If you've run into a honey locust tree and want to know whether those long, intimidating thorns are actually dangerous, or you're trying to work out if what you're looking at is a honey locust or the very different (and genuinely toxic) black locust, you're in the right place. This page covers how to identify a honey locust tree by its bark, thorns, and pods, whether the thorns pose a real safety risk, how to tell it apart from black locust, and which thornless varieties to plant instead if you want the tree without the hazard.
In short:
• Honey locust trees have long, sharp thorns, but the thorns aren't poisonous the danger is purely mechanical (puncture wounds), unlike toxic black locust.
• Thornless cultivars like Skyline, Sunburst, and Moraine (Gleditsia triacanthos f. inermis) are the only type recommended for home yards.
• They grow fast about 2 to 2½ feet a year for their first 20 years, with bark that starts reddish-brown and ages to flat, gray-brown vertical plates.
• Don't confuse it with black locust: different flowers, different thorn pattern, and black locust's leaves, bark, and pods are actually toxic.
Honey Locust Tree Basics (Gleditsia spp.)
| Summary Data | ||
|---|---|---|
| Species | Size and Bloom | Zones |
| Common Honeylocust (Gleditsia triacanthos) | Mature height is 20 to 35’ with a spread the same as the height | Zones 4 through 9 |
| |
Blooms yellow green in June | |
Honeylocust trees are native to the United States. It is also known as the Sweet Locust, Thorn Tree, Three thorned Acacia, or Honey Shucks. All of the native species have very serious thorns on their roots, trunk and branches, earning them the dubious distinction of being the most spiny tree in our north temperate zone. We are talking about thorns that can penetrate a farm tractor tire. All the females of the species produce fruit in the form of long pods of seeds, with the pods being 10 to 15 inches long depending on the species. These pods happen to be good as cattle fodder, but in the home landscape they only make a mess.
While most of the several types of Honeylocusts are not very valuable as ornamental plants, there is one exception. The Common Honeylocust (Gleditsia triacanthos) is truly an asset in the yard or park. Fortunately, there are a number of thornless versions of this tree that have no seed pods. A thornless Honeylocust is the only Honeylocust to have in your yard. If you wish, you can get a thornless Honeylocust that does have seedpods, we include both kinds in the list below. This tree is easy to take care of, is resistant to most insects and diseases, has lovely foliage, and flourishes in a wide range of soil types.
One caution to consider is that the Honeylocust has become so popular in some communities in the East and Midwest that they are becoming more vulnerable to insect and disease problems because so many are concentrated in single area. If there are lots of Honeylocusts in your neighborhood, you need to consider that potential problem.
Common Honeylocusts are fast growers. Typically they grow 2 or 2 1/2 feet a year during their first 20 years, reaching maturity at 100 to 125 years. They have an irregular, globular shape and are about as wide as they are tall. Honeylocusts can grow to 35 or 40 feet at maturity, but in a residential landscape they are typically about 20 feet tall. They spread as wide as they are tall, their horizontally growing branches giving them a tiered and flat-topped profile.
They are deciduous, losing their leaves in the fall. Honeylocust leaves are arranged opposite each other on the branches. They are small and egg-shaped, with prominent veins aligned almost parallel to the leaf edges. They turn scarlet red in the fall. Foliage emerges in the spring, usually late May, as many, many elongated, oval leaflets ranged along 8 inch stems. There may be as many as 20 to 30 leaflets on a stem, some trees having double leaves. Because the foliage is so lacy and light, Honeylocusts do not give much shade. New leaves are light green, turning yellow green during the summer. By autumn they are a pale yellow.
Male and female Honeylocust flowers both bloom in June. They emerge in separate clusters on the same tree. Clusters of male ones, called catkins, are the most obvious. They hang about 2 inches or more long and are yellow-green in color. These give way in late July to bean-like, flat pods that hang 12 inches or more from the tree. These purplish-brown pods persist until mid-January when they finally drop.
The wood of Honeylocust is strong, hard and durable. It is resistant to shock and has attractive grain with a reddish-brown color. It is used for fence posts, pallets, crating, general construction, and railroad ties. In some areas it has been valued for making guitars.
Honeylocust Choices
Thornless Honeylocust trees can be produced by budding with scionwood taken from the thornless upper branches of selected cultivars. However, seedlings from such trees are thorny. We ve divided the following suggestions into those thornless varieties with no seed pods and those with seed pods.
