Association of several different lichens on the same substrata always fascinate me. It is a big challenge to identify to species its elements. In the present case I chose a group of three lichen, growing on the bark of the same tree, belonging to three of the biggest lichen genera: Buellia, Lecanora and Pertusaria. This step is quite easy for people used to observe and study lichens, maybe with the exception of the first one, due to the existence of other similar looking genera. I created an observation for each species in this group.