5. Section Carex

Plants monoecious, the rhizomes well developed and long-creeping, forming large colonies, the aerial stems well spaced. Vegetative stems present, well developed, leafy. Flowering stems erect to ascending, sharply trigonous, glabrous, shorter than to longer than the leaves, dark purple at the base. Leaves basal and on the basal half of the stems, glabrous or hairy, the lowermost reduced to nearly bladeless sheaths. Leaf sheaths with the tip deeply concave, the lowermost sheaths brown or sometimes reddish to purplish tinged, the ligule about as long as wide and U-shaped or longer than wide and V-shaped. Spikes 4–10 per stem, the uppermost 2–6 staminate, the lowermost 2–5 pistillate, sometimes the centermost 1–2 spikes staminate toward the tip and pistillate toward the base, the bracts leaflike, the uppermost lacking sheaths, the lowermost with well-developed sheaths. Staminate spikes sessile, closely spaced to somewhat separated along the axis, erect to ascending, linear in outline. Pistillate spikes loosely spaced along the axis, none basal, sessile or short-stalked, ascending, cylindrical, with numerous ascending, densely overlapping perigynia. Perigynia 5–10 mm long, inflated, circular in cross-section or nearly so, lanceolate to narrowly ovate in outline, tapered to a straight beak ending in 2 prominent, stiff teeth 0.9–3.0 mm long, rounded at the base, sessile or sometimes with a very short stalk, the surface with numerous raised nerves (ribs), dull green to light brown or sometimes straw-colored at maturity, glabrous or hairy. Styles persistent, forming a hard, bony beak similar in texture to the main body of the fruit. Stigmas 3. Fruits obovate in outline, trigonous with flat to somewhat concave sides and blunt angles. About 20 species, North America, South America, Europe, Asia, Africa.

Section Carex is superficially similar to section Paludosae but differs in the production of true vegetative stems (as opposed to false stems composed almost entirely of a series of overlapping leaf sheaths), as well as in having larger, narrower perigynia with more prominent beaks ending in longer teeth.