Sorbus arranensis rupicola") which is still found on Holy Isle. This hybrid species interbred with the rowan/mountain ash ("Sorbus aucuparia") to produce "S. arranesis". The bastard mountain ash ("Sorbus pseudofennica") arose from a further cross between "S. arranensis" and the mountain ash ("S. aucuparia"). Smart showed by using physical characteristics that the species were separate and not a result of random variation. Some overlap does however occur and this suggests that some hybridising may occur between the two species. Sorbus arranensis Sorbus arranensis, sometimes referred to as the Scottish or Arran whitebeam is a species of plant in the family Rosaceae. It
Sorbus aucuparia but wide and the plant often grows multiple trunks. A trunk is slender and cylindrical and reaches up to 40 cm in diameter, and the branches stick out and are slanted upwards. The bark of a young "S. aucuparia" is yellowish gray and gleaming and becomes gray-black with lengthwise cracks in advanced age; it descales in small flakes. Lenticels in the bark are elongated and colored a bright ocher. The plant does not often grow older than 80 years and is one of the shortest-lived trees in temperate climate. Wood of "S. aucuparia" has a wide reddish white sapwood and