The New Nature Read online

  I am wandering through bushland with environmental consultant Rohan Cuming. As we wend our way through copse and thicket he keeps up a colourful banter: ‘This Sydney blue gum’s a bloody good weed. And that’s a real spready wattle. Here we’ve got a melaleuca, a big mongrel thing. I’ve seen it walking down roadsides. We’ve hand-pulled a lot of hakeas. These are hakea seedlings. They walk too, they really do. And there’s a Western Australian flowering gum.’

  I stumble along, wide-eyed in disbelief. In my darkest dreams I’ve never imagined the likes of this. We are in Mt Martha Park on the Mornington Peninsula near Melbourne, and it’s Australiana gone haywire. Weeds are overrunning this place – and the punchline is that most of them are Australian plants. A tangle of thirty-eight species has claimed a hillside that once carried grassy she-oak woodland. They make up the thick undergrowth we scrape through. All of this in an important nature reserve.

  Hundreds of Australian plants were planted on Mt Martha in the 1950s and 1980s to create an arboretum. Management lapsed, and more than a third of the species ‘walked’. The arboretum is now an 8.5 hectare eco-mess. Peppermint trees (Agonis flexuosa) from Western Australia jostle with South Australian sugar gums (Eucalyptus cladocalyx) and lemon-scented tea-trees (Leptospermum petersonii) from mountains in Queensland or northern New South Wales. Eleven plants spreading here have not been seen as weeds in Victoria before. ‘In the vernacular this is called a horror show, this level of weed invasion,’ Rohan assured me. Mornington Council wants him to remove all the weeds. I suggested he drop napalm.

  Mt Martha is an exaggerated version of a common problem. Native garden plants aren’t usually taken into the wilds directly, as animals on ‘arks’ were, but they soon make the move themselves by casting about their seeds. Wherever they are grown, some of them ‘walk’ into nearby forests and become weeds (plants that grow where they’re not wanted). Such plants undermine the idea that native gardens are good for the environment. They’re another example of changing nature, of wildlife going somewhere new.

  Victoria is by far the worst-affected state, with 200 Australian plants on her weed lists. These include more than thirty each of wattles and eucalypts, ten tea-trees and paperbarks (Melaleuca), a smattering of rainforest plants, and even kangaroo paws (Anigozanthus flavidus) from Western Australia. Western Australia has almost sixty errant natives, including tree-ferns (Cyathea cooperi) in gullies, she-oaks (Casuarina equisetifolia) on shores, and the plants I saw from the stream in John Forrest National Park (see chapter 12). Canberra has at least twenty-six invaders, including nine wattles and four hakeas. Misbehaving plants include golden wattle (Acacia pycnantha), Australia’s floral emblem, the floral emblems of Tasmania (blue gum) and the Northern Territory (Sturt’s desert rose, Gossypium sturtianum), and fine-leaved tuckeroo (Lepiderema pulchella), a very rare rainforest tree.

  Parks Victoria pours 30 per cent of its budget for the Mornington Peninsula into destroying Australian plants. They spent $95000 just in Arthur’s Seat State Park (near Mt Martha), just on one plant: bluebell creeper (Sollya heterophylla) from Western Australia. In the Dandenong Ranges National Park, just to the north, nine tree weeds are controlled and six of these are Australian. In Sydney, where highways slice through reserves, managers worry about three wattles that tint the verges blue: golden wreath wattle (Acacia saligna) from Western Australia, Cootamundra wattle (Acacia baileyana) from southern New South Wales, and Queensland silver wattle (A. podalyriifolia) from well to the north. In Adelaide’s Belair National Park sweet pittosporum (Pittosporum undulatum) is attacked as one of the two worst weeds. Surf Coast Shire, west of Melbourne, has published what looks like a wildflower guide – except that the text below each image of a tea-tree or wattle has advice like ‘treat the stems with a systemic herbicide’. Half of the sixteen shrubs and trees in this weed booklet are Australian.

  Most council weed lists produced in the southern half of Australia feature native plants. (Some of the major offenders are listed in Appendix 1.) Government scientist El Bruzzese toys with the idea of deploying biological control against some of these plants, for example coast tea-tree (Leptospermum laevigatum). It is so invidious it has spawned an organisation in Western Australia, the Feral Tea-Tree Eradication Group, committed to its defeat.

