Ecologist Robert Vennell is a man mad on plants. His book The Meaning of Trees: The history and use of New Zealand’s native trees tells the stories of the forest giants – kauri, tōtara et al – and the kelp that throngs our beaches. He writes about the oddballs, the plants that are revered, and those used for eating and healing. And he writes about the mongrels. Turns out two of our most-loathed bush dwellers – supplejack and ongaonga – are at once way more annoying and way more fascinating than we gave them credit for.
A trap for eels, rats and people
The thick, black, scrambling vines of supplejack are a distinctive feature of the New Zealand forest. In Māori tradition, the vines were known as ‘pirita’ or ‘kareao’, and grew from the tail of the monstrous eel god, Tunaroa. When Māui’s wife, Raukura, was gathering water from a stream, Tunaroa knocked her over with his giant tail and insulted her. In revenge, Māui ambushed Tunaroa, digging a trench for him to follow and then catching him and hacking him to pieces with his axe. The blood of Tunaroa was spattered across birds such as pūkeko and kākāriki, and plants such as rimu, tōtara and matai, giving them their distinctive red colouring. Tunaroa’s dismembered head was thrown into the sea to give rise to marine eels, while the tail gave rise to the freshwater eels. The very tip of the tail took root in the forest to become the supplejack vine, which from then on was used to construct eel traps, to catch the children of Tunaroa. Māui’s example is a good guide to catching eels: dig trenches, steer them into shallow water then construct traps for them with supplejack vines.
A wall of vines
Ever since these legendary times, supplejack has proven something of a trap for people as well. Dense thickets of supplejack provide an almost impenetrable barrier to moving about in the bush. Anyone who is familiar with tramping off-track in New Zealand forest is likely to be familiar with the peculiar form of bush yoga that is required to navigate through the tangled vines. Some Māori believed that these dense walls of supplejack were created by the magical patupaiarehe, or fairy folk, who weaved fortifications to keep people out of their misty forest homes.
The trials of contending with supplejack were recounted by the first Europeans to explore New Zealand on foot. While anchored in Dusky Sound, Captain James Cook wrote in his journal:
In many parts the woods are so over-run with supplejacks, that it is scarcely possible to force one’s way amongst them. I have seen several which were fifty or sixty fathoms long.
Ever since, the plant has provided a barrier to all kinds of explorers, settlers and soldiers. One early Nelson settler surveying land for the New Zealand Company compared weaving through a supplejack forest to a blowfly trying to move through a tangled hairbrush.
The long vines were also the cause of a number of accidents and deaths in the early days of settlement. There are tales from the timber industry of men attempting to flee from falling trunks and rolling logs, only to be tripped up by a length of supplejack and crushed. Wayward supplejack vines have sent people plummeting to their deaths off the edges of cliffs, and one missing goldminer was eventually found strangled by supplejack in a gully.
Despite the anguish it causes, supplejack can occasionally be of assistance when clambering about in the forest. The famous Pākehā explorers Thomas Brunner and Charles Heaphy used the vines to abseil down perilous cliff faces and precipices when making their famous trip around the north-west of the South Island. More recently, the survival expert Bear Grylls used supplejack to descend a cascading 37-metre waterfall while demonstrating survival techniques in the New Zealand forest.
A terror of the bush
Supplejack was to play a decisive role in the New Zealand Wars of the 19th century. For Māori, supplejack was an advantage, as it allowed them to bind together palisade walls and rescue wounded warriors from the battlefield by looping vines around their ankles and dragging them to safety. The broken stems were applied to cuts and grazes, and are said to have astringent properties that stop bleeding. For larger wounds, a piece of dry supplejack was ignited and burned near the cut to cauterise the wound.
In contrast, the colonial forces had to fight a double war against Māori and supplejack. Heavily clad infantry were frequently held up by the plant catching their bulky packs and bayonets, and strategic manoeuvres were often critically delayed by this slow progress. This led many British soldiers to develop an intense fear of the bush. One soldier recounted during the Taranaki wars that his platoon would retreat in the face of even the smallest bush fragment:
I can only suppose that we were scared by the terrors of the bush in front of us, to the extent of losing our reasoning faculties. It is the trees which fight the battles for the natives, and the very sight of a supplejack insures us a whipping …
It was in large part as a result of supplejack, as well as the tough terrain of the New Zealand bush, that the British army created an elite corps of ‘Forest Rangers’ — the forerunners of today’s Special Operations Forces. These lightly trained bushmen were equipped with short knives, small packs and revolvers, and were trained in tramping off-track, weaving through supplejack vines, and firing off rounds as they ducked behind trees.
Strong and pliable
Even though it can be a nuisance, supplejack has proved itself an incredibly useful and practical plant as well. It was a valued medicinal plant for Māori, with an infusion of the root being used to treat blood disorders, skin diseases, rheumatism, fever, bowel complaints, sexually transmitted diseases and heavy menstrual flow. There are even some reports that the decoction was drunk by pregnant women in order to cause an abortion.
Perhaps its greatest value was in construction, where it was used extensively by both Māori and Pākehā.
The tough, pliable, woody stem provided an excellent material for making baskets and sheep hurdles, and was useful in binding together fences, houses, canoes and platforms. The sturdy vines also made excellent pots, traps and nets for catching crayfish, eels and fish such as kōkopu.
