T: [Japan] Nippon media, ad Simoda, A.Franchet [P.A.Savatier, Pl. Jap.] 1357; lecto: P, designated here; iso: W; [Japan] Japonia, ad pedem montis Fudsi yama, P.A.Savatier 3477; residual syn: W.
Perennials, 20–35 (–40) cm tall, densely caespitose; rhizome short; stolons absent. Stems erect to ±ascending, compressed, winged, c. 3–5 (–6) mm wide. Basal 1–2 leaves cataphyllous, to c. 5–8 cm long. Cauline leaves (2–) 3–5, double-edged-compressed, ±winged, usually 9–20 cm long, (2–) 3–6 mm wide; sheaths broadly bordered membranous, dorsally acute; auricles obtuse, to c. 1 mm long, scarious; leaf apex acute; blade pluritubular, imperfectly septate. Lower bract leaf-like, 3–4 (–11) cm long, usually shorter than inflorescence; capitulum bracts ovate, scarious, to c. 2.5 mm long. Inflorescence loosely anthelate, decompound; branches suberect to erecto-patent, of c. (10–) 15–20 to many heads; heads greenish, semiglobose to cup-shaped, c. (3–) 5–7 (–9)-flowered, c. 5–7 mm wide. Tepals usually unequal, greenish with a narrow membranous margin; outer tepals ±shorter, acuminate, carinate, c. 2.7–3.2 mm long; inner tepals ±acute to acuminate, to c. 2.6–2.8 mm long, with a prominent midrib. Stamens 6; anthers 0.5–0.6 mm long; filaments thin, 0.9–1.1 mm long; style c. 0.1–0.2 mm long, difficult to distinguish from the capsule top; stigmas c. 0.6–1.3 mm long, erect to patent. Capsule unilocular, ±trigonous-prismatic, longer than perianth, c. 3.2–4.0 mm long; mucro short. Seeds ellipsoid-ovoid, c. 0.40–0.45 × c. 0.25 mm, apiculate, pale brown, distinctly reticulate, inter-reticulate areas square.