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  • Writer's picturePatrick Durkin

Field Guide Ensures Safe Foraging and Edible Eating of Wild Plants

Some men walk through woodlands and fallow fields each summer and see only weeds and lush brush.

But when Sam Thayer follows their oblivious boot prints, he sees endless varieties of food, teas, spices and nutritious treats. And if some varieties aren’t sweet or healthful today, Thayer curses himself for being late or calculates when to return.

Thayer, 47, sees nothing magical about his informed foraging. He’s just benefiting from a lifetime of experience. Though he’s comfortable citing scientific names and insights far beyond wild grapes and strawberries, he isn’t university-trained. “I never went to college except to use the library and meet girls,” he said.

By discovering his passion in his youth and chasing it ever since, he amassed a warehouse of useful information. And he had fun doing it. While other kids memorized the jersey numbers, batting averages and touchdown passes of their sports heroes, Thayer explored the outdoors and ate its edible parts.

Given that background, Thayer has never relied on stores for sustenance. As he notes in his new book, “Sam Thayer’s Field Guide to Edible Wild Plants of Eastern & Central North America,” modern groceries must stock products with long shelf lives. That priority keeps many of nature’s most nutritious fruits and vegetables off our plates.

More specifically, when Thayer visited the largest grocery store within an hour’s drive of Weyerhauser, his home in Wisconsin's Rusk County, he identified 124 plants and fungi as the sources for the store’s entire inventory. In contrast, Thayer, his wife and three kids eat nearly 350 species of plant-based foods growing wild within that distance from home. He’s been sharing his knowledge of these varied foods for decades through books, newsletters, interviews and his website,

Thayer wrote his first book, “The Forager’s Harvest,” in 2006; followed by “Nature’s Garden” in 2010, and “Incredible Wild Edibles” in 2017. They’re all great sources, but the topic’s exhaustive, comprehensive masterpiece is Thayer’s just-released “Field Guide,” a weighty 736-page full-color book that’s about the size of two bricks, but heavier.

Thayer owns and reads countless books on wild edibles, but each book sent him searching for details he deems vital. He finally decided to create the authoritative source for all wild edibles in the eastern two-thirds of North America.

He thinks the time is right for his new book. “The world didn’t have many cookbooks when everyone knew how to cook, and the world didn’t need a field guide to edible plants when most humans were hunters and foragers,” Thayer said. “Who today would buy a book about how to drive a car? No one. You just learn it and do it. But few people grow up hunting and fishing, and even fewer grow up foraging, so this book fills a need.”

In contrast, Thayer began foraging as a grade-schooler in Madison. He started learning about edible wild plants at about age 10, and hasn’t stopped stalking and studying them. His information sources were books, articles and his childhood mentor — a best friend’s uncle named David Black. And even though his parents never shared that interest, Thayer’s mother often dropped him off to explore Token Creek, a county park on Madison’s north side.

Back then, Thayer saw Token Creek only for its fields, marshes, muddy stream, scattered brush and the oak grove at its far end. Later, however, he saw its finer details in bur-oak acorns, tall sawtooth sunflowers, 12- to 14-foot giant ragweed, monstrous skunk cabbage, thick-stalked purple angelica, and jewelweed tangles nearly too thick for walking.

The same curiosity that drove Thayer to study edible plants also educated him about birds, wildlife, hunting and fishing. “The more you know about the woods, the better hunter and forager you’ll be,” he said. “You can succeed at one thing if you focus hard enough, but you can be so much better if learn all you can about what surrounds it and why it’s there. As a deer hunter, I always think about what deer are eating that day and how it affects where they move, how long they feed, and how long they must rest while digesting it.”

Thayer’s experience also taught him to be thorough and certain about every plant, leaf, stem, root, seed or tuber before he eats them. That helps explain his book’s size and heft. “When you look at plants or mushrooms, you must be as certain about their identity as you are when you see a banana,” he said.

And don’t rely on handy smartphone apps for that definitive ID. Thayer admits “a little bitterness” about apps and their convenience. “They’re fairly reliable and they’re not a bad place to start, but they’re not foolproof,” he said. “They’re about 95% accurate.”

Because foragers require “banana-certainty,” or 100% accuracy, Thayer suggests starting with an app, and confirming it with his field guide. After all, you aren’t just verifying a bird, fish or mammal’s identity. As Thayer notes in his book’s introduction, if you misidentify a bird, what’s the harm? You won’t require medical attention. But if you misidentify a specific plant, whether it releases a poison or triggers an allergic reaction, eating it can sicken or kill you.

Even so, let’s not over-react. Few people who eat a poisonous plant misidentified it. Thayer said they're most likely victims of non-identification. They ate the plant’s roots, leaves, stems and/or tubers without making a reasonable effort to identify them.

“I have yet to encounter a singled documented case where an adult was killed or severely poisoned after making a reasonable effort to identify a plant (and hopeful guesses don’t count as reasonable),” Thayer wrote in his book. “Most serious poisonings occur when a person who does not regularly forage decides to eat an unfamiliar plant or mushroom they made no attempt to identify. Nothing I write will fix this irresponsible behavior.”

He calls such behavior the “botanical equivalent of a “trigger-happy fool” shooting someone after mistaking them for a deer. Thayer said foragers can further reduce the risk through practice and experience. “Preppers,” for instance, shouldn’t wait for wars, natural catastrophes or civilization’s collapse to learn about wild foods.

“Unless you forage in your everyday life, you will not be competent to forage in the face of calamity,” Thayer wrote. “Start enjoying the benefits of wild food right now.”

Sam Thayer of Weyerhauser, Wisconsin, gathers seeds from prickly-ash bushes. Thayer’s field guide, inset, notes that dried fruit and leaves from this native plant make good seasonings because of their citrusy flavor. Patrick Durkin photo

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