Onosma tornense grows in the area of Slovenský kras in the vicinity of the village of Turnianske Podhradie where there is a protected habitat of 14 hectares on the castle hill. (It is otherwise to be found in the contiguous area of Hungary.) It is fully protected as a very rare species and its occurence is completely - or almost completely - limited to Slovakia. It grows nowhere else in the world. It is listed in the Red Book of the International Union for the Conservation of Nature and Natural Resources as a flower of Slovakia.

In addition to portraying the protected plants in question, stamps in this series also feature the emblem of the European Nature Conservation Year.