A length of the vine could be fashioned into a walking stick or hollowed out and made into a musical instrument, such as a trumpet or bullroarer.
Supplejack vines were commonly employed by Māori when hunting kiore, the Polynesian rat. Little sections of vines could be cut to make small trapdoor cages that swung shut. They were also made into spring snare traps, such as the tāwhiti makamaka. One end was split, propped open with twine, and baited with forest berries such as miro. In order for the rat to access the bait, it had to gnaw through the twine holding the split stem apart. This released the supplejack, which sprung back with great force, catching the poor kiore in a noose and killing it instantly.
A deadly stinger with pain-killing properties
Unlike its neighbour, Australia, New Zealand has very few dangerous animals. But plants are a different story. Lurking in the New Zealand forest is one of the largest stinging nettles in the world, packed with enough poison to kill a fully grown human, and regarded by some as the world’s most dangerous stinging plant.
In 1961 two young hunters in the Ruahine Ranges stumbled into a patch of the New Zealand tree nettle ongaonga. They were lightly clad, and were badly stung on their arms and legs. An hour later one of the men had difficulty walking and breathing, and soon lost his sight. He died five hours later in hospital. While this remains the only confirmed human death on record, there is an unconfirmed report of a man who went skinny-dipping in a river, was stung all over by ongaonga before he could get his clothes on, and died soon after.
Most who are stung lightly by ongaonga survive, but a number have been bedridden for several days in a serious condition.
The source of ongaonga’s toxicity is an array of poisonous syringe-like spines. When an unfortunate victim disturbs the plant, the spines are released — the sharp tip breaks off and the toxic substances are released into the skin. This injects a potent cocktail of compounds — histamine, serotonin and acetylcholine — which enter into the bloodstream and manipulate the nervous system. The skin becomes strongly inflamed and intensely painful, and in severe cases the victim begins drooling and losing their sight. With higher doses, the victim loses motor coordination and begins to convulse violently.
Research on the toxic compound has found that just five of these stinging spines are enough to kill a guinea pig, and ongaonga has killed dogs, cattle and horses in the past. The historian James Cowan recalled one such event when two men accidentally rode a pair of horses through a patch of ongaonga.
The horses were stung ferociously. Driven wild, they threw their riders and bolted. One horse rushed into a river and drowned; the other was found dead in the forest sometime later.
Interestingly, however, possums, goat and deer appear to eat ongaonga with no apparent effects.
A husband trap
Māori believed ongaonga had been placed in the bush to prevent people moving around freely. One version of the tale is that Kupe had stolen the wives of his brother-in-law Hoturapa. As Kupe fled the angry husband, he left obstacles on the path behind him — tātarāmoa, matagouri and the stinging ongaonga — as a way of slowing down his pursuer. The same story is told in a variety of different ways, and the names of the characters and plants differ depending on where you are in the country. The overall idea, however, remains the same: that from the very earliest days ongaonga was a plant used to slow people down and annoy and irritate them.
There are even anecdotes that Māori intentionally planted ongaonga as a protective barrier against intruders, and used the plant in defensive palisades, growing it between burnt stakes of mānuka.
Ongaonga was often invoked for anything in Māori life that was irritating or annoying. A frustrating person was called he tangata ongaonga — a prickly person. And when performing a rite of divorce, a tohunga might call upon ongaonga to cause the unhappy couple’s skin to prickle any time they were together.
Traditionally, Māori boiled the bark of ongaonga with kawakawa leaves as a treatment for eczema and venereal disease. It was either drunk or applied to the skin. Overseas, dock is a traditional remedy for nettle stings, and the leaves of introduced dock have been used to treat ongaonga stings by Pākehā and Māori.
Somewhat counterintuitively, the stinging leaves of ongaonga may one day provide a medical treatment for chronic pain. When a victim is stung, there is an initial rush of intense pain, but this is then followed by a period of prolonged numbness and insensitivity. While scientists have a fairly good handle on what causes the strong stinging reaction, the compounds responsible for the numbing after-effects are poorly understood. Currently an international research team has begun preliminary work to isolate these numbing compounds. If successful, the work could result in new therapeutics for chronic pain from conditions such as diabetes, leprosy and autoimmune diseases.
Despite the danger, ongaonga was occasionally eaten by Māori as food. The large stems were peeled, and the pith inside, which somewhat resembles the inner threads of lacebark, was eaten raw; it is said to taste rather sweet. The flowers can also be used as the basis for a delicately flavoured honey, similar to that produced by thistle.
One animal, however, has become immune to the toxic effects of ongaonga. The red admiral butterfly lays its eggs on the new growth of ongaonga leaves. Here, its caterpillar larvae hatch and spend up to six weeks feeding on the leaves. In this vulnerable stage the caterpillars use the leaves for protection, wrapping them around themselves like a blanket or constructing a small tent in which to hide from would-be predators, such as birds, spiders and other insects. Red admiral populations appear to have been declining in recent years, and it is speculated that this may be partly the result of people treating ongaonga as a weed and removing it from bush, lawns and parks.
© The Meaning of Trees: The history and use of New Zealand’s native plants, by Robert Vennell (HarperCollins, $55), available at Unity Books.
Robert Vennell appears at the Auckland Writers Festival on May 19.