Rengarenga is a species of herbaceous perennial plant, endemic to New Zealand, where it may once have been farmed. The leaves are 30–60 cm (12–24 in) long and 3–10 cm (1.2–3.9 in) wide. The flower stalk often reaches one metre, and bears many white six-petalled flowers, in groups of two or three, each about 2 cm (0.8 in) across. The stamens are tricoloured - purple and white, with yellow at the curled end. The roots are 2–3 cm (0.8–1.2 in) wide.