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Honey locust – sweet name for invasive pest

From regular series in the Progress:

Plants of the Southeast

Honey locust – sweet name for invasive pest




Photo / Linda Lee

No other tree in our part of the world has thorns quite this size, which makes identification of the honey locust very easy. 


By John Nelson,

Curator of the A.C. Moore Herbarium at the University of South Carolina



It’s the branch of a tree, but the honey locust is no good for a tree house. Take a look at the thorns which can be found up and down the trunk and also potently arming the branches. You won’t be inclined to fool around with these stickers as they really mean business, sometimes up to 5 inches long, needle-sharp and often divided at the base: the species’ scientific name means “three-spined.” 

No other tree in our part of the world has thorns quite this size, which makes identification very easy. These are “true” thorns in that they contain sap-conducting tissues which are continuous with the interior of the tree trunk. Birders will be familiar with the grisly shrike, or “butcher bird,” which uses these thorns for impaling prey.

Large individual trees may be nearly 80 feet tall and often with a rounded or flat-topped crown. The bark on an old tree will be dark grey, eventually splitting into ridges. The leaves are compound and somewhat fern-like. Its flowers (male and female on the same tree, usually) are greenish and fairly inconspicuous; they appear in late spring. Following the flowers, pale green beans will develop. These beans enlarge dramatically, eventually nearly 2 inches wide and over a foot long. The pods turn a handsome, shiny purple-brown and almost always curl as they mature. The plump hard seeds within the pod will be in a line, their linear arrangement easily seen from the outside. Much of the interior of the bean is eventually filled with a moist fragrant pulp which is edible. To me, these things are not much worth eating, but that pulp is sort of tasty, sticky and sweet. Like cocoa paste. (Is there such a thing?) Now, I’ll have tell you that the common name of this tree includes the word “honey,” not because it’s good for honey production, but because the fruits have that sweet, tasty pulp. At least, that’s my idea.

The beans fall from the branches in the winter, often forming a pile around the base of the tree. These beans are prized by wildlife including deer; cattle and hogs like to eat them too. The seeds, once they’ve gone through an animal, will readily sprout, as long as they end up in a sunny place. In the autumn, the foliage turns an attractive bright yellow.

This species is commonly seen in much of the eastern USA, through the Mississippi River valley and into Texas. In the South, the honey locust is most often encountered in the Piedmont and mountains. It is actually something of a pest sometimes and has fairly recently been designated as “invasive” in parts of South America and Australia. Here in the USA, these trees are often planted, as they form good windscreens, and are quite hardy, affected by few pests or diseases. They also make a great shade tree for city streets…but then there are those nasty thorns. Well, turns out that a thornless variety is available. Which is good if you want a tree house. 

John Nelson is the curator of the A.C. Moore Herbarium at the University of South Carolina in the Department of Biological Sciences, Columbia, S.C. 29208. As a public service, the Herbarium offers free plant identifications. For more information, visit or call 803-777-8196 or e-mail This email address is being protected from spambots. You need JavaScript enabled to view it. .


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