Long cultivated in several forms, its native origins unknown. Found along railroads and roadsides, in fields and disturbed places. First collected in 1878 in Genesee Co.

Another important cultivated species is Brassica oleracea L., rather similar to B. napus in characters of flowers and fruit, but with sepals closely appressed to the corolla rather than slightly spreading. Brassica oleracea apparently is native to Europe but long grown in various forms including cabbage, broccoli, cauliflower, kale, kohlrabi, Brussels sprouts, etc.