Scientific Name
Sorbus aucuparia ‘Cardinal Royal’
The European mountain ash is usually called rowan in Europe and is not a true ash of the genus Fraxinus, like the many ash trees in urban forests threatened by the emerald ash borer. This tree has an enormous range across the northern latitudes of Europe and Asia. At the western edge of its range, it is native to Iceland and extends east through Ireland, Britain and all of Scandinavia to the Arctic, continuing across Russia while largely avoiding the steppes and deserts of central Asia, all the way to the Pacific Ocean.
European mountain ash can clearly tolerate climates with temperatures down to minus 40 degrees Fahrenheit, but it may struggle where summers are as hot as they are here. However, the cool summer nights in Colorado, compared with those in the eastern United States, are more favorable to the species. Even so, it benefits from shade during much of the day, making its location at Regis especially well suited.
European mountain ash trees, including the ‘Cardinal Royal’ cultivar, typically grow to around 30 feet tall, though this cultivar has a more upright and somewhat narrow symmetrical form. The dark bluish-green leaves are compound with nine to 15 leaflets, and the terminal buds are large and woolly. The foliage of this cultivar usually turns rust red in the fall. In May, the tree produces white flower clusters 3 to 5 inches in diameter, followed by small bright red fruits in August or September that are quickly consumed by birds. European mountain ash is not a long-lived tree, with 80 years considered a normal life span.