152 



PHYTOGEAPHY. 



A. On Generic Characters. 

 230. 



The generic character (character genericus) is the expres- 

 sion of the peculiar and invariable marks by which a genus 

 of plants is distinguished from all others. This character 

 may be of three kinds. 



1. It may contain a complete enumeration of all and each 

 of the marks which are found in the whole plant. It is then 

 called a Natural Character. Such a character must always be 

 very circumstantial, and it is so much the more difficult to 

 give it correctly, that in the organs of nourishment non-essen- 

 tial things may easily be confounded with such as are es- 

 sential. 



2. The Artificial Character (character artificialis). This 

 contains only the marks of the organs of fructification, or, 

 where these are not distinct, the marks of those parts which 

 are subservient to propagation. 



3. The Diagnostic Character (character factitius, diag- 

 nosis). This consists in the selection of such marks only as 

 serve to distinguish one genus from another. This last cha- 

 racter facilitates, indeed, the acquisition of the knowledge of 

 plants, and renders it more sure ; but when a genus is represent- 

 ed by itself, this character cannot possibly be sufficient. When, 

 for instance, we merely state respecting Bromus, that the 

 awn springs from the ridge of the valve, we can distinguish 

 Bromus from Festuca by this means, but the whole charac- 

 ter of the former demands something more, and we must, for 

 this purpose, pay attention both to the inflorescence, and to 

 the number of flowers on the ear. 



231. 



Every generic character must state shortly and distinctly the 

 common marks which belong invariably to all species of the 

 same genus. No generic character, therefore, can be formed, 

 till we have compared together all the species. Inattention to 

 this rule is the reason why very many of the older characters 



