Doctrine of signatures

Last week I sent off a chapter for a proposed book on gardening during Covid-19 and assuming it is accepted I’ll have my head down writing the remaining chapters over the next few months. So, no time for lengthy blog essays but as part of the research for this book I’ve been reading about folk medicine and the use of plants to treat plague victims in history. Some of these plants are in my garden and I decided to have some fun exploring the language of plants, otherwise known as the doctrine of signatures. This is ancient system or art of knowing from the outer appearance of a plant or its environment what its medicinal properties are. Reading its colour and shape is apparently an indication of what it heals. In other words, form points to function – the physical characteristics of plants reveal their therapeutic value. My Calendula, otherwise known as Calendula officinalis is in full bloom at the moment and will probably flower all summer. The Romans called the first day of a month the calendae and Calendula flowered so abundantly in Roman gardens that it seemed to be in bloom on the calendae of every month, and so it merited the name Calendula.
Calendula features in the doctrine of signatures because of its colour and as a member of the sunflower and daisy family – the compositae.



The doctrine of signatures is an idea found throughout the world and is alluded to in classical Greek literature. Dioscorides, for example, wrote “.. the Herb Scorpius resembles the tail of a scorpion and is good against his biting.” Personally that’s one signature I wouldn’t put my trust in it!
Paracelsus was the greatest proponent of the doctrine of signatures. He believed that God provided signs within plants to indicate their uses: “the soul does not perceive the external or internal physical construction of herbs and roots, but it intuitively perceives their powers and virtues and recognizes at once their signatures.” Paracelsus is known as the father of modern medicine but he was also an alchemist and there is a long history in western plant signatures of a correspondence with mysticism and alchemy. However, exploring these connections is for another time.

The doctrine of signatures was, however, frequently used in herbal medicines during the Renaissance and was espoused by the famous Nicholas Culpeper who wrote “… by the icon or image of every herb man first found out their virtues.”

Today, many consider it a fanciful, primitive and unreliable system although occasionally a remedy is found to be true. Kreig, for example, in 1964 referred to willow bark’s efficacy in treating rheumatic pains, noting “at least one of these quaint beliefs had a fragment of truth in it.”

I lean more toward the late Stephen Jay Gould’s approach. He wrote: “I question our usual dismissal of this older approach as absurd, mystical or even prescientific … how can we blame our forebears for not knowing what later generations would discover? We might as well despise ourselves because our grandchildren will, no doubt, understand the world in a different way.”

One of the things it is impossible to ascertain is, when healers in traditional cultures first learned of the value of medicinal plants, did signatures influence their plant selection? And if they didn’t, then what did?
If the doctrine of signatures was a ubiquitous method of choosing medicinal plants then plants bearing signatures should be more widely used than those lacking a signature. But this isn’t the case. It is possible that many valuable herbs were in use before the doctrine and matches between ailment and plant were made later either as an aid to memory or to validate the doctrine. Many plants that lack signatures are used for the same purpose as those that have signatures while many species with obvious signatures are not used medicinally.

However, many plants that bear signatures are efficacious. Purslane, for example, is effective in controlling intestinal parasites and it is likely the plant’s resemblance to worms helped healers to remember and pass on this knowledge. The same is true for Eyebright, which can be used to effectively treat conjunctivitis.



Calendula officinalis has been used over the centuries for a variety of medicinal purposes and became a staple of British cottage gardens. Its leaves and flowers were used as a mild stimulant, to prevent or treat fever, for skin diseases, to cause sweating and to ease muscle cramps. In the old herbals Calendula has many other names: As the sponsa solis, it is the spouse of the sun, and solaris herba, the sun’s herb. Another of its names, Vertamnus, is the name of a shapeshifting Etruscan and the Roman god of gardens and orchards, seasons, change and plant growth.

Willima Coles (1654) considered the orange-yellow of Calendula flowers a signature for their action in jaundice. As a member of the compositae family of sunflowers and daisies the Calendula is known as herbal sunshine and is thought to bring a sense of inner centeredness and joy, a sunny mood. Here’s hoping!

Its petals have been used in cooking and were once used as yellow colouring in cheeses and butters. When used in stews and salads the petals add a spicy taste similar to saffron. I haven’t tried them in stews but often add the petals to salads mostly for the colour. Calendula is also said to stimulate the immune system and is used as an ingredient in many cosmetics. In the vegetable garden it is said to draw aphids away but I haven’t been able to find any proof of this.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s