i6 PLANT NAMES 



this point a brief statement of the principles of 

 classification adopted by botanists. We must not 

 suppose that the Creator made the vegetation that 

 we now find in the world divided into distinct com- 

 partments like those in a museum. Botanists have 

 done that for reasons of convenience, and the 

 arrangement of these divisions has been to a great 

 extent arbitrary. It used to be supposed that 

 variation in species was restricted by fixed limits, 

 and that when varieties appeared they tended to 

 revert to the parent form. It is now known that 

 variation is a continuous process, and may be 

 extended in any direction under the influence of 

 varying external conditions, so that new species 

 and genera are still appearing. Thus there is only 

 a difference of degree between a variety and a 

 species, between a species and a genus, and between 

 a genus and an order, and the classifying of any 

 plant, or set of plants, must be left to the judgment 

 of botanists. 



It is then agreed, as the most convenient system, 

 to regard as a species a group of individual plants 

 which possess certain well-marked features in 

 common, and which propagate with each other. 

 But sometimes a species is subdivided into varieties, 

 each variety possessing some characteristic of less 

 importance than those which determine the species. 

 There is no central authority recognized by all to 

 settle these matters, consequently there is no 

 absolute agreement. Brassica oleracea, for instance, 

 is the Cabbage. Some botanists make this the 



