8 



TREES OF NORTH AMERICA 



Texas, and westward on mountain ranges at elevations of 5000 to 12,000 to Montana, 



and southeastern California, reaching the western slopes of the Sierra Nevada at the 



head of King's River; usually scattered singly or in small groves; forming open 



forests on the eastern foothills of the Rocky Mountains of Montana and on the ranges 



of central Nevada; attaining its largest size on those of northern New Mexico and 



Arizona. 



6. Pinus albicaulis, Engelm. White Piiie. 



Leaves stout, rigid, slightly incurved, dark green, marked by 1-3 rows of dorsal 

 stomata, clustered at the ends of the branches, l^'-2^' long, persistent for five to 

 eight years. Flow^ers opening in July, scarlet. Fruit ripening in August, oval or 

 subglobose, horizontal, sessile, dark purple, l^'-3' long, with scales thickened, acute, 

 often armed with stout pointed umbos, remaining closed at maturity; seeds acute, 

 subcylindrical or flattened on one side, Y~k' ^^"S' *^l'ick, with a thick dark chestnut- 

 brown hard shell produced into a narrow border, and wings about ^ broad. 



A tree, usually 20-30 or rarely 60 high, generally with a short trunk 2-4 in 



diameter, stout very 

 flexible branches, finallv 

 often standing nearly 

 erect and forming an 

 open very irregular 

 broad head, and stout 

 dark red-brown or or- 

 ange-colored branchlets 

 puberulous for two years 

 or sometimes glabrous; 

 at high elevations often 

 a low shrub, with wide- 

 spreading nearly pros- 

 trate stems. Bark thin, 

 f~|(^ 5 except near the base of 



old trunks and broken 

 by narrow fissures into thin narrow brown or creamy white plate-like scales. 

 Wood light, soft, close-grained, brittle, light brown. The large sweet seeds are 

 gathered and eaten by Indians. 



Distribution. Alpine slopes and exposed ridges between 5000 and 12,000 eleva- 

 tion, forming the timber-line on many mountain ranges from latitude 53 north in 

 the Rocky Mountains and from the valley of the Iltasyouco River southward through 

 British Columbia, along the Rocky Mountains to the Yellowstone plateau, and on 

 the mountains of eastern Washington and Oregon, the Cascade Range, on Mt. 

 Shasta and along the Sierra Nevada to the San Bernardino Mountains of southern 

 California. 



* Cones short-stalked, subcylindrical, dark purple, their scales armed with slender 

 prickles wings longer than the seeds ; leaves in crowded clusters. 



7. Plnus Balfouriana, A. Murr. Foxtail Pine. 



Leaves stout, rigid, dark green and lustrous on the back, pale and marked on the 

 ventral faces by numerous rows of stomata, I'-l^' longj persistent for ten or twelve 

 years. Flo"wers: staminate dark orange-red ; pistillate dark purple. Fruit 3^'-5' 



