A loosely clumping bamboo with blackish or purplish-black coloured mature stems growing 3-7 m tall. These stems (1-4 cm thick) the stems are grooved above where the side branches emerge. It spreads rapidly via creeping underground stems which produce upright stems from their joints. Its elongated leaf blades (6-12 cm long and 9-15 mm wide) have very narrow stalk-like bases. It rarely if ever produces flowers or seeds.