Robert M. Blair
Honeylocust (Gleditsia triacanthos), also called sweet-locust or thorny-locust, is a moderately fast growing tree commonly found on moist bottom lands or limestone soils. Because it has proven very hardy and tolerant of drought and salinity, it is widely planted for windbreaks and soil erosion control. The thornless variety has been planted to replace the elm in many urban areas. The wood is dense, hard, and durable but used only locally. Honeylocust pods are sweet and eaten by livestock and wildlife. The tree is relatively short lived, reaching the age of 125 years.
Derivation of specific name
General: Pea Family (Fabaceae). Native trees growing to 20 meters tall, with an open crown, armed with thick-branched thorns to 20 cm long on the main trunk and lower branches. Bark blackish to grayish-brown, with smooth, elongate, plate-like patches separated by furrows. Leaves are deciduous, alternate, pinnately or bipinnately compound, 10-20 cm long, often with 3-6 pairs of side branches; leaflets paired, oblong, 1-3 cm long, shiny and dark green above, turning a showy yellow in the fall, typically dropping early. Flowers are greenish-yellow, fragrant, small and numerous in hanging clusters 5-13 cm long, mostly either staminate (male) or pistillate (female), these usually borne on separate trees, but some perfect flowers (male plus female) on each tree (the species polygamo-dioecious). Fruits are flattened and strap-like pods 15-40 cm long and 2.5-3.5 cm wide, dark brown at maturity, pendulous and usually twisted or spiraled, with a sticky, sweet, and flavorful pulp separating the seeds; seeds beanlike, about 1 cm long. The common name "honey" is in reference to the sweet pulp of the fruits.
Variation within the species: Gleditsia triacanthos var. inermis (L.) Schneid. (“inermis” means unarmed) is occasionally found wild, apparently more as a populational variant than what is generally given formal taxonomic status as a variety. Such trees have provided stock for selection of some the thornless horticultural forms, but most of the latter are actually derived from buds or stem cuttings taken from the upper, thornless portions of physiologically mature trees thorny in the lower portions. Scions taken from this area generally remain thornless. Breeders also can control the sex of scions by selecting unisexual budwood for cuttings. Certain branches bear only one type of flower, and trees from cuttings of those branches will bear only that type.
Southern races of the species produce fruit more nutritious for stock feeding than northern races.
Natural hybridization between honey-locust and water-locust (Gleditsia aquatica) produces Gleditsia X texana Sarg., the Texas honey-locust.
Range and Habitat in Illinois
Regularity: Regularly occurring
Regularity: Regularly occurring
The natural range of honey-locust extends from central Pennsylvania
through extreme southern Ontario, extreme southern Michigan, southern
Wisconsin, and extreme southeastern Minnesota to extreme southeastern
South Dakota; south through eastern Nebraska to eastern Texas; east to
Alabama; and northeast along the western slopes of the Appalachians.
Isolated populations occur in northwestern Florida. Honey-locust is
naturalized east of the Appalachians as far north as Nova Scotia [16,27].
Regional Distribution in the Western United States
This species can be found in the following regions of the western United States (according to the Bureau of Land Management classification of Physiographic Regions of the western United States):
14 Great Plains
Occurrence in North America
KY LA OK MD MI MN MS MO NE NY
NC OH PA RI SC SD TN TX VA WI
WV NS ON
-The native range of honey locust.
Honeylocust, especially the thornless form, is widely cultivated as an ornamental and shade tree in all countries having a temperate climate.
Honey-locust is essentially Midwestern in distribution, from the west slope of Appalachians to the eastern edge of Great Plains -- scattered in the east-central US from central Pennsylvania westward to southeastern South Dakota, south to central and southeastern Texas, east to southern Alabama, then northeasterly through Alabama to western Maryland. Outlying populations occur in northwestern Florida, west Texas, and west central Oklahoma. It is naturalized east to the Appalachians from South Carolina north to Pennsylvania, New York, and New England and Nova Scotia; sometimes a weed tree in India, New Zealand, and South Africa. For current distribution, please consult the Plant Profile page for this species on the PLANTS Web site.
