THE SPECIES. 29 



competition between the members of a group results in an advantage 

 to some and the suppression of others, so that they vary greatly in 

 size, and would seem to be of different ages. Examination of the 

 stem, however, will usually show them to be of the same age. 



The botanical characteristics of the species are rigid leaves about 

 2 inches in length, in clusters of five, and rather densely crowded 

 toward the ends of the twigs. The cones are about 3 inches long, 

 purple, with thick heavy scales. The seeds are relatively large, and, 

 owing to the habit of the cones above mentioned, are almost devoid 

 of wings. The squirrels frequently extract the seeds from these 

 cones while they are still on the tree. The bark of the tree is thin, 

 scaly, and light gray. The wood is often much twisted in the grain, 

 and is soft, of even texture, and light colored. The small size and 

 the inferior form of the trunk, and the usual inaccessibility of its 

 habitat render the tree of little commercial value. 



The limber pine. Another species which is characteristic of the 

 higher altitudes is the limber pine (Pinus flexilis), the general range 

 of which is from Alberta to Arizona and southern California. In 

 Montana this tree is confined to the eastern slope of the Continental 

 Divide and to some of the outlying ranges. Ordinarily it reaches a 

 diameter of 2 feet, more or less, and a height of about 50 feet, though 

 in sheltered canyons it sometimes assumes much better form. When 

 it descends among the dry and grassy foothills, it may be stunted 

 and dwarfed. 



Botanically it is similar to the preceding species, and its leaves and 

 twigs are scarcely distinguishable from it. The cones, however, are 

 somewhat longer and narrower, tan colored, and have thinner scales. 

 The cones, when dry, spread apart to liberate the seeds. The wood is 

 light in color, though fine grained, owing to the slowness of its 

 growth. It is of no commercial importance. 



THE LARCHES. 



The larches are deciduous conifers. In the fall the leaves turn 

 yellow, and in the winter the trees are devoid of foliage. Leaves to 

 the number of 10 to 40 are borne in brushlike clusters. On the young- 

 est shoots the leaves are always singly arranged and equally distributed 

 along the branch, but at the close of the first season lateral buds ap- 

 pear here and there in the axils of these single leaves, and these buds 

 give rise in the next season to clusters of leaves. The clusters are 

 thus borne upon short, lateral branches, as in the pine, with this 

 difference that in the larch the number of leaves is indefinite, such 

 lateral branches are fewer in number, and they continue to grow 

 slowly during the period in which they bear leaves. There comes a 

 time, of course, when, owing to the elongation of the branch, they 

 are left in the shade and perish. 



