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If you've ever noticed a tree covered in clusters of 5" long spikes, and wondered "What is this tree that could kill me?" then you probably have found the Honey Locust. The huge thorns on this tree could easily pierce a shoe if stepped on, or cause serious injury in the event that a branch fell down. Numerous tractor tires have also fallen victim to the thorns of the honey locust! Well, if you want to learn a bit more about this tree and it's role in our native environment stick around. I've been bumping into these trees since I was a kid (and lived to tell about it), and can share all I've learned with you! In this article: What is Honey Locust What are the benefits of Honey Locust Identification / Characteristics How to grow and care for Honey Locust How to grow Honey Locust from seed What Wildlife, Pests, and Diseases effect Honey Locust Where to buy Honey Locust Uses of Honey Locust Final thoughts What is the Honey Locust tree? The Honey Locust is a short lived, medium sized deciduous hardwood tree native to Eastern North America. Scientifically known as Gleditsia triacanthos, it grows up to 100’ tall in full sun and well drained soil. An important tree for wildlife, bees and flies pollinate the flowers, insects feed on the tree, and birds & many mammals eat the seed pods. [1][2][3] In fact the common name ‘honey locust’ comes from the fact that inside it’s seed pods is a sweet substance that is honey-like. And this is what draws all the animals to consume them. Also, although this is a member of the legume family, it does not fix nitrogen to the soil.[3] Immature seed pods on a Honey Locust tree. Note they are starting to coil. The mature Honey Locust as a very distinct appearance in that it’s trunk and branches are often covered in clusters or isolated thorns that are huge! They physically resemble framing or 10-penny nails, being up to 8” long and ¼” diameter at the base, tapering to a sharp pointed tip. Although scary, there are thornless varieties available that are becoming quite popular as an ornamental landscape tree, and street tree. [3][5] Honey Locust has proven itself to be a tough customer in regards to being around humans, as it is noted for it’s resistance to pollution and salt. A young Honeylocust Tree growing along the edge of a farm field. Numerous species of wildlife use the Honey Locust tree. Bees pollinate the flowers in Spring, numerous insects feed on leaves and wood of the tree, and then in Autumn the seeds are eaten by birds, fox, deer, squirrels, and other mammals.[2][3] Note - the Honey Locust tree is very different from the Black Locust tree. To see the differences between these species, click here. Honey Locust and the mammoth It is thought that the Mammoth and Mastodon were fans of the Honey Locust.[6][7] The overly large seed pods are believed to have evolved to such a large size when the giant prehistoric megafauna roamed North America. And only the megafauna (mammoth and mastodon) could fit the entire fruit in it's mouth. But as we will see later in this article, the seeds need some form of scarification to penetrate the hard outer seed coat. And it just so happens that this can happen naturally by passing through the digestive tract of an animal. Native Range of Honey Locust The native range of the Honey Locust is North America. Primarily from Texas/Louisiana to Minnesota, and East to Pennsylvania/South Carolina. Even parts of Florida and Southern Ontario have significant populations. Native range of the Honey Locust tree. Sources [1][2] As the Honey Locust has proved popular as an ornamental, it has subsequently been sent around the world. Established populations exist outside of it's native range in New England and the Western United States. And internationally it is now invasive and noxious in New Zealand and Argentina.[8] The Honeylocust serves as a good reminder that local ecotypes should be considered when selecting a tree for planting. The northern range Honey Locusts have adapted to go dormant earlier when cold temperatures arise, while Southern Trees stay active. This can make a problem when a Southern specimen is grown up North. As the portion of the shoots past the last set of lateral buds will often suffer frost damage and die back, resulting in irregular growth for the following season. Honey Locust Reference Table Scientific NameGleditsia triacanthosCommon Name(s)Honey Locust, Honeylocust, Honey-shucks locust, Honey-locust, Thorny locust, sweet locustNative Range, USDA ZoneEastern North America, USDA Hardiness Zones 3-8Bloom TimeSpringHeight60-80' (20-27m)Spacing / Spread60-80' (20-27m)Light RequirementsFull sunSoil TypesSandy loam to clayMoistureMedium-moisture, well drainedFauna Associations / Larval