Throughout history, almost all the world’s peoples have identified certain plants growing in their area as having medicinal value. Such plants were highly prized and sometimes traded or passed along to people in other areas.

Traditional methods of gathering plants for medicines often include strong spiritual or ritual aspects; gatherers believe that the plants must be approached in a proper spirit or harvested in a certain way for their healing powers to work.

Identifying and gathering medicinal plants was often done by the same people who gathered plants for food. In many cultures, it was - and is - "women’s work".

Many of the traditional medicinal plants identified by people in one area are now used around the world. Some plants have become staples of modern medicine. Others have fallen out of use, been replaced by other remedies, or been abandoned as ineffective or even dangerous.

How did our ancestors decide that a plant had value as a medicine?
- By close observation of the natural world
- Read More

Throughout history, almost all the world’s peoples have identified certain plants growing in their area as having medicinal value. Such plants were highly prized and sometimes traded or passed along to people in other areas.

Traditional methods of gathering plants for medicines often include strong spiritual or ritual aspects; gatherers believe that the plants must be approached in a proper spirit or harvested in a certain way for their healing powers to work.

Identifying and gathering medicinal plants was often done by the same people who gathered plants for food. In many cultures, it was - and is - "women’s work".

Many of the traditional medicinal plants identified by people in one area are now used around the world. Some plants have become staples of modern medicine. Others have fallen out of use, been replaced by other remedies, or been abandoned as ineffective or even dangerous.

How did our ancestors decide that a plant had value as a medicine?
- By close observation of the natural world
- By fitting plants into a theoretical framework


© 2005, Coalition of Canadian Healthcare Museums and Archives

Opium Poppy, a source of medicines since ancient times.

Royal Botanical Gardens

© Royal Botanical Gardens


Our ancestors identified medicinal plants by observing what happened when people touched or consumed various plants. Someone might notice, for example, that drinking a tea that included a particular plant lowered fever or calmed coughing. It's also likely that people watched what the animals around them did - there's a growing body of evidence that some animals use plants in a medicinal way. Watching animals could also help people identify plants that are poisonous or that alter mood and behaviour.

Our ancestors identified medicinal plants by observing what happened when people touched or consumed various plants. Someone might notice, for example, that drinking a tea that included a particular plant lowered fever or calmed coughing.

It's also likely that people watched what the animals around them did - there's a growing body of evidence that some animals use plants in a medicinal way. Watching animals could also help people identify plants that are poisonous or that alter mood and behaviour.

© 2005, Coalition of Canadian Healthcare Museums and Archives

Castor Bean. The laxative effect of its seeds was noted by the ancient Egyptians.

Coalition of Canadian Healthcare Museums and Archives

© 2005, Coalition of Canadian Healthcare Museums and Archives


Our ancestors did a very good job of identifying plants that had short-term visible effects on a patient. However, there were limits to what they could do.

Sometimes they failed to observe the more long-term internal effects of the plants they used. It's not surprising, since these effects often show up only when the health of a large group of subjects is tracked over a long period of time.

Example: Comfrey (Symphytum officinale) has been used as a healing herb since Roman times, especially to help wounds heal faster. Modern research has discovered that comfrey contains allantoin, a substance that promotes tissue growth and therefore wound healing. However, modern research has also shown that the chemical compounds in comfrey may cause liver damage and cancer, so the plant is no longer approved in Canada for use internally or on open wounds.

Second, they sometimes identified plants as medicinal, based on careful and accurate observation - but of features that were not, in fact, medically significant.

Example: In many cultures, people thought that the outward appearance of a plant could provide clues t Read More

Our ancestors did a very good job of identifying plants that had short-term visible effects on a patient. However, there were limits to what they could do.

Sometimes they failed to observe the more long-term internal effects of the plants they used. It's not surprising, since these effects often show up only when the health of a large group of subjects is tracked over a long period of time.

Example: Comfrey (Symphytum officinale) has been used as a healing herb since Roman times, especially to help wounds heal faster. Modern research has discovered that comfrey contains allantoin, a substance that promotes tissue growth and therefore wound healing. However, modern research has also shown that the chemical compounds in comfrey may cause liver damage and cancer, so the plant is no longer approved in Canada for use internally or on open wounds.

Second, they sometimes identified plants as medicinal, based on careful and accurate observation - but of features that were not, in fact, medically significant.

Example: In many cultures, people thought that the outward appearance of a plant could provide clues to its medicinal use. In Europe, this was called "the doctrine of signatures."


