Southeastern Washington and Adjacent Idaho. 89 
Galium sp. Viola glabella 
Streptopus majus Viola orbiculata 
Tiarella unifoliata Vagnera amplexicaulis 
Trillium ovatum 
The high humus content and consequent great water holding 
capacity of the soil is probably due in part to the lack of forest 
fires. or it is easy to see how the more moist areas in the deep 
ravines would be less subject to burning than the drier slopes 
with their proportionally greater amount of undershrubs. The 
forest floor supports the best developed fungus flora of the region. 
This includes species previously enumerated. However, even 
here the fungus flora is relatively scanty. 
Because of the shade the trees are often pruned high, while the 
branches are draped with long strands of Usnea. Often at higher 
altitudes Picea engelmanni accompanies the cedar down the moist 
ravines but never assumes very great importance. 
The greater mesophytism and tolerance of the white fir as con- 
trasted with that of the tamarack and Douglas fir are shown by the 
presence of the former in the mixed cedar-white fir forest. It is 
the last of these trees to give way to the cedar, certain communi- 
ties showing gigantic relict white firs while all of the saplings are 
those of the cedar. Proceeding up the slope from a cedar com- 
munity the white firs become dominant as the cedars become 
smaller and less frequent on the drier soil, then a zone of white 
fir and tamarack’is passed, while further up in this mixture 
Douglas fir becomes more abundant. Of course, the illustration 
is rather overdrawn for the accidents of windfalls, and especially 
fires, may often greatly alter these conditions. 
The formation as a living developing entity has reached its 
maturity in the cedar consociation. Because of the low light 
intensity the establishment of the seedlings of the other forest 
trees of the region in the cedar community is impossible. Hence, 
the adult stage will go on indefinitely repeating itself generation 
after generation, unless disturbed by some outside factor as a 
forest fire or the hand of man. 
Having traced the normal development of the forest through the 
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