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''Robinia pseudoacacia'', commonly known in its native territory as black locust, is a medium-sized hardwood
deciduous In the fields of horticulture and Botany, the term ''deciduous'' () means "falling off at maturity" and "tending to fall off", in reference to trees and shrubs that seasonally shed leaves, usually in the autumn; to the shedding of petals, afte ...
tree In botany, a tree is a perennial plant with an elongated Plant stem, stem, or trunk (botany), trunk, usually supporting branches and leaves. In some usages, the definition of a tree may be narrower, including only woody plants with secondar ...
, belonging to the tribe
Robinieae The tribe Robinieae is one of the subdivisions of the plant family Fabaceae and the currently unranked taxon Robinioids. The following genera are recognized by the USDA The United States Department of Agriculture (USDA) is the federal exe ...
of the legume family Fabaceae. It is endemic to a few small areas of the
United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territo ...
, but it has been widely planted and
naturalized Naturalization (or naturalisation) is the legal act or process by which a non-citizen of a country may acquire citizenship or nationality of that country. It may be done automatically by a statute, i.e., without any effort on the part of the in ...
elsewhere in temperate North America, Europe,
Southern Africa Southern Africa is the southernmost subregion of the African continent, south of the Congo and Tanzania. The physical location is the large part of Africa to the south of the extensive Congo River basin. Southern Africa is home to a number of ...
and
Asia Asia (, ) is one of the world's most notable geographical regions, which is either considered a continent in its own right or a subcontinent of Eurasia, which shares the continental landmass of Afro-Eurasia with Africa. Asia covers an area ...
and is considered an invasive species in some areas. Another common name is false acacia, a literal translation of the specific name (''pseudo'' reek ''ψευδο-''meaning fake or false and ''
acacia ''Acacia'', commonly known as the wattles or acacias, is a large genus of shrubs and trees in the subfamily Mimosoideae of the pea family Fabaceae. Initially, it comprised a group of plant species native to Africa and Australasia. The genus nam ...
'' referring to the genus of plants with the same name).


Description

Black locust reaches a typical height of with a diameter of . It is a very upright tree with a straight trunk and narrow crown that grows scraggly with age. The dark blue-green compound leaves with a contrasting lighter underside give this tree a beautiful appearance in the wind and contribute to its grace. Black locust is a shade-intolerant species and therefore is typical of young woodlands and disturbed areas where sunlight is plentiful and the soil is dry. In this sense, black locust can be considered a weed tree. It also spreads by underground shoots or suckers, which contributes to the weedy character of this species. Young trees are often spiny, but mature trees often lack spines. In the early summer black locust flowers; the flowers are large and appear in large, intensely fragrant clusters reminiscent of orange blossoms. The leaflets fold together in wet weather and at night (
nyctinasty Nyctinasty is the circadian rhythmic nastic movement of higher plants in response to the onset of darkness, or a plant "sleeping". Nyctinastic movements are associated with diurnal light and temperature changes and controlled by the circadian clo ...
), as some change of position at night is a habit of the entire
leguminous A legume () is a plant in the family Fabaceae (or Leguminosae), or the fruit or seed of such a plant. When used as a dry grain, the seed is also called a pulse. Legumes are grown agriculturally, primarily for human consumption, for livestock fo ...
family. Although similar in general appearance to the
honey locust The honey locust (''Gleditsia triacanthos''), also known as the thorny locust or thorny honeylocust, is a deciduous tree in the family Fabaceae, native to central North America where it is mostly found in the moist soil of river valleys. Honey ...
, the black locust lacks that tree's characteristic long branched thorns on the trunk, having instead pairs of short prickles at the base of each leaf; the leaflets are also much broader than honey locust. It may resemble ''
Styphnolobium japonicum ''Styphnolobium japonicum'', the Japanese pagoda tree (also known as the Chinese scholar tree and pagoda tree; syn. ''Sophora japonica'') is a species of tree in the subfamily Faboideae of the pea family Fabaceae. It was formerly included withi ...
'', which has smaller flower spikes and lacks spines.


