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 may indicate 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 safe choice).
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.