Black locust
Encyclopedia
Robinia pseudoacacia, commonly known as the Black Locust, is a tree
in the subfamily Faboideae
of the pea family Fabaceae
. It is native to the southeastern United States
, but has been widely planted and naturalized
elsewhere in temperate North America, Europe
, Southern Africa
and Asia
and is considered an invasive species in some areas. A less frequently used common name is False Acacia
, which is a literal translation of the specific epithet. It was introduced into Britain in 1636.
. The leaves
are 10–25 cm long, pinnate with 9–19 oval leaflet
s, 2–5 cm long and 1.5–3 cm broad. Each leaf usually has a pair of short thorns at the base, 1–2 mm long or absent on adult crown shoots, up to 2 cm long on vigorous young plants. The intensely fragrant (reminiscent of orange blossoms) flower
s are white, borne in pendulous raceme
s 8–20 cm long, and are considered edible (dipped in batter; deep-fried). The fruit
is a legume 5–10 cm long, containing 4–10 seed
s.
Although similar in general appearance to the honey locust
, it lacks that tree's characteristic long branched spines on the trunk, instead having the pairs of short thorns at the base of each leaf; the leaflets are also much broader.
The black locust is native in the United States from Pennsylvania
to northern Georgia
and westward as far as Arkansas
and Oklahoma
, but has been widely spread. The tree reaches a height of seventy feet, with a trunk three or four feet in diameter and brittle branches that form an oblong narrow head. It spreads by underground shoots. The leaflets fold together in wet weather and at night; some change of position at night is a habit of the entire leguminous family.
in eastern USA, and, having been taken and planted in France
, is the source of the renowned acacia monofloral honey
from France. Flowering starts after 140 growing degree day
s. However, its blooming period is short (about 10 days) and it does not consistently produce a honey crop year after year. Weather conditions can have quite an effect on the amount of nectar collected as well; in Ohio
state for example, good honey locust flow happens in one out of five years.
In Europe it is often planted alongside streets and in parks, especially in large cities, because it tolerates pollution well. The species is unsuitable for small gardens due to its large size and rapid growth, but the cultivar 'Frisia', a selection with bright yellow-green leaves, is occasionally planted as an ornamental tree.
Black locust has nitrogen-fixing
bacteria
on its root system; for this reason it can grow on poor soils and is an early colonizer of disturbed areas.
In 1900 it was reported that the value of Robinia pseudacacia was practically destroyed in nearly all parts of the United States beyond the mountain forests which are its home by locust borers
which riddle the trunk and branches. Were it not for these insects, it would be one of the most valuable timber trees that could be planted in the northern and middle states. Young trees grow quickly and vigorously for a number of years, but soon become stunted and diseased, and rarely live long enough to attain any commercial value.
7-O-β-d-glucuronopyranosyl-(1 → 2)[α-l-rhamnopyranosyl-(1 → 6)]-β-d-glucopyranosides of acacetin
(5,7-dihydroxy-4′-methoxyflavone), apigenin
(5,7,4′-trihydroxyflavone), diosmetin
(5,7,3′-trihydroxy-4′-methoxyflavone) and luteolin
(5,7,3′,4′-tetrahydroxyflavone).
is extremely hard, resistant to rot and durable, making it prized for furniture, flooring, panelling, fence posts and small watercraft
. As a young man, Abraham Lincoln
spent much of his time splitting rails and fence posts from black locust logs. Flavonoids in the heartwood allow the wood to last over 100 years in soil. In the Netherlands and some other parts of Europe, black locust is one of the most rot-resistant local trees, and projects have started to limit the use of tropical wood by promoting this tree and creating plantations. It is one of the heaviest and hardest woods in North America.
Black Locust is highly valued as firewood
for wood-burning stove
s; it burns slowly, with little visible flame or smoke, and has a higher heat content than any other species that grows widely in the Eastern United States, comparable to the heat content of anthracite. It is most easily ignited by insertion into a hot stove with an established coal bed. For best results it should be seasoned like any other hardwood, however black locust is also popular because of its ability to burn even when wet. In fireplaces it can be less satisfactory because knots and beetle damage make the wood prone to "spitting" coals for distances of up to several feet. If the Black Locust is cut, split, and cured while relatively young (within ten years), thus minimizing beetle damage, "spitting" problems are minimal.