Detailed description

*The bark is a reddish black and gray and tinged with red or orange in the grooves. It is deeply furrowed into grooves and ridges which run up and down the trunk and often cross and form diamond shapes. *The roots of black locust contain nodules that allow it to fix nitrogen, as is common within the pea family. *The branches are typically zig-zaggy and may have ridges and grooves or may be round. When young, they are at first coated with white silvery down; this soon disappears, and they become pale green and afterward reddish or greenish brown. * Spines may or may not be present on young trees, root suckers, and branches near the ground; typically, branches high above the ground rarely contain spines. ''R. pseudoacacia'' is quite variable in the number of spines present, as some trees are densely prickly and other trees have no prickles at all. The spines typically remain on the tree until the young thin bark to which they are attached is replaced by the thicker mature bark. They develop from
stipules In botany, a stipule is an outgrowth typically borne on both sides (sometimes on just one side) of the base of a leafstalk (the petiole). Stipules are considered part of the anatomy of the leaf of a typical flowering plant, although in many spe ...
(small leaf-like structures that grow at the base of leaves), and since stipules are paired at the base of leaves, the spines will be paired at the bases of leaves. They range from in length and are somewhat triangular with a flared base and sharp point. Their color is of a dark purple and they adhere only to the bark. *Wood is pale yellowish brown, heavy, hard, strong, close-grained, and very durable in contact with the ground. The wood has a
specific gravity Relative density, or specific gravity, is the ratio of the density (mass of a unit volume) of a substance to the density of a given reference material. Specific gravity for liquids is nearly always measured with respect to water at its densest ...
of 0.733 (733 kilograms per cubic metre or 45.7 pounds per cubic foot). *The leaves are
compound Compound may refer to: Architecture and built environments * Compound (enclosure), a cluster of buildings having a shared purpose, usually inside a fence or wall ** Compound (fortification), a version of the above fortified with defensive struc ...
, meaning that each leaf contains many smaller leaf like structures called leaflets, which are roughly paired on either side of the stem that runs through the leaf (
rachis In biology, a rachis (from the grc, ῥάχις [], "backbone, spine") is a main axis or "shaft". In zoology and microbiology In vertebrates, ''rachis'' can refer to the series of articulated vertebrae, which encase the spinal cord. In this c ...
). There is typically one leaflet at the tip of the leaf ( odd pinnate), and the leaves are alternately arranged on the stem. Each leaf is long and contains 9–19 leaflets, each being long, and wide. The leaflets are rounded or slightly indented at the tip and typically rounded at the base. The leaves come out of the bud folded in half, yellow green, covered with silvery down which soon disappears. Each leaflet initially has a minute stipel, which quickly falls, and is connected to the (
rachis In biology, a rachis (from the grc, ῥάχις [], "backbone, spine") is a main axis or "shaft". In zoology and microbiology In vertebrates, ''rachis'' can refer to the series of articulated vertebrae, which encase the spinal cord. In this c ...
) by a short stem or petiolule. The leaves are attached to the branch with slender hairy petioles which are grooved and swollen at the base. The stipules are linear, downy, membranous at first and occasionally develop into prickles. The leaves appear relatively late in spring. *The leaf color of the fully grown leaves is a dull dark green above and paler beneath. In autumn. the leaves turn a clear pale yellow. *The flowers open in May or June for 7–10 days, after the leaves have developed. They are arranged in loose drooping clumps (
raceme A raceme ( or ) or racemoid is an unbranched, indeterminate type of inflorescence bearing flowers having short floral stalks along the shoots that bear the flowers. The oldest flowers grow close to the base and new flowers are produced as the s ...
s) which are typically long. The flowers themselves are cream-white (rarely pink or purple) with a pale yellow blotch in the center and imperfectly
papilionaceous Papilionaceous flowers (from Latin: ''papilion'', a butterfly) are flowers with the characteristic irregular and butterfly-like corolla found in many, though not all, plants of the species-rich Faboideae subfamily of legumes. Tournefort suggeste ...
in shape. They are about wide, very fragrant, and produce large amounts of nectar. Each flower is perfect, having both
stamens The stamen (plural ''stamina'' or ''stamens'') is the pollen-producing reproductive organ of a flower. Collectively the stamens form the androecium., p. 10 Morphology and terminology A stamen typically consists of a stalk called the filam ...
and a
pistil Gynoecium (; ) is most commonly used as a collective term for the parts of a flower that produce ovules and ultimately develop into the fruit and seeds. The gynoecium is the innermost whorl of a flower; it consists of (one or more) '' pistils ...
(male and female parts). There are 10 stamens enclosed within the petals; these are fused together in a diadelphous configuration, where the filaments of 9 are all joined to form a tube and one stamen is separate and above the joined stamens. The single ovary is superior and contains several ovules. Below each flower is a calyx which looks like leafy tube between the flower and the stem. It is made from fused
sepal A sepal () is a part of the flower of angiosperms (flowering plants). Usually green, sepals typically function as protection for the flower in bud, and often as support for the petals when in bloom., p. 106 The term ''sepalum'' was coined ...
s and is dark green and may be blotched with red. The
pedicels In botany, a pedicel is a stem that attaches a single flower to the inflorescence. Such inflorescences are described as ''pedicellate''. Description Pedicel refers to a structure connecting a single flower to its inflorescence. In the absenc ...
(stems which connect the flower to the branch) are slender, , dark red or reddish green. *The fruit is a typical
legume A legume () is a plant in the family Fabaceae (or Leguminosae), or the fruit or seed of such a plant. When used as a dry grain, the seed is also called a pulse. Legumes are grown agriculturally, primarily for human consumption, for livestock for ...
fruit, being a flat and smooth pea-like pod long and broad. The fruit usually contains 4–8 seeds. The seeds are dark orange brown with irregular markings. They ripen late in autumn and hang on the branches until early spring. There are typically 25,500 seeds per pound. *Winter
bud In botany, a bud is an undeveloped or embryonic shoot and normally occurs in the axil of a leaf or at the tip of a stem. Once formed, a bud may remain for some time in a dormant condition, or it may form a shoot immediately. Buds may be spec ...
s: Minute, naked (having no scales covering them), 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 the buds are forming they are covered by the swollen base of the petiole. * Cotyledons are oval in shape and fleshy.


