Eat Up: Southern New England Offers Yummy Buffet of Invasive Plants

Massachusetts forager shares his favorites

By Frank Carini / ecoRI News staff

Autumn Olive, delicious and nutritious. Photo by Will Collette

The following statement is most likely an alternative fact, but it appears real enough: Invasive plants outnumber native species in southern New England, especially in Rhode Island.

We’re fighting them on land and in the water. It’s mostly our own fault, long ago and still introducing them into places where they don’t belong.

These unneighborly ornamentals, many brought to the United States from Japan and eastern Asia in the 1800s, can tolerate a range of site and soil conditions, which means they come to dominate the landscape.

They all crowd out native species, and some topple trees. They can easily be found along roadsides strangling diversity. For instance, both sides of the East Bay Bike Path from end to end are full of invaders.

Other popular recreational areas, such as Indian Lake in South Kingstown and Meshanticut Lake in Cranston, are teeming with aquatic invasive species.

EDITOR'S NOTE: While I also see invasive plants as a threat to our native species, I agree with Russ Cohen's comments, quoted by Frank below, that one way to attack them is to eat them. In 2012, I wrote the first of several pieces praising the Autumn Olive, an invasive plant that was imported to help reclaim strip mines because they will grow where most plants won't. Here's my first article.

We have several autumn olives that sprung up when the adjacent vacant lot was cleared by the former owners for a new home. We bought the lot to prevent that from happening and in the process inherited the autumn olive trees. Since I wrote the article in 2012, my autumn olives have slowly died back as the land regained its fertility. But still, there are harvestable amounts and using a food mill, they produced a very healthy juice. - Will Collette

To deal with these intruders, both on land and in the water, pesticides are routinely used. Besides being toxic, many of these poisons also contain per- and polyfluoroalkyl substances (PFAS). For instance, fluridone is being used in Indian Lake to kill hydrilla. The aquatic herbicide is one of some 1,400 pesticides that contain PFAS, according to a 2023 analysis by the Environmental Working Group of Maine “forever chemicals” data.

In 2022, Maine became the first state to enact a comprehensive PFAS ban. The ban goes into effect in 2030.

Russ Cohen, a longtime staffer for the Massachusetts Department of Fish and Game’s Division of Ecological Restoration, who retired in 2015, offers an alternative to applying poisons: mangia.

Most invasives don’t have natural predators feeding on or killing them, but more than a few are edible to humans. Cohen would know. He has been eating wild plants, both invasive and native, for five decades. Some of which are more nutritious and/or flavorful than their cultivated counterparts.

The naturalist and wild-foods enthusiast grew up in Weston, Mass., where he spent much of his free time in the woods, cultivating a strong connection to nature. His first formal exposure to edible wild plants happened when he was a high school sophomore. He enrolled in an “Edible Botany” course. The course taught him about two dozen edible species that grew around Weston High School, and the class finished its work with a “big feed” — a communal meal prepared from those wild plants.

By his senior year, Cohen was teaching the class. While in college, between his sophomore and junior years, he spent a summer at Harvard Forest in Petersham, Mass., enrolled in a course called “Plants in Relationship to Their Environment.”

The expert forager has since spent the past five decades, since he was 17, leading wild-edible walks all over New England and eastern New York. Cohen and his wife, Ellen, have hosted “Harvest Parties” for friends, preparing several dozen dishes — appetizers, soups, salads, main courses, desserts, condiments, and hot and cold beverages — with wild ingredients they foraged.

I first met him in June 2015 a few days before he retired. He was leading such a tour for the Audubon Society of Rhode Island. Joanna Detz (my wife and ecoRI News co-founder) and myself attended. He told us and the rest of those who took the tour that “Japanese knotweed is at the top of the invasive species list. It’s nasty and it takes over. It’s also yummy. Tastes like rhubarb.”

Cohen makes delicious strawberry-knotweed pies with the ubiquitous weed. Its stringy stalks need peeling before eating, and it is best harvested in April, before it grows big and starts resembling bamboo and is too tough and bitter to eat.

Russ Cohen doesn’t enjoy invasive garlic mustard, the big leaf above, because ‘it’s quite pungent. It’s on the bitter side, and it’s very ecologically disruptive.’ The white flowers are from multiflora rose, another edible invasive that crowds out native plants. (Joanna Detz/ecoRI News)

When Cohen, a longtime ecoRI News reader, commented on a recent story about aquatic invasives by colleague Rob Smith — “Speaking of edibility, Sacred Lotus is highly edible. Perhaps, in places where this plant is growing, its roots, etc., could be harvested for eating before they are poisoned with herbicides.” — I reached out to him to talk about edible invasives.

