A fearsome, thorny tree producing purple fruits known as sloes, popular steeped in gin but, being tannin-rich, highly astringent and almost inedible raw. Surprisingly, Blackthorn is one of the ancestral parents of Domestic Plum. Also simply called Sloe. Found in woodland glades and edges, hedgerows and field edges, and even on exposed cliffs and coastal shingle as a prostrate form. Adept at suckering and browse-resistant, it spreads into dense thickets.
Native to most of Europe, limited only at northern latitudes, spreading east through the Balkans, Caucasus, to the Ural Mountains. Very widely distributed in Britain and Ireland where it is native, but infrequent in the Scottish Highlands and far north.
Monoecious, producing single hermaphrodite flowers that are insect-pollinated. Fruits contain a single seed, distributed by birds and mammals. Also colonises by suckering.
Small (5-7m), with stiff, viciously thorned branches, often suckering densely into impenetrable thickets. Bark dark purple-black, finely rough. Twigs soon smooth with thorned tips. Leaves ovate or obovate, 2-4cm, wrinkled, soon smooth except the underside veins, sharply serrate. Flowers cream-white (15mm), singly or in pairs on bare branches before the leaves (March-April). Fruit a globular drupe (15mm), blue-purple to glossy black with an easily wiped waxy bloom, bitter and sour, with a large stone held to the flesh.
Blackthorn thrives almost everywhere but especially tolerates heavy clay. It can be included in a hedge to deter any animal, though it spreads outwards into fields and grassland. It can be laid, but beware its vicious thorns, which defeat thick gloves and cause instant pain and joint synovitis when they penetrate the skin (vanishing once removed). Sloes are traditionally left until the first frost softens (blets) them before picking.
Its early spring flowers attract pollinators and its fruit feeds birds. The foliage feeds the larvae of at least 150 insects, including Black Hairstreak (Satyrium pruni), Brown Hairstreak (Thecla betulae) and Swallowtail (Papilio machaon) butterflies. It is closely associated with the endangered (in Britain) Nightingale (Luscinia megarhynchos), which needs dense thorny scrub to nest, and with shrikes ('butcher birds') that impale prey on its thorns. It is very effective at controlling soil erosion.
Generally a very robust species.
Sloes are rich in vitamin C and can be combined with higher-pectin fruits like crab apples to make jellies and preserves, but their most popular use is steeping in gin with equal sugar to make sloe gin (also brandy and port). The yellow-brown timber, rarely sold commercially, suits turnery and small box-making. Hedgerow stems make fine walking sticks and were the traditional material for the shillelagh, cured in a chimney for a year.
