FLORA OF THE BISTRICpT OF COLUMBIA. 125 



3. Smilax pulverulenta Michx. 



Moist woodland; common in the upper Potomac and Rock Creek regioua. May. 

 Central Atlantic states, west to Ohio Valley. 



Easily distinguished from 5. herhacea by the pulverulent pubescence on the under 

 surface of the leaves, which lack the glaucous coat. The common Potomac River form. 



4. Smilax hispida Muhl. Greenbrier. 

 Moist rich woodland ; common in the upper Potomac and Rock Creek regions. May. 



Eastern U. S. 



This is the largest greenbrier of the region Its green leaves persist well into late 

 autumn. It does not spread rapidly underground like the other woody forms and 

 entirely lacks any glaucous coat. Even normally one-seeded berries are green-black. 

 (S. pseudo-china of Ward's Flora contained the larger plants of S. hispida. The tubers 

 Ward refers to were not from Smilax, as this species does not have tubers.) 



6. Smilax rotundifolia L. Horsebrier. 



Common everywhere. May. Eastern U. S. 



6. Smilax glauca L. Catbrier. 



Common everywhere. May-June. Eastern U. S. 

 This species often has tubers on the spiny rootstocks. 



29. AMARYLLIDACEAE. Amaryllis Family. 



This family contains numerous cultivated forms grown as greenhouse and outdoor 

 ornamentals, such as Narcissus of several species among which are the daffodils, jon- 

 quils, narcissus, etc. (N. hiflorus has been collected as an escape, but probably was a 

 persistent garden bulb); Polianthes tuberosa, the tuberose; Agave, century plants; 

 and Hippeastrum, the so-called amaryllis of the trade. 



1. HYPOXIS L. Star-grass. 



1. Hypoxis hirsuta (L.) Coville. 



Frequent in grassland. May. Eastern U. S. (H.erectaL.) 



This grasslike plant is recognized by its yellow starlike flowers, and its fleshy corm 

 about 1 cm. thick. 



30. DIOSCOREACEAE. Yam Family. 

 1. DIOSCOREA L. Yam. 



Lower leaves in whorls of 4-7; leaves glaucous beneath when mature, usually hirtellous 

 with sparsely scattered hairs, sometimes almost glabrous 1. D. glauca. 



Lower leaves alternate, or the three lowest close together or indefinitely whorled; 

 leaves pubescent beneath 2. D. villosa. 



1. Dioscorea glauca Muhl. Wild yam. 

 Thickets or open woods, climbing over shrubs; common. Eastern U. S. 



This is the wild yam of commerce; its thick, much-branched, irregular rootstock is 

 the source of the drug dioscorea. 



2. Dioscorea villosa L. 



Moist or low thickets; infrequent. Conn, to Md. and westward to Okla. 

 Rootstocks long and slender, simple or rarely branched; inflorescence densely 

 many- fruited . 



