The Universal Edibility Test

There’s no room for error when consuming wild plants. It only takes a few nibbles of a poisonous one to lead to dangerous, life-threatening consequences.

It’s always best to have a local edible plant guide at hand or an expert with you who’s skilled at foraging wild plants before touching or eating any wild plant. But, if you ever find yourself in an emergency situation, the universal edibility test is a survival skill that can help determine if a plant is safe for consumption.

The U.S. Army created the Universal Edibility Test to help soldiers identify poisonous vs. edible plants while out in the field. The test is a standard in the U.S. Army Survival Field Manual ATP 3-50.21, and it appears in the SAS Survival Handbook written by former British Army officer and survival expert John Wisemen.

Today, the universal edibility test is used to teach survival skills to foragers, hikers, and outdoor enthusiasts alike.

Larkspur causes skin irritation and can severely upset the digestive tract.

Step-by-Step Guide

STEP 1: FAST

From start to finish, the test will take 24-hours to complete.

It’s best to refrain from eating for at least eight hours before you begin the test. Doing this will ensure that any reaction you experience is from the plant, and not something you may have eaten before.

STEP 2: DIVIDE THE PLANT

You’re going to want to test each part of the plant separately. Most plants include five key parts: buds, flowers, leaves, roots, and stems.

It’s important to divide the plant into parts because with certain plants there may be sections that are safe to digest while other sections are poisonous. Like rhubarb, for example. On a rhubarb plant, the stem is safe to consume but the leaves contain a high level of toxic oxalic acid which can lead to kidney failure if eaten in high quantities.

Before you get started, ensure there is a generous amount of the plant you've chosen to warrant the time and dedication required to perform the edibility test.

To test each part of the plant first break it apart:

• Peel back the leaves
• Pull out any fruits
• Separate the roots, stems, leaves, buds, seeds, etc.

Then, organize the plant into groups based on its different sections. You can lay them out on a table or nearby rock to better study each part.

As a rule of thumb, most plants that are brightly colored, discolored, or have a milky or yellow-hued sap coming from them when broken apart are not safe to eat. Also, keep a lookout for any signs of worms or parasites. This will mean the plant is rotting and you’ll need to grab a new plant (whether it’s a different bushel entirely or one of the same variety).

STEP 3: SMELL

With this step, keep in mind that the scent of a plant is not always a credible indicator of whether it’s edible or not. However, it’s still important to smell the plant as there are a few telltale signs that hint at ones you should stay away from.

Check for acidic odors or other strong, foul smells, and pay special attention to if the plant has a musty or moldy scent. These are all red flags. Also beware if the plant smells like pears or bitter almonds. This is a sign it contains cyanide, a deadly toxin. 

STEP 4: SKIN REACTION TEST

Perform a contact-poison test to see how your skin reacts to the plant.

Select the part of the plant you’re considering eating. Then, crush it and rub its juice on your palm or forearm. Or, place the juice and the plant part against your wrist or inside of your elbow and hold it there for at least 15 minutes.

Then, wait for around eight hours to see if a reaction develops (this step can be done during fasting—step 1). You can drink water during this time but refrain from eating anything.

If you experience blistering, burning, itching, soreness, or swelling, you should discard the plant and wash the area and your hands immediately with soap. If you have an over-the-counter cream like Benadryl or Cortisone, apply that.

If you don’t have any creams, then wet a rag in cold water and compress it against the area. Some reactions fade within a few hours while others can take about a week to clear up.

If you don’t experience any side effects after 8 hours, move on to step five.

Rash caused by Wild Parsnip

STEP 5: COOK THE PLANT

Now it’s time to get the plant ready to eat.

Select a small portion of the plant part and cook it using your preferred method (i.e. boiling, pan-frying, sautéing, etc.)

Though some plants can be eaten raw, there are a few different reasons why it’s a better idea to cook them, if you can. First off, some poisonous plants are safe to eat after being cooked. Also, raw plants are harder on your digestive tract and can cause stomach upset, especially if you’re not used to eating raw, wild plants.

STEP 6: MOUTH REACTION TEST

Take a small part of the prepared plant and test it on the outside of your lips to see if you experience any itching, burning, or swelling. Hold it there for at least three minutes.

If you’re still reaction-free once the three minutes have passed, set the same part of the plant on your tongue and keep it there (without swallowing or chewing!) for a minimum of 15 minutes.

If you experience any sort of reaction, then set the plant aside and rinse your mouth, lips, and hands and tally that one up as a loss.

Start back at the beginning with a different part of the plant.

4 poisonous plants that will affect your digestive tract: Manchineel, Elderberry, Daffodil, Water Hemlock (left to right)

STEP 7: CHEW

If after 15 minutes you haven’t experienced a reaction, chew the plant part thoroughly (again, don’t swallow!) and then hold it in your mouth for another 15 minutes.

