The war-dependent fire of 1943 was a crucial event for herbarium B. It is unclear how many lichen specimens were available in B before that time. Urban (1916: Geschichte des k. bot. Museums zu Berlin-Dahlem 1815-1913) lists some 250 collectors. Certainly important parts were the herbaria of Flörke and Laurer. Other important (though probably not very numerous) collections were those by Meyen from his travel in the tropics, and those by various collectors in New Guinea. 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.
Only two larger loans, concerning the genus Lecanora and the family Stictaceae, survived abroad and were returned after the war. In addition, some not yet incorporated herbaria were saved: those of J. Lahm, F. W. Zopf (including a collection of lichen substances, cf. Huneck et al. 1973), and H. Zschacke (Mattick 1954). Contrary to the information by Grummann (1974), the latter herbarium is probably completely present in B, with ample material from Sachsen-Anhalt, the Harz mountains, Corsica and the Carpathians, and a large collection of Verrucariaceae.
Shortly after World War II, several large private herbaria were acquired: G. Lettau (38,000, including many packets with several vouchers), O. Behr (11,000) and V. Grummann (10,000). All three consisted predominantly of specimens from Germany.
Current expansion is mainly in tropical material. Ongoing research projects, in particular on the lichen flora of Colombia, Costa Rica, 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. Other extra-European areas for which important collections have become available include El Salvador, Mexico, Australia (duplicates leg. Streimann), Malaysia, the Philippines, Mongolia (herb. Huneck), Chile (herb. Follmann). Within Europe, the main activity is in the Mediterranean, in particular Greece. Important recent acquisitions were the herbarium of S. Huneck (1994), about 11,000 specimens, including vouchers for his "Mitteilungen über Flechteninhaltsstoffe" and 1,000 samples of lichen substances and their derivatives, and G. Follmann (2005), about 20,000 specimens.
Today the lichen herbarium comprises about 250,000 specimens, of which some 30% are included in the database LICHCOL. Another ca. 3,000 specimens collected by Lettau are included in a database of epiphytic lichens.
[Text: H. Sipman]