Cyperus bipartitus Torr.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
Species Description - Tufted annual 1–2(–4) dm; cauline lvs 1–3 mm wide, usually shorter than the stem; spikes all sessile, or the 1–5 rays to 10 cm; spikelets 3–10, 8–15 × 2–3.5 mm; scales ovate, 2–2.5 mm, as seen from the side in half-view usually less than 3 times as long as wide, obtuse, and with the prominent midvein incurved distally to a somewhat cucullate tip, at maturity strongly red-brown from midrib to margin (less so distally), not sulcate; stamens 2(3); achenes lenticular, elliptic-obovate, 1–1.5 mm; style undivided in the basal third, deciduous. Wet ground, especially along shores; Me. and Que. to N.D., s. to Ga. and Tex. (C. niger var. castaneus; C. rivularis)