South Carolina has no formal list of the state's worst invasive or non-native plants and animals, but there's no question they take a toll.
That's why The Post and Courier reached out to experts at Clemson and the University of Georgia, as well as the S.C. Department of Natural Resources, to try to come up with a list of the ones that do the most damage to the state's environment and its economy.
It proved to be a complicated, subjective question, not unlike ranking which undefeated football team is better than other undefeated teams.
For instance, Japanese honeysuckle, Chinese privet, bush honeysuckles and a few other invasive plants have been reported in all of South Carolina's 46 counties, but none were cited among experts' top concerns as far as damage goes.
Sherry Aultman with Clemson University's Department of Plant Industry said it was difficult to choose only five.
"Do you place more value on a cotton crop versus a peach crop? Is that really fair?" she asked. "Then you get into a situation where it's really hard to calculate the loss of recreational activity because the trees in a state park are dead. How do you really quantify that?"
But with all that in mind, what follows is a list of five of South Carolina's most invasive headaches:
The only critter on the list, feral hogs were brought to this state by some of its earliest settlers and used to exist in stable populations among the Coastal Plain.
But they have caused extensive damage to upland and wetland habitats that are home to threatened and endangered species, said Sam Chappelear of DNR.
These hogs also compete for the same food sources as native wildlife populations do. Prolific breeding and illegal movement by humans has caused unnatural expansion in many areas of the state where feral hogs were not historically located. In 1980, 28 counties reported wild hogs. Two years ago, all of them did.
A 2011 DNR report dubbed them "the greatest wildlife damage management challenge of the next decade," one that could lead to tens of millions of dollars -if not hundreds of millions of dollars -of damage to the state each year.
It's a problem by no means unique to South Carolina. A recent Time magazine article quoted wildlife expert Billy Higginbotham of Texas A&M: "There are but two kinds of landowners in Texas: those with wild pigs and those who are about to have wild pigs."
This species is considered highly invasive and is being found in a few locations in the state. It can form a monoculture that wipes out other native plants beneficial to wildlife.
The grass was introduced here in the early 1900s from Southeast Asia for wildlife forage and erosion control and accidentally through packing material.
Aultman said the biggest infestation currently being treated is in Hampton County, but Aiken, Charleston, Beaufort, Dorchester, Colleton and Williamsburg are among the counties with sites that were treated and are still being monitored. "It's just scattered all over," she said.
The grass leaf blades contain silica - finely serrated margins that make it unpalatable to wildlife. She said it also burns easily and at high temperatures, presenting a fire hazard on roadsides and in areas managed by fire.
Some regions in Alabama and Florida have been completely overrun and eradication is improbable, Aultman said. South Carolina put together a task force for cogon grass early detection and rapid response that has reduced the weed to only six active sites in the state, making control a more attainable goal.
This well-known and pretty well-established aquatic invasive species is all over Lakes Marion and Moultrie and can be found in the Goose Creek Reservoir, too.
The submerged weed produces dense mats via thousands of tubers and fragments of stem and root. Its infestations have been linked with a blue green alga that causes a neurological disease and lethal brain lesions in waterfowl and raptors, particularly coots and bald eagles.
Aultman said hydrilla and crested floating heart are similar lake weeds, though hydrilla has been around longer in South Carolina.
The public can help land managers to control both species by not transporting plant material between rivers and lakes.
The hemlock woolly adelgid is an insect pest causing the destruction of eastern hemlock and Carolina hemlock.
Unfortunately, the bug has been busy, and the hemlocks - which grow in the mountainous, western part of the state - are mostly gone.
"At this point, we as a department aren't even dealing with it anymore," Aultman said. "We consider it one of those that are too far gone. ... Basically, they eat until the trees die. They tend to die out because there are nothing else to feed on. Their populations have plummeted a little bit because there are no hemlocks left."
Actually, Aultman said she still has a hemlock in her yard, and other scattered trees survive. But their numbers are nowhere near what they once were. She said the loss of these trees has far-reaching consequences, including impacts on the carbon cycle and acidity levels in forests and watersheds.
This common reed is found in brackish environments and can outcompete native vegetation, potentially creating a monoculture of this single plant for hundreds of acres and eliminating wetland areas from use by wildlife because of its tall, thick strands.
What's worse, Chappelear said, is treatment is expensive and often unsuccessful. It takes repeat applications to make any headway.
"That's becoming a huge problem down on the coast, and it's working its way in," Aultman added. "It's a bad plant."
Phragmites are located mostly in the state's lower coastal plains, and its identification is made more difficult because the invasive is actually the same species as native common reed.
Reach Robert Behre at 937-5771.