Cyperus aggregatus

(Willdenow) Endlicher

Cat. Horti Vindob. 1: 93. 1842.

Basionym: Mariscus aggregatus Willdenow Enum. Pl. 1: 70. 1809 Cyperus cayennensis (Lamarck) Britton 1907 Cyperus flavus (Vahl) Nees 1847
Synonyms: Cyperus flavus var. aggregatus (Willdenow) Kükenthal Cyperus flavus var. laevis Kükenthal Kyllinga cayennensis Baldwin Kyllinga squarrosa Vahl Mariscus flavus Kunth Mariscus laevis
Treatment appears in FNA Volume 23. Mentioned on page 188.

Herbs, perennial, cespitose, rhizomatous. Culms trigonous, 20–100 cm × 0.8–2.5 mm, glabrous. Leaves 5–10, V-shaped to flanged V-shaped, 10–70(–90) cm × 2–7 mm, margins and midribs scabridulous or glabrous. Inflorescences: spikes 1(–6), densely cylindric, 6–30 × 5–11 mm; rays 3–12, 0.4–5(–7) cm; rays and rachis glabrous; usually only 1–2 spikes of inflorescence on elongate rays, other spikes sessile or nearly so; bracts 4–7, horizontal to slightly ascending, 1–16 cm × 0.5–4 mm; rachilla deciduous, wings persistent, 0.5 mm wide. Spikelets 20–80, ellipsoid, roughly quadrangular, 3–5 × 1–1.4 mm; floral scales 1–2(–4), appressed, stramineous to golden brown, often red-speckled, medially greenish, 9-ribbed, elliptic to ovate, 2.4–3.4 × 1.8–2.6 mm, apex obtuse. Flowers: anthers 0.4–0.6 mm; styles 0.7–1.1 mm; stigmas 1.4–2.1 mm. Achenes dark brown to reddish brown, sessile, broadly ellipsoid, 1.8–2.1 × 0.8–1 mm, apex apiculate, surfaces glabrous to finely puncticulate.

Phenology: Fruiting mid summer–fall (Jul–Oct).
Habitat: Dry roadsides, pastures, thickets
Elevation: 0–500 m


V23 325-distribution-map.jpg

Introduced; Ariz., La., Miss., N.J., N.Mex., Oreg., Pa., Tex., Mexico, Central America, South America, Australia.


The records of Cyperus aggregatus in New Jersey, Oregon, and Pennsylvania represent introductions from ballast.

The closely related Mexican and Central American Cyperus regiomontanus Britton has been collected once as an adventive or waif in southern California. It is distinguished from C. aggregatus by its silvery green, subulate-lanceolate spikelets and achenes that are only 0.4–0.6 mm wide.

Selected References


Lower Taxa

... more about "Cyperus aggregatus"
Gordon C. Tucker* +, Brian G. Marcks* +  and J. Richard Carter * +
(Willdenow) Endlicher +
Mariscus aggregatus +, Cyperus cayennensis +  and Cyperus flavus +
Ariz. +, La. +, Miss. +, N.J. +, N.Mex. +, Oreg. +, Pa. +, Tex. +, Mexico +, Central America +, South America +  and Australia. +
0–500 m +
Dry roadsides, pastures, thickets +
Fruiting mid summer–fall (Jul–Oct). +
Cat. Horti Vindob. +
Illustrated +
Cyperus flavus var. aggregatus +, Cyperus flavus var. laevis +, Kyllinga cayennensis +, Kyllinga squarrosa +, Mariscus flavus +  and Mariscus laevis +
Cyperus aggregatus +
Cyperus subg. Cyperus +
species +