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GRAY'S LESSONS IN BOTANY

REVISED EDITION

THE ELEMENTS OF BOTANY

FOR BEGINNERS AND FOR SCHOOLS

By ASA GRAY

IVISON, BLAKEMAN, AND COMPANY NEW YORK AND CHICAGO

_Copyright_, By Asa Gray. 1887.

PREFACE.

This volume takes the place of the author's Lessons in Botany and Vegetable Physiology, published over a quarter of a century ago. It is constructed on the same lines, and is a kind of new and much revised edition of that successful work. While in some respects more extended, it is also more concise and terse than its predecessor. This should the better fit it for its purpose now that competent teachers are common. They may in many cases develop paragraphs into lectures, and fully illustrate points which are barely, but it is hoped clearly, stated. Indeed, even for those without a teacher, it may be that a condensed is better than a diffuse exposition.

The book is adapted to the higher schools, "How Plants Grow and Behave" being the "Botany for Young People and Common Schools." It is intended to ground beginners in Structural Botany and the principles of vegetable life, mainly as concerns Flowering or Phanerogamous plants, with which botanical instruction should always begin; also to be a companion and interpreter to the Manuals and Floras by which the student threads his flowery way to a clear knowledge of the surrounding vegetable creation. Such a book, like a grammar, must needs abound in technical words, which thus arrayed may seem formidable; nevertheless, if rightly apprehended, this treatise should teach that the study of botany is not the learning of names and terms, but the acquisition of knowledge and ideas. No effort should be made to commit technical terms to memory. Any term used in describing a plant or explaining its structure can be looked up when it is wanted, and that should suffice. On the other hand, plans of structure, types, adaptations, and modifications, once understood, are not readily forgotten; and they give meaning and interest to the technical terms used in explaining them.

In these "Elements" naturally no mention has been made of certain terms and names which recent cryptogamically-minded botanists, with lack of proportion and just perspective, are endeavoring to introduce into phanerogamous botany, and which are not needed nor appropriate, even in more advanced works, for the adequate recognition of the ascertained analogies and homologies.

As this volume will be the grammar and dictionary to more than one or two Manuals, Floras, etc., the particular directions for procedure which were given in the "First Lessons" are now relegated to those works themselves, which in their new editions will provide the requisite explanations. On the other hand, in view of such extended use, the Glossary at the end of this book has been considerably enlarged. It will be found to include not merely the common terms of botanical description but also many which are unusual or obsolete; yet any of them may now and then be encountered. Moreover, no small number of the Latin and Greek words which form the whole or part of the commoner specific names are added to this Glossary, some in an Anglicized, others in their Latin form. This may be helpful to students with small Latin and less Greek, in catching the meaning of a botanical name or term.

The illustrations in this volume are largely increased in number. They are mostly from the hand of Isaac Sprague.

It happens that the title chosen for this book is that of the author's earliest publication, in the year 1836, of which copies are rarely seen; so that no inconvenience is likely to arise from the present use of the name.

ASA GRAY.

Cambridge, Massachusetts, _March, 1887_.

CONTENTS.

Page SECTION I. INTRODUCTORY 9

SECTION II. FLAX AS A PATTERN PLANT 11

Growth from the Seed, Organs of Vegetation 11 Blossoming, Flower, &c. 14

SECTION III. MORPHOLOGY OF SEEDLINGS 15

Germinating Maples 15 Cotyledons thickened, hypogaeous in germination 18 Store of Food external to the Embryo 20 Cotyledons as to number 22 Dicotyledonous and Polycotyledonous 23 Monocotyledonous 24 Simple-stemmed Plants 26

SECTION IV. GROWTH FROM BUDS; BRANCHING 27

Buds, situation and kinds 27 Vigorous vegetation from strong Buds 28 Arrangement of Branches 29 Non-developed, Latent, and Accessory Buds 30 Enumeration of kinds of Buds 31 Definite and Indefinite growth; Deliquescent and Excurrent 31

SECTION V. ROOTS 33

Primary and Secondary. Contrast between Stem and Root 34 Fibrous and Fleshy Roots; names of kinds 34 Anomalous Roots. Epiphytic and Parasitic Plants 36 Duration: Annuals, Biennials, Perennials 37

