Honey locust
Encyclopedia
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
.
are pinnately compound on older trees but bipinnately compound on vigorous young trees. The leaflets are 1.5–2.5 cm (smaller on bipinnate leaves) and bright green. They turn yellow in the fall (autumn
). Leafs out relatively late in spring, but generally slightly earlier than the black locust
(Robinia pseudoacacia). The strongly scented cream-colored flower
s appear in late spring, in clusters emerging from the base of the leaf axils.
The fruit
of the Honey locust is a flat legume (pod) that matures in early autumn. The pods are generally between 15–20 cm. The pulp on the insides of the pods is edible, unlike the Black locust
, which is toxic. The seeds are dispersed by grazing herbivore
s such as cattle
and horse
s, which eat the pod pulp and excrete the seeds in droppings; the animal's digestive system assists in breaking down the hard seed coat, making germination easier.
Honey locusts commonly have thorns 3–10 cm long growing out of the branches, some reaching lengths over 20 cm; these may be single, or branched into several points, and commonly form dense clusters. The thorns are fairly soft and green when young, harden and turn red as they age, then fade to ash grey and turn brittle when mature. These thorns are thought to have evolved to protect the trees from browsing Pleistocene megafauna
which may also have been involved in seed dispersal. Thornless forms (Gleditsia triacanthos inermis) are occasionally found growing wild and are available as nursery plants.
plant. The name derives from the sweet taste of the legume pulp, which was used for food by Native American people, and can also be fermented to make beer
. The long pods, which eventually dry and ripen to brown or maroon, are surrounded in a tough, leathery skin that adheres very strongly to the pulp within. The pulp - bright green in unripe pods - is strongly sweet, crisp and succulent in unripe pods. Dark brown tannin-rich beans are found in slots within the pulp.
Its cultivar
s are popular ornamental plant
s, especially in the northern plains of North America where few other trees can survive and prosper. It tolerates urban conditions, compacted soil, road salt, alkaline soil, heat and drought. The popularity is in part due to the fact that it transplants so easily. The fast growth rate and tolerance of poor site conditions make it valued in areas where shade is wanted quickly, such as new parks or housing developments, and in disturbed and reclaimed environments, such as mine tailings. It is resistant to Gypsy moth
s but is defoliated by another pest, the mimosa webworm. Spider mite
s, canker
s, and gall
s are a problem with some trees. Many cultivated varieties do not have thorns.
Honey locusts produce a high quality, durable wood that polishes well, but the tree does not grow in sufficient numbers to support a bulk industry. Its also used for posts and rails since it takes a long time to rot
. However, a niche market exists for honey locust furniture. In the past, the hard thorns of the younger trees have been used as nail
s.
The honey locust is popular with permaculturalists
across the globe, for its multiple uses. The legumes make a valuable, high protein cattle fodder, which becomes more readily accessible with the thornless (inermis) variety. The broad shade of the tree canopy is of great value for livestock in hotter climates, such as Australia. It is also claimed to be a nitrogen fixer
, by way of rhizobium
, which benefits the surrounding soil and plants. The durability and quality of the timber, as well as the ability to produce its own nails, fits the paradigm of self-sustaining agriculture that requires fewer external inputs/resources.
The ability of Gleditsia to fix nitrogen is disputed. Many scientific sources clearly state that Gleditsia does not fix nitrogen. Some support this statement with the fact that Gleditsia does not form root nodules with symbiotic bacteria, the assumption being that without nodulation, no N-fixation can occur. In contrast, many popular sources, permaculture publications in particular, claim that Gleditsia does fix nitrogen but by some other mechanism.
There are anatomical, ecological and taxonomic indications to counter the assumption that only nodulating legumes fix nitrogen. Many non-nodulating species are as capable as nodulating species of growing well in nitrogen-limited soils and in some cases grow better. Also their leaf litter and seeds are higher in nitrogen than non-legumes [McKey, 1994; Waterman 1994] and sometimes higher even than nodulating legumes growing on the same site. How this happens is not yet well understood, but current research has recorded by-products of nitrogenase
activity in non-nodulating leguminous plants including Gleditsia triacanthos. Also, electron microscopy indicates the presence of clusters around the inner cortex of roots, just outside the xylem, that resemble colonies of rhizobial bacterioids. These may well constitute the evolutionary precursors in legumes for nitrogen fixation through nodulation.
It is not known whether the kind of N-fixation implied by these discoveries benefits other plants in the vicinity, as is known to be the case with nodulating legumes. Gleditsia coppices readily, and it seems reasonable to assume that reduction in root mass in response to coppicing should liberate nutrients in the sloughed off roots into the soil, to the benefit of neighbouring plants.
