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 About the year 1670 Dr Robert Morison (1620–1683), 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 according as they were woody or herbaceous, and taking into account the nature of the flowers and fruit. In 1690 Rivinus promulgated a classification founded chiefly on the forms of the flowers. J. P. de Tournefort (1656–1708), who about the same time took up the subject of vegetable taxonomy, was long at the head of the French school of botany, and published a systematic arrangement in 1694–1700. He described about 8000 species of plants, and distributed them into twenty-two 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. The system of Tournefort was for a long time adopted on the continent, but was ultimately displaced by that of Carl von Linné, or (q.v.; 1707–1778).

The system of Linnaeus was founded on characters derived from the stamens and pistils, the so-called sexual organs of the flower, and hence it is often called the sexual system. It is an artificial method, because it takes into account only a few marked characters in plants, and does not propose to unite them by natural affinities. It is an index to a department of the book of nature, and as such is useful to the student. It does not aspire to any higher character, and although it cannot be looked upon as a scientific and natural arrangement, still it has a certain facility of application which at once commended it. It does not of itself give the student a view of the true relations of plants, and by leading to the discovery of the name of a plant, it is only a stepping-stone to the natural system. Linnaeus himself claimed nothing higher for it. He says—“Methodi Naturalis fragmenta studiose inquirenda sunt. Primum et ultimum hoc in botanicis desideratum est. Natura non facit saltus. Plantae omnes utrinque affinitatem monstrant, uti territorium in mappa geographica.” Accordingly, besides his artificial index, he also promulgated fragments of a natural method of arrangement.

The Linnean system was strongly supported by Sir James Edward Smith (1759–1828), who adopted it in his English Flora, and who also became possessor of the Linnean collection. The system was for a long time the only one taught in the schools of Britain, even after it had been discarded by those in France and in other continental countries.

The foundation of botanic gardens during the 16th and 17th centuries did much in the way of advancing botany. They were at first appropriated chiefly to the cultivation of medicinal plants. This was especially the case at universities, where medical schools existed. The first botanic garden was established at Padua in 1545, and was followed by that of Pisa. The garden at Leiden dates from 1577, that at Leipzig from 1579. Gardens also early existed at Florence and Bologna. The Montpellier garden was founded in 1592, that of Giessen in 1605, of Strassburg in 1620, of Altdorf in 1625, and of Jena in 1629. The Jardin des Plantes at Paris was established in 1626, and the Upsala garden in 1627. The botanic garden at Oxford was founded in 1632. The garden at Edinburgh was founded by Sir Andrew Balfour and Sir Robert Sibbald in 1670, and, under the name of the Physic Garden, was placed under the superintendence of James Sutherland, afterwards professor of botany in the university. The garden at Kew dates from about 1730, when Frederick, prince of Wales, obtained a long lease of Kew House and its gardens from the Capel family. After his death in 1751 his widow, Princess Augusta of Saxe-Gotha, showed great interest in their scientific development, and in 1759 engaged William Aiton to establish a Physic Garden. The garden of the Royal Dublin Society at Glasnevin was opened about 1796; that of Trinity College, Dublin, in 1807; and that of Glasgow in 1818. The Madrid garden dates from 1763, and that of Coimbra from 1773. Jean Gesner (1709–1790), a Swiss physician and botanist, states that at the end of the 18th century there were 1600 botanic gardens in Europe.

A new era dawned on botanical classification with the work of Antoine Laurent de Jussieu (1748–1836). His uncle, Bernard de Jussieu, had adopted the principles of Linnaeus’s Fragmenta in his arrangement of the plants in the royal garden at the Trianon. At an early age Antoine became botanical demonstrator in the Jardin des Plantes, and was thus led to devote his time to the science of botany. Being called upon to arrange the plants in the garden, he necessarily had to consider the best method of doing so, and, following the lines already suggested by his uncle, adopted a system founded in a certain degree on that of Ray, in which he embraced all the discoveries in organography, adopted the simplicity of the Linnean definitions, and displayed the natural affinities of plants. His Genera Plantarum, begun in 1778, and finally published in 1789, was an important advance, and formed the basis of all natural classifications. One of the early supporters of this natural method was Augustin Pyramus de Candolle (1778–1841), who in 1813 published his Théorie élémentaire de la botanique, in which he showed that the affinities of plants are to be sought by the comparative study of the form and development of organs (morphology), not of their functions (physiology). His Prodromus Systematis Naturalis Regni Vegetabilis was intended to embrace an arrangement and description of all known plants. The 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 orders of Dicotyledonous plants. The system followed by de Candolle is a modification of that of Jussieu.

In arranging plants according to a natural method, we require to have a thorough knowledge of structural and morphological botany, and hence we find that the advances made in these departments have materially aided the efforts of systematic botanists.

Robert Brown (1773–1858) was the first British botanist to support and advocate the natural system of classification. The publication of his Prodromus Florae Novae Hollandiae (in 1810), according to the natural method, led the way to the adoption of that method in the universities and schools of Britain. In 1827 Brown announced his important discovery of the distinction between Angiosperms and Gymnosperms, and the philosophical character of his work led A. von Humboldt to refer to him as “Botanicorum facile princeps.” In 1830 John Lindley published the first edition of his Introduction to the Natural System, embodying a slight modification of de Candolle’s system. From the year 1832 up to 1859 great advances were made in systematic botany, both in Britain and on the continent of Europe. The Enchiridion and Genera Plantarum of S. L. Endlicher (1804–1849), the Prodromus of de Candolle, and the Vegetable Kingdom (1846) of J. Lindley became the guides in systematic botany, according to the natural system.

The least satisfactory part of all these systems was that concerned with the lower plants or Cryptogams as contrasted with the higher or flowering plants (Phanerogams). The development of the compound microscope rendered possible the accurate study of their life-histories; and the publication in 1851 of the results of Wilhelm 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 Thallophyta, Bryophyta, Pteridophyta and Phanerogamae, the last named including Gymnospermae and Angiospermae.

A system of classification for the Phanerogams, or, as they are frequently now called, Spermatophyta (seed-plants), which has been much used in Great Britain and in America, is that of Bentham and Hooker, whose Genera Plantarum (1862–1883) is a descriptive account of all the genera of flowering plants, based on their careful examination. The arrangement is a modification of that adopted by the de Candolles. Another system differing somewhat in detail is that of A. W. Eichler (Berlin, 1883), a