210 TREES OF NORTH AMERICA 



grooved, abruptly enlarged at the base, |'-f long; stipules oblong to spatulate, 

 rounded and apiculate at the apex, puberulous, about \' long. Flowers: staminate 

 aments in pairs in the axils of the upper leaves sometimes reduced to small bracts, 

 and single in the axil of the leaf next below it, sessile, during the winter about % 

 long and \' thick, with dark red-brown shining puberulous apiculate scales, becoming 

 when the flowers open from spring to midsummer 4' or 5' long, with a puberulous 

 light red rachis and ovate acute apiculate 3-flowered scales; calyx-lobes rounded, 

 shorter than the 4 stamens; pistillate aments in elongated panicles, inclosed during 

 winter in buds formed the previous summer in the axils of the leaves of short lateral 

 branchlets, long-pedunculate, \' long, ' thick. Fruit: strobiles on slender peduncles 

 in elongated sometimes leafy panicles 4'-6' long, oblong, ' |' long, about ^' thick, 

 their truncate scales thickened at the apex; nut oval, about as wide as its wings. 



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, becom- 

 ing light gray. Winter-buds acuminate, dark purple, covered especially toward 

 the apex with close fine pubescence, about ^' long; often a shrub only a few feet tall 

 spreading into broad thickets. 



Distribution. Northwest coast from the borders of the Arctic Circle to Oregon; 

 common in the valley of the Yukon and eastward through British Columbia to Al- 

 berta, and through Washington and Oregon to the western slopes of the Rocky Moun- 

 tains; 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, or 

 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 Co- 

 lumbia and the United States generally smaller, growing usually only at elevations of 

 more than 3000 above the sea, and often forming thickets on the banks of streams 

 and lakes. 



2. Flowers opening in winter or early spring 'before the unfolding of the leaves ; pistil- 

 late aments usually naked during the winter. 



2. Alnus Oregona, Nutt. Alder. 



Leaves ovate to elliptical, acute, abruptly or gradually narrowed and wedge- 

 shaped at the 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 pubescence, 3'-5' long, l|'-3' broad, or on vigorous 

 branches sometimes 8'-10' long, with broad midribs and primary veins green on the 

 upper side and orange-colored on the lower, the primary veins running obliquely 

 t<> the points of the lobes and connected by conspicuous slightly reticulate cross vein- 

 lets; their petioles orange-colored, nearly terete, slightly grooved, '-f' long; stipules 

 ovate, acute, pale green flushed with red, tomentose, \'-\' long. Flowers: stami- 

 nate aments in red-stemmed clusters 2'-3' long, during the winter \\' long, \' 

 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 lobes rather shorter than the 4 stamens; pistillate aments in short 



