This widespread eastern winter-annual is often confused with hirsuta; both are diploids (2n = 16) but hybrids are unknown. Typical parviflora is not reported from North America, and our plants may deserve species status, but any morphological differences remain obscure (W, FNA 7). In contrast to hirstua, parviflora usually lacks a distinct rosette of basal leaves; its cauline leaves are generally more numerous (mostly 5-14 versus 1-40), with more or less linear leaflets (versus oblong to suborbicular); its flowers are generally smaller (petals mostly 1.8-2.5 x 0.4-0.8 mm versus 2.5-4.5 x 0.5-1.1 mm); and its seeds are generally smaller (mostly 0.6-0.9 x 0.4-0.6 mm versus 0.9-1.3 × 0.6-0.9 mm). Plants are often glabrous (versus consistently hirsute at least on basal petioles), but can be pubescent (FNA 7). C. parviflora tends to occur on more acid and less fertile soils than hirsuta.