Cyperus bipartitus |
Cyperus retroflexus |
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shining flatsedge, slender flatsedge |
one-flower flatsedge |
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Habit | Herbs, annual, densely cespitose, with fibrous roots. | Herbs, perennial, cespitose, rhizomatous. |
Culms | roundly trigonous, 3–25(–30) cm × 0.3–1.4 mm, glabrous. |
trigonous, basally tuberous-thickened, (5–)15–40(–80) cm × 1–2.5 mm, glabrous. |
Leaves | 1–3, V-shaped, 1–8 cm × 1–2 mm. |
flat to V-shaped, (5–)10–30(–60) cm × (0.5–)1–3(–4) mm. |
Inflorescences | spike 1, loosely ovoid, compressed, 7–14 × 9–14 mm; rays 1–4, to 2(–3) cm; bracts 2–3, horizontal to ascending at 30(–45)°, V-shaped to flat, 1–12 cm × 0.5–1.5 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 | 3–5(–8), flattened, oblong to oblong-lanceoloid, 8–18 × 2–2.6(–3) mm; floral scales (6–)10–26(–32), closely imbricate, laterally light to dark brown, medially light brown, laterally ribless, medially 2–3-ribbed, 2-keeled, oblong to ovate, 1.9–2.7 × 1.8–2.3 mm, apex obtuse. |
(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 | stamens 2–3; anthers 0.4–0.5 mm, connective not prolonged; styles 0.6–1 mm; stigmas 1–1.5 mm. |
anthers (0.3–)0.4–0.6 mm; styles 0.4–0.5 mm; stigmas 0.5–0.9 mm. |
Achenes | black, network of ridges forming isodiametric or square cells, sessile, obovoid to ovoid, 1–1.3(–1.5) × (0.6–)0.8 mm, apex apiculate, surfaces minutely punctate. |
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 bipartitus |
Cyperus retroflexus |
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Phenology | Fruiting summer. | Fruiting mid summer–early fall (Jul–Sep). |
Habitat | Emergent shorelines, ditches, puddles, often in disturbed places | Damp, disturbed soils, croplands |
Elevation | 0–1500 m (0–4900 ft) | 0–1000 m (0–3300 ft) |
Distribution |
AL; AR; AZ; CA; CO; CT; DC; DE; GA; IA; IL; IN; KS; KY; LA; MA; MD; ME; MI; MN; MO; MS; NC; ND; NE; NH; NJ; NM; NV; NY; OH; OK; OR; PA; RI; SC; SD; TN; TX; UT; VA; VT; WA; WI; WV; ON; QC; Mexico; Central America; South America
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AL; AR; AZ; MO; MS; NM; OK; TX; Mexico
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Discussion | 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.) |
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Source | FNA vol. 23, p. 161. | FNA vol. 23. |
Parent taxa | ||
Sibling taxa | ||
Synonyms | C. rivularis | C. uniflorus var. floribundus, C. uniflorus var. retroflexus, Mariscus uniflorus |
Name authority | Torrey: Ann. Lyceum Nat. Hist. New York 3: 257. (1836) | Buckley: Proc. Acad. Nat. Sci. Philadelphia. 14: 9. (1862) |
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