Cyperus entrerianus |
Cyperus retroflexus |
|
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woodrush flatsedge |
one-flower flatsedge |
|
Habit | Herbs, perennial, coarse; rhizomes (seldom collected) indurate, oblique, 5–12 mm wide, with fibrous brown floral scales, 1–5 cm. | Herbs, perennial, cespitose, rhizomatous. |
Culms | 1–3, trigonous to roundly trigonous, (30–)40–65(–95) cm × (1–)2–3 mm. |
trigonous, basally tuberous-thickened, (5–)15–40(–80) cm × 1–2.5 mm, glabrous. |
Leaves | (1–)5–10, V-shaped, (10–)30–45(–70) cm × 3–7 mm. |
flat to V-shaped, (5–)10–30(–60) cm × (0.5–)1–3(–4) mm. |
Inflorescences | heads loosely to densely globose-ovoid, (6–)10–12(–20) mm diam.; rays 6–10(–12), 1–8(–12) cm; 2d order rays 1–4, 5–15(–23) mm; bracts (5–)6–8(–10), ascending at 45–60(–75)°, V-shaped, (5–)15–40(–55) cm × (1–)3–7 mm. |
spike 1, loosely to densely ovoid to cylindric, 8–36 × 8–20 mm; rays 3–6(–9), (5–)10–32 cm; bracts 3–6, horizontal to ascending at 30°, V-shaped, (1–)3–15(–30) cm × 0.5–4.5 mm; rachilla deciduous, wings 0.5–0.7 mm wide. |
Spikelets | (1–)30–50(–65), greenish white, linear to broadly ellipsoid, flattened, 4–6.5 × 1.8–3.2 mm; floral scales (10–)16–20(–26), laterally clear, pale green, off-white, or light brown, medially green or light brown, laterally weakly 1-ribbed, medially 2-ribbed, basally 2-keeled, oblong-lanceolate, (1.2–)1.4–1.6(–1.8) × (0.7–)0.8–1 mm, apex acute, mucronate, distally glabrous or scabridulous. |
(5–)20–35(–65), linear to oblong (without narrowed basal portion), quadrangular; (2.2–)4–10(–18) × 0.7–1.1 mm; floral scales persistent, 1–5, appressed, pale greenish white laterally, stramineous with reddish dots, or deep red, greenish or light brown medially, 3–6-ribbed laterally, narrowly ovate to oblong-elliptic, 2.6–3.9 × 1.6–2 mm, apex rounded to ± acute, entire, mucronulate; distal scale with glabrous midrib and mucro 0.1–0.3(–0.5) mm; sterile terminal scale of spikelet only 0.4–0.6 mm wide, involute, frequently uncinate. |
Flowers | stamen 1; anthers ellipsoid, 0.6–0.7 mm, connective apex acute, 0.1–0.2 mm; styles 0.2–0.4 mm; stigmas 0.4–0.6 mm. |
anthers (0.3–)0.4–0.6 mm; styles 0.4–0.5 mm; stigmas 0.5–0.9 mm. |
Achenes | brown, stipitate, ellipsoid to narrowly ellipsoid, broadly rounded or contracted basally, gradually tapered toward apex, 0.9–1.1 × 0.3–0.4 mm, stipe 0.1 mm, apex acute, surfaces finely reticulate. |
light brown to reddish brown, sessile or slightly stipitate, ellipsoid, (1.8–)2–2.4 × 0.6–0.8(–0.9) mm, apex slightly apiculate, surfaces puncticulate. |
Cyperus entrerianus |
Cyperus retroflexus |
|
Phenology | Fruiting summer. | Fruiting mid summer–early fall (Jul–Sep). |
Habitat | Roadside ditches, marshes | Damp, disturbed soils, croplands |
Elevation | 0–100 m (0–300 ft) | 0–1000 m (0–3300 ft) |
Distribution |
AL; FL; GA; LA; MS; TX; Mexico; South America; Central America (Nicaragua) [Introduced in North America]
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AL; AR; AZ; MO; MS; NM; OK; TX; Mexico
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Discussion | Cyperus entrerianus is a recent introduction in the southern United States (earliest collection from Pensacola County, Florida, Brinker 413, MO in 1941). It has been confused with C. luzulae. The species that Boeckeler had first described 50 years earlier was accepted by G. Kükenthal (1935–1936). Cyperus entrerianus was accepted as a variety of C. luzulae by A. B. Ayers (1946); M. F. Denton (1978b) considered C. entrerianus a synonym of C. luzulae, stating that the features of these two taxa merged so completely throughout their geographic ranges that C. entrerianus could not be given specific status. Cyperus luzulae in the strict sense does not extend northward to North America. Morphologic differences between Cyperus entrerianus and C. luzulae are as follows (G. C. Tucker 1994). Cyperus entrerianus has culms 40–75 cm; inflorescence bracts ascending at 45–60°; primary rays ascending at 45–60(–75)°; 2d order rays present; heads of spikelets loosely globose-ovoid, light greenish white to golden brown; rachilla dark red with stramineous scale scars; and scale apices acute. Cyperus luzulae has culms 20–40 cm; inflorescence bracts approximately horizontal; primary rays ascending at 15–30°; 2d order rays absent; heads of spikelets densely oblong to pyramidal, bright to dull white; rachilla green throughout; and scale apices rounded. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Cyperus retroflexus is distinguished from other species of Cyperus with deciduous spikelets by the involute, sterile terminal scale of the spikelet. In plants with cuspidate scales, the terminal scale is usually somewhat recurved, giving the appearance of a hook at the end of the spikelet. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 23. | FNA vol. 23. |
Parent taxa | Cyperaceae > Cyperus > subg. Pycnostachys | Cyperaceae > Cyperus > subg. Cyperus |
Sibling taxa | ||
Synonyms | C. luzulae var. entrerianus | C. uniflorus var. floribundus, C. uniflorus var. retroflexus, Mariscus uniflorus |
Name authority | Boeckeler: Flora 61: 139. (1878) | Buckley: Proc. Acad. Nat. Sci. Philadelphia. 14: 9. (1862) |
Web links |