It is also planted for firewood because it grows rapidly, is highly resilient in a variety of soils, and it grows back even faster from its stump after harvest by using the existing root system. (see coppicing
)
With fertilizer prices rising, the importance of black locust as a nitrogen-fixing species is also noteworthy. The mass application of fertilizers in agriculture and forestry is increasingly expensive; therefore nitrogen-fixing tree and shrub species are gaining importance in managed forestry.
and fried in oil.
Important constituents of the plant are the toxalbumin robin
, which loses its toxicity when heated and robinin
, a non-toxic glucoside
. Horses that consume the plant show signs of anorexia
, depression, incontinence
, colic
, weakness, and cardiac arrhythmia. Symptoms usually occur about 1 hour following consumption, and immediate veterinary attention is required.
in the wilderness, but it is native only to North America. The locust tree of Spain (Ceratonia siliqua or Carob Tree), which is also native to Syria, is supposed to be the true locust of the New Testament; the fruit of this tree may be found in the shops under the name of St. John's bread.
Robinia is now a North American genus, but traces of it are found in the Eocene and Miocene rocks of Europe.
Tree
A tree is a perennial woody plant. It is most often defined as a woody plant that has many secondary branches supported clear of the ground on a single main stem or trunk with clear apical dominance. A minimum height specification at maturity is cited by some authors, varying from 3 m to...
in the subfamily Faboideae
Faboideae
Faboideae is a subfamily of the flowering plant family Fabaceae or Leguminosae. One acceptable alternative name for the subfamily is Papilionoideae....
of the pea family Fabaceae
Fabaceae
The Fabaceae or Leguminosae, commonly known as the legume, pea, or bean family, is a large and economically important family of flowering plants. The group is the third largest land plant family, behind only the Orchidaceae and Asteraceae, with 730 genera and over 19,400 species...
. It is native to the southeastern United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
, but has been widely planted and naturalized
Naturalisation (biology)
In biology, naturalisation is any process by which a non-native organism spreads into the wild and its reproduction is sufficient to maintain its population. Such populations are said to be naturalised....
elsewhere in temperate North America, Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
, Southern Africa
Southern Africa
Southern Africa is the southernmost region of the African continent, variably defined by geography or geopolitics. Within the region are numerous territories, including the Republic of South Africa ; nowadays, the simpler term South Africa is generally reserved for the country in English.-UN...
and Asia
Asia
Asia is the world's largest and most populous continent, located primarily in the eastern and northern hemispheres. It covers 8.7% of the Earth's total surface area and with approximately 3.879 billion people, it hosts 60% of the world's current human population...
and is considered an invasive species in some areas. A less frequently used common name is False Acacia
Acacia
Acacia is a genus of shrubs and trees belonging to the subfamily Mimosoideae of the family Fabaceae, first described in Africa by the Swedish botanist Carl Linnaeus in 1773. Many non-Australian species tend to be thorny, whereas the majority of Australian acacias are not...
, which is a literal translation of the specific epithet. It was introduced into Britain in 1636.
Description
With a trunk up to 0.8 m diameter (exceptionally up to 52 m tall and 1.6 m diameter in very old trees), with thick, deeply furrowed blackish barkBark
Bark is the outermost layers of stems and roots of woody plants. Plants with bark include trees, woody vines and shrubs. Bark refers to all the tissues outside of the vascular cambium and is a nontechnical term. It overlays the wood and consists of the inner bark and the outer bark. The inner...