Honey-locust is a native, deciduous tree. Mature heights usually range
from 49 to 98 feet (15-30 m) [11,36], with a maximum height of 140 feet
(43 m) . In natural stands honey-locust averages 70 to 80 feet
(21-24 m) in height . Honey-locust is armed with heavy branched
thorns on the lower branches and trunk . The crown is plumelike and
open [14,42]. The bole is usually short and often divided near the
ground. The bark of mature trunks is usually 0.25 to 0.75 inches
(0.6-3.5 cm) thick with narrow ridges divided by fissures. The bark
peels in strips . The thick, fibrous roots are deep and
wide-spreading [14,39]. The tree is sturdy and windfirm . The
fruit is a legume 8 to 16 inches (15-40 cm) long and 1 to 1.4 inches
(2.5-3.5 cm) wide [8,11,22].
Honey-locust is usually described as rapid-growing [8,39]. Average
longevity for honey-locust is 125 years .
Unlike most leguminous species, honey-locust does not form Rhizobium
nodules on its roots, and does not fix nitrogen .
Catalog Number: US 396758
Collection: Smithsonian Institution, National Museum of Natural History, Department of Botany
Verification Degree: Original publication and alleged type specimen examined
Preparation: Pressed specimen
Collector(s): C. G. Pringle
Year Collected: 1902
Locality: Guadalajara., Jalisco, Mexico, North America
- Holotype: Standley, P. C. 1919. Contr. U.S. Natl. Herb. 20: 185.
Range and Habitat in Illinois
Honey-locust is adapted to a variety of soils and climates . It is
common in both bottomlands and uplands, in the open or in open woods
. Honey-locust occurs on well-drained sites, upland woodlands and
borders, old fields, fencerows, river floodplains, hammocks , rich,
moist bottomlands , and rocky hillsides . It is most commonly
found on moist, fertile soils near streams and lakes . Best growth
occurs in small stream valleys in southern Indiana and Illinois .
It has been rated highly tolerant to flooding . It is also
drought-resistant and somewhat tolerant of salinity [37,39].
Honey-locust tolerates both alkaline and acid soils, but its best growth
occurs on soils with pH between 6.0 and 8.0 . Honey-locust grew
better on low nitrogen sites than many other tree species .
The natural range of honey-locust is generally below 2,500 feet (760 m)
elevation, although the upper limit appears to be 5,000 feet (1,520 m).
A 20-year-old plantation of honey-locust had good survival at 6,900 feet
(2,100 m) in Colorado, but the trees were small [8,16].
Key Plant Community Associations
Honey-locust is usually only a minor component of natural forest stands.
It is considered an accessory species in four SAF cover types: bur oak
(Quercus macrocarpa), willow oak (Q. phellos)-water oak (Q.
nigra)-diamondleaf (laurel) oak (Q. laurifolia), sweetgum (Liquidambar
styraciflua)-willow oak, and sugarberry (Celtis laevigata)-American elm
(Ulmus americana). Honey-locust is a secondary species in all other SAF
cover types listed above [8,17].
Mesophytic species commonly associated with honey-locust include red
maple (Acer rubrum), persimmon (Diospyros virginiana), black tupelo
(Nyssa sylvatica), sweet pecan (Carya illinoensis), boxelder (Acer
negundo), Kentucky coffeetree (Gymnocladus dioica), and black walnut
(Juglans nigra) .
Habitat: Cover Types
This species is known to occur in association with the following cover types (as classified by the Society of American Foresters):
More info for the term: hardwood
27 Sugar maple
42 Bur oak
62 Silver maple - American elm
82 Loblolly pine - hardwood
88 Willow oak - water oak - diamondleaf oak
92 Sweetgum - willow oak
93 Sugarberry - American elm - green ash
94 Sycamore - sweetgum - American elm
Habitat: Plant Associations
This species is known to occur in association with the following plant community types (as classified by Küchler 1964):
K098 Northern floodplain forest
K100 Oak - hickory forest
K101 Elm - ash forest
K102 Beech - maple forest
K103 Mixed mesophytic forest
K104 Appalachian oak forest
K106 Northern hardwoods
K111 Oak - hickory - pine forest
K112 Southern mixed forest
K113 Southern floodplain forest
This species is known to occur in the following ecosystem types (as named by the U.S. Forest Service in their Forest and Range Ecosystem [FRES] Type classification):
FRES14 Oak - pine
FRES15 Oak - hickory
FRES16 Oak - gum - cypress
FRES17 Elm - ash - cottonwood
FRES18 Maple - beech - birch
Soils and Topography
On 20 drought-resistant species of seedlings tested, honeylocust ranked third in alkali tolerance (7). The species is also tolerant of acid soils (26), but best development is usually on soils having a pH between 6.0 and 8.0. From tests incorporating artificially salinized soils, young honeylocusts were found to be tolerant of soil salinity (13). Seed germination was little influenced by as much as 0.20 percent of sodium chloride in the dry weight of soil (2). Salt tolerance has particular economic importance in the North where runoff from highway de-icing salts can damage plantings, and also where plantings are desired on saline soils in and states. Whether honeylocust can tolerate the cumulative effects of salinity over a period of years is still unknown.
