

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 ehallowly 

 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. alba X stellata. 



Leaves almost regularly toothed. 



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



the base ; 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 !*• 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- P rmus - 



Teeth of leaves acute. 



Plants small shrubs - "• Q- prinoides. 



Plants trees. 



Leaves obovate, broad 16 - Q - P rinus - 



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 IT. 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. phcllosXvelutina.) 



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 jack. 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 quinqucloba A. DC.) 



4. Quercus palustris DuRoi. PlN 0AK - 

 Low places. Northern states, south to Va. 



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



