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Portrait of Alder buckthorn

Nature · Shrubs

Alder buckthorn

Native · flowers May–Jun · wet woodland, fens and acid heath

Frangula alnus — Rhamnaceae

A thornless shrub of wet woods, fens and acid heath, with smooth alternate leaves and berries that ripen from green through red to black. Its charcoal is the classic gunpowder charcoal, and on acid, waterlogged ground it is the food plant of the brimstone butterfly.

How to spot them

  • ▸Alternate, matt green, oval leaves with 6–10 pairs of straight lateral veins that do not curve towards the tip
  • ▸Smooth, thornless, purple-brown twigs with fine white streaks; yellow inner bark when scratched
  • ▸Small star-shaped greenish-white flowers, 3–5 mm across, in clusters in the leaf axils in May–June
  • ▸Berries ripen from green to red to dark purple-black, often several colours at once
  • ▸Look-alike: purging buckthorn has opposite, curved-veined leaves and thorns; dogwood has opposite leaves and blood-red winter twigs

How to know it

Thornless shrub with alternate leaves, berries in three colours at once, and inner bark that is bright yellow when scratched

Alder buckthorn.

Its charcoal was regarded as the best for gunpowder, especially for time fuses because of its even burn rate

Alder buckthorn.

The brimstone butterfly lays on it in wet acid places, where the lime-loving relative does not grow

Alder buckthorn.

Its dried bark and fruit, containing anthraquinones, were once used as a laxative

Alder buckthorn — also 'breaking buckthorn'.

Which thornless native shrub has alternate leaves, unlike a spiny relative with opposite ones?

Alder buckthorn versus purging buckthorn.

Woodland Trust records that it was credited with the power to protect against witchcraft, demons, poisons and headaches

Alder buckthorn.

Quick-fire facts

  • •Frangula alnus, family Rhamnaceae; also called glossy buckthorn and breaking buckthorn; grows to about 6 m (Woodland Trust)
  • •Native; unlike purging buckthorn the branches are smooth and thornless, and the flowers are hermaphrodite
  • •Brimstone butterfly: alder buckthorn is one of two native food plants of the caterpillars, favouring moist acid soils and wetlands, while purging buckthorn favours chalk (Butterfly Conservation)
  • •Its charcoal is prized for gunpowder, particularly time fuses, for its very even burn rate (Woodland Trust)
  • •The dried bark has 3–7% anthraquinone content, which stimulates the colon
  • •TOXICITY: bark and fruit are strongly laxative; do not eat the berries
  • •Yellow dye from leaves and bark, green from unripe fruit, and blue or grey from ripe berries
  • •Hard, durable wood used for wooden nails, shoe lasts, arrows and skewers

Drill it — 6 cards

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Sources