Cyperus flavescens |
Cyperus lupulinus |
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pale flatsedge, yellow flatsedge |
Great Plains flatsedge, slender sand sedge |
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Habit | Herbs, annual, cespitose. | Herbs, perennial, cespitose, bases cormose; rhizomes knotted, beaded. | ||||
Culms | trigonous, (2–)4–30 cm × 0.4–2 mm, glabrous. |
trigonous, (3–)10–50 cm × 0.4–1.2 mm, glabrous. |
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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. |
flat, 5–40 cm × 1–3.5 mm. |
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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. |
spikes rather densely ovoid to globose, 1.2–3.5 cm; rays 0 or 1–4, 1–6 cm; rachis 1–3.5 mm; bracts 2–4, horizontal to reflexed, flat, 6–25 cm; rachilla ± deciduous, wingless. |
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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. |
15–60, compressed, oblong-lanceoloid, (3–)6–22 × 2.5–4 mm; floral scales deciduous, 5–22, off-white to light reddish brown, laterally 3–5-ribbed, ovate-elliptic, 2.5–4 × 2–2.6 mm, margins loosely spreading or clasping achene, apex entire to mucronate, mucro 0.05–0.2 mm. |
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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. |
anthers 0.3–0.6 mm; styles 1 mm; stigmas 1–1.5 mm. |
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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. |
dark brown or black, sessile, oblong-ellipsoid to ellipsoid, 1.7–2.2 × 0.8–1.2 mm, apex obtuse, apiculate, surfaces puncticulate. |
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2n | = 166. |
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Cyperus flavescens |
Cyperus lupulinus |
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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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AR; CO; CT; DC; DE; GA; IA; ID; IL; IN; KS; KY; MA; MD; ME; MI; MN; MO; NC; NE; NH; NJ; NY; OH; OR; PA; RI; TN; TX; VA; VT; WI; WV; NB; NS; ON; QC
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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.) |
Subspecies 2 (2 in the flora). Cyperus lupulinus was studied in detail (B. G. Marcks 1974). Ranges of the two subspecies overlap somewhat. Cyperus lupulinus subsp. lupulinus is found chiefly in the Great Plains, and subsp. macilentus is centered in the Northeast. It is seldom difficult to assign specimens to subspecies. The hybrid of Cyperus lupulinus with C. schweinitzii is C. ×mesochorus Geise. It is occasionally encountered with the two parent species in the north-central states (Illinois, Indiana, Michigan, Minnesota, and Wisconsin) and has been recorded once from Quebec. The hybrid is similar in size to C. schweinitzii; it has fewer rays, inflorescence bracts 30–45º above horizontal, and floral scales with mucros 0.4–0.5 mm. (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. 176. | ||||
Parent taxa | Cyperaceae > Cyperus > subg. Pycreus | Cyperaceae > Cyperus > subg. Cyperus | ||||
Sibling taxa | ||||||
Subordinate taxa | ||||||
Synonyms | C. flavescens var. poiformis, C. poiformis, Pycreus flavescens | Scirpus lupulinus | ||||
Name authority | Linnaeus: Sp. Pl. 1: 46. (1753) | (Sprengel) Marcks: Trans. Wisconsin Acad. Sci. 62: 271. (1974) | ||||
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