This taxon is centered in the lower Mississippi Valley and Gulf Coastal Plain, but it has been submerged within the more southeastern G. suberosus (L.) Ait. in most treatments. Typical suberosus (= Vincetoxicum gonocarpos Walt.) is not known definitively from Ky., although Kriangs (2006) cited a coll. of a transplant from JESS to the Univ. of North Carolina in 1963. There is an abrupt shift between the two taxa from the Interior Low Plateaus to the Ridge-and-Valley, with no proven overlap. But molecular data suggests incomplete genetic separation. Based on recent analysis (Krings & Xiang 2005), granulatus should be recognized at least as a variety; the name "Gonolobus petersii Nutt." has been applied to some colls. (PH). It differs from typical suberosus in its uniformly yellowish (olive-green to orange) corolla lobes on fresh upper surfaces (versus multi-colored, generally dark maroon to brownish near the base and green to yellowish near the tips). Also, laminar dorsal anther appendages are yellow, with apex rounded or truncate (versus dark purplish or maroon-tinted, with apex bilobed to emarginate). See Y and W for recent taxonomic review at species and genus level. Compared to Matelea, Gonolobus has fruits smooth, sharply 5-angled fruits (versus muricate, weakly angled); corollas have glabrous, stiffly spreading lobes (versus hairy-backed, often ascending), at least partly yellowish (versus purplish or creamy-white), with laminar dorsal anther appendages (versus absent); calyces are largely glabrous (versus hairy). Plants reportedly smell disagreeable when fresh (like burnt peanut/popcorn); they tend to be less glandular and less hairy (with sparse versus moderate to dense hairs on stems and lower leaf surfaces). Leaves tend to be darker green, more rugulose, and have narrower shape (oblong-ovate to broadly ovate versus ovate to suborbicular): "spade-shaped" versus "heart-shaped" [bwwellsassociation. wordpress. com]. But reliable distinction is often difficult to impossible without flowers or fruits.