Mapping here remains tentative. This globally restricted species occurs in rocky calcareous woods and glade margins, mostly on the southern Interior Low Plateaus (especially c. Tenn. and n. Ala.) and in or near the Black Belt region (Ala. and perhaps Miss.). Ky. colls. were made only during 1893 to 1941, mostly by S. Price (MO) from WARR ("all over Warren county"). There has been uncertainty over the correct name for these plants, named O. priceae Small by some authors (Nesom 2009). Rafinesque's (1836, 2:27) "cespitosa" evidently applied to this species: in "Glades of West Kentucky and West Tennessee, abundant, vernal, found in May and June 1823." This note predated by far publications of O. macrantha (with glabrous petals) in 1896 and of priceae (with pubescent petals) in 1898, but "caespitosa" had already been used for a different species of Oxalis (Nesom 2009). There has also been much confusion with colorea and florida; see notes under those names. Like grandis and illinoensis, macrantha has relatively large flowers, more or less red-lined in the throat (W). Compared to those two species, macrantha has particularly large flowers, with petals 13-23 mm long (versus 9-20 mm) that have strong red-lines (versus weak or strong), produced in umbelliform cymes well above the leaves (versus above or within). Also, leaflets tend be smaller, mostly 5-12 mm wide (versus 20-40 mm); stems are covered with dense non-septate hairs (versus almost glabrous to villous with at least some septate hairs); and plants tend to produce several woody rhizomes (versus one or few, herbaceous, tuberous or woody). Sm continued to distinguish priceae as endemic to Ala, Tenn. and Ky. from macrantha mostly further south: petals pubescent (versus glabrous), capsules 14-17 mm long (versus 10-14 mm), sepals ca. 7 mm long (versus 5-6 mm), stems "sparingly pubescent" (versus "villous or hirsute, sometimes sparingly so"), plants deep green (versus bright green). The potential for local differentiation should be investigated.