On Biodiversity Day on 22 May 2025, botanical biodiversity was demonstrated with a guided tour through the plant system in the inner courtyard (Building V.07) and attention was drawn to the diversity of plants. Information on the plant system in the inner courtyard can also be found in this brochure. The plant system contains the systematic groups into which plant species are categorised and makes their relationships visible. Sounds boring? Not at all, because it shows how land plants have developed (over the last 500 million years) and the immense diversity that exists. The evolutionary and success story of land plants can be depicted in this way and it was not only interesting for Charles Darwin (1809-1882).