Robust monoecious aquatic or marsh perennial herb. Stems 30–40 cm tall, papillose. Leaves: submerged leaves in whorls of 4–6, broadly ovate to orbicular, pectinate, with 17–23 pinnae, lamina 25–45 mm long; emergent leaves in whorls of 5 or 6, linear, with 12–18 teeth in distal 3/4, sometimes papillose at base, lamina 25–45 mm long. Bracteoles of male flowers oblong, 0.6–0.8 mm long, fimbriate; bracteoles of female flowers minute. Flowers 4-merous, at least some in fascicles of 2 or 3. Male flowers sessile; sepals lanceolate, 0.6 mm long; petals 2.5–3.6 mm long, tardily caducous, white-hyaline; stamens 8. Female flower: pedicels 0.3 mm long; sepals and petals absent; ovary 4-locular; stigmas ±sessile, deep reddish purple. Fruit cubiform, green to reddish purple; mericarps narrowly ovoid, 0.8–1 mm long, oblique apically, dorsally surface coarsely papillose.
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