Forest Vines to Snow Tussocks: The Story of New Zealand Plants
This type is not greatly different from the general conifer broadleaf forest of better drained sites. It is best developed along the Northland coasts and adjacent islands and is dominated by three species that rarely occur very far from the sea. Pohutukawa (Metrosideros excelsd), which often grows alone on coastal cliffs, is restricted to the northern half of the North Island, but karaka (Corynocarpus laevigatus) with its large, dark green leathery leaves and ngaio (Myoporum laetum) extend to the northern and eastern South Island.
Coastal forest is of lower stature than inland forest and, as a result of the general absence of conifers, it lacks emergents.
In addition to the three trees already mentioned, of which pohutukawa is the largest (and when in flower the most spectacular with its bright red stamens) there may be a number of other trees, shrubs and herbs. Many of these also occur in inland forests, at least in the far north. Notable among these are the trees puriri (Vitex lucens), kohekohe (Dysoxylum spectabile) and the shrub kawakawa (Macropiper excelsum).
Of particular note are a number of large-to very large-leaved species in the northern North Island which range from moderately common to rare. Some of them have strong tropical affinities, and so can be regarded as relicts from warmer times.
On the mainland as well as on islands, and extending to East Cape and beyond, are the small trees parapara or the 'bird catching tree' (Pisonia brunoniana) and tawapou (Planchonella costata). Parapara has extremely sticky fruits to which small birds can become attached. It is also found in Australia and some Pacific Islands. The tawapou is closely related to species in Norfolk Island and Fiji.
The remaining species are found on the Three Kings Islands85,86 off the northern tip of New Zealand and are either restricted there to or also occur on the Hen and Chicken Islands or Poor Knights Islands further south.
|(a)||Genera with no other New Zealand species: Pukanui (Meryta sinclairii): a small tree with very large simple leaves which is also found on the Hen and Chicken Islands off the Northland east coast. Meryta is centred in New Caledonia with a few species elsewhere in the Pacific.
Tecomanthe speciosa: a liane with compound leaves and cream-coloured tubular flowers. Only one plant is known. Other species of the genus are found in Queensland and New Guinea. Elingamita johnsonii: an endemic genus related to Tapeinosperma of the tropics. Only one tree is known.
Davallia tasmanii: a fern belonging to a largely tropical genus.
|(b)||Genera with one or two more widespread species in New Zealand:
Pennantia baylisiana: one tree only is known.
Alectryon grandis: one tree only is known on the Three Kings. It is possibly also found on the Poor Knights Islands.87
Streblus (Paratrophis) smithii.
Cordjline kaspar: also on Poor Knights Islands.87
(Some of the rare species may have been more common before goats, which have since been exterminated, were released on the Three Kings Islands.)
It should not be thought that plants are restricted to coastal forest because they require a salty environment. They grow near the coasts because that is where the mildest climates are. If New Zealand extended further to the north, then many of them would occur at inland sites, and indeed the nearest relatives of pohutukawa in the tropical Pacific are not coastal at all, but are found in mountain forests. Conversely, in the far south of New Zealand some species, of inland forests further north, can be found growing close to the sea.