Cyperus lanceolatus |
Cyperus rotundus |
|
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epiphytic flatsedge |
chaguan humatag, coco-grass, nutgrass, pakopako, purple nut-sedge |
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Habit | Herbs, perennial, cespitose, rhizomatous. | Herbs, perennial, stoloniferous; stolons (2–)5–12 cm × 1–2 mm, bearing tubers 3–8(–12) mm diam., wiry, springy when dried, indurate. |
Culms | trigonous, compressed, 15–75 cm × 0.5–3 mm, glabrous. |
trigonous, 10–35(–40) cm × 0.7–3.4 mm, basally indurate, glabrous. |
Leaves | 1–3, 5–30 cm × 1–2 mm. |
V-shaped to flanged V-shaped, 5–30 cm × 2–6 mm. |
Inflorescences | spikes 1(–2), ovoid, 5–23 × 9–21 mm; rays 2–3(–4), 0–15 mm; if rays absent, head single, compact, sessile, (12–)15–20 mm diam.; bracts 2–3, horizontal to vertical, 2–14 cm × 0.5–3.5 mm. |
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. |
Spikelets | 1–6, oblong-lanceoloid, 5–26 × 2–3 mm; floral scales 12–54, closely imbricate, laterally yellowish brown, medially pale brown, occasionally greenish, laterally 1-ribbed, medially 3-ribbed, distinctly 2-keeled basally, ovate, 1.8–2.6 × 1.4–1.7 mm, apex obtuse. |
(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. |
Flowers | stamens 2; anthers 0.4–0.5 mm, connectives not prolonged; styles 0.3–1 mm; stigmas 0.6–0.8(–1) mm. |
anthers 1–2.5 mm, styles 1.3–3.5 mm, stigmas (1.8–)2–3.3 mm. |
Achenes | brown, network of ridges forming isodiametric or square cells, stipitate, obovoid to ellipsoid, 1.1–1.3 × (0.5–)0.6 mm, apex acute to broadly rounded, surfaces minutely punctate or finely papillose. |
black, sessile, ellipsoid, abaxial face convex, adaxial face concave, 1.4–1.7(–1.9) × 0.8–1 mm, apex obtuse, surfaces puncticulate. |
Cyperus lanceolatus |
Cyperus rotundus |
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Phenology | Fruiting summer. | Fruiting summer–fall. |
Habitat | Marshes | Croplands, disturbed soils usually |
Elevation | 0–100 m (0–300 ft) | 0–400 m (0–1300 ft) |
Distribution |
AL; FL; GA; LA; TX; Mexico; Central America; South America; Africa
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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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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.) |
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Source | FNA vol. 23, p. 162. | FNA vol. 23, p. 169. |
Parent taxa | Cyperaceae > Cyperus > subg. Pycreus | Cyperaceae > Cyperus > subg. Cyperus |
Sibling taxa | ||
Synonyms | C. densus, C. humboldtianus, C. lanceolatus var. compositus, Pycreus densus | |
Name authority | Poiret: in J. Lamarck et al., Encycl. 7: 245. (1806) | Linnaeus: Sp. Pl. 1: 45. (1753) |
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