DEDICATION. 



To all my fellow Botanists in the United States ol 

 North America, and chiefly to those who are endeavor- 

 ing to complete and illustrate our Botany — I dedicate 

 these pages, results of 24 years of observations and re- 

 searches. 



But above all, to my friends, colleagues, or contribu- 

 tors now living, and to the memory of the worthy de- 

 parted, Elliot, Collins, Schweinitz, Pursh, Conrad, Brad- 

 bury ... in grateful remembrance of their worth and 

 kind help. . . . . D. D. D. 



Philadelphia, September, 1836. 



THE AUTHOR. 



