Cyperus acuminatus |
Cyperus onerosus |
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pale umbrella-sedge, sharp-point flatsedge, short flatsedge, short point cyperus, taper-tip cyperus, taper-tip flat sedge |
plains flatsedge |
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Habit | Herbs, annual, cespitose. | Herbs, perennial, cespitose, rhizomatous; base cormlike; rhizomes scaly, 12 cm × 2 mm. |
Culms | roundly trigonous, (10–)20–30(–45) cm × 0.4–1.2 mm, distal 1/2 glabrous or infrequently scabridulous. |
trigonous, 20–55 cm × 1.2–11.8 mm, glabrous. |
Leaves | 2–6(–8), V-shaped or flat, 8–12(–16) cm × 1–2(–4) mm. |
V-shaped, 12–30 cm × 2–3 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. |
heads digitate, 12–20 mm diam.; rays 7–12, 1–13 cm; 2d order rays 1–3 cm (sometimes absent); bracts 3–5, longest ± erect, V-shaped, 5–12(–18) cm × 2–3 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. |
(8–)20–30, linear-lanceoloid, compressed, 5–10(–14) × 1.4–1.7 mm; floral scales (8–)16–26, laterally brown to reddish brown, medially green, laterally 1-ribbed, medially 3-ribbed, broadly elliptic, 2–2.5 × 1.2–1.6 mm, apex with slightly excurved cusp 0.2–0.3 mm. |
Flowers | stamen 1; anthers 0.5 mm; styles 0.8–1.1 mm; stigmas 0.5 mm. |
stamens 3; anthers 1 mm, connective apex reddish, subulate, 0.1 mm; styles 1–1.5 mm; stigmas 1.5 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. |
white to light brown, sessile, ellipsoid, 0.7–0.8 × 0.25–0.35 mm, apex obtuse, apiculate, surfaces puncticulate. |
Cyperus acuminatus |
Cyperus onerosus |
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Phenology | Fruiting summer–fall (Jul–Oct). | Fruiting early summer (May–Jun). |
Habitat | Wet, often sandy shores and damp, disturbed soils | Permanent pools and wet swales between sand dunes |
Elevation | 0–1500 m (0–4900 ft) | 1200 m (3900 ft) |
Distribution |
Mexico (Coahuila, Tamaulipas) [Ala., Ariz., Ark., Calif., Colo., Ill., Ind., Iowa, Kans., Ky., La., Mich., Minn., Mo., Mont., Nebr., N.H., N.Y., N.C., N.Dak., Ohio, Okla., Oreg., Pa. (introduced?), S.Dak., Tenn., Tex., Utah, Va., Wash., Wyo.]
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TX |
Discussion | Cyperus acuminatus may be introduced in New Hampshire and New York. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Of conservation concern. Cyperus onerosus is apparently restricted to Andrews and Winkler counties in Texas. This interesting endemic is most similar to Cyperus dentatus; it lacks tubers and apparently is not proliferous. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 23, p. 152. | FNA vol. 23, p. 151. |
Parent taxa | ||
Sibling taxa | ||
Synonyms | C. acuminatus var. cyrtolepis, C. cyrtolepis, C. cyrtolepis var. denticarinatus, C. rufescens var. denticarinatus | |
Name authority | Torrey & Hooker: Ann. Lyceum Nat. Hist. New York 3: 435. (1836) | M. C. Johnston: SouthW. Naturalist 9: 308. (1964) |
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