Herbs perennial, or subshrubs, slender, 3–15 dm, green, gla­brous. Stems erect, much-branched distally. Leaves usu­ally opposite or subopposite throughout, rarely alternate, not crowded or overlapping distally; sessile; blade narrowly linear to narrowly lanceolate, 5–40 × 1–4 mm (mostly 5–10 mm distally in inflorescences), base attenuate. Inflorescences racemes. Flowers opposite, subsessile to pedicellate, pedicel slender, 0.5–1.5 mm, distylous; floral tube obconic becoming cylindrical, 3–5 × 1 mm; epicalyx segments equal to or slightly surpassing length of sepals; petals pale purple or white, oblong to obovate, 3–4 × 1 mm, mostly shorter than floral tube; nectary absent; stamens 6. Capsules septicidal or septifragal. Seeds ca. 30, obo­void to fusiform. 2n = 20.

Flowering summer–fall. In and near brackish marshes of the Atlantic and Gulf coastal plains; 0–100 m; Ala., Conn., Del., Fla., Ga., La., Md., Miss., N.J., N.Y., N.C., S.C., Tex., Va.