u 



SILVA OF NORTH AMEPdCA. cupulifer^ 



Obovate or oblong-obovate, wedge-shapeil or rounded at the broad or 

 narrow base, tomentose or pubescent and often silvery white on the 



lower surface 15. Q- MiCHAUXii 



Blue-green. 



Obovate or oblong, undulate, lobed or entire, i)ale and often silvery white 



and pubescent on the lower surface 16. Q- breviloba 



Oblong, sinuate-dentate, entire, pinnatifid-lobed or spinescent, pubescent 



on the lower surface 17. Q. undulata. 



Oblong, lobed, spinescent or entire, pubescent on the lower surface . . . 18. Q. DOUGLASII. 

 Leaves mostly persistent until the appearance of those of the following spring. 

 Blue-green. 



Oblong or obovate, usually obtuse and rounded at the apex, entire or 



remo 



tely dentate 19. Q. EngeliviANNI. 



Ovate, oval or obovate, usually cordate, entire or remotely si)uiulose- 



dentate . 20. Q. oblongifolia. 



Oblong-lanceolate to broadly obovat^, cordate or rounded at the base, 



spinose-dentate, pubescent and conspicuously reticulate-venulose on the 



lower surface 21. Q. Arizonica. 



Broadly obovate, cordate, usually rounded and obtuse at the apes, repandly 



spinose-dentate, coarsely reticulate-venulose 22. Q. reticulata. 



Ovate or ovate-oblong or oval, entire or remotely sjDinose-dentate . . . 23. Q. Toumeyi. 



Dark green. 



Oblong or obovate, entire, sinuate-toothed, or lobed, pubescent and often 



pale on the lower surface 24. Q. dumosa. 



Oblong, elliptical or obovate, entire or remotely spinose-dentate, j^ale or 



silvery white on the lower surface 25. Q. ViRGiJS'iANA. 



Oblong-lanceolate, entire or repand-serrate, coriaceous 26. Q* Emoryi. 



Maturation biennial ; nut sericeo-tomentose on the inner surface ; abortive ovules basal 

 or lateral. 



Leaves persistent. 



Oblong, acute or cuspidate, entire or dentate or sinuate-toothed, fulvous- 



tomentose and ultimately pale on the lower surface 27. Q. chrysolepis. 



Oblong-lanceolate, acute, crenate-dentate or entire, conspicuously veined, 



pubescent or tomentose on the lower surface 28. Q. TOMENTELLA. 



Melanobalanus. Abortive ovules superior ; stamens usually from 4 to 6 ; styles elongated, 

 finally recurved ; nut sericeo-tomentose on the inner surface. Black Oaks. 

 Maturation annual. 



Leaves persistent until the appearance of those of the following year. 



Oval, orbicular or oblong, entire or sinuately spinose-dentate, convex on 



the upper surface 



Oblong or elliptical, or oblong-obovate, usually entire, glabrous or coated 



with pale pubescence on the lower surface 



Maturation usually biennial. 



Leaves persistent until the appearance of those of the following year. 



Lanceolate, oblong-lanceolate or elliptical, entire or spinose-dentate toward 



the apex, coated with pale or fulvous tomentum on the lower surface . 31. Q. hypoleuca 

 Oblong-lanceolate, entire or sinuate-dentate, dark green and lustrous . . 32. Q. Wislizeni. 



29. Q. AGRIFOLTA 



30. Q. PUMILA. 



Oval to oblong-obovate, rounded or acute at the apex, mostly entire, with 



thickened revolute margins 



33. Q. MYRTIFOLTA 



Leaves deciduous. 



Pinnatifid or lobed. 



Oblong-obovate to oblong, the lobes tapering gradually from broad bases 

 and acute and usually dentate at the apex 



Obovate, truncate or abruptly wedge-shaped at the base, deeply lobed with 

 broad rounded sinuses, the lobes sinuate-dentate at the usually broad 

 apex 



34. Q. RUBRA. 



35. Q. Texana 



