Cyperus prolixus |
Cyperus rotundus |
|
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mosquito flatsedge |
chaguan humatag, coco-grass, nutgrass, pakopako, purple nut-sedge |
|
Habit | Herbs, perennial; rhizomes 3–20 cm × 1–2 cm, indurate. | Herbs, perennial, stoloniferous; stolons (2–)5–12 cm × 1–2 mm, bearing tubers 3–8(–12) mm diam., wiry, springy when dried, indurate. |
Culms | stoutly trigonous, thickened, 50–300 cm × 5–30 mm, basally indurate, glabrous. |
trigonous, 10–35(–40) cm × 0.7–3.4 mm, basally indurate, glabrous. |
Leaves | V-shaped, with cross ribs, 40–130 cm × 10–15 mm, margins and keel scabrid. |
V-shaped to flanged V-shaped, 5–30 cm × 2–6 mm. |
Inflorescences | spikes appressed-ascending, narrowly cylindric, (2–)3–45 mm × (4–)7–10 mm; rays (5–)9–12, 2–22(–30) cm; 2d order rays distinctly flattened, 1–10 cm; 3d order rays flattened, 0.5–3 cm; rachis 2.5–4 cm; bracts (6–)9–10, ascending at 45–75°, V- or inversely W-shaped, (5–)15–90 cm × 0.5–20 mm; rachilla persistent, wings 0.2–0.4 mm wide. |
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 | (4–)10–35, appressed-ascending, compressed, linear, 7–12(–15) × 0.6–1.2 mm; floral scales deciduous, 6–20, marginally clear, laterally brown, medially green, laterally 2–3-ribbed, medially 1-ribbed, oblong-ovate, (3.2–) 3.8–4.3 × 1.2–1.7 mm, apex spreading, acute to obtuse, mucronulate. |
(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 | anthers 0.7–0.9 mm, connective apex bright red, oblong, to 0.1 mm; styles 0.8–1.3 mm; stigmas 2–3.3 mm. |
anthers 1–2.5 mm, styles 1.3–3.5 mm, stigmas (1.8–)2–3.3 mm. |
Achenes | brown, sessile, narrowly ellipsoid, 1.8–2.5 × 0.8–1.3 mm, apex ± acute, not apiculate, surfaces puncticulate. |
black, sessile, ellipsoid, abaxial face convex, adaxial face concave, 1.4–1.7(–1.9) × 0.8–1 mm, apex obtuse, surfaces puncticulate. |
Cyperus prolixus |
Cyperus rotundus |
|
Phenology | Fruiting summer. | Fruiting summer–fall. |
Habitat | Coastal marshes | Croplands, disturbed soils usually |
Elevation | 0–10 m [0–30 ft] | 0–400 m [0–1300 ft] |
Distribution |
LA; Mexico; Central America; South America |
AL; AR; AZ; CA; FL; GA; LA; MO; MS; NC; NM; SC; TN; TX; VA; Mexico; Central America; South America; Asia; Africa; Australia
|
Discussion | Cyperus prolixus produces large plants, similar in habit to C. giganteus and C. papyrus but easily distinguished by flattened rays. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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.) |
Source | FNA vol. 23, p. 167. | FNA vol. 23, p. 169. |
Parent taxa | ||
Sibling taxa | ||
Synonyms | C. amplissimus | |
Name authority | Kunth: in A. von Humboldt et al., Nov. Gen. Sp. 1: 206. (1816) | Linnaeus: Sp. Pl. 1: 45. (1753) |
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