Winter twig

Brimstone butterfly

The opposite or nearly opposite, round to oval, hairless leaves, 3-7cm long, are hairless. They have finely toothed margins and 3-4 pairs of veins curving upwards. They are arranged in circular clusters on short shoots.

ID check

Purging buckthorn is a deciduous shrub, occasionally reaching 10 m in height but is usually only 4-6 m high. It is almost restricted to lime-rich soils, where it grows in woods, scrub and hedgerows.

The opposite branches bear long and short shoots. The latter are leafy and often end in a spine.

The flowers, which appear in June, have 4 small greenish sepals and petals. Male and female flowers may occur on separate bushes.

Female flowers will produce pea-sized fruits, green at first, but becoming black when ripe. They appear from September onwards.

Facts

• Purging buckthorn is one of the food plants of the caterpillars of the brimstone butterfly (see photograph).

• The berries are purgative, but not poisonous to humans and are eaten by birds in winter, with no apparent harmful effect.

• The leaves are often attacked by a fungus, crown rust, which appears as orange specks.