In middle Tennessee, five species of Viola were noted to be difficult to define or recognize, and were studied in the field and herbarium. A comparison of the leaf shapes, based on a study of length-wide ratios, indicated a gradual transition in ratios going from leaves that are definitely longer than broad to leaves that are slightly broader than long. A search for introgressive hybridization was conducted, and although two probable hybrids were located, it appeared that introgression was not a significant factor in the variability exhibited. The existing variability may be attributed to undetermined localized variations in the environment. The taxonomic problems between various species are discussed with probable relationships suggested.