FAGACE.E 277 



slender brauchlets coated at first with dense hoary tomentum, light reddish brown 

 or ashy gray and pubescent or tonaentose during their first winter, ultimately gla- 

 brous and dark brown or gray; usually a shrub, forming small thickets by vigorous 

 stolons, with stout more or less contorted stems 2-8 tall. "Winter-buds oval, 

 about ^' long, with few thiii light red-brown scales often ciliate on the margins. 

 Bark thin, scaly, pale gray slightly tinged with reddish brown. 



Distribution. Dry rocky mountain ridges; cliffs above the canon of the Arkan- 

 sas River, and the eastern foothills of the Rocky Mountains of Colorado, to western 

 Texas, and through New Mexico and Arizona to southern Utah and Nevada, and 

 southward into northern Mexico; in central Arizona south of the Colorado plateau 

 covering low mountain ranges with vast thickets; less common in southern Utah 

 and Nevada; arborescent only in the canons of the mountain ranges of southeastern 

 Arizona. 



39. Quercus Douglasii, Hook. & Arn. Blue Oak. Mountain White Oak. 



Leaves oblong, acute or rounded at the apex, gradually narrowed and wedge- 

 shaped to broad and rounded or subcordate at the base, divided by deep or shallow, 

 wide or narrow sinuses acute or rounded at the bottom into 4 or 5 broad or narrow 



acute or rounded often mucronate lobes, 2'-5' long, I'-lf broad, or oval, oblong or 

 obovate, rounded or acute at the apex, equally or unequally wedge-shaped or 

 rounded at the base, regularly or irregularly sinuate-toothed, with rounded acute 

 rigid spinescent teeth, or denticulate toward the apex, l'-2' long, \'-l' wide, when 

 they unfold covered by soft pale pubescence, at maturity thin, firm and rather rigid, 

 pale blue, with scattered stellate hairs above, often yellow-green and covered by 

 short pubescence below, with hirsute or puberulous prominent midribs and more 

 or less conspicuous reticulate veinlets; their petioles stout, tomentose, \'^' long. 

 Flowers: staminate in hairy aments l'-2' long; calyx yellow-green, coated on the 

 outer surface with pale hairs, deeply divided into broad acute laciniately cut seg- 

 ments; pistillate in short few-flowered spikes coated like the involucral scales with 

 hoary tomentum. Fruit sessile or short-stalked, solitary or in pairs; acorn broadly 

 oval, sometimes ventricose, with a narrow base, gradually narrowed and acute at the 

 a pex, !'-!' long, ^'-1' broad, or often ovate and acute, green and lustrous, turning 



