This is a widespread southeastern species of dry grasslands on medium acid soils. Much traditional usage of regularis versus volubilis is now reversed, based on better typification. Duncan (1979), Nesom (2015) and others (W) have indicated that names of recent tradition should be switched, rather than maintained through "conservation".. (This is the kind of thing that gives botanists a bad name!) Included here are several records of the more hairy G. regularis var. mississippienis Vail, which has not been recognized in recent treatments. The closely related species generally known as G. volubilis (L.) Britt. occurs mostly on the southeastern Coastal Plain; reports from Ky. are erroneous or unreliable (M), and the species is not even known for sure from Tenn. (Ch+); but see W. G. volubilis differs as follows (W): leaflets mostly ovate to lanceolate and 5-15 mm wide (versus elliptic to broadly elliptic and 10-21 mm wide), widest below the midpoint (versus at the midpoint); stems moderately to sparsely strigose with tightly to loosely appressed retrorse hairs or sometimes glabrate (versus moderately to densely hirsute to hirsute-villous with spreading-deflexed hairs); corollas 9-14 mm (7-10 mm); leaflets thin in texture, usually glaucous below (versus thick, not glaucous). Nesom (2015) stated: "The distinction between Galactia volubilis and G. regularis is subtle but examination of hundreds of collections provides a basis for considering them separate entities. The two appear to be mostly distinct in their area of sympatry (G. regularis has a much wider geographic range), but intermediates are encountered. Flowering times coincide and there is overlap in habitat, allowing opportunities for hybridization, but the relative stability of the two forms suggests that some kind of reproductive isolation is in effect, perhaps post-zygotic."