Blackthorn
leaves
The common
name of this small thorny tree or bush is due to the fact that its bark has a
much darker hue than that of the Hawthorn, which is also known as 'Whitethorn'.
'Spinosa' refers to the long spiny thorny shoots on the tree
Habitat
The Blackthorn is possibly one of the commonest European shrubs. It grows from
the British Isles, throughout Europe, into Western Siberia on any soil, except
for wet and acid peat-bogs. We are able to find it almost anywhere in Britain,
but in the North of Scotland it is more thinly spread.
Look for it in hedges, in clearings, on the edges of woodlands, on the edges of
neglected farmland, on dry slopes and waste land. Wherever its colonising habit
is allowed to continue without human interference, it will grow dense thickets,
which form natural tree nurseries for larger tree species, who will eventually
outgrow the Blackthorn.
General Appearance
A thorny shrub or small tree of 1-4 metres height. It often has more than one
main stem, due to the rapid spread of the roots and the growth of suckers from
these roots. The branches are stiff and rigid and usually thick set with many
closely intersecting twigs, which make it rather impenetrable. On close
examination, we find many spiny dwarf shoots on the branches, i.e. the shoots
terminate into a hardened thorn. The branches, buds and leaves are arranged
spirally in an 'alternate' (as opposed to 'opposite') fashion.
Bark
The winter twigs are very alike to Hawthorn, but the bark is smoother and
darker, sometimes almost black and often with a slate-grey hue or greenish hue.
The branches may may also have a reddish-brown to purple hue and have tiny
lenticel spots on them. New shoots have closely crowded, velvety hairs on them,
but these are soon lost. The tiny, nearly elliptical leaf-scar generally shows
three dots, where the leaf-trace bundles were attached.
Leaves
The leaves appear after the flowers have faded, usually in April. The leaves are
small and pointed oval to nearly lanceolate in shape on short stems. The size is
about 2-4 cm long. The colour is dull-green and there are tiny hairs on the
veins underneath the leaves. The edges of the leaf are very finely and
irregularly toothed. The central vein gives off 6 or more pairs of weak
secondary veins, which break up near the margin into tertiaries. In Autumn the
leaves may turn yellow and red.
Flowers
The white flowers appear early in the year (from end February to April,
depending on location) on the bare branches. They have a 5 lobed calyx and 5
white petals 5-8 mm long. Remember again, that the 5-petalled flowers are a
distinguishing feature of the Rose family. These hermaphrodite flowers can
appear single, in pairs or in close clusters on a small stalk. There are about
20 stamens, white with an orange head, clustered around a central green pistil
with a yellow head. All these little stamens reaching out gives the flowers a
happily ragged appearance. The pistils are ripe before the stamens, so
self-fertilisation is avoided. The flowers contain nectar and have a subtle
sweet smell to attract the insects on which it depends for pollination.
Fruits
By the end of June the smooth green berries are virtually full-size, about 1 cm
across. By Mid-August the colour changes to a purplish dark-blue with a misty
bloom over its skin, although the astringent flesh inside stays green. Each sloe
berry has one central stone or seed. The sloes ripen in September to October.
Cultivation
The Blackthorn grows long spreading roots, which send up shoots, known also as
suckers, which will quickly grow into healthy young trees. The easiest way to
propagate the Blackthorn therefore, is to dig up some of these baby trees,
including a bit of the root and plant these out where you want the tree to grow.
Alternatively, the sloe can be harvested and seeded. Plant straight after
picking and cover with about 1 cm of soil.