Plants cespitose. Culms straight or arcuate, 2-85 cm. Leaves of flowering stems shorter than to exceeding culms, to 20 cm × 0.8-5.4 mm; ligules on distal cauline leaves usually obsolete (except in 414.b Carex viridula subsp. brachyrrhyncha). Inflorescences: peduncles of terminal staminate spikes 0-28 mm; bracts to 18 cm × 0.6-3.4 mm; inner band of sheaths concave or truncate. Spikes: proximal pistillate spikes 1-8, contiguous or proximal distant, sessile or short-pedunculate, globose to short-cylindric, 4-17.5 × 3-11 mm; terminal staminate spike sessile or pedunculate, 5-25 × 1-3.6 mm. Scales: pistillate scales pale brown to reddish brown, 1.4-3.2 × 0.8-1.7 mm, margins pale, narrow, hyaline; staminate scales reddish brown, lanceolate to ovate, 2.3-5.2 × 0.7-2 mm, margins narrowly pale hyaline, apex obtuse to acuminate. Anthers 0.9-3.1 mm. Perigynia spreading, yellow to dark olive, 1.8-4.2 × 0.8-2 mm, apex gradually or abruptly narrowed; beak straight or reflexed less than 20°, 0.3-2.1 mm, scabrous or smooth. Achenes 1-1.8 × 0.7-1.4 mm.
Tufted, 1-4 dm; lvs flat to canaliculate, often equaling or surpassing the stems, mostly 1-3 mm wide; terminal spike sessile or short-peduncled, slender, staminate, 7-21 mm; lateral spikes 2-4, pistillate (or the upper androgynous), short and stout, 5-15 mm, sometimes compound, all sessile or short-pedunculate and crowded at the summit, or 1 or 2 of the lower ±remote and more evidently pedunculate; bracts sheathless or nearly so (except those subtending any remote spikes), one or more of them with an elongate blade much surpassing the infl; pistillate scales shorter than the perigynia, thin and pale except the green midrib, varying to medium brown; perigynia 2.2-3.3 mm, straight or nearly so, mostly spreading or the lower reflexed, pale green to stramineous or yellowish, obovoid, distended by the trigonous, 1.1-1.4 mm achene but distally empty and slightly inflated, irregularly several-nerved, or with 2 ±evidently marginal nerves and 2-6 often less prominent ones on each face, the slender, ±smooth beak 0.8-1.2 mm; 2n=66-72. Abundant on boggy or marly shores in calcareous districts; circumboreal, s. in Amer. to N.J., Ind., S.D., and N.M. (C. chlorophila; C. oederi, misapplied) Hybridizes with no. 154 [Carex flava L.].
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.