A glabrous, aquatic perennial herb with horizontal rhizomes; scapes (30-) 50-90 (rarely-150) cm long, erect; roots fibrous. Leaves all radical, usually about as long as the scapes, linear, ensiform, sheathing at the base, 6-9 mm broad. Inflorescence umbellate, cymose with an involucre of lanceolate-acuminate bracts and bracteoles; bracts 2 or 3, upto 25 mm long, 6-8 mm broad; bracteoles numerous, less than 10 mm long, 2-3 mm broad. Flowers pink, pedicellate; pedicels (3-) 5-9 cm long. Perianth segments 6. biseriate. Sepal-like segments obovate. c. 17-veined, keeled, 9-13 mm long and 6-8 mm broad; petal-like segments broadly obovate, c. 13-veined, 9-15 mm long, 8 mm broad. Stamens usually 9, rarely 5 or numerous; filaments linear, usually dilated at the base, variable in length, free, slightly connate at the base; anthers basifixed, 2-celled, ovate to oblong (linear-oblong in young flowers), 2-4 mm long. Carpels 6-9 or many, each 3-5.5 mm long, 1.5-2 mm broad, superior, free or somewhat connate basally, obovate; style simple, short, terminal, persistent; stigma ventral, curved. Ovules numerous, anatropous, minute on reticulate parietal placentas. Fruit a many-seeded, beaked follicle, obovate, 7-9 mm long, 2-3.5 mm broad. Seeds numerous, minute, 0.2-0.4 mm long, oblong with thin testa and straight embryo.