Rydberg: Phytogeographical notes 95 



Tofieldia palustris. This is found in Great Britain, Scandinavia, 

 northern Russia, the Alps, the Pyrenees and the Ural. Notwith- 

 standing the fact that it is less distinctly arctic-alpine than for 

 instance Lloydia serotina and has been collected in the lowland as far 

 south as Two Harbors, Minnesota, it has not been collected in 

 the Rockies south of northern Montana. 



Asiatic Arctic-alpine or Glacial Plants 



Dasystephana glanca is a distinctly Asiatic glacial plant, but 

 also found in western North America, coming down south as far 

 as Montana. 



American Arctic-alpine or Glacial Plants 



A large number of the alpine plants of the Rockies are strictly 

 American glacial plants, i. e., found both in the mountains and 

 the arctic regions of this continent but not in the mountains of 

 the Old World. 



I. In many cases they are there represented by closely related 

 plants. In such cases the history of the plant might be the follow- 

 ing: 



(a) That the parent plant had a circumpolar distribution 

 before or during the earlier part of the glacial period and the two 

 related species developed independently from it; 



(b) That the Old World plant existed on both continents during 

 the glacial epoch and became modified after isolation on this 

 side; or 



(c) That the American plant existed and became modified 

 abroad. 



Here I give a list of such plants and the nearest relatives in the 

 Old World. 



American European Asiatic 



*Calamagrostis purpurascens C. anmdinacea 



Salix glaucops "\S. glauca 



Salix chlorophylla S. phyllicijolia 



*Alsinopsis propinqua A. verna 



* Those starred are also subalpine and subarctic. 



t Salix glauca and Rhodiola rosea are also found in northeastern America, but 

 not in the Rockies. 



