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common name: Common Alder, Black Alder, Gwernen
growth rate: fast
growth habit: conical
leaf colour: dark green
flower colour: light brown
fruit colour: brown & green
main season: Summer
full sun, part shade
moist soil, wet/waterlogged soil, clay soil
preferred soil pH: any
minimum temp: -35°C
USDA zone: 4 to 9
Tough and fast growing deciduous tree with alternate, coarse, toothed dark green leaves. Pendant yellowish-brown male catkins in late winter or early spring. Woody, cone-like fruits, green at first turning brown in autumn.
Moist or wet soil in sun or part shade. Often grows by on river and lake banks and other damp place but will tolerate drier conditions. Able to grow in poor soils, assisted by symbiotic association with nitrogen-fixing bacterium in the roots (Frankia alni).
Can be coppiced or pollarded.
From seed or hardwood cuttings in winter.
Perfect for difficult boggy ground. Through its relationship with bactrium at the roots, fixes nitrogen and improves soil fertility. An important species for stabilisation of river banks and reclaimation of boggy land. Has been used for coppicing on waterlogged ground.
Timber is very durable under water, although not so above ground. It was used for the foundation supports of many buildings in Venice.
Native to most of Europe, southwest Asia and parts of northern Africa. A British native tree.