Herbs, perennial, cespitose, rhizomatous. Culms trigonous, (20-) 30-80 cm × 1-2.5 mm, glabrous or occasionally with scattered prickles on distal angles. Leaves 9-11, flat to slightly V-shaped, 25-80 cm × 3.5-10 mm. Inflorescences: spikes (1-)3-6, loosely cylindric or oblong with parallel sides, 1.5-4 cm × 10-17 mm; rays 6-12, 2-25 cm, glabrous or rarely scabridulous proximal to spikes; bracts 6-11, ascending at 45°, flat, (1-)10-20(-26) cm × 1-10 mm; rachilla deciduous, wings persistent, 0.4-0.5 mm wide. Spikelets 10-60, narrowly ellipsoid, quadrangular, 5-8 × 1.5-2 mm; floral scales persistent, (2-)3-7, appressed, clear at maturity, laterally reddish to purplish brown, medially greenish, often erose at maturity, laterally 3-5-ribbed, medially 3-ribbed, ovate-elliptic, 2.5-3.2 × 1.8-2.1 mm, apex obtuse. Flowers: anthers 0.8-1 mm; styles 0.3-0.5 mm; stigmas 2-2.5 mm. Achenes brown to reddish brown, sessile, oblong-ovoid to broadly ellipsoid, slightly dorsiventrally flattened, 1.8-2 × 0.7-0.8 mm, apex obtuse, apiculate, surfaces papillose to puncticulate.

Fruiting summer-fall (Jun-Nov). Open woods, thickets, barrier islands; 0-1000 m; Ala., Ariz., Fla., Ga., Miss., N.Mex., N.C.

The status of Cyperus pringlei from the southwestern United States requires further study.

Common Name: fourangle flatsedge

Duration: Perennial

Nativity: Native

Lifeform: Graminoid

General: Tufted perennial from rhizomes, with trigonous stems 30-80 cm tall and 1-2.5 mm wide, generally glabrous.

Vegetative: Flat to slightly v-shaped leaves, 9-11, 25-80 cm long and 3.5-10 mm wide.

Inflorescence: Loosely cylindric to oblong spikes, usually 3-6, 1.5-4 cm tall by 10-17 mm wide, bearing 6-12 rays, these 2-25 cm and glabrous to scabridulous at base of spikes, 6-11 bracts, ascending, flat, 10-20 cm long and 1-10 mm wide, the rachilla deciduous with persistent wings less than 1 mm wide; 10-60 spikelets that are narrowly ellipsoid, quadrangular, 5-8 mm by 1.5-2 mm, the scales persistent, usually 3-7 and appressed, clear at maturity but laterally reddish to reddish brown, often erose at maturity, laterally 3-5 ribbed, ovate-elliptic, 2.5-3 mm by 1.8-2 mm, achenes brown to reddish brown, sessile, oblong-ovoid to broadly ellipsoid, dorsiventrally flattened, the surfaces papillose to puncticulate.

Ecology: Found in open woods and thickets below 5,000 ft (1524 m), flowers June-November.

Distribution: Ranges across the southern US, from Arizona to New Mexico, into the southeast and to Florida.

Notes: There remains some question about the status of Cyperus pringlei, which is the former name of this taxa.

Ethnobotany: Unknown

Etymology: Cyperus is from the Greek word meaning sedge, while tetragonus means four angled.

Synonyms: Cyperus pringlei, Cyperus tetragonus var. pringlei, Mariscus tetragonus

Editor: SBuckley 2012