Cyperus schweinitzii |
Cyperus acuminatus |
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sand flatsedge, Schweinitz's flatsedge |
pale umbrella-sedge, sharp-point flatsedge, short flatsedge, short point cyperus, taper-tip cyperus, taper-tip flat sedge |
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Habit | Herbs, perennial, rhizomatous. | Herbs, annual, cespitose. |
Culms | trigonous, (10–)20–50 cm × (0.6–)1–2 mm, glabrous or more often scabridulous, either in distal 1/2 or over entire length; basal sheaths, 1–3, light brown, 1–4 cm, papery. |
roundly trigonous, (10–)20–30(–45) cm × 0.4–1.2 mm, distal 1/2 glabrous or infrequently scabridulous. |
Leaves | flat to V-shaped, (2–)20–35 cm × 2–6 mm, margins and keel minutely scabridulous; proximal leaves bladeless. |
2–6(–8), V-shaped or flat, 8–12(–16) cm × 1–2(–4) mm. |
Inflorescences | spikes ± umbellate to slenderly (infrequently broadly) ovoid, 10–25 × 7–16 mm; rays 3–5, 1.5–8(–15) cm; bracts 3–7, erect (or declined at most 25–30° from vertical), (2.5–)8–20(–25) cm × (0.5–)1.5–6 mm; rachilla ± deciduous, wingless. |
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 | (1–)5–10(–20), oblong to linear-oblong, quadrangular, 7–10(–18) × (2.8–)3.2–4(–4.5) mm; floral scales deciduous, (1–)5–10(–14), spreading, laterally stramineous or dull whitish, sometimes also red-spotted, medially green, laterally 2–3-ribbed, medially 3-ribbed, broadly ovate to oblong-ovate, (2.3–)2.8–3.2 × (2–)2.4–3.2 mm, apex broadly rounded, often clear-erose, cusp 0.1–0.4 mm in proximal scales, 0.3–1 mm in distal scales. |
(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 | anthers 0.8–1.4 mm; styles 0.1–0.3 mm; stigmas 1.5–3 mm. |
stamen 1; anthers 0.5 mm; styles 0.8–1.1 mm; stigmas 0.5 mm. |
Achenes | light to dark brown or nearly black, broadly ellipsoid, infrequently obovoid, 2–2.4 × 0.9–1.4 mm, base cuneate to ± stipelike, apex obtuse to broadly rounded, surfaces papillose. |
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. |
2n | = 166. |
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Cyperus schweinitzii |
Cyperus acuminatus |
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Phenology | Fruiting late spring–early summer. | Fruiting summer–fall (Jul–Oct). |
Habitat | Riverbanks, sand bars, lakeshores, sand dunes, sandy openings in woods | Wet, often sandy shores and damp, disturbed soils |
Elevation | 0–1000 m (0–3300 ft) | 0–1500 m (0–4900 ft) |
Distribution |
CO; IA; IL; KY; MA; MI; MN; MO; MT; NJ; NM; NY; OH; OK; PA; SD; TX; UT; WA; WI; WY; AB; MB; ON; QC; SK; Mexico (Coahuila)
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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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Discussion | Cyperus schweinitzii is introduced, but not naturalized, in Massachusetts and Washington. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Cyperus acuminatus may be introduced in New Hampshire and New York. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 23, p. 174. | FNA vol. 23, p. 152. |
Parent taxa | Cyperaceae > Cyperus > subg. Cyperus | Cyperaceae > Cyperus > subg. Pycnostachys |
Sibling taxa | ||
Synonyms | C. alterniflorus | C. acuminatus var. cyrtolepis, C. cyrtolepis, C. cyrtolepis var. denticarinatus, C. rufescens var. denticarinatus |
Name authority | Torrey: Ann. Lyceum Nat. Hist. New York 3: 276. (1836) | Torrey & Hooker: Ann. Lyceum Nat. Hist. New York 3: 435. (1836) |
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