One of the most damaging invasive plant species in the United States has been found in Maine for the first time.

Japanese Stiltgrass was recently found at a nursery in York County, marking the first time it has been found in the state, the Maine Department of Agriculture, Conservation and Forestry announced Friday. Previously, the closest known locations for stiltgrass were at nurseries in New Hampshire.

Stiltgrass forms dense colonies in sun or shade, invading the forest and forming a thick thatch layer over time. Native trees, shrubs and wildflower seeds have difficulty growing because of the thatch layer, which also raises fire risk.

A staff member from the Department of Agriculture, Conservation and Forestry pulls invasive stiltgrass from the ground at a York County nursery. Photo courtesy of DACF

“We know it was likely this invasive plant would make its way to Maine eventually,” state horticulturist Gary Fish said in a statement. “It is a severely invasive plant with small seeds that can hitchhike on plant root balls, potted plants, soil, gravel or equipment.”

Nancy Olmstead, an invasive plant biologist with the state’s Natural Areas Program, said landowners should search recently disturbed areas for new infestations of stiltgrass.

“It’s imperative to be on the lookout for this plant,” she said. “We have to work together to locate any additional sites and keep stiltgrass from invading Maine’s priceless forests and natural areas.”

Stiltgrass is an annual plant and each stem can produce hundreds to thousands of seeds before dying in the fall. Seeds survive for at least five years in the soil.

Stiltgrass leaves Photo courtesy of DACF

Several features of stiltgrass help distinguish it from other grasses. Leaves of stiltgrass alternate along the stem, are 2 to 4 inches long and a half-inch wide, and have a strip of reflective hairs along the midrib of the leaf’s top surface. The leaf edges and surfaces feel smooth to the touch, unlike native grasses with stiff hairs along the leaf edge.

Stiltgrass trails along the ground, branching from nodes where it produces “stilts,” or roots, to support the new branches. It is shallow-rooted and easy to pull up. Stems can have a reddish tint late in the season.

If people believe they have stiltgrass on their property, they are asked to either map the location with images in the online mapping tool iMapInvasives or send an email with photos and location description to [email protected]


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