The Mugwort Chronicles

July 1st, 2012

Lungwort and the Doctrine of Signatures

Several weekends ago our apprenticeship class from the Arctos School ofherbal and Botanical Studies went on an awesome hike to check out a young forest near the Clackamas River in Oregon. The area had been logged about fifty years earlier, and the Douglas Firs (Pseudotsuga menziesii) were slowly making a comeback. What I found most exciting was that the trees were COVERED with an abundance of Lungwort-Lobaria pulmonaria.


There are many plants with which I enjoy a deep relationship; however, Lungwort is definitely one that joyfully and powerfully sings to my heart. There is just something about the vibrancy of its nearly iridescent green colour, its substantial, fleshy structure and textured shape which makes Lobaria Pulmonaria appear magical to me, as if it was truly breathing.


It is important to make the distinction that this Lungwort is Lobaria pulmonaria- the lichen (also known as Sticta pulmonaria in older texts), and NOT the Lungwort Pulmonaria officinalis- the herbaceous perennial of the Boraginaceae family. Although they have similar uses medicinally, they belong to two entirely different plant kingdoms.


The lichen Lungwort is also known by several other common names including Longwort Moss and Lungmoss, emphasizing the importance of always including the taxonomic name when discussing plants. Not only does this avoid confusion, but it just may prevent a serious error in plant medicine use, as well.



Lichens are unique organisms- a partnership between fungus and alga, enabling it to live in situations where neither fungus nor alga alone could exist. The fungus protects the more delicate alga from drying out and the alga provides nutrients to the fungus through photosynthesis. Many lichens contain green algae, but Lungwort also contains a nitrogen-fixing cyanbacterium, a blue-green alga. Often found on the bark of trees, when Lungworts are blown down during storms, they decompose on the forest floor, enriching the soil with nitrogen.


Lungwort can be found in North America, Europe and Asia. Highly sensitive to pollution, L pulmonaria numbers have declined in many parts of the world and are considered endangered in some areas of Europe. Here in our humid Pacific Northwest forests, Lungwort can often be seen in large numbers, especially in areas of older growth.


When wet, Lungwort’s top surface is bright green with a smooth cream coloured underside. Its pliable, almost rubbery ridged and pitted lobes appear similar to lung tissue.  When moisture is unavailable, Lungwort will look pale and brittle, becoming dormant via a process known as poikilohydry. When rains return, the renewed moisture allows Lungwort to begin photosynthesizing once more.



L Pulmonaria has long been used to treat respiratory conditions including bronchitis, chronic asthma, croup and pertussis (Whooping Cough). The dried frond is usually made into either an infusion or a tincture and is often combined with other respiratory herbs.  Lungwort’s action is considered antimicrobial and expectorant (Tilgner).  It has also been used to make dyes and as a replacement for Hops (Humulus lupulus) to flavor beer.


It is Lungwort’s similarity in appearance to lung tissue which may have led to its discovery for treating respiratory ailments. According to the doctrine of signatures, the usefulness of plants for treating specific conditions could be determined based on certain characteristics of the plant such as leaf shape, colour as well as resemblance to body parts.  For example, St. John’s Wort (Hypericum perforatum) was considered useful for treating skin problems as the holes in the leaves resembled pores in the skin. Although popularized in Europe during the 1500’s, the theory of signatures has much earlier beginnings.


In ancient China, plant colour and flavor helped to determine which organs would benefit from certain plants. For example, plants which were red and bitter were considered useful for treating the heart, while plants that were green and sour were good for the liver.


The basic concept of signatures can be found in the writings of the Roman physician Galen (129 AD- circa 200 AD). Philippus von Hohenheim (1493-1541), a German-Swiss physician better known as Paracelsus, further developed the doctrine of signatures, helping to popularize it within Renaissance Europe’s medical community.


In the first half of the 1600’s, a German shoemaker name Jakob Böhme had a mystical vision in which a divine relationship between plants and healing was revealed to him based on the color of the flowers, the shape of the leaves and where the plants grew. In 1621, Böhme wrote of his revelations in “Signatura Rerum; The Signature of all Things”.


