by Jeanne Siviski

Japanese barberry, burning bush and Norway maple, perennial favorites at plant nurseries, are also highly invasive plants that can spread rapidly, choking out native species. They are on the list of thirty-three plants banned from sale in Maine in a ruling that went into effect on January 14, 2017. Prohibition of sales will begin on January 1, 2018.

Specifically, the ruling states that, “No person shall import, export, buy, sell, or intentionally propagate for sale or distribution any living and viable portion of any plant species, which includes all of their cultivars, varieties and hybrids, listed in Section III as invasive, likely invasive or potentially invasive.”

Not all plants brought home from nurseries are intentionally acquired, though. Often considered a “horticultural hitchhiker,” garlic mustard is one of the invasives on the list. Not sold by nurseries, it “catches a ride” by sprouting as a weed in pots of nursery plants. Nancy Olmstead, an Invasive Plant Biologist with the Maine Natural Areas Program, says that garlic mustard is very shade-tolerant and a real problem in floodplain forests as well as upland forests. Olmstead said it is “definitely present’ in the greater Augusta area.

Two additional horticultural hitchhikers on the list are mile-a-minute weed and Japanese stiltgrass. Olmstead says, “Japanese stiltgrass is particularly bad news for the forest, as it is shade-tolerant and can form a thick carpet on the forest floor, interfering with native plant growth. The mile-a-minute weed is less a forest interior plant but very bad on forest edges, landings/roads, etc”. At this point, it is not believed these two plants have arrived in Maine, but both have been found as hitchhikers in New Hampshire. New Hampshire, Massachusetts, Connecticut and Vermont all have rules banning the sale of invasive species.

As to banned plants that have been popular with gardeners, there are native plants which possess qualites similar to those that made the invasives appealing in the first place. The New England Wild Flower Society has created a well-illustrated brochure of invasive plants alongside native alternatives. A table listing the characteristics that originally made invasive plants desirable with comparable native plants was developed by the United States National Arboretum. Additional information about plant alternatives, places to purchase them, the actual ruling and the list of all thirty-three plants named in the ruling can be found by clicking here.

Banning the Sale of Invasive Plants, and a Few Hitchhikers