Evidence for the recognition of Viola appalachiensis

Because most taxonomists merge the Appalachian endemic Viola appalachiensis with the southeastern V. walteri, distinctions between the two taxa and the morphologically related V. conspersa were reexamined. Herbarium studies, morphometric analyses, and scanning electron microscopy of leaf vestiture and style morphology clearly distinguish V. appalachiensis from V. walteri. Most features of V. appalachiensis occur in V. conspersa or V. walteri, but its combination of character states is unique and not intermediate. Flowering specimens of V. appalachiensis produce variably stainable pollen, but herbarium specimens in fruit usually bear well-formed cleistogamous and chasmogamous seeds. Several locations for putative hybrids with V. conspersa and V. striata provide further, indirect evidence of the fertility of V. appalachiensis for outcrossing and sexual reproduction. Ecological and distributional information, coupled with morphological patterns, suggest that V. appalachiensis may have arisen from hybridization of V. conspersa and V. walteri during or after the Pleistocene glacial epoch, with subsequent genetic segregation of a population with a non-intermediate morphology and comparatively high fertility. Because it behaves like other well-defined sexual species in section Viola and is isolated ecologically or geographically from them, V. appalachiensis warrants recognition as a species distinct from V. walteri