Metrosideros () is a genus of approximately 50 trees, shrubs, and vines native to the islands of the Pacific Ocean, from the Philippines to New Zealand and including the Bonin Islands, Polynesia, and Melanesia, with an anomalous outlier in South Africa. 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.