Editor’s Note: This article is printed with the permission of the Cooperative Extension Service.
Maine’s landscape is famous for its variety. Within the state, one can find ocean beaches, lakes, rivers, mountains and forests. Maine is locally influenced by both coastal and inland weather patterns. This creates relatively mild areas and areas that are almost arctic within the state’s 300 mile length and 200 width. Maine rises from sea level to over 5,000 feet at the top of Mt. Katahdin. This wide range of elevation results in a diversity of habitats including flat, sandy plains, rolling hills, rounded balds and craggy mountains with shear cliffs. Maine’s forest ranges from spruce and fir near the coast, to hardwoods in the western and northern hills. More than 100 types of habitats have been identified with over 2100 plant species spread across the state’s varied landscape.
What are native versus non-native plant species, and why should we care?
Native plants are those species that either arrived in Maine without any influence of people, perhaps thousands if years ago, or originated here. Non-native species were brought intentionally, for horticultural or other uses, or came accidentally, such as in ships’ ballast, as crop seed or in soil.
Some non-native plants continue to escape from cultivation and become naturalized in wetlands, lakes, woods, fields or roadsides.Because natural predators and diseases are left behind when they are introduced here, these plants have few population controls and can spread aggressively. Although species such as purple loosestrife, Japanese barberry, and Asian honeysuckles may be pretty, they can become serious pests. One long-term effect is to degrade the habitat for native plants and animals. These plants choke out native vegetation, diminish the availability of food plants for wildlife, and alter the behavior of native animals such as pollinators, plant-eating insects and fruit-eating birds.Unchecked, the invasion by non-natives could drive some species to extinction. This is why these plants are a concern to those who want to protect native species and natural areas.
Plants to Avoid and Why
Most familiar nursery plants are not invasive and are appropriate for planting. However, two popular species often found in the trade, purple loosestrife (lythrum) and Japanese barberry (berberis thunbergii), are highly invasive. A single purple loosestrife plant can produce three million seeds in a single season! Even the tiniest root fragments can grow into new plants. Japanese barberry is invading Maine’s forests and wetlands because birds disperse its seeds over long distances. Both of these are very difficult to eradicate once they become established.
Non-native plants considered invasive in Maine include:
purple loosestrife Lythrum salicaria
Japanese barberry Berberis thunbergii
Oriental bittersweet Celastrus orbiculatus
Japanese Knotweed Polygonum cuspidatum
Smooth buckthorn Frangula alnus
Common buckthorn Rhamnus cathartica
Honeysuckle (non-native) Lonicera ssps.
Garlic mustard Alliaria petiolata
Multiflora rose Rosa multiflora
Small-flowered tickle grass Deschampsia caespitosa ssp. Parviflora
What Can You Do To Help?
You can promote the use of native plants by refusing to purchase or transplant purple loosestrife and other invasive plants.
Grow plants that do not "jump the fence" or escape the garden.
Try growing some native species as ornamentals and as food for the birds and pollinators.
Eliminate invasive non-natives from your yard and garden. Remove the plant and all roots from the soil.
Urge your garden center manager to expand selections of appropriately propagated native plants.
Looking for Native Plants at Your Garden Center
Native plants are well adapted to Maine’s climate and are therefore hardy. Most plants listed in the plant tables are available at local garden centers, where the staff can usually help customers with selection. Ask if their plants are nursery-propagated. This is important, since collecting plants, cuttings, seeds or sods from the wild can devastate natural populations. If the nursery will not guarantee that its native plants are nursery-propagated, buy elsewhere.
Native plants provide color, screening, windbreaks, food and shelter for wildlife. They add visual interest in the winter garden. Herbaceous perennials add color, structure and texture to the border or woodland and can be effective parts of the landscape most of the year.
A Short List of Native Ferns
| Adiantum pedatum | Athyrium felix-femina | Dennstaedia punctiloba |
| Dryopteris carthusiana | Dryopteris marginalis | Onoclea sensibilis |
| Osmunda claytoniana | Osmunda regalis | Polystichum acrostichoides |
A Short List of Native Perennials
| Actaea pachypoda | Aquilegia canadensis | Aralia racemosa |
| Arisaema triphyllum | Asclepias syriaca | Aster nova-angliae |
| Aster nova-belgii | Caltha palustris | Campanula rotundifolia |
| Chelone glabra | Clintonia borealis | Erythronium americana |
| Eupatorium maculatum | Eupatorium perfoliatum | Iris versicolor |
| Physostegia virginiana | Polygonatum pubescens | Potentilla argentea |
| Sanguinaria canadensis | Tiarella cordifolia | Uvularia sessifolia |
| Viola cucullata | Viola labradorica | Viola pubescens |
More information about invasive species may be obtained from:
Maine Natural Areas Program
93 State House Station
Augusta, Maine 04333-0093
207.288.8042