218 BULLETIN UNIVERSITY OF MONTANA 



cinnamon red in color. The thick bark enables the tree to resist fires. 

 This is, of course, of great advantage to the tree, for since fires have 

 become more numerous, those trees that are easily destroyed by them 

 are first excluded from the forest. The western larch is one of the last 

 to suffer permanent injury from fires. Those seed-bearing trees that 

 remain after fires will re-stock the bum with a new generation of trees. 

 The western larch requires light in its seedling stages; hence it can re- 

 produce itself only in open places. These may be caused by fire, by 

 death of old trees, or by any accident that will remove the trees of the 

 mature forest. The western larch is then exceedingly intolerant of shade. 



In the Flathead valley the western larch does best in soil not too 

 moist nor too dry. This tree is said to reach ils greatest development 

 In the basin of the upper Columbia river. In the United States it is 

 most at home in the Flathead valley, and in northern Idaho. Here it 

 may reach the height of 200 feet, with a trunk of five to six feet in 

 diameter, and occasionally is even larger. 



Mountain larch (Larix Lyallii Par.). The mountain larch is reported 

 to be present in a few places at high altitudes in the mountains of north- 

 western Montana. It does not, however, form a conspicuous element in 

 the forest. It is distinguished from the western larch by the fact that 

 the leaves are nearly as thick as broad. In the latter species the leaves 

 are somewhat wider than thick. The branchlets of the mountain larch 

 are hairy, as compared with those of its lowland relative. The height of 

 the tree is seldom over fifty feet. 



The genus Pinus (pine) is easily distinguished from the other conifers 

 by the fact that the needle like leaves are in groups of two, three, or five. 

 The first leaves that are produced on the leading shoots are scale-like. 

 In the axil of each scale-like leaf a bud may appear which develops soon 

 into a branch, so short and inconspicuous as to be hardly recognizable. 

 On each of these short branches, two, three, or five leaves appear, the 

 number being usually definite in each species. 



There are five species of pine in Montana. They may be divided into 

 two groups, viz., those that have two or three leaves in a cluster or 

 fascicle and those that have five leaves in a cluster. The latter, known 

 as white pines, are represented by three species in Montana, and are 

 seldom found growing together. In the Flathead valley the silver pine 

 is found only in the lower altitudes. Near the timber line is the white- 

 bark pine. (Plate XLVII.) This is usually on the west side of the con- 

 tinental divide. On the east side of the divide at high altitudes, the 

 limber pine occurs. Aside from their mode of distribution, these three 

 pines may usually be distinguished from one another by the length of their 

 cones. The cones (Fig. 8) of the silver pine are from five to eleven 

 inches in length, usually not less than eight; those of the limber pine 

 from three to ten inches, most frequently under eight; and those of the 

 white-bark pine from one and a half to three inches. The tips of the 

 cones of the last named species are curved inward. The length of the 

 leaves is variable, but usually in the silver pine they are long, in the 

 white-bark pine and the timber pine they are short; the first of the last 

 two named having the shorter leaves. 



