Cyperus surinamensis |
Cyperus eragrostis |
|
---|---|---|
tropical flatsedge |
tall cyperus, tall flatsedge, tall nutgrass |
|
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). |
trigonous to terete, (25–)40–60(–90) cm, glabrous. |
Leaves | 3–9, V-shaped, (12–)25–45(–65) cm × 2–10 mm; blades and bracts without cross ribs. |
flat or V-shaped, (10–)25–50 cm × 5–8(–12) 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. |
heads globose, (10–)20–40 mm diam.; rays (0–)3–10, 2.5–5(–12) cm; 2d order rays usually absent (when present, 0.5–1.5 cm); bracts 4–8, horizontal to ascending at 15–30°, flat (or V-shaped), 3–30(–50) cm × 1.5–8(–12) mm. |
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. |
(20–)30–50(–70), oblong, compressed, 5–20 × 2.2–3 mm; floral scales (12–)20–30(–50), off-white to golden brown, basally 2-keeled, laterally ribless, ovate-deltate, 2–2.3 × 1–1.4 mm (declined 30–40º from rachilla). |
Flowers | stamen 1; anthers 0.5 mm; styles 0.8–1.1 mm; stigmas 0.5 mm. |
stamen 1; anthers 1–1.2 mm; styles 1–1.2 mm; stigmas 0.5 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. |
black or dark brown, stipitate, broadly ellipsoid, 1.2–1.4 × 0.5–0.6 mm, stipe to 0.1 mm, apex apiculate, beak 0.2–0.3 mm, surfaces puncticulate. |
Cyperus surinamensis |
Cyperus eragrostis |
|
Phenology | Fruiting late spring–early fall. | Fruiting summer. |
Habitat | Moist sunny areas with disturbed soils | Damp grasslands, roadsides ditches |
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
|
AL; CA; LA; MS; NJ; OR; PA; SC; TX; WA; BC; South America; naturalized; Europe
|
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.) |
The distributions of Cyperus eragrostis in British Columbia, Alabama, Pennsylvania, South Carolina, and Texas represent introduced populations. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 23, p. 153. | FNA vol. 23, p. 154. |
Parent taxa | Cyperaceae > Cyperus > subg. Pycnostachys | Cyperaceae > Cyperus > subg. Pycnostachys |
Sibling taxa | ||
Synonyms | C. vegetus | |
Name authority | Rottbøll: Descr. Pl. Rar., 20. (1772) | Lamarck: in J. Lamarck and J. Poiret, Tabl. Encycl. 1: 146. (1791) |
Web links |
|