Stems 2-10 dm from creeping rhizomes, subequally quadrangular but scarcely winged, bristly-setose; hypanthium sparsely to copiously bristly, 10-13 mm at maturity; pet bright rose-lavender, 18-25 mm, generally with some bristles on the back; otherwise much like no. 5 [Rhexia mariana L.]; 2n=44. Moist or wet open places. Two geographically discrete but otherwise scarcely distinguishable segments: Plants of the Atlantic Coastal Plain, from s. N.J. to S.C., have been segregated as R. ventricosa Fernald & Griscom. More inland plants, occurring from s. Ind. to c. Ala., w. to se. Kans., e. Okla., and n. La., are considered to be R. interior proper.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.