British Native Trees
and Shrubs

Alder Buckthorn Frangula alnus (Rhamnaceae)

Alder buckthorn is a charming, slow-growing deciduous shrub that gives a good show of colour in autumn with yellow leaves and violet-black berries. Despite its name it is thornless, its dark grey-brown, ascending branches reaching up to 5 m in height and bearing hairy brown buds in winter. Shiny oval leaves, 2-7 cm long, with parallel veins and untoothed margins appear in April, followed later by inconspicuous five-petalled, greenish flowers borne in small clusters at the base of the leaf stalk. The two to three-seeded egg-shaped fruits develop in summer, turning from green through red to black when they are fully ripe in autumn.

Alder buckthorn is found in open woods, scrub and bogs on damp and acid soils throughout most of lowland England, though absent from the north-east.

It can be a useful hedge plant, or it can be grown singly or in groups in a shrubbery. It grows rapidly after coppicing or cutting back and likes moist but not waterlogged soils. Alder buckthorn will not tolerate drought or a very exposed site. It was much planted in the past as a source of charcoal for making gunpowder, and a dried extract from the bark was a purgative used by medieval monks. The bark is also a source of yellow or brown dyes while the fruit yields green or bluish-grey dyes. It is best propagated from seeds gathered in autumn, stratified, and sown in early spring, thinned in autumn and grown on before planting in a permanent site two years later. Alternatively, semi-hard cuttings with a heel can be taken in late summer or hardwood cuttings in autumn. Young plants must not be allowed to dry out.

Growing alder buckthorn south of Yorkshire attracts the beautiful yellow brimstone butterfly, because after buckthorn it is its main food plant. A tortricoid moth caterpillar lives on the berries in the summer, and in the winter the black fruits are a valuable source of food for wintering birds, including cuckoos and fieldfares. The seeds are stored and eaten by field mice.

Page last updated - January 10, 2002  

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