Racing Mile-A-Minute

Mile-a-Minute weed on Grape Island

NPS Photo

Mile-a-minute is an undeniably cute plant species that grows a dressy little cup-shaped collar at its nodes to complement its stand-out-green, arrowhead-shaped leaves and blushing pink young stems.

It’s lovely – a tough plant to side against aesthetically. But the beauty has made enemies among gardeners, land stewards, and native biodiversity protectors here in New England.

In its native range of east Asia, mile-a-minute, or gangbangui in Chinese, complements native habitats and serves as a source of traditional medicine. Once displaced, however, it causes damage. Here in the Boston Harbor Islands, where mile-a-minute entered the scene in more recent years, the species poses a threat to native coastal shrublands.

Aptly named, mile-a-minute grows tall and fast into crawling vines that cover native woody shrubs like highbush blueberry and bayberry, starving them of sunlight. Its talents for spreading quickly and out-shading its neighbors also enable it to stamp out rare native species vulnerable to local decimation.

Of course, mile-a-minute isn’t the only displaced plant that harms native species on our islands. A handful of other "invasive" species, like glossy buckthorn and privet, also thrive in the Boston Harbor Islands’ moderately shady, moderately sunny coastal shrubland habitats, where they outcompete native plants for space and sunlight. The coastal shrublands act almost like a Goldilocks Zone for plants that come from a variety of places, offering welcoming conditions without demanding too many adaptations, making the shrublands hotspots for aggressive, displaced plants.

NPS Photo

Among its pesty peers, however, mile-a-minute stands out. It’s the star of the summer for the Boston Harbor Islands’ Science and Stewardship team, who intend to eradicate it entirely from Grape Island. That’s a big goal reserved just for mile-a-minute.

It’s possible that land stewards have caught mile-a-minute early, before it has spread from Grape to other islands. Other aggressive displaced plants have already proliferated throughout the Harbor Islands and are now challenging to control. By acting quickly, in this unique case, park stewards have the chance to snuff out mile-a-minute completely rather than merely working to keep it at bay.

The project is intensive – an all-hands-on-deck situation. First, in February and March, stewards apply an herbicide treatment to the soil in spaces where large patches of mile-a-minute had overwhelmed other plants last season. Then, from June to July and maybe early August, after the mile-a-minute has grown tall enough to easily see and handle, stewards follow-up with weeding and more targeted herbicide spraying. Around late July and early August, mile-a-minute goes to seed, and controlling it becomes difficult. The team is racing against the clock to remove the mile-a-minute before then, all for the sake of protecting Grape Island’s lovely, native highbush blueberries and bayberries.

Native blueberries and bayberries are innately important members of Grape Island’s biodiversity and its ecosystem functions. For instance, many species of bird, from resident robins to migrating cedar waxwings rely on the food and shelter of these native shrubs.

By protecting native shrubs against the likes of mile-a-minute, staff, partners, and volunteers alike protect these birds and a whole host of other organisms and ecosystems functions that coastal shrublands support.

Join in the race, connect with land, water, and life on Grape Island, and learn more about ecosystems of the Boston Harbor Islands at our next Stewardship Saturday.

Contributed by: Elle Bernbaum, Biological Science Technician

Additional Source: Maria DeLaundreau, Supervisory Biologist, National Parks of Boston