214 



TREES OF NORTH AMERICA 



5. Alnus oblongifolia, Torr. Alder. 



(Alnus acuminata, Silva, N. Am. ix. 79.) 



Leaves oblong-lanceolate, acute or rarely obovate and rounded at the apex, grad- 

 ually narrowed and wedge-shaped at the base, sharply and usually doubly serrate, 

 more or less thickly covered, especially early in the season, with black glands, dark 

 yellow-green and glabrous or slightly puberulous above, pale and glabrous or puber- 

 ulous below, especially along the slender yellow midribs and veins, with small tufts 

 of rusty hairs i the axils of the primary veins, 2'-3' long, about 1^' wide; their 

 petioles slender, grooved, pubescent, f long; stipules ovate-lanceolate, brown and 

 scarious, about ^ long. Flowers: staminate aments in short stout-stemmed racemes, 

 during the winter light yellow, '-' long and about T y thick, becoming when the 

 flowers open at the end of February before the appearance of the leaves 2'-2' 



long, with ovate pointed dark orange-brown scales; calyx 4-lobed; stamens 3 or occa- 

 sionally 2, with pale red anthers soon becoming light yellow; pistillate aments naked 

 during the winter, ^' to nearly ^' long, with light brown ovate rounded scales; 

 stigmas bright red. Fruit : strobiles \'-V long, with thin scales slightly thickened 

 and nearly truncate at the apex; nut broadly ovate, with a narrow membranaceous 

 border. 



A tree, in the United States rarely more than 20-30 high, with a trunk some- 

 times 8' in diameter, long slender spreading branches forming an open round-topped 

 head, and slender branchlets slightly puberulous when they first appear, light orange- 

 red and lustrous during their first winter, and marked by small conspicuous pale 

 lenticels, becoming in their second year dark red-brown or gray tinged with red and 

 much roughened by the elevated leaf-scars. Winter-buds acute, bright red, lus- 

 trous, glabrous, \' long. Bark thin, smooth, light brown tinged with red. 



Distribution. Banks of streams in canons of the mountains of southern New 

 Mexico and Arizona at elevations of 4000 -6000 above the sea; and on the moun- 

 tains of northern Mexico. 



