Fraxinus excelsior (European ash)

European ash is native to Europe and Iran.

Black buds of European ash

Overview: Deciduous tree up to 40 m tall with grey, hairless branches. Dormant buds are black.

Leaves: 20–25 cm long, divided into 9–13 toothed leaflets, dark green above and paler beneath. Leaves are in opposing pairs.

Flowers: Unisexual or bisexual (on the same or separate trees), in dense clusters, appearing before leaves. Individual flowers are small, inconspicuous, with no petals or sepals, and wind-pollinated.

Fruits: Dry, one-seeded, winged fruits up to 4 cm long. Borne in bunches and often referred to as ‘keys’.

European ash is under threat from ‘chalara ash dieback’, which is caused by the fungus Hymenoscyphus pseudoalbidus (often referred to as Chalara fraxinea in the popular literature). The disease causes dieback of the crown and loss of leaves and can lead to death of the tree. A wide range of Fraxinus species have reportedly been infected with this disease, although F. excelsior is the most severely affected species.

Trees reported dying in large numbers in Poland in 1992 are now believed to have been infected with this newly identified pathogen. It has since spread across northern, western and southern Europe, causing widespread damage to ash populations, and infecting an estimated 60–90% of Denmark’s ash trees since 2007.

Young infected ash trees often die quickly, whereas older trees tend to resist the pathogen for longer. There is no known cure and control is therefore limited to reducing the severity of symptoms and spread of the disease, for example by controlling imports/exports of ash plants and seeds and their movement within a country.

Fraxinus excelsior 'Aurea' (golden ash)

Widely used for its timber, European ash produces wood that is both strong and elastic. It is particularly good at withstanding sudden shocks and has therefore been used for a wide range of sporting goods, such as tennis racquets, hockey sticks, cricket stumps and billiard cues, as well as for tool handles and walking sticks.

It was formerly used for wheel-making and is still used to make the frames of Morgan cars. European ash has long been coppiced (repeatedly cut back to a short stump in order to harvest the many new shoots that sprout from it). In Suffolk (UK) there is a still-productive, coppiced tree estimated to be over 1,000 years old.

Cultivated as an ornamental in parks and large gardens, European ash is a useful shade tree that tolerates pollution and exposed sites. Cultivars available include:
• Fraxinus excelsior ‘Aurea’ (golden ash) – slow-growing with yellow leaves
• F. excelsior ‘Crispa’ – dark leaves with ruffled margins
• F. excelsior ‘Jaspidea’ – up to about 20 m tall with yellow leaves and yellow winter shoots (awarded the Royal Horticultural Society’s AGM)
• F. excelsior ‘Pendula’ – with an umbrella-shaped crown of pendulous branches (awarded the Royal Horticultural Society’s AGM)

European ash has been used in traditional medicine. Its bark was once used to treat fevers, its buds were used as a slimming aid in the UK, its leaves were used to treat gout, and its sap was used as a remedy for earache and warts.

In18th century England, ash leaves were used to adulterate tea. Ash leaves have been used as cattle-fodder in Scandinavia.

In Scandinavian mythology, the tree of the world was an ash called Yggdrasil. It was said that its roots reached down into hell while its crown touched the heavens, its huge trunk connecting the two. Odin, considered to be the greatest of the gods, was said to have carved the first man from its wood.

European ash was regarded as a healing tree in Britain up until the end of the 18th century. In Hampshire (UK), it was believed that a child with broken or weak limbs could be healed by passing the child naked through the split trunk of an ash, which would then be plastered with loam and bound back together. If the split trunk then grew back together it was believed that the child would be cured.

In the past, burning of ash logs was thought to drive evil spirits from the room. There has been a long-standing belief dating back to the writings of ancient Roman author, Pliny the Elder, that ash-sticks can be used to repel snakes or to protect against snake-bite. Some thought a single blow with an ash-stick would kill a snake, whereas others believed that simply drawing a circle around it, or just carrying an ash-stick, would protect the user.

The Millennium Seed Bank Partnership aims to save plant life worldwide, focusing on plants under threat and those of most use in the future. Seeds are dried, packaged and stored at a sub-zero temperature in our seed bank vault.

Two collections of Fraxinus excelsior seeds are held in Kew’s Millennium Seed Bank based at Wakehurst in West Sussex.

See Kew’s Seed Information Database for further information on Fraxinus excelsior seeds.

Fraxinus excelsior (European ash)

There are over 200 specimens of Fraxinus excelsior in the collections at Kew and Wakehurst Place. These include a range of cultivars grown for their horticultural merit. The main ash collection is grown along either side of Princess Walk at Kew. European ash can also be seen growing in Kew’s Conservation Area.

Dried and alcohol-preserved specimens of Fraxinus excelsior are held in Kew’s Herbarium, where they are available to researchers by appointment. Details of some of these can be seen online in Kew’s Herbarium Catalogue.

Specimens of wood, bark and sap of European ash, in addition to a wooden garden dibber and boomerangs made from it, are held in Kew’s Economic Botany Collection, where they are available to researchers by appointment.

No symptoms of ‘chalara ash dieback’ have so far been found in the ash trees at Kew. Fraxinus specimens for the collections are not imported from external commercial nurseries in the UK or Europe.

Kew staff are encouraged to be vigilant whilst working in the Gardens and look out for the symptoms on ash trees. A pro-active monitoring programme will be implemented to spot when this disease arrives and record any effects that it has on the collections.

Search Kew’s science databases for more information on Fraxinus excelsior

Rhizotron and Xstrata Treetop Walkway – Fraxinus excelsior

See Kew's profile on Hymenoscyphus pseudoalbidus (chalara ash dieback fungus)

Read Kew's news article on 'chalara ash dieback' (5 Nov 2012)

Forestry Commission Pest Alert – ash dieback disease

Forestry Commission – chalara dieback of ash