Mapping remains tentative. This variable annual includes the common weedy "field mustard", also known as B. campestris L., plus several cultivars, including "bird's rape" (ssp. olifera DC.) and the common turnip (ssp. rapa). These cultivars can revert to wild-types when naturalized; 2n = 20 in all taxa (Al-Shehbaz 1985). There has been some confusion in nomenclature, and there are few verified records from Ky.; see notes under other species of Brassica.