Chicago bans 14 invasive plants

Invasive plants, with no natural enemies, like to take over -- often at the expense of local habitats and the creatures they support. The City of Chicago is fighting back, banning the sale and possession of 14 plants within city limits that are classified as invasive.

The more prevalent of these banned plants include chocolate vine (Akebia quinata), wild chervil (Anthriscus sylvestris), Oriental bittersweet (Celastrus orbiculatas) and privet (Ligustrum spp).

The list from Chicago's Department of Environment updates the invasive species ordinance that passed in 2007, which made it unlawful to possess 26 aquatic invasive plants and animals.

Many of these intruder plants were brought over from Europe or Asia to be ornamental plants for landscaping. Unfortunately, they thrived a little too well. "[Invasive plants] overtake the natural plants because [there is] no competition and the native wildlife is lost," said Wayne Vanderploeg, the lead forestry ecologist from the Forest Preserve District of Cook County.

Furthermore, once invasives have taken over, removing them is difficult, time-consuming and costly. Vanderploeg estimated that it can cost anywhere from $10,000 to $20,000 per acre from the start of restoration to the complete eradication of an invasive plant. He added that treatments can make it later uninhabitable for the native plants.

An advisory group spanning a wide range of expertise was enlisted to develop the list of banned plants, said Aaron Durnbaugh, deputy commissioner of Chicago's Department of Natural Resources and Water Quality Division. The group included experts in plant ecology from federal, state and local government and private agencies. Farmers, park managers and representatives from garden centers and regional nurseries were also asked to participate.

Elyse Girard, the perennials manager at Gethsemane Garden Center, said that "most of the perennials on this year's list we had already stopped carrying before the ban. We try to limit plants we know have a tendency to be invasive. If we did have one of these it was on a special request from a customer."

Girard said that, for the most part, Gethsemane is unaffected by the ban -- except for chocolate vine, which she said is popular with customers.

The city deliberately chose plants that have not already taken over and/or are not a major threat, with the goal of circumventing future problems. "There are other invasive plants, but they are so abundant that it would be hard for the city to make an impact," Durnbaugh said.

The city also created a list of 43 plants that should be discouraged, but not regulated, either because they are prevalent or already limited by the state.

"The city needs to be commended for this attempt to prevent the spread of invasive plants," Vanderploeg said.

Cities in the Northwest such as Seattle and Portland, Ore., have made similar bans, Durnbaugh said.

Information on the banned and discouraged plants, as well as a list of non-invasive alternatives, can be found at