Plants cespitose, 30–100 cm tall.
Leaves sheath fronts cross-corrugated, white-hyaline with brown spots; blades approximately 5 mm wide, generally longer than the flowering culms.
Inflorescences elongate, (3)7–10 cm × 15 mm, somewhat interrupted; bracts hair-like, usually conspicuous; spikes many, short, androgynous; lowest node usually with a short branch with at least 1 side spike, thus the lowest node often seeming to produce 2 spikes.
Female scales brown, short-awned.
Perigynia elliptic to ovate, 2–3.2 × 1.3– 1.8 mm, dull grayish brown, with 0–3 dorsal veins, veinless ventrally; base obtuse or rounded, depending on the amount of pithy tissue within; stigmas 2.
Achenes lenticular.
2n=52, 54.
Moist to wet meadows, marshes and ditches. 0–1300 m. BW, Casc, Col, ECas, Owy, Sisk, WV. CA, ID, WA; throughout most of Canada and US, south to Mexico; Eurasia, New Zealand. Native.
Carex vulpinoidea is a cespitose sedge with cross-corrugated leaf sheaths and long, interrupted inflorescences with conspicuous though almost hair-thin bracts. Carex densa, its equivalent west of the Cascades, has a shorter, uninterrupted inflorescence with less conspicuous bracts and yellower perigynia that average larger, with more dorsal and ventral veins. Its leaves are shorter than the flowering culms. Carex vulpinoidea is native in eastern Oregon and along the Columbia, but southwestern Oregon records are recent introductions.
as described under Carex vulpinoidea
Culms to 100 cm × 2 mm, scabrous. Leaves: sheath fronts spotted red-brown or pale brown, apex truncate or short-convex, membranous or hyaline, rugose; ligule retuse or rounded, to 2 mm, free limb to 0.2 mm; blades 120 cm × 5 mm, longer than flowering stem. Inflorescences spicate, (3-)7-10 cm × 15 mm, with 10-15 branches, the proximal branches distinctly separate; the proximal internode to 25 mm; bracts setaceous, those subtending at least the proximal lateral branches conspicuous. Scales pale brown, hyaline, awn to 3 mm. Perigynia green to pale brown, veinless on both faces or 3-veined abaxially, body ovate or elliptic, 2-3.2 × 1.3-1.8 mm, base obtuse; beak 0.8-1.2 mm, 1/3-1/2 length of perigynium. Achenes red-brown, ovate, 1.2-1.4 × 1 mm, glossy. 2n = 52.Fruiting Jul-Aug. Seasonally saturated or inundated soils in open habitats, wet meadows, marshes, roadside ditches; 0-1800 m; St. Pierre and Miquelon; Alta., B.C., Man., N.B., Nfld. and Labr., N.S., Ont., P.E.I., Que., Sask.; Ala., Ariz., Ark., Calif., Colo., Conn., Del., D.C., Fla., Ga., Idaho, Ill., Ind., Iowa, Kans., Ky., La., Maine, Md., Mass., Mich., Minn., Miss., Mo., Nebr., N.H., N.J., N.Mex., N.Y., N.C., N.Dak., Ohio, Okla., Oreg., Pa., R.I., S.C., S.Dak., Tenn., Tex., Vt., Va., Wash., W.Va., Wis., Wyo.; Mexico (Sonora); introduced to Europe; New Zealand.Carex vulpinoidea is widely distributed in North America and frequently grows as a weed in wet roadside ditches and fields. It is quite variable, particularly in the degree to which the spongy tissue lateral to the achene is developed. The development of that tissue determines the shape of the perigynium and the degree to which the perigynium appears to contract into the achene, as discussed by F. M. B. Boott (1858-1867). The flowering stems shorter than the leaves, the pale brown, elliptic perigynia, and the preference for moist substrates of C. vulpinoidea readily distinguish it from C. annectens.