200 FAGACEAE 



Scales of the cups decidedly corky-thickened on the back. 



Leaves decidedly crisp, sinuately lobed; lobes distinctly spinulose-tipped. 



12. Q. pungens. 

 Leaves flat, sinuate-dentate or entire; teeth mucronate, or sometimes slightly 



spinulose-tipped. 

 Acorns 6-7 mm. thick; cup shallow, enclosing about one-third of the acorn; 



leaves usually sinuate-dentate. 13. Q. undulata. 



Acorns about 1 cm. thick or more; cup deeper, enclosing about half of the 



acorn. 

 Leaves usually entire, except those of the young shoots. 



14. Q. grisea. 



Leaves lobed, with few (5-7) lobes. 15. Q. panciloba. 



Scales of the cups thin, only slightly thickened on the back; leaves glabrate and 



shining above in age. 16. Q. Wilcoxii. 



Cup more or less turbinate; acorns elongated-ovoid. 17. Q. turbinella. 



1. Q. macrocarpa Michx. A tree 10^50 m. high; leaf -blades obovate, 

 irregularly round-lobed, usually pinnately divided below the middle, bright green 

 and shining above, grayish tomentulose beneath, 1-2 dm. long; fruit short- 

 peduncled; cup hemispheric, 1-2.5 cm. in diameter; scales floccose, thick, ovate 

 or lanceolate, the upper subulate-tipped; acorns 1.5-2.5 cm. long, ovoid. BUR 

 OAK. MOSSY-CUP OAK. Rich soil: N.S. Pa. Tex. (? Wyo.) S.D. Sask. 

 Plain Submont. My-Je. 



2. Q. submollis Rydb. Shrub or small tree; leaf -blades obovate in outline, 

 deeply pinnatifid at least two-thirds to the midrib, with oblong segments, rounded 

 at the apex, glabrous and shining above, densely and softly pubescent beneath; 

 fruit sessile; cup depressed-hemispheric, about 15 mm. broad; acorn obtuse, 12- 

 15 mm. long. Mountain sides: Ariz. s Utah -N.M. Son. -Submont. 



3. Q. utahensis (A. DC.) Rydb. A small tree, sometimes 10 m. high, or 

 more often only a shrub; leaf -blades 6-10 cm. long, broadly obovate, deeply 

 divided, often to near the midrib; lobes oblong, rounded at the apex, the larger 

 usually again lobed or undulate; upper surface sparingly stellate, in age glabrate, 

 dark green and glossy; fruit subsessile; cup hemispheric, 12-15 mm. in diameter; 

 scales pubescent, ovate; acorn 15-20 mm. long, light brown. UTAH OAK. Hills 

 and mountains: Utah Colo. N.M. 'Ariz. Submont. -Mont. My. 



4. Q. Vreelandii Rydb. A small shrub 1-1.5 m. high; young branches 

 brown, puberulent; leaf -blades 5-7 cm. long, obovate, deeply lobed about two- 

 thirds to the midrib, thick, firm; lobes rounded, the larger often lobed or sinuate; 

 upper surface soon glabrate, bright green and rather dull; lower surface slightly 

 paler; fruit subsessile; scales ovate and very corky on the back; acorn about 15 

 mm. long, light brown. Hills and bench-lands: Colo. N.M. Submont. My. 



5. Q. leptophylla Rydb. A tree 10-15 m. high; young twigs brownish or 

 purplish, slightly pubescent at first; leaf -blades broadly obovate, very thin, 

 pinnately 5-9-lobed scarcely more than half way to the midrib; lobes rounded; 

 upper surface soon glabrate, bright green, but not very glossy; lower surface 

 paler; fruit subsessile; cup hemispheric, about 15 mm. wide; scales ovate-lanceo- 

 late, obtuse, only slightly thickened on the back. Along mountain streams: 

 Colo. N.M. Submont. Mont. My. 



6. Q. Gunnisonii (Torr.) Rydb. A low shrub 1-3 m. high, forming 

 chapparels; leaf-blades with rounded lobes, usually directed forward, very thick, 

 pale and bluish green above, soon glabrate, scarcely paler beneath; fruit sub- 

 sessile; cup rather deep, 12-15 mm. in diameter, hemispheric; scales ovate, corky- 

 thickened on the back; acorns barrel-shaped, obtuse. Dry hillsides and table- 

 lands: Colo. N.M. Ariz. Utah. Submont. My. 



7. Q. Gambellii Nutt. A shrub 3-5 m. high; young twigs light brown and 

 puberulent; leaf-blades broadly obovate in outline, thinner than in the preced- 

 ing; upper surface glabrate, green, lower surface only slightly paler, lobes rounded; 

 fruit subsessile; cup hemispheric or somewhat turbinate; acorn ovoid, acute or 

 obtuse, about 15 mm. long. Q. nitescens Rydb. Hills and table-lands: Wyo. 

 N.M. Utah. Submont. Mont. My-Je. 



8. Q. novomexicana (A. DC.) Rydb. A shrub 3-5 m. high; young branches 

 light brown, or grayish, sparingly puberulent or glabrous; leaf-blades obovate in 

 outline, deeply divided about three-fourths the distance to the midrib, very 



