The common alder is a tree, widespread throughout most of Europe, extending from Spain to Scandinavia and eastward far into Siberia. It tolerates very moist soils, and is found mainly on the banks of rivers, beside brooks and ponds, and in swampy situations. It is most plentiful in the lowlands, occurring in the mountains up to elevations of about 700 metres. It attains heights up to 30 metres, sometimes more, and develops a straight bole with black-brown bark breaking up into plates.

It is easily recognised in winter by the narrowly ovoid, stalked, violet-brown buds. The broad obovate leaves are sticky in spring. The flowers, arranged in catkins, are already formed by the autumn and open in early spring (March), the female ones developing by autumn into woody cones with small winged nutlets. These are equipped with buoyant tissues that enable them to be carried great distances by air or water. The common alder is marked by the vigorous production of stump sprouts and is often grown for coppicing. The roots have small nodules with nitrogen-fixing bacteria which thereby enrich the soil. The common alder is a fairly light-demanding, fast-growing tree. The yellowish-red wood is used for the foundations of bridges, for plywood and for matches.