INTRODUCTION. 



The grasses whicli are known to groM' on tLe Pacific slope of the United States, 

 iuchuling Alaska, miruber not I'ar from i-'OO si)ecies. These are nearly all specifically 

 distinct fi oni the grasses growing east of the Mississippi Elver, 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 fiora. 



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

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

 interior Rockies. 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 wc 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 desciiptions of the species are almost wholly the work of Mr. L. H. Dewey, 

 Assistant Botanist. 



Geo. Vasey. 



