Acacia koaia is usually distinguished by growing as a short (rarely more than 5 m or 16 ft), broad, gnarled tree; having the seeds longitudinally arranged in the pod; shorter, straighter phyllodes; and much denser wood.

Acacia koaia, Koaiʻa, is highly adapted to dry habitats, and is capable of forming dense forests in areas with very little rainfall.

Associated plants include uluhe (Dicranopteris linearis), hala (Pandanus tectorius), koʻokoʻolau (Bidens spp.

Koaiʻa is one of the species being used to revegetate the island of Kahoʻolawe, which lost most of its plant life to overgrazing and ordnance testing.

[4] Native Hawaiians ground koaiʻa leaves and bark with ʻauʻaukoʻi (Senna occidentalis) and kikānia pipili (Desmodium sandwicense) stalks.