Open thicket-forming with rhizomes running extensively. Culm 4-7 m (often much taller in cultivation), green, remaining so or becoming black or heavily blotched black in 2nd year, erect, with white waxy ring beneath nodes when young; nodes all ± evenly spaced. Culm-sheaths uniformly purple or purple-flushed, sometimes dark blotched above; auricles on main shoots prominent, dark; oral bristles long, caducous; sheath-blade linear, undulate. Branches green or black, spreading widely (giving an open network). Leaf-sheath with very short auricles. Oral bristles present. Leaf-blade usually 5-9-(13)× 0.5-2-(3) cm, lanceolate, abaxially glaucescent, adaxially moderately shining, acuminate.