Invasive Plant Species in Ohio

Emma Houston is a gardener, bookkeeper, writer, and mother of three. She is spending her time mostly in her garden. When she is not there, you will find her working on developing her own line of homemade natural skincare products.

The spread of invasive species happens right under our noses and the majority of people are completely oblivious to it. We’ll be discussing the significance of it in Ohio, but it’s a big issue all around the world and a difficult thing to control.

The term invasive species refers to any living organism, be it a plant, animal, or something else entirely, that is not native to an ecosystem and causes harm upon finding its way into said ecosystem.

They might outcompete native species for resources and endanger those species, preventing their natural benefit to the environment. An invasive species could reduce native biodiversity, introduce parasites, or become a predatory force to other species. 

The crazy thing about invasive species is that a large part of the reason why they spread so easily can be attributed to human activity. Specifically in Ohio, there have been many non-native plants introduced for the purposes of erosion control or medicinal use and in some cases they have actually been introduced by accident. 

It’s estimated that the presence of plants and animals costs America upwards of $120 billion in damages every year. An absolutely staggering number, and one that needs to be dealt with on a state-by-state basis.

Ohio is a place where the problem is pretty significant and that may be due to the fact that Ohio has more roads than anywhere in the United States and many miles of waterways, which makes it somewhat of a crossroads for commerce. The spread of invasive species comes with that.

Let’s take a look at some of the most prominent offenders in the state:

Purple Loosestrife

The purple loosestrife first arrived in Ohio back in the 1800s, and the assumption is that it was introduced to the Great Lakes by way of contaminated European cargo ship ballast, and has been growing ever since. 

What’s unfortunate about this plant is that it looks quite similar to a native loosestrife plant and is often mistaken for it. People fail to realize that there’s an invasive plant growing and so they don’t take any measures to deal with it. 

It’s distinctive by the fact that it’s longer and its flowers aren’t as widely-spaced. You’ll typically see it along river edges where it will overtake the habitat needed for native species, because of how quickly it spreads.

This plant has an extended flowering season that lasts from June to September and will often produce two or three million plants per year. This is much more than the majority of native plants and so there is less of an opportunity for growth. 

The purple loosestrife is also an unsuitable habitat for native wildlife which is extremely detrimental when it’s dominating the area. 



The common buckthorn originated in Europe and Asia and was brought to the United States for specific wildlife enhancement programs and also as an ornamental plant for public and private gardens.

Naturally, it escaped these environments and spread out across most of the states in New England as well as other Northeastern states like Ohio. The reason why this happened is also the primary reason as to why it’s classed as an invasive species, and that’s the viability of the seeds.

Much like the loosestrife, seed production is high, but buckthorn seeds can also last in the soil bank for up to six years. And so buckthorns can spread quite easily and there are a few other factors contributing to their resilience.

There are no predators or diseases affecting this plant right now, leaving little to reduce the spread and it has a shade-tolerance that ensures it can last even outside of the sun. It can quickly become a dominant presence in the ecosystem and overwhelm the presence of native plants.

Garlic Mustard

The arrival of the garlic mustard plant in the United States was a well-intentioned one. The idea was that it could have some medicinal benefit, having been used in England as a treatment for bruises, ulcers and the common cold.

Unfortunately, the spread of it outside of medical and research facilities couldn’t be contained and it soon found its way into the forests and woodland areas of America, where it is not recorded in every single county in Ohio.

You’ll notice a bit of a pattern here, in that garlic mustard is yet another species on this list that has a high seed production rate and great viability in the soil. It can remain viable for up to ten years.

In the forests of Ohio, the roots of the garlic mustard plant exude a chemical that suppresses soil fungi many native trees and wildflowers require in order to thrive, and in turn greatly reduces their growth.

Japanese Knotweed

Another invasive species that has been around in the U.S since the 1800s, the Japanese knotweed is a perennial plant that can grow up to 10 feet tall and because of this it was popular for ornamental purposes. 

The threat that these plants pose is mainly to riparian areas, which is where land meets rivers and streams. There’s a lot of native wildlife in those zones and knotweed will spread like crazy there because its roots tend to come in the form of rhizomes that can survive when traveling downstream.

New colonies will grow in dense thickets along the rivers and overtake the natural species. This might become an even bigger problem very soon because riparian areas are a place where ash trees can thrive, and the wood from those is important for the textile and building industries.

These trees are already massively under threat in other Northeastern states because of the spread of the Emerald Ash Borer, an invasive Asian insect that feeds on Ash wood and is extremely difficult to control. Should these insects find their way to Ohio, which is a strong possibility, the ash trees could be in even more serious jeopardy.

It’s important to be aware of these and other invasive species so that we can do whatever we can to ensure the spread is controlled. The best course of action for you is to familiarize yourself with which species are problematic and see if you can volunteer, or perhaps initiate removal efforts.