Carex atrovirens Boeckeler; C. involucrata Boeckeler

Plants colonial, long-rhizomatous. Culms (10–)20–85 cm. Leaves 2–8.5 mm wide, sparingly scabrous. Spikes 4–6, erect; lateral spikes pistillate with a few staminate flowers proximally and rarely also distally, narrowly elliptic, 11–4.5 × 5.5–11 mm; terminal spike staminate, sometimes gynecandrous or abortive, 9–42 × 1.5–3.5 mm. Pistillate scales with distinct body, 2.9–7(–11.8) × 0.4–0.9(–1.1) mm, body 1.5–2.5 mm, translucent, apex with long, scabrous awn to 1.4–4.5(–9) mm, exceeding perigynia. Staminate scales ± tightly imbricate, lanceolate, narrowly ovate, or oblong-obovate, 3.3–9.3(–12.5) × 0.9–1.6 mm, apex acute to truncate-erose or retuse, sometimes with scabrous awn to 0.1–6.2(–9.2) mm. Perigynia horizontal, 3.2–5.1(–5.6) × 1.3–2.5 mm, minutely pustulate; beak 1.2–2.1 mm, smooth. Achenes trigonous-obovoid, sides strongly concave, 1.2–1.8(–2.1) × 0.9–1.3(–1.5) mm, less than 2 times as long as wide; style deciduous, straight or sinuous.

Fruiting summer. Wet meadows and woods, muddy margins of lakes and ponds, roadside ditches; 0–500 m; Ala., Ark., Fl., Ga., Ill., Kans., Ky., La., Miss., Mo., Nebr., N.Mex., N.C., Okla., S.C., Tenn., Tex., Va.; Mexico (Coahuila, Nuevo León); South America.

Carex aureolensis has been recognized as a distinct species based on its staminate and pistillate scale morphology, growth habit, and distribution.