HostsBees, butterflies. Hosts Silver Spotted Skipper.Sources [1][2][3][4] Pros and cons of Honey Locust Pros Beauty Grown in the open the Honeylocust has an open crown and shape that is stately. And the leaves look nice all year long. But the seedpods themselves make this tree incredibly interesting. Dark flat twisting pods that reach nearly 18” in length, dangling from a tree. They rattle once they’ve dried a bit, and contain a sweet ‘honey’-like substance. No raking leaves! The individual leaflets of the Honeylocust are quite small. When they fall in Autumn, they do not need to be raked as they will just blend in with the grass. Turf grass / lawn can grow under a Honey Locust Common suburban shade trees make thick canopies that can shade out most grasses. But the tiny leaflets of the Honey Locust will allow enough light through to let most grasses persist. Cons Thorns The thorns of wild Honey Locust make them undesirable if you need to go near them. These massive spikes could really hurt or injure someone! Note – there are thornless varieties of Honey Locust, and if you are considering landscaping with this tree, you should absolutely consider getting a thornless variety! Messy Although you may not need to rake leaves, the seed pods will still drop in Autumn. And these pods can be large – up to 14” and cork-screw shaped. If you don’t have enough wildlife around then you will need to clean them up each Winter, as they take a long time to all fall down. Dozens of Honeylocust seed pods hanging on a tree in winter. Identification and Characteristics of Honey Locust Growth rate of the Honey Locust tree Honey Locust trees grow relatively fast, growing 12-26” per year. They begin growing in height and elongating branches in Spring, and will continue until a hard frost. Seedlings often reach 12-15” in height in their first year. And trees planted in shelter belts from frigid North Dakota to Texas grew on average 19” per year during their first seven years. Trunks can grow 0.33-0.50” per year in optimum conditions. [2] Lifespan Honey Locust trees will live on average for 125 years.[3] They are fast growing trees reaching maturity in approximately 30-40 years, growing along the edge of prairies, forest edges, and meadows. Trunk Typically growing 50-100’ tall, the Honey Locust tree produces an open crown that is plume-like. A mature Honey Locust tree. Bark The bark of mature Honey Locust trees are light gray to black and arranged in irregular large flat plates separated by shallow furrows. [4] Young bark and bark of twigs is smooth and brown. First year growth of twigs will often be green. The above image is the bark of a thornless variety of Honeylocust Honey Locust Thorns The thorns are what make this tree famous, and for good reason. Clusters of thorns appear on mature trunks, and the thorns grow thorns themselves at 90 degree angles to the parent. On branches, one may encounter isolated thorns or clusters of thorns.[3] Individual thorns are typically 2-8” long, and ¼” diameter at the base, tapering to a sharp tip.[2][4] Note how long these thorns are! The thorns are If one were to accidentally step on a branch with upward facing thorns in the woods, they may face severe injury. Were you cutting down a tree, you would face much hazard, as these are serious thorns. Leaf The leaves of Honey Locust trees are alternate, compound, and usually bipinnate 6-14” long. There will be 5-11 pairs of simple leaflets. Individual leaflets are small, ¾”-1.5” long by ¼-1/2” wide and are lanceolate-oblong in shape, and the margins are crenate. [4] Leaves of Honey Locust Buds of Honeylocust trees are not visible until Spring when leaves and flowers begin to emerge. They share this characteristic with a few other shrubs such as Sumac.[9] Note - the leaves of Honey Locust, and their seedlings can both closely resemble Prickly Ash. Make sure you have a proper identification! Flower In late Spring, flowering begins with dense groups of green racemes. The male racemes of staminate flowers are usually 2-5” long (5-13 cm) and commonly clustered. Flowers have 4-5 petals that are elliptic-lanceolate in shape, and will have up to 10 stamens. Occasionally male flowers may have a rudimentary pistil. Female flowers are usually 2-3” long (5 to 8 cm), and will have fewer, and commonly isolated flowers. [3] Honeylocust flowers in Spring. Credit Andrew Butko, CC BY-SA 3.0 Honey Locust seed pods Honey Locust trees begin producing seed at roughly 10 years of age, with peak production occurring from roughly 25-100 years of age. Seed will be produced each year, with bumper crops every 2nd or 3rd year (typically). Examples of Honey Locust tree seed pods. I collected seeds from these to germinate them. Initially seed pods are green, but by Autumn they will change to a maroon or dark brown color. The pods usually range from 4-17” long (10 cm-45 cm).