230 TREES OF NORTH AMERICA 



**Leaves often dentate or spinesoent, or sometimes entire. 



- Leaves deciduous in their first autumn or winter, blue-green, convolute in the bud. 



Leaves obovate or oblong, undulate-lobed or entire, pale, and often silvery white 



and pubescent on the lower surface. 37. Q. breviloba (C). 



Leaves oblong, sinuate-dentate, entire, pinnatifid-lobed or spinescent, pubescent 



below. 38. Q. undulata (F, H). 



Leaves oblong, lobed, spinescent or entire, pubescent below. 



39. Q. Douglasii (G). 



-t---Leaves mostly persistent until the appearance of those of the following spring, 

 re volute in the bud (convolute in 45) 

 Leaves blue-green. 



Fruit solitary or in pairs. 



Cup hemispherical or turbinate, inclosing about one third of the acorn, 

 raised on a short peduncle or nearly sessile. 



Leaves oblong-obovate, usually obtuse and rounded at the apex, entire 



or remotely dentate. 40. Q. Engelmanni (G). 



Leaves ovate, oval or obovate, usually cordate, entire or remotely 



spinulose-dentate. 41. Q. oblongifolia (E, H). 



Leaves oblong-lanceolate or broadly obovate, cordate or rounded at 



the base, spinose-dentate, pubescent and conspicuously reticulate- 



venulose on the lower surface. 42. Q. Arizonica (H). 



Cup saucer-shaped, inclosing about one fourth of the acorn, sessile ; leaves 



ovate or ovate-oblong or oval, entire or remotely spinose-dentate. 



43. Q. Toumeyi (H). 



Fruits several on a long and slender peduncle. Leaves broadly obovate, 

 cordate, usually "rounded and obtuse at the apex, repandly spinose-dentate, 

 coarsely reticulate-venulose. 44. Q. reticulata (H). 



Leaves dark green. 



Leaves oblong or obovate, entire, sinuate-toothed or lobed, pubescent and 

 often pale below, convolute in the bud. 45. Q. dumosa (G). 



Leaves oblong, elliptical or obovate, entire or remotely spinose-dentate, 

 pale or silvery white on the lower surface ; anthers hirsute. 



46. Q. Virginiana (C). 



Leaves oblong-lanceolate, entire or repand-serrate, coriaceous ; inner sur- 

 face of the shell of the acorn hoary-tomentose. 47. Q. Emoryi (F, H). 



1. Fruit maturing at the end of the second season (except 22) ; shell of the acorn tomen- 

 tose on the inner surface leaves or their lobes bristle-tipped. BLACK OAKS. 

 * Stamens usually J^-Q abortive ovules basal. 



-t-Leaves deciduous in their first autumn or winter. 

 +-t-Leaves pinnately lobed. 



1. Quercus rubra, L. Red Oak. 



Leaves obovate or oblong, acute or acuminate, abruptly or gradually wedge- 

 shaped or rounded at the broad or narrow base, usually divided about half way to 

 the midribs by wide oblique sinuses rounded at the bottom into 11 or sometimes 

 into 7 or 9 acute oblique ovate lobes tapering from broad Eases and mostly sinuately 

 3-toothed at the apex, with elongated bristle-pointed teeth, or sometimes oblong- 

 obovate, gradually narrowed and wedge-shaped at the base, and sinuately lobed, with 

 broad acute usually entire or slightly dentate lobes, when they unfold pink, covered 

 with soft silky pale pubescence on the upper surface and below with thick white 

 tomentum, soon glabrous, and at maturity thin and firm, dark green, dull and gla- 



