Culms to 4 m tall, to 2.5 cm thick; internodes to 30 cm, smooth and not finely ridged, glabrous, with light wax at first, becoming glossy; walls thick, to 4 mm; nodes with moderately to prominently raised supra-nodal ridge, sheath scar slightly raised, branches at mid-culm usually solitary. Culm sheaths to 18(--25) cm long, coriaceous, apically rounded-truncate, proximally initially sparsely to quite densely long white-pilose, distally glabrous, hairs erect, external margin membranous, white-ciliate; auricles oblong to falcate, to 3 mm, deflexed; oral setae spreading, white, to 15mm; ligule, ca. 1 mm, entire, glabrous; blade to 5 cm, deflexed, lanceolate. Leaf sheaths shortly pilose, apically glabrous external margin ciliate; auricles ovate, to 5 mm, deflexed; oral setae radiating, to 10 mm, straight, finely scabrous, distally coloured; ligule ca. 2 mm, rounded, entire, glabrous; blade broad, to 25 cm long, to 5 cm wide. Name from Latin, ‘tranquillus’ for the static foliage.
‘Shiroshima’ has leaf blades with variable pale cream to light green stripes occurring rather sporadically and developing best in bright sunlight. ‘Kimmei’ has less leaf variegation but also has culms with yellow and green stripes.
While it seems very likely that this bamboo is the result of hybridisation between species from 2 different genera, the exact parentage and the timing of the hybridisation are disputed, so that it is difficult to produce a stable hybrid generic name. In any case, most bamboos seem to be the result of hybridisation at some time, as this is very common in the bamboos. Consequently it is placed here in Hibanobambusa.
Introduced from Mt Hiba, Hiroshima Prefecture, Honshu, Japan to France in 1980.
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