DEDICATION. 
To all my fellow Botanists in the United States of 
North America, ‘and chiefly to those who are endeavor- 
ing to complete and illustrate our Botany — 1 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. 
