BOTANY
The Science of Plant Life
BY
NORMAN TAYLOR
Curator, Brooklyn Botanic Garden
P. F. COLLIER & SON COMPANY
NEW YORK
PREFACE
THIS book is for those who want some general knowledge of the plant world, without necessarily caring for the technical details upon which such knowledge is based. If it leaves the reader with an impulse to follow the subject further than has been possible here, it will have more than fulfilled its mission.
Throughout the book, it has often been convenient to refer to plants or their behavior in terms implying reasoning faculties. Of course, plants are never reasoning things, reasonable as many of their actions appear to be, and to ascribe such qualities to them is to saddle them with attributes perfectly foreign to the plant world. But the description of them in the terms of our everyday speech, the translation of plant behavior into the current conceptions of mankind, does so fix these in our minds that they cease to be among those interesting things that nearly everyone forgets. I have followed this method deliberately, understanding perfectly the objections to it, but believing, with the late C. E. Bessey, that in popular books “it is an admirable way of looking at some botanical things.”
All of the half-tone illustrations, except two, are from the photographic collections of the Brooklyn Botanic Garden, and I am under the greatest obligation to the director of that institution for permission to publish them here. The illustration of the living and fossil algæ has been taken from Prof. Henry Fairfield Osborn’s “Origin and Evolution of Life,” with his kind permission. The illustration of desert vegetation is from a photograph by the late E. L. Morris, and kindly loaned from the collection of the Brooklyn Museum. All the line cuts in the text are from drawings made specially for this book by my wife, Bertha Fanning Taylor.
While grateful and particular acknowledgments can be made for the illustrations, it is difficult or impossible to properly express my indebtedness to all those who, through their books and pamphlets, have indirectly aided in the making of this book. It would involve the mention of most of the better known writers of the books found in the larger botanical libraries. It is a pleasure to acknowledge help from Dr. M. A. Howe of the New York Botanical Garden on the literature of fossil and hot-spring algæ, and from Dr. Orland E. White of the Brooklyn Botanic Garden for helpful criticism of the section dealing with “How Plants Change Their Characters.”
Norman Taylor.
Brooklyn Botanic Garden
20th October, 1920
CONTENTS
| CHAPTER | PAGE | |
| Introductory—Plants and Our Daily Needs | [9] | |
| [I.] | What Plants Are | [13] |
| [II.] | Plant Behavior | [76] |
| [III.] | How Plants Produce Their Young | [116] |
| [IV.] | The Families of Flowering Plants and Their Relationship | [168] |
| [V.] | Uses of Plants to Man | [208] |
| [VI.] | Garden Plants | [267] |
| [VII.] | History of the Plant Kingdom | [298] |
| [VIII.] | Distribution of Plants | [337] |
LIST OF ILLUSTRATIONS
INTRODUCTORY CHAPTER
PLANTS AND OUR DAILY NEEDS
PERHAPS few of us realize that without plants all our modern civilization would be swept away and that upon plants has been built all that we have so far accomplished and everything that we may yet become. The overthrow of any king or republic, the wiping out of all money and finance or any of the manifold evidences of our modern world could not for a moment be compared to what would happen to us with the sudden destruction of plant life from the earth.
Food and drink, the very houses we live in and heat, medicines and drugs, books and pictures, musical instruments and tires for automobiles, all these and hundreds of our daily needs depend upon the fact that plants of many different kinds grow upon the earth and in sufficient amounts to be of importance. It is easy to say in opposition to this that we get much food from animals, that we can drink water, and that neither of these comes from plants. But water would soon be lost to us if forests did not conserve it, and upon pasturage most of our food animals depend for their life. The discovery of a single tree in the mountains of northern South America made possible for white man the malarial regions unfit for him before the advent of quinine. Just before Shakespeare’s time sugar and tea and coffee became regular articles of commerce. Not until the discovery of America was tobacco, Indian corn, chocolate, the pineapple or the potato known to man. Upon the spruce forests in the north depends much of our paper supply, from cotton we get clothes and explosives, from hemp and sisal ropes, from a single kind of Brazilian tree most of our rubber, and from rice a food that sustains nearly half the world.
While it is thus plain enough that life depends upon plants now present upon the earth it may not be so obvious that from certain ancient forests has come the greatest source of artificial heat in the world. Coal is nothing but the partial decomposition of vast forests, living ages before man was first found upon the earth, subsequently buried, and under the earth’s pressure forming soft coal, or where the pressure was severe enough hard coal. When it is remembered that a dead, partly decayed tree is only a fraction of its living size and that coal is found in many parts of the world in tremendous quantities we get a partial glimpse of what our debt is to a great forest that lived in luxuriance no one knows how many millions of years ago, reached its climax, and upon whose embedded remains we depend for heat.
