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 at elevations of up to 2000 m. "S. aucuparia" appears north of the boreal forest at the arctic tree line; in Norway, it is found up to the 71st parallel north. It has naturalized in America from Washington to Alaska and eastward in Canada and the northeast of the US very successfully. "Sorbus aucuparia" is an undemanding species and can withstand shade. It is frost hardy and can tolerate winter dryness and a brief growing season. The plant is also resistant to air pollution, wind, and snow pressure. "S. aucuparia" mostly grows on soil that is moderately dry to moderately