Cyperus rotundus |
Cyperus odoratus |
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chaguan humatag, coco-grass, nutgrass, pakopako, purple nut-sedge |
fragrant flatsedge, rusty flat sedge, scented sedge |
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Habit | Herbs, perennial, stoloniferous; stolons (2–)5–12 cm × 1–2 mm, bearing tubers 3–8(–12) mm diam., wiry, springy when dried, indurate. | Herbs, annual (or short-lived perennial). |
Culms | trigonous, 10–35(–40) cm × 0.7–3.4 mm, basally indurate, glabrous. |
trigonous, (4–)10–50(–130) cm × (0.5–)1–4 mm. |
Leaves | V-shaped to flanged V-shaped, 5–30 cm × 2–6 mm. |
flanged V- or inversely W-shaped, 5–30(–60) cm × 4–12 mm. |
Inflorescences | spikes 1(–3), broadly ellipsoid, (12–)15–25(–30) × (12–)20–30(–50) mm, rays (3–)4–6(–7), 0.2–10 cm;, bracts (2–)3–5, horizontal to ascending at 45°, V-shaped to flanged V-shaped, 0.5–10 cm × 0.5–4 mm, rachilla persistent, wings 0.5–1 mm wide. |
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 | (2–)3–7(–12), compressed, linear, 4–40 × 1.3–1.8 mm, floral scales persistent, 6–36(–42), spreading or appressed, purple to reddish brown, with narrow clear border and green midrib, 7–9-ribbed, ovate, (1.8–)2.6–3.4 × 2.2–3 mm, apex obtuse. |
(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 | anthers 1–2.5 mm, styles 1.3–3.5 mm, stigmas (1.8–)2–3.3 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 | black, sessile, ellipsoid, abaxial face convex, adaxial face concave, 1.4–1.7(–1.9) × 0.8–1 mm, apex obtuse, surfaces puncticulate. |
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 rotundus |
Cyperus odoratus |
|
Phenology | Fruiting summer–fall. | Fruiting summer–early fall. |
Habitat | Croplands, disturbed soils usually | Emergent shorelines, disturbed, muddy places, fresh or slightly brackish marshes |
Elevation | 0–400 m (0–1300 ft) | 0–1500 m (0–4900 ft) |
Distribution |
AL; AR; AZ; CA; FL; GA; LA; MO; MS; NC; NM; SC; TN; TX; VA; Mexico; Central America; South America; Asia; Africa; Australia
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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 rotundus is documented in Connecticut, Delaware, New York, and Pennsylvania; there is no evidence of persistent populations. Cyperus esculentus and C. rotundus are the only two species of subg. Cyperus in the New World that produce tuberiferous stolons. The two species also have persistent floral scales and persistent rachillas, a combination of characteristics not found in any other New World species of Cyperus. Cyperus rotundus is distinguished from other species of the genus in the New World by its open spikes composed of linear reddish spikelets borne on a conspicuous slender rachis. Cyperus rotundus is usually acknowledged to be the world’s worst weed (cf. G. C. Tucker 1987). In the United States, it does not grow north of the mean 1°C January isotherm. Cyperus esculentus (preceding species) is a serious weed in much of the world, especially in cooler regions where the more tropical C. rotundus does not grow. Cyperus esculentus is able to tolerate lower air temperatures (as low as -18°C). The two species apparently differ also in their thermal optima for growth. (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. 169. | FNA vol. 23, p. 191. |
Parent taxa | Cyperaceae > Cyperus > subg. Cyperus | Cyperaceae > Cyperus > subg. Diclidium |
Sibling taxa | ||
Synonyms | 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: Sp. Pl. 1: 45. (1753) | Linnaeus: Sp. Pl. 1: 46. (1753) |
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