Plants shrub-like, in dense spreading clumps; rhizomes leptomorph, short. Culms erect, 1.5–9 m tall, 0.5–4 cm thick, self-supporting, pluricespitose in well-separated clusters; internodes basally flattened or grooved above branches, terete above, glabrous (initially pubescent in S. densiflora); nodes slightly raised. Branches erect, initially 3(–5) per node; buds at mid-culm tall, open at front, prophylls 2-keeled, 2–3 initials visible. Culm sheaths deciduous, coriaceous; auricles absent or rudimentary; oral setae absent or rudimentary; blades linear to lanceolate, reflexed. Leaf sheaths deciduous; auricles poorly developed; ligule rudimentary; blades oblong-lanceolate to linear-lanceolate, thick, venation distinctly tessellate. Synflorescence partially iterauctant, branching fully bracteate, racemose, with clusters of 1–3 spikelets each subtended by a large bract with small blade. Spikelets sessile or shortly pedicellate, narrow, with 2–10 florets; glumes with vestigial subtended buds; lemmas mucronate; paleas 2-keeled; stamens 3; style with 3 plumose branches. Name an allusion to its similarity to Arundinaria.
Semiarundinaria includes approximately six very similar species from Japan, and S. densiflora from China, sometimes placed in its own genus Brachystachyum. Plants cultivated under the name Brachystachyum densiflorum in the west are mostly an unidentified species of Oligostachyum instead.
Suzuki, S. 1978. Index to Japanese Bambusaceae. Gakken, Tokyo.