FLORA OF THE DISTRICT OF COLUMBIA. 139 



Leaves 12 cm. long or larger, more or less deeply 5-9-lobed. 

 Lateral lobes of the leaves divaricate, as broad as long, truncate or shallowly 

 lobed, the basal lobes small. Cup turbinate, about 10 mm. broad; 

 acorn ovoid; leaves copper or red-brown in autumn.. 11. Q. stellata. 

 Lateral lobes forming an angle of 45° with the midrib, oblong, simple or with 

 secondary lobes. 

 Primary lobes of the leaves entire or 2-3-lobed; cup hemispheric, 15-20 

 mm. broad; acorn oblong, 2-3 cm. long, stalked. Leaves copper- 

 brown in autumn; bark of trunk flaky 12. Q. alba. 



Primary lobes commonly entire, the leaves smaller; cup 10 mm. broad or 

 more; acorn sessile or nearly so, ovoid. (Bark and fruit resembling 

 those of Q. stellata and the leaves those of Q. alba.) 



12a. Q. albaXstellata. 



Leaves almost regularly toothed. 



Leaves angularly toothed or lobed, obovate, 10 cm. long or larger, cuneate at 

 the basC; tomentulose or green and glabrate. Fruit long-stalked; cup 

 hemispheric, 10 mm. broad or more; acorn ovoid-oblong; bark of trunk 



flaky 13. Q. bicolor. 



Leaves crenate-serrate. Chestnut oaks. 

 Teeth of leaves blunt. 

 Fruit sessile; small shrub. Leaves obovate, 10 cm. long or less, pale and 

 pubescent beneath, copper-red in autumn; cup hemispheric, 15 



mm. broad or less; acorn ovoid 14. Q. prinoides. 



Fruit stalked; tall trees. 

 Leaves oblong or obovate, pale beneath, 15 cm. long or larger, reddish 

 brown in autumn; cup turbinate, about 20 mm. broad; acorn 



ovoid or oblong, 15-24 mm. long 15. Q. montana. 



Leaves obovate, abruptly acuminate, 10 cm. long or larger, pale and 

 pubescent beneath, brown in autumn; cup hemispheric, 30 mm. 



broad or more; acorn ovoid 16. Q. prinus. 



Teeth of leaves acute. 



Plants small shrubs 14. G. prinoides. 



Plants trees. 



Leaves obovate, broad 16. Q. prinus. 



Leaves oblong-lanceolate, gray-tomentulose beneath, 10 cm. long or 

 larger. Cup 15 mm. broad or more; acorn ovoid, 12-20 mm. long. 



17. Q. muhlenbergii. 



1. Quercus phellos L. ' Willow oak. 



Moist woods. Eastern U. S. 



All the oaks flower in April or May and mature the fruit in September. 

 la. Quercus heterophylla Michx. f. Bartram oak. 



With the preceding; rare. (Q. phellosXvelutina.) 



2. Quercus imbricaria Michx. Shingle oak. 



Low woods. Eastern U. S. 



2a. Quercus leana Nutt. 

 With the preceding; rare. (Q. imbricariaXvelutina.) 



3. Quercus marilandica Muenchh. Black tack. Jack oak. 

 Dry soil . Eastern U.S. ( Q . nigra of Ward 's Flora . ) 



The characteristic form on the Serpentine barrens has 5-lobed rather than 3-lobed 

 leaves. (Q. nigra quinqueloba A. DC.) 



4. Quercus palustris DuRoi. Pin oak. 

 Low places. Northern states, south to Va. 



Frequently planted in parks and along streets. A tree is shown in plate 22A. 



