Cyperus surinamensis |
Cyperus squarrosus |
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tropical flatsedge |
awn cyperus, awn flatsedge, bearded flatsedge |
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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). |
1–20, trigonous, 2–16 cm × 0.5–0.8 mm, glabrous. |
Leaves | 3–9, V-shaped, (12–)25–45(–65) cm × 2–10 mm; blades and bracts without cross ribs. |
1–3, flat to V-shaped, (1–)5–10(–15) × 0.5–2.5 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. |
spike 1, loosely to densely ovoid to oblong, 6–20(–40) × 9–15(–20) mm; rays absent or 1–3(–6), 4–40 mm; bracts (1–)2–4, longest ± erect, V-shaped, 1–15 cm × 0.5–3 mm; rachilla ± deciduous, 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. |
(2–)6–20(–40), greenish to reddish brown, somewhat compressed, ovoid-lanceoloid to oblong, 2.5–10(–20) × 1.3–2.2 mm (excluding awns); floral scales deciduous, (4–)10–20(–34), greenish to stramineous or brownish red laterally, greenish medially, (5–)7–9(–11)-ribbed nearly to margins, oblong-lanceolate, (1.2–)1.3–1.8(–2.2) × (0.5–)0.7–0.8(–1) mm, apex cuspidate, excurved awn additional 0.5–1(–1.3) mm. |
Flowers | stamen 1; anthers 0.5 mm; styles 0.8–1.1 mm; stigmas 0.5 mm. |
stamen 1, filaments 1.5 mm; anthers oblong, 0.2–0.3 mm, connective apex reddish, minute; styles 0.3–0.5 mm; stigmas 0.4–0.7 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. |
light brown to nearly black, stipitate, obovoid (occasionally linear-spatulate or linear oblong, infrequently constricted in middle), 0.7–0.8(–1.1) × (0.2–)0.3–0.4(–0.5) mm, stipe 0.05–0.1 × 0.1 mm, apex truncate, apiculate, surfaces papillose. |
Cyperus surinamensis |
Cyperus squarrosus |
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Phenology | Fruiting late spring–early fall. | Fruiting summer. |
Habitat | Moist sunny areas with disturbed soils | Moist, disturbed soils, gravelly roadsides, flood plains, edges of puddles, muddy places |
Elevation | 0–200 m (0–700 ft) | 0–2500 m (0–8200 ft) |
Distribution |
AL; AR; FL; GA; KS; LA; MS; OK; SC; TN; TX; Mexico; Central America; South America
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AL; AR; AZ; CA; CO; CT; DC; DE; FL; GA; IA; ID; IL; IN; KS; KY; LA; MA; MD; ME; MI; MN; MO; MS; MT; NC; ND; NE; NH; NJ; NM; NV; NY; OH; OK; OR; PA; RI; SC; SD; TN; TX; UT; VA; VT; WA; WI; WV; WY; AB; BC; MB; NB; ON; QC; Mexico; Central America; South America; West Indies; Bermuda; Eurasia; Africa; Atlantic Islands; Indian Ocean Islands; Pacific Islands; Australia
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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.) |
Cyperus squarrosus can be recognized by its small size and annual habit combined with its oblong-lanceolate floral scales bearing five to eleven conspicuous ribs and excurved awns. Some collections have been misidentified as C. acuminatus, an annual species of subg. Pycnostachys that has ovate-lanceolate, three-ribbed floral scales and digitately clustered spikelets. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 23, p. 153. | FNA vol. 23, p. 165. |
Parent taxa | Cyperaceae > Cyperus > subg. Pycnostachys | Cyperaceae > Cyperus > subg. Cyperus |
Sibling taxa | ||
Synonyms | Chlorocyperus inflexus, C. aristatus, C. aristatus var. inflexus, C. aristatus var. runyonii, C. inflexus, Dichostylis aristata, Mariscus squarrosus | |
Name authority | Rottbøll: Descr. Pl. Rar., 20. (1772) | Linnaeus: Cent. Pl. II, 6. (1756) |
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