'The Cape Cod jungle': What you should know about invasive plants

The movie begins with a happy scene. It's a Cape Cod garden center in spring. Cheerful folks are selecting seeds and flats of plants, loading up on high quality cow poop and topsoil. Optimism is in the air and great green accomplishments are right around the corner.

We cut to an area of disturbed dirt at the edge of the woods. Ominous music slides into the soundtrack. It's a meeting of villains: invasive plants plotting to take over the world.

"I'll take 'em high," says the bittersweet .

"I'll take 'em low," says the leafy spurge .

"I'll get everything else," says the Japanese knotweed .

While it might not be quite this dramatic, the scourge of invasive plant species is always a threat to gardeners and those striving for a beautiful landscape around their homes.

What are invasive plant species?

The Massachusetts Invasive Plants Advisory Group lists over 30 invasive plant species for our state. According to the group, "'Invasive' plants are non-native species that have spread into native or minimally managed plant systems in Massachusetts. These plants cause economic or environmental harm by developing self-sustaining populations and becoming dominant and/or disruptive to those systems."

So we turned to Cape gardening guru C.L. Fornari to get an idea of what invasive plant species are the most problematic on Cape Cod, and what we can do to battle back.

Here's what gets her goat about invasive plants: "Once they show up, parts of people's properties become choked," she said. "It's the start of the Cape Cod jungle. You lose places and landscapes that people want to use for other things."

Honeysuckle is a hassle

First up in Fornari's invasive batting order is honeysuckle, which comes in bush and vine form. "I see it growing at almost every Cape property I visit," she said.

The state Office of Coastal Zone Management (CZM) describes Japanese honeysuckle as a "rapidly growing, woody, perennial vine (that) can be found either trailing or climbing to lengths of 80 feet or more. Look for 1- to 2½-inch oval leaves and showy, fragrant, tubular, yellow-whitish-pink flowers blooming from April to July."

Honeysuckle "can also spread by underground rhizomes and above ground runners and can form dense stands that overwhelm native vegetation—this vine can girdle small saplings and shade out undergrowth," according to CZM.

The bane of bittersweet

Next in Fornari's lineup is bittersweet. According to the University of Massachusetts Extension service , "Oriental bittersweet can be observed growing as a brushy groundcover to a height of a few feet or as a climbing vine on tall trees where the vines may reach 40 to 60 feet. Climbing vines can negatively impact the health of native trees and shrubs."

Fornari said that fall is the easiest time to identify bittersweet vines, because they are festooned with orange-covered berries that split open, revealing a red interior.

Multiflora rose is not so sweet

Let's turn to another invasive that has drawn Fornari's ire. Multiflora rose delivers big flower power, but problematic consequences.

According to Penn State Extension , "multiflora rose persists in our landscape partly due to citizen unwillingness to remove plants perceived to have aesthetic value or value to pollinators and other wildlife. However, the dense, monocultural thickets created by multiflora rose degrade natural environments and reduce native plant and wildlife diversity."

Fornari said multiflora rose can climb up into trees, causing chaos in the canopy, even providing a way for wildfires to climb.

How to fight back against invasive plants

The first step is identification, said Fornari, who suggests using state websites and university extension services to ID possibly invasive plants and find out more about control methods. Mass Audubon also has a handy website with good photos of invasive plants in the state.

Controlling these plants can be a continuous battle, and it is important to research the pros and cons of possible methods. "If nothing else, just cut them off at ground level," said Fornari. "Grab the beverage of your choice and your snippers and go on invasive patrol once a week."

Eric Williams, when not solving Curious Cape Cod mysteries, writes about a variety of ways to enjoy the Cape, the weather, wildlife and other subjects. Contact him at ewilliams@capecodonline.com . Follow him on X: @capecast.

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This article originally appeared on Cape Cod Times: 'The Cape Cod jungle': What you should know about invasive plants