This is the most abundant forest tree in New Zealand. It occurs in lowland, montane, and subalpine forests and shrubland from about the centre of the North Island southwards to Stewart Island. It is mostly a medium-sized forest tree, reaching its greatest height of 80 or more feet in the Catlins forests of the south-east corner of the South Island. Trunks are irregular and there are usually more than one to a tree. It frequently commences as an epiphyte on tree ferns. Leaves are opposite, 2–4 in. long, about elliptic and are coarsely and bluntly toothed. Those of juvenile plants are three-lobed or three-foliate. The small creamy flowers are borne in short racemes. The fruit is a capsule about one-fifth of an inch long.
Kamahi occurs mostly in mixture with other broadleaf forest trees but occasionally grows in pure limited colonies. It sometimes acts as a pioneer shrub through which the southern beeches (Nothofagus spp.) or podocarps grow. Its most extensive development is probably in the forests on the western flanks of the South Island Main Divide where it grows in association with the southern rata (Metrosideros umbellata). As the wood is difficult to season without warping or cracking, it is seldom used in spite of plentiful supplies.
A closely related tree, towai or tawhero (W. silvicola), occurs in much the same habitat as kamahi but north of about latitude 37°. The juvenile leaves are pinnate and the adult three-foliate or pinnate.
by Alec Lindsay Poole, M.SC., B.FOR.SC., F.R.S.N.Z., Director-General of Forests, Wellington.