Blackthorn (scientific name Prunus spinosa L.) is a thorny shrub native to Eurasia that usually grows up to a height of 4 meters. The branches of this woody shrub are very thorny and protected with hairs like velvet when they are young. The shrub bears pale green leaves, white flowers and bluish-black round-shaped fruits. The ovate leaves are small and grow alternately on the branches. They are very much serrated and the veins on the underside are hairy to some extent. The shrub bears abundance of flowers that appear singularly as well as in pairs along the thorny branches. The fruits usually ripen in October and are coarse and caustic growing up to approximately half an inch in diameter.
There are several species of Prunus and many of them possess therapeutic characteristics. For instance, the fruit stems of the European wild cherry (scientific name P. avium) have been conventionally used by herbal medical practitioners as an astringent and diuretic. It is important to mention here that the European wild cherry must not be mistaken for the morello cherry or amarelle cherry (scientific name P. cerasus) whose leaves are traditionally used to prepare an herbal tea. The bark of another species of Prunus, American wild cherry or black cherry (scientific name P. serotina) is used in the preparation of a ‘wild cherry syrup', which is a very popular medication to treat cough. In China, people have been traditionally using little quantities of apricot seeds (scientific name P. armeniaca) as cough syrups and the oil extracted from the seeds for cosmetic purposes. In Europe, people have been traditionally preparing cherry-laurel water from P. larocerasus and used it as a medication to stimulate respiration. Similarly, the fruits of the Japanese apricot, also called wu mei, is an astringent and effective medication for cough as well as diarrhea.
Dried flowers and fresh or dried ripe fruits.
Nearly all parts of the blackthorn shrub are medicinally useful. The leaves, flowers, fruits and even the bark of this woody shrub possess purgative, astringent, purifying, diaphoretic, laxative, disinfectant and diuretic properties and they are beneficial for the stomach. A tea prepared with the blackthorn flowers is a safe and consistent purgative and is useful for the stomach and, at the same time, increases craving for food. Herbal medical practitioners prescribe this tea to treat minor gallbladder problems, skin complaints, catarrh, stone formations and cramps in the stomach. It is especially useful in treating diarrhea among children and also for curing kidney problems. The blackthorn berries are usually more pleasant to eat when they are collected after going through 2 or 3 nights of frost. The juice extracted from the blackthorn fruits or berries is useful in curing swelling and irritation in the mouth, gum and throat. On the other hand, a decoction prepared with the shrub's bark helps to lower fever. However, the flowers of the shrub seem to possess the most therapeutic value. Traditionally, herbal medical practitioners have attributed numerous medicinal features, such as expectorant, diuretic, gentle laxative and diaphoretic, to the blackthorn flowers.
Despite the fact that the herbalists have not particularly talked about the blackthorn (Prunus spinosa L.), all species of this class enclose amygdalin (a bitter cyanogenic glucoside extracted from the apricot and plum seeds) and prunasin (the crystalline cyanogenetic glucoside found in various plants of the genus Prunus) matters that disintegrate into water to produce hydrocyanic acid (also called cyanide or prussic acid). This is an extremely poisonous substance, but when taken in small dosages, the chemical kindles breathing, enhances digestion and also induces a feeling of health and happiness.
The bark of the blackthorn is also of multiple uses. For instance, it is not only an excellent resource for natural tannin, but is also used widely in preparing ink. When the bark of blackthorn is boiled in an alkali it yields a yellow colorant. Even the juice extracted from the unripe blackthorn berries is made use of by the washer men to mark the clothes as it is more or less difficult to erase. The soft tissues or pulp from the ripened berries are utilized for cosmetic purposes, such as preparing astringent facial masks. On the other hand, the green leaves of the shrub serve to prepare a green colorant, while the fruit may be used to obtain a colorant that varies in hue from deep gray to green. A significant aspect of the blackthorn is that the shrub is resilient to marine conditions and bears secondary shoots for rapid growth and expansion. If enclosures made with blackthorn shrubs are properly conserved they are able to resist harsh weather conditions. However, the hedge lies bare during the winter months owing to shedding of leaves by the shrub and unless it is quite extensive, it does not provide adequate shelter during this season. The suckering nature or the inclination of giving rise to secondary shoots, the blackthorn is able to overrun agricultural lands and develops conditions that are suitable for the restoration of woods. The blackthorn grows quickly even after being chopped down or destroyed by rapidly spreading forest fires. The suckering nature of the shrub enables it to develop secondary shoots from below the ground and regenerate rapidly creating dense thickets. These species of Prunus are remarkably unaffected by honey fungus.