[3] Once the seeds mature, the pods will naturally fall from the trees. Although this can often last into Winter. Root The root system of the Honey Locust consists of a taproot, and deep, wide-spreading and frequent branching. Given space, taproots can reach 20’ deep (6m). But the root system will adapt to it’s environment. For example in clay soils it was found that 4-6 year old saplings had root systems that were twice as long as deeper, richer soils. This adaptable root system allows Honey Locust to grow on such a wide variety of conditions.[2] Grow and Care for Honey Locust Sunlight Requirements Honey Locust will prefer full sun, which is six hours of direct sunlight per day. But it can tolerate partial shade, which is four to six hours per day.[2][3] It is not shade tolerant. Honey Locust can only grow when enough overhead light is present. Trees that grow on forest edges, or in forest openings will have their shaded or lower limbs die or shed. This is a natural response to shade. If photosynthesis is not occurring on leaves from a limb, then why spend energy maintaining it? Soil Requirements For soil types, Honey Locust will grow well in many soil textures, from sandy loam, silt, to clay loam (as long as clay loam drains well). It is not tolerant of clay soil or rocky soils, nor if the soil layer is too thin.[2][3] Soil pH / chemistry Honey Locust is listed as being tolerant of both alkali soils and acidic. But it will grow best when the soil pH is between 6.0-8.0. [2] It is tolerant of salinity, as studies have found that 0.2% Na-Cl (sodium chloride) didn’t have an effect on germination or growth of young trees. And it seems to do very well on limestone soils, as I’ve personally observed many specimens growing seemingly everywhere in the drift-less region of the upper Midwest. Moisture Requirements For moisture, Honey Locust can grow in dry to moist soil. Growth will be best, and the tree will reach it’s maximum height in moist soils. But, the soil should be able to drain well. [3] Maintenance For maintenance, one may wish to collect seed pods when they fall in Autumn. But if you wait long enough, it is likely that deer, raccoon, opossum, and squirrel will consume or gather them for you. If you have the kind with thorns (most often encountered in the wild) then you may wish to carefully prune limbs to allow for walking paths or trails. Pruning of Honey Locust trees can be hazardous, as some of the spikes will inevitably become dislodged from the main branch and could be pointed upwards from the ground. These large spikes could cause serious injury. It have usually brought a rake when pruning, to help clear the ground of upright spikes after pruning. Fertilizer As a native tree, Honey Locust will not require supplemental fertilizer. How messy are Honey Locust trees? The Honey Locust tree can be considered fairly messy in that every Autumn you can expect numerous large seed pods to fall to the ground. Many of these pods will be taken by squirrels for winter food, but many will still remain and need to be cleaned up. Also, if limbs die back thorns will become brittle and can fall off. These are not just messy, but can be considered hazardous to step on. How to Grow Honey Locust from Seed Honey Loucst seed will have a hard outer shell that must be scarified in order to germinate. But there are no other special requirements (no cold stratification, for example).[3][11][12] Seed collection To grow Honey Locust from seed, we must first collect the pods from the ground in Fall or Winter after they have fallen. Leave the pods to dry for a couple days in a cool, dark, dry location. Then, simply go open the pods up by carefully cutting the ends and edges, and peeling apart the pod. The seeds will fall out naturally. A special note – if you are gathering seed from a thornless variety of Honeylocust, please know that it may produce the thorned type. It has been found that seed from thornless trees will produce trees that do grow thorns roughly 40% of the time. [10] Storing Honey Locust seed Honey Locust seed can be stored for several years if stored in a sealed container in the refrigerator. Seed that is not going to be stored for long term should be scarified and planted soon. Scarifying Honey Locust seed As Honey Locust is a member of the legume family, it’s seed will have a hard outer shell. Germination rates will be greatly enhanced when a scarification method is performed. In nature, this often happens by passing through the digestive tract of an animal. And it is thought that bison or prehistoric megafauna may have helped spread this tree far and wide by this scarification method.