INTRODUCTION. 
For a long time the botanists of this country have felt the want of a 
general work on the grasses of the United States. For several years 
I have had such a work in contemplation, and now venture to present 
to the public the first part of the same. It has been prepared in con- 
nection with numerous official duties, and is not in all respects as com- 
plete as I could wish it to be. There are many difficulties of identifica- 
tion and synonymy, particularly respecting the grasses of the Pacific 
coast and of our southwestern boundary. A number of these have been 
named from descriptions of some of the old botanical explorers without 
access to the original types. Botanists in general know the difficulty 
of identification from the commonly brief descriptions of writers, and 
they will not be surprised if many changes or modifications will be 
needed whenever it is possible to examine the original specimens. 
I wish to return thanks to Prof. Edw. Hackel, of St. Poelten, Aus- 
tria, for the privilege of making such use as I found convenient of the 
analytic tables in his excellent work on “ The ‘Lrue Grasses,” as trans- 
lated by Scribner and Southworth. 
A complete synopsis of the tribes and genera will appear with the 
second part of this work. 
I hope to follow this part within a few months with the remaining 
portion of the work, and in the meantime solicit from botanists notes, 
criticisms, or information such as they may deem worthy of attention. 
Gro. VASEY, 
WaASHINGLON, November 20, 1891. 
Vv 
