The Italian alder tree is the most common alder tree to be found in cities, because it is the only one that can survive a long way from ponds or fresh water rivers. It is much like the grey alder and varies from the common alder by the shape of its leaves. The bark is not dissimilar to that of the lime tree, except that the alder always looks tidier. The leaves also are not dissimilar. What makes the alder distinctive are its nuts (catkins: see tree identification section) which remain on the tree for most of the summer and throughout the winter. They only fall in the early spring and are immediately replaced by the next years batch.