  Australian weeds are sometimes worse than anything imported from abroad. They elbow aside local vegetation, change fire regimes, create monocultures and shade out smaller plants. Sweet pittosporum forms thickets so dark that eucalypt seedlings cannot sprout below, ending forest succession by turning sunny eucalypt woodlands into perpetually gloomy glades. In Adelaide’s Belair National Park this same tree is shading out a rare orchid (Pterostylis cucullata). (In Jamaica it is shading out many rare plants, and in the Azores, west of Portugal, it is taking over the habitat of the endangered Azores bullfinch.) Around Brisbane the umbrella tree (Schefflera actinophylla) from tropical Queensland is shading the understorey in exactly the same way. I have pulled out eighty seedlings from one square metre of eucalypt forest. Very few foreign weeds behave this badly. In a study on the Sunshine Coast I ranked umbrella tree the worst of forty-three weeds.

  These kinds of problems are also global in nature. Australian garden plants are misbehaving all over the place. Umbrella trees are taking over hills in Hawaii, wattles are infiltrating Africa, and sweet pittosporum poses problems on four continents. One of our most unlikely weeds – the tree-fern invading Western Australia – is also invading Hawaii, New Zealand, South Africa and Mauritius. Australian plants have been popular for a long time abroad. Sweet pitosporum seeds were selling in America by 1826, and Robert Sweet’s Flora Australiensis, an English gardening book, appeared two years later.

  The seed trade has provided many plants with a passport to the world. No species better illustrates this point than Cootamundra wattle. This very attractive shrubby tree grows on hills just north of Cootamundra in southern New South Wales. The town was a key stop on the Sydney–Melbourne railway, and this golden shrub with the lacy leaves soon found its way into gardens around Australia before journeying abroad. Now it is weedy in Europe, Africa and America, and in every Australian state. I’ve seen it running amok in Sydney, Melbourne, Canberra, Perth, Tasmania, New Zealand and California. ‘Coota-bloody-mongrel wattle’ is one name for it. Some years ago its seeds were on sale in Dick Smith’s Australian Geographic shops. (I wrote a complaint to the supplier but received no reply.) It even rates a mention in Australia’s National Weeds Strategy. Not bad for a plant with a range originally about 25 kilometres long and wide. Rarely does anything ever go from so little to so much. Like the redback spider, it has leapt from obscurity to infamy in a hundred years.

  The first Antipodean gardening book, Thomas Shepherd’s Lectures on the Horticulture of New South Wales (1835), confined itself to vegetables, but only three years later a book came out featuring native flowers. It was nurseryman Daniel Bunce’s Manual of Practical Gardening Adapted to the Climate of Van Diemen’s Land Containing Plain and Familiar Directions for the Management of the Kitchen, Fruit and Flower Gardens, Nursery, Greenhouse and Forcing Department for Every Month of the Year, reissued in Melbourne in 1850 as The Australian Manual of Horticulture. Bunce urged readers to dig up young forest shrubs and plant them in their gardens: ‘Many of these plants are not only free, but pretty flowerers’, he averred. The ‘leaves of most, when rubbed, emit a strong agreeable scent, and give so verdant and lively an appearance to the borders, when compared to their more slow growing and unacclimatized exotics, that no shrubbery is perfect without them.’ Bunce promoted pea-bushes, mint-bushes, stinkwood, and many other plants unsuited to the over-fertilised soils of our cities today.

  H.A. James devoted thirty pages of his Handbook of Australian Horticulture (1892) to Australian natives. He bemoaned the fact that ‘plants and flowers indigenous in Australia do not appear to have received from Colonial nurserymen and amateur gardeners that consideration which their beauties may fairly claim’. His weighty tome li
sted many of today’s weeds, including wandering jew (Commelina diffusa), a sprightly little creeper that blights my garden. The first Australian book totally devoted to growing natives was William Guilfoyle’s Australian Plants Suitable for Gardens, Parks, Timber Reserves, etc., which appeared in 1911.

  Around this time Edward Pescott was speaking to Victorian horticultural societies about ‘Australian Flowers for Australian Gardens’, complaining, like James, that native plants were ‘very much neglected’. Pescott and Guilfoyle appealed to the spirit of nationalism arising from Federation in 1901, but horticultural patriotism waned as the century advanced. American architect Walter Burley Griffin, moving to Australia after winning the contest to design Canberra, was a lone voice in the wilderness. In the 1920s he organised the planting of nearly 2000 native trees and shrubs at Castlecrag, the Sydney suburb he designed, to better harmonise houses and landscape.

