Black Wattle is a fast-growing, medium-sized, evergreen tree with expanded petioles that serve as leaves. Trees reach 30 m in height in their native range. The stem is usually straight and topped with a symmetrical crown of relatively light limbs; the lower bole is often fluted. The bark is reddish brown and lightly furrowed. The small flowers are grouped in spikes up to 10 cm long, singly or in pairs in the leaf axils near the branch tips. The trees flower annually, usually at the end of the rainy season or the early part of the dry season.