Aquatic perennial, profusely branched, filiform, rhizomatous with tuberous winter-buds. Leaves submerged, acute to mucronate, narrowly linear, 1-2.5 mm wide; stipular sheath adnate to the leaf base, 2-8 cm long, tip short, acute, or mucronate margin white, open to the base. Spikes 1.5-2 cm long, cylindric 13-17 cm long and ± interrupted in fruit. Fruitlets 3-5 mm long, 2.5-3 mm broad, obliquely obovoid, smooth.