Inner City Reforestation in Utrecht and the G/Local Amazon; Psychogeography is involved.
The yellow one has a beautiful name:Xanthoria Parietinahttp://en.wikipedia.org/wiki/Xanthoria_parietina
Wilfried those are some extraordinarily beautiful pics. I love to photograph lichen too and have brought lichen samples home for my kids to view under our computer microscope. My favorite professor is a botanist and lichen specialist. So please humor and forgive my pedantic correction. I must defend the honor of the fair lichen. ...lichens do not cause plant damage. The lichen symbiosis is not damaging bark in any direct ways. It does not rob bark of significant amounts of moisture. The fungal symbionts of the lichen do not parasitize living plant cells, and lichens do not appear to be associated with providing entrance ways for pathogens into plant tissue. So why do so many people, including many horticulturists, think lichens damage plants? Perhaps it is because when branch decline occurs due to other factors, lichen growth sometimes proliferates. This is due to increased sunlight that penetrates to the bark which favors the algae that are photosynthesizing, resulting in enhanced growth. The lichens did not cause the branch decline, but rather, one of the effects of the plant decline was an increase in lichen growth. http://ohioline.osu.edu/sc195/029.html