Viola retusa Greene. Section: Nosphinium. Subsection: Borealiamericanae. Phen: Apr-May. Hab: Gravel riverbanks along rivers and streams, sometimes under open woods bordering riverbanks, in the Great Plains. Dist: N. ND to n. WY, south to e. KS, c. TX and nc. CO.
Origin/Endemic status: Native
Taxonomy Comments: Mysteriously showing up in Brainerd’s treatment of violets in the 1913 Britton and Brown illustrated flora, but not in his 1921 summary of North American violets. Recent studies have nevertheless shown it to be distinct from V. nephrophylla and other species in several traits; it appears to rarely occupy the same sites as V. nephrophylla. It has been virtually ignored as a Great Plains endemic, and is surely more common than the sporadic herbarium collections suggest. While not yet confirmed in the region, it occurs within a couple of counties of sw. MO, and its future discovery is expected.
Synonymy: < Viola nephrophylla Greene – FNA6, K4