The opening line of a recent press release from the Weed Science Society really caught my eye. Heck, it would catch anyone's eye: "Earlier this year a woman in Washington State died from suspected hemlock poisoning after gathering the leafy green weed and using it on a salad."
So I called the article's quoted weed expert, Joe DiTomaso, a Cooperative Extension Specialist in the Department of Plant Sciences at the University of California at Davis to see how often something like this happens.
"Thankfully not that often—at least that we know of. But of course even once is too often if you're the eater," he replied.
Joe agrees that there seems to be a resurgence of interest in the topic of wild foods—we here at You Bet Your Garden have been getting quite a few calls and emails about the subject—so I thought that he and I should go over the basics of wild food safety, as well as touch on some of the "Ten Least Wanted" plants identified in the release.
I began by asking Joe his feelings about a quote from the late, great master of wild foods, Euell Gibbons that I have hanging in my office. It says: "There are no poisonous plants that taste good; nature does not want to kill you."
"That's pretty much true," he agreed, adding that it also introduces a valuable point; that naturally occurring poisonous compounds in plants are there to protect the plants from being devoured by insects and herbivores. These natural repellants generally taste bad, so they act as a feeding deterrent. If the creature isn't deterred and keeps eating, it'll get sick; perhaps even die. Either way, it will soon cease to be a threat to the plant.
Conversely, Joe explains, some plants taste good as an incentive. Fruits for example; the creature eating a sweet fruit gets good taste and nutrition, and then wanders off and plants the seed (or seeds) it ingested with those good tasting parts, helping the plant propagate and spread its range. So a bitter taste is often an indication of an unsafe plant, and a nice sweet taste typically means: "I'm safe; come and eat me!"
"I have to agree with the late Mr. Gibbons," says Joe; "I can't think of a sweet tasting fruit that's dangerous.
"Of course, not all plants that taste bad are poisonous," he continues. "Some natural repellants that function as pesticides turn out to be good for human health; components in onions, garlic and broccoli come to mind. But this information has been assembled over centuries, he cautions. "People shouldn't try and figure it out in the field."
Perhaps most interesting are the plants whose fruits are poisonous when immature and then safe to eat when ripe, he notes, adding that two such plants are on the Weed Society's 'Top Ten' list.
One is bittersweet nightshade (Solanum dulcamara), an invasive weed related to tomatoes and potatoes. "It can be extremely toxic; just the juice from the wilted leaves can be deadly," he explains. "The most common nightshade poisonings occur when curious people eat the green berries. But those same berries are safe and edible—at least for wildlife—when they turn a ripe red or purple. It makes perfect sense; the plant doesn't get any benefit when its unripe fruit is eaten, so that fruit is bitter and deadly. But it WANTS birds and mammals to consume and replant its ripe, mature berries, so they become sweet—and safe to eat.
"The other example on the Weed Science Society list is a plant called the Groundcherry (Physalis species), also in the tomato and potato family. Its leaves and unripe fruit are so poisonous they can be fatal, but the ripened fruit loses all toxicity. Some people even make jams and jellies from the ripe fruit."
I'll pass on that potential delicacy, thank you.
"Common pokeweed or pokeberry (Phytolacca americana) is somewhat similar," he continues. All parts of the raw, uncooked weed are poisonous at all growth stages, but pokeweed greens can be safely eaten if cooked correctly," he explains, citing the popular old song "Poke Salad Annie". "But poke greens need to be thoroughly cooked to remove their toxins, and you really have to know what you're doing," he cautions. "If they're not prepared exactly right, they can be really harmful."
Other members of the Weed Society's rogue's gallery include the afore-mentioned Poison hemlock (Conium maculatum), a biennial weed with fern-like leaves that can be visually mistaken for parsley. "But it doesn't TASTE like parsley", explains Joe. Same with Waterhemlock (Cicuta douglasii and Cicuta maculata), a group of native perennials in the carrot family that grow wild in wetlands and marshes. "An inexperienced person might mistake waterhemlock for a number of different edible plants, including carrot, wild celery, watercress, ginseng and parsnip, but the taste is wrong—a bitter warning that you're sampling a deadly poison, and not a free edible," warns Joe.
Bottom Line: As they used to say in every episode of the old TV show, "Hill Street Blues": "Let's be careful out there." If you want to collect and eat wild plants, take some classes and go out first with experienced gatherers. And don't continue to eat anything that doesn't taste good.
Here's a link to the Weed Science Society's 'Top Ten Plants to Avoid' release, with photos of the weeds in question (or should that be "questionable weeds"?).