Discaria toumatou is a prickly, bushy shrub or small tree, which grows up to 20 ft (6 m) high. The green, spear-shaped leaves are 0.4–8 in (1–2 cm) long, and occur singly or in bundles next to the thorns. The white flowers are tiny, 0.1–0.2 in (3–5 mm) in diameter; summer.
Discaria toumatou occurs in sand dunes, riverbeds and scrubland in both the North and South Islands of New Zealand, from Waikato southwards to Otago. In New Zealand it is called wild Irishman. It may not be fully hardy in the UK.