Fraxinus excelsior, known as the ash, or European ash or common ash to distinguish it from other types of ash, is a flowering plant species in the olive family Oleaceae. It is native throughout mainland Europe east to the Caucasus and Alborz mountains, and Britain and Ireland, the latter determining its western boundary. The northernmost location is in the Trondheimsfjord region of Norway. The species is widely cultivated and reportedly naturalised in New Zealand and in scattered locales in the United States and Canada. Description It is a large deciduous tree growing to (exceptionally to ) tall with a trunk up to (exceptionally to ) diameter, with a tall, narrow crown. The bark is smooth and pale grey on young trees, becoming thick and vertically fissured on old trees. The shoots are stout, greenish-grey, with jet-black buds (which distinguish it from most other ash species, which have grey or brown buds). The leaves are opposite, long, pinnately compound, with 7–13 leaflets with coarsely serrated margins, elliptic to narrowly elliptic, long and broad and sessile on the leaf rachis. There are no stipules. These features distinguish ash from mountain ash (Sorbus aucuparia) in which the leaves are alternate with paired stipules. The leaves are often among the last to open in spring, and the first to fall in autumn if an early frost strikes; they often fall dull green or develop a bright yellow autumn colour. The flowers are borne in short panicles, open before the leaves, and have no perianth. The female flowers are somewhat longer than the male flowers, dark purple, without petals, and are wind-pollinated. Both male and female flowers can occur on the same tree, but it is more common to find all male and all female trees. A tree that is all male one year can produce female flowers the next, and similarly a female tree can become male. The fruit is a samara long and broad, often hanging in bunches through the winter; they are often called 'ash keys'. If the fruit is gathered and planted when it is still green and not fully ripe, it will germinate straight away, however once the fruit is brown and fully ripe, it will not germinate until 18 months after sowing (i.e. not until two winters have passed). European ash rarely exceeds 250 years of age. However, there are numerous specimens estimated between 200 and 250 years old