Reproduction and dispersal

Black locust reproduces both sexually via flowers, and asexually via root suckers. The flowers are pollinated by insects, primarily by
Hymenoptera Hymenoptera is a large order of insects, comprising the sawflies, wasps, bees, and ants. Over 150,000 living species of Hymenoptera have been described, in addition to over 2,000 extinct ones. Many of the species are parasitic. Females typic ...
n insects. The physical construction of the flower separates the male and female parts so that self-pollination will not typically occur. The seedlings grow rapidly but they have a thick seed coat which means that not all seeds will germinate. The seed coat can be weakened via hot water, sulfuric acid, or be mechanically scarified, which will allow a greater quantity of the seeds to grow. The seeds are produced in good crops every year or every other year. Root suckers are an important method of local reproduction of this tree. The roots may grow suckers after damage (by being hit with a lawn mower or otherwise damaged) or after no damage at all. The suckers are stems which grow from the roots, directly into the air and may grow into full trees. The main trunk also has the capability to grow sprouts and will do so after being cut down. This makes removal of black locust difficult as the suckers need to be continually removed from both the trunk and roots or the tree will regrow. This is considered an asexual form of reproduction. The suckers allow black locust to grow into colonies which often exclude other species. These colonies may form dense thickets which shade out competition. Black locust has been found to have either 2n=20 or 2n=22 chromosomes.


Flavonoids content

Black locust leaves contain flavone glycosides characterised by spectroscopic and chemical methods as the 7-''O''-β-ᴅ-glucuronopyranosyl-(1→2) �-ʟ-rhamnopyranosyl-(1→6)β-ᴅ-glucopyranosides of acacetin (5,7-dihydroxy-4′-methoxyflavone),
apigenin Apigenin (4′,5,7-trihydroxyflavone), found in many plants, is a natural product belonging to the flavone class that is the aglycone of several naturally occurring glycosides. It is a yellow crystalline solid that has been used to dye wool. Sou ...
(5,7,4′-trihydroxyflavone), diosmetin (5,7,3′-trihydroxy-4′-methoxyflavone) and
luteolin Luteolin is a flavone, a type of flavonoid, with a yellow crystalline appearance. Luteolin is the principal yellow dye compound that is obtained from the plant ''Reseda luteola'', which has been used as a source of the dye since at least the firs ...
(5,7,3′,4′-tetrahydroxyflavone).


