The ash is actually a member of the olive family and grows mostly on limestone or deep valley soils, often exceeding 40 metres in height. Its fast growing but becomes hollow-boled and senile at around 200 years old. In the spring the branches have distinctive black buds, and seeds pods form luxurious green sprays which germinate easily in most soils.
The leaves are compound (several leaflets are attached to a midrib) and light green; they are often the first leaves to fall in the autumn, frequently without changing colour. The bark of young trees is smooth and a dull dark grey. Old trees tend to be paler in colour, the bark regularly patterned with flat-topped ridges.