[From the Bullbtin op the Torrby Botanical Club, 43: 343-364. 14 Aug 1916.] 



Phytogeographical notes on the Rocky Mountain region 

 VI. Distribution of tlie subalpine plants 



p. A. Rydberg 



I have already pointed out in a paper entitled "Vegetative 

 Life Zones of the Rocky Mountains," read at the twentieth anni- 

 versary of the New York Botanical Garden, that the Subalpine 

 and Montane Zones of the Rockies are very different from those 

 zones in the eastern part of North America, although the Hudsonian 

 and Canadian Zones extend west to the foot of the Rockies from 

 the headwaters of the Athabasca River northward. Also, I 

 showed that the aspen was the only one among the eco- 

 logically important trees, common to the eastern and central 

 (Rocky Mountain) provinces, that the Subalpine and Mon- 

 tane Zones of the central and western (Pacific) provinces merge 

 in the north, and that many species have emigrated from either 

 of these provinces to the other. These statements were largely 

 based on the most conspicuous element of these zones, namely, the 

 forest trees. Now it is to be shown whether or not these state- 

 ments apply to the secondary species of the forests, to the grass- 

 ands and other herbaceous formations, and to the coppice. 



The subalpine flora may be divided into the following cate- 

 gories: — I. The transcontinental element, many members of which 

 are also found in the Old World; II. Plants common to the Rockie 

 and either of the other provinces; III. The endemic element.- 

 To the first belong the larger proportion of the plants common 

 to the alpine-arctic zone. 



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