Sorbus White Swan - Arnold Rowan

Sorbus 'White Swan' is a hybrid mountain ash that stands out for its white fruits, very rare among mountain ashes. It is also planted for its natural appearance, its white spring flowering visited by bees, and its magnificent autumn colours. Extremely tolerant to different types of soil and exposure, it just needs to be protected from stagnant moisture, aridity, and dense shade.

Sorbus 'White Swan' belongs to the important Rosaceae family. Sorbus x arnoldiana is a hybrid resulting from cross-breeding between Sorbus aucuparia (the rowan tree) and S. discolor, native to northern China. This hybrid was described in 1920 by the great botanist Alfred Rehder, who was curator at the Arnold Arboretum in the United States for many years.
The 'White Swan' mountain ash can reach a height of 6 to 8 m and a spread of about 3 to 4 m. Its trunk carries a conical and narrow crown. Its growth is moderately fast. The leaves are composed of an odd number of green leaflets. They turn a beautiful red in autumn before falling. The flowering, which occurs from May to June, takes the form of small white flowers grouped in inflorescences called corymbs. These flowers give way to white fruits that ripen in September. The smooth, grey, and shiny bark adds an additional aesthetic dimension to this tree, even in winter.

The 'White Swan' mountain ash can be planted as a specimen to highlight its elegant silhouette and seasonal colouring. When planted along a wide avenue, it is pleasant to look at and attracts birds. For example, it can be paired with purple birch (Betula pendula 'Royal Frost'), star magnolias, Amur maple (Acer ginnala), and large dogwoods like Cornus mas (European cornel).