

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 cymose 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. TITHYMALTJS. 



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

 near the ground. 



Plants deep-rooted perennials; stipules minute 5. TITHYMALOPSIS. 



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



1. PHYLLANTHUS 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 II. S. 



Mercurial-is annua L. was collected by Steele on the Department of Agriculture 

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



3. ACALYPHA L. Three-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. P. 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 with broken transverse ridges. . .3. C. preslii. 



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

 Common on dry walks and open ground. June-No v. Eastern U. S. (Euphorbia 



maculata L.) 



2. Chamaesyce rafinesqui (Greene) Small. 



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

 Pa. and northward. (Euphorbia rafinesqui Greene.) 



