Lichens and people

In past centuries it was common practice for some of the European scientific societies to invite essays on particular topics and offer prizes. For its prizes of 1786 the Académie des Sciences, Belles-Lettres et Arts of Lyon invited essays on the subject of the lichens that could be used in medicine and the arts. Prizes were awarded to three essays by Pierre Joseph Amoreux, Georg Franz Hoffmann and Pierre Rémy Willemet.

I will give some examples taken from those memoirs. I have left the species names as they were in 1787 for two reasons. The aim of the list is simply to show the variety of uses to which lichens were put several centuries ago and while there is no doubt which modern species correspond to some of those listed lichens, for others the old name encompasses a group of current species. After each species name I have given translations of some of the observations made by the memoirs' authors.

Having given this list it's important to add that the fact that lichens have been used for many purposes does not mean that they have been effective for all purposes, as indicated by some of the dismissive or doubtful statements made by the three authors. Certainly, the three memoirs are very interesting as social history since they do record what people did and while the authors do describe ways in which various lichens can be used effectively they also record many dubious claims. On the rest of this page I will give some more detail about some of the ways in which lichens have been used effectively and much of the information has come from the sources given in the following reference button.

This website (http://www.lichen.com/people.html) is relevant to anyone investigating human lichen use. The website is largely a compilation from published sources, with the sources given. It is a useful starting point but you would still need to do your own follow-up research to see how reliable any particular claim is.

Dyeing

The list of uses given above mentioned several species from which dyes were obtained and the use of lichens to produce dyes has a long history. Dyeing is also the commercially most valued application of lichens and lichen dyes had high monetary value for many centuries until the discovery of synthetic dyes in the latter half of the 19th century. The DYEING page gives more detail.

Food

There is convincing evidence that, over many centuries, people from many cultures in widespread parts of the world have eaten or drunk lichens or products derived from lichens. However, there is no evidence that lichens have consistently formed a major part of the diet within any society. Some lichens have been seen as delicacies but more often they appear to have been a food of last resort or have been used to eke out other food supplies. Rather than producing a long list of the many species that have been consumed by humans I will confine myself to a few examples which will give you some idea of the range of culinary uses of lichens.

In India a Parmelia species (known in Telugu as rathapu or 'rock flower') has been used as a curry and Lecanora esculenta has been eaten by inhabitants of the Middle Eastern deserts, with suggestions that this was the biblical manna. The evidence for this is weak. Nevertheless the expression manna lichen has been coined as an informal collective term for the small, terrestrial VAGRANT LICHENS of the Northern Hemisphere, though not all have been recorded as being eaten. Two examples of such manna lichens are shown in the photo (right) and you can read more about the subject in the DIYARBAKIR'S HEAVENLY BREAD CASE STUDY.

Cetraria islandica , even though a lichen, has been sold commercially as Icelandic Moss. It has been used as a constituent in broths or gruel and, when dried and ground to meal, mixed with ship's flour to make a bread reputedly less liable to weevil attack. Iceland Moss was also used in other ways, as shown by the following classified advertisement from the Sydney Morning Herald of Saturday of the 18th of April in 1863.

You need to know your lichens. A century ago Cetraria nivalis was considered a species very similar to Cetraria islandica and in the early 1900s Edvard Poulsson, a Norwegian professor of pharmacology, tested both for use in breads suitable for diabetics. About 50% of the carbohydrates of the latter species were digested but the former caused such intestinal disturbances that the experiment was stopped. Cetraria nivalis is no longer considered to belong in the same genus as Cetraria islandica and is known as Flavocetraria nivalis. Those test subjects of the early 1900s must have been expressing a gut feeling about the taxonomic difference. The Inuit of North Canada have been recorded as eating the semi-digested lichen contents within the stomachs of caribou, as a warm, post-hunt delicacy. Alaskan Inuit have found lichens nutritionally useful in an indirect way. Marmot hunters found the animals' burrows by looking for the bright yellow thalli of Xanthoria species, which grow in spots where marmots have urinated or defecated, close to their hidden burrow entrances. Lichens contain carbohydrates and so have been used to produce alcohol at least by the mid 1700s, though on an ad hoc basis. In the 1860s a Swedish professor, Sten Stenberg, improved the process to allow industrial production and put his research into practice by setting up a distillery near Stockholm. It is reported that in 1869 17 Scandinavian lichen distilleries produced 1,120,100 litres of alcohol (and that you could produce a good lichen brandy) but by the end of the century the industry had virtually disappeared. The route from lichen to alcohol was first via a treatment with acid to transform lichenin (a carbohydrate) into glucose and during the Second World War there was industrial production of sugar from lichens in Russia. The incentive to use lichens came from the scarcity of beet sugar and the need to use grain or potato starch for military alcohol production. When compared to the production of beet sugar, the cost of lichen sugar was reported as "quite high". The lichen itself was easily collected and hence close to costless, but the costs associated with the manufacture and transport of the chemicals necessary for treating the lichens were high. As the Russian example shows, during wartime necessity dictates the use of unorthodox or 'uneconomic' materials. During the First World War Germany was blockaded by the opposing forces and so lacked access to many of the materials that had been imported during peacetime. In 1915 Carl Jacobj, professor of pharmacology at Tübingen University, published a pamphlet about the possible uses of Cetraria Islandica and Cladonia rangifera as food or fodder. In an appendix he included some of Poulsson's notes about the preparation of Cetraria islandica bread and I've put a translation into the following boxed paragraph.

