548 Part IV. Chapter 3. 
Lake. In places, it occurs only in scattered groves and crosses the mountains 
in the Peace River country and enters that between Lesser Slave Lake and 
the Athabasca River. — The Russell Mountains at the forks of the Mac- 
Millan River, a tributary of the Pelly River, which empties into the Yukon 
at 137° W. Long., 63° N. Lat., are spurs of the northern Rocky Mountains. 
In the canyons and along the small streams of these mountains, the white 
spruce, Picea alba (= P. canadensis) is abundant extending up the mountain 
sides on northerly exposures to about 2,000 feet (610 m) and on southerly to 
2,500 to 3,000 feet (915 m). At higher elevation, it is outnumbered by Adses 
subalpına (= A. lasiocarpa). The deciduous trees are Populus balsamifera, 
P. tremuloides, abundant along the banks of Russell Creek and on the benches 
associated with Deiula alaskana, while on hot exposed benches, Pinus Mur- 
rayana is abundant ’).. — Pinus ponderosa reaches latitude 5ı° 30” in the 
valleys near the upper portion of the Columbia River and extends to the Sel- 
kirk and Gold ranges. It forms open groves in the valleys, where it is some- 
times exclusive, and stretches up the slopes of the Mountains and upon the 
plateaux tö an elevation of 3,000 feet where it is replaced by Pseudotsuga 
Douglasii and Pinus Murrayana (= P. contorta var. Murrayana). This pine 
densely covers great areas on the eastern slopes of the Rocky Mountains 
northward, while in the southern part of British Columbia, it is found on 
those parts of the plateau and hills which rise above 3,500 feet, but it never 
reaches timber-line. Zarir occidentalis is found in the Rocky Mountains 
and in the valleys of the Gold and Selkirk ranges, its limit there being 
determined by that of abundant rainfall. Larir Lyallii grows at an ele- 
vation above 7,000 feet near Lake Louise, B. C. and elsewhere, and is 
the distinctive tree of this phytogeographic district. — Populus 
fremuloides abounds in all parts of the district characterizing some of the 
fertile lands. In the southern dry portions, it usually grows on areas denuded 
by fire and on the dry mountain slopes while 2. balsamifera is a characte- 
ristic tree of the river valleys. 
The valley of the Kootanay River is characterized by open woods con- = 
sisting of Pinus ponderosa, Psendotsuga, Larix occidentalis with Purshia tri- 
dentata and Balsamorhiza sagittata, but near the upper Columbia Lake a 
denser forest prevails of which the black or scrub pine, Pinus Murrayana and 
Engelmann’s spruce, Picea Engelmanni, form a large part, and these trees 
form the forest growth of the Rocky Mountains about the great bend of the e 
Columbia River. — Northward to the headwaters of the Fraser River the e 
same trees constitute the forest growth, viz: Pinus, Picea, Pseudotsuga Dow 
glasıi (which there reaches the northern limit) Populus tremuloides, P. tricho- 
carpa, Betula papyrifera, Funiperus virginiana with such shrubs as Amelanchier _ 
alnıfolia, Sorbus sambucifolia. The Rocky Mountain country north of this 
ı) OsG00D, WILFRED H.: Biological Investigation in Alaska and Yukon Territory. U. 5. 
Bureau of Biological Survey. North American Fauna No, 30 (1909): 70. 
Aue 
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