WordNet (r) 3.0 (2006):

purple nightshade
    n 1: weedy nightshade with silvery foliage and violet or blue or
         white flowers; roundish berry widely used to curdle milk;
         central United States to South America [syn: trompillo,
         white horse nettle, prairie berry, purple nightshade,
         silverleaf nightshade, silver-leaved nightshade,
         silver-leaved nettle, Solanum elaeagnifolium]