OP GENERA. SrS 



hairy seeds ; but the saiTiie circumstance %vill 

 not justify us in separating a fe spe.ios from 

 Convolimlus, which are attached to that jie- 

 nus by stronger ties of another kind. 



Some genera are obvious and indubitable 

 both in habit and character, as QuerciiSy 

 Ilosa, Euphorbia^ Begonia, Eiot, Dot. t. 101, 

 and Sarracenia, t. 53 ; others are obvious, 

 but their character extremely difficult to de- 

 fine, as Valeriana. The greatest difficulty 

 lies in distinguishing genera that belong to 

 guch very natural orders 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 ex- 

 cellent generic differences, as that to which 

 Hoaa, Rubas, Fragaria, &;c., belong ; and 

 even in the Papilionaceous plants with ten 

 distinct stamens, a tribe hitherto iudired in- 

 extricable, a regular examination on scientific 

 principles has led to the discovery of very na^ 

 tural well defined genera. See Annals of 

 Botany, t;. 1. 501. I have in a preceding 

 chapter hinted that the umbelliferous plants 



