A herbarium is a collection of preserved plants which are pressed, dried and mounted on paper and labelled with their scientific name, place of collection, and collectors name. Thereby vouchers can be preserved over centuries. Herbaria serve for the taxonomic description of species and are a basis for classification and systematics. Furthermore herbaria serve as a documentation of local and worldwide plant diversity. The vouchers in herbaria, the genetic information stored in them and other information are used today intensively for research on various topics concerning biodiversity. Recently available methods (i.e. isotope analysis) allow the use of herbaria to document climate and environmental changes.)