66 FAGACEAE. 



brown thin-shelled nuts, I or several in a prickly dehiscent bur. 

 i.- Mature leaves essentially glabrous beneath. 2. 



Mature leaves pubescent beneath, of petioles pubescent. 4. 



2. Young leaves glabrate, acute at base. (American).. C. dentata. 

 Young leaves stellate-tomeiitose beneath. 3, 



3. Leaves acute at base. (European chestnut). C sativa. 

 Leaves rounded Or subcordate at base. (Japanese). C. crenata. 



4. Petiole villotls : riuts several in the bur. C. mollissima. 

 Petiole Hot villous : nut solitary. (Chinquapin). C. pumila. 



QUERCUS. Oak. 



In our region deciduous trees, or exceptionally shrubs, with 

 yellowish or red-brown hard ring-porous wood with the smal- 

 ler ducts radially arranged, fine medullary rays, with transverse 

 bands of wood parenchyma and frequent very heavy interven- 

 ing rays ; slender or moderate usually fluted twigs ; moderate 

 5-angled continuous pith ; alternate rather small half-round 

 somewhat raised leaf-scars with half a dozen scattered bundle- 

 traces ; minute stipule-scars or filiform persistent stipules; ses- 

 sile ovoid or conical buds crowded toward the tip, with a con- 

 siderable number of scales ; entire or toothed or mostly pin- 

 nately lobed petioled leaves ; monoecious small apetalous flowers, 

 in catkins or axillary; and nut-like fruit with a scaly cup at the 

 base. 



1. Leaves entire. 2. 



Leaves coarsely toothed. 3. 

 Leaves distinctly lobed. 5. 



2. Leaves narrow (under 25 mm. wide), glabrous. Q. Phellos. 

 Leaves broad (of ten- 50 mm.), downy beneath. Q. imbricaria. 



3. Shrub : leaves sharp-toothed, downy beneath. Q. prinoides. 

 Trees : leaves downy beneath. 4. 



4. Leaves with sharp teeth : fruit sessile. Q. Muhlenbergii. 

 Leaves with blunt teeth : fruit long-stalked. Q. bicolor. 



5. Lobes blunt, never bristle-tipped. 6. 

 Lobes acute, ending in bristles. 10. 



6. Leaves pubescent beneath : twigs buff. Q. macrocarpa. 

 Leaves glabrous or nearly so. 7. 



