
408 THE SYLVA OF MONTANA. 
Western PocvE-niocn (Betula occidentalis). This birch 
forms a shrubby tree, from Sun river through the Rocky 
Mountains to the Ceur d’Alene river, where it becomes of 
large size, sometimes two feet in diameter and sixty feet in 
height, of handsome appearance, and with a laminated bark 
of which the Indians make canoes. The color of the bark 
is of a pale coppery yellow, dark on the branches, and the 
leaf is always quite small. It is common at Fort Colville, 
where I took it for B. papyrifera, when leafless, in 1853, 
and the dwarfed form, growing along streams of the Great 
Plain to the Cascade Mountains, is the B. resinosa of my 
report. I saw it at Fort Walla Walla, but not at Fort 
Dalles. 
GREEN ALDER (Alnus viridis? or new species (perhaps 
rubra of Bengard Veg. Sitch.). This alder has a range sim- 
ilar to that of the western birch, and attains a similar size 
‘toward the west. Its bark is less white and its leaves finer 
toothed than those of A. Oregona near the coast, which I 
first saw at Fort Dalles. : 
Wittows (Salix). The willows were only to be had in 
leaf, and if determinable, will probably prove to be S. Fend- 
leriana, Hookeriana, and longifolia, but I cannot give at- 
counts of their respective distribution, as these trees need 
long acquaintance to distinguish them by the leaves only. 
Baxsow-ndavikb Portat (Populus angustifolia). This 
peculiarly western poplar does not extend east of the 
of the Rocky Mountains at Forts Benton and Laramie. , It 
varies much in the leaf, even on the same tree, some being 
four inches wide; and though I believe it to be the most 
common species in the mountains, I was often in doubt 
whether this or P. balsamifera was the most so, as I could 
not always distinguish between them at a little distance. 
sam Portar (P. balsamifera). This seems to be the 
prevailing species of "Cotton Wood" along the Missouri 
: above Fort Union, and across the Rocky Mountains, and 
— sos uncommon to the west coast. The tree seems 





