Invasive species spotlight: Killer vines
Non-native vines are invading Florida's natural areas, engulfing and smothering pines and oaks and causing ecosystem damage.
When you think of Florida, what landscape do you see in your head? Chances are it includes either tall, majestic pines or wide-spreading live oaks. Florida’s oak hammocks, cypress domes, and pine flatwoods are iconic. Whether we’re headed down south to the land of the pines or tying a yellow ribbon round the ol’ oak tree, Florida residents know how important our oak and pine trees are. They’re tall, strong, and beautiful- but also vulnerable to some of our most destructive invasive species.
Florida’s non-native invasive vines have been introduced from tropical locations around the world, and they have a few things in common: they thrive in our wet and humid weather, they can grow unbelievably quickly, and many of them can shade out and kill mature pine and oak trees.For more information on Florida’s invasive plants, please visit the University of Florida Institute for Food and Agricultural Science’s Invasive Plant Page. You’ll find information on lots of invasive species as well as exciting new studies on invasive plant treatment and removal.
Old World Climbing Fern
and Japanese Climbing Fern
There are two extremely aggressive species of invasive climbing fern in Florida, old world climbing fern (Lygodium microphyllum) and Japanese climbing fern (Lygodium japonicum). These vines are both listed as Category I invasive plants by the Florida Exotic Pest Plant Council (FLEPPC), meaning that they alter native plant communities by out-competing native plants and changing ecological functions. Both species of climbing fern can grow up to 90 feet high and can engulf entire islands and sections of forest, shading out and killing mature trees. They can also act as a thick groundcover, making it impossible for native plants to grow.
These vines have small, fern-like leaves and produce thousands of tiny spores, which are spread by animal and human movement and can be blown for miles by the wind. This means that lygodium is often found in remote areas, and infestations can remain undiscovered for a long time. In most parts of Florida, these vines don’t die back in the winter, so they can produce extremely dense and heavy mats of vegetation.
If you find lygodium on your property, please get rid of it! The spores will spread quickly to other nearby properties and natural areas, and the vines could pose a danger to your trees and other nearby plants. Pulling it up by the roots and bagging all of the plant material will help to get rid of the infestation, but you might have to return and pull up more vine if some root material remains in the ground. You’ll also want to immediately wash your skin and clothing to get rid of any spores. Lygodium can also be killed by some common herbicides available to the public, including glyphosate. If you do spray lygodium with herbicide, make sure that you cut any climbing fronds at waist height and then spray the bottom portion of the plant.
Air Potato and Winged Yam
Air potato (Dioscorea bulbifera) and winged yam (Dioscorea alata) look very similar at first glance, and both are category I invasive plants in Florida. Both vines have twining stems, heart-shaped leaves with no central vein, and large hanging tubers. Air potato has slightly fatter, wider leaves and very round tubers, while winged yam has more elongated leaves and long, knobbly tubers. Both species can grow up to eight inches a day and engulf trees and understory plants. They produce lots of "potatoes," which lie dormant through the fall and sprout in the spring. These vines are handsome and fast-growing, so they’re often left alone in gardens and backyards, but if they aren’t removed they can overrun large areas and cause serious damage to native plants.
If you want to remove air potato or air yam from your property, cut the plants at waist height to kill the climbing portion and then pull up vines at the root or spray the lower portion with an herbicide like glyphosate. Pick up tubers, bag them tightly, and throw them away to prevent them from sprouting the next year. If you have a large air potato infestation, or you don’t mind waiting a while to see results, you can order air potato beetles from the University of Florida- these beetles come from the plant’s native range, have been extensively tested to make sure they don’t cause damage to native plants, and can help to shrink and control air potato infestations by defoliating the vines. Unfortunately, air potato beetles are so specific and picky that they won’t eat the closely related winged yam, so you’ll have to hand pull or spray winged yam to remove it.
Rosary pea
With its compound leaflets and bright red berries, this handsome vine is often found growing on fences and in gardens. In fact, rosary pea (Abrus precatorius) was most likely brought to Florida for use as an ornamental garden plant, but quickly spread to natural areas. Rosary pea vine can grow over 80 feet tall and shade out bushes, groundcover and trees. The seeds are spread far and wide by birds, so this plant can infest remote spots and cause damage to undisturbed natural areas. Due to the problems it causes in native ecosystems, rosary pea is listed as a Category I invasive species in Florida.
Rosary pea seeds contain one of the deadliest toxins in the plant kingdom. A single seed, if it’s damaged or chewed to release the toxin, can cause death in an adult human. This is another great reason to remove rosary pea from your yard, even if you aren’t worried about it over-running your garden or native plants! To remove rosary pea, pull it from the roots, and be sure to bag it and get all of the seeds. You may have to return and pull the vine several times. For high-climbing vines, remove before the plant produces seeds, or you’ll have to return the next year to remove the baby plants. Cut the vine at waist height and pull from the roots or spray the lower portion with an herbicide like glyphosate.
Skunk Vine and Sewer Vine
They sound pleasant, right? Skunk vine (Paederia foetida) and sewer vine (Paederia cruddasiana) (yes, really, that's its scientific name) come by their names honestly; when damaged, their leaves release a very unpleasant skunky or sulfuric smell. These vines don’t tend to grow as tall as the others on this list, but they can still reach 30 feet or more in height, making them dangerous to small trees, bushes, and groundcover plants. Skunk vine has elongated heart-shaped leaves, tiny light-colored flowers, and shiny, round, brown fruit. Sewer vine is very similar, but with flattened yellow or brown fruit. Both of these vines seed prolifically and the seeds are probably transported to new areas by birds. They also put down new roots at stem nodules, helping them spread. Both species produce dense, heavy mats of plant matter, which smother native plants and can even cause tree branches to break. Both vines are Category I invasive plants due to the damage they cause to native systems.
Skunk vine and sewer vine are unpleasant plants to have around, so they’re less likely to be found in yards and gardens than some other invasive vines. They can be very difficult to control. If you pull the vines, make sure to properly bag and dispose of all of the plant matter, since stems and leaves can re-root and grow into new vines. You’ll need to return a few times to make sure that the vine isn’t re-growing from any leftover root matter. Control is easier with an herbicide like glyphosate, but you may have to spray these vines multiple times as they re-sprout so easily from the roots.
Balsam Apple
Balsam apple (Momordica charantia), also known as balsam pear or bitter melon, is the only vine on this list that’s not a category I, but rather a category II invasive plant. This means that although it’s spreading, it hasn’t yet been shown to have the same negative effects on Florida’s ecosystems as category I invasive plants have. We can’t get complacent, though- balsam apple certainly has the potential to become a category I invasive species. It grows quickly, especially in disturbed areas, and creates dense groundcover patches. It’s less dangerous to mature trees, but it can kill shrubs and seedlings, and it's been known to ruin restoration areas by killing planted longleaf pine seedlings. Balsam apple has deeply lobed leaves, yellow flowers, and a distinctive unpleasant odor. Its orange fruits and bright red seeds can be toxic to humans and pets, but are widely dispersed by birds.
If you find balsam apple growing on your fence or in your yard, pulling up the vine by hand is the best way to remove it. It tends to break easily, so tracing the vine to the ground and pulling from the root is a good idea. Balsam apple can also be killed with glyphosate, but it does tend to grow over other plants that you may not want to kill, so spray with caution.
