Cereus aethiops is a shrubby, erect, more or less columnar cactus, sometimes prostrate, usually much branched from the base, to 2 m high, 1.5 m wide, with blue waxy coating on young stems and peculiar black spines. It is one of the few true Cereus which will flower when small (on 50 cm tall plants ), the night-blooming flowers are fragrant, white to pale pink, to 20 cm long.