SECTION VI. STEMS 38

Those above Ground: kinds and modifications 39 Subterranean Stems and Branches 42 Rootstock 42 Tuber 44 Corm 45 Bulb and Bulblets 46 Consolidated Vegetation 47

SECTION VII. LEAVES 49

Sec. 1. LEAVES AS FOLIAGE 49

Parts and Venation 50 Forms as to general outline 52 As to apex and particular outline 53 As to lobing or division 56 Compound, Perfoliate, and Equitant Leaves 57 With no distinction of Petiole and Blade, Phyllodia, &c. 61

Sec. 2. LEAVES OF SPECIAL CONFORMATION AND USE 62

Leaves for storage 62 Leaves as bud-scales 63 Spines 64 and for Climbing 64 Pitchers 64 and Fly-traps 65

Sec. 3. STIPULES 66

Sec. 4. THE ARRANGEMENT OF LEAVES 67

Phyllotaxy 67 Of Alternate Leaves 69 Of Opposite and Whorled Leaves 71 Vernation or Praefoliation 71

SECTION VIII. FLOWERS 72

Sec. 1. POSITION AND ARRANGEMENT, INFLORESCENCE 73

Raceme 73 Corymb, Umbel, Spike, Head 74 Spadix, Catkin, or Ament 75 Panicle: Determinate Inflorescence 76 Cyme, Fascicle, Glomerule, Scorpioid or Helicoid Cymes 77 Mixed Inflorescence 78

Sec. 2. PARTS OR ORGANS OF THE FLOWER 79

Floral Envelopes: Perianth, Calyx, Corolla 79 Essential Organs: Stamen, Pistil 80 Torus or Receptacle 81

Sec. 3. PLAN OF THE FLOWER 81

When perfect, complete, regular, or symmetrical 81 Numerical Plan and Alternation of Organs 82 Flowers are altered branches 83

Sec. 4. MODIFICATIONS OF THE TYPE 85

Unisexual or diclinous 85 Incomplete, Irregular, and Unsymmetrical 86 Flowers with Multiplication of Parts 88 Flowers with Union of Parts: Coalescence 88 Regular Forms 89 Irregular Forms 90 Papilionaceous 91 Labiate 92 and Ligulate Corollas 93 Adnation or Consolidation 94 Position of Flower or of its Parts 96

Sec. 5. ARRANGEMENT OF PARTS IN THE BUD 97

AEstivation or Praefloration, its kinds 97

SECTION IX. STAMENS IN PARTICULAR 98

Androecium 98 Insertion, Relation, &c. 99 Anther and Filament. Pollen 101

SECTION X. PISTILS IN PARTICULAR 105

Sec. 1. ANGIOSPERMOUS OR ORDINARY GYNOECIUM 105

Parts of a complete Pistil 105 Carpels, Simple Pistil 106 Compound Pistil with Cells and Axile Placentae 107 One-celled with Free Central Placenta 108 One-celled with Parietal Placentae 108

Sec. 2. GYMNOSPERMOUS GYNOECIUM 109

SECTION XI. OVULES 110

Their Parts, Insertion, and Kinds 111

SECTION XII. MODIFICATIONS OF THE RECEPTACLE 112

Torus, Stipe, Carpophore, Disk 113

SECTION XIII. FERTILIZATION 114

Sec. 1. ADAPTATIONS FOR POLLINATION OF THE STIGMA 114

Close and Cross Fertilization, Anemophilous and Entomophilous 115 Dichogamy and Heterogony 116

Sec. 2. ACTION OF THE POLLEN AND FORMATION OF THE EMBRYO 117

SECTION XIV. THE FRUIT 117

Nature and kinds 118 Berry, Pepo, Pome 119 Drupe and Akene 120 Cremocarp, Caryopsis, Nut 121 Follicle, Legume, Capsule 122 Capsular Dehiscence, Silique and Silicle 123 Pyxis, Strobile or Cone 124

SECTION XV. THE SEED 125

Seed-coats and their appendages 125 The Kernel or Nucleus, Embryo and its parts, Albumen 127

