Published on 04/01/05

Exotic, invasive plants threaten Georgia's forests

By Brad Haire
University of Georgia

Japanese climbing fern climbs plants and chokes them. Cogongrass forms a toxic mat. And they're just two of many foreign plant invaders that threaten Georgia's forests and natural areas.

Cogongrass grows thick foliage about 4 feet high, said Chris Evans, an invasive species and natural resource specialist with the University of Georgia Bugwood Network.

The Bugwood Network is a Web-based system used to collect, promote and distribute educational materials in entomology, forestry and natural resources.

Forming thick clumps and releasing toxins that smother all other plants, cogongrass can hurt natural wildlife and forestry production. "It's considered one of the worst weeds in the world," Evans said.

It's already infested several southwest Georgia counties, including a 20-acre site in Mitchell County. It has caused major problems for some pastures and forests in Mississippi and Florida. "We want to find and suppress it before it becomes a problem in Georgia," he said.

The light fluffy seeds of cogongrass are easily carried by wind. They also catch rides on vehicles. As a result, the plant fills many roadside ditches in Mississippi, he said.

A native of southeast Asia, it was introduced into the Gulf states early last century as packing for cargo shipments. Others later tried it for livestock forage and erosion control.

Japanese climbing fern grows quickly over small trees and shrubs, shades them out and kills them, Evans said. It grows up taller trees, too, where it becomes an easy path for fire to reach treetops.

"Just in the past year," he said, "we're seeing more of it in pine stands in Georgia and natural areas."

The Asian and Australian native has made it hard for some south Georgia pine straw farmers to rake their straw, which they bundle and sell as landscape mulch, he said. Alabama and Florida officials regulate pine straw that enters their states for this fern.

The plant was introduced into the United States in the 1930s as an ornamental. It grows as fast as kudzu. If left unchecked, kudzu can quickly take over a local area. But the Japanese climbing fern can spread faster over greater distances, he said.

It takes time for some invasive species to become problems, he said. A population may be slow to establish. But once it does, it can explode.

Invasive plant species like the Japanese climbing fern and cogongrass may have been introduced decades ago, Evans said, but they could now have the foothold they need to cause ecological and economic damage.

Exotic invasive plants are found in almost every state. Georgia has about 20 major ones, he said.

Many people think some common plants in Georgia are native species, he said, but they're exotic and potentially invasive plants.

Privet, for instance, is a small bush usually found growing under trees. It has white flowers and purple berries and can outcompete native shrubs.

Wisteria is a popular landscape plant that sometimes escapes to become wild and unchecked in wooded areas. Its showy purple blooms can be seen growing on trees along some Georgia roadways in spring.

The Georgia Exotic Pest Plant Council and the Bugwood Network are sponsoring the Invasive Plant Control Workshop April 13 at the UGA Rural Development Center in Tifton, Ga.

Participants will learn how to identify exotic, invasive plant species, find out what measures are being taken to control them and how they can help. For more information, call (229) 386- 3416. Or go to the Web site (

Brad Haire is the former news editor with the University of Georgia College of Agricultural and Environmental Sciences.