This winter- or summer-annual (Baskin & Baskin 1979) is widespread over temperate North America, especially on somewhat eutrophic soils in freshly plowed fields or dug gardens. Its first report from Ky. was in 1914 (Gm), but it has now become a widespread weed here, especially along roads and in cropland on the best soils. T. alliaceum and T. arvense are diploids (2n = 14) in distinct sections of the genus (FNA 7), but arvense appears closer to Microthlaspi; see notes under M. perfoliatum.