. The leaves
Leaf
A leaf is an organ of a vascular plant, as defined in botanical terms, and in particular in plant morphology. Foliage is a mass noun that refers to leaves as a feature of plants....
are 10–25 cm long, pinnate with 9–19 oval leaflet
Leaflet
A leaflet in botany is a part of a compound leaf. A leaflet may resemble an entire leaf, but it is not borne on a stem as a leaf is, but rather on a vein of the whole leaf. Compound leaves are common in many plant families...
s, 2–5 cm long and 1.5–3 cm broad. Each leaf usually has a pair of short thorns at the base, 1–2 mm long or absent on adult crown shoots, up to 2 cm long on vigorous young plants. The intensely fragrant (reminiscent of orange blossoms) flower
Flower
A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants . The biological function of a flower is to effect reproduction, usually by providing a mechanism for the union of sperm with eggs...
s are white, borne in pendulous raceme
Raceme
A raceme is a type of inflorescence that is unbranched and indeterminate and bears pedicellate flowers — flowers having short floral stalks called pedicels — along the axis. In botany, axis means a shoot, in this case one bearing the flowers. In a raceme, the oldest flowers are borne...
s 8–20 cm long, and are considered edible (dipped in batter; deep-fried). The fruit
Fruit
In broad terms, a fruit is a structure of a plant that contains its seeds.The term has different meanings dependent on context. In non-technical usage, such as food preparation, fruit normally means the fleshy seed-associated structures of certain plants that are sweet and edible in the raw state,...
is a legume 5–10 cm long, containing 4–10 seed
Seed
A seed is a small embryonic plant enclosed in a covering called the seed coat, usually with some stored food. It is the product of the ripened ovule of gymnosperm and angiosperm plants which occurs after fertilization and some growth within the mother plant...
s.
Although similar in general appearance to the honey locust
Honey locust
The Honey locust, Gleditsia triacanthos, is a deciduous tree native to central North America. It is mostly found in the moist soil of river valleys ranging from southeastern South Dakota to New Orleans and central Texas, and as far east as eastern Massachusetts.-Description:Honey locusts, Gleditsia...
, it lacks that tree's characteristic long branched spines on the trunk, instead having the pairs of short thorns at the base of each leaf; the leaflets are also much broader.
The black locust is native in the United States from Pennsylvania
Pennsylvania
The Commonwealth of Pennsylvania is a U.S. state that is located in the Northeastern and Mid-Atlantic regions of the United States. The state borders Delaware and Maryland to the south, West Virginia to the southwest, Ohio to the west, New York and Ontario, Canada, to the north, and New Jersey to...
to northern Georgia
Georgia (U.S. state)
Georgia is a state located in the southeastern United States. It was established in 1732, the last of the original Thirteen Colonies. The state is named after King George II of Great Britain. Georgia was the fourth state to ratify the United States Constitution, on January 2, 1788...
and westward as far as Arkansas
Arkansas
Arkansas is a state located in the southern region of the United States. Its name is an Algonquian name of the Quapaw Indians. Arkansas shares borders with six states , and its eastern border is largely defined by the Mississippi River...
and Oklahoma
Oklahoma
Oklahoma is a state located in the South Central region of the United States of America. With an estimated 3,751,351 residents as of the 2010 census and a land area of 68,667 square miles , Oklahoma is the 28th most populous and 20th-largest state...
, but has been widely spread. The tree reaches a height of seventy feet, with a trunk three or four feet in diameter and brittle branches that form an oblong narrow head. It spreads by underground shoots. The leaflets fold together in wet weather and at night; some change of position at night is a habit of the entire leguminous family.
- Bark: Dark gray brown tinged with red, deeply furrowed, surface inclined to scale. Branchlets at first coated with white silvery down. This soon disappears and they become pale green, afterward reddish brown. Prickles develop from stipules, are short, somewhat triangular, dilated at base, sharp, dark purple, adhering only to the bark, but persistent.
- Wood: Pale yellowish brown; heavy, hard, strong, close-grained and very durable in contact with the ground. The wood has a specific gravitySpecific gravitySpecific gravity is the ratio of the density of a substance to the density of a reference substance. Apparent specific gravity is the ratio of the weight of a volume of the substance to the weight of an equal volume of the reference substance. The reference substance is nearly always water for...
0.7333, and a weight of approximately 45.7 pounds per cubic foot. - Winter buds: Minute, naked, three or four together, protected in a depression by a scale-like covering lined on the inner surface with a thick coat of tomentum and opening in early spring; when forming are covered by the swollen base of the petiole.
