An introduction to physiological and systematical botany

Front matter

AN INTRODUCTION TO PHYSIOLOGICAL AND SYSTEMATICAL BOTANY.

BY JAMES EDWARD SMITH, M.D. F.R.S. &c. &c. PRESIDENT OF THE LINNÆAN SOCIETY.

"CONSIDER THE LILIES OF THE FIELD, HOW THEY GROW."

Preface

PREFACE.

After the many elementary works on Botany which have appeared in various languages, any new attempt of the same kind may, at first sight, seem unnecessary. But when we consider the rapid progress of the science within a few years, in the acquisition and determination of new plants, and especially the discoveries and improvements in vegetable physiology; when we reflect on the view with which those fundamental works of Linnæus, the basis of all following ones, were composed, and to whom they were addressed, we must be aware of their unfitness for purposes of general and popular utility, and that something else is wanting. If we examine the mass of introductory books on botany in this light, we shall find them in some cases too elaborate and intricate, in others too obscure and imperfect: they are also deficient in that very pleasing and instructive part of botany, the anatomy and physiology of plants. There are indeed works, such as Rose's Elements of Botany, and Darwin's Phytologia, with which no such faults can be found. The former is a compendium of Linnæan learning, the latter a store of ingenious philosophy; but they were designed for philosophers, and are not calculated for every reader. Linnæus and his scholars have generally written in Latin. They addressed themselves to physicians, to anatomists, to philosophers, little thinking that their science would ever be the amusing pursuit of the young, the elegant and the refined, or they would have treated the subject differently. It appears to me, therefore, that an introductory publication is still desirable in this country, on an original plan, easy, comprehensive, and fit for general use, and such were the reasons which first prompted me to the undertaking.

When, however, I had proceeded a considerable way in its execution, I found that such a work might not only serve to teach the first outlines of the science, but that it might prove a vehicle for many observations, criticisms, and communications, scarcely to be brought together on any other plan; nor did it appear any objection to the general use of the book, that, besides its primary intention, it might be capable of leading into the depths of botanical philosophy, whether physiological, systematical, or critical, any student who should be desirous of proceeding so far. A volume of this size can indeed be but elementary on subjects so extensive; but if it be clear and intelligible as far as it goes, serving to indicate the scope of the science of botany, and how any of its branches may be cultivated further, my purpose is answered. The subject has naturally led me to a particular criticism of the Linnæan system of arrangement, which the public, it seems, has expected from me. Without wasting any words on those speculative and fanciful changes, which the most ignorant may easily make, in an artificial system; and without entering into controversy with the very few competent writers who have proposed any alterations; I have simply stated the result of my own practical observations, wishing by the light of experience to correct and to confirm what has been found useful, rather than rashly to overthrow what perhaps cannot on the whole be improved.

As the discriminating characters of the Linnæan system are founded in nature and fact, and depend upon parts essential to every species of plant when in perfection; and as the application of them to practice is, above all other systems, easy and intelligible; I conceive nothing more useful can be done than to perfect, upon its own principles, any parts of this system that experience may show to have been originally defective. This is all I presume to do. Speculative alterations in an artificial system are endless, and scarcely answer any more useful purpose than changing the order of letters in an alphabet. The philosophy of botanical arrangement, or the study of the natural affinities of plants, is quite another matter. But it would be as idle, while we pursue this last-mentioned subject, so deep and so intricate that its most able cultivators are only learners, to lay aside the continual use of the Linnæan system, as it would be for philologists and logicians to slight the convenience, and indeed necessity, of the alphabet, and to substitute the Chinese character in its stead. If the following pages be found to elucidate and to confirm this comparison, I wish the student to keep it ever in view.