Typically, honeylocust is a bottom land species, most commonly found only on moist fertile soils near streams or lakes. Although it is not common anywhere in the Mississippi River Delta, it frequently grows on low clay ridges and flats in first bottoms and on the secondary flood plains along the Missouri River tributaries in Nebraska.
Over its range honeylocust grows naturally below a maximum elevation of 610 to 760 m (2,000 to 2,500 ft), although the general upper elevational. limit for the species is reported as 1520 m (5,000 ft). A 20year-old plantation growing at 2100 m (6,900 ft) in Colorado had "good" survival, but trees averaged only 2.4 m (8 ft) in height (7).
Honeylocust is tolerant of low temperatures and in the north it is hardy at -29° to -34° C (-20° to -30° F) (10). Northern races harden-off and become dormant relatively early, while growth of southern races continues later into the year. Southern races are subject to frost damage when planted in the north (7). Honeylocust also may suffer frost damage or dieback because of its indefinite or indeterminate annual growth pattern (4). Twigs may continue to elongate until stopped by cold, whereupon the tender terminal internodes are killed by the first frosts. New growth in the spring then comes from the lower lateral buds.
Adaptation: Honey-locust occurs on well-drained sites, upland woodlands and borders, rocky hillsides, old fields, fence rows, river floodplains, hammocks, and rich, moist bottomlands. It is most commonly found on moist, fertile soils near streams and lakes. It is tolerant of flooding and also is drought-resistant and somewhat tolerant of salinity. On bottomlands, it is a pioneer tree. On limestone uplands, it is an invader of rocky glades and abandoned farm fields and pastures. It is generally found below 760 meters, but up to 1500 meters in a few places. Flowering: May-June; fruiting: September-October, sometimes remaining on the tree through February.
General: Seed production begins on honey-locust trees at about 10 years and continues until about age 100, with optimum production at about 25-75 years of age. Some seed usually is produced every year but large crops usually occur every other year. The seeds are viable for long periods because of a thick, impermeable seed coat. Under natural conditions, individual seeds become permeable at different periods following maturation so that germination is spread over several years. The seeds are dispersed by birds and mammals, including cattle, which eat the fruits, and buffalo may have been historically important dispersal agents of the seeds. Germinability apparently is enhanced by passage through the digestive tract of animals. Honey-locust also reproduces from stump and root sprouts.
Honey-locust is generally shade-intolerant and reproduction is primarily in open areas, gaps, and at the edges of woods. The ability of honey-locust to invade prairie and rangeland is thought to be related to its tolerance of xeric conditions. Growth is rapid and trees live to a maximum of about 125 years.
Flower-Visiting Insects of Honey Locust in Illinois
(Bees suck nectar or collect pollen; flies suck nectar; observations are from Robertson)
Apidae (Apinae): Apis mellifera sn cp fq; Apidae (Bombini): Bombus griseocallis sn cp
Halictidae (Halictinae): Agapostemon sericea sn cp, Lasioglossum illinoensis sn, Lasioglossum imitatus sn; Andrenidae (Andreninae): Andrena dunningi sn, Andrena imitatrix imitatrix sn cp, Andrena personata sn
Syrphidae: Eristalis dimidiatus, Myolepta varipes, Toxomerus geminatus; Empididae: Rhamphomyia mutabilis; Anthomyiidae: Delia platura
Foodplant / gall
larva of Dasineura gleditschiae causes gall of live leaf of Gleditsia triacanthos
Foodplant / saprobe
fruitbody of Pholiota squarrosa is saprobic on relatively freshly cut, white rotted stump of Gleditsia triacanthos
Associated Forest Cover
Diseases and Parasites
Agrilus difficilis, a flatheaded borer, important west of the Mississippi River, burrows beneath the bark and may eventually girdle the trunk or large limbs (18). Several other bark and wood borers attack honeylocust, such as the widely distributed Xyleborus saxeseni.
