202 CllAUACrERS 



which are attached to that genus by stronger ties of an- 

 other kind. ^ 

 Some genera are obvious and indubitable both in 1 

 habit and character, as Quercus, Rosa, Euphorbia, Be- fl 

 gonia, Exot. Bot. t, 101, and Sarracema^ t, 5^ \ others 

 are obvious, but their character extremely difficult to 

 define, as Valeriana. The greatest difficulty lies in dis- 

 tinguishing genera that belong to such very natural or- 

 ders as the Grasses and Umbelliferous plants ; and the 

 ablest botanists differ about the best guides in these two 

 particular cases. Yet other orders, equally natural, 

 sometimes afford very excellent generic differences, as 

 that to which Rosa, Rubiis, Fragaria, &c., belong ; and 

 even in the Papilionaceous plants with ten distinct sta- 

 mens, a tribe hitherto judged inextricable, a regular ex- 

 amination on scientific principles has led to the discovery 

 of very natural well defined genera. See Annals of 

 Botany, v. 1. 501. I have in a preceding chapter 

 hinted that the umbelliferous plants seem to me very 

 capable of being well discriminated by their seeds, and 

 other botanists have held the same opinion. 



But though I feel convinced, as far as my experience 

 «"oes, that genera are really founded in nature, I am far 

 from asserting that Linnseus, or any other writer, has 

 succeeded in fixing all their just limits. This deep and 

 r important branch of natural science requires the union 

 of various talents. Many persons who can perceive a 

 l^enus cannot define it ; nor do acuteness of perception, 

 ; soUdity of judgment, and perspicui^ of expression, 

 always meet in the same person. Those who excel in 

 this department are named by Linnceus, Phil. Bot. sect. 



