Did you hear the one about the fungus and the algae?
They took a “lichen” to each other.


Lichen comes from the Greek leiko to lick or lick up, a habit of the “plant” to lap its tongue all over the host. However, “lichen” may come from the Greek “leprous, wart or eruption,” as Dioscorides thought they resembled the skin of afflicted people, and used the Doctrine of Signatures as an attempted cure. The French scientist, Tournefort named them around 1700 AD.

Lichens are a slow growing symbiotic combination of fungi and algae. As such, they do not completely resemble either group, but have their own beautiful and distinctive look. One lichenologist called lichens “fungi that have discovered agriculture” in reference to their symbiotic relationship. There are 42% lichenized, and 58% non-lichenized fungal species within Ascomycota (Lutzoni et al., 2001).

Lichen fossils have been discovered dating back to the Devonian period, some 400 million years ago. For a long time, it was believed the relationship was symbiotic. Many scientists now think, following laboratory study, that the fungus is really  a parasite. When lichens were experimentally separated in labs and grown apart, the algae grew more quickly and the fungus more slowly. However, when the two join forces, they can survive where neither would make it on its own. In fact, scientists could get them to rejoin only when conditions would not support them separately. Strange bedfellows indeed!

When this idea of two organisms living together was first proposed, it was considered quite radical. Mordecai Cooke denounced this dualism as “unqualified romance, which a future generation will contemplate as fairy tales.” Simon Schwendener wrote in 1869, “This fungus … slaves are green algae, which it has sought out or indeed caught hold of, and compelled into its service. It surrounds them, as a spider its prey, with a fibrous  net of narrow meshes, which is gradually converted into an impenetrable covering, but while the spider sucks its prey and leaves it dead, the fungus incites the algae found in its net to more rapid activity, even to more vigorous increase.” The term helotism, suggesting a master-slave relationship, best describes lichens, according to this ancient dictum. I prefer to see them as whole organisms instead of resorting to reductionist redundancy. They have the ability to grow in the coldest, snow-free alpine and boreal forest, often growing less than a millimeter a year. Lichens have been found growing on rocks just 264 miles from the South Pole! It is estimated some 14,000 lichen species inhabit our planet. Lichenographs, or printed illustrations were first published in 1480. Linnaeus was not keen on lichens, and called them “Iceland moss,” Cetraria islandica subspecies Crispiformis, courtesy of Stephen Sharnoff. Rustici pauperrimi, or the poor trash of vegetation. These tiny powerhouses, have a history of being under-estimated. Due to limited space and the wide range of medicinal lichens, we will look at two of the more well-known genera. My recent book, The Fungal Pharmacy (Rogers, 2011), on medicinal mushrooms and lichens contains more information on these valuable members of the Kingdom Fungi.


At the top of the list is the genus Usnea, often referred to as “old man’s beard.” It was first mentioned in the Formulary of Al- Kindi around 850 AD, as a treatment for swollen spleen.
In early Greece Usnea was recommended by Hippocrates and Dioscorides for uterine issues. The Chinese have used Usnea species for thousands of years as expectorants, and for colds and flu. Energetically, this lichen has a cold, bitter nature that helps clear heat and remove toxins.

In my region of northern Canada, the Blackfoot call Usnea E-SIMATCH-SIS, and the Cree MITHAPAKWAN. Various First Nations used the disinfectant tree lichen for diapers, wound dressings and sanitary napkins. Identification of green-grey Usnea species hanging over other tree lichen is made easier if you locate the unique central white elastic cord. The outer cortex contains antibiotic and anti-fungal substances, particularly usnic acids, while the white inner core contains immune-modulating polysaccharides. Work in Iceland has found Usnea effective against gram-positive bacteria such  as Streptococcus (strep throat), Staphylococcus (impetigo), and Mycobacterium tuberculosis (Ingólfsdóttir, 2002).

Usnic acid is strongly anti-fungal and used in various forms for ringworm, athlete’s foot and tinea versicolor. The mode of action is quite different from standard prescription antibiotics.
Usnic acid is more effective against some bacterial strains than penicillin. It is able to completely inhibit the growth of different strains of human tuberculosis in dilutions of 1:20,000. Other studies cite its effectiveness at one part per million, similar to streptomycin.

Microbes like the tubercle bacterium form heavily waxed coats and stiff cell walls that allow them to persist and even divide inside macrophages. They are able to prevent the host’s lyosomes from taking in the hydrogen ions needed to create an acidic environment, thus neutralizing them. Drug resistant TB is presently undergoing a worldwide resurgence that one WHO health official described as “the most frightening situation I have ever encountered.” Honda (2010) looked at a variety of lichen constituents and activity against tuberculosis. Usnic acid ranked third, behind norstictic acid and the most powerful, diffractaic acid. Synthetic antibiotics resemble the cell wall building blocks of bacteria, and are incorporated in the cell. This results in a weak cell structure, as the bacteria swell and burst.

