394 A HANDBOOK OF CONIFERS 



attacks of the fungus Trametes pini, which causes the disease 

 known as " red rot " in that country. 



Gamble, J. S., A Manual of Indian Timbers, p. 704 (1921) ; Elwea and Henry, 

 loc. cit. V, p. 1011 (1910) ; Troup, R. S., The Silviculture of Indian Trees, iii, 1015, 

 (1921). 



Pinus flexilis, James. (Fig. 89.) 

 Limber Pine. 



Pinus reflexa, Engelmann ; P. strobiformis, Sudworth (not Engelmann) . 

 Rocky Mountain White Pine ; White Pine. 



A tree 20-50 or occasionally 80 ft. high, with a short trunk 3-7 

 or sometimes 12 ft. in girth, usually producing regular whorls of 

 short, flexible branches on young trees, and long, slender, drooping 

 branches, often 16-18 ft. long, on mature trees, the branches 

 drooping at a sharp angle with the trunk. ^ Bark of old trees dark 

 brown, 1^ in. thick, fissured into scaly ridges. On young trees the 

 bark is thin and smooth. Young shoots without down, or covered 

 with minute broT\Tiish hairs. Winter buds ovoid, sharply 

 pointed, | in. long. Leaves in fives, persisting about 5-6 years, 

 densely crowded on the ends of the branchlets, pointing for- 

 wards, rigid, curved or shghtly twisted, 2-3 in. long, margin 

 entire or rarely with distinct teeth on the margins, apex sharp- 

 pointed, 3-4 lines of stomata on each surface, resin-canals 

 marginal. Canes sub-terminal, erect when young, spreading 

 when mature, almost stalkless, 3-5 in. long, buff or orange-buff 

 in colour ; scales tliick, opening and spreading horizontally when 

 mature, 1 in. long, f in, wide, obovate, with the upper margin 

 thickened and reflexed. Seed shed as soon as ripe, ovoid, reddish 

 brown, mottled, ^\ in. long, wing rudimentary. 



The species is distinguished from all other five-leaved pines, 

 except P. pumila and P. albicaulis, by its entire or almost entire 

 leaves. P. pumila differs in its dwarf habit and intensely downy 

 shoots, and P. albicaulis has shorter indehiscent cones. In 

 foUage P. flexilis and the latter are hardly distinguishable. 



P. flexilis is an alpine species widely distributed on the eastern 

 slope of the Rocky Mountains from Alberta to Texas. It also 

 occurs in the mountains of N. Arizona, Utah, Nevada, and S.E. 

 California, growing on arid and rocky slopes at 5,000-11,000 ft. 

 elevation. It was discovered in Colorado in 1820 by Dr. Edward 

 James and was introduced by Jeffrey in 1851. P. reflexa of 

 Engelmann is sometimes regarded as a synonym and sometimes 

 as a variety of P. flexilis ; it has been seen in a wild state only 

 in Mexico and has not, apparently, been introduced elsewhere. 

 The cone-scales are much reflexed, and it is intermediary in 

 character between this species and P. Ayacahuite. 



^ Sudworth, Pine Trees of the Rocky Mountain Region, BuU. 460, U.S. Dept. of 

 Agric. p. 7 (1917). 



