Honey Locust

Photo of Honey Locust tree taken in mid spring
Basic Information
Tree ID: 
Genus and species: 
This Gleditsia tricanthos, or Honey locust, is located in a small green walkway between Winchester Ave and Lockstreet behind Yale Health. The honey locust is a deciduous tree native to central North America. However, it is highly adaptable to different environments, and has been introduced worldwide as an aggressively invasive species, considered as a nuisance by farmers as they grow quickly and outcompete grasses and crops. They can reach a height of around 20-30m; considering our tree is only 7.70m, it is most likely very young. Honey locusts have bright green, pinnately compound leaves which turn yellow in the autumn and are shed in the winter. They leaf out relatively late in the spring (May), when strongly scented, off-white-colored flowers appear. The fruit of honey locusts are flat legumes, which are eaten by herbivores who then excrete the seeds in droppings. The pulp on the inside of the fruit is sweet, where the name Honey locust originates, and has been used for food and traditional medicine as a sweetening agent by several Native American tribes.
Collected Data
Tree shape: 
Date of tree entry: 
7.70 m
Diameter at breast height: 
17.50 m

The bark of the Honey Locust tree is made up of “plates” separated by groves. In addition to patches of moss, horizontal lenticels can be seen running up and down the length of the trunk. The bark of Honey Locust trees tends to be either gray or brown and is initially relatively smooth. Later in the tree’s life, the bark breaks into narrow curling strips separated by crooked boundaries. In native species, clusters of branched thorns can often be found on the stem and bark of Honey Locust trees. Notably, the bark from Honey Locust trees was used by several Cherokee tribes as a source of medicine, food, and construction materials. For this specific Honey Locust tree, there were very few visible changes in the bark observed between late winter and mid-spring.
Twigs & branches
Honey Locust trees have a wide variety of twigs and branches ranging from thin to stout. The twigs often grow in a V shape or zig-zag pattern. They are glossy and usually reddish-brown. The branches have visible lenticels and in some species are covered with clusters of thorns. Although thorns can be found on any branch, it is the older and lower branches that tend to be more covered in spines. One theory is that the branches closer to the ground are tend to be thornier in order to dissuade animals from consuming them. Notably, the Honey Locust is one of the only species of tree that doesn’t produce visible terminal buds at the tips of its branches.
Honey locust trees are deciduous, and have alternate, pinnately compound leaves. The leaflets are 0.75 to 1.5 inches long, and they are bright green in the summer and turn bright yellow in the autumn. In the winter, the leaves fall off and become absent. Honey locusts leaf out relatively late in the spring, in May.
Reproductive Structures
The honey locust is polygamodioecious, which means that nearly all flowers on a single tree are all the same sex but there are some perfect flowers, which have both male and female reproductive structures. Thus, the honey locust can rarely self-pollinate. The flowering of the honey locust begins the reproductive cycle, taking place in early May to mid-June depending on the climate. The flowers of the honey locust are off-white in color, and are very fragrant. The strong fragrance of the honey locust attracts insects, who pollinate the tree. The male, or staminate, flowers are densely packed into clusters, with 5-7 stamens. The female, or pistillate, flowers are more loosely clustered and have a single, small pistil that has a broad ovary and two-lobed stigma. Perfect flowers have stamens that surround the pistils. The sepals of both flowers are around 3-4mm long, while the petals (4-5 on each flower) are 3-6mm long.
The fruit of the Honey locust is flat and pod-shaped (legume). It is hairy, leathery, flattened, and usually between 6-8 inches in length. It matures in the early autumn, initially green but when ripe turning a dark brown. The fruit generally appears in September or October. The pods of the Honey Locust are filled with sticky and sweet beans, contributing to the tree’s name. The fruit is consumed by herbivorous wildlife and livestock, and the digestive system of animals breaks down the hard outer coating of the seeds to make germination easier. The pods are surrounded by a tough, leathery skin that contains a pulp which is very sweet and crisp in ripe pods.
  • Mid-spring
  • Early-spring
  • Late-winter
  • Early-winter
Natural range of distribution: 
The natural range of the honey locust tree can be found in central North America. Typically, honey locusts are most commonly found only in moist, fertile soils near streams or lakes. However, it is also very adaptable and can survive urban and suburban conditions as well as compacted soil, road salt, alkaline soil, heat, and drought. The hardiness and fast-growing nature of the honey locust make it an invasive nuisance in agriculture; however, this also makes them popular ornamental plants in new parks or housing developments, and other locations where shade is wanted quickly.
Origin, history, and uses: 

The Honey Locust tree originates from the central United States. Specifically, it comes from the region between Pennsylvania and Nebraska that is south of Minnesota and north of Louisiana. Honey Locusts are most common in the valleys of streams in Illinois and Indiana.

Historically, the Honey Locust tree has been very important. The wood is dense, heavy, and stiff, making it desirable for many types of construction. In the past, it was often used to build houses, fence posts, pallets, and a plethora of other projects. Additionally, the Cherokees in Tennessee often made hunting longbows from the Honey Locust’s wood. It has been reported that some Cherokee tribes used Honey Locust trees as a source of medicine, food, and wood to carve games with. Beyond humans, many animals have also historically depended on these trees. The pods of Honey Locust trees are more than 40% carbohydrates by mass, making this tree an important source of food for squirrels, deer, crows, bobwhites, starlings, opossums, and other small mammals.

The Honey Locust tree continues to have important uses today. Its fruits are used as a food source for livestock. Additionally, because of its stiff and durable trunk, Honey Locust trees are planted as wind breakers and to protect areas from erosion. When fully grown, these trees form dense thickets of vegetation which serve as an important source of shade and cover for many different animals. Finally, some research suggests that the Honey Locust tree possesses important medicinal properties. The juice of Honey Locust pods has antiseptic properties and is occasionally utilized as a home remedy for indigestion, flu symptoms, and catarrh. 

Honey Locust trees have an average lifespan of 125 years. The tree usually begins to flower when its leaves are fully developed. In southern regions, this occurs around mid-May while in northern regions flowering doesn’t occur until mid-June. The legumes ripen during the autumn (sept-oct) and usually fall off at the beginning of November. The Honey Locust tree becomes seed bearing at approximately 10 years old and produces seeds once every year. Honey Locust trees can thrive in a variety of climates but inviable in temperatures under -33°F. These trees prefer to grow in sunny conditions but juvenile ones can prosper in partial shade. Honey Locust trees can also grow in a variety of water conditions and have a fair tolerance to both droughts and floods.

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