What is "western wallflower"

Wallflower \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.