Invasive plants typically have been brought to the United States through the nursery trade, either intentionally as landscape specimens or sometimes unintentionally as seeds or smaller seedlings.
Of all 2,263 plants that have been identified in Massachusetts, about 725 are non-native and considered naturalized (i.e. introduced directly or indirectly by humans and have established populations). Of those, 69 plant species have been classified by the Massachusetts Invasive Plant Advisory Group (MIPAG) as "Invasive," "Likely Invasive," or "Potentially Invasive." Many of these species are now prohibited from import, sale, or trade in Massachusetts by the Mass. Department of Agricultural Resources.
Some of these invasive plants are particularly problematic here in Massachusetts. You may well have seen one or more of them in your own yard or on your street. See the links below for pictures and more information about these, including suggested methods of control.
Lesser celandine Ficaria verna –ALERT click here for more information.
Japanese knotweed Fallopia japonica (also called Reynoutria japonica) –Grows to 6-8’ in colonies so dense that virtually no other plants can survive. The plant has a vigorous system of extremely long roots that makes removal of the plant challenging. Click here for more information.
Bittersweet vine Celastrus orbiculatus –an invasive vine frequently found along roadsides and forest edges. If allowed to grow, bittersweet vines can take over wide areas, aggressively smothering out native trees and shrubs.
Glossy buckthorn Frangula alnus –a woody shrub or small tree that can form dense stands in forests and formerly open areas. It spreads aggressively and threatens forests and wetlands by outcompeting native species for nutrients, light, and moisture.
Multiflora rose Rosa multiflora –a climbing or rambling shrub with single or multiple arching stems that can grow 10-15 feet tall. It produces a large number of hips (seed pods) that get distributed by the birds. It often forms dense thickets that prevent native shrubs and herbs from establishing.
Burning bush Euonymus alatus –this shrub has been popular with gardeners because of its crimson red color in the fall. However, the plant reseeds easily and tends to escape our yards and invade nearby forests and open fields, where it outcompetes native plant species that provide food and shelter essential for birds and other wildlife.
Garlic mustard Alliaria petiolate –a bi-annual plant that readily invades wooded habitats and spreads by seed. The plants produce a toxin that kills soil fungi that our native plants depend on. Annual pulling each spring (April-early May) before the flowers set seed is a way to eventually halt its spread. This is a great activity for kids.
Black swallow-wort Cynanchum louiseae -a perennial vine in the milkweed family with small, black-purple flowers and dark green shiny leaves. Very fast-growing, the plant out-competes native vegetation, reducing native plant diversity and wildlife habitat. Monarch Butterflies mistake this plant for common milkweed but its caterpillars cannot fully develop on it.
More comprehensive lists of invasive plants, along with photos that aid identification and information about their biology and control, are published on the web by Mass Audubon, the Lexington Conservation Commission, the Lincoln Conservation Department, and CISMA (the Cooperative Invasives Species Management Area of the Concord-Sudbury-Assabet watersheds).
A word about herbicides: Many authorities recommend the prudent, limited use of pesticides to control some invasives, particularly with large, well-established populations and where the owner’s time is limited. In small areas like gardens, though, most of these invasive plants can be controlled or even eliminated with diligent cutting or digging. For those who are leery of the health and environmental impacts of herbicides, and who are willing to invest the time and energy to control these manually, we recommend trying to do it without chemicals, as we do in our own gardens.