BOTANY, the science which includes everything relating to the vegetable kingdom, whether in a living or in a fossil state. The name is derived from the Greek gorluni, a plant. It embraces a consideration of the external forms of plants—of their anatomi cal structure, however minute—of the functions which they per form—of their classification—of their distribution over the globe at the present and at former epochs—and of the uses to which they are subservient. It examines the plant in its earliest state of development, and follows it through all its stages of progress until it attains maturity. It takes a comprehensive view of all the plants which cover the earth, from the minutest organism, only visible by aid of the microscope, to the tall forest tree. It marks the relations which subsist between all members of the plant world, including those between existing groups and those known only from their fossilized remains preserved in the rocks. We deal here with the history and evolution of the science.
One of the earliest attempts at a methodical arrangement of plants was made in Florence by Andreas Caesalpinus (1519 1603), who is called by Linnaeus prinvus verus systematicus. In his work De Plantis (1583), he distributed the 1,520 plants then known into fifteen classes, the distinguishing characters being taken from the fruit.
The Englishman John Ray (1627-1705) did much to advance the science of botany, and was also a good zoologist. He promul gated a system which may be considered as the beginning of a natural system (Methodus Plantarum, 1682). He separated flowering from flowerless plants (ferns, mosses, seaweeds, fungi, etc.) and divided the former into Dicotyledons (with a pair of seed-leaves) and Monocotyledons (with a single seed-leaf ). His orders (or "classes") were founded to some extent on a correct idea of the affinities of plants, and he far outstripped his con temporaries in his enlightened views of arrangement.
In 1669 Robert Morison' (162o-83), the first professor of botany at Oxford, published a systematic arrangement of plants, largely on the lines previously suggested by Caesalpinus. He divided them into eighteen classes, distinguishing plants accord ing as they were woody or herbaceous, and taking into account the nature of the flowers and fruit. In 1690 promulgated a classification founded chiefly on the forms of flowers. J. P. de (1656-1708), who about the same time took up the subject of plant-classification, was long at the head of the French school of botany, and published a systematic arrangement in 1694-1700. He described about 8,000 species of plants, and dis tributed them into 22 classes, chiefly according to the form of the corolla, distinguishing herbs and under-shrubs on the one hand from trees and shrubs on the other. Tournefort's system was for a long time adopted on the Continent, but was ultimately dis placed by that of Carl von Linne, or Linnaeus (1707-78, q.v.).
The Linnaean system was strongly supported by Sir James Edward Smith (1758-1828), who adopted it in his English Flora, and who also became possessor of the Linnaean collection. The system was for long the only one taught in the schools of Britain, even after it had been discarded by those in Continental countries.
(Augustus Quirinus) paterno nomine Bachmann, Intro. ductio generalis in Rem Herbarium (Lipsiae, 169o) .
P. de Tournefort, Elemens de botanique (1694) ; Institutiones Rei Herbariae (1700) .
description of all known plants. This work was continued after his death, by his son Alphonse de Candolle, with the aid of other eminent botanists, and embraces descriptions of the genera and species of the families of Dicotyledons. The system followed by de Candolle is a modification of that of Jussieu.
In arranging plants according to a natural method, we require a thorough comparative knowledge of the form and structure of plant-organs and hence the advances made in these departments have materially aided the efforts of systematic botanists.
The least satisfactory part of all these systems was that con cerned with the lower plants or cryptogams, i.e., plants without an obvious flower producing a seed, as contrasted with the higher or flowering plants (phanerogams). The development of the com pound microscope rendered possible the accurate study of their life-histories; and the publication, in 1851, of the results of Wil helm Hofmeister's researches on the comparative embryology of the higher Cryptogamia shed a flood of light on their relationships to each other and to the higher plants, and supplied the basis for the distinction of the great groups in ascending order Thallophyta (seaweeds, fungi, lichens) Bryophyta (mosses), Pteridophyta (ferns) and Phanerogamae (seed-bearing plants) the last named including Gymnospermae (seeds not enclosed in a fruit) and Angiospermae (seeds enclosed in a fruit).
