Vilfa pilifera Trinius, Gram. Unifl. Sesquifl. 157. 1824; Agrostis japonica Steudel; Sporobolus japonicus (Steudel) Maximowicz ex Rendle.

Annual. Culms tufted, slender, usually geniculate at base, 5–25 cm tall, branched. Leaf sheaths with long tubercle-based cilia; leaf blades narrowly lanceolate, flat or margins rolled when dry, 1.5–7 × 0.1–0.4 cm, thinly pilose on both surfaces, margins pectinate with long tubercle-based bristles especially near blade base; ligule ca. 0.5 mm. Panicle linear, spikelike, 1.5–8 × 0.3–0.7 cm; branches subverticillate, short, erect, mostly unbranched, spotted with small glands. Spikelets narrowly lanceolate-oblong, 2.4–3 mm, purplish brown; glumes acuminate; lower glume lanceolate, 1/2 spikelet length, veinless; upper glume oblong, as long as spikelet; lemma oblong, equaling upper glume, 1-veined or obscurely 3-veined, acute; palea equaling or shorter than lemma, broader, obtuse, easily splitting longitudinally. Anthers 3, ca. 0.5 mm. Grain red-brown, elliptic, 0.8–1.4 mm, slightly laterally compressed, apex rounded. Fl. and fr. Apr–Sep. 2n = 36, 40.

Open situations on moist ground, fields. Anhui, Jiangxi, Zhejiang [Bhutan, India, Japan, Korea, Malaysia, Nepal, Philippines; Africa].