Alder
Alnus glutinosa 路 Betulaceae 路 also Common alder, Black alder
A conical to rounded tree of around 28 m with sticky young leaves, dark woody cones and roots that fix nitrogen with the bacterium Frankia. It is the tree for riverbanks, ponds and waterlogged corners where little else will grow, stabilising banks and sheltering otters, siskins and redpolls. Widely planted in riparian restoration and flood-mitigation schemes.
Where it stands
Care
Plant in winter straight into damp ground; no staking needed and it tolerates having its feet in water. Prune in late summer if required. The main threat is Phytophthora alder disease (root rot, bleeding bark lesions, small yellow leaves); avoid moving soil or plants from affected sites. Roughly 60-year lifespan.
Benefits
Good for