Invasive Plants in the Home Landscape
Article by Jessica Warren, ANR Agent – Camden County
Living in a coastal area on the state line brings some unique challenges to our landscapes and natural areas. One of those challenges is invasive plants. This isn’t a unique challenge, but it’s a uniquely large and critical challenge in our area. Invasive plants are non-native plants that displace native species, reproduce prolifically and have no predators. These plant invaders cause both economic and environmental harm. Invasive plants utilize a longer growing season, thrive on disturbance and produce many seed with high viability and successful dispersal mechanisms. Some even utilize allelopathy – a type of chemical warfare. I want to clarify, as I hear people mistakenly accuse native plants that they don’t like of being invasive. Native plants may be assertive or aggressive, but they cannot be invasive. They have evolved in this ecosystem along with checks and balances. They are a part of the ecosystem and not disruptive and damaging to it – they just may not always behave the way that we think they should (i.e. Virginia creeper, poison ivy, groundsel bush, bee balm, greenbrier, etc.).
There are dozens of invasive plant species that are affecting our coastal ecosystems, but today I’ll focus on the species that I see most often in residential landscapes and the ones that I see people continuing to plant. You may ask, “why can people still buy plants that we know are damaging and invasive?” Georgia is one of a handful of states that doesn’t have a noxious weed law preventing the sale of known invasive species. You’ll notice that you can find things for sale in the stores and nurseries here in Camden that aren’t available a few miles away in Florida.
One of our most loved enemies is lantana. Not all species of lantana are invasive, but the most popular ones are. Lantanas with multi-colored blooms are the ones to watch out for. Lantana readily spreads and expands, and through its many berries is spread to new and unseen areas where it chokes out native vegetation. Its leaves and unripe fruit are poisonous and pose a danger to pets and children. Some people love lantana as a pollinator plant, but the truth is that there are native alternatives that offer far superior resources to pollinators as well as other wildlife – and without the drawbacks.
Nandina is what I call a heritage favorite. People love it because their mother or grandmother planted it. This invader will take over and spread locally as well as to far off places through its berries – which contain cyanide. The cyanide in the berries kills many native birds that consume them, especially birds like cedar waxwings who tend to feast heavily. As you can imagine, this can pose a risk to pets and children too.
While not all species of elephant ear are invasive, some of them certainly are. Unless you’re willing to do your research on varieties, I would urge you to stay away. Elephant ear spreads profusely, especially in wet areas and is very difficult to control or eradicate in an area once established. If you’d like to see some of the damage that it can do, drive through Woodbine and keep an eye on the wetlands and drainage ditches in the summer.
Sword fern is found in a lot of landscapes and natural areas. It forms dense, impenetrable stands that choke out native understories and low growing plants. It’s also not nearly as attractive as our native fern species. This also holds true for asparagus fern, which chokes out native vegetation and spreads by its berries. If you like the way asparagus fern looks, keep it as a houseplant.
Coral ardesia is the bane of my existence. No matter how much I work to eradicate this plant from my property, it keeps popping up due to plants nearby. This nasty ornamental has wreaked havoc on natural areas in Florida, choking out understory vegetation and creating massive monocultures. You can find it beginning to do the same throughout Camden County, yet people still want it in their landscapes. This plant has an extensive and aggressive root system even on a small plant. It forms dense stands and its berries are spread by birds and other wildlife to form new invasive colonies.
Chinese and Japanese wisterias strangle mature trees and choke out other native plants. On the bright side, there is a native wisteria. Native wisteria is a little less showy, though still beautiful, and much easier to manage.
Air potato has beautiful leaves and a bad attitude. It’s the kudzu of the coast. Air potato grows up to 8 inches per day and produces a reproductive structure called a bulbil at each leaf node. These bulbils drop to the ground to produce new plants. Vines grow up to 70 feet in length and smother tree canopies, increasing the risk of fire.
Chinese tallow is a prevalent tree in home landscapes and residential as well as natural areas. This tree with its teardrop shaped leaves is also called popcorn tree because of the thousand of seeds it produces that look like popcorn. Each tree can produce over 100,000 seeds. Chinese tallow is toxic to livestock and causes vomiting in humans. It also alters the soil chemistry to control competition.
Camphor tree is another prevalent tree invader throughout our community. It can be found in home and natural landscapes. It grows and produces seed quickly, and it too is toxic. I’ve been on a mission to remove this one from my own property, but since there are so many in my neighborhood I have to remove many dozens of seedlings each year.
The last plant I’ll cover today is Bradford pear, also known as callery pear. Personally, I’ve never understood the appeal of these trees. They’re structurally unsound, prone to failure and their flowers smell like cat urine. My high school planted the courtyard where everyone went for lunch full of them – it was disgusting. Though these stinky trees were intended to be sterile, through their mass planting and increased genetic diversity they have begun to produce plants with viable seeds and thorns that can pierce a tractor tire. These gnarly and abusive offspring invade forests and field edges impacting natural areas and agricultural areas.
These plants are just the tip of the iceberg (or the Bradford pear thorn?) of the invasive plants affecting our coastal ecosystems. If you’re concerned about invasive plants and their effects, there’s plenty that you can do. First, don’t buy invasive plants. That seems obvious, but it may require some research when you’re integrating new plants into your landscape. If you think it should be easier and invasive plants simply shouldn’t be for sale in Georgia – talk to your legislators. Don’t share invasive plants. If you kill every plant that you touch except this one plant that survives everything, you might should question that plant. Remove invasive plants in your landscape. Physically removing all plants parts and either burning them or bagging them securely and sending to the landfill is a great place to start. For large shrubs and trees, the best method is often to cut it close to the ground and quickly paint the cut area with a concentrated herbicide such as glyphosate or triclopyr (following all label directions). Keep in mind that anything in our near water – including wetlands – can only be treated with aquatic formulations of herbicides. Share your knowledge. Help educate others in the community and your circle of influence on invasive plants. Contact our office if you have questions on invasive plants or their management. You can also check out the Georgia Green Landscape Stewards Program for further resources on invasive plants as well as other sustainable landscaping practices at https://site.extension.uga.edu/georgiagreen/.