Tree moss

Description:

It 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. 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 it has been investigated. 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.

Habitat:

The preferred growing surfaces for it are the so-called "nutrient poor" bark trees, including birch, pine and spruce.

Notes:

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. Because specimens of P. furfuracea tend to bioaccumulate heavy metals like Cr, Zn, Cd, Pb, Ni, Fe, Mn and Cu proportional to their concentration in airborne particulates, they may be used as a biomonitor of air quality, although it has been noted that both trace metal accumulation and major element accumulation is partly dependent on the hydration level of the specimen. Also, the species is sensitive to ozone concentrations: ozone fumigation results in biophysical, physiological, and structural impairment of specimens. It has also been used to monitor the levels of radionuclides such as Cesium-137 in Austria after the Chernobyl nuclear accident.