Cyperus surinamensis |
Cyperus compressus |
|
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tropical flatsedge |
annual sedge, poorland flatsedge |
|
Habit | Herbs, annual or short-lived perennial, annuals cespitose; rhizomes absent. | Herbs, annual, cespitose with fibrous roots. |
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, (2–)6–15(–35) cm × (0.3–)1–1.8 mm, glabrous. |
Leaves | 3–9, V-shaped, (12–)25–45(–65) cm × 2–10 mm; blades and bracts without cross ribs. |
1–5, flat to V-shaped, (1–)5–15(–22) cm × (0.5–)1.5–3 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 ± digitate, ± globose, 7–40 × 10–20 mm; rays (0–)1–6, 2–12 cm; if absent, inflorescence a sessile cluster of (1–)3–10 spikelets; rachis 2–5 mm; bracts (1–)4–5(–6), ascending, V-shaped, 1–15(–20) cm × 0.5–3.5 mm; 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. |
(1–)3–12(–16), greenish white, linear to linear-lanceoloid, compressed-quadrangular, 6–34(–40) × 2–3(–3.6) mm; floral scales deciduous, (8–)16–36(–42), spreading, laterally whitish, greenish, or pale brownish, medially green, weakly 7–9-ribbed, laterally weakly 1–2-ribbed, most ribs medial, ovate, (2.4–)2.6–3 × (1.9–)2–2.4(–2.5) mm, apex acute to ± acute, cuspidate tip (0.3–)0.5–0.7(–0.8) mm. |
Flowers | stamen 1; anthers 0.5 mm; styles 0.8–1.1 mm; stigmas 0.5 mm. |
anthers 0.6–0.7 mm; styles 0.9–1.3 mm; stigmas 0.5–0.8 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, stipitate to sessile, obovoid, (1–)1.2–1.4(–1.5) × 0.9–1(–1.1) mm, apex obtuse to emarginate, surfaces very finely puncticulate. |
Cyperus surinamensis |
Cyperus compressus |
|
Phenology | Fruiting late spring–early fall. | Fruiting summer–early fall. |
Habitat | Moist sunny areas with disturbed soils | Various disturbed soils |
Elevation | 0–200 m (0–700 ft) | 0–900 m (0–3000 ft) |
Distribution |
AL; AR; FL; GA; KS; LA; MS; OK; SC; TN; TX; Mexico; Central America; South America
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AL; AR; DE; FL; GA; IL; LA; MD; MO; MS; NC; NY; OH; PA; SC; TX; VA; Mexico; Central America; South America; Asia; Africa
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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.) |
|
Source | FNA vol. 23, p. 153. | FNA vol. 23, p. 171. |
Parent taxa | Cyperaceae > Cyperus > subg. Pycnostachys | Cyperaceae > Cyperus > subg. Cyperus |
Sibling taxa | ||
Synonyms | C. compressus var. pectiniformis, C. pectinatus, C. pectiniformis | |
Name authority | Rottbøll: Descr. Pl. Rar., 20. (1772) | Linnaeus: Sp. Pl. 1: 46. (1753) |
Web links |