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 lb. 

 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 (Umbellifcrae) 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. 



