单穗水蜈蚣 dan sui shui wu gong

Thryocephalon nemorale J. R. Forster & G. Forster, Char. Gen. Pl. 65. 1775.

Perennials. Rhizomes long creeping. Culms distant or laxly tufted, 10-40 cm tall, slender, compressed triquetrous, base not swollen. Leaves usually shorter than culm; sheath brown or purplish brown maculate, short, basalmost bladeless; leaf blade 2.5-4.5 mm wide, flat, flaccid, margin laxly dentate. Involucral bracts 3 or 4, leaflike, much longer than inflorescence. Spike 1(-3), ovoid to globose, 5-9 × 5-7 mm, with numerous spikelets. Spikelets subobovoid to narrowly ovoid-oblong, 2.5-3.5 × ca. 1.5 mm, compressed, 1-flowered. Glumes pale to straw-colored and rusty brown maculate, boat-shaped, 2.5-3.5 mm, keel wings narrow at basal part and ± broad from middle to apex, veins 3 or 4 on each side of keel, margin spinulose, apex slightly recurved mucronate. Stamens 3. Style long; stigmas 2. Nutlet brown, oblong to obovoid-oblong, ca. 1/2 as long as subtending glume, compressed plano-convex, densely puncticulate, apex shortly mucronate. Fl. and fr. May-Aug. 2n = 18.

Under shrubs or forests, meadows, swamps in valleys, mountain slopes, wet places along trails, field margins, river margins, ditch margins; 100-1400 m. Guangdong, Guangxi, Hainan, Hunan, Taiwan, Yunnan [Bhutan, Cambodia, India, Indonesia, Japan, Kashmir, Laos, Malaysia, Myanmar, Nepal, Pakistan, Papua New Guinea, Philippines, Sri Lanka, Thailand, Vietnam; tropical Africa, NE Australia, Indian Ocean islands, Madagascar, Pacific islands].

Kyllinga nemoralis is naturalized in tropical America.