216 BOTANICAL GAZETTE [MARCH 
The altitude of the Mission Range within the limits of the plot 
is nowhere more than 1372™ above the level of the surrounding 
country. The core of the mountains is composed of a dolomite 
shale, which outcrops in many places. Especially is the rock near 
the surface on the steep northwest fault face and where the soil has 
been removed by the action of glaciers (fig. 16). South of the river 
the forest on the western slope has been partially destroyed by fire 
(figs. 16 and 17), but enough of the original stand remains to give 
a clue to the conditions of the whole slope. A discussion of the burned 
area will be taken up in another connection. 
Wherever the rock outcrops there is little or no vegetation (jig. 
16), due to the fact that there is no soil; the pioneer plants on the 
rocks here, as elsewhere, are the lichens. The crustaceous lichens 
appear where there is absolutely no disintegrated rock; sometimes 
associated with these are the foliaceous forms, but these are more 
common where a little soil has accumulated; with these are found 
mosses adapted to the dry conditions. After more soil has accumu 
lated, conditions are favorable for plants that require more moisture; 
among these are the fruitcose lichens, Cladonia rangijerina sylvatica 
being a good example. Associated with these lichens are Selaginella 
densa, Sedum Douglasii, Heuchera parvijolia, the last being usually 
found rooted in cracks. These plants prepare the way by their decay 
for the higher forms that can get a foothold as soon as sufficient soil 
is present. The inorganic material made by the disintegration of 
the rocks is blown or washed in from the surrounding region and 
reinforces the organic accretion. In the meantime the rock crevices 
have been filling up with soil, thus furnishing favorable places ae 
shrubs like Prunus demissa, Symphoricar pos sp., Amelanchier alm 
folia, and Juniperus sibirica; and Campanula rotundifolia, Arc 
siaphylos Uva-ursi, and grasses are early pioneers in these places. 
If the outcrop is near a large body of water like Flathead Lake, 
Juniperus scopulorum is one of the first trees. This tree is found 
distributed around the shores of the lake and along water courses 
in the prairie region in the valley at the foot of the lake, and with ™ 
are found Douglas spruce and bull pine. These of course g4!? 1g 
foothold by sending their roots into the rock crevices and may play 
an important réle in the weathering processes by prying the ate 
