This weedy winter/spring-annual of fallow fields is found across temperate North America, especially on relatively infertile, worn-out fields or sandy soils. In Ky. it has been locally abundant since early after settlement (Short et al. 1833; Gm). It probably occurs in cropland of all counties but is often overlooked due to small size and early flowering. In greenhouses of the Univ. of Ky. (and across the World), there is now intensive genetic research on its unusually few chromosomes (2n = 10).