Taxonomy

The black locust is a plant from the subfamily of
Faboideae The Faboideae are a subfamily of the flowering plant family Fabaceae or Leguminosae. An acceptable alternative name for the subfamily is Papilionoideae, or Papilionaceae when this group of plants is treated as a family. This subfamily is widely ...
in the family of
legume A legume () is a plant in the family Fabaceae (or Leguminosae), or the fruit or seed of such a plant. When used as a dry grain, the seed is also called a pulse. Legumes are grown agriculturally, primarily for human consumption, for livestock for ...
s (
Fabaceae The Fabaceae or Leguminosae,International Code of Nomenc ...
) and is a relative of the pea and bean. The black locust is commonly referred to as "false acacia" after its species name "pseudoacacia", although it is not particularly closely related to the
acacia ''Acacia'', commonly known as the wattles or acacias, is a large genus of shrubs and trees in the subfamily Mimosoideae of the pea family Fabaceae. Initially, it comprised a group of plant species native to Africa and Australasia. The genus nam ...
, which belongs to the
mimosa ''Mimosa'' is a genus of about 590 species of herbs and shrubs, in the mimosoid clade of the legume family Fabaceae. The generic name is derived from the Greek word (''mimos''), an "actor" or "mime", and the feminine suffix -''osa'', "resembl ...
subfamily (
Mimosoideae The Mimosoideae are a traditional subfamily of trees, herbs, lianas, and shrubs in the pea family (Fabaceae) that mostly grow in tropical and subtropical climates. They are typically characterized by having radially symmetric flowers, with petals ...
). Both species are similar in the form of their feathered leaves and thorns, but the flower shapes are very different. Confusion between species of both genera is almost impossible in higher latitudes, since acacias are native to subtropical and tropical areas and do not thrive in the cooler climates favoured by the black locust.


History and naming

The tree was identified in 1607 at Jamestown by British colonists, who used the timber to build houses. The tree was named for its resemblance to ''
Ceratonia siliqua The carob ( ; ''Ceratonia siliqua'') is a flowering evergreen tree or shrub in the Caesalpinioideae sub-family of the legume family, Fabaceae. It is widely cultivated for its edible fruit pods, and as an ornamental tree in gardens and landsca ...
'', known as the "Old World Locust". Jesuit missionaries apparently fancied that this was the tree that supported St. John in the wilderness, but it is native only to North America. It was introduced into Britain in 1636. ''Robinia'' is a native North American genus, but traces of it are found in the
Eocene The Eocene ( ) Epoch is a geological epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period in the modern Cenozoic Era. The name ''Eocene'' comes from the Ancient Greek (''ēṓs'', "daw ...
and
Miocene The Miocene ( ) is the first geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and means "less recent" ...
rocks of Europe. The genus is named after the royal French gardeners Jean Robin and his son Vespasien Robin, who brought the plant to Europe in 1601, in what may be regarded as a reintroduction. A black locust planted by Vespasien Robin still exists in the Square René Viviani in Paris.


