FAGACEAE. 99 



Cup less than 18 mm. wide : lobes of the leaf- 

 blades much longer than the width of the 

 body. 3. Q. palustris. 



Cup over 18 mm. wide : lobes of the leaf- 

 blades about as long as the width of the 

 body. 4. Q. rubra. 



Cup of the acorn turbinate or hemispheric. 5. Q. coccinea. 



Leaf-blades pubescent beneath. 



Cup of the acorn turbinate : leaf -blades brown- 



or rusty-pubescent beneath. 6. Q. velutina. 



Cup of the corn saucer-shaped : leaf-blades gray- 



or white-pubescent beneath. 7. Q. nana. 



Leaf -blades, or their teeth or lobes, without bristles (except 



on shoots) : nuts often glabrous within. 

 Leaf-blades toothed or shallowly lobed. 

 Acorns sessile. 



Shrub or small tree : leaf -blades mostly broadest 



above the middle. 8. Q. prinoides. 



Tall tree : leaf -blades mostly broadest below the 



middle. 9. Q. Muhlenbergli. 



Acorns peduncled. 



Peduncles shorter than the petioles, or about equal- 

 ling them. 10. Q. Prinus. 

 Peduncles much longer than the petioles. 11. Q. ticolor. 

 Leaf-blades prominently or deeply lobed. 



Mature leaf -blades more or less pubescent beneath : cup 



fully % as long as the nut. 

 Upper scales of the cup awned forming a fringe 



around the nut. 12. Q. macrocarpa. 



Upper scales of the cup not awned. 13. Q. stellata. 



Mature leaf-blades glabrous and pale or glaucous be- 

 neath : cup shallow. 14. Q. alba. 



1. Q. Phellos L. Tree becoming 25 m. tall: leaves sometimes partly persistent; 

 blades linear-oblong or narrowly elliptic to lanceolate or oblanceolate, 4-10 cm. 

 long, shining and glabrous at maturity, entire: acorns sessile or nearly so; cup 

 saucer-shaped, 1015 mm. wide; nut subglobose, often depressed or globose- 

 ovoid, about 1 cm. long. S. Rare, on dry hills. Schists. WILLOW-OAK. 



2. Q. marylandica Muench. Tree becoming 20 m. tall, the bark very rough: 

 leaf -blades broadly or narrowly obovate in outline, 8-17 cm. long, 3-5-lobed or 

 with a single dilated terminal lobe, brownish-pubescent beneath: acorns sessile 

 or short-stalked; cup depressed-hemispheric, 15-20 mm. wide; nut subglobose or 

 ovoid, 10-20 mm. long. S. Very common, on dry hills. Serpentine, schists. 

 BLACK-JACK. BARREN-OAK. 



3. Q. palustris Du Roi. Tree becoming 6 m. tall, the lower branches reflexed: 

 leaf -blades broadly oval, varying to ovate or obovate in outline, 6-15 cm. long, 

 merely pubescent in the vein-axils beneath, deeply pinnatifid, the lobes oblong, 

 lanceolate, or triangular: acorns short-stalked; cup saucer-shaped, 12-15 mm. 

 wide; nut subglobose, 10^-15 mm. long. Common, mostly in moist woods. 

 SWAMP SPANISH-OAK. PIN-OAK. 



4. Q. rubra L. Tree becoming 50 m. tall, the lower branches spreading: leaf- 

 blades oval, varying from ovate to obovate in outline, 10^20 cm. long, with tufts 

 of hairs in the vein-axils beneath, pinnately 5-7-lobed, the lobes ascending, the 

 sinuses rounded: acorns short-stalked; cup saucer-shaped, 25-35 mm. wide; nut 

 ovoid, 25-30 mm. long. Common, in woods. RED-OAK. 



5. Q. coccinea Wang. Tree becoming 50 m. tall: leaf -blades oval, varying to 

 oblong or obovate in outline, 10-20 cm. long, glabrous, except the tufted vein- 

 axils beneath, pinnately 5-7-lobed, the lobes usually toothed: acorn sessile or 

 short-stalked; cup turbinate, 15-20 mm. wide, more or less constricted at the 

 base; nut ovoid or oblong-ovoid, mostly 10-20 mm. long. Common, in dry 

 soil. SCARLET-OAK. 



6. Q. velutina Lam. Tree becoming 50 m. tall: leaf -blades oval or obovate In 

 outline, 10-30 cm. long, usually rusty-pubescent beneath, pinnately lobed, the 

 lobes coarsely bristle-toothed: acorn sessile or nearly so; cup turbinate or 

 hemispheric-turbinate, 20-25 mm. wide; nut globose-oblong or ovoid, 15-25 mm. 

 long. Common, in woods. BLACK-OAK. YELLOW-BARKED OAK. QUERCITRON. 



