MANUAL OF BOTANY. 



BOOK III. 



SYSTEMATIC BOTANY, 

 OB TEE CLASSIFICATION OF PLANTS. 



CHAPTEE I. 

 general peinciples of classification. 



Section 1. — Species, Genera, Okdbbs, and Classes. 



Our attention has been hitherto directed to the examination of 

 the structure and shapes of the various organs and parts of 

 plants. In doing so, we cannot but have noticed the almost 

 infinite varieties of forms which have thus been presented to 

 us, and also at the same time observed that, notwithstanding 

 such variations, there are some striking resemblances ui the 

 structure of the members of certain plants, by which a close 

 relationship is thus clearly indicated between them. It is the 

 object of Systematic Botany to take notice of such relation- 

 ships, and thus to bring plants together which are allied in 

 their forms and structure, and to separate those that are unlike ; 

 and in this way to take a comprehensive view of the whole 

 Vegetable Kingdom. In its extended sense, Systematic Botany 

 has for its object the naming, describing, and arranging of plants 

 in such a manner that we may readily ascertain their names, 

 and at the same time get an insight into their affinities and 

 general properties. 



At the present time there are at least 120,000 species of 



VOL. II. B 



