Cyperus reflexus |
Cyperus lupulinus |
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bentawn flatsedge |
Great Plains flatsedge, slender sand sedge |
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Habit | Herbs, perennial, cespitose; rhizomes elongate, scaly, 2–3 mm wide. | Herbs, perennial, cespitose, bases cormose; rhizomes knotted, beaded. | ||||
Culms | roundly trigonous to terete, 30–80 cm × 1–1.6 mm, glabrous. |
trigonous, (3–)10–50 cm × 0.4–1.2 mm, glabrous. |
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Leaves | 1–6, 10–40 cm, glabrous or essentially so. |
flat, 5–40 cm × 1–3.5 mm. |
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Inflorescences | heads ovoid to pyramidal, 9–15 mm diam.; rays 0 or 3–6, 0.5–4 cm, glabrous; bracts 3–4, longest erect, appearing as continuation of culm, others horizontal to ascending, 4–17 cm × 1.5–4 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 | 25–60, reddish with contrasting yellowish or greenish edges, oblong-lanceoloid, strongly compressed, 5–6(–15) × 1.5–2.5 mm; floral scales 10–22, laterally reddish, medially yellowish green, 2-keeled, laterally strongly 1-ribbed on each side, proximally grooved, ovate-elliptic, 1.4–2.2 × 0.8–1.5 mm, apex acute, apically scabridulous (sometimes glabrous). |
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 | stamen 1; anthers 0.6–1 mm; styles 0.3–0.5 mm; stigmas 0.3–0.6 mm. |
anthers 0.3–0.6 mm; styles 1 mm; stigmas 1–1.5 mm. |
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Achenes | reddish brown, stipitate, ovoid-ellipsoid, 0.8–0.9 × 0.3–0.4 mm, stipe 0.1–0.2 mm, apex acute to acuminate, surfaces reticulate or subtly rugulose. |
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 reflexus |
Cyperus lupulinus |
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Phenology | Fruiting late spring–fall (May–Oct). | |||||
Habitat | Muddy soils or shallow waters | |||||
Elevation | 0–200 m (0–700 ft) | |||||
Distribution |
FL; LA; OK; TX; Mexico; Central America (Costa Rica) |
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 | Cyperus reflexus is recognized by its reddish scales with contrasting greenish or yellow keels and by the laterally 1ribbed scales. The lateral rib is most often situated where the reddish and yellowish parts of the scale meet. Two varieties of C. reflexus, var. reflexus and var. fraternus, have been recognized (M. F. Denton 1978b). Both varieties were noted as intermingled in the North American and South American segments of the widely disjunct range of C. reflexus. Such variation does not seem significant at the varietal level (see G. C. Tucker 1994; G. C. Tucker and R. McVaugh 1993). (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. | FNA vol. 23, p. 176. | ||||
Parent taxa | Cyperaceae > Cyperus > subg. Pycnostachys | Cyperaceae > Cyperus > subg. Cyperus | ||||
Sibling taxa | ||||||
Subordinate taxa | ||||||
Synonyms | C. arenicola, C. fraternus, C. pseudovegetus var. arenicola, C. reflexus var. fraternus | Scirpus lupulinus | ||||
Name authority | Vahl: Enum. Pl. 2: 299. (1805) | (Sprengel) Marcks: Trans. Wisconsin Acad. Sci. 62: 271. (1974) | ||||
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