Cyperus surinamensis |
Cyperus subg. Pycnostachys |
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tropical flatsedge |
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Habit | Herbs, annual or short-lived perennial, annuals cespitose; rhizomes absent. | |
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). |
and leaves with non-Kranz anatomy (C3). |
Leaves | 3–9, V-shaped, (12–)25–45(–65) cm × 2–10 mm; blades and bracts without cross ribs. |
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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; rachilla persistent, wingless. |
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. |
borne in digitate clusters (rarely singly) or in umbellate or glomerulate heads; floral scales deciduous, 2-keeled or folded (conduplicate). |
Flowers | stamen 1; anthers 0.5 mm; styles 0.8–1.1 mm; stigmas 0.5 mm. |
stamens 1–3; stigmas 3. |
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. |
trigonous, plano-convex, or terete. |
Cyperus surinamensis |
Cyperus subg. Pycnostachys |
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Phenology | Fruiting late spring–early fall. | |
Habitat | Moist sunny areas with disturbed soils | |
Elevation | 0–200 m (0–700 ft) | |
Distribution |
AL; AR; FL; GA; KS; LA; MS; OK; SC; TN; TX; Mexico; Central America; South America
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Worldwide |
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.) |
Species ca. 150 (22 in the flora). The greatest species diversity of Cyperus subg. Pycnostachys is found in the lowland forests of Central America, South America, Africa, and Malesia. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 23, p. 153. | FNA vol. 23. |
Parent taxa | Cyperaceae > Cyperus > subg. Pycnostachys | Cyperaceae > Cyperus |
Sibling taxa | ||
Subordinate taxa | ||
Synonyms | C. subg. Protocyperus | |
Name authority | Rottbøll: Descr. Pl. Rar., 20. (1772) | C. B. Clarke: in J. D. Hooker, Fl. Brit. India 6: 597. (1893) |
Web links |