166 



CONTRIBUTIONS FEOM THE NATIONAL HERBARIUM. 



Acorns of medium size; only tlie younger 

 leaves conspicuously toothed. 

 Leaves large, obovate, strongly reticu- 

 late; teeth small and numerous 13. Q. reticulata. 



Leaves of medium size, oblong, only 



slightly reticulate, entire or with 



few coarse teeth. 



Leaves and twigs of the year glabrous 



in age; leaves rarely with any 



teeth 10. Q. ohlongifolia. 



Leaves permanently and densely 

 stellate-pubescent beneath, as 

 also the twigs of the year; leaves 

 various. 



Cup shallow; acorn acute 12. Q. arizonica. 



Cup deep, covering one-third the 



acorn; acorntruncateorobtuse.il. Q. grisea. 

 Leaves chlorophyll green, not coriaceous, deciduous in the 

 fall, hence the plants leafless in the winter. 

 Leaves coarsely serrate-toothed with numerous teeth 



from base to apex, not truly lobed 14 . Q. muhlenhergii. 



Leaves more or less sinuately lobed. 



Low shrubs, never forming trees; leaves small, 7 cm. 

 long or less. 

 Lobes few and shallow, appearing as a few large 

 teeth; some of the leaves obovate in 



outline 15. Q. media. 



Lobes deep and more numerous; leaves oblong 

 in outline. 

 Acorns very large, 25 mm. long; a plant of 



the southeastern sandhills 16. Q. havardii. 



Acorns small, 10 mm. long or less, racemose; 

 plant of the mountains of the northern 



part of the State 17. Q. venustula. 



Taller shrubs or trees with large, deeply lobed leaves 



mostly 10 cm. long or more. 



Mature leaves soft-pubescent and almost velvety 



beneath. 



Scales of the cup thin, little thickened on 



the back; leaves distinctly obovate 



in outline 18. Q. suhmollis. 



Scales of the cup thickened on the back; 

 leaves mostly oblong, only slightly 



broadened upward 19. Q. utahensis. 



Mature leaves not velvety beneath, usually 

 glabrate, sometimes slightly pubescent, 

 especially on the veins. 

 Cup saucer-shaped, covering less than one- 

 fourth of the acorn 20. Q. vreelandii. 



Cup hemispheric, covering one-third to half 

 the acorn . 

 Aconis ovoid, acute; cup covering 



about half the acorn 24. Q. gamhelii. 