Seeds of Gleditsia triacanthos contain a trypsin inhibitor
Deciduous
Deciduous means "falling off at maturity" or "tending to fall off", and is typically used in reference to trees or shrubs that lose their leaves seasonally, and to the shedding of other plant structures such as petals after flowering or fruit when ripe...
tree
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...
native to central North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
. It is mostly found in the moist soil of river valleys ranging from southeastern South Dakota
South Dakota
South Dakota is a state located in the Midwestern region of the United States. It is named after the Lakota and Dakota Sioux American Indian tribes. Once a part of Dakota Territory, South Dakota became a state on November 2, 1889. The state has an area of and an estimated population of just over...
to New Orleans and central Texas
Texas
Texas is the second largest U.S. state by both area and population, and the largest state by area in the contiguous United States.The name, based on the Caddo word "Tejas" meaning "friends" or "allies", was applied by the Spanish to the Caddo themselves and to the region of their settlement in...
, and as far east as eastern Massachusetts
Massachusetts
The Commonwealth of Massachusetts is a state in the New England region of the northeastern United States of America. It is bordered by Rhode Island and Connecticut to the south, New York to the west, and Vermont and New Hampshire to the north; at its east lies the Atlantic Ocean. As of the 2010...
.
Description
Honey locusts, Gleditsia triacanthos, can reach a height of 20–30 m (66–100 ft), with fast growth, and are relatively short-lived; their life spans are typically about 120 years, though some live up to 150 years. They are prone to losing large branches in windstorms. The leavesLeaf
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 pinnately compound on older trees but bipinnately compound on vigorous young trees. The leaflets are 1.5–2.5 cm (smaller on bipinnate leaves) and bright green. They turn yellow in the fall (autumn
Autumn
Autumn is one of the four temperate seasons. Autumn marks the transition from summer into winter usually in September or March when the arrival of night becomes noticeably earlier....
). Leafs out relatively late in spring, but generally slightly earlier than the black locust
Black locust
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...
(Robinia pseudoacacia). The strongly scented cream-colored 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 appear in late spring, in clusters emerging from the base of the leaf axils.
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,...
of the Honey locust is a flat legume (pod) that matures in early autumn. The pods are generally between 15–20 cm. The pulp on the insides of the pods is edible, unlike the Black locust
Black locust
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...
, which is toxic. The seeds are dispersed by grazing herbivore
Herbivore
Herbivores are organisms that are anatomically and physiologically adapted to eat plant-based foods. Herbivory is a form of consumption in which an organism principally eats autotrophs such as plants, algae and photosynthesizing bacteria. More generally, organisms that feed on autotrophs in...
s such as cattle
Cattle
Cattle are the most common type of large domesticated ungulates. They are a prominent modern member of the subfamily Bovinae, are the most widespread species of the genus Bos, and are most commonly classified collectively as Bos primigenius...
and horse
Horse
The horse is one of two extant subspecies of Equus ferus, or the wild horse. It is a single-hooved mammal belonging to the taxonomic family Equidae. The horse has evolved over the past 45 to 55 million years from a small multi-toed creature into the large, single-toed animal of today...
s, which eat the pod pulp and excrete the seeds in droppings; the animal's digestive system assists in breaking down the hard seed coat, making germination easier.
Honey locusts commonly have thorns 3–10 cm long growing out of the branches, some reaching lengths over 20 cm; these may be single, or branched into several points, and commonly form dense clusters. The thorns are fairly soft and green when young, harden and turn red as they age, then fade to ash grey and turn brittle when mature. These thorns are thought to have evolved to protect the trees from browsing Pleistocene megafauna
Pleistocene megafauna
Pleistocene megafauna is the set of species of large animals — mammals, birds and reptiles — that lived on Earth during the Pleistocene epoch and became extinct in a Quaternary extinction event. These species appear to have died off as humans expanded out of Africa and southern Asia,...
which may also have been involved in seed dispersal. Thornless forms (Gleditsia triacanthos inermis) are occasionally found growing wild and are available as nursery plants.
Uses
Despite its name, the honey locust is not a significant honeyHoney
Honey is a sweet food made by bees using nectar from flowers. The variety produced by honey bees is the one most commonly referred to and is the type of honey collected by beekeepers and consumed by humans...
plant. The name derives from the sweet taste of the legume pulp, which was used for food by Native American people, and can also be fermented to make beer
Beer
Beer is the world's most widely consumed andprobably oldest alcoholic beverage; it is the third most popular drink overall, after water and tea. It is produced by the brewing and fermentation of sugars, mainly derived from malted cereal grains, most commonly malted barley and malted wheat...
. The long pods, which eventually dry and ripen to brown or maroon, are surrounded in a tough, leathery skin that adheres very strongly to the pulp within. The pulp - bright green in unripe pods - is strongly sweet, crisp and succulent in unripe pods. Dark brown tannin-rich beans are found in slots within the pulp.
