Arundinella rupestris A. Camus

This is a lowland, riverine species with tufts of wiry, many-noded culms. The lower leaf blades and upper part of the lower sheaths are often broken away, exposing the nodes.

Perennial, tufted, rhizomes absent, base with persistent papery sheaths. Culms very slender, erect or decumbent and rooting at base, 30–80 cm tall, ca. 1 mm in diam., 7–10-noded, nodes glabrous or pubescent. Leaf sheaths longer than internodes, thinly pilose, glabrescent, one margin ciliate, bearded at mouth; leaf blades linear or often involute, 5–20 cm × 2–5 mm, glabrous or adaxial surface thinly pilose, apex finely acuminate; ligule ca. 0.25 mm. Panicle loosely contracted, 7–15 cm; central axis and branches scabrid-hispidulous; branches narrowly ascending, 3–7 cm, loosely spiculate; pedicels scabrid. Spikelets 3.5–4 mm, yellowish green orpurplish; glumes glabrous, smooth or midvein scabrid; lower glume 2.5–3.5 mm, 3–5-veined; upper glume as long as spikelet, 5-veined; lower floret staminate, as long as lower glume; upper floret 2.5–3 mm, lemma apex 2-denticulate, awned; awn geniculate with brown twisted column, 2–5 mm; callus hairs 1/4–1/3 length of lemma. Fl. and fr. May–Oct.

Guangxi, Guizhou, Hunan [Thailand, Vietnam].

River banks, floodlands, rock fissures; 300–500 m.

Arundinella fluviatilis var. pachyathera Handel-Mazzetti; A. rupestris var. pachyathera (Handel-Mazzetti) B. S. Sun & Z. H. Hu.