Distribution and invasive habit

The black locust is native to the eastern United States, but the exact native range is not accurately known as the tree has been cultivated and is currently found across the continent, in all the lower 48 states, eastern Canada, and British Columbia. The native range is thought to be two separate populations, one centered about the
Appalachian Mountains The Appalachian Mountains, often called the Appalachians, (french: Appalaches), are a system of mountains in eastern to northeastern North America. The Appalachians first formed roughly 480 million years ago during the Ordovician Period. They ...
, from
Pennsylvania Pennsylvania (; (Pennsylvania Dutch: )), officially the Commonwealth of Pennsylvania, is a state spanning the Mid-Atlantic, Northeastern, Appalachian, and Great Lakes regions of the United States. It borders Delaware to its southeast, Mary ...
to northern
Georgia Georgia most commonly refers to: * Georgia (country), a country in the Caucasus region of Eurasia * Georgia (U.S. state), a state in the Southeast United States Georgia may also refer to: Places Historical states and entities * Related to the ...
, and a second westward focused around the
Ozark Plateau The Ozarks, also known as the Ozark Mountains, Ozark Highlands or Ozark Plateau, is a physiographic region in the U.S. states of Missouri, Arkansas, Oklahoma and the extreme southeastern corner of Kansas. The Ozarks cover a significant porti ...
and
Ouachita Mountains The Ouachita Mountains (), simply referred to as the Ouachitas, are a mountain range in western Arkansas and southeastern Oklahoma. They are formed by a thick succession of highly deformed Paleozoic strata constituting the Ouachita Fold and Thru ...
of
Arkansas Arkansas ( ) is a landlocked state in the South Central United States. It is bordered by Missouri to the north, Tennessee and Mississippi to the east, Louisiana to the south, and Texas and Oklahoma to the west. Its name is from the Osage la ...
,
Oklahoma Oklahoma (; Choctaw: ; chr, ᎣᎧᎳᎰᎹ, ''Okalahoma'' ) is a state in the South Central region of the United States, bordered by Texas on the south and west, Kansas on the north, Missouri on the northeast, Arkansas on the east, New M ...
and
Missouri Missouri is a U.S. state, state in the Midwestern United States, Midwestern region of the United States. Ranking List of U.S. states and territories by area, 21st in land area, it is bordered by eight states (tied for the most with Tennessee ...
. Black locust's current range has been expanded by humans distributing the tree for landscaping and now includes
Pakistan Pakistan ( ur, ), officially the Islamic Republic of Pakistan ( ur, , label=none), is a country in South Asia. It is the world's fifth-most populous country, with a population of almost 243 million people, and has the world's second-lar ...
,
India India, officially the Republic of India (Hindi: ), is a country in South Asia. It is the seventh-largest country by area, the second-most populous country, and the most populous democracy in the world. Bounded by the Indian Ocean on the so ...
, Australia, Canada, China, Europe, Northern and South Africa, temperate regions in Asia, New Zealand, Southern South America. Black locust is an interesting example of how one plant species can be considered invasive even on the continent to which it is native. For example, within the western United States, New England region, northern California, and in the Midwest, black locust is considered an
invasive species An invasive species otherwise known as an alien is an introduced organism that becomes overpopulated and harms its new environment. Although most introduced species are neutral or beneficial with respect to other species, invasive species ad ...
. In the prairie and savanna regions of the Midwest black locust can dominate and shade open habitats. These ecosystems have been decreasing in size, and black locust is contributing to this reduction; when black locust invades an area, it will convert the grassland ecosystem into a forested ecosystem where the grasses are displaced. Black locust has been listed as invasive in Connecticut, Wisconsin, and Michigan, and is prohibited in Massachusetts. In Australia black locust has become
naturalized Naturalization (or naturalisation) is the legal act or process by which a non-citizen of a country may acquire citizenship or nationality of that country. It may be done automatically by a statute, i.e., without any effort on the part of the in ...
within Victoria, New South Wales, South Australia and Western Australia. It is considered an environmental weed there. In South Africa, it is regarded as a weed because of its suckering habit. In
Asia Asia (, ) is one of the world's most notable geographical regions, which is either considered a continent in its own right or a subcontinent of Eurasia, which shares the continental landmass of Afro-Eurasia with Africa. Asia covers an area ...
, many black locusts, called cihuai ( :zh:刺槐), yanghuai (foreign huai :zh:洋槐, against native huai :zh:国槐) or simply "acacias", were planted in Dalian, Liaoning, China, during its Russian and Japanese occupation, and are loved by the local people: there is Acacia Avenue (槐树大道) in downtown; the Acacia Flower Festival (槐花節) is celebrated every year in May; and acacia honey is collected in the suburbs by
bee keepers Beekeeping (or apiculture) is the maintenance of bee colonies, commonly in man-made beehives. Honey bees in the genus '' Apis'' are the most-commonly-kept species but other honey-producing bees such as '' Melipona'' stingless bees are also kept. ...
.


