British Native Trees
and Shrubs

Blackthorn or Sloe Prunus spinosa (Rosaceae)

How oft, my slice of pocket store consumed,
Still hungering, penniless and far from home,
I fed on scarlet hips and stony haws,
Or blushing crabs, or berries, that emboss
The bramble, black as jet, or sloes austere.
The Charm of the Country from The Task

William Cowper [1731-1800]

 

Blackthorn’s dark tangle of spiny branches is smothered with a mass of tiny, pure-white flowers in spring, but autumn is its high point when the lustrous bluish-black fruits glow amongst the foliage. The upright, deciduous shrub or small tree has stiff, black, thorny twigs and seldom reaches more than 4 m in height, and on older plants the bark fractures into small, scale-like squares. Its little five-petalled flowers with red anthers blossom in March and April before the small, oval, finely-toothed, fresh-green leaves appear on reddish stalks. The leaves becoming longer, up to 4 cm, narrower and a darker, duller green as they mature. In September or October come the almost round fruits, or sloes, each a gleaming purplish-black with a bluish-white bloom. But do not be tempted to bite into the pale green flesh as it is mouth-witheringly acid.

Blackthorn is widespread in hedgerows, on woodland margins and in scrub on all types of soil except the most acid, throughout the lowlands of England, but up to 400 m in the Lake District.

This dense, thorny shrub makes a first-class anti-burglar and animal-proof hedge, keeping its green leaves until October or November and providing spring blossom and autumn fruit. It prefers a fairly open position on almost any soil except the most peaty and acid, and it does not like heavy shade but will protect smaller plants growing underneath. It withstands exposure to strong winds. Blackthorn suckers freely and soon makes dense thickets unless it is controlled, making is suitable only for a large garden. It is propagated from seed treated in the same way as that of wild cherry, and seedlings can be planted out after three years.

The sloes can be used to make jelly or wine, or sloe gin when steeped in spirit. Knobbly walking sticks and marquetry are made from the hard, durable wood.

A blackthorn hedge makes an excellent, well-protected nesting site for garden birds, while the flowers produce nectar for humble bees and early-flying small tortoiseshell butterflies. The leaves are the main foodplant of the larvae of black and brown hairstreak butterflies and are host to a gall midge which may produce up to 60 blisters round the margin of a single leaf.

Page last updated - January 10, 2002  

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