Picture yourself stranded in the wild. Desert island, northern forest, southwestern desert, pick the place. You must have water and food. Both can be equally daunting if water is not immediately available and no bunnies are cooperative enough to scamper past.
Vegetation can be found almost anywhere. You may not know a dandelion from a rose bush, but there is a test developed for those in survival situations that will help you determine which vegetation can be eaten. That's what we're going to look at now.
First, break or crush a part of the plant. Does the sap have color? Discard. If colorless, proceed to step two.
Next, touch the sap to the inner forearm or the tip of your tongue. Does this produce any rash or burning, bitterness, or numbness? If not, proceed. By the way, if you are a heavy smoker, you may not be capable of tasting some poisons such as alkaloids.
Now, boil the plant or the part of the plant you are examining for about five minutes total in two sets of water. This could remove or neutralize any poison that may exist in the plant completely.
Put about a teaspoonful of the plant in your mouth for five minutes, chew, do not swallow. A burning or other unpleasant reaction ends the test at this point.
If no unpleasant effects, swallow this teaspoonful and wait eight hours. If this does not, during that period, cause effects such as cramps, nausea, or diarrhea, eat two teaspoons and wait another eight hours.
After the end of this period, if there are no ill effects, you can consider the plant or the part of the plant you tested edible.
I'll remind you that some parts of some plants can be perfectly edible, other parts can be poisonous. Rhubarb is often given as an example because people eat the stalks but not the leaves. I must point out here that, from what I've learned, the entire plant does have a poison present in varying amounts called oxalate. It is, in fact, strongest in rhubarb leaves which you should avoid because eating large amounts of the leaves can be lethal.
Parts of plants that may be edible include the underground parts, stems and leaves, flower parts including the flowers themselves and pollen, fruits, gums and resins, and saps. Of course, all parts of some plants like dandelions can be edible, in other plants the edible parts vary with the season as with cattails, and then there are plants where one part is edible but another part can be toxic, as mentioned previously.