DESCRIPTIVE MANUAL 



205 



Fig. 11 8- A. Distribution of Caltrop. 



EUPHORBIACEAE, SPURGE FAMILY. 



Many of the plants of this family contain an irritating milky 

 juice. Few are of economic importance. The poinsettia commonly 

 cultivated in greenhouses, snow-on-the-mountain in gardens, and 

 castor-oil bean belong to this family. 



Three-seeded Mercury (Acalypha virginica L.) . 



Description. — A smoothish or hairy annual from 1-2 ft. high, 

 turning purple especially in the autumn; leaves ovate or oblong- 

 ovate, sparingly serrate, long-petioled ; sterile spike, few-flowered, 

 pistillate flowers 1-3 at the base of staminate peduncle surrounded 

 by a large leaf -like bract; capsule 3-lobed, subglobular, 2-valved 

 carpels. 



Distribution. — From Nova Scotia to Texas and northward to Min- 

 nesota. Common everywhere in Iowa along roadsides and in fields. 

 Especially noticeable in the fall on account of the purple bracts. 



Extermination. — Three-seeded Mercury is not a difficult weed to 

 exterminate. The small, reddish, striate seeds are expelled from 

 the plant to some little distance in a manner similar to the dispersal 

 of the castor-oil bean. Thorough cultivation by preventing the for- 

 mation of seed will eradicate the weed. 