- Leaves: Parallel, compound, odd-pinnate, 21-40 inches long, with slender hairy petioles, grooved and swollen at the base. Leaflets petiolate, seven to nine, one to two inches long, one-half to three-fourths of an inch broad, emarginate or rounded at apex. They come out of the bud conduplicate, yellow green, covered with silvery down which soon disappears; when full grown are dull dark green above, paler beneath. Feather-veined, midvein prominent. In autumn they turn a clear pale yellow. Leafs out relatively late in spring. Stipules linear, downy, membranous at first, ultimately developing into hard woody prickles, straight or slightly curved. Each leaflet has a minute stipel which quickly falls and a short petiole.
- Flowers: May or June, after the leaves. Papilionaceous. Perfect, borne in loose drooping racemes four to five inches long, cream-white, about an inch long, nectar bearing, fragrant. Pedicels slender, half an inch long, dark red or reddish green.
- Calyx: Campanulate, gibbous, hairy, five-toothed, slightly two-lipped, dark green blotched with red, especially on the upper side teeth valvate in bud.
- Corolla: Imperfectly papilionaceous, petals inserted upon a tubular disk; standard white with pale yellow blotch; wings white, oblong-falcate; keel petals incurved, obtuse, united below.
- Stamens: Ten, inserted, with the petals, diadelphous, nine inferior, united into a tube which is cleft on the upper side, superior one free at the base. Anthers two-celled, cells opening longitudinally.
- Pistil: Ovary superior, linear-oblong, stipitate, one-celled; style inflexed, long, slender, bearded; stigma capitate; ovules several, two-ranked.
- Fruit: legume two-valved, smooth three to four inches long and half an inch broad, usually four to eight seeded. Ripens late in autumn and hangs on the branches until early spring. Seeds dark orange brown with irregular markings. Cotyledons oval, fleshy.
Cultivation
Black locust is a major honey plantNorthern Nectar Sources for Honeybees
The nectar source in a given area depends on the type of vegetation present and the length of their bloom period. What type of vegetation will grow in an area depends on soil texture, soil pH, soil drainage, daily maximum and minimum temperatures, precipitation, extreme minimum winter temperature,...
in eastern USA, and, having been taken and planted in France
France
The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...
, is the source of the renowned acacia monofloral honey
Monofloral honey
Monofloral honey is a type of honey which has a high value in the marketplace because it has a distinctive flavor or other attribute due to its being predominantly from the nectar of one plant species....
from France. Flowering starts after 140 growing degree day
Growing degree day
Growing degree days , also called growing degree units , are a heuristic tool in phenology. GDD are a measure of heat accumulation used by horticulturists, gardeners, and farmers to predict plant and pest development rates such as the date that a flower will bloom or a crop reach...
s. However, its blooming period is short (about 10 days) and it does not consistently produce a honey crop year after year. Weather conditions can have quite an effect on the amount of nectar collected as well; in Ohio
Ohio
Ohio is a Midwestern state in the United States. The 34th largest state by area in the U.S.,it is the 7th‑most populous with over 11.5 million residents, containing several major American cities and seven metropolitan areas with populations of 500,000 or more.The state's capital is Columbus...
state for example, good honey locust flow happens in one out of five years.
In Europe it is often planted alongside streets and in parks, especially in large cities, because it tolerates pollution well. The species is unsuitable for small gardens due to its large size and rapid growth, but the cultivar 'Frisia', a selection with bright yellow-green leaves, is occasionally planted as an ornamental tree.
Black locust has nitrogen-fixing
Nitrogen fixation
Nitrogen fixation is the natural process, either biological or abiotic, by which nitrogen in the atmosphere is converted into ammonia . This process is essential for life because fixed nitrogen is required to biosynthesize the basic building blocks of life, e.g., nucleotides for DNA and RNA and...
bacteria
Bacteria
Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...
on its root system; for this reason it can grow on poor soils and is an early colonizer of disturbed areas.
