Cyperus difformis |
Cyperus odoratus |
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Asian flatsedge, smallflower umbrella sedge, variable flatsedge |
fragrant flatsedge, rusty flat sedge, scented sedge |
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Habit | Herbs, annual, cespitose. | Herbs, annual (or short-lived perennial). |
Culms | 1–15, trigonous, 7–30 cm × 1.2–2.5 mm, soft (flattened in pressing), glabrous. |
trigonous, (4–)10–50(–130) cm × (0.5–)1–4 mm. |
Leaves | 2–7, flat, (2–)7–22 cm × 2.2–4 mm. |
flanged V- or inversely W-shaped, 5–30(–60) cm × 4–12 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 1–5(–12), loosely to densely cylindric, ovoid, or ± pyramidal, 10–20(–40) × (8–)10–30(–35) mm; rays (0–2)6–9(–12), 2–8(–13) cm; if rays absent, infloresence a single dense, capitate cluster of closely imbricate spikes; bracts (4–)5–8(–10), horizontal to ascending at 30–60°, (3–)10–25(–55) cm × 1–14 mm; rachilla hyaline or thickened bronze, carmine, or yellowish, wings clasping achene. |
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. |
(10–)20–60(–100), linear-oblong to narrowly linear, cylindric to slightly flattened (when scale tips spreading), (5–)8–15(–38) × 0.8–1.3(–1.9) mm; floral scales (4–)8–12–(30), medially green, laterally reddish to stramineous to shiny brown or beige, medially 2–5-ribbed, laterally 1–3-ribbed, ovate to elliptic, (2–)2.2–2.8(–3.2) × (1.2–)1.4–1.6(–1.8) mm, apex entire or emarginate with mucro to 0.3 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 (0.2–)0.3–0.4(–0.7) mm; styles 0.4–0.7(–1) mm; stigmas (1–)1.5–3 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, reddish brown, or black, stipitate, narrowly ellipsoid to oblong (rarely obovoid-oblong), (1–)1.2–1.5(–1.9) × 0.5–0.6(–0.75) mm, stipe 0.1–0.2 mm, apex acute to barely obtuse, surfaces finely papillose. |
Cyperus difformis |
Cyperus odoratus |
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Phenology | Fruiting summer. | Fruiting summer–early fall. |
Habitat | Disturbed, muddy soils, shallow waters | Emergent shorelines, disturbed, muddy places, fresh or slightly brackish marshes |
Elevation | 0–1000 m (0–3300 ft) | 0–1500 m (0–4900 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; AR; AZ; CA; CO; CT; DC; DE; FL; GA; IA; IL; IN; KS; KY; LA; MA; MD; ME; MI; MN; MO; MS; NC; NE; NH; NJ; NM; NY; OH; OK; OR; PA; RI; SC; SD; TN; TX; VA; VT; WA; WI; WV; HI; ON; QC; Central America; South America; Asia; Africa; Australia
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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.) |
As circumscribed here, Cyperus odoratus is easily identified by its cylindric to subcylindric spikelets in which the corky rachilla of the mature spikelet disarticulates at the base of each scale. The mature spikelet breaks into segments each consisting of a scale and an internode of the rachilla clasping the achene with its corky wings. Cyperus odoratus is an exceedingly variable pantropical and warm-temperate species. Numerous segregates have been named, some of which may deserve recognition when the species is studied in detail worldwide. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 23, p. 156. | FNA vol. 23, p. 191. |
Parent taxa | Cyperaceae > Cyperus > subg. Pycnostachys | Cyperaceae > Cyperus > subg. Diclidium |
Sibling taxa | ||
Synonyms | C. lateriflorus | C. acicularis, C. californicus, C. eggersii, C. engelmannii, C. ferax, C. ferax subsp. engelmannii, C. ferax subsp. speciosus, C. ferruginescens, C. haenkei, C. huarmensis, C. macrocephalus, C. michauxianus, C. odoratus var. engelmannii, C. oxycarioides, C. speciosus, C. squarrosus var. parvus, Diclidium aciculare, Diclidium odoratum, Mariscus ferax, Mariscus huarmensis, Torulinium eggersii, Torulinium ferax, Torulinium macrocephalum, Torulinium michauxianum, Torulinium odoratum |
Name authority | Linnaeus: Cent. Pl. II, 6. (1756) | Linnaeus: Sp. Pl. 1: 46. (1753) |
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