Cyperus rotundus |
Cyperus sanguinolentus |
|
---|---|---|
chaguan humatag, coco-grass, nutgrass, pakopako, purple nut-sedge |
purpleglume flatsedge |
|
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, perennial; rhizomes ± horizontal, to 12 cm × 0.8–1.2 mm. |
Culms | trigonous, 10–35(–40) cm × 0.7–3.4 mm, basally indurate, glabrous. |
± terete to roundly trigonous, 3–25(–60) cm × 0.3–2 mm, glabrous. |
Leaves | V-shaped to flanged V-shaped, 5–30 cm × 2–6 mm. |
1–3, V-shaped, 1–8(–15) cm × 1–2 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. |
spike 1, loosely ovoid, 7–14 × 8–20 mm; rays (0–)1–4, to 2(–3) cm; bracts 2–4, horizontal to ascending at 30(–45)°, V-shaped to flat, 1–8(–18) cm × 0.5–1.5(–2) mm. |
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. |
3–5(–14), oblong to linear-lanceoloid, 8–18 × 2–2.6(–3) mm; floral scales (6–)10–26(–32), laterally clear to light brown, sometimes with purplish margins, medially light brown, 2-keeled, laterally ribless, medially 2–3-ribbed, oblong to ovate, 1.9–2.2(–2.7) × 1.8–2.3 mm, apex obtuse. |
Flowers | anthers 1–2.5 mm, styles 1.3–3.5 mm, stigmas (1.8–)2–3.3 mm. |
stamens 3; anthers ellipsoid, 0.3–0.6 mm, connective not prolonged; styles 0.6–1 mm; stigmas 1–1.5 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, ± stipitate, obovoid to ovoid, 1–1.4 × 0.6–0.8 mm, apex truncate, apiculate, surfaces minutely punctate. |
Cyperus rotundus |
Cyperus sanguinolentus |
|
Phenology | Fruiting summer–fall. | Fruiting late summer–fall. |
Habitat | Croplands, disturbed soils usually | Emergent shorelines, ditches |
Elevation | 0–400 m (0–1300 ft) | 20 m (100 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
|
AL; GA; LA; MS; Asia; Africa [Introduced in North America] |
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.) |
Cyperus sanguinolentus is the only rhizomatous, distigmatic Cyperus in the eastern United States. An early collection from Louisiana was described as C. louisianensis, supposedly endemic. Recent field work and morphometric studies convincingly showed it to be an introduction of the Asian C. sanguinolentus) (J. R. Carter and C. T. Bryson 2001. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 23, p. 169. | FNA vol. 23, p. 161. |
Parent taxa | Cyperaceae > Cyperus > subg. Cyperus | Cyperaceae > Cyperus > subg. Pycreus |
Sibling taxa | ||
Synonyms | C. louisianensis, Pycreus sanguinolentus | |
Name authority | Linnaeus: Sp. Pl. 1: 45. (1753) | Vahl: Enum. Pl. 2: 351. (1805) |
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