PART II. 



SYSTEMATIC BOTANY, TAXONOMY, OE THE 

 CLASSIFICATION OF PLANTS. 



CHAPTER I. 

 SYSTEMS OF CLASSIFICATION. 



703. THIS department of Botany may be considered as a combina- 

 tion of all the observations made on the structure and physiology of 

 plants, with the view of forming a scientific arrangement. It can only, 

 therefore, be prosecuted successfully after the student has acquired a 

 complete knowledge of Organography. In every branch of science, 

 arrangement is necessary in order that the facts may be rendered avail- 

 able, and this is more especially the case when a knowledge of species 

 is to be acquired. When it is considered that there are upwards of 

 100,000 known species of plants, it is obvious that there must be a 

 definite nomenclature and classification, were it only to facilitate refer- 

 ence and communication. Taxonomy has sometimes been pursued 

 with no higher aim than that of knowing the names of plants. When 

 prosecuted in such a spirit, it does not lead to an enlarged and philoso- 

 phical view of the vegetable kingdom. In all truly scientific systems, 

 regard is paid, not merely to the determination of the names of the 

 species, but to their relations and affinities, so as to give some concep- 

 tion of the order which has been followed in the plan of creation. 



704. In Classificatory Sciences, the arrangements are founded upon 

 an idea of likeness an idea, however, which is applied in a more exact 

 and rigorous manner than in its common and popular employment. 

 The resemblances of the objects must rest, not on vague generalities, but 

 upon an accurate scientific basis. In order that an arrangement may be 

 constructed on philosophical principles, and that it may be rendered 

 useful for the purpose of science, the following steps are required: 

 1. A Technical (rt-^vi^, artificial or conventional) language, rigorously 



