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Local lichen quite different from that in Europe, says researcher/expert
Misidentified and not just recently — but for more than 150 years!
It is nothing to do with wanting both the ravula (beard) and the kenda (cunjee) as frequently mentioned in Sinhala parlance but differentiating between the ravula in Sri Lanka and that in Europe.
Erect to pendent, greyish to yellow, fruticose Ramalina species in Horton Plains which are misidentified as ‘Old Man's Beard’ lichen (Usnea barbata). Photos by L.J.M. Wickramasinghe under the Dilmah Conservation Programme
It’s all to do with the ‘Old Man’s Beard’, a common lichen found in abundance not only at Horton Plains but also in many other areas, which has been mistaken for that in Europe, the Sunday Times learns.
And the person who has trudged through Horton Plains peering at the “tangled and tufted strands of beard-hairs” and pored not only over reams of literature but also the microscope is Lichenologist Dr. Gothamie Weerakoon.
Pointing out that for as long as 150 years, the botanical name of Sri Lanka’s ‘Old Man’s Beard’ has been a misnomer, Dr. Weerakoon, a Scientific Affiliate at the Integrative Research Center at the Field Museum of Natural History, Chicago, United States of America, says that it cannot be written off with “what’s in a name”.
Everything is in the name, she underscores, explaining that Sri Lanka’s ‘Old Man’s Beard’ falls under the ‘Ramalina’ genus, while those in Europe are under the genus of ‘Usnea’. Genus is a group of plants that include several or many different species.
“So we need to examine the species present in Sri Lanka thoroughly and taxonomically revise all the ‘Usnea’ species as they could have been misidentified and some may even belong to ‘Ramalina’,” she says.
Dr. Weerakoon’s findings are based on the analysis of more than 250 specimens of Usnea collected between 1987 and 2011 as well as a careful study of the historic collections between 1879 and 1977 from Sri Lanka and their described characteristics in published literature. This had been followed by chemical, morphological and molecular analysis, the identification of which was then confirmed by world-renowned Usnea specialists, Dr. Philippe Clerc and Dr. Yoshihito Ohmura.
In her efforts to separate the strands of the ‘Old Man’s Beard’ in Sri Lanka and Europe, she says that among the Usnea specimens collected between 1879 and 2011, there are no specimens of U. barbata.
Going back in time, she says that the early botanists in Europe correctly named the ‘Old Man’s Beard’ lichen found there as Usnea barbata. Regrettably, Sri Lankans have used the same name here without checking the lichens carefully.
“But, the Sri Lankan ‘Old Man’s Beard’, thought to represent one of the most prevalent and characteristic species especially in the ecosystems of Horton Plains for more than 150 years is different,” she is categorical, adding that although this name fits the lichen’s appearance, the ‘Old Man’s Beard’ in Sri Lanka has a greenish tint to its tangled, tufted beard and is different to the one in Europe.
Dr. Weerakoon says: “Finding the lichen species Usnea barbata in Sri Lanka is just a myth. It is a botanical misidentification. Sri Lanka’s ‘Old Man’s Beard’ is a different lichen genus and family – Ramalina and Ramalinaceae, while the possible species could be Ramalina thrausta or Ramalina usnea.”
Lamenting that almost every newspaper and journal article, book chapter, field guide and scientific publication written about Horton Plains mentions Usnea barbata as the common lichen found there, she urges the correction of this misidentification.
“It is essential to carry out further studies using molecular, morphological and chemical analysis for the correct identification of the Sri Lankan Usnea and Ramalina species, with taxonomic revisions being made in the species names of Usnea barbata (L.) Weber ex F.H. Wigg. emend. Jørgensen et al; Usnea barbata var. ceratina (Ach.) Schaer; Usnea barbata var. dasypoga (Ach.) Fr.; and Usnea barbata var. hirta (L.) Fr., being excluded from Sri Lankan literature.
The recent Lichen Checklist (2010) published in India has excluded Usnea barbata from India, after confirming it as a misidentification, she further explains, pointing out that it is a very common taxon in the Alps and the temperate areas of Europe. Dr. Weerakoon cites lichen specialists who are working on Usnea barbata as confirming that it has not been found in any tropical areas including Sri Lanka. It is restricted to humid, high-elevation forests in Austria, Bulgaria, Czech Republic, Denmark, Estonia, Finland, Germany, Italy, Latvia, Lithuania, Norway, Poland, Romania, Russia, Slovakia, Slovenia, Spain, Sweden, Switzerland and Ukraine. So far, this species has not been recorded in India, Nepal or other South Asian regions.
With Prof. Veranja Karunaratne and his students studying the chemical components of Usnea in Sri Lanka and putting out several publications and Dr. Siril Wijesundara, Prof. Karunaratne, Dr. Patricia Wolseley and Dr. Udeni Jayalal studying Usnea in the Nuwara Eliya district since 1999, Dr. Weerakoon feels that things have moved forward with regard to tropical lichens since 2006 in Sri Lanka.
“There is molecular data available for Usnea and it is possible to compare the morphology with the molecular data. So there is hope that the issue of misidentification of the Sri Lankan Usnea species can be resolved quickly,” she says, adding that the time has come to right the wrong name.
| Organisms with long history of therapeutic use
Lichens, according to Dr. Weerakoon, are some of the most unique organisms on this planet. They are products of a symbiotic association between a fungus and photosynthetic partner, usually an alga, which have evolved together to behave and look like an entirely new being, with almost no resemblance to either partners. Lichens can be found on tree-trunks or rock faces at Horton Plains, Hakgala, Nuwara Eliya, Pidurutalalgala and Samanala Kanda. They cling to trees, rocks and even man-made signboards, fences and boundary markers. Usnea lichens, found all over the world, arise from a symbiosis between fungi from the Ascomycota phylum (often known as Sac fungi) and green alga of the Chlorophyta division. Although widespread, these lichens are highly sensitive to environmental disturbance, especially air pollution such as sulfur dioxide, says Dr. Weerakoon. Known commonly as Usnea lichens, Usnea longissima, Beard moss and Tree moss, they have a long history of medicinal use in Asia, Europe and America, with Christopher Hobbs writing a thorough review titled: ‘Usnea: The Herbal Antibiotic’, the Sunday Times learns. The active constituents being lichen acids (usnic acid C18H16O7 which acts as an antibiotic), polysaccharides (as an immunostimulant), mucilage, anthraquinones (endocrocin-laxative), fatty acids, all the essential amino acids, vitamins and carotenoids, it is valued medicinally for its anti-microbial, anti-fungal, immunomodulating, demulcent, laxative and nutritive actions, she says. “It has a documented history of therapeutic use dating over 3,000 years in Chinese medicine and is approved in Germany to reduce throat and mucous membrane inflammation. With its ability to stimulate the production of mucus, it helps to ease pain from coughs and colds,” according to her. Here are some of its uses as elaborated by Dr. Weerakoon: - Having strong antibiotic traits, this lichen had been used to treat lung and upper respiratory tract infections, whooping cough and dropsy. |