羽序灯心草 yu xu deng xin cao

Juncus tratangensis Satake.

Plants perennial, tufted, 15--33 cm tall. Rhizome short. Stems terete, ca. 1 mm in diam., striate. Basal leaves few, cauline leaves 2 or 3; leaf sheath auricles obtuse, membranous, free part ca. 0.3 mm; leaf blade linear (4--)7--17 cm, apex acute. Inflorescences cymose, much branched, plumelike, to 12 cm; involucral bract leaflike, 2.7--3.5 cm. Perianth segments lanceolate, center greenish, margin hyaline, apex acute or acuminate; outer segments 3--3.5 × ca. 1.2 mm; inner segments 3--3.2 × ca. 1.2 mm. Stamens 6; filaments 1--1.5 mm; anthers 1.3--2.2 mm. Style 1.7--2.6 mm; stigmas 1.7--3.2 mm. Capsule trigonous oblong, ca. 2.4 mm; beak ca. 1.8 mm. Seeds (immature) apparently not appendaged at both ends. Fl. Sep--Oct, fr. Oct--Nov.

Valley forests, slopes, bare soil or earthy banks near rivers; 2500--4000 m. Sichuan, Xizang, Yunnan [Bhutan, India, Nepal, Sikkim].

This species is readily distinguished from others by its plumelike, vegetatively reproductive partial inflorescences and by the long style and stigmas of the fertile flowers. Juncus tratangensis was described for the fertile form that grows intermingled with the sterile form. Juncus fimbristyloides Noltie (Edinburgh J. Bot. 55: 39. 1998), recently described from Yunnan, resembles J. ochraceus in its plumelike partial inflorescences but differs in having a single stem leaf and smaller sterile partial inflorescences, with fewer, smaller, acute bracts.