  In the 1950s Australian plants finally won the acclamation they deserved. Thistle Harris published Australian Plants for the Garden (1953), and the Society for Growing Australian Plants formed in 1957. Australians were beginning to adopt natives-only gardens. Interest surged during the 1970s and remains high today. Unfortunately a penchant for native plants can prove as harmful as a faith in island arks for animals. Nurseries that sell natives sometimes do more ill than good. At a Victorian inquiry on weeds in 1998 ranger Wayne Hill railed against the bluebell creeper ruining Arthur’s Seat State Park: ‘We have spoken to about twenty nurseries about growing that weed, but one opposite the park will not stop selling it. I have had irate and friendly chats with that nursery. I have tried psychological warfare, explaining that I am telling people the nursery is not a good-quality nursery – but they are still selling Sollya heterophylla.’

  Before the 1970s very few natives found a place in gardens. Most of our worst miscreants today entered the trade over a century ago. Sweet pittosporum made the grade early because it looked English and answered well as a tall hedge. H.A. James included it among foreign hedge trees and barely mentioned it in his natives chapter. Edward Pescott in 1911 lauded four of today’s worst rogues – pittosporum, bluebell creeper, Cootamundra wattle and golden wreath wattle. These plants have a century’s head start over species brought into cultivation more recently. Many of the newcomers in cultivation will presumably go feral in future. Scientists worry about ‘sleepers’, garden plants that bide their time for decades before breaking out. Our native gardens are vast reservoirs of sleepers.

  Bushfires, which often drive change in the wild, sometimes prompt sleepers to break out of gardens. Geoff Carr admires the rich heathlands around Anglesea, near Melbourne: ‘There are huge expanses of coastal treeless heath where more than a hundred species of orchid grow. But that’s going down the gurgler. It’s all being transformed into taller shrublands.’ The victors here include coast tea-tree, coast wattle (Acacia sophorae), hakeas (Hakea drupacea, H. laurina) and paperbarks (Melaleuca diosmifolia, M. armillaris), all of which were cultivated in gardens close to bushland. After the Ash Wednesday Fire there was a huge recruitment of these things. Seeds travelled hundreds of metres in updrafts. Tens of thousands of seedlings burst forth from the ash beds. Ancient ecosystems were derailed by one fire.

  Many of the eucalypts and wattles planted on our roadsides and farms are not yet weeds, but fires may unleash them, too, in future. Geoff nominates Eucalyptus spathulata from Western Australia as one plant to watch. ‘You don’t see it naturalised much but if you get a fire they all die and you get an impenetrable stand of young ones coming up in their place. They can sit around the landscape for decades and decades and decades, with no recruitment, and then you get a fire . . .’

  Some of these plants, including sweet pittosporum, umbrella tree and bluebell creeper, are spread about by the same birds that spread exotic weeds. Cadagi (Corymbia torelliana), a tropical eucalypt, is pollinated by flying-foxes, then helped by little native bees (Trigona carbonaria) that use the resin on its seeds in their hives. Cadagi is the only plant on earth known to trade glue for transport, and it is multiplying fast along flight paths to hives. The native hive on my verandah has more than a hundred cadagi seeds pasted round its entrance.

  Plants to worry about in future will include those traded across the deserts between east and west, into climate zones that match. We should not be fooled by any notions about a ‘balance of nature’ into thinking that plants will only grow well in their natural habitats. I would watch out for Western Australian ornamental gums coming east, and rainforest plants taken west to the rain-drenched lands around Walpole. One plant with time on its hands is mat-rush (Lomandra longifolia), a domineering species in eastern Australia that is now sold by nurseries in Perth and sprouting prolifically in gardens there. I have urged weed officers in Perth to get this rush banned, but Australian plants aren’t taken seriously as threats by the Agriculture Protection Board.

  Movement between islands is another worry. Norfolk Island pines are invading Lord Howe Island, along with mainland sweet pittosporum, silky oak (Grevillea robusta), flame trees (Brachychiton acerifolius) and bulrushes (Typha domingensis). Pittosporum is one of the two worst weeds on Lord Howe. ‘Two plants were introduced in 1921,’ naturalist Ian Hutton told me. ‘Now there are thousands across Transit Hill. In the last four years I’ve been organising weeding trips.’ Invading in reverse is Norfolk Island hibiscus (Lagunaria patersonia). Bushland consultant Mark Trengove showed me where a prisoner workforce had culled a stand of them at Swan Bay near Melbourne. They were back in greater numbers that day. ‘It’s really become a fair-dinkum weed,’ he acknowledged.