Charles Darwin's Origin of Species (1859) and the consequent theory of evolution suggested a new point of view for botanists. It became evident that a natural system of classification should present not only existing relationships of plant-families but also their past relationships ; a perfect system should be a genealogical tree representing the story of plant-life from its remote origin. But plant-families at the present day represent only the end branches of a great tree most of which has disappeared and the reconstruction of which with the aid of the fragments that have been preserved in the rocks must be a matter of conjecture. The study of phylogeny, i.e., the reconstruction of the genealogical tree, has received much attention from botanists in recent years, some account of this will be found in the articles on the various groups GYMNOSPERMS, ANGIOSPERMS, etc.
Nehemiah Grew seems to have been the first to describe, in a paper on the Anatomy of Plants read before the Royal Society in November 1676, the functions of the stamens and pistils. Grew speaks of the attire, or the stamens, as being the male parts, and refers to conversations with Sir Thomas Millington, Sedleian pro fessor at Oxford, to whom the credit of the sexual theory seems really to belong. Grew says that "when the attire or apices break or open, the globules or dust falls down on the seedcase or uterus, and touches it with a prolific virtue." Ray adopted Grew's views, and states various arguments to prove their correctness in the preface to his work on European plants, published in 1694. In the same year R. J. Camerarius, professor of botany and medicine at Tubingen, published a letter on the sexes of plants, in which he refers to the stamens and pistils as the organs of reproduction, and states the difficulties he had encountered in determining the organs of cryptogamic plants. In 1703, Samuel Morland, in a paper read before the Royal Society (Phil. Trans. xxiii., 1474) stated that the farina (pollen) "is a congeries of seminal plants, one of which must be conveyed into every ovum before it can become prolific." In this remarkable statement he seems to antici pate in part the discoveries afterwards made as to pollen tubes. In 1711, E. F. Geoffroy, in a memoir presented to the Royal Academy at Paris, supported the views of Grew and others as to the sexes of plants (Mem. Acad. Roy. Sci., 1711, 207). He states that the germ is never to be seen in the seed till the apices (anthers) shed their dust; and that if the stamina be cut out be fore the apices open, the seed will either not ripen, or be barren if it ripens. He mentions two experiments made by him to prove this—one by cutting off the staminal flowers in maize, and the other by rearing the female plant of mercurialis apart from the male. In these instances most of the flowers were abortive, but a few were fertile, which he attributes to the dust of the apices having been wafted by the wind from other plants.
Linnaeus took up the subject in the inauguration of his sexual system. He divided plants into sexual and asexual, the former being phanerogamous or flowering, and the latter cryptogamous or flowerless. In the latter division of plants he could not detect stamens and pistils, and he did not investigate the mode in which their germs were produced. He was no physiologist, and did not promulgate any views as to the embryogenic process. His fol lowers were chiefly engaged in the arrangement and classification of plants, and while descriptive botany made great advances the physiological department of the science was neglected. His views were not, however, adopted at once by all, for we find Charles Alston stating arguments against them in his Dissertation on the Sexes of Plants (1754) ; (See Essays and Observations, Physical and Literary; Medical Society of Edinburgh, i., 205 ) • Als ton's observations were founded on what occurred in certain uni sexual plants, such as mercurialis, spinach, hemp, hop and bryony. The conclusion at which he arrives is that the pollen is not in all flowering plants necessary for impregnation, for fertile seeds can be produced without its influence. He supports parthenogenesis in some plants. Soon after the promulgation of Linnaeus's method of classification, the attention of botanists was directed to the study of cryptogamic plants, and the valuable work of Johann Hedwig (173o-99) on the reproductive organs of mosses made its appearance in 1782. He was one of the first to point out the existence of certain cellular bodies in these plants which appeared to perform the functions of reproductive bodies, and to them the names antheridia and pistillidia were given. This opened up a new field of research, and led the way in the study of cryptogamic reproduction, which has since been much advanced by the labours of numerous workers. The interesting observations of Morland, already quoted, seem to have been neglected, and botanists were for a long time content to know that the scattering of the pollen from the anther, and its application to the stigma, were necessary for the production of perfect seed, but the stages of the process of fertilization remained unexplored, and no one attempted to raise the veil which hung over the subject of embryogeny.
