Caustis

Rhizomatous perennials. Culms terete, striate, often bulbously thickened at base. Leaves reduced to sheaths along and at base of culm. Inflorescence as long as or longer than culms, occasionally functionally unisexual, with numerous 1-grooved to flattened branches, the ultimate spikelet-bearing branchlets elongating with maturity. Spikelets with 1 bisexual or female flower, often with a male below it; glumes 3–6, spirally arranged, usually puberulous on adaxial surface near apex; lower glumes empty, uppermost occasionally reduced or empty; perianth absent; stamens 3–6; style 3–5-fid; style-base narrow-conical to pyramidal, thick, hard, hispid at apex, smooth and shining below, persistent on nut. Nut trigonous to terete, readily deciduous, glabrous, with a narrow elongated neck between body of nut and style-base.