Mile-a-minute weed has appeared in Maine. This fast-growing invasive species poses a significant threat to plants and trees. Credit: Courtesy of Maine Department of Agriculture, Conservation and Forestry

An invasive weed that spreads so fast you can almost watch it grow has been reported in Maine for the first time.

The Maine Department of Agriculture, Conservation and Forestry on Tuesday verified the discovery of Persicaria perfoliata — commonly known as mile-a-minute weed — at a private residence in Boothbay Harbor. The weed most likely hitched a ride with newly installed landscaping plants delivered to the property.

The invasive weed is one of 33 plants on the state’s “do not sell list” due to the harm it poses to native plants and wildlife, according to the Maine DACF.

As its name implies, mile-a-minute weed grows at an astonishing rate of up to six inches a day or 25 feet in only six weeks.

Left unchecked, it can quickly smother young plants and trees. The state said it’s a significant threat to nurseries, Christmas tree farms, reforestation projects and restoration areas.

The weed was reported by the landowner after he spotted it while cleaning up weeds among new landscaping plants.

“The timely reporting of invasive plants is crucial to our efforts in safeguarding Maine’s natural areas,” said Gary Fish, Maine state horticulturist. “With the public’s support we can respond rapidly and take necessary measures to eradicate any other mile-a-minute weed plants in the area.”

Native to Asia, mile-a-minute weed is a vine that has distinctive triangular leaves, spikes of pea-sized blue fruit and barbs along the stem and leaf margins. It also has circular leaves on the stems beneath each fruit spike.

Anyone who spots a plant resembling mile-a-minute weed can go to the Maine Natural Areas website for identification information. If it matches the description, take a photograph and submit it by email to along with information about where it was spotted. You can also report it by calling 207-287-7545.

Julia Bayly is a reporter at the Bangor Daily News with a regular bi-weekly column. Julia has been a freelance travel writer/photographer since 2000.