162 TREES OF NORTH AMERICA 



first year, gradually becoming dark gray, and roughened by the greatly enlarged 

 and thickened elevated leaf-scars. Winter-buds resinous, fragrant, ovate, long- 

 pointed, frequently curved above the middle, f ' long and \' broad, with 6 or 7 

 light orange-brown slightly puberulous scales scarious on the margins. Bark l'-2l' 

 thick, ashy gray, deeply divided into broad rounded ridges broken on the surface 

 into thick closely appressed scales. Wood light, dull brown, with thin nearly white 

 sapwood; largely used in Oregon and Washington for the staves of sugar barrels 

 and in the manufacture of woodenware. 



Distribution. In open groves by the banks of streams; southern Alaska, south- 

 ward to western Oregon, along the mountains and islands of western California to the 

 southern slopes of the San Bernardino Mountains, and eastward through British 

 Columbia to the valley of the Columbia River; of its largest size near the level 

 of the sea in all the coast region north of California; southward and beyond the 

 influence of the ocean often not more than 30-40 tall ; sometimes ascending to 

 elevations of 6000 above the sea on the western slope of the Sierra Nevada of 

 central California; the largest of the broad-leaved trees of British Columbia, Wash- 

 ington, and Oregon. 



8. Populus Mexicana, Wesm. Cottonwood. 



Leaves rhombic and long-pointed, especially on young trees, or broadly deltoid 

 and acute or acuminate, broadly or acutely cuneate or truncate or slightly cordate 

 at the base, or often rounded at the apex and much broader than long, usually 

 coarsely and irregularly crenately serrate except at the base and toward the apex, 

 the broad and*rounded leaves finely crenulate-serrate above the middle, as they un- 

 fold dark red, covered below with pale pubescence, puberulous above, ciliate on the 



margins, thin, terete, glandular, with bright red caducous glands, soon becoming 

 glabrous, and at maturity subcoriaceous, bright yellow-green, very lustrous, 2'-3' 

 long and somewhat narrower or much broader than long, with slender yellow mid- 

 ribs and obscure primary veins; their petioles terete, at first puberulous, soon gla- 

 ms, l'-2' long. Flowers: staminate aments dense, cylindrical, !'-!' long; pis- 

 illateaments slender, many-flowered, l'-2' long, 3'-4' long before the fruit ripens; 



