Common alder
Alnus glutinosa
Family · Betulaceae · Harmless
The tree that only grows with its feet in water, holding up the banks of northern rivers. Its roots fix nitrogen, which makes it a fertility factory at the water's edge.
Where it grows
Streams and ditches · Uplands
Also known asblack alder, European alder
In flower
In fruit
How to tell it
A round leaf with a bluntly cut-off tip, sticky when young. In winter it keeps small woody cones on the branches, which no other native broadleaf has. Cut wood turns orange in air.
What it is confused with
No dangerous lookalikes known in the Iberian Peninsula.
What it is for
The wood does not rot underwater and served as piles in foundations, channels and mills. A line of alders in a valley means permanent water.