SECTION XVI. VEGETABLE LIFE AND WORK 128

Sec. 1. ANATOMICAL STRUCTURE AND GROWTH 129

Nature of Growth, Protoplasm 129 Cells and Cell-walls. Cellular Structure or Tissue 130 Strengthening Cells. Wood, Wood-cells, Vessels or Ducts 132

Sec. 2. CELL-CONTENTS 136

Sap, Chlorophyll, Starch 136 Crystals, Rhaphides 137

Sec. 3. ANATOMY OF ROOTS AND STEMS 138

Endogenous and Exogenous Stems 139 Particular structure of the latter 140 Wood, Sapwood and Heart-wood. The living parts of a Tree 141

Sec. 4. ANATOMY OF LEAVES 142

Epidermis, Stomata or Breathing pores 143

Sec. 5. PLANT FOOD AND ASSIMILATION 144

Sec. 6. PLANT WORK AND MOVEMENT 149

Movements in Cells or Cyclosis 149 Transference from Cell to Cell 150 Movements of Organs, Twining Stems, Leaf-movements 150 Movements of Tendrils, Sensitiveness 152 Movements in Flowers 153 Movements for capture of Insects 154 Work costs, using up Material and Energy 155

SECTION XVII. CRYPTOGAMOUS OR FLOWERLESS PLANTS 156

Vascular Cryptogams, Pteridophytes 156 Horsetails (Equisetaceae), Ferns 157 Club-Mosses (Lycopodium), &c. 161 Quillworts (Isoetes), Pillworts (Marsilia) 161 Azolla. Cellular Cryptogams 162 Bryophytes. Mosses (Musci) 163 Liverworts (Hepaticae) 164 Thallophytes 165 Characeae 167 Algae, Seaweeds, &c. 168 Lichenes or Lichens 171 Fungi 172

SECTION XVIII. CLASSIFICATION AND NOMENCLATURE 175

Sec. 1. KINDS AND RELATIONSHIP 175

Species, Varieties, Individuals 176 Genera, Orders, Classes, &c. 177

Sec. 2. NAMES, TERMS AND CHARACTERS 178

Nomenclature of Genera, Species, and Varieties 179 Nomenclature of Orders, Classes, &c. Terminology 180

Sec. 3. SYSTEM 181

Artificial and Natural 182 Synopsis of Series, Classes, &c. 183

SECTION XIX. BOTANICAL WORK 184

Sec. 1. COLLECTION OR HERBORIZATION 184

Sec. 2. HERBARIUM 186

Sec. 3. INVESTIGATION AND DETERMINATION OF PLANTS 187

Sec. 4. SIGNS AND ABBREVIATIONS 188

ABBREVIATIONS OF THE NAMES OF BOTANISTS 190

GLOSSARY COMBINED WITH INDEX 193

ELEMENTS OF BOTANY.

Section I. INTRODUCTORY.

1. BOTANY is the name of the science of the vegetable kingdom in general; that is, of plants.

2. Plants may be studied as to their kinds and relationships. This study is SYSTEMATIC BOTANY. An enumeration of the kinds of vegetables, as far as known, classified according to their various degrees of resemblance or difference, constitutes a general _System of plants_. A similar account of the vegetables of any particular country or district is called a _Flora_.

3. Plants may be studied as to their structure and parts. This is STRUCTURAL BOTANY, or ORGANOGRAPHY. The study of the organs or parts of plants in regard to the different forms and different uses which the same kind of organ may assume,--the comparison, for instance, of a flower-leaf or a bud-scale with a common leaf,--is VEGETABLE MORPHOLOGY, or MORPHOLOGICAL BOTANY. The study of the minute structure of the parts, to learn by the microscope what they themselves are formed of, is VEGETABLE ANATOMY, or HISTOLOGY; in other words, it is Microscopical Structural Botany. The study of the actions of plants or of their parts, of the ways in which a plant lives, grows, and acts, is the province of PHYSIOLOGICAL BOTANY, or VEGETABLE PHYSIOLOGY.

4. This book is to teach the outlines of Structural Botany and of the simpler parts of the physiology of plants, that it may be known how plants are constructed and adapted to their surroundings, and how they live, move, propagate, and have their being in an existence no less real, although more simple, than that of the animal creation which they support. Particularly, this book is to teach the principles of the structure and relationships of plants, the nature and names of their parts and their modifications, and so to prepare for the study of Systematic Botany; in which the learner may ascertain the name and the place in the system of any or all of the ordinary plants within reach, whether wild or cultivated. And in ascertaining the name of any plant, the student, if rightly taught, will come to know all about its general or particular structure, rank, and relationship to other plants.

