The nīkau palm shows considerable variation in the wild. Plants from the South Island and the offshore islands of the North Island have larger, more-gracefully-arching fronds and are popular in cultivation. The Chatham Islands form is particularly different, having a distinct juvenile form and larger fruits, and a thicker covering of fine hairs on the fronds. More research is needed into its precise relationship with the mainland form. The New Zealand nīkau palm is very similar to Rhopalostylis baueri of the Kermadecs and Norfolk Island, which can be distinguished by its more rounded or oval fruits, and by its leaflets which are broader than those found in most populations of R. sapida.