Ecology

When growing in sandy areas this plant can enrich the soil by means of its nitrogen-fixing nodules, allowing other species to move in. On sandy soils black locust may replace other vegetation which cannot fix nitrogen. Black locust is a typical early successional plant, a
pioneer species Pioneer species are hardy species that are the first to colonize barren environments or previously biodiverse steady-state ecosystems that have been disrupted, such as by wildfire. Pioneer flora Some lichens grow on rocks without soil, so ...
. It grows best in bright sunlight and does not handle shade well. It specializes in colonizing disturbed areas and edges of woodlots before it is eventually replaced with taller or more shade-tolerant species. It prefers dry to moist limestone soils but will grow on most soils as long as they are not wet or poorly drained. This tree tolerates a soil pH range of 4.6 to 8.2. Within its native range it will grow on soils of
Inceptisols Inceptisols are a soil order in USDA soil taxonomy. They form quickly through alteration of parent material. They are more developed than Entisols. They have no accumulation of clays, iron oxide, aluminium oxide or organic matter. They have an ...
,
Ultisols Ultisols, commonly known as red clay soils, are one of twelve soil orders in the United States Department of Agriculture soil taxonomy. The word "Ultisol" is derived from "ultimate", because Ultisols were seen as the ultimate product of continu ...
, and
Alfisols Alfisols are a soil order in USDA soil taxonomy. Alfisols form in semi-arid to humid areas, typically under a hardwood forest cover. They have a clay-enriched subsoil and relatively high native fertility. "Alf" refers to aluminium (Al) and iron ( ...
groups, but does not do well on compacted, clayey or eroded soils. Black locust is a part of the
Appalachian mixed mesophytic forests The Appalachian mixed mesophytic forests is an ecoregion of the temperate broadleaf and mixed forests biome, as defined by the World Wildlife Fund. It consists of mesophytic plants west of the Appalachian Mountains in the Southeastern United Sta ...
. Black locust is host to up to 67 species of
lepidoptera Lepidoptera ( ) is an order of insects that includes butterflies and moths (both are called lepidopterans). About 180,000 species of the Lepidoptera are described, in 126 families and 46 superfamilies, 10 percent of the total described specie ...
, and provides valuable cover when planted on previously open areas. Its seeds are eaten by bobwhite quail and other game birds and squirrels. Woodpeckers may nest in the trunk since older trees are often infected by heart rot.


Pests

Locust leaf miner '' Odontota dorsalis'' attacks the tree in spring and turns the leaves brown by mid summer, slowing the growth of the tree though not seriously. Locust borer '' Megacyllene robiniae'' larvae carve tunnels into the trunk of the tree and make it more prone to being knocked down by the wind. Heart rot is the only significant disease affecting black locust. Black locust is also attacked by '' Chlorogenus robiniae'', a virus which causes
witch's broom Witch's broom or witches' broom is a deformity in a woody plant, typically a tree, where the natural structure of the plant is changed. A dense mass of shoots grows from a single point, with the resulting structure resembling a broom or a ...
growths; clear leaflet veins are a symptom of the disease.


