Leaving the small African farmhouse behind, we follow the two local men into a patch of thorny scrubland. This is an area of Kenya that has been badly hit by drought: crops have withered and failed, people are digging for water in the dusty riverbeds. One of the men turns. ‘That’s it — over there!’
Up ahead is a strange looking tree, something like a spiky pinkish succulent stuck on top of a slim-trunked yucca. It sits in three adjacent clumps, surrounded by the more familiar trees of Kenya’s eastern bushlands. With our quarry in sight, the three botanists behind me come speeding up. Tim Pearce from Kew’s Millennium Seed Bank is clearly excited. ‘It’s a tree aloe,’ he says. ‘Almost certainly a new species.’
The plant has recently flowered, so Tim’s colleagues from Nairobi’s National Museum, botanist Paul Kirika and research scientist Dr Patrick Muthoka, start to search around for seeds. Meanwhile, the two locals who have brought us here begin to tell me a little of how this rarity arrived on their land.
‘Some years ago, it was in the bush near the river,’ says the younger man, Julius Mathenga. ‘But that land was being cleared for growing crops. The people were going to cut it down and burn it, but my grandfather decided to move it here, on to our farm.’ I ask why he did that. ‘In those days, people said that this tree would keep witchcraft away.’ Saved from becoming cabbage manure, the tree appears to be doing well. ‘Are these the only known specimens?’ I ask Tim. He shakes his head. ‘We don’t know. They might be.’
Paul and Patrick’s excitement has become subdued: they have failed to find any seeds. ‘It’s almost certainly new to science but there are no seeds here — none.’
We take photographs, a cutting and a GPS reading, then pay the farmer a few shillings for his trouble and move on. In the car, as we drive east, Paul tells stories that show just how narrow the gap between extinction and salvation can be for the world’s plant rarities.
‘We knew of one particular tree only from specimens taken by early botanical collectors. No one alive had ever actually seen one. In fact we thought it was extinct. But then the museum had a call from someone claiming to have seen a single tree living near the coast. When we finally reached the place, someone had just cut the tree down.’ He smiles ruefully. ‘There were some old fruits on the ground which we picked up, but none had viable seed. So now — finally — it is definitely extinct.’
In Kenya, the pressures on the natural environment are all too clear to see: population growth has rolled back the wilderness right across the Central Highlands in the past three decades, leaving both flora and fauna in isolated pockets. Forest cover for the country has dropped alarmingly in the same period, from about ten per cent to below two. Inevitably, wildlife has suffered enormously with migration routes threatened and many of the renowned national parks becoming island sanctuaries. However, while animals can move away from human development, plants are victims of slash-and-burn agriculture, over-grazing and building. Global warming and drought have also struck, placing further pressure on both human population and environment. In such a dire situation the work of plant hunters from seed banks in Kew and Nairobi has become a race against time.
Kew Gardens’ Millennium Seed Bank, based in Sussex, aims one day to hold the seeds of at least a quarter of the world’s known plants and, this month, it is scheduled to reach its initial landmark of a tenth of the world’s wild species. The idea is to provide not only an insurance policy against extinction but also to supply seeds and information for research and restoration projects all over the world.
‘We’ve banked about 2,000 species in Kenya,’ says Patrick. ‘That’s about a third of our flora. There are probably about 2,500 more that produce seed and could easily be collected.’
Finding these plants, collecting sufficient seed at the right time, then banking it and working out the complexities of its germination requirements can be costly and time-consuming. In the meantime, no one knows how many species might have been lost, but Tim has a good example of how collecting seeds can help rescue a species. ‘In 2008, in Victoria, Australia, seed was collected from a bush — nothing spectacular, just a small, rare evergreen shrub. But in the bush fires later that year, it was destroyed. Now, using the seed collected, they are reintroducing the species.’