Usnic acid has a different mode of action. Scientists believe usnic acid disrupts cellular metabolism, either by preventing ATP formation, or by uncoupling oxidative phosphorization. Either way, the cells run out of energy and die. Usnic acid disrupts the mitochondrial membrane in human breast and pancreatic cancer cell lines (Einarsdóttir et al., 2010).

Weckesser et al. (2007) found Usnea species active against Propionibacterium acnes, Corynebacterium species, and most importantly MRSA, or methicillin-resistant Staphylococcus aureus. Usnea may be superior to Flagyl™ (metronidazole) in treating Trichomonas, a parasite that causes serious uterine and cervical infection, and tissue destruction. It is useful for fungal candidiasis, and giardia, or “beaver fever,” as it is known, as well as bowel inflammation in general. Usnea is a relaxant of the smooth muscles of the body, including the colon and lungs.

Herbalists use Usnea tinctures for tuberculosis lymphangitis. Kahlee Keane, noted herbalist, even suggests Usnea as a heartworm medicine for wolves!

Usnic acid disperses poorly in water. It is somewhat soluble in alcohol, but is best in oil. For internal use, prepare a 1:2 tincture with 95% alcohol. A one to five ratio may be heated in a crockpot with organic olive or canola oil to create a healing salve for infected boils, impetigo, ringworm or athlete’s foot. Use coconut oil as the medium to prepare a vaginal bolus for trichomona infections. Use only living Usnea to make medicine; Usnea is contraindicated during pregnancy.


Iceland moss
Iceland moss (Cetraria islandica) is a green-brown lichen that attaches to rocks in sub-alpine and northern forests. In Iceland, it is called fjallagros. In the first written laws from 1280 AD in Iceland, it was forbidden to pick the lichen on another’s land. Bread moss, or brodmose, is a Scandinavian name for its use in extending wheat flour or potatoes in time of famine. Other names are matmasa or “food moss” and svinmasa meaning “swine moss.” It was traditionally soaked in 2% birch ash to decrease the lichen acids and mixed in porridge, jellies, and bread. Today, it is added to luncheon meats and various pastries to retard spoilage.


Historically, Iceland moss has been used to manufacture antibiotics to inhibit tuberculosis; one kg of antibiotics results from 40 kg of plant material. In Finland, an anti-fungal cream called USNO is made, for treating athlete’s foot and ringworm. The lichen entered the Finnish Pharmacopoeia in 1915. In Switzerland, Iceland moss is used for sore throat pastilles, and as an additive to luncheon meats and pastries to retard spoilage.

Iceland moss is a nutritious and soothing tonic, with slight laxative effect. It helps improve the appetite and digestion of the elderly and those recovering from a debilitating illness. The bitter principles benefit the stomach in both, tincture and infusion form, stimulating appetite, through increasing the production of saliva and gastric juices. It can be used, like queen of the meadow (aka meadowsweet, an herb known scientifically as Filipendula ulmaria), for both hyper and hypo- acidic stomach conditions. Decoctions are used for chronic diarrhea and respiratory problems. Like lungwort, it increases the flow of breast milk, but not with inflamed or sore breasts. Symptoms caused from low thyroid and anemia benefit from the trace levels of iodine, iron, and other nutritive elements in Iceland moss.

Dr. King’s American Dispensatory (1875) is a classic of eclectic herbal medicine. King wrote that the lichen was “used as a demulcent in chronic catarrhs, dysentery, and diarrhea, and as a tonic in dyspepsia, convalescence and exhausting diseases. Boiled with milk it forms an excellent nutritive and tonic in phthisis and general debility. It relieves the cough of chronic bronchitis.” Lichenan is a polysaccharide similar to beta glucan, found in oats and barley (besides lichens). Lichenan is soluble in hot water, and upon cooling forms a gel; while isolichenan, present in smaller amounts, is soluble in cold water. Work by Stübler and Buchenauer (1996) found lichenan exhibits strong anti- viral activity. It soothes nausea from gastritis and vomiting, and combines well with borage and chickweed leaf for peptic ulcers, hiatus hernia and esophageal reflux. In fact, for those individuals with a yin or fluid deficiency, it would work better than a straight astringent herb. In one open clinical trial, 100 patients with pharyngitis, laryngitis or bronchial ailments were given lozenges containing 160 mg of an aqueous extract of the lichen. There was an 86% positive response with good gastric tolerance and lack of side effects. Perhaps it should be considered in cases of diverticulitis and possibly cystic fibrosis in children. Mild infusions of Iceland moss can be used as a vaginal douche for its soothing, demulcent properties. Tincture form is best for whooping cough, asthma, TB, and kidney/bladder complaints; especially those related to a dry, irritating condition. Here, the sweet, moist and astringent nature of Iceland moss helps address the underlying concern. It may be used for night sweats, but is taken during the day to prevent recurrence. Do not use Iceland moss when an acute fever is present.

