Buckthorn, purging (Rhamnus cathartica)
Purging buckthorn is often known simply as 'buckthorn'. It is commonly found growing in scrub and woodland around Britain.
Common name: purging buckthorn, common buckthorn, buckthorn
Scientific name: Rhamnus cathartica
UK provenance: native
Interesting fact: buckthorn was introduced into North America as an ornamental landscaping plant, but has naturalised and become a problem in parts of Canada and the United States, as its dense growth crowds out native plants.
What does purging buckthorn look like?
Overview: named after the laxative effects its berries induce when eaten, purging buckthorn is a small, spiny tree native to England and Wales and throughout Europe. Mature trees can grow to a height of 10m, with grey-brown bark and spiny branches. The leaf buds are conical and black-brown in colour, and form on long stalks.
Leaves: the glossy, dark green, toothed leaves turn yellow before falling in autumn.
Flowers: buckthorn is dioecious, meaning male and female flowers are found on different trees. Flowers are yellow-green with four petals, and are pollinated by insects.
Fruits: after successful pollination, the female flowers develop into purple-black berries (drupes), 6-10mm in diameter. The seeds within the fruit are dispersed by birds.
Look out for: leaves are opposite along the twig and have 3-5 pairs of curved veins that meet at the tip of the leaf.
Could be confused with: dogwood (Cornus sanguinea), purging buckthorn is spiny whereas dogwood is not. It is also similar to alder buckthorn (frangula alnus) but purging buckthorn has opposite leaves and alder buckthorn has alternate leaves.
Identified in winter by: the twigs have thorns. The buds are elongated and closely pressed to the twig, they also have bud scales. Peeling back the bark surface reveals orange bark underneath.
Where to find purging buckthorn
Purging buckthorn is a hardy tree and grows well in most soils, in shade or sunlight.
Value to wildlife
Purging buckthorn is the main food plant of the brimstone butterfly, whose caterpillars eat the leaves. Its flowers provide a source of pollen and nectar for bees and other insects. Its dense growth makes it a valuable nesting site for birds.
Mythology and symbolism
It was once used as a purgative, which was thought to help rid the body of illness and disease.
How we use purging buckthorn
Traditionally the fruits and bark were used to make a yellow dye. The hard, dense wood is rarely used.
As well as having a laxative effect, the berries are slightly poisonous and can irritate the skin. The bark can also irritate the skin.
There are no known threats, pests or diseases associated with purging buckthorn.