Cyperus difformis |
Cyperus thyrsiflorus |
|
---|---|---|
Asian flatsedge, smallflower umbrella sedge, variable flatsedge |
southern flatsedge |
|
Habit | Herbs, annual, cespitose. | Herbs, perennial, rhizomatous. |
Culms | 1–15, trigonous, 7–30 cm × 1.2–2.5 mm, soft (flattened in pressing), glabrous. |
trigonous, (15–) 20–40(–65) cm × 0.5–1 mm, glabrous. |
Leaves | 2–7, flat, (2–)7–22 cm × 2.2–4 mm. |
V-shaped, (10–)20–40 cm × 0.8–2.8(–3) mm, glabrous. |
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. |
spike 1, densely oblong-cylindric, (15–)25–35(–40) × 12–18(–22) mm, (spikelets loosely spaced, 7–9 per 5 mm of rachis); rays (5–)6–8(–11), 0.5–4(–7.5) cm; bracts (4–)5–7(–8), ascending at 30º, (4–)10–30(–35) cm × (1–)2–4(–7) mm; rachilla deciduous, wings persistent, 0.4–0.5 mm wide. |
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. |
(20–)40–80(–100), linear, ± cylindric, scarcely compressed, (4.5–)6–9(–11) × (0.5–) 0.6–0.7(–1) mm; floral scales persistent, (1–)2–3(–4), appressed, medially green, laterally light brown to tawny or bronze, medially (1–)3-ribbed, laterally 3-ribbed, oblong, (2.6–)2.8–3.2(–3.4) × (1–)1.2(–1.4) mm, apex acute, mucronulate, mucro to 0.1(–0.2) 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. |
anthers 0.6–0.8 mm; styles (0.4–)0.6–1(–1.2) mm; stigmas persistent on achenes, prominently exserted from floral scales, (1.5–)2–3(–4) 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. |
brown to reddish brown, stipitate, narrowly oblong, 1.8–2.1 × (0.4–)0.5(–0.7) mm, stipe 0.1–0.2 × 0.1–0.2 mm, apex apiculate, acute, surfaces puncticulate. |
Cyperus difformis |
Cyperus thyrsiflorus |
|
Phenology | Fruiting summer. | Fruiting summer. |
Habitat | Disturbed, muddy soils, shallow waters | Dry, open woods |
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]
|
AL; FL; GA; LA; TX; Mexico; South America; West Indies |
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.) |
|
Source | FNA vol. 23, p. 156. | FNA vol. 23, p. 185. |
Parent taxa | Cyperaceae > Cyperus > subg. Pycnostachys | Cyperaceae > Cyperus > subg. Cyperus |
Sibling taxa | ||
Synonyms | C. lateriflorus | C. anceps, C. dissitiflorus, C. pallens, C. regiomontanus var. pallens, C. tribrachiatus, Mariscus dissitiflorus, Mariscus pallens, Mariscus tribrachiatus |
Name authority | Linnaeus: Cent. Pl. II, 6. (1756) | Junghuhn: Linnaea 6: 24. (1831) |
Web links |