Watch for any signs of burning, itching, or numbness.

STEP 8: SWALLOW

If the 15 minutes are up and you still aren’t experiencing any negative reactions or side effects (i.e. numbness, itching, burning, or irritation of any sort), then swallow the bite.

You’ll need to wait at least eight hours to give your body time to adequately digest the plant to determine if it has any ill effects on your body.

If you experience illness of any sort, then you need to rid your body of the poisonous plant as quickly as possible by forcing yourself to vomit and flushing your body by drinking a lot of water.

STEP 9: TEST AGAIN

You’ll need to wait at least eight hours before beginning the test over again with a different part of the plant or a new plant.

If you don’t experience any side effects, then prepare the plant in the same manner as before and eat about ¼ cup (equivalent to filling the palm of your hand.) After eating the larger amount, wait another eight hours. If the larger portion of the plant goes over well, then you’ll know that plant parts safe to eat.

Each section of the plant needs to be tested using this sequence. The test is a time-consuming process. But, in the end, it’s better than the alternative!

Dandelion is an edible plant

Common Poisonous Plant Symptoms

When eating wild plants always do so slowly and in moderation.

Some plants aren’t as toxic and may only lead to mild gastro issues or no symptoms at all. But others, even if consumed only in small amounts, have a much higher toxic concentration and can lead to severe reactions, and in certain circumstances, even death.

According to the University of Vermont Medical Center, the most common symptoms experienced from eating a poisonous plant include:

• Development of a rash or blisters
• Muscle weakness
• Dry mouth or extreme salivation
• Sweating
• Burning or irritation within the mouth
• Abnormally quick or slow heartbeat
• Feeling lightheaded or dizzy
• Vomiting, nausea, diarrhea, pain, or other digestive issues
• Difficulty breathing
• Drop-in blood pressure and breathing rate

The major body parts affected by poisonous plants are the gastrointestinal tract, blood, and nervous system, heart, lungs, and skin. Keep in mind that symptoms may be immediate or delayed for up to 24 hours, depending on the toxicity of the plant.

Further severe symptoms include:

• Paralysis
• Seizures
• Collapsing or becoming unresponsive to touch or sound
• Vomiting of blood

Castor Beans contain ricin, one of nature's strongest poisons.

What to Do If Poisoned

1. SEEK MEDICAL HELP

If you believe a plant that you touched or consumed is poisonous, seek medical attention immediately. Professionals say the sooner before symptoms appear, the better. 

When seeking medical attention, it will be very helpful if you can determine the name of the plant you consumed, or, better yet, can safely gather a sample of it.

Here are the most common poisonous plants in the United States.

2. REDUCE POISONING

If you’ve called for medical help, there are a few things you can do while waiting for them to arrive:

• Wash the area of your skin that has touched the plant with soap, detergent, or alcohol immediately, and keep washing for a solid 15 minutes.

• Induce vomiting.

Poison hemlock isn't toxic when touched, but can be lethal if ingested.

Other Ways to Identify a Poisonous Plant

Many poisonous plants share similar characteristics, and knowing what to look for along with a few rules of thumb to remember to avoid poisonous plants.

• Avoid plants with thorns, shiny leaves, black, pink, or purple spurs, and fine hairs on their stems.

• Steer clear of plants that look similar to dill, parsnips, parsley, and carrot leaves. It is easy to confuse these plants with poison hemlock, which can be fatal.

• Follow the “leaves of three, let it be” rule. Most plants with three leaves are bad news.

• Avoid plants with yellow or white berries.

• Plants with beans, bulbs, or pods that contain seeds are often poisonous.

• Look out for plants that have milky or discolored sap.

• Pay close attention to how a plant tastes. If it has a soapy or bitter taste to it, then spit it out and don’t continue eating it.

• Don’t eat plants that smell like almonds or pears. It’s also best to avoid plants that have wood on their stems, leaves, etc., as these are often toxic. 

ADDITIONAL SAFETY TIPS:

• Take a foraging class prior to your backpacking trip.

• In preparation for your trip, devote some time to studying plants in the area you’ll be visiting, and practice determining the different species.

• Keep an edible plant guide book with you so you can be aware of which plants are poisonous by touch, which are poisonous by ingestion, and which are both. Certain plants can cause skin reactions but are still safe to consume once boiled.

• Wear long sleeves and pants when walking through areas of thick brush.

• Do not burn plants if there is any uncertainty about whether they are poisonous.

• Avoid eating mushrooms unless you are 100% sure that the one you’re eating is safe to consume. Many edible and poisonous mushrooms look a lot alike, and it's hard to tell them apart.

• Write down the number for Poison Control (1-800-222-1222) before going on your hike and keep it close by.

Doll’s Eye forms white berries which can cause nausea, diarrhea, and vomiting.