Leaves: basal rosette forming in winter annual plants, absent later. Sepals ovate, hyaline margins or apex frequently purple. Seeds light tan, with delicate reticulate ridge pattern (50-80×), smooth or pebbled to strongly tuberculate. 2n = 36. Flowering spring-early summer. Moist or dryish sandy places, field margins, open pine woods, paths, roadsides, sidewalk cracks, lawns; 0-500 m; Que.; Ala., Ark., Conn., Del., Fla., Ga., Ill., Ind., Kans., Ky., La., Md., Mass., Miss., Mo., N.J., N.Y., N.C., Ohio, Okla., Pa., S.C., Tenn., Tex., Vt., Va. Specimens of subsp. decumbens from Alberta, New Brunswick, Saskatchewan, and Arizona represent historical collections that apparently did not persist.
Subspecies decumbens is extremely variable. A slender, nearly apetalous variation with a greater frequency of 4-merous flowers has previously been recognized as var. smithii; the range of variability is continuous and it seems best to consider the material as a single taxon.