Those who take on the fight against the weeds must do research, work in the field to eradicate the plants and continually push to inform the public about which plants must go and which can stay - many say this is the most essential and difficult part of the job.

"A lot of people have invasives in their backyards and don't quite realize it," said Nancy Pau, a biologist at the Parker River Nation Wildlife Refuge who works to control invasive plant species. "Not all people know what it looks like or how bad it can be.

"If they see a plant they might not know how invasive it is," she added.

But it is not for a lack of trying. Several groups in the area strive to keep neighbors, local officials and organizations aware of the importance of controlling invasive plants and introducing people to the different plants that move into the area regularly.

This summer alone the Newburyport Gulf of Maine Institute Pepperweed Team has completed seven different tasks that range from contacting refuge neighbors about helping control the spread of invasive plant species to presenting information about the plants to Canadian environmentalists, politicians and policy makers.

Along with that effort, Sara Janson, a local graduate student who had an internship at the refuge this summer, worked for months identifying all the places on the refuge where pepperweed - a multi-stemmed weed that grows as high as 6 feet tall - took root and also cleared 1,000 meters of the plant from the Plum Island Turnpike.

The education of locals of the invasive problems continues at 7 p.m. Thursday at an Invasive Species Summit at the Parker River National Wildlife Refuge.

As part of that summit, officials are inviting civic groups, community groups, homeowners near the marsh and other nonprofit organizations to listen to experts teach about the threat of the invasive species and what is being done to eradicate the problem.

"We want to inform people who can have an impact on these invasive species," Janson said. "We want to educate and empower them to deal with the problem on their own."

Invasive plants are those not native to the area that spread rapidly either through their root systems or through massive seed production. "They can spread far and wide," Janson said.

The most common problem they present is creating a monoculture in the Great Marsh, which means that they take over the land, use up all the nutrients that other plants rely on and disrupt the natural habitat for insects and animals.

"That is a real ecological threat," Janson said.

It is an old problem.

For decades, local biologists and conservationists have been fighting certain grasses and plants like Phragmites that they say threaten to destroy the marsh.

The newest plants, however - Perennial Pepperweed and Japanese Knotweed - are the plants that the groups have been focused on in recent months and years.

John Halloran, a retired Newburyport teacher who is the leader of the city's GOMI Pepperweed Team - which is comprised of local high schoolers - said his group focuses on pepperweed because it is not as well known in the area.

He said just yesterday, for example, he contacted local garden and horticultural clubs and the people he spoke to had never even heard of it.

"It's very important because pepperweed is basically flying under the radar right now," he said of spreading the word on the plant. "Not too many know about pepperweed. It has made a very strong movement in the past five years."

His team speaks to conservation committees in different towns, neighbors of the marsh that have the weed growing in their backyard and others necessary to help fight against it.

"Virtually everyone we talk to about this, it is the first time they've heard about it," Halloran said.

Pau said people in the greater Newburyport region know the dangers of invasive species, but they don't know exactly what to look for all the time.

"I think people generally have a good understanding that invasives are bad," she said. "I think with so many species coming in, they might not be aware of the new species."

Halloran said the pepperweed, for instance, is a pretty little white flower that grows in fields. At first, he said, people enjoy it and think it is a beautiful plant.

"It's sort of a little chameleon in a way," he said.

Janson said even her parents recently discovered pepperweed growing in their backyards and thought it was an attractive new plant when the first saw it.

That needs to stop, she said.

"It's a challenge," Janson said. "I think some people think, 'oh what a pretty flower' but they don't realize that its a danger to local plants and animals."

If you go...

What: Invasive Species Summit

Where: Parker River National Wildlife Refuge Headquarters, Rolfes Lane in Newbury

When: 7 p.m., Thursday

Why: To learn about invasive plants in the region

Who: Nancy Pau, biologist at the refuge; Sara Janson, member of Newburyport GOMI Pepperweed Team; Chris Whittaker, of the refuge.