Phaseolus sinuatus (Nuttall) Torrey & A. Gray. Section: Paniculati. Subsection: Volubili. Phen: Jul-Sep; Aug-Oct. Hab: Longleaf pine sandhills, especially in loamier, more mesic swales. Dist: Sc. NC south to s. FL, west to s. MS, a Southeastern Coastal Plain endemic.
ID notes:Phaseolus sinuatus is not always easy to distinguish in sterile condition from Strophostyles. Phaseolus sinuatus has notable variegation of the leaflets, with irregular bands or spots of lighter green along the midvein and especially at the junctions of the midvein of each leaflet with the primary lateral veins.
Origin/Endemic status: Endemic
Taxonomy Comments: Freytag & DeBouck (2002) describes P. sinuatus and P. polystachios as being "very distinct and there seems to be no intergradation", yet treated them as only subspecifically distinct; I choose to recognize them as species. Debouck (2021) concurred with species rank.
Synonymy: = RAB, S, SE3, W, Debouck (2021), Isely (1998); = Phaseolus polystachios (L.) Britton, Sterns, & Poggenb. var. sinuatus (Nutt.) R.Marechal, Mascherpa, & Stainier – K1, K3, WH3; = Phaseolus polystachyus (L.) Britton, Sterns, & Poggenb. ssp. sinuatus (Nutt.) Freytag – K4, Freytag & Debouck (2002); = Phaseolus polystachyus (L.) Britton, Sterns, & Poggenb. var. sinuatus (Nutt.) R.Marechal, Mascherpa, & Stainier – Maréchal, Mascherpa, & Stainier (1978)