Do we still need plant hunters?

by Rhiannon James

credit: Diego Cupol

Plant hunters of the past became the swashbuckling heroes of their age: their extraordinary adventures in pursuit of rare and exquisite plants captured the public imagination. They were feted by society, and immortalised in fiction.

In her book The Brother Gardeners, Andrea Wulf says that when the Endeavour returned to Britain in 1771, it was Joseph Banks, the plant hunter, rather than Captain Cook who was in demand amongst both aristocrats and scientists, and “celebrated as the real hero of the most successful expedition of the century”.

Today though, plant hunters are more like the secret agents of the horticultural world: their adventures are still enthralling but significantly lower-profile. “Don’t ask, don’t tell,” is the situation said James Hitchmough, Professor of Horticultural Ecology at The University of Sheffield and one of the designers responsible for the Olympic Park gardens.

The reason for all this secrecy is that plant hunting can now attract as much controversy as acclaim which, according to Hitchmough, comes down to two things. “There’s what you might call the political or ethical issue – this is the idea that plant hunting is politically-incorrect theft, especially for post-colonials with a left-leaning perspective,” he said. From the legal point of view, the 1992 Rio Convention on Biological Diversity established the rights of sovereign states over the plants growing in their country although not all choose to enforce this. “And then there’s the ecological conservation view which is very much that plants should stay where they evolved and not move to other places where they might do terrible things such as escape,” said Hitchmough. Japanese knotweed and Rhododendron ponticum are two famous examples of garden escapees that have caused havoc, although native and naturalised invasives probably create more problems in the UK. “Cacti scavengers who clear whole hillsides of plants don’t help either,” he said.

All of this, along with the question of whether gardeners really need any more new plants, especially given the current enthusiasm for native wildflowers, is enough to create a crisis in any career. So on a grey and drizzly day this month, some of the country’s most respected plant hunters gathered at the Garden Museum in London to discuss the point of their profession in the 21st century.

Firstly, it emerged there’s still plenty of potential for plant discoveries to equal those of earlier eras. Plant hunters such as Sue and Bleddyn Wynn-Jones, owners of Crûg Farm Plants nursery, who have braved everything from gun-toting opium field guards to sleeping snakes in their pursuit of new plants, are proof of that. “We opened up a small nursery in 1991 and even in that first year, we decided we wanted to go out and look for more interesting plants,” said Bleddyn. The pair have travelled all over the world but just in their trips to the mountains of northern Vietnam, they have discovered everything from a strongly-scented new species of that shady city garden favourite Sarcococca (wild population: one) to an amazingly beautiful epiphytic lily. Even more excitingly, there’s still much more to come: a recent study led by the University of Oxford has suggested that 15% to 30% of the world’s flowering plants are yet to be discovered.

New, quirky and beautiful plants also keep gardeners enthused, and this, Hitchmough said, helps our environment. “The engine of collecting, of new plants, drives the creation of hyper-diverse gardens which support native wildlife,” he said.

But, it was argued, it’s not just new plants that we need, but also more diversity in the ones that we’ve got. Plants’ ability to thrive in our current, or indeed future, climate is not down to species so much as to individual specimens, according to Hitchmough. He gives the example of Liquidambar styraciflua which struggles in the north of Britain. This, he said, is because the original plant material was collected in the wrong place: at low altitude and at a too southerly latitude. If it had been collected from the White Mountains, where the US’ northernmost population of Liquidambar thrives in a climate much closer to Britain’s, it would have been a different story. “The trees may look the same but they’re genetically able to do different things,” he said. Gladiolus cardinalis tends to suffer winter damage in the UK, but a population at 1,900m on the Matroosberg mountain in South Africa can happily survive -20°C winters. “Fitness is not defined at the level of a species, fitness is defined at the level of individuals and populations of individuals,” he said.

