Southeastern Washington and Adjacent Idaho. 87 
A. oregana is less abundant. As conditions become more meso- 
phytic in the Larix-Abies community, Usnea dasypoga begins to 
predominate, while in the climax cedar consociation the trees are 
often beautifully draped with the long yellow strands of this 
species. Under such conditions species of Alectoria are not fre- 
quent. 
Other trees which are more or léss important components of 
these forests are the white pine, Pinus monticola, lodgepole pine, 
Pinus murrayana, yew, Taxus brevifolia, and Engelmann spruce, 
Picea engelmanni. 
The white pine, although more abundant and of greater value 
on the bottom lands of streams in northern Idaho than anywhere 
throughout its range, is not an important tree in the area under 
consideration. It occurs only sparingly throughout and where it 
is best developed on the moister slopes, seldom makes up more 
than 5 per cent. of the forest and reaches this abundance in only 
local areas. It appears to require a moister soil than white fir, but 
its seedlings can stand considerable shading. Perhaps the dry- 
ness of the climate combined with the ravages of forest fires 
which may kill it and leave larch and red fir uninjured, combined 
to make it an unsuccessful tree in this region. 
The lodgepole pine, Pinus murrayana, occurs very sparingly 
throughout the western forest frontier of the region. Eastward 
and northward, especially in cut-over and burned-over regions, it ° 
assumes considerable importance, occurring in mixture through- 
out all types of forest, and frequently forming dense even stands 
over considerable areas. Unlike the yellow pine it seldom plays 
the role of pioneering in grass land and since it is distinctly a “ fire 
tree” of a weedy nature, it had best be considered in another 
place. 
Taxus brevifolia is very rare in this region, occurring only oc- 
casionally along ravines and then taking on only a scrubby form. 
Its role in the forests of the region is insignificant. 
Engelmann spruce, so characteristic of high mountain slopes 
elsewhere, while never found in great abundance, is rather a fre- 
quent forest tree at the highest altitudes, especially in wet ravines 
and about the edges of alder swamps. It does best in soils where 
87 
