Prunus spinosa is a large deciduousshrub or small tree growing to 5 metres (16 feet) tall, with blackish bark and dense, stiff, spiny branches. The leaves are oval, 2–4.5 centimetres (3⁄4–1+3⁄4 inches) long and 1.2–2 cm (1⁄2–3⁄4in) broad, with a serrated margin. The flowers are about 1.5 cm (1⁄2in) in diameter, with five creamy-white petals; they are produced shortly before the leaves in early spring,[3] and are hermaphroditic, and insect-pollinated. The fruit, called a "sloe", is a drupe 10–12 millimetres (3⁄8–1⁄2in) in diameter, black with a purple-blue waxy bloom, ripening in autumn and traditionally harvested – at least in the UK – in October or November, after the first frosts. Sloes are thin-fleshed, with a very strongly astringent flavour when fresh.[4]
Blackthorn usually grows as a bush but can grow to become a tree to a height of 6 m. Its branches usually grow forming a tangle.[5][6]
Prunus spinosa is frequently confused with the related P. cerasifera (cherry plum), particularly in early spring when the latter starts flowering somewhat earlier than P. spinosa.[citation needed] They can be distinguished by flower colour, pure white in P. spinosa, creamy white in P. cerasifera. In addition, the sepals are bent backwards in P. cerasifera, but not in P. spinosa.[7] They can be distinguished in winter by the shrubbier habit with stiffer, wider-angled branches of P. spinosa; in summer by the relatively narrower leaves of P. spinosa, more than twice as long as broad;[4][8][page needed] and in autumn by the colour of the fruit skin purplish black in P. spinosa and yellow or red in P. cerasifera.[9]: 207
Prunus spinosa has a tetraploid (2n=4x=32) set of chromosomes.[10]
Like many other fruits with pits, the pit of the sloe contains trace amounts of hydrogen cyanide.[11]
The specific name spinosa is a Latin term indicating the pointed and thornlike spur shoots characteristic of this species. The common name "blackthorn" is due to the thorny nature of the shrub, and possibly its very dark bark: it has a much darker bark than the white-thorn (hawthorn), to which it is contrasted.[12]
The species is native to Europe, western Asia, and locally in northwest Africa.[15][4] It is also locally naturalizedinTasmania and eastern North America.[15]
The shrub, with its long, sharp thorns, is traditionally used in Britain and other parts of northern Europe to make a cattle-proof hedge.[16]
The fruit is similar to a small damsonorplum, suitable for preserves, but rather tart and astringent for eating, unless it is picked after the first few days of autumn frost. This effect can be reproduced by freezing harvested sloes.[17]
Since the plant is hardy, and grows in a wide range of conditions, it is used as a rootstock for many other species of plum, as well as some other fruit species.
The juice is used in the manufacture of fake port wine, and used as an adulterant to impart roughness to genuine port, into the 20th century.[18][19][20] In rural Britain a liqueur, sloe gin, is made by infusing gin with sloes and sugar. Vodka can also be infused with sloes.[21] Similarly, in Northern Greece, they make a blackthorn liqueur by infusing tsipouro with the fruit and adding sugar.
InNavarre, Spain, a popular liqueur called pacharán is made with sloes. In France a liqueur called épineorépinetteortroussepinette is made from the young shoots in spring rather than from fruits in autumn. In Italy, the infusion of spirit with the fruits and sugar produces a liqueur called bargnolino (or sometimes prunella). In France, eau de vie de prunelle[s] is distilled from fermented sloes in regions such as the Alsace[b] and vin d'épine is an infusion of early shoots of blackthorn macerated with sugar in wine.[24][25] Wine made from fermented sloes is made in Britain, and in Germany and other central European countries. It is also sometimes used in the brewing of lambic beer in Belgium.
Sloes can also be made into jam, chutney,[21] and used in fruit pies. Sloes preserved in vinegar are similar in taste to Japaneseumeboshi. The juice of the fruits dyes linen a reddish colour that washes out to a durable pale blue.[16]
The leaves resemble tea leaves, and were used as an adulterant of tea.[19][26]
The fruit stones have been found in Swiss lake dwellings.[19] Early human use of sloes as food is evidenced in the case of a 5,300-year-old human mummy (nick-named Ötzi), discovered in the Ötztal Alps along the Austrian-Italian border in 1991: a sloe was found near the remains, evidently with the intent to eat it before the man died.[27][28]
Blackthorn makes an excellent fire wood that burns slowly with a good heat and little smoke.[29] The wood takes a fine polish and is used for tool handles and canes.[26] Straight blackthorn stems have traditionally been made into walking sticksorclubs (known in Ireland as a shillelagh).[30] In the British Army, blackthorn sticks are carried by commissioned officers of the Royal Irish Regiment; this is a tradition also in Irish regiments in some Commonwealth countries.
The expression "sloe-eyed" for a person with dark eyes comes from the fruit, and is first attested in A. J. Wilson's 1867 novel Vashti.[34]
The flowering of the blackthorn may have been associated with the ancient Celtic celebration of Imbolc, traditionally celebrated on February 1 in Ireland, Scotland and the Isle of Man.[35]
The name of the dark-coloured cloth prunella was derived from the French word prunelle, meaning sloe.[36]
^Johns, Charles Alexander (1882). "The Blackthorn". The Forest Trees of Britain. Society for Promoting Christian Knowledge. pp. 103–112, esp. 105 – via Google Books.
^ abcd
Whitney, William Dwight; Smith, Benjamin Eli, eds. (1906). "sloe". The Century Dictionary and Cyclopedia. Vol. 7 – via Google Books.
^
Brown, Lynda (July 1994). "Damson time". House & Garden. Vol. 166. pp. 140–142, esp. 142 – via Google Books. In former times people waited to pick the sloes until the first frost which makes the skins more permeable ... [A proprietor] which makes one of the best sloe gins, recommends freezing the fruit first.
Weinberger, J.H. (1975). "Plums". In Janick, J.; Moore, J.N. (eds.). Advances in Fruit Breeding. West Lafayette, IN: Purdue University Press. pp. 336–347. ISBN0-911198-36-9.
