T: [Japan] Nippon, in montibus Hakone, P.A.L.Savatier 1355; syn: P; [Japan] circa Yokoska, P.A.L.Savatier 2521; syn: P.
Perennials, c. 20–40 cm tall, caespitose to loosely caespitose; rhizome short, ascending; stolons short, ascending. Cataphylls 0–2, often with a developed blade, reddish brown. Cauline leaves 2–4, terete or slightly compressed, unitubular, with ±obtuse apex, perfectly septate, to 12 cm long, 1–2 mm wide; auricles ±obtuse, scarious, c. 0.4–1.0 mm long. Lower bract reduced, c. 1–2 cm long, leaf-like, much shorter than inflorescence. Inflorescence rich, decompound to supradecompound, loose and diffuse, less often subdense; main branches suberect, of many (1–) 2–3 (–5)-flowered, sometimes subcontracted heads. Tepals unequal; inner tepals conspicuously longer, ±lanceolate, c. 2.0–2.4 mm long, acute to acuminate, with distinct membranous margins; outer tepals to 2.0 mm long, linear-lanceolate, greenish, often suffused pale purplish, later ±stramineous-brown. Stamens 3, shorter than or equalling tepals; anthers c. 0.4–0.5 mm long; filaments 0.8–1.3 mm long; style c. 0.3–0.5 mm long, difficult to distinguish from rostrum apex; stigmas c. 0.6–1.0 mm long. Capsule unilocular, narrowly oblong-ovoid, acutely trigonous, c. 3.2–4.0 mm long, acuminate, with a c. 0.3–0.5 mm rostrum, thin-walled, pale brownish stramineous, ±shiny, much exceeding perianth. Seeds ellipsoid, apiculate, c. 0.5 × 0.2 mm, pale brown, longitudinally c. 16–20-striate, transversally reticulate; appendages absent.