FLORA OF THE DISTRICT OF COLUMBIA. 195 



Glands of the involucre without petal-like appendages; cyathia in umbels or cymes 

 topping a well-developed stem. 

 Plants annual, hairy; stipules glandlike; cyathia in cymbse clusters, with 1 or 



rarely 4 glands 6. POINSETTIA. 



Plants perennials or winter annuals, glabrous; stipules none; cyathia in 3-many- 



rayed umbels, with 4 glands 7. TITHYMALUS. 



Glands with petal-like appendages, or the cyathia borne in the forks of the stem 

 near the ground. 



Plants deep-rooted perennials; stipules minute 6. TITHYMALOPSIS. 



Plants annuals; stipules triangular or awl-shaped 4. CHAMAESYCE. 



1. PHYLLANTHITS L. 



1. Phyllanthus carolinensis "Walt. 

 Frequent in low sandy soil. June-Oct. Eastern U. S. to Centr. Amer. 



2. CROTONOPSIS Michx. 



1. Crotonopsis linearis Michx. 

 Reported from near Berwyn. Dry sandy soil, eastern and southern U. S. 



Mercurialis annua L. was collected by Steele on the Department of Agriculture 

 grounds in 1916, the station since destroyed. Adventive from Eur. 



3. ACALYPHA L. Thkee-seeded mercury. 



The bracts are sometimes reduced or wanting in both our species; such forms and 

 occasional intermediates are difficult to place. Variations with spreading rather 

 than appressed pubescence occur here. 



Leaves ovate, long-petioled ; bracts deeply lobed, not prominently ciliate; branches 

 ascending 1. A. virginica. 



Leaves linear to lanceolate, short-petioled; bracts dentate to cleft, usually conspicu- 

 ously ciliate; lower branches spreading, long and slender 2. A. gracilens. 



1. Acalypha virginica L. 



Common in fields, gardens, and open places generally. June-Oct. Eastern N. 

 Amer. 



2. Acalypha gracilens A. Gray. 



Common in open places, usually in drier situations than the preceding, but the 

 two often together. June-Oct. Eastern and southern U. S. 



Ricinus communis L., the castor-oil plant, is found occasionally in waste ground, 

 escaping from cultivation and often seeding itself year to year, but not established. 



4. CHAMAESYCE S. F. Gray. 



Capsules pubescent; seeds less than 1 mm. long, violet gray to reddish. Plant pros- 

 trate; stem puberulent to hairy 1. C. maculata. 



Capsules glabrous; seeds larger, black, often with a whitish coating. 



Stem hirsute, prostrate or spreading; middle leaves about twice as long as wide; 



seed faces smooth or slightly wrinkled 2. C. rafinesqui. 



Stem with scattered hairs or glabrous, erect or ascending; middle leaves about 3 

 times as long as wide; seed faces mth broken transverse ridges. . .3. C. preslii. 



1. Chamaesyce maculata (L.) Small. Milk purslane. 

 Common on dry walks and open ground. June-Nov. Eastern U. S, {Euphorbia 



maculata L.) 



2. Chamaesyce rafinesqul (Greene) Small. 



Reported from Great Falls and Marshall Hall (as Euphorbia hirsuta (Torr.) Wieg. 

 Pa. and northward. {Euphorbia rafinesqui Greene.) 



