BOTANY

From Agepedia

BOTANY, the science of plants, may be divided into two parts, one of which describes their external appearance, and is sometimes called phytography; the other treats of their internal structure and organic action, and may be termed philosophical botany or phytonomy. The former requires a perfect knowledge of terminology, the latter a thorough knowledge of the plants themselves, with a view to a systematic classification of them, according to fixed principles. The necessity of such a classification must have been felt as soon as the number of known plants became great, and their relations and analogies obvious. At the time of the revival of letters, hardly 1500 plants were known from the descriptions of the ancients. At present, at a moderate estimation, more than 50,000 have been described. It is obviously impossible to introduce order into this infinite chaos, or to acquire any distinct knowledge, without the aid of general principles. Even in the 16th and 17th centuries, the founders of botanical science perceived that in plants, as well as in all other natural bodies, the essential and necessary parts must be distinguished from the accidental, and that a scientific classification must be founded on the former alone. Now it was obvious that the production of fruit and seed is the ultimate object of vegetation, and, accordingly, in the first attempts at classification, the relations and component parts of the seed and of the fruit were made the foundation of the arrangement. This arrangement was confirmed by an observation of the uniformity of nature in the formation of those parts in plants of similar kinds. But it was found, also, that uniformity in these formations prevailed in too great a number of plants to allow them alone to be made the distinguishing characteristics. It became, therefore, necessaiy to have recourse to other parts. The flower was first chosen, as it presents a great variety of forms, and, at the same time, a uniformity of structure. But the limits to this uniformity, and the absence of flowers in innumerable plants, with the consideration that they are not essential, suggested to the immortal founder of modern scientific botany the idea that the sexual parts are most intimately related to the growth of the fruit, and that they are, therefore, of the greatest importance, and furnish better grounds of classification than the flower. A general principle was thus established, fertile in consequences, excellently adapted to facilitate the diffusion and extend the sphere of the science. The Linnsean system was founded exclusively on the relations of the sexual parts. Linnaeus divided all known plants into two general divisions, one of which has visible sexual parts [phanerogamous), while in the other they are invisible or wanting (ciyptogamous). The first division comprehends the 23 first classes of his system, which are distinguished according to the situation of the sexual parts in the same or in separate flowers, their number, their length, &c. If any system has introduced order in the midst of variety, and shed light on the immense diversities of nature, it is that of Linnseus. Hence, even those who have departed from it in their writings have considered it necessary for elementary instruction. Many objections, however, are brought against it. It has been made a question whether it is fitted for the investigation and classification of unknown plants. It is said that the sexual parts may be very different in similar plants; that he never will have a complete idea of nature, who proceeds only on one principle. It has, therefore, been thought necessaiy to find a more natural arrangement. (See Plants.) In order to follow nature, we must look at every part; at the internal structure, as well as the external relations, analogies and differences. This can be done only by a profound and toilsome investigation, of which the mere follower of a system has hardly a notion. Seed is considered as the ultimate object of vegetation. Its parts, their formation, situation, and other relations, must be critically examined. The most perfect natural system, in modern times, is that of Jussieu, particularly as enlarged by Decandolle. (See Decandolle's Regni vegetabilis Systema naturale, his TMorie elementaire de la Botanique, and his Prodromus Systematis naturalis Uegni vegetabilis; also the JYouveaux Elemens de la Botanique, by Richard.) The second general division of this science begins with the investigation of the internal structure, or the anatomy of plants. This study has been recently cultivated, by the Germans, to an extent, which, 30 years ago, could hardly have been conceived. It is closely connected with the first division, if the plants are studied in their natural order. Without good microscopes, and the aid of the best works in this branch, a distinct knowledge of the structure of plants cannot easily be obtained. Chemical botany must, be connected with the anatomy of plants. Their constituent parts, their various changes, and the different combinations of their liquid and solid parts, are to be examined. From those, at last, we ascend to the laws of vegetable life, which are, in general, the same as those of animal life. Animal physiology must, therefore, be intimately united with the physiology of plants. Connected with the latter are two branches of knowledge, which the botanist cannot well dispense with, since they offer the most important conclusions on the economy of nature, on the history of the earth, and on the application of science to the arts. These are, first, the science of the deformities and diseases of plants, which can be made certain only by correct physiological views, and which is of great value in gardening, agriculture, and