Wall·flow·er n.
 1. Bot. A perennial, cruciferous plant (Cheiranthus Cheiri), with sweet-scented flowers varying in color from yellow to orange and deep red. In Europe it very common on old walls.
 Note: ☞ The name is sometimes extended to other species of Cheiranthus and of the related genus Erysimum, especially the American Western wallflower (Erysimum asperum), a biennial herb with orange-yellow flowers.
 2. A lady at a ball, who, either from choice, or because not asked to dance, remains a spectator.  [Colloq.]
 3. Bot. In Australia, the desert poison bush (Gastrolobium grandiflorum); -- called also native wallflower.
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 Erysimum asperum
      n : biennial or short-lived perennial prairie rocket having
          orange-yellow flowers; western North America to Minnesota
          and Kansas; sometimes placed in genus Cheiranthus [syn: western
          wall flower, Cheiranthus asperus, Erysimum arkansanum]