382. Carex rostrata Stokes in W. Withering, Bot. Arr. Brit. Pl., ed. 2. 2: 1059. 1787.
Plants colonial; rhizomes long. Culms terete or very bluntly trigonous in cross section, 8–90 cm, smooth distally. Leaves: basal sheaths brown, occasionally tinged with pinkish red; ligules as long as wide; blades whitish green, U-shaped, with involute margins, widest leaves 1.5–4.5(–7.5) mm wide, papillose adaxially. Inflorescences 10–30 cm; proximal bract 18–45 cm, exceeding but no more than 2.5 times longer than inflorescence; proximal (1–)2–3 spikes pistillate, erect or the proximal ascending, ca. 20–150-flowered, cylindric; terminal (1–)2–4 spikes staminate, well elevated beyond summit of separate pistillate spikes. Pistillate scales lanceolate ovate, 2.5–4.5(–8.8) × 0.8–1.6 mm, mostly shorter than perigynia, margins entire, apex acute to acuminate (rarely acuminate-awned). Perigynia spreading, often green or straw colored, 9–15-veined, veins running into beak, ovate, 3.6–5.8 × 1.7–2.8 mm, apex contracted; beak (1–)1.2–2 mm, bidentulate, smooth, teeth straight, 0.2–0.7 mm. Stigmas 3. Achenes brown, symmetric, not indented, trigonous, smooth. 2n = 60.
Fruiting Jun–Aug. Fens, especially in flarks in patterned fens, bogs and bog pools, lake and stream shores, often in shallow water or on floating mats; 0–1600 m; Greenland; Alta., B.C., Man., N.B., Nfld. and Labr., N.W.T., N.S., Nunavut, Ont., Que., Sask., Yukon; Alaska, Mich, Minn., Mont., Wash., Wis.; Eurasia.
Carex rostrata is infrequent and local in large portions of its range, often forming large colonies where found. Carex rostrata hybridizes with C. oligosperma and C. saxatilis; rare sterile intermediates with C. utriculata are likely hybrids. The vast majority of records of C. rostrata from North America are C. utriculata.