the cultivation of woods; and, second, a knowledge of the mode in which plants have been spread over the earth. If we study the forms of vegetation which have come to us from distant ages, in the fiotz formations, this observation affords the most interesting discoveries in relation to the history of our earth. If we trace the laws by which vegetation seems to have been distributed, we extend our knowledge of the general action of nature, and arrive at conclusions which may be of great practical utility. The work of Sprengel on the structure and nature of plants, is, perhaps, the most complete. Separate parts of the anatomy of plants nave been treated of by Link, Treviranus and Moldenhawer; vegetable chemistry by Senebier, Saussure and Schrader. Histoiy of the Science. Of the two general divisions of BOTANY, the physiological or philosophical is the elder. Before the Greek philosophers attempted to distinguish classes and species of plants, they examined the laws of vegetable life, the difference of plants from animals, and, as far as it could be done with the naked eye, their structure. Theophrastus of Eresus is the creator of philosophical botany, which he treated on a great and original plan. From the writings of the Alexandrians, and from original observations, Dioscorides of Anazarba, in the first century of the Christian era, compiled a work, which contains imperfect descriptions of about 1200 plants, the medical qualities of which were more attended to by the author than the description of their characteristics or their philosophical classification. This work continued, for 15 centuries, the only source of botanical knowledge. The Persian and Arabian physicians added about 200 plants, which were unknown to the Greeks, and, consequently, the number of known plants, at the time of the revival of letters, was about 1400. Germany has the merit of having founded historical botany. The obvious imperfections of Dioscorides, when the plants of Germany came to be investigated, and the extravagances into which those persons fell, who attempted to apply his descriptions to German plants, impelled Hieronymus of Brunswick, Otho Braunfelsius, Leon. Fuchsius, Hieron. Tragus and Conrad Gesner, to examine the vegetable productions of their country, independently of Dioscorides, and to represent them in woodcuts. Gesner first started the idea that the parts of fructification were the most essential, and that plants must be classified with reference to them. They were followed, in the 16th century, by the Italians, Peter Matthiolus, Andr. CsesaJpinus, Prosp. Alpinus and Fab. Columna; the Belgians, Dodonseus, Clusius and Lobelius. Among the botanists of this period, who extended the science by their labors in collecting specimens, are the French Da^echamp, the English Gerard, the German Joach. Camerarius, Tabernsemontanus and John Bauhin, whose brother Gaspard not only increased the number of known plants by numerous discoveries, but endeavored to reform the nomenclature, which had become much confused by the multiplication of names of the same plant. These are the fathers of botany, whose standard works still reward examination. By the exertions of these men, the number of known plants, at the beginning of the 17th century, amounted to 5500. The necessity of classification increased with the quantity of materials. Lobelius and John Bauhin adopted the natural division of trees, grasses, &c, without reference to any general principle. Andreas Cassalpinus, by the advice of Conrad Gesner, fixed upon the fruit and the seed as the foundation of a classification, which is still retained by many of his followers, who are c&lhdfructists. In the 17th century, new methods were introduced by Robert Morison and John Ray; the latter of whom attended to the structure of the corolla and its parts, while Rivinus considered only the regularity or irregularity of its shape, and Tournefort its resemblance to other objects. The number of known plants was increased by Morison, Plukenet, Barrelier, Boccone, van Rheede, Petiver and Plumier. In the 17th century, the foundation of botanical anatomy was laid by Grew and Malpighi; botanical chemistry was founded by Homberg, Dodart and Mariotte ; and the difference of sex was discovered by Grew, Morland and Rud. Jak. Camerarius. This discovery Micheli attempted to extend even to the lower degrees of organization, moss, lichens and sponges. To such predecessors, and to the great collectors of herbariums, Rumphius, Parkinson, Sloane, Flacourt, Sommelyn, Buxbaum, Ammann and Feuillee, the immortal Linnseus was indebted, in part, for the idea on which his system was founded, and for his great stores of botanical knowledge. When the first edition of his Species Plantarum was published, he was acquainted with 7300 species ; in the second edition, with 8800. If we consider that a moderate herbarium now contains from 11,000 to 12,000 species, we must be astonished at the increase in the number of known plants in 60 years. The two sexes of Linnseus were afterwards extended, by Dillenius, Schmidel and Hedwig, to the imperfect vegetables. This system was opposed by Adanson, Alston and Haller; it was extended still farther by Schreber Scopoli, Crantz and Jacquin. In the 18th century, numerous discoveries in the vegetable world were made by John Burmamij J. G. Gmelin, Pallas, Forskak For ster, Hasselquist, Browne, Jacquin, Aublet, Sommerson, Stahl, Swartz, Aiton. Vegetable physiology was enlarged and enriched with new discoveries by Bonnet, Du Hamel, Hill, Koelreuter and Sennebier, and thus botany approached its present degree of improvement. (See Sprengel's History of Botany, 2 vols., Leipsic, 1818.) An outline of the Linnsean system is to be found in the article Plants.