BETULACE.E 



225 



brown and lustrous, -f'-l' long and about T V 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, rather 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, f'-|' long, with thin scales 

 slightly thickened and lobed at apex, fully grown at midsummer, remaining closed until 

 the trees flower the following year; nut broadly ovoid, with a thin 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. Bark on old trunks 1' thick, dark brown, irregularly 

 divided into flat often connected ridges broken into oblong plates covered with small closely 

 appressed scales. 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 southeastern Oregon, and southward from the valley of the 

 Willamette River, Oregon (near Salem, Marion County, J. C. Nelson) over the coast 

 ranges and along the western slopes of the Sierra Nevada to the mountains of southern Cali- 

 fornia (San Bernardino, San Jacinto, and Cuyamaca Ranges) ; the common Alder of the 

 valleys of central California, occasionally ascending on the southern Sierra Nevada to alti- 

 tudes of 8000, and the only species at low altitudes in the southern part of the state. 



5. Alnus oblongifolia Torr. Alder. 

 Alnus acuminata Sarg., not H. B. K. 



Leaves oblong- lanceolate, acute; or rarely obovate and rounded at apex, gradually nar- 

 rowed and cuneate at base, sharply and usually doubly serrate, more or less thickly covered, 

 especially early in the season, with black glands, dark yellow-green and glabrous or slightly 



Fig. 213 



puberulous above, pale and glabrous or puberulous below, especially along the slender 

 yellow midrib and veins, with small tufts of rusty hairs in the axils of the primary veins, 

 2'-3' long, about l' wide; petioles slender, grooved, pubescent, ' long; stipules ovate- 