Thornless With Seed Pods
Inermis (Gleditsia triacanthos) is a spreading, rounded tree that can grow to be 100 feet tall with a spread of up to 70 feet. The flowers are inconspicuous but the long, pea-like pods develop in the late summer and persist into late fall sometimes still dangling from the branches into early winter. The fall color is a warm golden yellow. Bujotii is a weeping form with pendulous branches. Elegantissima is a compact form, thornless and bushy. Maxwell has an irregular form and is very cold hardy;
Thornless With No Seed Pods
Cottage Green is semi upright and seedless. Halka is a very strong, vigorous tree. It occasionally produces fruit. Imperial has a symmetrical and compact, broad crown. Majestic is upright. Moraine is one of the earliest cultivars considered the standard. The deep green foliage turns to yellow in the fall. This tree is a favorite of Municipal Arborists. Shademaster is an old reliable. It has good form and virtually no pods. It has ascending branches. It can begin developing pods after 15 years old. Skyline is an erect, pyramidal tree that has good fall color. Sunburst is a smaller and more compact tree than the species. This tree is fast growing and will reach 30 to 40 feet with a spread of 25 to 30 feet. The leaves emerge in the spring bright yellow and then mature into a light green by summer.
Do Honey Locust Trees Have Thorns? And Are They Poisonous?
Yes, straight-species honey locust trees grow long, rigid thorns directly out of the trunk and major branches, often in dense, branched clusters that can reach up to a foot long. These thorns are serious: they're sharp and strong enough to puncture a tractor tire, and they typically show up on the trunk and lower branches, right where people and pets are most likely to brush against them.
The good news is that honey locust thorns are not poisonous. Neither the thorns nor any other part of the tree contain toxins dangerous to humans or animals. The real risk is mechanical, not chemical thorn punctures are often coated in dirt and debris, which raises the risk of a deep, dirty wound and infection rather than any kind of poisoning.
If you want a honey locust without the thorn hazard, look for thornless honey locust (Gleditsia triacanthos f. inermis) or one of its named cultivars, all bred specifically without the trait. Even thornless cultivars can occasionally send up thorny growth from root suckers or the base of the trunk, so it's worth checking young shoots and removing any that show thorns.
Honey Locust vs. Black Locust: How to Tell Them Apart
Honey locust (Gleditsia triacanthos) and black locust (Robinia pseudoacacia) share part of a name and both belong to the legume family, but they're different trees, and mixing them up matters, because black locust is genuinely toxic where honey locust is not.
The flowers are the clearest visual difference. Honey locust produces small, inconspicuous yellow-green catkins, while black locust produces large, fragrant, showy white flower clusters that look similar to wisteria and bloom heavily in spring.
Thorns tell a similar story: honey locust carries long, serious thorns on its trunk and branches at any age, while black locust rarely develops trunk thorns once mature, and any thorns young black locust trees do have are much smaller.
Pods matter most if you have livestock, pets, or kids around the tree. Honey locust pods are long up to 18 inches sweet, and safe; wildlife and livestock readily eat them. Black locust pods are short, just 2 to 4 inches, and are toxic if eaten, along with the tree's leaves and bark.
Bark is a supporting clue: honey locust bark stays relatively flat, developing long, narrow plates that run vertically along the trunk, while mature black locust bark forms deep, thick ridges with a braided, rope-like texture.
What Does a Honey Locust Tree Look Like? Bark and Identification
Honey locust bark starts out reddish-brown and smooth on young trees, then ages to gray-brown as the tree matures. Rather than developing deep ridges, it breaks into long, narrow plates running vertically along the trunk with slightly raised edges a flatter, less rugged look than many other large shade trees.
Beyond bark, the fastest identification cues are the ones covered elsewhere on this page: long trunk thorns on non-thornless types, fine, lacy compound leaves made up of 20 to 30 small oval leaflets, and later in the season long, flat, bean-like seed pods that can hang on the tree into mid-January. Reddish, flat bark plus long thorns plus long pods together is close to a guaranteed honey locust identification, since few other trees share all three traits at once.
Choose A Thornless Honey Locust For A Fast-Growing, Low-Hassle Shade Tree
A thornless honey locust cultivar is the best choice for almost any home landscape, since it delivers the tree's real advantages fast growth, light dappled shade, tolerance for tough soils, and good fall color without the trunk thorns that make the straight species risky near people, pets, or high-traffic areas. Those thorns look alarming but aren't poisonous; the actual danger is a nasty puncture wound, not toxicity, which is the opposite of black locust, a different tree whose bark, leaves, and pods really are toxic. Once you've picked a thornless variety like Skyline, Sunburst, or Moraine, honey locust is a low-maintenance tree that resists most pests and diseases and asks for little beyond enough room to reach its mature spread. If seed pods are a concern, look specifically for a seedless cultivar such as Cottage Green, Halka, or Shademaster to skip fall cleanup almost entirely.
