Smooth Sheath Sedge

Carex laevivaginata is readily distinguished from all other species in the section by the thickened, yellow sheath apex and the papillose, epistomic leaves.

Plants with basal sheaths of previous year not persistent. Culms to 80 cm × 2 mm, scabrous throughout. Leaves: sheaths all with blades, fronts smooth, lacking spots, veinless, apex yellow, thickened, truncate, cartilaginous, entire; ligules acute, 5 mm, free limb to 0.5 mm; blades yellow-green, epistomic, to 60 cm × 6 mm, papillose adaxially (25X). Inflorescences densely spicate, cylindric, elongate, with 6–15 distinguishable branches, 3–6 × 1.5 cm; proximal internode to 10 mm; proximal bracts setaceous, apparent. Scales hyaline. Perigynia pale brown, red-brown distally, with red-brown veins, 10–12-veined abaxially, 7-veined adaxially, to 6 × 2.6 mm, base slightly distended proximally, cordate; stipe to 0.2 mm; beak to 2.5 mm, margins serrulate. Achenes ovate, 2 × 1.3 mm; stalk to 0.3 mm; persistent style base cylindric, 0.3 mm. 2n = 46.

Ont.; Ala., Ark., Conn., Del., D.C., Fla., Ga., Ill., Ind., Iowa, Md., Mass., Mich., Minn., Mo., N.J., N.Y., N.C., Ohio, Pa., R.I., S.C., Va., W.Va., Wis.

Fruiting May–Jun.

Seasonally saturated or inundated soils in wet meadows, marshes, edges of tidal marshes, swamps, or alluvial bottomlands, particularly on calcareous substrates; 0–1500m.

Carex stipata Muhlenberg ex Willdenow var. laevivaginata Kükenthal in H. G. A. Engler, Pflanzenr. 20[IV,38]: 172. 1909

Carex laevivaginata (Kiikenth.) Mackenzie, in Britt. & Brown, III. Fl. ed. 2. 1: 371. 1913.
Carex stipata var. laevivaginata Kiikenth. in Engler, Pflanzenreich 4 20 : 172. 1909. (Type from Biltmore. North Carolina.)
Densely cespitose, the rootstocks short-prolonged, stout, tough, dark, fibrillose, the culms aphyllopodic, stoutish, 3-5 mm. thick at base, 3-8 dm. high, shorter than to somewhat exceeding the leaves, sharply triangular with concave sides, and slightly wing-angled, weak and flattened in drying, very rough above, light-brown at base; leaves with well-developed blades 3-6 to a culm, not bunched, the blades erect-ascending, light-green, flaccid, flat, usually 1-3 dm. long, 3-6 mm. wide, roughened on margins and towards tip, the sheaths septate-nodulose dorsally and not at all or only obscurely transversely rugulose ventrally, strongly thickened at mouth, not prolonged beyond base of blade and not breaking, the ligule conspicuous, longer than wide, colored on the margin; spikes numerous, yellowish-green, in a somewhat compound linear-oblong or oblong head 2.5-6 cm. long, 1-1.5 cm. thick, the lower branches little separate; individual spikes poorly defined, androgynous, the perigynia 4-10, ascending or spreading; bracts bristle-form and inconspicuous or the upper scale-like; scales triangular-lanceolate, hyaline with 3-nerved gTeen center, awned, narrower than and about length of bodies of perigynia; perigynia plano-convex, lanceolate, thick, 4.5-5 mm. long, 1.5-2 mm. wide, greenish or yellowish at maturity, membranaceous, strongly nerved on both sides, sharp-edged to base, abruptly slender-stipitate, spongy and truncate-rounded at base, tapering into a serrulate beak 1-2 times length of the body, dorsally cleft, bidentate, the teeth subulate-triangular, dark-tinged, appressed; achenes lenticular, small, strongly apiculate and substipitate, the body ovate-orbicular, 1.5-1.75 mm. long, 1.25 mm. wide; style slender, straight, jointed with achene, slightly enlarged at base; stigmas two, slender, reddish-brown, 1.5-2 mm. long.
Type locality' (of C. stipata var. laevivaginata Kiikenth. on which C. laevivaginata is based) : Biltmore, North Carolina (Biltmore no. 262a).
Distribution: Swampy woods. Massachusetts to Minnesota, and southward to Florida and Missouri. (Specimens examined from Massachusetts, Rhode Island. Connecticut, New York, New Jersey, Pennsylvania. Maryland, District of Columbia, Virginia, West Virginia. North Carolina. South Carolina, Georgia, Alabama, Florida, Tennessee, Kentucky, Ohio, Indiana, Illinois, Minnesota, Missouri.)