Perennials, 25–100 (–250) cm tall; rhizome sparsely branching with mostly 5–10 mm long nodes. Stem leafless, 1–10 mm thick, bluish green, smooth or when dry inconspicuously 30–70-striate, lacking subepidermal sclerenchyma strands; epidermis cells uniform; bundles in three variously well defined rows, rarely interspaced with lacunar tubes; pith continuous, rarely finely interrupted (subsp. andicola), initially of astericiform cells, later irregular, arachnoid. Cataphylls 3–6; upper cataphylls 3–30 cm, stramineous to light brown, mostly with no or short awn-like blade but in some American races with one or rarely two well developed blades. Inflorescence pseudolateral, diffuse, (5–) 25–66 (–80)-flowered. Lower bract considerably exceeding inflorescence, 1/5–1/3 as long as stem; flowers bracteolate. Tepals 3.2–5 mm long, subequal, obtuse to apiculate, light to dark brown with broad scarious margin. Stamens 6; anthers 0.8–l.5 mm long, 1.5–2 (–6) times as long as filaments. Style 0.8–1 mm long; stigmas 1.5–2 mm long. Capsule 3–4.5 mm long, equalling or slightly exceeding perianth, trigono-ovoidal, with mucro 0.2–0.3 mm long, unilocular, triseptate, usually light brown, shining. Seeds 0.8–1 × 0.4 mm, ovoid, faintly striate-reticulate, with two inconspicuous appendages.