Conservation crew works to protect Ozark National Scenic Riverway

Plants imported from Asia 100 years ago still threaten natural Missouri.

ELLINGTON Mo.-Katie Derr peered cautiously into the tangled undergrowth around her, ignoring the persistent whine of mosquito wings in her ears. Backpack straps cut into her shoulders as she ducked beneath a low-hanging vine. Her eyes darted warily left and right.

Then she spotted them: a whole battalion of the enemy was spread out in front of her, almost in range. Her right hand tightened around the grip of her gun. A trickle of sweat slid down the small of her back, sending a chill up her spine. She called for backup.

"I've got a bunch over here!"

Moments later, Bob Gillespie and Scott Kelley took up trailing positions on Derr's left and right flanks. Together, they waded into the fray, guns spitting death. . .

Like most battles, this one played out far from the public eye. The soldiers were workers with the Missouri Department of Conservation.

Derr, a master's student at Iowa State University, is an intern looking to expand her resume. The fair-skinned, 5-foot, 6 ½-inch strawberry blond is getting her wish. She spent the previous work day installing an iron gate to protect endangered Indiana bats at Meramec Caverns. The following day she and her crew would explore Ozark fens looking for new populations of the Hines emerald dragonfly, another endangered species.

Kelley has a wiry frame, a grizzled, close-trimmed beard and a bachelor's degree in art history. He spent years traveling the world as a cameraman for a syndicated hunting and fishing show before deciding to focus his interest in nature elsewhere.

Gillespie, a natural history biologist, is the leader of this search-and-destroy squad. He is a veteran of the plant wars, having worked to eradicate kudzu, fescue, purple loosestrife, Reed's canary grass and a bevy of other invasive exotics in Missouri and Illinois.

All three are lean and buff from days spent hiking through rugged terrain carrying 30-pound backpack sprayers and other gear in all sorts of weather.

The enemy this day was an army of Chinese yam plants that have carved out a beachhead along the banks of Paint Rock Creek in Shannon County. The stakes were high.

"Worst-case scenario," said Gillespie, "in a few years this place could be a solid mat of Chinese yams. They climb right over the top of native plants and shade them out."

In other words, it could be an ecological massacre. The present engagement is limited, but losing this battle could plunge the entire Current River watershed-including the Ozark National Scenic Riverway-into ecological chaos.

The yam's tactics are simple but effective. Instead of producing flowers and seeds, Doscorea oppositifolia spreads by means of aerial tubers, also known as bulbils or propagules. These starchy, raspberry-sized lumps drop to the ground, where they sprout, starting new plants.

Chinese yam is best suited to live along creeks and rivers. When streams rise and wash through yam-infested ground, they pick up propagules and carry them downstream. This method of spread is especially troubling because of Paint Rock Creek's location.

Imagine the banks of the Current River, a national recreational treasure, with no jewel-like wildflowers, no dogwood or sassafras trees, only a dense carpet of clinging vines. That is the future, unless someone intervenes to protect natural Missouri from the onslaught of alien invaders.

The Conservation Department's troops have to be versatile, because the fight against invasive exotic plants has several fronts. Kudzu threatens to smother natural communities in the Bootheel. Purple loosestrife and Reed's canary grass are marching across wetlands, and multiflora rose is rooting out indigenous plants in old fields and on gravel bars.

At Paint Rock Creek, on Current River Conservation Area, the fighting is hand-to-hand. The engagement described above took place July 25 in stifling heat and humidity. The troopers had to traverse minefields of face-level spider webs and artfully camouflaged copperheads and timber rattlesnakes. Their pace is slow and deliberate.

Once located, Chinese yam plants are easy to dispatch. A squirt or two of 4 percent Roundup solution on one leaf is enough to take out an entire plant. The trick is finding them.

"We were in here earlier this year," said Gillespie. "So far we have spent about eight man hours spraying. When we started, there were thousands of plants. Most of the larger ones are dead or dying now, but we still have a lot of work to do."

Chinese yam plants came to the United States during the Victorian era, when Americans' increasing leisure time allowed them to indulge their interest in exotic plants. The Chinese yam was hardy, it had an edible root, and it produced showy white flowers that smelled of cinnamon.

The Conservation Department knows of four places in Missouri with Chinese yam infestations. The site of the original Paint Rock Creek infestation is near an unstaffed Conservation Department shooting range. The spot once was a thriving community where someone had a garden with Chinese yam plants. The community vanished without a trace, but the yams persist. One hundred years later, they continue to drop little ecological bombs into Paint Rock Creek.

The July 25 patrol was a mopping-up operation. The crew gave a few previously treated plants still clinging to life a chemical coup de grace, but most of their attention was directed at sprouting propagules. Spotting plants consisting of only one leaf among a riot of similar native plants takes experience.

"There's a lot of plants that look like it," said Derr as she walked along spraying, "but you get really good at picking out the yam plants (pfft-pfft). It's almost like stalking an elusive beast. There's one of the little devils (pfft-pfft). This could be several plants (pfft-pfft), or just branches from one central vine. It hides so well."

Kelley was more succinct as he scanned the forest floor, squirting brief bursts of herbicide onto selected leaves. "Die, die, die," he intoned softly.

Working conditions were awful. The forecast called for a high temperature near 100 degrees, and by the time the crew set to work around 11 a.m. the sky had the chalky blue color that signals high humidity. Within 30 minutes of leaving their truck, all three were drenched with perspiration. Even the rocks in the dry creek bed were sweating.

Pauses to mop brows were frequent. Kelly had to stop periodically to empty accumulated perspiration from the yellow rubber gloves he wore to protect his skin from herbicide.

The day's work began 2.5 miles upstream from Paint Rock Creek's mouth. The farther downstream toward the Current River the crew went, the fewer Chinese yam sprouts they found. Gillespie said this was encouraging. The Conservation Department may be able to eradicate the yam population because it is isolated.

"This would be a lot tougher if there was a source of propagules on private land where the owner wouldn't let us spray," said Gillespie. "The limited size of the infested area helps, too. It's just in this little creek, not spread across a huge river bottom."

Furthermore, he said, most of the plants on Paint Rock Creek still are small. A mature infestation smothers shrubs and small trees and breaks off low branches of taller trees. The number of propagules from such established infestations is enormous.

If eradication is possible at Paint Rock Creek, it will take a long time. Even after locating and spraying all the plants, the Conservation Department will have to check the site repeatedly throughout the growing season for at least five years. Then monitoring can drop back to every other year for 10 years. If no yam plants are found after that time, the population will be considered eradicated.

However, Gillespie worries that the effort might be too late.

"Because the plant has been here for such a long time, my fear is that yam has already dispersed from this drainage and is established on the Current River. I have seen this in past dealings with this plant in similar streams. We need to look beyond this original site to be sure others aren't developing downstream."

A study of costs of exotic species published in the January 2000 issue of BioScience magazine said that damage from non-indigenous species in the United States alone exceeds $137 billion annually. This did not include ecological or aesthetic costs.

To see illustrations of Chinese yam plants, visit
http://www.ill-inps.org/index_page0032.htm.  For more information about invasive exotic plants and animals in Missouri, visit http://www.mdc.mo.gov/nathis/exotic/. 

- Jim Low -

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