Erysimum, or wallflower, is a genus of flowering plants in the cabbage family, Brassicaceae. It includes more than 150 species, both popular garden plants and many wild forms. The genus Cheiranthus is sometimes included here in whole or in part.
Wallflowers are annuals, herbaceous perennials or sub-shrubs. The perennial species are short-lived and in cultivation treated as biennials. Most species have stems erect, somewhat winged, canescent with an indumentum of bifid hairs, usually 25 ± 53 cm × 2–3 mm in size, and t-shaped trichomes. The leaves are narrow and sessile. The genus name Erysimum is derived from the Greek word 'Eryo' meaning to drag.
