Erysimum

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. Erysimum is characterised by star-shaped (and/or two-sided) trichomes growing from the stem, with yellow, red, pink or orange flowers and multiseeded seed pods.

==Morphology== 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, with a covering of bifid hairs, usually 25 ± 53cm × 2–3mm in size. The leaves are narrow and fixed. The lower leaves are broad and round with backwardly directed lobes, 50–80mm × 0.5–3mm. Stem leaves are linear, entire, growing whitish with 2-fid hairs; 21–43mm × 1.5–2mm. Flower clusters grow at intervals on short equal stalks along the stem, with bright yellow to red or pink bilateral flowers. Flowering occurs during spring and summer. One species, Erysimum semperflorens, native to Morocco and Algeria, has white flowers. The flowering part of the stem ranges from 4 to 7mm. There are four pouch-shaped sepals, light green, 5–7mm × 1.5–2mm.