Alnus glutinosa

Alnus glutinosa, or, common alder, is a native tree that excels within difficult locations. It is particularly suited for wet clay areas prone to regular waterlogging. At the base of its trunk, it produces adventitious roots above the ground. These grow from the trunk down into the soil, stabilising both the ground and the tree within its location. On certain sites, it can appear like stilt roots propping the tree up. It has strong symbiotic relationships with many mycorrhizae, particularly Frankia alni. This beneficial bacterium attaches itself to the roots of the alder and further improves soil fertility with nitrogen. A perfect tree for erosion control and stabilisation of river banks and water course-ways.

Its roots grow deeper than that of the Italian Alnus. This allows its use not only in wetlands but also for urban applications where clay is the predominant soil structure. It is ideal selected for roundabouts where salt spreading may occasionally disperse over from the road into the tree locations.

These are interesting ornamental features that hangs compactly from the tree. The oval pear-shaped leaves are quite distinct with an indented tip rather than pointed. They are vivid green with deep attractive ridges that remain green until near the beginning of winter.