Cattail Bob spots the first edible plants before we’ve walked halfway across the REI parking lot. He points to a bush in the Denver store’s landscaping: “Wild rose. The rose hips are edible, of course, as are the petals. There’s not a lot of flavor, but they make a nice color addition to a dish.”

He points at another plant: “Red osier dogwood—Native Americans would scrape the bark and smoke the cambium layer.” A few steps farther: “Golden currant. Try the fruit.” I pluck a few of the yellow-orange berries and sample them, wondering if REI’s security is radioing for backup. The berries are tart and yummy.

Bob Seebeck, 55, who goes by the self-bestowed nickname Cattail Bob, is a naturalist from Drake, in the high foothills west of Loveland. He has been studying and gathering wild edible foods since 1975. He published a book called Best-Tasting Wild Plants of Colorado and the Rockies (Westcliffe, 1998), and he teaches classes on edible and medicinal plants, emergency survival, and cabin building on weekends during the growing season. I asked him to meet me near downtown Denver because I was curious about the wild foods that grow in the middle of a major city—if you had to, I wondered, could you live off the urban landscape?

Standing by the bike trail that’s sandwiched between I-25 and the South Platte River, we have to speak over the roar of traffic and the rush of the rapids at Confluence Park. It’s a foggy morning in September—a bit late for finding wild plants, I would have thought—but Cattail Bob assures me we’ll have no problem. (The collection season extends from mid-April to October in Denver.) Slender and sporting a trim salt-and-pepper beard, Seebeck wears a pale-blue nurse’s smock, jeans, and hiking shoes. We cross nearby railroad tracks and walk southwest along the bike path under Speer Boulevard. Seebeck stops every few feet to point out plants we could eat, and now and then he picks samples for me to try. Mallow, a round-leafed creeping weed that’s the bane of my lawn at home, has a mild, nutty flavor. Seebeck says the leaves are great in salads and casseroles, or as a thickener for soup. Purslane, a spreading, pink-stemmed weed often found growing in the cracks in sidewalks, has a pleasant yet slightly sour taste. Seebeck tells me the plant is extremely rich in healthful omega-3 fatty acids and is useful in marinades or sprinkled on sandwiches. He points to a tall, long-leafed plant: “Lambs quarter. It’s got a bland-tasting leaf, but it works well on sandwiches and salads if you add some dressing. Think about it: Lettuce is also bland without salad dressing.”

Seebeck looks around and says, “There’s not as much diversity in an urban landscape as we’d find if we were up in the foothills near my home. The only fruit we’ve seen is in the landscaping—no wild apple, no wild plum. I’m not seeing any mints or any berries.”

He’s apologizing, but I’m already astonished by how much he’s found. And it’s not just the greens—Seebeck sees wild resources everywhere. Rearing up among the waterlogged garbage on the banks of the Platte are tall stalks of amaranth, whose shiny black seeds are used as cereal or ground for the flour you find in health food stores. “In a big field, you could collect a big sack of these seeds real quick,” Cattail Bob explains. As we walk across the weedy grasses behind the Children’s Museum, he points to a patch of alfalfa, a plant whose seeds yield, of course, those alfalfa sprouts you might find in a garden salad. In fact, he says, “Any edible seed can be sprouted, so you can have fresh vegetables in winter and get your vitamins.”

Here’s a patch of salsify (“the root tastes like oysters when you cook it and makes a great white sauce for pasta”), and over there is dogbane (“one of the best rope-making plants in the West”), and there’s a stand of willow (“you can scrape the bark off to get acetosalic acid—aspirin”).

I ask Seebeck how people figured out which plants were edible. “We are sitting on top of generations of people who learned to use these plants,” he explains. “European immigrants experimented with things similar to the plants they knew from home. And they learned from the Indians. Lots of information was probably lost when the tribes were eliminated in Colorado.”

As shrieks from the roller-coaster riders at Elitch Gardens rise across the river, Seebeck adds, “I’d like to see parts of city parks left wild, so kids could experience a wild environment and learn about these things in a safe place.”

We double back past the museum and find a tiny, oily-looking marsh, where Cattail Bob spots some cattails. He plucks a stalk, pulls out a knife, and pares away the husk, leaving a pale-green core that looks like a leek but tastes like a cucumber.

Given all the edible plants we’ve seen during our short stroll, I’m surprised to hear Seebeck say that wild plants are seldom useful in real survival scenarios. People can almost always live without food until rescuers arrive, he explains; shelter, water, and warmth are much higher priorities, and foraging for edible plants just wastes valuable energy. Plus, even though Colorado has a relative paucity of poisonous plants, there are a few dangerous species that look very similar to edible plants: death camas, poison hemlock, and sweet pea, among them.

And there are other dangers in the city for would-be gatherers. Walking back along the bike path toward REI, we pass an evening primrose, whose roots, leaves, buds, and flowers all are edible, but Seebeck demurs: “It looks like it may have been sprayed. I wouldn’t want to eat that.” The leaves of urban plants may be covered with herbicides and pollutants from nearby highways; toxins may accumulate in the soils; and you have to worry about giardia on plants that grow in water. It seems to me that even though you may well be able to dine daily on back-alley and roadside plants in Denver, you probably wouldn’t want to do it too often—and only then for the sheer novelty of it.

Moreover, Seebeck says, overharvesting wild plants can threaten their survival, especially if foragers pull up entire roots. Pick only a few leaves or berries from a plant; if you’re going to eat a lot of wild food, Cattail Bob suggests planting the seeds and growing your own.

In other words, foraging for plants should be a fun pastime, not a way to cut down on your grocery bills. Try a salad of wild greens or serve a novel appetizer at a dinner party. Just remember Cattail Bob’s sage advice: “If you’re making a dish from wild plants for guests, you have to use as much color, texture, and taste variety as possible. Because remember, you’re asking them to eat weeds.”