TREES OF NORTH AMERICA 



Bark of the trunk rarely more than ' thick, close and firm, light orange-brown and covered 

 by small thin loosely appressed scales. Wood light, soft, not strong, close, straight-grained 

 and easily worked, not durable, light yellow or nearly white, with thin lighter colored sap- 

 wood ; occasionally manufactured 

 into lumber; also used for railway- 

 tics, mine-timbers, and for fuel. 



Distribution. Common on the 

 Yukon hills in the valley of the 

 Yukon River: on the interior pla- 

 teau of northern British Columbia 

 and eastward to the eastern foot- 

 hills of the Rocky Mountains, 

 covering with dense forests great 

 areas in the basin of the Columbia 

 River; forming forests on both 

 slopes of the Rocky Mountains of 

 Montana ; on the Yellowstone pla- 

 teau at elevations of 7000-8000; 

 Fig, 27 common on the mountains of Wy- 



oming, and extending southward 



to southern Colorado; the most abundant coniferous tree of the northern Rocky Moun- 

 tain region; common on the ranges of eastern Washington and Oregon, on the mountains 

 of northern California, and southward along the Sierra Nevada, where it attains its 

 greatest size and beauty in alpine forests at elevations between 8000 and 9500; in 

 southern California the principal tree at elevations between 7000 and 10,000 on the high 

 peaks of the San Bernardino and San Jacinto Mountains; on the upper slopes of the 

 San Pedro Martir Mountains, Lower California. 



21. Pinus Banksiana Lamb. Gray Pine. Jack Pine. 



Pinus divaricata Du Mont de Cours. 



Leaves in remote clusters, stout, flat or slightly concave on the inner face, at first light 

 yellow-green, soon becoming dark green, f'-lj' long, gradually and irregularly deciduous 

 in their second or third year. Flowers: male in short crowded clusters, yellow; female 



Fig. 23 



clustered, dark purple, often with 2 clusters produced on the same shoot. Fruit oblong- 

 conic, acute, oblique at base, sessile, usually erect and strongly incurved, H'-2' long, dull 

 purple or green when fully grown, becoming light yellow and lustrous, with thin stiff 