The illustration of the Linnæan system of classification, though essential to my purpose, is however but a small part of my aim. To explain and apply to practice those beautiful principles of method, arrangement and discrimination, which render botany not merely an amusement, a motive for taking air and exercise, or an assistance to many other arts and sciences; but a school for the mental powers, an alluring incitement for the young mind to try its growing strength, and a confirmation of the most enlightened understand in some of its sublimest most important truths. That every path tending to ends so desirable may be accessible, I have not confined myself to systematical subjects, wide and various as they are, but I have introduced the anatomy and physiology of plants to the botanical student, wishing to combine all these several objects; so far as least that those who do not cultivate them all, may be sensible of the value of each in itself, and that no disgraceful rivalship or contempt, the offspring of ignorance, may be felt by the pursuers of any to the prejudice of the rest.

I have treated of physiological and anatomical subjects in the first place, because a true knowledge of the structure and parts of plants seems necessary to the right understanding of botanical arrangement; and I trust the most superficial reader will here find enough for that pur , even though he should not be led to pursue these subjects further by himself. I have every where aimed at familiar illustrations and examples, referring, as much as possible, to plants of easy acquisition. In the explanation of botanical terms and characters, I have, besides furnishing a new set of plates with references to the body of the work, always cited a plant for my purpose by its scientific name, with a reference to some good and sufficient figure. For this end I have generally used either my own work English and Exotic Botany, all the plates of which, as well as of the present volume, are the performance of the same excellent botanist as well as artist; or Curtis's Magazine, much of which also was drawn by Mr. Sowerby. I have chosen these as the most comprehensive and popular books, quoting others only when these failed me, or when I had some particular end in view. If this treatise should be adopted for general use in schools or families, the teacher at least will probably be furnished with those works, and will accommodate their contents to the use of the pupils. I am aware of the want of a systematical English description of British plants, on the principles of this Introduction; but that deficiency I hope as soon as possible to supply. In the mean while, Dr. Withering's work may serve the desired purpose, attention being paid only to his original descriptions, or to those quoted from English writers. His index will atone for the changes I cannot appprove in his system. Wherever my book may be found deficient in the explanation of his or any other terms, as I profess to retain only what are necessary, or in some shape useful, the Language of Botany, by Pro , will prove extremely serviceable.

Having thus explained the use and intention of the present work, perhaps a few remarks on the recommendations of the study of Botany, besides what have already been suggested, may not here be misplaced.

I shall not labour to prove how delightful and instructive it is to

"Look through Nature up to Nature's God."

Neither, surely, need I demonstrate, that if any judicious or improved use is to be made of the natural bodies around us, it must be expected from those who discriminate their kinds and study their properties. Of the benefits of natural science in the improvement of many arts, no one doubts. Our food, our physic, our luxuries are improved by it. By the enquiries of the curious new acquisitions are made in remote countries, and our resources of various kinds are augmented. The skill of Linnæus by the most simple observation, founded however on scientific principles, taught his countrymen to destroy an insect, the Cantharis navalis, which had cost the Swedish government many thousand pounds a year by its ravages on the timber of one dockyard only. After its metamorphoses, and the season when the fly laid its eggs, were known, all its ravages were stopped by immersing the timber in water during that period. The same great observer, by his botanical knowledge, detected the cause of a dreadful disease among the horned cattle of the north of Lapland, which had previously been thought equally unaccountable and irremediable, and of which he has given an exquisite account in his Lapland tour, as well as under Cicuta virosa, Engl. Bot. t. 479, in his Flora Lapponica. One man in our days, by his scientific skill alone, has given the bread-fruit to the West-Indies, and his country justly honours his character and pursuits. All this is acknowledged. We are no longer in the infancy of science, in which its utility, not having been proved, might be doubted, nor is it for this that I contend. I would recommend botany for its own sake. I have often alluded to its benefits as a mental exercise, nor can any study exceed it in raising curiosity, gratifying a taste for beauty and ingenuity of contrivance, or sharpening the powers of discrimination. What then can be better adapted for young persons? The chief use of a great part of our education is no other than what I have just mentioned. The languages and the mathematics, however valuable in themselves when acquired, are even more so as they train the youthful mind to thought and observations. In Sweden Natural History is the study of the schools, by which men rise to preferment; and there are no people with more acute or better regulated minds than the Swedes.

