TREES OF NORTH AMERICA 



A tree, sometimes 40 high, with a trunk 7'-8' in diameter, short small nearly horizontal 

 branches forming a narrow crown, and slender slightly zigzag branchlets puberulous and 

 very glandular when they first appear, bright orange-brown and lustrous and marked by 

 numerous large pale lenticels during their first season, much roughened during their second 

 year by the elevated crowded leaf-scars, becoming light gray. Winter-buds acuminate, 

 dark purple, covered especially toward the apex with close fine pubescence, about \' long. 

 Bark thin bluish gray, with bright red inner bark; often a shrub only a few feet tall spread- 

 ing into broad thickets. 



Distribution. Northwest coast from the borders of the Arctic Circle to the high moun- 

 tains of northern California; common in the valley of the Yukon and eastward through 

 British Columbia to Alberta, and through Washington and Oregon to the western slopes 

 of the Rocky Mountains in Montana; at the north with dwarf Willows, forming great 

 thickets; in southeastern Alaska often a tall tree on rich moist bottom-lands near the 

 mouths of mountain streams, and at the upper limits of tree growth a low shrub; very 

 abundant in the valley of the Yukon on the wet banks of streams and often arborescent in 

 habit; in British Columbia and the United States generally smaller and a shrub, growing 

 usually only at altitudes of more than 3000 above the sea, and often forming thickets 

 on the banks of streams and lakes. 



2. Alnus rubra Bong. Alder. 

 Alnus oregona Nutt. 



Leaves ovate to elliptic, acute, abruptly or gradually narrowed and cuneate at base, 

 crenately lobed, dentate with minute gland-tipped teeth, and slightly revolute on the 

 margins, covered when they unfold with pale tomentum, at maturity thick dark green and 

 glabrous or pilose with scattered white hairs above, clothed below with short rusty pubes- 



Fig. 210 



cence, 3'-5' long, lf-3' wide, or on vigorous branchlets sometimes 8'-10' long, with a 

 broad midrib and primary veins green on the upper side and orange-colored on the lower, 

 the primary veins running obliquely to the points of the lobes and connected by con- 

 spicuous slightly reticulate cross veinlets; petioles orange-colored, nearly terete, slightly 

 grooved, I'-f in length; stipules ovate, acute, pale green flushed with red, tomentose, I'-J' 

 long. Flowers: staminate aments in red-stemmed clusters, during the winter lj' long, 5' 

 thick, with dark red-brown lustrous closely appressed scales, becoming 4'-6' long and 

 thick, with ovate acute orange-colored glabrous scales; calyx yellow, with ovate rounded 



