Cyperus erythrorhizos Muhl.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
Species Description - Stout, tufted annual 1–7 dm with red roots; lvs crowded toward the base, with elongate blade 2–9 mm wide; invol bracts several, elongate, unequal; infl of clustered, cylindric spikes, the terminal cluster sessile, the others on rays to 7 cm, each spike 1–4 cm, with numerous serially arranged spikelets on an elongate rachis; spikelets 3–12 × 1–1.5 mm, 6–many-fld; rachilla persistent, with narrow, deciduous, hyaline wings; scales 1.2–1.5 mm, ovate to elliptic, with prominent, green, minutely excurrent keel, 1 or 2 adjacent pairs of much finer lateral nerves, and narrow, golden- brown margins; achenes pearly-white, unequally trigonous, 0.7–1 mm; 2n=96. Streambanks and other wet places; Mass., N.H., and N.Y. to Ont. and N.D., s. to Ark., Tex., and Ariz., and irregularly to the Pacific.