Sloe’s, otherwise known as Blackthorn, is a species of Prunus native to Europe, western Asia, and locally in northwest Africa (1). It is a deciduous large shrub or small tree growing to around 5 metres tall, with blackish bark, and stiff, spiny branches (1). They have creamy-white flowers with five petals, which are produced shortly before the leaves in early spring (1). They are hermaphroditic and insect-pollinated (1). The fruit, a “sloe” is a drupe – a soft fleshy fruit surrounding a shell which contains a single seed (2), they are black with a pale purple-blue waxy bloom, ripening in the autumn, and harvested, traditionally, at least in the UK, in October and November, after the first frosts (1).
The fruit is similar to a small damson or plum, however they are rather tart and astringent tasting when fresh, unless deeply frozen, as is practised in eastern Europe (1), the berries taste better and not so bitter if harvested after a few frosts (3). Ancient folk used to bury the sloes in straw-lined pits for a few months to ripen them and make them sweeter (3). A Neolithic lake village in Glastonbury was found to have such a pit, full of sloe stones (3).
In rural Britain, sloe gin is produced from the fruit, it is an infusion of gin, sugar or neutral spirits, which produces a liqueur (1). In Navarre, Spain, a popular liqueur called “patxaran” is made with sloes; they can also be used to make jam, and if preserved in vinegar, are similar in taste to Japanese umeboshi (1).
Much folklore surrounds the Blackthorn (3). It was believed that Christ’s Crown of Thorn’s was made from Blackthorn; to bring Blackthorn blossom into the home meant a certain death would follow (3). In Herefordshire and Worcestershire, a wreath or globe of Blackthorn twigs would be scorched on a fire on New Year's morning and then burned in a wheatfield in the furrows and its ashes scattered over the wheat; then a new globe or wreath would be made and hung in the farmhouse kitchen ready for next year (3). It was believed that this ritual would rid the field of the devil (3). In a similar vein, Blackthorn would be scorched and hung up with mistletoe for good luck (3).
Blackthorn in bloom is considered an emblem of life and death together as the flowers appear when the tree has no leaves, just black bark and thorns (3). It is considered wise not to grow three trees closely together (3). It is said that a Hawthorn will destroy any Blackthorn near it; on the Isle of Man it is believed that if the Blackthorn and the Hawthorn have many berries then the ensuing winter will be severe (3).
In Irish folklore it was believed that the "little people" lived in Blackthorn bushes (3). Fairy tribes, called Lunantishees, are said to guard Blackthorn trees and will not let you cut branches off it on 11 November or 11 May - if you do you will be cursed with bad luck (3). It was also bad luck to wear the flowers in your buttonhole (3). Another belief was that a Blackthorn wand with thorns fixed to the ends was harmful; while a carved rod carried by Devonshire witches was thought to cause miscarriage (3).
The flowers produce nectar for humblebees and early-flying Small Tortoiseshell butterflies (3). The leaves provide food for the larvae of Black and Brown Hairstreak butterflies (3). The tree is also the food plant for the caterpillars of the following moths - March, Common Emerald, Little Emerald, Mottle Pug, Feathered Thorn, Orange, Scalloped Hazel, Scalloped Oak, Swallowtailed, Brimstone, August Thorn, Early Thorn, Pale Brindled Beauty, Blue Bordered Carpet, Broken Barred Carpet, November, Pale November, Winter, Sloe Pug, Green Pug, Sharp Angled Peacock and The Magpie (3). In fact, Blackthorn supports around 153 species of wildlife; it is particularly favoured by nightingales (3).
The sharp thorns have been used for centuries as awls (3). Blackthorn is also the traditional wood used in wands for tribal medicine people and wise women etc (3). It is also used to make the traditional Irish shillelagh - cudgel - used in fighting sports (3). The tree also makes good firewood, marquetry and walking sticks (3).
Nutritional and Medicinal Background – Including Medieval Medicinal Uses
Studies have shown that 100g dry weight of the fruits of Prunus spinosa, contains considerable levels of vitamin A, in the form of B-carotene, vitamin E, vitamin B1, B2, B6 and niacin to satisfy the dietary requirements of all life stage groups (4). However, vitamin C and folate levels were noted to be lower than necessary to satisfy the dietary requirements of all life stage groups (4). The higher presence of vitamin E, B-carotene and folate in the sloes gives the fruit considerable antioxidant quantities.
Organic acids in the fruits are significant raw materials for the fruit juice industry, such as malic acid, lactic acid, citric acid and fumaric acid; there were no detectable levels of quinic acid found in the fruit (4). The volumes of acid found in the fruit explain its astringent taste when eaten raw. The genotype and growing conditions of the fruits can alter the limits of the different acids in the fruits (4).
Sloes contain a number of minerals such as calcium, potassium, magnesium and sodium (5).
The dried juice of the berries makes gum acacia (3). The flowers and fruit make a good tonic for diarrhoea and other bowel problems (3). Sloe syrup has anti-rheumatic properties and can help fight flu (3). The plant is also good for nosebleeds, constipation and eye pain (3). Sloe berries were first used by herbalists for treating stomach problems and blood disorders (3). Sloes can also be made into a paste for whitening teeth and removing tartar (3).
Shlomo Yitzhaki, a Talmudist and Tanakh, commentator of the High Middle Ages, has written that the sap (or gum) of Prunus spinosa (or what he refers to as the prunellier) was used as an ingredient in the making of some inks used for manuscripts (1).
When cooking, the sloes high pectin content means that they are sometimes combined with other fruit in jams and jellies to encourage the preserve to set (6). When preparing the sloes for making either sloe gin, fruit wine or sloe-flavoured vinegar, they can either be pricked all over with a needle, or put in the freezer for a couple of days so that the skins split (6).
Sloe syrup is a traditional remedy for fighting off the flu, and due to its potent antioxidant qualities, they may well have many alternative medicinal uses (7).
The flowers of the Blackthorn appear before the leaves, both of which can be used for tea, traditionally only the flowers are used (8). They are mildly stimulating for the whole body: mildly diuretic, mildly diaphoretic and mildly laxative (8). They ‘cleanse the blood’, and make a great supportive tea for those who like to do internal ‘spring cleanses’ (8).
4. Ozcan, T., “Some vitamin and organic acid contents in the fruits of Prunus spinosa L. subsp. dasyphylla (Schur) Domain from Europe-in-Turkey”, IUFS Journal of Biology (2008), 67(2):105-114