20 
ested area. This type is composed in varied proportions of white pine, 
white fir, larch and Douglas fir. 
The white pine type varies considerably in composition north of the 
Clark Fork and, again, south of it. In the north, Tsuga heterophylla 
is abundant and associated with it are numerous abundant species com- 
monly reckoned as inhabitants of the Cascade or Canadian floras. 
These do not appear south of the Clark Fork, or if so, not abundantly. 
Such plants are Oplopanax horridum, characteristic of small shaded 
streams; Vaccinium ovalifolium, locally abundant on the floor of ma- 
ture woods; Rubus spectabilis and R. pedatus, the latter abundant on 
the mature forest floor of the upper Priest River; Stenanthium occi- 
dentale, frequent in moist meadows; Habenaria orbiculata, and Coral- 
lorhiza trifida in deep woods; Drosera rotundifolia, D. longifolia and 
Oxycoccus palustris in sphagnum bogs under Betula pumila var. glanduli- 
fera; Dryas octopetela, Phylledoce glanduliflora and Cassiope Merten- 
siana on highest peaks and ridges; Rhododendron albiflorum, an important 
constituent of subalpine brush; Leptarrhena pyrolifolia, Tellima gran- 
diflora, Mitella trifida, Comandra livida, Lilium columbianum, Ribes 
acerifolium and Pentstemon albertinus. Other genera such as Pyrola, 
Lycopodium and Mitella, while found elsewhere less extensively, are 
represented in the north by several species each of which is frequent 
in occurrence. The converse is also true: many species which are fre- 
quent south of the Clark Fork do not occur north of it, or but spar- 
ingly. 
