Rowan - Caorthann - (Sorbus aucuparia)

Rowan adds colour to woodland throughout Ireland, especially in the hills where it will grow at a high altitude even on rocky ground: its other common name is mountain ash.

Rowan belongs to the genus Sorbus and is a member of the Rose family (Rosaceae).

Rowan (Sorbus aucuparia) is a deciduous tree growing to 25m and flowering May to June.

Lifespan: 100–200 years old.

 

Characteristics

Bark is smooth; grey to silver-grey. Buds are purple and downy. Leaves are pinnate; each is made up of five to eight pairs of leaflets plus one terminal leaflet. Each leaflet is long, ovoid and strongly toothed (3–6cm), hairless above and downy below when young.

Rowan is a hermaphrodite: it has ‘perfect’ flowers with both sexes being represented in one flower. Flowers grow on woolly stalks in dense umbel-like heads. Each has five creamy-white petals (3–5mm) and many stamens. Fruits are scarlet, rounded berries (6–9mm) containing one or two seeds. Rowan is insect pollinated.

Rowan tree
Rowan leaves

Distribution

Native in the UK and in northern and western Europe.

Commonly found in dry woods, on neutral to acidic soils and in upland areas; especially in the north.

Often planted as an ornamental tree in green spaces and residential areas due to its striking autumn berries, coloured foliage and relatively small size. Many cultivated forms exist with different coloured flowers and berries.

Rowan is one of a number of Sorbus species native to the UK. Others include the wild service tree (Sorbus torminalis) and the Common whitebeam (Sorbus aria).

Human value

The wood is pale yellow-brown with deeper brown heartwood. It is strong, hard and tough but not very durable. The tree is too small to create large diameter timber for industry, but is sometimes used in turnery, furniture, craftwork, tool handles and engraving (similar uses to apple timber).

Rowan berries are sour but rich in vitamin C. If sweetened they make a good jelly.

Rowan is sometimes called ‘mountain ash’ because its leaves are similar to the compound leaves of common ash and it grows in high elevations. The two trees are not related, however, and have no other features in common.

Rowan berries
Rowan flowers

Wildlife value

A number of micro-moths feed on the leaves of rowan, as do the larger Welsh wave and autumn green carpet moths. The larvae of the apple fruit moth feed on its fruits.

Many pollinating insects are attracted to the flowers, and birds love the berries especially blackbird, mistle thrush, redstart, redwing, song thrush, fieldfare and waxwing. By eating the fruits the birds help to separate the seeds and disperse them.

Rowan has many lichen species associated with it; particularly the Graphidion community of lichens which grow on smooth-barked trees.

Rowan is an important understorey tree in upland oakwood, upland mixed ashwoods and native pine woodland; all of which are priority habitats under the UK Biodiversity Action Plan.

Management

A hardy, light-loving pioneer species able to thrive at elevations of over 1000m above sea level and cope with frost and exposure. It grows well on well-drained to slightly moist soils of poor to medium fertility. It is not suited to wet or waterlogged soils or very poor nutrient conditions. Rowan is a deep-rooted tree requiring good soil depth.

The fruits ripen July to August. Rowan is easily grown from seed, softwood cuttings or grafting techniques. Seeds must be extracted from the flesh and then pre-treated before planting in March.

Rowan can be susceptible to fireblight (Erwinia amylovora) and may be affected by silverleaf (Chondrostereum purpureum). It can suffer from heavy deer browsing.

Rowan leaves close-up

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Illustrations © Reader’s Digest Association, Inc.
Photographs © Debbie Cotton
All Information provided by Royal Forestry Society

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