absorbed, and the contents pass from one cell into the other, condense, acquire an investing membrane, and so formaspore: the stages are represented from above downwards ; a completed spore is seen at the bottom, on the right. 334 REPRODUCTION IN 658. Direct Fertilization of Spores by Spermatozoids from an Anthe- ridium; the latter answering to the anther, or essential part of the stamen, of Phenogamous plants. Cohn* has shown that even Volvox—an undoubted vegetable, consisting of microscopic one- celled plants of rounded form, grouped into a spherical colony — has a true sexual propagation, like that of the higher green Algie, some of the individuals or cells of the sphere producing antheridia or fer- tilizing cells, while others produce spores, or bodies which become such on being fertilized by the antheridia, which alone renders them capable of germination. A good general idea of bisexual reproduction in the simplest Alga may best be obtained from a brief abstract of what has lately been discovered by Pringsheim and Cohn in two or three common species of comparatively easy investigation. 659. Vaucheria is a genus of several species of green Algm, con- sisting of simple but indefinitely branching cells (Fig. 89). In frue- tification, the whole contents of the more or less enlarged extremity of some of the branches, or of a special projection from the side of the cell, separate from the general contents of the plant, con- dense into a globular green mass (Fig. 89 a), and become a spore, which at length escapes by a rupture of the walls (Fig. 90), moves freely about in the water for some hours, then fixes itself, and ger- minates, elongating directly into a thread-like and at length branch- ing plant, like the parent. Here there appears, and was generally thought to be, reproduction without fecundation. Vaucher, however, more than half a century ago, noticed one or more horn-shaped pro- jections in the vicinity of the spore-bearing portion, which he sus- pected to be the analogues of the anther. Nothing had been found to verify this view until the year 1854, when Pringsheim, of Berlin, discovered the fecundation and verified this conjecture. The horn- shaped body is an antheridiwm, or the analogue of the anther. It produces myriads of extremely minute corpuscles, of oblong shape, and furnished with a bristle or cilia at each end, by the vibration of which they move freely in the water. These are spermatozotds (so called from their obvious resemblance to the spermatozoa of ani- mals), and the analogues of pollen. At the proper time the anthe- ridium bursts at the summit, and discharges the spermatozoids ; at this time the wall of the projection which contains the spore likewise opens; numbers of the free-moving spermatozoids find their way * In Comptes Rendus, vol. 43, 1856, and Ann. Sci. Nat. ser. 4, vol. 5, p. 323. CRYPTOGAMOUS OR FLOWERLESS PLANTS. 835 into the opening and into contact with the forming spore, or even penetrate its substance ; it being an amorphous mass, coated with protoplasm only. But, as a consequence of fecundation by one or more spermatozoids, a wall of cellulose is presently formed on its surface, converting it into a proper specialized cell or spore.* 660. A&dogonium is a genus of simple Alge of the Conferva tribe, consisting of a row of cylindrical cells placed end to end, as in Fig. 639. Some of these cells, usually shorter than the rest, become tumid, and, without conjugation, have their whole green contents transformed into a spore resembling that of Zygnema (Fig. 635) and Vaucheria (Fig. 90). The fertilization of this spore has re- cently been discovered by Pringsheim.f He ascertained that other cells of the same little plant produce a great number of minute ovoid bodies, which he names Androspores: these escape by the opening of the mother cell, moving about freely by the vibration of a crown of cilia attached near the smaller end. One or more of these androspores fix themselves by the smaller end upon the surface of the cell in which a large ordinary spore is forming, or in the vicinity, and germinate there, growing longer and narrower at the point of attachment, while near the free end a cross partition forms, and some- times another, making one or two small cells; this is the true anthe- ridium ; for in it a crowd of spermatozoids are formed, also endowed with motivity by means of vibratile cilia. Now the top of the an- theridium falls off as a lid, the spermatozoids escape; the spore-cell at this time opens at the top; one of the spermatozoids enters the opening, its pointed end foremost; this becomes stationary upon or slightly penetrates the surface of the young spore, into which its contents are probably transferred, by rupture or by endosmosis, and a coat of cellulose is then, but not till then, deposited upon it, com- pleting its organization as a spore. ‘This spore, as in the preceding cases, in due time germinates, and grows directly into a plant like the parent. .But in Bolbochete, according to Pringsheim, and in Sphzroplea, as investigated by Cohn,t the spore in germination converts its contents by successive division into a large number of small, oval or oblong bodies, furnished with two long cilia on a short * Pringsheim, in the Procecdings of the Royal Academy of Sciences, Berlin, March, 1855, and Ann. Sci. Nat. ser. 4, vol. 3, p. 363. ; + Op. supra cit. May, 1856, and Ann. Sci. Nat. ser. 4, vol. 5, p. 250. + Op. supra cit. May, 1855, and Ann. Sci. Nat. 1. c. p. 186, pl. 12, 13. 336 REPRODUCTION IN beak at one end, and which from their extreme resemblance to ani- malcules and their lively movements are called Zodspores. And these zodspores germinate by elongation and the formation of trans- verse partitions into adult thread-like plants, consisting of a row of cells. The whole contents of the cells of some adult individuals of Spheroplea are formed into large green spores, as yet without a coat ; those of different individuals give rise to myriads of slender sperma- tozoids, moving by means of a pair of cilia fixed at the narrow end. These escape from the parent cell through a small perforation which now appears, enter the spore-bearing cells of the fertile plant through a similar perforation, play around the spores, and at length one or more of them drives its pointed extremity into their naked surface ; after which, fertilization being accomplished, a thick coat of cellulose is deposited to complete the spore. 661. That in the Fucacee or olive-green Seaweeds, the highest tribe of Alew, the large spores are fecundated by spermatozoids, or minute lively-moving cells produced in antheridia, was demonstrated by Thuret in the year 1850.* And in more recent memoirs f he has shown that the fertilization takes place through direct contact of the spermatozoids with the naked surface of the unimpregnated spore, then having only a protoplasmic coating ; and that these spores will not develop unless so fertilized. Through the researches of Thuret and others, antheridia are now well known in the remaining or rose-red series of Algz, although their spermatozoids are not known to be endowed with motivity. The same appears to be the case with Lichens, the bodies described by Itsigsohn,} being probably of the nature of spermatozoids or fertilizing cells. In the vast family of Fungi there are similar indications of antheridia and spermatozoids, but the fecundation is not yet clearly made out. 662. Fertilization by Spermatozoids of a Cell in a Pistilidium, which becomes a Sporangium. In all the foregoing cases, the spores them- selves are the subjects of direct fertilization. But in Mosses, Liverworts, &c. (in which the two kinds of organs have long been recognized and their functions to some extent understood), the contents of the antheridium act upon an organ which, in conse- * Ann. Sci. Nat. ser. 8, vol. 14 and 16, 1850-1. See Harvey, Nereis Bor.- Amer. in Smithsonian Contributions, 1852, &c. 1 Op. cit. ser. 4, vol. 2 and 3, 1854, 1855. t In Botanische Zeitung, 1850. CRYPTOGAMOUS OR FLOWERLESS PLANTS. 337 quence of fertilization, develops into a sort of pod, the Sporangium or Spore-case, filled with a multitude of spores which receive no in- dividual fecundation ; this organ, from its general analogy to the pistil, has been termed a Pistillidium. The antheridia of Mosses and the like occur either in the axils of the leaves, or collected into a head at the summit of the stem. They are found either in the same heads as the pistillidia, or in distinct heads on the same individuals (moncecious), or on separate individuals (dice- cious). The antheridium (Fig. 1807) is merely a cylindrical or club-shaped sac, composed of a single layer of cells, united to form a delicate membrane; within which are developed vast numbers of minute, very delicate cells, completely filling the sac. The sac bursting at its apex when mature, the delicate vesicles are discharged. Each of these contains a slender filament, thick- ened at one end and tapering off to a fine point at the other: it may be seen through the transparent walls, spirally coiled up in the interior of each vesicle. When these vesicles are extruded in water under the microscope, the contained filaments may be seen to execute lively movements, wheeling round and round in the vesicle, or, when dis- engaged from the latter, and assuming a corkscrew form, at the same time advancing forward, the thin end of the filament almost always preceding. Minute. observation, which is very difficult, both from the rapidity of the motion (which, however, is arrested by poisons) and from the great delicacy of the whole structure, shows that the movements arise from two long and extremely delicate cilia, attached to the tapering end of the filament. These are the spermatozoids, or true fertilizing organs. The pistillidia (Fig. 13806), which ap- pear at the same time as the antheridia, and often mixed with them, are flask-shaped bodies (like an ovary in shape), with a long neck (resembling a style), composed of a cellular membrane. The neck is perforated by an open canal, leading to a cavity below, at the base of which a single cell is the germ of the future sporangium or spore- case. Upon this the spermatozoids, or spiral filaments of the an- theridia, act, one or more of them reaching it by finding their way down the canal of the pistillidium. Then this cell commences a special development, divides into two, and proceeds by ordinary cell- multiplication to build up the sporangium or capsule, in which a countless number of minute spores are produced. The spores of Mosses are formed in the same way as pollen-grains, which they much resemble in structure, being single cells with a double coat, of 29 338 REPRODUCTION IN which the inner is the true cell-wall, and the outer a sort of secre- tion from it. In germination, the inner or proper membrane of the spore swells, and protrudes, from any part of its surface favorably situated, a tubular process, which forms partitions as it elongates and branches, giving rise to what has been fancifully named a pro- embryo, or, better, a prothallus, — a rudimentary plantlet very unlike a Moss, but closely resembling a branched Conferva, consisting, as it does, merely of ramified threads, or rows of cells. After a time certain cells of its various branches, taking a special development, produce buds, which are soon covered with a tuft of rudimentary leaves, and grow up into the leafy stems of the perfected plant. Here a single spore— or rather a peculiar transitory plantlet developed from it — gives rise at once to a number of individuals. And in fecundation it is not the spores themselves that are fertilized, but a cell which by its development gives origin to a spore-case, and this to a vast number of spores.* 663. Fertilization of a Cell of a Prothallus, or peculiar germinating Plantlet, which thereupon develops into a Plant. This most extraordi- nary mode of fecundation has recently been discovered in the Ferns and other of the higher Cryptogamous orders. The fructification of Ferns consists of spore-cases alone, which are borne on the back, margins, or some other part of their leaves (Fig. 1287-1294), and are filled with spores resembling those of Mosses. Since Mosses have long been known to have organs answering in function to stamens, as well as those answering to pistils, and since Ferns are regarded as plants of higher rank than Mosses, their antheridia were diligent- ly sought for upon the fructifying plants, but in vain ; and botanists were therefore forced to the unwilling conclusion, that the highest organized of Cryptogamous plants were asexual. But antheridia, essentially like those of Mosses, have been at length detected, not upon the mature and fructifying plant, but upon the germinating plantlet. The germination of the spores of Ferns had long since been ob- served. The process begins in the same manner as in Mosses; but the extremity of the tubular prolongation of the spore, converted by partitions into a row of cells, is developed into an expanded, leaf- like body (the pro-embryo, or prothallus as it is now called), which * The fullest account is by Hofmeister, Vergleichende Untersuchungen der Keimung, Entfaltung, und Fruchtbildung Hoherer Kryptogamen, etc. — Leipsic, 1851. CRYPTOGAMOUS OR FLOWERLESS PLANTS. 339 on a small scale resembles a frondose Liverwort. Upon this body, Niigeli, in 1844, found moving spiral filaments, like those of ‘the an- theridia of Mosses, &c. This, as Henfrey remarks, “seemed to destroy all grounds for the assumption of distinct sexes, not only in the Ferns, but in the other Cryptogamia; for it was argued that the existence of these cellular organs producing moving spiral filaments (the so-called spermatozoa) upon the germinating fronds, proved that they were not to be regarded as in any way connected with the reproductive processes. But an essay published by the Count Suminski in 1848 totally changed the face of the question.” On the under side of the delicate, Marchantia-like, germinating frond, Suminski found a number of cellular organs of two distinct ‘kinds, answering to antheridia and pistillidia. The former, which are the more numerous, are cells elevated on the surface of the germinating frond, in the cavity of which are formed other cells, filled with minute vesicles containing each a spiral filament coiled up in its in-. terior. The organ bursts at its summit, and discharges the vesicles in a mucilaginous mass; the spiral filaments moving within the vesicles at length make their way out of them and swim about in the water. These filaments, or spermatozoids, resemble those of Mosses, but“are flat and ribbon-like, as in Chara, and possess accord- ing to Suminski about six, according to Thuret numerous cilia, by whose vibrations they are moved. The pistillidia, if they may be so called, are rounded cavities in the cellular tissue of the same body, opening on the under side, in the bottom of which is a single glob- ular cell, from which the future growth proceeds. One or more of the active spermatic filaments, liberated by the bursting of the an- theridia, have been found to enter the open pistillidium, and to come to rest and then wither away in contact with this specialized cell. The latter now develops into a bud, or embryo, as it may perhaps be termed, which grows in the ordinary way, producing an abbrevi- ated axis, sending roots downward and leaf after leaf upwards ; and so producing the mature Fern.* And, as most Ferns are perennial plants, they produce year after year their fructification (consisting * The English reader is referred to Henfrey’s Translation of Mohl’s Anatomy and Physiology of the Vegetable Cell; and Henfrey’s Report on the Reproduction and supposed Existence of Serual Organs in the higher Cryptogamous Plants, in the Report of the British Association for the Advancement of Science, for 1851, reprinted in Silliman’s Journal, Vol. 14 and 15; from which the above account has been condensed. 340 SPECIAL DIRECTIONS AND merely of spores in spore-cases), without any known limit, and with- out any other fecundation than that which occurred at first upon the germinating plantlet. 664. In Ferns, accordingly, it is not the sporangium that is fer- tilized, still less the spores, but a cell of a peculiar transitory plant- let formed by the germination of a spore. This cell otherwise will not develop at all; but when thus fecundated, it develops like a bud, and grows into a plant of indefinite longevity, capable of fructifying by a true parthenogenesis (571) throughout its long existence. This is also known to be the case with Equisetacex; and the Lycopodia- cee or Club-Mosses and other vascular Cryptogamous Plants are thought to have analogous fecundation, although the details as yet are not well made out. CHAPTER XIII. OF THE SPONTANEOUS MOVEMENTS AND VITALITY OF PLANTS, 665. Tue facts brought to view in the preceding chapter, namely, that either the spores or the fertilizing corpuscles or filaments of most Cryptogamous plants of every order are temporarily endowed with motivity, naturally raises'the inquiry whether such phenomena are altogether exceptional in the vegetable kingdom, or whether the power of executing movements is not a general endowment of plants as well as of animals, although in lesser degree. As we pass in re- view the various phenomena exhibited by plants in this respect, and at the same time consider that self-caused motion, internal or exter- nal, or the faculty of directing motion, is a necessary concomitant of life, we shall probably arrive at the conclusion, that this surprising activity of the microscopic spores and spermatozoids of Cryptogamous plants is not altogether anomalous, —that these are merely more vivid manifestations of a power which they share with ordinary vege- tables, — that plants are endowed with life no less really than ani- mals, — that the distinction between plants and the lower animals in this respect is one of degree rather than of kind,— and that it is a «characteristic of living things to move. SPONTANEOUS MOVEMENTS IN PLANTS. 341 666. The Special Directions which the parts of all plants assume are the result of self-caused movements, although such movements are mostly much too slow to be directly observed. Among these the most universal are the descent of the root in germination, the ascent of the stem into the light and air, and the turning of branches and the upper surface of leaves towards the light (120, 181, 294). These directions evidently are not the result of mere growth. It is not that the root grows downwards and the stem upwards ; but the root end of the elongating radicle bends or curves in the course of its growth so as to point downwards if not already in that. position, and the other extremity, with the plumule, curves upwards, and the young stem, after reaching the light, if unequally illuminated, bends towards the stronger light. 667. Strenuous attempts have been made to explain these changes of direction upon mechanical principles. Mr. Knight thought that the descent of the root and the ascent of the stem were caused by gravitation ; and he seemed to show this by his celebrated experi- ments of removing germinating seeds from the influence of gravita- tion, and causing the root and stem to take a different direction in obedience to a different force. THe fixed some beans ready to ger- minate in a quantity of moss upon the circumference of a wheel, and made it to revolve vertically at a rapid rate ; replacing the effect of gravity by centrifugal force. On examination, after some days, the young root was found to have turned towards the circumference, and the stem towards the centre of the wheel. The same result took place when the wheel was made to revolve horizontally with con- siderable rapidity ; but when the velocity was moderate, the roots were directed obliquely downwards and outwards, and the stems obliquely upwards and inwards, in obedience both to the centrifugal force and the power of gravitation, acting at right angles to each other. It remained for Mr. Knight to explain how the same force, gravitation, could produce such opposite effects, causing the stem to ascend as well as the root to descend. This he ingeniously at- tributed to their different mode of growth. The root growing at its extremity only, he supposed that the soft substance of the growing point would be acted upon by gravity like an imperfect solid, and accumulated on the lower side; while the stem, growing by the elongation of an internode or a series of internodes already formed, its solid tissues would be unaffected by gravity, which could affect only its nutritive juices, causing their accumulation on the lower side of a 29 * 342 SPECIAL DIRECTIONS AND stem out of the perpendicular line; which side, thus more actively nourished, would grow more vigorously than the upper, and so cause the stem to turn upwards. To show how baseless this ingenious hypothesis is, we have only to remember, on the one hand, that the fluid contents of the cells of plants arrange themselves in obedience to other forces than gravity, and freely rise against its influence to the summit of the loftiest trees, so that gravity could establish no difference within the diameter of a germinating stem; and on the other, that the root in germination, if fixed upon its surface, will pen- etrate a fluid of greater weight than itself, such as mercury. More- over, Schultz and Mohl have shown that, by careful management in reversing the ordinary conditions,—as by germinating seeds in damp moss, so arranged that the only light they could receive was reflected from a mirror, which threw the solar rays upon them directly from below, — the ordinary direction of the organs could be reversed, the roots turning upwards into the dark and damp moss, and the stems downward into the light. This would prove that light has more effect than gravitation, or any other imaginable influence of the mass of the earth. Yet, what shows that there is some real relation between the direction assumed by the plant and the earth, — stems which grow in complete darkness always point to the zenith, as is seen in the shoots of vegetables in perfectly dark cellars, and in the elongated, constantly upright stemlet of germinating seeds too deeply buried to receive any light before they reach the surface of the soil. 668. The influence of a mass in some way analogous to attrac- tion is also observed in the germination of the Mistletoe. Its form- ing root turns regularly to the trunk or branch upon which it is parasitic, just as those of ordinary plants turn to the earth. And that it is the mass and not the quality of the body which determines the direction, is seen when germinating seeds of the Mistletoe are fixed close to the surface of a cannon-ball: all the roots as they grow point to its centre and advance to its surface, just as they do to the branch of a tree which they penetrate. 669. When the stem has emerged from the earth into the light of day, this exerts a controlling influence over its direction. Young and green stems always tend to expose themselves as much as possi- ble to the light, and bend, very promptly when delicate, towards the’ most illuminated side, as is well observed when plants are raised in an apartment lighted from a single aperture: and consequently in the open air, being equally illuminated on all sides, they grow up- SPONTANEOUS MOVEMENTS IN PLANTS. 343 right. De Candolle attempted a mechanical explanation of this bending of green stems towards the light, connecting it with assimi- lation and growth. He supposed that, as the side upon which the light strikes will fix most carbon by the decomposition of carbonic acid (346 — 348), so its tissue will solidify faster, and therefore elon- gate less, than the shaded side (which will become drawn, as the gardener terms it); and the stem or branch will necessarily bend towards the shorter or illuminated side. But when the light is equally diffused around a plant, the decomposition of carbonic acid will take place uniformly on all sides, and the perpendicular direc- tion naturally be maintained. Two facts at once demolish this in- genious theory. 1. It is now well known that, under the solar spectrum, the decomposition of carbonic acid in the green parts of plants is effected chiefly by the most luminous rays, that is, by yellow light, and next to this by orange and red; whereas the bending is strongest under the violet and blue rays, the yellow producing little curvature, and the red none at all. 2. When a stem curved under the light is split from the apex downwards, so as to separate the illuminated from the shaded side, the former curves more than be- fore, while the latter tends to straighten,— showing that it was pulled over by the contraction of the concave side, and not pushed over by its own greater growth. J’rom all this it clearly appears that the turning of parts towards the light, and the other special directions of plants, are independent of growth, and apparently are effected by some inherent power. At least, they have thus far! proved no more susceptible of mechanical explanation than the more. marked movements of animals. 670. In leaves it is the denser and deeper green upper surface (262) that is presented to the light, while the paler lower surface, of looser tissue, avoids it. The recovery of the natural position, when the leaf is artificially reversed, is the more promptly effected in pro- portion to the difference in structure and hue between the two strata. This movement is so prompt in some plants, that their leaves follow the daily course of the sun. The leaf is more capable of executing such movements, on account of its extended surface, and its pliancy, and also on account of its usual attachment by an articulation. Here the slender vascular bundles oppose little resistance to lateral motion, while the soft and usually cellular enlargement favors it. Indeed, the efficient cause of the movement appears to be exerted here, and to be connected with the unequal tension or turgescence of 344 SPECIAL DIRECTIONS AND the cells on the two sides. We might therefore expect more prompt and obvious changes of position in leaves than in stems. Familiar examples of the kind are met with in the altered nocturnal position of the leaves, &c. of many plants (often drooping, or folded as if in repose), which Linneus designated by the fanciful name of 671. The Sleep of Plants, ‘This is well seen in the foliage of the Locust and of most Leguminous plants, and in those of Oxalis, or Wood-Sorrel. Jt is most striking in the leaflets of compound leaves. The nocturnal position is various in different species, but uniform in the same species, showing that the phenomenon is not mechanical. Nor is it a passive state, for, instead of drooping, as do those of the common Locust-tree, the leaflets are very commonly turned upwards, as those of Honey-Locust, or upwards and forwards, as in the Sensi- tive-Plant, contrary to the position into which they would fall from \ their own weight. De Candolle found that most plants could be | made to acknowledge an artificial day and night, by keeping them in , darkness during the day, and by illuminating artificially at night. | The sensibility to light appears to reside in the petiole, and not in \the blade of the leaf or leaflet; for these movements are similarly jexecuted, when nearly the whole surface of the latter is cut away. 672. The leaves of the blossom also assume various positions, according to the intensity and duration of the light. Many expand their blossoms in the morning and close them towards evening, never to be opened again, as those of Cistus, Portulaca, and Spider- wort; while others, like the Crocus, close when the sun is with- drawn, but expand again the following morning. On the other hand, the Evening Primrose, Silene noctiflora, &c. unfold their petals at twilight, and close at sunrise. The White Water-Lily (Nymphza) expands in the full light of day, but uniformly closes near the mid- dle of the afternoon, and is then usually withdrawn beneath the sur- face of the water. The Morning-Glory opens at the dawn; the Lettuce, and most Cichoraceous plants, a few hours later, but close under the noonday sun; the Mirabilis is called Four-o’clock, because opening nearly at that hour in the afternoon, and it closes the next morning; and so of other species, — each having its own hour or amount of light in which its blossoms open or close. Berthelot men- tions an Acacia at Teneriffe, whose leaflets regularly close at sunset and unfold at sunrise, while its flowers close at sunrise and unfold at sunset. Although these movements, both in leaves and blossoms, are undoubtedly dependent on the light, they are by no means directly SPONTANEOUS MOVEMENTS IN PLANTS. 345 governed by it. The so-called sleep of the common Sensitive Plant, for instance, begins just before sunset, but its waking frequently pre- cedes the dawn of day; showing that it is not the mere amount of the light which governs the position, in the manner of a mechanical power.* 673. Sensible Movements from Irritation, All the changes of posi- tion already described —like those of the hands of a clock or of the shadow on a dial— are too slow for the motion to be directly seen. But a greater exaltation apparently of this common faculty is observed in the leaflets of various Leguminous plants, especially of the Mimosa tribe, which, when roughly touched, assume their peculiar nocturnal position, or one like it, by a visible and sometimes a rapid movement. The Sensitive Plant of the gardens (Mimosa pudica) is a familiar instance of the kind, suddenly changing the position of its leaflets on being touched or jarred, and applying them one over the other close upon the secondary petiole ; if more strongly irritated, the secondary petioles also bend forward and approach each other, and the general petiole itself sinks by a bend- ing at the articulation with the stem. Similar although less vivid irritability is shown by the Mimosa strigillosa and the Schrankia of the Southern States, where the leaflets promptly fold up when brushed with the hand. The most remarkable instance of the kind, however, is presented by another native plant of the United States, the Dionza muscipula, or Venus’s Fly-trap (Fig. 297, 298) ; in which the touch even of an insect, alighting upon the upper surface of the outspread lamina, causes its sides to close suddenly, the strong bristles of the marginal fringe crossing each other like the teeth of a steel-trap, and the two surfaces pressing together with considerable force, so as to retain, if not to destroy, the intruder, whose struggles only increase the pressure which this animated trap exerts. This most extraordinary plant abounds in the damp, sandy savannas in the neighborhood of Cape Fear River, from Wilmington to Fayette- * The odors of flowers, also, are sometimes given off continually, as in the Orange and the Violet, or flowers may nearly lose their fragrance during the heat of mid-day, as in most cases ; while others, such as Pelargonium triste, Hesperis tristis, and most dingy flowers, which are almost scentless during the day, ex- hale a powerful fragrance at night. The night-flowering Cereus grandiflorus emits its powerful fragrance at intervals; sudden emanations of odor being given off about every quarter of an hour, during the brief period of the expan-; sion of the flower. Sek ee erty 346 SPONTANEOUS MOVEMENTS IN PLANTS. ville, North Carolina, where it is exceedingly abundant ; but it is not elsewhere found. 674. A familiar, although less striking, instance of the same kind is seen in the stamens of the common Barberry; which are so excit- able, that the filament approaches the pistil with a sudden jerk, when touched with a point, or brushed by an insect, near the base on the inner side. The object of this motion seems plainly to be the dis- lodgement of the pollen from the cells of the anther, and its projec- tion upon the stigma. But in the Dionza it is difficult to conceive what end is subserved by the capture of insects. In a species of Stylidium of New Holland, not uncommon in conservatories, the column, consisting of the united stamens and styles, is bent over to one side of the corolla; but if slightly irritated, it instantly springs over to the opposite side of the flower. These are among the more remarkable cases of the kind, but by no means the only ones. Anatomical investigation brings to view no peculiarity in the struc- ture of such plants which might explain these movements. Some other movements, which have been likened to these, are entirely mechanical; as that of the stamens of Kalmia, where the ten an- thers are in the bud received into as many pouches of the mono- petalous corolla, and are carried outwards and downwards when the corolla expands. In this way the slender filaments are strongly re- curved, like so many springs; until at length, when the anthers are liberated by the full expansion of the corolla, or by the touch of a large insect or other extraneous body, they fly upwards elastically, projecting a mass of pollen in the direction of the stigma. 675. The twining of stems round a support, and the coiling of tendrils, are attributed by Mohl to a dull irritability ; and this is the most plausible explanation that has been offered. The inner side, which becomes concave and has smaller cells, is in this, as in other cases, the irritable portion. When a foreign body is reached, a contraction of this side causes the tendril partially to embrace the support: this brings the portion just above into contact with it, which is in like manner incited to curve; and so the hold is secured, or the twining stem continues to wind around the support. In ten- drils this irritability, propagated downward along the concave side, would appear to cause its contraction, which throws the whole into a spiral coil, or, when fixed at both ends, into two opposite spiral coils, thus approximating the growing stem to the supporting body. SPONTANEOUS MOVEMENTS IN PLANTS. 