From The Collaborative International Dictionary of English v.0.48 [gcide]:
Rhus \Rhus\, n. [L., sumac, fr. Gr. ???.] (Bot.)
A genus of shrubs and small treets. See Sumac.
[1913 Webster]
From WordNet (r) 3.0 (2006) [wn]:
Rhus
n 1: deciduous or evergreen shrubs and shrubby trees of
temperate and subtropical North America, South Africa,
eastern Asia and northeastern Australia; usually limited to
nonpoisonous sumacs (see genus Toxicodendron) [syn: Rhus,
genus Rhus]