This is widespread across southeastern states, north to the southern Great Lakes, and south to Central America. It is especially common in old fields on nutrient-depleted soils (FNA 25). Variation needs further study, but only diploids (2n = 20) have been reported. Records mapped here include plants that have been referred to var. tetrastachys (Ell.) Hack., using older treatments (Hitchcock & Chase 1950), but that segregate is not recognized in recent treatments. Also, some intergradation with glomeratus is expected (FNA 25).