Let's Talk Invasives (And Natives!)

May 18th, 2018

If you’re anything like me, you’re a plant lover. Maybe you acknowledge the beauty of a flower, or maybe you’re more of a biologist and acknowledge the sheer fact that we need plants to exist. I would say I’m both. We owe a lot to the plants on this planet. They give us food, shelter, medicines, and probably most importantly, oxygen! It’s time that we start giving back and realizing that it’s not all about gardens or pretty landscapes (although no one is against that), and it’s definitely not all about us. It’s about the health and well-being of our planet. Let’s start at the beginning.

What is an invasive species?

An invasive species is one that did not originally/naturally occur in the area that it is in, and one that can cause harm to environmental or human health. In our case, we will be talking about invasive plants!

Why are they here?

Most invasive plants are here (like privet, kudzu, and English ivy) because someone originally wanted them to be. They were planted as ornamental plants (people thought they were pretty), and now they are wreaking havoc on our landscapes. The thing is, these guys can reproduce at rapid rates because they don't have their natural competitors to keep them at bay. And unfortunately, our native plants can't simply move to a different location. Instead, they are out-competed by this more aggressive plant that was introduced into the landscape. It isn't fair!

Why should you care?

Invasive plants outcompete our native plant species by shading them from sunlight (think privet and kudzu) and using up all of their resources. Our native plants need adequate space, sun, water, and nourishment to live. With an aggressive plant like privet that grows very quickly, all of those resources are used up before our natives even get a chance. Kudzu can take over forests, killing trees by shading them from sunlight or becoming so heavy that they break the tree in half. And remember when I said that it’s not all about us? The wildlife that usually depend on native plants for habitat and food can be put in danger from dwindling resources. Invasive plants can also drastically change a landscape, affecting water flow patterns and nutrient cycling in the environment, as well as lowering biodiversity and therefore a healthy habitat for all living organisms. 

One example of how detrimental invasive plants can be is the example of Garlic Mustard (Alliaria petiolata) and a native butterfly called Virginia White butterfly (Pieris virginiensis). Garlic mustard omits a chemical called sinigrin, an attractant found in most toothworts. The Virginia white butterfly uses this chemical attractant to identify the plant it wants to lay its eggs on (usually a toothwort, or Cardamine of some sort). Garlic mustard produces a much larger amount of sinigrin than toothworts, so the butterfly naturally chooses the plant with more sinigrin, being garlic mustard. The problem is that there’s TOO much sinigrin within garlic mustard, which is actually lethal to the caterpillars and causes them to die after ingesting the leaves. How sad is that? The butterfly evolved a certain way without this plant, and now it suffers because of its introduction to the butterfly’s habitat. This is just one way an invasive plant species can be bad for not only the land, but the wildlife surrounding it. 

Another example of invasive species is actually an insect from Asia called the hemlock wooly adelgid (Adelges tsugae). It affects one of our native trees (and one of my favorite trees), the eastern hemlock (Tsuga canadensis). This adelgid is very tiny, but there are lots of them. They attach themselves to the base of the needles on the tree and deplete the tree of its nutrients, which eventually leads to needle loss and death of the tree. Whole forests of this tree are disappearing from this adelgid, which means tremendous habitat loss for the wildlife that depend on them.

 There are a multitude of other invasive species dynamics just like these two, and there is always something that we, as land owners and nature-lovers, can do to lessen the negative impact on the native plants that we know and love.

How can you help? 

When it comes to controlling invasive plant species, the best method is prevention - just don't plant them! Always plant native plants instead. Or at least make sure the plants you buy for your yard are not invasive before putting them in the ground. If you have invasive plants on your own property, you can easily do your part by removing them. It’s also good practice to check yourself before you leave an area that is infested and remove any seeds that may have attached to you while you were out, that way you are preventing the spread. And if you find that you enjoy being outdoors and helping out the land, maybe consider volunteering with a local nonprofit or state agency. A lot of organizations hold weed pulls and other opportunities for you to get involved! You could also talk to your local nursery to see if they’re on the right track when it comes to preventing the spread of invasives. Sadly, a lot of invasive plants such as Vinca and English ivy are still sold at nurseries as ground cover. Let’s put an end to this!

Here are some good resources for local information about invasive plants:

Tennessee Invasive Plant Council
Center for Invasive Species and Ecosystem Health 

Join efforts with Reflection Riding Arboretum & Nature Center! 

Let’s save our natives and show the invasives who’s boss!

About the Author

Melanie Flood is a nature-loving outdoors enthusiast. She constantly strives to take part in the conservation of our native plant species and hopes she can inspire others to do the same. When she isn't outside staring at plants, she's probably posting about them on her Instagram. Follow her @mflood023.

Posted by Melanie Flood  | Category: Horticulture

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