352 Rydberg: Phytogeographical notes 



Most of these extend to the western slopes of the Rockies in 

 British Columbia or northern Montana, but Tsiiga Mertensiana, 

 Osniorrhiza Leihergii and Synthyris reniformis are restricted to the 

 western slopes of the Bitter Root Mountains in Idaho. 



4. Western immigrants from the Sierra Nevada and the 

 Cascades, which have invaded the Northern 



Rockies 



There are a number of species which are common to the Pacific 

 mountains and the Rockies, but have a wider distribution in the 

 former than in the latter. Their home may therefore be regarded 

 as being on the west coast, and they may be regarded as immigrants 

 into the Rocky Mountains. Those of the following list are com- 

 mon to the Sierra Nevada and the Cascades, and their range 

 extends into the Northern Rockies. Some of these are found in 

 the Bitter Root or the Selkirk Mountains only, and are without 

 doubt immigrants. Others extend into the main Rockies of 

 Alberta and Montana and even as far south as northern Wyoming. 

 Whether these are immigrants or endemics to the Rockies is more 

 doubtful. A very few reach the Wasatch Mountains in northern 

 Utah. There are no immigrants from the Sierras to the southern 

 Rockies. It is true that there are a few subalpine endemics com- 

 mon to the Sierra Nevada and the Southern Rockies, but these 

 are plants characteristic of the mountains of the Great Basin, and 

 limited to the eastern slope of the Sierra Nevada and the western 

 slope of the Rockies. 



Trees 



Pinus alhicaulis Salix sitchensis 



Shrubs 



^Salix cascadensis Cassiope Mertensiana 



Ribes laxiflorum Vaccinium occidentale 



Ribes glandidosiim Linnaea longiflora 



Herbs 



Stipa oregonensis Carex spectabilis 



Poa Cicsickii XerophyUiim tetiax 