In 1900 it was reported that the value of Robinia pseudacacia was practically destroyed in nearly all parts of the United States beyond the mountain forests which are its home by locust borers
Megacyllene robiniae
Common names: Locust BorerThe Locust Borer is a serious pest to Robinia pseudoacacia in North America. The name is derived from the Latin name "Robinia" which is the same as the genus of locust on which the larvae feed.-Description:...
which riddle the trunk and branches. Were it not for these insects, it would be one of the most valuable timber trees that could be planted in the northern and middle states. Young trees grow quickly and vigorously for a number of years, but soon become stunted and diseased, and rarely live long enough to attain any commercial value.
Flavonoids content
Black locust leaves contain flavone glycosides characterised by spectroscopic and chemical methods as theAcacetin
Acacetin is an O-methylated flavone found in Robinia pseudoacacia and Turnera diffusa .The enzyme apigenin 4'-O-methyltransferase uses S-adenosyl methionine and 5,7,4'-trihydroxyflavone to produce S-adenosylhomocysteine and 4'-methoxy-5,7-dihydroxyflavone ....
(5,7-dihydroxy-4′-methoxyflavone), apigenin
Apigenin
Apigenin is a flavone that is the aglycone of several glycosides. It is a yellow crystalline solid that has been used to dye wool. Apigenin may contribute to the chemopreventive action of vegetables and fruits...
(5,7,4′-trihydroxyflavone), diosmetin
Diosmetin
Diosmetin is an O-methylated flavone, a chemical compound that can be found in the Caucasian vetch...
(5,7,3′-trihydroxy-4′-methoxyflavone) and luteolin
Luteolin
Luteolin is a yellow crystalline compound. It is a flavonoid; to be specific, it is one of the more common flavones. From preliminary research, it is thought to play a role in the human body possibly as an antioxidant, a free radical scavenger, a promoter of carbohydrate metabolism, or an immune...
(5,7,3′,4′-tetrahydroxyflavone).
Uses
The woodWood
Wood is a hard, fibrous tissue found in many trees. It has been used for hundreds of thousands of years for both fuel and as a construction material. It is an organic material, a natural composite of cellulose fibers embedded in a matrix of lignin which resists compression...
is extremely hard, resistant to rot and durable, making it prized for furniture, flooring, panelling, fence posts and small watercraft
Dinghy
A dinghy is a type of small boat, often carried or towed for use as a ship's boat by a larger vessel. It is a loanword from either Bengali or Urdu. The term can also refer to small racing yachts or recreational open sailing boats. Utility dinghies are usually rowboats or have an outboard motor,...
. As a young man, Abraham Lincoln
Abraham Lincoln
Abraham Lincoln was the 16th President of the United States, serving from March 1861 until his assassination in April 1865. He successfully led his country through a great constitutional, military and moral crisis – the American Civil War – preserving the Union, while ending slavery, and...
spent much of his time splitting rails and fence posts from black locust logs. Flavonoids in the heartwood allow the wood to last over 100 years in soil. In the Netherlands and some other parts of Europe, black locust is one of the most rot-resistant local trees, and projects have started to limit the use of tropical wood by promoting this tree and creating plantations. It is one of the heaviest and hardest woods in North America.
Black Locust is highly valued as firewood
Firewood
Firewood is any wood-like material that is gathered and used for fuel. Generally, firewood is not highly processed and is in some sort of recognizable log or branch form....
for wood-burning stove
Wood-burning stove
For a list of stove types see Stove .A wood-burning stove is a heating appliance capable of burning wood fuel and wood-derived biomass fuel. Generally the appliance consists of a solid metal closed fire chamber, a grate and an adjustable air control...
s; it burns slowly, with little visible flame or smoke, and has a higher heat content than any other species that grows widely in the Eastern United States, comparable to the heat content of anthracite. It is most easily ignited by insertion into a hot stove with an established coal bed. For best results it should be seasoned like any other hardwood, however black locust is also popular because of its ability to burn even when wet. In fireplaces it can be less satisfactory because knots and beetle damage make the wood prone to "spitting" coals for distances of up to several feet. If the Black Locust is cut, split, and cured while relatively young (within ten years), thus minimizing beetle damage, "spitting" problems are minimal.