A number of scale insects, such as the European fruit lecanium (Parthenolecanium corni), which is widespread and particularly damaging to shade trees, and the cottony maple scale (Pulvinaria innumerabilis), injure the bark of honeylocust, especially on small branches, lowering the vitality and growth rate of trees (18). Weakened trees become subject to attack and further damage by various species of boring insects and bark beetles.
The twig girdler, Oncideres cingulata, prunes small branches and can inflict severe injury on nursery seedlings. Heavy infestations can also severely damage large trees. The larvae of Amblycerus robiniae, a bruchid weevil, feed on honeylocust seed (1). The female periodical cicada (Magicicada septendecim) can damage honeylocust, especially young transplanted trees, by depositing eggs in the twigs.
Honeylocust is subject to few diseases, none of which interfere with its growth, except in isolated situations. The most noteworthy disease is the canker Thyronectria austro-americana, which can be fatal. Spiculosa cankers cause loss in merchantable wood volume or cull. Honeylocust is subject to several heart-rot and wood-decay fungi from species of Fomes and Polyporus.
Few leaf diseases attack honeylocust, and none mar the tree. The most widely distributed is tarry leaf spot caused by Linospora gleditsiae (9). In the seedling stage honeylocust is susceptible to cotton root rot (Phymatotrichum omnivorum), which is sometimes fatal (7). In shelterbelt planting tests in Oklahoma and Texas it was ranked as highly susceptible to certain Phymatotrichum root rots (27). Two other root diseases, Ganoderma lucidum and G. curtisii, can cause extensive root rot and tree fatality. The incidence of these root rots is not high.
In the southeast Texas area honeylocust was visibly damaged but not killed by air pollution, presumed to be mainly sulfur dioxide. In Illinois the species was ranked as highly resistant to ice damage and in Tennessee it was rated about average in resistance to flooding damage (9). It also appears to be resistant to salt spray when planted near the coast. Honeylocust is considered to be windfirm, but heavy limb breakage from wind was reported in Kansas. Because of its relatively thin bark it is easily damaged by fire (7). Rabbits sometimes inflict damage by gnawing the bark from young trees during the winter.
Plant Response to Fire
Honey-locust sprouts after top-kill by fire .
In the south-central Iowa study, there was an increase in the number of
honey-locust stems in the first season following the April prescribed
fire, but the number of honey-locust stems declined to prefire levels by
the second postfire year .
In Kansas, a bur oak-dominated gallery forest was prescribed burned in
1983. There was no apparent fire-caused mortality to the overstory.
The reproduction layer was dominated by elm seedlings, both before and
after the fire. Although honey-locust seedling mortality was not
reported directly, 100 honey-locust seedlings were present before the
fire, and 50 were recorded in each of the 2 years following the fire .
Immediate Effect of Fire
Honey-locust is easily injured by fire due to its thin bark [8,39].
In south-central Iowa, grassland dominated by Kentucky bluegrass (Poa
pratense) that was undergoing invasion by coralberry (Symphoricarpos
orbiculatus), honey-locust, and elms was prescribed burned with a series
of fires to observe the effect of fire season on brush control.
Prescribed fires were conducted in February, April, June, and September
in order to include all stages of plant phenology. Some large
honey-locust trees suffered bark damage and subsequent insect injury.
Many honey-locust trees under 10 feet (3 m) in height were top-killed
and sprouted the following year .
Honey-locust appears to be excluded from prairies by frequent fire, and
expands where fire is excluded. On bluestem (Andropogon spp. and/or
Schizachyrium spp.) prairie in Kansas, honey-locust was one of a number
of woody species invading undisturbed prairie that had not burned since
On the Konza Prairie, sites adjacent to gallery forests that had
remained unburned for 10 or more years were converting to woodlands
dominated by junipers (Juniperus spp.), elms (Ulmus spp.), honey-locust,
and hackberries (Celtis spp.). In areas farther from gallery forests,
fire exclusion leads to increased density of species, including
honey-locust, that otherwise persist only at low densities along stream
margins of frequently burned prairies .
Honey-locust also occurs in bottomland forests that experience fire
infrequently. Fire may create openings for honey-locust reproduction in
More info for the terms: density, hardwood, presence, tree, xeric
Facultative Seral Species
Honey-locust is intolerant of shade. Reproduction establishes only in
open areas, gaps, and at the edges of woods . The ability of
honey-locust to invade open prairie is thought to be related to its
tolerance of xeric conditions . Both top and root growth are
retarded by shade. Lower limbs die back in excessive shade.
