94 Rydberg: Phytogeographical notes 



mountains farther south, as the Pyrenees, the Caucasus, the 

 Himalayas, and, in America, in the San Francisco Mountains, 

 Arizona. Like most bulbiferous plants, it does not readily propa- 

 gate by seeds, but when these are formed, they may easily be 

 distributed by the wind on account of their flatness. 



Juncoides spicatum has about the same distribution except that 

 it is not found in the Himalayan region. The seeds of this species 

 must have been carried by birds as they are too heavy to be carried 

 by wind. 



Poa alpina extends south to the Sierra Nevada (Spain), the 

 Appennines, and the Himalayas, and Trisetum subspicatum and 

 Phleum alpinum extend in America south through the mountains 

 of Mexico, Central and South America. As these grasses also are 

 subalpine, their seeds have probably been distributed by animals. 



The following two species are common to the arctic regions of 

 both hemispheres, to the Rockies, and to the Asiatic mountains, 

 but not found in the Alps: Draba glacialis and Anemone parviflora. 



Saxifraga cernua and Campanula uniflora are circumpolar 

 glacial plants, but do not reach the Alps. They are found in 

 America as far south as Colorado and Utah. Either these plants 

 are of American origin and have extended their range over northern 

 Europe, or else they have perished in the Alps. 



The same may be said about Micranthes hieracifolia, although 

 it does not reach the southern Rockies. 



Aster alpinus is a glacial plant found both in the Alps and the 

 Altai, rare in the Rockies and lacking altogether in the Scandinavian 

 mountains. 



Some of the circumpolar glacial plants, although they are found 

 on this continent, are found neither in the southern Rockies nor 

 in Sierra Nevada, although they are found in both the Alps and 

 the Altai. Such are: 



Cerastium alpinum Chondrosea Aizoon 



Erigeron alpinum Micranthes nivalis 



The first two are, however, represented by related endemic 

 species. 



A few of these circumpolar plants are found in the Alps, but 

 neither in the Altai nor in the southern Rockies, as for instance 



