This weedy northeastern species extends south to N.Car. in the Blue Ridge, and there are scattered records from the Ohio Valley, especially Ind. There are colls. from ADAI (EKY), FAYE (Univ. of Ind.), HICK (Montreal Bot. Gard.) and perhaps elsewhere. O. parviflora may have originated from hybridization of nutans with another species, and hybrids with nutans do occur in the wild (Dietrich et al. 1997). It differs from nutans (W) in its generally shorter petals (mostly 0.8-1.5 cm versus 1.4-2.5 cm), with more persistent yellow color (versus fading to yellowish-white and translucent), its free sepal tips subterminal in bud (versus terminal), and its bracts more persistent (versus caducous and paler green). O. oakesiana (Gray) J.W. Robbins ex S. Wats. & Coult. is a closely related but less widespread northern species (Dietrich et al. 1997; W), with more appressed pubescence, paler leaves and rusty brown capsules (versus dark green or black). It is probably derived from hybridization of parviflora with biennis. B's coll. of oakesiana from HARL (US) is tentatively included here, since Munz (1937) redetermined it as O. laevigata Bartlett, a synonym of parviflora.