[3][6][7] (See here for more details on scarification) But you can use sandpaper to mechanically scarify the seed. To do so, gently rub the seed on 100-150 grit sandpaper until a portion of the outer shell is worn through. Soak the seed in room temperature water overnight to allow it to imbibe. You can also use hot water to scarify the seed. This can be done by placing some seed in a coffee cup. Then, bring a small amount of water to a boil (less than that of the coffee cup). Next, remove the water from the boil and wait 10-30 seconds for the water to slightly cool. Then, pour the water into the coffee cup containing the seeds. The seeds on the right have be scarified with hot water. The seeds on the left are from dried pods. Note how much larger they are from imbibing the water. Leave the water/seeds to sit overnight. In the morning, many of the seeds should be noticeably larger, meaning they have successfully imbibed the water. Planting Honey Locust seed To plant the seed, bury it approximately 3/8” deep (9 mm) in moist potting soil. Place it in a location that receives morning sun and afternoon shade. Keep it moist by watering in the mornings, and germination should occur within a couple weeks at soil temperatures above 70F. A Honey Locust tree seedlings shortly after germination. Establishment Once trees have 2-4 true leaves, they can be transplanted to their final location. Even though they have thorns, they should be protected from deer with a cage or tree shelter. A juvenile Honeylocust tree in a pot that could use some more drainage! I didn't plan on planting this tree in my yard, as I don't want the thorns! But those leaves are unmistakable. Propagating Honey Locust from cuttings New growth can be taken for cuttings in Fall or Spring. Simply cut below 3-4 nodes and place in moist sterile sand or sphagnum peat moss, in mostly shady environment. And interestingly, it has been demonstrated that when cuttings are taken from thornless regions of thorny trees, the resulting tree from the cutting is thornless. Wildlife, Pests, and Diseases associated with Honey Locust Pollinators The flowers of Honeylocust are pollinated by small bees and flies.[3] It also hosts several butterflies and moths such as the Silver Spotted Skipper. [13] Birds The seeds of Honey Locust are eaten by Bobwhite Quail, Crows, and Starlings. In addition to a food source, the trees are popular sites for birds to build nests. This is probably due to the difficulty in climbing. [3][14] Other mammals The sweet seed pods are readily consumed by Fox, deer, livestock (cattle & sheep), opossum, and squirrels. Deer and Rabbits Young branches that don’t have thorns present may be eaten by deer, as well as younger bark. Otherwise, the thorns keep deer away (as is their evolutionary intent). Rabbits however will chew the bark on young trees, causing damage. It is more a problem in harsh winters with lots of snowfall. This can be particularly frustrating as you won’t realize the problem has happened until Spring. Damaging insects A number of insects will attack Honey Locust trees, and while often not fatal, then can weaken it, or slow it’s growth. Many of these are native, but the ones that are noted as having a fatal effect on the tree should be treated as a threat if the tree is desired to live, such as in your yard. [2] Leaf feeders There are a number of leaf-feeding insects that can defoliate trees. The Mimosa webworm can often be seen and is quite damaging. A spider mite (Eotetranychus multidigituli), seems to occur in hot, dry weather. It can rapidly defoliate a tree.[2] Other insects that feed on the leaves include the whitemarked tussock moth (Orgyia leucostigma), Honey Locust plant bug (Diaphnocoris chlorionis), leaf hoppers, several pod galls, walkingsticks, loopers, bagworms, beetles….numerous types of defoliators.[2] Wood boring insects A flatheaded borer, Agrilus difficilis, will burrow under the bark and may girdle the trunk or large branches of the tree. A twig girdler, Oncideres cingulate, will damage and prune small branches. It is most damaging on young saplings. [2] And the cicada….they will bore holes into the small branches/twigs to lay their eggs. This action usually results in pruning of the tree branch. Scale Scale insects like the European fruit lecanium, cottony maple scale, and others will injur the thin bark of Honeylocust, particularly hurting small branches. Disease There aren’t many diseases that seem to effect Honeylocust. There is however a canker (Thyronectria austro-americana), which can prove fatal. If one notices cankers on their trees, then diseased or effected branches should be removed with sterilized tools. A less common disease is a type of root rot, which can prove fatal.