347 676. In all these cases, whether of slow or rapid change of posi- tion, the immediate cause of the movement, however incited, must be either the shortening of the cells on the concave side, or their elongation on the convex side. The fact that stems curved towards the light tend to curve still more when the convex side is cut away (669) points to a contraction of the cells on the concave side as the cause of the curvature. The elastically bursting pods of the Balsam or Touch-me-not (Impatiens), &c. confirm this view. Here the valves of the capsule curve inwards very strongly when liber- ated in dehiscence ; and that this is owing to the shortening of the cells of the inner layer, and not to the enlargement or turgescence of those of the thick outer layer, is readily shown by gently paring away the whole outer portion before dehiscence ; for the inner layer when liberated still incurves and rolls itself up as strongly as before. The short valves at the summit of the pod of Echinocystis slowly curve outwards in dehiscence; here the cells of the outer layer of the valve are longer and narrower than those of the inner, and the latter are stretched and torn in opening; so that here the con- traction of the cells on the side which becomes concave is undoubt- edly the cause of the movement. And since muscular movements are effected by the contraction of the cells which, placed end to end, compose a muscular fibril, we may suspect that vital movements generally, both in vegetables and in animals, are so far analogous, that they are brought about in the same general way, viz. by the shortening of cells. Even the opening and closing of the stomata of the leaves (268) appear to be controlled by the vital force, and to be effected by a self-caused change in the form of the guardian cells. How the light, or external irritation, or any other influence, acts in inciting this change of form of the cells of some part of a plant, we know no more, and no less, than we know how a nerve, or an electrical current, acts upon a muscle of an animal to bring about the contraction or change of shape of its component cells. If animals make 677. Spontaneous or Automatic Movements, so also do some plants execute brisk and repeated movements irrespective of extraneous force, or even of extraneous excitation, and which, indeed, are ar- rested by the touch. An instance of such spontaneous and contin- ued motion, of the most remarkable kind, is furnished by the trifoli- olate leaves of Desmodium gyrans, an East-Indian Leguminous plant. The terminal leaflet does not move, except to change from the 348 SPONTANEOUS MOVEMENTS IN PLANTS. diurnal to the nocturnal position, and the contrary; but the lateral ones are continually rising and falling, both day and night, by a suc- cession of little jerks, like the second-hand of a time-keeper ; the one rising while the other falls. Exposure to cold, or cold water poured upon the plant, stops the motion, which is immediately re- newed by warmth. The late Dr. Baldwin is said by Nuttall to have witnessed the same thing in our own Desmodium cuspidatum, in Georgia; but the observation has never been confirmed. In several tropical Orchideous plants, and especially in a species of Megaclinium, the lower petal, or labellum, executes similar spontane- ous movements, with great freedom and pertinacity. Such phenom- ena, occurring as they do in Phenogamous plants of ordinary struc- ture may serve to render more credible the true vegetable character of the 678. Free Movements of the Spores of Algw, and the cor- puscles or spiral filaments of the antheridia of most Cryp- togamous plants, already re- ferred to (659-663). The spores of most of the lower Algz are now known to ex- hibit this peculiar activity at the time of their discharge from the parent cell, when, for some moments, or usual- ly for several hours, they behave like infusory ani- mals, executing spontaneous movements in the water, until they are about to ger- minate. This singular move- ment was first detected many years ago, in Vaucheria a3 FIG. 636. Fruiting end of a plant of Vaucheria geminata (after Thuret); one of the branches still containing its spore. 637. Moving spore just escaped from the apex of the other branch ; the ciliary apparatus seen over the whole surface. 688. Spore in germination. FIG. 689-642. Successive steps in the germination of Gdogonium (Conferva) vesicata. 648. The plant developed into a series of cells, four of which display the successive steps in the formation of a spore. 644. The locomotive spore with its vibratile cilia (copied from Thuret). When the movement ceases, and it begins to germinate, it appears as in 639. (The antheridia or fertilizing apparatus of these plants were not known when these figures were made.) SPONTANEOUS MOVEMENTS IN PLANTS. 349 (Fig. 89, 636). Immediately on its discharge from the mother plant the spore begins to move freely in the water, and continues to do so for some hours, when it fixes itself and begins to grow (Fig. 638). Its movements, moreover, like those of the antheridial fila- ments or corpuscles, may be enfeebled or arrested by the application of a weak solution of opium or chloroform. Through these means it has been ascertained that they are caused by the vibrations of minute cilia which cover the surface, which are rendered visible by thus enfeebling their movement, and which exhibit the closest resemblance to the vibratile cilia of animals, especially those of the polygastric animalcules. In the Conferva tribe generally the vibra- tile cilia occupy one end of the spore, and are in some cases numer- ous (as in Fig. 644), in others only two or three in number. The spores are small, and of about the same specific gravity as the water in which they live, so that a slight force suffices to propel them. 679. Locomotion of Adult Microscopic Plants. The spores of Vau- cheria and the like, becoming quiescent before germination, grow into fixed thread-like plants of considerable size, endowed with no greater degree of motivity than ordinary vegetables. A multitude of still simpler Algz, however, swarm in every pool or stream, so: minute in size as to be individually totally invisible to the naked. eye (most of them when full grown are very much smaller than the: spores of Vaucheria, &c.) ; and these are endowed, even at maturity, with such powers of locomotion that their vegetable character, although now well made out, was long in question on this account alone. Of this kind are the various species of Oscillaria (Fig. 84), so named from the writhing movement they exhibit, the Desmidi-. acex, to which Closterium (Fig. 631) belongs, and the: nearly allied Diatomace,—the lowest, minutest, and the most freely moving of plants, but clearly members of the vegetable kingdom notwithstanding. These execute free movements of translation, in some cases slow, in others rapid; but the mechanism of the: motion is still unknown. 680. Not only, therefore, do plants generally manifest impressi- bility or sensdtiveness to external agents, and execute more or less decided, though slow, movements; but many species of the higher grades exhibit certain vivid motions, either spontaneous or in conse-- quence of extraneous irritation ; while the lowest tribes of aquatic plants, as they diminish in size and in complexity of organization, habitually execute, at some period at least, varied spontaneous move- 30 350 SPONTANEOUS MQVEMENTS IN PLANTS. ments, which we are unable to distinguish in character from those of the lowest animals. It is at their lowest confines, accordingly, that the vegetable and the animal kingdoms approach or meet, and even seem to blend their characters. 681. When we consider that the excitability of sensitive plants is often transmitted, as if by a sort of sympathy, from one part to another; that it is soon exhausted by repeated excitation (as is certainly the case in Dionea, the Sensitive-Plant, &c.), to be re- newed only after a period of repose; that all plants require a season of repose; that they consume their products and evolve heat under special circumstances with the same results as in the animal kingdom (Chap. VII.); that, as if by a kind of instinct, the various organs of the vegetable assume the positions or the directions most favorable to the proper exercise of their functions and the supply of their wants, to this end surmounting intervening obstacles ; when we consider in this connection the still more striking cases of spon- taneous motion that the lower Alge exhibit; and that all these motions are arrested by narcotics, or other poisons, — the narcotic and acrid poisons even producing effects upon vegetables respectively analogous to their different effects upon the animal economy; we cannot avoid attributing to plants a vitality and a power of “making movements tending to a determinate end,” not different in nature, perhaps, from those of the lowest animals. Probably life is essen- tially the same in the two kingdoms ; and to vegetable life faculties are superadded in the lower animals, some of which are here and there not indistinctly foreshadowed in plants. 682. The essential differences between plants and animals were enumerated at the commencement of this work (16), and have been illustrated in its progress. Distinct as are the general structure and the offices of the two great kinds of organized beings, it is still | doubtful whether the discrimination is absolute, or whether the ' functions of the vegetable and the animal may not, in some micro- scopic organisms, be imposed upon the same individual. PART II. SYSTEMATIC BOTANY. 683. In the preceding chapters plants have been considered in view of their structure and action. And when different plants have been referred to and their diversities noticed, it has been in eluci- dation of their morphology, — of the exuberantly varied forms or modifications under which the simple common plan of vegetation is worked out, as it were, in rich detail. The vegetable kingdom, that is, vegetation taken as a great whole, presents to our view an im- mense number of different kinds of plants, more or less resembling each other, more or less nearly related to each other. It is the object of Systematic Borany to treat of plants as members of a system, or orderly parts of a whole,— and therefore to consider them as to their kinds, marked by differences and resemblances, and to contemplate the relations which the kinds, or individual members of the great whole, sustain to each other. To this end the botanist classifies them, so as to exhibit their relationships, or degrees of resemblance, and expresses these in a systematic arrangement or classification, — designates them by appropriate appellations, and distinguishes them by clear and precise descriptions in scientific lan- guage; so that not only may the name and place in the system, the known properties, and the whole history of any given plant, be read- ily and surely obtained by the learner, but likewise an interesting view may be obtained of the general scheme or plan of the Cre- ator in the Vegetable World. 684. Our present endeavor will be to explain the general prin- ciples of natural-history classification, and the foundation, or facts in nature, upon which it rests, and then cursorily to show how these are applied to the actual arrangement of the known species of plants. 352 PRINCIPLES OF CLASSIFICATION. CHAPTER I. OF THE PRINCIPLES OF CLASSIFICATION. 685. Piants and animals —the members of the organic king- doms of nature — exist as individuals (18), of definite kinds, each endowed with the characteristic power of producing like individuals and so of continuing the succession. The different sorts (1.) are re- produced true to their essential characteristics from generation to generation ; and (2.) they exhibit unequal and very various degrees of resemblance or of dissimilarity among themselves. These simple propositions lie at the foundation of all classification and system in natural history. Upon the first rests the idea of species ; upon the second that of genera, orders, and all groups higher than species. 686. Individuals. The idea of individuality is derived from man and ordinary animals, and thence naturally extended to vegetables. Individuals are beings, owing their existence and their characteris- ties to similar antecedent beings, and composed of parts ‘which together constitute an independent whole, indivisible except by mu- tilation. Individuality is perfectly exemplified in all the higher and most of the lower animals, which multiply by sexual propagation only, and in which the offspring, or the ovum, early separates from the parent; but it is incompletely realized in those animals of the lower grade which are propagated by buds or offshoots as well as by ova, and where the offspring may remain more or less intimately connected with the parent. Still more is this so in plants, which in every grade are or may be propagated by buds or offshoots; which in vegetation develop an indefinite number of similar parts ; which produce branches like the parent plant, and capable either of continuing to grow in connection with it, or of becoming independent (282). The individual plant, therefore, is evidently not a simple and true individual in the proper sense of the word, —in the sense that an ordinary animal is. A kind of social or corporate individu- ality in the complex radiated animals often gives a certain limita- tion and shape to the congeries or polypidom, and in many of them even subordinates certain parts to the common whole, assigning to them special functions for the common weal: and this-is universally and more strikingly the case with plants, except the very simplest. Es a4 4 fir INDIVIDUALS. 853 So that for practical purposes, and in a loose, general sense, we take the whole plant as an individual, so long as it forms one con- nected mass, and no longer. But in a philosophical view we cannot well regard this congeries as the true vegetable individual. 687. Accordingly many botanists (of whom are Thouars at the beginning of the present century, and Braun * at the present day) regard as the true individual the shoot, or simple axis with its foli- age, &c., whether this be the primary stem with its roots implanted in the soil, or a branch implanted on the stem. This view simpli- fies our conception of a vegetable, but is itself open to all the objec- tions it raises against the individuality of the plant as a whole. For just as the herb, shrub, or tree is divisible into shoots or series of similar axes, so the shoot is divisible into similar component parts, or phytons (163), indefinitely repeated, and which may equally give rise to independent plants. Those philosophical naturalists, there- fore, who find no stable ground in this position, are forced towards one of two opposite extremes. Some, justly viewing sexual repro- duction as of the highest import, are led to regard the whole vege- tative product of a seed as theoretically constituting one individual, whether the successive growths remain united, or whether they form a thousand or a million of vegetables, as may often happen. Ac- cording to this view, all the Weeping-Willow trees of this country are parts of one individual ; and most of our Potato plants must be- long to one multitudinous individual, while others wholly similar, but freshly grown from seed, are- each individuals of themselves; — a view which apparently amounts to an absurdity in terms and in fact. Others, following out the idea mentioned above, and laying the main stress upon simplicity and indivisibility, rather than upon tendency to separation, regard the phyton in ordinary plants, and the cell in those of lowest grade, as on the whole best answering, in the vege- table kingdom, to the simple individual in the animal. But this is merely a question of greater or less analogy. For the individual, in the proper sense of the term, is more or less confluent into a vegeta- tive cycle in all plants, and in many of the lower animals, and attains full realization only in the higher grades of organized existence. * See his elaborate treatise, On the Vegetable Individual in its Relation to Species (of which a translation from the German, by C. F. Stone, was published in the American Journal of Science and the Arts, vols. 19 and 20, 1855), for the com- pletest development of this view, and for the history of the subject generally. 30 * 354 PRINCIPLES OF CLASSIFICATION. 688. But, whatever it may be which we practically or philosophi- cally regard as the vegetable individual, it is evident that plants as well as animals occur in a continued succession of organisms or beings which stand in the relation of parent and offspring. Each particular sort is a chain, of which the individuals are the links. To this chain, or (as expressed by Linnaeus) this perennial succes- ston of individuals, the natural-historian applies the name of 689. Species (14). Every one knows that the several sorts of plants and animals steadily reproduce themselves, or, in other words, keep up a succession of essentially similar individuals, and under favorable circumstances increase their numbers. Each particular kind of cultivated plant or domesticated animal is represented before our eyes in a mass of individuals, which we know from observation to a certain extent, and from necessary inference, have sprung from the same stock. And common observation has led people everywhere to expect that the different sorts will continue true to their kind, or at least to conclude that the different sorts of plants or of animals do not shade off one into another by insensible grada- tions, like the colors of the rainbow, as would have been the case if there were not distinct kinds at the beginning, and if their distinc- tions were not kept up, unmingled, and transmitted essentially un- altered, from generation to generation. So we naturally assume that the Creator established a definite, although a vast, number of types or sorts of plants and animals, and endowed them with the faculty of propagation each after its kind; and that these have so continued unchanged in all their essential characteristics. Out of these gen- eral observations and conceptions the idea of species must have origi- nated ; from them we deduce its scientific definition. Namely, that the species is, abstractly, the type or original of each sort of plant, or animal, thus represented in time by a perennial succession of like individuals, or, concretely, that it is the sum of such series or con- geries of individuals; and that all the descendants of the same stock, and of no other, compose one species. And, conversely, as we can never trace back the genealogy far, we naturally infer community of origin from fraternal resemblance; that is, we refer to the same species those individuals which are as much alike as those are which we know to have sprung from the same stock.* * We use the word stock advisedly, (and in one of its proper meanings, that of the original or originals of a lineage,) to avoid the assertion or denial of the SPECIES AND VARIETIES. 355 690. Specific identity is not of course inferred from every strongly marked resemblance; for the resemblance may be only that of genus, and individuals so related are inferred not to have had a common origin. Nor is it denied on account of every difference ; for individu- als of the same stock may differ considerably ; in fact, no two plants are exactly alike, any more than two men are. Such differences when they become distinctly marked give rise to 691. Varieties. Iftwo seeds from the same pod are sown in dif- ferent soils, and submitted to different conditions as respects heat, light, and moisture, the plants that spring from them will show marks of this different treatment in their appearance. Such differ- ences are continually arising in the natural course of things, and to produce and increase them artificially is one of the objects of culti- ‘vation. Such variations in nature are transient; the plant often outlasting the cause or outgrowing its influence, or else perishing from the continued and graver operation of the modifying influ- ences. But in the more marked varieties which alone deserve the name, the cause of the deviation is occult and constitutional; the deviation occurs we know not why, and continues throughout the existence and growth of the herb, shrub, or tree, and consequently through all that proceeds from it by propagation from buds, as by off- sets, layers, cuttings, grafts, &c. In this way choice varieties of Ap- ples, Pears, Potatoes, and the like, are multiplied and perpetuated. 692. Since the progeny inherits or tends to inherit all the char- acters and properties of the parent, constitutional varieties must have a tendency to be reproduced by seed,—a tendency which might often prevail, within certain limits, over that general influence which would remind the variety to the normal state, were it not for the commingling which so commonly occurs in nature, through the cas- ual fertilization of the ovules of one individual by the pollen of other individuals of the same species. By assiduously pursuing the oppo- origin of each species from a single individual or a single pair, —a question which science does not furnish grounds for deciding. It is evidently more simple to assume the single origin, where there is no presumption to the con- trary, as there may be in the case of tricecious or of organically associated plants or animals ; but the contrary supposition does not affect our idea of specics, if* we suppose the originals to have been as much alike as individuals proceeding from the same parent are, and to have had a common birthplace. The investi- gation of the geographical distribution of plants more and more favors the idea of the dissemination of each species from a centre of its own. 856 PRINCIPLES OF CLASSIFICATION. site course in domesticated plants, that is, by constantly insuring the fertilization of the ovules of a marked variety by the pollen of the same, and by saving seed only from such of the resulting progeny as possess the desired peculiarity in the highest degree, and so on for several generations, it would appear that 693. Races, viz. varieties whose characteristics are transmissible by seed with considerable certainty, may generally be produced. Of this kind are the particular sorts of Indian Corn, Rye, Cabbage, Lettuce, Radishes, &e., and indeed of nearly all our varieties of culti- vated annual and biennial esculent plants, as well as of several per- ennials, many of which have been fixed through centuries of domes- tication. { What is now taking place with the Peach in this country may convince us that races may be developed in trees as well as in ‘ herbs, and in the same manner; and that the reason why most of our cultivated races are annuals or biennials is because these can ; be perpetuated in no other way, and because the desired result is obtainable in fewer years than in shrubs or trees. Although " races hardly exist independently of man, he cannot be said to origi- nate their peculiarities, nor is it known how they originate. The sports, as the gardener calls them, appear as it were accidentally ' ‘in cultivated plants. The cultivator merely selects the most promis- ing sorts for preservation, leaving the others to their fate. By par- ticular care he develops the characteristic feature, and strengthens and fixes, in the manner already explained, the tendency to become hereditary, so securing the transmissibility of the variety as long as he takes sufficient care of it. If not duly cared for, they dwindle and } lose their peculiarities, or else perish ; if allowed to mix with normal ' forms, they revert to the common state of the species. Were culti- vation to cease, all these valued products of man’s care and skill would doubtless speedily disappear ; the greater part, perhaps, would perish outright ; the remainder would revert, in a few generations of spontaneous growth, to the character of the primitive stock. 694. Although man has no power to create the peculiarities of such varieties, he may manage so as not only largely to increase them, but also to combine the peculiarities of widely different varic- ties of a species, and thereby produce novel results. This is effected “by Cross-breeding, i. ¢. by fertilizing the pistil of one variety with the pollen of another variety of the same species. In this way most esteemed new varieties of flowers and fruits are originated, which combine the separate excellences of both parents. The cultivator RACES, HYBRIDS, ETC. 857 often proceeds one step farther, in certain cases, and gives rise to a different kind of cross-breeds, viz. 695. Hybrids. These are cross-breeds from different but nearly related species. It is well known that, by proper precautions, the pistil of a flower of one species may often be fertilized by the pollen of another of a similar constitution, and that the plants raised from the seeds so produced combine the characters and properties of both parents. Some kinds, such as Azaleas and Pelargoniums, hy- bridize very readily; in others hybridism is effected with difficulty between nearly related species. The gardener produces hybrids among most of his favorite plants, and variously cross-breeds and mingles them, so as to confuse the limits of many cultivated species. But in nature hybrids rarely occur. Not more than fifty wild kinds are clearly known as of continued or frequent occurrence. Others may perhaps be originated from time to time; but their existence is transient. {For hybrids are generally, if not always, sterile, and/ therefore incapable of perpetuation by seed. | But their ovules may be fertilized by the pollen of either of their parents, when the progeny reverts to that species, probably retaining, however, some traces of the mixture, unless this should be obliterated by successive fertilizations from individuals of the same parent species. It is probable that cross-fertilization between different individuals of the same species is more common than is generally supposed, and that it is one of Nature’s means for repressing variation. On the other hand, continued self-fertilization (or breeding in and in) is almost sure to perpetuate, as well as farther to develop, individual peculiari- ties, i. e. those of variety or race. 696. However plants may be modified by art and man’s device, the systematic botanist proceeds upon the ground that the distine- tions between species, whether small or great, are real, and in nature’ are permanent, — that variation, wide as it may be, is naturally re- stricted within certain limits. And this appears to be true. As dis- tinctions subordinate to species are in nature both indefinite and transitory, these, however important to the cultivator, are of little account with the systematic botanist. 697. Species are the true subjects of classification. And the end and aim of systematic botany is to ascertain and to express their relationship to each other. The whole ground in nature for the classification of species is the obvious fact that species resemble or differ from each other unequally and in extremely various de-- 358 PRINCIPLES OF CLASSIFICATION. grees, If this were not so, or if related species differed one from another by a constant quantity, so that, when arranged according to their resemblances, the first differed from the second about as much as the second from the third, and the third from the fourth, and so on throughout, —then, with all the diversity in the vege- table kingdom there actually is, there could be no natural founda- tion for their classification. The multitude of species would render it necessary to classify them, but the classification would be wholly artificial and arbitrary. The actual constitution of the vegetable kingdom, however, as appears from observation, is, that some species resemble each other very closely indeed, others differ as widely as possible, and between these the most numerous and the most various grades of resemblance or difference are presented, but always with a manifest tendency to compose groups or associations of resembling species, — groups the more numerous and apparently the less defi- nite in proportion to the number and the nearness of the points of resemblance. These various associations the naturalist endeavors to express, as far as is necessary or practicable, by a series of generali- zations, — of which the lower or particular are included in the higher, — based on the more striking, or what he ‘deems the most important (i. e. the most definite or least exceptional) points of re- semblance of several grades. Linnzus and the naturalists of his day mainly recognized three grades of association, or groups supe- rior to species, viz. the genus, the order, and the class ; and these are still the principal members of classification. Of these 698. Genera (plural of Genus) are the more particular or special groups of related species. They are groups of species which are most alike in all or most respects, — which are constructed, so to say, upon the same particular model, with only circumstantial dif- ferences in the details. They are not necessarily nor generally the lowest definable groups of species, but are the lowest most clearly definable groups which the botanist recognizes and accounts worthy to bear the generic name; for the name of the genus with that of the species added to it is the scientific appellation of the plant or animal. Constituted as the vegetable and animal kingdoms are, the recognition of genera, or groups of kindred species, is as natural an operation of the mind as is the conception of species from tlie asso- ciation of like individuals. This is because many genera are so strongly marked, or at least appear to be so, as far as ordinary ob- . servation extends. Every one knows the Rose genus, composed of GENERA AND ORDERS. 359 the various species of Roses and Sweetbriers ; the Bramble. genus, comprising Raspberries, &c., is popularly distinguished to a cer- tain extent; the Oak genus is distinguished from the Chestnut and the Beech genus, &c.: each is a group of species whose mutual resemblance is greater than that of any one of them to any other plant. The number of species in such a group is immaterial, and in fact is very diverse. A genus may be represented by a single known species, when its peculiarities are equivalent in degree to those which characterize other genera, — a case which often occurs ; although if this were generally so, genus and species would be equivalent terms. If only one species of Oak were known, the Oak genus would have been as explicitly discerned as it is now that the species amount to two hundred; it would have been equally distin- guished by its acorn and cup from the Chestnut, Beech, Hazel, &c. Familiar illustrations of genera in the animal kingdom are furnished by the Cat kind, to which belong the domestic Cat, the Catamount, the Panther, the Lion, the Tiger, the Leopard, &c.; and by the Dog kind, which includes with the Dog the different species of Foxes and Wolves, the Jackal, &c. The languages of the most barbarous people show that they have recognized such groups. Naturalists merely give to them a greater degree of precision, and indicate what the points of agreement are. 699. If all such groups were as definite and as conspicuously marked out as those from which illustrations are generally taken, genera might be as natural as species. But unfortunately the pure- ly popular genera are comparatively few, and although often cor- rectly founded by the unscientific, yet they are as frequently wrongly limited, or based upon fanciful resemblances. Popular nomencla- ture, embodying the common ideas of people, merely shows that generic groups are recognizable in a considerable number of cases, but not that the whole vegetable or the whole animal kingdom is divisible into a definite number of such groups of equally or some- what equally related species. Whether this proves to be so or not, and whether genera are actually limited groups throughout, this is not the place to consider. Suffice it to say, that there is a ground in nature for genera, and that the naturalist is obliged to treat them, for systematic purposes, as strictly definite groups of species. While genera represent the closer relationships of species, 700. Orders or Families (as they are interchangeably called in botany) express remoter relationships or more general resemblances. 360 PRINCIPLES OF CLASSIFICATION. They are groups of kindred genera, or rather genera of a higher grade. For example, Oaks, Chestnuts, Beeches, Hazels, and Horn- - beams constitute so many genera, which, although quite distinct, have so strong a family likeness, and are so much alike in their general structure and properties, that they are associated into one order or family group (the Oak family); while the Birches and the Alders form another order not very different in character, and the Walnuts and Ilickories another. So the Pines, Firs or Spruces, Larches, Cedars, &c., obviously related among themselves so much more than they are to any other genera, are members of the Pine family; the Raspberry, Blackberry, and Strawberry, with many others, are as- sociated with the Rose in the Rose family; and so on. 701. Classes are to orders what these are to genera. They ex- press more extensive, or the most extensive relations of species, each class embracing all those species which are framed upon the same general plan of structure, however differently that plan may be carried out in particulars. Thus all Exogenous or Dicotyledonous plants constitute one class, their stems, their embryo, their lcaves, &c, being constructed upon the same general plan in all the species, while Endogenous or Moncotyledonous plants for the same reasons compose another class. 