Have You Seen These Plants?

Have You Seen These Plants?

Wanted for crimes against nature. State horticulturalist Gary Fish on the state’s newest horticultural outlaws (and a warning label for beach roses).

beach roses at Portland Head Light

ABOVE Beach roses, which have been given the ominous designation, “Invasive Terrestrial Plant of Special Concern.” Photograph by Benjamin Williamson. 


From the October 2022 issue of Down East magazine

Come the new year, Mainers will no longer be able to purchase European mountain ash, a popular red-berried ornamental; creeping Charlie, commonly substituted for lawn grass; or shrubs such as border privet, Christmasberry, and dwarf honeysuckle. They’re among 30 invasive plants the Maine Department of Agriculture, Conservation and Forestry recently added to its Do Not Sell list — started in 2018 with 33 prohibited varieties — on account of the threats they pose to native species. Although invasives have long taken root in Maine, warming temps have created newly hospitable conditions for some types to thrive, says state horticulturalist Gary Fish, who coordinates the committee responsible for the bans. Currently, the group is monitoring an additional 29 plants for possible inclusion on the next list, due out in 2030. Meanwhile, rosa rugosas — everyone’s favorite beach roses — have been given the ominous designation, “Invasive Terrestrial Plant of Special Concern.”

Maine state horticulturalist Gary Fish
State horticulturalist Gary Fish

How does a plant get on the Do Not Sell list?

Our committee receives recommendations from the [DACF’s] Maine Natural Areas Program and the Regional Invasive Species and Climate Change Network. The public can also suggest plants on the DACF’s website. We work through the list, guided by state rules that define an invasive plant as one that is not native to the state, has spread or is likely to spread into minimally managed plant habitats, and causes economic or environmental harm by developing self-sustaining populations that dominate or disrupt native species. For the new list, we started with 173 nominations, three of which came from the public. I believe all three made it onto the final list.

asiatic bittersweet

coltsfoot flowers

hardy kiwi

fuki, aka butterbur

ABOVE Asiatic bittersweet; coltsfoot flowers; hardy kiwi; fuki (aka butterbur). 

What are some of the worst offenders?

Russian olive trees invade pastures and hay fields. Coltsfoot, a yellow-flowered perennial, blankets areas and smothers pollinating plants. And Callery pear trees take over rural areas, excluding natives that are then over-grazed by deer that won’t eat the pear. They’re so invasive that Kentucky and North and South Carolina have placed a bounty on them.

Why the sinister new label for rosa rugosas?

The committee couldn’t come to consensus on whether it’s invasive throughout the state, although it is on coastal islands and sand dunes where it pushes out native plants and endangers local animals and insects. So for the moment, we’re requiring that nurseries label it as “Invasive Terrestrial Plant Species of Special Concern” and that shoppers be told that it’s inappropriate for planting near the coast. We suggest planting Carolina or Virginia roses instead.

common reed

common valerian

Japanese barberry

bull thistle

autumn olive

ABOVE Common reed, common valerian, Japanese barberry, bull thistle, and autumn olive.

How should gardeners deal with invasives in their yards?

Our list doesn’t require removal from private land. Folks who want to get rid of invasives should first plan what they’ll use to replace them. You don’t want to plant another invasive species or leave a fallow area for invasives to colonize. Remove plants before they go to seed and leave them out to dry and die before disposing of them on-site. If that’s not feasible, double bag everything in contractor trash bags and take them to the dump for incineration. I’ve seen success replacing invasive barberry with red chokeberry or highbush blueberry; Norway maples with red or sugar maples; and crimson king maples with copper beech trees. Around the holidays, winterberry is a great replacement for bittersweet.