Cyperus surinamensis |
Cyperus |
|||||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
tropical flatsedge |
cyperus, flatsedge, galingale, nutsedge, umbrella-sedge |
|||||||||||||||||
Habit | Herbs, annual or short-lived perennial, annuals cespitose; rhizomes absent. | Herbs, perennial or less often annual, cespitose or not, rhizomatous, stoloniferous, rarely tuberous. | ||||||||||||||||
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). |
solitary or not, trigonous or round, glabrous or scabridulous with extrorse or antrorse (rarely retrorse) prickles. |
||||||||||||||||
Leaves | 3–9, V-shaped, (12–)25–45(–65) cm × 2–10 mm; blades and bracts without cross ribs. |
usually basal; ligules absent; blades keeled abaxially, flat, V-, or inversely W-shaped in cross section. |
||||||||||||||||
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. |
terminal, rarely pseudolateral, 1st order subumbellate to capitate, 2d order with spicate or digitately arranged spikelets, rarely a solitary spikelet; spikelets 1–150; 1st order rays unequal (rarely equal) in length, produced singly from the axils of inflorescence bracts; involucral bracts 1–22, spirally arranged at culm apex, spreading to erect, leaflike. |
||||||||||||||||
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. |
scales to 76, distichous, each subtending flower, cylindric to compressed, borne spicately or digitately at ends of rays (occasionally proliferous). |
||||||||||||||||
Flowers | stamen 1; anthers 0.5 mm; styles 0.8–1.1 mm; stigmas 0.5 mm. |
bisexual [rarely unisexual], in axils of distichous floral scales, bases often decurrent onto rachilla as ± hyaline wings; perianth absent; stamens 1–3; styles linear, 2–3-fid, base deciduous or persistent; stigmas 2–3. |
||||||||||||||||
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. |
biconvex, flattened, or trigonous. |
||||||||||||||||
Cyperus surinamensis |
Cyperus |
|||||||||||||||||
Phenology | Fruiting late spring–early fall. | |||||||||||||||||
Habitat | Moist sunny areas with disturbed soils | |||||||||||||||||
Elevation | 0–200 m (0–700 ft) | |||||||||||||||||
Distribution |
AL; AR; FL; GA; KS; LA; MS; OK; SC; TN; TX; Mexico; Central America; South America
|
Pantemperate and tropical |
||||||||||||||||
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.) |
Species ca. 600 (96 in the flora). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
||||||||||||||||
Key |
|
|||||||||||||||||
Source | FNA vol. 23, p. 153. | FNA vol. 23, p. 141. | ||||||||||||||||
Parent taxa | Cyperaceae > Cyperus > subg. Pycnostachys | Cyperaceae | ||||||||||||||||
Sibling taxa | ||||||||||||||||||
Subordinate taxa | ||||||||||||||||||
Name authority | Rottbøll: Descr. Pl. Rar., 20. (1772) | Linnaeus: Sp. Pl. 1: 44. (1753): Gen. Pl. ed. 5, 26. (1754) | ||||||||||||||||
Web links |
|