POISONOUS PLANTS 



247 



423. Poison oak, a trailing or climbing 

 plant of the Pacific Coast. Rhus 

 diversiloba. 



in books and government publications, and periodicals. 

 Sprays of copper sulfate or iron sulfate are sometimes used 



for mustard and other field 

 weeds. A 3 per cent solution 

 of copper sulfate (about 10 Ib. 

 to 40 gal. water) at the rate of 

 40 to 50 gallons an acre de- 

 stroys wild mustard without 

 injuring peas or cereals with 

 which the weed may be grow- 

 ing. There are special herbi- 

 cides about which information 

 can be secured from the ex- 

 periment stations. These her- 

 bicides are poisonous, and 

 must be used with caution and 

 only by those who are reliable and who understand them. 



419. Poisonous Plants. Many plants produce ill effects 

 on live stock and human beings 

 when eaten; and some are in- 

 jurious to the touch. Some 

 plants produce such marked 

 results, leading even to death, 

 that they are known as poison- 

 ous plants. Some of the mush- 

 rooms are examples, two of which 

 are shown in the illustrations 

 (Figs. 419, 420), (wild mush- 

 rooms should never be eaten ex- 

 cept on the advice of someone 

 who knows the different species). 

 Many plants of the parsley 

 family (Umbelliferae) are poison- 

 ous; the poison hemlock and the water hemlock or mus- 

 quash-root are deadly when eaten. The poison ivy is shown 



424. Solanum Dulcamara. 



