Coprosma acerosa is a low, spreading yellowish/green shrub that is native to New Zealand. It is a coastal plant found naturally throughout the North, South, Stewart and Chatham Islands, on the landward side of sand dunes. It forms a tight tangled mound of brown foliage. The yellowish leaves are narrow, small and have a dark line down the middle on the underside. They are in clusters of pairs scattered along twigs. The word ‘‘acerosa’’ used in the binomial name refers to the leaves and is from the Latin word ‘‘acus’’ meaning sharp or pointed. The bark is an orange colour.

It flowers are tiny with long protruding threads. The fruit is a white berry. Coprosma acerosa is declining over large parts of its original range due to competition from marram grass (Ammophila arenaria). The Maori used a decoction of the bark and stems of the pikiarero (Clematis forsteri) and the root of the tātarahake (Coprosma acerosa) taken, ‘‘slightly alternative’’ (A medication that restores health). Colenso 1869.