202 BOTANICAL GAZETTE [MARCH 
of the Mission Mountains in moist situations. In the swampy soils 
silver pine has a shallow root system and is easily blown over by 
winds, many large trees being observed lying prostrate with nearly 
the entire root system exposed. Where the soil has sufficient moisture, 
this tree can germinate in the open with no shade whatever, but it 
can pass the seedling stage in rather shaded conditions. The only 
two trees that have a shade too dense for it are the giant arborvitae 
and the western hemlock. While it can exist in the shade around 
the drier edges of the mesophytic forest, it fails utterly to maintain 
a stand in the mature growth of these areas, and except in extremely 
favored places the silver pine cannot be considered a successful tree 
for the region under consideration. It succumbs easily to fires, 
many instances being noted where fires had swept through the forests 
destroying the silver pine, while such trees as western larch and 
Douglas spruce were only slightly damaged. 
The distribution of lowland fir is very much like that of silver 
pine, both reaching their climax growth in about the same situations. 
Where the water level is rather far from the surface it is more suc- 
cessful than silver pine in the low altitudes; but its altitudinal range 
is less than that of the latter. It is able to develop in open places, 
in soil so dry that silver pine is excluded. Where the moisture was 
sufficient it was not an uncommon thing to find stands of small (3 
to 5™ high) trees so dense that absolutely all vegetation was lacking 
beneath them. It is more tolerant of the shade than is silver pine, and 
because it can grow in drier soils it extends as undergrowth into the 
borders of the meso-xerophytic regions, where silver pine is seldom 
if ever found. Like silver pine and Engelmann spruce, the range 
of this tree is extended because of the protection of the forest canopy; 
but this is not the region of its best development. The largest tree 
seen were less than a meter in diameter and not more than 38" 7 
height. SaRcEnr reports that it attains its best development along 
the Pacific coast in Washington, Oregon, and northern California, 
where it is frequently 75-90™ in height. 
By far the most successful tree in Flathead valley is wester? larch. 
It is a tree that closely resembles its eastern relative (Larix lari na) 
in general appearance, although its habits are decidedly different 
(fig. 11). As already shown, it is one of the first trees to gain a foot- 
