Mem. Torrey Bot. Club 1: 15. 1889.
Plants densely cespitose. Culms 15–38 cm. Leaves: sheath summits white-hyaline, green ribbed, U-shaped, occasionally prolonged to 4 mm distal to collar; distal ligules 1–3 (–3.5) mm; blades 2–4 per fertile culm, 4.5–18 cm × 1.5–2.5 mm. Inflorescences nodding, dense, dark or medium brown, 1–1.2 cm × 5.5–10 mm; proximal internode 1.3–3 mm; 2d internode 0.6–1.5 mm; proximal bracts scalelike to bristlelike. Spikes 3–6, usually individually indistinct, ovoid to broadly ovoid, 4.5–6.5 × 2.5–5.5 mm, base and apex acute to rounded; terminal spike without conspicuous staminate base. Pistillate scales dark-brown, usually with pale or green midstripe, ovate, 1.5–2.5 (–3.5) mm, usually shorter, narrower than perigynia, margin occasionally hyaline gold, to 0.4 mm wide, apex obtuse or acute. Perigynia ascending-spreading to spreading, gold to dark-brown, conspicuously 0–7-veined abaxially, conspicuously 0–4-veined adaxially, ovate, planoconvex, 2.6–3.2 × 0.9–1.3 mm, 0.5–0.65 mm thick, margin unwinged, pithlike tissue usually present in proximal perigynia walls; beak medium or dark-brown at tip, often with white-hyaline, cylindric to somewhat flat, abaxial suture with conspicuous white margin, distance from beak tip to achene 1.2–1.6 mm, entire. Achenes ovate to obovate, 1.2–1.5 × 0.8–1 mm, 0.4–0.5 mm thick. 2n = 64
Phenology: Fruiting summer.
Habitat: Marshes, bogs, wet meadows
Elevation: 2100–3700 m
Alta., B.C., Calif., Colo., Idaho, Mont., Nev., Oreg., Utah, Wash., Wyo.
Carex illota is unlike all other members of sect. Ovales in having perigynia lacking wings and margins consistently entire from perigynia base to beak tip.
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