Invasive Plants

Barberry an example of an invasive plant.

Rules

The Maine Department of Agriculture, Conservation and Forestry rules, Ch 273, Criteria for Listing Invasive Terrestrial Plants (DOC), prohibits the sale of 33 terrestrial plant species determined to meet the invasive plant criteria described in the rule. The rule went into effect on January 14, 2017 and the prohibition of sales began on January 1, 2018.

The final section of Ch 273 prescribes a five-year review of the listed species. In 2021 the Horticulture Program began the review process by assembling a stakeholder committee that is assisting in reviewing the rule and any proposed species to add or remove from the list. More Information

Questions?: Call Gary Fish 207-287-7545 or email gary.fish@maine.gov

Plant List

Plants listed below are illegal to import, export, buy, sell or intentionally propagate for sale or distribution. The ban includes all cultivars, varieties and hybrids of these plants.

Terrestrial Invasive Plant List (PDF 139KB)

Terrestrial Invasive Plant Poster (PDF 4MB) Full size printer versions (PDF 26MB) (PUB 79MB) Large files.

Species links go to fact sheets that help with identifcation and control.

Scientific Name Common Name
Acer ginnala Amur maple
Acer platanoides Norway Maple
Aegopodium podagraria Bishop's Weed
Ailanthus altissima Tree of Heaven
Alliaria petiolata Garlic Mustard
Amorpha fruticosa False Indigo
Ampelopsis glandulosa Porcelainberry
Artemisia vulgaris Common Mugwort
Berberis thunbergii Japanese Barberry
Berberis vulgaris Common Barberry
Celastrus orbiculatus Asiatic Bittersweet
Elaeagnus umbellata Autumn Olive
Euonymus alatus Winged Euonymus
Euphorbia cyparissias Cypress Spurge
Fallopia baldschuanica Chinese Bindweed
Fallopia japonica Japanese Knotweed
Frangula alnus Glossy Buckthorn
Hesperis matronalis Dame's Rocket
Impatiens glandulifera Ornamental Jewelweed
Iris pseudacorus Yellow Iris
Ligustrum vulgare Common Privet
Lonicera japonica Japanese Honeysuckle
Lonicera maackii Amur or Bush Honeysuckle
Lonicera morrowii Morrow's Honeysuckle
Lonicera tatarica Tatarian Honeysuckle
Lythrum salicaria Purple Loosestrife
Microstegium vimineum Japanese Stilt Grass
Paulownia tomentosa Paulownia
Persicaria perfoliata Mile-a-Minute Weed
Phellodendron amurense Amur Cork Tree
Populus alba White Cottonwood
Robinia pseudoacacia Black Locust
Rosa multiflora Multiflora Rose

Alternatives to Invasive Plants

What are invasive plants?

In Maine a plant is considered invasive if it:

  1. is not native to Maine
  2. has spread (or has the potential to spread) into minimally managed plant communities (habitats)
  3. causes economic or environmental harm by developing self-sustaining populations that are dominant or disruptive to native species

Invasive plants are a direct threat to what we value about Maine's natural and working landscapes. The aggressive growth of invasive plants increases costs for agriculture, can affect forest regeneration, threatens our recreational experiences, and reduces the value of habitats for mammals, birds and pollinators. Species like Japanese barberry and multiflora rose can form thorny, impenetrable thickets in forests and agricultural fields.

Invasive species are the second-greatest threat to global biodiversity after loss of habitat. Invading plants out compete native species by hogging sunlight, water, nutrients, and space. They change animal habitat by eliminating native foods, altering cover, and destroying nesting opportunities. Some invaders are so aggressive they leave no room for our natives.

Invasive Plant Rule Review

When Chapter 273, Criteria for Listing Invasive Terrestrial Plants was adopted in January 2017, the final section of the rule prescribed a five-year review of the listed species. 2021 begins that fifth year and to begin the review process the DACF Horticulture Program has assembled a stakeholder committee that will assist in reviewing the rule and any proposed species to add or remove from the list.

The stakeholder committee is comprised of a variety of individuals from industry, government, non-profit and educational institutions that represent different organizations affected by the development, implementation and enforcement of the prohibited plant list.

