see list

Metrosideros is a genus of tree native to the islands of the Pacific Ocean, including the Bonin Islands, Polynesia, and Melanesia. There are approximately fifty species, in two subgenera, Mearnsia (24 species) and Metrosideros (26 species). The best-known species are the Pohutukawa (Metrosideros excelsa), Northern Rata (M. robustus), and Southern rata (M. umbellatus) of New Zealand and M. polymorpha, known in Hawaii as the Ohi'a lehua. New Caledonia has seven endemic species of Metrosideros, Hawaii five, and New Zealand four.

Metrosideros seeds can disperse on the wind, which accounts for its wide distribution from its source in New Zealand. How the genus reached Hawaii appears puzzling at first sight, because the prevailing NE trade winds blow in the opposite direction. However molecular evolutionary evidence suggests that intermittent high altitude circulation may have brought it north from the Marquesas Islands.

Metrosideros species (not a complete list)

• M. bartlettii (New Zealand)
• M. boninensis (Bonin Islands)
• M. cherrieri (New Caledonia)
• M. collina (Fiji)
• M. engleriana (New Caledonia)
• M. excelsa - Pohutukawa (New Zealand)
• M. gregoryi (Samoa)
• M. humboldtiana (New Caledonia)
• M. kermadecensis (Kermadec Islands)
• M. macropus (Hawaii)
• M. microphylla (New Caledonia)
• M. nervulosa (Lord Howe Island)
• M. nitida (New Caledonia)
• M. ochrantha (Fiji)
• M. oreomyrtus (New Caledonia)
• M. polymorpha - Ohi'a lehua (from Vanuatu in the southwest to French Polynesia in the east and Hawaii in the north)
• M. punctata (New Caledonia)
• M. robustus - Northern Rata (New Zealand)
• M. rugosa (Hawaii)
• M. salomonensis (Solomon Islands)
• M. sclerocarpa (Lord Howe Island)
• M. tremuloides (Hawaii)
• M. umbellata - Southern Rata (New Zealand)
• M. waialeaiae (Hawaii)

Sources

• Wright, S. D., Yong, C. G., Wichman, S. R., Dawson, J. W. & Gardner, R. C. (2001). Stepping stones to Hawaii: a trans-equatorial dispersal pathway for Metrosideros (Myrtaceae) inferred from nrDNA (ITS+ETS). Journal of Biogeography 28 (6), 769-774.