[2][15] To avoid root rot only plant Honeylocust in well-drained soil. Where you can buy Honey Locust is not typically sold in nurseries, as it isn't a typical 'garden friendly' plant. But it can be purchased at specialty nurseries that deal in Native Plants. You can find native plant nurseries near you on our interactive map. Varieties of Honey Locust A number of varities of Honey Locust are available. Most popular are the thornless varieties (Gleditsia triacanthos var. inermis Willd.), for obvious reasons. [3][14][16] Other variaties include Thornless Honey Locust (Gleditsia triacanthos var. inermis) has a slender shape. Bushy Honey Locust (G. triacanthos var. elegantissima) has no thorns and is bushy Bujot Honey Locust (G. triacanthos var. bujotii) has slender branches with narrow leaflets Dwarf Honey Locust (G. triacanthos var. nana) is a small tree or shrub, and very friendly to landscaping Texas Honeylocust, (G. texana) is a hybrid of Honey Locust and Water Locust (Gleditsia aquatica). It is primarily grown in the Brazos River bottoms, but also found on the Red River in Louisiana and occasionally along the Mississippi. Sunburst, a hybrid that has yellow foliage and does not produce as many pods as the straight species 'Sunburst' Honey Locust. Credit Famartin, CC BY-SA 4.0 Where to buy seeds I do not know of any reputable source for Honeylocust seeds. Your best bet is to go find a tree and get permission to collect pods in the Fall. Just know that even if the tree you are collecting from has no thorns....the offspring might.[10] Uses of Honey Locust Landscaping Uses The thornless varieties of Honey Locust make nice trees for yards. They grow fast, are attractive, and are frequently used in residential and commercial landscaping. I've encountered them in people's yards, hotels, and other areas. Street tree The Honey Locust is becoming a popular choice for a street tree because of it’s rapid growth, toughness, resistance to pollution and tolerance of salt. It has been used to replace Elm trees. I believe it’s popularity may increase as more communities wise-up to the problems caused by the dreaded Callery Pear tree. [16] Companion Plants Because of the small leaves of Honeylocust, enough sunlight will pass through so that many flowers can actually grow well underneath them. Really anything that can tolerate partial shade, which is many species. Some examples would be: Aromatic Aster Short's Aster Heart Leaf Aster Bell Flower Columbine Virginia Bluebells Echinacea Rudbeckia Mountain Mint Trees that would grow well near Honey Locust would be the following; Butternut Pawpaw Persimmon Silver Maple Spice Bush Food The interior pulp of the Honey Locust seed pods is edible and is high in sugar content when green. And it was the basis for sweeteners and fermentation in several Native American tribes. Once ripe, the substance turns crisp and succulent.[3] Lumber Lumber made from Honey Locust is strong, hard, dense, and rot resistant. Furniture is sometimes made from lumber, but there is generally not enough trees of mature size to support a larger industry. [17] However, if nothing else it's rot resistance make it a good choice for fence posts. In fact, I helped my Father make a stool out of a Honeylocust stump that we had previously cut. After cutting the tree down, about 5 trunks resprouted from it. We cut those too, and flipped it upside down to make a small end table. It sort of a resembles an elephant, see it below. Medicinal Uses Extracts from the leaves of Honeylocust have been found to be strong in anitoxidents and have potential to help in the fight against various cancers.[18] And it is thought that additional uses could exist for treating rheumatoid arthritis. Native American uses There are 27 uses of Honey Locust documented by six different Tribes. The pods were used as a sweetener to make it easier to take medicine. Or sometimes and infusion was used to treat measles. Pods could be eaten raw, or the pulp used to make a drink. Bark was used in infusions used as blood medicine, tonic, cough medicine, and several other uses.[19] Final Thoughts The Honey Locust is a scary looking tree when you first encounter it. And hopefully, you see it before you feel it! But it is a valuable tree for wildlife, serving pollinators, insects, as well as birds and mammals. As a native plant enthusiast, I can like and respect the Honey Locust tree. As a hiker/outdoorsman, I absolutely hate this tree because of the hazards the large thorns pose from bumping into it, falling limb, or just stepping on a fallen limb with a huge thorn. As a general curious person, I find the massive seed pods interesting and fun as a natural 'rattle' as well as the potential relationship mammoths and mastodons had with the Honeylocust. So, I guess you could say I have a complicated relationship with this tree, and that is ok. Find more native trees here