Field Mustard, Common Mustard, Turnip, Wild Turnip: Brassica rapa (Synonyms: Brassica campestris, Brassica campestris ssp. rapifera, Brassica campestris var. rapa, Brassica rapa ssp. campestris, Brassica rapa ssp. olifera, Brassica rapa ssp. rapa, Brassica rapa ssp. rapifera, Brassica rapa ssp. sylvestris, Brassica rapa var. campestris, Brassica rapa var. rapa, Caulanthus sulfureus) - Siliques with a rounded beak which is 1-nerved (1-veined). The valves of the lower portion of the siliques are single-nerved. Siliques spreading and ascending. Stem leaves sessile with heart-shaped clasping bases.
Chinese Mustard, India Mustard, Indian Mustard: Brassica juncea (Synonyms: Brassica integrifolia, Brassica japonica, Brassica juncea var. cripsifolia, Brassica juncea var. japonica, Brassica willdenowii, Sinapis juncea) -
Charlock, Wild Mustard: Sinapis arvensis (Synonyms: Brassica arvensis, Brassica kaber, Brassica kaber var. pinnatifida, Brassica kaber var. schkuhriana, Sinapis arvensis var. orientalis, Sinapis arvensis var. schkuhriana) - Siliques with conspicuously flattened beaks which are 3-nerved (3 veins). The valves of the lower portion of the siliques bear 3 nerves. Siliques ascending.
Black Mustard: Brassica nigra (Synonym: Sinapis nigra) - Siliques with a rounded beak which is 1-nerved (1-veined). The valves of the lower portion of the siliques are single-nerved. The siliques are tightly appressed to the stem or ascend closely and paralleling the stem. Stem leaves petiolate to sessile but lacking the heart-shaped bases which extend around the stem.