How Kudzu Works


If kudzu seems ubiquitous, that's because it is.
If kudzu seems ubiquitous, that's because it is.
DKAR Images/Getty Images

If you've ever traveled the highways or country roads of Georgia, Alabama or Mississippi, you've probably seen kudzu -- a rich blanket of leafy vines covering large areas of land, trees and abandoned buildings.

This creeping and climbing vine flourishes in the Southeast region of the U.S. because of the area's humid and hot climate. Kudzu thrives on warm summer temperatures that regularly top 80 degrees Fahrenheit (27 degrees Celsius) and mild winter temperatures that rarely dip below 40 degrees Fahrenheit (-4 degrees Celsius). What's more, the Southeast gets roughly 40 inches (1 meter) of rainfall a year, setting up a proverbial paradise for this perennial plant. As of 2008, kudzu covers more than 7 million acres of the U.S., and you can even spot it as far north as New Jersey and Illinois, as far west as Oregon and as far south as the Florida Keys [source: Southeast Exotic Pest Plant Council].

Kudzu seems to be ubiquitous in the U.S., but this unusual plant isn't a homegrown fellow. It's actually native to Asia. In fact, writings dating back to A.D. 100 trace this hardy member of the legume family to China, Japan and India. It's been used there for centuries as a homeopathic remedy and for other purposes that we'll explore later. Although kudzu grows like a weed throughout the U.S., it's nearly extinct in some parts of China due to deforestation and its widespread popularity as a remedy for a host of minor maladies.

Considering kudzu's origin and reputation, you may be wondering how the plant got to the U.S. in the first place. It made its American debut in 1876 at the Philadelphia Centennial Exposition, where it was touted as an ornamental vine meant to provide shade. Several decades later, the Soil Conservation Service promoted kudzu cultivation as a way to control soil erosion caused by deforestation in the South. The agency paid farmers $8 an acre to plant kudzu in the 1930s and '40s [source: Britton].

Kudzu grows quickly and easily and many swear by its healing virtue, but some landowners in the Southeastern part of the U.S. aren't happy with it living in their backyards. Before we find out why, we need to learn more about how kudzu and how it grows.

How Kudzu Grows

Kudzu flower in bloom.
Kudzu flower in bloom.
© iStockphoto.com/Joe_Potato

Kudzu belongs to the legume family and is related to the pea, soybean, peanut, alfalfa, aster and oat. Interestingly enough, it's also related to the cannabis plant [source: Britton]. A legume is a plant that produces its fruit in the form of a pod. A kudzu's pod blossoms into a tall, purple flower that has a grapelike fragrance. In late summer, the flower turns into brown, flat, hairy-looking pods that contain anywhere from two to 10 seeds. The catch is that only kudzu vines draped over other plants or objects can produce seed pods, because blossoms grow from those hanging vines. An entire cluster produces two or three healthy seeds, but they can germinate even after several years of dormancy [source: Everest].

As any landowner who's dealt with kudzu can tell you, however, this lack of viable seeds doesn't make much difference in the kudzu survival rate. The secret to the plant's durability is in the roots -- they sprout new ones to reproduce very quickly. These root crowns are relentless and have been known to hitchhike in truckloads of fill dirt and take up residency hundreds of miles away. They set up camp right on the soil surface of the ground. From there, these starch roots grow as deep as 12 feet (3.66 meters) and can weigh up to 300 pounds (136 kilograms) [source: Everest]. These roots are rich in carbohydrates and have the unique ability to tap water from deep underground sources, which makes kudzu survive in dry, hot conditions where other plants can't.

At the ground's surface, kudzu vines sprout outward and upward from root crowns. New root crowns sprout every few feet along a vine, attach to the soil and spring yet more root crowns. Meanwhile, vines continue to grow as much as 2 feet (61 centimeters) a day in summer months. Attaching to a tree, pole, fence or building, kudzu can grow up to 80 feet (24 meters) high. That's why some people call it the "mile-a-minute vine."

Kudzu leaves grow in bunches of three and measure 2 to 4 inches (5 to 10 centimeters) in diameter. These leaves twist and turn, depending on the intensity of sunlight that's beaming down, to provide optimal shade for their vines and roots while working their own version of photosynthesis. Photosynthesis is how green plants turn sunlight and water into the energy they use for food.

Alternative Uses for Kudzu

As we learned earlier, kudzu's history begins in ancient Asia. For centuries, people in China, Japan and India have used kudzu for homeopathic remedies for symptoms of heart disease and high blood pressure [source: Drugsite Trust]. It's even been used as an alternative remedy to relieve muscular aches and to treat measles. Herbalists take the root of the plant and boil it to make a starchy powder or solid kudzu root starch. Some make liquid concoctions like ginseng extract or vanilla extract from the root. Yet others make tea from it.

Some studies suggest that kudzu extract can reduce alcohol cravings and others indicate that kudzu can be used to prevent and treat hangovers. In any case, the scientific community has found evidence that kudzu affects alcohol consumption in humans in some form. One study even found that although kudzu didn't deter subjects from drinking, people actually did drink less after ingesting it. Why? People who took kudzu actually got drunker off fewer beers than participants who didn't ingest the plant. Researchers thought that the plant may contain a compound that increases blood alcohol levels in humans and enhances its effects [source: Associated Press].

