Blackthorn (Prunus spinosa)

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Blackthorn, also known as 'sloe', is a small deciduous tree native to the UK and most of Europe.

Common name: blackthorn, sloe

Scientific name: Prunus spinosa
Family: Rosaceae

UK provenance: native

Interesting fact: blackthorn wood has been used to make walking or riding sticks, and was the traditional wood for Irish shillelaghs. 

A year in the life of a blackthorn tree

What does blackthorn look like?

Habit: spiny and densely branched, mature trees can grow to a height of around 6-7m, and live for up to 100 years. The dark brown bark is smooth, and twigs form straight side shoots, which develop into thorns.

Leaves: slightly wrinkled, oval, toothed, pointed at the tip and tapered at the base.

Flowers: blackthorn is a hermaphrodite, meaning both male and female reproductive parts are found in one flower. White flowers appear on short stalks before the leaves in March and April, either singularly or in pairs.

Fruits: once pollinated by insects, the flowers develop into blue-black fruits measuring 1cm across. 

Look out for: it is a spiny shrubby tree with black-purple twigs and small, narrow leaves.

Could be confused with: hawthorn (Crataegus monogyna), without leaves. The flowers of blackthorn appear before the leaves and the spines have buds along their length, on the hawthorn flowers emerge from the same point as the buds.

Identified in winter by: the twigs are black and spiny with leaf buds along the spines.

Where to find blackthorn

Blackthorn is native to Europe and western Asia. It can also be found in New Zealand and eastern North America. It grows best in moist, well drained soil and thrives in full sunlight.

It grows naturally in scrub, copses and woodlands, but is commonly used as a hedging plant. 

Value to wildlife

Early flowering, blackthorn provides a valuable source of nectar and pollen for bees in spring. Its foliage is a food plant for the caterpillars of many moths, including the lackey, magpie, common emerald, small eggar, swallow-tailed and yellow-tailed. It is also used by the black and brown hairstreak butterflies.

Birds nest among the dense, thorny thickets, eat caterpillars and other insects from the leaves, and feast on the berries in autumn.

Mythology and symbolism

Blackthorn was long associated with witchcraft, and it is said that witches' wands and staffs were made using blackthorn wood.

How we use blackthorn

The timber is hardwearing and tough, light yellow with a brown heartwood. It was traditionally used for making walking sticks and tool parts. It burns well, and is often used as firewood.

Blackthorn is used as a hedging shrub, particularly in wildlife gardens. The sloes are used for wine making and preserves, and, most commonly, flavouring gin. 

Threats

Blackthorn can be susceptible to fungal diseases which causes blossom wilt in fruit trees, and the fruits can sometimes be distorted by a gall-forming fungus, Taphrina pruni.

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