Michigan spends millions of dollars a year to fight invasive plants that harm the water, lower fish populations and threaten recreational tourism. Yet despite the potential damage, invasive plants are still brought into the state.

Often, as Bridge Magazine discovered, a purchase is just a click away.

Aquatic plants listed as invasive, and thus illegal, in Michigan are readily available online for home aquariums or ornamental ponds, with limited repercussions for Internet retailers.

“There has been a lot of effort to encourage boaters to clean, drain, and dry their equipment so they’re not inadvertently spreading plants and animals or viruses from one waterbody to the next,” said Jo Latimore, an aquatic ecologist and outreach specialist with Michigan’s Department of Fisheries and Wildlife.

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“But those aren’t the only way that invasive species can be spread in our waters.”

Plants that grow too quickly or broadly are often discarded by residents into local rivers or washed out of decorative ponds into local waterways during heavy rains, Latimore told Bridge Magazine.

Michigan’s Aquatic Nuisance Species Task Force estimates the value of the water garden industry to be $1 billion annually nationwide.

Though popular aquarium plants have popped up in waters across the state over the last several years, the volume of plants brought into the state is unknown, with online sales more difficult to track and regulate.

“The internet is a large place and it changes regularly,” said Erika Jensen, aquatic invasive species program manager for the Great Lakes Commission, a partnership among U.S. states and Canadian provinces within the Great Lakes basin.

“So it can be very hard for those invasive species managers who are interested in this issue to keep up with all of the different websites [that offer] live aquatic organisms for sale that we’re concerned about.”

Complicating matters, different states ban different plants. It may be legal to ship a plant from Tennessee to Florida, but illegal to ship that same plant to Michigan. This can make it complicated for buyers and sellers across state lines to know if the transaction violates state or federal law.

“You can inadvertently end up with something in your aquarium or in your pond that we really don’t want to see escaping out into the waters of Michigan,” Latimore warned.

Consider the European frogbit.

“It’s a cute little plant that people like to put in their aquariums and ponds,” Latimore said.