Honey-locust is a fast-growing member of early seral stands . Hupp
 classes honey-locust as an upland disturbance species which is
sometimes found on the most severely degraded stream channels (streams
disturbed by stream channelization projects). The presence of
honey-locust and similar species suggests that these streambanks are now
so high as to be above most fluvial activity, and that these sites are
highly disturbed . Honey-locust is also described as a
mid-successional species  and is found in gaps or on the edges of
old-growth forests . The distribution of honey-locust appears to be
related to the serendipitous combination of openings (disturbance) and
In southeastern Iowa, honey-locust was one of the major dominants in
pioneer forests that developed on abandoned fields and pastures .
Honey-locust is also a pioneer in the rocky limestone glades of
Tennessee and Kentucky that are later populated by eastern redcedar
(Juniperus virginiana) . In Mississippi, honey-locust was a
volunteer on an 11-year-old hardwood stand planted to Nuttall oak
(Quercus nuttallii). At 20 feet (8.8 m), it was the tallest tree in the
stand. It is likely that honey-locust will eventually be overtopped and
shaded out by other species as the stand matures . In Tennessee,
honey-locust was present on a 12-year-old site (oldfield succession),
but not on 3-, 28-, 30-, 40-, and 45-year-old sites .
In southeastern Texas, honey-locust was present at very low density on a
47-year-old gravel pit, but was not present in 3- and 5-year-old pits or
in adjacent undisturbed forest . In southwestern Ohio, honey-locust
was common in 50-year-old forests (on old fields), and present but not
common in 90-year-old and old-growth (over 200 years old) forests
[41,41]. In Ohio, honey-locust was an occasional member of the canopy
of 40- and 60-year-old oak (Quercus spp.)-sugar maple (Acer saccharum)
In central Indiana, honey-locust was present in edge plots but not
interior plots in an old-growth forest . In Kansas, honey-locust
grew in patches on the edges of Konza Prairie gallery forests, reaching
heights of up to 20 feet (6 m); under the canopy it was rarely over 6 to
8 feet (1.8-2.4 m) tall . Large honey-locust trees were present in
a mature shingle oak (Quercus imbricaria)- bur oak community in Kansas,
suggesting that they were relics of an earlier successional stage.
There was no honey-locust in the reproduction layer .
The mimimum seed-bearing age of honey-locust is 10 years. Optimum seed
production occurs from about 25 to 75 years of age. Seeds are produced
until about age 100. Large crops usually occur every other year but can
be produced annually. Some seed is usually produced every year.
Honey-locust seed is viable for long periods due to an impermeable
seedcoat. Seeds are dispersed by birds and mammals, including cattle.
Germination of honey-locust seeds is apparently enhanced by passage
through the digestive tract of animals. Germination is artificially
enhanced by scarification (both hot water and acid treatments are
effective) . Honey-locust seeds showed the broadest germination
response of five species tested (honey-locust, white ash [Fraxinus
americana], sycamore [Platanus occidentalis], red mulberry [Morus
rubra], and black cherry [Prunus serotina]). Honey-locust showed a high
rate of emergence under all temperatures tested, and under all but the
driest conditions. It was also the only species of the five that had a
higher proportion of variance in germination rate explained by moisture
than by temperature .
Honey-locust seedlings grew faster on clay soils than on loess and
alluvium. There was no growth difference between sun and shade on clay
soils, but on the other two soil types honey-locust seedlings exhibited
retarded growth in the shade. Seedling root depths were 5 to 5.25 feet
(1.5-1.6 m) on clay and 20 to 24 inches (50.8-61 cm) in moist alluvial
Honey-locust can be propagated by grafting, budding, and cuttings
(hardwood, softwood, and root cuttings) .
Growth Form (according to Raunkiær Life-form classification)
Reaction to Competition
sides, and the dead limbs often are retained for some time.
Honeylocust is occasionally a pioneer on midwest strip-mine spoil banks. It is also a pioneer in rocky limestone glades of Tennessee and Kentucky, where it is often succeeded by eastern redcedar (Juniperus uirginiana). In northern Ohio, honeylocust was found with shellbark hickory (Carya laciniosa) and bur oak (Quercus macrocarpa) in the elm-ash-soft maple association on areas that formerly were swampy (7).
