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 larger forest trees. In Central Europe it often grows in association with red elderberry, goat willow, Eurasian aspen, and silver birch. The plant is highly flammable and tends not to accumulate plant litter. Other species of the genus "Sorbus" easily hybridize with "S. aucuparia" and hybrid speciation can result; hybrids include "Sorbus × hybrida", a small tree with oval serrated leaves and 2 to 3 pairs of leaflets, which is a hybrid with "Sorbus × intermedia", and "Sorbus thuringiaca", a medium-size tree with elongated leaves and 1 to 3 pairs of leaflets that are sometimes fused at the central vein,