VI PREFACE. 



hence of the* proper mode in which they should be 

 grouped together. It is difficult to determine the "true 

 import of the Linnaean maxim, " let the genus give the 

 character" ; but if it is intended by it that the charac- 

 ters thus established should be so modified as to embrace 

 all new plants, 'or that the genera should not be divid- 

 ed as nature seems to warrant, it is*, in my opinion, quite 

 as much honored " in the breach as in the observ- 

 ance." I * 



In the description of tlie Species, in addition to my 

 own observations, I have freely availed myself of all 

 the sources of information within my reach. The works 

 on American Botany have been constantly consulted ; 

 especially Pursh's Flora, Torrey's Flora and Compen- 

 dium, Elliott's Sketch, Nuttall's Genera, Bigelow's Flo- 

 rula, Muhlenberg's Grasses, and his Catalogue, &tc. 

 In this part of the work, it has been my object to give 

 an accurate and sufficiently detailed description, togeth- 

 er with the habitat and geographical range of each spe- 

 cies, and such popular characters and illustrations as it 

 was thought would be an additional guide to the begin- 

 ner. It may be observed, that I have generally adopt- 

 ed the specific characters of De Candolle, as far as the 

 PJatural Order Composite. With regard to the Gluma- 

 ceae, I have, with few exceptions, adopted the views of 

 Dr. Torrey. Dr. Hooker's valuable Flora Bor. Amer. 

 and- Richardson's Appcndfx to Franklin's Narrative, 

 have afforded me the means of determining the Northern 

 limits of many of our plants. For the Southern limits 

 I have generally depended upon Elliott, and upon the 

 information which 1 have received from my friends, 

 Prof. T. R. Ingalls of Louisiana, and Dr. Isaac Branch 

 of South Carolina; and. for the Western, upon my own 

 observations, and upon those of Mr. Nuttall, and other 

 botanists who have explored the region west of the Mis- 

 sissippi. I should also state, that while this work was 



