No detailed account exists of the pre-war lichen collections, and it is unknown how many specimens were available. Certainly an important part was formed by the herbaria of Fl rke and Laurer. In spite of the presence of numerous important types and valuable exsiccata series, the herbarium has probably contained less than one hundred thousand specimens, predominantly from Central Europe. The lichens incorporated in the General Herbarium were nearly completely destroyed in 1943. Only two larger loans, concerning the genus Lecanora and the family Stictaceae, survived abroad and were returned after the war.
Current expansion is mainly in tropical taxa.
Ongoing research projects , in particular on the lichen flora of Colombia, the Guianas and New Guinea, brought ample material from these areas, on which already several new species were based. A spin-off is the exsiccata series Lichenotheca Latinoamericana , which is sent to 25 herbaria over the world, including several in developing countries. Within Europe, the main activity is in the Mediterranean, in particular Greece. An important recent acquisition was the herbarium of S. Huneck, about 11,000 specimens and 1,000 samples of lichen substances and their derivatives.