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
North Fork Mountain pine barren in the Central Appalachians. Other rocky summits, including the summit of Pike Knob, are blanketed by red pine ("Pinus resinosa") forests, here at their southernmost natural occurrences. The Monongahela National Forest has designated of old growth red pine forest on the mountain as the North Fork Mountain Red Pine Botanical Area. Another unusual vegetation type on North Fork Mountain is an elfin forest dominated by yellow birch ("Betula alleghaniensis"), mountain ash ("Sorbus americana"), and mountain holly. The oak-and-pine vegetation of North Fork Mountain contrasts strongly with the more diverse vegetation of the nearby mountains just west of the