Cyperus lupulinus |
Cyperus onerosus |
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Great Plains flatsedge, slender sand sedge |
plains flatsedge |
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Habit | Herbs, perennial, cespitose, bases cormose; rhizomes knotted, beaded. | Herbs, perennial, cespitose, rhizomatous; base cormlike; rhizomes scaly, 12 cm × 2 mm. | ||||
Culms | trigonous, (3–)10–50 cm × 0.4–1.2 mm, glabrous. |
trigonous, 20–55 cm × 1.2–11.8 mm, glabrous. |
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Leaves | flat, 5–40 cm × 1–3.5 mm. |
V-shaped, 12–30 cm × 2–3 mm. |
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Inflorescences | 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. |
heads digitate, 12–20 mm diam.; rays 7–12, 1–13 cm; 2d order rays 1–3 cm (sometimes absent); bracts 3–5, longest ± erect, V-shaped, 5–12(–18) cm × 2–3 mm. |
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Spikelets | 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. |
(8–)20–30, linear-lanceoloid, compressed, 5–10(–14) × 1.4–1.7 mm; floral scales (8–)16–26, laterally brown to reddish brown, medially green, laterally 1-ribbed, medially 3-ribbed, broadly elliptic, 2–2.5 × 1.2–1.6 mm, apex with slightly excurved cusp 0.2–0.3 mm. |
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Flowers | anthers 0.3–0.6 mm; styles 1 mm; stigmas 1–1.5 mm. |
stamens 3; anthers 1 mm, connective apex reddish, subulate, 0.1 mm; styles 1–1.5 mm; stigmas 1.5 mm. |
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Achenes | dark brown or black, sessile, oblong-ellipsoid to ellipsoid, 1.7–2.2 × 0.8–1.2 mm, apex obtuse, apiculate, surfaces puncticulate. |
white to light brown, sessile, ellipsoid, 0.7–0.8 × 0.25–0.35 mm, apex obtuse, apiculate, surfaces puncticulate. |
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2n | = 166. |
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Cyperus lupulinus |
Cyperus onerosus |
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Phenology | Fruiting early summer (May–Jun). | |||||
Habitat | Permanent pools and wet swales between sand dunes | |||||
Elevation | 1200 m (3900 ft) | |||||
Distribution |
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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TX |
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Discussion | 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.) |
Of conservation concern. Cyperus onerosus is apparently restricted to Andrews and Winkler counties in Texas. This interesting endemic is most similar to Cyperus dentatus; it lacks tubers and apparently is not proliferous. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Key |
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Source | FNA vol. 23, p. 176. | FNA vol. 23, p. 151. | ||||
Parent taxa | Cyperaceae > Cyperus > subg. Cyperus | Cyperaceae > Cyperus > subg. Pycnostachys | ||||
Sibling taxa | ||||||
Subordinate taxa | ||||||
Synonyms | Scirpus lupulinus | |||||
Name authority | (Sprengel) Marcks: Trans. Wisconsin Acad. Sci. 62: 271. (1974) | M. C. Johnston: SouthW. Naturalist 9: 308. (1964) | ||||
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