› Weird Science

Weed Eaters

These guys want you to eat weeds—and they’ll show you where to find ’em.

Tom Carlson has a tendency to pull disappearing acts. You might be walking across campus at the University of California, Berkeley, with the ethnobotonist and suddenly realize, mid-conversation, that he’s no longer at your side.

That’s what happened to me on a recent sunny afternoon. Carlson had scampered down the side of a low ravine to inspect the plants growing in a trickle of a stream. “Aha!” he cried, holding up a fistful of green leaves. “Watercress. You have to try some—it’s delicious.”

He was right. It had a delicate, peppery flavor, and I found myself reaching for more.

Carlson is a dedicated forager who has studied how plants influence human health in cultures all over the world, from Asia to Africa to the Pacific Islands. But his latest project is much closer to home. This fall he teamed up with Berkeley statistician and fellow forager Philip Stark to suss out how much produce—in the form of edible weeds—is available in California’s East Bay. The project’s website has an interactive map as well as recipes and soil-quality information.

Sure, you can just buy dandelions for $1.99 a bunch at your local upscale farmers’ market, but the duo isn’t looking cater to that crowd. The project, funded with $25,000 from the Berkeley Food Institute, focuses on food deserts: low-income neighborhoods with little access to fresh produce.

The lack of nearby supermarkets drives food-desert dwellers to spend their grocery money at corner stores or fast-food joints, which tend to carry highly processed foods that contribute to obesity, diabetes, and other health problems. Carlson wants people to start looking out their front door to find the greens missing from their diets, noting that fennel, nettles, huckleberries, wild lettuce and radish, and 70 or so other edible plant species abound, most brought here long ago by European and Asian immigrants who used them for food and medicine. “Many of these may not show up in your typical grocery stores,” he said, “but they’re tasty, nutritious—and free.”

On that sunny Thursday, I tagged along on a weekly reconnaissance expedition. Carlson, Stark, four students, and I piled into a rented van and drove north to Richmond to get a snapshot of the edible weeds pushing up through sidewalk crags, along the road verge, and behind chain-link fences. The professors explained how to estimate the number of servings for each species, and everyone pulled out their smartphone to enter the data and location in the iNaturalist app.

I turned to Carlson to ask him how much one serving is, but he’d vanished on me again. I found him behind a tree. “This dock is very voluptuous,” he said, pointing to a broad-leaf perennial. As I chewed the bitter herb, jotting down that a serving is a half-cup, or about a handful, a woman walked up and asked us what we were doing. Carlson told her. She cocked her head.

Photo: Philip B. StarkBroad-leaved dock growing in Richmond, California

“You’re looking for weed?”

“Yes. Oh, no. We’re looking for edible weeds.”

She looked dubious.

“It’s a smorgasbord of goodies—most of the plants here are edible,” said Carlson, a smear of green on one lip as he munched oxalis, whose clover-like leaves have a pleasingly tangy flavor. She refused his offer to try it.

“No thanks,” she said. “Dogs be pee-peeing on it. Maybe if I was starving.”

And therein lies the challenge. Yeah, weeds are free and nutritious, but convincing people to change their food habits is notoriously difficult. That’s why the team engages the people they encounter on the street, as well as trains a small but growing army of enthusiastic college students. “This is the piece of the project that could really go viral,” said Stark, the statistician who developed a taste for foraging on his long trail runs, and now picks most of the greens and herbs he eats. 

“Do I think people can get everything they need from foraging?” asked Carlson, a vegetarian who prefers to hunt for his meal rather than packing lunch. “No. And I know not everyone will try it. But people really can augment their diet with these plants, which just keep growing despite the fact that California is in the midst of one of the worst droughts on record.”

Photo: Philip B. StarkHomemade pho noodles with dandelion, dock, sow thistle, fennel, and field mustard.

Oh, and that concern about dog urine? Stark sighed. “That’s the number one question we get.” He pointed out that conventional produce is grown with fertilizer and pesticides, and organic foods are grown in manure and compost. “Wash your veggies before you eat them, wherever they come from,” he said.

Of the dozen or so passersby, about half were willing to try the proffered greens, with varying levels of enthusiasm. “The stuff you buy in the store is getting worse,” said one man. “And you don’t know what they spray on it.”

As for the safety of the street weeds, Carlson explained that most herbicides target broad-leaf plants, which also happen to be the edible ones. So if they’re growing, it’s a good indication no one is spraying. (“The more people take care of their lawns,” added Stark, “the less there is to eat.”) The project is also testing for heavy metals in the soil. “So far, we haven’t seen any red flags,” said Carlson, bending down to pluck a low-growing plant. Chickweed, I discovered, tastes like alfalfa sprouts.

With only a couple of blocks left to go, a man driving by stopped, rolled down his window, and asked, “You studying the plant life?” He and his two grandsons got out of the car and joined the crew. As we wrapped up, he exchanged contact information with Carlson, promising to join the team on the next excursion. “Don’t forget to call me,” he said as he walked back to his car.

“Did you hear that?” Carlson asked, clearly elated. A new member of the weed-eater army.


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