BETULACE^ 213 



the base, finely or sometimes coarsely and occasionally doubly serrate, slightly thick- 

 ened and reflexed on the somewhat undulate margins, when they unfold pale green 



and covered with deciduous matted white hairs, at maturity dark green and lustrous 

 on the upper suface, frequently marked, especially on the midribs, with minute glan- 

 dular dots, light yellow-green and slightly puberulous below, 2'-3' long, 1^-2' wide, 

 with stout yellow midribs and primary veins; their petioles slender, yellow, hairy, 

 flattened and grooved on the upper side, ^'-f' long; stipules ovate, acute, scarious, 

 puberulous, about \' long. Flo"wers: staminate aments in slender-stemmed pubescent 

 clusters, usually short-stalked, during the summer dark olive-brown and lustrous, 

 I'-l' long and about y^ thick, beginning to lengthen late in the autumn before the 

 leaves fall, fully grown and 4'-6' long and \' thick in January, with dark orange- 

 brown scales, and deciduous in February before the appearance of the new leaves; 

 calyx yellow, 4-lobed, rathe'r shorter than the 2 or occasionally 3 or rarely single 

 stamen; pistillate aments in short pubescent racemes emerging from the bud in 

 December, their scales broadly ovate and rounded. Fruit: strobiles oblong, ^' j' 

 long, with thin scales slightly thickened and lobed at the apex, fully grown at mid- 

 summer, remaining closed until the trees flower the following year; nut broadly 

 ovate, with a thin acute margin. 



A tree, frequently 70-80 high, with a tall straight trunk 2-3 in diameter, long 

 slender branches pendulous at the ends, forming a wide round-topped open head, 

 and slender branchlets marked by small scattered lenticels, at first light green and 

 coated with pale caducous pubescence, soon becoming dark orange-red and glabrous, 

 and darker during the winter and following summer. Winter-buds nearly ^' long, 

 very slender, dark red, and covered with pale scurfy pubescence. "Wood light, soft, 

 not strong, brittle, close-grained, light brown, with thick lighter colored often nearly 

 white sapwood. 



Distribution. Banks of streams from northern Idaho to the eastern slope of the 

 Cascade Mountains of Washington and southwestern Oregon and southward over the 

 coast ranges and along the western slopes of the Sierra Nevada to the mountains of 

 southern California; the common Alder of the valleys of central California, and the 

 only species at low altitudes in the southern part of the state. 



