Perennial, aquatic, submerged, dioecious herb; stem terete, toothed, rather stout, branched, contains good quantity of starch; leaves 3-10 cm long, alternate, opposite or whorled, linear or pinnaticidly toothed, more on both surfaces and fewer on the back, teeth 4-8 on either side, triangular, base slightly dilated, dorsally spinous; sheaths entire or minutely denticulate; flowers minute, solitary, axillary, dioecious, oblong, 2-3 toothed; spathe present in male flowers; outer perianth tubular or inflated, entire or 4-fid, inner hyaline; stamen-1, adnate to inner perianth, anthers 4 celled; in female flowers perianth usually absent, if present hyaline and adherent to the carpels; carpel solitary, sessile, 1- basal, erect placenta, stigmas 2-4 lobed, style slender; fruit oblong-ellipsoid achene; seed erect, minute.