Perennial aquatic or marsh herb. Rhizome creeping, rather robust, with or without enlarged tip.

The leaf of this plant is arrow-shaped with significant variations in length and width. The terminal lobe is usually shorter than the lateral lobes, with a ratio of about 1:1.2 to 1:1.5. Occasionally, the lateral lobes are longer, and there is a constriction between the terminal and lateral lobes, or not. The petiole base gradually widens, is sheath-like, with a membranous margin, and has visible or faint cross veins. The scape is upright, emergent, and typically ranges from 15 to 20-70 centimeters high, or more, usually robust. The inflorescence is racemose or paniculate, measuring 5-20 centimeters in length.

Flowers are solitary, bisexual; petals reflexed, outer petals elliptic or broadly ovate, 3-5 mm long, 2.5-3.5 mm wide; inner petals white or pale yellow, 6-10 mm long, 5-7 mm wide, base constricted. Female flowers usually in 1-3 whorls, pedicels short and thick, carpels numerous, laterally flattened, style ascending obliquely from the ventral side; male flowers in multiple whorls, pedicels obliquely ascending, 0.5-1.5 cm long, stamens numerous, yellow, 1-1.5 (-2) mm long, filaments of varying lengths, about 0.5-3 mm, usually shorter in the outer whorls and gradually longer towards the inside. Achenes laterally flattened, about 4 mm long, 3 mm wide, broadly ovate, winged, with irregular dorsal wings; fruit beak short, ascending obliquely from the ventral side. Seeds brown. Flowering and fruiting period: May to October.

The variant differs from the original in its taller and robust plants, wider and thicker leaves with broadly rounded, ovate to broadly ovate apex of the top lobe; creeping stem ends enlarge into corms, which are ovate or spherical, reaching 5-8×4-6 cm; tall panicles, 20-60 cm long, occasionally exceeding 80 cm, with 1-2 branches (1-2-) 3), bearing 1-2 whorls of pistillate flowers at the base, with 3-4 whorls of pistillate flowers on the main axis, located above the lateral branches; and many whorls of staminate flowers at the top, forming large panicles, often lying obliquely in water during fruiting season; fruiting receptacles are broadly spherical, 4-5 mm in diameter, and about 3 mm tall. Seeds are brown with small protuberances.