Juncus pseudocastaneus (Lingelsheim) Samuelsson; J. sikkimensis var. pseudocastaneus Lingelsheim.

Plants perennial, 10--25 cm tall. Rhizome creeping, densely branched, tufted. Stems borne singly, terete, slightly compressed, striate. Cataphylls shortly aristate. Basal leaf 1, sometimes with remnants of old leaves; leaf sheath auricles obtuse, free part ca. 0.3 × 0.7 mm; leaf blade subterete to slightly compressed, 7--14 cm × 1--3 mm, sometimes septate, apex obtuse to subacute. Inflorescences seemingly pseudolateral; involucral bract leaflike, ovate-lanceolate, 1.5--3.5 cm, base black-brown; heads usually 2(or 3), 2--5(--7)-flowered. Perianth segments blackish brown to chestnut brown, lanceolate; outer segments 4.5--8 × 1.8--3 mm, apex acuminate; inner segments slightly shorter than outer ones, margin broadly scarious, apex obtuse. Stamens 6; filaments 0.5--1.5 mm; anthers oblong, 2.2--4 mm. Style 2.5--3 mm; stigmas linear, 3--5.5 mm. Capsule chestnut brown at maturity, shiny, trigonous ovoid to trigonous ellipsoid, 4--5.9 mm, 3-septate, apex beaked; beak ca. 1 mm. Seeds oblong, 0.5--1 mm, both ends appendaged; appendages white, 0.8--1 mm. Fl. Jun--Oct, fr. Jul--Oct.

Forests, Rhododendron forests, wet grasslands on slopes, swamps, bogs, wet places by streams; 4000--4600 m. Gansu, Qinghai, Sichuan, Xizang, Yunnan [Bhutan, India, Nepal, Sikkim].