XXIV PREFACE. 



tribe in question. But what affords me most satis- 

 faction is, that I am thus enabled to keep entire al- 

 most all his own genera. He had in reality founded 

 them by that penetrating insight into natural genera, 

 for whieh he was so eminent ; but he was always 

 labouring, according to his ideas derived from the 

 umbels, and involucrums as he called the bracteas, to 

 make " the genus give a character/' and this labour 

 was often in vain. Parts that vary in the same 

 individual species, and differ in those most closely 

 related, can obviously never prove a safe foundation 

 for generic distinctions. Yet prepossession often 

 stands in the way of truth. It appears from the 

 letters of Cusson, who devoted all his time to the 

 study of this tribe, that he just began, towards the 

 end of his labours, to think the floral receptacle, 

 meaning principally the bases of the styles, had not 

 been sufficiently attended to ; but he had not reso- 

 lution to begin his task anew. If what I have done 

 should excite the attention of competent judges, I 

 hope succeeding botanists will improve upon this 

 attempt ; for all who have looked at Umbelliferous 

 plants, must be aware of the necessity of their better 

 definition. When studied upon fixed principles, 

 they will be found well worthy of attention, and not 

 less instructive or curious than more gaudy flowers. 



I must now particularly explain what I have had 

 in view in the general plan and execution of the 

 following work. 



The reader is requested to consider that the first 

 object of this English Flora is botanical discrimina- 

 tion ; by which I mean, not only the furnishing 

 English readers with means for the easy and accu- 