It is also planted for firewood because it grows rapidly, is highly resilient in a variety of soils, and it grows back even faster from its stump after harvest by using the existing root system. (see coppicing
Coppicing
Coppicing is a traditional method of woodland management which takes advantage of the fact that many trees make new growth from the stump or roots if cut down. In a coppiced wood, young tree stems are repeatedly cut down to near ground level...
)
With fertilizer prices rising, the importance of black locust as a nitrogen-fixing species is also noteworthy. The mass application of fertilizers in agriculture and forestry is increasingly expensive; therefore nitrogen-fixing tree and shrub species are gaining importance in managed forestry.
Toxicity
Black locust's pods are small and light, and easily carried long distances. Although the bark and leaves are toxic, various reports suggest that the seeds and the young pods of the black locust can be edible when cooked, since the poisons that are contained in this plant are decomposed by heat. In France Robinia pseudoacacia flowers are eaten as beignets after being dunked in batterBatter (cooking)
Batter is a semi-liquid mixture of one or more flours combined with liquids such as water, milk or eggs used to prepare various foods. Often a leavening agent such as baking powder is included to aerate and fluff up the batter as it cooks, or the mixture may be naturally fermented for this purpose...
and fried in oil.
Important constituents of the plant are the toxalbumin robin
Toxalbumin
Toxalbumins are toxic plant proteins that disable ribosomes and thereby inhibit protein synthesis, producing severe cytotoxic effects in multiple organ systems. They are dimers held together by a disulfide bond and comprise a lectin part which binds to the cell membrane and enables the toxin part...
, which loses its toxicity when heated and robinin
Robinin
Robinin is a chemical compound. It can be isolated from Vinca erecta or from the common locust Robinia pseudoacacia....
, a non-toxic glucoside
Glucoside
A glucoside is a glycoside that is derived from glucose. Glucosides are common in plants, but rare in animals. Glucose is produced when a glucoside is hydrolysed by purely chemical means, or decomposed by fermentation or enzymes....
. Horses that consume the plant show signs of anorexia
Anorexia (symptom)
Anorexia is the decreased sensation of appetite...
, depression, incontinence
Incontinence
Incontinence or Incontinent may refer to:*Fecal incontinence, the inability to control one's bowels*Incontinence *Incontinent , a 1981 album by Fad Gadget*Urinary incontinence, the involuntary excretion of urine...
, colic
Horse colic
Colic in horses is defined as abdominal pain, but it is a clinical sign rather than a diagnosis. The term colic can encompass all forms of gastrointestinal conditions which cause pain as well as other causes of abdominal pain not involving the gastrointestinal tract. The most common forms of colic...
, weakness, and cardiac arrhythmia. Symptoms usually occur about 1 hour following consumption, and immediate veterinary attention is required.
History
The name locust is said to have been given to Robinia by Jesuit missionaries, who fancied that this was the tree that supported St. JohnJohn the Baptist
John the Baptist was an itinerant preacher and a major religious figure mentioned in the Canonical gospels. He is described in the Gospel of Luke as a relative of Jesus, who led a movement of baptism at the Jordan River...
in the wilderness, but it is native only to North America. The locust tree of Spain (Ceratonia siliqua or Carob Tree), which is also native to Syria, is supposed to be the true locust of the New Testament; the fruit of this tree may be found in the shops under the name of St. John's bread.
Robinia is now a North American genus, but traces of it are found in the Eocene and Miocene rocks of Europe.
External links
- Robinia pseudoacacia images at bioimages.vanderbilt.edu
- Robinia pseudoacacia images at Forestry Images
- Robinia pseudoacacia - US Forest Service Fire Effects Database
- Robinia pseudoacacia at USDA Plants Database
- Black Locust - US Forest Service Silvics Manual
- Black Locust (as an invasive species)
- Robinia pseudoacacia 'Frisia'
- Interactive Distribution Map of Robinia pseudoacacia
- Robinia pseudoacacia flowers as food