Rhizomes present. Cauline stems compressed, without spots, 10--25 cm; glands absent. Turions absent. Leaves both submersed and floating or floating absent, ± spirally arranged. Submersed leaves sessile, lax; stipules persistent to deliquescent, inconspicuous, convolute, adnate to blade for less than ½ stipule length, light green, ligulate, 0.2--1.2 cm, not fibrous, not shredding at tip, apex obtuse; blade light green to rarely brown, linear-setaceous, not arcuate, 1.5--11 cm ´ 0.1--0.4(--0.6) mm, base slightly tapering, without basal lobes, not clasping, margins entire, not crispate, apex not hoodlike, tapering, lacunae absent; veins 1. Floating leaves petiolate; petioles continuous in color to apex, 5--35 mm; blade adaxially light green, lanceolate-elliptic to broadly elliptic, 0.6--2.3(--2.8) cm ´ 1--11 mm, base tapering or rounded, apex acute to long tapering; veins 3--7. Inflorescences unbranched; peduncles dimorphic, submersed axillary, somewhat recurved, clavate, 1--10 mm, emersed axillary or terminal, erect to slightly recurved, slightly clavate, 3.5--22 mm; spikes dimorphic, submersed , globular to ellipsoid, 1.5--7 mm, emersed ellipsoid to cylindric, 3--14 mm. Fruits sessile, greenish brown, somewhat orbicular, compressed, abaxially keeled, laterally keeled, 1.1--2.1 ´ 1.1--2 mm, lateral keel without points; beak absent; sides without basal tubercles; embryo with more than 1 full spiral.
