TAXONOMY. 



TAXONOMY is tlie part of Botany which treats of classification ; i.e. the methodical 

 distribution of plants in groups, named Classes, Families (or Orders), Genera, and. 

 Species. All the individuals or separate beings of the Vegetable Kingdom which 

 resemble each other as much as they resemble their parents and their posterity, form 

 collectively a species. 



All the species which resemble each other, although differing in certain charac- 

 ters which become the distinctive sign of each, form collectively a genus, which takes 

 the name of the principal species. 1 Thus, the Cabbage, the Turnip, the Colza, the 

 Radish, are species of the same genus, which has received the name of Cabbage. As 

 a necessary consequence, each plant belonging to a genus and to a species has 

 received two names, that of the genus and that of the species, i.e. the generic and 

 specific name, and we say the Drum-head Cabbage, the Turnip Cabbage, the Colza 

 Cabbage, the Radish Cabbage. 



All the genera which resemble each other form collectively a family (or order) ;< 

 thus, the genus Cabbage, the genus Stock, the genus Thlaspi, the genus Cochlearia, 

 belong to the same family, namely that of Cruciferce. 



Those families which are allied are united into classes ; and thus all the species 

 composing the Vegetable Kingdom are classified. 



But the species itself may be subdivided : individuals of the same species may be 

 placed under different conditions ; one may vegetate on a barren rock, another in a 

 swamp ; this will be shaded, that torn by the wind ; man himself may intentionally 

 create such differences, and combine them according to his wants. The vegetable 

 under these diverse influences will finally undergo changes in its sensible qualities, 

 such as size of root ; the size, consistency, and duration of stem ; the form, colour, and 

 scent of its floral whorls, the taste of its fruit, &c. But these changes, however con- 

 siderable, will not destroy the primitive character of the species, which will always 

 be discoverable throughout its modifications. A collection of individuals of the 

 same species which have undergone such modifications bears the name of variety. 

 The characters of a variety, depending on accidental causes, are never constant ; as 

 soon as the influencing cause ceases, the change ceases, and the primitive species 

 reappears in its original form. The cultivated Cabbage is an example, of which six 



1 This holds only in a limited sense. ED. 



