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The Isle of Arran is home to two species of tree which do not occur anywhere else in the world, the Arran whitebeam (Sorbus arranensis) and the Arran cut-leaved whitebeam (Sorbus pseudofennica).
They are Scotland’s rarest native trees, and in global terms are officially classed as dangerously close to extinction by the WWF.
A perilous existence
Only a few hundred trees of each species exist, clinging perilously to the steep rocky slopes of two remote glens at the north of the island.
The Arran whitebeam was first recorded in 1897, and is thought to have arisen as a natural hybrid between the rock whitebeam (Sorbus rupicola) and the ubiquitous rowan (Sorbus aucuparia).
Uniquely Scottish
The other rare hybrid, the Arran cut-leaved whitebeam, was first noted in 1952. This appears to have arisen from the Arran whitebeam back-crossing with the rowan. Both species were more abundant in the past, but have been forced to retreat to their restricted enclaves as the island was progressively improved for agriculture.
Montane habitat
Small, windswept and stunted, these uniquely Scottish trees are under constant threat from the strong gales and heavy snow storms common in their montane habitat, because the fragile root systems are easily dislodged from the rocky soil.
Where to see the Arran Whitebeams:
Glens Catacol and Diomhan, approximately 3.2km (2 miles) west of Lochranza, Isle of arran.
Images: copyright Archie Miles
