Carex decomposita Muhl.

The chiefly southeastern Carex decomposita is in the Ozark (in sinkhole ponds) but not the Appalachian province. Rare or local over much of its distributional range, it is most frequent on the Mississippi alluvial plain.

Culms 5–120 cm. Leaves: sheaths adaxially strongly dotted purplish red, concave at mouth, not prolonged beyond base of blade; ligules 1.2–5.8 mm; foliage leaf blades 10–80 cm × 2.5–5.5(–7) mm. Inflorescences bisexual, evidently paniculate, proximal 3–9 branches well separated, (6–)7–15(–18) × 1–4.2 cm; basal branch with 9–33(–48) spikes; proximal internode 6–27 mm. Pistillate scales translucent with green center, 1.6–2.4 × 1–1.6 mm, shorter, narrower than perigynia. Perigynia spreading, deep olive green to brown, 8–11-veined abaxially, with or without slight median lengthwise depression, without membranous flap toward apex, obpyramidal or obovoid (body very widely obovoid or widely depressed-obovoid), unequally biconvex, 1.8–2.6 × 1.4–2 mm, shiny; beak 0.4–0.7 mm. Achenes oblong-ellipsoid to widely ellipsoid, 1.4–1.7 × 0.8–1 mm. 2n = 60, 64, 66.

Ala., Ark., D.C., Fla., Ga., Ill., Ind., Ky., La., Md., Mich., Miss., Mo., N.Y., N.C., Ohio, Okla., S.C., Tenn., Tex., Va.

Fruiting mid Apr–Aug.

Marshes, swamp forests, usually on rotten stumps, floating logs, or bases of trees (often Taxodium) or shrubs (Cephalanthus) on lake, pond, and slough margins; 0–300m.

Carex decomposita Muhl. Descr. Gram. 264. 1817
Carrx NuUallii Schw. Ann. Lye. N. Y. 1: 65. 1824. (Type from Arkansas; an obscure species,
doubtfully referred here.) Carex paniculata var. decomposita Dewey, Am. Jour. Sci. 10: 276. 1826. (Based on C. decomposita
Muhl.)
Densely cespitose, the rootstocks very short, lignescent, blackish, fibrillose, the culms stout at base (4-8 mm. thick), slender above but stiff, more or less roughened on the angles above, 4-10 dm. high, obtusely triangular with convex sides, from shorter than to much exceeding the leaves, darkor blackish-brown at base and clothed with the dried-up leaves of the previous year, the lowest bladeless; leaves of the year with well-developed blades several to a culm, on lower third, strongly separate, the blades erect, very long, 2-7 dm. long, 2.5-8 mm. wide, flat or somewhat canaliculate, thickish, light-green, stiff, the margins and main nerves (especially in the larger leaves) very serrulate, the sheaths tight, septate-nodulose dorsally, hyaline and strongly purplish-red-dotted ventrally, concave and slightly reddish-brown-tinged at mouth, the ligule wider than long; spikes androgynous, very numerous, in a decompound panicle 4-15 cm. long, 1-4.5 cm. wide, the panicle-branches widely separated but the spikes closely aggregated on the branches, the spikes with several to many spreading perigynia and inconspicuous terminal staminate flowers; bracts absent or occasionally one or two short ones present, 2 cm. long or less, awl-shaped, long-attenuate; scales ovate-triangular, mucronate, hyaline, with 3-nerved green center, narrower and rather shorter than the perigynia; perigynia unequally biconvex, high-convex dorsally, low-convex ventrally, thick, very coriaceous, olive or brownish-green, 2-2.5 mm. long, 1.75 mm. wide, the body broadly obpyramidal, few-nerved dorsally, several-nerved at the base ventrally, sharp-edged ventrally to base and serrulate on upper part, tapering at base into a short stipe, very spongy at base, very abruptly beaked, the beak slender but flat, shallowly bidentate, serrulate, one third length of body; achenes very closely enveloped, lenticular, oblong-elliptic, slightly more than 1 mm. long and less than 1 mm. wide, apiculatc, substipitate; style very short, slender, slightly enlarged at base, jointed with achene; stigmas two, light-reddish-brown, slender, short.
Type locality: "Habitat in Cherokee."
Distribution: Swamps, Florida to Louisiana, and northward to Maryland and west of the mountains to Michigan and western New York; very local northward. (Specimens examined from western New York, Maryland, Ohio. Michigan, Indiana, Missouri, Arkansas. Louisiana. Alabama, Florida.)

Carex decomposita adalah spesies tumbuhan seperti rumput yang tergolong ke dalam famili Cyperaceae. Spesies ini juga merupakan bagian dari ordo Poales. Spesies Carex decomposita sendiri merupakan bagian dari genus Carex. Nama ilmiah dari spesies ini pertama kali diterbitkan oleh Muhl..

Carex decomposita là một loài thực vật có hoa trong họ Cói. Loài này được Muhl. mô tả khoa học đầu tiên năm 1817.