SALICACE.E 



129 



about \' long, 3 or rarely 2-valved; seeds oblong-obovoid, rounded at the apex, light 

 brown, about T V m length. 



A tree, usually about 40 high, with a trunk 12'-18' in diameter, stout spreading and 

 ascending branches forming a compact round-topped head, and slender terete or slightly 

 4-angled pale yellow-brown branchlets roughened for two or three years by the elevated 

 oval horizontal leaf-scars. Winter-buds acuminate, resinous, about ' long, with 6 or 7 

 light chestnut-brown lustrous scales. Bark on young stems and large branches smooth, 

 nearly white, becoming on old trunks pale gray-brown, about \' thick, deeply divided 

 into broad flat ridges. 



Fig. 122 



Distribution. Banks of streams in the arid eastern foothill region of the Rocky Moun- 

 tains; Assiniboia to the Black Hills of South Dakota, northwestern Nebraska, eastern 

 Wyoming, southern Colorado, and southwestern New Mexico (Fort Bayard, Grant 

 County); in Colorado crossing the Continental Divide to southeastern Utah; passing into 

 the var. Rehderi Sarg. differing in the larger leaves on longer petioles, and in the pubes- 

 cent branchlets and winter-buds. Borders of streams southeastern New Mexico. 



Sometimes planted as a shade-tree in the streets of cities in the Rocky Mountain region. 



X Populus Andrewsii Sarg. intermediate in its character between P. acuminata and P. 

 'Sargentii and believed to be a natural hybrid of these species has been found growing 

 naturally near Boulder and Walsenburg, Colorado, and as a street tree in Montrose, 

 Colorado. 



8. Populus Fremontii S. Wats. Cottonwood. 



Leaves deltoid or reniform, generally contracted into broad short entire points, or rarely 

 rounded or emarginate at apex, truncate, slightly cordate or abruptly cuneate at the entire 

 base, coarsely and irregularly serrate, with few or many incurved gland-tipped teeth, 

 coated like the petioles when they unfold with short spreading caducous pubescence, at 

 maturity thick and firm, glabrous bright green and lustrous, 2'-2^' long, 2|'-3' wide, with a 

 thin yellow midrib and 4 or 5 pairs of slender veins; petioles flattened, yellow, l|'-3' long. 

 Flowers: staminate aments densely flowered, l|'-2' long, nearly \* thick, with slender 

 glabrous stems, the pistillate sparsely flowered, with stout glabrous or puberulous stems, 

 becoming before the fruit ripens 4' or 5' long; scales light brown, thin and scarious, dilated 

 and irregularly cut at apex into filiform lobes; disk of the staminate flower broad, oblique, 

 slightly thickened on the entire re volute margin; stamens 60 or more, with large dark red 



