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Cyperus acuminatus Torr. & Hook.  
Family: Cyperaceae
tapertip flatsedge
Cyperus acuminatus image
Max Licher  
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Gordon C. Tucker*, Brian G. Marcks* & J. Richard Carter * in Flora of North America (vol. 23)
Herbs, annual, cespitose. Culms roundly trigonous, (10-)20-30(-45) cm × 0.4-1.2 mm, distal 1/2 glabrous or infrequently scabridulous. Leaves 2-6(-8), V-shaped or flat, 8-12(-16) cm × 1-2(-4) mm. Inflorescences: heads hemispheric, 7-12(-15) mm diam.; rays 1-3(-5), 0.5-2 cm; bracts 3-6, longest erect to ascending, flat to V-shaped, (1.5-)3-12(-25) cm × 1-2.5(-3.5) mm. Spikelets (15-)25-50(-75), ovoid, compressed, 4-7 × 2-3 mm; floral scales 8-20(-35), laterally yellowish, yellowish green, or light reddish brown, medially light brown or greenish brown, 2-keeled, subtly 1-ribbed, ovate-lanceolate, 1-2 × 1-1.4 mm, apex acute, mucronate, straight to excurved, glabrous or sparsely scabridulous. Flowers: stamen 1; anthers 0.5 mm; styles 0.8-1.1 mm; stigmas 0.5 mm. Achenes brown, stipitate, broadly ellipsoid, abruptly contracted to base, 0.8-1.1 × 0.3-0.4 mm, stipe 0.1 mm, apex acute, tapering to slender beak formed of persistent style base, surfaces papillose. Fruiting summer-fall (Jul-Oct). Wet, often sandy shores and damp, disturbed soils; 0-1500 m; Ala., Ariz., Ark., Calif., Colo., Ill., Ind., Iowa, Kans., Ky., La., Mich., Minn., Mo., Mont., Nebr., N.H. (introduced-), N.Y. (introduced-), N.C., N.Dak., Ohio, Okla., Oreg., Pa. (introduced-), S.Dak., Tenn., Tex., Utah, Va., Wash., Wyo.; Mexico (Coahuila, Tamaulipas).
The Morton Arboretum
Annual herb with rhizomes and runners, tufted 10 - 40 cm tall Leaves: two to six, basal, alternate, 8 - 12 cm long, 1 - 2 mm wide, flat or V-shaped in cross-section, linear, parallel-veined, keeled beneath, with a sheathing base that encloses the stem. Inflorescence: consisting of terminal spikelet heads, subtended by spirally arranged leafy bracts. Bracts three to six, upright to ascending, unequal, 3 - 12 cm long, 1 - 2.5 mm wide, all or some much longer than the inflorescence, flat or V-shaped in cross-section. Rays (branches of inflorescence) one to three, 0.5 - 2 cm long. Spikelet heads 7 - 15 mm in diameter, hemispheric, dense, consisting of 25 to 50 spikelets. Flowers: minute, in the axil of a floral scale, lacking sepals and petals. Stamen one. Anthers about 0.5 mm long. Pistil one. Style two- or three-cleft. Fruit: a one-seeded achene, short-stalked, brown, about 1 mm long and 0.5 mm wide, broadly ellipsoid with a pointed apex and slender beak, contracted at base, bumpy. Seed with a thin, non-adherent wall. Culm: 10 - 40 cm long, 0.5 - 1 mm wide, roundly triangular in cross-section, solid. Spikelets: 3 - 7 mm long, 2 - 3 mm wide, strongly flattened, egg-shaped, subtended by two small bracts, with eight to twenty floral scales. Scales two-ranked, 1 - 2 mm long, 1 - 1.5 mm wide, egg- lance-shaped with a recurved-pointed apex, two-keeled basally, three-ribbed, lowest one empty.

Similar species: No information at this time.

Flowering: August to mid-September

Habitat and ecology: Rare in the Chicago Region. Found in ditches, mud flats, and other wet places.

Occurence in the Chicago region: native

Etymology: Cyperus is the ancient Greek word for sedge. Acuminatus means "tapering into a long point."

Author: The Morton Arboretum

Vascular plants of NE US and adjacent Canada
Tufted annual 0.5-4 dm; lvs few, all near the base, slender and ±elongate, 1-2(-3) mm wide; invol bracts 3-6, unequal, elongate, some or all much surpassing the infl; spikelets 3-7 mm, strongly flattened, 8-20(-40)-fld, borne in very dense, globose clusters on very short axes; scales 1.3-2 mm, ovate, bicarinate basally, strongly 3-nerved, otherwise subhyaline and cellular-reticulate, shortly recurved-acuminate at the tip; rachilla persistent, wingless; stamen 1; anthers 0.5-0.7 mm; achenes rather broadly trigonous, 0.6-1 mm. Streambanks and other wet, low places, tolerant of alkali; Ill. to N.D., Mo., Tex., and n. Mex., e. occasionally to O., Ky. and w. N.C., and w. irregularly to the Pacific.

Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.

©The New York Botanical Garden. All rights reserved. Used by permission.
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Cyperus acuminatus
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Cyperus acuminatus image
Max Licher  
Cyperus acuminatus image
Max Licher  
Cyperus acuminatus image
Paul Rothrock  
Cyperus acuminatus image
Max Licher  
Cyperus acuminatus image
Max Licher  
Cyperus acuminatus image
Max Licher  
Cyperus acuminatus image
Max Licher  
Cyperus acuminatus image
Max Licher  
Cyperus acuminatus image
Max Licher  
Cyperus acuminatus image
Morton Arboretum  
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