Vol. 43 No.7 
BULLETIN 
OF THE 
TORREY BOTANICAL CLUB 
ns ee ee 
JULY, 1916 
Phytogeographical notes on the Rocky Mountain region 
VI, Distribution of the 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- 
lands 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 Rockies 
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. 
[The BuLLETIN for June (43: 283-342. pl. 16-20) was issued June 29, 1916.] 
343. 
