Cyperus difformis |
Cyperus dentatus |
|
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Asian flatsedge, smallflower umbrella sedge, variable flatsedge |
tooth flatsedge |
|
Habit | Herbs, annual, cespitose. | Herbs, perennial, cespitose, rhizomatous; stolons tuberiferous, 1–10 cm. |
Culms | 1–15, trigonous, 7–30 cm × 1.2–2.5 mm, soft (flattened in pressing), glabrous. |
trigonous, 8–50 cm × 1–3 mm. |
Leaves | 2–7, flat, (2–)7–22 cm × 2.2–4 mm. |
flat or V-shaped, 10–40 cm × 2–5 mm. |
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. |
heads digitate, 8–18 mm diam.; rays 4–9, 1–8 cm; 2d order rays 0.5–2 cm; bracts 3–5, ± horizontal, flat, 1–20 cm × 1–4 mm. |
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. |
commonly proliferous, 2–6, linear to oblong, compressed, 3–24 × 2–2.5 mm; floral scales 3–20(–50), reddish brown, laterally 1–3-ribbed, ovate, 2–2.5 × 1.5–2 mm. |
Flowers | stamens 1 or 2; anthers ovoid-ellipsoid, 0.1 mm, connective not prolonged; styles 0.1 mm; stigmas 0.1–0.3 mm. |
stamens 3; anthers 1.5 mm; styles 1 mm; stigmas 1.5 mm. |
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. |
reddish brown, sessile, obovoid, 0.8–1 × 0.4–0.5 mm, apex obtuse, scarcely apiculate, surfaces glabrous. |
Cyperus difformis |
Cyperus dentatus |
|
Phenology | Fruiting summer. | Fruiting summer. |
Habitat | Disturbed, muddy soils, shallow waters | Emergent sandy, peaty, or gravelly shorelines |
Elevation | 0–1000 m (0–3300 ft) | 0–600 m (0–2000 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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CT; DC; DE; IN; MA; MD; ME; NC; NH; NY; PA; RI; SC; TN; VA; VT; NB; NS; ON; QC
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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.) |
The report of Cyperus dentatus from West Virginia (M. V. McGivney 1938) is erroneous; the cited specimen was from New Jersey (Gutenberg s.n. 1886, US) (M. Strong, pers. comm.). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 23, p. 156. | FNA vol. 23, p. 151. |
Parent taxa | Cyperaceae > Cyperus > subg. Pycnostachys | Cyperaceae > Cyperus > subg. Pycnostachys |
Sibling taxa | ||
Synonyms | C. lateriflorus | |
Name authority | Linnaeus: Cent. Pl. II, 6. (1756) | Torrey: Fl. N. Middle United States 1: 61. (1824) |
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