Leaves few–many (usually 5–10 fresh leaves per plant); petiole 3–30 cm. long and 1–3 mm. thick, usually prominent, but occasionally soft juvenile linear leaves without stalk and blade are produced; blade usually floating on the surface of the water, oval to linear-lanceolate, 3–10 cm. long and 0.3–2.5 cm. wide (East African plants have 3–8 mm. wide blades), with apiculate or subacute tip and cuneate or somewhat rounded base, sometimes strongly attenuate; midrib prominent and with 2–3 weak parallel nerves on each side of the midrib.
Spikes bisexual, densely-flowered, 0.5–2.5 cm. long and 4–6(–9 in fruit) mm. wide.
Flowers white, densely set in bifid spikes with the flowers facing in all directions; penducles 5–30 cm. long and 0.5–2 mm. thick, green to olive-brown with white or purplish base, not thickened below the inflorescence; spathe up to 10 mm. long, very early caducous.
Stamens 6, but often lacking since the plants are often apomictic.
Tepals 1–2, white or with a faint pinkish tinge, ovate or obovate, 2–4 mm. long and 0.7–2 mm. wide, 1-nerved.
Follicles 5–6 mm. long and ± 3 mm. wide, greyish brown with whitish beak.
Ovaries 3–6, grey to purplish when young; ovules 2–6.
Seeds cylindrical, straight or slightly curved, 2.5–3.8 mm. long and 0.8–1.2 mm. wide, greyish green, without longitudinal ridges; testa simple.
Tuber oval or irregularly shaped, 15–40 mm. long and 10–25 mm. thick, densely set with white or brownish roots in upper part.
Freshwater aquatic with tuberous rhizome. Leaves with a distinct blade, almost always floating. Petiole up to 300 mm long. Inflorescence with 2 spikes, ± 15 mm long. Flowers turned in all directions, white or pale pink.
Fresh-water aquatic with tuberous rhizome. Leaves with a distinct blade, almost always floating; petioles up to 300 mm long. Flowers: inflorescence with 2 spikes, ± 15 mm long, flowers turned in all directions; stamens usually absent; perianth segments 2-3 mm long, white or pale pink; Nov.-Apr. Seeds with 2 coats.