Later on in this book will be given in greater detail some of the plants useful to man and just how we have used them. Hardly any part of the study of the plant kingdom has so much of interest as that dealing with our utilization of the things that grow about us. From the earliest struggles of our half-savage ancestors to grow definite crops rescued from the wild down to our modern nut butter made from the partly fermented meat of the cocoanut and shipped half round the world before it is refined, man has constantly striven to use for his advantage the plants most likely to prove valuable. Countries and empires have been built upon such facts. Even to-day rubber from the Straits Settlements and palm oil from Africa are deciding the economic life of those countries.
But man’s use of plants, in fact his absolute reliance upon them, is not the only reason for attempting to find out more about them, what they are, where they came from, how they live and produce their young. A knowledge of even a small part of such a science opens up a rich field of inquiry involving a concept of plant life of greater interest than mere bread and butter. For those with an eye to see and knowledge to interpret, a landscape with its trees or flowers or marshes may contain a host of hidden secrets of dramatic import. Unfolded before one may be found a spectacle of struggle and strife, quiet tragedies of the forest, the inexorable pressure of plants upon their neighbors, the woods upon the prairies or an apparently forlorn hope of some plant living in a hot desert or upon some icy mountain peak. And while these rather obvious things are happening how much more is hidden of the adjustments that leaves or flowers or roots or other organs of the plant are constantly making to the conditions about them. Upon the perfection of such adjustments to light, heat, or water, for instance, depends their very existence. Mistakes are fatal, the forces of nature seem peculiarly relentless, and it is literally a case where many are called but few chosen. Of the untold millions of seeds produced each year few ever grow, yet out of this enormous wastage springs all that makes the earth not only habitable but the beautiful panorama of vegetation to which we are so accustomed that it is nearly taken for granted.
The study of botany attempts to answer some of the questions raised above and many others. Subsequent parts of the book will deal with what plants are, the behavior of them, with the life histories of some of the better known ones, with the grouping of plants in families and their relationships one to another, with their uses to man, with the history of their development from the earliest times, and finally with their distribution over the earth. The latter will be discussed last because it is the most important of all the phases of plant life. How plants are distributed, whether as forest or prairie or thickets or what not, depends upon the response of individual plants and their organs to the conditions about them. The type of vegetation in different parts of the world has been dictated by the success of the survivors in meeting existing conditions and of having met them in the past. Upon this fact rests our civilization to-day. Upon this fact there has been reared a study the cultural, esthetic, and practical value of which may well outweigh any other.
While the study of botany is necessarily a technical one with a language all its own, its terms, though generally unfamiliar, are unexcelled for their purpose. They will be avoided here as much as a clear understanding of the subject will permit. The few that must be used will be explained where they first occur and it is assumed that the reader will understand their subsequent use.
CHAPTER I
WHAT PLANTS ARE
WHAT we commonly call plants, such as corn or buttercups or an oak tree, are so familiar that a definition of what plants are may seem needless. It would be quite so if these generally recognized examples comprised all the plant kingdom. Actually what are ordinarily thought of as plants make up only a fraction of the great plant world. The fact that our familiar roadside and garden plants produce blossoms followed by a fruit and seed, such as peas and beans and all the ordinary flora of any region, separates them at once from that other large group of plants that do not. Common examples of the latter class are the green scum on the ponds, moss, seaweed, the rust on wheat, yeast, disease-causing bacteria, the smallest of all known plants, and many others. Most of these organisms are so small that they can be distinguished only under the higher powers of the microscope. Some of them in their habits and growth are like the minute animals described in the volume of this series devoted to that subject. In fact there are organisms about which scientists are still in doubt as to their animal or vegetable character.
One or two characteristics common to most plants, however, separate them from animals and these are their method of getting food and their practically immovable mode of life. Animals, however simple, do eat and digest their food, plants take various mineral substances from the earth or air or water in the form of inorganic matter such as oxygen, carbon, nitrogen, and all the food materials found in the soil, and transform them, with the aid of sunshine, into the structure that characterizes each particular form. Plants, then, may be defined as any living organism that, with minor exceptions, has the power to assimilate inorganic substances and transform them into organic matter. Nothing else in all the realm of nature has this power. It is a possession beyond all price, this ability to take from the soil and air and water simple chemical substances and under the magic of sunlight transform them into the wonderful plant life of the world. But this faculty has its handicaps, for it is usually, though not always, associated with inability to move from place to place, which, in some measure, even the simplest animals can accomplish.
It will be readily understood that this definition of plants includes many other things that are commonly attributed to the plant kingdom. For our purpose the discussion of these relatively unfamiliar forms of plant life will be left until later. A rough and ready distinction between those plants that everyone recognizes as such and those others like yeast and microbes, which are plants to most of us only by virtue of the definition given above, is that the first group produce flowers and seeds and the second do not. It should not be forgotten, and it will be shown later, that this is not a true distinction, but for practical purposes of dividing the plant kingdom it suffices.