Cyperus surinamensis |
Cyperus elegans |
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tropical flatsedge |
royal flatsedge, sticky flatsedge |
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Habit | Herbs, annual or short-lived perennial, annuals cespitose; rhizomes absent. | Herbs, perennial, cespitose, shortly rhizomatous, coarse, viscous. |
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). |
round to roundly trigonous, 15–80 cm × 2–4 mm, glabrous. |
Leaves | 3–9, V-shaped, (12–)25–45(–65) cm × 2–10 mm; blades and bracts without cross ribs. |
adaxial face concave, becoming trigonous apically, 15–75 cm × 1–4 mm, margins involute. |
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 ovoid, 10–20 mm wide; rays 3–8(–10), 0.5–12 cm; 2d order rays 0–3, 1–3 cm; bracts 3–7, horizontal to vertical, 2.5–5.5 cm × 1–4 mm, margins involute; 2d order bracts 0–3, 1–3 cm; 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. |
3–20(–30), beige to greenish or reddish brown, strongly compressed, oblong-ellipsoid to oblong-lanceoloid, 3–15 × 2.5–3.5 mm; floral scales deciduous, 6–22, laterally pale greenish white to stramineous or reddish brown, medially pale green to yellowish green, laterally 2-ribbed, medially 3–5-ribbed, broadly ovate, (2–)2.8–3.6 × 2.4–2.6 mm, apex with slightly excurved mucro 0.2–0.3 mm, apically scabrid. |
Flowers | stamen 1; anthers 0.5 mm; styles 0.8–1.1 mm; stigmas 0.5 mm. |
anthers 0.6–1.4 mm; styles 1.2–1.5 mm; stigmas 1–1.5(–3) 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. |
dark reddish brown to black, stipitate, obovoid, faces concave, flat or subtly convex, (1.4–)1.8–2 × 0.9–1 mm, base cuneate, stipe (sometimes absent) spongy, 0.1–0.2 × 0.2–0.4 mm, apex truncate, apiculate, surfaces coarsely papillose. |
Cyperus surinamensis |
Cyperus elegans |
|
Phenology | Fruiting late spring–early fall. | Fruiting summer. |
Habitat | Moist sunny areas with disturbed soils | Ditches, damp pastures, pond shores, riverbanks |
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
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FL; LA; NM; TX; Mexico; Central America; South America
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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.) |
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Source | FNA vol. 23, p. 153. | FNA vol. 23, p. 172. |
Parent taxa | Cyperaceae > Cyperus > subg. Pycnostachys | Cyperaceae > Cyperus > subg. Cyperus |
Sibling taxa | ||
Synonyms | C. trachynotus | |
Name authority | Rottbøll: Descr. Pl. Rar., 20. (1772) | Linnaeus: Sp. Pl. 1: 45. (1753) |
Web links |