The first New Zealand plants in European gardens came from seeds taken back to Britain in 1771 by the botanists on Lieutenant James Cook’s voyage. In Britain they were successfully grown in the Royal Botanic Garden at Kew, the Chelsea Physic Garden, and the gardens of various gentlemen. The showier flowering plants were particularly prized: kōwhai (Sophora tetraptera and S. microphylla), mānuka (Leptospermum scoparium) and flax (Phormium tenax), and also several species that New Zealanders might not think of as garden plants, including poroporo (Solanum laciniatum), horokaka or native ice plant (Disphyma australe), kōkihi or New Zealand spinach (Tetragonium tetragonioides), and even piri-piri or ‘biddy-bid’ (Acaena anserinifolia and A. novae-zelandiae) – a ground cover regarded locally as a nuisance because its small burrs catch on clothing and sheep fleeces.
By 1800, as a result of exchanges between gardeners and sales by nurserymen, these and other New Zealand plants were already growing in gardens right across Europe, from Dublin to Edinburgh, Paris and Moscow.
Nineteenth-century scientists including Charles Darwin believed that New Zealand species were less vigorous and competitive than European species and predicted that they would not be able to establish in Europe. They argued that there was more evolutionary progress on the large land masses of the northern hemisphere, where there were larger populations of plants and animals, and more competition. But some New Zealand species have managed to establish in the wild in Europe; Darwin’s prediction has not been borne out.
New Zealand flax is grown in many countries as a spectacular garden plant, and it has also been grown commercially for fibre production. In the 19th and early 20th centuries British imperial administrators saw it as a possible cash crop for various outposts of the empire. They tried to establish flax industries on islands such as Tristan da Cunha and St Helena in the South Atlantic, and the Isle of Man in the Irish Sea. On Tristan da Cunha, where other materials were in short supply, the flax was used for roofing – it bleached in the weather to give the stone cottages a fine blonde thatch. On St Helena, flax was the mainstay of the island’s economy until the 1960s, when flax fibre could no longer compete with the new synthetic fibres.
Kiwi (Apteryx australis mantelli) were first displayed in the zoo at Regent’s Park in London in 1851, and by 1875 there were tuatara (Sphenodon punctatum) and 17 species of New Zealand birds, including kākāpō (Strigops habroptilus) and a solitary huia (Heteralocha acutirostris, now extinct). There are now protective restrictions on exporting such species from New Zealand, but kiwi and tuatara remain prize exhibits, bred in captivity and exchanged between zoos around the world.
Many New Zealanders travelling overseas will have recognised New Zealand plants growing in some places far from home. Some species are well established in gardens, parks and public places around the world. They grow best in regions with a climate like New Zealand’s, such as southern Europe, California or Japan.
Travellers have spotted New Zealand flax in Japan, cabbage trees (Cordyline australis) in Italy, nīkau (Rhopalostylis sapida) along the boulevards of Los Angeles (where they are called ‘feather-duster palms’) and scarlet-flowering pōhutukawa trees (Metrosideros excelsa) in Spain. The Spanish city of La Coruña has adopted pōhutukawa as its floral emblem, and boasts a great tree said to be many hundreds of years old. However, a visiting New Zealand botanist has suggested that it may date only from the time of the Napoleonic wars, when the British army fought a famous rearguard action at La Coruña in 1809 and buried their general there. The tree may have grown from a seed or small plant, possibly from a garden in Britain.
Britain has a colder climate than New Zealand, but quite a few natives grow well there. Commonly grown species include kāpuka or broadleaf (Griselinia littoralis – called ‘New Zealand privet’ in Ireland), and many species of senecio, olearia (‘daisybush’), carex (‘New Zealand sedge’) and the ubiquitous hebe.
New Zealand hebes have become standard international garden plants almost like roses or rhododendrons, although they have not yet entirely lost their New Zealand associations. There is a hebe society based in Britain and a horticultural industry breeding new hybrids and cultivars for the international market. Some new varieties have been exported back to New Zealand.
New Zealand flaxes, cabbage trees, and tree ferns are particularly in vogue in Britain, perhaps because they seem so exotic there. Cabbage trees are so much a part of the landscape in the south of England that they have become known as Torquay or Torbay palms, and are used in tourist posters to promote Devon as the English Riviera.
Native plants growing overseas often look healthier than those in New Zealand, as they are free from many of the pests and diseases that attack them at home. Cabbage trees overseas do not have their leaves notched by the cabbage tree moth as they do in New Zealand, and pōhutukawa grows well in Spain, where there are no possums to nibble at them.
Some plants are growing well even as far north as the highlands of Scotland, at least along the western coast where the Gulf Stream tempers the climate. There the coastal village of Plockton also makes a feature of its tropical-looking ‘palms’ – actually New Zealand cabbage trees growing very far from home.
