212 



TREES OF NORTH AMERICA 



nate aments 3 or 4 in number in slender-stemmed racemes, nearly sessile or raised 

 on stout peduncles often ' long, during the winter light purple, f'-l' long and 

 ^' thick, becoming l^'-2' long; calyx-lobes rounded, shorter than the 4 stamens; 

 pistillate aments naked during the winter, dark red-brown, nearly ^' long, with 

 acute apiculate loosely imbricated scales, only slightly enlarged when the flowers 

 open. Fruit : strobiles ovate-oblong, \'-% long, their scales much thickened, trun- 

 cate and 3-lobed at the apex; nut nearly circular to slightly obovate, surrounded 

 by a thin membranaceous border. 



A tree, occasionally 30 tall, with a trunk 6'-8' in diameter, small spreading 

 slightly pendulous branches forming a narrow round-topped head, and slender branch- 

 lets marked at first by a few large orange-colored lenticels and coated with fine pale 

 or rusty caducous pubescence, becoming light brown or ashy gray more or less 



deeply flushed with red in their first winter and ultimately paler; more often shrubby, 

 with several spreading stems, and at the north and at high elevations frequently only 

 4-5 tall. Winter-buds '-' long, bright red, and ptiberulous. Bark rarely more 

 than \' thick, bright red-brown, and broken on the surface into small closely ap- 

 pressed scales. 



Distribution. Banks of streams and mountain canons from Francis Lake in 

 latitude 61 north, to the valley of the lower Fraser River, British Columbia, east- 

 ward along the Saskatchewan to Prince Albert, and southward through the Rocky 

 Mountains to northern New Mexico; on the Sierra Nevada of southern California, 

 and in Lower California; the common Alder of mountain streams in the northern 

 interior region of the continent; very abundant on the eastern slopes of the Cascade 

 Mountains, and on the southern California sierra, forming great thickets at 6000- 

 7000 above the sea along the head-waters of the rivers of southern California flowing 

 to the Pacific Ocean; the common Alder of eastern Washington and Oregon, and of 

 Idaho and Montana; very abundant and of its largest size in Colorado and northern 

 New Mexico. 



4. Alnus rhombifolia, Nutt. Alder. 



Leaves ovate or oval or sometimes nearly orbicular, rounded or acute at the apex, 

 especially on vigorous shoots, gradually or abruptly narrowed and wedge-shaped at 