The theory of signatures continued through the works of Nicholas Culpepper, William Cole in 1657 (“Adam in Eden”) and into the twentieth century in Ben Charles Harris’s book, “The Complete herbal” (1972).


Undoubtedly, signatures played an important role throughout time in learning and remembering plant medicine associations. As a method for determining medicinal use of plants, the doctrine of signatures is often considered nothing more than coincidental by today’s scientific community. However the theory’s influence can still be found in contemporary plant therapies such as the Bach flower remedies.



I am fascinated how the signatures really do seem to relate to Lungwort’s healing properties. Not only do the structures of this wonderful lichen look like lung tissue, but the lush forest in which it grows encourages deep healing breaths.


As an herbalist, I would love to make medicine from L pulmonaria, the lichen which calls so strongly to me. However, there are more readily available plants that work quite well for any respiratory problems that I encounter, many growing right in my own herb garden. I prefer to leave this lovely jewel to work its healing magic where it proliferates: in our sacred forests.


This information is offered for educational purposes and is not intended to take the place of personalized medical care from a trained healthcare professional. The reader assumes all risk when utilizing the above information.



Copyright© 2012 Louise Harmon

All Rights Reserved


Bergner, P. (2001). Respiratory-acute and chronic case studies. Medical herbalism   

        2(6):1, 4-5. Retrieved from

Accessed 9 June 2012


Gibson, A. Doctrine of signatures. Retrieved from   ndex.html

Accessed 9 June 2012

Lepp, H. (2011). Lichens and people. Retrieved from

Accessed 6 June 2012


Tilgner, S. (1999). Materia medica. Retrieved from

Accessed 9 June 2012


US Forest Service. Celebrating wildflowers: lichens. Retrieved from

Accessed 9 June 2012


Wikipedia. Doctrine of signatures. Retrieved from

Accessed 9 June 2012


Wikipedia. Lobaria pulmonaria. Retrieved from

Accessed 7 June 2012


Wood, M. (2011). The doctrine of signatures. Retrieved from

Accessed 11 June 2012


For more information regarding workshops or the apprenticeship program at Arctos School of herbal and Botanical Studies located in Portland, Oregon, please visit their site:


4 Responses to “The Mugwort Chronicles”

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  2. Laurieon 23 Jul 2012 at 4:29 pm

    I really enjoyed the practical and historical information that the mugwort chronicles provide. Keep up the good work

    Laurie V

  3. Deborah Rumbergeron 25 Aug 2012 at 8:58 pm

    I loved your article on lobaria pulmonaria! Your love of nature is so refreshing.

    I recently read that three species of lichen were recently identified that degrade the prion protein (PfP) in research animals infected with TSE (transmissible spongiform encephalopathies, such as mad-cow disease). The lichens species are: Parmelia sulcata, Cladonia rangiferina and Lobaria pulmonaria. I read that the last one, also known as lungmoss or oak lungs (sometimes inaccurately confused with lung wort), is used in India for eczema. I also read that “a hot-water extract prepared using this species has been shown to have anti-inflammatory and ulcer-preventing activities. Also, methanol extracts were shown to have a protective effect on the gastrointestinal system of rats, possibly by reducing oxidative stress and reducing the inflammatory effects of neutrophils.”

    I asked my naturopath recently about using this lichen medicinally to treat my child’s health conditions that are related to prions (we’ve been told) and eczema and nausea. She was open to the idea, but I’m still looking for a place to purchase some.

    I’m curious to know your thoughts on the potential medicinal value of lobaria pulmonaria, as a nurse interested in herbs and as a student of botanical studies. If you care to share. My interest stems primarily from being a mother with a sick child. At the same time, I love moist, green, lush forests. (Alas, I am living in Montana, where rainforests are in short supply!) I was fortunate to visit the Olympic Penninsula once upon a time, before our family got sick from toxic mold and all the health problems that developed as a result. Anyway, hope to hear from you!

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