Cyperus schweinitzii

Torrey

Ann. Lyceum Nat. Hist. New York 3: 276. 1836.

Common names: Schweinitz’s flatsedge
Illustrated
Basionym: Cyperus alterniflorus Schweinitz 1824
Treatment appears in FNA Volume 23. Treatment on page 174. Mentioned on page 144, 145, 147, 175, 176.

Herbs, perennial, rhizomatous. Culms trigonous, (10–)20–50 cm × (0.6–)1–2 mm, glabrous or more often scabridulous, either in distal 1/2 or over entire length; basal sheaths, 1–3, light brown, 1–4 cm, papery. Leaves flat to V-shaped, (2–)20–35 cm × 2–6 mm, margins and keel minutely scabridulous; proximal leaves bladeless. Inflorescences: spikes ± umbellate to slenderly (infrequently broadly) ovoid, 10–25 × 7–16 mm; rays 3–5, 1.5–8(–15) cm; bracts 3–7, erect (or declined at most 25–30° from vertical), (2.5–)8–20(–25) cm × (0.5–)1.5–6 mm; rachilla ± deciduous, wingless. Spikelets (1–)5–10(–20), oblong to linear-oblong, quadrangular, 7–10(–18) × (2.8–)3.2–4(–4.5) mm; floral scales deciduous, (1–)5–10(–14), spreading, laterally stramineous or dull whitish, sometimes also red-spotted, medially green, laterally 2–3-ribbed, medially 3-ribbed, broadly ovate to oblong-ovate, (2.3–)2.8–3.2 × (2–)2.4–3.2 mm, apex broadly rounded, often clear-erose, cusp 0.1–0.4 mm in proximal scales, 0.3–1 mm in distal scales. Flowers: anthers 0.8–1.4 mm; styles 0.1–0.3 mm; stigmas 1.5–3 mm. Achenes light to dark brown or nearly black, broadly ellipsoid, infrequently obovoid, 2–2.4 × 0.9–1.4 mm, base cuneate to ± stipelike, apex obtuse to broadly rounded, surfaces papillose. 2n = 166.


Phenology: Fruiting late spring–early summer.
Habitat: Riverbanks, sand bars, lakeshores, sand dunes, sandy openings in woods
Elevation: 0–1000 m

Distribution

V23 291-distribution-map.jpg

Alta., Man., Ont., Que., Sask., Colo., Ill., Iowa, Ky., Mass., Mich., Minn., Mo., Mont., N.J., N.Mex., N.Y., Ohio, Okla., Pa., S.Dak., Tex., Utah, Wash., Wis., Wyo., Mexico (Coahuila).

Discussion

Cyperus schweinitzii is introduced, but not naturalized, in Massachusetts and Washington.

Selected References

None.

Lower Taxa

None.
... more about "Cyperus schweinitzii"
Gordon C. Tucker* +, Brian G. Marcks* +  and J. Richard Carter * +
Torrey +
Cyperus alterniflorus +
Schweinitz’s flatsedge +
Alta. +, Man. +, Ont. +, Que. +, Sask. +, Colo. +, Ill. +, Iowa +, Ky. +, Mass. +, Mich. +, Minn. +, Mo. +, Mont. +, N.J. +, N.Mex. +, N.Y. +, Ohio +, Okla. +, Pa. +, S.Dak. +, Tex. +, Utah +, Wash. +, Wis. +, Wyo. +  and Mexico (Coahuila). +
0–1000 m +
Riverbanks, sand bars, lakeshores, sand dunes, sandy openings in woods +
Fruiting late spring–early summer. +
Ann. Lyceum Nat. Hist. New York +
Illustrated +
Undefined subg. Chlorocyperus +, Cyperus subg. Mariscus +  and Undefined subg. Papyrus +
Cyperus schweinitzii +
Cyperus subg. Cyperus +
species +