Herb 1.5–5 cm high, to 18 cm when inundated. Leaves linear, 0.6–1.3 cm long, 0.04–0.07 cm wide, 1-nerved. Peduncle 1.5–4.5 cm long, to 18 when inundated. Sheath 8–10 mm long. Flower heads globular, 2.5–5 mm long, 2.5–6.5 mm wide. Involucral bracts hyaline, elliptic, 1.3–2.5 mm long, 0.7–1 mm wide, acute, pubescent with sparse white hairs, strongly reflexed at maturity. Floral bracts hyaline, elliptic or oblanceolate to narrowly spathulate, 1–2.5 mm long, 0.46–1.1 mm wide, acute to acuminate, pubescent with dense white hairs on apical half, basally with hyaline hairs. Receptacle glabrous. Male flowers: sepals 3, fused but split on one side to form a spathe, hyaline to greyish, 1–2.1 mm long, 0.4–0.75 mm wide, truncate, pubescent with apical fringe of white hairs; petals 3, hyaline, equal, oblong, obtuse, pubescent with apical fringe of white hairs; stamens 6; anthers yellow. Female flowers: sepals 3, hyaline, equal, linear, lacking dorsal keel or wing, 0.75–1.6 mm long, 0.05–0.15 mm wide, acute, pubescent with hyaline hairs on apex and margins, rarely white hairs on apex; petals 3, hyaline, equal, linear, 0.75–1.3 mm long, c. 0.05 mm wide, acute, pubescent with apical fringe of white hairs and hyaline hairs basally and on margins; ovary 3-locular. Seeds 0.275–0.33 mm long, 0.175–0.25 mm wide; epidermal cells with even wall thickenings.
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