Some New Zealand plants overseas are garden escapees, having spread from cultivation and run wild. New Zealand flax, cabbage trees, various species of hebe, pittosporum, olearia, carex, and many others have become established in this way in Australia, Britain, the United States and elsewhere.
The New Zealand flax once grown commercially on St Helena, in the South Atlantic, continues to grow wild there – so vigorously that is displacing the struggling local native plants and is regarded as a threat. Karaka (Corynocarpus laevigatus), planted in Hawaii for afforestation purposes in the 1920s, also remains there as a serious weed.
Some plants have been carried abroad in other ways. Four species of the mat-forming piri-piri or ‘biddy-bid’ (Acaena) have been carried in exported wool and are now growing as weeds in parts of the United States and in Britain, especially near old woollen mills.
Other species have been carried abroad unnoticed in potted plants. Several species of Epilobium, which are hardly noticed at home in New Zealand, have become established across Europe, and are now gaining a foothold in North America. One of them, Epilobium brunnescens, known as ‘New Zealand willowherb’ in Britain, has become an aggressive invader, listed among the 20 worst introduced weeds there.
Two species of New Zealand parakeets or kākāriki (Cyanoramphus novaezelandiae and C. auriceps) are kept as cage birds in the United States and Britain. Protective legislation and the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) prohibits any further export of these birds from New Zealand, but the overseas kākāriki continue to be bred and hybridised in captivity.
Three New Zealand species of stick insect, Acanthoxyla geisovii, A. inermis and Clitarchus hookeri, have become established in Britain. Stick insects are a curiosity in Britain as there are no native species there. A variety of exotic stick insects are sold in pet shops and occasionally escape, but the New Zealand species are the only ones tough enough to survive outside in the British winter. In Germany, wētā (Hemideina crassidens and H. thoracica) have been traded as pets.
Two native woodboring beetles, Euophryum rufum and E. confine, hardly noticed in New Zealand, have become notorious pests abroad. After reaching Britain (probably in exported timber) they made themselves known by attacking damp woodwork. These ‘New Zealand weevils’ are now among the commonest borer beetles in houses in Britain, and have spread to France, Scandinavia and Canada.
Some New Zealand native species went unnoticed until they spread abroad. For instance, a mealybug, Balanococcus diminutus, and a fungus, Kirramyces phormii, which both live on New Zealand flax, were first noticed on plants growing in Italy and Japan respectively and only later discovered in New Zealand. Similarly, a phytoplasma (a form of bacteria) known as Phytoplasma australiense was first identified in Australia when it spread there and began affecting papaya and other fruit. It was subsequently confirmed as having originated in New Zealand, where it has been found to be the cause of yellow-leaf disease in flax and ‘sudden decline’ in cabbage trees.
Not all successful invaders abroad are obscure natives at home. Just as European birds have become established in New Zealand, some native New Zealand birds have spread elsewhere. The southern black-backed gull (Larus dominicanus dominicanus) has become established in Australia within the last 50 years. New Zealand’s harrier hawk (Circus approximans) and silvereye (Zosterops lateralis lateralis) both became established in Tahiti after being liberated there by aviculturalists.
The most widely publicised native animal overseas probably got to Britain hidden in potted plants. This is the planarian flatworm Arthurdendyus triangulatus. Planarians are common in New Zealand – these slow-moving black flatworms are often found under rocks or flower pots left out in the garden. Britain, by contrast, has only a few native planarians.
The flatworm made tabloid headlines in Britain when it was discovered that this slimy ‘alien’ had invaded their green and pleasant fields and was eating its way through the local earthworms. Several other New Zealand planarians have followed Arthurdendyus triangulatus to Britain, and there are now as many New Zealand species there as native British species.
Another successful New Zealander abroad is a small freshwater snail, Potamopyrgus antipodarum. It is common in streams and drainage ditches in New Zealand, but when it was found in London’s River Thames in the 1850s, British scientists did not recognise it. They assumed it was a rare local species and gave it a new name.
The snails probably got there in sailing ships’ water barrels filled from streams in New Zealand. They are adapted to brackish water, so could live in the barrels until they were eventually tipped out with the last foul dregs into the Thames after the long voyage from the Antipodes.
During the 19th century the snail spread through the streams and rivers of Britain and then across to the continent of Europe – and in each country scientists gave this unknown species a new name. Suggestions that it might be similar to a species known from New Zealand were ignored until in the 1970s two New Zealand scientists showed that it was in fact Potamopyrgus antipodarum. The ‘New Zealand mudsnail’, as it has become known, is continuing to spread through the streams and rivers of Europe and now the United States, displacing local snails.
Judd, Warren. ‘Attack of the clones: a New Zealand freshwater snail takes over the world.’ New Zealand Geographic 70 (November–December 2004): 76–81.