Description from Flora of China
Agrostis clavata subsp. matsumurae (Hackel ex Honda) Tateoka; A. clavata var. nukabo Ohwi; A. formosana Ohwi; A. matsumurae Hackel ex Honda.
Annual or short-lived perennial, loosely tufted. Culms erect or geniculate at base, slender, 30–70 cm tall, 2–4-noded. Leaf sheaths smooth; leaf blades linear, flat, thin, 6–15 cm × 1–5 mm, both surfaces scabrid; ligule 1.5–3 mm, back scabrid, apex obtuse or lacerate. Panicle lax, lanceolate to narrowly oblong in outline, 8–25 cm; branches 2–7 at each node, ascending, capillary, 8–15 cm, scabrid, bare in lower 1/3–1/2 or sometimes with spikelets from base. Spikelets 1.5–2.5 mm, yellowish green; glumes lanceolate, subequal, lower slightly longer, keeled, keels aculeate-scabrid, apex acuminate; callus glabrous or nearly so; lemma 2/3–3/4 spikelet length, awnless, apex obtuse; palea to 0.25 mm. Anthers 0.3–0.5 mm. Fl. and fr. summer and autumn.
Agrostis clavata is distinguished by the combination of scabrid leaves and panicle branches, small, pale green spikelets, acuminate glumes, an awnless lemma, and very small palea and anthers.
Agrostis clavata subsp. matsumurae (A. clavata var. nukabo) is often recognized, mainly on the basis of a dense, narrow panicle bearing spikelets from the base of the primary branches. In contrast, subsp. clavata has panicle branches divergent at flowering and bare in the lower 1/3–1/2. However, short, densely spiculate branches are often present at the panicle nodes among the longer, bare-based branches in subsp. clavata, contributing to a denser panicle appearance when frequent. All the panicle branches become erect in the fruiting stage, further blurring the boundary with subsp. matsumurae. It has not been possible to distinguish two subspecies satisfactorily in herbarium material.
Roadsides, riversides, forest margins, disturbed grassy places, often in moist situations; below 4000 m. Anhui, Fujian, Gansu, Guangdong, Guizhou, Hebei, Henan, Heilongjiang, Jilin, Nei Mongol, Shaanxi, Shandong, Sichuan, Taiwan, Xizang, Yunnan [Japan, Korea, Mongolia, Russia; SW Asia (Caucasus), N Europe, North America (Alaska)].