The centre of diversity is in the upper West Coast of the South Island, and the genus appears to be absent from the eastern portion of the North Island, (the Bay of Plenty, East Cape, and northern Hawke's Bay), presumably due to a recent history of volcanism.
The center of diversity for this species is found in the upper West Coast of the South Island, while it appears to be absent from the eastern portion of the North Island (the Bay of Plenty, East Cape, and northern Hawke's Bay), possibly due to recent volcanic activity.