Herbs, perennial, cespitose, bases cormose; rhizomes knotted, beaded. Culms trigonous, 15-48 cm × 0.4-1 mm, glabrous. Leaves flat, 10-30 cm × 0.5-2 mm. Inflorescences: spikes rather densely ovoid, 1-3.5 cm; rays 0 (sometimes 1-4), 1-6 cm; rachis 1-4 mm; bracts 3-4, horizontal to slightly reflexed, flat, 6-25 cm; rachilla ± deciduous, wingless. Spikelets 25-60, compressed, oblong-lanceoloid, 5-12 × 2.2-3.5 mm; floral scales deciduous, 5-15, yellowish to yellowish brown, laterally 4-5-ribbed, oblong-ovate, 2.6-3.6 × 1.4-2 mm, margins loosely spreading or clasping achene. Flowers: anthers 0.8-1 mm; styles 1 mm; stigmas 1.5-2.5 mm. Achenes dark grayish brown, sessile, narrowly oblong, 1.8-2.2 × 0.5-0.8 mm, apex obtuse, apiculate, surfaces puncticulate.

Fruiting summer. Well-drained, open roadsides, fields, pine barrens, dunes; 0-200 m; Ala., Fla., Ga., La., Md., Miss., N.C., S.C., Tex., Va.

Cyperus filiculmis has long been treated within a broader and more widely used concept of C. filiculmis (C. lupulinus); see B. G. Marcks (1974)

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."

Author: The Morton Arboretum

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.

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