To those whose minds and understandings are already formed, this study may be recommended, independently of all other considerations, as a rich source of innocent pleasure. Some people are ever enquiring "what is the use?" of any particular plant, by which they mean "what food or physic, or what materials for the painter or dyer does it afford?" They look on a beautiful flowery meadow with admiration, only in proportion as it affords nauseous drugs or salves. Others consider a botanist with respect only as he may be able to teach them some profitable improvement in tanning, or dyeing, by which they may quickly grow rich, and be then perhaps no longer of any use to mankind or to themselves. They would permit their children to study botany, only because it might possibly lead to professorships, or other lucrative preferment.

These views are not blameable, but they are not the sole end of human existence. Is it not desirable to call the soul from the feverish agitation of worldly pursuits, to the contemplation of Divine Wisdom in the beautiful economy of Nature? Is it not a privilege to walk with God in the garden of creation, and hold converse with his providence? If such elevated feelings do not lead to the study of Nature, it cannot far be pursued without rewarding the student by exciting them.

Rousseau, a great judge of the human heart and observer of human manners, has remarked, that "when science is transplanted from the mountains and woods into cities and worldly society, it loses its genuine charms, and becomes a source of envy, jealousy and rivalship." This is still more true if it be cultivated as a mere source of emolument. But the man who loves botany for its own sake knows no such feelings, nor is he dependent for happiness on situations or scenes that favour their growth. He would find himself neither solitary nor desolate, had he no other companion than a "mountain daisy," that "modest crimson-tipped flower," so sweetly sung by one of Nature's own poets. The humblest weed or moss will ever afford him something to examine or to illustrate, and a great deal to admire. Introduce him to the magnificence of a tropical forest, the enamelled meadows of the Alps, or the wonders of New Holland, and his thoughts will not dwell much upon riches or literary honours, things that

"Play round the head, but come not near the heart."

One idea is indeed worthy to mix in the pure contemplation of Nature, the anticipation of the pleasure we may have to bestow in kindred minds with our own, in sharing with them our discoveries and our acquisitions. This is truly an object worthy of a good man, the pleasure of communicating virtuous disinterested pleasure to those who have the same tastes with ourselves; or of guiding young ingenuous minds to worthy pursuits, and facilitating their acquisition of what we have already obtained. If honours and respectful consideration reward such motives, they flow from a pure source. The giver and the receiver are alike invulnerable, as well as inaccessible, to "envy jealousy or rivalship," and may pardon their attacks without an effort.

The natural history of animals, in many respects even more interesting than botany to man as an animated being, and more striking in some of the phænomena which it displays, is in other points less pleasing to a tender and delicate mind. In botany all is elegance and delight. No painful, disgusting, unhealthy experiments or enquiries are to be made. Its pleasures spring up under our feet, and, as we pursue them, reward us with health and serene satisfaction. None but the most foolish or depraved could derive any thing from it but what is beautiful, or pollute its lovely scenery with unamiable or unhallowed images. Those who do so, either from corrupt taste or malicious design, can be compared only to the fiend entering into the garden of Eden.

Let us turn from this odious picture to the contemplation of Nature, ever new, ever abundant in inexhaustible variety. Whether we scrutinize the damp recesses of woods in the wintry months, when the numerous tribes of mosses are displaying their minute, but highly interesting structure; whether we walk forth in the early spring, when the ruby tips of the hawthorn-bush give the first sign of its approaching vegetaion, or a little after, when the violet welcomes us with its scent, and the primrose with its beauty; whether we contemplate in succession all the profuse flowery treasures of the summer, or the more hidden secrets of Nature at the season when fruits and seeds are forming; the most familiar objects, like old friends, will always afford us something to study and to admire in their characters, while new discoveries will awaken a train of new ideas. The yellow blossoms of the morning, that fold up their delicate leaves as the day advances: others that court and sustain the full blaze of noon; and the pale night-scented tribe, which expand, and diffuse their very sweet fragrance, towards evening, will all please in their turn. Though spring is the season of hope and novelty, to a naturalist more especially, yet the wise provisions and abundant resources of Nature, in the close of the year, will yield an observing mind no less pleasure, than the rich variety of her autumnal tints afford to the admirers of her external charms. The more we study the works of the Creator, the more wisdom, beauty and harmony become manifest, even to our limited apprehensions; and while we admire, it is impossible not to adore.

