Cyperus difformis |
Cyperus filiculmis |
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Asian flatsedge, smallflower umbrella sedge, variable flatsedge |
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Habit | Herbs, annual, cespitose. | Herbs, perennial, cespitose, bases cormose; rhizomes knotted, beaded. |
Culms | 1–15, trigonous, 7–30 cm × 1.2–2.5 mm, soft (flattened in pressing), glabrous. |
trigonous, 15–48 cm × 0.4–1 mm, glabrous. |
Leaves | 2–7, flat, (2–)7–22 cm × 2.2–4 mm. |
flat, 10–30 cm × 0.5–2 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. |
spikes rather densely ovoid, 1–3.5 cm; rays 0 (sometimes 1–4), 1–6 cm; rachis 1–4 mm; bracts 3–4, horizontal to slightly reflexed, flat, 6–25 cm; rachilla ± deciduous, wingless. |
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. |
25–60, compressed, oblong-lanceoloid, 5–12 × 2.2–3.5 mm; floral scales deciduous, 5–15, yellowish to yellowish brown, laterally 4–5-ribbed, oblong-ovate, 2.6–3.6 × 1.4–2 mm, margins loosely spreading or clasping achene. |
Flowers | stamens 1 or 2; anthers ovoid-ellipsoid, 0.1 mm, connective not prolonged; styles 0.1 mm; stigmas 0.1–0.3 mm. |
anthers 0.8–1 mm; styles 1 mm; stigmas 1.5–2.5 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. |
dark grayish brown, sessile, narrowly oblong, 1.8–2.2 × 0.5–0.8 mm, apex obtuse, apiculate, surfaces puncticulate. |
Cyperus difformis |
Cyperus filiculmis |
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Phenology | Fruiting summer. | Fruiting summer. |
Habitat | Disturbed, muddy soils, shallow waters | Well-drained, open roadsides, fields, pine barrens, dunes |
Elevation | 0–1000 m (0–3300 ft) | 0–200 m (0–700 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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AL; FL; GA; LA; MD; MS; NC; SC; TX; VA |
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.) |
Cyperus filiculmis has long been treated within a broader and more widely used concept of C. filiculmis (C. lupulinus); see B. G. Marcks (1974) (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 23, p. 156. | FNA vol. 23, p. 175. |
Parent taxa | Cyperaceae > Cyperus > subg. Pycnostachys | Cyperaceae > Cyperus > subg. Cyperus |
Sibling taxa | ||
Synonyms | C. lateriflorus | C. martindalei |
Name authority | Linnaeus: Cent. Pl. II, 6. (1756) | Vahl: Enum. Pl. 2: 328. (1805) |
Web links |