702. The sequence of groups, rising from particular to universal, is Species, Genus, Order, Class ; or, in descending from the univer- sal to the particular, Crass, ORDER, GENUS, SPEcIEs. 703. These are the common framework of all methods of classifi- cation, both in the animal and the vegetable kingdoms. But these do not exhaust our powers of analysis, nor express all the gradations which we may observe in the relationship of species. They merely gather up what are deemed the most essential indications of re- lationship, and express them under three grades superior to species, which always carry with them distinctive names. But a more elab- orate analysis is often requisite, on account of the large number of objects to be arranged, and the various degrees of relationship which may come into view. And these, when needful, are expressed in a series of intermediate groups or divisions, which may or may not requite distinctive names. Names for them are, however, a ORDERS, CLASSES, AND TIIEIR SUBDIVISIONS. 361 great convenience, especially for those which are most natural and definite. For some of these intermediate groups may be as dis- tinctly marked as are those which we call genera or orders. 704. The great advantages and proper use of this intermediate grouping are, that it secures all the benefits of complete analysis without undue multiplication of genera and orders, and that, by ex- tending the scale, more grades of relationship may be noted, and the whole expressed in our systems in truer perspective. Accordingly, when groups of species below what we take for genera are recog- nized, and found to be so well marked that by a little lowering of the scale they would be received as genera, they are denominated SusGenera. If less definite, we term them merely Sections. For example, Pyrus, the Pear genus, embraces Apples, Pears, Crab- apples and the like; and the Pear itself is the type or normal rep- resentative. From this the Apple and the several species of Crab- apple differ considerably, but not quite enough to warrant generic separation: they are therefore recognized as forming a subgenus, Malus, of the genus Pyrus. Again, the Bramble genus, Rubus, com- prises both Raspberries and Blackberries, which, although distin- guished by everybody, are not so much or so definitely different from each other as Apples and Crab-apples are from Pears; so they are ranked merely as sections of the Bramble genus. ‘If we were to receive all such particular groups of species as genera, and give them substantive names, as many naturalists are doing, the nicer grada- tions of affinity would be disregarded, while genera would be reck- oned by tens of thousands ; at length half our species would become genera with substantive names, and the whole advantage of classifi- cation and nomenclature would be lost. The proper discrimination of genera is the real test of a naturalist. 705. When groups intermediate between genera and orders are admitted, they are generally denominated Trivers, and their divis- ions, if any, SuBTRIBES. But the highest divisions of orders, when marked by characters of such importance that it might fairly be questioned whether they ought not to be received as independent orders, take the name of Susorpers. For example, the great Rose family, as we receive it, embraces three suborders; one of them represented by the Plum, Peach, Almond, &c. ; a second, by the Pear, Quince, Hawthorn, and the like; and the third, by the Rose itself and its immediate relatives. Some botanists receive these three as so many orders: we regard them as suborders, be- 31 362 PRINCIPLES OF CLASSIFICATION. cause of the strong family likeness which pervades the whole, and of the transitions between them. In the larger of these suborders, or the proper Rose family, we recognize three tribes: one repre- sented by the Rose genus itself; one by the Bramble genus, with the Strawberry, Cinquefoil, Avens, &c.; and the third by Spirza and its near relations. And, again, the second and larger of these embraces genera which are different enough to be ranked under several subtribes. 706. Upon the same principles, groups may be interposed between the orders and the classes, of which the highest kind will take the name of SuBcLassES. And even above classes we have the most comprehensive division of all plants into a higher and a lower grade or Serres (98); which brings us up to the vegetable Kinepom, one of the three great departments of Nature. 707. To exhibit the whole sequence or stages of natural-history classification, so that the student may see the relative rank of groups, designated by the terms which have now been explained, they are here presented, arranged in a descending series, beginning with the primary division of natural objects into kingdoms, and indicating by small capitals those of fundamental importance and universal use in classification. Kinepoms, Series, CLassEs, Subclasses, OrpDERs or FAMILIES, Suborders, Tribes, Subtribes, GENERA, Subgenera, SPECIEs, Varieties, Individuals. 708. Characters. An enumeration of the distinguishing marks, or points of difference between one class or order, &c. and the others, is termed its character. Characters accordingly properly embrace only those points which are common to all plants of the group, but not to the other groups of the same rank. The characters of classes, &c. are restricted to those general peculiarities of structure upon which these great groups are established: the ordinal charac- ter recites the particulars in which the plants it comprises differ CHARACTERS. — BINOMIAL NOMENCLATURE. 863 from all others of the class ;. the generte character enumerates those points which distinguish the plants of the genus in question from all others of the same order or suborder ; the specific character indicates the differences between species of the same genus ; —— to which in botanical works more or less of general description, accord- ing to the plan and extent of the work, is generally added. 709. A complete system of Botany will therefore comprise a methodical distribution of plants according to their organization, with their characters arranged in proper subordination ; so that the investigation of any one particular species will bring to view, not only its name (which separately considered is of little importance), but also its plan of structure, both in general and in particular, its relationships, essential qualities, and whole natural history. The classification and the method of investigation in natural history con- stitute not only the most complete arrangement known for the col- location of a vast amount of facts, but also the best system of prac- tical logic; and the study exercises and sharpens at once both the powers of reasoning and of observation, more, probably, than any other pursuit. As a system for collocating facts for convenient ref- erence, a great practical advantage of natural history is secured by its happily devised 710. Binomial Nomenclature: Since the time of Linnzus, who in- troduced the system, the scientific name of every plant is expressed by two words, viz. by the name of its species appended to that of its genus, each of a single word. That of the genus, i. e. the ge- neric name, is a substantive; that of the species, or the specific name, is an adjective adjunct. The same name is never employed for different genera; the same specific name is not available for more than one species of the same genus, but may be used in any other genus. A few thousand names accordingly serve completely to designate something like 8,000 genera and nearly 100,000 species of plants, in a manner which obviates all confusion, and does not greatly burden the memory. The generic name of a plant answers to the surname of a person, as Brown or Jones; the specific name answers to the baptismal name, as John or James. Thus, Quercus alba is the botanical appellation of the White Oak; Quercus being the substantive name for the genus, and alba (white) the adjec- tive name for this particular species ; while the Red Oak is named Quercus rubra; the Scarlet Oak, Quercus coccinea ; the Live Oak, Quercus virens; the Bur Oak, Quercus macrocarpa; and so on. 364 PRINCIPLES OF CLASSIFICATION. The scientific names of plants are all Latin or Latinized ; and that of the species always follows that of the genus. 711. Generic names in botany are derived from various sources. Those of plants known to the ancients generally preserve their clas- sical appellations ; as, for example, Quercus, Fagus, Corylus, Prunus, Myrtus, Viola, &c. For plants since made known, even their barba- rous names are often adopted, when susceptible of a Latin termina- tion, and not too uncouth; for example, Thea and Coffea, for the Tea and Coffee plants, Bambusa for the Bamboo, Yucca, Negundo, &c. But more commonly, new generic names, when wanted, have been framed by botanists to express some botanical character, habit, or obvious peculiarity of the plants they designate; such as Arena- ria, for a plant which grows in sandy places; Dentarta, for a plant with toothed roots; Zunaria, for one with moon-like pods; Sanguinaria, for the Bloodroot with its sanguine juice ; Crassula, for some plants with remarkably thick leaves. These are instances of Latin derivatives; but recourse is more commonly had to the Greek language, in which compounds of two words are much more readily made, expressive of peculiarities ; such as Menispermum, or Moonseed ; Lithospermum, for a plant with stony seeds ; Aelanthium, for a genus whose flowers turn black or dusky; Hpidendrum, for certain Orchideous plants which grow upon trees; Liriodendron, for a tree which bears lily-shaped flowers, &c. Genera are also dedicated to distinguished persons; a practice commenced by the ancients ; as Peonia, which bears the name of Pzeon, who is said to have employed the plant in medicine ; and Euphorbia, Artemisia, and Asclepias are also examples of the kind. Modern names of this kind are freely given in commemoration of botanists, or of persons who have contributed to the advancement of natural history. Mag- nolia, Bignonta, Lobelia, and Lonicera, dedicated to Magnol, Big- non, Lobel, and Lonicer, are early instances; Linnea, Tournefortia, Jussiea, Hallerta, and Gronovia, bear the names of the most cel- ebrated botanists of the eighteenth century; and at the present day almost every devotee of the science is thus commemorated. 712. Specific names are adjuncts, and mostly adjectives, adopted on similar principles. Most of them are expressive of some char- acteristic or obvious irait of the species ; as, Magnolia grandiflora, the Large-flowered Magnolia; J/ macrophylla, the Large-leaved Magnolia; Jf glauca, which has the foliage glaucous or whitened underneath ; or Viola tricolor, from the three-colored corolla of the NATURAL AND ARTIFICIAL ‘SYSTEMS. 865 Pansy ; V. rostrata, a remarkably long-spurred species; V. rotundt- folia, with rounded leaves; V. lanceolata, with lanceolate leaves ; V. pedata, with pedately parted leaves; V. primulefolia, where the leaves are compared to those of the Primrose; and V. pubescens, with pubescent or hairy herbage. Sometimes the specific name re- fers to the country which the plant inhabits or was first found in, as Viola Canadensis, the Canadian Violet; or to the station where it naturally grows, as V. palustris (Marsh Violet). Sometimes it com- memorates the discoverer or describer, when it rightly takes the genitive form, as Viola Muhlenbergii, V. Nuttallii, &c. When com- memorative names are given merely in compliment to a botanist un- connected with the discovery or history of the plant, the adjective form is preferred; as, Carex Torreyana, C. Hookeriana, &c.: but this rule is not universally followed. Specific names are sometimes substantive ; ‘as, Magnolia Umbrella, Ranunculus Flammula, Hypericum Sarothra, Linaria Cymbalaria, &e. (most of these being old generic names used as specific); when they do not necessarily accord with the genus in gender. These, as well as all specific names taken from persons or countries, are to be written with a capital initial letter. 713. Varieties may be designated by names when they are re- markable enough to require it. The name of the variety, when used at all, follows that of the species, and is formed on the same plan. Subgenera need to be designated by names, which are sub- stantive, and on the same principle as generic names. These are convenient to refer to, but are not a part of the proper name of a plant, which is that of the genus and species only. 714. The names of genera and species are the same in all botani- cal systems, and therefore are properly alluded to here. But those of orders, and all other groups higher than genera, vary in, plan with the system adopted. Classifications are of two sorts, viz. 715. Natural and Artificial Systems. A natural system carries out in practice as perfectly as possible the principles sketched in this chapter, arranging all known species in groups of various grades in view of their whole plan of structure, so placing each genus, tribe, order, &c. next to those it most resembles in all respects. An arti- ficial system arranges the genera by some one character, or set of characters, chosen for convenience, disregarding other considerations.. It aims only to provide an easy mode of ascertaining the names of plants, and does not attempt to express their points of resemblance generally, but serves nearly the same purpose as a dictionary. 31* 866 THE PRINCIPLES OF 716. Artificial systems are no longer used in botany, except as keys or helps in referring plants to their proper groups in natural arrangements. But the celebrated Artificial System of Linnzus so long prevailed, and has exerted so great an influence over the progress of the science, that it is still desirable for the student to understand it. It will therefore be explained, after we have illus- trated the principles of the Natural System of Botany. CHAPTER ITI. OF THE NATURAL SYSTEM OF BOTANY. 717. Tue object proposed by the Natural System of Botany is to bring together into groups those plants which most nearly resem- ble each other, not in a single and perhaps relatively unimportant point (as in an artificial classification), but in all essential particu- lars; and to combine the subordinate groups into successively more comprehensive natural assemblages, so as to embrace the whole vegetable kingdom in a methodical arrangement. All the charac- ters which plants present, that is, all their points of agreement or difference, are employed in the classification ; those which are com- mon to the greatest number of plants being used for the primary grand divisions ; those less comprehensive, for subordinate groups, &c.; so that the character, or description of each group, when fully given, actually expresses the main particulars in which the plants it embrgces agree among themselves, and differ from other groups of the same rank. This complete analysis being carried through the system, from the primary divisions down to the species, it is evident that the study of a single plant of each group will give a correct general idea of the structure, habits, and even the sensible proper- ties, of the whole. 718. For it is evident that the relationships of plants are real; that there is not only a general plan of vegetation (with which the student has already become familiar), but also a plan in the relations which subsist between one plant and another; that the species sustain to each other the relation of parts to a whole, — so that this whole, or vegetable kingdom, is an organized system. And this system, as THE NATURAL SYSTEM OF CLASSIFICATION. 367 far as comprehended, may be to a good degree expressed in our classification. This idea of plan and system in nature supposes a Planner, or a mind which has ordered things so, with intelligence and purpose; and it is this plan, or its evidences and results, which the naturalist is endeavoring to investigate. The botanist, accordingly, does not undertake to contrive a system, but he strives to express in a classification, as well as he can, the System of Nature, or, in other words, the Plan of the Creator in the Vegetable Kingdom. 719. “So there can be only one natural system of botany, if by the term we mean the plan according to which the vegetable crea- tion was called into being, with all its grades and diversities among the species, as well of past as of the present time. But there may be many natural systems, if we mean the attempts of men to inter- pret and express the plan of the vegetable creation, — systems which will vary with our advancing knowledge, and with the judg- ment and skill of different botanists, — and which must all be very imperfect. They will all bear the impress of individual minds, and be shaped by the current philosophy of the age. But the endeavor always is to make the classification a reflection of Nature, as far as any system can be which has to express such a vast and ever in- creasing array of facts, and most various and intricate relations, in a series of definite propositions, and have its divisions and subdi- visions following each other in some fixed order.” Our so-called natural methods must always fail to give more than an imperfect and considerably distorted reflection, not merely of the plan of the vegetable kingdom, but even of our knowledge of it; and every form of it yet devised, or likely to be, is more or less artificial, in some of its parts or details. This is inevitable, because, — 720. (1st.) The relationships of any group cannot always be, right- ly estimated before all its members are known, and their whole structure understood ; so that the views of botanists are liable to be modified with the discoveries of every year. The discovery of a single plant, or of a point of structure before misunderstood, has sometimes changed materially the position of a considerable group in the system, and minor alterations are continually made by our in- creasing knowledge. (2d.) The groups which we recognize, and dis- tinguish as genera, tribes, orders, &c., are not always, and perhaps not generally, completely circumscribed in nature, as we are obliged to assume them to be in our classification. This might be expected from the nature of the case. For the naturalist’s groups, of what- 368 THE PRINCIPLES OF ever grade, are not realities, but ¢deas ; their consideration involves questions, not of things, between which absolute distinctions might be drawn, but of degrees of resemblance, which may be expected to present infinite gradations. (8d.) Although the grades of affinity among species are most various, if not wholly indefinite, the nat- uralist reduces them all to a few, and treats his genera, tribes, &e. as equal units, or as distinguished by characters of about equal value throughout, — which is far from being the case. (4th.) The nat- uralist in his works is obliged to arrange the groups he recognizes in a lineal series ; but each genus, or order, &c. is very often about equally related to three or four others; so that only a part of the relationship of plants can practically be indicated in the published arrangement. 721. The natural system as sketched by Bernard and A. L. Jus- sieu, and improved by the labors of succeeding botanists, essentially consists of an arrangement of the known genera according to their af- finities under two hundred or more natural orders, and of these under a few great types or classes. What is now most wanted to complete the system is a truly natural arrangement of the orders under the great classes, like that of the genera under their respective orders. Until this is done, the series in which the orders follow one another in botanical works must. not be regarded as a part of the system of nature. Different authors adopt different modes of arranging them; and all of them that a learner could use are avowedly more or less artificial. 722. Omitting all historical details and statements of more or less conflicting views, we will briefly sketch the outlines of the principal divisions of the vegetable kingdom, according to the natural system as we now practically receive it. In explaining the principles of classification, we proceeded from the individual to the class. In ex- amining the actual construction of the system of botany, it is simpler to regard the vegetable kingdom as a whole, and show how it is nat- urally divided and subdivided. This is the course a student must follow with an unknown plant before him, which he wishes to refer first to its class, then to its order, and finally to its genus and species. 723. The long and complex series, stretching from the highest organized vegetable down to the simplest and minutest of the Fungi .and Algz, is most naturally divided, as we have already seen, into two parts, forming a higher and a lower grade or series (98), viz. THE NATURAL SYSTEM OF CLASSIFICATION. 369 Series J. Puanocamovus (or Phanerogamous) or FLoOwER- ING Prants (114, 117), which produce flowers and seeds, the latter containing a ready-formed embryo. Series I. Cryprogamous or FLrowerirss Prants (118, 117, 651), whose organs of reproduction are not flowers, but some more or less analogous apparatus, and which are propagated by spores or specialized cells. 724, We have next to consider how these two series may be themselves divided, in view of the most general and important points of difference which the plants they comprise exhibit. Whenever Phznogamous plants rise to arborescent forms, a difference in port and aspect at once arrests attention; that which distinguishes our common trees and shrubs from Palms and the like (Fig. 184). On examination, this is found to accompany a well-marked important difference in the structure of the stem or wood, and in its mode of growth. The former present the exogenous, the latter the endoge- nous structure or growth (200 — 203, 207, &c.). This difference is equally discernible, if not so striking, in the annual or herbaceous stems of these two sorts of Phenogamous plants. A difference is also apparent in their foliage; the former generally have reticulat- ed, or netted-veined, the latter parallel-veined leaves (276). The leaves of the former usually fall off by an articulation; those of the latter decay on the stem (309, 310). The Phanogamous series, therefore, divides into two great classes, namely, into Exogenous and ExpOGENovs plants, more briefly named Exocens and Enpo- crens. The difference between the two not only pervades their whole port and aspect, but is manifest from the earliest stage, in the plan of the embryo. The embryo of Exogens, as already shown, is provided with a pair of cotyledons (or sometimes with more than one pair) ; that of Endogens, with only one; whence the former are also termed DicotyLeponovs, and the latter MonocoryLepo- nous plants (128, 641-643): names introduced by Jussieu, the father. of this branch of botany.* Taking these divisions for classes, we have * There is, perhaps, no real and complete exception to the coincidence of an exogenous stem with a dicotyledonous (or polycotyledonous) embryo, and of an endogenous stem with w monocotyledonous embryo. Nyctaginaceous plants and some others have a few vascular bundles scattered through their pith, but the rest of the wood is regularly exogenous. The stalk of Podophyllum imi- tates an Endogen, but the subterranean rootstock is truly exogenous, as it should 370 THE PRINCIPLES OF Class I. Exogenous or DicotyLeponous PLants; those with endogenous stems, netted-veined leaves, and dicotyledonous (or rarely polycotyledonous) embryo; Class 1. Enpocrenovus or MonocotyLeponous Pants; those with endogenous stems, mostly parallel-veined leaves, and monocotyledonous embryo. 725. Without entering here into a particular explanation of the diversities of structure which Cryptogamous plants present, suffice it to say that they exhibit three grades of simplification as to their vegetation, which appear to correspond with three different modes of fertilization. Plants of the highest grades of the Cryptogamous series have wood and ducts in their composition (i. e. they are vascu- lar plants, 111), and display the ordinary type of vegetation, viz. with an axis or stem, bearing distinct foliage. But this stem in structure is neither endogenous nor exogenous, and grows from the apex only, having no primary root ; whence these vascular Flower- less plants have been called AcroGENS, or ACROGENOUS plants. Of this kind are Ferns, Lycopodiacex, Equisetacee or Horsetails, &c. These plants, it appears, produce their organs analogous to flowers, and have their fecundation effected, once for all, upon the infantile or germinating plantlet, and the result is the origination of a bud, which develops into the adult plant; and that bears the fruit, in the form of spore-cases and spores (663). Here then are the characters of Class IJ. Acrocenous Prants; Cryptogamous plants, with a distinct axis and mostly with foliage, having wood and ducts in their composition: fertilization occurring upon a transient germinat- ing plantlet, and giving rise to the adult plant. 726. The other Cryptogamous plants, being composed of paren- chyma only, (or with slight exceptions,) are called Cellular plants (111). Among them the Mosses and Liverworts present for the most part the ordinary plan of vegetation ; their organs analogous to flowers appear in the adult plant; and the fertilization of the pistillidium gives origin to a sporangium in which a multitude of spores, capable of germination, are developed. These compose Class IV. Anopuytes: cellular Cryptogamous plants, with distinct stem and foliage, or sometimes these parts confluent into a be. The trunks or rootstocks of Water-Lilies appear to be endogenous ; but those who have investigated them minutely, declare that they are not really so. THE NATURAL SYSTEM OF CLASSIFICATION. ‘371 frond, composed of parenchyma alone: fertilization giving rise to a sporangium filled with spores. 727. The remaining and lower grade consists of plants such as Lichens, Seaweeds or Algw, and Fungi, which exhibit no clear dis- tinction into stem, root, and leaves, but consist of single cells or rows of cells in their lowest grades, and in the higher, of masses of cells disposed in almost every shape, but tending mostly to flat strata or expansions ; hence the vegetation is termed a thallus (or bed), and this word gives a name to the class, viz. Class V. TuHaLLopuytes: cellular Cryptogamous plants with no distinction of axis and foliage; their spores mostly directly fer- tilized (as explained in another place, 656-661). 728. These five classes are unequal in extent and diversity; the Exogenous class containing much the largest number of orders ; the Endogens also comprising a considerable number ; the others com- prise few orders or main types, but are most of them very rich in tribes, genera, and species. 729. Only the first or highest class presents such marked diver- sity of type among the plants it comprises as to call for the estab- lishment of subclasses, that is, of groups of such importance as to raise the question whether they should not be regarded as classes. This question is raised by the peculiarities of Coniferse (Pines, Cy- presses, the Yew, &c.), and by the tropical order of Cycadacez ; in which, not only are the flowers reduced to the greatest simplicity, but the fertile ones consist of naked ovules merely, borne on the ‘margins or surface of a sort of open leaf, or else of an ovule, without anything answering to a pistil at all. But as these plants are truly exogenous and dicotyledonous (or often polycotyledonous), the better opinion is that they should be ranked under the Exogenous or Dicotyledonous class, as a subclass. So that, while the main body of the first class consists of = Subclass I. AnGiosprrmous Exoerns: viz. those with proper pistils enclosing their ovules in an ovary, in the ordinary manner ; the pollen to fertilize the ovules received upon a stigma (420, 559, 574), — the others form the Subclass II. Gymnospermous Exocens: those with naked ovules and seeds (as the name denotes), which are fertilized by direct application of the pollen (560, 573, 625). 730. The general plan of the classes and subclasses may be pre- sented in one view, as in the subjoined synopsis. THE NATURAL CLASSES. 372 ‘SHLAHAOTIVHL “A » ‘snqTeq} B UL pepunoyuod Te nq ‘aBerpoy pUB Td}s Jo WOTOUHS!P Om ) WA ‘SLNVTd SQOWVDOLAAND “I “7S “SHLAHGONY ‘AI > *£[dO ansst} TeNT[99 ' Zuyuyeynoo ‘eSeyoy pue wia}s Jo ‘stxe youNsIp e VSNADOUOV ‘IIL sstIQ ‘onssi} 2enosea pas Apooas im > ais of the Cabbage and Cauliflower. None are really poisonous plants, although some are yery‘acrid. Several species are in FIG, 696 A Cruciferous flower. 697. The same, with the calyx and corolla removed, show- ing the tetradynamous stamens. 698. Siligues of Arabis Canadensis; one of them with one of the valves detached. showing the seeds lying on the false partition ; the other valve also falling away. 699. A magnified cross-section of one of the winged seeds, showing the embryo with the radicle applied to the edge of the cotyledons (cotyledons accumbent). "700 The embryo detached. 701. The raceme of Draba verna, in fruit. 702. A cross-section of one of the sili- cles, magnified, exhibiting the parietal insertion of the seeds, and the false partition 705. A Rilicle of Shepherd’s Purse (Capsella Bursa Pastoris). 704 The same, with one of the boat- shaped valves removed, presenting a longitudinal view of the narrow partition, &c. 705. A magnified cross-section of one of the seeds, showing the embryo with the radicle applied to the side of the cotyledon (cotyledons incumbent). EXOGENOUS OR DICOTYLEDONOUS PLANTS. 391 cultivation, for their beauty or fragrance; such as the Wall-flower, Stock, &e. 754. Ord, Capparidaces (Caper Family). Terbs, or in the tropics often shrubs or trees; differing from Cruciferz in the one-celled pod (which is often stalked) being destitute of any false partition; in the kidney-shaped seeds; and in the stamens, which, when six, are scarcely tetradynamous, and are often more numerous. — Fz. Cle- ome, Polanisia, Gynandropsis; chiefly tropical or subtropical. Many have the pungency of Cruciferz, but are more acrid. Capers are the pickled flower-buds of Capparis spinosa of the Levant, &c. The roots and herbage or bark are bitter, nauseous, and sometimes poisonous. 755. Ord. Resedacew (Mignonette Family). Herbs, with a watery juice, and alternate leaves without stipules, except a pair of glands be so considered: the flowers in terminal racemes, small, and often fragrant.— Calyx persistent, of four to seven sepals, somewhat united at the base. Corolla of two to seven usually unequal and lacerated petals, with broad or thickened claws (Fig. 877). A fleshy disk is commonly present, enlarged posteriorly between the petals and the stamens, and bearing the latter, which vary from three to forty in number, and are not covered by the petals and sepals in the bud. Fruit a one-celled pod, with three to six parietal placentz, three to six-lobed at the apex, where it opens along the FIG. 706. Flower of Gynandropsis. 707. Flower of Polanisia graveolens. 708. Fructified ovary of the same, a portion cut away by a vertical and horizontal section, to show the single cell and two parietal pl ft 709, Cross-section of the ovary. 710. Section of the seed and embryo. 392 ILLUSTRATIONS OF THE NATURAL ORDERS. inner sutures, usually long before the seeds are ripe. Seeds several or many, curved or kidney-shaped, with no albumen; the embryo incurved. — Hx. The common representatives of this order are the Mignonette (Reseda odorata), prized for its fragrant flowers, and the Weld (R. Luteola), which yields a poor dye. 756. Ord, Flacourtiacer, a group of tropical shrubs and trees, placed in this vicinity, is best known by Bixa Orellana, which yields Arnatto, the orange-red dried pulp of the pod, surrounding the seeds. 757. Ord. Violacew (Violet Family). Tlerbs (in tropical countries sometimes shrubby plants), with mostly alternate simple leaves, on petioles, furnished with stipules; and irregular flowers (Fig. 396, 397). Calyx of five persistent sepals, often auricled at the base. Corolla of five unequal petals, one of them larger than the others and commonly bearing a spur or a sac at the base: zstivation imbri- EPG 112% aL 712 cative. Stamens five, with short and broad filaments, which are usually elongated beyond the (adnate introrse) anthers; two of them commonly bearing a gland or a slender appendage which is concealed in the spur of the corolla: the anthers approaching each other, or united in a ring or tube. Style usually turned to one side FIG. T1l. Viola sagittata, 712. One of the stamens without appendage, seen from within ; and one furnished with a spur-like appendage on the back. 112%. A capsule which has opened and separated into three valves; the calyx still persistent. 712”. A vertical section of the seed and embryo. EXOGENOUS OR DICOTYLEDONOUS PLANTS. 