This annual weed is a diploid (2n = 14, 16) that is widespread across northern states and adjacent Canada. In Ky. it was first recorded during the 1930s (B). It has become widely scattered but not as abundant as Sisymbrium officinale, which is sometimes confused. Some colls. from FAYE, HARR and JEFF have strigose fruits. Erysimum differs from Sisymbrium as follows (FNA 7): plants with 2-rayed or multi-rayed hairs (versus unbranched hairs or glabrous); lower leaves entire to dentate to pinnately lobed with subequal widely spaced lobes (versus sinuate, dentate, lyrate, runcinate or pinnately lobed but with broad retrorse lobes, often unequal); fruit valves each with obscure to prominant midvein (versus with prominant midvein plus two conspicuous marginal veins). In E. repandrum fruiting pedicels are divaricate, and in S. officinale these are erect and appressed to the rachis; but there is much variation within each genus.