Black Locust: Native or Not?

Native or introduced? Often, this is an easy question to answer - either a plant is from Hamilton County or it isn't. For Black Locust, however, the answer is a bit more complex. First, what do we mean by "native"? Plants can be historically native to a Country or larger region without being native to a specific State or County. Due to changes in elevation, topography, soil type, water availability, or physical barriers such as mountains or rivers, it is possible for a plant to be native to one part of the United States, but not another. 

This is the case for the Black Locust (Robinia pseudoacacia) a tree whose historic native range is thought to be the Appalachian region from Alabama to Pennsylvania with isolated pockets in the Ozark Mountains, Southern Illinois, Arkansas, and the southern edge of Indiana. Through the settlement of the West and the boom of agriculture in the 18th and 19th centuries it is thought that early settlers brought Black Locust trees from the Appalachians further inland due to their fast growth, wood quality, and its nitrogen fixing capabilities. Black Locust wood was commonly used for fence posts along agricultural properties and firewood and was instrumental in the foundation of our Country, being used to help build Jamestown and ships during the War of 1812. Evidence has been found that Native Americans also used Black Locust wood for bows and other tools, giving the tree a long and storied history in the eastern United States. 

Though it is only native to the southernmost Counties in Indiana, Black Locust trees can be found throughout the state, primarily along forested edges, in fallow fields, prairies, drainage ditches, and other sunny unmanaged areas. 

So, what is the issue with Black Locust? Surely if a tree's native range is so close to where we are, just a couple hours south on the highway and you are in its native range, it can't be too harmful for our environment, right? Well, the answer to how harmful Black Locust can be depends on how well it is doing on a particular site. In dry and sandy prairies, woodland edges, and savanna habitats, Black Locust forms thickets that outcompete other, more valuable native species and reduce already reduced prairie habitat. In addition to reducing valuable habitat, the highly fragrant Black Locust blossoms compete with native plants for pollination from bees. 

Some land managers consider Black Locust to be harmless and naturalized, while others consider it to be an invasive pest that needs to be controlled and managed. Whether you see this as valuable and naturalized plant or aggressive pest probably depends on how present it is on your property and whether it is a nuisance to you. If you own or manage large areas of woodland edges or prairies you may consider this plant a nuisance, but if you live in an urban setting or manage established woods you may not have ever seen this plant before. 

So should you manage Black Locust on your property? On sites where Black Locust is plentiful and dominant it is encouraged to reduce their population in favor of other native diversity. It is not encouraged to plant Black Locust unless you intend to use it as a crop plant. It is also unlikely that you should be concerned with total eradication of Black Locust on your property as it does provide nitrogen fixing properties to the soil and habitat for native animals.

Black Locust thrives in fields and along wooded edges.

Black Locust (Robinia pseudoacacia) has a native range in the Appalachian Range from Alabama to Pennsylvania with isolated pockets in the Ozark Mountains, Southern Illinois, Arkansas, and the southern edge of Indiana.

Works Cited
6, A. T. on F. (2018, February 6). Yale University. Black Locust | Yale Nature Walk. https://naturewalk.yale.edu/trees/fabaceae/robinia-pseudoacacia/black-locust-81
Black Locust Tree Guide: Thorns, wood, bark, flowers, areas (beware this tree). (n.d.). https://8billiontrees.com/trees/black-locust-tree/
Evans, D. J. (2025, February 10). Black Locust: Invasive in Woodlands?. Purdue Extension Forestry & Natural Resources. https://purdue.edu/fnr/extension/black-locust-invasive-in-woodlands/
​Robinia Pseudoacacia L. (n.d.). https://www.srs.fs.usda.gov/pubs/misc/ag_654/volume_2/robinia/pseudoacacia.htm