There have been few reports of this widespread southeastern species from Ky. and some of these remain unverified. M. caroliniana is close to decipiens and intermediates have been reported further south. It may be less concentrated on base-rich soils but still "nutrient-rich" (W). Compared to decipiens, corolla lobes of carolinensis are generally shorter (7-12 mm versus 11-15 mm), broader (L/W = 1.5-2.6 versus 2.4-4), and rotate (versus ascending); buds are bluntly ovoid (versus oblong-conical). In both species, corolla lobes are widest at or above the middle with an obtuse apex (versus tapering from the base to an acute apex in obliqua), generally broader (L/W mostly 1.5-4 versus 4-6), and usually dark maroon (versus usually "rose to light maroon. rarely dark maroon, green, or cream"); the corona is thin, with alternate lobes prolonged into acute or acuminate tips (versus fleshy, with lobes all truncate or emarginate in obliqua). There do not appear to be clear differences among these species in their fruits, but some tentative records have been based on fruiting colls.