Karaka (Corynocarpus laevigatus) grows to 20 metres tall and has a spreading canopy of dark green, glossy leaves. It is found in coastal and lowland forest throughout the North Island and northern South Island, and on the Chatham Islands, where it is called kopi. It is believed that before people arrived in New Zealand, karaka grew only in northern New Zealand, but Māori planted it in other areas. It was an important food – the large seeds within the fruit are poisonous when raw, but are safe to eat after soaking in water and baking.
Karaka regenerates prolifically. In some forest reserves of the southern North Island – and in Hawaii, where it was introduced for timber – it has become a serious weed, choking out other species.
New Zealand’s only plant from the tropical mahogany family, kohekohe (Dysoxylum spectabile) grows to 15 metres tall, with a broad spreading canopy. It is found in coastal and lowland forest of the North Island and northern tip of the South Island. Like many tropical plants, it has large compound leaves and flower stalks that grow directly from its trunk and branches in winter.
Kohekohe fruits take about a year to ripen, and look like bunches of green grapes for much of this time. Eventually they turn brown, then split open, exposing three seeds in a bright orange fleshy covering. The seeds are eaten by large forest birds. Seedlings regenerate well under shade in the absence of possums, a major browsing pest of this species.
Nīkau (Rhopalostylis sapida) is the world’s southernmost palm, growing in coastal and lowland forest throughout the North Island, as far south as Banks Peninsula on the South Island’s east coast and Ōkārito on the west, and on the Chatham Islands.
Nīkau grows to 18 metres in height and is a canopy or subcanopy tree. Its single trunk bears rings of leaf scars, formed when old leaves are shed. The leaves are up to 3 metres long, and are made of many narrow, metre-long leaflets. They form an ascending crown above the trunk’s bulbous top. In summer, nīkau produces a much-branched flower stalk studded with little pink flowers. Its berries take about a year to ripen. Once ripe, they provide abundant food for forest birds, especially kererū (native pigeons), nīkau’s main seed disperser.
Nīkau may be over 50 years old before it forms an above-ground stem, and 90 years old before it flowers and fruits. Botanists estimate that it lives for 200 years.
Māori used nīkau leaves for thatching the roofs of their whare (dwellings) and for weaving.
Growing to 15 metres in height, tawapou (Pouteria costata) only occurs in northern coastal forests. It has shiny green, leathery leaves that exude a milky fluid when torn. Tawapou’s flowers are tiny, only a few millimetres long – they seem disproportionate to the big orange berries that develop from them. Inside the berry are several shiny black seeds, which were used for necklaces by Māori. Kiore (Polynesian rats) eat the berries and have stopped the tree from regenerating in some areas.