Large pachymorph bamboo with culms to 12 or 13 m high, erect, to c. 7 cm diameter; walls just over 1 cm thick. Culm sheaths striped purple, including the narrowly triangular blade to c. 23 cm long. Auricles low, rounded and wide; sheath with appressed brown hairs when young. Branches 3 from each node, later bearing small subsidiary ones from near their bases; central one much the largest (often a metre or more long). Leaves deep green above, lighter beneath; ligule with weak hairs or short bristles. Relic of cultivation.