Kudzu has several uses outside of the medicinal realm. In fact, it's considered a delicacy in many areas. Legend has it that the Chinese ruler Shennong, the "divine farmer" and father of Chinese herbal medicine, tasted each and every herb in the area, including kudzu, and created a book based on his research [source: Dharmananda]. Since then, people have come up with more ways to put kudzu on the menu. Some use it as the main ingredient in a variety of condiments and dishes. In the Southeastern U.S., some people make and sell kudzu blossom jellies and syrups. If there's a way to prepare kudzu, you can bet you'll probably find a recipe for it -- quiche, salad, salsa, candy, soda and tea, just to name a few.

More Kudzu Products

Leave it to the creative and resourceful among us to create even more ways to take something that's just hanging around and turn it into a useful product -- how about kudzu lotion? Along with this green bath and beauty product, you can also find kudzu prominently featured in folk arts and crafts. Artisans can build wall hangings, quilts, sculptures and baskets with handicrafts they've made from kudzu plants. Don't be surprised to find that a house's wall or roof was made with kudzu, either.

You may recall that kudzu was introduced in the U.S. in 1876 as an ornamental vine. It was also promoted as feed for horses and cattle. This makes sense because it's practically free, grows plentifully and seems to appeal to the taste buds of grazing animals. But kudzu's popularity as fodder didn't last very long, because people quickly found that it doesn't hold up well to trampling.

Kudzu may not have gained much traction as a bovine food source, but it may have a future as a source of alternative fuel for automobiles and airplanes. In fact, researchers are exploring it as a form of ethanol. This green, lush plant's roots contain large amounts of carbohydrates that can easily be converted to biofuel. These days, corn and soy are largely used to create biofuel, but some people are concerned that depleted supplies of both due to ethanol production could create a food shortage. In fact, the popularity of corn-based ethanol has already made price swings more volatile, affecting farmers, food manufacturers and even charitable organizations that depend on food donations [source: Ruble]. Proponents of kudzunol say that kudzu is the perfect solution for this dilemma; it grows like a weed and it can meet the demand for fuel for combustible engines -- without jeopardizing food supplies.

Kudzu's Effect on American Ecosystems

Kudzu quickly slithers around this tree to put it in a deadly choke hold.
Kudzu quickly slithers around this tree to put it in a deadly choke hold.
©iStockPhoto.com/rwhite3

People don't call kudzu the plant that ate the South for nothing. As we learned earlier, kudzu grows really fast -- as much as a foot or two (30 or 61 centimeters) each day. Once it forms a blanket over land or trees, light can't get through, so the vast majority of the underlying plants or trees eventually die. Only the hardiest plants can survive the suffocating effects of a kudzu infestation. Considering that, imagine the damage kudzu can do to a food or timber crop. Forest economist Coleman Dangerfield estimates that for every acre of timber that kudzu overtakes, landowners lose $48 per acre per year. Another expert, plant ecologist James Miller, calculates that electricity providers spend $1.5 million per year just to control kudzu and keep it off power lines and utility poles [source: Britton]. That's scary enough, but the weight of kudzu vines can actually uproot trees, elevating the plant from a mere annoyance to an actual source of danger.

As early as 1953, the U.S. government began to ramp up kudzu control efforts. In 1970, it declared kudzu a weed because of the nuisance caused by its relentless growth [source: Southeast Exotic Pest Plant Council]. The problem has only grown since then because of the way that kudzu overtakes and smothers native plants, setting off a chain reaction that undermines ecosystems in the process. It's chilling in its simplicity, actually: Kudzu disrupts the food chain by threatening vegetation that native animals use for food and shelter. What's more, kudzu root systems impact the amount of water in the soil and ultimately, the ecosystem itself. For these reasons, the Invasive Species Specialist Group (ISSG) recently added kudzu to the Global Invasive Species database and they've named it one of the 100 worst alien invasive species on Earth [source: Global Invasive Species Database].

Kudzu Control

What can a farmer, forester or simple landowner do to control kudzu? First, you've got to be persistent and be able to rally a team ready for combat. It's not unlike exterminating insects from your apartment or condo: You'll have to get all neighboring landowners to work together to snuff out a kudzu infestation. For your kudzu control program to succeed, each person must faithfully play his or her part.

Here are a few things you'll want to consider:

  • Size -- how large the infested area is
  • Proximity -- how close the infestation is to the trees, crops or plants you want to keep
  • Future -- whether you have plans for the land that's currently infested
  • [source: Everest]

On kudzu patches younger than 25 years old, three or four years of frequent and continuous mowing and grazing can keep it in check. In Tennessee, some people are using goats to chow down on kudzu in urban and suburban areas. You'll want to get the support and guidance of your local kudzu control program authority; even simple mowing and grazing methods require that you contain the infested area by cutting large vines and fencing it off.

From there, you may have to burn the land and apply a series of herbicides. The herbicide you choose depends on a number of factors, such as where the kudzu is growing, the size of its root crowns and the soil conditions, to name a few. You should consult your local kudzu control or land use authority before even attempting to buy any herbicide, though: Some of them are so toxic that you'll need a special permit to buy and apply any of the stuff -- they contaminate runoff water, streams, rivers, lakes and crops.

When you contact an expert, he or she will work with you to come up with the best way to address your kudzu problem. You may find yourself spraying tall overgrowth with a pressure hose spewing a fancy weed killer. You and your neighbors could end up driving big farm equipment like crop sprayers and dusting large areas of land that's covered with kudzu. Patience is the key: It may take seven to 10 years of repeated spraying, cutting and chopping to resolve your kudzu infestation.

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