wall·flow·er /ˈwɔlˌflaʊ(ə)r/
  香羅蘭;局外人
  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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  wallflower
       n 1: any of numerous plants of the genus Erysimum having fragrant
            yellow or orange or brownish flowers
       2: perennial of southern Europe having clusters of fragrant
          flowers of all colors especially yellow and orange; often
          naturalized on old walls or cliffs; sometimes placed in
          genus Erysimum [syn: Cheiranthus cheiri, Erysimum
          cheiri]
       3: remains on sidelines at social event