Perennials, aquatic. Aerial stems with sessile glands or pilose or nearly smooth and glabrous. Submerged leaves to 50 cm, multiparted; segments capillary. Aerial leaves opposite or whorled, sessile, oblong, ca. 15 X 3 mm, glabrous, base subamplexicaul, margin subcrenate; veins 3-5, parallel. Flowers sessile and in terminal spikes or short pedicellate and solitary in leaf axils. Bracteoles absent. Calyx ca. 3 mm, with sessile glands, without raised veins in fruit. Corolla pale purple, ca. 5 mm, glabrous. Capsule pale brown, subglobose, ca. 2.5 mm. Fl. Jul.