Cultivation

Black locust is a major honey plant in the eastern US, and has been planted in European countries. In many European countries, it is the source of the renowned acacia honey. Flowering starts after 140
growing degree day Growing degree days (GDD), also called growing degree units (GDUs), are a heuristic tool in phenology. GDD are a measure of heat accumulation used by horticulturists, gardeners, and farmers to predict plant and animal development rates such as th ...
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 () is a state in the Midwestern region of the United States. Of the fifty U.S. states, it is the 34th-largest by area, and with a population of nearly 11.8 million, is the seventh-most populous and tenth-most densely populated. The sta ...
for example, good locust honey flow happens in one of five years. Black locust can be easily propagated from roots, softwood, or hardwood. Cultivars may be grafted, ensuring that parent and daughter plants will be genetically identical.''R. pseudoacacia'' is considered an excellent plant for growing in highly disturbed areas as an erosion control plant. Black locust's shallow, aggressive roots help hold onto the soil, and
nitrogen-fixing Nitrogen fixation is a chemical process by which molecular nitrogen (), with a strong triple covalent bond, in the air is converted into ammonia () or related nitrogenous compounds, typically in soil or aquatic systems but also in industry. Atmo ...
bacteria on its root system allow it to grow on poor soils, making it an early colonizer of disturbed areas. Obviating the mass application of fertilizers, black locust and other nitrogen-fixing tree and shrub species have gained importance in managed forestry. Black locust is planted for firewood, as it grows rapidly, is highly resilient in a variety of soils, and it grows back rapidly after harvest from the existing root system. (see coppicing) In Europe, it is often planted along streets and in parks, especially in large cities, because it tolerates pollution well.


Cultivars

Several cultivars exist, 'Frisia' being one of the most planted ones. *'Decaisneana' has been considered a cultivar but is more accurately a hybrid (''R. pseudoacacia'' x ''R. viscosa''). It has light rose-pink colored flowers and small or no prickles. *‘Frisia’, a selection with bright yellow-green leaves and red prickles, is occasionally planted as an
ornamental tree Ornamental plants or garden plants are plants that are primarily grown for their beauty but also for qualities such as scent or how they shape physical space. Many flowering plants and garden varieties tend to be specially bred cultivars that i ...
. *'Purple robe' has dark rose-pink flowers and bronze red new growth. The flowers tend to last longer than on the wild tree. *'Tortuosa', a small tree with curved and distorted branches. *'Unifoliola', a plant with fewer leaflets, no prickles, and a shorter height.


Toxicity

The bark, leaves, and wood are toxic to both humans and livestock. Important constituents of the plant are the toxalbumin robin, which loses its toxicity when heated, and robinin, a nontoxic
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. The name was o ...
. Horses that consume the plant show signs of
anorexia Anorexia nervosa, often referred to simply as anorexia, is an eating disorder characterized by low weight, food restriction, body image disturbance, fear of gaining weight, and an overpowering desire to be thin. ''Anorexia'' is a term of Gre ...
, depression,
incontinence Incontinence or Incontinent may refer to: *Fecal incontinence, the involuntary excretion of bowel contents *Urinary incontinence Urinary incontinence (UI), also known as involuntary urination, is any uncontrolled leakage of urine. It is a com ...
, colic, weakness, and
cardiac arrhythmia Arrhythmias, also known as cardiac arrhythmias, heart arrhythmias, or dysrhythmias, are irregularities in the heartbeat, including when it is too fast or too slow. A resting heart rate that is too fast – above 100 beats per minute in adults ...
. Symptoms usually occur about 1 hour following consumption, and immediate veterinary attention is required.


Uses

Black locust has been spread and used as a plant for erosion control as it is fast growing and generally a tough tree. The wood, considered the most durable wood in North America, has been very desirable and motivated people to move the tree to areas where it is not native so the wood can be farmed and used.


