Illustrations of Conifers. 33 



PINUS ALBICAULIS (Engelmann). 



Trans. St. Louis Acad. II. 209 (1868). 



Teitch's Man. Conif. ed. 2, p. 810 (1900). 



Trees of Great Britain and Ireland, Vol. V. p. 1048 (1910). 



A tree attaining in western North America a maximum height of 

 100 feet, but usually only 15 to 20 feet high with a stem 12 to 

 18 inches in diameter ; becoming a low shrub at high elevations. 

 Bark of young stems white or pale grey, smooth and thin ; on 

 old trunks scaling off in small plates. 



Young branchlets reddish-brown, with a scattered minute stiff 

 pubescence. Leaves in fives, similar to those of P. flexilis, persist- 

 ing five to eight years, stout, rigid, slightly incurved, densely 

 crowded on the branchlets, 2 to 3 inches long, entire in margin, 

 marked on each surface with white lines of stomata. 



Cones sub-terminal, sessile, spreading, ovoid, 1 to 3 inches 

 long, dark purple when growing, light brown when mature : scales 

 much thickened, very brittle at the base, f inch long, $ inch 

 broad, many undeveloped and infertile. Seed J to \ inch long, 

 ovoid ; wing rudimentary or absent. 



Pimis alhicaulis is allied to P. flexilis, but has different cones ; 

 and in a barren state may be distinguished by its pubescent branchy 

 lets. It is more alpine in its distribution, forming the timber line 

 on many mountain ranges in North-West America at altitudes 

 ranging from 5,000 to 12,000 feet. 



The cones of Pinns albicaulis resemble those of P. Cembra 

 in never opening. The seeds are distributed by squirrels and 

 mountain crows which break the scales and carry off the seed. 



The species was discovered on the mountains rising above 

 the valley of the lower Fraser River near Port Hope in 1851, by 

 John Jeffrey who sent seeds from Mount Shasta, California, but 

 none of these appear to have survived. There are young plants in 

 cultivation at Kew. 



The illustration shows a native specimen collected by Mr. 

 F. R. S. Balfour. 



