INTRODUCTION. 



The grasses which are known to grow on the Pacific slope of the United States, 

 including Alaska, number not far from 200 species. These are nearly all specifically 

 distinct fi om the grasses growing east of the Mississippi River, and also mainly distinct 

 from the grasses of the plains and of the desert, except in that part of California 

 which partakes of the desert flora. 



A considerable number of the grasses of the mountain regions of California, 

 Oregon, and Washington reappear in the mountains of Idaho, Montana, and the 

 interior Eockies. The interior of California is a dry region, verging in the extreme 

 south into the desert country, and is deficient in grasses, especially of those species 

 which form a continuous turf. In this volume we have figured and described mainly 

 those grasses which are most conspicuous in size and apparent utility. Nearly all are 

 here illustrated for the first time. 



The descriptions of the species are almost wholly the work of Mr. L. H. Dewey, 

 Assistant Botanist. 



Geo. Vasey. 



