Cyperus surinamensis |
Cyperus tetragonus |
|
---|---|---|
tropical flatsedge |
fourangle flatsedge |
|
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, (20–) 30–80 cm × 1–2.5 mm, glabrous or occasionally with scattered prickles on distal angles. |
Leaves | 3–9, V-shaped, (12–)25–45(–65) cm × 2–10 mm; blades and bracts without cross ribs. |
9–11, flat to slightly V-shaped, 25–80 cm × 3.5–10 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 (1–)3–6, loosely cylindric or oblong with parallel sides, 1.5–4 cm × 10–17 mm; rays 6–12, 2–25 cm, glabrous or rarely scabridulous proximal to spikes; bracts 6–11, ascending at 45°, flat, (1–)10–20(–26) cm × 1–10 mm; rachilla deciduous, wings persistent, 0.4–0.5 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. |
10–60, narrowly ellipsoid, quadrangular, 5–8 × 1.5–2 mm; floral scales persistent, (2–)3–7, appressed, clear at maturity, laterally reddish to purplish brown, medially greenish, often erose at maturity, laterally 3–5-ribbed, medially 3-ribbed, ovate-elliptic, 2.5–3.2 × 1.8–2.1 mm, apex obtuse. |
Flowers | stamen 1; anthers 0.5 mm; styles 0.8–1.1 mm; stigmas 0.5 mm. |
anthers 0.8–1 mm; styles 0.3–0.5 mm; stigmas 2–2.5 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. |
brown to reddish brown, sessile, oblong-ovoid to broadly ellipsoid, slightly dorsiventrally flattened, 1.8–2 × 0.7–0.8 mm, apex obtuse, apiculate, surfaces papillose to puncticulate. |
Cyperus surinamensis |
Cyperus tetragonus |
|
Phenology | Fruiting late spring–early fall. | Fruiting summer–fall (Jun–Nov). |
Habitat | Moist sunny areas with disturbed soils | Open woods, thickets, barrier islands |
Elevation | 0–200 m (0–700 ft) | 0–1000 m (0–3300 ft) |
Distribution |
AL; AR; FL; GA; KS; LA; MS; OK; SC; TN; TX; Mexico; Central America; South America
|
AL; AZ; FL; GA; MS; NC; NM
|
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 status of Cyperus pringlei from the southwestern United States requires further study. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 23, p. 153. | FNA vol. 23, p. 189. |
Parent taxa | Cyperaceae > Cyperus > subg. Pycnostachys | Cyperaceae > Cyperus > subg. Cyperus |
Sibling taxa | ||
Synonyms | C. pringlei, C. tetragonus var. pringlei, Mariscus tetragonus | |
Name authority | Rottbøll: Descr. Pl. Rar., 20. (1772) | Elliott: Sketch Bot. S. Carolina 1: 71. (1821) |
Web links |