893 and thickened at the apex. Fruit a one-celled capsule, opening by three valves, each bearing a parictal placenta on its middle. Seeds several or numerous, anatropous, with a crustaceous integument, and a straight embryo, nearly the length of the fleshy albumen (Fig. 604, 605).— Ex. The Violet is the principal genus of this order; some species, like the Pansy, are cultivated for the beauty of their flow- ers; others, for their delicate fragrance. The roots of all are acrid, and emetic. Those of some South American species of Ionidium furnish a part of the Zpecacuanha of commerce. 758. Ord. Cistaces (Rock-Rose Family). Low shrubby plants or herbs, with simple and entire leaves (at least the lower opposite). Calyx of five persistent sepals; the three inner with a convolute zestivation ; the two outer small or sometimes wanting. Corolla of five, or rarely three, regular petals, convolute in estivation in the direction contrary to that of the sepals, often crumpled, usually ephemeral, sometimes wanting, at least a portion of the flowers. Stamens few or numerous, distinct, with short innate anthers. Fruit 719 a one-celled capsule with parictal placenta, or imperfectly three to five-celled by dissepiments arising from the middle of the valves (dehiscence therefore loculicidal), and bearing the placentz at or near the axis. Seeds few or numerous, mostly orthotropous, with mealy FIG. 713. The Rock-Rose, Helianthemum Canadense. 714. Flower from which the petals and stamens have fallen. -715 Magnified cross-section of the ovary; with a single stamen, showing its hypogynous insertion. 716 Cross-section of a capsule, loculicidally debiscent ; the seeds therefore borne on the middle of each valve. 717. An ovule. 718 Plan of the flower. 719. Section of a seed, showing the curved embryo. 394 ILLUSTRATIONS OF THE NATURAL ORDERS. albumen. Embryo curved, or variously coiled or bent. — Zz. Cistus, Helianthemum : a small family ; the flowers often showy. No im- portant properties. Several exude a balsamic resin, such as Lada- num from a Cistus of the Levant. 759. Ord. Droseracew (Sundew Family). Small herbs, growing in swamps, usually covered with gland-bearing hairs; with the leaves rolled up from the apex to the base in vernation (circinnate) : stip- ules none, except a fringe of hairs or bristles at the base of the petioles. Calyx of five equal sepals, persistent. Corolla of five regular petals, withering and persistent, convolute in estivation. Stamens as many as the petals and alternate with them, or some- times two or three times as many, distinct, withering; anthers ex- trorse. Styles three to five, distinct or nearly so, and each two- parted (so as to be taken for ten styles, Fig. 510), and these divis- ions sometimes two-lobed or many-cleft at the apex. Fruit a one- celled capsule, opening loculicidally by three to five valves, with three to five parietal placente; in Dionzea membranaceous, burst- ing irregularly, and with a thick placenta at the base. Seeds usu- ally numerous. Embryo small, at the base of cartilaginous or fleshy albumen. — Hx. Drosera, the Sundew; and Dionza (Venus’s Fly- trap, Fig. 297, 298), so remarkable for its sensitive leaves, which suddenly close when touched. The styles of the latter are all united into one. 760. Ord. Parnassiace® is for the present made for the genus Par- nassia, which was formerly appended to Droseracee (for no good reason), and has since becn placed by some next to Hypericacex, by others referred to Saxifragacew. It is remarkable for having the four or five stigmas situated directly over the parietal placents (p. 294, note), and for the curious appendages resembling sterile sta- mens before each petal (Fig. 880, 381). 761. Ord. Hypericacer (St. Johnswort Family). Shrubs or herbs, with a resinous or limpid juice, and opposite entire leaves, destitute of stipules, and punctate with pellucid or blackish dots. Flowers regular. Calyx of four or five persistent sepals, the two exterior often smaller. Petals four or five, convolute in xstivation, often beset with black dots. Stamens commonly polyadelphous and numer- ous. Ovary one-celled with parietal placenta, or 4—-5-celled (Fig. 375, 497, 498, 508, 509). Capsule with septicidal dehiscence (Fig. 582), many-seeded. — Hx. Hypericum (St. Johnswort) is the type of this small family. Embryo straight; albumen little or none. EXOGENOUS OR DICOTYLEDONOUS PLANTS. 3895 The plants yield a resinous acrid juice, and a bitter, balsamic ex- tractive matter. 721 720 762. Ord, Elatinacee (Waterwort Family). Small annual weeds with membranaceous stipules between the opposite leaves, and mi- nute axillary flowers. Sepals and petals three to five. Stamens as many or twice as many as the petals, distinct. Capsule 2 — 5-celled, septicidal or septifragal; the numerous seeds attached to a persist- ent central axis. Albumen none. — Zz. Elatine is the type of this order, containing a few insignificant weeds. 763. Ord. Caryophyllacee (Pink Family). Herbs, with opposite entire leaves; the stems tumid at the nodes. Flowers regular. Calyx of four or five sepals. Corolla of four or five petals, or sometimes wanting. Stamens as many, or commonly twice as many, as the petals, sometimes reduced to two or three. Styles two to five, stigmatose down the inside. Ovary mostly one-celled, with a central or basilar placenta, forming a pod in fruit. -Embryo periph- eric, curved or coiled around the outside of mealy albumen (Fig. 620, 621, 726). — There are five principal suborders, viz. : — 764. Subord. Silene (Pink Family proper) ; in which the sepals are united into a tube, and the petals (mostly convolute in zstiva- tion) and stamens are inserted on the stipe of the ovary, the former with long claws (Fig. 482, 449), and there are no stipules. — Ez. Silene, Dianthus (Pink, Carnation). 7605. Subord. Alsinew (Chickweed Family); in which there are no FIG. 120. ILypericum perforatum (St Jobnswort). 721. Its tricarpellary pistil. 722. Cross-section of the capsule. 723. Vertical section of a seed and iis enibr, 0. 396 ILLUSTRATIONS OF THE NATURAL ORDERS. stipules, the ovary is sessile, the sepals and petals (imbricated in wstivation) are nearly or quite distinct ; the petals destitute of claws ; and the stamens are inserted into the margin of a small hypogynous disk, which, however, occasionally coheres with the base of the calyx, and becomes perigynous. — Zz. Stellaria, Arenaria, &c. (Chick- weeds). Some are ornamental ; others, such as the common Chickweed, are in- significant weeds. 766. Subord. Ille- cebrete = (Anotwort Family); differing from the last main- ly in. having sca- rious stipules ; the sepals often united below ; the petals fe= often wanting or ru- (@) dimentary ; the sta- : mens manifestly pe- rigynous ; and the Te 728 es fruit more commonly a one-seeded utricle — #x. Paronychia and Anychia. Spergula has conspicuous petals, and many-seeded capsules; and so differs from Alsinee only in its stipules. Insignificant weeds. 767. Subord. Scleranthee (Anewel Family) is like the last, only there are no stipules. — “x. Scleranthus. 768. Subord. Molluginew (Carpet-weed Family) is apetalous with- out stipules, and has the stamens alternate with the sepals when of the same number ; thus effecting a transition to 769. Ord. Portulacacer (Purslane Family). Succulent or fleshy herbs, with entire exstipulate leaves and usually ephemeral flowers. Calyx mostly of two or three sepals, sometimes cohering with the base of the ovary. Petals five, or rarely more numerous, sometimes none. Stamens variable in number, but when equal to the petals situated opposite them. Styles two to eight, united below. Capsule FIG. 724. Moehringia lateriflora. 725 A magnified flower. 726. Magnified section of a seed, showing the embryo coiled into a ring around the albumen. 727. Vertical section ofa pistil of Spergularia. EXOGENOUS OR DICOTYLEDONOUS PLANTS. 397 with few or numerous seeds, attached to a central basilar placenta, often by slender funiculi. Seed and embryo as in Caryophyllacex. — x. Portulaca (Purslane, Fig. 389, 588) Claytonia. Chiefly natives of dry places in the warmer parts of the world; except Claytonia. Insipid or slightly bitter: several are pot-herbs, as the Purslane. Some are ornamental. The farinaceous root of Lewisia 730 736 rediviva, a native of the dry interior plains of Oregon, is an impor- tant article of food with the natives. 770. Ord. Mesembryanthemacce (fig-Marigold Family) consists of succulent plants, with showy flowers opening only under bright sun- shine, containing an indefinite number of petals and stamens, and a many-celled and many-seeded capsule: otherwise much as in Caryo- phyllacee. — Hx. Mesembryanthemum (Fig-Marigold, Ice-plant) ; chiefly natives of the Cape of Good Hope, flourishing in the most arid situations. 771. Ord. Malvacee (Mallow Family). Herbs, shrubs, or rarely trees. Leaves alternate, palmately veined, with stipules. Flowers ‘regular, often with an involucel, forming a double calyx. Calyx mostly of five sepals, more or less united at the base, valvate in FIG. 728. Flower of the Purslane; the calyx cut away at the point where it adheres to the ovary, and Jaid open. 729. A capsule (pyxis) of the same, transversely dehiscent. 730. Clay- tonia Virginica (Spring-Beauty). 731. Diagram of the flower. 732. Young fruit and the per- sistent two-leaved calyx. 788. Section of the dehiscing capsule. 734. A seed. 735. The same, vertically divided. 786. The embryo, detached. 34 398 ILLUSTRATIONS OF THE NATURAL ORDERS. zstivation. Petals as many as the sepals, convolute in wstivation, hypogynous. Stamens indefinite, monadelphous, united with the claws of the petals: anthers reniform, confluently one-celled. Pollen hispid (Fig. 483). Ovary several-celled, with the placente in the axis; or ovaries several. Fruit capsular, or the carpels separate or separable. Seeds with a little mucilaginous or fleshy albumen. Embryo large, with foliaceous cotyledons, variously incurved or folded. — Ex. Malva (Mallow), Althea (Hollyhock), Gossypium (Cotton), &c.: a rather large and important family, the herbage, .&c. commonly abounding in mucilage, and entirely destitute of un- wholesome qualities. The unripe fruit of Abelmoschus or Hibiscus esculentus (Okra) is used in soups. Althzea officinalis is the Marsh Mallow of Europe, the Guimauve of the French. The tenacious inner bark of many species is employed for cordage. Cotton is the hairy covering of the seeds of Gossypium: the long and slender tubes, or attenuated cells, collapse and twist as the seed ripens, which renders the substance capable of being spun. Cotton-seed yields a good fixed oil. Some species are cultivated for ornament. 772. Ord. Byttneriacee is distinguished from the foregoing by its usually definite stamens, and the two-celled anthers (the cells par- allel), with smooth pollen. — A Melochia and a Hermannia are found in Texas. The rest of the order is tropical or subtropical. Chocolate is made of the roasted and comminuted seeds of Theo- broma Cacao (a South American tree), mixed with sugar, arnotto, vanilla, and other ingredients. The roasted integuments of the seeds, also, are used as a substitute for coffee. FIG. 7387. The Marsh Mallow (Althzea officinalis). 738. One of the kidney-shaped one-celled anthers, magnified. 7389. The pistils, magnified. 440. Capsule of Ilibiscus Moscheutos, with the persistent calyx and involucel. 741. The same, loculicidally dehiscent. EXOGENOUS OR DICOTYLEDONOUS PLANTS. 399 7738. Ord. Sterculiacer, very closely allied to the last two, and con- sisting of tropical trees, possesses the same mucilaginous properties (as well as oily seeds), with which bitter and astringent qualities are often combined. The seeds of Bombax, the Silk-cotton tree, are enveloped in a kind of cotton, which belongs to the endocarp and not to the seed ; and the hairs, being perfectly smooth and even, can- not be spun. Canoes are made from the trunk of the huge Bombax Ceiba, in the West Indies. To this order belongs the famous Baobab, or Monkey-bread, of Senegal (Adansonia digitata), some trunks of which are from sixty to eighty feet in circumference! The fruit resembles a gourd, and serves for vessels; it contains a subacid and refrigerant, somewhat astringent pulp; the mucilagi- nous young leaves are also used for food in time of scarcity; the dried leaves (Zalo) are ordinarily mixed with food, and the bark furnishes a coarse thread, which is made into cordage or woven into cloth. Cheirostemon platanoides is the remarkable Hand-flower tree of Mexico. A plant of the family (Fremontia, Zorr.) nearly allied to Cheirostemon has been found in California, by Fremont. 774. Ord. Tiliacee (Linden Family). Trees or shrubby plants, with alternate leaves, furnished with deciduous stipules, and small flowers. Calyx deciduous. Petals sometimes imbricated in estiva- FIG. 742. Flowering branch of Tilia Americana, the common American Linden ; the flower- stalk cohering with the bract. 748. One of the clusters of stamens adhering to the petaloid scale, 744. The pistil. 745. Cross-section of the fruit, which has become one-celled by the obliteration of the partitions, and one-seeded. 746 Vertical section of the seed, magnified, to show the large embryo with its taper radicle and foliaceous crumpled cotyledons. (A better section of the seed, cut in the direction across the cotyledons, is shown in Fig. 599.) 1747. Diagram of the flower. 400 ILLUSTRATIONS OF THE NATURAL ORDERS. tion. Stamens indefinite, often in three to five clusters, distinct or somewhat united, one of each parcel often transformed into a peta- loid scale (Fig. 883, 743): anthers two-celled. Styles united into one. Fruit two to five-celled, or, by obliteration, one-celled when ripe. In other respects nearly as in Malvacee. — Tilia, the Linden, or Lime-Tree, represents the order in northern temperate regions ; the other genera are tropical. All are mucilaginous, with a tough fibrous inner bark. From this bast or bass of the Linden, the Rus- sian mats, &c. are made, whence the name of Basswood. Gunny- bags and fishing-nets are made in India from the bark of Corchorus capsularis ; the fibre of which, called Jute, is spun and woven. The light wood of the Linden is excellent for wainscoting and carv- ing: its charcoal is used for the manufacture of gunpowder. It is said that a little sugar may be obtained from the sap: and the honey made from the odorous flowers is thought to be the finest in the world. The acid berries of Grewia sapida are employed in the East in the manufacture of sherbet. 775. Ord. Dipterocarpee, allied in some respects to Tiliacew, con- sists of a few tropical Indian trees, with a resinous or balsamic juice. Dryobalanops aromatica, a large tree of Sumatra and Borneo, yields in great abundance camphor oil and solid camphor : both are found deposited in cavities of the trunk. It is more solid than common camphor, and is not volatile at ordinary temperatures. It bears a high price, and is seldom found in Europe or this country, but is chiefly carried to China and Japan. Shorea robusta yields the Dammer-pitch. Vateria Indica exudes a kind of copal, the Gum Animi of commerce; and a somewhat aromatic fatty matter, called Piney Tallow, is derived from the seeds. 776. Ord, Guttifere, or Clusiace®, consists of tropical trees, with a yellow resinous juice, opposite and coriaceous entire leaves, and large flowers with many stamens, little distinction between the sepals and petals, no styles, an indehiscent fruit, and seeds with a peculiar undivided fleshy embryo. It has been associated with Hy- pericacex, but is more related to the ensuing families. The resin- ous juice is acrid and drastic ; that of a Ceylonese tree of the order yields Gamboge. It is remarkable that such an order should pro- duce one of the most esteemed fruits, viz. the Mangosteen, yielded by Garcinia Mangostana of Malacca, and also the Mammee-apple, &c. 777. Ord. Camelliacee (Camellia or Tea Family). Trees or shrubs, with a watery juice, alternate simple leaves without stipules, and EXOGENOUS OR DICOTYLEDONOUS PLANTS. 401 large and showy flowers. Calyx of three to seven coriaceous and concave imbricated sepals. Petals five or more, imbricated in esti- vation. Stamens hypogynous, indefinite, monadelphous or polyadel- phous at the base. Capsule dehiscent, several-celled, usually with a central column. Seeds few in each cell, large, often winged, with’ or without albumen.— The Camellia and the closely related Tea- plant form the type of this family, to which belong our Gordonia and Stuartia. The leaves of Zea contain a peculiar extractive mat- ter, and an ethereal oil; its moderately stimulant properties are said to become narcotic in very hot climates. 778. Ord. Ternstremiace®, chiefly tropical, with which the last has been confounded, by its aspect, its commonly polygamous flowers, and more or less gamopetalous corolla, &c., appears on the whole to be more allied to the Ebenacezw and Symplocinez. 779. Ord. Aurantiacees (Orange Family). Trees or shrubs, with alternate leaves (compound, or with jointed petioles), destitute of stipules, dotted with pellucid glands full of volatile oil. Flowers fragrant. Calyx short, urceolate or campanulate. Petals three to five. Stamens inserted in a single row upon a hypogynous disk (Fig. 484), often somewhat monadelphous or polyadelphous. Style cylindrical. Fruit a many-celled berry, with a leathery rind, filled with pulp. Seeds without albumen. — Fz. Citrus, the Orange and Lemon. Nearly all natives of tropical Asia; now dispersed through- out the warmer regions of the world, and cultivated for their beauty and fragrance, and for their grateful fruit. The acid of the Lemon, Lime, &c. is the citric and the malic. The rind abounds in a vola- tile oil (such as the Owl of Bergamot from C. Limetta), and an aro- matic, bitter principle. 780. Ord, Meliacee, ‘Trees or shrubs, with alternate, usually com- pound leaves, destitute of stipules. Calyx of three to five sepals. Petals three to five. Stamens twice as many as the petals, mona- delphous, inserted with the petals on the outside of an hypogynous disk ; the anthers included in the tube of filaments. Ovary several- celled, with one or two ovules in each cell: styles and stigmas united into one. Fruit a drupe, berry, or capsule; the cells one-seeded. Seeds without albumen, wingless. — Hx. Melia Azedarach (Pride of India), naturalized, as an ornamental tree, in the Southern States. An acrid and bitter principle pervades this tropical order. 781. Ord. Cedrelaces (Mahogany Family). Trees (tropical or Australian), with hard and durable, usually fragrant and beautiful 34* 402 ILLUSTRATIONS OF THE NATURAL ORDERS. wood ; differing botanically from Meliacex chiefly by their capsular fruit, with several winged seeds in each cell.— Hx. The Mahogany (Swietenia Mahagoni) of tropical America, reaching to East Flor- ida. Bark, &e. bitter, astringent, tonic, often aromatic and febrifugal. 782. Ord. Linaceer (lax Family). Nerbs, with entire and sessile leaves, either alternate, opposite, or verticillate, and no stipules, ex- cept minute glands. Flowers regular and symmetrical. Calyx of three or five persistent sepals, strongly imbricated. Petals as many as the sepals, convolute in estivation. Stamens as many. as the petals, and usually with as many intermediate teeth representing an abortive series (Fig. 423), all united at the base into a ring, hypogy- nous. Ovary with as many styles and cells as there are sepals, each cell with two suspended ovules ; the cells in the capsule each more or Jess divided into two, by a false par- aN tition which grows from the back (Fig. 750) ; =\\ the spurious cells @ one-seeded. Em- k< [39 0 bryo straight : o YJ cotyledons flat, == fleshy and oily, surrounded by a thin albumen.— £x. Linum, the Flax. The tough woody fibre of the bark (flax) is of the highest importance: the seeds yield a copious mucilage, and the fixed oil expressed from them is applied 750 to various uses in the arts. The general plan of the flower is the same in the succeeding orders. FIG. 748. Flowers of the common Flax. 749. Vertical section of a flower. 750. Diagram of the same, in a transverse section. 751. Its 10-celled capsule transversely divided. 752. Similar section of the incompletely 10-celled capsule of Linum perenne. EXOGENOUS OR DICOTYLEDONOUS PLANTS. 402 783. Ord. Geraniace (Cranesbill Family). Herbs or shrubby plants, commonly strong-scented ; ‘with palmately veined and usually lobed leaves, mostly with stipules; the lower opposite. Flowers regular. — Calyx of five persistent sepals, imbricated in sstivation. Petals five, with claws, mostly convolute in estivation. Stamens 10, the five exterior hypogynous, occasionally sterile ; the filaments all broad and often united at the base; five glands within and alternate with the petals. Ovary of five two-ovuled carpels, attached to the base of an elongated axis (gynobase, Fig. 480, 481) to which the styles cohere : in fruit the distinct one-seeded carpels separate from the axis, by the twisting or curling back of the persistent indurated 753 754 755 738 styles from the base upwards. Seeds with no albumen: cotyledons convolute and plaited together, bent on the short radicle. For the plan of the blossom see p. 264, and Fig. 421. Our cultivated Geraniums, so called, from the Cape of Good Hope, are species of Pelargonium. The roots are simply and strongly astringent. The foliage abounds with resinous matter and an ethereal oil, on which the aroma depends. 784. Ord. Balsaminacee (Balsam Family). Annual herbs, with succulent stems filled with a watery juice. Leaves simple, without stipules. Flowers irregular, and one of the colored sepals spurred or saccate. Stamens five, cohering by an internal appendage. FIG. 753. Radical leaf of Geranium maculatum (Cranesbill), 754. A flowering branch. 755. A flower with the calyx and corolla removed, showing the stamens, &c. 1756. The pistil in fruit; the indurated styles separating below from the prolonged axis, and curving back ‘elastically, carrying with them the membranous carpels. 757. A magnified seed. 758. A cross-section of the same, showing the folded and convolute cotyledons. 404 ILLUSTRATIONS OF THE NATURAL ORDERS. Compound ovary five-celled; stigmas sessile. Capsule bursting elastically by five valves. Seeds several, without albumen, and with a thick straight embryo. — Hx. Impatiens, the Balsam, or Touch- me-not. Remarkable for the elastic force with which the capsule bursts in pieces, and expels the seeds. Somewhat differently irreg- ular blossoms are presented by the 785. Ord. Tropwolacees (Jndian-Cress or Nasturtium Family). Straggling or twining herbs, with a pungent watery juice, and peltate or palmate leaves. Flowers irregular. Calyx of five colored and united sepals, the lower one spurred. Petals five; the two upper arising from the throat of the calyx, remote from the three lower, which are stalked. Stamens eight, unequal, distinct. Ovary three- lobed, composed of three united carpels; which separate from the common axis when ripe, are indehiscent, and one-seeded. Seed filling the cell, without, albumen: cotyledons very large and thick. — Ex. Tropeolum, the Garden Nasturtium, from South America, where there are a few other species, one of which bears edible tubers. They possess the same acrid principle and antiscorbutic properties as the Crucifere. The unripe fruit of Tropezolum majus is pickled, 7) and used as a substitute for capers. 786. Ord, Limnanthacee differs from the last only in its regular and symmetrical blossoms, and the erect instead of suspended seeds ; the calyx valvate in estivation. — Hx. Limnanthes of California (some- times cultivated as an ornamental annual), and Fleerkea of the Northern United States. 787. Ord. Oxalidacew (Wood-Sorrel Family). Low herbs, with an acid juice, and alternate compound leaves; the leaflets usually ob- cordate. Flowers regular, of the same general structure as in Li- naces, &c., except the gynxcium, which in fruit forms a membra- naceous five-lobed and five-celled, several-seeded capsule. Seeds with a fleshy outer coat, which bursts elastically when ripe, with a large and straight embryo in thin albumen. — Fz. Oxalis, the Wood-Sorrel. The herbage is sour, as the name denotes, and con- tains oxalic acid. The foliage is remarkably sensitive in some spe- cies. The tubers of some South American species, filled with starch, have been substituted for potatoes. 788. Ord. Zygophyllaces differs from the last in the opposite, mostly abruptly pinnate leaves, distinct stamens (the filaments com- monly furnished with an internal scale, Fig. 379), and the styles united into one. — Zz. Tribulus and Kallstreemia (introduced into EXOGENOUS OR DICOTYLEDONOUS PLANTS. 405 the Southern States) are exalbuminous; the latter is 10-coccous, just as Linum is, by a false partition, Guaiacum, Larrea (Creo- sote-plant of New Mexico and Texas), and the rest of the family, have a corneous albumen. The wood of Guaiacum (Lignum-vite) is extremely hard and heavy, and yields a gum-resinous, bitter, and acrid principle (Gum Guatacum), well known in medicine. 789. Ord. Simarubacee (Quassia Family), of tropical shrubs or trees, resembles the last in generally having a peculiar scale to the filaments. It is, however, more nearly related to the next order, but its apocarpous ovaries are one-ovuled, and the (mostly com- pound) leaves are dotless. The wood, &c. is intensely bitter: that of Quassia amara is used as a stomachic tonic. The seed of Cedron (Simaba Cedron) is the famous antidote for the bites of venomous snakes in Central America. 790. Ord. Rutacew (Rue Family). Herbs, shrubs, or trees; the leaves punctate with pellucid dots, and without stipules. Calyx of four or five sepals. Petals four or five, or rarely none. Stamens 761 762 763 766 as many or twice (rarely three times) as many as the petals, insert- FIG. 759. A flowering branch of Zanthoxylum Americanum (the Northern Prickly Ash). 760. A piece of a leaf, to show the pellueid dots. 761. Staminate flower. 762. A pistillate flower, the sepals spread open. 1763. Two of the pistils; one of them divided vertically to show the ovules. 764. A branch in fruit. 765. One of the dehiscent pods, and the seed, 766. Ver- tical section of an unripe pod and seed; the latter pendent from a a ding funiculus, show- ing a slender embryo in copious albumen. 406 ILLUSTRATIONS OF THE NATURAL ORDERS. ed on the outside of a hypogynous disk. Ovary three- to five-lobed, three- to five-celled, with the styles united, or distinct only at the base, or the ovaries nearly separate, during ripening usually sepa- rating into its component carpels, which are dehiscent by one or both sutures. Seeds few or single, mostly with albumen; and a curved embryo.— Lx. Ruta (the Rue), Dictamnus (Fraxinella), of Europe. Diosma and its allies, of the Cape of Good Hope, New Holland, &c., form a group, or suborder (DiosmE«) from which the ZANTHOXYLE (or Prickly-Ash Family) differs only in being gen- erally dicecious ; but have no claim to be ranked as a distinct order. Strong-scented, bitter-aromatic, often very pungent, from an a€rid volatile oil (as Rue and Zanthoxylum) ; also bitter. Some contain a bitter alkaloid, and are febrifugal. The most important is the Galipea, which furnishes the Angostura bark. 791. Ord. Anacardiaceee (Cashew Family). Trees or shrubs, with a resinous or milky, often acrid juice, which turns blackish in dry- ing; the leaves alternate, without stipules, and not dotted. Flowers small, often polygamous or diccious. Calyx of three to five sepals, united at the base. Petals, and usually the stamens, as many as the sepals, inserted into the base of the calyx or into an hypogynous disk. Ovary one-celled, but with three styles or stigmas, and a single ovule. Fruit a berry or drupe. Seed without albumen. Embryo curved or bent. — Hx. Rhus, Anacardium (the Cashew), Pistacia. Chiefly tropical; except Rhus. The acrid resinous juice is used in var- nishes; but it often contains a caustic poison. Even the exhalations from Rhus Toxicodendron (Poi:on Oak, Poison Ivy), and R. vene- nata (Poison Sumach, Poison Elder), as is well known, severely affect many persons, producing a kind of erysipelas. Their juice is a good indelible ink for marking linen. But the common Sumachs (R. typhina and R. glabra) are innocuous ; their bark or leaves are used for tanning, and their sour berries (which contain bimalate of lime) for acidulated drinks. The oily seeds of Pistacia vera (the Pistachio-nut) are edible; and the drupe of Mangifera Indica (Mango) is one of the most grateful of tropical fruits. The kernel of the Cashew-nut (Anacardium occidentale) is eatable ; and so is the enlarged and fleshy peduncle on which the nut rests: but the coats of the latter are filled with a caustic oil, which blisters the skin; while from the bark of the tree a bland gum exudes. 792. Ord. Burserace®, including a great part of what were formerly called Terebinthacex, consists of tropical trees, with a copious resin- EXOGENOUS OR DICOTYLEDONOUS PLANTS. 407 ous juice, compound leaves usually marked with pellucid dots, and small flowers; with valvate petals, a two- to five-celled ovary, and drupaceous fruit. Their balsamic juice, which flows when the trunk is wounded, usually hardens into a resin. The Ol/banum, used as a fragrant incense, the Balm of Gilead, Balsam of Mecca, Myrrh, and the Bdellium, are derived from Arabian species of the order ; the East Indian Gum Elemi, from Canarium commune; Balsam of Acouchi, and similar substances, from various American trees of this family. 793. Ord. Amyridace® consists of a few West Indian plants, inter- mediate as it were between Burseracez and Leguminose, and dis- tinguished from the former chiefly by their simple and solitary ovary. — Very probably this and the two last are to be recombined. . 163 769 794. Ord. Vitacee (Vine Family). Shrubby plants, climbing by tendrils, with simple or compound leaves, the upper alternate. FIG. 767. A branch of the Grape-Vine. 768. A flower; the petals separating from the base, and falling off together without expanding. 769. A flower from which the petals have fallen; the lobes of the disk seen alternate with the stamens. 770. Vertical section through the ovary and the base of the flower: a, calyx, the limb of which is a mere rim: 5, petal, having the stamen, c, directly before it; and the lobes of the disk are shown between this and theovary. 771 Aseed. 772. Section of the seed, showing the thick ecrustaceous testa, and the albumen, at the base of which is the minute embryo. 772'. A horizontal plan of the flower. 408 ILLUSTRATIONS OF THE NATURAL ORDERS. Flowers small, often polygamous or dicecious. Calyx very small, filled with a disk ; its limb short or obsolete. Petals 4 or 5, valvate in wstivation, sometimes cohering by their tips, and caducous. Sta- mens as many as the petals and opposite them! Ovary two-celled, with two erect ovules in each cell. Fruit a berry. Seeds with a bony testa, and a small embryo in hard albumen. — Zz. Vitis (the Vine), Ampelopsis (the Virginia Creeper). The fruit of the Vine is the only important product of the order. The acid of the grape, which also pervades the young shoots and leaves, is chiefly the tar- taric. Grape-sugar is very distinct from cane-sugar, and the only kind that can long exist in connection with acids. 795. Ord, Rhamnacee (Buckthorn Family). Shrubs or trees, often with spinose branches; the leaves mostly alternate, simple. Flowers small. Calyx of four or five sepals, united at the base, valvate in estivation. Petals four or five, cucullate or convolute, inserted on the throat of the calyx, sometimes wanting. Stamens as many as the petals, inserted with and opposite them! Ovary sometimes coherent with the tube of the calyx, and more or less immersed in a fleshy disk, with a single erect ovule in each cell (Fig. 435, 436). Seeds not arilled. Embryo straight, large, in sparing albumen. — Ex. Rhamnus (Buckthorn) is the type of the order. The berries of most species are somewhat nauseous ; but those of Zizyphus are edible. Jujube paste is prepared from those of Z. Jujuba and Z. vulgaris of Asia. Syrup-of Buckthorn and the pigment called Sap- green are prepared from the fruit of Rhamnus catharticus. The herbage and bark in this order are more or less astringent and bitter. An infusion of the leaves of Ceanothus Americanus. (thence called New Jersey Tea) has been used as a substitute for tea, and a very poor one it is. 796. Ord. Celastraces (Spindle-tree Family). Shrubs or trees, with alternate or opposite simple leaves. Calyx of four or five sepals, imbricated in wstivation. Petals as many as the sepals, in- serted under the flat expanded disk which closely surrounds the ovary, imbricated in estivation. Stamens as many as the petals, and alternate with them, inserted on the margin or upper surface of the disk. Ovary free from the calyx. Fruit a capsule or berry, with one or few seeds in each cell. Seeds usually arilled, albumi- nous, with a large and straight embryo. — /x. Celastrus, Euonymus (Burning Bush, Spindle-tree, Strawberry-tree) ; all somewhat bitter and acrid; but of little economical importance. The red or crim- EXOGENOUS OR DICOTYLEDONOUS PLANTS. 