This section is from the book "British Wild Flowers - In Their Natural Haunts Vol2-4", by A. R. Horwood. Also available from Amazon: A British Wild Flowers In Their Natural Haunts.
Preglacial, Interglacial, and Neolithic beds have yielded evidence of the early occurrence of this plant in Britain. In its present distribution it is confined to Europe, but the Bullace is found in Africa and the Himalayas, both in the Warm Temperate Zone. In Great Britain it is found south of Sutherland throughout the country, up to a height of 1300 ft. in Yorkshire. It is met with in Ireland and the Channel Islands.
The Sloe is so common a wayside plant as scarcely to need description. It is found not only by the highway, with Spindle, Maple, Crab, Hawthorn, Cornel, and Elder, but also in the hedgerows, in fields, and in woods, forming dense brakes in the latter, or in the open, where the Blackthorn blossoms make the otherwise dark growth of branches quite white in early spring.
As the Latin specific name indicates this plant is peculiarly spinous, which separates it from P. instititia, where there are few spines. The plant is a bushy tree with numerous interlacing branches, rigid.
The Sloe has the shrub habit. It is small, rigid, much-branched, the branches spreading, zigzag, spinous (hence spinosa), the spines being- arrested branches. The wood is hard and tough. The bark is black. The leaves appear after the flowers. They are egg-shaped, or oblong to lance-shaped, stalked, and vary considerably in form, in the acuteness of the leaf, and in the length of the stalk. They are downy below when young, later hairless, and are toothed.
The flowers are white, 1/2 - 5/8 in. across, shortly-stalked, the stalks solitary or in pairs, hairless. The petals are inversely egg-shaped to oblong, and vary in breadth. The fruit is a drupe, the flesh adhering to the stone, round. When the carpel becomes the fruit the layers are three, the skin or epicarp, the flesh or mesocarp, and the inner stony endocarp, the three forming the pericarp, the seed being the kernel within the stone. There are two ovules, one often being undeveloped.
The plant is often 15 ft. high, and grows in clumps, several being associated together forming bush-land. It is one of the earliest wild flowers in March and April. The Sloe is a deciduous shrub, propa-gated by seeds.
The flowers are conspicuous, and contain abundant honey, and owing to their appearance before the leaves and the early flowering are much visited by insects. The stigma matures before the anthers. In the first stage the style is considerably above the stamens. The anthers have not yet opened, and are bent down towards the centre The stigma is already receptive, and projects. It is therefore first touched by an insect visitor, the petals becoming more or less horizontal. The stamens become erect, and bend outwards. The outer anthers open first. The style lengthens and overtops the short stamens, which stand near the centre. As the stigma is at this stage still receptive, self-pollination may thus occur by the agency of insect visitors. In their absence self-pollination may occur as the flowers turn to the sun, from the inflection of the stamens toward the centre above the stigma, causing pollen to fall on the latter.
Photo. Rev. C. A. Hall - Blackthorn (prunus Spinosa, L.)
The flower is visited by Hymenoptera (Apidae), Diptera (Empidae.
Syrphidae, Muscidae, Bibionidae), Coleoptera (Nitidulidae), Lepidoptera (Vanessa).
The fruit is edible, and the seed is dispersed by animals.
The Sloe is at home on sand soil, and is a sand plant, but is also a lime plant, loving limestone, and a humus-loving plant requiring humus soil. A fungus, Puccinia pruni, causes early fall of the leaf.
Eriophyes similis is a gall that attacks it. Many larger fungi grow on it: Stereum, Podosphcera, Eutypella, Polystigma, Plowrightia, Poly-porus, Hypocmis, Entomospo-rium, Corynum, Cladosporium. It is also galled by Cecidomyia pruni and Biorhiza terminalis; and the beetles Otiorhynchus picipes, Monochetus sulcatus, Magdalinus pruni, Rhynchites auratus, the Hymenopterous insects Andrena bucephala, Eriocampa adumbrata, Lepidoptera Black Hairstreak ( Thecla pruni), Scarlet Tiger (Callimorpha dominula), Yellow Tail Moth (Liparis auri-flua), Grey Dagger (Acrony-ata psi), White-letter Hair-streak ( Thecla W. album), Brown Hairstreak (T. betulce), Short-cloaked Moth (Nola cucullatella), etc, and the Homopterous Capsus capillaris, the Homoptera Psylla pruni, Trichopsylla Walkeri feed on it.
Prunus, Pliny, is Latin for plum-tree, and the second Latin name refers to the spinose character.
The names it goes by are: Blackberry, Blackthorn, Blackthorn-May, Buckthorn, Bullens, Bullies, Bullins, Bullister, Cat's-sloes, Egg-peg Bushes, Hedge Picks, Hedge Speaks, Heg Peg Bushes, Hep, Winter Kecksies, May Blackthorn, Quick Scrog, Skig Slaathorn, Slacen-bush, Slan, Slaunbush, Slea, Sloey, Slon, Slone Bloom, Sloo-bush, Slines, Snag, Snagbush, Winter Picks.
Quick or Quicks are young black or white thorn for planting in a hedge. The name Sloe for the fruit is extended to the plant itself, and sloes are recommended for fences. Blackthorn distinguishes it from Whitethorn or May.
Blackthorn (Prunus Spinosa, L.)
Blackthorn Chats are the young shoots when they have been cut down.
The " Lay of Runzifal " makes a Blackthorn shoot out of the bodies of slain heathens, a white flower by the heads of fallen Christians. It was held antagonistic to witchcraft. In Surrey it is always cold when the Blackthorn comes in flower.
" When the Sloe tree is as white as a sheet, Grow your barley whether it be dry or not."
It is the origin of the Bullace and the Plum. In a wild state it has spines. The fruit is very astringent. A conserve is made from it, and port wine has been made from it as well as sloe gin. It has been used for marking ink. Lye or tea used to be made from the leaves. It has been substituted for cinchona bark for ague and fever. As a wood it is used for the teeth of rakes.
Essential Specific Characters: 91. Primus spinosa, L. - Shrubby, stems woody, branched, twigs zigzag, spinose, black, leaves elliptical, narrow, downy below, after the flowers; flowers white, 1-2, peduncle glabrous, fruit globose.