Lvs ovate to rotund, the basal lobes sometimes separated by a wide, rounded sinus, sometimes overlapping; fl-buds conic; cor brownish-purple, its lobes ascending, 10- 16 mm, 1.5-2.5 mm wide, gradually tapering from base to apex; corona fleshy, equaling or slightly surpassing the gynostegium, its lobes ±truncate or emarginate. Rocky woods and thickets; Pa. to O., Ind., and Mo., s. to N.C. and Tenn. June, July. (Gonolobus o.; Odontostephana o.; Vincetoxicum o.; G. shortii; O. shortii)

Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.

©The New York Botanical Garden. All rights reserved. Used by permission.

From Flora of Indiana (1940) by Charles C. Deam

All of my specimens are from rocky wooded slopes except one which was found in a low woods in Posey County, associated with the preceding species [Gonolobus suberosus]. 

.……

Indiana Coefficient of Conservatism: C = 10

Wetland Indicator Status: UPL

Diagnostic Traits: pubescent vines; leaves opposite, ovate to round; inflorescences peduncled axillary clusters; flowers purple-brown, corolla lobes gradually tapered from base to apex; follicle fruits lanceoloid, with soft warty projections.