Tree of the moment: Karaka

My wanderings in the Whanganui River mist took me along the Anzac Parade bank quite close to the Aramoho rail bridge where I found all sorts of interesting trees in the  reserve.

I photographed the tiny flowers and multi-trunks of what was clearly a New Zealand native without being sure of exactly what it was. A look through the Field Guide to New Zealand’s Native Trees by John Dawson and Rob Lucas (Craig Potton Publishing, 2012) gave me the answer –  Corynocarpus laevigatus or karaka. This is a tree well-known by many in its yellow-orange berry phase but I’d never seen its flowers before.

The book tells me that: “Although now thought to have been originally restricted to the northern North Island, karaka is naturalised in many native forests in the southern North Island and northern South Island, and is considered invasive. Its shade tolerant seedlings can be abundant.” In many cases trees were planted by Maori around settlements as a food source with seeds spread naturally by kereru (native pigeon).

The hardy nature of the karaka is shown by this one beside the Whanganui River – the damaged original trunk is now surrounded by about 20 new trunks. Photo: Sandra Simpson

A 2002 article by Graham Harris in the Journal of the Royal New Zealand Institute of Horticulture says: “Karaka … is a serious weed pest in Hawaii … The karaka was originally planted in the Hawaiian islands over 100 years ago. It was further spread for re-afforestation purposes, by broadcasting seeds from aircraft over the interior of the island of Kaua’i in 1929. It is now present on four islands and … seeds are being further spread by birds. Of particular concern is the threat that karaka poses to heau (Exocarpus luteolus), a member of the sandalwood family and one of Hawaii’s most endangered plants.”

Karaka can grow up to 20m and features glossy, upright leaves. Some trees have  female flowers, others mostly male (which are larger and open wider) and flowering is from late winter through spring with fruit appearing from mid-summer into autumn.

Karaka flowers – small for a big tree. Photo: Sandra Simpson

The excellent The Meaning of Trees website says karaka means ‘to be orange’ in te reo Maori and that William Colenso recorded karaka as being second only to kumara (sweet potato) as a significant food source for Maori.

The fruit, however, contains the toxin karakin and has to be ‘treated’ before it can be safely consumed – by some alchemy of nature the kereru is immune. A 2007 Government project into looking at karaka for a commercial crop reported that: “The berries contain the sugars sucrose and glucose, the fatty acids stearic and oleic, and six of the eight essential amino acids, while the treated kernels have a food value resembling oatmeal.” Read the report here.

Te Rongoa Maori by retired pharmacist PME Williams (Raupo, 2006) notes that: “Because the seeds are poisonous in their raw state … they are boiled for eight to ten hours then put in a kete or flax kit and left in fresh running water for a couple of days. … When dried, the seeds become quite palatable to chew and are known as Maori peanuts.” The kernels were also ground to make bread and karaka leaves were used as a poultice on wounds.

Karaka berries. Photo: Sandra Simpson

An 1891 article, sourced from the invaluable Papers Past, describes the effects of eating raw karaka berries after the death of a child and how Maori treated cases of poisoning. Read it here. These days cases of dogs dying from eating karaka berries are more common.

According to a collection of karaka references on Landcare Research’s Maori Plant Use Database, Maori told early chroniclers they had brought karaka seeds with them on their migration to Aotearoa New Zealand. The Language Garden website has this to say: “In this case, however, it is the name that came from Hawaiiki, and the tree (known to botanists as Corynocarpus laevigatus) was probably dispersed from around the Bay of Islands.” Read more here.

Robin Atherton studied karaka DNA for her doctoral thesis, concluding that there is a close relationship between northern New Zealand trees and species of Corynocarpus in Vanuatu and New Caledonia. Her thesis is available to read online.

Finally, to link back to Whanganui, here is a piece from a 1913 Journal of the Polynesian Society about the voyaging of the master navigator Kupe, as told by Te Matorohanga. Read the full entry here.

Kupe paddled up the Whanganui River to see if any people lived there; he went as far as Kau-arapawa, so called by him because his servant tried to swim the river there to obtain some korau, or wild cabbage, and was drowned, for the river was in flood. So Pawa was drowned, and his name was applied to that place. (Kau-arapawa is about fifteen miles above the town of Whanganui.) Kupe heard some voices there, but as soon as he found these voices were only from birds (weka, kokako and tiwaiwaka), he returned to the mouth of the river, and then went on to Patea, where he planted some karaka seed of the species called oturu.* While at Patea he tested the soil by smelling it, and found it to be para-umu – a rich black soil – and sweet-scented.

*From the notes of translator S Percy Smith: “The karaka-oturu is described to me as like the ordinary karaka (Corynocarpus levigata), but with smaller leaves and berries and fewer of them, with a low growth. There are some trees of the same species growing at Nuhaka, Hawkes Bay, the seed of which is said to have been brought here by the Kura-haupo canoe, under Whatonga. If this karaka at Patea bore a few fruit on the west side of the tree it denoted a lean year – if on the east, or inland side, it meant a prolific year for all cultivated foods. The Rev. T. G. Hammond, who knows Patea and its history better than any man, does not recognise this tree. It is also related of Turi, who commanded the Aotea canoe, and who settled down at Patea, that he brought the karaka tree with him.”