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 M. excelsa, M. robusta and M. umbellata of New Zealand, and M. polymorpha from the Hawaiian Islands.

Metrosideros angustifolia commonly known as Cape Gum or Lance-leaved Myrtle in English and Smalblaar or Smalblad in Afrikaans is a South African endemic species from the Western Cape Province where it can be found growing mostly along streams. It grows into an evergreen shrub or small tree one to three meters tall. It has flaky bark and long narrow leaves. During summer it bears clustered white/cream flowers. Cape-gum would make an excellent garden tree, which would probably be fairly water-demanding until established as a sapling. It grows well in moist soil and is drought sensitive. It requires little pruning and makes an excellent bonsai.