Herbs, perennial, internally mostly solid, without evident air cavities, cespitose or not, rhizomatous. Culms solitary or not, ± terete, tough, wiry. Leaves all basal; sheaths often disintegrating into fibers; ligules ciliate; blades strongly C-shaped in cross section to subcylindric, tough, wiry. Inflorescences terminal, often pseudolateral, capitate; spikelets 1–6(–10); involucral bracts 1–3, spreading or erect, leaflike. Spikelets 5–20 × 3–5 mm; scales 30–60, spirally arranged, each subtending flower, smooth, glabrous, margins ciliolate. Flowers bisexual; perianth of 1–6 bristles, straight, not longer than achene, retrorsely spinulose; stamens 3; styles deciduous, linear, 2-fid. Achenes plano-convex or unequally biconvex.
|[Greek amphi-, doubtful, ambiguous, and Latin scirpus, bulrush]|