The sand verbenas in Abronia (Nyctaginaceae) have had an extensive history of inconsistent classification, possibly due to overlapping regions among species. Abronia fragrans is the most widespread species within the Abronia genus that also has the lowest support in genetic relationships to other species. In our previous phylogenetic analysis, we found that although Abronia fragrans is in a clade with high support it remains indistinct from several range-restricted taxa including the gypsum endemic Abronia angustifolia. We sampled over 200 herbarium specimens of Abronia fragrans to identify genetic structure in the range, especially related to a color morph variation found in west and central Texas. By using population genetic methods, we investigate further whether A. fragrans has a history of gene flow associated with color morphology and introgression with other species that have restricted distributions.