By Sabri Ben-Achour
Invasive plants can overwhelm a forest or grassland where they don't belong, and that can affect much more than just the scenery.
But at Wheaton park in Maryland, a small army of volunteers is trying to do something about it.
Carole Bergmann is leading her troops through a battlefield
"This was a woods. It came up to here," Bergmann says.
Bergmann is a forest ecologist with Montgomery County, and she's showing a team of volunteers how invasive vines have eaten away the forest.
"The vines started growing and killing of the trees, the trees fell down, the vines moved farther in, and killed more trees, and they moved farther in and little by little your forest gets eaten up," she says. "And we don't really have a lot of forest to waste around here."
Besides eating up forests, invasives choke out food for migrating birds, interfere with the way they build nests, and can obliterate biodiversity.
"People don't realize what they plant in their yard can hop over to a park and become invasive."
Elizabeth Crane is one of the volunteers here today.
They're known as Weed Warriors.
After their training, they'll be allowed to go out on their own to parks and public forests to do battle with enemies like Perilla, Microstegium, and if they're really brave, the dreaded Japanese knotwood.
It's not a war they can completely win, but between the 700 of them throughout the county, they hope to at least hold the invaders at bay.