409 son capsules and bright scarlet arils of several species present a striking appearance when the fruit is ripe. 797. Ord. Malpishiacee is a large tropical family (with one or two representatives in Texas), of trees, shrubs, and twining plants, with opposite entire leaves, unguiculate petals, and solitary seeds with a curved embryo; differing from the next in the want of a disk, the more symmetrical flowers, &e. 798. Ord. Sapindaces (Soapberry Family). Trees, shrubs, or climb- ers with tendrils, rarely herbs, with simple or compound leaves, and mostly unsymmetrical or irregular flowers; the sepals and petals imbricated in estivation. Stamens 5 to 10, inserted on a fleshy perigynous or hypogynous disk. Ovary 2—8-celled, 2—3-lobed, with one or two (in Staphylea several) ovules in each cell; the embryo (except in Staphylea) curved or convolute and without albumen. — Includes a variety of forms, the greater part of which may be ranged under the following suborders, which have been taken for orders. 799. Subord, Staphyleacee: (Bladdernut Family) has opposite com- pound leaves with stipules and stipels, regular and perfect pentan- FIG. 773. Flowering branch of Zsculus Pavia (Red Buckeye). 774. A flower. 7715. Flower with the calyx and two of the petals removed. 776. A ground-plan of the flower, showing that its parts are unsymmetrical, 777. Vertical section of an ovary, showing two of the cells with a pair of ovules in each, one ascending, one descending. 778. Cross-section of an ovary. 779. Cross-section of the immature fruit; only one fertile seed; the others abortive. 780. The dehiscent fruit. 385 410 ILLUSTRATIONS OF THE NATURAL ORDERS. drous flowers, three partly united pistils with several ovules in each, and large bony seeds, with a straight embryo in scanty albumen. — Ex. Staphylea. - 800. Subord. Sapindee (Soapberry Family proper) has alternate, or in the Horsechestnut tribe opposite leaves, without stipules, more or less unsymmetrical or irregular and polygamous flowers, exalbu- minous seeds, and a curved embryo with thickened cotyledons. — Mostly tropical, except the Horsechestnut and Buckeyes (Aésculus), which have been deemed a separate family (Aippocastanee). Their very large and fleshy embryo has the cotyledons more or less con- solidated (Fig. 629, 630). The seeds of the Horsechestnut are nu- tritious, but contain an intensely bitter principle which is more or less noxious. Those of AZ. Pavia are used to stupefy fish. The root, according to Elliott, is employed as a substitute for soap. The fruit of Sapindus is used for the same purpose, whence the name of Soapberry. 782 787 784 801. Subord. Acerinee (Maple Family) has opposite (simple or compound) leaves without stipules, a 2-lobed and 2-winged fruit FIG. 781. A branch of Acer dasycarpum (the White Soft Maple) with staminate flowers. 782. Aseparate, enlarged, staminate flower. 783. Branch with pistillate flowers. 784. A separate fertile flower. 785. The same, enlarged, with the calyx cut away. 786. A cluster showing the fruiting ovaries expanding into wings (reduced in size). 787. Ripe fruit; one of the samaras cut open to show the seed. 788. A leaf. EXOGENOUS OR DICOTYLEDONOUS PLANTS. 411 forming two samaras, and an embryo with long and thin, variously curved or coiled cotyledons (Fig. 103-105); otherwise nearly as in the true Sapindacee. — Hx. Acer, the Maple; useful timber-trees of northern temperate regions. Sugar is yielded by the vernal sap of Acer saccharinum, and in less quantity by all the species. 802. Ord. Polygalace. Herbs or shrubby plants, with simple entire leaves, destitute of stipules. Flowers perfect, unsymmetrical, and irregular, somewhat papilionaceous in appearance, but of wide- ly different structure. Calyx of five irregular sepals; the odd one superior, the two inner (wings) larger, and usually petaloid. Petals usually three, inserted on the receptacle, more or less united; the anterior (keel) larger than the rest. Stamens six to eight, combined in a tube, which is split on the upper side, and united below with the claws of the petals: anthers innate, mostly one-celled, opening by a pore at the apex. Ovary compound, two-celled, with a single suspended ovule in each cell: style curved and often hooded. 791 790 795 794 Capsule flattened. Seeds usually with a caruncle. Embryo straight, large, in fleshy, thin albumen. —- Hx. Polygala is the principal genus of the order. The plants yield a bitter principle with some acrid FIG. 789. Polygala paucifolia. 790. A flower, enlarged. 791. The calyx displayed. 792. The corolla and stamineal tube laid open. 793. The pistil and the free portion of the stamens. 794. Vertical section of the ovary. 1795. Vertical section of the seed, showing the large embryo and scanty albumen. 412 ILLUSTRATIONS OF THE NATURAL ORDERS. extractive matter. Polygala Senega (Seneca Snakeroot) is the most important medicinal plant of the family. Other species are employed medicinally in Brazil, Peru, Nepaul, &c.; where, like our own, they are reputed antidotes to the bites of venomous reptiles. 803. Ord. Krameriaces (2hatany Family) consists of the genus Krameria only, which has ordinarily been annexed to the Polyga- laceew ; but the position of the parts of the flower is more like that of the Leguminose, having the odd sepal inferior, a simple unilocu- lar pistil, and an exalbuminous seed. In fact it is technically distin- guishable from the latter chiefly by the hypogynous stamens and the want of stipules. The roots contain a red coloring matter, and are astringent without bitterness. Rhatany-root, used to adulterate port- wine, and as an ingredient in tooth-powders, &c., is the produce of K. triandra of Peru. That of our own Southern species possesses the same properties. 796 197 798 799 804. Ord. Leguminose (Pulse Family). Terbs, shrubs, or trees, with alternate and usually compound leaves, furnished with stipules. FIG. 796. A flowering branch of Lathyrus palustris, var. myrtifolius. 797. The corolla displayed : a, the vexillum or standard; 6, the ale or wings; c, the two petals of the carina or keel.’ 798. The keel-petals in their natural situation. 799. The stamens and pistil, en- larged ; the sheath of filaments partly turned back. EXOGENOUS OR DICOTYLEDONOUS PLANTS. 413 Calyx. mostly of five sepals, more or less united; the odd sepal in- ferior (Fig. 858). Corolla of five petals, either papilionaceous or regular. Stamens perigynous, or sometimes hypogynous. Ovary single and simple. Fruit a legume, various forms of which are shown in Fig. 580, 581, 800-807. Seeds destitute of albumen, or with a mere vestige of it.— This immense family is divided into three principal suborders; viz.:— 802 804 805 805. Subord. Papilionacer (Pulse Family proper), which is charac-- terized by the papilionaceous corolla, — the vexillum always exter- nal in estivation (471, Fig. 392),—ten diadelphous (Fig. 461), monadelphous (Fig. 462), or rarely distinct, perigynous stamens, and the radicle bent on the large cotyledons. Leaves (rarely sim- ple) only once compound ; the leaflets very rarely toothed or lobed. 806. Subord. Cesalpinew (to which Cassia, Cercis, and the Honey-. Locust belong): here the corolla gradually loses its papilionaceous character, and always has the vexillum, or superior petal, covered by the lateral ones in estivation ; the stamens are distinct, and the embryo straight. The leaves are often bipinnate. 807. Subord. Mimosee (a large group, to which the Acacia and the Sensitive Plant belong) has a perfectly regular calyx and corolla, the latter mostly valvate in ewstivation and hypogynous, as well as the stamens, which are sometimes definite, but often very numerous ;. and the embryo is straight. The leaves are frequently tripinnate. FIG. 800. Open legume of the Pea. 801. Loment of Desmodium. 802. Loment of Mi-- mosa: b, one of its dehiscent joints which has fallen away from the persisting border or frame- (replum), seen in 803. 804. The jointed indehiscent legume of Sophora. 805 ‘VIMANVIUL “8 *VIEENVIC 'Z “VIUGNYNOJL ‘T. : qos a]Zuls B UL syuaMELY 1104} fq . . . . . syenpta cIDUL |MaTEYIP BIG IO OM3 JO ‘oures ay} UL ‘payerndas s1aq]0 ‘yoaprad s1aMoy aq} JO atuos + S[BUPLAIPAL JUaTAYyIp Ut 3 G S[BNPLAIpUr ures BY} UT s % sraqyme areqy Aq ® 4 S308 OY WEY} OLOUL UI sqUsMTETY 11aqy Aq % $793 OA} UI spusute[y rey. fq SUAUILS JIOYS 0419 PUB Fao] ANoy SUIUIL}S JLOYS OF PUB BUOT OA\4 xA]Ra 0y} 07 JUaIAypE OU ‘AIO IO [Zy, x Aywo om o yaaraype ‘QL0U 10 OZ gy : i 7 ‘ OL » “s ‘ 5 . s 6 a i 8 ” . o a ” f . . “ “9 i . “i é g i 2 . ~ . } = = € ” 5 . . 5 ‘ -¢ es 5 . . . . 7 T suauyg J euou Jo ‘pareeouod ssid pus statutes a4t + gtoog oyeredas ur THystd 049 07 yuoraype sueuTEys 04} Jaq}IO Yous ILA pe}oosuu0d 1 Odu9T yenbeaun jo $ qyzuey jeuba jo) pus ‘1aq30 yous atay payoeumooun ‘syst any wodJy ayeredas suaure}s out ‘SHSSVID NVONNIT HHL JO MALIA TVOILAONAG BRC ares 04} Ut panos qy0q ‘say -yaeur stysid pus sademinys f Suraeq SINVId THE ARTIFICIAL SYSTEM OF LINNAUS. 515 998. The orders, in the first thirteen classes of the Linnwan ar- tificial system, depend on the number of styles, or of the stigmas when the styles are wanting; and are named by Greek numerals prefixed to the word gynia, used metaphorically for pistil, as follows : — Order 1. Monocynia embraces all plants of any of the first thir- teen classes, with one style to each flower. 2, Diaynta embraces those with two styles. 3. Triexnia, those with three styles. 4. Terraeynia, those with four styles. 5. Prentacynta, those with five styles. 6. Hexagynia, those with six styles. 7. Herracyntia, those with seven styles. 8. Ocroeyrnta, those with eight styles. 9. Enneacynta, those with nine styles. 10. Decacynta, those with ten styles. 11. Doprcaeynt, those with eleven or twelve styles. 12. PoLyeynra, those with more than twelve styles. 999. The orders of class 14, Didynamia, are only two; namely, 1. GYMNOSPERMIA, meaning seeds naked, the achenia-like fruits having been taken for naked seeds. 2. ANGIOSPERMIA, with the seeds evidently in a seed-vessel or pericarp. 1000. The 15th class, Tetradynamia, is also divided into two or- ders, which are distinguished merely by the form of the pod : — 1. SrticuLosa; the fruit a silicle (621), or short pod. 2. Stz1qvosa; fruit a silique (620), or more or less elon- gated pod. 1001. The orders of the 16th, 17th, 18th, 20th, 21st, and 22d classes depend merely on the number of stamens; that is, on the characters of the first thirteen classes, whose names they likewise bear: thus, Order 1. MonanprtA, with one stamen; 2. DranpRi4, with two stamens; and so on. 1002. The orders of the 19th class, Syngenesia, are six ; namely, 1. PoLyGAMIA QUALIS, where the flowers are in heads (compound flower, 394), and all perfect. 516 THE ARTIFICIAL SYSTEM OF LINNEUS. bo . PoLyGamia sureRFLUvA, the same as the last, except that the rays, or marginal flowers of the head, are pistillate only. 3. POLYGAMIA FRUSTRANEA, those with the marginal flowers neutral (Fig. 824, 325), the others perfect. 4, POLYGAMIA NECESSARIA, where the marginal flowers are pistillate and fertile, and the central, staminate and sterile. 5. PoLYGAMIA SEGREGATA, where each flower of the head thas its own proper involucre. . Monocamtia, where solitary flowers (that is, not united into a head) have united anthers, as in Lobelia. ao 1003. The 28d class, Polygamia, has three orders, founded on the characters of the two preceding classes ; namely, 1. Monacta, where both separated and perfect flowers are founded in the same individual. 2. Diacra, where they occupy different individuals. 8. Triacra, where one individual bears the perfect, another the staminate, and a third the pistillate flowers. 1004. The orders of the 24th class, Cryptogamia, are natural or- ders, and therefore not definable by a single character. They are, 1. Finicrs, the Ferns. 2. Musct, the Mosses. 8. AtGa, which, as left by Linnzus, comprised the Hepatice, Lichens, &c., as well as the Seaweeds. 4. Funer, Mushrooms, &c. APPENDIX. Or THE Sicns AND ABREVIATIONS EMPLOYED IN BoranicaL WRITINGS. Linnus adopted the following signs for designating the duration of a plant, viz. : — (©) An annual plant. é A biennial plant. 2 A perennial herb. hk A shrub or tree. Among the signs recently introduced, the following have come into general use : — © A monocarpic (once-flowering) plant, whether annual or biennial. @ An annual plant. ® A biennial plant. 2! A perennial herb. hk A plant with a woody stem. & Astaminate flower, or plant. @ A pistillate flower, or plant. 3% A perfect flower, or a plant bearing perfect flowers. ! The exclamation point is employed as the counterpart of the note of interrogation. When it follows the name of an author appended to the name of a plant, it imports that an authentic specimen of the plant in question, under this name, has been examined by the writer: when it is appended to a locality, it signifies that the writer has seen or collected specimens of the plant from that locality, &c. ? The note of interrogation is employed to denote doubt or uncertain- ty ; and is affixed either to a generic or specific name, or to that of an author or locality cited. * As used by De Candolle, indicates that a good description is found at the reference to which it is appended. It is not in common use. 44. 518 APPENDIX. Those abbreviations of the names of organs which are commonly em- ployed, such as Cal. for calyx, Cor. for corolla, Fl. for flower, Fr. for fruit, Gen. for genus, Hab. for habitat, IJerb. for herbarium, Zort. for garden, Adus. for Museum, Ord. for order, Rad. (Radix) for root, Syn. for synonymy, Sp. or Spec. for species, Var. for variety, &c., scarcely require explanation. VY. sp. denotes, in general terms, that the writer has seen the plant under consideration. V. 8. c. (Vidi siccam cuttam), that a dried specimen of a cultivated plant has been examined. V.s.s. (Vig siccam spontaneam), that a dried specimen of the wild plant has been examined. V.v. ce. (Vidi vivam cultam), that the living cultivated plant has been under examination. V. v. s. (Vidi vivam spontaneam), that the wild plant has been examined in a living state. The names of authors, when of more than one syllable, are commonly abridged by writing the first syllable, and the first letter or the first con- sonant of the second. Thus, Linn., or L.,is the customary abbreviation for Linneus; Juss. for Jussieu; Willd. for Willdenow; Muh. for Muh- lenberg ; AMichx. for Michaux; Jich. for Richard; De Cand., or DC, for De Candolle; Hook. for Hooker; 2nd. for Endlicher; Lindl. for Lindley, &c. Or CoLLECTING AND Preserving PLAnts. 1. Tux botanist’s collection of specimens of plants, preserved by drying under pressure between folds of paper, is termed a Hortus Siccus, or com- monly an Herbarium. 2. A complete specimen consists of one or more shoots, bearing the leaves, flowers, and fruit; and, in case of herbaceous plants, a portion of the root is also desirable. 3. Fruits and seeds which are too large to accompany the dried speci- mens, or which would be injured by compression with sections of wood, &c., should be separately preserved in cabinets. 4. Specimens for the herbarium should be gathered, if possible, in a dry day ; and carried either in a close tin box, as is the common practice, or in a strong portfolio, containing a quire or more of firm paper, with a few loose sheets of blotting-paper to receive delicate plants. They are to be dried under strong pressure, (but without crushing the parts,) between dryers composed of six to ten thicknesses of bibulous paper; which should be changed daily, or even more frequently, until all the moisture is ex- tracted from the plants;—a period which varies in different specics, and APPENDIX. 519 with the season, from two or three days toa week. All delicate speci- mens should be laid in folded sheets of thin and smooth bibulous paper (such as tea-paper), and such sheets, filled with the freshly gathered specimens, are to be placed between the dryers, and so transferred entire, day after day, into new dryers, without being disturbed, until perfectly dry. This preserves all delicate flowers better than the ordinary mode of shifting of the papers which are in immediate contact with the specimens, and also saves much time usually lost in transferring numerous small specimens, one by one, into dry paper, often to the great injury of the deli- cate corolla, &c. 5. The dried specimens, properly ticketed with the name, locality, &c., and arranged under their respective genera and orders, are preserved in the herbarium, either in separate double sheets, or with each species at- tached by glue or otherwise to a half-sheet of strong white paper, with the name written on one corner. These are collected in folios, or else lie flat (as is the best mode) in parcels of convenient size, received into compart- ag of a cabinet, with close doors, and kept in a perfectly dry place. . The seeds of plants intended for cultivation, which are to be trans- Ret to a distance before being committed to the earth, should first be dried “in the sun, wrapped in coarse paper, and preserved in a dry state. They should not be packed in close boxes, at least so long as there is dan- ger of the retention of moisture. 7. Roots, shrubs, &c., designed for cultivation, should be taken from the ground at the close of their annual vegetation, or early in the spring before growth recommences, and packed in successive layers of slightly damp (but not wet) Peat-moss (Sphagnum). Succulent plants, however, such as Cacti, may be packed in dry sand. 8. Plants in a growing state can only be safely transported to a consider- able distance, especially by sea, in the closely glazed cases invented by Mr. Ward ;* where they are provided with the requisite moisture, while they are sufficiently exposed to the light. * On the Growth of Plants in Closely Glazed Cases, by N. B. Ward, F. L.5S., London, 1842. — Ed. 2, 1853. GLOSSARY OF ENGLISH BOTANICAL TERMS, EMPLOYED IN BOTANICAL DESCRIPTIONS, COMBINED WITH AN INDEX. [The numerals without any prefix refer to the pages of the work: those preceded by fig. to figures. ] A, privative, as the initial in many words of Greek derivation, signifies the absence of the organ men- tioned ; as, apetalous, destitute of petals; aphyllous, leafless. In words beginning with a vowel this prefix is changed to an; as, anan- thous, flowerless ; anantherous, des- titute of anthers. Abbreviations. The customary ones are mentioned on p. 518. Aberrant (wandering) : applied to spe- cies, genera, &c. which differ in some respectfrom the usual or nor- mal character of the group they belong to. Abictinex, 480. Abnormal: differing from the normal or usual structure. Aboriginal: strictly native ; indigenous. Abortion: the non-formation or imper- fect formation of an organ, 255. Abortive organs, 258. Abrupt: terminating suddenly. Abruptly pinnate, 163, fig. 290. Absorption, 80. Acanthacez, 447. Acanthocladous: with spiny branches. Acanthophorous: spine-bearing. Acaulescent: stemless, or apparently so, i. e. without a proper caulis; 91. Accessory: something additional. Accessory buds, 98. Accessory fruits, 318. Accrescent : increasing in size after flow- ering, as the calyx of Physalis. 44* Accrete: grown together. Accumbent: lying against, especially edgewise against another body; 326, 390, fig. 700. Acéphalous : headless. Acecrdcez, or Accrinex, 410. Acerose : needle-shaped, like the leaves of Pines, &c. ; 166, fig. 212, 213. Acetdé buliform or acetabulous: saucer- shaped. Achenium (pl. achenia): a one-seeded seed-like fruit ; 313, fig. 566-573. Achlamydeous : destitute of calyx and corolla, 261. Acids, 56, 195. Acicu/ar: slender needle-shaped or bristle-shaped. Acies: the edge of a thing. Acindciform: scymitar-shaped, some bean-pods. Acines (dcini): the separate grains or carpels of an aggregate fleshy fruit, like the raspberry, as the term is now generally used ; classically, the dcinus meant the whole bunch of such fruits. Acotylédonous : destitute of cotyledons. Aecrobryous: budding from the apex only ; same as Acrdgenous: growing 370. Acrogens, Acrégenous plants, 370, 499. Acramphibryous: growing from both ends and over the surface. Acileate: prickly ; beset with prickles (acule) ; 52. like from the apex, 522 \ Acileolate: diminutive of the last: i. ¢. beset with small or few prickles. Aciminate: ending in a narrowed or prolonged and tapering point ; 162, fig. 268, 239. Acutangular ; sharp-angled ; stems of Scirpus pungens. Acute: merely sharp-pointed; ending by an acute angle ; 162, fig. 269. Adelphous (stamens): joined by their filaments or clustered into a brother- hood (adelphia). Adherent; sticking to, or, commonly, growing fast to, another body, 252. Adnate: grown fast to, or formed in union with, another body, as the calyx-tube of the Gooseberry and Cranberry (fig. 891) to the ovary, 251, 252. Attached by its whole Iength, as the anther of Lirioden- dron, 282, fig. 470, and of Asarum, fig. 472. Adnation ; the union of heterogeneous parts, 250. Adpressed, or appressed: brought into contact or nearly, but not united. Adscendent, or ascending : rising gradu- ally upwards, 102. Adsurgent, or assurgent : rising upwards Adventitious, adventive: found out of the natural place. Adventitious buds, 82, 98. equilateral: equal-sided ; opposed to oblique. Aerial: growing in the air. Aerial rovts, 85. Aerophyte: same as Air-plant. Aistival: relating to summer. Aistivation ; arrangement of floral or- gans in the bud, 269. Affinity: true and near relationship ; i. e. species have affinity when they resemble each other in their prin- cipal points of structure, or, in other words, are constructed throughout upon the same particular plan or , type. (See Analogy.) Agamous or Agdmic: destitute of sexes Agglomerate or aggregate: heaped or crowded into a cluster. Aggregate fruits, 317. Air-cells, air-passages, 50. Air-plants, 87. Akenium ov akene: see achenium. Alu (pl. ale): a wing; the side petals of a papilionaccous flower; 253, fig. 392, b. Alahdstrum : a flower-bud. Alur ; borne in the forks of a stem. Alate: winged ; i. e. furnished with any broad and thin adherent appendage, as the seeds of Trumpet Creeper, as the GLOSSARY AND INDEX. fig. 601, the leafstalks of the Or- ange, Rhus Copallina, &c, and the stem of the common Thistle. Albescent : whitened, or hoary-white. Albumen, a vegetable product, 198. Allnimen of the seed, 76, 322. Albuminous (seeds): furnished with albumen, 323. Albiirnum : sapwood, 126. Alga, 509. Algology : the science relating to Algae. Alismaceze, 487. Alkaloids, 57. Alliaceous: like the garlic or onion. Alliances : natural groups of nearly re- lated orders, 374. Allspice, 418. Almond, 415, 417. Alpine: growing on the higher parts of the Alps, and in general on mountains above the limits of trees. Aloes, 493. Alsines, 395. Altérnate (leaves): situated one after another, 78, 97, 133. Petals, sta- mens, &c. are said to alternate with adjacent organs, when they stand over the intervals between them, 235, Alternation of parts, 285. Alvéolate: honeycombed; having deep angular cavities separated by thin partitions, as the receptacle of Cot- ton-Thistle, fig. 898. Amarantaces, 465. Amaryllidaccee, 491. Ament: acatkin ; a peculiar scaly spike ; 213, fig. 312. Amentaceous : resembling or bearing cat- kins. Amnios: the embryo-sac, 304. Amorphous: shapeless, i. e. of no defi- nite or regular form. Amphibryous: growing by additions over the whole periphery. Amphicdrpous, or amphicdrpic : produc- ing two kinds of fruit; as in the genus Amphicarpzea, so named on this account. Amphigastria: the peculiar stipule-like leaves of certain Hepaticee, 504. Amphitropous, or amphitropal, ovule or seed, 300, fig. 528. Amplectant : embracing. Ampléxicaul (leaves, &c.): clasping the stem by a broad base or insertion. Ampulldceous: shaped like an ampulla or flask-shaped vessel ; swelling out at the base or middle. Amygdalex, 415. Amylaceous: composed of starch (dmy- lum), or resembling starch. GLOSSARY AND INDEX. Amyloid, 55. Amyridacez, 407. Anacardiacesx, 406. Analogy: resemblance in certain re- spects. As distinguished from af Jinity it means resemblance in cer- tain respects only, not in the whole plan of structure. Thus a Ranun- culus is analogous to a Potentilla, but there is no near affinity or re- lationship between the two. And the tendril of a Pea, that of a Smi- lax, and that of the Grape-Vine are analogues, i. e. are analogous organs, but are not homologues ; for the first answers to a leaf, the second to stipules, and the third to a stem. The spur of a Larkspur (fig. 398) is analogous to one of the five spurs of Columbine (fig. 646), but not homologous with it, for the first is a sepal, and the second a petal. Andndrous: destitute of stamens. Andntherous : destitute of anthers. Ananthous : without flowers. Andstomosing: connected by cross branches into a network, as the veins of animals, and the so-called veins of reticulated leaves, 49, 54. Andtropous, orandtropal, seeds or ovules, 299, fig. 529. Aneipital: with two edges, as the stem of Sisyrinchium anceps. Andrécium: the stamens of a flower, taken as a whole, 223. Androgynous: bearing both stamens and pistils in separate flowers of the , _same inflorescence. Androphore: a column of united stamens, or any support on which the sta- mens are raised. Androus, in words of Greek derivation, refers to the stamens: see dian- , _arous, &e. Androspores, 335. Anfrdctuose or anfractuous : abruptly bent hither and thither, as the stamens of Melon, fig. 467. Angiospermia, 515. Angiospérmous (Angiospermxz, Angio- - sperms): producing seeds in a peri- carp, 371, 375. Angostura bark, 406. Angular divergence of leaves, 135. Anise, 426. Anisémerous (flower) : of unequal num- ber in the different circles ; unsym- metrical. Anisophy ious: unequal-leaved, as when the two leaves of the same pair are of unequal size. Anisostémonous: when the number of 523 the stamens is different from that of the petals. Annual: lasting not above one year or one season, 83. Annular : in the form of a ring. Annular ducts, 46. Annulate: marked with rings or cireu- , lar transverse lines. Annilus: the ring of the spore-case of true Ferns, 501, fig. 1289: that of the mouth of the spore-case or cap- sule of Mosses, 503, fig. 1304. Anonacee, 382. Anophytes (top-growing plants, of the same meaning as Acrogens ?), 370, 502. Anteposition, 248. Anterior: as to position in the flow- er, on the side next the bract, 237. Anther : the pollen-bearing part of a sta- men, 223, 281. Antheridium (plural, antheridia), 334, 502 Antheriferous : anther-bearing. A’nthesis : the time when the flower opens and performs its functions, or the act of expansion in a flower, 271. Anthocdrpous fruits, 318. Anthocerdtex, 504. . Anthédium: a technical name for the capitulum or head of flowers of a plant of the order Composit. Antholysis : the retrograde metamorpho- sis of a flower. Anthophore : the stalk or internode which is sometimes developed between the calyx and the corolla, as in Silence, 267, fig. 482. Anticous: anterior, or facing forwards. Antitropous, or antitropal: (reversed ;) applied to the embryo, it means one with the radicle pointing away from the hilum, as in fig. 600 and fig. 606. Antrorse : directed upwards or forwards. Apétalous : destitute of petals or corolla, 260. Aphiyllous : destitute of leaves, at least in the form of foliage. Apical: relating to the apex. Apiculate : terminating in an abrupt short point or tip. Apocdrpous pistils : those not united into one body or compound pistil, 290. Apocynaces:, 457. Apophysis: any irregular enlargement, like that of the spore-case of Splach- num and some other Mosses, 503. Apothecium : the shield or shicld-shaped fructification of most Lichens, 506. Appendix, appendage: any superadded part. 524 Appendiculate: having an appendage. Apple, 416. Appressed: lying flat against, or close- pressed together. Apricot, 417. Apterous : wingless ; having no dilated border or appendages. Aquatic: living in water, either sub- mersed or raised partly out of it. Aquifoliacese, 442. Aracee, or Aroidese, 485. Ardchnoid, or drenose: cobwcebby, i. e. with entangled slender hairs look- ing like cobweb. Araliacese, 427.0 © Arboreous, arborescent: tree-like, in size or appearance, 101. Archegdnium (pl. archegonia) : the ana- , logue in Mosses of the pistil. arenate: curved like a bent bow. Aréola, pl. areola: spaces marked out on a surface. Aréolate: marked out into defimte spaces. Arhizal: destitute of root Aril, avillus: an accessory covering or appendage of asced formed by a growth from the funiculus, hilum, or placenta after the completion of | , _the ovule, 321, fig. 603. Arillate: furnished with an arillus. Arillode : a false aril, or covering of the seed appearing like an aril. Aristate : furnished with an awn (arista). Aristolochiacesxs, 462. Arnatto, 392. Arrét: pointing upwards. Arrowroot, 481, 490. Arrow-shaped, or arrow-headed : gittate ; fig. 252. Artichokes, 437. Articulated : jointed, i. e. separating by an articulation or joint, as most leaves from the stem in autumn, or haying the appearance of a joint, 92, 163, 173. Artificial classification, 365, 511. Artocarpex, 474. Ascending: rising obliquely upwards, 102. Asrending axis, 72, 91. Asci: the spore-cases of certain Lichens and Fungi, 506, 507. Ascidium : a pitcher-shaped or sac- shaped leaf, 169. Asclepiadacee, 458. Ashes of plants, 58, 174, 186. Asperqilliform : shaped like an aspergil- lus, or brush used to sprinkle holy water, as the stigmas of most Grasses. Assafeetida, 427. see Sa- GLOSSARY AND INDEX. Assimilation, 19, 21, 61, 177, 190. Assurgent : same as ascending. Atropous or dtropal (ovules): same as orthotropous, 298. Attar of Roses, 417. Attenuate: tapering gradually to a thin or narrow extremity. Augmentation of parts, 242. Aurantiacese, 401. Aurtculate: eared ; furnished with au- ricles or small lobes at the base. Automatic movements, 347. Ava, 469. Avocado Pear, 467. Auwl-shaped: narrow and terete, or near- ly so, and tapering to a point; 166. Awn: a bristle-shaped appendage, like the beard of Barley, &c. Awned : sce Aristate. Azil (arilla, the armpit): the angle he- tween a leaf and the stem, on the upper side, 97. Axile, or dzial: belonging to the axis, , 292. Azillary ; belonging to or growing in the axil. Axillary buds, &e., 97, 210. zlvis: the stem and root, 67, 72; the central line of any body, as the Axis of inflorescence, 211. Baccate: berry-like ; of a fleshy or pulpy texture like a berry (bacca), 311. Bahn of Gilead, &c., 407. Balsams, 145, 407, 414, 480. Balsamiflux, 425. Balsaminaceeze, 403. Banner: same as vexillum, 253. Barbate : bearded ; bearing tufts, spots, or lines of hairs. Barbellate: beset with short and stiff hairs, like the pappus of Liatris spicata, &c. Barbéllulate : a diminutive of the last. Barberry, 384. Bark, 120, 126. Barley, 498. Basal: belonging or relating to the base of an organ. Bascllacese, 464. Basidia: cells of the fructification of Mushrooms, &c., which bear the spores, 507. Basi fixed: attached by the base. Basilar : seated on the base of anything. Bassorin, 55. Bast, or bass, 400: bast-cells or tissue, 44, 120. Baueriez, 425. Bayberry, 477. Bdellium, 407. GLOSSARY Beaked : ending in a prolonged narrow tip. Bearded: beset with hairs, especially stiff or long hairs. Beard is some- times used for awn. Bell-shaped : having the shape of a bell ; 277, fig. 456. Benzoic Acid, Benzoin, 443. Berberidaces, 384. Bergamot, 401. Berry: a fruit fleshy or pulpy through- out, 311. Betel, 469. Betulacez, 477. Bi- (or bis), as a prefix, means twice, as in the following : Biactiminate : two-pointed. Biarticulate : two-jointed. Biauriculate: two-eared. Bibracteate : with two bracts. Bibrdcteolate : with two bractlets. Bicdllose: bearing two callosities or lit- tle protuberances. Bicipital : having two stalks or legs, as the keel of a papilionaceous corolla, fig. 392. Biconjugate : twice-paived, as when the petiole of a compound leaf forks twice. Bicornute : two-horned. Bidéntate : having two teeth (not twice dentate or doubly toothed). Biennial: lasting more than one year, but not more than two ycars, 83. Bifarious : two-ranked ; arranged in two vertical rows. Bifid : two-cleft to the middle or there- abouts, 159. Biflorous : two-flowered. Bifoliate: two-leaved. Bifoliolate: of two leaflets. Brfircate: two-forked, or, sometimes, twice-forked. Bigéminate : twice-paired. Bigener : a hybrid between two plants of different genera. Bignoniacew, 447. Bijugate: a pinnate leaf with two pairs of leaflets. Bildbiate: two-lipped, 255, 258, 278. Bildmellate, or bildmellar : of two plates or lamellae. Bilberry, 439. Bilcbate, or bilobed: two-lobed, 159. Bilscular : two-celled. Binary : the parts in twos, 239. Binate : in twos ; produced or borne in pairs, 164. Binomial nomenclature (of two names), 363. Bipartite: two-parted. ; Bipinnate: doubly or twice pinnate ; 164, fig. 282. 