Blackthorn

Blackthorn
Prunus spinosa

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Blackthorn belongs to the genus Prunus and is a member of the Rose family (Rosaceae).

Blackthorn (Prunus spinosa) is a small deciduous tree growing to around 6m and flowering March to April.

Lifespan: Blackthorn has been known to live for over 100 years.

 

Characteristics

A spiny, densely branched shrub forming thickets and producing suckers. Bark is dark blackish brown. Twigs are downy when young and form straight side shoots which become thorns. Leaves are oval, toothed, pointed at the tip and tapered at the base.

Blackthorn is a hermaphrodite: it has ‘perfect’ flowers with both sexes represented in one flower. The flowers appear before the leaves in early spring, singularly or in pairs on short stalks. They are white, five-petalled (5–8mm) with long stamens and are produced abundantly.

Fruits are blue–black, globular, 15mm and very astringent. Blackthorn is insect pollinated.

Blackthorn leaves
Blackthorn flowers

Distribution

Native in much of Europe and in the UK, with a central to southern distribution.

Blackthorn can be locally abundant in hedgerows, scrub, copses and woodlands, but has been widely planted in hedgerow schemes alongside hawthorn, extending its natural range.

It is found on a wide range of soils from moist to well-drained; on acid, alkaline or neutral; and on chalk, clay, loams and sands.

Many cultivars are available for planting in gardens.

Human value

The timber is light yellow with brown heartwood; it is dense, hardwearing and tough.

It was traditionally used in turnery and for making walking sticks and tool parts. Blackthorn wood has also been used to make ‘cudgels’ a kind of baton used as a weapon. It also makes good firewood.

The fruits are also called ‘sloes’ and are collected for making wine or preserves and for flavouring gin. The name ‘Sloe’ has long been a common name for this species.

Blackthorn fruit
Blackthorn flower

Wildlife value

Blackthorn can flower as early as March making it a vital source of early nectar for bees.

Blackthorn is said to support over 150 species of insect. It is a food plant for a great many moth species, such as the lackey moth, magpie moth, common emerald, small eggar, swallow-tailed and yellow-tailed moths, and for butterflies including the black hairstreak, brown hairstreak and the scarce swallowtail.

The dense, thorny thickets provide safe nesting sites for many birds such as blackbirds, sparrows, finches, long-tailed tits, song thrush and nightingales.

Management

A hardy light-loving small shrub which is slow growing; taking from 30–50 years to reach its full height, it is easily propagated from softwood cuttings in early summer or from seed.

Blackthorn is quite tolerant to honey fungus but can be susceptible to fungal diseases which causes blossom wilt in fruit trees: Monilinia laxa and M. fructigena.

Fruits can sometimes be distorted by a gall-forming fungus Taphrina pruni.

Blackthorn buds

Illustrations © Reader’s Digest Association, Inc.
Photographs © Forestry Commission