Life History and Behavior
More info for the term: tree
Honey-locust begins to flower when its leaves are nearly full grown,
from around May 10 in the southern parts of its range to around June 25
in the northern parts of its range [8,42]. The legumes ripen from
September to October, usually falling after ripening but sometimes
remaining on the tree through February [8,16,39,42].
Honeylocust thorn production usually diminishes gradually and finally ceases in the upper and outer crown growth as the tree ages. Thorns may still be produced on the lower trunk and on lower-trunk and limb sprouts. Typical trees, 10 years old or more, show a definite thornless region in the upper and outer shoot growth. When hardwood cuttings for propagation are taken from this thornless area, the scions generally remain thornless (6). Tree breeders can control the sex of scions from honeylocust by selecting unisexual budwood when taking cuttings. Certain branches bear only one type of flower, and trees from cuttings from those branches will bear only that type (14).
Honeylocust seedlings show a growth pattern characteristic of deciduous hardwoods with sympodial. growth. Persistent terminal buds are not formed and the shoot tip often dies and falls off (5).
Nursery-grown seedlings from pretreated seeds attain suitable size-30 cm (12 in) or more in height-for field planting in 1 year (3). In southern Michigan, first-year seedlings grown in pots reached a height of 37 cm (14.6 in) by September 21, just before leaf abscission (5). The average root-to-shoot ratio was 2 to 3. Stem growth was slow in the spring but rapid in early summer and fall. Only 60 percent of the height growth was attained by mid-July. In an additional study in southern Michigan, nursery seedlings grown 3 years in pots and nearly two growing seasons outplanted in the field averaged 22 mm (0.9 in) in trunk diameter (16) by early autumn. The following year trunk diameter increased 4 min (0.15 in).
Dormant nursery-grown seedlings can be stored, barerooted, at about 0° C (32° F) for several weeks before outplanting with no appreciable loss in survival rate (15).
Seed Production and Dissemination
Honeylocust seeds, like those of many leguminous species, have impermeable coats and thus remain viable for long periods of time. Under natural conditions, individual seeds become permeable at different periods following maturation so that any one crop is capable of producing seedlings over a period of several years.
The seeding range or natural dispersal of honeylocust seeds is not extensive. The pods, however, are readily eaten by cattle, whereby seeds are scattered in the feces. Undoubtedly seeds are also disseminated by birds and other mammals that feed on the fruit. Cleaned seeds average about 6,170/kg (2,800/lb), with a commercial purity of 95 percent and a soundness of 98 percent (24). Viability can be retained for several years when seeds are stored in sealed containers at 0° to 7° C (32° to 45° F) (3).
Flowering and Fruiting
The species is polygamo-dioecious; flowers are home in axillary, dense, green racemes (24). Racemes of staminate flowers are 5 to 13 em (2 to 5 in) long, pubescent, and often clustered. The calyx is campanulate, with five elliptic-lanceolate lobes; there are four to five petals, erect, oval, and longer than the calyx lobes; and up to 10 stamens, inserted on the calyx tube. The pistil is rudimentary or absent in the staminate flowers. Pistillate racemes are 5 to 8 ern (2 to 3 in) long, slender, with few flowers, and usually solitary. The pistils are tomentose, the ovary nearly sessile, and the style short; there may be two ovules or many. The stamens are much smaller and abortive in pistillate flowers.
Seeds, borne in long (15 to 41 cm, 6 to 16in), flat, indehiscent, and often twisted pods, ripen about mid-September in the southern portion of the range and around mid-October in the north. Soon after fruits mature they begin falling and dissemination often continues into late winter.
Growth and Yield
The average height growth of honeylocust planted in shelterbelts from North Dakota to Texas was 49 cm (19.2 in) per year during the first 7 years (7). This was a slower height growth than for plains cottonwood (Populus deltoides var. occidentalis) and Siberian elm (Ulmus pumila) but faster than that of American elm (U. americana), green ash (Fraxinus pennsylvanica), or hackberry (Celtis laevigata), all of which were frequently planted on the same shelterbelt projects. Under favorable conditions the annual diameter growth of young honeylocust is from 8 to 13 mm (0.33 to 0.50 in) (22). The species is an excellent tree for windbreaks.
