This annual diploid (2n = 16) is the "black mustard" that is often grown for its seed, but also a common weed across temperate North America, esecially in cooler regions; it is generally uncommon in southerastern states (K). In Ky. the species was first recorded early after settlement (McMurtrie 1819). Plants are often relatively robust, up to 2 m tall (versus 1-1.3 m in congeners of Ky.). Experimental work on this species has shown that increased pubescence can be induced by herbivory or similar damage (Dalin et al. 2008).