Alder
(Alnus glutinosa)
The alder is a common deciduous tree in the UK, growing along riverbanks and in damp woodlands. Recognisable by its serrated, rounded leaves and catkins, the alder thrives in wet environments, making it a familiar sight in places like Killearn Glen, where it may once have formed part of a managed woodland.
Alder trees can grow up to 25 metres tall and live for around 60 years. Flowering early in the year, from February to April, they produce both male and female catkins on the same tree – a perfect symbol of balance in Celtic mythology. When the catkins drop into water, they float and are carried downstream, allowing seeds to spread widely along river systems.
Fascinating fact:
Alder has made its mark in music: it’s been the wood of choice for electric guitar bodies, including classic Fender models, since the 1950s.
Alder wood has some remarkable qualities. It does not rot in water, which has made it highly valuable for centuries – from boatbuilding and canal linings to the foundations of Venice, which still stand on alder piles.
The tree is important ecologically too. It forms a special partnership with nitrogen-fixing bacteria in its roots, which helps to improve soil fertility. This makes it a valuable pioneer species, paving the way for other plants to thrive. Alder catkins are a vital early source of nectar and pollen for bees, while its leaves feed the caterpillars of several moths. Birds such as siskins, redpolls and goldfinches feast on the seeds, and the tree’s roots offer shelter and nest sites for otters.
Did you know
Alder branches were once placed in cupboards to attract female woodworm, keeping them away from valuable furniture. It was thought they preferred to lay their eggs in alder over other woods.