174 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 



DD. Leaves elliptic-obovate or obovate. 



Leaves subacute, scarcely rugose 14. Q. idonea. 



Leaves very obtuse. 



Leaves somewhat I'ugose and puberulent 38. Q. arizonica. 



Leaves not rugose, glabrate. 



Leaves finely low-venulose beneath 15. Q. nudinervis. 



Leaves heavily veiny beneath 16. Q. standleyi. 



DDD. Leaves elliptic-oblong, characteristically crenate only above. 



Fruit subsessile; acorn exserted" 19. Q. sororia. 



Fruit stout-peduncled ; acorn nearly included 20. Q. germana. 



DDDD. Leaves oblanceolate. Cup scales thickened. 



13. Q. tuberculata. 

 Acorn oblong, rather slender (10 to 15 mm. in diameter, 15 to 25 mm. 

 long. ) 



Leaves slender-petioled, round-based 17. Q. polymorpha. 



Leaves short-petioled, subcuneate at base 18. Q. juergensenii. 



Acorn round-ovoid, thicker 19. Q. sororia. 



CC. Leaves transiently silvery beneath, elliptic-oblong or obovate. 



52. Q. brevlloba. 

 CCC. Leaves pale- toe lentulose beneath, broadly oblanceolate. 



21. Q. glaucescens. 

 CCCC. Leaves dingy-puberulent or tomentulose beneath. Peduncle mod- 

 erate or rather long. 

 Leaves not extremely large, distinctly or slenderly petioled. 



Leaves scarcely more than undulate 30. Q. peduncularis. 



Leaves crenate throughout, not very rugose. 



Leaves elliptic-oblanceolate 22. Q. martensiana. 



Leaves subpandurate, becoming glabrate 23. Q. liebmannii. 



Leaves crenate only toward the apex, rugose, pandurate. 



24. Q. pandurata. 

 Leaves large (20 cm. long or more), very short-petioled or very thick- 

 petioled, rugose. 

 Leaves round-obovate, very obtuse. Peduncle thick. 



25. Q. macrophylla. 



Leaves more elliptic-obovate and pointed 26. Q. resinosa. 



Leaves oblanceolate-elliptic. Peduncle relatively slender. 

 Leaves not pandurate. 



Leaves rather acuminate, crisped 27. Q. circinata. 



Leaves blunt or subacute 28. Q. magnoliaefolia. 



Leaves subpandurately narrowed 29. Q. lutea. 



CCCCC. Leaves tomentose beneath, rugose. Peduncle long. 

 Leaves often very large (15 cm. wide and 25 cm. long), obovate. 



37. Q. decipiens. 

 Leaves never extremely large. 

 Leaves elliptic-oblong. 



Leaves rather large (5 cm. wide and 10 cm. long) ; peduncle 



moderate 30. Q. peduncularis. 



Leaves smaller (scarcely 3 cm. wide and 8 cm. long) ; peduncle 



filiform 33. Q. laeta. 



Leaves obovate to broadly elliptic. 



Scales of the rather large (20 to 25 mm. broad) cup lax. 



31. Q. hartwegi. 

 Scales of the smaller cup mostly appressed. 

 T^eaves broadly pandurate-obovate 32. Q. laxa. 



