Blackthorn is our commonest wild plum, growing in hedgerows and on waste ground throughout the British Isles and across northern Europe. Its botanical name Prunus spinosa (thorny plum) is aptly named, and is derived from its vicious black thorns.
Blackthorn is usually seen as a hedgerow shrub. It is very aggressive and if left alone spreads out across fields by means of sucker shoots springing up across its roots. The resulting thicket protects the unarmed saplings of other trees from damage by animals, including deer, so helping the formation of taller woodland. However, annual mowing of fields keeps the trees in the hedgerows forming excellent stock-proof hedges. It can grow twenty feet tall, with a trunk two feet around.
Blackthorn flowers early, towards the end of March and just after the spring equinox where day-length equals night. Flowering before the leaves to show spectacular masses of snow-white blossoms on black twigs.
Blackthorn is remarkable for having two names in several languages, one for the tree and one for the fruit. The tree is usually "Black thorn" due to its black bark and thorns, the fruit is called "Sloe".
Like the cherries, the early flowering, blackthorn provides a valuable source of nectar and pollen for bees in spring. Its foliage is a food plant for the caterpillars of many moths, including the lackey, magpie, swallow-tailed and yellow-tailed. It is also used by the black and brown hairstreak butterflies. Birds nest among the dense, thorny thickets, eat caterpillars and other insects from the leaves, and feast on the sloes in autumn.
