PREFACE. 



from books like the author's Natural System of Botany. 

 His examination in practical Botany becomes alarming to 

 him because he is necessarily ill-prepared to meet it ; and 

 when passed, all but the theory of the science is too apt to 

 quit his memory, from the want of definite points upon 

 which his attention can be permanently fixed. 



But there is another reason which has induced the 

 author to take up the investigation of medical plants. 

 All persons at all conversant with Materia Medica, are 

 aware how conflicting are the statements found in books, 

 and made in conversation, respecting the sources from 

 which medicinal plants, often of the commonest kind, are 

 derived. 



For instance, one writer says that Cubebs are obtained 

 from Sierra Leone, where Piper Cubeba does not grow : 

 another refers the origin of this pepper, in Bourbon, to 

 Piper caudatum, which is a Brazilian, not an African 

 species ; a third asserts that Cubebs come from Java, and 

 are the fruit of Piper caninum, not of P. Cubeba. Cas- 

 carilla bark is assigned by one writer to Croton Cascarilla, 

 by another to C. pseudo-china, and by a third to C. Eleu- 

 teria. Rhubarb has been said by different writers to be the 

 root of Rheum palmatum, R. undulatum, and R. Emodi ; 

 and in all these cases the assertion has been made with 

 equal confidence. According to one author Sarsaparilla is 

 the root of Smilax officinalis ; to another, of Smilax me- 

 dica ; to a third, of Smilax aspera ; to others, of a species 

 called S. Sarsaparilla. I have even heard it stated with 

 great confidence, that of the few kinds of vegetable drugs 

 admitted into the last edition of the Pharmacopoeia of the 

 College of Physicians, twelve are referred to plants which 

 certainly do not produce them ; and that twenty-six others 

 have been assigned to their sources with more or less in- 

 accuracy. As the greater part of these differences of 

 opinion can be more readily settled by Botanical investi- 

 gation than by Pharmaceutical evidence, the author trusts 

 that it will not be thought presumptuous in him to have 

 made the attempt, although he is not a medical man. 



vi 



