There is a new landscaping trend to incorporate more native species. In general I am in favor of that, but people need to learn a little about terminology before embarking on a drastic revamping of their environment. Just because something is native doesn’t mean it won’t have weedy qualities.
Most of our troublesome weedy species are exotic species. That just means they were brought here from some other place, most likely Europe or Asia. Many have become naturalized and people don’t even consider them exotic. Queen Anne’s lace, gaillardia and yarrow are examples.
Plants that are invasive spread and choke out less aggressive native ones. This reduces the genetic diversity and that can cause a variety of problems. The same can be said for invasive exotic animals like nutrias. Invasive species change the environment.
Think of your lawn. Let’s say crabgrass, an exotic annual weed, gets established and chokes out much of your desirable perennial lawn grasses. Bare spots will develop and more weeds can come in and add to the carnage. Similar scenarios occur in our wild areas but we are usually unaware of it.
In past history we have polluted our environment with exotic plants such as kudzu, multiflora rose, wisteria, Japanese honeysuckle, several privets, and countless other trees, shrubs, vines and herbs. Some have simply escaped cultivation. Others were purposely planted for erosion control.
Whenever a single species dominates an ecosystem bad things happen. Animals that depend on certain plants for their survival begin to disappear. We don’t care about this until the struggling species are dear to us.
This brings us back to protecting native species. Some are just as bad as the exotic ones. At our greenhouse plant sales I’ve had people request trumpet vine and Virginia creeper. These are two strongly invasive native species. Once you have them on your property you’ll never get rid of them. They’ll climb all over your house and shrubbery. Passion vine can be put in that group too.
Poison Ivy is a native plant, but we don’t need to encourage it. It invades enough on its own. Copperheads and timber rattlers are native species too, but we’d rather they stay in less populated areas and not take up residence near our homes.
I haven’t received any requests for poison ivy, but people have inquired about Joe Pye weed, ironweed, hemp dogbane and goldenrod. Ask any cattle farmer about the headaches caused by any of those species. I know my father-in-law struggled with all of them.
In general, I must admit that most native species don’t overpower their environment. For that reason I am firmly in the corner of native plant enthusiasts. My only qualm is when people make statements that all natives are good and all exotics are bad.
Not all exotic plant species are invasive. Too often people use the terms exotic and invasive interchangeably. Exotic simply means the plants were imported from somewhere else and invasive means they have a tendency to spread all over the country. Some native species do that too.
Ted Manzer teaches agriculture at Northeastern High School (firstname.lastname@example.org).