© 2005, Coalition of Canadian Healthcare Museums and Archives

Comfrey

Missouri Botanical Garden

© Missouri Botanical Garden


Dandelion - used to treat jaundice.

Why? Because dandelions are yellow and jaundice gives people a yellow colour.

Coalition of Canadian Healthcare Museums and Archives

© 2005, Coalition of Canadian Healthcare Museums and Archives


Red clover flowers - used as a blood purifier.

Why? Because they are red, the colour of blood.

Coalition of Canadian Healthcare Museums and Archives

© 2005, Coalition of Canadian Healthcare Museums and Archives


Hepatica - used for liver problems.

Why? Because it has 3-lobed leaves and the liver also has lobes.

Coalition of Canadian Healthcare Museums and Archives

© 2005, Coalition of Canadian Healthcare Museums and Archives


There’s now a growing field of study called zoopharmacognosy, in which researchers study how animals in the wild use medicinal plants. For more information, visit: Really Wild Remedies - Medicinal Plant Use by Animals.
There’s now a growing field of study called zoopharmacognosy, in which researchers study how animals in the wild use medicinal plants. For more information, visit: Really Wild Remedies - Medicinal Plant Use by Animals.

© 2005, Coalition of Canadian Healthcare Museums and Archives

Our ancestors sometimes created a theoretical framework - a view of how the world worked and was ordered - that included medicinal plants. For example, the Chinese classed medicinal plants and illnesses (as well as many other things) as yin or yang, opposites that had to be kept in a state of dynamic balance. More about traditional Chinese medicine. Ayurvedic medicine in India developed an organizing principle of five elements. More about Ayurvedic medicine.
Our ancestors sometimes created a theoretical framework - a view of how the world worked and was ordered - that included medicinal plants. For example, the Chinese classed medicinal plants and illnesses (as well as many other things) as yin or yang, opposites that had to be kept in a state of dynamic balance. More about traditional Chinese medicine. Ayurvedic medicine in India developed an organizing principle of five elements. More about Ayurvedic medicine.

© 2005, Coalition of Canadian Healthcare Museums and Archives

This correlation of the physical properties of the world with human temperament and body fluids was first developed in Greece around 400 B.C. Illness, it was believed, developed when the elements got out of balance. Balance - and therefore health - could be restored by consuming foods and medicinal plants that would bolster the weaker humours.

Garlic, for example, was classed as hot and dry. It would therefore benefit someone suffering from an excess of phlegm, but might aggravate the symptoms of someone suffering from an excess of yellow bile.

This correlation of the physical properties of the world with human temperament and body fluids was first developed in Greece around 400 B.C. Illness, it was believed, developed when the elements got out of balance. Balance - and therefore health - could be restored by consuming foods and medicinal plants that would bolster the weaker humours.

Garlic, for example, was classed as hot and dry. It would therefore benefit someone suffering from an excess of phlegm, but might aggravate the symptoms of someone suffering from an excess of yellow bile.


© 2005, Coalition of Canadian Healthcare Museums and Archives

The Four Humours play an important part in Unani Traditional Medicine, which is practiced today in India and across the Arab world.

Coalition of Canadian Healthcare Museums and Archives

© 2005, Coalition of Canadian Healthcare Museums and Archives


In the Middle Ages and Renaissance, medicine was often closely linked to astrology. Medicinal plants were fit into the astrological system, with each plant having a particular heavenly body named as its ruler. Example: Pot marigold (Calendula officinalis), whose flower resembles a sunburst, was thought to be ruled astrologically by the sun. The sun governs Leo, which is associated with the heart. Therefore, pot marigold was recommended for heart problems.

In the Middle Ages and Renaissance, medicine was often closely linked to astrology. Medicinal plants were fit into the astrological system, with each plant having a particular heavenly body named as its ruler.

Example: Pot marigold (Calendula officinalis), whose flower resembles a sunburst, was thought to be ruled astrologically by the sun. The sun governs Leo, which is associated with the heart. Therefore, pot marigold was recommended for heart problems.

© 2005, Coalition of Canadian Healthcare Museums and Archives

Pot Marigold

Missouri Botanical Garden

© Missouri Botanical Garden


Learning Objectives

The learner will:
  • demonstrate an understanding of how our ancestors discovered medicinal plants;
  • describe how our ancestors identifies medicinal plants and the limits to their methods.

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