Herbs perennial; rhizomes to 200 cm. Culms to 25 cm apart, 1(-3) together, terete (scarcely compressed in drying), occasionally trigonous for apical 1/3, 40-140(-200) cm, 4-12 mm thick at base, (1.2-)1.5-2.5 mm thick at apex (with conspicuous transverse septa ca. 3 cm apart basally, to 3-5 mm apart apically), glabrous or infrequently scabrid on angles apically; sheaths at base of culm, 2-3, (5-)10-25 cm, loose, papery. Leaves usually bladeless, blades when present, cross ribs prominent, especially adaxially, (1-)10-20(-40) cm × 4-6(-9) mm. Inflorescences: spikes 1(-5), broadly ovoid to ± umbellate, 15-45 × 10-30 mm; rays 5-7(-10), 0.3-8(-12) cm; 2d order rays occasionally present, 5-20 mm; bracts 2(-4), erect, longest appearing to be continuation of culm, deltate to lance-linear, 0.2-2(-9) cm × 1.5-4.5 mm; rachilla persistent, wings translucent, whitish, or stramineous, 0.4 mm wide. Spikelets (1-)5-10, linear, compressed, 10-35(-45) × 1.1-2 mm; floral scales deciduous, 15-45, spreading or appressed, laterally light brown, medially green to brown, laterally 1-2-ribbed, medially 3-ribbed, oblong-elliptic to ovate, 2.9-3.7 × 1.1-1.6(-1.8) mm, apex acute. Flowers: anthers 1.7-2.4 mm; styles 1.2-3.6 mm; stigmas 1.7-6 mm. Achenes brown, stipitate, obovoid-ellipsoid, 1.2-1.6 × 0.4-0.6 mm, stipe 0.1 mm, apex markedly apiculate, surfaces puncticulate.

Fruiting summer. Marshes, shallow water, ditches; 0-100 m; Ala., Fla., Ga., La., Miss., S.C., Tex.; Mexico; Central America; South America; Asia; Africa.

In habit, Cyperus articulatus is reminscent of larger plants of Juncus or Schoenoplectus and is the only North American Cyperus with such a reedlike appearance.