Maine’s native landscape

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-mile width. Maine rises from sea level to over 5,000 feet in elevation at the top of Mount Katahdin. This wide range of elevation results in a diversity of habitats including flat sandy plains, rolling hills, rounded summits and craggy mountains with shear cliffs. Maine’s forests vary 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 about 1,500 native plant species spread across the state’s varied landscape.

What Are native versus non-native plant species, and why should I care?

Native plants are those species that either arrived in Maine without human intervention, perhaps thousands of years ago, or originated here. Non-native species were brought intentionally for horticultural or other uses, or came accidentally in ships’ ballasts, crop seed or in soil. Some non-native plants continue to escape from cultivation and become naturalized in wetlands, lakes, woods, fields or roadsides.

Natural predators and diseases are left behind when non-native plants are introduced here. Therefore, their spread is uncontrolled and such non-native species as purple loosestrife, Japanese barberry and Asian honeysuckle can become serious pests.

One long-term effect of invasive non-native species is to degrade 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, invasion by non-natives could drive some species to extinction. This is why non-native plants are a major concern to people 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, a few popular species, including purple loosestrife and Japanese barberry, 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 species are very difficult to eradicated once they become established.

Non-native plants considered most invasive in Maine include:

Purple loosestrife (Lythrum salicaria)

Japanese barberry (Berberis thunbergii)

Oriental bittersweet (Celastrus orbiculatus)

Japanese knotweed (Fallopia japonica)

Smooth and common buckthorn (Frangula alnus and Rhamnus cathartica)

Non-native honeysuckles (Lonicera spp.)

Garlic mustard (Alliaria petiolata)

Multiflora rose (Rosa multiflora)

Small-flowered tickle-grass (Deschampsia cespitosa ssp. parviflora)

Common reed (Phragmites australis)

What can you do to help?

You can promote native plants by refusing to purchase or transplant purple loosestrife and other invasive plants.

Grow plants that do not “jump the fence” or escape from the garden.

Try growing some native species as ornamentals and as food for birds and pollinators.

Eliminate invasive non-natives from your yard and garden. Remove the plant, including roots, from the soil.

Urge your garden center managers to expand their selection of 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 in the Native Plant Recommendations are available at local garden centers, where the staff can usually help customers with plant selection. Ask if their native plants are nursery-propagated. Collecting plants, cuttings, seeds, or sods from the wild can devastate natural populations. If the nursery cannot guarantee that its native plants are nursery-propagated, purchase your plants elsewhere.

For more information about Maine native plants, see Bulletin #2502, “Native Plants: A Maine Source List.” The Maine Invasive Plants fact sheet series describes invasive exotic plants that present threats to native Maine terrestrial and aquatic habitats. For information about UMaine Extension programs and resources, visit extension.umaine.edu.