The honey locust (''Gleditsia triacanthos''), also known as the thorny locust or thorny honeylocust, is a
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, ...
tree
In botany, a tree is a perennial plant with an elongated stem, or trunk, usually supporting branches and leaves. In some usages, the definition of a tree may be narrower, including only woody plants with secondary growth, plants that are ...
in the family Fabaceae, native to central
North America where it is mostly found in the moist soil of river valleys.
Honey locust is highly adaptable to different environments, has been introduced worldwide, and can be an aggressive,
invasive species outside of its native range.
[
]
Description
The honey locust, ''Gleditsia triacanthos'', can reach a height of . They exhibit fast growth, but live a medium life span of about 120 years. The leaves are pinnate
Pinnation (also called pennation) is the arrangement of feather-like or multi-divided features arising from both sides of a common axis. Pinnation occurs in biological morphology, in crystals, such as some forms of ice or metal crystals, and in ...
ly 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 ...
on older trees but bipinnate
The following is a list of terms which are used to describe leaf morphology in the description and taxonomy of plants. Leaves may be simple (a single leaf blade or lamina) or compound (with several leaflets). The edge of the leaf may be regular o ...
ly compound on vigorous young trees.[ The leaflets are (smaller on bipinnate leaves) and bright green. They turn yellow in the autumn. Honey locusts leaf out relatively late in spring, but generally slightly earlier than the ]black locust
''Robinia pseudoacacia'', commonly known in its native territory as black locust, is a medium-sized hardwood deciduous tree, belonging to the tribe Robinieae of the legume family Fabaceae. It is endemic to a few small areas of the United States ...
(''Robinia pseudoacacia
''Robinia pseudoacacia'', commonly known in its native territory as black locust, is a medium-sized hardwood deciduous tree, belonging to the tribe Robinieae of the legume family Fabaceae. It is endemic to a few small areas of the United States, ...
''). The strongly scented, cream-colored flowers appear in late spring, in clusters emerging from the base of the leaf axil
A leaf ( : leaves) is any of the principal appendages of a vascular plant stem, usually borne laterally aboveground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", while the leaves, ste ...
s. The trees are polygamodioecious
Plant reproductive morphology is the study of the physical form and structure (the morphology) of those parts of plants directly or indirectly concerned with sexual reproduction.
Among all living organisms, flowers, which are the reproductive st ...
: most are strictly dioecious with male and female flowers on separate trees though some have bisexual flowers with a few male or female flowers on the same tree.
The fruit of the honey locust is a flat legume (pod) that matures in early autumn.[ The pods are generally between . The seeds are dispersed by grazing herbivores such as cattle and horses, 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. In addition, the seeds are released in the host's manure, providing fertilizer for them. Honey locust seed pods ripen in late spring and germinate rapidly when temperatures are warm enough.
Honey locusts commonly have ]thorns
Thorn(s) or The Thorn(s) may refer to:
Botany
* Thorns, spines, and prickles, sharp structures on plants
* ''Crataegus monogyna'', or common hawthorn, a plant species
Comics and literature
* Rose and Thorn, the two personalities of two DC Com ...
long growing out of the branches, some reaching lengths over ; 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 is the set of large animals that lived on Earth during the Pleistocene epoch. Pleistocene megafauna became extinct during the Quaternary extinction event resulting in substantial changes to ecosystems globally. The role of ...
, which may also have been involved in seed dispersal, but the size and spacing of them is less useful in defending against smaller extant herbivores such as deer. Thornless forms (''Gleditsia triacanthos'' var. ''inermis'') are occasionally found growing wild and are available as nursery plants.[ Hybridization of honey locust with ]water locust
''Gleditsia aquatica'', commonly called water locust or swamp locust after its habitat of river swamps and slough margins, is a tree native to the Southeastern United States and adjacent regions.
Description
''Gleditsia aquatica'' often grows 50 ...
(''G. aquatica'') has been reported.
