Carex retroflexa Muhl. ex Willd.

Records of Carex retroflexa and C. texensis are not always clearly distinguished, consequently some reports of C. retroflexa may refer to C. texensis.

Plants without conspicuous rhizomes. Culms 10–75 cm, 1.3–1.8 mm wide basally, 0.5–0.8 mm wide distally. Leaves: sheaths tight, green, fronts hyaline; ligules less than 2 mm, wider than long; widest leaf blades 1.4–3 mm wide. Inflorescences with 3–9 spikes, 1–4 cm × 5–9 mm; proximal internodes 1–3 times as long as proximal spikes; proximal bracts to 6 cm; spikes with 3–10 spreading perigynia. Pistillate scales hyaline with green midvein, ovate, 2–3 × 1.4–1.6 mm, 3/4 length to equaling perigynia, apex acute to acuminate. Anthers 1.5–2.3 mm. Perigynia green to pale yellow, faces weakly veined, 2.5–3.2 × 1.2–1.8 mm, base of body spongy, thickened and longitudinally striate adaxially, spongy region 0.8–1.5 mm, margins entire, serrulate distally; beak 0.7–1 mm, apical teeth 0.1–0.3 mm. Stigmas straight or slightly twisted, 0.05 mm wide. Achenes ovate-circular, 1.3–1.6 × 1.3–1.5 mm. 2n = 40.

Ont.; Ark., Conn., Del., D.C., Fla., Ga., Ill., Ind., Kans., Ky., La., Md., Mass., Mich., Miss., Mo., N.J., N.Y., N.C., Ohio, Okla., Pa., R.I., S.C., Tenn., Tex., Va., W.Va.

Fruiting spring.

Thickets and openings in dry deciduous forests; 10–500m.

Carex retroflexa Muhl.; Wilid. Sp. PI. 4: 235. 1805
Carex rosea var. retroflexa Torr. Ann. Lye. N. Y. 3: 3S9. 1836. (Based on C. retroflexa Muhl.) Diemisa retroflexa Raf. Good Book 27. 1840. (Based on Carex relroflexa Muhl.) Carex bicostata Olney, Caric. Bor.-Am. 9. 1872. (Based on C. retroflexa Muhl., as treated by Carey.)
Densely cespitose, the rootstocks very short-prolonged, slender, dark-colored, fibrillose, the culms 1.5-4.5 dm. high, slender, but erect and rather stiff, sharply triangular, smooth, or rough immediately beneath the head, usually somewhat exceeding the leaves, light-brownish at base ; leaves with well-developed blades 3-6 to a fertile culm, on the lower fourth , the blades flat, green, erect or ascending, 5-25 cm. long, 1-3 mm. wide, roughened on the margins and towards the apex, the sheaths very tight, not septate-nodulose, concave at mouth, not crossrugulose nor readily breaking, the ligule very short; spikes 4-9, in an elongate terminal head 1-4 cm. long, 5 mm. thick, the lower 1-3 separated, the upper close together; staminate flowers apical, usually inconspicuous, except sometimes in the terminal spike; perigynia usually less than 10 to a spike, ascending, spreading, or at maturity much reflexed; lower bract bristleform, 0.5-5 cm. long, the upper much smaller; scales ovate, hyaline, with a green midrib, acuminate to cuspidate, usually a little narrower and shorter than the perigynia, falling before the perigynia; perigynia unequally biconvex, broadly ovate, 3 mm. long, 1.75 mm. wide, membranaceous, deep-green or brownish-green at full maturity, rounded at base, very narrowly smooth-margined to base, finely and faintly several-striate dorsally, finely many-striate at base ventrally, fully one half of the lower part of the body spongy and empty, the achene being borne in the upper part, contracted into a smooth bidentate beak one third to one fourth length of body, the teeth short, sharp, hyaline; achenes lenticular, ovoid, 1.3 mm. long, rounded at base and tapering to the apex; style short, slender, strongly enlarged at base, jointed with achene; stigmas two, slender, light-reddish-brown.
Type locality: "Habitat in Pennsylvania."
Distribution: Dry woods and thickets, Vermont and Massachusetts to Ontario and Michigan, and southward to Florida and Texas. (Specimens examined from Massachusetts, Vermont, Rhode Island, Connecticut, New York, New Jersey, Pennsylvania, Delaware, Maryland, District of Columbia, Virginia, Ohio, Indiana, Kentucky, Illinois, Missouri, Arkansas, Oklahoma, Louisiana, Texas, Mississippi, Florida.)

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

Carex retroflexa là một loài thực vật có hoa trong họ Cói. Loài này được Muhl. ex Willd. mô tả khoa học đầu tiên năm 1805.