The Gonolobus Complex (apocynaceae: Asclepiadoideae) in the Southeastern United States

Taxonomic limits of Gonolobus (Apocynaceae: Asclepiadoideae) in the southeastern United States have been controversial, with some authors recognizing two species and others only one. Over the past 30 years, most authors have tended toward recognition of a single species. However, the morphological variation within the taxon appears complicated and has not been analyzed using a quantitative approach. We analyzed the morphological variation within southeastern Gonolobus, based on 143 herbarium specimens from 13 southeastern states, using ANOVA, and mapped taxon distributions. Two distinct Gonolobus entities, based on differences in floral character states and geographic tendencies, appear to exist in the southeast, although questions regarding rank recognition remain.