The Japanese climbing fern also goes by the name Lygodium Japonicum, which is its scientific name. Some confusion exists as to the difference between Lygodium Japonicum and Lygodium microphyllum. The latter is also an invasive plant that is non-native to the United States. However, it features fewer dissections and lobes than the former. In this article we will talk about how to control Japanese climbing fern.
The Lygodium Japonicum, which we will refer to by its English name, the Japanese Climbing fern, is quite a beautiful plant. For this reason, many people have used it as an ornamental plant in and around their homes. While this elevated the aesthetics of their homes, it contributed to the growth of a problem that cannot seem to go away.
The Japanese climbing fern can grow at a rate of 6.5 centimeters (2,5 inch) each day. Think of how big it would be in a month if left undisturbed!
Japanese climbing fern description
The Japanese climbing fern is a common plant that is native to Asia. Ever since its spread to the United States at the beginning of the twentieth century, it became a popular option for landscaping. Its cultivation started in the southeast and slowly caught on in the other states. As such, you will find that it has a dense population towards the southeastern side.
In Asia, it is a native plant, and its growth is, therefore, at par with that of other species in the region. But in the United States, it is a whole different story, as it is an invasive plant. You will find it in disturbed sites, wetlands, forests, Flatwoods, and other such areas.
As it spreads, it becomes a threat to native species as it alters the conditions to make them conducive for its growth. Plus, it is more competitive than most native species and thus dominates the uptake of water and nutrients from the soil. Native plants are therefore at a disadvantage, and where the Japanese climbing fern establishes itself, other species reduce in number.
Plus, it can alter fire behavior, and in doing so, it threatens the pine straw and timber sectors. With all these disadvantages, it is worrying that the spread of this plant continues to gain pace. If left uncontrolled, this fern could take up almost a third of the United States. It has also spread to other continents such as Africa, where its growth is already a concern.
Identifying a Japanese climbing fern
Given the recent increases in concerns, people are now taking a keener look at this plant, which threatens the ecological system. The Japanese climbing fern is a perennial rhizomatous vine with the ability to climb to heights of thirty meters (100 ft). Can you picture how high that would be?
It attracts landscapers owing to its beautiful features. For one, there are the lacy leaves with fine divides that spread over the vines. As they do so, they create a mat of some kind. Beautiful to the eyes, yes, but bad for the environment. In the winter and cold months, the fronds turn brown. But where the weather is favorable, they are green.
The stem is quite slender, and you would think that breaking it would be easy, but that is not the case. It is wiry and twines around surfaces as it climbs other plants. Its color changes as per its age and the season. It could be green through to red.
The leaves also referred to as the fronds, have triangular shapes, and feature some divisions. They are on opposite sides of the vine, and their appearance depends on the number of divisions in play. Their lengths vary from three to six inches and their widths from two to three inches. The Japanese climbing fern does not produce flowers. Instead, it relies on the release of spores.
Are you worried that you might have this invasive species in your yard? If so, here is what you should look for. First, look at the appearance of the fronds. If they appear wiry, tangled, and twining, then you could have a reason for worry. Next, look at the leaflets. Do they have hair on the undersides? Are they lacy and ferny? If you have answered yes to both these questions, move on to the last step.
Look at the surface beneath the curled leaflet margins. Can you see sporangia? If all these apply to the plants in your yard, you could be dealing with the Japanese climbing fern. It is also possible that you are dealing with the Old World climbing fern, which is just as invasive.
From whence did this species come? Well, the Japanese climbing fern is native to the south, eastern and south-eastern parts of Asia. You will find it in places such as Nepal, Taiwan, China, India, Pakistan, and other such regions in this continent.
It got introduced in the United States and is pretty dominant in at least nine of the states towards the south and southeast. The first report of its sighting placed its location in Southern Georgia, where it was under cultivation. That was in 1903. From that point, reports of plant escapes became the norm, and soon, the vine had spread to other states such as Alabama, South Carolina, and North Florida. By 1938, the plant had spread to North Carolina. And its spread did not stop there, but rather, it took up more pace.
The Risk of Spread
With the Japanese climbing fern, the risk of distribution is quite high. Unlike most invasive plants that get dispersed through seeds, this plant relies on spores. Spores are quite small, and this makes dispersal by wind quite easy, spreading them over large areas. As such, if a plant establishes itself in one area, it will not be long before surrounding places record its sightings.
Where does Japanese climbing fern grow?
In regions where this plant is native, it mostly occupies moist areas. However, it also has a preference for habitats with dry seasons. In regions such as China, Malaysia, and Indonesia, this vine does well in secondary forests. In Japan and the Philippines, you will find it in thickets as well as the edge of the woods. While in Indonesia, it does well in previously volcanic areas.