In vitro studies have shown protolichesterinic acid to be a potent inhibitor of HIV, the virus associated with AIDS, as well as 5-lipoxygenase (Pengsuparp et al., 1995). Other components, such as polysaccharides, have been found  to stimulate the immune system (Ingólfsdóttir, 1994). The author found polysaccharides comparable to the fungal polysaccharide lentinan (from shiitake) used for clinical cancer therapy in Japan. Ingólfsdóttir (1997) found extracts of Iceland moss to suppress the growth of Helicobacter pylori that contributes to gastric and duodenal ulcers
Protolicheresterinic acid was found by Ogmundsdottir et al. (1998) to be significantly anti-carcinogenic with regards to two types of breast carcinoma and erythro-leukemia cell lines, as well as having anti-inflammatory properties. The ED50 for lobaric acid is between 14 and 44 µg/ml for these three cancer cell lines. Haraldsdóttir et al. (2004) found lobaric acid very effective against a number of human cancer cell lines in vitro.

On a recent visit to Iceland, I noticed Iceland moss everywhere. Not only throughout the beautiful countryside, but in nearly every grocery and health food store.

References cited
Einarsdóttir, E., J. Groeneweg, G.G. Björnsdóttir, G. Harethardottir, S. Omarsdóttir, K. Ingólfsdóttir, and H.M. Ögmundsdóttir. 2010. Cellular mechanisms of the anticancer effects of the lichen compound usnic acid. Planta Medica 76(10): 969-974.
Haraldsdóttir, S., E. Guolaugsdóttir, K. Ingólfsdóttir, and H.M. Ogmundsdóttir. 2004. Anti-proliferative effects of lichen- derived lipoxygenase inhibitors on twelve human cancer cell lines of different tissue origin in vitro. Planta Medica 70: 1098–1100.
Honda, N.K., F.R. Pavan, R.G. Coelho, S.R. de Andrade Leite,
Micheletti, T.I.B. Lopes, M.Y. Misutsu, A. Beatriz, R.L. Brum, and C.Q.F. Leite. 2010. Antimycobacterial activity of lichen substances. Phytomedicine 17(5): 328-332.
Ingólfsdóttir, K. 1994. Immunologically active polysaccharide from Cetraria islandica. Planta Medica 60(6): 527-531.
Ingólfsdóttir, K. 1997. In vitro susceptibility of Helicobacter pylori to protolichesterinic acid from the lichen Cetraria islandia. Antimicrobial Agents and Chemotherapy 41(1): 215-217.
Ingólfsdóttir, K. 2002. Usnic acid. Phytochemistry 61: 729-736. King, J. 1875. King’s American Dispensatory. 10th Ed. Wilstach,
Baldwin & Co. Cincinnati, OH.
Lutzoni F., M. Pagel, and V. Reeb. 2001. Major fungal lineages are derived from lichen symbiotic ancestors. Nature 411: 937-940.
Ogmundsdottir, H.M., G.M. Zoega, S.R. Gissurarson, and K. Ingólfsdóttir. 1998. Antiproliferative effects of lichen derived inhibitors of 5-lipoxygenase on malignant cell lines and mitogen-stimulated lymphocytes. Journal Pharmacy and Pharmacology 50(1): 107-115.
Pengsuparp, T., L. Cai, H. Constant, H.H.S. Fong, L.-Z. Lin,
Kinghorn J.M. Pezzuto, G.A. Cordell, K. Ingólfsdóttir,
Wagner, and S.H. Hughes.1995. Mechanistic evaluation of new plant-derived compounds that inhibit HIV-1 reverse transcriptase. Journal of Natural Products 58(7): 1024-1031.
Rogers, R.D. 2011. The Fungal Pharmacy: The Complete Guide to Medicinal Mushrooms and Lichens of North America. North Atlantic Books. Berkeley, CA.
Stübler, D., and H. Buchenauer. 1996. Antiviral activity of glucan lichenan poly- beta 1-3, 1-4D-anhydroglucose.
Biological activity in tobacco plants. Journal of Phytopathology 144(1): 37-43.
Weckesser, S., K. Engel, B. Simon-Haarhaus, A. Wittmer, K. Pelz, and C.M. Schempp. 2007. Screening of plant extracts for antimicrobial activity against bacteria and yeasts with dermatological relevance. Phytomedicine 14(7-8): 508-516.


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