

FLORA OF THE DISTRICT OF COLUMBIA. 



137 



2. OSTRYA Scop. 

 1. Ostrya virginiana (Mill.) Willd. Hop hornbeam. Ironwood. 



Woods; Potomac valley. Apr.; fr. July. Eastern N. Amer. 



3. CORYLUS L. 



1. Corylus americana Walt. Hazelnut. 



Low places. March; fr. Aug. Eastern IT. S. 



4. ALWTJS Hill. 



1. Alnus rugosa (DuBoi) Spreng. Alder. 



Swamps and low ground. March. Eastern U. S. (A. serrulate Willd.) 



5. BETULA L. Birch. 



Leaves rhombic-oval e; hark yellow; twigs grayish, puhescent 1. B. nigra. 



Leaves ovate-oblong, cordate; bark brown; twigs glabrous or nearly so.. ..2. B. lenta. 



1. Betula nigra L. Black > red < or RIVER BIRCH - 

 Along streams and in low wet places. Apr.; fr. May. Eastern U. S. 



2. Betula lenta L. C HERRY or 8WEET BIRCH - 

 Bluffs along the Potomac above Cabin John. Apr.; fr. May. Eastern IT. S. 



38. FAGACEAE. Beech Family. 



Leaves not straight- veined, entire, crenate, lobed, or pinnatifid; fruit an acorn 

 (1-seeded nut) partially inclosed in a cuplike involucre. Staminate flowers in 

 slender pendulous aments; pistillate flowers borne singly or in clusters. 



1 3. QTJERCUS. 



Leaves straight- veined, uniformly serrate, oblong-lanceolate to ovate-oblong or 

 oblanceolate; fruit not, an acorn. 

 Leaves ovate-oblong; staminate flowers in globose long-stalked heads; fruit (bur) 

 ovate, 1.5 cm. long or less, the involucre prickly, splitting into 4 valves; nut 



2, 3-angled; trees with smooth, light gray bark 1- FAGUS. 



Leaves oblong-lanceolate to oblanceolate; staminate flowers in long slender aments 

 in separate clusters or in the upper part of the pistillate aments; fruit (bur) 

 globular, 2.5-7 cm. in diameter; nuts 2 or 3 or more, inclosed m a densely 

 prickly involucre; trees or shrubs 2 - CASTANEA. 



1. FAGUS L. 

 1. Fagus grandifolia Ebrh. Beech. 



Deciduous woods. Apr.-May; fr. Sept.-Oct. Eastern N. Amer. (F. ferrugwa 



Ait ) 



2. CASTANEA Hill. 



Plants trees; leaves 10-20 cm. long or more, oblong-lanceolate, glabrous at maturity. 

 Bur about 7 cm. in diameter l - J. dentate. 



Plants shrubs; leaves densely white-pubescent or tomentulose beneath, oblong- 

 lanceolate or oblanceolate. 



Leaves about 10 cm. long; bur 2.5 cm. long or smaller 2. C. pumila. 



Leaves 10-20 cm. long or more; mature fruit unknown 3. C. neglecta. 



1. Castanea dentate (Marsh.) Borkh. Chestnut. 

 Deciduous woods. June; fr. Sept.-Oct. Eastern IT. S. (C. vulgaris americana 



A. DC.) 



2. Castanea pumila (L.) Mill. Chinquapin 

 Deciduous and coniferous woods. June; fr. Sept.-Oct. Southern states, north 



to Pa. 



