Activity 1


Many creatures depend on plants for their food. Even insects, bacteria and viruses get their nourishment from plants. With so many enemies, plants must have a good defense. Imagine you are the plant and your worst enemy is about to make a tasty meal of your leaves. You can't run away or use a karate kick for defense. What can you do? One way plants fight back is to make poisons. Poisons can warn away enemies by making leaves or fruit taste bitter, or by making the enemy very dizzy or sick.
People eat foods with poisons in them every day, but we have learned ways to prepare foods to make them safe. Cassava, an important food for more than 400 million people in tropical countries, contains the poison cyanide. Cassava is a starchy tuber, like a potato. People usually boil or dry cassava to make it safe. This takes most of the poison out, but a little is still left. In small amounts the poison in cassava is not harmful. Sometimes poisons in plants can be used to treat sickness, if they are taken in tiny amounts or the plants are prepared a certain way. Scientists think that when people eat cassava every day, the tiny amount of cyanide may actually help protect them against certain diseases, like malaria and sickle cell anemia.
For thousands of years people have experimented with plants to find new foods and medicines. Sometimes a person died or became sick from eating a certain plant. People would remember which plants or parts of plants were safe to eat and how to prepare them. This important knowledge has been passed from person to person for centuries. Women who gathered seeds, grew the crops and cooked the meals were often healers who made medicine from plants. You probably have a box in your home filled with recipes collected from family and friends. This is one way we pass along our knowledge about food today.



Watch the 18-minute video of Dr. Fatimah Jackson, an anthropologist who studies plants and people in Africa. Read the Poison Plant Cards to discover the amazing number of poison chemicals in everyday foods. Then find recipes for these plants and create a poison plant cookbook.

What You Need (for each group of 4 students):

  • 8 Poison Plant Recipe Cards copied single-sided (page 6)
  • Cookbooks from home or your school library that include recipes for preparing potatoes, apples, lima beans, rhubarb, cherries, cassava, avocado or things that contain the spice nutmeg.
  • Pencils or colored markers


    Follow the steps below to investigate 8 common but poisonous foods.

    1. In your group, highlight the following on each poison plant card:
    2. From the cookbooks provided, choose a recipe for each plant that sounds good enough to gobble.
    3. Record each recipe on a Poison Recipe Card. Complete the poison control section on each card. Each group should complete 8 different Poison Recipe Cards.



    RHUBARB (Rheum rhaponticum)

    Description: A dark green leafy vegetable with red stems that originated in Asia. The stems have a very sour taste and so are stewed with sugar as a dessert, pie filling, or jelly.

    Fact: During World War I when vegetables were scarce, Americans were encouraged to eat rhubarb. Many cases of poisoning occurred when people ate the poisonous leaves rather than the stems.
    POISON NOTES: The stems are safe to eat, but the leaves contain high amounts of poisonous oxalic acid.

    Symptoms: Eating rhubarb leaves can give you abdominal pain and diarrhea. Large amounts of oxalic acid can cause coma and death.

     WILD CHERRIES (Prunus species)

    Description: Several kinds of wild cherries are found in the woods all over North America. They include chokecherry, bitter cherry, black cherry and pin cherry.

    Fact: Native Americans treated coughs and colds with a tea made from black cherry bark.
    POISON NOTES: Cherry fruit is great to eat, but the leaves, bark, twigs and pits of wild cherries contain dangerous amounts of a cyanide-producing compound. Children are sometimes poisoned by swallowing lots of cherry pits.

    Symptoms: Eating a few cherries with their pits will give you a stomach ache. Big doses of cyanide can cause shortness of breath, spasms, coma and even death.



    POTATO (Solanum tuberosum)

    Description: Potatoes are starchy tubers produced by plants that are members of the deadly nightshade family.

    Fact: Potatoes are one of the most nutritious foods. They supply vitamins, minerals and fiber, no fat and nearly no salt. You could stay healthy on a diet of just potatoes and whole milk.
    POISON NOTES: Potatoes are good for you, but all of the green parts of the potato plant contain poisons called alkaloids. Even the potato tuber can be poisonous when it is left in the light and begins to turn green. Avoid any potato with green skin.

