Alder

Short Description

Alders often grow multi-stemmed. They can grow up to 30 m tall and have a rounded crown.

The leaves are roundish to inverse oval. The leaf margins are coarsely serrated and the tip of the leaf generally indented. The leaves grow alternately on the branch.

The bark is initially smooth and a shiny red-brown. A dark fissured outer bark is formed later.

The flowers are green or yellowish and clustered in catkins. The tree has male and female flowers. Male catkins are long and pendulous. Female flower heads are globular and cone-shaped.

The fruit is a small winged nut. They are clustered in woody, cone-shaped seed heads that can easily be mistaken for the fruit itself. They remain on the tree during the winter.

In the city

The alder can be found on riverbanks, lakeshores or at the edge of water bodies in parks. Due to the increasing periods of drought, the tree will only be found to a limited extent in the city in the future. Only locations with sufficient water supply, such as in parks and gardens, remain suitable. As an important ecological service of the alder, its potential for improving urban air quality by binding particulate matter is discussed.

Alders are often used to stabilise banks.