Corynocarpus is a genus of evergreen trees and shrubs and the sole genus in the flowering-plant family Corynocarpaceae, comprising five accepted species. GBIF places the family in order Cucurbitales, though botanists such as Philipson (1986) have described Corynocarpus as taxonomically isolated within its order. The genus was first published by the German naturalists Johann Reinhold Forster and Georg Forster in 1775. Its name derives from the Greek koryne ("club") and karpos ("fruit"), referring to the club-like shape of the fruit.
The five species are distributed across the southwest Pacific: New Guinea, Queensland and New South Wales in Australia, New Caledonia, Vanuatu, and New Zealand. Biogeographers propose the genus arose in a Paleotropical centre and radiated in two directions — one lineage reaching Australia and New Guinea (C. cribbianus, C. rupestris), the other moving via New Caledonia (C. dissimilis, C. similis) into New Zealand (C. laevigatus). Fossilised Corynocarpus kernels from the early Miocene have been found in New Zealand's Southland Region, showing the genus has a long history there.
The best-documented species, Corynocarpus laevigatus (karaka, or New Zealand laurel), is a medium-sized evergreen tree growing 15–20 m tall with leathery, dark-green elliptic leaves, panicles of small greenish-yellow flowers, and orange, plum-like drupes. Across the genus, seeds are notable for containing toxic nitropropanoyl glucosides (such as corynocarpin and karakin) that make them highly poisonous to humans and animals unless carefully processed — a chemical trait tied to the family's few, closely related species.
Where they occur, Corynocarpus species have significant ecological and cultural roles. In New Zealand, karaka fruit is an important food source for large native pigeons (kererū and the Chatham Islands pigeon), among the few birds with a gape wide enough to swallow the fruit whole and disperse its seed. C. laevigatus has long been a taonga (treasured resource) for Māori and Moriori communities, who developed detoxification methods to render its seeds edible and used the tree culturally, including Moriori dendroglyph carving on the Chatham Islands.
Etymology
The genus name Corynocarpus comes from the Greek koryne ("club") and karpos ("fruit"), meaning "club fruit," a reference to the shape of the fruit. In the best-known species, C. laevigatus, the epithet laevigatus is Latin for "smooth."
Distribution
Corynocarpus is native to New Guinea, Australia (Queensland, New South Wales), New Zealand, New Caledonia, and Vanuatu. Its best-studied species, C. laevigatus, is endemic to New Zealand and its outlying islands (Chatham, Kermadec, Three Kings) and has also naturalised in Hawaii and Southern California.
Ecology
Fruit-bearing species in the genus rely on large native pigeons for seed dispersal — in New Zealand, the kererū and Chatham Islands pigeon are the only native birds with a gape wide enough to swallow the drupes whole. Seeds across the genus contain toxic nitropropanoyl glucosides, a chemical defence that makes them poisonous to most animals unless detoxified.
Cultural Uses
Corynocarpus laevigatus (karaka) was a major pre-European Māori food crop, its poisonous seeds rendered safe through steaming and sun-drying; it is considered a taonga (treasured resource) by both Māori and Moriori. On the Chatham Islands, Moriori carved ancestor depictions (rākau momori) into karaka bark, and the timber was used for canoe-building and food preservation.
History
Fossilised endocarps attributed to Corynocarpus, dating to the early Miocene, have been found at Landslip Hill in New Zealand's Southland Region, indicating the genus has occupied the region for millions of years. The genus is thought to have originated in a Paleotropical centre before radiating into Australia/New Guinea and, via New Caledonia, into New Zealand.
Taxonomy Notes
Corynocarpus is the sole genus in family Corynocarpaceae, placed by GBIF in order Cucurbitales; Philipson (1986) described it as "an isolated genus" within its order. It was first published by J.R. Forster & G. Forster in 1775, with C. laevigatus formally described in 1776 from specimens collected on Cook's second voyage (after an earlier unpublished description by Banks and Solander as "Merretia lucida").
