This is a common annual weed of the central and lower Mississippi Valley and elsewhere in central North America. It is probably adventive in some eastern states but appears native in Ky. A large-seeded selection was widely cultivated in east-central states for food by native people during the Woodland period, ca. 2000-4000 years ago (Ford 1985, Smith 2006). Based on fossils, those plants were named var. megacarpa (Blake) R.C. Jackson, but they now appear to be extinct (St, M, W).