57 North

To the best of our understanding, left: common, or black alder (Alnus glutinosa); middle pair: red alder (Alnus rubra); right: grey or european alder (Alnus incana).

The common alder is a true native, the grey alder was introduced to Britain a couple of hundred years ago, and the red alder is an American tree that has been grown in plantations in Britain, especially in the West of Scotland.

The common alder has a leaf which indented at the tip and which has seven or so spines. The grey alder has leaves which should have grey hairs on the underside (this was more visible in life than comes across in these photos, but the colour effect wasn’t greatly strong). There are also more spines. The red alder should show rust coloured hairs on the underside. The edges should also be ‘minutely but sharply rolled under’. This was very visible in the fresh leaves, but the grey alder leaves began to do this quite soon after being picked.

The red alder fails quite soon in British conditions and ‘bigger trees are only in a few gardens’. Ours are about three metres tall and are thin and unhealthy looking with small and sparse leaves. They were probably planted when the house was built.