We spoke a day after he and his wife had returned from a camping trip in western Massachusetts to forage for wild mushrooms.

After exchanging some pleasantries and small talk, our online discussion began with Cohen talking about Japanese knotweed, which can grow 3 inches a day and reach 10 feet in height.

“This could be one of the most hated species on Earth, because once it gets established somewhere, it’s really hard to eradicate and it tends to form these monocultures to the exclusion of everything else,” he said. “And there’s a ton of it in Rhode Island.”

He noted there are some 20 species on the Massachusetts invasive plant list that can be eaten.

“As far as most ecologists are concerned, they’d be thrilled if we all picked and ate as many of these as we possibly could,” Cohen said. “Provided that you’re not spreading them around in the process, and it’s usually pretty easy to do that.”

Many of the edible invasive species on the Massachusetts list can also be found in Rhode Island and Connecticut. Cohen, 67, provided a list of his favorites, “in terms of tastiness”:

Autumn olive: The plant’s flowers bloom in May and they “have a very nice scent.” Cohen harvests the berries in the fall to make fruit leather, likely better known as fruit rollups. He noted “you can eat the fruit raw if you want.”

“This plant is originally from the northeast corner of Eurasia, like where Manchuria is,” Cohen said. “That’s where it grows wild, but it was brought to the United States, and probably the folks that are most responsible for it spreading all over the place are the highway departments that planted it along highways that were built, like, for example, Route 24 coming down from the Boston area into Rhode Island has lots of autumn olive growing along it. Route 95 has some, but this plant has no trouble growing in nutrient-poor soil, because it can make its own nitrogen fertilizer.”

Japanese knotweed: The shoots are “tart and juicy like a Granny Smith apple.” Harvest the shoots — which Cohen calls the plant’s “wild asparagus stage” — in April. “You can just snap that shoot off at the ground level. It’s about a foot tall, and then just steam it for a few minutes and eat it hot or cold like asparagus.”

Cohen tends to wait until the plant gets a little bit taller, 1.5 to 2 feet, in mid-April in Rhode Island, he said. “This is what I call the ‘wild rhubarb stage’ of the plant. I’ll cut these off at ground level, cut off the top cluster of leaves, and I’ll have a length of stalk about a foot and a half long. I peel the skin off the stalk, because the skin is stringy. There’s nothing poisonous about it at all. It’s just when you cook with the stalks that skin can get caught in your teeth. So I’d rather just trim that off. You can chop them up into pieces and then use those pieces instead of rhubarb in virtually any recipe calling for rhubarb.”

Dame’s rocket: This invasive is a member of the mustard family. The white or purple flowers “have that familiar radish, broccoli type flavor to them,” according to Cohen.

“Although the white flowers and the purple flowers have the same flavor, I tend to just use the purple flowers, because purple is a funner color than white,” he said. “You could just eat these or you could, you know, throw them in a salad or just use them to decorate other dishes.”

Black locust: The edible part is the flowers. “They smell like jasmine and they taste like sweet pea pods.” He said this invasive is quite common in Providence and East Providence. Look for the flowers during the second week of May.

“What I will do is just strip the flowers off their central stocks and then you could just eat these plain or throw them in a salad,” Cohen said. “What I love to do with them is make fritters. Take any fruit fritter recipe and just substitute the flowers for the fruit. This is the kind of thing that you could serve to company for Sunday brunch and they’ll be blown away with how good these fritters are.”

Wineberry: This invasive from China is closely related to raspberries and blackberries. “I would say that a regular red raspberry is probably a tastier fruit than these are, because it has a little bit more going on flavor wise. But it’s hard to imagine any fruit that is prettier than these wineberries,” Cohen said. “Wineberry is great for any recipe where you could show off the beauty, even if that’s just on your breakfast cereal in the morning.”

He said the second half of July in Rhode Island is when these berries are going to be ripe.

As for how this overseas invader got here, Cohen has heard this theory and has no reason to doubt it.

“Whalers in their worldwide whaling expeditions ran into this plant in China and liked it and brought it home with them and got it planted in their gardens,” he said. “Then it escaped from gardens, because places where this plant grows, like Cape Cod, the Islands, Narragansett Bay, Long Island Sound, lower Hudson Valley, these are all places that had whaling communities.”

Common/European barberry: Cohen makes what he said “is the best jelly there is” out of the plant’s berries.

“So this one is a nice fall even into the winter foraging opportunity, because the berries will persist on the plants,” he said. “I’m usually not harvesting these until the end of October or November, or sometimes December.”

