Rhus

A genus of vines and shrubs (family Anacardiaceae) containing various species that are used for their ornamental foliage; formerly used in tanning. Certain poisonous species are classified as Toxicodendron. [L., fr. G. rhous, sumac]

* * *

rhus 'rüs n

1) cap a genus of shrubs and trees of the cashew family (Anacardiaceae) that are native to temperate and warm regions, have compound trifoliolate or pinnate leaves, and include some (as poison ivy, poison oak, and poison sumac) producing irritating oils that cause dermatitis see SUMAC, TOXICODENDRON

2) pl rhuses or rhus any shrub or tree of the genus Rhus

* * *

(rus) [L., gen. rhois] the sumacs, a genus of vines, shrubs, and trees of the family Anacardiaceae; most species are native to North America. Some species contain urushiol, a highly allergenic oleoresin mixture, and contact with them produces a severe dermatitis (rhus dermatitis) in sensitive persons. Extracts of the leaves and twigs of some species (see poison ivy extract and poison oak extract, under extract) have been used in the prophylaxis and treatment of dermatitis associated with these species. See also Toxicodendron.