Major milestone reached on Scottish island in saving rare tree from extinction
The whitebeam has been around on Arran since the Ice Age - and now there is a fighting chance they are to return in significant numbers
Until recently, just three of the most endangered trees in the world grew on a Scottish island - and now hundreds are coming to life.
A major milestone has been reached in Glen Rosa on the Isle of Arran in efforts by National Trust for Scotland to grow numbers of the exceptionally rare whitebeam species after batches of young trees arrived on the island.
The Isle of Arran is home to three species of whitebeams, which have been endemic to the island since the last Ice Age.
The population of the extremely rare Catacol whitebeam in the wild is thought to be down to three.
Meanwhile, there are just 407 Arran whitebeam known to be growing in the wild on Arran and 436 cut-leaved whitebeam.
NTS has adopted the whitebeam as a priority species for conservation, with the charity now propagating all three whitebeam species to plant them in Glen Rosa, with the aim to continue restoring numbers of the trees and protect them from extinction.
More than 500 young whitebeam plants arrived at the National Trust for Scotland’s tree nursery at the Brodick Estate in August.
They are the product of two and a half years of painstaking work by small Aberdeenshire-based biotechnology laboratory In Vitro Microplants, who have successfully micro-propagated the plants using plant material taken from Glen Rosa in the Goatfell area, which is cared for by the Trust.
Micropopagation is a technique used to rapidly multiply plants by growing small pieces of plant tissue under laboratory conditions. Most of the healthy saplings are of the very rarest species of whitebeam, the Catacol whitebeam.
The saplings will spend a year in the tree nursery on the Trust’s Brodick Estate, where they will acclimatise to the Arran environment and continue their development. They will then be planted out in Glen Rosa within a fenced area, where they will be protected from deer grazing.
Seeds and cuttings have been taken from mature trees to enable propagation of these rare species and shared with partners, including the Royal Botanic Garden Edinburgh and the Woodland Trust.
These partners have successfully grown identical specimens, saplings and seedlings for off-site conservation. Future work will include genetic surveys of the population to ensure genetic diversity among the propagated trees, reducing the likelihood of risk from disease.
The propagation of the rare whitebeams is part of a wider project, which began in 2018, to regenerate woodland in the Goatfell landscape. Funded largely by players of Postcode Lottery, this work seeks to restore habitats across Glen Rosa that have been degraded through over-grazing and to increase biodiversity in the glen.
With natural regeneration not achievable due to the paucity of existing woodland in Glen Rosa, the project has focused on widespread replanting to provide a fertile seed source.
Over 44,000 trees, a mixture of birch, oak, hazel, holly, willows, aspen, alder and whitebeams, were initially planted, before the April 2025 wildfire destroyed approximately 23,7000.
Over 30,000 more trees have been planted since the wildfire and the project aims to plant an additional 5,000 trees in Glen Rosa by 2029.
Kate Sampson, National Trust for Scotland Senior Ranger, said: “This is an enormous step forward in our efforts to regenerate the woodland here on Arran, notably to ensure the future of the extremely rare Catacol whitebeam, which is not found anywhere else in the world.
QThrough this monumental propagation effort, we’ve been able to increase over a hundredfold the population of this endangered tree. However, reforestation requires sustained effort over many years, and these saplings have a challenging journey ahead of them to thrive in Glen Rosa.
“Our young trees are increasingly threatened by wildfire, the devastating impact of which we faced in the wake of the April 2025 wildfire. Thank you to all who supported our wildfire appeal, which raised a staggering £58,000, allowing us to support the recovery of our delicate young saplings.
“ We estimate that around a third of the trees burnt in the wildfire have since started to resprout from their roots, offering a potent symbol of hope for woodland regeneration in the glen.”
Jeff Waddell, the National Trust for Scotland’s Head of Nature, said: “It’s with enormous thanks to the generosity of our members and supporters, including players of Postcode Lottery, that we’re able to continue our work to safeguard and grow the population of rare whitebeam trees in the glen, ensuring all can enjoy this wonderful piece of Scotland’s natural heritage for generations to come.”
Postcode Lottery players have now raised over £4.3 m since 2014 to support NTS.
Other supporters of the project include the Auchrannie Charitable Trust, Whitebeam Homes SCIO, Arran Active, and Corrie Homes.
The cut-leaved whitebeam and the Catacol whitebeam are on the British Red List of critically endangered species, while the Arran whitebeam is on the British Red List of endangered species.
All three species have been identified in the Trust’s Plan for Nature as among the 26 priority species for which the Trust has special responsibility to take conservation action.
These include mountain plants, such as the stunning alpine gentian, and seabirds, as well as hen harrier, red-necked phalarope, corncrake, Greenland white-fronted goose, narrow-headed ant, willow tit and Scotland’s rarest fish: the vendace.
The list also features the slender Scotch burnet moth and three species of trees, including the Arran whitebeams, which occur nowhere else in the world.
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