Ash is a tall domed deciduous tree belonging to the olive tree family. The trunk is olive green-grey and smooth when young, becoming rigid as it matures. The central stem of the compound leaf has 9-13 leaflets in pairs, with one at the tip. The leaflets are pointed and toothed, with hairs on the lower surface.

Behaviour

Ash is a common woodland, hedgerow, park and garden tree found throughout the UK. There are two types of native woodland with ash as a major component in Scotland. The ‘upland mixed ash woods’ and the rarer ‘lowland mixed deciduous woodland’. The former are found, predominantly but not exclusively, in the west of Scotland, whilst the latter is found on base rich to neutral soils in the east where the climate is warmer and drier.

Ash trees can be either monoecious (meaning that both sexes occur on an individual tree) or dioecious, where any one tree has either all male or all female flowers. Both male and female flowers are purple and appear before the leaves in spring, growing in clusters at the tips of twigs. Once the female flowers have been pollinated by wind, they develop into conspicuous fruits, called a samara or ‘key’, consisting of a seed and an attached single wing (2.5-4.00 cm) in length. The samaras hang in dense bunches, falling from the tree in winter and early spring, when they are dispersed by wind, birds and animals. A large mature tree can produce up to 100,000 seeds a year.

Size

• Height: 25-35m; ash is the UK’s tallest (up to 40m) native deciduous tree, when fully mature
• Lifespan: 30-50 years; can reach an age of 250-300 years

Status

Ash dieback, also known as ‘Chalara’, is a fungal disease that seriously threatens the population of Scotland’s ash trees. In 2019, the Forestry Commission Scotland issued guidelines for best management practices for ash woodlands and the Scottish Wildlife Trust published an information sheet, ‘Living with Ash Dieback’ providing recommendations for ash ‘substitutes’ for different sites. The ‘Living Ash Project’, a partnership of Forest Research and the Future Trees Trust, is also investigating levels of Chalara tolerance in other ash species so that, if necessary, they can be crossed with common ash to induce tolerance.

Distribution

Ash, or European ash as it is sometimes known, occurs naturally throughout much of Europe and western parts of Asia. Ash occurs throughout Scotland, from Caithness to the Borders and Dumfries and Galloway. Its range includes many of the larger western islands, such as Skye and Mull, and it has been planted on Orkney, Shetland and Harris. It is scarce or absent from mountainous areas and large areas in the northwest. However, despite being widely distributed, it is quite scarce.

When to see

January to December; in spring, flowers appear from the black buds; in summer the trees are in full leaf and in winter the trees are easily identified by twigs with distinctive black, velvety leaf buds.

Facts

• Ash is one of the last trees to gain new leaves in the spring and amongst the first to shed its leaves in autumn. A characteristic of ash leaves is that they often fall when they are still green.
• Ash trees make the perfect habitat for a number of different species of wildlife. It has been estimated that ash supports 955 species, 45 of which only use ash.
• Ash timber is one of the toughest hardwoods and absorbs shocks without splintering. It is the wood of choice for making tool handles and some sports equipment, including hammers, axes, spades, hockey sticks and oars.
• The genus name, Fraxinus, is the classical name for ash. It is derived from the Greek word ‘phraxix’, meaning separation, which is in reference to the European use of ash trees as hedges. The species name, excelsior, is from the Latin for taller or higher.