In the United States, the plant does not seem to be picky as to where it will occupy. Whether the habitat is in a natural state or experiences disturbances, there is a risk of the vine establishing itself. While it prefers moist regions, it is not unlike it to occupy dry regions.
You will find it along water sources such as rivers, lakes, and streams, in forests, low woods, and upland woodlands, in marshes and swamps. Pine plantation owners have had a hard time with this plant as it seems to have a preference for such environments.
Pinpointing a given region and stating that the Japanese climbing fern would do well there is quite tricky in its non-native regions.
How does it grow?
It is a perennial plant. When the weather gets cold, it suffers dieback. Then new fronds grow when the weather gets warmer before they die back when it gets frosty. It is a cycle of some sort.
This climbing vine can reach heights of up to thirty meters. It does so by twining around other vegetation such as shrubs and trees. Japanese climbing fern can also climb dead vegetation.
It is interesting to note that fronds continue growing even when cut. Suppose the front apex gets cut, the bases of the pinnae will support new growth. While this is good for the plant, it is not a good thing for one who plans to deal with the plant through cutting. For the plant, this allows the growth of fronds to reach sunlight in shaded areas. It would not be possible if the plant were to grow from the ground under other vegetation.
This vine grows quite fast, at a rate of about 6.5 centimeters (2,5 inch) each day. In a month, it should be a few centimeters shy of two meters, which is quite remarkable. Its roots serve as storage organs and contribute towards this fast growth.
The Japanese climbing fern is well-adapted to cold weather. Studies show that frost does not affect spores. What’s more, the production of spores takes place throughout the year, where the vine is in a hot region. That would mean that dispersal would be continuous, adding to the spread of this vine. In cold areas, the production takes place for about six months, which is also a lot, considering the ease of spore dispersal.
While other plants die down in the event of a fire, it is not the case with the Japanese climbing fern. When fires and other disturbances take place, they create canopy gaps. And this vine moves in to occupy this newly-found space.
Does it have competitors?
It would be fantastic if some biological agent were to feed on this vine and put an end to this problem, right? Well, there have been a few reports on this. Puccinia lygodii is one such agent. This fungus can feed on up to ninety-five percent of the vine’s foliage.
Scientists have also introduced moths in densely populated areas, in the hope of eradicating these vines. However, testing on these biological agents is yet to come to an end.
How does Japanese climbing fern spread?
Spore production takes place at a high rate. Think about it like this. Spores are small enough to get dispersed by wind over a large area. Plus, the Japanese climbing fern occupies moist areas, making water another means of dispersal. Combine these two dispersal means, and you have covered an extensive area.
This vine is beautiful, so much so that people want to use it in their garden. Its cultivation for ornamental reasons began in the southeastern parts of the United States towards the end of the nineteenth century. From here, other nurseries started introducing the vine to their selection. And slowly, this plant spread from one county to the other.
Sometimes, it was intentional. And at others, it was as a result of confusion in the names. At the time, people thought of the plants as delightful species to have around their homes. But now, the story has taken quite a turn, wouldn’t you think?
Sometimes, spore dispersal takes place accidentally when the spores adhere to surfaces such as timber, cars, and clothes. A good example would be in pine plantations. Where there are infestations of this vine, spores would be on most surfaces, including on the timber. As the harvesting takes place, the spores would attach to clothes and vehicles, getting dispersed as people move about.
Is it useful?
The Japanese climbing fern grows at fast rates and spreads with ease. It would be great if people could get some use out of it. The question is, can they? The answer is yes!
For a long time, this vine has been useful as an ornament. But that is not all that it can do. It also works as a medicine, food, pesticide, and as material for crafts.
Take China as an example. This vine is native to this region and has come in handy in treating renal ailments, colds, kidney stones, and inflammation. In India, people have used it on snakebites as well as to deal with wounds and ulcers. Nepalese have used it as a treatment for wounds and herpes. They also use its juice to treat scabies and boils, amongst other skin conditions.
In the modern-day, a lot of research has gone into the properties of this fern. And it has borne fruits. It turns out that this fern has strong antioxidants, which can prevent the formation of kidney stones.
Away from medicinal benefits, this vine is a Godsend to craft lovers who can use it for binding and weaving. Agriculturally, it works as an insect repellant and a pesticide. And for people looking to expand their palate, this vine is edible.
Threats of Japanese climbing fern
The Japanese climbing fern has wreaked havoc on the economy as well as the environment.