Species of Umbilicaria grow on rock, worldwide, and in English the genus is often referred to as Rock Tripe. The species Umbilicaria esculenta is found in east Asia and in Japan, where it is known as iwatake (literally 'rock mushroom'), and has long been eaten. The earliest record of Japanese use seems to be in the 17th century cookery book Ryori Monogatari (Tales of cookery). In the following panel are some later comments, published in 1925, and an illustration from about 1860 showing the gathering of this lichen.

Medicine, poison, perfume - and Egyptian mummies

The list at the start of this page records the use of lichens for the treatment, not necessarily successful, of various ailments, from minor to deadly. Many of the medicinal uses of lichens can be ascribed to the doctrine of signatures. This philosophy had its origins two millennia ago and held that there were divinely placed marks or 'signatures' to indicate the ailments a plant could treat - and in those times plants included lichens. A signature could be a feature that resembled some part of the human body. hence a stringy, fruticose lichen was supposedly good for problems with hair. The thallus of Lichen pulmonarius (now known as Lobaria pulmonaria) was supposed to resemble the surface of a lung and so was good for chest ailments. Alternatively, a signature could be the environment in which a plant grew. Obviously a lichen growing on a skull would be useful for treating problems of the mind, such as epilepsy. The subject of LICHEN CHEMISTRY is vast and lichens do produce a variety of biologically active compounds. For example, many lichen secondary metabolites are antibiotics but equally effective, or more effective, compounds can be obtained more easily from other sources. Lichen metabolites are being investigated for anti-tumour and anti-viral properties but currently few lichens are used medicinally. One of the few is Cetraria islandica which has featured earlier on this page. It has been and is used in the production of pastilles for the relief of various throat and chest ailments. Here is an advertisement from a 19th century Australian newspaper.

In the list near the beginning of this page Lichen vulpinus (now known as Letharia vulpina) was listed as a source of wolf poison. Some people have suggested that the broken glass would be enough to kill a wolf, or that is was necessary to damage the digestive system and render the wolf very sensitive to the lichen. In fact research has shown that the lichen itself is sufficient. The active ingredient is vulpinic acid and poisons meat eaters, is toxic to various insects and molluscs but has no effect on animals such as mice and rabbits.

Lichens are still used today in the manufacture of various perfumes and there is a long history of lichen use in perfumes or cosmetics. Today the major perfume lichens are Evernia prunastri (often called Oakmoss), which grows on oak trees, and Pseudevernia furfuracea (often called Treemoss), which grows on conifers. Lichen extracts act as fixatives and also give the so-called 'bass notes' (or base notes) in a perfume, with floral essences supplying the 'top notes'. In perfumery the bass notes are less volatile, evaporate slowly and so are not perceived until some time after application, perhaps not until a half hour or longer after application. Today it is in perfumes that lichens have their greatest commercial value. It is known that a variety of lichens can cause contact dermatitis reactions in some people and some perfumes containing lichen extracts have caused similar reactions.

In Ancient Egypt, during the New Kingdom (1549-1069 BC) and the Third Intermediate Period (1069-656 BC), lichens were used in mummification and a number of mummies, their body cavities stuffed with Pseudevernia furfuracea, have been found. The source of the lichen is unknown. There is no information about the lichens of Ancient Egypt but Pseudevernia furfuracea has not been found in the country during the past two centuries or so of modern botanical exploration there and it has been suggested the country is too dry to support the species. In past centuries there have been records of the importation of this lichen into Egypt.