Alberta dogs trained to sniff out invasive zebra mussels on boats have been given a new mission.

Hilo, Diesel and Seuss are searching for an elusive plant in Fish Creek Provincial Park.

The perennial herb, called Thesium arvense, is an invasive plant from Europe and Asia that feeds off other plants and kills them. Fish Creek Provincial Park is the only place in Canada it's found.

The plant is small and grows low among tall grass, making it hard for humans to spot, but the dogs can quickly sniff it out.

The weeds' location can then be mapped, and the plants can be pulled out or sprayed.

Mysterious plant

St. Mary's University professor Mary Ann McLean said the plant was first discovered in the park in 2001.

"In Europe and Asia it's not a weed and it's not rare, so nobody writes about it. It's not interesting. So we don't know much about its biology because of that," she said.

"So we've spent the past couple of years trying to figure out some basic biology."

No one knows how the plant got to Alberta or how it spreads, although McLean suspects the seeds may be distributed in the park by ants.

The high-energy dogs needed a job to do between boating seasons, said Cindy Sawchuk, lead of the province's Conservation K-9 program.

"It's late September and boat traffic is winding down," she said.

"We were looking for a target that we could train the dogs in the off season because it's really good to keep them working in the winter time."

With files from Evelyne Asselin