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
Mountain Ash, Rhondda Cynon Taf Mountain Ash, Rhondda Cynon Taf Mountain Ash () is a town (and former community) in the Cynon Valley, within the County Borough of Rhondda Cynon Taf, Wales. At the 2001 census, Mountain Ash had a population of 7,039 increasing to 7,374 at the 2011 Census. The Mountain Ash geographical area incorporates and includes the districts and villages of Cefnpennar, Cwmpennar, Caegarw, Darranlas, Fernhill, Glenboi and Newtown. Mountain Ash lies within the historic county boundaries of Glamorgan. The town lies about 4.5 miles south of the town of Aberdare and approximately 19 miles northwest of Cardiff. The village and community of