Perennials, (5–) 15–30 (–65) cm tall, loosely caespitose; rhizome creeping, stoloniform, 1–2.5 mm in diam., without scales or with few light brown scales to 5 mm long, with nodes 1–5 cm long. Stem 0.7–2.0 mm in diam., terete; proximal internode sometimes elongated (separating leaf rosette from rhizome). Cataphylls 0–2 per stem, to 6.5 cm long, scarious to herbaceous, obtuse or mucronate. Cauline leaves basal or sub-basal or some inserted in lower 1/2 of stem, 4–20 cm long; blades terete, unitubular, 0.5–3.0 mm in diam., perfectly septate; sheaths 1.5–9 cm long; margins scarious; auricles 0.5–1.5 mm long, obtuse, scarious. Lower bract leaf-like or sheath-like, to 6 cm long, shorter than or ±equalling inflorescence; most distal bracts lanceolate, to 3.5 mm long, castaneous. Inflorescence compound, anthelate, of (1–) 2–8 (–11) semiglobose to subglobose (5–) 10–20 (–30)-flowered heads 7–12 (–14) mm in diam.; pedicels to 2 mm long, visible in the head; heads with protruding styles and capsule rostra. Tepals subequal (inner ones sometimes shorter), lanceolate, acute, 2.5–5.0 mm long, castaneous, paler towards base, sometimes pale brownish or dark brown; outer tepals carinate; inner tepals often distinctly 3-veined. Stamens 6; anthers 1.0–1.8 mm long, whitish; filaments flattened, to 0.5 mm long; style 1–3 mm long; stigmas 1–3 mm long. Capsule unilocular, obovoid to obclavate, trilobed at base, otherwise trigonous, 3–4 mm long, tapering into 1–2 mm rostrum, exceeding perianth, light to dark brown. Seeds ovoid, apiculate, 0.4–0.5 × 0.2–0.3 mm, brown, rugose; appendages absent. Fig. 95.
Widely distributed in Mexico and Guatemala, and probably disjunctly in the Andes from Peru to S Bolivia. 79: MXC, MXE, MXG, MXS, MXT. 80: GUA. 83: BOL, PER.
79. MEXICO CENTRAL: Distrito Federal, Valle de México, C.G.Pringle 6652 (BR, CM, F, G, GOET, K, M, MEXU, MO, NY, P, PH, S, UC, US, WU). MEXICO NORTHEAST: San Luis Potosí, Sierra de San Miguelito S of San Luis Potosí, F.W.Pennell 17713 (NY, PH, US). 80. GUATEMALA: San Marcos, Serchil, 3120 m, D.N.Smith 973 (AAU, F). 83. BOLIVIA: Cochabamba, M.Bang 1076 (G, GH, K, MO, NY, PH, US, WIS); Tarija, Tucumilla, 3000 m, K.Fiebrig 2640 (G, GH, L, M). PERU: Lima, Madean, Hortigal, 3600 m, J.Brandbyge 230 (AAU).
Grassy swales, meadows, along streams, on waterlogged or floody soils, above 1800 m.