NEW ARRAN WHITEBEAM
A unique tree has been discovered on the Isle of Arran. Thanks to a major research project by Scottish Natural Heritage (SNH), Dougarie Estate and the Royal Botanic Gardens in Edinburgh, two specimens of the newly-named Catacol whitebeam (Sorbus pseudomeincichii) have been found on the island. The discovery brings the total number of tree species unique to Arran to three.
“It has long been recognised the endemic whitebeam is one of the botanical highlights of Arran,” says Graeme Walker, area officer for SNH. “These are unique trees which are not found anywhere else in the world, but investigations into the genetics of the trees by the University of Bristol show the population is much more diverse than previously thought.”
The new tree – a cross between the native rowan and whitebeam - joins the Arran whitebeam and the cut-leaved Arran whitebeam, which are also crosses between rowan and different species of whitebeam. It was previously thought the former was a simple hybrid between the rock whitebeam and the native rowan, while the latter was a back-cross between the Arran whitebeam and rowan. Recent research shows these crosses are not one-off events, however, and further back-crossing has taken place. As a result, the Arran population is now regarded as a complex of hybrids which is probably gradually evolving towards a new type of tree and will look very similar to a rowan.