Leaves usually many; petiole 5–40 cm. long and 0.5–2 mm. thick, but sometimes wider at the pale or pinkish sheathing base; blade floating on the surface of the water, oblong to oblong-lanceolate (rarely linear-lanceolate), 2–13 cm. long and 0.3–4.5 cm. wide, base cuneate to truncate, tip blunt or acute; midrib distinct and with 2–4 parallel main nerves on each side of the midrib.
Flowers white or yellowish white, set in bifid spikes with flowers facing in all directions; peduncles 15–50 cm. long and 0.5–3 mm. thick, greenish, but paler below, not thickened towards the inflorescence; spathes 3–20 mm. long, green to greyish, rather long-persistent.
Tepals 2 in ♂ flowers, absent in ♀ flowers, white or cream, 1.5–3 mm. long, ligulate, broadly ovate or obovate, 1-nerved.
Stamens usually 6, rarely 7–8, ± as long as the perianth; filaments white, hardly widened towards the base; anthers green to yellow, turning blackish with age.
Male spikes relatively laxly flowered, usually 1–8 cm. long and 2–5 mm. wide, consisting of tepals and stamens.
Female spikes densely flowered, 1–5 cm. long and 4–8 mm. wide, consisting of ovaries only.
Seeds 1.5–2 mm. long and 0.4–0.7 mm. wide, greyish with paler longitudinal ribs; testa double.
Follicles green to brown, 3–4 mm. long and 1–2 mm. wide including a 1–1.5 mm. long narrow beak.
Ovaries 3, greenish, with 3–6 ovules.