In 1815, L. C. Treviranus, professor of botany in Bonn, roused the attention of botanists to the development of the embryo, but although he made valuable researches, he did not add much in the way of new information. In 1823, G. B. Amici discovered the existence of pollen-tubes, and he was followed by A. T. Brongniart (1801-76) and Robert Brown. The latter traced the tubes as far as the nucleus of the ovule. These important dis coveries mark a new epoch in embryology, and may be said to be the foundation of the views now entertained, which were material ly aided by the subsequent elucidation of the process of cytogene sis, or cell-development, by Schleiden, Schwann, Mohl and others. The whole subject of fertilization and development of the embryo has been more recently investigated with great assiduity and zeal, as regards both cryptogamous and phanerogamous plants, and details must be sought in the various special articles. The obser vations of Darwin as to the fertilization of orchids, Primula, Lythrur, and other flowering plants, and the part which insects take in this function, gave an explanation of the observations of Christian Konrad Sprengel, made at the close of the 18th century, and opened up a new phase in the study of botany, which has been followed by Hermann Muller, Federico Delpino and others. This phase of the subject, the transference of the pollen from the stamens to the stigma of the flower, is now distinguished as pollination, the term fertilization being restricted to the processes directly associated with the union of the male and female cells which occurs in all plant-groups. (An excellent handbook is Paul Knuth's Handbook of Pollination, Eng. trans., 1906–o9.) Physiology of Plants.—One of the earliest workers at plant physiology was Stephen Hales. In his Vegetable Staticks (1727) he gave an account of numerous experiments and observations which he had made on the nutrition of plants and the movement of sap. He showed that the gaseous constituents of the air con tribute largely to the nourishment of plants, and that the leaves are the organs which elaborate the food; the importance of leaves in nutrition had been previously pointed out by Malpighi in a short account of nutrition which forms an appendix to his anatomical work. The birth of modern chemistry in the work of J. Priestley and A. L. Lavoisier, at the close of the 18th century, made possible the scientific study of plant-nutrition, though Jan Ingenhousz in 1779 discovered that plants incessantly give out carbonic acid gas, but the green leaves and shoots only exhale oxygen in sunlight or clear daylight, thereby indicating the dis tinction between assimilation of carbonic acid gas (photosynthe sis) and respiration. N. T. de Saussure (1767-1845) gave pre cision to the science of plant-nutrition by use of quantitative methods. The subjects of plant-nutrition and respiration were further studied by R. J. H. Dutrochet towards the middle of the century, and J. von Liebig's application of chemistry to agricul ture and physiology put beyond question the parts played by the atmosphere and the soil in the nutrition of plants.
The phenomena of movements of the organs of plants attracted the attention of John Ray (1693), who ascribed the movements of the leaf of mimosa and others to alteration in temperature. Linnaeus also studied the periodical movements of flowers and leaves, and referred to the assumption of the night-position as the sleep-movement. Early in the 19th century, Andrew Knight showed by experiment that the vertical growth of stems and roots is due to the influence of gravitation, and made other observa tions on the relation between the position assumed by plant organs and external directive forces, and later Dutrochet, H. von Mohl and others contributed to the advance of this phase of plant physiology. Darwin's experiments in reference to the movements of climbing and twining plants, and of leaves in insectivorous plants, opened up a wide field of enquiry as to the relation be tween plants and the various external factors, which has attracted numerous workers. By the work of Julius Sachs and his pupils plant physiology was established on a scientific basis, and became an important part of the study of plants, for the development of which reference may be made to the article PLANTS : Physiology. The study of form and development has advanced under the name morphology, with the progress of which are associated the names of K. Goebel, Eduard Strasburger, A. de Bary, F. O. Bower and others (see PLANTS : Morphology), while more recently, as cy tology (q.v.), the intimate study of the cell and its contents has attracted considerable attention.
Subdivisions.—Botany may be divided into the following departments : I. Structural, having reference to the form and structure of the various parts, including (a) Morphology, the study of the general form of the organs and their development—to be found treated in detail in a series of articles dealing with the great subdivisions of plants (see ANGIOSPERMS, GYMNOSPERMS, PTERI