Herbs, perennial, cespitose. Culms basally cormlike, obtusely trigonous to subterete, 25-100 cm × 2-4 mm, densely minutely scabridulous. Leaves inversely W-shaped, 20-70 cm × 4-7 mm, adaxial surface densely hirtellous. Inflorescences: spikes turbinate, 10-12 × 6-9 mm, ± as long as wide; rays 6-12, 1-30 cm (longest bract equaling or shorter than longest ray), harshly scabrid; bracts 3-10, horizontal to ascending at 30°, inversely W-shaped, 6-27 cm × 3-6 mm; rachilla persistent, wings hyaline, 0.5 mm wide, covering 1/2 of mature achene. Spikelets 30-60, proximal spikelets reflexed nearly parallel to ray, distal ones spreading, linear, ± terete, 6-8 × 1-1.4 mm; floral scales persistent, 1(-2), appressed, stramineous, often suffused with reddish purple, laterally 4-6-ribbed, ovate-lanceolate, 4-4.5 × 1.4-1.6 mm, apex straight, excurved mucronate or cuspidate; terminal scale spinose. Flowers: anthers 0.5-1 mm; styles 1.5-2 mm; stigmas 2 mm. Achenes dark brown, narrowly oblong, (2.4-)2.7-2.9(-3.2) × 0.7-0.8 mm, base cuneate, apex obtuse, apiculate, surfaces puncticulate. Fruiting summer (Jul-Aug). Dry sand hills, xeric upland woods; 0-200 m; Ala., Ark., Del., Fla., Ga., Ky., La., Md., Miss., Mo., N.J., N.C., Okla., S.C., Tenn., Tex., Va. Cyperus plukenetii is distinguished by its tight, burlike spikes, few-flowered spikelets, and densely pubescent culms, leaves, and rays.

Much like no. 18 [Cyperus retrofractus (L.) Torr], but the rays, prophylls, and upper side of the bracts shortly rough-puberulent or scabrid; stem obtusely trigonous to rounded, rough-hairy to the base; spikes tight, bur-like, only slightly or scarcely longer than thick, tapering downward from the broad top, the axis 7-13 mm; spikelets 6-8 mm, with 1(2) fertile scale; scales 4-4.5 mm; bracts up to as long as the rays; rachilla-wings clasping the achene for half its length. Dry, sandy places; N.J. to Fla., w. to Ky., s. Mo., se. Okla., and e. Tex. (C. retrofractus var. p.)

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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