525 AND INDEX. Bipinnately : twice pinnately, 161. Bipinndtifid: doubly or twice pinnati- fid; 161, fig. 280. Bipinndtisect :_ twice-pinnately divided, 161. Biplicate : twice folded, or having two folds. Biporose: opening by two small holes or pores, fig. 474, Biradiate : consisting of two rays. Birdlime, 469. Birimose: opening by two most anthers, fig. 473, Biséptate: having two partitions. Bisérial, or bisériate: occupying two rows, one within or above the other. Bisérrate: doubly serrate, i. e. the teeth themselves serrate. Bisexual: having both stamens and pis- tils, 261. Bisulcate : having two furrows. Bitérnate: twice ternate; i. e. divided into three parts, and these again into three ;: 164, fig. 284. Blackberry, 416. Bladdery : thin and inflated, like a blad- der. Blade of a leaf, petal, &e., 145, 276. Bloom, 56, 144. Blueberry, 439. Boat-shaped: concave within and con- vex (and often keeled) without. Bohon-Upas, 475. Borraginaces, 450. Bothrénchyma, 45, 46. Brdchiate: with opposite branches, the successive pairs spreading at right angles with each other. Bract (Latin, bractea) : the leaves of an inflorescence, especially the leaf which subtends a flower, 143, 211. Brdcteate : subtended by a bract. Brécteolate : subtended by Bractlets, brdcteoles (Latin, bractéole) : bracts of a second order, &c¢., or bracts on the pedicel or the flower- stalk, 211. Branches, and branchlets, 97. Brazil-wood, 414. Bread-fruit, 475. Breathing-pores, 52, 150. Bristles: stiff short hairs (52), or hair- like bodies. Brisily : beset with stiff bristles. Bromeliacese, 492. Brydlogy : same as Muscology. Buckwheat, 466. Bud: a stem or branch in an undevel-- oped state, 93. Budding, 100. Bud-scales, 95, 167. Buffalo-berry, 468. slits, as do 526 Bulb: a permanent bud with fleshy scales, mostly subterranean, 109. Bulbijirous : producing bulbs. Bultiets = little bulbs above ground, 109. Bulbose, or bulbous : bulb-like in shape. Bulbo-tuber ; same as a corm. Bullate : a surface appearing as if blis- tered, puckered, or bladdery (from bulla, a bubble). Burmanniacee, 490. Burseracew, 406. Bursicilate : provided with pouch-like appendages (bursicule), Butomacee, 487. Butterfly-shaped corolla, 253, 277. Butternut, 476. Byssaceous : composed of fine entangled threads (byssus, or fine flax). Byttneriaces, 398. Cabombacex, 386. Cactacex, 421. Cadicous: falling off at the time of expansion, as the calyx of the Poppy, 279. Casalpincx, 413. Cesions : layender-colored. Céspitose, or cespitose: growing in tufts or turfs. Cajeput oil, 418. Calabash, 447. Calabash-Nutmeg, 383. Culathidium : a name for the head of Composite. Caldthiform : cup-shaped. Cdlcarate : bearing a spur (calcar), 278 ; as the Violet, fig. 396, and Lark- spur, fig. 398. Calccolate, or cdleiform, slipper-shaped. Callitrichacex, 470. Callose : furnished with callosities (calli) or hardened or protuberant spots. Calvous : bald. Calycanthaces, 417. Calycine: relating to the calyx. . Calculate, or culiculate : furnished with an outeraccessory calyx (calzculus), or set of bractlets resembling a ca- lyx, as in Dianthus. Cahjptra : the hood or veil of the spore- case of a Moss, 503, 504; or a body like it, 389. Caljptrate : furnished with a calyptra, or something like it. Cahjptriform : shaped like a calyptra or cand]e-extinguisher, as the calyx of Eschscholtzia, p. 389, fig. 692. Calyx : the exterior floral envelope, or leaves of the flower, 222, 274, Cambium, Cambium-layer, 122. Camelliacez, 400. ‘Campanulacer, 438. GLOSSARY AND INDEX. Campdnulate: bell-shaped ; 277; fig. 456. Camphor, 400, 467. Campylospérmous: when a seed or secd- like fruit is rolled up so as to form a longitudinal furrow down one side, as that of Sweet Cicely. Campylotropous or campylotropal ovule or seed, 298, 299, fig. 527. Canada Balsam, 480. Canaliculate : longitudinally channelled. Céncellate: resembling lattice-work. Candleberry, 477. Canescent: whitened or hoary with fine and close pubescence. Cannabince, 475. Cannacee, 490. Caoutchouc, 57, 458, 478, 475. Capers, 391. Capillary, or capilldceous : hair-like. Capitate: headed; having a globular apex like the head of a pin; or col- lected into a head. Capitellate : diminutive of capitate. Capitulum : a head of flowers, as of Clover, Button-bush, &c. ; 213, fig. 320. Capparidacex, 391. Cupréolate: furnished with tendrils. Caprifoliaces, 431. Capsiar : relating to a Capsule : any compound dehiscent fruit ; 315, fig. 582, 583. Cardamon, 490. Carina: akeel; the two anterior petals of a papilionaceous flower; 254, fig. 392, ¢. Carinate: keeled ; furnished with a pro- jecting longitudinal ridge along the under side. Caridpsis, or carydpsis: a grain, 314. Carneous : flesh-colored. Carnose: fleshy in texture. Carpel (carpellum or carpidium) : a sim- ple pistil, or one of the elements of a compound one, 290. Carpellary : pertaining to a carpel. Carpology: the department of Botany that relates to fruits. Carpophore: the stalk of a pistil, 267. Carrot, 426. Curtilaginous ; tough, like cartilage. Caruncle: an excrescence at the hilum of certain seeds, 322. Carinculate : furnished with a caruncle. Caryophyllacex, 395. Caryophyllaccous (corolla) : pink-like, 9 Caryopsis : a grain, 314. Cascine, 198. Cashew, 406. Cassava, 472. GLOSSARY AND INDEX. Cassia-bark, 467. Castor-oil, 472. Castrate (stamen): with no anther or one containing no pollen. Catapetalous : where the petals are unit- ed with each other at the base and with the base of the stamens, as in the Mallow family. Catechu, 414. Caténulute: composed of parts united end to-end, like the links of a chain. Catkin: see Ament, 213. Caudate : tailed or tail-pointed. Caudex, 101. Caudicle: a little stalk, like that of the pollen-mass of Orchis, &., fig. 1235 Caulescent : obviously having a stem. Caulicle : a little stem, or a rudimentary stem ; the radicle, 71. Cauline, or caulinar: relating to a Caulis: the main stem, 91. Cayenne pepper, 456. Cedrelacex, 401. Cedron, 405. Celastracee, 408. Cell: a cavity of an anther, ovary, &c., 281, 291. In vegetable anatomy, one of the vesicles, or elements of which a plant is composed, 23. Cell-formation, 27. Cell-growth, 30. Cell-multiplication, 28. Cellular bark, or envelope, 121. Cellular Plants, 68. Cellular tissue, or structure, 23. Cellule: same as Cell (in veg. anatomy). Cétlulose, 27, 192. Celtidex, 474. Centrifugal inflorescence, 218. - radicle, 326. Centripetal inflorescence, 212. _ radicle, 326. Ceratophyllaceze, 470. Céreal: belonging to corn or corn- plants ; these ‘having been called the gift of Ceres. Cernuous: nodding. Chaff: the scales or bracts on the re- ceptacle which subtend each a flow- erin the heads of many Composite, as the Sunflower ; also the glumes, &c. of Grasses ; 215, 435. Chaffy : provided with, or of the texture of chaff. Chaléza: the part of the ovule where the coats, nucleus, &c. are all unit- cd; 298, fig. 521, d, 526, c, Channelled: see Canaliculate. Characex, 510. Characters : the essential marks distin- guishing one species, genus, &c. from those most resembling it, 362. 527 Chartaceous : of the texture of paper or parchment. Checkerberry, 441. Chenopodiacee, 464. Cherry, 417, Chestnut, 477. Chlorophyll : leaf-green, 58. Chlordsis : a loss of color; a reversion of the petals, &c. of a blossom to green leaves. Chlorospermee, 509. Chocolate, 398. ‘ Chorisis : the division of onc organ into two or more, 243. Chromule; the coloring matter of plants, especially of petals, &c. Chrysobalanacex, 415. Cicatrix : a scar left by the fall of a leaf or other organ. Cilia (sing. cilium, the eyclash) : hairs or bristles fringing the maryin of any- thing ; those of the inner peristome of a Moss, 502. Ciliate: the margin fringed with hairs. Cinchona, 432. Cinchonee, 432, Cinénchyma, 49. Cinereous, cineraceous: ash-gray. Cinnamon, 467. Circinate: involute from the top; 144, Circulation in cells, $1, 178. Circumeissile, or _circumscissile : opening or divided by a transverse circular line ; 317, fig. 588. Circumscription ; the general outline. Cirrhose, cirrhiferous: tendril-bearing, or with organs serving as a Cirrhus : a tendril. Cistacez, 393. Cistoma : a kind of sac lining the cham- ber under a stomate in certain plants. Classes, 360. Classification, 352. Clathrate ; latticed. Clavate, claviform: club-shaped ; narrow below and thickened towards the summit. Claviculate: with tendrils, or leafstalks acting as such (clavicule). Claw.: the. narrowed base of a petal, &e., 276. Cleft : cut to about the middle, and with narrow or acute sinuses; 159, fig. 261, 265. Climbing : rising by laying hold of oth- er objects in any way, 102. Clindnthium : the receptacle of the flow- ers in Composite. Cloves, 418. Club-shaped: see Clavate. 528 Clusiacen, 400. Clustered : collected into a bunch. Chjpeate : buckler-shaped. Coacérvate : heaped together. Coddunate : cohering ; united at the base or farther. Coalescence, 249, Coalescent : growing together. Coarctate : crowded together. Coated: composed of layers; or fur- nished with a rind. Cobwebbed, or cobwebby: bearing long hairs like cobweb or gossamer. Cocculus Indicus, 384. Coceus (pl. cocci): anciently a berry; now used for the closed carpels into which many fruits split (316), as those of Euphorbia, fig. 1143, 1145, and Verbena, fig. 985. Cochledriform: shaped like a spoon (coch- lear). Cochlente: like a snail-shell (cochlea). Cocoa-plum, £15. Celospérmous : i. ve. hollow-seeded ; the top and bottom incurved, as in Co- riander-seed. Coffee, 433. Coherent : united together. Cohesion of parts, 250, &e. Coleorhiza (root-sheath) : the sheath or covering (belonging to the cotyle- don or plumule) through which the radicle of most Endogens bursts in germination. Collar, collum : the neck or line of junc- tion between the primary stem and root. Collective fruits, 318. Colocynth, 423. Colored: of some other color than green. Columbo-root, 384, 457. Columéila : the axis, or central column, of a pod or spore-case. Column: the united filaments of mon- adelphous stamens, or the united filaments and style in gynandrous flowers ; 281, fig. 468. Cotnmnar : pillar-shaped. Coma; a tuft of any sort, especially a tuft of hairs on a seed, 321, fig. 662; the whole head of a tree, &e. Comate, or comose: bearing a coma. Combretacee, 419. Commelynacez, or Commclinaceze, 496. Commissure: the line of junction of two carpels; used mostly in Umbel- liferae, 426. Common: used as “ general,” opposed to partial. Complanate: flattened. Complete flower: having all the kinds of organs, 222, 238. GLOSSARY AND INDEX. Complicate: folded upon itself. Composite, 435. Compound flower, 215, fig. 323 - 325, and 435, fig. 887, &e. Compound leaf: one composed of two or more blades, 163. Compound pistil, 290. Compound spike, raceme, umbel, &c., 216. Compressed: flattened on two opposite sides. Concentric layers of wood, 112, 123. Conchiform: shell-shaped. Concolored : all of one color. Condiiplicate ; folded together length- wise, 144, 165. Cone: see Strobile, 319. Conferriiminate: stuck together by their adjacent faces, as the cotyledons of Horsechestnut, 327. Conferted : crowded. Confluent : running together, or blended into one. Conformed: similar to; or closely fitted to, as the skin to the kernel of a seed. Congested : crowded together. Conylobate: clustered into a ball. Conglomerate: thickly clustered. Conifers, 479. Coniferous: cone-bearing. Conjugate : coupled; in single pairs. Conjugation, 332. Connate: united or grown together from the earliest state, 251. Connate-perfoliate, 166, fig. 294. Connective, connectivum : the part of the anther connecting its two cells or lobes, 281, 282. Connirent : converging. Conoidal: approaching a conical form. Consolidated: when unlike parts are grown together. Consolidution, 250. Continuous : not interrupted. Contorted : twisted, 272. Contortuplicale : twisted and folded. Contracted : either narrowed or short- ened. Contrary : opposite in direction to some- thing it is compared with, as the pod of Shepherd’s Purse flattened contrary to the partition. Convolute (rolled up) or cénvolutive sti- vation, 272. Convolute vernation: rolled up length- wise in the bud, 144. Convolvulacem, 454. Copaiva, 414. Copal, 414. Copalche-bark, 434. Cordate: heart-shaped; shaped like a heart as painted upon cards, the GLOSSARY AND INDEX. sinus, or notched end, being at the base ; fig. 244. Cordiacex, 451. Coriuceous : of a leathery consistence. Cork, 477. Corky: of the texture of cork. Corky envelope or layer of the bark, 121, 127. Corm (cormus) : a solid bulb, 108. Cormophytes: plants having an axis (root and stem), in contradistine- tion to Thallophytes, 371 Cornaceer, 428. Corneous: of the consistence of horn. Corntculate: furnished with a small horn. Cornine, 428. Cornute: furnished with a horn (cornu). Corolla : the inner of the two floral en- velopes, 222, 275, Corolldceous, corolline: like a corolla in appearance or texture, or belong- ing to the corolla. Corénu: a crown, such as the append- age at the top of the claw of the ‘ petals of Silene ; 246, fig. 378. Coronate: bearing a crown. Cortex : the bark or rind. Cortical: pertaining to the bark. Corticate: furnished with a distinct rind. Corymb: a conyex or flat-topped flower- cluster, 211. Coérymbose: disposed in, or resembling, corymbs. Costa: a rib, or midrib. Costate: ribbed, or with a midrib. - Cotton, 44, 398. Cotyléions : the first leaves of the em- bryo ; seed-leaves, 71, 324. Cofjliform : dish-shaped. Coumatin, 414. Cowitch, 415. Cranberry, 439. Crassulacese, 423. Cratériform : goblet-shaped. Creeping: ranning on or beneath the ground and rooting, 102. Crémocurp: the fruit of Umbellifere, 425. Crenate, or crenelled: the margin fur- nished with even and rounded notches or scallops ; 159, fig. 256. Crénulate: diminutive of Crenate. Crescentiee, 447. Crested: see Cristate. Cribrose: pierced with holes like a sieve. Crinite: bearded with long hairs. Crispate : curled. Cristate: evested ; bearing any elevated appendage on its surface. ; Cross-breeds : individuals originated by 45 529 fertilizing one variety or specics by another, 356, 357. Crowberry, 474. Z Crown (246, 279, fig. 378) : see Corona. Crowned : sce Coronate. Crowning : borne on the apex of any organ. Cruciate, or cruciform: cyoss-shaped, 277, as the corolla of the Mustard family, fig. 405. Crucifere, 389. Crude sap, 53, 190. Crustaceous :_ crusty in texture, hard and brittle. Cryptogamia, 513. Cryptégamous or cryptogamic: relat- ing to Cryptogamous Plants, 69, 330, 499. Crystals, 59. Cricullate, or cuculliform : hooded or hood-shaped ; rolled up like a cor- net of paper, 503. Cucumber, 423. Cucurbitacex, 423. Culm: a straw, or straw-like stem, 101. Cultrate: shaped like a broad knife- blade. Ciineate, or cuneiform: wedge-shaped ; broad above, and narrowed to the base, with straight sides ; fig. 235. Cunoniacex, or Cunonice, 525. Cupressinez, 480. Cup-shaped, cupiliform : hemispherical, and hollow above. Cipulate: furnished with a Cupule, or cipula: the acorn-cup, 314. Cupuliferae, 476. Curled: irvegularly folded and crimped. Currant, 421. Curvinerved, 158, fig. 236. Curviserial : in curved ranks, 141. Cuscutez, or Cuscutine, 455. Cushion: the swollen base of a leaf- stalk, or the enlargement below the insertion of many leaves. Cispidate : tipped with a cusp, or sharp and rigid point ; 162, fig. 275. Custard-Apple, 382. Cut : see Incised, or Dissected. Cuticle : the outer skin or pellicle of the epidermis, 149. Cydthiform : cup-shaped. Cycadacez, 481. . Cycle: one complete turn of a spire; @ circle. Cyclical : coiled into a full circle. Cyclosis : circulation in cells, 31. Cylindraceous: approaching to the Cylindrical: circular in transverse out- line and tapering gradually, if at all, as in most stems. Cimbecform : boat-shaped. 530 Cyme (cyma): u cluster of centrifugal infloreseences, 218. Cymose: bearing cymes, or cyme-like. Cijmule (cyjnula): wx cymelet, or little cyme, 218. Cynarrhodium : such a fruit as that of Rose (fig. 429) and Calycanthus, fig. 815, 819. Cyperaceee, 496. Cipsela : an achenium with an adher- ent calyx-tube, as in Composita. eis: 2 a utricle. ‘“ystolithes, 60. Cytoblast: the nucleus of a vegetable cell. Dammer Pitch, 400. Deca-, in words of Greek derivation : ten ; asin Decagynia, 515. Decdyjynous : with ten pistils or styles. Decdmerous : the parts in tens, 234. Deedndria, 512. Decéndrous : with ten stamens, 280. Decapétalous : with ten petals, 276. Deciduous: falling off, or subject to fall; as petals falling after blos- soming, 279, and leaves before winter, 172. Declinate, declined: turned to one side. Decompound: several times compound- ed, 165. Deciimbent : reclined on the ground, the summit rising, 102. Deciirrent: prolonged below the inser- tion, as the leaves of the Thistle, 170. Decissate: the successive pairs crossing each other at right angles, 142. Deduplication (dédoublement), 243. Definite: of a fixed number, and not above twelve or twenty. Definite growth, 100- Definite inflorescence, 217. Deflexed: bent downwards. Deflorate: past the flowering state. Defoliate: having cast its leaves. Dehiscent fruits, &c., 315; opening by Dehiscence: splitting, as do pods,311, 316. *% of anthers, 283. Deliquescent : the stem dissolving into branches, 99. Deéltoid : shaped like the Greek capital A. Demersed: growing under water. Dendroid, dendritic : trec-like. Dentale : same as toothed ; 159, fig. 255. Denticulate : furnished with fine tecth, or denticulations. Deniidate : made naked. Depauperate: dwarfed in size. Depressed : flattened vertically or from above. GLOSSARY AND INDEX. Descending: tending gradually down- wards. Descending axis, 72, 79. ‘ Desmidiz, or Desmidiaces, 510. Determinate inflorescence, 217. Descriptive Botany, 15. Development, 19. Dextrine, 54, 193. Dextrorse: towards the right. Di-, in Greek compounds ; two. Diadelphia, 513. ‘ Diadeélphous: stamens united by their filaments in two sets ; 280, fig. 461. Diandria, 512. Didndrous : with two stamens, 279. Diagnosis: a brief essential character. Dialypétalous : of distinct petals. Diapensiacem, 454. Didphanous : transparent. Diatomacee, 510. Dicdrpellary : of two carpels. Dichlamjdcous: with both calyx and corolla, Dichondrex, 455. Dichotomous ; forking into two branches. PDictinous : with the stamens and pistils in separate blossoms, 261. Dicéccous : separable into two cocci. Dicotyledonous : having a pair of cotyle- dons, 78, 326. Dicotyledons, Dicotyledonous Plants, 114, 326, 370. Didymous : twin. Didyndmia, 512. Didijnamous: with two long and two shorter stamens, 258, 281. Difformed: of unusual shape. Diffuse: widely and loosely spreading. Digamous : having flowers of two dif- ferent sexes. Digestion, 190. Digitate (fingered) : compound, with the parts all arising from the same point ; 163, tig. 277. Digitately tri-plurifoliolate, 164. Digynia, 515. Digynous : with two pistils or styles, 287. Dillenincez, 380. Dimerous: the parts in twos, 234, 239. Dimidiate: halved, or appearing as if one half or side were wanting, 283. Dimorphous : of two forms. Dieecia, 513. Dicecious : with stamens and pistils in separate blossoms on different individuals, 262. Dioscoreacer, 492. Diosmex, 407. Dipeétalous : of two petals, 276. Diphyllous : two-leaved, 275. Diplostémonous: stamens double the petals or sepals in number. GLOSSARY AND INDEX. Dipsacer, 435, Diptcrocarpes, 400. Dipterous : two-winged. Disciform: disk-shape ; flat and cireu- lar, like a disk or quoit. Discoidal, discoid: like a disk; or be- longing to the disk; destitute of rays, 436. Disépalous + of two sepals. Disk, or disc: a fleshy expansion of the receptacle of a flower, 267 : the central part of ahead of flowers, as opposed to the border, 436 ; the face of any flat body, as opposed to the margins. Disk-bearing woody tissue, 43. Disk-flowers, 436. Dissected : cut into picces, or nearly so. Dissépiment : the partition of a pod, 291. Dissilient : bursting in picces. Distichous : in two vertical ranks, 134. Distinct: when parts of the same name are unconnected, 251. Divaricate: straddling widely. Divergent: separating, their summits inclining from each other. Divided: cut into distinct portions ; 160, fig. 263, 267. Dodeca-: in Greck derivatives ; twelve. Dodecagynia, 515 Dodecdgynous: with twelve pistils or styles. Dodecindria, 512. Dodecéndrous: with twelve (or from twelve to nineteen) stamens, 280. Doldbriform : axe-shaped. Dorsal: belonging to the back (dorsum). Dorsal suture, 289. Dottid ducts, 38. Doited leaves, &e.: marked with small spots, either colored, or transparent and appearing like punctures. Double flowers : monstrous blossoms, with the petals unduly multiplied, 222, 229, Doubly compound, 164. Downy: clothed with soft pubescence. Dragon’s blood, 414, 493. Droseracex, 394. Drupaceous : like or pertaining to a Drupe: a stone-fruit, 312. Drupelet : a diminutive drupe, 313. Dryade, 418. Ducts, 45. Dumose: bushy. Duplicate: doubled or folded. Durdmen: heart-wood, 126. Dwarf: comparatively low in stature. E., or Ex-, as a prefix, means destitute of ; as, ecostate, ribless ; exalbumi- nous, without albumen, &c. 531 Feared: see Auriculate. Earthy constituents of plants, 179, 186. Ebenacee, 442. Ebéneous : black like ebony. Ebony, 442. Ebrdcteute: destitute of bracts. Ebrdcteolate : destitute of bractlets. Ebirneous : white like ivory. Echinate: beset with prickles (like a hedgchog). Echinulate: rough with small prickles. Edéntate : toothless. Effee: past the perfect or productive state. Effiise: very loosely spreading. LEqlandulose: destitute of glands. Tlaborated sap, 53. Eleagnacer, 467. Eaters, 40, 505. Elatinacee, 395. Elementary constituents of plants, 179. Elementary structure of plants, 17. Fillipsoidad : approaching the form of Elliptical: oval or oblong, and with both ends similar and regularly rounded. Emarginate: notched at the end; 162, fig. 273. Embracing : surrounding, as by a broad , _ attachment. Embryo: the rudimentary plantlet in a seed, 71, 323. Eembryo-sac, 304. Embryogeny ; the formation of the em- bryo, 304. Embryonal vesicle, 306. Emersed : raised out of water. FEmetine, 433. Enantiobldstous : with the embryo at the end of the (orthotropous) seed dia- metrically opposite the hilum, as in Tradescantia. Endecagynia, 515. Endecdgynous: with eleven pistils or styles. Endocarp : the inner layer of a pericarp, , 810, 312. Endochrome: the coloring matter of , Alge. Endogen, Endégene, Enddgenous Plants, 113, 370, 482. Endogenous structure, 113, 114. Endophléum : inner bark, 120. Endopleira: the innermost seed-coat, 321, Endorhize : 2 synonyme for Endogens. Endorhizal: said of an embryo which has the radicle sheathed by the cotyledon or plumule wrapped around it. Endosmose, or Endosmosis, 33. E'ndosperm: the albumen of the seed, 532 especially when this is formed in the , _embryo-sac of the ovule, 322, 323. Endostome: the orifice of the inner coat of the ovule, 298. Endothécium: the inner lining of the cells of an anther. Enerved ; nerveless. Finnea-: nine; as in Enneagynia, 515. Ennedqynous : with ninc pistils or styles. Enneandria, 512. Ennedndrous : with nine stamens. FEnneapeétalous : nine-petalled, 276. Znédal; without a node. Ensate: same as Ensiform : sword-shaped. Entire: the margin whole and even, , hot toothed or cut, 158, 275. Entophytes : plants parasitic within oth- er plants. Epacridex, 440. Ephemeral: lasting but a day. Bei, in Greek compounds : upon. Epicdlyx: an involucel resembling an exterior calyx, as in Mallow. dpicarp: the outermost layer of a peri- carp, 310. Epichilium: the upper part of the lip of an Orchid, when different from the lower. Epicérolline : wpon the corolla. Epidermal : relating to the Epidérmis: the skin of a plant; 51, 122, 148. Epigéous : growing on or close to the ground. Epiyynous: upon the ovary, 252, 268, 281. Epipetalous : upon the corolla, 281. Epiphléum : outer or corky bark, 121. Epiphijlious : upon a leaf. Epiplijtal, ov epiphitic : relating to E’piphytes, plants growing affixed to another plant, but not nourished by it, 87. Epiplterous ; winged at the top. Episperm ; the outer seed-coat, 320. Bal: regular, or of the same length or number, as the case may be. Equilateral : equal-sided. Equisetaccz, 499. F'quitant : viding straddle, 145, 165. Evianthous : woolly-flowered. Ericacese, 439. Ergot, 498. Eriocaulonacee, 496. Eriogonce, 466. Erose: eroded, as if gnawed. Erostrate: not beaked. Escallonice, 425. Essential organs of the flower, 222. Estivation: see Aistivation. GLOSSARY AND INDEX. Eterio: a name for such a fruit as a raspberry and blackberry. Euphorbiacex, 471. valved, or evdivular : valveless. Evergreen: holding the leaves over win- ter or longer, 172. Evralbiiminous : without albumen, 323. Excentric: out of the centre, 325; one- sided. FExeretions, 57, 178. LExcurrent : protruding beyond the apex, as when the midrib of a leaf pro- jects : or running to the very sum- mit, as the main stem of a Fir, 99. Exhalation, 175. E’xocarp: the outer layer of a pericarp, , 312 Exogen, Exdgene, Exogenous Plants, 113, 370. Fexogenous structure, 113, 116. Exorhize : a synonyme of Exogens ; the radicle in these being Exorhizal: not enclosed or sheathed by the cotyledons or plumule. Frosmose, or L’xosmosis, 33. f'xostome: the orifice of the outer coat of an ovule, 298. Ferostdsis : an indurated protuberance. Frothecium : outer coat of the anther. Explanate: outspread or broadly flat- tened. Exserted, exsért: protruding beyond, as the stamens out of the corolla in fig. 450. Exstipulate : destitute of stipules, 171. Fatrior: as applied to the parts of a blossom, the same as anterior. Extine: the outer coat of a pollen-grain, 286. Extra-axillary: out of the axil, 99, 220. Extrorse: turned outwards, 282. Facies: the general aspect. Falcate, fulciform : scythe-shaped ; flat and curved, the edges parallel. Families, 359. Fan-shaped: sce Flabelliform. Farina: starch, 54. Farinaceous : mealy; containing starch. Farinose: covered with mealy powder. Fasciate: banded ; applicd also to mon- strous stems which grow flat. Fasciation: the singular monstrous ex- pansion of stems, &c. as in the gar- den Cock’s-comb. Fascicle: a close cyme or cluster of flowers, 219; a bundle of leaves crowded like those of the Larch, fic. 213. Fascicled : growing in tufts or clusters, 84, 142. GLOSSARY AND INDEX. 533 _Fasciculate: in small tufts. Fastigiate: close, parallel, and upright. Faux (pl. fuuces) + the gorge or throat. Frveolute, favose: with deep pits, like honeycomb. Feather-vened: haying veins all pro- ceeding from a midrib, 155. Feathery : see plumose. Féewa: starch, 54, Female flower: see Fertile flower. Fene’strate: pierced with one or more holes, like windows. Ferrujineous or ferruginous: of the color of iron-rust. Fertile: capable of producing fruit. Stamens ‘are also said to he fertile when their anthers contain good pollen. Fertile flower: 261. * Fertilization, 300. Fibre, 41, Fibril: a delicate fibre-like body ; the root-hairs, 81. Fibrilliform tissue, 48. Fibrilloss : bearing fibrils: diminutive of fibrous. Fibrine, 198. Fibrous or fibrose : composed of slender threads or fibres. Fibro-vascular tissue or system, 50. Fiddie-shaped: obovate and contracted on cach side. Fig, 215, 475, and fig. 590-592. Filament: the stalk of an anther, 223, 281. Or any slender thread. Filamentous, or filamentose: composed of threads or filaments. Filices (Ferns), 500. Filicology: the part of Botany which treats of Ferns. Fuiform: shaped like a thread ; slender and terete, 166. Filipendulous: hanging from _« thread, as the tuberous roots of Spireza fili- pendula. Fimbriate: fringed ; bordered by slen- der processes or appendages. Finbrillate or fimbrilliferous: diminu- tive of the last. Fingered: see Digitate. : Fissiparous : propagating by division into two portions. Fistular ov Fistulose: hollow through its length, as the leaves of Onion. Fldbellate, or flabdlliform : fan-shaped ; broadly wedge-shaped with the summit rounded. Flacourtiacer, 392. Flagellute: bearing flagella, i. e. runners, like those of the Strawberry. Flagélliform : long, taper, and supple, 45 * one having pistils, like the thong of a whip ;_ runner- like. Flavescent : yellowish or pale yellow. Flavous : yellow. Flax, 402. Fleshy : succulent, or of the consistence of flesh, 84. Fléxuose, or flexuous : zigzag ; bent alter- nately inwards and outwards. Floating: growing on the surface of water. Floccose: bearing or clothed with locks of soft hairs or wool. Flora (the goddess of flowers) : the ag- gregate of the species of plants of a country ; or a work systematically deseribing them. : Floral: belonging to the flower. Floral envelopes : flower-leaves, 222, 268 Torescence: same as anthesis. Floret: a small flower, or a separate blossom of a so-called compound flower. Floridex, 509. flortferous : flower-bearing. Flssculous : composed of or bearing flos- culi, i. e. florets; or composed of tubular flowers only. Flower, 70, 221. Flower-bud, 209, 224. Flowering, 204. Flowering Plants, 69, 369, 375. Flowerless Plants, 69, 330, 499. Fiuitant: floating on water. Fhiviatile: belonging to flowing water. Fly-traps, 168. . Foliaceous: leaf-like, i. v. thin, membra- naceous and green; or bearing leaves, Foliar: belonging to leaves ( folia). Foliation ; leafing out. Foliate: clothed with leaves ; or, with a numeral prefix, denoting the num- ber of leaves ; as, bifoliate, two- leaved : trifoliate, three-leaved, &c. Féliolate: consisting of leaflets (fo- lola) ;_ as, bifoliate, a leaf having two leaflets, or trifoliolate, having three leaflets, &e. Foliose: bearing numerous leaves. Follicle: « simple pod opening down one side; 315, fig. 579. Follicular, of the nature of a follicle. Fordmen: an aperture or orifice, 298. Foraminulose : pierced with small holes. Forcipate : forked like a pair of pincers. Forked: branching into two or more divisions. Fornicute: arched over, bearing a Fornix, pl. fornices : little arched scales in the throat of a corolla, as in that of Hound’s-tongue. 534 Foveate: pitted, having fovec or depres- sions of the surface. Foveolate : marked with little pits or ae- pressions ( foveole). Foville: minute particles in the fluid contained in pollen, 286. Free: separate ; not united with dis- similar parts, 250. Fringed : see Fimbriate. Frond: the foliage or Ferns (500), Liverworts (504), &c., 67. Frondescence : the act of leafing. Frondose: leafy, or more commonly it now means frond-like, or producing a frond instead of ordinary foliage, 504. Fructification : fruiting, or the fruit and what attends it. Fructification, organs of : the stamens and pistils. Fruit, 308. Fruit-dots, of Ferns, 501. Frumentaceous: producing starch, or re- lating to corn ( frumentum). Fristulose : consisting of small portions or fragments. Frutescent : becoming shrubby. Fruticulose: very small and shrubby. Friticose: shrubby ; relating to a Frutex : a shrub. Fucacez, 509. Fugacious : falling off or perishing very carly, as the calyx of the Poppy, and the corolla of Cistus; 172. Fulerate: belonging to or furnished with Jfulera (props), i. e. with append- ages such as tendrils, prickles, stip- ules, &e. Fuliginons, ov fidiginose: sooty; dark and deep brown. Fulvous: tawny: orange-yellow mixed with gray. Fumariacee, 389. Fundamental organs, 70. Fungi, 507. Fungiform: mushroom-shaped. Fungilliform: diminutive of the last. Fungose: spongy in texture. Funiculus : the secd-stalk, 297, 321. Funnel-shaped, funnel-form: sec Infun- dibuliform, 277. Furcate: forked, the forks spreading. Furfuraceous : scurfy. Furrowed : see Sulcate. Fuscous : grayish-brown. Frisiform : spindle-shaped ; 84, fig. 138. Fuastic, 475. Galbanum, 427. Galbilus: a fleshy and closed strobile imitating a berry, as a Juniper- berry, 320. GLOSSARY AND INDEX. Galea: a helmet; an arched sepal or petal, 278, fig. 458. Gdleate: having, or shaped like, a hel- met. Galingale, 490. Galls, 477. Gamboge, 400. Gdmophyllous : composed of Icaves united by their edges, 275. Gamopétalous : composed of united pe- tals, 249, 275. Gamosépalous : of united sepals, 249. Gelatinous coils in cells, 40. Geminate: in pairs. Gemma: a bud or growing point. Gemmation: budding growth, 31. Gémmule: a young bud; the plumule. Genera : plural of genus. General: the opposite of partial ; as the General involucre of a compound um- bel, &e., 216: Generic: relating to the genus. Geniculate: bent abruptly like a knec. Gentianacer, 456. Gentianine (Gentian), 457. Genus, 358. Geographical Botany: the study of plants in respect to their geograph- ical distribution. Geraniacese, 403. Germ: the eye of a bud; or any grow- ing point; or an embryo, 323. Germen: an old name for the ovary. Germinal vesicle, 806. Germination : growth of the embryo from the seed, 71, 328. Gerontogéous: belonging to the Old World. Gesneriaces, 44. Gibber; an enlargement, or gibbosity of any sort, on one side of a calyx, a fruit, &e. Gibberose or gibbous: swollen or en- lareed on one side. Gills of Fungi, 500. Ginger, 490. Ginseng, 428. Glabrous : smooth, i. ¢, destitute of hair- iness. Glabrate : smoothed, or becoming near- ly glabrous. Gladiate: sword-shaped. Glands: any scercting apparatus, 52. The name is also given to any pro- jection or appendage the nature and function of which is not obvi- ous, 264. Glans is also the classi- cal name of an acorn and chestnut. Glandular, glanduliferous, glandulose : bearing glands, or gland-like in texture. Glandular hairs, 52. GLOSSARY AND INDEX. 