What Is the Special Adaptation That Helped the Kudzu Survive?
Kudzu (Pueraria lobata) is a perennial vine from China that is extremely invasive in the southeastern United States. It can grow in U.S. Department of Agriculture plant hardiness zones 5 through 10, though it is most seriously invasive in regions of the Southeast that fall in zones 7 through 9. Kudzu is in the legume family and has large green leaves and fragrant purple flowers.
Few plants grow as fast as kudzu. It can put on 1 foot of growth per day and up to 100 feet of growth in a season, clambering over trees, cars, houses or anything else in its path. Though it is dormant in winter, the energy produced by the rampant vines is stored in a massive root system that sprouts with vigor each spring. The giant taproots can be 12 inches in diameter and weigh up to 400 pounds.
Not only does kudzu grow fast but it also is tolerant of a wide range of environmental factors that allow it to survive and adapt in harsh conditions. It is shade-tolerant and often takes root in the deep shade of the forest where little else grows, twining up the trunks of trees and eventually overcoming them. It grows well in extremely dry, hot, rocky locations like the exposed soil left at construction sites. Wet clay soils are equally favorable to this remarkably adaptable species.
Incredibly, kudzu was intentionally introduced to the United States and planted on millions of acres in the Southeast in the 1930s and 1940s. It was touted as a soil-building crop to help regenerate the degraded lands depleted by the cultivation methods of the cotton industry. The plant does enrich the soil and is a very nutritious feed for livestock, but the invasive potential of the species was not recognized until it was too late. The assistance of humans in establishing kudzu is one of the primary factors that has lead to its dominance in the landscape.
Resistant to Eradication
Kudzu is extremely difficult to eradicate in the landscape, largely due to the size and persistence of its massive root system. Chemical herbicides kill the leaves on contact, but the woody vines resprout immediately and require constant reapplication to be effective. Mechanical means are costly and not very effective. The mass of long, twining vines clogs mowers and other equipment and makes it a very slow process. As with herbicides, mechanical clearing must be repeated with vigilance until all regrowth has ceased.