"Soft roll your incense, herbs, and fruits, and flowers, In mingled clouds, to Him, whose sun exalts, Whose breath perfumes you, and whose pencil paints!"

Chapter 1

INTRODUCTION TO PHYSIOLOGICAL AND SYSTEMATICAL BOTANY.

CHAPTER I.

DISTINCTIONS BETWEEN ANIMALS, VEGETABLES AND FOSSILS.—ON THE VITAL PRINCIPLE ESSENTIAL TO THE TWO FORMER.

Those who with a philosophical eye have contemplated the productions of Nature, have all, by common consent, divided them into three great classes, called the Animal, the Vegetable, and the Mineral or Fossil Kingdoms. These terms are still in general use, and the most superficial observer must be struck with their propriety. The application of them seems at first sight perfectly easy, and in general it is so. Difficulties occur to those only who look very deeply into the subject.

Animals have an organized structure which regularly unfolds itself, and is nourished and supported by air and food; they consequently possess life, and are subject to death; they are moreover endowed with sensation and with spontaneous, as well as voluntary, motion.

Vegetables are organized, supported by air and food, endowed with life and subject to death as well as animals. They have in some instances spontaneous, though we know not that they have voluntary, motion. They are sensible to the action of nourishment, air, and light, and either thrive or languish according to the wholesome or hurtful application of these stimulants. This is evident to all who have ever seen a plant growing in a climate, soil, or situation, not suitable to it. Those who have ever gathered a rose, know but too well how soon it withers; and the familiar application of its fate to that of human life and beauty, is not more striking to the imagination than philosophically and literally true. The sensitive plant is a more astonishing example of the capability of vegetables to be acted upon as living bodies. Other instances of the same kind we shall hereafter have occasion to mention.

The spontaneous movements of plants are almost as readily to be observed as their living principle. The general direction of their branches, and especially of the upper surface of their leaves, though repeatedly disturbed, to the light; the unfolding and closing of their flowers at stated times, or according to favourable or unfavourable circumstances, with some still more curious particulars to be explained in the sequel of this work, are actions undoubtedly depending on their vital principle, and are performed with the greater facility in proportion as that principle is in its greatest vigour. Hence arises a question whether Vegetables are endowed with sensation. As they possess life, irritability and motion, spontaneously directing their organs to what is natural and beneficial to them, and flourishing according to their success in satisfying their wants, may not the exercise of their vital functions be attended with some degree of sensation, however low, and some consequent share of happiness? Such a supposition accords with all the best ideas we can form of the Divine Creator; nor could the consequent uneasiness which plants must suffer, no doubt in a very low degree likewise, from the depredations of animals, bear any comparison with their enjoyment on the whole. However this may be, the want of sensation is most certainly not to be proved with regard to Vegetables, and therefore of no use as a practical means of distinguishing them, in doubtful cases, from Animals.

