Blackthorn / Sloe (Prunus spinosa)

Are Blackthorn and Sloe the same?

Blackthorn and sloe refer to the same plant, scientifically known as Prunus spinosa. The term "blackthorn" typically describes the entire plant, while "sloe" specifically refers to its small, dark-purple fruits.

Here are some key characteristics to help identify blackthorn and sloe:

Appearance of Blackthorn & Sloe:

Blackthorn:
This is a spiny shrub or small tree that grows to about 2–6 meters tall. It has dense branches forming a tangled structure, making it a common component of hedgerows.
Sloe:
The fruits are round, dark purple or black drupes with a blueish bloom. They are small (around 1 cm wide) and extremely astringent when eaten raw. Sloes are best picked after the first frost, as the cold weather helps to reduce their tartness.

Flowers of Blackthorn:

Blackthorn produces small, five-petaled white flowers in early spring, often before its leaves appear. These flowers are a characteristic feature of the plant and can be seen in abundance before the leaves unfurl.

Leaves of Blackthorn:

The leaves of blackthorn are oval and have serrated edges. They appear after the flowers bloom, providing a contrast to the earlier flowering period.

Common Blackthorn Confusions:

People often confuse blackthorn with similar plants such as the cherry plum or damson. However, blackthorn is distinguishable by its spiny nature, earlier flowering, and smaller, darker fruits.

Description of Blackthorn / Sloe:

The Blackthorn, also known as Sloe, is a thorny hedgerow tree or shrub with dark purple berries that have culinary, medicinal, and historical significance. It grows up to 4 meters in height. It has blackish bark and spiny black stems, with oval-like leaves and snowy-white flowers. The dark purplish berries appear between August and November.

Habitat of Blackthorn / Sloe:

Blackthorn can be found in hedgerows, woodlands, parks, and gardens. It is native to Britain, Europe, and North Asia.

Food Uses of Blackthorn / Sloe:

The fruits, commonly known as sloes, are traditionally used to make sloe wine or gin, jam, and jelly. The flowers can be sugared for edible cake decorations, and a tea can be made from the leaves. While fresh sloes contain vitamin C and other nutrients, they are known for their rich content of antioxidant compounds, phenols, and flavonoids.

Medicinal Uses of Blackthorn / Sloe:

Blackthorn has been used in traditional medicine to treat various ailments. The astringent berries and bark have been used to treat diarrhoea, while the flowers have been used as a laxative. Sloes were also used as remedies for coughs and colds due to their astringency. The peeled bark boiled in water was a remedy for bronchitis in some traditions.

Other Uses of Blackthorn / Sloe:

Blackthorn is known for its use in creating impenetrable hedgerows, providing a protective barrier for fields and coasts. The shrub has been historically used to make walking sticks, known as shillelaghs, and can be used to create different coloured dyes.

Wildlife Value of Blackthorn / Sloe :

Flowers appear in March-April, before leaves emerge, providing crucial early nectar for bees, hoverflies, and early butterflies when few other sources are available
The dense, thorny structure creates perfect nesting sites for birds like thrushes, blackbirds, and finches
Sloe berries persist into winter, providing vital food for fieldfares, redwings, and other winter birds
Acts as larval food plant for several moth species including the Brown Hairstreak butterfly, Lunar Yellow Underwing, and Dark Dagger
Connected hedgerows of blackthorn create wildlife corridors essential for small mammal movement and bat navigation

Cultural & Historical Significance of Blackthorn / Sloe:

In Celtic tradition, blackthorn was associated with warfare and fate, featuring in tales of the Morrigan
The wood was believed to offer protection against evil spirits
Flowering times were used to predict spring weather patterns in rural communities
Ancient parish boundaries were often marked with blackthorn hedges
Traditional folklore warned against bringing flowering branches indoors, considering it unlucky
Featured prominently in the Irish tradition of shillelagh-making, where the wood was smoked and shaped

