THE FOREST TREES. 229 



flat ridges, giving it the name of "rough barlv fir" in some sections of the 

 country. It is sometimes two inches thick, though usually thinner. 

 The tree tolerates shade fairly well. It is not at home in the Flathead 

 valley, though in favorable places it reaches comparatively large dimen- 

 sions. Like so many of the other conifers it does its best on the Pacific 

 coast. It Is confined to low altitudes, seldom reaching above 3,500 feet. 

 The alpine fir (Abies jasiocarpa (Hook) Nutt.) : This tree is also 

 known as the balsam fir. The leaves of the lower branches resemble 

 those of the lowland fir, though in trees growing side by side those of the 

 alpine fir are narrower and lighter green than the leaves of the lowland 

 fir. The cones are much alike also. The seeds have bright violet wings 

 and can thus be easily distinguished from the pale colorless wings of the 

 seeds of the lowland fir. The bark of the lowland fir is grayish or reddish 

 brown, while that of the alpine fir is much lighter. The bark of the 

 former is also much more ridged than that of the latter, which remains 

 more or less smooth until very old age. The alpine fir, as its name im- 

 plies, is a tree of the alpine regions. It does its best, however, in damp 

 canyons, where it is associated with the Engelmann spruce. In the 

 higher altitudes it is a companion of the white-bark pine on the exposed 

 ridges, but is more at home in basins, occupying the places where the 

 snow disappears first. It is found throughout the alpine regions in the 

 western part of the United States, and reaches as far south as northern 

 Arizona. (See frontispiece for characteristic locality for growth. On 

 the extreme right is the tapering top of a beautiful tree.) 



