Expert delves into Saskatchewan's centuries-long history of invasive species

·3 min read

Invasive species have been threatening Saskatchewan's natural environment for hundreds of years.

Many, like the common tansy, were brought into the province because they had uses.

The common tansy was used for beauty treatments, intestinal issues, in embalming and as an insect repellant, said Shauna Lehmann, who is with the Saskatchewan Invasive Species Council.

But the plant can also be quite toxic to humans and animals in certain quantities, Lehmann told The Morning Edition's Stefani Langenegger.

Lehmann will be giving an online presentation on Jan. 18 that delves into the history of these invasive species in Saskatchewan.

"A lot of the invasive species had come in the early 1800s from Europe and Asia," she said. "Things like the leafy spurge and thistles that we're seeing in agricultural areas.

"A lot of the troublesome ones that we're starting to see are things that were brought in for ornamental reasons or medicinal reasons, cultural and culinary reasons. So things like flowering rush or Prussian carp that we're starting to see in our waterways and some of the harmful ones like wild parsnip or even common tansy."


The root of wild parsnip was used as food at one time, but the top of the plant can be quite dangerous to your skin if you touch it, Lehmann said.

Prussian carp, which can now be found in Wascana Creek, are native to Asia and was likely introduced as a food fish.

"It's not necessarily the type of food we want to eat here just because it is quite bony, but it was used for food and it may have also been released for cultural practices."

Other invasive species brought into the province include kochia plants, dandelion, garlic mustard weed (which is prohibited in the Sask.) and koi fish.

"The ones that were brought in for culinary reasons or for medicinal reasons can still be used the way that they were intended," Lehmann said. "But we generally don't like to encourage people to plant them or to release them into the natural environment here just because they're not suited to our environment and can actually be quite dangerous. "

George Chernilevsky
George Chernilevsky

She said they can cause a lot of damage to the habitat and also have economic consequences.

"Invasive species in general will out-compete some of the native species that are here and take over and cause disruptions that really aren't handled well by our environment," Lehmann said.

"Some of the agricultural weeds can cause huge losses in the economy and can choke out beneficial habitat for animals. Some can also be harmful to our health."

She said the best way at stopping invasive species is prevention.

"If you have them in your gardens or if you see them in other areas just make sure not to release them elsewhere, that's kind of the key," Lehmann said.

"There are also a lot of different techniques, either using herbicides or using different mowing practices and cultural methods to get rid of them."

Iowa Parks Foundation
Iowa Parks Foundation

The Invasive Species Council can provide information on how to target certain species.

Invasive species that are already widespread like the leafy spurge and thistles can't be completely eradicated, so it is just about trying to control their spread.

"But some of the newer ones that we're seeing like Prussian carp and some of the zebra mussels and things like that coming in, we do have an opportunity to prevent them from moving further," Lehmann said.

Nature Conservancy of Canada
Nature Conservancy of Canada

She said people should be aware of what they might be bringing into their gardens or aquariums so they can protect the environment from them.

Lehmann's presentation about invasive species and their cultural, culinary and medicinal history will be held Jan. 18 at 6 p.m. on Zoom.