Culms aphyllopodic, smoothly 3-angled, 8-40 cm. Leaves: sheath white-hyaline adaxially, summit U-shaped, smooth; distal ligule 0.5-4.3 mm; blades 0-3 per culm, 12 cm × 1.2-3 mm. Inflorescences green or pale brown, 1.6-3 cm × 7-15 mm; proximal internode (2-)4-8 mm, 2d internode 1.7-4 mm; bracts appressed to ascending. Spikes 3-8, densely clustered except, often, the proximal 1-2, obovoid-oblanceoloid, 10-16 × 5-7 mm, base acute to acuminate, apex truncate. Pistillate scales white- or gold-hyaline with green or gold midstripe, lanceolate to ovate, to 3.5-4.5 mm, shorter than or longer than perigynia. Perigynia appressed, green or gold to light brown, conspicuously 3-12-veined abaxially, 0-9-veined adaxially, wing 0.1-0.15(-0.2) mm wide, narrowly lanceolate, (4.6-)5.5-7.3 × 0.7-1.2 mm, 0.3-0.4 mm thick; beak tip white, green, or gold, narrowly flat, distance from beak tip to achene 3-5 mm, ± ciliate-serrulate. Achenes elliptic to ovate, 1-1.8 × 0.6-0.8 mm, 0.3-0.4 mm thick. 2n = 64. Fruiting summer-fall. Wet areas, at least seasonally, open, sandy, silty or peaty shores, banks, on limestone; less than 1500 m; Alta., B.C., Man., N.W.T., Ont., Que., Sask., Yukon; Alaska, Colo., Iowa, Mich., Minn., Mo., Mont., N.Y., N.Dak., S.Dak., Wash., Wis. Because Carex sychnocephala often lacks conspicuous rhizomes and has a small diffuse root system, it may appear to be annual. In some situations, it may actually grow as an annual.
Carey Densely cespitose, erect, 1-5 dm; main lvs 2-4 mm wide; bracteal lvs 2-4, dilated at base, the larger usually 1-2 dm; spikes ca 10, ovoid, 1 cm, closely crowded and almost indistinguishable in an ovoid, lobed head 2-3 cm; pistillate scales lanceolate, two-thirds as long as the perigynia, hyaline except the midnerve, acuminate; perigynia very thin, lanceolate, 5-6 mm, one sixth as wide, lightly nerved on both sides, gradually tapering to the long, slenderly bidentate beak; achene lenticular, elliptic, 1-1.5 mm. Wet meadows and shores; N.Y. to Mo., Io., Mont., and Sask.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.