Wood

The
wood Wood is a porous and fibrous structural tissue found in the stems and roots of trees and other woody plants. It is an organic materiala natural composite of cellulose fibers that are strong in tension and embedded in a matrix of lignin th ...
is extremely hard, being one of the hardest woods in Northern America with a
Janka hardness test The Janka hardness test (; ), created by Austrian-born American researcher Gabriel Janka (1864–1932), measures the resistance of a sample of wood to denting and wear. It measures the force required to embed an steel ball halfway into a sample ...
of 1,700 lbf (7,560 N). It is very resistant to rot, and durable, making it prized for furniture, flooring, paneling, fence posts, and small watercraft. Black Locust is a highly durable organic wood product that does not require chemical treatment to preserve its beauty for 50 years or longer. Wet, newly cut planks have an offensive odor which disappears with seasoning. Black locust is still in use in some rustic
handrail A handrail is a rail that is designed to be grasped by the hand so as to provide safety or support. In Britain, handrails are referred to as banisters. Handrails are usually used to provide support for body or to hold clothings in a bathroom o ...
systems. 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.
Flavonoid Flavonoids (or bioflavonoids; from the Latin word ''flavus'', meaning yellow, their color in nature) are a class of polyphenolic secondary metabolites found in plants, and thus commonly consumed in the diets of humans. Chemically, flavonoids ...
s in the heartwood allow the wood to last over 100 years in soil. Black locust is highly valued as
firewood Firewood is any wooden 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, compared to other forms of wood fuel like pellets or chips. Firewood can ...
for
wood-burning stove A wood-burning stove (or wood burner or log burner in the UK) is a heating or cooking appliance capable of burning wood fuel and wood-derived biomass fuel, such as sawdust bricks. Generally the appliance consists of a solid metal (usually cast i ...
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 Anthracite, also known as hard coal, and black coal, is a hard, compact variety of coal that has a submetallic luster. It has the highest carbon content, the fewest impurities, and the highest energy density of all types of coal and is the high ...
. For best results, it should be seasoned like any other hardwood, but 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 10 years), thus minimizing beetle damage, "spitting" problems are minimal. With a light yellowish color and strength, the wood was much used for decorative inlays and banding in furniture in England and France in the 17th and 18th centuries, under the name "acacia" or "Virginia acacia". In 1900, the value of ''Robinia pseudoacacia'' was reported to be 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.


Food and medicine

In
traditional medicine Traditional medicine (also known as indigenous medicine or folk medicine) comprises medical aspects of traditional knowledge that developed over generations within the folk beliefs of various societies, including indigenous peoples, before the ...
of
India India, officially the Republic of India (Hindi: ), is a country in South Asia. It is the seventh-largest country by area, the second-most populous country, and the most populous democracy in the world. Bounded by the Indian Ocean on the so ...
, different parts of ''R. pseudoacacia'' are used as
laxative Laxatives, purgatives, or aperients are substances that loosen stools and increase bowel movements. They are used to treat and prevent constipation. Laxatives vary as to how they work and the side effects they may have. Certain stimulant, lub ...
,
antispasmodic An antispasmodic (synonym: spasmolytic) is a pharmaceutical drug or other agent that suppresses muscle spasms. Smooth muscle spasm One type of antispasmodics is used for smooth muscle relaxation, especially in tubular organs of the gastrointestin ...
, and
diuretic A diuretic () is any substance that promotes diuresis, the increased production of urine. This includes forced diuresis. A diuretic tablet is sometimes colloquially called a water tablet. There are several categories of diuretics. All diuretics in ...
. In Romania the flowers are sometimes used to produce a sweet and perfumed jam. This means manual harvesting of flowers, eliminating the seeds and boiling the petals with sugar, in certain proportions, to obtain a light sweet and delicate perfume jam. Although the bark and leaves are toxic, various reports suggest that the seeds and the young pods of the black locust are edible. Shelled seeds are safe to harvest from summer through fall, and are edible both raw and boiled. Due to the small size of the seeds, shelling them efficiently can prove tedious and difficult. In France, Italy and Romania, ''R. pseudoacacia'' flowers are eaten as '' beignets'' after being coated in batter and fried in oil; they are also eaten in Japan, largely as tempura.


References


External links


Purdue University''Robinia pseudoacacia'' images at Forestry Images
* ttp://www.euforgen.org/species/robinia-pseudoacacia/ ''Robinia pseudoacacia''- information, genetic conservation units and related resources.
European Forest Genetic Resources Programme European Forest Genetic Resources Programme (EUFORGEN) is an international network that supports the conservation and sustainable use of forest genetic resources in Europe. The programme’s tasks include to coordinate and promote ''in situ'' an ...
(EUFORGEN)
" Coach " Tutoring Center 2018, ''Robinia pseudoacacia''
{{Authority control Robinieae Trees of the Southeastern United States Trees of Canada Garden plants of North America Ornamental trees Plants used in bonsai Medicinal plants Trees of the Northeastern United States Plants described in 1753 Taxa named by Carl Linnaeus Trees of the Great Lakes region (North America)