    Symptoms: Eating green potato parts can cause nausea, vomiting, dizziness, weakness and sleepiness. High levels of alkaloids cause a drop in blood pressure and heart rate and can lead to coma.

     AVOCADO (Persea americana)

    Description: Dark green, pear-shaped fleshy fruits that grow on trees and are native to Central America.

    Fact: In the Philippines a piece of the avocado seed is applied to decayed teeth to relieve the pain.
    POISON NOTES: The avocado fruit's flesh is safe to eat. However, the seeds and skin of the fruit and the leaves and bark of the tree are poisonous to cattle, horses, goats, rabbits and other animals.

    Symptoms: Animals who eat the poisonous parts of the avocado can experience loss of appetite and sometimes liver and lung damage.



    LIMA BEANS (Phaseolus lunatus)

    Description: Limas are tropical beans named after Lima, the capital city of Peru. In the U.S. we grow large, white lima beans selected especially because they contain very small amounts of the poison cyanide.

    Fact: The small red lima beans that are grown in Asia contain 20 to 30 times more cyanide than the white varieties.
    POISON NOTES: Boiling lima beans in a pot with no lid releases the harmful cyanide poison as a gas. Eating small amounts of raw, green, sprouted or roasted limas is probably not harmful, but these are not the safest ways to eat the beans.

    Symptoms: Eating too many raw limas can cause abdominal cramping, diarrhea and vomiting. High levels of cyanide prevent oxygen from getting into blood and can cause death.

     APPLES (Malus domestica)

    Description: A round, fleshy, usually sweet fruit that grows on trees.

    Fact: Don't panic. Apples are fine, it's their seeds that can be toxic. So are the seeds of pears, peaches, apricots and plums. Eating the seeds is rarely a problem, unless you eat dozens. The bark and roots are a source of antibiotics for treating bacterial infections.
    POISON NOTES: Apple seeds contain cyanide. Eating a few might give you a stomach ache but shouldn't be dangerous.

    Symptoms: Large doses of cyanide produce abdominal cramping, diarrhea and vomiting and may even cause death.

     Cassava Plant and Root     Nutmeg



    CASSAVA (Manihot esculenta)

    Description: A tough tropical plant grown for its fat starchy roots. The roots are boiled and eaten in soups and stews, or ground into flour and made into dumplings, puddings and breads, and used as a thickener for sauces and pies.

    Fact: Scientists think the tiny amount of cyanide in prepared cassava may actually help people who eat it every day. It may protect them from diseases such as malaria and sickle cell anemia.
    POISON NOTES: Cassava roots contain cyanide but can be made safe to eat by boiling or peeling, grating and washing repeatedly to remove the poison. The little bit of cyanide that remains may actually be beneficial.

    Symptoms: Eating raw cassava can cause abdominal cramping, diarrhea and vomiting. High levels of cyanide prevent oxygen from getting into the blood and may even cause death.

     NUTMEG (Myristica fragrans)

    Description: Nutmeg originated in Indonesia. It is a woody seed with a special covering called mace. Both the seed and the covering are used as spices for flavoring sweet dishes like cookies and eggnog.

    Fact: Ancient East Indian medical books call nutmeg the "narcotic fruit" because it induces sleep and relieves pain. In colonial times in North America, nutmeg oil was put on decayed teeth to relieve pain.
    POISON NOTES: Nutmeg is safe in very small amounts, but eating 1 to 6 tablespoons at on sitting can make you ill.

    Symptoms: Eating nutmeg causes headache, dizziness, nausea and aching muscles.


    Recipe Name __________________________ Number of Servings____

    Cooking Temperature_________ Cooking Time__________



















    Poison Control:

    What parts of the plant should be avoided due to the poison?


    How can a person get rid of the toxins before eating the plant?


    What symptoms can a person look for in case of poisoning?






    1. Put your eight recipes together into a cookbook.
    Look at some of the cookbooks you used for ideas
    on how to organize your book.

    2. Share your cookbook with the rest of the class.



    1. How did people in the past find out if a plant food was poisonous?





    2. Name a plant that has safe and dangerous parts. What parts of the plant are safe? What parts are dangerous?




    3. How does cooking help to make poisonous plants safe?




    4. How do plants serve as both food and medicine?





    Excellent Job!!!!!!!


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