Cyperus surinamensis |
Cyperus iria |
|
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tropical flatsedge |
rice-field flatsedge |
|
Habit | Herbs, annual or short-lived perennial, annuals cespitose; rhizomes absent. | Herbs, annual, cespitose. |
Culms | 2–6, trigonous, (10–)35–80 cm × 0.5–2(–4) mm, scabridulous with retrorse prickles (infrequently glabrous or rarely also with extrorse prickles). |
trigonous, (5–)20–60 cm × (0.2–) 0.6–2.4 mm, glabrous. |
Leaves | 3–9, V-shaped, (12–)25–45(–65) cm × 2–10 mm; blades and bracts without cross ribs. |
(1–)3–4, V-shaped, 15–40 cm × 3–6 mm. |
Inflorescences | heads umbellate, 10–20(–30) mm diam.; rays 4–12, 1–6 cm, minutely scabridulous with retrorse prickles; 2d order rays often present, 1–2(–3) cm; 3d order rays rarely present, 0.5–1.5 cm; bracts 3–8, approximately horizontal to ascending at 30°, V-shaped to flat, 2–15(–34) cm × 1–4(–5) mm. |
spikes 2–5(–8), oblong to ovoid, 2–10 cm × 3–12 mm; rays 4–8, to 11 cm; bracts (4–)5(–7), ascending at 45°, V-shaped, (1.5–)8–30(–50) cm × 1–6 mm; rachilla persistent, wingless (successive floral scales 0.7–0.9 mm apart). |
Spikelets | (6–)15–40(–65), greenish white, linear to linear-oblong, (3–)4–12(–15) × 1.5–2.5 mm; floral scales 10–50(–65), laterally pale yellow, light brown, or reddish brown, 2-keeled, medially 3-ribbed, lanceolate, 1–1.5 × 0.8–0.9 mm, distinctly reticulate, often scabridulous near apex. |
10–30, compressed, linear to ellipsoid, 4–20 × 1.5–2.1 mm; floral scales deciduous, (2–)6–26, laterally brown to golden brown, edges clear, medially green, 5-ribbed, outermost ribs more noticeable than others, obovate to nearly orbiculate, 1.3–1.8 × 1.2–1.8 mm, margins emarginate, apex with mucro 0.05–0.12 mm. |
Flowers | stamen 1; anthers 0.5 mm; styles 0.8–1.1 mm; stigmas 0.5 mm. |
stamens 2(–3); anthers (0.2–)0.3–0.4 mm, connective tips reddish, less than 0.1 mm; styles less than 0.1 mm; stigmas 0.2–0.4 mm. |
Achenes | brown to reddish brown, slightly stipitate, narrowly ellipsoid, 0.7–0.9 × 0.2–0.4 mm, apex apiculate, surfaces papillate or obscurely reticulate to rugulose. |
brown, slightly stipitate, obovoid, 1.2–1.4 × 0.5–0.7 mm, apex apiculate, surfaces puncticulate. |
Cyperus surinamensis |
Cyperus iria |
|
Phenology | Fruiting late spring–early fall. | Fruiting summer–fall (Jul–Oct). |
Habitat | Moist sunny areas with disturbed soils | Damp to moderately dry, disturbed soils |
Elevation | 0–200 m (0–700 ft) | 0–500 m (0–1600 ft) |
Distribution |
AL; AR; FL; GA; KS; LA; MS; OK; SC; TN; TX; Mexico; Central America; South America
|
AL; AR; CA; CT; FL; GA; IL; LA; MD; MO; MS; NC; NY; OK; SC; TN; TX; VA; WV; Mexico; Central America; South America; Asia; Africa; Australia [Introduced in North America]
|
Discussion | Cyperus surinamensis is distinguished readily from all other species of the genus in the New World by the usual presence of retrorse prickles on the culms and rays. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Cyperus iria was first recorded in the New World from the southeastern United States in the 1840s. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 23, p. 153. | FNA vol. 23, p. 166. |
Parent taxa | Cyperaceae > Cyperus > subg. Pycnostachys | Cyperaceae > Cyperus > subg. Cyperus |
Sibling taxa | ||
Name authority | Rottbøll: Descr. Pl. Rar., 20. (1772) | Linnaeus: Sp. Pl. 1: 45. (1753) |
Web links |