Pseudevernia furfuracea

Pseudevernia furfuracea, commonly known as tree moss, is a lichenized species of fungus that grows on the bark of firs and pines. The lichen is rather sensitive to air pollution, its presence usually indicating good air conditions in the growing place. The species has numerous human uses, including use in perfume, embalming and in medicine. Large amounts of tree moss is annually processed in France for the perfume industry. Pseudevernia furfuracea is associated with photobionts from the green algae genus Trebouxia. It reproduces asexually by isidia. The ontogeny of isidia development and its role in CO2 gas exchange in P. furfuracea has been investigated.The preferred growing surfaces for P. furfuracea are the so-called 'nutrient poor' bark trees, including birch, pine and spruce. The species has two morphologically identical varieties that are distinguished by the secondary metabolites they produce: var. ceratea Zopf. produces olivetoric acid and other physodic acids, while var. furfuracea produces physodic but not olivetoric acid. Some authors (e.g., Hale 1968) have separated the chemotypes at the species level, designating the olivetoric acid-containing specimens as Pseudevernia olivetorina, but more recent literature separates them at the varietal level. Large amounts of tree moss (approximately 1900 tons in 1997) are processed in Grasse, France for the perfume industry. In ancient Egyptian embalming, P. furfuracea was found packed into the body cavity of mummies, although it is not certain whether this was done because of the supposed preservative properties or the aromatic properties of the lichen. Soluble extracts from P. furfuracea var. furfuracea and var. ceratea, as well as specific compounds found therein, have antimicrobial activity against a variety of microorganisms. In Alfacar and Viznar, Andalucia (Spain), P. furfuracea is used for respiratory complaints. The thallus is washed and boiled for a long time to prepare a decoction which is drunk. Water extracts of this species have been shown to have a potent protective effect on genotoxicity caused by bismuth compounds such as colloidal bismuth subcitrate.