扁茎灯心草 bian jing deng xin cao

Juncus compressus Jacquin var. gracillimus Buchenau in Engler, Pflanzenr. 25(IV. 36): 112. 1906.

Plants perennial, laxly tufted. Rhizome thick. Stems (8--)15--80 cm, usually slightly compressed. Cataphylls absent to 3. Basal leaves 1--3; leaf blade linear, 3--15 cm × 0.5--1 mm. Distal cauline leaves 1 or 2; leaf sheath auricles rounded, ca. 1 mm; leaf blade flat, 10--15(--20) mm. Inflorescences usually lax, many branched; branches unequal, longer ones 4--6 cm; involucral bract linear, often longer than inflorescence. Bracteoles present, broadly ovate, ca. 1 mm, margin scarious, apex obtuse. Perianth segments lanceolate to oblong-lanceolate, 1.8--2.6 × 0.9--1.1 mm, apex obtuse; outer segments slightly longer and narrower than inner ones, center greenish, margin broadly scarious. Stamens 6; filaments ca. 1 mm; anthers 0.8--1 mm. Ovary oblong. Style very short; stigmas ca. 1.5 mm. Capsule globose to ovoid, ca. 2.5 mm, apex obtuse and mucronate. Seeds obliquely ovoid, ca. 0.4 mm, striate. Fl. May--Jul, fr. Jun--Aug.

River banks, pool margins, marshes, wet grasslands, ridges; 500--1500 m. Gansu, Hebei, Heilongjiang, Henan, Jiangsu, Jiangxi, Jilin, Liaoning, Nei Mongol, Qinghai, Shandong, Shanxi [Japan, Korea, Mongolia, Pakistan, Russia; Europe].

Chinese records of Juncus compressus Jacquin (e.g., in FRPS) are referable to J. gracillimus.