The universal edibility test requires breaking down the parts of a plant and testing them individually over a period of 24 hours. In a survival situation, you don't want to go through this trouble if there isn't a lot of the plant you're testing. If there are only a few sprigs of what you think might be the colorful and edible borage, it won't help you much even if you find that it is the cucumber-like herb. Find something near you that's growing in abundance. To prepare for the test, don't eat or drink anything but water for at least eight hours beforehand. If you're lost or stranded in the wild without any food, this should be pretty easy to accomplish. Now it's test time:
Separate - Because only some parts of the plant may be edible, separate it into its five basic parts. These are the leaves, roots, stems, buds and flowers. There may not be buds or flowers. Check out the parts for worms or insects -- you want a clean and fresh plant. Evidence of parasites or worms is a good sign that it's rotting. If you find them, discard the plant and get another of the same variety or choose a different one.
Contact - First you need to perform a contact test. If it's not good for your skin, it's not good for your belly. Crush only one of the plant parts and rub it on the inside of your wrist or elbow for 15 minutes. Now wait for eight hours. If you have a reaction at the point of contact, then you don't want to continue with this part of the plant. A burning sensation, redness, welts and bumps are all bad signs. While you wait, you can drink water, but don't eat anything. If there is no topical reaction after eight hours, move along to the next step.
Cook - Some toxic plants become edible after they're boiled, so get out your apron and start cooking. Your goal is to test it how you would eat it, so if you don't have any means to boil the plant part, test it raw. Once you've boiled it, or if you're going raw, take the plant part and hold it to your lip for three minutes. If you feel any kind of burning or tingling sensation, remove the piece from your lip and start over with a new part. If there's no reaction, press on.
Taste - Pop the same part in your mouth and hold it on your tongue for another 15 minutes. If you experience anything unpleasant, spit it out and wash your mouth with water. You're looking for a similar burning or tingling as you did on your lip. It may not taste great, but that doesn't mean it's toxic.
If there's no adverse reaction in step four, keep on truckin' to the following page for the next steps.