Alnus glutinosa - Common Alder

A fast-growing, medium-sized native tree found all over Britain, especially in wet places. Very hardy and coping with a wide range of soil types, Alder is particularly useful for preventing soil erosion, and for establishing plantings in waterlogged areas. Young plants are seldom attacked by rabbits or stock, so makes a good choice where this could be a problem.

Site and soil

Alder tolerates a wide range of soils and situations, except very dry conditions. It will grow well on damp hillsides and in boggy, waterlogged sites.

Height and spread

Below are the approximate stages of growth, assuming sited in suitable conditions for this species;

After 10 years: 8m x 2.5m
After 20 years: 9m x 3.7m

Leaf and bark

The leaves are ovate, and glossy dark green, and deeply lobed, rather like an oak, and about 5cm long. The bark is a greyish dark brown, cracked into thin rectangular plates.

Flower, seed and fruit

Male catkins of Alder can be seen as a purplish haze among the branches as early as January, opening to a dull yellow in March and April. Female catkins are very short (0.5cm), becoming woody 'cones' over winter which are a useful source of food for native birds.

Uses

Coppicing, hedging, specimen tree. Alder wood has the property of withstanding constant wetting and drying out, and for this reason was much used in the past for lock gates, mill wheels and troughs. It has also been used for clog-making and furniture, as well as for smaller items. Both the leaves and the bark were used in dye-making, and the tree has several medicinal uses too.

Wildlife

Alder fruits (false cones) are a useful source of food for birds in spring. The catkins are an early source of pollen and the trees provide shelter on wetland sites.