The black locust (scientific name Robinia pseudoacacia) is a deciduous tree that grows up to a height of 60 to 80 feet and has broad, deeply grooved, deep brown and splitting branches. The tree is native to North America having originated in the Appalachian Mountains and is said to be nectarous. The tree bears leaves that are often able to reach lengths of 8 to10 inches and comprise elliptical leaflets that are around 1 to 2.5 inches long. At the base of each leaf there is a pair of thorns that are approximately half an inch in length. The black locust is such variety that it grows on its own accord on nearly every type of soil, but prefers even meadows with sandy soils. As the black locust trees have a very hard core and are extremely moisture resistant, the wood of the tree is used in different kinds of building purposes, including ships and manufacturing plaques. In addition, the black locust leaves and flowers also possess therapeutic properties and are used to treat several disorders.
The tree produces white and pleasantly aromatic flowers that appear in bunch during May and June. The flowers have a resemblance to the pea blossoms and produces fruits that are brown-reddish flattened seedpods that enables one to identify the species as a member of the pea family. Since the tree is indigenous to North America, it is said that long back the native Indians used the bark of black locust to prepare cathartics and potent purgatives. However, as the black locust encloses minor toxic elements, these medications were never widely accepted by the masses. The wood of the black locust is the most important part of the tree and is extensively used in the construction industry. Nevertheless, posts made from black locust are so firm and hardy that they are able to withstand all weather conditions for over 50 years. This particular aspect of the tree encouraged the early settlers in North America to extensively grown the tree all over the continent. In the early part of the 17th century, the seeds of black locust were sent to Paris to Jean Robin, the botanist and landscaper to the then king of France, and he was the first to plant black locust in Europe. It is interesting to note that the species derived its scientific name ‘Robinia' from Jean Robin. From this period, the black locust has been extensively planted in France, England and other regions of Eastern Europe. Over the years, the tree has emerged to be the most significant timber tree in countries like Romania and Hungary.
From time to time, numerous Europeans have undertaken a number of researches to ascertain the therapeutic properties of black locust. They prepared an infusion with the dried flowers of the tree to cure nausea, headaches and also stomach pains. In addition, flowers of black locust were soaked in wine and the liquid was taken internally as a medication for anemia.
Flowers, wood, bark, leaves, seeds.
The different parts of the black locust tree have different therapeutic properties and they include the aptitude to cure spasms, viral attacks, expel waste from the body, purify the system, energize the body, promote the flow of bile and even treat cancer. In addition, some of these parts are scented and function as diuretic, emollients, laxative, and purgative. Besides, some of them are narcotic in nature too.
Blossoms of black locust are scented and possess anti-spasmodic, diuretic, laxative and emollient (aptitude to soothe) properties. Many people even cook the flowers and consume them to cure eye problems. Flowers of black locust are believed to enclose an anti-tumor or tumor combating chemical called benzoaldehyde. On the other hand, the inside bark and the root bark of the species are capable to expelling wastes from the body and are usually used as purgatives and stimulants or energizers. Many people chew the root bark of the tree to bring out vomiting and it is also retained in the mouth to alleviate toothache. However, it is interesting to note that despite such medicinal properties of the black locust bark, it is hardly prescribed by the herbal medical practitioners to treat any of the above mentioned problems. The fruits or berries, especially the seedpods, have narcotic properties and are often used as an analgesic. When ingested, the leaves of the tree are able to enhance the secretion and flow of bile as well as soothe the aggravated organs. In addition to these, the juice extracted from the leaves help to combat or restrain viruses.
The wood of black locust is very hard and durable and, hence, is usually used as fence posts, mine timbers and railway ties. Another advantage of the black locust is that its rapid growth has made it a favorite of the environmentalists who prefer to grow them to control soil erosion. In addition, the tree is also useful for yielding colorants, fiber and fuel.
