Honey Locust Trees vs. Black Locust, Compared

by Erin Marissa Russell

Honey locust trees and black locust trees have similar names and share some of the same characteristics, but as separate locust species. These two tree varieties also have plenty of traits that aren’t in common between them. We’ll teach you how to tell the difference between these popular types of locust trees and also review some of their similarities and differences. Keep on reading to learn how to identify black locust and honey locust trees.

How Do I Tell Honey Locust From Black Locust Trees?

Although their names are similar, there are plenty of ways you can tell black locust trees and honey locust trees apart. Here are the signs to look for when you need to differentiate these trees.

• Bark and Thorns: The black locust bark has a dark color with a pattern of furrows that looks like rope that’s intertwined. Honey locust trees, on the other hand, can have dark brown or dark gray bark. Both varieties of locust trees have sharp thorns. The honey locust has clusters of red-brown thorns among the branches or single thorns lining each stem. The thorns have a three-pointed shape, but if they form sharp spines on the honey locust tree’s trunk, there may be more than three points. While black locust trees may also display thorns, the thorns will be limited to the base of the trunk, while the thorns of the honey locust appear all over the tree.

• Flowers: Both varieties of tree flower at the same time, so if the flowers are visible, you can use them to identify the type of tree. Black locust trees have small, white flowers, forming clusters between four inches and eight inches long. One variety of black locust tree, the Purple Robe Black Locust, has pinkish purple flowers. The blooms of honey locust trees are greenish yellow and stop at two inches long.

• Leaves: Although leaves from both black locust trees and honey locust trees are long compound leaves with central stems, the leaves of black locust trees are simple compound leaves, while the honey locust tree has contrasting bipinnate compound leaves. You can tell when a tree’s leaves are the bipinnate compound variety because the entire leaf shape is divided into individual leaflets, each of which is again divided into its own individual leaflets. Simple compound leaves are divided only once into individual leaflets. Bipinnate compound leaves also have side stems coming off of the central stem, which simple compound leaves do not have.

The new leaves of the honey locust tree will emerge earlier in the season than those of the black locust tree. The color of the leaves is another way you can identify each tree. The black locust leaves are bluish green in the summer and turn yellowish green in fall. The honey locust trees are a vivid green color in the summer and become completely bright yellow in the fall.

• Seed Pods: Although both trees have seed pods that are shiny, smooth, and thin, they differ in size. The seed pods of the black locust reach lengths between two inches and four inches at maturity, while the honey locust tree’s seed pods can grow to reach lengths between 12 inches and 14 inches. The seed pods of the honey locust tree have a distinctive aroma similar to honey for which the tree was named.

• Shape: The trunk of a black locust tree grows straight, with the separate branches and stems coming off the trunk in a zig-zag formation. Honey locust trees have a short or arched main trunk shape, and the branches and stems grow off it in zig-zag formation like that of the black locust tree. So although the growth patterns are similar, if the trunk of a tree you are working to identify is arched, that tree must be a honey locust tree. And while the black locust spreads a maximum of between 20 and 35 feet, honey locust trees can have a spread that reaches 60 to 80 feet.

Honey Locust Versus Black Locust Trees: Similarities

• Both the black locust tree and the honey locust tree are native to parts of the United States of America. You’ll find both types of trees spread throughout North America, with the exception of the states of Oregon and Washington, which only have black locust trees.

• Both black locust and honey locust trees are locust trees that come from the pea family, Fabaceae.

• Between the middle of spring to late spring, both species of locust trees will be in bloom.

• Both black locusts and honey locusts can be either trees or shrubs.

• Both the black locust tree and the honey locust tree can be grown in USDA Hardiness Zones 3 through 8. Both varieties also need to grow in full sun in order to thrive.

• Either the black locust tree or the honey locust tree can be grown near a black walnut tree. Both varieties are also tolerant of deer due to their thorns. Because they are thorny trees, both varieties are also tolerant of white-tailed deer.

Honey Locust Versus Black Locust Trees: Differences

• The botanical or scientific name for the black locust trees is Robinia pseudoacacia, and the botanical name for honey locust trees is Gleditsia triacanthos. The black locust tree also has the common names of false acacia tree or yellow locust tree. Honey locust trees can be called thorny honey locust or thorny locust trees, or you can see the common name as one word: honeylocust.

• Honey locust trees can grow larger than black locust trees at maturity. While wild black locust trees can stretch up to 80 feet high, most specimens of mature trees top out at 50 feet, whereas the honey locust is a large tree that can reach up to 100 feet tall.

• Black locust trees are more adaptable to different types of soil than honey locust trees. A black locust will happily grow in drought, clay soil, poor soil, soil that contains salt, or on the banks of a river as long as there are well-drained soils. The honey locust tree needs soil that is rich and moist to really flourish. The honey locust tree can be cultivated in soil that doesn’t have plenty of moisture, contains high levels of salt, is made of clay, or has a high pH level, but the honey locust tree will be more vulnerable to pests and diseases due to the stress of adapting to these environments.

• In the midwestern United States, black locust trees are considered an invasive species because they are a fast-growing tree that can rapidly reproduce by root suckering and self-seeding. In many areas, it is not advised to introduce black locust trees because of this tendency to be invasive. The honey locust tree is not invasive.

As you can tell, the similarity between the names of these two tree varieties isn’t where their likeness ends. However, there are plenty of differences that can help you to tell the difference between black locust and honey locust trees. After reading our explanation, you should be able to identify each of these trees and tell the difference between them when you see them in the wild, as well as learning about what makes them alike and different.

Learn More About Locust Trees

https://communityenvironment.unl.edu/plant-month-honeylocust