Its cultivar
Cultivar
A cultivar'Cultivar has two meanings as explained under Formal definition. When used in reference to a taxon, the word does not apply to an individual plant but to all those plants sharing the unique characteristics that define the cultivar. is a plant or group of plants selected for desirable...
s are popular ornamental plant
Ornamental plant
Ornamental plants are plants that are grown for decorative purposes in gardens and landscape design projects, as house plants, for cut flowers and specimen display...
s, especially in the northern plains of North America where few other trees can survive and prosper. It tolerates urban conditions, compacted soil, road salt, alkaline soil, heat and drought. The popularity is in part due to the fact that it transplants so easily. The fast growth rate and tolerance of poor site conditions make it valued in areas where shade is wanted quickly, such as new parks or housing developments, and in disturbed and reclaimed environments, such as mine tailings. It is resistant to Gypsy moth
Gypsy moth
The gypsy moth, Lymantria dispar, is a moth in the family Lymantriidae of Eurasian origin. Originally ranging from Europe to Asia, it was introduced to North America in the late 1860s and has been expanding its range ever since...
s but is defoliated by another pest, the mimosa webworm. Spider mite
Spider mite
Spider mites are members of the Acari family Tetranychidae, which includes about 1,200 species. They generally live on the under sides of leaves of plants, where they may spin protective silk webs, and they can cause damage by puncturing the plant cells to feed...
s, canker
Canker
Canker and anthracnose are general terms for a large number of different plant diseases, characterised by broadly similar symptoms including the appearance of small areas of dead tissue, which grow slowly, often over a period of years. Some are of only minor consequence, but others are ultimately...
s, and gall
Gall
Galls or cecidia are outgrowths on the surface of lifeforms caused by invasion by other lifeforms, such as parasites or bacterial infection. Plant galls are abnormal outgrowths of plant tissues and can be caused by various parasites, from fungi and bacteria, to insects and mites...
s are a problem with some trees. Many cultivated varieties do not have thorns.
Honey locusts produce a high quality, durable wood that polishes well, but the tree does not grow in sufficient numbers to support a bulk industry. Its also used for posts and rails since it takes a long time to rot
Decomposition
Decomposition is the process by which organic material is broken down into simpler forms of matter. The process is essential for recycling the finite matter that occupies physical space in the biome. Bodies of living organisms begin to decompose shortly after death...
. However, a niche market exists for honey locust furniture. In the past, the hard thorns of the younger trees have been used as nail
Nail (engineering)
In woodworking and construction, a nail is a pin-shaped, sharp object of hard metal or alloy used as a fastener. Formerly wrought iron, today's nails are typically made of steel, often dipped or coated to prevent corrosion in harsh conditions or improve adhesion...
s.
The honey locust is popular with permaculturalists
Permaculture
Permaculture is an approach to designing human settlements and agricultural systems that is modeled on the relationships found in nature. It is based on the ecology of how things interrelate rather than on the strictly biological concerns that form the foundation of modern agriculture...
across the globe, for its multiple uses. The legumes make a valuable, high protein cattle fodder, which becomes more readily accessible with the thornless (inermis) variety. The broad shade of the tree canopy is of great value for livestock in hotter climates, such as Australia. It is also claimed to be a nitrogen fixer
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...
, by way of rhizobium
Rhizobium
Rhizobium is a genus of Gram-negative soil bacteria that fix nitrogen. Rhizobium forms an endosymbiotic nitrogen fixing association with roots of legumes and Parasponia....
, which benefits the surrounding soil and plants. The durability and quality of the timber, as well as the ability to produce its own nails, fits the paradigm of self-sustaining agriculture that requires fewer external inputs/resources.
The ability of Gleditsia to fix nitrogen is disputed. Many scientific sources clearly state that Gleditsia does not fix nitrogen. Some support this statement with the fact that Gleditsia does not form root nodules with symbiotic bacteria, the assumption being that without nodulation, no N-fixation can occur. In contrast, many popular sources, permaculture publications in particular, claim that Gleditsia does fix nitrogen but by some other mechanism.
There are anatomical, ecological and taxonomic indications to counter the assumption that only nodulating legumes fix nitrogen. Many non-nodulating species are as capable as nodulating species of growing well in nitrogen-limited soils and in some cases grow better. Also their leaf litter and seeds are higher in nitrogen than non-legumes [McKey, 1994; Waterman 1994] and sometimes higher even than nodulating legumes growing on the same site. How this happens is not yet well understood, but current research has recorded by-products of nitrogenase
Nitrogenase
Nitrogenases are enzymes used by some organisms to fix atmospheric nitrogen gas . It is the only known family of enzymes that accomplish this process. Dinitrogen is quite inert because of the strength of its N-N triple bond...
activity in non-nodulating leguminous plants including Gleditsia triacanthos. Also, electron microscopy indicates the presence of clusters around the inner cortex of roots, just outside the xylem, that resemble colonies of rhizobial bacterioids. These may well constitute the evolutionary precursors in legumes for nitrogen fixation through nodulation.
It is not known whether the kind of N-fixation implied by these discoveries benefits other plants in the vicinity, as is known to be the case with nodulating legumes. Gleditsia coppices readily, and it seems reasonable to assume that reduction in root mass in response to coppicing should liberate nutrients in the sloughed off roots into the soil, to the benefit of neighbouring plants.
Pharmacological activities
Extracts of Gleditsia posses important pharmacological activities in treating rheumatoid arthritis,as anti-mutagenic , anticancer and have significant cytotoxic activity against different cell linesSeeds of Gleditsia triacanthos contain a trypsin inhibitor
Trypsin inhibitor
Trypsin inhibitors are chemicals that reduce the availability of trypsin, an enzyme essential to nutrition of many animals, including humans.There are four commercial sources of trypsin inhibitors....