THE MONTANE ZONE 157 



8,000 in the Bitter Roots, and in the Absaroka Range above 7,000. 

 In the Little Belt TMountains it is found only on the highest points 

 above 8,000 feet. Its endurance of high temperatures is only for 

 brief periods at the altitudes which it usually inhabits. 



In its local distribution it shuns the wet soils and is found 

 usually on rocky ridges which have better drainage and aeration. 

 Here it grows to its best size and so partial is it to the rock, 

 either fixed or in the form of fragments or boulders, that no 

 case can be recalled where trees of more than seedling size were 

 found in the wet soil. It is a common accompaniment of the 

 topography which is exhibited in crumbling outcrops of rock, 

 alternating with depressed areas composed of finer materials, 

 but seldom occupied by trees except at times the spruce. Sloping 

 mountain sides are also favorite situations for this species. Uni- 

 form stands have been found by the writer where the ground 

 cover consisted mainly of a thick carpet, ankle-deep, of small 

 heaths mainly Cassiopr Mertevfriana. Its relation to tempera- 

 ture and to soil conditions are thus the important factors which 

 control its local distribution. Owing to its very thin bark it is 

 easily destroyed by slight fires and areas are known where 

 whole stands are reduced to dry and bleaching trunks with 

 little evidence of reoccupation by the same species, in marked 

 contrast to the progress of the lodgepole pine. At its best the 

 whitebark pine is not vigorous in propagation, and stands once 

 destroyed are very slowly restored. Nevertheless this tree is 

 readily found, as a rule in all the higher altitudes of the State 

 and ranks third among the native species as to the extent, and 

 uniformity of its distribution in this region. 



Closely related to this species is Piniis flexilis, limber pine, 

 which in this region is found east of the main divide. Cases re- 

 ported of the finding of Pimis flexilis on the west slope in Mon- 

 tana seem not to be clearly substantiated. The two species are 

 similar in requirements and in altitudinal range. The twigs and 

 leaves are practically indistinguishable but the cones differ in 

 form, color, thickness of the scales and manner of opening. The 

 tree occupies high and exposed situations, and responds in the 

 manner of its growth and its form much as other trees in similar 

 situations, severely distorted and repressed. 



The positive qualities of this species are found mainly in 



