Fraxinus is a deciduous tree which under most favourable conditions may reach heights of over 40m with a girth of up to 6m, although under extreme conditions may remain a shrub. The trunk is long and clean leading to a particularly open crown. Younger branches are smooth and are light grey/olive in colour; with age these become characteristically more rugged with close, deep furrows. The wood is hard and elastic and is usually coppiced for its poles. Fraxinus coppices very strongly after felling and seedlings possess a high degree of shade cast by other deciduous trees. The twigs are thick and flatten at leaf joints where black buds are situated opposite each other and at 90° to the next pair. The leaves can reach up to 30cm in length and have many pairs of side leaflets with one terminal leaf; these are accompanied by bunches of winged seeds known as "keys" which aid easy seed dispersal (Wilkinson, 1978).