Cyperus surinamensis |
Cyperus grayi |
|
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tropical flatsedge |
Gray's flatsedge, Gray's sedge |
|
Habit | Herbs, annual or short-lived perennial, annuals cespitose; rhizomes absent. | Herbs, perennial, cespitose, rhizomatous. |
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). |
basally cormlike, trigonous, 5–40 cm × 0.5–1.3 mm, glabrous. |
Leaves | 3–9, V-shaped, (12–)25–45(–65) cm × 2–10 mm; blades and bracts without cross ribs. |
V-shaped, 5–25 cm × 1–3 mm, slightly minutely scabridulous abaxially on margins, midrib. |
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 loosely ± globose, 6–20 mm wide; rays 1–8 cm; rachis 1–4 mm; bracts 3–8, ascending, V-shaped, 3–20 cm × 1–3 mm; rachilla deciduous, wings hyaline, 0.6 mm wide. |
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. |
3–18(–28), oblong-lanceoloid, compressed, 3–12 × 1.8–2.5 mm; floral scales deciduous, 2–11, yellowish brown to reddish brown, laterally 3–4-ribbed, ovate, 2–2.8 × 1.6–2.2 mm, apex mucronulate. |
Flowers | stamen 1; anthers 0.5 mm; styles 0.8–1.1 mm; stigmas 0.5 mm. |
anthers 0.7–1 mm; styles 0.4–0.6 mm; stigmas 1–2 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 brown, ± stipitate, ellipsoid, 1.5–2 × 0.7–1 mm, apex obtuse, apiculate surfaces glabrous or puncticulate. |
2n | = 166. |
|
Cyperus surinamensis |
Cyperus grayi |
|
Phenology | Fruiting late spring–early fall. | Fruiting summer. |
Habitat | Moist sunny areas with disturbed soils | Coastal dunes, well-drained woods, railroad yards |
Elevation | 0–200 m (0–700 ft) | 0–200 m (0–700 ft) |
Distribution |
AL; AR; FL; GA; KS; LA; MS; OK; SC; TN; TX; Mexico; Central America; South America
|
CT; DE; GA; MA; MD; NC; NH; NJ; NY; PA; RI; SC; VA |
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. 179. |
Parent taxa | Cyperaceae > Cyperus > subg. Pycnostachys | Cyperaceae > Cyperus > subg. Cyperus |
Sibling taxa | ||
Synonyms | C. filiculmis var. grayi, C. filiculmis var. oblitus | |
Name authority | Rottbøll: Descr. Pl. Rar., 20. (1772) | Torrey: Ann. Lyceum Nat. Hist. New York 3: 268. (1836) |
Web links |