From The Collaborative International Dictionary of English v.0.48 :
Tradescantia \Trad`es*can"ti*a\, prop. n. (Bot.)
A genus including spiderwort and Wandering Jew.
[1913 Webster]
From WordNet (r) 3.0 (2006) :
Tradescantia
n 1: spiderworts [syn: Tradescantia, genus Tradescantia]