Alder

Crown jewel in the De Kruidhof garden of the Nijmegen Botanic Garden.

Alnus glutinosa has multiple uses in the forestry and the timber industry. The orange coloured wood is resistant to rotting and has been called the Scottish Mahogany. When submerged alder wood becomes as hard as iron and was used for piles, foundations, bank protection and to make mattresses for the waterwork industry. Today it is used to make plywood. The wood makes good charcoal. This variety has also been used extensively to control soil erosion and to improve the soil (atmospheric nitrogen converted into a usable form). It is used as a windbreak by fruit igeowers.

The wood is used for coppicing, hedging and historically for lock gates, mill wheels and troughs as it can withstand constant wetting and drying. In Europe it has served for many centuries as an important source of hardwood for timber and carved items, including clogs.

The leaves and bark were historically used to make dyes.

Alnus glutinosa plays an important role in superstition especially in rural areas where it is used to keep pests out of the fields during the sowing season. The white wood of a freshly pruned alder undergoes a colour change - initially to yellow through orange-red to almost blood red. It was once thought that this change in colour was linked to the blood of the devil or witches living in the tree.

The bark and leaves of the tree also have medicinal uses, the bark is astringent, and a decoction was used as a gargle for sore throats; the leaves were used as a compress for swelling and inflammation.

Alnus glutinosa is valuable to wildlife as the cones open gradually and release seed throughout the winter, the seeds are a dependable source of food for seed-eating birds such as pine siskins and goldfinches. It is a recommended species for use in shelterbelts to provide cover for pheasants.

Alder pollen causes moderate allergies and as the black alder is one of the first species to bloom in the winter it is therefore one of the earliest hay fever-causing species.