Perennial herb with rhizomes and runners, tufted 15 cm - 0.5 m tall Leaves: basal, alternate, grayish green, 10 - 30 cm long, 0.5 - 2.5 mm wide, flat, linear, parallel-veined, keeled beneath, with a sheathing base that encloses the stem. Inflorescence: consisting of terminal spikes, subtended by spirally arranged leafy bracts. Bracts three to four, more or less horizontal, unequal, 6 - 25 cm long, flat. Rays (branches of inflorescence) zero or sometimes one to four, 1 - 6 cm long. Spikes 1 - 3.5 cm wide, densely egg-shaped, consisting of 25 to 60 spikelets. Flowers: minute, in the axil of a floral scale, lacking sepals and petals. Stamens exserted. Anthers 0.5 - 1 mm long. Pistil one. Style about 1 mm long. Stigma 1.5 - 2.5 mm long. Fruit: a one-seeded achene, stalkless, grayish brown, about 2 mm long and 0.5 mm wide, narrowly oblong with a rounded apex, tiny-dotted. Seed with a thin, non-adherent wall. Culm: 15 cm - 0.5 m long, 0.5 - 1 mm wide, triangular in cross-section, solid. Spikelets: 5 - 12 mm long, 2 - 3.5 mm wide, compressed, narrowly lance-shaped, subtended by two small bracts, with five to fifteen floral scales. Scales yellow to yellowish brown, 2.5 - 3.5 mm long, 1.5 - 2 mm wide, narrowly egg-shaped, four- to five-ribbed, lowest one empty.
Similar species: No information at this time.
Flowering: June to late September
Habitat and ecology: Sandy soil.
Occurence in the Chicago region: native
Etymology: Cyperus is the ancient Greek word for sedge. Filiculmis means "with thread-like culms."
Much like no. 27 [Cyperus lupulinus (Spreng.) Marcks]; lvs gray-green, 1-2.5 mm wide; heads stramineous to yellowish-brown; spikelets 2-3 mm wide; anthers 0.6-1 mm; achene a little narrower, a third to nearly half as wide as long; 2n=ca 166. Dunes, pine-barrens, and disturbed sandy places, mainly on the coastal plain; se. Md. and se. Va. to Fla. and Tex. (C. martindalei)
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.