Cyperus flavicomus |
Cyperus surinamensis |
|
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white-edge flatsedge |
tropical flatsedge |
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Habit | Herbs, annual, cespitose or single-stemmed. | Herbs, annual or short-lived perennial, annuals cespitose; rhizomes absent. |
Culms | trigonous, easily compressed, 30–75 cm × 1–5 mm, basally soft, glabrous. |
2–6, trigonous, (10–)35–80 cm × 0.5–2(–4) mm, scabridulous with retrorse prickles (infrequently glabrous or rarely also with extrorse prickles). |
Leaves | 1–3, usually withered at anthesis, V-shaped, 5–35 cm × 2–8 mm. |
3–9, V-shaped, (12–)25–45(–65) cm × 2–10 mm; blades and bracts without cross ribs. |
Inflorescences | spikes loosely ovoid, 5–25 × 8–22 mm; rays (3–)5–11, 0.4–20 cm; 2d order rays occasionally present, 5–28 mm; bracts 3–7, horizontal to ascending at 30°, (2–)8–35 cm × (1–)4–10 mm. |
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. |
Spikelets | 6–60, linear to lanceoloid, 7–30 × 2–3 mm, margins appearing serrate; floral scales 6–24, loosely overlapping, light brown to reddish brown, with conspicuous clear border, medially greenish, 5–7-ribbed, ovate-obovate, (1.4–)1.7–2.3 × 1.4–2 mm, apex acute to obtuse. |
(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. |
Flowers | stamens 2–3; anthers 0.4 mm, connective apex reddish, to 0.1 mm; styles 0.1–0.3 mm; stigmas 0.7–1.5 mm. |
stamen 1; anthers 0.5 mm; styles 0.8–1.1 mm; stigmas 0.5 mm. |
Achenes | jet black to dark reddish brown, sessile, obovoid, broadly rounded, 1.2–1.6 × 0.6–1.1 mm, surfaces minutely punctate. |
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. |
Cyperus flavicomus |
Cyperus surinamensis |
|
Phenology | Fruiting summer–early fall. | Fruiting late spring–early fall. |
Habitat | Emergent shorelines, roadsides ditches, marshes | Moist sunny areas with disturbed soils |
Elevation | 0–200 m (0–700 ft) | 0–200 m (0–700 ft) |
Distribution |
AL; AZ; FL; GA; KY; LA; MO; MS; NC; NM; PA; SC; TX; VA; Mexico; Central America; South America; Asia; Africa [Introduced in North America]
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AL; AR; FL; GA; KS; LA; MS; OK; SC; TN; TX; Mexico; Central America; South America
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Discussion | Cyperus flavicomus has long been called C. albomarginatus (see G. C. Tucker 1994). The closely related (perhaps not distinct) C. macrostachyos Lamarck, a pantropical subspecies, has been reported from Central America; the relationship of the two species needs further study. Cyperus flavicomus has been introduced in New York; it has not persisted there (R. S. Mitchell and G. C. Tucker 1997). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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. 159. | FNA vol. 23, p. 153. |
Parent taxa | ||
Sibling taxa | ||
Synonyms | C. albomarginatus, C. albomarginatus var. sabulosus, C. sabulosus, Pycreus albomarginatus, Pycreus sabulosus | |
Name authority | Michaux: Fl. Bor.-Amer. 1: 27. (1803) | Rottbøll: Descr. Pl. Rar., 20. (1772) |
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