Metrosideros excelsa, commonly known as pōhutukawa, New Zealand Christmas tree, and iron tree, is a coastal evergreen tree in the myrtle family, Myrtaceae, that produces a brilliant display of red flowers, each consisting of a mass of stamens. The pōhutukawa is one of twelve Metrosideros species endemic to New Zealand. Renowned for its vibrant colour and its ability to survive even perched on rocky, precarious cliffs, it has found an important place in New Zealand culture for its strength and beauty, and is regarded as a chiefly tree by Māori.

Metrosideros is a genus of approximately 60 trees, shrubs, and vines mostly found in the Pacific region in the family Myrtaceae. 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 pohutukawa, northern and southern rātā of New Zealand, and ʻōhiʻa lehua, from the Hawaiian Islands.