Micranthes petiolaris (Rafinesque) Small var. petiolaris . Section: Stellares. Hab: Rock outcrops, especially in seasonal seepage, at low to high elevations in the Southern and Central Appalachians. Dist: Nw. VA, WV, and KY south to e. TN, w. NC, sw. SC, and ne. GA.
Origin/Endemic status: Endemic
Taxonomy Comments: The species' earliest name was Saxifraga leucanthemifolia Michaux 1803, but this name is not allowable because the name had already been used for a different plant by Lapeyrouse in 1795. The next oldest name is Hexaphoma petiolaris Rafinesque 1837, and that epithet must serve as the epithet in any other genus -- unless blocked by previous usage in that genus. The species later moved through the genera Spatularia petiolaris (Rafinesque) Small 1905, Hydatica petiolaris (Rafinesque) Small 1911, Micranthes petiolaris (Rafinesque) Bush 1928, and Saxifraga. If the species is placed in Saxifraga, the epithet "petiolaris" cannot be legally transferred, because it is "blocked" by an older Saxifraga petiolaris R. Brown 1819 which refers to a different species, so Britton (1894) created a "new name" or "replacement name" in the genus Saxifraga -- Saxifraga michauxii honoring Michaux who was the first to name the species (albeit inadvertently incorrectly). This name and placement in Saxifraga had wide usage from the early 1900s to 2001. Since 2001 it is accepted that Saxifraga is not monophyletic, and that this species falls in either Micranthes or Hydatica. More recent work established that Hydatica should best be included in Micranthes.
Other Comments: The orange anthers are an attractive contrast to the white petals (the three upper with two yellow spots each).
Synonymy: = Cushman, Richards, & McMillan (2020); < Hydatica petiolaris (Raf.) Small – S, Va, Lanning (2009); < Micranthes petiolaris (Raf.) Small – FNA8, Tn, Brouillet & Gornall (2007); < Saxifraga michauxii Britton – C, F, G, GW2, K1, K3, RAB, W, WV