Cyperus difformis |
Cyperus |
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Asian flatsedge, smallflower umbrella sedge, variable flatsedge |
cyperus, flatsedge, galingale, nutsedge, umbrella-sedge |
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Habit | Herbs, annual, cespitose. | Herbs, perennial or less often annual, cespitose or not, rhizomatous, stoloniferous, rarely tuberous. | ||||||||||||||||
Culms | 1–15, trigonous, 7–30 cm × 1.2–2.5 mm, soft (flattened in pressing), glabrous. |
solitary or not, trigonous or round, glabrous or scabridulous with extrorse or antrorse (rarely retrorse) prickles. |
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Leaves | 2–7, flat, (2–)7–22 cm × 2.2–4 mm. |
usually basal; ligules absent; blades keeled abaxially, flat, V-, or inversely W-shaped in cross section. |
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Inflorescences | heads dense, 7–17 mm diam.; when rays short, heads sessile or nearly so, then densely irregularly lobate, 12–35 mm diam.; rays 1–5, 2–32 mm; bracts 2–4, longest bract erect or nearly so, appearing as continuation of culm, other bracts horizontal to ascending, 1–22 cm × 0.5–3.5 mm, margins and keel minutely scabridulous. |
terminal, rarely pseudolateral, 1st order subumbellate to capitate, 2d order with spicate or digitately arranged spikelets, rarely a solitary spikelet; spikelets 1–150; 1st order rays unequal (rarely equal) in length, produced singly from the axils of inflorescence bracts; involucral bracts 1–22, spirally arranged at culm apex, spreading to erect, leaflike. |
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Spikelets | 30–120, greenish brown to purplish brown, oblong-ellipsoid, compressed, (2–)3–5(–6) × 0.8–1.2 mm; floral scales (6–)12–20(–30), laterally clear margins, stramineous to deep purple, medially greenish, stramineous, or purplish, laterally ribless, medially 3-ribbed, obovate to orbiculate, 0.6–0.8 × 0.6–0.8 mm, apex mucronulate. |
scales to 76, distichous, each subtending flower, cylindric to compressed, borne spicately or digitately at ends of rays (occasionally proliferous). |
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Flowers | stamens 1 or 2; anthers ovoid-ellipsoid, 0.1 mm, connective not prolonged; styles 0.1 mm; stigmas 0.1–0.3 mm. |
bisexual [rarely unisexual], in axils of distichous floral scales, bases often decurrent onto rachilla as ± hyaline wings; perianth absent; stamens 1–3; styles linear, 2–3-fid, base deciduous or persistent; stigmas 2–3. |
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Achenes | light brown, obovoid-ellipsoid, 0.6–0.8 × 0.3–0.4 mm (as long as subtending scale), base cuneate, apex obtuse, apiculate, surfaces finely reticulate, papillose. |
biconvex, flattened, or trigonous. |
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Cyperus difformis |
Cyperus |
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Phenology | Fruiting summer. | |||||||||||||||||
Habitat | Disturbed, muddy soils, shallow waters | |||||||||||||||||
Elevation | 0–1000 m (0–3300 ft) | |||||||||||||||||
Distribution |
AL; AZ; CA; FL; GA; ID; KY; LA; MS; NC; NJ; NM; OR; PA; SC; TN; TX; VA; Mexico; South America; West Indies (Puerto Rico); Central America (Nicaragua, Panama); Eurasia; Indian Ocean Islands; Pacific Islands; Australia [Introduced in North America]
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Pantemperate and tropical |
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Discussion | Cyperus difformis is naturalized in the New World and native to the Old World, where it ranges from southern Europe to southern Africa and eastward to Southeast Asia and Australia. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Species ca. 600 (96 in the flora). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Key |
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Source | FNA vol. 23, p. 156. | FNA vol. 23, p. 141. | ||||||||||||||||
Parent taxa | Cyperaceae > Cyperus > subg. Pycnostachys | Cyperaceae | ||||||||||||||||
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Synonyms | C. lateriflorus | |||||||||||||||||
Name authority | Linnaeus: Cent. Pl. II, 6. (1756) | Linnaeus: Sp. Pl. 1: 44. (1753): Gen. Pl. ed. 5, 26. (1754) | ||||||||||||||||
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