File:HoneyLocustThorn.JPG, Detail of thorns
File:Honey Locust Tree Thorns in Kansas.jpg, Honey locust tree thorns in Kansas
File:Gleditsia triacanthos Flower HW1.jpg, Detail of flowers
File:2014-10-11 12 49 16 Honey Locust foliage during autumn in Elko, Nevada.JPG, Autumn leaf color
File:Honeylocust fruits.jpg, Mature honeylocust fruits
File:Old growth honeylocust tree.jpg, Old growth honeylocust tree in Tennessee, US, 1941
Cultivation and history
Its cultivar
A cultivar is a type of cultivated plant that people have selected for desired traits and when propagated retain those traits. Methods used to propagate cultivars include: division, root and stem cuttings, offsets, grafting, tissue culture ...
s are popular ornamental plant
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 ...
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. Cultivars with narrow upright growth habit, such as ''Northern Sentinel,'' are especially prized as street trees. It is resistant to spongy moth
''Lymantria dispar'', also known as the gypsy moth or the spongy moth, is a species of moth in the family Erebidae. ''Lymantria dispar'' is subdivided into several subspecies, with subspecies such as ''L. d. dispar'' and ''L. d. japonica'' bei ...
s but is defoliated by another pest, the mimosa webworm
''Homadaula anisocentra'', also known as the mimosa webworm, is a species of moth in the family Galacticidae. It is considered a pest of ornamental plants. They attack the leaves of mimosa ('' Albizia julibrissin'') and honeylocust (''Gleditsia t ...
. Spider mites, cankers, and galls are a problem with some trees. Many cultivated varieties do not have thorns.
Agriculture
The species is a major invasive environmental and economic weed in agricultural regions of Australia. The plant forms thickets and destroys the pasture required for livestock to survive. The thickets choke waterways and prevent both domestic and native animals from drinking and also harbour vermin
Vermin ( colloquially varmint(s) or varmit(s)) are pests or nuisance animals that spread diseases or destroy crops or livestock. Since the term is defined in relation to human activities, which species are included vary by region and enterp ...
. The spines cause damage to both people and domestic and native wildlife and puncture vehicle tires. In much of the Midwest of the United States the honey locust is also considered a weed tree and a pest that establishes itself in farm fields. In other regions of the world, ranchers and farmers who employ monocropping In agriculture, monocropping is the practice of growing a single crop year after year on the same land. Maize, soybeans, and wheat are three common crops often monocropped. Monocropping is also referred to as continuous cropping, as in "continuous ...
deem honey locust a nuisance weed; its fast growth allows it to out-compete grasses and other crops.
Uses
Food
The pulp on the inside of the pods is edible[ (unlike the ]black locust
''Robinia pseudoacacia'', commonly known in its native territory as black locust, is a medium-sized hardwood deciduous tree, belonging to the tribe Robinieae of the legume family Fabaceae. It is endemic to a few small areas of the United States ...
, which is toxic) and consumed by wildlife and livestock.
Despite its name, the honey locust is not a significant honey
Honey is a sweet and viscous substance made by several bees, the best-known of which are honey bees. Honey is made and stored to nourish bee colonies. Bees produce honey by gathering and then refining the sugary secretions of plants (primar ...
plant.[ The name derives from the sweet taste of the legume pulp, which was used for food and ]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 ...
by Native American people
Native Americans, also known as American Indians, First Americans, Indigenous Americans, and other terms, are the Indigenous peoples of the mainland United States (Indigenous peoples of Hawaii, Alaska and territories of the United States are ...
, and can also be used to make tea
Tea is an aromatic beverage prepared by pouring hot or boiling water over cured or fresh leaves of ''Camellia sinensis'', an evergreen shrub native to East Asia which probably originated in the borderlands of southwestern China and north ...
