Smooth grey bark in young trees. Becomes fissured as the tree matures. Buds are black (the only tree in Ireland with this trait). Leaves are in 3 to 6 pairs of leaflets with a distinct point. The leaves appear at the end of April and mostly in May.
Do not confuse it with the Elder. Elder and Ash are often confused because of their similar leaves. Some sighting of Ash budburst in 2007 turned out to be Elder.