53 Glandular woody tissue, 43. Glareose: growing in gravelly placcs. Glaucescent : verging upon or slightly Glaucous : covered with a whitish bloom, which rubs off, as the surface of a cabbage-leaf or a plum, or so whitened as to appear to have a bloom, 56. Globose : spherical or nearly so. eee : nearly globose or spheri- cal. Glochideous, or glochidiate: barbed ‘ hooked back ‘at the point, like the barb of a fish-hook, or with two or more such barbs at the point. Glomerate : clustered into a Glomerule: a capitate eyme, i.e.a cyme condensed into a head, 219. Glossology: the department of Botany which explains the technical terms of the science, 15. Glumaceous: bearing, or resembling glumes. Glune: one of the husks or chaff of Grasses, &c., 497. Glumelle ; an inner glume or palea. Gluten, 197. Glutine, 198. Gonophore : a stalk elevating both sta- mens and pistil, 267. Gooseberry, 421. Gossypine: cottony. Gourd (a pepo), 423. Grafting, 100. Grain, 314. Graminex, 497. Granadilla, 422. Granular : composed of grains or gran- ules. Granulate: composed of little kernels or coarse grains. Granules ; any minute particles. Grape, 408. Green layer of the bark, 121. Grossulaceze, 420. Grumous, or grumose: consisting of clustered grains. Guaiacum, 405, Guava, 418. Gum Animi, 400. Gum Arabic, 414. Gum Elemi, 407. Gum Traga- eanth and Senegal, 414. Gutta-percha, 57. Guttate : sprinkled with colored dots or small spots. Guttiferse, 400. Gymnocdrpous : naked-fruited. Gymnospermia, 315. Gymnospérmous ; naked-seeded, 296. Gymnosperms, or Gymnospermous Plants, 297, 371, 479, Gynécium : the pistils of a flower, 223. or Gynandria, 513 Gyndndrous : stamens borne on the pis- til, especially on the style; 253, 281, fig. 468. Gynobase: the base of a style, or sum- mit of a receptacle, on or around which two or more carpcls are in- serted, as in Rue, Sage, Geranium, &e., 267. Gynophore: the stalk of a pistil, 267. Gyrale or gyrose: bent round, or bent back and forth. Habit (Habitus): the general aspect of a plant. Habitat: the habitation, or situation in which a plant is naturally found. Hackberry, 474. Ilematine, 414. Hemodoracer, 492. Hairs, 52. Hairy: clothed or beset with hairs, which are separately distinguish- able. Halberd-shaped, or Halberd-headed : see Hastate. Halorager, 420. Halved ; sec Dimidiate ; appearing as if one half was absent. Hamamelacex, 425. Lamate, ov hamose: hooked. Ilémulose: diminutive of hamate. Hastate: halberd-headed ; shaped like a halberd, viz. with a spreading lobe at the base on each side; 157, fig. 250. Hazel-nut, 476. Head: see 320, &e. Headed : same as capitate. Fleart-shaped : sce Cordate. Feart-wood, 35, 124, 126. Hebetate: blunted, having a soft obtuse Capitulum; 213, fig. point. Helicoid: coiled into a helix or snail- shell, or tending to be rolled up; as in Fig. 332. Helmet: see Galea, 278. Helobious : living in marshes. Helvolous: grayish-yellow mixed with some red. Hemi- in Greek derivatives: halved or half; as Hemi-andtropous: half-anatropous. Heémicarp : a half-fruit of Umbellifere ; same as mericarp. Hemétropal, or hemitropous : nearly the same as amphitropous. Hemp, 475. Hepatice, 503. Hepta ; the Greck numeral seven, used in the following compounds. 536 Heptagynia, 515. Heptdgynous: haying seven pistils or styles. Heptémerous: the parts in sevens. Heptandria, 512. Heptdndrous : with sevea stamens, 280. Heptapetalous : of seven petals, 276. Herb, 101, Herbaceous : not woody ; of a soft text- ure like an herb, 101, 102. Herbarium : the botanist’s collection of dried specimens of plants, 518. Hermdphrodite: bisexual, 261. Hesperidium: a firm-rinded berry like an orange, 311. Fetero-, in Greek derivatives : unlike; as Heterocdrpous: having two kinds of fruit. Heterocéphalous: bearing two kinds of heads ; as in Baccharis. FTeterodrémous, 140. HHeterdgamous: bearing two sorts of flowers, 436. Heterogeneous : of two or more kinds. Heterétropous, or heterdtropal, ovule or seed : same as amphitropous, 300. Flexa-, in Greek derivatives ; six. Hexagynia, 515. Hexgynous: having six pistils styles. Hexdmerous : the parts in sixes, 234. Hexandria, 512. Hexdndrous : with six stamens, 279. Herapétalous: six-petalled, 276. Hexaphillous: six-leaved, 275. Hexdpterous : six-winged. Hexasépalous: with six sepals, 272. Hexustémonous : having six stamens. Hickory-nut, 476. Hidden-veined : where the veins are not visible, as those of the leaves of Pinks and Houselecks. ffilar : yvelating to the hilum. Hilum: the scar, or point of attachment of the seed, 297, 321. Hippocastanacez, or Hippocastanez, 410. FHippocrépiform : horseshoe-shaped. Hirsute: clothed with coarse hairs. Hispid: beset with stiff bristly hairs. Hoary: gvayish-white from a fine pu- bescence. Homocarpous: bearing fruits all of one kind, Homodrémous, or homodromal, 140. Homoéyamous : when all the flowers of a head, &c. are alike, 436. Homogencous : all of the same nature or structure. Homologous: of the same name; said of parts which are of the same morphological nature ; e. g. bracts, sepals, petals, stamens, and sim- or GLOSSARY AND INDEX. ple pistils are homologous with leaves ; 225, 231. See Analogous. Homologue: an homologous part. LHomomatlous (leaves, &c.): originating all round an organ, but directed or curved round to one side of it. Homomorphous : of one form. Homotropous, or homotropal (embryo) : curved in the same way as the seed, as in the Chickweed, fig. 621. Hops, 475. Horny : see Corncous. FTorizontal system, 50, 112. Hortus Siecus: same as herbarium. Huckleberry, 439. F Humifuse : spreading flat on the ground. Humus, Humic acid, 57. HTjaline : transparent, or partly so. Hybrid: a cross-brecd between individ- uals of two species, 337. Hydrangier, 425. Hydrocharidacex, 487. Hydroleacex, or Hydrolex, 452. Hydrophyllacee, 451. Fideaphores a water-plant. Hydropterides, 502. Fe ert belonging to winter. yménium: the gills of Mushrooms, &c., 507 Hymenophylleze, 501. Hypdnthiun : anaked fleshy receptacle, like a fig. Hypericacese, 394. LMypo-, in Greek derivatives : under. ypochilium : the under part of the lip of Orchids, when jointed or other- wise distinguishable. Hypocratériform, or, more properly, LHypocraterimérphous : — salver-shaped ; i.e. with a limb spreading flat at right angles to the tube; 277, fig. 457. LHypogéous, or hypogean (flowers or fruits): borne under ground, 76, 78, 328. Hypojynous: growing under the pistil, and free, 250, 268, 280. Ayjpophyllous: growing on the lower side of a leaf. Hysteranthous : plants whose leaves ap- pear later than the blossoms, as the Red Maple. Hysterophytal : living on a matrix, cither of dead or living organic matter. Hysterophytes : same as Fungi, &e. Icos-, in Greek compounds: twenty. Icosandria, 512. Icoséndrous: having 20 stamens or more inserted on the calyx, 280. Illecebree, 396. Imbibition, 177. GLOSSARY Inbricate, imbricated, imbricative: over- lapping, the outer covering the in- ner, and breaking joints, like tiles on a roof, 144, 269. Inmarginate: not margined. Inmersed : growing wholly under water. Inpari-pinnate: pinnate with an odd leaflet ; 163, fig. 288. Imperfect flowers: wanting either sta- mens or pistils. Impregnation : same as fertilization. Inane: empty. Incanous: hoary-white. Incised: cut irregularly and sharply; 159, fig. 259. Included: not projecting beyond; en- closed. Incomplete flower: wanting some one or more kinds of organs, 259. Incrassated: thickened. Incrustations in cells, 58. L'ncubous : the apex of each leaf lying over the base of the next, as in many Hepatice. Incumbent: leaning or lying upon: said of the cotyledons when the radicle lays against the back of one of them, 390, 326, fig. 705; or when the anther lies on the inner side of the filament, 282. Incurved: bent or curved inwards. Indefinite: either uncertain in num- ber, or too many to be readily counted, 242. Indefinite growth, 100. Indefinite inflorescence, 210. Indehiscent (fruits): not opening, at least not in a regular way, 310, 313. Indeterminate inflorescence, 210. India-rubber, 57. Indigenous : of spontaneous and original growth in a country. Indigo, 414, 415. Individual, 20, 131, 352. Individuality, 132, 352. Indumentum: any hairiness or downy covering. Indiplicate: bent or folded inwards, 145, 273. Indisium: the proper covering of the fruit-dots of Ferns; any peculiar membyanous covering, 501. Inequilateral: unequal-sided. Inferior : underneath, 252; or same as anterior: thus the inferior petal, &c. is the same as the anterior one, 237. Inflated: bladdery. Inflexed: abruptly bent inwards. Inflorescence, 209. Infra-avillary: originating below the axil. AND INDEX. 537 Infundibular, infundtbuliform: funncl- shaped ; i. e. a tube enlarging up- wards ; 277, fig. 1049. Innate: borne directly on the apex of a thing, 282. Innovations : new shoots or new growths. Jnoryanic : unorganized, Inorganic constituents, 179. Inosculating : opening into each other; anastomosing, 49. Inserted: attached to, 224, 250. Insertion: the place or the mode of june- tion of lcaves with the stem, &c., 133. Inter-, in composition : between ; as Intercellular : between the cells. Intercellular spaces or passages, 24, 50. Intercellular system, 50. Interlaced tissue, 48. Internal glands, 51. Internodes, 92. . Interpétiolar : between the petioles, 171. Interruptedly pinnate, 164, fig. 285. Intine: the inner coat of a pollen-grain. Intrafoliaceous: within or before a leaf, 171, as the stipules in fig. 305. Introflered: bent strongly inwards. Introrse: turned inwards towards the axis, 282. Intruse: appearing as if pushed inwards or indented. Inverse: inverted ; suspended. Involucéllate: furnished with an Incolucéllum, or tnvoluccl: a secondary or partial involucre, 216.’ Invohicrate: provided with an Invohicrum, or involucre: an outer or accessory covering ; a set of bracts surrounding a flower-cluster ; 214, fig. 321, &e. Involute : rolled inwards, 144, 273. Ipecacuanha, 393, 433. Tridaceze, 490. Irregular :_ unequal in size or in shape, 253, 277. Trregularity, 253. Irritability, 345. Lsdchroiis : one-colored. Tsoétinese, 502. Isomerous, or isomeric : the parts equal in number. Isostémonous : the stamens as many as the petals or sepals. Jalap, 455. Jasminacee, 459. Jelly, 55, 310. Jointed: separate or separable trans- versely into pieces (joints), 92. Juba: a loose panicle, as of Grasses. Juga: the ridges of the fruit of Umbel- liferee, 426. 538 Juga: the pairs of partial petioles or leaflets of « pinnately-compound leaf, 164. Juglandacex, 476. Jujube, 408. Julus : a name for a catkin. Julaceous : shaped like or resembling a catkin. Juncacer, 495. Juncagines, 487. Jungermanniaceer, 505. Juniper-berries, 480. Jute, 400. Keel: see Carina, 254. Keeled: furnished with a keel or sharp ridge underneath. Kernel of an ovule, 297, or seed, 322. Key-fruit, 314. Kidney-shaped: see Reniform ; 157, fig. 245. Kingdom, 362, 15. Kinic acid, 433. Kino, 414. - Knot: sce Node, 92. Knotted : a cylindrical body swollen into knobs at intervals. Krameriacex, 412. Labélum: the lip, or lower petal of an Orchidcous Hower. Labiate, 450. Ladbiate: two-lipped, 278. Labiatiflore, 436. Lac, 475. Laciniate: slashed ; cut into narrow in- cisions ; these are called Jacinie. Lactescent: yielding milky juice. Ladcunose: full of depressions or exca- vations (laciine). Lacistrine: belonging to lakes. Ladanum, 394. Leevigate: smooth as if polished. Lagéniform: shaped like a Florence flask (/dgena). Lalo, 399. Lame: thin plates, like the gills of an Agaric, 507, &c. Lédmellar, ox lémellate: composed of flat plates. Lémina (a plate): the blade of a leaf, petal, &c., 145, 276. Lanate, lanose: woolly; i. e. clothed with soft interlaced hairs. Lédneeolate: lance-shaped ; fiz 239. Laniginous: cottony or woolly. Latent buds, 167. Lateral: belonging, or attached to, the sides of an organ. Latex: milky or proper juice, 49. Laticifcrous tissue or vessels, 49. Lauracese, or Laurincee, 466. GLOSSARY AND INDEX. Lax: loose; the opposite of close or crowded. Layering, 102. Leaf, 138. Leaf-arrangement (phyllotaxis), 133. Leaf-bud, 72, 93. id Leaf-qreen, 58. Leaflet : a separate piece or partial blade of a compound leaf, 163. Leaf-stalk, 145, 170. Leaf-scars, 94. Leathery : see Foliaceous. Legume: a fruit like a Pea-pod, 315. Legumineg198. Leguminose (Leguminous Plants), 412. Leguminous: relating to legumes. Lemnacee, 486. Lemon, 401. Lentibulacez, 445. Lenticels : little spots on the bark, whence roots often issue. Lenticular : lens-shaped ; double-convex. Lentiyinose: freckled, or dusty-dotted. Lepals : sterile transformed stamens. Lepidote : leprous ; scaly or scurfy, 52. Leucanthous : white-flowered. Liber : the inner fibrous bark, 120, 127. Lid: see Operculum, 502. Lichenes (Lichens), 505. Lichenology : the part of Botany devoted to Lichens. Licorice, 414. Ligneous : woody in texture. Lignine, 36, 195. Lignum-vite, 405. Ligulate: strap-shaped, 255; having a Ligule: a strap-shaped corolla, 255, fig. 325, d; the appendage between the blade and the sheath of the leaf in Grasses, 170. Liguliflore, 436. Liguliflorous: when a head consists of ligulate flowers only, as Cichory, fig. 323. Liliaceere, 493. Liliaceous: lily-like, 276. Limb (limbus, a border); the expanded part or border of a corolla, calyx, &c., or the lamina or blade of a petal, &c., 145, 276. Limbate: bordered. Lime, 401. Limnanthacee, 404. Linacew, 402. Line: the twelfth of an inch. (In deci- mal measures, the tenth of an inch.) Linear: narrow and much longer than broad, the two margins parallel ; fig. 240. Lineate: marked with lines. Lineolate : marked with fine or obscure lines. GLOSSARY AND INDEX. Linguiform, or lingulate: tongue-shaped, as the leaves of Hound’s-tongue. Lip: the two lobes a bilabiate calyx or corolla; the lower petal of an Orchidcous plant. Littoral, or litoral: growing on shores. Livid : pale lead-color. Loasacee, 421. Lobe: any division or projecting part of an organ, especially a rounded one, 275. Lobed, lubute: divided into lobes ; fig. 260, 264. Lobeliacex, 438. Lbulate : bearing small lobes (/ébuli). Locellute: having secondary cells (or locelli). Loceéllus (plural, locelli) : a secondary cell, or a division of a cell. Loculament, 316 ; same as loculus. Locular : having cells. Loculicidal, or loculicide: dehiscence opening directly into the back of a cell; 316, fig. 583, 585. Leeulose: partitioned off into cells, as the pith of Poke, &c. Loculus (plural, loculi): the cells of an _ ovary, anther, &e. Locista : a spikelet or flower-cluster of Grasses. Ledieules (lodicule): the minute scales inside of the paleze of Grasses, 497. Loganiacer, 433. Logwood, 414. - Loment: a jointed legume; 3815, fig. 581. Lomentaceous : bearing or resembling a loment. Longitudinal tissue or system, 45, 50, 112. Lonicerex, 431. Loranthacex, 469. Lorate: thong-shaped. Lucid: shining. Lunate: crescent or half-moon shaped. Lninulate : diminutive of the last. Lupuline : waxy grains “on the scales of Hops. Lurid: dingy brown. Lutescent : yellowish. (Luteus : yellow). Lycopodiacee, 501. Lycotropous, or lycotropal : an orthotro- pous ovule curved into a horse- shoe form. Lyrate, lyre-shaped, 161, fig. 138, 278. Lyrately pinnate, 164, fig. 285. Lythrace, or Lythariez, 418. Mace: the arillus of Nutmeg, 322, 383. Muaculate: spotted or blotched. Madder, 482. Magnoliacee, 381. Mahogany, 401. 539 Maize, 498. Male flower, 261. Malpighiacez, 409. Malpighiaceous hairs: hairs fixed by their middle, as in the foregoing order, in Cornus, &c. Malvacee, 397. Mamillate, or mdmillar: bearing little prominences on the surface. Maémmeform : teat-shaped. Mammee-apple, 400. Mammose: bearing larger prominences, like breasts. Mango, 406. Mangosteen, 400. Mancate (gloved): covered with a woolly coat which may be stripped off whole. Manilla hemp, 490. Manna, 460. AMany-cleft: cut as far as the middle into several divisions, 159. Many-headed: see Multicipital. Marantacee :; see Cannacese Marcescent: gradually withering with- out falling off, 279. Marchantiaces, 504. Marginal: belonging to the margin. Marginate: furnished with a margin of different texture or color from the rest. Maritime: belonging to the sea-shore. Markings on cells, 3, 6. Marmorate: marbled. Marsiliacese, 502. Mas: male, masculine; belonging to the stamens. Masked : see Personate, 278. Mealy : see Farinaceous. Medal: belonging to the middle. Medilla: pith, 118. AMeédullary rays, 117, 119. Medullary sheath, 119. Medullose, or medullary : pith-like. Meiostémonous: having fewer stamens than petals. Melanospermez, 509. Melanthacez, 494. Melastomacez, 418. Meliacez, 401. Melon, 423. Membranaceous, or membranous: thin and soft, like a membrane. Meniscoid: shaped like a meniscus or concavo-convex lens. Menispermacee, 383. Menyanthidew, 457. Merénchyma, 41. Meéricarp: half a cremocarp, 426. Merismdtic: dividing into parts, 28. Meérithall : a name for an internode. Merous, in Greck compounds: the purts 540 GLOSSARY of a flower: see Dimerous, Trime- rous, &e. Mesembryanthemacee, 397. Mesocarp: the middle layer of a peri- carp, 310. Mesophiéum : the middle bark or green layer, 121. Mesophyllum: the parenchyma of a leaf between the skin of the two sur- faces. Metamorphosed: that which has under- gone. Metamorphosis: the transformation of one organ into another homologous one, 228, 231. Micropyle: the orifice of a seed, 298. Midrib : the central or main rib, 155 Milky juice, 49. Mimosez, 413. Mineral constituents of plants, 179. Winiate : vermilion-color. Mitriform : mitre-shaped, 503. Molluginem, 395. Monadelphia, 513. Monadelphous : with filaments united into a tube, or ring; 280, fig. 462. Monandria, 512. Mondnd: ous: with a single stamen, 279. Monduthous : onc-flowered. Moniliform: necklace-shaped ; cylin- drical and contracted at intervals. Monimiacee, 382. Monkey-bread, 399. Mono-, in Greek compounds: one or single. Monocdrpellary : of one carpel. Monocdrpic, or monocdrpian : once-fruit- ing, 101. Monocéphalous : bearing a single head. Monochlanujdeous ; with a single floral envelope; i. c. apetalous, 260. Monoclinous : hermaphrodite. Monocotylédonous : one-cotyledoned, 79, 326. Monocotyledons or Monocotyledonous Plants, 113, 326, 370, 482. Moneecia, 513. AMonecious: stamens and pistils in sep- arate flowers on the same individ- ual, 262. Monogamia, 516. Monogynia, 515. Monoéyynous: with one pistil or style, 287. Monoicous : same as moneecious. Monémerous: the parts of the flower single, 234. Dfonopétalons: one-petalled, but it is used for gamopetalous, viz. petals more or less united into one body, 249, 275. Monophyllous : one-leaved, of one piece, 275. AND INDEX. Mondpterous: one-winged. Afonopyrenous : one-stoned. Jfonosepalous : the calyx of one picce, 249, AMonospérmous: one-seeded. AMondstichous: in one vertical rank, 134. Mondstylous ; with one style. Monotropex, or Monotropacex, 440. Aonster, monstrous (430): developed in an unnatural manner, Morphine, 57. Morphology, 14, 60, 224. Morphosis: the manner of development. Moschate* exhaling the odor of musk. Moulds, 65. Alucilage: dissolved vegetable jelly, or dextrine, 55, 193. Mucilaginous, mucose, or mucous: slimy. AMucro: a short, sharp point. Aicronate: abruptly tipped with a mu- cro; 162, fig. 276, 231. Mucrénulate: tipped with a minute mu- cro. Mulberry, 475. Afde: a hybrid. Alultangular : many-angled. Afuti-, in Latin derivatives: many; as, Méulticipital (milticeps) : many-headed ; where several buds or shoots pro- ceed from the crown of one root. Multifarious : many-sided. Ahiujid: many-cleft, 159. Multifldrous ; many-flowered. AMidtijugate: in many pairs. Multilocular : many-celled. Afultiple: compound. Multiple fruits, 309, 318. Afutisérial: in several horizontal ranks. Maultiseptate: many-partitioned. Miiricate+ rough with short and hard points. Muriculate: minutely muricate. Musacee, 490. Muscardine, 508. Muscariform: 6rush-shaped. Musci (Mosses), 502. Musciform: moss-like. Afuscology: the department of Botany which treats of Mosses. Mustard, 389. Ahiticous : pointless ; blunt. Mycelium, 507. Ayodtogys or Mycetology: the depart- ment of Botany which treats of Fungi. Afjcropyle: sce Micropyle. Myricacee, 477. Myrsinacer, 443. Myristicacex, 383. Myrrh, 407. Myrtacee, 418. GLOSSARY AND INDEX. Naiadacee, 487, Naked flowers: same as achlamydeous ; or destitute of involucre, &c. Naked ovules and seeds, 296, 320. Names of species and genera, 363; of orders, tribes, &c., 373. Népiform: turnip-shaped, 84. Natant: floating under water. Natural system, 365, 366. Naturalized: species introduced, but growing completely spontaneous, and propagating by seed. Navicular: boat-shaped. Nebulose: clouded. Neck: the junction of root and stem. Necklace-shaped : see Moniliform. Nectar : the honey of a flower, or any sweetish exudation. Nectary (nectarium): a place or thing in which nectar is secreted: for- metly applied also to any anoma- lous part or appendage of a flower, whether known to secrete honey or not, as to the spur-shaped petals of Aquilegia, fig. 647, or the two singular-shaped petals of Aconi- tum, 257, fig. 402, 404. Needle-shaped: see Accrose. Nelumbiacee (Nelumbo), 385. Neémeous: filamentose; composed of threads. Nervation: the arrangement of the Nerves: parallel and simple veins. Nerved : nervate ; furnished with nerves, 154. Nervose: abounding in nerves. Netted : same as reticulated. Netted-veined, 154. Neurose: same as nervose. Neutral: without sexes. Neutral flowers: having neither stamen nor pistil, 263, 436. Neutral quaternary products, 196. New Zealand Hemp, 492. Miduant: nestling in. Nitid (nitidus): smooth and shining. Miveous : snow-white. Nodding: curved so that the apex hangs down. Node (knot): the place on a stem where a leaf is attached, 92. Nodose : knotty ; swollen in some parts, contracted at others. Nodulose: diminutive of the last. Normal: according to rule. Notate: marked by spots or lines. Notorhizal: the radicle bent round to the back of one cotyledon ; same as incumbent. Nucumentaceous : nut-like. Micelle: same as nucleus. Miciform: nut-like. 46 541 Nucleus: the kernel, 297, 320, 322. Nucleus of a ‘cell, 26. Nuculanium : a name for a berry like a grape. Micwe: a diminutive nut, stone, or kernel. Miculose: containing nucules or nut- lets. Numerous: same as indefinite. Nut, 314. Nutlet : a small nut, or the small stone of a berry-like drupe. Nutmeg, 383. Nutant : nodding. Nutrition, 61, 177. Nux-vomica, 434. Nyctaginacez, 463. Nymphzacezx, 385. Oat, 498. Ob- (over against) signifies inversely ; Obcompressed : flattened fore and aft, in- stead of laterally. Obcordate: heart-shaped inverted ; 162, fig. 274, 233. Obldnceolaute : lance-shaped, but broader upwards. Oblique, referring to shape, unequal- sided, 165. Obliteration, 309. Oblong: elliptical, or approaching it, and much longer than wide; fig. 242. Obdvate: inversely ovate ; 157, fig. 232. Obtusg: blunt; the apex an obtuse an- aes 162, fig. 270, 236. Obverse: same as ob. Obvolute: a modification of convolute, 145. Océllate: eyed; a circular patch of , _ color within another patch. Ochrea (a boot): a tubular stipule ; 171, fig. 305. Ockreate: furnished with ochree. Ochroleicous: ochre-colored (pale dull yellow) verging to white. Octo-: eight; in composition in such words as the following. Octagynia, 515. Octdgynous : with eight pistils or styles. Octdmerous : the parts in eights. Octandria, 512. Octdndrous: with eight stamens. Octopétalous: of eight petals, 276. O'culate: eyed ; same as ocellate. Officinal (belonging to the shop): ap- plied to plants, &c. used in medi- cine or the arts. Offset, 102. Oilnut, 469. Oils, 56, 57. 542 Okra, 398. Oleaceze, 459. Oleraceous : of the nature of, or fit for, pot-herbs. Oligo-, in Greek derivatives : few ; as Oligandrous: having few stamens. Oligospérmous : few-seeded. Olive, Olive-oil, 460. Onagracer, 419. One-celled plants, 61. One-sided: see Secund and Unilateral. Ouphoridia: the larger and eompound spores of Lycopodiacez. Opaque: the reverse of shining ; dull. Operculate: furnished with a, lid or Opérculum: a lid, such as that of the spore-case of Mosses, 502. Ophioglossez, 501. Opium, 389. Opposite (leaves, &c.) : opposed to alter- nate, that is, placed over against each other, 78,97, 133, 141. A stamen, &c. is said to be opposite a petal, when it stands before it (248), as in fig. 435 and 670. Oppositifolious: opposite a leaf, as the tendrils of Vitis, fig. 767, and the peduncles of Phytolacea, fig. 1086. Orange, 401. Orbicular : circular in outline. Orchidacez, 488. Orders, 359. Ordinal: relating to orders. Organic constituents, 179, 180. Organization, 17. Organography, 14, 60. Organdgeny : the development ot for- mation of organs, 268. Organs, 18. Organs of Reproduction, 70. Organs of Vegetation, 68, 70, 204. Orobanchacez, 446. Orris-root, 491. Orthoploceous (embryo): with incum- bent and conduplicate cotyledons, as in Mustard. Orthotropous, or orthétropal ovule ; 298, fig. 526. The term when applied to the embryo is used as the con- trary of antitropous, i. e. having the radicle next the hilum, as in an anatropous seed. Osage Orange, 475. Osmundacex, or Osmundinee, 501. Osseous: of the texture of bone. QOuari Poison, 434. Oval: broadly elliptical ; 157, fig. 229. O'vary: the ovule-bearing portion of a pistil, 228, 287. Ovate : egg-shaped, or like the longitu- dinal section of an egg, fig. 241. Ovoid: w solid ovate or oval. GLOSSARY AND INDEX. Ovulate, ovuled, or ovuliferous: bear- ing ovules. ‘ Ovule:” an unimpregnated seed or body destined to become a seed, 223, 297. Oxalidacez, 404. Palate: an inward projection of the lower lip of a personate corolla; 278, fig. 459, 460. Pilea, or pala: a chaff; one of the bracts on the receptacle of Com- posite, 215, 435; one of the inner bracts or glumes of Grasses, 497. Paledceous : chaff-like, or bearing chaff. Paléola: diminutive of palea; one of the minute innermost scales of the flower of: Grasses. See Squa- mella. Palme (Palms), 484. Palinate : lobed or divided so that the sinuses all point to the apex of the petiole, either moderately, as in a Maple-leaf, or so as to make the leaf compound, as in Horsechest- nut, when it is the same as Digitate; 161, 163, 164. Palmately lobed, cleft, parted, &c., 161. Palmately 2 — plurifoliolate, 164. Palmately veined, 156. Palmdifid: palmatcly cleft; fig. 265. Palmdtisect: palmately divided; fig. 267. Paludose, palustrine: inhabiting marshes. Pandanacee, 485. Pandurate, or pandiriform; same as fiddle-shaped. Panicle: « raceme, branched irregular- ly ; 216, fig. 326. Panicled, or paniculate: arranged in a panicle. Papaveracee, 388. Papaw, 383, 422. Papayacer, 422. Papery: of the consistence of letter- paper. Papilionacee, 413. Papilionaceous: butterfly-like, 253. Papillose, or pdpillate: bearing small, soft projections (papillz, nipples or pimples). Pappose, or pappiferous: bearing a Pappus (thistle-down), 260, 314, 435. Papyraceous : papery. Papyrus, 496. Paracorolla : an appendage or duplicate of a corolla, such as was once ealled a nectary. Parallel-veined.or nerved, 154. Pardphysis ; jointed thread-like bodies accompanying the pistillidia of Mosses. GLOSSARY AND INDEX. Parasitic plants, or Parasites: living on the juices of other plants, 88. Parastémon : same as Staminodium. Parénchyma: soft cellular tissue, 41. Parietal: attached or belonging to the walls, 292. Partetes: walls of an ovary, &e. Paripinnate: same as abruptly pinnate, Parnassiacex, 394. Parsnip, 426. Parted, or partite: cut almost through ; 160, fig. 262, 266. Partial peduncle, 211. Partial petiole, 164. Partial umbel, 216. Parthenogenesis, 300, 340. Passifloracese (Passion-flowers), 422. Patélliform : kneepan-shaped. Patent : spreading wide open. Pdtulous: moderately spreading. Pauci-, in Latin derivatives : few ; as Paucifiorous: few-flowered. Peach, 415. Pear, 416. Pear-shaped: ovoid at the extremity, conical at the base. Peéctinate: pinnatifid with close-sct and equal lobes, like the teeth of a comb (pecten), 160. Pectine, and Pectic acid, 55, 310. Pedute: palmate, with the lateral lobes again lobed ; appearing like a bird’s foot, 161, fig. 249. Pedately: in a pedate mode. Pedicel: the stalk of a particular flower, 211. Pédicellate, pedicelled: having a pedi- cel. Pedincle: a flower-stalk in general. either of one blossom or a whole cluster, 211. Pediinculate, peduncled: having a pe- duncle. Peloria, 278. Peliate: shield-form or target-shaped ; fixed by the centre or some part of the lower surface ; fig. 248, 681. Pelitinerved: peltately veined. Pelviform: open cup-shaped. . Pendent, pendulous: hanging down. Penicillate, penteilliform: tipped with a brush of hairs, like a camel’s-hair pencil. Pennate: same as pinnate. Penniform : feather-like. Pénninerved : same as pinnately nerved or veined. Z Penta-, in Greck derivatives: five ; as Pentacdrpellary : of five carpels. ' Pentaccccous: of five cocci. Pentagynia, 515, 548 Pentdgynous : with five pistils or styles, 287. Pentdmerous : fig. 354. Pentandria, 512. Pentdndrous : having five stamens, 279. Pentapetalous : of five petals, 276. Pentaphijllous : five-leaved, 275. Pentdpterous: five-winged. Pentasepalous: of five sepals, 274. Pentdstichous: in five vertical ranks, 135, Pepo: a Gourd-fruit, 312, Pepper, 456, 469. Perennial: lasting year after year, 84. Perfect flower : one having both stamens and pistils, 261. Perfoliate: when the stem appears to pass through the leaf; 165, fig. 293, 294, Pérforate: pierced with holes, or having transparent dots which look like holes. Pergaméneous, or pergamentdceous : like parchment. Peri-, in Greck derivatives ; around. Peérianth (peridnthium): the floral en- velopes collectively, either of one set (calyx) or of two sets (calyx and corolla), 222. Peéricarp: the ovary in fruit, 308. Pericdrpic: belonging to the pericarp. Perichetial: relating to the Peéricheth, or perichetium: the cluster of peculiar leaves surrounding the base of the fruit-stalk of Mosses. Periclinium : a name for the involucre of Composite. Peériderm: same as Epiphloeum. Peérigone, or perigonium ; same as Peri- anth. Perigijnium : bristles or other organs, of doubtful nature, around the pistil in Cyperacezz, 497. Perigynous : borne on the calyx ; liter- ally around the ovary; i. e. when the petals or stamens are adnate to the base of the ovary or to the calyx ; 251, 268, fig. 388, 389, 281. Peripetalous : around the petals. Peripheric: surrounding the circumfer- ence, 325; as the embryo around the albumen in fig. 621. Perisperm: the albumen of the seed, 322, or that albumen which is formed in the tissue of the nucleus, 323. Peéristome, 502. Peritropous, perttropal (secd) : horizon- tal to the axis of the fruit. Perpendicular system of the stem, 112. Persimmon, 443. of five parts ; 234, 239, 544 Persistent: remaining, as the leaves of evergreens through the winter, 172 ; and the calyx, &c. of many plants until the fruit is formed, 279. Pérsonate: masked; 278, fig. 459, 460. Pertuse: having slits or holes. Pérulate: having pérule or bud-scales. Peruvian Bark, 432. Petal: a leaf of the corolla, 222. Pétaline, or pétaloid: petal-like, in color and texture, 260. Pétiolar : borne on the petiole. Peétiolate, petioled: having a petiole. Pétiole: \eafstalk, 145, 170. Petiolulute: the leaflet stalked, 164. Peétiolule: the stalk of a leaflet, 164. Phendgamous, or phanerdgamous : hav- ing manifest flowers, 69. Phenogamous or Phanerogamous Plants, 69, 369, 375. Phalanges: bundles of adelphous or clustered stamens. Phordnthium: the receptacle of Com- posite. Phrymaceex, 450. Phycology : same as Algology. Phylla: leaves, 274. -phyllous : leaved, as 3-phyllous, three-leaved, &e. Phyllodineous : bearing or resembling a Phyllddium: a dilated petiole taking the place ofa blade, 170, Phyllotézis, or phyllotéxy, 183. Physiological Botany, 14, 17. Phytelephantez, 485. Phytography : descriptive Botany. Phytolaccacem, 463. Phytology : Botany in general. Phyton: a simple plant-individual, or plant-element, 96. Phytotomy: vegetable anatomy, 14. Pileate, pileiform: like a cap or Pileus, 507. Pileorhiza: the cap of a root, as found in some aquatic plants; fig. 102. Piltferous: bearing or tipped with hairs ali). Pitos hairy, as distinguished from woolly or downy ; i.c. distinct and straight, but not rigid hairs. Pilosity : hairiness. Pimento, 418. Pine-apple, 492. Piney Tallow, 400. Pink-root, 435. Pinna: one of the primary divisions of a pinnately compound leaf, 164. Pinnate, pinnated: a compound leaf with leaflets arranged along the sides of a common petiole; 163, fig. 288 - 290, Pinnuately cleft, lobed, parted, &¢., 160, GLOSSARY AND INDEX. Pinnately 3-plurifoliolate, &c., 164. Pinnaiely veined, 155, 160. Pinndtifid: pinnately cleft ; fig. 261. Pinndtisect: pinnately divided; fig. 263. Pinnule : a secondary division of a pin- nately compound leaf. Piperaceze, 469. Piperine, 469. Pisiform: pea-shaped. Pistachio-nut, 406. Pistil: the ovule-bearing organ of a flower, 223, 287. Pistillate : furnished with pistils, or pis- tils only, 261. : Pistillidium, 337. Pitch, 480. Pitchers: see Ascidium ; 169, 387, fig. 299-301. Pitcher-shaped : campanulate or tubular, but with a narrower mouth. Pith, 118. Pits, 37. Pitted : marked with small depressions. Pitted tissue, 45. Placénta: the place or part of the ovary which bears the ovules or seeds, 289. Placentation: the arrangement of pla- cente. Plucentiferous: bearing the placentae. Placéntiform : nearly the same as quoit- shaped. Plaited: see Plicate, 273. Plane: flat. Plantaginacer, 444. Platanacezx, 476. Platycdrpous : broad-fruited. Pleio-, in Greek derivatives : full of, or many ; as Pleiospermous : many-seeded, &c. Pleurénchyma : woody tissue, 41. Pleurorhizal : embryo with the radicle lying against the side or edge of the cotyledons; same as accum- bent. Plicate, plicative : thrown into longitu- dinal plaits (plice); folded, 144, 273. Plum, 415. Plumbaginacer, 444. Plumose: feathered ; when bristles, &c. have fine hairs on each side like the plume of a feather, as the pap- pus of Thistles, &.; fig. 890. Plimue: the bud or growing point of the embryo above the cotyledons, 71, 324. Pluri-,in words of Latin origin: sev- eral, at least more than one; as Plurificrous : several-flowered, Plurifoliolate ; bearing several leaflets. GLOSSARY Plurilécular : several-celled. Poculiform: deep cup-shaped. Pod: a dry dehiscent fruit, 315. Pédosperm: sced-stalk, 297. Podostemacex, 471. Pointless: see Mutic6us. Pointletted: same as Apiculate. Polemoniaceex, 453. Pollen: the contents of the anther, 223, 285 Pollen-tube, 286, 302. Pollinia : pollen-masses, 286, 489. Polliniferous: bearing pollen. Poly-, in Greek compounds ; numerous. Polyadélphia, 513. Polyadéiphous: having the filaments in several sets, 280. Polyandria, 512. Polydndrous: with numerous stamens, especially when inserted on the receptacle, 242, 280. Polydnthous : many-flowered. Polyednoes fruiting many times, i.e. year after year; perennial, 101. Polycéphalous : bearing many heads. Polycladous : much-branched. Polyedccous: of several cocci. Polycotylédonous : having several cotyle- dons, 79, 326. Polygalacex, 411. Polygdamia, 513, 515. Poljgamous: having both perfect and separated flowers, 262. Polygonacez, 465. Polyjgonous: many-angled. Polygyna, 515. Poljgynous: with numerous pistils or styles, 287. Pohjmerous : formed of many members. Polymorphous : various in form. Polypétalous: having distinct petals, 249, 275. Polyphore: a common receptacle of many carpels, as in Strawberry. Polyphyllous: — many-leaved or several- leaved, 275. Poly podiaceze, or Polypodinez, 501. Polyrhizal : many-rooted. Palani of two or more distinct sepals, 249, 275. Polyspér mous : many-seeded. Poljsporous: containing many spores. Polystémonous : with many stamens. Pome: an apple, pear, &c., 312. Pomee, or Pomacezx, 416. Pomegranate, 418. Pomiferous : pome-bearing. Pomology: the department of Botany relating to fruits. Pontederiacez, 495. Porose: porous, having holes. Portulacacez, 396, 46* AND INDEX. 