Cyperus flavescens |
Cyperus |
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pale flatsedge, yellow flatsedge |
cyperus, flatsedge, galingale, nutsedge, umbrella-sedge |
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Habit | Herbs, annual, cespitose. | Herbs, perennial or less often annual, cespitose or not, rhizomatous, stoloniferous, rarely tuberous. | ||||||||||||||||
Culms | trigonous, (2–)4–30 cm × 0.4–2 mm, glabrous. |
solitary or not, trigonous or round, glabrous or scabridulous with extrorse or antrorse (rarely retrorse) prickles. |
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Leaves | 1–5, (blades often absent, base of culm with 1 reddish sheath bearing minute blade tooth 1–2 mm), (3–)10–18 cm × (0.5–)1.5–2(–2.6) mm. |
usually basal; ligules absent; blades keeled abaxially, flat, V-, or inversely W-shaped in cross section. |
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Inflorescences | spikes 1–3, ovoid or ± digitate, 10–30 × 8–26 mm; rays 1–4(–6), 0.5–3(–9) cm; bracts 2–3, approximately horizontal, 1–12 cm × 0.5–2.5 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. |
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Spikelets | 1–6, compressed, oblong-lanceoloid, 5–15 × (2–)2.3–2.8 mm; floral scales (4–)8–24, closely imbricate, laterally yellow to yellowish brown, margins light brown to clear, medially green, laterally ribless, medially 2–3-ribbed, 2-keeled basally, ovate, (1.5–)1.8–2.2 × 1.8 mm, apex obtuse. |
scales to 76, distichous, each subtending flower, cylindric to compressed, borne spicately or digitately at ends of rays (occasionally proliferous). |
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Flowers | stamens 3; anthers 0.4 mm, connectives not prolonged; styles 0.5–1 mm; stigmas 0.5–0.8 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. |
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Achenes | jet black to reddish brown, slightly stipitate, obovoid, 1–1.2 × 0.8 mm, apex apiculate, surface with network of rectangular longitudinally elongate cells and transverse undulations. |
biconvex, flattened, or trigonous. |
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Cyperus flavescens |
Cyperus |
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Phenology | Fruiting summer–early fall. | |||||||||||||||||
Habitat | Damp, often disturbed soils | |||||||||||||||||
Elevation | 0–800 m (0–2600 ft) | |||||||||||||||||
Distribution |
AL; AR; CA; DC; DE; FL; GA; IL; IN; KS; KY; LA; MA; MD; MI; MO; MS; NC; NJ; NY; OH; OK; PA; SC; TN; TX; VA; WV; ON; South America; West Indies; Eurasia; Africa
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Pantemperate and tropical |
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Discussion | North American populations have been distinguished as Cyperus flavescens var. poiformis; their taxonomic separation was not supported by M. L. Corcoran’s (1941) careful study. Plants of Mexico and Central America consistently have purplish rather than yellowish floral scales and may be recognized as C. flavescens var. piceus (Liebmann) Fernald (G. C. Tucker 1983, 1994). (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.) |
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Key |
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Source | FNA vol. 23, p. 162. | FNA vol. 23, p. 141. | ||||||||||||||||
Parent taxa | Cyperaceae > Cyperus > subg. Pycreus | Cyperaceae | ||||||||||||||||
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Synonyms | C. flavescens var. poiformis, C. poiformis, Pycreus flavescens | |||||||||||||||||
Name authority | Linnaeus: Sp. Pl. 1: 46. (1753) | Linnaeus: Sp. Pl. 1: 44. (1753): Gen. Pl. ed. 5, 26. (1754) | ||||||||||||||||
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