Common alder (Alnus glutinosa): what the forestry bodies record

This page reports what forestry bodies say about one tree. It does not identify trees from descriptions or photos and does not say what should be done with any tree. Each fact names its source, all read on October 9, 2026. The Phytophthora root rots page covers the genus of the pathogen named below.

At a glance

Item	What the source records
Scientific name and family	Alnus glutinosa, family Betulaceae (Woodland Trust)
Common names	Alder, common alder, black alder and European alder (Woodland Trust); Forest Research files it as Common (or black) alder with the code CAR
Origin	Native, and the only native species of the genus in the United Kingdom (Woodland Trust); a Principal tree species (Forest Research)
Height and age	Mature trees reach around 28 m and live to approximately 60 years (Woodland Trust)
Rainfall, exposure, shade	More than 600 mm of rain preferred; not tolerant of exposure; light demanding (Forest Research key properties)

Range

Forest Research says common alder grows naturally throughout Britain, thrives in the wetter areas of the north and west, and grows wherever there is ample year-round water. Wet woodlands dominated by it are known as alder-carr. It gives the native range as all parts of the British Isles, mainland Europe and southern Siberia. The Woodland Trust says it is native to almost the whole of continental Europe except the extreme north and south, with a natural habitat of moist ground near rivers, ponds and lakes. EUFORGEN, the European forest genetic resources programme, adds western Asia and northern Africa, with a scattered range.

Site and soil

Forest Research calls it a light demanding pioneer characteristic of wet areas, stream sides and riparian zones. It is cold hardy and frost resistant. It needs a high but not stagnant water table, medium to rich nutrient supply, and a pH above 4, and not calcareous soils. It grows best on deep loams and alluvial soils and is remarkably tolerant of wet conditions, restricted in Britain to altitudes below 500 m. The Woodland Trust says its association with the nitrogen-fixing bacterium Frankia alni lets it grow in nutrient-poor soils where few other trees thrive. Forest Research ties the same nitrogen fixing to a place in land restoration such as former colliery spoil heaps, and says it is used with willows in riparian planting for flood risk programmes.

Leaves, catkins and cones

The Woodland Trust describes dark fissured bark often covered in lichen, sticky young twigs, and dark green leaves 3 to 9 cm long that are racquet-shaped and leathery with serrated edges and a tip that is never pointed and is often indented. Catkins appear from February to April. Male catkins hang and turn yellow, and female catkins grow in groups of three to eight, red at first, then becoming woody cone-like fruit that stay on the tree all year. It says alder is the only British native deciduous tree to develop cones, and separates it from hazel by shiny leaves where hazel leaves are softly hairy.

Wildlife and uses

The Woodland Trust says the foliage feeds caterpillars of moths including the alder kitten, catkins give early nectar and pollen to bees, and siskins, redpolls and goldfinches eat the seed. Forest Research says it was coppiced in the past for turnery and charcoal, the preferred charcoal for gunpowder, and that it has no significant role in productive forestry but is commonly planted in native woodlands. It records a moderately fast-growing hardwood sometimes reaching Yield Class 12, full development in 30 to 40 years and rarely growing beyond 60. EUFORGEN calls the wood soft, resistant to rot and durable under water.

Pests and diseases the sources name

Forest Research says Phytophthora alni is the most significant pathogen of common alder, causing mortality or chronic dieback, and shows an affected tree on the River Rother in Sussex. The only other pathogens it says are reported with any frequency are root rot fungi and some fungal foliar pathogens, Melampsoridium, Taphrina and the shoot fungus Melanconium. It adds that common alder suffers less browsing than some native broadleaves.

Text on Forest Research is adapted from its tree species database entry and contains public sector information licensed under the Open Government Licence v3.0.