Cyperus retroflexus |
Cyperus oxylepis |
|
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one-flower flatsedge |
sharpscale flatsedge |
|
Habit | Herbs, perennial, cespitose, rhizomatous. | Herbs, perennial, cespitose, coarse, (culms, leaves, bracts, and rays viscid). |
Culms | trigonous, basally tuberous-thickened, (5–)15–40(–80) cm × 1–2.5 mm, glabrous. |
roundly trigonous, 10–50 cm × 0.9–2.4 mm. |
Leaves | flat to V-shaped, (5–)10–30(–60) cm × (0.5–)1–3(–4) mm. |
adaxial face concave, becoming flat to trigonous apically, 10–46 cm × 1.5–4 mm, margins involute. |
Inflorescences | 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. |
spikes ovoid, 1–5.5 cm wide; rays usually 3–6, 0.5–5 cm, glabrous; sometimes absent in small plants; if absent, inflorescence a congested head of spikelets 1–3.5 cm diam.; 2d order rays 0–3, 1–3 cm; bracts 3–5, vertical to ascending at 45°, 2.5–25 cm × 1.2–4 mm, margins involute; 2d order bracts 0–2, 5–20 mm; rachilla persistent, wingless. |
Spikelets | (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. |
5–24, greenish yellow to golden brown, oblong to linear-lanceoloid, quadrangular, strongly compressed, 7–20(–30) × 2.5–4(–6) mm; floral scales 10–20(–40), spreading, pale green to stramineous, laterally 2–3-ribbed, ovate-lanceolate, 3.1–4 × 1.5–2.4 mm, apex with mucro 0.2–0.8 mm. |
Flowers | anthers (0.3–)0.4–0.6 mm; styles 0.4–0.5 mm; stigmas 0.5–0.9 mm. |
anthers 0.6–0.8 mm; styles 0.8–1.6 mm; stigmas 1–1.4 mm. |
Achenes | 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. |
light to dark brown, rarely somewhat reddish, stipitate, ellipsoid, 2–2.4 × 0.5–0.8 mm, base cuneate, stipe whitish, spongy, 0.2–0.3 × 0.2–0.4 mm, apex acute, persistent style forming beak 0.5–1.2 mm, surfaces glabrous or finely papillose. |
Cyperus retroflexus |
Cyperus oxylepis |
|
Phenology | Fruiting mid summer–early fall (Jul–Sep). | Fruiting summer. |
Habitat | Damp, disturbed soils, croplands | Ditches and disturbed places in marshes, often in saline soil |
Elevation | 0–1000 m (0–3300 ft) | 0–100 m (0–300 ft) |
Distribution |
AL; AR; AZ; MO; MS; NM; OK; TX; Mexico
|
AR; FL; GA; LA; MS; SC; TX; Mexico; South America [Introduced in North America]
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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.) |
Cyperus oxylepis is easily recognized by its sticky leaves, culms, and bracts (in living plants), involute leaves,and golden brown spikelets. The ovate-lanceolate floral scales and the ellipsoid, brownish achene with a persistent beak distinguish C. oxylepis from other species with deciduous floral scales. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 23. | FNA vol. 23, p. 171. |
Parent taxa | ||
Sibling taxa | ||
Synonyms | C. uniflorus var. floribundus, C. uniflorus var. retroflexus, Mariscus uniflorus | |
Name authority | Buckley: Proc. Acad. Nat. Sci. Philadelphia. 14: 9. (1862) | Nees ex Steudel: Syn. Pl. Glumac. 2: 25. (1855) |
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