PREFACE. IX 



As the discriminating characters of the 

 Linnaean system are founded in nature 

 and fact, and depend upon parts essential 

 to every species of plant when in perfec- 

 tion ; and as the application of them to 

 practice is, above all other systems, easy 

 and intelligible ; I conceive nothing more 

 useful can be done than to perfect, upon 

 its own principles, any parts of this sy- 

 stem that experience may show to have 

 been originally defective. This is all I 

 presume to do. Speculative alterations 

 "in an artificial system are endless, and 

 scarcely answer any more useful purpose 

 than changing the order of letters in an 

 alphabet. The philosophy of botanical 

 arrangement, or the study of the natural 

 affinities of plants, is quite another mat- 

 ter. But it would be as idle, while we 

 pursue this last-mentioned subject, so 

 deep and so intricate that its most able 

 cultivators are only learners, to lay aside 



