CLASSIFICATION. 



IN classification it is necessary first to explain what is to be 

 understood by a species. A species comprises all the indivi- 

 dual plants which resemble each other sufficiently to make it 

 apparent that they all are, or may have been, descended from 

 a common ancestor, as for instance anyone would feel certain 

 of this as to all the oak trees or all the mango trees that he 

 may meet with from time to time. These individuals may 

 often differ from each other in many particulars (as well as in 

 the mere size of the plants), such as the colour of the flowers, 

 the size of the leaves, etc. ; but these differences would 

 scarcely hide from any one the identity of the trees, and are 

 such as experience shows are likely to occur in seedlings 

 raised from the same tree or herb. 



When a large number of individuals of a species differ from 

 the others in any striking particular they constitute a variety ; 

 but it is almost needless to say that botanists constantly differ as 

 to whether a particular variation is sufficient to make a separate 

 species or merely to constitute a variety. Varieties are much 

 more numerous and striking in well-known garden flowers (e.g. 

 roses and tulips) than in wild flowers ; because it is to the 

 interests of florists in the case of garden flowers to make and 

 perpetuate differences in the blossoms of some plants and the 

 foliage of others. 



The known species of plants (now near 100,000) are grouped 

 into genera, a genus containing a number of species resembling 

 each other in the most important points of structure. Each 

 genus has a Latin (substantive) name; and each species belong- 

 ing to the genus has that generic name, as it is called, with a 

 Latin adjective joined to it, the two words forming the specific 

 name. Thus the teak tree is Tectona grandis; the shoe flower 

 and the vegetable Wiendi are two species of the same genus, 

 Hibiscus, the former being H. rosasinensis, and the latter //. 



