Blackthorn (Prunus spinosa)

Last Updated on November 29, 2022

Traditionally used to create cattle-proof barrier hedges and Irish Shillelagh walking sticks, blackthorn plants are common across the British Isles. Today, its berries are still used to create preserves and sloe gin, while the dense, spiny branches provide an essential, safe haven for many birds.

Overview

• Scientific Name: Prunus spinosa
• Common Name/s: Blackthorn, sloe bush, sloe
• Family: Rosaceae
• Origin: native
• Habitat: field edges, woodland areas
• Flowering months: March to May

Where Can You Find Them?

Prunus spinosa is native to Europe and western Asia, although it can also be found in North America and New Zealand. Traditionally used in hedgerows to create effective cattle-proof barriers, it is also a popular species for use as a security hedge.

Blackthorn plants can be found most often around the edges of fields, where it enjoys full sun, alongside rocky, scrub or woodland areas. It thrives in moist soil with good drainage.

Distribution 

Blackthorn (Prunus spinosa) is a very common plant and can be easily spotted throughout the UK. 

What Do Blackthorn Plants Look Like?

The blackthorn bush is a large deciduous shrub which can grow up to around five feet in height, conditions permitting. It has very dark, almost black bark and extremely dense, spiny branches with long thorns – hence its common name of blackthorn. 

Leaves

Blackthorn plant leaves are oval-shaped and sized around two to three centimetres long. Slender, they are at their widest above their halfway point, measuring between 1-2cm in width and ending in a pointed tip.

Blackthorn leaves are slightly wrinkled in appearance and have a serrated margin. Leaves open after the bush has flowered, and you can clearly see the plant’s thorns amongst the leaves. 

Flowers

Blackthorn flowers blossom in early spring and can be quite a sight. Bushes are seemingly covered in huge numbers of tiny white flowers, providing an early source of nectar and pollen for insects. 

Small, measuring approximately 1.5cm in diameter, the small white flowers consist of five petals. Occurring either singularly or in pairs, you’ll find them the entire length of the stems. 

Fruit

Berries are known as “sloes” and appear in the autumn. Round, sloes are bluish-black, almost dark purple in colour and approximately one centimetre wide. They have a large stone, not a lot of flesh and a slightly waxy coating. Wildlife creatures like to eat their fruit.

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Why Is It Dangerous?

While blackthorn has been used for centuries in traditional medicine, as well as a flavouring for drinks and food, you should not consume its leaves, fruit stones or stems. These parts contain prussic acid, also known as cyanide, a lethal toxin. 

Aside from the dangers of ingesting any part of this plant, apart from the edible flesh of its fruits, blackthorn thorns can be a lot more dangerous than they are given credit for. This is one of the reasons it makes such a popular hedging plant. With time, blackthorn hedges become virtually impenetrable, and the plant’s long, very sharp thorns tend to break off under the skin, where they can go septic. 

Are Blackthorn Berries Edible?

Yes, the fruit of the berries, or sloes, is edible. Sloes are still used to this day to make jams and wine, as well as sloe gin – a liqueur made with gin, sugar and sloe fruit. 

When picked, sloes are very tart, so they are not best enjoyed raw. It is traditionally recommended that the best time of the year to harvest sloe berries is after the first frosts, which is when they are at their ripest and the skins split with the cold for a better infusion of flavours. Alternatively, you could pick them earlier, if they are ripe and juicy, and simply place them in your freezer for the same effect. 

Have you enjoyed Blackthorn berries before? Do you know any other uses for this plant? Let us know below.