WordNet (r) 3.0 (2006):

Crocanthemum canadense
    n 1: perennial of the eastern United States having early
         solitary yellow flowers followed by late petalless flowers;
         so-called because ice crystals form on it during first
         frosts [syn: frostweed, frost-weed, frostwort,
         Helianthemum canadense, Crocanthemum canadense]