I’m one of those transplants to Georgia. Having grown up in the Midwest, I was struck by Georgia’s beautiful trees, rolling hills, mountains, and lovely gardens. You might imagine my horror the first time I saw some of the beautiful trees completely covered by a coat of green vines.
I quickly learned that the culprit is Kudzu, a vine that was introduced into the US from Asia for erosion control and potential fodder for cattle. Everyone in the Southeast knows this. It is an invasive plant and joins a list that is termed the “dirty dozen” by the Georgia Forestry Commission. Others on the list are non-native privet, Japanese stiltgrass, non-native lespedeza, Chinese tallowtree, Japanese climbing fern, non-native olive, English ivy, mimosa, trifoliate orange, and wisteria.
Invasives are any species that is not native to a given ecosystem and whose presence causes economic or environmental harm or harm to human health. Typically, they can take over a landscape and can be found in a wide variety of conditions—sun, shade, dry, moist, etc. They can also quickly colonize an area by a wide variety of means—seed, sprouts, rhizomes, etc. Because they are not native to the area, they don’t have any competitors, predators, or pathogens to control their spread. It is not unusual to find them in areas that have been disturbed for a variety of reasons such as cuts for roads and power lines, logging, etc.
Most of the plants that are invasive were introduced in the US as landscape plants, providing more options for our gardens. Many come from Asia and other areas that have the same environmental conditions as the US. It is good that the vast majority of these plant introductions don’t become invasive and have expanded the options for diversity in our gardens. Loropetalum (from China and Japan), evergreen azaleas (from Japan), and gardenias (from China and South Africa) are just a few of examples of these.
Others such as Japanese and Chinese wisteria (not to be confused with American wisteria), Japanese honeysuckle (not the native honeysuckle), and English ivy unfortunately are invasive. Where they have taken over the ecosystem and have become invasive, they create problems and the native plants are unable to compete with the aggressive growth of these non-natives.
I’ll mention just a couple of the plants that have had significant impact on Georgia’s ecosystem. One that I’ve fought in my backyard is Chinese privet (Ligustrum sinense). From April through June, you might detect the scent of this invasive plant. To my nose, it is not a pleasant scent, but others may have a different impression. It may also be the source of nasal irritation for some at this time of year.
This aggressive semi-evergreen shrub can quickly take over spaces, resulting in thickets up to 30 feet tall, particularly in shady areas. The purple-black berries that appear in winter are enjoyed by the birds, who then help spread seeds through their droppings. I have pulled many of these shrubs in my day, but I can’t keep up with the birds and their feeding on the vast number of privets nearby. Nor can I remove all the roots that send up new shoots.
Another invasive that blooms in May to July is the mimosa tree (Albizia julibrissin). In my naivety, when I first arrived in Georgia, I enjoyed the sweet smell of the unusual blooms on the mimosa tree. This tree was introduced from Asia in the 1700’s, so it has been in our landscapes for centuries. The pretty pink flowers in the early summer develop into legume pods later in the year.
Unfortunately, this tree can grow about anywhere in the South—from wet to dry land, and sunny to shady areas. It is a prolific grower, growing from seeds strewn around or from root sprouts. It is not unusual to see it growing on abandoned farmland.
So, what can you do to help? As with most things, prevention is the best way. Don’t choose these plants for your garden. Believe it or not, some plant nurseries still offer these plants for sale. Therefore, it is important that you be able to identify the invasive plants from those acceptable for your garden.
If you need assistance, there are a number of sources of information about invasives available. Some websites that may be helpful include:www.gainvasives.org,www.invasive.org/101/index.cfm,www.invasivespeciesinfo.gov/what-are-invasive-species, and www.invasiveplantatlas.org.