This annual is a widespread weed in temperate regions; 2n = 36 and 72 (FNA 25). It has probably been present in Ky. since early after settlement (McMurtrie 1819, Short & Peter 1835). In early accounts it was misleadingly named Panicum glaucum, which is a synonym of Pennisetum glaucum (M). In 1914 Gm noted: "A common weed in all fields and elsewhere."