Some philosophers have made a locomotive power peculiarly characteristic of Animals, not being aware of the true nature of those half-animated beings called Corals and Corallines, which are fixed, as immoveably as any plants, to the bottom of the sea, while indeed many living vegetables swim around them, unattached to the soil, and nourished by the water in which they float. Some have characterized Animals as nourished by their internal, and Vegetables by their external surface, the latter having no such thing as an internal stomach. This is ingenious and tolerably correct; but the proofs of it must fail with respect to those minute and simply-constructed animals the Polypes, and the lower tribes of Worms, whose feelers, put forth into the water, seem scarcely different from roots seeking their food in the earth, and some of which may be turned inside out, like a glove, without any disturbance of their ordinary functions. The most satisfactory remark I have for a long time met with on this difficult subject is that of M. Mirbel, in his Traité d'Anatomie et de Physiologie Végétables, a work I shall often have occasion to quote. He observes, vol. I. p. 19, "that plants alone, have a power of deriving nourishment, though not indeed exclusively, from inorganic matter, mere earths, salts or airs, substances certainly incapable of serving as food for any animals, the latter only feeding on what is or has been organized matter, either of a vegetable or animal nature. So that it should seem to be the office of vegetable life alone to transform dead matter into organized living bodies." This idea appears to me so just, that I have in vain sought for any exception to it.

Let us however descend from these philosophical speculations to purposes of practical utility. It is sufficient for the young student of Natural History to know, that in every case in which he can be in doubt whether he has found a plant or one of the lower orders of animals, the simple experiment of burning will decide the question. The smell of a burnt bone, coralline, or other animal substance, is so peculiar that it can never be mistaken, nor does any known vegetable give out the same odour.

The Mineral Kingdom can never be confounded with the other two. Fossils are masses of mere dead unorganized matter, subject to the laws of chemistry alone; grow indeed, or increasing by the mechanical addition of extraneous substances, or by the laws of chemical attraction, but not fed by nourishment taken into an organized structure. Their curious crystallization bears some resemblance to organization, but performs none of its functions, nor is any thing like a vital principle to be found in this department of Nature.

If it be asked what is this vital principle, so essential to animals and vegetables, but of which fossils are destitute, we must own our complete ignorance. We know it, as we know its Omnipotent Author, by its effects.

Perhaps in the fossil kingdom heat may be equivalent to a vital principle; but heat is not the vital principle of organized bodies, though probably a consequence of that principle.

Living bodies of animals and plants produce heat; and this phænomenon has not, I think, been entirely explained on any chemical principles, though in fossils the production of heat is in most cases tolerably well accounted for. In animals it seems to have the closest possible connexion with the vital energy. But the effects of this vital energy are still more stupendous in the operations constantly going on in every organized body, from our own elaborate frame to the humblest moss or fungus. Those different fluids, so fine and transparent, separated from each other by membranes as fine, which compose the eye, all retain their proper situations (though each fluid individually is perpetually removed and renewed) for sixty, eighty, or a hundred years, or more, while life remains. So do the infinitely small vessels of an almost invisible insect, the fine and pellucid tubes of a plant, all hold their destined fluids, conveying or changing them according to fixed laws, but never permitting them to run into confusion, so long as the vital principle animates their various forms. But no sooner does death happen, than, without any alteration of structure, any apparent change in their material configuration, all is reversed. The eye loses its form and brightness; its membranes let go their contents, which mix in confusion, and thenceforth yield to the laws of chemistry alone. Just so it happens, sooner or later, to the other parts of the animal as well as vegetable frame. Chemical changes, putrefaction and destruction, immediately follow the total privation of life, the importance of which becomes instantly evident when it is no more. I humbly conceive therefore, that if the human understanding can, in any case, flatter itself with obtaining, in the natural world, a glimpse of the immediate agency of the Deity, it is in the contemplation of this vital principle, which seems independent of material organization, and an impulse of his own divine energy.

Chapter 2

CHAPTER II.

DEFINITION OF NATURAL HISTORY, AND PARTICULARLY BOTANY.—OF THE GENERAL TEXTURE OF PLANTS.

