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xx which may therefore be supposed to have descended from a single individual.

Species are perhaps the only truly natural divisions of plants; but naturalists, for convenience of reference and description, have been compelled to arrange them in more or less artificial groups or families. Certain plants possessing a great resemblance to each other in structure are formed into genera; these are collected into larger groups called orders, and the orders into subclasses and classes. All these divisions are dependent upon some general similarity in the structure of the plants composing them, usually in that of the flower and seed, those organs being less liable to variation than others. Linnæus, the founder of modern systematic Natural History, adopted the number and position of the stamens and pistils as the basis of his classification of the flowering plants, forming the names of most of his classes by affixing the word andria, the synonym of stamen, to the Greek numeral expressing the number of those organs present in the flower: thus plants, the flowers of which contained but one stamen, were called Monandria; those having two, Diandria. The orders or subdivisions of these were formed in a similar way by adding the word gynia, adopted as synonymous with pistil, to the numeral. Other divisions he made dependent upon the connexion of the filaments or anthers, and the monœcious or diœcious character of the plant. We have not space to enter into the details of his system, and have only made allusion to it because it has been adopted in the 'English Botany' and some other works of reference still in use. Its simplicity rendered it of easy application by the unscientific; but it had the great disadvantage of bringing together plants of widely different affinities into the same artificial section, owing to some coincidence in the development of a single organ, while it separated others evidently closely connected; it is therefore no longer used by naturalists, and the mode of classification adopted by Jussieu and DeCandolle, variously modified by other botanists, has been substituted.