Skip to main content

Alnus glutinosa - common (or European) alder

Alnus glutinosa © Susanna

European alder is common in Finland south of the line Kokkola-Iisalmi-Nurmes, though also found on shores and fertile soils as far north as the northern Gulf of Bothnia and southern Lapland. At its best, this species is as impressive in the landscape as the grandest of oaks, developing strong branches and a broad crown when given enough space.

New shoots are somewhat sticky. The species is wind-pollinated and enlivens the landscape in spring (April-May) with its flower catkins about a week before grey alder (A. incana). The seeds fall from the dry “cones” in winter, causing extra work for fishermen emptying their nets on the shores.

Roots extending into lake and sea waters draw attention by their bright red colour. One special characteristic of the alders is their co-operation with Frankia alni-bacteria, which enables them to fix atmospheric nitrogen in their roots. This means alders don’t need to withdraw the chlorophyll from their leaves into storage in the trunk and roots in autumn and the leaves fall while still green, enriching forest soils.

The European alder does not produce root suckers, though it does sucker from the butts of felled trees. The species tolerates trimming and has been used as hedging on the shores of the Gulf of Bothnia. In landscaping use it is rare but beautiful. The species should also be valued in forestry, since the reddish timber has many uses.