pronounced: met-roh-SID-er-oss species
Metrosideros is a genus of about 50 trees, shrubs and vines native to the islands of the Pacific Ocean from the Philippines to New Zealand, with one, the odd man out, in South Africa. Most of the trees are small, but a few are especially large, particularly some of the New Zealand ones. The name is derived from the Greek, μετρον (metron), a measure, and σιδηρος (sidéros), iron: thus, a measure (or heart) of iron. Metrosideros are often cultivated for their showy flowers, as street trees or in home gardens. The flowers are generally red, as in this specimen, but some cultivars have orange, yellow or white flowers. The New Zealand Metrosideros excelsa has several cultivars grown in Australia and Hawaii, is very popular in California, and it has even been planted successfully in the north of Spain; but the species is considered an invasive pest in parts of South Africa. Some species recently naturalized in Hawaii are also considered to have the potential to become a pest.
In 1996 a research group from Auckland University began the long task of collecting samples of the approximately 60 species of Metrosideros, with the purpose of undertaking DNA sequencing of all the species to look at patterns of evolution and dispersal across the vast oceanic distances separating them. The collection of the 30 species of the subgenus Metrosideros was completed by 2001, but the second part of the work on the subgenus Mearnsia (to which the New Guinea plants belong) is still in progress, so far as I can ascertain. The majority of these occur in New Zealand and New Caledonia, and proved relatively straightforward to collect; but there are at least four species in New Guinea, one in the Philippines and one in the Solomon Islands that have proved much more elusive. The single Philippines species required three expeditions before it was found, and, at the last up-date I have been able to find, only three of the New Guinea species had been located. The fourth, Metrosideros ovata, which appears to occur only in the high mountain forests of eastern New Guinea, still remained uncollected. A major difficulty in looking for these species was the fact that there were no photographs of them available. Paintings were made by the New Zealand botanical artist Stephen McCarthy, working from the original botanical descriptions of the plants and from photographs of the old and faded herbarium specimens. From his paintings the Telefol people of the upper Sepik instantly recognized the painting of Metrosideros ramiflora as the tree they knew as ang, and were able to take the botanists directly to them. Near Kiunga, the Awin people were less sure of the Metrosideros scandens from the painting, but it was eventually shown to be the vine they called titmin. Metrosideros cordata had already been found, but, in the last account I have been able to find (2001), Metrosideros ovata has still not been collected. It has been recorded from a handful of high elevation sites on the Owen Stanley and Ekuti ranges.