Black locust seeds yield oil, while the flowers produce an essential oil. The essential oil obtained from the flowers of this species is extremely appreciated and used by the cosmetic industry in making perfumes. The bark of the tree yields a yellow colorant called ‘Robinetin' that is very potent dye that is compliant with various corrosives in distinct shades muck akin to the colorants acquired with quercetin, fisetin and myricetin. Using aluminum, robinetin colors cotton materials to a brownish-orange tint. Although the bark of black locust encloses some amount of tannin, it is not adequate for commercial use. Normally, when the humidity is around 10 per cent, the tannin content in the bark is around 7.2 per cent, while the hard central wood of young trees contains around 5.7 per cent of tannin at the same moisture level. Interesting, the bark of this species is also utilized in making paper and it also often serves as a replacement for silk and wool! As mentioned earlier, the black locust trees are able to develop secondary shoots from under the ground easily and rapidly (sucker) and when they form dense thickets they are useful for protecting embankments.
Habitat and cultivation
Black locust grows over an extensive area in North America. While the tree is found in abundance between the stretches from Nova Scotia to Ontario in Canada, in the United States, black locust grows all over from Maine to California. The species flourishes in any type of soil having adequate drainage system. Nevertheless, the black locust does not grow well in rich or fertilized soils. The tree has the aptitude to survive even in arid and barren locations and is able to withstand drought as well as air pollution.
The black locust plants thrive well in a hot and arid situation. Plants of this species are able to withstand yearly average rainfall ranging between 60 cm to about 200 cm, an annual temperature range of 7.6° C to 20.3° C and a pH ranging between 6.0 and 7.0. Black locust grows rapidly during the first 30 years of their existence and may start blossoming from the sixth year. However, the tree normally bears flowers when it is 10-12 years old. The black locust is an ideal bee plant and hence its blossoms enclose abundance of nectar and have an aroma similar to vanilla. Although the tree grows to a height of around 30 meters, its branches are awfully easily broken and liable to damage by strong winds. As discussed earlier, black locust does not prefer very rich or fertile soil and, hence, when they are grown on such soils, their development is rough and poor and they are then more susceptible to damage by winds. In addition, the black locust is a normal sucker (it is able to rapidly develop secondary shoots from below the ground) and, hence, is able to form intense woods even after being destroyed by cutting or wild moving fires. Besides, the suckers have thorns that are pretty nasty.
However, there are some popular varieties of black locust that do not possess thorns and are primarily grown for their ornamental value. If these black locust plants require any trimming then it should be undertaken during the end of summer with a view to avoid or lessen the risk of the plants bleeding. The leaves of this species enclose abundance of tannin and other materials that, in effect, slow down the growth of other plants in the neighborhood. The black locust is infamous as a ravenous tree that depletes all minerals from the soil making it poor as far as its fertility is concerned. The tree is, however, unaffected by honey fungus and an excellent bee plant.
Black locust propagates by means of its seeds and winter is the most suitable time to sow the seeds of this species. The seeds need to be soaked for around 48 hour in warm water before sowing in a cold frame. If the seeds are put under a brief period of stratification, it enhances the speed as well as time of their germination. After the saplings have grown big enough to be handled, pluck them out individually and place them in a greenhouse where they need to spend their first winter. The plants may be put into their permanent place outdoors during the subsequent summer. According to many herbalists, it is possible to sow the seeds outdoors during the spring in properly made beds. The seeds of black locust may be preserved for more than 10 years without being damaged or rendered infertile.
The chemical composition of the black locust varies in its different parts - seeds, flowers, bark and roots. Black locust flowers enclose a yellow glucosid that is able to form crystals, robinin (C25H20O16) that splits into quercetin and a non-fermentable sugar following hydrolysis. The dehydrated black locust seeds enclose fat, proteins, fiber, calcium, phosphorous, a number of vitamins and small amounts of different minerals. On the other hand, when the bark of the tree is chewed it produces a strong emeto-catharsis. In addition to these, scientists have found a static albumin, little amounts of the toxic alkaloid, choline, some fatty substances, cane sugar (also called air-dry bark), inactive resin, starch, some amount of tannin, gum, a colorant and perhaps asparagin.