October in the forest with Chris Horne and Barbara Mitcalfe
Corynocarpus laevigatus, Karaka
Karaka is the only NZ species in the Corynocarpus genus, a plant group confined to the south- west Pacific.
Distribution and habitat
If you're tramping around Wellington's wild coast, you occasionally find groves of naturally occur- ring karaka in sheltered valley sites where they can reach to c.15 m. in height, with dense, spreading crowns and stout, usually single columnar trunks. As in earlier Māori times, and even now, the presence of karaka can be a useful indicator of a potential camp site in an otherwise inhospitable environment.
Its dark green leaves are thick and leathery, about 15 cm. long and 7 cm. wide, with down-curved edges, and a glossy sheen, called a “pellicle”, protecting the leaves from wind-driven salt crystals. The tiny greenish flowers are followed by handsome orange fruit, so heavy and prolific as to weigh down the branches. But beware – the kernel inside each fruit contains a deadly poison, karakin. Māori developed a lengthy, laborious soaking and steaming process to eliminate this poison, because once treated, the kernels were an important source of carbohydrate. If you're tempted to try this yourself, don't! However, you may be assured that as long as the fruit is ripe, it is safe to eat the sweet, tangy outside covering, raw.
Some botanists believe that the presence of karaka in the Wellington region is solely due to hu- mans bringing it down from the north, as with pōhutukawa. This is why some Wellingtonians pull up, or choose not to plant, this handsome tree in their gardens or restoration projects, because karaka have become “weedy” here, rapidly becoming dominant, with hundreds of seedlings per square metre, crowding out almost everything else, and significantly altering the species composi- tion of the surrounding ecosystem.
Kererū are the only indigenous bird which can swallow karaka fruit. Apparently the fruit passes through the bird so fast that the kernel is voided in minutes, minus its tasty outer covering – very clever! Kererū numbers are increasing so rapidly in Wellington that staff and volunteers at Otari, the Botanic Garden and Zealandia are having to organise working bees to reduce the number of karaka seedlings and saplings.