Blackthorn wood: The woody stems of the blackthorn shrubs are so tough that they are generally made use of to manufacture turnery (machines for lathe workshop), the teeth of rakes or hoes and several similar hardy items. The right branches of the blackthorn are used to manufacture walking sticks and they are extremely appreciated for this use owing to their entwined and attractive forms.
Habitat and cultivation
Basically, the blackthorn is known to be a Eurasian species. The shrub is indigenous to several regions, including Europe, western Asia as well as North Africa where the most common species is P. spinosa. In eastern regions of Europe, the shrub and its products are harvested from the wild.
The shrub is generally grown for decorative reasons. In nature, blackthorn grows untamed in cleaned lands, in the midst of hedges, along the periphery of woodlands, sunlit mountain slopes, on moorlands and in meadows where the soil contains sufficient lime. To thrive well, the blackthorn needs a well-drained soil that is capable of retaining moisture. The shrub grows best in clay soil as well as limestone. Although the blackthorn has a preference for some pigment in the soil, presence of it in excess may render the shrub weak or sickly.
The blackthorn blooms during March and April and the seeds of the berries mature sometime during October. The flowers of the shrub are hermaphrodite having both sex organs and are generally fertilized by insects. The flowers of the blackthorn are susceptible to frost and are sometimes damaged by late frosting. Hence, it is natural that the flowers of the blackthorn are an attraction for the wildlife. In fact, the blackthorn serves as a significant food plant for the caterpillars of many different butterfly species, particularly the black and brown hairstreak butterflies. The shrub is also a fine bee plant. As the shrub suckers freely, it forms an excellent nesting place for different birds, particularly the nightingale.
The blackthorn reproduces by means of its seeds. The seeds germinate fast and better if they are sown in a cold frame immediately after they are mature. The seeds need two to three months cold stratification (placing them in layers of cold). It is advisable to sow the stockpiled seeds in a cold frame very early in the year and remember to guard the seeds from rats and other pests. In fact, the germination of the seeds may take very long, at time consuming as may as 18 months to sprout.
Once the shoots have come out and sufficiently big to cope with, pick them up individually and place them into separate pots. During their first winter, the plants ought to be grown in a greenhouse or in cold frames with a view to protect them from frost. The plants may be planted in their permanent place outdoors during the next spring or late summer. The plant may be grown from cuttings of half-mature wood of the shrub with a heel during July-August and plant them in a frame. Soft wood from mature and vigorously growing plants may be cut during spring or early summer and planted in a frame. Again the layering or stratification may be done during the spring. The plant may also be grown by division of the suckers when they are inactive. These suckers may be directly planted outdoors at their permanent places.
The chemical composition of blackthorn largely comprises flavonoids, tannins, cyanogenic glycosides, prunasin that forms prussic acid (hydrogen cyanide or HCN) and benzaldehyde having a ‘marzipan' odor following an enzymatic hydrolysis.
An infusion prepared with one gram or two grams of dried flowers may be ingested in the morning or night to cure inflammation of the mouth and throat. In addition, an infusion prepared with two to four grams of the dried blackthorn fruit or fresh juice extracted from the berries is an effective gargle. However, remember that the infusion must be made fresh each time and if it tastes astringent, you may add some honey to sweeten it.
Side effects and cautions
As discussed earlier, HCN or hydrocyanic acid (also called cyanide or prussic acid) formed by some chemicals present in blackthorn is a very potent poison and medications prepared with the shrub must not always be taken internally. The compound is so poisonous that even five to twelve seeds of bitter almonds (scientific name P. dulcis var. amara) may prove to be deadly for small children. Even cherry-laurel water prepared from from P. larocerasus, which is useful in stimulating respiration, may enclose HCN. As a result one needs to be extra cautious while using medications prepared with blackthorn or its parts and they should always be taken under the supervision of a qualified healthcare professional.