Diversity within species will become even more important as the climate changes, he said. In less than 40 years, if the models are correct, London will have the climate of Bordeaux. At the same time, cities are expanding and condensing, raising temperatures even further in a phenomenon known as the urban heat island effect. “Using plant technology, watering, that’s the nineteenth century, that’s the past: the future is about using genes,” he said. “If you desperately want to grow silver birch in the future, you need to get yourself to the warmest, driest summer populations.”

Greater exploration in this area should also help when it comes to new forms of urban planting. Extensive green roofs are becoming one of the most important ways of greening cities and require plants that can thrive in a thin, dry layer of material but also survive wet British winters. So Hitchmough is excited about a population of the strikingly beautiful Delosperma sphalmanthoides at 1,700 metres in South Africa, which can deal with both wet and cold. “Imagine buildings studded with them, whole skins of buildings,” he said.

Plant hunters also stress their role in conservation. Crûg Farm Plants, for example, won the RHS President’s Award at the Chelsea Flower Show last year for its role in preserving rare plants in danger of deforestation. Wynn-Jones described last year’s trip to northern Vietnam as “the serious business of gathering seed before it disappears forever”. The first area he went to had changed dramatically since his last visit. “It was highly degraded and all the original trees had been cut down,” he said. “It was very sad that as the day progressed, the noise of chopping got louder and louder until it was a mass of sound, even though we were in a national park.” Then towards the end of the trip, Wynn-Jones came across some Tsuga trees discovered during a previous visit and thought to be the largest ever recorded in the wild. “Most had been felled and just left there to rot: there was no use for the timber or anything. They were just planting a cash crop underneath,” he said.

Nonetheless, the risks of plant hunting do need to be considered, said Dr. Tim Entwisle, Director of Conservation, Living Collections and Estates at the Royal Botanic Gardens, Kew.

In addition to the possibility that plant discoveries may turn out to be invasive, there is also the danger of importing pests and diseases into the country. Entwisle noted the example of Fuchsia gall mite which was transported to Jersey in some rooted cuttings posted from South America, travelled to the mainland in 2007 and is now spreading through British gardens.

The identification of new and rare plants can assist their conservation but also paradoxically threaten their chances of survival, if they become desirable targets for thieves. Even visits from plant enthusiasts who are happy to look but not touch can cause problems in rarely-visited territory. Entwisle gives the example of the Wollemi pine, which was thought to have been extinct for two million years until it was discovered in a canyon north of Sydney. The trees’ location is a secret and only a few researchers have been allowed to see them in the wild. Fear of fire was one reason for this controversial decision. “The trees are also quite susceptible to phytophthora and that can easily be brought in on the feet of people coming into the area,” says Entwisle. “It was also thought that with only 100 individuals and not that many seedlings, unscrupulous collectors could come and take them.” The fact that the tree is propagated and available to buy also means there’s less incentive to take specimens from the wild. Many discoveries, however, are not this well guarded.

And then there’s the thorny issue of helping the country of origin to benefit from the discovery, collection and use of these plants. The Convention on Biological Diversity enshrined the principle of fair and equitable sharing of benefits, but did not create a mechanism for this to happen, which has created uncertainty and confusion. Nevertheless, efforts are being made in this area. Wynn-Jones said: “After our first expedition to Vietnam in 1999, Dan Hinkley volunteered to open his garden, which was Heronswood at the time, and was able to donate the money from this to a university herbarium in Hanoi. From that money they were able to fill the herbarium. They showed it to us in 1999, and it had one tin, the following year we went back and it was pretty full, which was very encouraging.” The Wynn-Jones themselves work closely with botanical institutions in host countries. The Royal Horticultural Society meanwhile, has recommended providing benefits in kind such as training so source countries are better equipped to manage their own natural resources.

In the end perhaps, the heroes of 21st century plant hunting won’t be intrepid individuals but ground-breaking cross-border teams.

The Plant Seekers exhibition, which tells the history of plant hunting using treasures from the RHS Lindley Library, can be seen at the Garden Museum until Wednesday 24th October 2012 

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