Cyperus cephalanthus

Torrey & Hooker

Ann. Lyceum Nat. Hist. New York. 3: 431. 1836.

Synonyms: Cyperus laetus var. cephalanthus (Torrey & Hooker) Kükenthal
Treatment appears in FNA Volume 23. Mentioned on page 180.

Herbs, perennial, rhizomatous. Culms trigonous, 40–70(–100) cm × 2–3 mm, scabrid or hirtellate, either immediately proximal to apex or over distal 1/2 of culm. Leaves flat, 30–80 cm × 4–10 mm, scabrid on margins, ribs on abaxial surface. Inflorescences: spikes ovoid, 12–20 × 13–18 mm; rays 3–6, 4–10(–16) cm, glabrous; bracts 3–5, ± horizontal to reflexed, 3–12(–36) cm × 0.4–3(–5) mm, scabrid like leaves; rachilla deciduous, essentially wingless or wings inconspicuous, hyaline, 0.1(–0.2) mm wide. Spikelets 25–50(–80), oblong, quadrangular-compressed, 5–10 × 2.5–3.5 mm; floral scales deciduous, 4–10(–14), marginally clear, laterally brownish to clear distally, or light brown or reddish brown, blunt, laterally 3(–4)-ribbed, ovate-lanceolate, 2.5–3 × (1.2–)1.4–2 mm, often erose apically, apex acute to obtuse, entire or emarginate. Flowers: anthers 0.4–0.6 mm; styles 0.8–1.2 mm; stigmas 2 mm. Achenes brown to reddish brown, ± stipitate, ellipsoid, 1.2 × 0.5–0.6 mm, apex obtuse, scarcely to distinctly apiculate, surfaces puncticulate.

Phenology: Fruiting summer.
Habitat: Wet prairies
Elevation: 0–50 m


V23 306-distribution-map.jpg

La., Okla., Tex., South America (Argentina, Brazil, Paraguay, Uruguay).


The combination of spreading floral scales and scabrid culms separates this rather uncommon species from any others occurring in its range. The scarcity of Cyperus cephalanthus in the United States and its disjunct distribution suggest it might be naturalized rather than native. It was collected early in the nineteenth century in Louisiana, and the amphitropical distribution is not without parallel in the genus (cf. 12. C. eragrostis).

Cyperus cephalanthus has been treated as a variety of the widespread, polymorphic South American C. laetus (G. Kükenthal 1935–1936). Recognition of C. cephalanthus as a species follows recent American floristic practice.

Selected References


Lower Taxa

... more about "Cyperus cephalanthus"
Gordon C. Tucker* +, Brian G. Marcks* +  and J. Richard Carter * +
Torrey & Hooker +
La. +, Okla. +, Tex. +, South America (Argentina +, Brazil +, Paraguay +  and Uruguay). +
0–50 m +
Wet prairies +
Fruiting summer. +
Ann. Lyceum Nat. Hist. New York. +
Illustrated +
Cyperus laetus var. cephalanthus +
Cyperus cephalanthus +
Cyperus subg. Cyperus +
species +