Syst. Veg. 3: 808. 1826.
Culms sharply angled, at least 1 angle serrulate distally, 10–35 cm. Inflorescences with pistillate heads 2.5–5 cm wide; proximal spikes ascending-spreading to spreading. Pistillate scales reddish to brown with green or gold center, sometimes with distal margins white or pale gold, 0.1–0.3(–0.5) mm wide, apex short-tapered with awn to 1.2–4 mm. Anthers 2.5–5 mm. Perigynia ascending to ascending-spreading, sometimes spreading, with deeply erose wings 0.7–1.7 mm wide, base cordate; beak ± straight, 6.5–9 mm from apex to achene, apex notched 0.7–1.5 mm adaxially. Achenes 3–4.5 × 2.3–3 mm. 2n = 74, 78.
Phenology: Fruiting spring–summer.
Habitat: Sandy beaches along seacoasts, sounds, bays, and inlets, especially on dunes
Elevation: 0 m
B.C., Alaska, Oreg., Wash., Asia [Japan, Russian Far East (Kamchatka) to n China].