People growing pine trees for commercial use have been especially affected by the invasion of this species. Not only does it occupy gaps in the plantations, but it also competes with pine for nutrients. The health of the latter thus gets affected.
Plantation owners have to resort to the use of chemicals to control Japanese climbing fern. In doing so, they incur about forty to four hundred dollars per acre. That cost is devoid of the expenses that they will incur in maintaining and harvesting the trees. It is a cost that was unexpected and one that east into their profits.
The pine straw industry has also felt the effect of the invasion. When needles fall, people collect them and use them as mulch for landscapes. This industry accounts for millions of dollars each year. But with spore contamination, there have been concerns as to the effect of the transportation of these needles. Moving them from an infested area to a non-infested one leads to the spread of vines. Plus, it threatens the production of wood in the non-infested areas.
What’s more, these vines spread fast and grow high, which gets in the way of viewing as well as hunting wildlife. As such, the vines affect tourism, timber harvesting, and landscape mulching.
The Japanese climbing fern has greatly affected the environment. For one, it has affected light levels. The vine can reach heights of up to thirty meters and form a canopy. In so doing, it limits the amount of light that gets to the vegetation beneath it. This growth also affects fuel levels.
Another major concern with this vine is how it alters fire behavior. In normal circumstances, a forest fire will reach certain heights but cannot reach the canopies. But with tall vines in place, fires can spread to the canopies through the vines. Thus, the effects of fires are much more where ferns are in place.
Also, the vines facilitate the spread of fire to wetland areas. In normal circumstances, the water would be a barrier. But the fire can bypass movement through the water and opt instead to follow the twining vines to the canopy.
Biodiversity is also at risk. When the Japanese climbing fern establishes itself, it competes with native plant species and keeps them from reaching their full potential. For one, it limits the entry of light to the lower levels of the forest. This shading prevents the plants underneath from getting one of the essential requirements for growth – light.
How to control Japanese climbing fern
How can you deal with this plant? It all starts with preventing its spread and growth, where applicable. Where it has already taken root, you can control Japanese climbing fern.
Prevention and Containment
It is possible to keep this vine species from spreading by ensuring that it stays within infested areas. Some counties have regulations that restrict the movement of this fern to other states. In some cases, you cannot plant this fern close to native plants, as given by the existing regulations. If the infestation is in your yard, avoid disturbing the area to prevent the spread of the spores.
Most of the efforts go into controlling the plant from reaching unmanageable numbers. You can do it by limiting movement and using biological and chemical agents.
The more people have access to infested areas, the higher the chances of spreading the spores. Movement to these areas should thus remain limited to avoid disturbances.
Spores often get moved to other areas when they adhere to clothes and cars in infested areas. You cannot keep them from adhering to surfaces, but you can ensure that they will not leave the infested area. Cleaning clothes and machinery used near the vines is an excellent way to go about it.
Some people have tried using fire to deal with the vines, but this has proven not to be an effective method.
Finding a biological agent that can eradicate a plant is often hard. In this case, most of the concerns surround the L. palmatum species. While an agent could work in removing the Japanese climbing fern, it could affect the L. palmatum, which is a native species.
However, there have been strides to deal with the vine. The first moth released into a climbing fern population was unable to establish. The second moth was a success as it is sensitive to cold and will not affect the L. palmatum. The third species was a no-go as it was a threat to the L. palmatum.
Using chemicals on the Japanese climbing fern has proven to be an effective means of eradication. However, it also comes with downsides and considerations.
While glyphosate has worked on these populations, high amounts can affect the growth of other species. A low concentration of this chemical is necessary when targeting an area with native plants. It is best to pull the vines and spray them with chemicals, as this will reduce the damage to native plants. Note that this pulling can also damage native plants, hence the need for caution.
Use the chemicals as advised by the manufacturer to ensure that you do not impact the environment negatively. It also helps to follow up with the treatments every half year or so to keep the vines under control.
Dealing with the Japanese climbing fern is not easy. But with herbicide in one hand and a glove on the other, you can do it! All the best on this journey!
Lygodium Japonicum (Japanese climbing fern) – https://www.cabi.org/isc/datasheet/31783
Invasive Plants of the Eastern United States – https://www.invasive.org/eastern/srs/jcf.html
Weed alert Japanese climbing fern (Lygodium japonicum) – https://myfwc.com/media/3224/invasiveplants-japaneseclimbingfern.pdf
Lygodium japonicum – https://plants.ifas.ufl.edu/plant-directory/lygodium-japonicum/
Biology and control of Japanese climbing fern – https://edis.ifas.ufl.edu/fr280