.[ The long pods, which eventually dry and ripen to brown or maroon, are surrounded in a tough, leathery skin that adheres strongly to the pulp within. The pulp—bright green in unripe pods—is strongly sweet, crisp and succulent in ripe pods. Dark brown tannin-rich beans are found in slots within the pulp. Likewise, its edible seed has nutritional potential, and the flour made from its ]cotyledon
A cotyledon (; ; ; , gen. (), ) is a significant part of the embryo within the seed of a plant, and is defined as "the embryonic leaf in seed-bearing plants, one or more of which are the first to appear from a germinating seed." The num ...
s constitutes a food source with various potential uses for pastry and bakery, among other gastronomic uses.
Timber
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. However, a niche market exists for honey locust furniture. It is also used for posts and rails because of the dense, rot-resistant nature of the wood. In the past, the hard thorns of the younger trees were used as nails and the wood itself was used to fashion treenail
A treenail, also trenail, trennel, or trunnel, is a wooden peg, pin, or dowel used to fasten pieces of wood together, especially in timber frames, covered bridges, wooden shipbuilding and boat building. It is driven into a hole bored through two ...
s for shipbuilding.
Nitrogen fixation
The ability of ''Gleditsia'' to fix nitrogen is disputed. Many scientific sources 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 nitrogen fixation can occur. In contrast, many popular sources, permaculture
Permaculture is an approach to land management and settlement design that adopts arrangements observed in flourishing natural ecosystems. It includes a set of design principles derived using whole-systems thinking. It applies these principle ...
publications in particular, claim that ''Gleditsia'' does fix nitrogen but by some other mechanism.
There are anatomical, ecological, and taxonomic indications of nitrogen fixation in non-nodulating legumes. Both nodulating and non-nodulating species have been observed to grow well in nitrogen-poor soil with non-nodulating legumes even dominating some sites. The litter and seeds of non-nodulating species contain levels of nitrogen higher than non-legumes and sometimes even higher than nodulating legumes growing on the same site. How this happens is not yet well understood but there have been some observations of nitrogenase
Nitrogenases are enzymes () that are produced by certain bacteria, such as cyanobacteria (blue-green bacteria) and rhizobacteria. These enzymes are responsible for the reduction of nitrogen (N2) to ammonia (NH3). Nitrogenases are the only fa ...
activity in non-nodulating leguminous plants, including honey locust. 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 non-nodulating nitrogen fixation, if it exists, benefits neighboring plants as is said to be the case with nodulating legumes.
Research
In research using databases, more than 60 phytochemicals were identified from honey locust, including polyphenol
Polyphenols () are a large family of naturally occurring organic compounds characterized by multiples of phenol units. They are abundant in plants and structurally diverse. Polyphenols include flavonoids, tannic acid, and ellagitannin, some o ...
s, triterpene
Triterpenes are a class of chemical compounds composed of three terpene units with the molecular formula C30H48; they may also be thought of as consisting of six isoprene units. Animals, plants and fungi all produce triterpenes, including squa ...
s, sterols, and saponins, with in vitro
''In vitro'' (meaning in glass, or ''in the glass'') studies are performed with microorganisms, cells, or biological molecules outside their normal biological context. Colloquially called " test-tube experiments", these studies in biology ...
studies assessing for possible biological activity.
References
Further reading
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*
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*
External links
*
''Gleditsia triacanthos'' images
at bioimages.vanderbilt.edu
''Gleditsia triacanthos'' images
at Forestry Images
''Gleditsia triacanthos''
at the USDA Plants Database
{{Taxonbar, from=Q157650
Edible legumes
Garden plants of North America
Gleditsia
Nearctic realm flora
Ornamental trees
Plants described in 1753
Plants used in Native American cuisine
Plants used in traditional Native American medicine
Trees of humid continental climate
Trees of Ontario
Trees of the Eastern United States
Trees of the North-Central United States
Trees of the Northeastern United States
Trees of the Plains-Midwest (United States)
Trees of the Southeastern United States
Trees of the United States