For this week's theme, I've found a couple of stamps in my 'collection/stash' which relate to the environment. The above stamps from West Germany, issued in May 1980 are about conservation areas, 'Naturschutzgebiete'. It has a nice cancellation too but I'm not sure of the significance, the place is Ketsch, on the Rhein (wiki link).
The next stamp was issued in 1993 for an international horticultural exhibition in Stuttgart.
I'm linking to Viridian's Sunday Stamps, click on the icon to visit more entries this week.
Thanks for visiting.