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 reducta Sorbus reducta Sorbus reducta (铺地花楸), the dwarf Chinese mountain ash, is a species of flowering plant in the family Rosaceae, native to western China (South West Sichuan and North West Yunnan}. Growing to tall by wide, it is a dense deciduous spreading shrub. Each leaf, long, has up to 15 leaflets which turn to brilliant shades of red in the autumn (fall). White flowers in spring are followed by red or pink, and then white berries in autumn. The Latin specific epithet "reducta" means "dwarf", referring to its compact habit. This plant has gained the Royal Horticultural Society's Award of