David Robson Extension Educator, Springfield Extension Center, University of Illinois
Yard & Garden
Going native in your yard and garden
We can all help stop invasive plants
One of the words bantered around in recent years is “native”, as in “this or that is a native plant and much better for the landscape.” The opposite of “native” is “exotic”, which means the plant is imported into Illinois.
There’s a third term that is incorrectly equated with “exotic” - “invasive.” Many exotics are invasive but there are some invasive native plants.
Kudzu is an example of the first, and the scourge of any gardener or any one that cares about the environment. Kudzu was introduced, like so many of our so-called “invasives” with the good intention that the plant would be excellent fodder for livestock. Unfortunately, compared to the natural habitat in Japan and China, there wasn’t anything to keep kudzu in check, and it found the perfect environment in the southern states. It’s been found growing in southern Illinois, where our major defense is our sub-freezing temperatures, which can kill it back.
On the other hand, poison ivy is native and can be invasive. Birds will feast on the seeds during the winter and spread the plant from location to location. It’s invasive, but it’s also native. Does that make it better? And what about our native black-eyed Susans in our yards? They’ll multiply faster than rabbits.
Further muddying up the issue is the definition of “native.” Just what is “native?”
Is “native” a plant found naturally growing in your area? Throughout Illinois? Throughout the Midwest? Throughout the United States? Throughout North America?
Some plants have a large distribution area. Redbud (Cercis canadensis) and flowering dogwood (Cornus florida) can be found in native stands from Minnesota to Florida, though there are some genetic differences, which is why native Florida dogwoods don’t do well in Illinois gardens.
Most horticulturists expand the word “native” to a larger geographic area, such as the eastern United States, west of the Rockies, or North America.
And by and large, native plants using the above definition, adapt to the changes in Illinois climates with little damage, provided you duplicate the growing conditions.
Yet most native plants are adapted to the wide range of temperatures from sub-sub zero to those days above 100, and from drought to floods. By and large, native plants are resistant to most native insect and disease pests.
The term “exotic” now applies to plants that weren’t here when the settlers arrived. That includes many annual and perennial flowers, as well as most of our fruit trees.
There are some plants that are so rampant that we would think they are native. Dandelions come to mind, though it was our forefathers that brought that plant across the seas. It’s an exotic.
Just because a plant is invasive in one part of the United States doesn’t mean it’s invasive everywhere.
One way to look at “invasive” is to think “If this escapes, will it take over wild plants, growing better than they do, and destroying some of our natural areas?
In Illinois, some of these invasive plants have been given the distinction of “exotic weeds”, and fall in categories that make them illegal to sell, plant or propagate any forms unless they can be proven to be non-invasive varieties. Essentially, the last part means the plant has to essentially be sterile, not producing any viable seeds.
Vining or Japanese honeysuckle and just about all the buckthorn are listed in this Act. Vining honeysuckle was a great groundcover, but like kudzu, it just keeps growing and growing. Buckthorn, a shrub, is just as rampant.
There are many shrubby honeysuckle that are just as bad, but aren’t in the law. Just walk into most woods and try not to see honeysuckle growing. It would be tough to recommend planting honeysuckle as an ornamental shrub, though the native honeysuckle vines are okay.
Before planting something, do a little checking to make sure it’s not spreading and potentially suffocating native plants. Ask at your garden center or nursery. Contact your local Extension office. Ask your Ill. Dept. of Natural Resources Conservation officer.
David Robson is an Extension Educator, Horticulture, at the Springfield Extension Center, University of Illinois Extension, P.O. Box 8199, Springfield, IL 62791. Telephone: 217-782-6515.
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