Phormium colensoi, also called mountain flax, or wharariki in Māori, is a perennial plant that is endemic to New Zealand. The greenish, yellow or orange flowers are followed by twisted seed pods. It is less common than the other Phormium species, P. tenax or harakeke. Mountain flax is also called whararipi, whatariki, mangaeka, kōrari tuauru, wauraki, coastal flax, hill flax and lesser New Zealand flax.

Phormium is a genus of two plant species in the family Asphodelaceae. One species is endemic to New Zealand and the other is native to New Zealand and Norfolk Island. The two species are widely known in New Zealand as flax or their Māori names wharariki and harakeke respectively, and elsewhere as New Zealand flax or flax lily, but they are not closely related to the Northern Hemisphere's flax, which is native to the region extending from the eastern Mediterranean to India and has been used by humans since 30,000 B.C.