This winter annual is largely restricted to thin woods and edges on moist base-rich soils in east-central states, and it is especially common in the central Ohio Valley. The common name is usually "Miami mist" apparently after the Miami Rv. in sw. Ohio, where this species used to carpet many miles of low woodland floors. Short (1828-9) listed it under the misapplied name P. fimbriata: "abundant throughout the western country... Moist meadows." It was formerly widespread on deep fertile soils of upland and lowlands in the Bluegrass region, including less manicured roadsides, but it has been grazed, mowed or herbicided out of many areas duing recent decades. Yet the species is easily reestablished from seed, collected during late May to early June as whole dying plant-straw, then spread soon onto sites for restoration; seedlings germinate in cool damp weather during Sep to Nov then flower during early May (at same time as Hydrophyllum appendiculatum). Variation deserves deeper study across Ky. Levy (2020) has recently revived the segregate that is now named P. purshii var. boykinii (Small) Levy. This is restricted to southeastern regions, east of the Mississippi Rv. and south of the glacial limit, but perhaps predominant only in Ala. For Ky., Levy reported colls. only from BELL, HENR and MARS. Var. boykinii differs as follows: ovary below the apex more or less pubescent (versus glabrous), abaxial surface of corolla lobes usually more or less pubescent (versus glabrous or occasionally with a few hairs), pedicels in fruit mostly 5-6.5 mm (versus 9.5-11.5 mm),or about half as long in flower for both taxa. In "barren soil" of c. Tenn. (Sm), plants with relatively small flowers and capsules, short pedicels, and style branches longer than the united portion have been segregated as P. bicknellii Small; however, these plants now appear to be just a local male-sterile form (with empty stamens or aborted pollen) and no taxonomic merit (Levy 2020). Related species (all with 2n = 18), or perhaps transitional plants, may be expected in Ky. The closely related P. fimbriata Michx. is largely restricted to cooler zones in the Blue Ridge; records from Ala. (Small 1933) and Ga. are erroneous (W). More likely as a native in se. or sc. Ky. is the P. dubia (L.) Trel. (2n = 12), which occurs in close or adjacent counties of Tenn., including var. interior Fern. that is restricted to the Nashville Basin (Ch, J, W). See also notes under cf. gilioides.