The lichen Hypogymnia physodes is very common in Germany. It grows on trees bark with a low pH or on trees grown on silicate soils. This specimen was grown on an old stup.
The lichen has no fluorescence or color changes under ultraviolet light, like other lichen.
Hypogymnia physodes in ultraviolet light (254 nm).
Lichens are small chemical supermarkets. The constituents are called lichen acids and can involve more than 600 different chemicals. This is the lichen acid of the Hypogymnia physodes lichen extracted by micro-sublimation. It is made of small white crystals in polarized light.