Molecular Biology and Genetics
A number of horticultural forms have been developed and are widely cultivated, especially for shade and as ornamentals (24). Thornless honeylocust (Gleditsia triacanthos var. inermis Willd.) is thornless, or nearly so, and slender in habit; bushy honeylocust (G. triacanthos var. elegantissima [Grosdemangel Rehd.) is unarmed and densely bushy; Bujot honeylocust (G. triacanthos var. bujotii [Neuml Rehd.) has slender pendulous branches and narrow leaflets; and dwarf honeylocust (G. triacanthos var. nana [Loud.] A. Henry) is a small compact shrub or tree. Selected cultivars of the thornless forms have been patented. About 60 percent of the seedlings grown from thornless honeylocust seed are thornless (7).
Gleditsia x texana Sarg., the Texas honeylocust, is considered to be a hybrid of G. aquatica Marsh. and G. triacanthos L. (24). Its range is largely restricted to the Brazos River bottoms in Texas, with additional trees found along the Red River in Louisiana and occasionally along the Mississippi River in Indiana and Mississippi.
Barcode data: Gleditsia triacanthos
Statistics of barcoding coverage: Gleditsia triacanthos
Public Records: 4
Specimens with Barcodes: 17
Species With Barcodes: 1
National NatureServe Conservation Status
Rounded National Status Rank: N2 - Imperiled
Rounded National Status Rank: N5 - Secure
NatureServe Conservation Status
Rounded Global Status Rank: G5 - Secure
Please consult the PLANTS Web site and your State Department of Natural Resources for this plant’s current status, such as, state noxious status and wetland indicator values.
to release .
In some areas honey-locust invades rangelands. Honey-locust is
susceptible to triclopyr and to a mixture of picloram and 2,4,-D .
Honey-locust is not usually subject to serious insect and disease
problems; however, with the increase in plantations of honey-locust,
there has been a concomitant increase in insect pests. Honey-locust is
host to a number of leaf feeders including spider mites, white marked
tussock moth, and honey-locust plant bug. The only serious disease of
honey-locust is a canker which is occasionally fatal .
Damage to young honey-locust is caused by rabbits gnawing the bark 
and by livestock and white-tailed deer browsing [8,36].
Cultivars, improved and selected materials (and area of origin)
Contact your local Natural Resources Conservation Service (formerly Soil Conservation Service) office for more information. Look in the phone book under ”United States Government.” The Natural Resources Conservation Service will be listed under the subheading “Department of Agriculture.” These plant materials are readily available from commercial sources.
The only serious disease of honey-locust is a canker, which is occasionally fatal, but trees in landscape plantings may be damaged by a number of pests and pathogens. Damage to young honey-locust also may be caused by rabbits gnawing the bark and by browsing of livestock and deer.
Honey-locust is easily injured by fire because of its thin bark, but it sprouts after top-kill by fire. It appears to be excluded from prairies by frequent fire. Infrequent fires may create openings for reproduction in bottomland forests. Honey-locust is not a nitrogen fixer.
Relevance to Humans and Ecosystems
Other uses and values
particularly on dry sites . Honey-locust is also widely used in
windbreaks and shelterbelts [8,36].
Honey-locust pods are being fermented for ethanol production in studies
to explore the feasibility of biomass fuels .
Honey-locust was one of a number of species planted to assess biomass
yield potential for short-rotation cropping. Honey-locust showed good
survival through the fourth annual harvest .
Honey-locust pods are edible .
Importance to Livestock and Wildlife
Honey-locust pods are eaten by cattle, goats, white-tailed deer,
Virginia opossum, eastern gray squirrel, fox squirrel, rabbits, quail
(including northern bobwhite), crows, and starling [8,11]. White-tailed
deer frequently strip and eat the soft bark of young trees in winter
; rabbits also consume honey-locust bark in winter . Livestock
and white-tailed deer consume young vegetative growth [8,36].
Honey-locust is a source of pollen and nectar for honey .
In Virginia, honey-locust and other species were planted for mast
production on the margins of plots cleared and revegetated for wildlife
. Honey-locust is planted into currently operating pastures and
hayfields to provide high-protein mast for livestock (a management
system termed browse agroforestry). Cattle do not digest the seeds and
thus do not derive full nutritional benefit from consuming whole pods,
but ground honey-locust pods do provide a high-protein feed for cattle.
Sheep do digest the seeds, and therefore obtain more of the available
protein when consuming whole pods. The open canopy of honey-locust
allows good growth of pasture grasses .
Value for rehabilitation of disturbed sites
is often planted for erosion control .
(as fed) and 9.3 percent protein .
