RATAS, Northern and Southern
(Metrosideros robusta and M. umbellata). These two ratas are amongst the best known of New Zealand trees because of the profuse crops of red flowers they bear, in good flowering seasons, about Christmas time. They are also the only broad-leaf trees which, together with the conifers like rimu (Dacrydium cupressinum), rise above the general level of the broadleaf canopy. There are a number of other New Zealand ratas, but they are all climbers of varying habits. The coastal tree, pohutukawa, also belongs to the same genus. Metrosideros belongs to the myrtle family which is a very large one, mostly tropical and subtropical, well represented in Australia especially by the genus Eucalyptus. Species of Metrosideros also occur in Australia as well as in Malaya and Polynesia.
The northern rata is found in coastal to lower montane forests from the Three Kings to the northern part of the South Island. It is a remarkable tree in that it starts as an epiphyte in the crowns of tall forest trees, often rimus. Aerial roots then grow down the trunks of the host tree and from these lateral roots are given off which finally encircle the host. The rata continues to grow till roots reach the ground and the rata finally displaces the host altogether. The trunks of large ratas are therefore most irregular, composed as they are of a tangled, fused mass of roots. The southern rata occurs in lowland to subalpine forests from just north of Auckland to the Snares, Auckland, and Campbell Islands. It commences as a ground plant and grows up to 60 ft high, with a large rounded crown. In many forests on steep mountain sides west of the South Island Main Divide, and especially in Fiord–land, it is the dominant tree.
The leaves of both trees are opposite, 1–2 in. long and about elliptic. Those of the northern rata have emarginate tips, while the leaves of the southern rata are sharp pointed. Both have many-flowered cymes of flowers with numerous red stamens. The leaves are relished by opossums. The wood of both trees is very hard and strong. It is highly prized for firewood, but otherwise is not much used because of the difficulty of getting good logs for sawing. In the early days of settlement, southern rata wood was used for shipbuilding. It is now used, when obtainable, for coach work and cross-arms for telephone poles.
by Alec Lindsay Poole, M.SC., B.FOR.SC., F.R.S.N.Z., Director-General of Forests, Wellington.