The distinctions between Prunus spinosa and Prunus domestica are not clear. Some researchers consider the hexaploid Prunus domestica to have been derived from the tetraploid Prunus spinosa, often in a scenario involving hybridization with Prunus cerasifera. It should not be surprising that some of the characters used in keys to separate these three taxa (spininess, indument, leaf size, pedicel length, numbers of flowers per bud) are subject to variation within each species and overlap among the species[].
The taxonomic history of Prunus is long and complicated, in part due to the economic value of its fruit crops and also the ease with which some species hybridize. Here, Prunus is circumscribed in its broad sense based on the argument that when viewed on a worldwide scale, the morphologic discontinuities among the segregate genera diminish and they overlap with one another. Included here are species that have at times been placed in the genera Amygdalus, Armeniaca, Cerasus, Laurocerasus, Padus, and Persica.
At the species level, Prunus has been the object of the usual combining and splitting common among taxonomists with different philosophies and opinions. In particular, over-reliance on the indument of various vegetative and floral parts has led to the naming of numerous species and infraspecific taxa. Similarly, too much has been made of fruit colour and palatability in naming taxa of Prunus. It is very likely that, as molecular and genetic data are analyzed and, more importantly, correlated with morphological data, circumscriptions will be redrawn and the number of Prunus species will be reduced[].

Common Name: Sloe

General Information

Prunus spinosa is a very spiny, much-branched, deciduous shrub, rarely becoming a small tree; it can grow 1 - 4 metres tall, occasionally to 8 metres. The plant produces suckers and can form dense thickets[, ].
The plant is harvested from the wild for local use as a food, medicine and source of materials. It is sometimes grown as a stock-proof barrier or hedge and can be used as a pioneer for the restoration of native woodland.
Prunus spinosa is a widespread species that is documented to be common and stable in many areas of its native range. The plant is classified as 'Least Concern' in the IUCN Red List of Threatened Species(2013)[].

Known Hazards

The plant (especially the seed and young shoots) contains cyanogenic glycosides, especially amygdalin and prunasin. When injested, these compounds break down in the digestive tract to release cyanide. Used in small quantities in both traditional and conventional medicine, this exceedingly poisonous compound has been shown to stimulate respiration, improve digestion, and promote a sense of well-being[]. It is also claimed by some to be of benefit in the treatment of cancer - though this claim has been largely refuted.
In larger concentrations, however, cyanide can cause gasping, weakness, excitement, pupil dilation, spasms, convulsions, coma and respiratory failure leading to death[].
The fruits and flowers of most members of this genus generally have low or very low concentrations of this toxin, though the seeds and young shoots can contain much higher levels.
The levels of toxin can be detected by the level of bitterness:- for example sweet tasting almond seeds are a major food crop and are often eaten in quantity, whilst bitter tasting almond seeds are used as a flavouring (in marzipan for example) but are not usually eaten on their own.
In general, it can be considered safe to eat any fruit or seed from species in this genus that either have a sweet flavour or are slightly bitter. Great caution should be taken, however, if the flavour is moderately to very bitter[].

Botanical References

, ,

Range

Eurasia - Norway to Portugal, east to the Caucasus, Turkey and Iran; N. Africa - Morocco, Algeria, Tunisia

Habitat

Hedgerows and woods, usually in sunny positions, on all soils except acid peats[, ]. Mostly in the forest-steppe zone, glades, forest edges, ravines, river valleys; rarely inside forest; at elevations from 800 - 1,200 metres[].

Properties

Conservation Status	Least Concern
Edibility Rating
Medicinal Rating
Habit	Deciduous Shrub
Height	3.00 m
Growth Rate	Medium
Pollinators	Insects
Cultivation Status	Wild

Cultivation Details

Requires a well-drained moisture retentive soil[]. Succeeds in all soils except very acid peats[]. Succeeds in light shade but fruits better in a sunny position[, ]. Thrives in a loamy soil, doing well on limestone[]. Prefers some chalk in the soil but apt to become chlorotic if too much is present[]. Thrives on chalk according to another report[]. Plants are very resistant to maritime exposure[].
An important food plant for the caterpillars of several species of butterfly[], especially the larvae of the brown and black hairstreak butterflies[]. A good bee plant.
Plants are shallow-rooted and of a suckering habit, they can form dense impenetrable thickets which are ideal for nesting birds, especially nightingales[].
Flowers are often damaged by late frosts[].
Plants regenerate quickly after cutting or after fast moving forest fires, producing suckers from below ground level[].
This species is notably resistant to honey fungus[, ].

Edible Uses

Fruit - raw or cooked[, , , , , , ]. Exceedingly astringent, it is normally cooked but once the fruit has been frosted it loses some of its astringency and some people find they can enjoy it raw[, ]. The fruit is more usually used in jellies, syrups, conserves etc and as a flavouring for sloe gin and other liqueurs[]. Some fruits that we ate in December were fairly pleasant raw[]. In France the unripe fruit is pickled like an olive[]. The bluish-black, globose fruit is about 10 - 15mm in diameter and contains one large seed[, ].

Seed - raw or cooked. Do not eat the seed if it is too bitter - see the notes above on toxicity.

The leaves are used as a tea substitute[, ]. The dried fruits can be added to herbal teas[].

The flowers are edible and can be crystallised or sugared[].

Medicinal

The flowers, bark, leaves and fruits are aperient, astringent, depurative, diaphoretic, diuretic, febrifuge, laxative and stomachic[, , ]. An infusion of the flowers is used in the treatment of diarrhoea (especially for children), bladder and kidney disorders, stomach weakness et[].

Although no specific mention has been seen for this species, all members of the genus contain amygdalin and prunasin, substances which break down in water to form hydrocyanic acid (cyanide or prussic acid). In small amounts this exceedingly poisonous compound stimulates respiration, improves digestion and gives a sense of well-being[].

Agroforestry Uses:

The sloe is very resistant to maritime exposure and also suckers freely. It can be used as a hedge in exposed maritime positions. The hedge is stock-proof if it is well maintained[, ], though it is rather bare in the winter and, unless the hedge is rather wide, it is not a very good shelter at this time[].
Because of its suckering habit, the plant is a natural pioneer species, invading cultivated fields and creating conditions conducive to the regeneration of woodland. The freely suckering habit makes this species a good choice in soil stabilization projects[].

Other Uses

The bark is a good source of tannin[]. It is used to make an ink[].

The juice of unripe fruits is used as a laundry mark[], it is almost indelible[].

The pulped ripe fruit is used cosmetically in making astringent face-masks[].

A green dye can be obtained from the leaves[].
A dark grey to green dye can be obtained from the fruit[].
The bark, boiled in an alkali, produces a yellow dye[].

The seed contains up to 37% oil[].

The wood is very hard. It is highly prized for turnery, making the teeth of rakes etc[, , , , ]. Suitable branches are used for making walking sticks and are highly valued for this purpose because of their twisted and interesting shapes[].

Propagation

Seed - requires 2 - 3 months cold stratification and is best sown in a cold frame as soon as it is ripe[]. Sow stored seed in a cold frame as early in the year as possible[]. Protect the seed from mice etc. The seed can be rather slow, sometimes taking 18 months to germinate[]. Prick out the seedlings into individual pots when they are large enough to handle. Grow them on in a greenhouse or cold frame for their first winter and plant them out in late spring or early summer of the following year.
Cuttings of half-ripe wood with a heel, mid summer in a frame[, ].
Softwood cuttings from strongly growing plants in spring to early summer in a frame.
Layering in spring.
Division of suckers during the dormant season. They can be planted out direct into their permanent positions.