Natural History properly signifies that study by which we learn to distinguish from one another the natural bodies, whether Animal, Vegetable or Mineral, around us; to discover as much as possible their nature and properties, and especially their natural dependence on each other in the general scale of beings. In a more extensive sense it may be said to teach their secondary properties, or the various uses to which they have been, or may be, converted, in the service of mankind or of other animals; inasmuch as an acquaintance with their natural qualities is our only sure guide to a knowledge of their arti uses. But as this definition would include many arts and sciences, each of them sufficient to occupy any common mind, as Agriculture, Dietetics, Medicine, and many others; it is sufficient for a philosophical naturalist to be acquainted with the general principles upon which such arts and sciences are founded.

That part of Natural History which concerns plants is called Botany, from βοτάνη, the Greek word for an herb or grass. It may be divided into three branches; 1st, The physiology of plants, or a knowledge of the structure and functions of their different parts; 2dly, The systematical arrangement and denomination of their several kinds; and 3dly, Their œconomical or medical properties. All these objects should be kept in view by an intelligent botanist. The two first are of essential service to each other, and the last is only to be pursued, with any certainty, by such as are versed in the other two. The present publication is intended to explain the fundamental principles of them all, with as much practical illustration as may be necessary for those who wish to become well acquainted with this delightful science. Botany has one advantage over many other useful and necessary studies, that even its first beginnings are pleasing and profitable, though pursued to ever so small an extent; the objects with which it is conversant are in themselves charming, and they become doubly so to those who contemplate them with the additional sense, as it were, which science gives; the pursuit of these objects is an exercise no less healthful to the body, than the observation of their laws and characters is to the mind.

In studying the functions of the Vegetable frame, we must constantly remember that it is not merely a collection of tubes or vessels holding different fluids, but that it is endowed with life, and consequently able not only to imbibe particular fluids, but to alter their nature according to certain laws, that is, to form peculiar secretions. This is the exclusive property of a living being. Animals secrete milk and fat from food which has no resemblance to those substances; so Vegetables secrete gum, sugar, and various resinous substances from the uniform juices of the earth, or perhaps from mere water and air. The most different and discordant fluids, separated only by the finest film or membrane, are, as we have already observed, kept perfectly distinct, while life remains; but no sooner does the vital principle depart, than secretion, as well as the due preservation of what has been secreted, are both at an end, and the principle of dissolution reigns absolute.

Before we can examine the physiology of vegetables, it is necessary to acquire some idea of their structure.

Much light has been thrown upon the general texture of Vegetables by the microscopic figures of Grew, Malpighi and others, repeated by Dr. Thornton in his Illustration of the Linnaean System, but more especially by the recent observations and highly magnified dissections of M. Mirbel. See his Table of Vegetable Anatomy in the work already mentioned. From preceding writers we had learned the general tubular or vascular structure of the vegetable body, and the existence of some peculiar spirally-coated vessels in many plants. On these slender foundations physiologists have at their pleasure, constructed various theories, relative to the motion of the sap, respiration and other functions, presumed to be analogous to those of animals. The anatomical observations of Mirbel go further than those of Grew, &c., and it is necessary to give a short account of his discoveries.

He finds, by the help of the highest magnifying powers, that the vegetable body is a continued mass of tubes and cells; the former extended indefinitely, the latter frequently and regularly interrupted by transverse partitions. These partitions being ranged alternately in the corresponding cells, and each cell increasing somewhat in diameter after its first formation, except where restrained by the transverse partitions, seems to account for their hexagonal figure. See Tab. I. f. a. The membranous sides of all these cells and tubes are very thin, more or less transparent, often porous, variously perforated or torn. Of the tubes, some are without any lateral perforations, f. b, at least for a considerable ex

others pierced with holes ranged in a close spiral line, f. c; in others several of these holes run together, as it were, into interrupted spiral clefts, f. d; and in some those clefts are continued, so that the whole tube, more or less, is cut into a spiral line, f. e; which, in some young branches and tender leaves, will unroll to a great extent, when they are gently torn asunder. The cellular texture especially is extended to every part of the vegetable body, even into the thin skin, called the cuticle, which covers every external part, and into the fine hairs or down which, in some instances, clothe the cuticle itself.