Marge Bartlett leads a foraging group at the U.S. Fish and Wildlife Service’s Kettle Pond Visitor Center in Charlestown.

THE Providence Journal / Tom Meade

Got a problem with Japanese knotweed? Dandelions? Autumn olive?

Before his foraging walks, Massachusetts naturalist Russ Cohen, author of Wild Plants I Have Known and Eaten, serves fruit leather made with autumn olive berries. It’s sweet and tart all at once, and the berries contain 18 times more healthy lycopene than tomatoes.

In his book, Cohen has a recipe for strawberry-knotweed pie. Cohen’s recipe for sour cream knotweed crumb cake appears on New England Wildflower Society’s Web site, newfs.org. In spring, knotweed shoots may be steamed and served with melted butter. They taste a little like asparagus sprinkled with lemon juice.

Marge Bartlett of Charlestown told would-be foragers on her walks that all parts of the dandelion, including roots, are delicious.

“A weed is a plant that is not only in the wrong place, but intends to stay,” writes Sara Stein, author of My Weeds: A Gardener’s Botany.

You can’t beat ’em, so eat ’em, say Bartlett and Cohen.

Sheep sorrel, a sure sign that the soil beneath a lawn is acidic, adds a pleasant tang to salad, says Bartlett.

Lamb’s quarters, or goosefoot, a weed that grows in even the most barren city lot, tastes much like spinach, delicious cooked or raw.

Sweet fern, another weed that tolerates terrible soil, makes a terrific tea, says Bartlett.

Milkweed shoots and young seedpods taste a little like a cross between green beans and asparagus. They are best when immersed in water that is already boiling and boiled for seven minutes, says Cohen. They are wonderful with butter or used in a dish like milkweed egg puff.

Stinging nettles make a delightful springtime soup, and they work with other greens in spanikopita.

Shadbush sounds more appealing when it’s called juneberry, a tasty and nutritious ingredient in granola. Native Americans used juneberries in Pemmican, their version of energy bars.

Bayberry leaves may be used in place of bay leaves to impart their own fragrance and flavor to soups and stews.

Staghorn sumac, a plant that grows around vacant lots, has a flower that makes lemonade-like beverage when steeped in water. Cohen says his friend, Sam Thayer, likes to snap off young stems in the spring so he can peel and eat them raw.

Chickweed, a common invader of gardens, is excellent in salads; it tastes like raw corn.

Purslane, another common “weed” is prized in some African cuisines; it makes a tart addition in salads.

Wood sorrel, a common weed in many lawns, also makes a tart addition to salads.

Jerusalem artichoke, a tall native weed with large flowers, grows above tubers that are like potatoes, only nuttier.

Mugwort, an invasive weed that usually enters a landscape with nursery-grown ornamental plants, is reputed to make dreams more vivid, says Bartlett.

Never eat a plant you’re unsure of, she advises, and don’t eat plants that grow near the road where they absorb pollutants. Stay away from plants that have been exposed to pesticides, Cohen adds.

There are dozens of books on wild, edible plants. Russ Cohen’s book, Wild Plants I Have Known and Eaten, is one of the best because Cohen writes about plants that grow in Southern New England. It is available at online book sellers.

The best introduction to wild edible plants is a plant walk with an expert. Cohen leads several walks throughout the summer, including one in Westport, Mass. His schedule is posted online at http://users.rcn.com/eatwild/sched.htm.

tmeade@projo.com