Tree of the moment: Rewarewa

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A rewarewa flower unfurling beside a busy street in Tauranga. Just visible in the background are the old seed pods. Photo: Sandra Simpson

I spotted the rewarewa tree in Greerton’s shopping area a couple of years ago but had never been in the right place at the right time (with camera) to get a photo of the beautiful flowers – until now.

Sandwiched in tarmac between a small off-street carpark and the footpath it wouldn’t seem to be in ideal conditions but it’s apparently thriving and covered in racemes of intricate flowers just opening or waiting to open. I was once told that rewarewa flowers “are like candyfloss to possums”.

Knightia excelsa grows naturally throughout the North Island, but only in the Malborough Sounds in the South Island, according to the Tane’s Tree Trust website. Maori appreciated the flowers for their nectar, but didn’t use the attractive wood, which is usually pale with a reddish-brown fleck. Early settlers called it the bucket of water tree as it made useless firewood! Its more common name is New Zealand honeysuckle. Honey produced from the tree is said to be a beautiful deep reddish-amber colour with a rich, full bodied caramel-like taste.

The trees are a colonising species in the wild and grow in a conical shape – up to 30m tall but with only a 1m diameter trunk – and have tough, leathery leaves. Lawrie Metcalf writes in his 2011 book The Cultivation of NZ Trees and Shrubs (Raupo) that rewarewa will grow in sun or shade, although very dry conditions will make growth slower.

“The flowers secrete copious quantities of nectar at their bases, to which tui and bellbirds are attracted. In fact, the birds can often be seen investigating the state of the flowers long before they are ready to open. In their desire for the nectar the birds are dusted with pollen, which they transfer from the younger open flowers to the receptive stigmas of the older flowers.”

The tree is a member of the Protea family and distantly related to the Banksias of Australia.

In his 1884 book, Medical Botany of New Zealand, P J O’Carroll noted that the inner part of the bark was bandaged on to wounds and he had seen several wounds healed in a surprisingly short space of time. PME Williams in Te Rongoa Maori (Raupo, 2008) notes that the inner bark was applied in its raw state by bushmen to stem the bloodflow from cuts, and the bark was also used as a bandage. Researchers in 1987 reported that the bark contains beta-sitosterol, a major component of an American proprietary drug used to lower blood cholesterol levels.

Knightia excelsa was first collected at Tolaga Bay in 1769 by Daniel Solander during the first voyage of James Cook.

Our native plants: Whau

Entelea arborescens is a large shrub or small tree, the only one in its genus, and is part of the mallow family, which includes hibiscus, lacebarks and ribbon wood. The trunks of some members have tough fibres as a layer under the bark and these fibres have been used in many countries to make ropes, hats, mats and fishing nets, with the most important fibre in this family being the cotton plant.

Whau has large, soft leaves and is found where it doesn’t get browsed, which in my case meant the base track of Mauao (Mt Maunganui), although I’d seen the spiky, brown seedpods before and wondered what the plant might be. This particular day my attention was caught by the pretty, white flowers on a plant.

The flowers of whau have attractive crinkled petals and resemble a single rose. Photo: Sandra Simpson, taken on Mauao base track

Years ago I’d been told by someone who made wooden jewellery that not only was whau a very light wood, it also had an interesting green tinge to it. In fact, the wood is so light it was used by Maori as fishing floats, while long fibres from the trunk were used as fishing lines. (I’ve read that, when dry, whau in comparison to cork is no more than half the weight.)

The Meaning of Trees website entry says seasoned trunks were also lashed together with supplejack to construct small rafts for hunting crayfish and the plant was of such value to Māori that in some places it was actively cultivated. The Māori name of Auckland’s dormant volcano Mt Eden is Maungawhau (Mountain of the Whau Tree) so its slopes would likely once have been covered in whau, providing a constant supply of fishing material.

