Arran whitebeams complex fashion, which involved the common whitebeam ("Sorbus aria") giving rise to the tetraploid rock whitebeam ("Sorbus rupicola") which is still found on Holy Isle. This species is able to survive at higher altitudes and therefore occupies a less competitive niche with fewer tree species able to tolerate the harsher conditions. The rock whitebeam interbred with the rowan / mountain ash ("Sorbus aucuparia") to produce the hybrid, a fertile separate species the Scottish whitebeam ("Sorbus arranesis") which grows well in this zone of reduced competitive growth at higher altitudes. The bastard mountain ash ("Sorbus pseudofennica") arose from a further cross
Sorbus anglica cliffs, quarries and rocky hillsides. It appears to be indifferent to soil pH. Occasional specimens are known from oak woodland. Research suggests Sorbus anglica developed from a cross between Sorbus porrigentiformis and Sorbus aucuparia. Sorbus anglica Sorbus anglica, the English whitebeam, is a species of whitebeam tree in the family Rosaceae. It is uncommonly found in Ireland and the United Kingdom, with an entire British population estimated at about 600 individuals. Sorbus anglica grows as a small tree or shrub, often with multiple stems. The leaves are broader than most other Sorbus, with lobes whose bases are incised up to