Any of several BRASSICA species that are commonly called mustard. Brassica alba is white mustard, B. juncea is brown or Chinese mustard, and B. nigra is black, brown, or red mustard. The plant is grown both for mustard seed from which oil is extracted and for greens or animal feed. It was formerly used as an emetic, counter-irritant, and carminative. There is no relationship to MUSTARD COMPOUNDS.