Alder
Alnus glutinosa
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The tree that holds the riverbank together — and the only broadleaf here with little woody cones.
A medium-sized deciduous tree of wet ground, lining the Nith and its tributaries, and found in carr woodland, ditches and loch margins. The leaves are dark green, rounded and notched at the tip rather than pointed, and the twigs carry both purple catkins in late winter and small, hard, woody cones that persist through the year — the only native broadleaf with cones like these.
Behaviour
Alder roots carry nodules containing bacteria that fix nitrogen from the air, so the tree improves the soil it grows in and can colonise poor, waterlogged ground. Its timber does not rot underwater and was used for piles, clogs and sluices. The winter cones are an important seed source for siskins and redpolls, which hang from the twigs in flocks to feed.
When to see it
Quick facts
- Family
- Birches (Betulaceae)
- Height
- Up to 25 m
- Status
- Native; characteristic of riverbank and wet woodland
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