31 May What Tree? Common Ash
Common Ash (Fraxinus excelsior)
This month we focus on one of our favourite native broadleaves. A species of tree that many of you will have appreciated as you go about your day-to-day activities as it is the third most common tree in the UK, but also one that you will have undoubtedly heard a lot about with the introduction of ash dieback in 2012.
The origin of the name is believed to derive from either Greek ‘phraxis’, meaning hedge where trees or timber were planted to demarcate property, or Latin ‘lightning’ with links to isolated trees attracting lightning. The species name of ‘excelsior’ derives from Latin and means higher or more elevated.
The tree’s common English name, “ash”, traces back to the Old English æsc, which relates to both the tree and the word for birch. These words were also used to mean “spear” in their respective languages, as the wood is good for shafts.
This species is found in a wide range of habitats across the UK. Specimens are found in hedgerows, along roadsides, gardens, churches, woodlands and more. Trees can live for over 400 years, with many coppice stools exceeding 700 years. Trees were previously managed through coppicing for animal fodder and firewood. This species also responds well to pollarding and many ancient and veteran specimens in the UK are as a result of this practice. With the main stem becoming squat and hollow, but supporting new growth from the pollarding point (pollard head). These specimens can support an abundance of different fauna and flora and are integral to our ecosystems.
The relatively thin canopy, in comparison to other native broadleaves such as oak, means that sunlight often reaches ground level and thus provides suitable conditions for a range of ground flora. In a woodland setting and particular ancient woodland, this can consist of dog violet, wild garlic and dog’s mercury. In addition to the above, ash saplings are shade tolerant and are an early-succession species, which in woodland settings can outcompete other native broadleaves (i.e. oak and beech), with trees quickly growing to seek light. This often results in a straight stem which is sought after in timber markets.
Ash is a very durable timber. It has been and continues to be used in construction, woodworking and many other disciplines. Chariots and coach axles were typically made of ash due to their strength and degree of flexibility. It can also absorb shocks without splintering which means it is an ideal medium for making tools and sports equipment. The fluted buttresses of mature ash are highly sought after for Hurling. Similarly to historic uses, ash is still one of the most popular sources of fuel, as they burn for a long time with intense heat.
In British folklore the ash was credited with a range of protective and healing properties. Most of these were related to child health. Newborn babies were popularly given a teaspoon of ash sap. Furthermore, druids staffs/wands were also typically made from ash coppice, which connected the user to the realms of earth and sky. In Norse mythology, the ash was considered the ‘Tree of Life’ (Yggdrasil) with the first man on Earth to have been carved from an ash tree.
An old rhyme indicates that some believed that the timing of the leaf flush may dictate how wet the summer months may be:
“If the oak before the ash, then we’ll only have a splash. If the ash before the oak, then we’ll surely have a soak?”
Unfortunately, the rhyme has no foundation in truth, and as ash generally has a later leaf flush, one could optimistically hope for only a splash when in fact the summer could be extremely wet.
Appearance and Identification
Mature trees can grow to a height of over 30m and generally have a wide oval to round canopy shape. Due to this distinct canopy form they are often easily recognisable in winter from other native trees.
Ash trees generally have a late leaf flush, being one of the last of the native broadleaves to produce leaves. Leaves are pinnately compound and comprise of 3-6 opposite pairs of oval leaflets. Leaves are typically 20-40cm long, dark green on the topside, with a lighter green beneath.
Ash is dioecious, meaning that male and female flowers grow on different trees. However, trees can have male and female flowers on different branches. Flowers are an off-purple and appear before leaves in late-spring/early-summer.
Ash trees produce winged fruits (keys/samaras) in early autumn. These gradually turn brown and persist on the tree throughout winter and are not to be confused with hanging dead leaves, which indicate ash dieback. Seeds are generally dispersed by wind, birds and mammals.
Key characteristics mean that trees are easily identified in winter. Buds are distinctively black and in opposite pairs except for a lone end-bud. Furthermore, in maturity bark is grey and vertically fissured.
Propagation and Control
The main threat to ash is ash dieback (Hymenoscyphus fraxineus). Most ash trees appear to be highly susceptible to the disease which leads to dieback of the tree crown, loss of leaves, bark lesions and eventually death of the whole tree. Often with a weakened physiological state, the trees become susceptible to secondary pathogens (i.e. fungi), which degrades the structural integrity of the trees. Where these are in close proximity to high use zones, they pose a risk to people and property.
A potential threat is the Emerald Ash Borer (EAB) (Agrilus planipennis), which is currently having a devastating effect on ash populations in USA. There are concerns that should this pest reach the UK that any specimens that have survived the onset of ash dieback will ultimately succumb to EAB.
This species thrive in deep and well-drained soil in relatively cool atmospheric conditions. However, this is a hardy species and generally frost and pollution tolerant. While it is a durable tree and can often be found in urban settings, with the prevalence of Ash Dieback, imports were banned in 2012 to try and halt the import of infected material and therefore are not being specified in new landscaping proposals.
Source and Reference Materials
Information detailed in this post has been obtained from the author’s own knowledge and photographic library where possible. Additional source of information and photographs include:
More, D & White, J. (2013). Illustrated trees of Britain and Europe. Domino.
Van den Berk, B.V. (2004). Van den Berk on Trees. Van den Berk Nurseries