Harvesting & Processing of Blackthorn / Sloe:

Traditional harvesting occurs after the first frost (usually October-November)
Modern method: freeze berries overnight to simulate frost effect
Berries should be slightly soft when squeezed but not mushy
Can be stored in freezer for up to 6 months
For gin-making, prick each berry or freeze/thaw to split the skins
Optimal sugar-to-fruit ratios for different preparations (1:1 for jam, varied for gin)

Cultivation of Blackthorn / Sloe:

Prefers well-drained, neutral to alkaline soils
Full sun to partial shade
Can be grown from seed but requires cold stratification
Best propagated from suckers or semi-ripe cuttings in late summer
Prune in winter to maintain shape and encourage fruiting
Watch for bacterial canker and brown rot
Takes 5-8 years to reach fruiting maturity

Modern Applications for Blackthorn / Sloe:

Used in craft gin production worldwide
Sloe syrup used in modern cocktail mixing
Becoming popular in artisanal preserves and condiments
Recent studies investigating anti-inflammatory properties
Commercial orchards now growing specifically for gin industry
Being incorporated into rewilding projects

Seasonal Changes of Blackthorn / Sloe:

March-April: White flowers appear

April-May: Leaves emerge

June-July: Small green fruits develop

August-September: Fruits begin to ripen

October-November: Fruits fully ripe, traditional harvesting

December-February: Dormant period, good for pruning

What Can Be Mistaken for Sloes?

When foraging for sloes, it's essential to be aware of similar-looking fruits that might lead to misidentification.

Here's a comprehensive guide to help you distinguish sloes from their common lookalikes:

1. Damson (Prunus domestica subsp. insititia)

Appearance: Damsons are often confused with sloes due to their similar dark color. However, damsons are larger, typically around 2-3 cm in diameter, and more oval or egg-shaped compared to the smaller, round sloes.
Tree Characteristics: Damson trees are less thorny than blackthorn bushes. They have a more upright growth habit, resembling small trees rather than dense shrubs.
Taste: Damsons are generally sweeter and less astringent than sloes. They are often used in jams and desserts due to their pleasant flavour.

2. Bullace (Prunus domestica var. insititia)

Appearance: Bullaces are another close relative of sloes, with fruits that are slightly larger and more rounded. Their color can vary from dark purple to a more reddish hue.
Tree Characteristics: Bullace trees are less spiny than blackthorn but still have some thorns. The overall structure is more tree-like, with less dense branching.
Taste: Bullaces are less tart than sloes but still have a distinct tang. They are commonly used in preserves and beverages.

3. Cherry Plums (Prunus cerasifera)

Appearance: Cherry plums can be mistaken for sloes, especially when not fully ripe. However, they are generally larger, with a smoother skin and a more varied color range, including red, yellow, and purple.
Taste: Cherry plums are sweet and juicy, making them pleasant to eat raw. This contrasts sharply with the astringent taste of sloes.

4. Hawthorn Berries (Crataegus spp.)

Appearance: Hawthorn berries, also known as "haws," are small, round, and bright red when ripe. They grow in clusters, unlike sloes, which grow individually on short stalks.
Tree Characteristics: Hawthorn trees have thorns, but they are smaller and less dense than those of blackthorn. The leaves of hawthorn are deeply lobed, unlike the simple oval leaves of blackthorn.
Taste: Hawthorn berries have a mild, slightly sweet flavor with a mealy texture. They are often used in jams and herbal teas.

Safety Note for Blackthorn / Sloe:

While there is limited conclusive data on the toxicity of Blackthorn, caution is advised when using any medicinal herb during pregnancy or while breastfeeding, or when using it alongside prescribed medications.

Overall, the Blackthorn, or Sloe, is a versatile plant with its astringent fruit and medicinal properties, making it a valuable resource in the countryside and an important part of traditional practices in the British Isles. Its thorny branches serve practical purposes, including the creation of protective hedges.