This annual tetraploid (2n = 32, 36) is a widely scattered weed in temperate regions. It probably been present in Ky. since early after settlement (Gray 1864; Gm), but it has remained less abundant than asper. It may be more restricted to damp eutrophic soils, often in domestic or ruderal settings of little interest to most botanists. As observed in Mo. (St, Y), this species is undercollected and much more widespread than records indicate. In Ky. it tends to flower earlier than aspera, mostly in May-Jul (versus Jul-Sep), but both species can flower until frost.