Annual herb 20 cm - 1 m tall Stem: upright, usually unbranched, very hairy. Leaves: alternate, linear to oblong, mostly non-toothed, and hairy. Flowers: in a long, dense, branched cluster (raceme). Stalks widely spreading, slender, 6 - 14 mm long. Sepals four, 2 - 3.5 mm long. Petals four, pale to bright yellow, 3.5 - 5 mm long. Stamens six. Fruit: a long, narrow pod, upright to ascending, 1.2 - 3 cm long, four-angled, and hairy. Seeds in one row.
Similar species: The similar Erysimum hieraciifolium, E. inconspicuum, and E. repandum differ by having petals that exceed 5 mm long, sepals that exceed 3.5 mm long, and fruit that exceeds 3 cm long.
Flowering: mid-May to early September
Habitat and ecology: Introduced from Eurasia. In the Chicago Region, this is an uncommon but widespread weed of nitrogen-rich soils. It has become naturalized in many disturbed areas such as along roads, railroads, and in fields. Also found in barnyards, cultivated ground, and areas where grain has been accidentally scattered.
Occurence in the Chicago region: non-native
Etymology: Erysimum comes from the Greek word eryomai, meaning "to help or save," which refers to the medicinal qualities of some species. Cheiranthoides means "like Cheiranthus," which is the genus name for the wallflower.
Erect, often simple annual 2-10 dm; lvs linear to oblanceolate, entire or barely sinuate; sep 2-3.5 mm; pet bright yellow, 3.5-5.5 mm; mature racemes elongate, with straight rachis and slender, widely divergent pedicels (6-)8-12(-14) mm; frs ascending to erect, (1.2-)1.5-2.5(-3) cm; 2n=16. Usually in wet soil, but also a weed in fields and roadsides; originally European, but now circumboreal, s. in Amer. to N.C., Ark., Colo., and Oreg. June- Aug. (Cheirinia c.)
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.