(Engelm.) Coville in N.L.Britton & A.Brown, Ill. Fl. N. U.S. , ed. 2, 1: 482 (1913)
Perennials, 30–100 cm tall, robust, caespitose. Rhizome short, stout, creeping. Stem terete, usually 4–7 mm in diam. near the base. Cataphylls 1–2, lax, stramineous, acute; basal leaves 1–2, 20–65 cm long. Cauline leaves 1–2, 20–65 cm long, reduced to 2.5 cm distally, terete, perfectly septate (septa conspicuous externally), unitubular; tip acuminate; sheaths loose; auricles 1.2–1.5 mm long, rounded, scarious. Lower bract herbaceous, green turning brown, terete, to 4 cm long, shorter than the inflorescence, erect to ascending; other bracts castaneous, narrowly ovate, 0.2–1.2 cm long. Inflorescence decompound, diffuse, ±loose, of 30–250 heads, usually 8–12 (–15) cm tall; main branches usually erecto-patent, some often ±patent; heads broadly obovoid to semiglobose, 2–10-flowered, 3–5 mm in diam. Tepals ±unequal, acuminate; outer tepals lanceolate, carinate with subulate apex, 1.9–2.5 mm long, stramineous; inner tepals flat, slightly shorter, 1.7–2.3 mm long. Stamens 3, not exserted; anthers 0.5–0.7 mm long; filaments 0.5–0.8 mm long; style to 0.1 mm long; stigmas 0.6–1 mm long. Capsules unilocular, narrowly ovoid, acute, 1.9–2.5 mm long, stramineous-brown, ±exceeding to equalling perianth. Seeds ellipsoid, 0.5–0.6 × 0.2 mm, pale brown, reticulate; appendages absent.