This widespread species of eastern and central North America is locally common in trampled or mowed areas on nutrient-rich soils, especially barn yards and cow pastures. It was frequently used for its edible seed by native people during the Woodland era, along with other starchy seeds (Chenopodium buschianum, Hordeum pusillum, Phalaris caroliniana) and the oily Iva annua (Ford 1985, Wymer & Abrams 2003). However, there is little evidence of selection for seed size. P. achoreum S.F. Blake (erectum ssp. a.) is a closely related species of cool temperate to boreal regions that may also be expected in Ky.; 2n = 40, 60 (FNA 5, PL). Both of these taxa are distinguished by their "bottle-shaped periianth, constricted above the achene" (W).