30 Species Added to List of Invasive Plants that are Illegal to Sell in Maine

In addition to the 33 plants that were made illegal to sell more than three years ago, the state has now added 30 species to the list of plants that will no longer be allowed to be sold in Maine as of January 2024. The plants are prohibited from sale because they are invasive, which means they spread quickly and squelch the growth of local species.

The spread of this second group of species will be tracked until, roughly five years from now when the Terrestrial Invasive Plant Stakeholder Committee starts debating again which new plants to add to the prohibited list.

Imported into US Soil

Rugosa rose, a fragrant beach rose that is common throughout Maine but is more common along the coast, is now classified as an "Invasive Terrestrial Plant of Special Concern" under the new regulations.

All of the new plants on the list were imported into the country because, at one point, a plant dealer decided they would look nice in a garden. Some of the 33 original plants unintentionally made their way to America; for instance, weeds that were growing in pots were brought over for sale.

Although many of the plants on the list are no longer offered by neighborhood nurseries, they are still available online, according to state horticulturist Gary Fish, who oversees the committee. If everything goes as planned, Mainers won't be able to purchase these plants online either in the future. Although American online retailers like Amazon have been trying to abide by Maine's prohibited list, Fish claimed that it has been more challenging to enforce the ban on European plant vendors.

Callery Pear

The Callery, or "Bradford" pear, a decorative tree with a profusion of white blossoms, was, as expected, included on the list. The ornamental tree was created from an Asian tree that was initially believed to be sterile. Domestic plantings in private gardens, public parks, and along streets allowed it to disperse by seed into the wild. Now, there are more wild Callery pear tree stands in states to our south as well as in southern Maine. Experts predict that the tree will become more problematic in Maine as temperatures rise.

Another native of Asia, Wintercreeper, has gotten out of people's gardens and into the wild, especially along rivers. According to Fish, a sizable patch is expanding under a bridge in Augusta that crosses the Kennebec. Gardeners shouldn't be overly concerned about the impending ban as there won't be a significant gap left in anyone's garden as many cultivars, including the one that is most frequently seen, "Emerald Gaiety," are still sold in many nurseries.

According to Fish, creeping Charlie, a plant native to the British Isles, has been used as a ground cover for a very long time. As of right now, it is also prohibited.

The new list includes European alder, which has spread from gardens to Maine's wild areas. According to Fish, homeowners frequently intend to buy native alders but accidentally buy the wrong ones. That won't take place with the ban.

Read also: Scientists Turn to Lab-Raised Killer Bugs to Stop Invasive Species From Wreaking Havoc 

 Rugosa Rose

The Rugosa rose, a native to Asia, was one of 63 plants on the committee's preliminary list of plants it considered for ban late last year.

The committee ultimately decided on the following compromise: Nurseries will still be permitted to sell rugosa roses, but a label will be necessary, either on the container, in the soil, or in the area of the store where the roses are for sale. The seller must inform the buyer about inappropriate habitats for rugosa roses and it must say "Invasive Terrestrial Plant Species of Special Concern."

Rugosa roses, also known as "beach roses" due to their profusion on beaches, shouldn't be planted there. Rugosa roses are extremely invasive near bodies of water; the rose hips, the red, Ping-Pong-ball-sized fruit that develops after flowering, can float far away from the original plant and possibly even travel miles. Rugosa roses, however, are not a significant issue if they are grown inland, far from the sea, lakes, or streams, according to Fish.

He went on to say that the beach rose is unique in another way. A cultivar created with an invasive species as one of its parent plants is prohibited by the invasive species law, but that won't apply to rosa rugosa. Since it has been a component of so many hybrids for such a long time, it would be impossible to enforce such a rule.

The initial list of popular species that were subject to a potential ban has been replaced with a watch list. They include well-known plants like Japanese spirea, Japanese tree lilac, hardy kiwi, and Buddleia davidii, also known as butterfly bush. These plants are currently granted a five-year reprieve, Portland Press Herald reports.

Vinca, which was originally on the prohibited list, didn't even make the watch list, but it'll likely be brought up again in five years. Vinca is a "colonizer," according to Fish, as it spreads by roots as opposed to seeds over great distances.

Related article: Common Reed: Researchers May Have Uncovered Some Mysteries Surrounding This Invasive Plant