A related invasive species, Japanese barberry, is also edible, but it “produces berries that I don’t think taste good at all,” Cohen said.

Besides noting the aquatic freshwater invasive sacred lotus — Meshanticut Lake, a 12-acre waterbody in a Rhode Island state park, is being treated for the showy perennial plant native to the warmer regions of Asia — is edible, Cohen said there is an invasive seaweed with several common names, including green fleece, dead man’s fingers, and oyster thief, that also make a good meal.

“In Korea they make kimchi from it. I’ve eaten it raw and cooked,” he said. “The texture is a little off putting, because it’s kind of like eating yarn. It’s really like a fleece, like nibbling on a fleece jacket, but pickled or in a kimchi form it could be really good.”

While he has never eaten sacred lotus, he has dined on a native cousin, American lotus. The latter’s flower is yellow, while the former’s is pink. He said there’s no recorded occurrence of the American lotus in Rhode Island, but it has been found in Massachusetts and Connecticut. He called the lotus a starchy vegetable.

“Have you ever been to a Chinese restaurant and seen lotus root on the menu?” Cohen said. “I’m almost positive that is made from the sacred lotus, except that those roots would be, you know, probably imported from China, dried, and then rehydrated and then sliced up and cooked.”

Cohen and his wife don’t survive on wild plants alone. He said they account for about 10% of their diet. It’s more of a fun hobby.

“I do lot of foraging, and a lot of it is for sharing with other people,” Cohen said. “We have relatively conventional diets … we’re going to supermarkets and restaurants and going to farm stands and farmers markets, and we grow lots of fruits and vegetables in our little lot here. But in addition to that, there’s all this wild stuff, wild berries and nuts and roots and wild mushrooms and stuff that we’re adding to our diet.”

For those looking to go food shopping in the wild, Cohen offered some guidance and tips, such as don’t harvest Japanese knotweed shoots growing near a dumpster at an auto-body shop, or in an open space or roadside that may have been sprayed with pesticides.

Also, foragers shouldn’t be picking plants bare, most notably native ones. In most cases, astute foraging will not hurt an ecosystem, Cohen said, but foragers must be aware of the role plants, especially native ones, play. Overpicking, for instance, could lead to local extinction. Raking the woods searching for delicious treats could alter the humidity of the forest floor and negatively impact the habitat’s ecological balance.

Cohen noted that picking most wild nuts and berries has little impact on the plants, their habitats, or the ecosystem. There are exceptions, however. Some native species’ berries serve an important ecological role. The high-calorie berries of spicebush, for example, are relied upon by migrating songbirds to fuel their southward migrations, according to Cohen. He said it is incumbent upon foragers to show restraint, and leave plenty of berries on the plants.

Digging up plants or stripping off leaves causes stress and has a major impact, he said. Endangered species are off-limits, but, he noted, there are few species in Rhode Island or Massachusetts that are both edible and endangered.

Cohen stressed, however, the importance of not spreading invasive species around when harvesting them. “Don’t spit the seeds of invasive species onto the ground,” he said. “Like a responsible dog owner does, bring a bag and then throw it in the trash.”

“Pick as much of these plants as you like,” Cohen said. “It’s guilt-free foraging.”

While he encourages chefs to use invasive plant species when creating their menus, the same doesn’t apply for native ones. He said he has seen the harm done to native species, their sensitive habitats, and/or wildlife that rely on them by harvesting done to meet the demands of chefs and produce markets.

Since his retirement nearly a decade ago, while continuing to offer walks-and-talks on foraging for wild edibles, the Arlington, Mass., resident has set up a nursery, near his childhood home in Weston, where he is growing some 1,000 plants, representing more than a third of the more than 190 species native to the Northeast that are edible. Many of these plants were propagated from seed Cohen gathered himself.

Note: Russ Cohen received his bachelor’s degree in land use planning from Vassar College in 1978, and received a master’s in natural resources and a law degree from The Ohio State University in 1982. Besides working for the Massachusetts Department of Fish and Game, he also worked for The Nature Conservancy, the Land Trust Alliance, and the Massachusetts Audubon Society.

His foraging book Wild Plants I Have Known … and Eaten, originally published in 2004 by the Essex County Greenbelt Association — and now in its ninth edition — describes some 40 species of edible wild plants commonly found in Essex County, Mass., and in much of southern New England.

For a list of wild recipes, including Sour Cream Knotweed Crumb Cake and Go Anywhere Knotweed Squares, click here. For his schedule of presentations for the rest of the year, click here.