This is never an easy question to answer unless you know your wild plant book from back to front, inside and out and can identify every plant within it.
The most crucial factor in using plants for food is to avoid accidental poisoning. The general rule is if you can’t positively identify it and can be 100% sure it is safe, and then don’t eat it.
Learn as much as you can about plants you intend using for food and their unique characteristics. Some plants, for example, have both poisonous and edible parts and others are poisonous if you eat them raw but are fine when cooked. Then there are other plants which are poisonous for part of the year but are edible during other periods so you need to gain a thorough understanding of each and every plant which is almost impossible. However, if you’re unsure don’t take a chance.
For the purpose of this article, however, let’s suppose you have found yourself in a survival situation and can only rely on plants for food. What would you do? Even if you had an encyclopaedic knowledge of British wild plants, supposing you’re in the middle of a rain forest in Brazil, what then?
The truth is, unless you’re 100% sure, you’re not going to be absolutely certain that the plants you are considering eating are not poisonous but there are 2 basic things you can do.
Whilst emphasising that no plant is perfectly safe to eat unless you definitely know what it is you’re consuming, following some simple rules should help a little.
Firstly, remember that plants growing near houses and buildings or along roadsides might have been sprayed with pesticides so you should wash them thoroughly before eating them.
If you find plants near water and suspect the water might be contaminated, thoroughly boil the plant and even disinfect it first to eliminate any water borne parasites.
Never eat fruit that is starting to go off or show signs of mildew as it may be contain fungal toxins which can be highly dangerous if consumed.
Plants that give off an almond-like scent can indicate the presence of cyanide compounds.
Never eat any mushrooms unless you can absolutely 100% identify them. With mushrooms, there is no room for experimentation. Symptoms of the most dangerous mushrooms which can attack the central nervous system may only manifest themselves after a few days and by then; it is too late to reverse their effects.
The Universal Edibility Test
Firstly, it must be emphasised that this should only be used in an emergency survival situation. It also takes 24 hours or so to complete the test so it’s only worth doing if there is a plentiful amount of an unknown plant that is enough to keep you going if it turns out to be safe. The test isn’t 100% guaranteed but, in a life or death situation, it provides a pretty reasonable benchmark.
Before you start the test, you shouldn’t have eaten anything for 8 hours. That said, if you’re in the jungle without supplies, that’s likely to be the case anyway.
To begin the test, separate the plant into its basic components – leaves, stems, buds, roots and flowers and test each part one at a time.
To do that, first smell the plant to try and detect any strong or acidic odours. Throw any away that smell highly acidic. During the 8 hours you abstain from eating, test for contact poisoning by placing a piece of the plant part you’re testing on the inside of your elbow or wrist. 15 or 20 minutes are usually enough to allow for a reaction. During this period take nil by mouth except purified water and the part of the plant you’re testing.
Select a portion of the plant part and prepare it in the way you plan to eat it. Before placing a tiny amount of it in your mouth, place it on the outer surface of your lip to test for burning or itching. If there’s no reaction after a few minutes, place the piece on your tongue and hold it there for 15 minutes. Don’t swallow it yet!
After 15 minutes have elapsed, if you feel no sensation of burning, numbing, itching stinging or any other irritation, then you can swallow it. Wait 8 hours and if you feel any ill effects, induce vomiting and drink lots of water. If no effects occur, prepare a cup sized portion of the plant part the same way, eat it and then wait another 8 hours. If, after that time, there’s still no reaction or effects, then it’s highly likely that the plant part is safe to eat.
However, that doesn’t mean the whole of the plant is safe to eat, just the part you’ve tested. This might seem a painstaking method of testing, especially when you’re hungry and in a survival situation but it is better to be safe than sorry.
Do though bear in mind that eating large portions of plant food on an empty stomach can cause cramps, diarreah and nausea so, even after finding the food safe, only eat it in moderation.
To avoid other potentially harmful plants, avoid any wild plants you can’t identify which contain bulbs, beans or seeds inside pods or those with a milky sap. Avoid those with fine hairs, thorns or spines and anything that resembles carrot, parsnip, dill or parsley when you know it isn’t any of those things.
If in doubt, you should always cook the plant but not until you’ve followed the universal edibility test first after which you can boil, bake or steam to improve the flavour.