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Eating even a tiny bite of a toxic plant can cause extreme gastrointestinal problems, or even death. The U.S. Army’s survival experts devised this test to determine a plant’s edibility. When in doubt, follow these steps before chowing down. It’s a slow process, but necessary. (Warning: This is for emergencies only. Plan A should always be to positively identify everything you eat.)
You’re going to need time to properly conduct this test—about 24 hours per part of the plant—so there needs to be enough of whatever plant you’re testing to be worth the trouble. To make sure the reactions you’re observing are from the plant you’re testing, begin by fasting for 8 hours, if you haven’t already. (Though we assume if you’re doing this test, you’re in desperate straits as it is, and probably haven’t been snacking for a while.) This test is only for plants; don’t try it with mushrooms, which can be deadly without the kind of warning that many plants provide.
- Separate the plant into its various parts—roots, stems, leaves, buds, and flowers. Focus on only one piece of the plant at a time.
- Smell it. A strong, unpleasant odor is a bad sign, as is a musty or rotting odor. Keep a special lookout for pear- or almond-like scents, which can be evidence of cyanide.
- Test for contact poisoning by placing a piece of the plant on your inner elbow or wrist for 8 hours. If your skin burns, itches, feels numb, or breaks out in a rash, wash off your skin and don’t eat the plant.
- If the plant passes the skin test, prepare a small portion the way you plan to eat it (boiling is always a good bet).
- Before taking a bite, touch the plant to your lips to test for burning or itching. If there’s no reaction after 15 minutes, take a small bite, chew it, and hold it in your mouth for 15 minutes. If the plant tastes very bitter or soapy, spit it out and wash out your mouth.
- If there’s no reaction in your mouth, swallow the bite and wait 8 hours. If there’s no ill effect, you can assume this part of the plant is edible. Repeat the test for other parts of the plant; some plants have both edible and inedible parts. Starting to feel sick? Time to bring it up.
A Better Idea: Know What Plants You’re Eating
The Universal Edibility Test is a last resort for a reason: Not all dangerous plants will exhibit expected signs in a test like this. Others may not seem poisonous in small quantities but can cause debilitating or even deadly effects in large amounts. Instead of guessing, take a little extra time in advance to seek out a regional field guide and familiarize yourself with common edible species wherever you’ll be hiking. (Best idea? Don’t run out of food in the first place by packing enough calories and bringing a map, compass, and the knowledge to use both.)
Last updated November 2021