Alnus glutinosa, commonly called Black Alder is a small to medium-sized deciduous tree growing 12m x 6m.

It has rounded, glossy dark green leaves and forms drooping male catkins (to 100mm) long in autumn and overwinter on the tree.

Best grown in medium to wet soils in full sun to part shade. Tolerates a wide range of soils, however, including dry, infertile ones. Best performace is in cool climates.

A good selection for difficult sites such as moist low spots or dry sites with poor soils.

Nitrogen fixing microorganisms develop in nodules on the tree roots in somewhat the same manner as with the legumes.