Much branched, rootless, submerged, aquatic plants, 15-60 (-90) cm long. Leaves whorled, 1-4 times dichotomously branched, minutely toothed at irregular intervals, often terminated by 1 or 2 sharp bristles. Flowers minute, solitary, axillary, unisexual, male and female flowers at different nodes. Perianth segments 6-15, upto 1 mm long, connate at the base, each segment terminated by 2 bristles. Male flowers consisting of 8-30 stamens, spirally arranged on a convex receptacle, narrowed into the base, subsessile, apex terminated by two spinous incurved processes; anthers erect, 2-lobed, pollen elliptical or round. Female flower consists of a sessile carpel, ovary 1-celled, 1-ovuled, style simple, stigma oblique, style elongating in fruit forming the apical spine. Fruit a nutlet, 3.5-4 mm long, 2.5-3 mm broad (excluding spines), sessile with persistent perianth, ovoid, compressed, provided with 3 spines; one apical and 2-lateral, near the base.
Fl. Per.: March June.
Type: “Habitat in Europe maritimis”. Hort. Clif. (BM).
The plant is used as a cooling agent for biliosness and scorpion sting. The achenes are eaten by wild ducks (Subramanyam, l.c.). It is also commonly cultivated in aquaria.