I loved watching classic 1950s black-and-white sci-fi movies on TV when I was growing up, with “Invasion of the Body Snatchers” being a particular favorite. Creatures from outer space invade a small town in California and methodically replace its residents with emotionless alien duplicates grown in giant seed pods. What was not to love? The story, from a Jack Finney novel, was first adapted for the screen in 1956. That was followed by a second version with the same title in 1978, and then another in 1993 (“The Body Snatchers”), and finally a fourth in 2007 (“The Invasion”). 

A somewhat similar scenario is actually taking place right here in towns all through New England. The creatures may not be from outer space, but they are aliens, and they are taking over. They are the invasive plant species that move in and crowd out our woodland and wetland resident plant populations. These non-native species are silently infiltrating our neighborhood like the “pod people” of “Invasion of the Body Snatchers,” and dominating natural ecosystems.  

What are invasive species?

As the Native Plant Trust explains it, “invasive plants are exotic species introduced into a new location by human activity.”  But not all introduced species are considered invasive. “Invasives are distinguished by their ability to grow and reproduce quickly throughout a natural area, disrupting habitats and food sources for the native plants and the animals that are dependent upon them.” Similar to the Body Snatcher’s “pod people,” these “pod plants” take over and slowly replace our native species. 

Equally true, not all aggressive plants are invasive species. Weeds, for example, can reproduce quickly and aggressively take over an area to the frustration of gardeners. However, those weeds may be native plants, not aliens. A key characteristic of an invasive plant is that it is not indigenous to the area.  

Why are they considered bad?

Invasive plant and animal species have a devastating impact on native species, causing their decline or even extinction. Because invasive species can rapidly reproduce and outcompete native species for food, water, and space, they are among the main causes of global biodiversity loss – second only to direct habitat destruction.

Some of the invasive plants in our area can be enticingly appealing. Winged Euonymus (Euonymus alatus, commonly called Burning Bush) has striking autumn colors. Multiflora Rose (Rosa multiflora) sprouts springtime masses of small white roses. Oriental Bittersweet (Celastrus orbiculatus) has decorative orange and red berries in the fall. Purple Loosestrife (Lythrum salicaria), with its summertime waving stalks of purple, can be quite striking.  Don’t be fooled!  These can quickly take over an area, and in many instances are a hassle to remove. While birds may feed on these plants’ berries or bees pollinate their flowers, our native birds and pollinators don’t have the evolutionary history to extract their full nutritional value – it’s the equivalent of feeding junk food to them. Invasives offer neither a healthy food source nor suitable habitat for our native species.  

One of the most aggressive of the invasive plants is Japanese Knotweed (Fallopia japonica). With its bamboo-like stems, broad leaves, and summertime shoots of small white flowers, it can grow up to 15 feet tall. It can completely cover an area in short order as it sends out rhizomes underground that can extend as far as 70 feet. In addition to smothering native vegetation, it can actually damage pavement, concrete foundations and walls, and drainage systems. Realizing the damage that this plant can do to both infrastructure and the environment, the UK has strict laws in place to prevent its spread.

What can I do?

• Start by learning more about the native and invasive plant species in our neighborhood. Information and a list of invasive species in Massachusetts can be found at: mass.gov/info-details/invasive-plants. The Swampscott Conservancy also has a series of short, informative videos to help you identify some of our most common invasives. Find them on our YouTube channel under “Nature Notes” youtube.com/@swampscottconservancy77/videos.

• Plant native! Help create demand. When you visit your local garden center ask them what native plants they have in stock and select these over non-natives.  You’ll be creating a backyard that is not only beautiful, but a healthy place for native species.

This month, you can also pick up some native plants at the Conservancy’s annual native plant sale, which will be on the opening day of the Swampscott Farmers Market, June 7, from 10 a.m. to 1 p.m., on the town hall lawn off Monument Ave. 

• Don’t buy or transplant invasive plants and, if you have invasive plants on your land, remove them. 
• Report sightings of invasive species on iNaturalist or via the Invasive Plant Atlas of New England (IPANE). IPANE aggregates data related to invasive species that can be shared with educators, land managers, and conservationists: http://www.eddmaps.org/ipane/
• Volunteer to help remove invasive species from public natural areas. The Conservancy has organized invasive plant removal events this summer on the third Saturday of each month. Become a volunteer steward by performing low-key maintenance, including removing invasive species. The next event will be on June 20 at 9 a.m. at the new Archer Street town-owned woodlands. There will also be cleanups on July 18 at the Rail Trail; on August 15 at Muskrat Pond (off Forest Ave.); and Sept. 19 at Ewing Woods (by the new Elementary School). For more information on these events, and to be informed of any scheduling changes, you should register online at: tinyurl.com/SCVolunteerCrew. If you have any questions, email: [email protected] 
• And don’t forget to spread the word! As you learn more about natives and invasives in our neighborhood, share what you know.  

The invasion of the invasive species in our neighborhood is as chilling as a 1950s sci-fi thriller. You can help protect our native ecosystems and reduce the ecological and economic impact of these alien invaders by taking action. 

Note that a Nature in the Neighborhood article will not appear in July, returning in August. Have a fun and nature-filled summer until then! 

Nature in the Neighborhood is a monthly feature provided by the Swampscott Conservancy and submitted by Conservancy President Tonia Bandrowicz.