Descurainia is a genus of plants in the mustard family which are known commonly as the tansymustards. They are similar in appearance to other mustards, sending up long erect stems and bearing small yellow or whitish flowers. Many species are noxious weeds. Some species are toxic to livestock and become a nuisance when they grow in grazing fields. Plants of this genus are found worldwide in temperate regions. Descurainia sophia, (flixweed or herb sophia), is the type species of Descurainia. Selected species: