142 PHARMACAL PLANTS AND THEIR CULTURE. 



728. Rhododendron maximum L. Great laurel. Ericacece. 

 Eastern in range ; cultivated throughout the State. Poisonous. Re- 

 quires further study. 



729. Rhododendron occidentale Gray. Azelea. Ericacece. 



Cultivated as an ornamental plant. Related to the Siberian R. chrys- 

 anthemum. (Proc. A. Ph. A. 30: 190, 1882.) (Proc. A. Ph. A. 29 r 

 225-231, 1881.) 



730. Rhus diversiloba T. and G. Poison oak. Anacardiacece. 

 Perhaps the greatest pest in California. The most annoying of all 



poisonous weeds. Said to be used by the Indians to counteract rattle- 

 snake poisoning and to remove warts. 



731. Rhus integrifolia B. and H. Sumac. Lemonade berry. Ana- 

 cardiacece. 



Rich in tannin. The seeds are used by Indians to prepare a cool- 

 ing drink. May prove of commercial value. The fruits of R. laurina 

 Nutt, and R. ovata Wats., are similarly used. The Indians use a tea 

 made from the leaves of the latter species in the treatment of coughs 

 and colds, and for pains in the chest. R. succedanea, R. vermicifera 

 and R. sylvestris, yield illuminating wax. (Proc. A. Ph. A. 26 : 295, 

 1878.) 



732. Rhus toxicodendron L. Poison ivy. Anacardiacece. 

 Common throughout the United States, having properties similar to 



those of poison oak. Rare in California. 



733. Rhus trilobata Nutt. Red fruited sumac. Anacardiacece. 

 Indians powder the berries, making a lotion used in the treatment 



of smallpox. The fruit is pleasantly acid, and is eaten by the Indians. 

 A stem decoction is said to be excellent for coughs and lung trouble. 



734. Rhus vernix L., (R. venenata D. C.) Poison sumac. Ana- 

 cardiacece. 



An Eastern poisonous plant which is spreading westward rapidly. 



735. Ribes species. Gooseberries and currants. Rosacece. 



The fruits have agreeable acid qualities and are eaten raw, cooked and 

 preserved. Numerous varieties and forms are cultivated in the State 

 There are several native species. Among them Ribes cereum Dougl.. 

 of which the fruit is eaten by the Indians. 



736. Ricinus communis L. Castor oil plant. EuplioMacece. 



A very common ornamental plant, which could be grown commer- 

 cially. Well known medicinally. There are several varieties. 



737. Robinia pseudacacia L. Locust tree. Leguminosce. 



A handsome ornamental tree with very fragrant flowers. The root 

 bark is much used by the eclectics; said to have tonic, purgative and 



