Family: Rosaceae
Common Name: Mountain Ash, Rowan, Whitebeam

This genus includes more than 100 deciduous trees and shrubs, found throughout temperate regions of the northern hemisphere. Many are grown for their colourful display of autumn foliage. The trees are small to medium in height and are of two main types. The rowan or mountain ash types have pinnate leaves, comprising varying numbers of leaflets, while the whitebeams have simple leaves. Mountain ash types colour red and orange in autumn. The terminal clusters of small, white flowers appear in late spring and are followed by red, orange, pink, yellow or white berries in autumn. Many species have edible fruits that have a range of culinary and medicinal uses. The timber of some species is used for carpentry, while the bark has been used in tanning. The fruit is very attractive to birds.

Species

S. americana, zone 2, is a variable species, to 9 m (30 ft), with green, sword-shaped leaflets, grayish green on the under-sides, and dense clusters of flowers, followed by small, round, bright red fruit.

S. aria, white-beam, zone 5, is a European tree, growing to 15 m (50 ft). The simple, oval leaves are green above and felty white below. It produces clusters of very small, bright red, speckled berries. Cultivar 'Malestica' has very large leaves which are pure white on the undersides.

S. aucuparia, rowan or mountain ash, zone 2, is the most commonly grown species. It is an erect tree, to 15 m (50 ft) in its native habitat, usually smaller in cultivation. It has a narrow crown and pinnate leaves which colour rich gold or red in autumn. The dense clusters of flowers are followed by very decorative, small, scarlet fruits. Cultivar 'Fructu Luteo' produces yellowish orange fruit which is not attractive to birds.

S. domestica, service tree, zone 6, grows to around 20 m (65 ft), and is long-lived. It has pinnate leaves and sprays of white flowers, followed by pear-shaped, edible fruit ripening to bright yellow, crimson or orange-scarlet. The bark is used in tanning. This species can be identified by the large fruit.

Cultivation

Sorbus need soil with good drainage, and a position in sun or partial shade. The mountain ash types grow best in acid to neutral soils, while the whitebeams prefer alkaline or chalky soils, and tolerate dry conditions. Propagate from seed sown in autumn, outdoors. Cultivars are budded in summer or grafted in late winter.

Climate

There are species suited to various climatic zones.