The stakeholder committee and the groups they represent are:

  • President of the Maine Landscape and Nursery Association: Ryan Russel, Land Plans Inc.
  • Representative from a production nursery: Jake Pierson, Pierson Nurseries
  • Representative from a retail nursery: Randy Martin, The King's Gardener
  • Representative from a land trust/land management community: Amy Soper, 7 Lakes Alliance
  • Representative from the production forestry sector: Kyle Burdick, Baskahegan Company
  • Representative from DACF, Natural Areas Program: Molly Docherty, Director, Maine Natural Areas Program (MNAP)
  • Representative from a university or college with an ornamental horticulture experience: Matt Wallhead, Ornamental Horticulture Specialist, University of Maine Cooperative Extension
  • Representative from either Maine Department of Transportation or a municipal public works: Kyle Rosenberg, Bath City Arborist
  • Representative from DACF, Horticulture Program: Gary Fish, State Horticulturist

 

Committee Tasks and Timeline

The stakeholder committee held its first meeting at the beginning of March and will meet regularly throughout the year to accomplish various tasks.

Spring and Early Summer

Develop a list of potential species to be evaluated for addition to the list of species prohibited from sale. This list will be assembled using:

The committee will only consider species for inclusion on the list that are either available for sale or are known to hitchhike with plants offered for sale.

The committee may also develop a list of species or cultivars currently on the prohibited plant list to consider for removal from the list using suggestions from the committee or cultivars that have been submitted by the public using the Request to Exempt a Specific Cultivar (PDF). The stakeholder committee will only consider submitted cultivars for exemption when there is independently, peer reviewed, scientific research evaluating the invasiveness of the cultivar.

Late Summer and Early Fall

The list of species will be evaluated for invasive potential using the criteria listed in Ch 273. The Rule lists specific criteria that a plant must meet in order to be considered invasive and included on the list:

  • The species must be non-native,
  • Can rapidly grow, establish and spread in minimally managed habitats
  • Has the biological potential to spread widely including across spatial gaps (unassisted by people),
  • Can exist in high numbers or large colonies in minimally managed habitats and
  • Can displace native species in minimally managed habitats.

Once the plants have been evaluated for invasive potential, the committee will finalize a proposed list of species to be included on the list of invasive terrestrial plants prohibited from sale in Maine. The committee will also determine if any cultivars proposed for exemption should be approved.

When developing these lists the committee may consider additional data and other information than just the criteria listed in the rule; a species evaluation may determine that the species is invasive, but the species is not automatically included on the prohibited plant list.

Factors the committee may consider for species inclusion or exclusion from the list could include (but are not limited to):

  • Extent to which the species is available in the nursery trade or if the species is known to move as a hitchhiker with plants offered for sale,
  • Any economic, social, cultural or environmental benefits of the species,
  • Distribution and range of habitats in Maine where the species could be invasive,
  • Climate change influences on range shifting invasive species

Late Fall and Winter

Proposed rule changes including additions or deletions to the prohibited plant list, will be published and available for public comment. As with the original rules, a phase-in period of at least one year will be included in the proposed rule to allow newly listed plants to be sold out of inventory.

Opportunities for Participation

While the stakeholder committee will be doing the bulk of the work to assemble, review and prepare a proposed list of species for inclusion on the prohibited plant list, there are still ways for the public to make sure that your voice is heard.

Here are four ways you can participate in the process:

  1. Have a species in mind that you think should be evaluated for inclusion on the prohibited plant list? Submit the species using the Maine Invasive Species Nomination Form
  2. Is there a new or existing cultivar of a species on the current prohibited list that research shows is not invasive? Submit the Request to Exempt a Specific Cultivar paperwork.
  3. Contact a committee member to discuss a particular species and how its inclusion (or exclusion) on the prohibited plant list might affect you.
  4. When the proposed rule goes out to public comment be sure to review the proposed rule and submit your comments. We want to hear from you whether you are in support, against or neither for nor against the proposed rule changes. The Department will respond to every comment before the rule is finalized. In some cases, if enough comments are submitted suggesting changes the proposed rule may be revised and re-submitted for public comment. The only way for us to know how the proposed rule affects you, is if you tell us!