XIV PREFACE. 



A complete index of the genera and species, and an enumera- 

 tion of all the works which relate to North American Botany, or 

 are cited in this work, will be given with the concluding volume, 

 and likewise, if space permit, some general observations respect- 

 ing the geographical distribution of North American plants. 

 A connected notice of those plants which are important on ac- 

 count of their active or medicinal properties or economical uses, 

 will also be added. 



New-York, June 1st, 1840. 



*** The exclamation point is used after the manner in which it is employed 

 by De Candolle and other modern botanists, to indicate that we have seen an 

 authentic specimen of the author, or from the locahty cited. When the dash is 

 omitted after the character of a species, the description is derived from the author 

 whose name immediately follows : when the dash is inserted, wc are alone respon- 

 sible for the description. The abbreviations of the names and works of authors 

 are mostly those in common use, and will be generally understood : they will, 

 however, be fully explained at the close of the work. 



