2. SOME PECULIAR CASES OF PLANT DISTRIBUTION 

 IN THE SELKIRK MOUNTAINS, BRITISH COLUMBIA 



Frederic K. Butters 



All botanists who have travelled across the Canadian Rocky 

 mountains and the Selkirk range have noted the great differences 

 in the vegetation of the two regions. Indeed these differences are 

 so manifest that they appeal strongly to the average intelligent 

 tourist who crosses these ranges along the main line of the Canadian 

 Pacific railway, stopping perhaps at Banff and Laggan or Field 

 in the Rockies and at Glacier in the Selkirks. 



The first difference that appeals to one is the much greater 

 luxuriance of the Selkirk vegetation. This is of course easily ex- 

 plained by the greater rainfall and humidity of the Selkirk range, 

 and, in fact, there are some parts of the eastern Selkirks where 

 the vegetation is but little more luxuriant than in the wetter valleys 

 of the western Rockies. There is, however, a qualitative difference 

 also in the vegetation of the two ranges. The commonest and most 

 characteristic plants about Glacier, for example, are not the same as 

 the characteristic plants of similar altitudes in the Rockies. In 

 general the flora of the Selkirk range is remarkably similar to the 

 flora of regions of like elevation near the Pacific coast, e. g.,. the 

 subalpine and alpine parts of Vancouver Island, while the flora of 

 the main range of the Rockies is equally similar to that found farther 

 south in Montana, and even in Wyoming and Colorado. The obvious 

 explanation is, of course, the historical one, that the Selkirk plants 

 have migrated in from the west, and the Rocky mountain plants 

 from the southeast, though there is at present little continuity be- 

 tween the Selkirk vegetation and the similar vegetation of the 

 coastal region. 



The transition between the Rocky mountain and the Selkirk 

 regions is abrupt. The Columbia valley, lying between the two 



