Culms 1–3(5) m tall, to 1.5 cm thick, erect or nodding, finely ridged, nodes slightly raised, sheath scar large, internodes long, finely mottled, with light ring of wax below the nodes. Culm sheaths to 25 cm, basally glabrous distally appressed-hispid, persistent; auricles and oral setae lacking; blades 2–5 cm, erect, abaxially glabrous. Branches usually 1 per node with no basal buds or branches on that branch, reflexed, if rebranching then from more distal nodes. Leaf sheaths glabrous, edges membranous without ciliation, auricles small, erect, or absent; oral setae scarce, erect or lacking; ligule long, oblique, eroded, lightly pubescent; external ligule glabrous to finely ciliate; blades 15–35 cm long, 1.5–5 cm wide, glabrous or abaxially sporadically very shortly red-brown tomentose, light green to glaucous; adaxially dark green, glossy, glabrous; petiole glabrous. Spikelets 3.5–10 cm, narrowly cylindrical, curving, florets 5–20(–25). Lemma 1.2–1.5 cm, glabrous, often with a fine c. 2 mm mucros; palea nearly equaling the lemma, glabrous, keels finely cilate.
This species was once widely cultivated for arrows in Japan. No wild populations are known. It is now a widely cultivated ornamental species in most temperate areas of the world, where it forms a tough and effective screen, and has become naturalized in Europe, the eastern United States and British Columbia. A shorter cultivar with partially ventricose culms, ‘Tsutsumiana’ and cultivars with variegated leaves are also available.
In cooler climates P. japonica stays in a well-defined clump, but in warmer areas it can spread invasively.
Introduced to Europe from cultivation in Japan during the 19th Century, quickly becoming a well established component of public and suburban gardens.