The NZ Plant Conservation Network entry says whau is found on Three Kings Islands, North (including Little and Great Barrier Islands) and South Islands. In the North Island, whau is locally common from Te Paki to about Kawhia and Mahia Peninsula, south of there it is known from a few sites in the eastern Wairarapa, at Paekakariki and Wellington. In the South Island it is confined to the Golden Bay area of northwest Nelson.

“Recent field work gathering samples for a Marsden study into the possible past use of whau by Maori indicates it is much less common in the North Island than it once was. Browsing pressure from cattle, goats and horses, clearance of coastal scrub of housing and the spread of invasive woody shrubs and trees into many northern coastal areas may be threatening some populations.”

The tree’s spiky seedpods, pictured at Zealandia in Wellington. Photo: Sandra Simpson

This pioneer species tree is short-lived, surviving for between 10 and 15 years, although easily grows from seed and cuttings. Laurie Metcalfe in The Cultivation of NZ Trees and Shrubs (Raupo, 2011) says the tree grows rapidly, is frost tender and once established can endure dry spells.

PME Williams is his book Te Rongoa Maori (Raupo, 1996) reports that leaves, heated in water, were made into a poultice for treating wounds and sores.

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.”

Tree of the moment: Puriri

Although puriri trees (Vitex luscens) can flower and fruit off and on all year round, winter is the start of the main flowering season, and while visiting Te Puna Quarry Park at the weekend I finally got my first decent shots of puriri flowers – relative to the size of the tree the flowers are small and often hidden underneath the spreading canopy.

The tree is naturally found in roughly the top-third of the North Island. Its pretty flowers provide nectar for birds, while the fruit is an important food source too. The birds return the favour by spreading puriri seed with a helpful little dollop of fertiliser to start them off.

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Puriri flowers. Photo: Sandra Simpson

Lawrie Metcalfe (The Cultivation of NZ Trees and Shrubs, 2011) calls the puriri a “large, handsome tree” and says it grows rapidly when young to a mature height of 12-20m or more. Young trees are frost tender. In Tauranga we have an avenue of mature puriri trees outside the Domain on Cameron Rd, where they don’t seem to mind vehicles being parked on their roots day in and day out!

Alison Evans in New Zealand in Flower (1987) notes that puriri are distantly related to the teak trees of Burma and Southeast Asia, and have one of the longest flowering periods of any native plant.

European settlers used the hardwood for fence posts, railway sleepers, house piles, bridge building and furniture (the veneers have a walnut-like finish), while Maori used the timber for garden tools and weapons. The timber, “very hard, dense and heavy and of great strength” (Metcalfe), is no longer used commercially. The green puriri moth (Aenetus virescens) tunnels through the tree causing much damage, although I’ve seen a magnificent table top that made a feature of the moth’s handiwork. See an unusual cabinet made from puriri here, along with some interesting information about the tree, including that it was traditionally used for eel traps because it sank and that the bark makes a yellow dye.

In the charming small book, Te Rongoa Maori (Maori Medicine, 1996), author PME Williams says the liquor from boiling leaves was used to relieve sprains, backache and ulcers, and he had also heard of an infusion of leaves being taken as a drink to relieve kidney complaints.

Puriri were also used as burial trees by Maori and there is a venerable example, Taketakerau, at Hukutaia Domain near Opotiki in the eastern Bay of Plenty. The Meaning of Trees website offers an age of about 2000 years old, and says: “After the death of a chief or person of high mana, the body would be adorned with a coronet of puriri leaves, and washed with an infusion of the leaves and water.” The website is well worth a visit.

Part of the tree known as Taketakerau in Hukutaia Domain. Photo: Sandra Simpson

A sign by the tree says: “The bones of the distinguished dead some years after burial, were with much ritual, including on occasion the sacrifice of slaves, dug up, scraped, painted with oxide of iron and deposited in a cave or hollow tree where they could not be found and put to base purposes by tribal enemies.

“A tree such as this was highly tapu [taboo] and any desecration of such tapu was a deadly matter and an affront to the tribal atua (ancestral gods). The offender’s death would surely follow.”