Culms 3–9 m tall, 1–4 cm thick, thin-walled, erect; internodes glabrous, substantially grooved above branches, apically terete, lightly waxy below nodes, green or becoming purple-striate to red-purple where exposed later; nodes with thin unraised initially puberulent sheath scar, supranodal ridge distinctly raised. Branches 3–5(–9) per node at first, the central branch thicker. Culm sheaths coriaceous, basally very thick and smooth, often remaining attached at centre, glabrous but initially puberulent on the persistent basal ring, green with purplish streaks at first, margins glabrous, shoulders raised; auricles absent; oral setae absent or scarce and rudimentary; ligule ca. 1 mm, shortly ciliate, glabrous. Leaf sheaths glabrous, margins glabrous, shoulders rising; auricles lacking; oral setae 2–5 each side, weak, erect, 2–5 mm; ligule ca. 2 mm, truncate, shortly tomentose, shortly ciliate, external ligule very shortly ciliate; blades 4–5 each branchlet, 9–20 cm long, 1.2–2.5 cm wide, glabrous, long-acuminate with a long fine tip. Spikelets sessile or shortly pedicellate, narrow, with 3–6 florets;lemmas mucronate, glabrous; paleas 2-keeled, shortly bifid; style with 3 plumose branches 2n = unknown. Name from the Latin fastuosus, ‘proud’, for the erect culms.
The most widely cultivated form of S. fastuosa has culm internodes that can develop purple-brown colouration, and has very short branches, making it an erect and elegant bamboo, but it grows slowly. Cultivar ‘Viridis’ has culms that remain green, and is reportedly more vigorous.
Semiarundinaria fortis, S. makinoi, S. okuboi, and S. yashadake are all quite similar to S. fastuosa, though generally hairier, but their taxonomy remains problematic and they are currently very difficult to identify.
Widely cultivated in Japan, wild origin not known, introduced to Europe late 19th Century.