Sp. Pl. 1: 346. 1753.
Caudices barely developed; roots often long and rhizomelike, tuberiferous. Stems usually unbranched or few-branched proximally, 40–100 cm, faces subequal, angles narrowly winged, internodes and nodes usually sparsely villous, sometimes glabrous, hairs gland-tipped. Leaves sessile or subsessile; blade lanceolate to narrowly lanceolate, ovate, or elliptic, 3–5(–7) cm × (7–)10–20(–35) mm, margins finely serrate, surfaces glabrate abaxially, bristly villous adaxially. Inflorescences diffuse, not obscured by bracts. Flowers: hypanthium globose, longer than the constricted neck, (6–)7–10 mm, glabrous or sparsely villous, then hairs gland-tipped; calyx lobes narrowly triangular, apices acute to acuminate; petals spreading, lavender-rose to lavender-purple, 1.5–2 cm; anthers curved, 5–5.5 mm. Seeds 0.7 mm, surfaces low-muricate, papillose, or tuberculate in concentric rows, with sculpturing most prominent toward crest. 2n = 22, 44.
Phenology: Flowering (May–)Jun–Sep(–Oct).
Habitat: Pine flatwoods and savannas, pine-cypress savannas, bottomland hardwoods, turkey oak-pine flats, streamhead pocosins, hillside bogs, seepages, lake, pond, and stream edges, depressions, ditches, clearings, sandy fields, powerline rights-of-way, sand, sandy peat, sandy clay.
Elevation: 10–500 m.
N.S., Ont., Ala., Ark., Conn., Del., D.C., Fla., Ga., Ill., Ind., Iowa, Ky., La., Maine, Md., Mass., Mich., Miss., Mo., N.H., N.J., N.Y., N.C., Ohio, Okla., Pa., R.I., S.C., Tenn., Tex., Vt., Va., W.Va., Wis.
Plants that have been treated as var. purshii differ mainly in reduced vesture, shorter hypanthial neck, and erect-incurved (versus recurved) calyx lobes, but there is too much intergradation and geographic ambiguity to formally recognize variants. The geographic relationship of these plants to more typical ones is closely analogous to that between R. mariana vars. exalbida and mariana, with plants called var. purshii mostly in Florida, Georgia, and South Carolina. Polyploidy does not appear to be correlated with morphological variation.
Extremes of Rhexia virginica are similar to. Rinterior or R. ventricosa, both of which are sympatric with it. Both of the latter, however, are exclusively rhizomatous, have a tendency toward longer, hairier hypanthia, have stems usually without prominently winged angles, and never produce root tubers. Hybrids between the species appear to be common, although experimental crosses between R. interior or. Rventricosa (treated here as tetraploid R. mariana) and tetraploid R. virginica produced only non-germinable seeds (R. Kral and P. E. Bostick 1969).