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Plants small to shrub-like, in dense spreading thickets; rhizomes leptomorph, tillering. Culms 0.5-7 m tall, 0.2-4 cm in diam., self-supporting, erect or nodding, pluricaespitose; internodes terete, smooth, apically pruinose; nodes slightly swollen, the supranodal ridge obscure. Branches 1-10 per mid-culm node, erect, long, central dominant, basal nodes compressed, laterals arising from basal nodes, some lateral branches lacking subtending sheaths, sheaths and prophylls more or less glabrous, very persistent, papery; buds at mid-culm tall, initially closed at front, on small promontory, prophylls 2-keeled, 1 to 3 initials visible within. Culm sheaths persistent, nearly coriaceous; blade deciduous, usually reflexed. Leaf sheaths persistent, blade small to medium-sized relative to stature, without substantial winter necrosis of margins (white edges), arrangement random or more or less distichous, distinctly tessellate. Synflorescence semelauctant, ebracteate, an open raceme or panicle, branching subtended by very small bracts or hairs, often pulvinate, spikelets exserted on long, delicate pedicels. Spikelets 1-4 cm, with 4-8 florets; disarticulation below the florets. Glumes 1-2, much shorter than the first lemma, delicate, basally loose, usually subtending vestigial buds; lemmas to 1 cm; palea shorter than the lemma, 2-keeled. Anthers 3, filaments free. Stigmas 3. Fruit a caryopsis. Name from the Greek pleio ‘many’ and blastos ‘buds’, alluding to the often relatively large number of branches at each node.
Pleioblastus includes about 20 species and is native to Japan and China. Larger species have more branches than other large-stature running bamboos. Small-stature species (Section Nezasa Koidz.) are often similar to those of Sasa or Sasaella, but lack the winter necrosis of leaf margins and have a less palmate, more irregular arrangement of leaf blades. Sometimes they also have several branches. The smaller species have many, often very similar cultivars with variegated leaf blades. These are better known than their green relatives, and unfortunately were often described first, the epithet consequently referring to variegation seen only in a small proportion of the species. Their naming has become highly complicated with very extensive synonymy, a result of narrow species concepts, repeated shuffling of the species, infra-specific taxa, and their variegated and green forms, as well as confusion between names published in Japan and Europe. The larger species, especially P. simonii, can be highly invasive and very persistent. The smaller species are relatively less invasive than similar species of Sasa or Sasaella, but can still spread quite widely.
Suzuki, S. 1978. Index to Japanese Bambusaceae. Gakken, Tokyo.
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