乳头灯心草 ru tou deng xin cao

Juncus nikkoensis Satake.

Plants perennial, 15--50 cm tall, usually papillose. Rhizome short. Stems terete, 1--2 mm in diam. Basal leaves 2 or 3, cauline leaves 2; leaf sheath auricles narrow; leaf blade terete, 3--10 cm × 1--2 mm, hollow, distinctly septate. Inflorescences terminal, compoundly branched; primary branches erect; involucral bract leaflike, often shorter than inflorescence; heads many, usually obconical, 2--4-flowered. Perianth segments narrowly lanceolate, ca. 2 mm, unequal with inner ones somewhat longer than outer, apex acute. Stamens 3; filaments 1.4--1.6 mm; anthers 0.5--0.8 mm. Capsule trigonous lanceolate, 3--3.5 mm, apex acuminate. Seeds obovoid to narrowly ellipsoid, ca. 0.5 mm, reticulate. Fl. Jul--Aug, fr. Jun--Sep.

Swampy meadows; 800--2000 m. Hebei, Heilongjiang, Henan, Jiangsu, Jilin, Liaoning, Nei Mongol, Shandong [Japan, Korea].