545 Posterior (in the flower) : next the com- mon axis, 237. Posticous: same as extrorse. Potato, 456, 455. Pouch: see Silicle, 317. Preefloration: same as /Estivation, 269. Prefoliation: same as Vernation, 143. Premorse: as if bitten off. Prickly : armed with Prickles, 52. Prinine: outer coat of the ovule, 298. Primordial leaves, 143 ; utricle, 26. Primulacee, 443. Prismatic, prismatical : with flat longi- tudinal faces, separated by angles. Process: any projection from a surface. Procumbent: lying along the ground, 102. Produced: prolonged or extended. Pro-embryo, 338. Proliferous (bearing offspring) : develop- ing new branches, flowers, &c. from the older ones, or from unusual places. Prone: lying face downwards, Proper juices, 57. Prosénchyma, 41. Prosénthesis, 236. Prostrate : lying flat on the ground, 102. Proteacez, 468. Proteine, 27, 53, 57, 196. Proterdnthous : where flowers are pro-- duced earlier than the leaves. Prothdllus, or protothallus, 338. Protophytes: Algz and Lichenes are so called. Préotoplasm, 26, 53, 57, 196. Priinate, priinose: as if frosted over: Priniform: plum-shaped. Pseudo-bulb : a kind of corm, as of epi-- phytic Orchidacez. Pseudo-parasitic: same as epiphytic. Pterocdrpous : wing-fruited. Pteroid: wing-like. Pubéscent : clothed with soft or downy hairs, or pubescence. Pugioniform : dagger-shaped. Pulque, 491. Pulse, 413. Pulveraceous, or pulvéfulent: dusty or powdery on the surface. Pilvinate : cushioned. Pulvinus (a cushion) : an enlargement at or below the base of a leafstalk. Pumpkin, 423. Punctate: dotted as if by punctures. Pungent : pricking ; rigid-pointed. Piistulate: blistered. Putdmen: the stone or shell of a drupe,. 310, 312. Pyréne: the stones of small drupes ;. same as nucules, 546 Pyriform : pear-shaped. Pyrolex, or Pyrolacee, 440. Pyzxidate : furnished with a lid, like a Pyxidium, or pyzis: a pod opening by a lid; 317, fig. 575, 588, 950, &c. Quadrdngular : four-angled. Quadri-, in Latin compounds: four. Quadrifurious: in four vertical ranks. Quddrifid ; four-cleft. Quadrifoliate: four-leaved. Quadrifoliolute : of four leaflets. Quadrijugate : four-paired. Quadripartite: four-parted. Quandang-nuts, 460. Quassia, 405. Quatérnary : consisting of four, 239. Quaternary products, 53, 57, 196. Quatérnate: in fours. Quercitron, Quercine, 476. Quin-, in Latin compounds: five in number. Quinary : consisting of five, 234, 239. Quinate : in fives. Quince, 416. Quincuncial : five-ranked ; ina quincunx, 135, 270. Quinine, Quinia, 57, 433. Quinquefarious : five-ranked. Quinquefoliate: five-leaved. Quinquefoliolate: of five leaflets, Quinqueldcular : five-celled. Quinquina Bark, 433. Quintuple : dividing into five parts. Quintuple-ribbed, or Quintipli-nerved, 156. Race: a variety perpetuable by seed, 356. Réceme : an indefinite inflorescence with single pedicelled flowers arranged along a prolonged axis; 211, fig. 307. Racemiferous: bearing racemes. Racémiform: resernbling a raceme. Récemose: bearing or resembling ra- cemes. Rachis : see Rhachis. Radial: belonging to the border or ray. Rédiate, radiant: spreading from or arranged around a centre; having rays. Rédiatal-veined, 156. -Rédicul: relating to the root (radiz). Radical leaves : those apparently spring- ing from the root, 143. Rédicant: rooting. Radicel: a diminutive root or rootlet. Radicifiorous: flowering from the root, or apparently so. Redon : appearing like a root. Radicle: a diminutive root; the part of GLOSSARY AND INDEX. an embryo below ‘the cotyledons, 71, 324. Radii: rays. Rafflesiacese, 463. Ramal, or rameal: relating to branches, 143, Raménta, raments: thin chaffy scales in place of hairs. Ramentdceous : bearing raments, as the stalks of many Ferns. Ramification, 97. Ramiflorous: flowering on the branches. Ramose: bearing branches (ram) ; branchy. : Rdmulose: bearing many branchlets (rdmult). Ranunculacce, 380. Raphe: see Rhaphe. Raphides : crystals in plants, 59 Rare: thinly set; sparse or few. Raspberry. 416. Ray: the marginal flowers of a head, when different from the rest, 436; the branches of an umbel, &c. Ray-flower, 436. Receptacle of the flower, 224, 266. Receptacle of inflorescence, 211, 215. Recess: same as sinus. Reéclinate, reclined: falling or turned downwards. Rectinerved : parallel-veined. Rectisérial : in rectilinear ranks, 141. Reciirved: curved, especially curved backwards. Redhiiplicate, reduplicative, 273. Refiexed : bent downwards or back- wards. Refracted: suddenly bent backwards. Regular : the members alike in size and form, 239, 277. Réniform: kidney-shaped ; same as round-heart-shaped, but the breadth greater than the length; fig, 245, Repdnd : bowed, the margin obscurely sinuate, 159, fig. 257. Répent: same as creeping, 102, Replicate: folded back. Replum (a door-case) ; the frame-like placente of Papaveracee, &c. from which the valves of the pod fall away in dehiscence. Reproduction, 20, 21, 61 ;—in Cryptoga- mous plants, 330. Reproductive organs, 70. Reptant : same as repent. Resedacez, 391. Resins, 195. Respiration, 178, 199, 202. Restiacese, 496. Restipinate : underside up, or having that appearance. Reticulated : netted, 154. GLOSSARY AND INDEX. Reticulated ducts, 46. Retindcutum: a stay or holdfast: ap- plied to the processes bearing the seeds of Acanthacer, &c. Rétinerved : same as reticulated. Retrocirved: same as recurved. Retrofléxed : same as reflexed. Retrofracted: same as refracted. Retrorse: backwards, directed back- wards. Retrovérted: turned upside down. Retiuse: slightly notched at a rounded apex ; 162, fig. 272. Révolute, revolitive: rolled backwards, 144. Rhachis (back-bone): the axis of a spike, &c., 211. Rhamnacee, 408. Rhaphe of an ovule or seed, 299, fig. 529, r. Rhatany, 412. Rhizdnthous: root-flowered ; as when a flower (like Rafflesia, fig. 150), or a cluster of flowers, &c. without green foliage (like Becch-drops), is parasitic by what answers to roots, on some foster plant. Rhizocérpous (root-fruiting) : having a perennial root. Rhizéma: rootstock, 106. Rhizomorphous : root-like. Rhizophoraces, 419. Rhodospermez, 509. Rhombic : rhomb-shaped. Rhomboidal: approaching a rhomboid in form. Rhubarb, 466. Rib: astrong nerve or part of the frame- work of a leaf, &c , 145, 155. Ribbed: when strong nerves or ribs run lengthwise through a leaf, &c. Ricciacer, 504. Rice, 498. Rimose : with chinks or clefts (rime). Ring of Ferns, 501; of Mosses, 503. Ringent: grinning; when a, bilabiate corolla is open, 278. Riparious: along water-courses. Root, 79. Root-hairs, 81. Rootlet : a very small root, or ultimate branch of a root. Rootstock : same as rhizoma, 106. Rosaccee, 415. Rosaccous: rose-like, 276. Rostellute: diminutive of rostrate. Rostéllum : a little beak. Roéstrate : beaked, bearing a Rostrum : a beak-like projection. Rosular, or rosulate: shaped like a ro- sette. : Rotate ; wheel-shaped ; 278, fig. 454. 5AT Rotation in eclls: see Cyclosis, 31. Rotind, rotindate ; of rounded outline. Rough: see Scabrid or Scabrous. Rubescent, rubicund : reddish or rosy. Rubiacee, 431. Rubiginose : rusty reddish. Rideral : growing in rubbish. Rudimentary: imperfectly or incom- pletely developed. Rufescent : approaching to Rufous: brown-red. Rugose : wrinkled (ruga, a wrinkle). Riminated (albumen) : penctrated with holes or channels ; 323, 383, fig. 658. Rincinate: saw-toothed, the teeth tumed backwards, 161, fig. 279. Runner, 102. Running, 102. Rupestrine : growing naturally on rocks. Ruptile: bursting irregularly. Rusty: see Ferrugineous. Rutacez, 405. Rye, 498, Sdbuline, or sdbulose: growing in sand. Saccate, sdcciform: sac-shaped, 278. Sac of the amnios, 304. Saffron, 491, 437. Sdgittate: arrow-headed, or arrow- shaped ; lanceolate with a lobe at the base on each side pointing backwards ; fig. 252. Sago, 481, 485. Salep, 489. Salicacese, or Salicinix, 478. Salicine, 478. Saline, salsuginous: growing in salt places, or impregnated with salt. Salver-shaped: tubular and the border spreading flat at right angles to the tube ; 277, fig. 457. Salvinieas, 502. Sdmara: a key or winged indchiscent fruit, 314, fig. 577, 578. Sdmaroid: resembling a samara. Sambucee, 431. Sandal-wood, 414, 469. Santalacez, 468. Sap, 58, 190. Sapindacez, 409. Sap-green, 408. Sapodilla Plum, 443. Sapotacee, 443. Sap-wood, 35, 124, 126. Sdrcocarp: the fleshy part of a drupe, 310, 312. ; Sarmentdceous : bearing or resembling Sarments : runners or long and flexible branches. Sarraceniacce, 387. Sarsaparilla, 493. 548 Saururacee, 469. Saw-toothed: same as Serrate. Sdzatile: living in rocky places. Saxifragacex, 424. Scabrate, scabrid, or scabrous: rough to the touch. Scaldriform : ladder-shaped, or barred. Scalariform ducts, 46. Scales: any thin scale-like appendages ; usually degenerated leaves, 105. Scalloped : same as Crenate. Scaly : furnished with scales, 95, 191. Scammony, 455. Scandent: climbing. Scape: a‘flower-stalk rising from the ground or near it, 220. Scdpiform, or scapoid: resembling a scape. Scar: see Leaf-scar and Hilum. Scdriose, or scdrious: thin, dry, and membranaceous. . Scattered: either sparse, or without ap- parent symmetry of arrangement. Schizandreex, 382. Scion: a shoot, especially one used for grafting. Sciuroid : like a squirrel’s tail. Scleranthex, 396. Sclérogen : same as Lignine, 36. Scobiform, or scobicular: like sawdust. Scorpioid: coiled round like a scorpion, as the branches of the cyme of Heliotrope. Scrobiculate : pitted. Scrophulariaces, 448. Scrotiform : pouch-shaped. Scurf: minute or bran-like scales on the epidermis, 52. Scutate, scutiform : shicld-shaped. Scutélliform : shaped like a platter (scu- tella). Secretions, 51. Sectile : divided into portions. Secund: all turned to one side of an axis. Seciindine: the second coat of an ovule, 298. Seed, 70, 320. Seed-vessel, 308. Segment: one of the divisions or lobes of a leaf or other organ; 159, 275. Segregate : kept separate. Semi-, in Latin compounds : half. Semi-adherent : the lower half adherent. Semi-amplexicaul : half-clasping. Semicordate: half heart-shaped (divided lengthwise). Semi-double: half-double. Semi-floscular: when the flowers of a head are ligulate. Semilunar, or semilunate: like a crescent or half-moon. GLOSSARY AND INDEX. Seminal : relating or belonging to the seed. Seminiferous ; seed-bearing. Semiorbicular : half-round. Semioval : half of an oval, and Semiovate : half of an ovate figure, di- vided longitudinally. Semisagittate : arrow-headed with one lobe wanting. Semiseptate ; a partition reaching partly across. Semiterete: half-cylindrical, Sempervtrent : evergreen. Senna, 414, Sensitive plants, 345. Sepal: a calyx-leaf, 222. Sépaline, sepalous: relating to sepals, Sépaloid : resembling a sepal. Separated flowers: the stamens and the pistils occupying separate blossoms, 261. Septate: with a partition (septum). Septicidal, or sépticide: dehiscent through the partitions, i. e. by the lines of junction; 316, fig. 582, 584. Septiferous: bearing a partition. Septifragal : where the valves separate from the dissepiments, 317. Septum (plural septa): a partition of any kind, 316. Sérial, or sériate: arranged in rows. Sericeous: silky. Series: rank. Serotinous : flowering or fruiting late. Serrate: beset with teeth pointing for- wards, like those of a saw, 159, fig. 254. Sérratures: the teeth of a serrate body. Sérrulate: serrate with fine teeth. Sesames, 447. Sé&sile (sitting): not stalked, 145, 211, 281. Seta: a bristle, or bristle-like body, 52. Setaceous, setiform: like a bristle. Setigerous : bristle-bearing. Setose: bearing or abounding with bris- tles. Sétula ; diminutive of Scta. Sétulose: bearing minute bristles. Sex: six; as in Sexangular : six-angled. Serfurious: six-rowed. Sexpartite: six-parted, &e. Shaggy: sce Villous. Sheath : a tubular body, enclosing or surrounding some other; as the base of the leaves of Grasses ; 170, fig. 237. Sheathing : forming a sheath ; see Va- gpinate. Shields: see Apothecia, 506. GLOSSARY AND INDEX. 549 Shield-shaped : see Peltate, 158, fig. 248, 681. Shoot : any fresh branch. Shrub, shrubby, 101. Sigillate: as if marked with the impres- sion of a seal, as in Solomon’s Seal, fig. 168. Sigmoid: curved like the Greek sigma, or letter S. Signs used in Botany, 517. Silene, 395. Silicle: a pouch, or short pod of Cru- ciferze, 317, fig. 703. Siliculosa, 515. eels having or resembling a sili- cle, Silique :.a long pod of Cruciferse ; 317, -fig. 589. Siliquosa, 516. Siliquose: like a silique. Silk-cotton, 399. Silky :’ clothed with fine, appressed, and glossy hairs, producing a satiny surface. Silver-berry, 468. Stlver-grain, 120. Simarubaceex, 405. Simple: of one piece or rank. Simple fruits, 309, 311; leaves, 162; pistil, 288. Sinistrorse : turned to the left. Sinuate: strongly wavy on the margin, with alternate convexities and con- cavities ; 159, fig. 258. Sinus : a re-entering angle or recess. Slashed : same as Laciniate. Sleep of plants, 344. Smilacez, 492. Smooth : not pubescent or hairy, or else (and more strictly) not rough. Snakc-root, 412, 462. Soap-berry, 410. Soboliferous : bearing shoots (soboles). Social (plants): growing gregariously. Solanacex, 456. Solitary: single; alone. Soluble: separating into parts. Sorédiate : bearing little patches on the surface. Sorose : heaped, or bearing. Sordsis: a fleshy multiple fruit, like a mulberry. Sori (sing. sorus) : heaps or patches, as those of the spore-cases of most Ferns, called in English fruit-dots, » SOL. Spadiceous : bearing a Spadix : a sort of fleshy spike, 213. Span: the length spanned between the thumb and little finger; seven or eight inches. Sparse: scattered and generally scanty. Pier ea : bearing a pathe: the enveloping bract of a spa- dix, 213. Spathulate, or spatulate: shaped like a druggist’s spatula. Special directions, 341. Species, 19, 354. Specific : relating to species. Spérmaphore : a name for the placenta, or the funiculus of the seed. Spermatozoids, 334. Spermic, or spermous: relating to the seed. | einai : the outer seed-coat, 320. spicate: relating to or disposed in a spike. Spiciform : spike-like. Spicula: a spikelet. Somer a prolonged indefinite inflo- rescence with sessile flowers, 212. Spikelet: a diminutiye or secondary spike; the ultimate flower-clusters of Grasses. Spikenard, 435. Spindle-shaped, 84, fig. 138. Spine, 104, 167. spinescent : tipped with a spine, 104. Spinose: spiny, 104. Spinulose: bearing diminutive spines. Spiral : as if wound round an axis. Spiral arrangement of leaves, 134. Spiral markings on cells, 39. Spiral vessels or ducts, 46. Spires, 416.” Spithameous : a span high. Spongioles, or spongelets, 80. Spongy: of the texture of sponge. Spontaneous movements, 340, 347. Sporddic: widely dispersed. Spordngium : a spore-case, 837, 500, &e. Spore: the body in Cryptogamous plants which answers to the seed in the Phenogamous, 61, 70, 331. Spore-case, 337. Sporiferous: spore-bearing. Sporocarp: a kind of sporangium, 502. Sports, 356. Sporule: a spore, or small spore. Sporuliferous : bearing sporules. Spumescent, spumose: froth-like. Spur: any tubular projection, 278. Spurred: bearing a spur, 278. Syuamate, squamose, squamiferous ; fur- nished with scales (squame). Squdmellate: with or resembling minute and narrow scales (squamella, 497). Squdmiform: scale-shaped. Squdmuliform : like a small scale, or Squdmula, 497. Squdmulose ; covered with small scales. Squarrose: where scales, small leaves, or other bodies, spread widely from . 550 the axis crowded. Squdrrulose: diminutive of Squarrose. Squash, 423. Squills, 493. Stalked: furnished with a stalk, stem, or any lengthened support. Stalked glands, 52. Stalklet: a diminutive or secondary stalk. Stamen : the fertilizing organ of a flow- er, 223. Stdminate, ov stamineal: relating to the stamens. A staminate flower has no pistils, 261. Staminiferous : bearing stamens. Staminddium: an altered and sterile sta- men, or a body occupying the place of a stamen. Standard: the posterior petal of a pa- pilionaceous corolla, 253. Staphyleacex, 409. Star-apple, 443. Starch, 54, 193. Statices, 445. . Station: the locality or kind of situa- tion in which a plant naturally grows. Stellate, 432. Stellate: starry, star-shaped; arranged in rays, like the points of a star. Stellate hairs, 52. Stéllulate: diminutive of Stellate. Stem, 91. Stemless : having no obvious stem, 91. Stemlet: a diminutive stem; the first internode of the plumule. Sterculiacex, 399. Sterigma: the adherent base or down- ward prolongation of a decurrent leaf. Sterile: barren. Sterile flower: one having no pistils, 261. Sterile stamens or filaments: those des- titute of anthers, or with the anther imperfect, 281. Stigma: the part of a pistil which re- ceives the pollen, 223, 287. Stigmdtic, or stigmatose: relating to or bearing the stigma. Stings, stinging hairs, 52. Stipe (stipes) : a stalk of an ovary (267), of a Mushroom (507), and the leaf-stalk of a Fern. Stipel: the stipule of a leaflet ; 171, fig. 286. Stipellate: furnished with stipels, 171. Stipitate: having a stipe, 267. Stipitiform : shaped like a stipe. Stipuldceous, sttpular: belonging to or resembling stipules. on which they are GLOSSARY AND INDEX. Sttpulate, stipuled: possessing stipules, Lik Stipule: an accessory part of a leaf, one on each side of the base, 145, 170. Stock, 355. Stole, stolon: a rooting’ branch, 102. Stolontferous : bearing stolons. : Stoma (plural sfémata), stomate: a breathing-pore, 52, 150. Stomatiferous: bearing stomates. Stone: the endocarp of a drupe. Stone-fruit, 312. Stool: the plant from which layers are propagated. Storax, 425, 442. Stramineous : straw-like. Strangulated : irregularly contracted. Strap-shaped: see Ligulate. Stratum: a layer. . Strawberry, 416. Striate: marked with longitudinal streaks or furrows (strie). Strict: very straight or close, or very upright. Strigillose : same as Strigose. Strigose: clothed with sharp and stout close-pressed hairs or scale-like bristles (strige). Strobildceous: relating to, or resem- bling a Strovile : the cone of a Pine, &e., 319. Strobiliferous : bearing strobiles. Strombuliferous : spirally twisted, like a corkscrew or a strombus. Strdphiole: same as a Caruncle, 322. Structural Botany, 14. Strumose: swollen on one side, bearing astruma or wen. Strychnine, 57, 434. Stupose : tow-like. Style: a columnar or slender part of the pistil above the ovary, 223, 287. Styltferous : style-bearing. Styliform : style-shaped. Stylopddium: an enlargement or fleshy, disk at the base of a style, as in Umbelliferae. Styraces, 442. Sub-, as a prefix, mcans somewhat, or slightly ; as Subacute : somewhat acute. Subclass, 362. Subcordate ; slightly heart-shaped, &c. Stiberose: of a corky texture. Subgenus, 361, 362. Submerged: growing under water. Suborder, 361. Subspecies : a marked variety. Subtribe, 361. Subterranean : growing beneath the sur- face of the ground. GLOSSARY AND INDEX. Subulate, subuliform: awl-shaped ;_ nar- row, and tapering to a sharp rigid point, as the leaves of Juniper, &c. 166, Succise: as if cut off at the end. Succose, succulent: juicy. Sticcubous: the apex of each leaf cov- ered by the base of the next, as in Jungermannia. Succulent leaves, 166. Sucker, 102. Sujffrutéscent: slightly shrubby, 101. Suffritec : an undershrub. Suffiuiticose: low and shrubby, or shrub- by at the base, 101. Sugar, 53, 193, 194. Sulcate: longitudinally grooved. Super-, above ; as Super-axillary : above the axil. Superior ; above, 252; also, on the up- per side of the flower, i. e. next the common axis (237), as, for cxam- ple, the vexillum of a papiliona- ccous corolla (fig. 372, a) is the superior petal. Superposed : one above another. Superposition, 248. Supeérvolute, 274. Supine: lying flat with face upwards. Suppression: obliteration of parts, 239, 255, Supra-, above ; as Supra-azillary: above the axil. Supra-decompound : several times com- pounded. Sirculose: producing suckers. Sirculus : a sucker, 102. Suspended : hanging from the apex, 297. Suspensor of the embryo, 306. Sutural ; relating to the Suture: the seam, or line of opening of a pod, &c., 289. Sword-shaped: a blade with two sharp and nearly parallel edges, tapering to a point, as in Iris, fig. 291. Syconium, or siyconus: such a fruit as a Ne. Symmetrical : equal in the number of all the parts, 232, 239. Sympetalous : becoming somewhat mon- opetalous by a junction of the base of the petals with the monadel- phous stamens, as in the Mallow family. Symphydntherous : same as Syngenesious. Symphysis: a growing together of parts. Symphystémonous : the stamens united. Symplocinee, 443. : Syndntherous: united by their anthers ; whence Composite have been named Synanthere, 435. 551 Synedrpous : formed of two or more united carpels, 290. : Syncotylédonous : the cotyledons soldered together. Syjnedral: growing on the angles. Synéma: a name for a column of mon- adelphous filaments. Syngenesia, 513. Syngenesious: stamens united by their anthers ; 280, fig. 463. Synonyme: equivalent or superseded names. Synonymy : what relates to synonymes. System, 365, 366. Systematic Botany, 15, 351. Tabescent : wasting or shrivelling. Tabular : flattened horizontally. Tail: any long and slender terminal appendage. Tail-pointed : tipped with a prolonged and weak acumination. Tannin, Tannic Acid, 57. Taper-pointed: same as Acuminate. Tapioca, 472. Tap-root, 84. Tar, 480. Taro, 485. Tawny: dull yellowish, verging to brown. Taxinesx, 480. Taxology, or Taxénomy: the depart- ment of Botany which relates to classification. Tea, 401. Teasels, 435. Teeth of calyx, corolla, &c., 275; of leaves, 159. Tegmen: the inner seed-coat, 321. Tendril, 102, 167. Tepal: a name proposed for a leaf or part of the perianth when it is un- certain whether it belongs to the calyx or the corolla. Teratology : morphology monstrous states. Tercine: a third coat of the ovule. Terete : long and round, i. ec. the cross- section circular. Tergeminate: thrice twin. Términal: belonging or relating to the summit. Terminology: the same as Glossology, 15. Ternary: consisting of three, 239. Ternary products, 53. Ternate: in threes. Ternstreemiacee, 401. Tessellated: in checker-work. Testa: the outer seed-coat, 320. Testuceous: brownish-yellow, like un- glazed earthen-waie. applied to 552 GLOSSARY Tetra-, in Greek compound words: four. Tetracdrpellary: of four carpels. Tetracdmarous : same as Tetracvccous: of four cocci. Tetradyndmia, 512. Tetradinamous; two of the six stamens shorter than the rest; 281, fig. 407. Tetrdgonal, or tetrdgonous: four-angled. Tetragynia, 515. Tetrdgynous : with four pistils or styles, 287. * Tetrdmerous: the parts in fours, 234, 239. Tetrandria, 512. Tetrandrous: with four stamens, 279. Tetrapetalous: with four petals, 276. Tetraphyllous : four-leaved, 275. Tetraqueétrous: quadrangular, with very sharp and salient angles. Tetrasépalous: with four sepals, 274. Tetrdstichous : with four vertical ranks. Thalamiflorous : with the stamens, &c. inserted in the receptacle, or Thdlamus : the receptacle of a flower. Thallophytes, 371, 505. Thailus, 67, 871, 505. Theca: ananther-cell, 281; or aspore- case, 499, 500. Thécaphore : same as Gynophore, 267. Thread-shaped: see Filiform, 166. Throat: the orifice of a tubular organ, 275, 276. Thorn, 104. Thyrse, or thyrsus: a thick panicle, 217. Thyrsoid: like a thyrse. Thymelacex, 467 Tieute, 434. Tiliaces, 399. Tissue: the fabric of plants, 22. Tobacco, 456. Tomato, 456. Tomentose: clothed with Toméntum : aclose and matted down or wool. Tongue-shaped : long, fleshy, nearly flat, and rounded at the end. Tonka-bean, 414. Tooth: any short and narrow projec- tion. Toothed: same as Dentate; beset with teeth which on the leaf do not point forwards ; 159, fig. 255. Top-shaped : inversely conical. Torose: a cylindrical body swollen at in- tervals. Tortuous: bent in different directions. Torulose: somewhat torose. Torus: the receptacle of the flower, 224, Trabeculate: cross-barred. Trachea ; a spiral vessel or duct, 46. AND INDEX. Trachénchyma, 46. Trapezoid, or trapeziform : unsymmet- rically four-sided, like a trape- zium. Tree, 101. Tri-, in compound words: three; as Triadelphous: having the filaments in three sets, 280. Tridndria, 512. Tridndrous : with three stamens, 279. Triangular : three-angled. Trianthous : three-flowered. Tribe, 361. Tricdrpellary : of three carpels. Tricdrpous : with three ovaries. Tricéphalous : three-headed. Trichotomous : branched into threes. Tricoccous: of three cocci. Tricispidate: three-pointed. Tridéntate: three-toothed. Triénnial : lasting three years. Lrifarious : in three vertical ranks. Trifid: three-cleft ; 159, fig. 265. Trifoliate : three-leaved. Trifoliolate : of three leaflets. Trifircate: three-forked. Trigamous : having three sorts of flowers. Trigonal, or trigonous : three-angled. Trigynia, 515. Trigynous : with three pistils or styles, 287. Trtjugate: three-paired. Trilateral ; three-sided. Trilliaces, 493. Trilobate: three-lobed. Trilécular : three-celled. Trimerous: the parts in threes; 234, 939, fig. 353. Trinérvate: three-nerved. Trinodal : of three nodes or joints. Tricia, 516. Triccious, or trioicous: having stami- nate, pistillate, and perfect flowers on three different plants. Trisvulate: having three ovules. Tripartible: capable of splitting into three. Tripartite : three-parted. Tripetalous : of three petals, 276. Triphyllous : three-leaved, 275. Tripinnate : thrice pinnate, 164. Tripinnatifid : thrice pinnatifid, 161. Triple-ribbed, or nerved: same as Tripli-nerved, 155. Tripterous: three-winged. Triquétrous : with three salient angles. Trisepalous : of three sepals, 274. Trisérial, or trisériate: in three horizon- tal ranks. Tristichous : in three vertical ranks, 134. Tristigmadtic : with three stigmas. Tristylous : with three styles. GLOSSARY AND INDEX. Trisiileate : three-grooved. Tritérnate : thrice ternate, 164. Trivial name: the popular name; or the specific name. Trochlear : pulley-shaped. Tropeolacez, 404. Trophosperm: the placenta. Tropical : growing near or between the tropics. Trumpet-shaped : tubular, with the sum- mit dilated. Truncate: as if cut off at the end; 162, fig. 271. Trunk : a main stem. Tube: the portion of a calyx, corolla, &e. formed by the union of the sepals, petals, &c., 275. Tuber: a short and thickened subterra- nean branch, 107. Tubercle: a small tuber, or an excres- cence. Tubercled : bearing excrescences. Tuberiferous : bearing tubers. Triberous : tuber-like ; 85, fig. 139. Tubulose, tubular: having a tube, or tube-shaped, as the corolla of Trum- pet Honeysuckle, &c., 277. Tubuliflore, 436. Tumid : somewhat inflated. Tinicate: having an accessory covering (tunic). Tunicated bulb, 109. Tirbinate: top-shaped. Turio, turions; the early state of a suck- er or subterranean shoot, as an Asparagus-shoot, 95. Turmeric, 490. Turneraces, 422. Turnip-shaped: see Napiform, 84. Turnsole, 473. Turpentine, 57, 480. Twin: in pairs. Twining: winding spirally round a sup- port, 102. Two-lipped, 255. Type: the pattern or ideal plan, 231, 238. Typhacee, 485. Typical: representing the type or plan. Uliginose: growing in marshes. Ulmaceer, 474. Ulmine, Ulmic Acid, 57. Umbel: an umbrella-shaped inflores- , cence, 212. Umbellate, umbelliform : in umbels. Umbellet: a secondary or partial um- bel, 216. Umbellifere, 425. Unbelliferous : bearing umbels, Umbilicate: depressed in the centre, like the navel. 47 553 Unbilicus : the hilum of a sced; a cen- , _ tral depression. Umbonate: bearing an umbo or boss, a central projection. Unbrdculiform : umbrella-shaped. Unarmed: destitute of prickles, spines, Cc. Uncate: hooked. U'nciform, or uncinate : hooked. Undate, or undulate: wavy. Undershrub, 101. Unequally pinnate : same as impari-pin- nate, 163. Unguiculate: furnished with a claw (un- guis), as the petals of Saponaria, 276, fig. 449, &c. Oni-, in Latin compounds: one. Unicéllular : one-celled, 61. Uniflorous : one-flowered. Unifoliate : one-leaved. Unifoliolate: with one leaflet. Unajugate : of only one pair, 164. Unildbiate: one-lipped. Onildteral: one-sided: either all dis- posed on one side of an axis, or turned to one side. Unilocular : one-celled. Uninérvate : one-nerved. Uniovulate : one-ovuled. Unipeétalous: having only one petal, as in Amorpha, fig. 395. Unisérial, or uniséviate: in one horizon- tal row or whorl. Uniserual: having stamens only or pis- , _ tils only, 261. Univalved : of one piece ; one-valved. Universal : same as General. Upas, 475. . . Drccotete : pitcher-shaped or urn-shaped ; i.e. hollow and contracted at the mouth. Urticacer, 473. Utricle : a small bladdery fruit, 314. Utricular : bladder-like. Utriculariaceze, or Utricularines: : same as Lentibulace, 445. Utriculiform : shaped like a little bottle. Utriculose : bearing utriculi, or bladders. Uvulariex, 494. Vacciniee, or Vacciniacer, 439. Vagina: the sheath of a leaf, &c. Vaginant: sheathing. Vaginate: sheathed. Vaginula : a little sheath, as that around the sporangium of Peat Moss. Vaginulate : with a vaginula. : Vague : in no definite order or direction. Valerian, 434. Valerianacee, 434, Vallécule: the intervals between the ridges of the fruit of Umbelliferze. 554 Valvate or vdlvular sxstivation, &c.: where the parts meet by their edges without overlapping, 144, 273. Valve : a door, or portion into which a pod, &c. separates in dehiscence ; also a piece or leaf of a spathe, &c. Valved: opening by valves. Vanilla, 489. Variegated : having one or two colors disposed in patches. Varieties, 355. Vasculur ; relating to or furnished with vesscls. Vascular Plants, 68. Vascular or vasiform tissue, 40, 45. Vasculum : same as Ascidium. Vegetable Ivory, 484. Vegetable Physiology and Anatomy, 14 Veil: sce Calyptra. Veined : furnished with slender vascular or woody bundles, especially with branching ones, or Verns, 145, 155. Veinless : destitute of apparent veins. Veinlets: the smaller ramifications of veins, 155. Velate: veiled. Velutinous : velvety ; covered with very fine and close soft hairs, so that the surface resembles velvet to the touch. Venation: the mode of veining, 154. Veénose: veiny ; abounding in veins. Ventral: relating to the inner side of a simple pistil, viz. that next the axis. Ventral suture: the inner suture, 289. Ventricose: big-bellied ; swelling out. Ventriculose : somewhat ventricose. Vénulose: abounding in veinlets. Veratria, 494. Verbenacez, 449. Vermicular : worm-like, in shape or ap- pearance. Vernal : belonging to spring. Vernation: the disposition of leaves in the bud, 143. : Vernicose : varnished. Vérrucose: warty. Veérruculose: studded with little warts. Versatile: swinging to and fro; 282, fig. 471. Vertex : the summit. Vertical : perpendicular, lengthwise. Vertical leaves, 165. Vertical tissue or system, 45, 50, 112. Verticil, or verticel : a whorl, 92, 134. Verticilldster : the pair of dense cymes forming an apparent verticil in most Lahiata, 221. Verticillate : whorled, 133, 142, 221. GLOSSARY AND INDEX. Vesicle: a little bladder. Vesicular: as if composed of little blad- ders. Vespertine: appearing or expanding in the carly evening. Vessels, 40. Vécillary wstivation, 271. Vécxillary: pertaining to the Vextllum: the standard of a papiliona- ceous corolla; 253, fig. 392, a. Villose, or villous ; shaggy with long and soft hairs, or villosity. . Vimineous: bearing or resembling long and flexible twigs, like wicker. Vine: any trailing, climbing, or twining stem, The Vine, originally, is the Grape-vine. Violacee, or Violarice, 392. Viréscent : somewhat green (virens). Virqate: twig-like ; wand-like. Viridescent : same as Virescent. Viscid, viscous: sticky from a tena- cious secretion. Vitacee, 407. Vitéilus : the thickened embryo-sac per- sistent in the seed, as in Saururus and Brasenia. Viticulose: producing small suckers or stolons (viticude). Vittce (fillets) : the oil-receptacles of the fruit of Umbellifere, 426. Vittate: bearing vittee: marked with longitudinal stripes or fillets, 426. Viviparous : germinating from the seed (330), or sprouting from a bulb, &c., while still attached to the parent plant. Foluble: twining, 102. Volute : rolled up. Volva: the wrapper of Fungi, 507. Walnut, 476. Wavy: see Undulate. Wax, 56. Wazy: resembling beeswax in appear- ance or consistence. Wedge-shaped: see Cuneate. Wheat, 498. Wheel-shaped: a corolla or calyx with a very short tube and a flat- spreading border; 278, fig. 454. Whori :' a set of organs arranged in a circle round an axis, 92, 134, 221. Whorled: disposed in whorls. Whortleberry, 439. Wild: growing spontaneously. Wing: any membranous expansion. Also the two side petals of a pa- pilionaceous corolla; 253, fig. 392, b. GLOSSARY AND INDEX. 555 Winged: provided with wings. Xyridacee, 496. Winterex (or Winteraces), 381. Winter's Bark, 381. Yam, 492, Withering : see Marcescent. Wood, 119. Zanthoxylacer, or Zanthoxylem, 406. Woodly tissue or fibre, 40. Zingiberacez, 489. 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