Wood Products Value
shock-resistant, takes a high polish, and is durable in contact with
soil [11,14,16,22,42]. Honey-locust wood is used locally for posts,
pallets, crates, general construction, furniture, interior finish,
turnery, and firewood [8,36]. It is useful, but is too scarce to be of
economic importance .
Both the common honeylocust and its thornless varieties are planted for erosion control and for wind breaks; the thornless varieties are widely planted as shade and ornamental trees. In many urban areas thornless honeylocust has been planted as a replacement for the American elm (26).
The wood of honeylocust possesses many desirable qualities but is little used because of its scarcity (23).
The sapwood is generally wide and yellowish in contrast to the reddish-brown heartwood, providing an attractive grain. The wood is dense, very heavy, very hard, strong in bending, stiff, resistant to shock, and is durable when in contact with soil. It is used locally for fence posts, and also as lumber for pallets, crating, and general construction.
Honey-locust is widely planted as a hardy and fast-growing ornamental. It is often used in extreme urban stress areas such as parking lot islands and sidewalk tree squares and has been planted for erosion control, for windbreaks and shelterbelts, and as a vegetation pioneer for rehabilitation of strip-mine spoil banks. Because of the small leaflets and open crown, the trees cast a light shade that permits shade-tolerant turfgrass and partial-shade perennials to grow underneath. Cultivars have been selected for crown shape and branch angles and leaf color, and most are both thornless and fruitless. Over-use of honey-locust in cities has led to recommendations that its use be discouraged until adequate biodiversity is restored.
Honey-locust wood is dense, hard, coarse-grained, strong, stiff, shock-resistant, takes a high polish, and is durable in contact with soil. It has been used locally for pallets, crates, general construction, furniture, interior finish, turnery, firewood, railroad ties, and posts (fence posts may sprout to form living fences), but it is too scarce to be of economic importance. The wood also was formerly valued for bows.
The geographic range of honey-locust probably was extended by Indians who dried the legumes, ground the dried pulp, and used it as a sweetener and thickener, although the pulp also is reported to be irritating to the throat and somewhat toxic. Fermenting the pulp can make a potable or energy alcohol. Native Americans sometimes ate cooked seeds, they have also been roasted and used as a coffee substitute.
Honey-locust pods are eaten by cattle, goats, deer, opossum, squirrel, rabbits, quail, crows, and starling. White-tailed deer and rabbits eat the soft bark of young trees in winter, and livestock and deer eat young vegetative growth. Honey-locust is planted around wildlife plots and into pastures and hayfields to provide high-protein mast. Cattle do not digest the seeds, but sheep do.
The honey locust, Gleditsia triacanthos, also known as the thorny locust, is a deciduous tree native to central North America where 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. The species has become a significant invasive weed in other regions of the world.
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 leaves 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 flowers 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 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 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, but the size and spacing of them is useless in defending against smaller extant herbivores such as deer. Thornless forms (Gleditsia triacanthos inermis) are occasionally found growing wild and are available as nursery plants. Hybridization of honey locust with water locust (G. aquatica) has been reported.
Its cultivars are popular ornamental plants, 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 moths but is defoliated by another pest, the mimosa webworm. Spider mites, cankers, and galls are a problem with some trees. Many cultivated varieties do not have thorns.
Despite its name, the honey locust is not a significant honey 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.
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 since it takes a long time to rot. In the past, the hard thorns of the younger trees were used as nails while the wood itself was used to fashion treenails for shipbuilding.
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. The spines cause damage to both people and domestic and native wildlife and puncture vehicle tyres. 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 deem honey locust as a nuisance weed; its fast growth allows it to out-compete grasses and other crops.
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 indicate 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 contains higher nitrogen 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 has been some observations of nitrogenase 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, does benefit neighboring plants as is said to be the case with nodulating legumes.
The tree has been used in traditional Native American medicine. Extracts of Gleditsia possess important pharmacological activities in treating rheumatoid arthritis, as anti-mutagenic, anticancer and have significant cytotoxic activity against different cell lines. Seeds of Gleditsia triacanthos contain a trypsin inhibitor.
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Names and Taxonomy
Comments: Native in eastern North America; planted and occasionally escaped elsewhere.
honey shucks locust
sweet bean locust
triacanthos L. (Cesalpiniaceae) [11,14,16,27,42]. Thornless
honey-locust (G. t. forma inermis Schneid.) is occasionally found wild
Natural hybridization between honey-locust and water-locust (G.
aquatica) has been reported .
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