DESCRIPTIVE MANUAL 



213 



Fig. 124-A. Distribution of Cypress Spurge. 



ANACARDIACEAE, SUMACH FAMILY. 



Many of the plants are poisonous. Many, like sumach, contain 

 tannin. Some, as the smoke tree, are cultivated for ornamental 

 purposes. 



Poison Ivy (Rhus toxicodendron L.). 



Description. — -A climbing or trailing shrub sometimes erect, cling- 

 ing to trees or other objects by aerial rootlets ; 3 leaflets ; inconspicu- 

 ous flowers ; waxy fruit, frequently remaining on plant until late 

 winter or early spring. It is often mistaken for Virginia creeper 

 (Psedera quinquefolia (L.) Greene) which, however, has 5 leaflets. 

 Many persons are sensitive to poisoning from this plant, every part 

 of which contains the poisonous principle. The usual remedy for in- 

 fection from it is to wash the skin with a solution of sugar of lead. 



Distribution. — Poison ivy is abundant throughout eastern North 

 America and the Rocky mountains. It is common everywhere in 

 Iowa, in hedge rows, thickets or woods. 



Extermination. — Poison ivy is not easily destroyed because in 

 most cases it is troublesome in wood lots along fences and in yards. 

 It is difficult to destroy except by giving thorough cultivation. If 

 persistently cut off below the surface of the ground it can be de- 

 stroyed. Sodium arsenite at the rate of one and one-half to two 

 pounds to 52 gallons of water will help to destroy the weed. It is 

 not, however, safe to use this since it is a strong poison. 



MALVACEAE, MALLOW FAMILY. 

 Cotton, hollyhock and okra are well known plants of the family. 



