Herbs, perennial, cespitose; rhizomes upright, 5-8 mm diam., indurate. Culms trigonous, 30-50(-80) cm × 1.8-2.5 mm, glabrous. Leaves 4-7(-10), V-shaped, (20-)40-60 cm × 4.5-8 mm. Inflorescences: heads dense, hemispheric, 7-15(-18) mm diam; or if rays absent, heads dense, irregularly lobate, 2-3.5 cm diam.; rays 3-6, 1-30 mm; 2d order rays infrequently present, to 5 mm; bracts (5-)10-15(-40), horizontal to ascending at 30(-45)°, V-shaped, 6-30(-40) cm × 5-8(-10) mm. Spikelets 40-100, greenish white, flattened, ovoid, 3.5-5 × 3-4 mm; floral scales (8-)12-16, uniformly light greenish to light brown, laterally 1-ribbed, medially indistinctly 3-ribbed, basally 2-keeled, oblong-spatulate, widest at or above median, 2-2.5 × (0.7-)1-1.2 mm, apex minutely mucronate, scabridulous, infrequently glabrous. Flowers: stamen 1; anthers oblong, 0.7-1 mm, connective apex subulate, prolonged 0.1-0.2 mm; styles thick, confluent with apex of, and persistent on, achene, 0.5-0.8 mm; stigmas 0.6-1 mm. Achenes brown, stipitate, linear, slightly curved, 1.2-1.4 × 0.2(-0.3) mm, base whitish, stipe spongy, 0.1-0.2 × 0.2 mm, apex acute, surfaces papillose.
Fruiting summer. Damp places; 0-200 m; Ala., Ark., Del., D.C., Fla., Ga., Ill., Ind., Kans., Ky., La., Md., Mass., Mo., N.J., N.C., Okla., S.C., Tenn., Tex., Va.
Cyperus pseudovegetus is introduced in Massachusetts.
Infrequent in ditches and swamps in Point Township of Posey County. It has been found also in Gibson, Pike, and Jefferson Counties. Where found it is usually common.
Tufted perennial 3-8 dm; lvs elongate, often surpassing the stem, mostly 4-6 mm wide but conduplicate; bracts 4-8, much surpassing the infl; rays usually well developed, each bearing a terminal glomerule of spikes, or occasionally suppressed, producing a compact infl; spikes ovoid or subglobose, very dense, 7-15 mm; spikelets flat, ovate, 2-5 נ1.5-3 mm, closely imbricate with their flat sides together, (6-)10-22-fld; scales 1.5-2.5 mm, falcately incurved-ascending with divergent tip, in side-view with parallel sides, distinctly bicarinate basally; rachilla persistent, wingless; stamen 1; achenes linear-trigonous, 1-1.5 mm. Swamps and marshes; N.J. to Fla., w. to Ill., Mo., Okla., and Tex. Sometimes confused with C. virens, a more s. sp. not reaching our range.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
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