5. The vegetable kingdom is so vast and various, and the difference is so wide between ordinary trees, shrubs, and herbs on the one hand, and mosses, moulds, and such like on the other, that it is hardly possible to frame an intelligible account of plants as a whole without contradictions or misstatements, or endless and troublesome qualifications. If we say that plants come from seeds, bear flowers, and have roots, stems, and leaves, this is not true of the lower orders. It is best for the beginner, therefore, to treat of the higher orders of plants by themselves, without particular reference to the lower.

6. Let it be understood, accordingly, that there is a higher and a lower series of plants; namely:--

PHANEROGAMOUS PLANTS, which come from seed and bear _flowers_, essentially stamens and pistils, through the co-operation of which seed is produced. For shortness, these are commonly called PHANEROGAMS, or _Phaenogams_, or by the equivalent English name of FLOWERING PLANTS.[1]

CRYPTOGAMOUS PLANTS, or CRYPTOGAMS, come from minute bodies, which answer to seeds, but are of much simpler structure, and such plants have not stamens and pistils. Therefore they are called in English FLOWERLESS PLANTS. Such are Ferns, Mosses, Algae or Seaweeds, Fungi, etc. These sorts have each to be studied separately, for each class or order has a plan of its own.

7. But Phanerogamous, or Flowering, Plants are all constructed on one plan, or _type_. That is, taking almost any ordinary herb, shrub, or tree for a pattern, it will exemplify the whole series: the parts of one plant answer to the parts of any other, with only certain differences in particulars. And the occupation and the delight of the scientific botanist is in tracing out this common plan, in detecting the likenesses under all the diversities, and in noting the meaning of these manifold diversities. So the attentive study of any one plant, from its growth out of the seed to the flowering and fruiting state and the production of seed like to that from which the plant grew, would not only give a correct general idea of the structure, growth, and characteristics of Flowering Plants in general, but also serve as a pattern or standard of comparison. Some plants will serve this purpose of a pattern much better than others. A proper pattern will be one that is perfect in the sense of having all the principal parts of a phanerogamous plant, and simple and regular in having these parts free from complications or disguises. The common Flax-plant may very well serve this purpose. Being an annual, it has the advantage of being easily raised and carried in a short time through its circle of existence, from seedling to fruit and seed.

FOOTNOTES:

[1] The name is sometimes _Phanerogamous_, sometimes _Phaenogamous_ (_Phanerogams_, or _Phaenogams_), terms of the same meaning etymologically; the former of preferable form, but the latter shorter. The meaning of such terms is explained in the Glossary.

Section II. FLAX AS A PATTERN PLANT.

8. =Growth from the Seed.= Phanerogamous plants grow from seed, and their flowers are destined to the production of seeds. A seed has a rudimentary plant ready formed in it,--sometimes with the two most essential parts, i. e. stem and leaf, plainly discernible; sometimes with no obvious distinction of organs until germination begins. This incipient plant is called an EMBRYO.

9. In this section the Flax-plant is taken as a specimen, or type, and the development and history of common plants in general is illustrated by it. In flax-seed the embryo nearly fills the coats, but not quite. There is a small deposit of nourishment between the seed-coat and the embryo: this may for the present be left out of the account. This embryo consists of a pair of leaves, pressed together face to face, and attached to an extremely short stem. (Fig. 2-4.) In this rudimentary condition the real nature of the parts is not at once apparent; but when the seed grows they promptly reveal their character,--as the accompanying figures (Fig. 5-7) show.

10. Before the nature of these parts in the seed was altogether understood, technical names were given to them, which are still in use. These initial leaves were named COTYLEDONS. The initial stem on which they stand was called the RADICLE. That was because it gives rise to the first root; but, as it is really the beginning of the stem, and because it is the stem that produces the root and not the root that produces the stem, it is better to name it the CAULICLE. Recently it has been named _Hypocotyle_; which signifies something below the cotyledons, without pronouncing what its nature is.