X PREFACE. 



a portion of the plants collected during his travels in Arkansas 

 in the year 1819. 



Our acknowledgments are also due to the Botanical Com- 

 mittee of the Academy of Natural Sciences, Philadelphia, 

 who have obligingly afforded us every facility in consulting the 

 large herbarium of that Society, which includes that of the late 

 Mr. Von Schw^einitz, and the chief collections of Mr. Nuttall. 

 To the urbanity of Mr. Vaughan, the Librarian of the Ameri- 

 can Philosophical Society, we are indebted for the opportunity 

 of examining the botanical collections in the custody of that 

 Society, comprising the herbarium of Muhlenberg, and that of 

 the late Professor Benjamin Smith Barton, which appears to 

 have been formed by Pursh, and contains many of his plants. 



To the daughter of the lamented Elliott, we desire to 

 express our thanks for kindly entrusting to our charge a portion 

 of her late father's herbarium ; and also to Prof. Bachman and 

 Prof. GiBBEs of Charleston, South Carolina, who kindly select- 

 ed and transmitted to us the specimens which we desired. 



To Mr. B. D. Greene of Boston, for the loan of a very 

 complete set of the plants collected by the late Mr. Drummond 

 in Texas. 



To our numerous correspondents in different parts of the 

 country, who have from time to time furnished us with valuable 

 collections and observations, our limits will only allow us to 

 offer our acknowledgments in general terms. Their names 

 frequently occur throughout the pages of this work, where we 

 have endeavored faithfully to indicate the sources from which 

 our specimens have been derived, as fully as the plan of the 

 work would permit. But whenever a species has been received 

 from several correspondents, and from different sections of the 

 country, we are obliged, in most cases, to omit the citation of 

 particular locaUties, and to give as nearly as possible its geo- 

 graphical range. Additional specimens of many rare plants 

 described in this volume have also been received since the 

 Orders to which they belong were printed ; and we have only 

 space to notice the more important of these accessions in the 

 Supplement, this volume having already extended much beyond 



