Submerged, rhizomatous, scapigerous, perennial herb; rootstock tuberous; leaves submerged, floating or erect, spirally arranged, 3-5 nerved, lateral veins opaque; submerged leaves sessile, linear, rigid; floating leaves elliptic to ovate, apex acuminate to rounded, margins entire; petiole slender, much longer than blade; scape long, unbranched, bearing a single or paired, terminal spikes, often erect to ascending, cylindric, unilateral or distichous, densely flowered; young flowers enclosed in conical, deciduous spathe or sheath; perianth lobes-1-3, equal or unequal, obovate, short or sometimes absent; stamens-6 or more, filaments unequal, subulate, persistent, anthers didymous, bluish purple; carpels 3-6, free, ovules 2 or more, style short, stigma discoid, persistent; fruits of 3 or more, coriaceous, echinate, sessile, 2-seeded follicles, green to greenish brown, obovoid, beak erect or recurved; seeds minute, erect.