No.l.i GEAY AND HOOKER ON THE EOCKY MOUNTAIN FLORA. 



The analysis of this alpine flora need not detain us. The botanist sees 

 at a glance that it is the arctic flora, or rather x^rolongations of it, ex- 

 tended southward along the mountains of sufficient elevation, with cer- 

 tain admixtures of types pertaining to the vegetation of the regions. 



The peculiar elements in the scanty alpine flora of the Eastern United 

 States are only five species, viz : One grass of arctic affinity, Calamagrostis 

 PicJceringii; an orchid, Hahenaria ohtusata; a Geum, which has its princi- 

 pal home on the subalpine summits of the AUeghanies farther south, 

 and is nearly represented by a sjDecies on the ISTorthern Pacific coast; 

 and two species of J^ahalus, which will be allowed to be altered states of 

 species peculiar to Xorth America and nearly peculiar to the Atlantic 

 side. 



The Pacific ali)ine flora has a higher proportional number of non-arctic 

 species, as mu«t needs be, considering its long stretch through so many 

 parallels of latitude ; but the number pertaining to non-arctic genera is 

 small. They are — 



Calandrinia pygmcea. Gymopterus, 2 species. 



Eriogynki pectinata. Aplopappus Lyallii. 



Ivcsia, 2 si^ecies. Ur logon urn, 3 species. 



All of them are of genera peculiar to America. Besides these, only 

 38 species are peculiar to America, and between a third and a quarter 



