Kudzu Has Outsmarted Us

Guest post by Patricia Chan, a freshman in 2014 Byrne seminar on weedy plants

Let me tell you about Pueraria montana var. lobata —it is a crazy, crazy, invasive weed.  This plant, commonly known as Kudzu, but also known as Japanese arrowroot, is a plant in the pea family, Fabacaeae.  You may be thinking: “it’s related to the pea, I guess it probably climbs” (ok you probably didn’t think that, but bear with me).  Well if you were thinking that, you are more than right.  Kudzu is an aggressive and skillful climber, much to the dismay of property owners of the southern United States. But before I tell you about this insane plant, let’s discuss how to recognize it in the wild.

CC Gsmith 

If you happen to stroll around anywhere in the southeast US and encounter a large green mass where there probably shouldn’t be one  - Congratulations!  You have found Kudzu. Kudzu is a very distinguishable plant from afar due to its tendency to cover large areas.   Up close, it may be slightly harder to recognize.  It’s got compound trifoliate leaves (meaning it has three leaflets on one stem) with a varying number of lobes on each leaflet from 1-3 lobes.  The leaves are fuzzy by the way, like a rabbit.  Like a very small, green, coarse, leaf-shaped rabbit…  The long vines cling to surfaces with little brown bristles that it uses to grapple over trees and buildings.  The flowers are a lovely deep pinkish purple hue and grow in clusters.  That’s nice.

photo by Peggy Greb, public domain 

Anyway, now that you know how to point out Kudzu when you see it, let’s learn more about how it behaves.  Kudzu has a very aggressive growing habit; in the right conditions, it can grow up to one foot per vine a day.  Monstrous.  People have reported losing entire cars to masses of Kudzu because they were parked for a few days.  How crazy is that?  In nature, Kudzu is considered a nuisance because it can envelop entire trees in short periods of time, killing forests by crowding out the light.  What a horrible plant to bring places, one may assume.

With that in mind, how did Kudzu even get here, not being native to this continent?  Maybe by a shipping mistake or a tourist?   No, in fact, Kudzu was brought to this country intentionally from Asia for ornamental and erosion prevention purposes.  That’s right, us humans spread this plant ourselves.  The sad truth is that we didn’t do the research we should have to ensure that this plant didn’t damage our ecosystems the way it did.  We just brought it over on a hypothesis and a whim.

This just goes to show: it’s wise not to mess with the natural order of things.  Not to say that it’s impossible to introduce a foreign species successfully, but a lot of heavy research must be done before it happens to make sure a monster isn’t unleashed.  All in all, Kudzu isn’t actually a wholly evil plant.  It carries medicinal purposes, has beautiful flowers, and it really does prevent erosion.  And in the end, it only behaves the way it because these characteristics have helped it to survive and reproduce in the past.  Kudzu acts to survive, and it just so happens that it is really good at doing that in the US.  What we need to do, however, is be more careful to monitor this kind of thing when considering what exotic plants to put where.  We need to be smart in our ecological decisions.

The good side of an invasive

クズ (Kudzu) 

The non-native species Pueraria lobata, commonly known as kudzu (or sometimes mile-a-minute weed, but it is not the same plant as in this blogpost), is a creeping, climbing legume vine from japan and china. “Kudzu” literally means ‘plant’ in Japanese. Like most invasive species, kudzu is considered a noxious weed in our part of the world. The ecological damage caused by this plant is solely due to its ability to out-compete neighboring species for resources such as light. As it grows over other plants, its large leaves blocks sunlight and often plants beneath the kudzu are suffocated. 

"The Vine that ate the south." Kudzu invasion in forest.
Creative Commons image by Frank DiBona on Flickr.

In its home countries, however, it has proven to be a herbal remedy for a variety of troubles such as hair loss and alcoholism. Such two-sided traits beautifully sum up the contradiction of invasive species. Though malicious in some environments, invasive species can be used to our benefit in other area. As seen in our last post about invasives, significant efforts have been put in to mitigate these weeds. However, recent research has shown that some of their characteristics could be beneficial to society.

History
How did kudzu get here? In 1876, during the US’ 100^th birthday exposition in Philadelphia, the Japanese government constructed a native Japanese garden for the exhibit. The imagery of the leaves appealed to many American gardeners leading to the vast spread of kudzu in local gardens as ornamental plants from a Florida nursery that propagated and sold the plant. Kudzu was also actively promoted as a forage plant and soil conservation plant in the US during 1930s and 1940s. But it didn’t stay in gardens and on roadsides, it quickly escaped and took over the native forest. 

In addition to this, the US Armed Forces used kudzu as camouflage for equipment in Vanuatu and Fiji in the Pacific. Needless to say, the plant has become classified as an “unwanted organism” in these countries too.
           
The root, flower and leaf from kudzu are used to make herbal medicines. In Traditional Chinese medicine, the use of natural resources is the norm. In fact, the use of herbal-based medication is still a leading treatment for disease in many areas of the world. Kudzu is noted to have been used in Chinese medicine before 600 AD. Its uses range from treatments of menopause symptoms, muscle pain, stomach pain, fever, diarrhea, sinus infections, high blood pressure, to irregular heartbeat, chest pain and various other illnesses.

This medicine features the roots and flowers of the Kudzu plant, which aims to lessen the desire and craving for alcohol. In addition it aids the body's natural detoxification processes. Source: vitaminshoppe.com

Research
Despite its popularity on the Asian continent, the herbal remedy from kudzu has so far lacked sufficient scientific evidence to prove any effects. So can this weed actually help the medical world?

Kudzu promises a remedy for an illness of much importance to society. It has been used to “cure” alcoholism, or more accurately, decrease the symptoms of drinking and the urge to do so. In 2012 Penetar et al published a study conducted at McLean (a hospital affiliated with Harvard University) on kudzu’s effects on alcohol consumption. It was found that physiologically, kudzu can increase the blood flow to the brain and heart. “Wherever blood goes, alcohol goes”, states professor Scott Lukas on the research team. The theory is that this allows for a quicker response time, and the ability for the body to have enough alcohol in less time. Simply put, you get drunk faster on less alcohol. 

First tested on rodents, the intake of alcohol decreased significantly in the lab results when they were given kudzu. When tested on humans, the group treated with kudzu drank significantly less than the placebo group. The research states that alcohol consumption was almost cut in half!  

More research into the how’s and why’s of such effects could lead to very improtant discoveries regarding potential contributions of this invasive species to medicine. 

Check out an old poem written on this historic weed!