  North–south movement is also surprisingly common, probably reflecting natural global warming. Plants from southern Queensland, such as lemon-scented tea-tree and silky oak, now sprout as far south as Victoria. Umbrella trees from the central Queensland lowlands are now feral as far south as Sydney. A new example that worries me is a large-leafed tree from the tropics, rusty pittosporum (Pittosporum ferrugineum). ‘I planted it twenty-eight years ago and I noticed it becoming feral about ten years ago,’ said Graham McDonald, who runs a native nursery near the Gold Coast. ‘Within a radius of about 2 kilometres of our house I’ve seen thousands of seedlings. The largest I’ve seen are about 5 metres tall. The big ones are starting to fruit. You’ve reached the explosive point then.’ Many are invading the Hinterland Regional Park, which Graham helps manage. ‘We’ve hand-pulled well over four or five hundred in the last couple of years.’ He’s seen currawongs dropping seeds in nearby gardens, where they sprout. ‘Usually people keep them. It’s a free tree.’ He sold this plant until he saw what was happening. ‘I grew it because it was tough and fast-growing, like all weeds.’ If it performs anything like sweet pittosporum, it will become a major invader, especially in northern New South Wales.

  Plants grown for forestry, land repair and aquariums also misbehave. Golden wreath wattle has marched away from mine reclamation sites in eastern Australia but is still promoted in a CSIRO book, Trees for Saltland (1995). Two native aquarium plants – water fern (Ceratopteris thalictroides) and Bacopa (Bacopa monnieri) – have escaped in Western Australia. Near Robe, South Australia, old-timer Arch McArthur told me the golden wattles (A. pycnantha) around the lake had escaped years ago from a tannery. (Wattles yield tannins once used to make leather.) The north Queensland timber tree Queensland maple (Flindersia brayleyana) is taking off in southern Queensland. It’s already a major weed in Hawaii, where it colonises old lava flows.

  So what should we do about all this? For a start, we should rethink what we mean by ‘native’. In my dictionary it means, in part, ‘of one’s birth, where one was born’. Geraldton wax (Chamelaucium uncinatum) is native to sandplains around Perth, and to say that Geraldton wax is native to Australia fudges the facts. Australia is one of the world’s largest countries – a whole continent – and Geraldton wax naturally occupies but little of it. Perth and Sydney stand as far apart as Portugal and Russia, or Switzerland and Arabia. If ex
plorer Nicolas Baudin had claimed Western Australia for France, Geraldton wax in Sydney would count as an exotic (foreign) species. ‘Native’ as a biological category shouldn’t be defined by political boundaries. The World Conservation Union (IUCN) defines an alien (or exotic) species as one that is ‘introduced outside its normal past or present distribution’. This means that all the plants mentioned here are exotic in their new homes.

  The Association of Societies for Growing Australian Plants knows about these problems. It has a web page that goes like this: ‘Don’t Grow Australian Plants! Now that we have your attention . . . Is an organisation whose objective is to encourage the cultivation of Australian plants really suggesting that people should NOT grow those plants? Well . . . yes! Under certain circumstances.’ The association lists some of the rogue plants, emphasising that it doesn’t have a policy of ‘Plant Australian at any cost’. It doesn’t want to promote the spread of ‘ugly Australians’. And it proposes some rules: grow indigenous plants (meaning those native to your area); become familiar with weed lists and avoid problem species; check out unusual plants with experts, and so on. If growing something new, observe it closely, and if it becomes rampant pull it out. ‘If in any doubt . . . DON’T PLANT! It’s not worth the risk!’ Sound advice.

  American landscape architect Joachim Wolschke-Bulmahn is a fierce critic of native gardening, which he links to racism. The Nazis wanted foreign garden plants banned. One of his articles shows Adolf Hitler greeting a leading landscape architect. Wolschke-Bulmahn’s theme can’t be taken too seriously but I’m inclined to agree with his conclusions:

  Advocacy of the use of ‘native’ plants may be a moral response to some of the many environmental problems we have all over the earth. However, there is no reason for a native plant doctrine, nor for the assumption that so-called native plants would serve environmental goals. The segregation of good and bad plants, natives and non-natives, and the condemnation of the latter as aggressive invaders is too simplistic and helps to mask problems rather than engage them.