|Flowers and foliage of M. excelsa|
Banks ex Gaertn.
Metrosideros /, / is a genus of approximately 60 trees, shrubs, and vines mostly found in the Pacific region in the Myrtaceae family. Most of the tree forms are small, but some are exceptionally large, the New Zealand species in particular. The name derives from the Ancient Greek metra or "heartwood" and sideron or "iron". Perhaps the best-known species are the pōhutukawa (M. excelsa), northern rātā (M. robusta), and southern rātā (M. umbellata) of New Zealand, and ʻōhiʻa lehua, (M. polymorpha), from the Hawaiian Islands.
New Caledonia has 21 species of Metrosideros, New Zealand has twelve, New Guinea has seven and Hawaiʻi has five. The genus is present on most other high Pacific Islands, including Solomon Islands, Vanuatu, Fiji, Samoa, Cook islands, French Polynesia, Bonin Islands and Lord Howe Island, but absent from Micronesia . The genus is also represented by one species in the Philippines, one in South America (Chile and Argentina), and one outlier in South Africa. Metrosideros seeds can be dispersed by the wind, which probably accounts for their wide distribution. They are often found as pioneer trees on lava flows and on mountain ridges.
Metrosideros are often cultivated for their showy flowers, as street trees or in home gardens. The flowers are generally red, but some cultivars have orange, yellow or white flowers. Some names listed in horticultural catalogs and other publications, such as M. villosa and M. vitiensis, are actually the names of varieties or cultivars (usually of M. collina) rather than valid scientific species. The pōhutukawa of New Zealand has several cultivars grown in Australia, Hawaiʻi and California and it has been planted successfully in the north of Spain and on the Scilly Isles off the south-west coast of Britain, but the species is considered an invasive pest in parts of South Africa. Metrosideros kermadecensis is recently naturalised in Hawaiʻi, and has the potential to become a pest. In turn, various cultivars of M. collina and M. polymorpha are widely grown in New Zealand under various names. Metrosideros umbellata occurs naturally south of mainland New Zealand in the Auckland Islands at 50° South latitude, and is the hardiest member of the genus, and a few cultivated specimens are growing in Scotland.
French Polynesia and the Cook Islands
Fiji, Samoa and Vanuatu
Lord Howe Island
|Wikimedia Commons has media related to Metrosideros.|
|Wikispecies has information related to: Metrosideros|
- Simpson, P., 2005. Pōhutukawa & Rātā: New Zealand's Iron-Hearted Trees. Te Papa Press. 346 pp.
- Wagner, W.L., D. R. Herbst, and S.H. Sohmer. 1999. Manual of the Flowering Plants of Hawaii. Revised edition. University of Hawaiʻi Press and Bishop Museum Press, Honolulu. 1919 pp.
- 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)". J. Biogeography 28 (6): 769–774. doi:10.1046/j.1365-2699.2001.00605.x.
- Wright, S. D.; Gray, R. D.; Gardner, R. C. (2003). "Energy and the rate of evolution: inferences from plant rDNA substitution rates in the Western Pacific". Evolution 57 (12): 2893–2898. doi:10.1111/j.0014-3820.2003.tb01529.x.
- Wright, S.D.; C. G. Yong; J. W. Dawson; D. J. Whittaker; R. C. Gardner (2000-03-21). "Riding the ice age El Niño? Pacific biogeography and evolution of Metrosideros subg. Metrosideros (Myrtaceae) inferred from nuclear ribosomal DNA" (PDF). PNAS. Retrieved 2007-06-13.