The alphabetical arrangement of plants, the most artificial, or at least the most unnatural of all, was at one time much followed by botanists, especially in local catalogues. The time of flowering, the place of growth, the general habit or appearance, and various other circumstances, formed a basis to other arrangements. In the sixteenth century, Conrad Gesner showed that the flower and fruit were the only parts capable of affording determinate characters. Cæsalpinus, physician to Pope Clement VIII., presented the first model of a botanical system, in his Libri de Plantis, published in 1583. The characters are derived principally from the fruit, though likewise from the flowers, and the duration of plants. The two Bauhins, Ray, and Morison, published systems constructed on similar principles. Others, as Rivinus and Ludwig, derived their characters from the corolla. All these methods, however, successively passed into neglect, and were superseded by that of Tournefort, who was professor of botany at the Garden of Plants in Paris, in the reign of Louis XIV. This eminent writer was the first who defined the species and genera with any degree of precision. He arranged plants according to the various forms of the corolla, dividing them primarily, according to the consistence of the stem, into Herbs and Trees. The former were subdivided into three orders; those with simple flowers, those with compound flowers, and those destitute of flowers. The following is an outline of his system:—
Division I. Herbs.
* With simple flowers.
Corolla of one piece, regular.
Class I. Campaniformes, with a regular corolla, of one piece, and resembling a bell; as the convolvulus.
II. Infundibuliformes, with a regular corolla, of one piece, and resembling a funnel; as the tobacco.
Corolla of one piece, irregular.
III. Personatæ, with an irregular corolla, of one piece, resembling an antique mask; as the foxglove.
IV. Labiatæ, with an irregular corolla, of one piece, divided into two lips; as the sage.
Corolla of several pieces, regular.