MONOECIA.— POLYANDRIA. 35? 



550. QUERCUS. Oak. Corylacece. 



* Fructification biennial; leaves setaciously mucronatt. 



j Leaves entire. 



1. Q. Phellos : leaves deciduous, linear-lanceolate, at- 



tenuate at each end, very entire, smooth, mucro- 

 nate ; acorn roundish. 

 HAB. Sandy woods. A large tree ; young leav. 

 dentate ; acorn small. 



2. Q,. imbricaria : leaves deciduous, oblong, acute at 



each end, mucronate, very entire, shining, pubes- 

 cent beneath ; cup flat ; scales broad-ovate ; acorn 

 subglobose. 

 HAB. Woods and river banks. A large tree. 



1 1 Leaves dentate, or with short lobes. 



3. Q,. heterophylla : leaves on long petioles, ovate- 



lanceolate and oblong, entire, or coarsely toothed ; 

 cup hemispherical ; acorn subglobose. 

 HAB. River banks. A hybrid ? 



4. Q, aquatica : leaves obovate-cuneiform, smooth, 



very entire, obscurely 3-lobecl at the end, with 

 the middle lobe largest ; cup hemispherical ; 

 acorn subglobose. 

 HAB. Swamps. Tree middle-sized ; leaves very 

 variable. 



5. Q,. triloba : leaves oblong-cuneiform, acute at the 



base, somewhat 3-lobecl at the end ; lobes equal 

 and mucronate, tomentose beneath; cup flat; acorn 

 depressed-globose. 

 HAB. Fine barrens. Tree small. 



G. Q, nigra : leaves coriaceous, cuneiform, subcordate 

 at the base, dilated, and retusely 3-lobed at the 

 summit, when young, mucronate, smooth above, 

 rusty pubescent beneath ; cup turbinate, with the 

 scales obtuse and scanous ; acorn short-ovate. 

 HAB. Pine barrens. Tree 10— 20 ft. high ; acorns 

 abundant. 



7. Q,. tinctoria : leaves ovate-oblong, slightly lobed, 

 pubescent beneath ; lobea oblong, obtuse, mucro- 

 nate : cup flat ; acorn depressed-globose. 



