1913 to March 1, 1943

The year 1913, the last year covered by Urban's history of 1916, coincidentally was also the last year in the rapid development of the Botanical Museum during Engler's directorship. After the outbreak of World War I in 1914 the number of staff members was soon reduced, and the stream of collections from the colonies dried up very quickly. Nevertheless, the study of plant specimens already in the herbarium resulted in 12 more "Beiträge zur Flora von Afrika" (Contributions to the Flora of Africa) published in the "Botanische Jahrbücher" (vols. 51-62, 1914-1929) with more than 1,700 pages edited by Engler.

Shortly before the war another series was started, "Beiträge zur Flora von Papuasien" (Contributions to the Flora of Papuasia) edited by C. Lauterbach and published in the same journal. This series of papers was at first based on collections of C. Ledermann, R. Schlechter, H. Hollrung, C. Lauterbach, O. Warburg and many others (see Timler & Zepernick 1987), mainly from the northeastern part of New Guinea (Kaiser-Wilhelmsland). For the later publications in this series, edited by L. Diels, new collections of Brass, Clemens and others were also studied. The 25 parts of the series were published between 1912 and 1940 and comprise over 3,300 pages.

After retiring in 1913, Urban worked exclusively on the plants from the West Indies assembled in the Herbarium Krug & Urban. These collections were continuously expanded during the years 1915-1935 by the collections of E. L. Ekman who added more than 24,000 numbers.

Engler retired in 1921 at 77 and his pupil L. Diels (1874-1945) was appointed Director. Diels had been Vice-Director of the Botanical Garden and Museum at Dahlem since 1913. During the last 7 years of Engler's directorship several other large collections came into the possession of the Museum. The most important was the herbarium of the Naturhistorisches Museum zu Lübeck which contained several thousand specimens including many old collections not present in Berlin before (see Anon. 1916: 405 f. for list of collectors). The most important part of the "Herbar Lübeck" was the original S. African collection of J. Drège with about 8,000 specimens that had originally belonged to E. H. F. Meyer (Königsberg, † 1858).

Other notable acquisitions during that time were the herbaria of H. Dingler (including the original Greek collection of W. v. Spruner), H. Kinscher, E. Koehne, M. Schulze (Jena), and J. Utsch (for details see Appendix A).

The transition of the directorship to L. Diels - R. Pilger (1876-1953) was Diels' successor as Vice-Director - at first resulted in hardly any change in the research program. In addition to studies for the second edition of "Die Natürlichen Pflanzenfamilien" and further monographs for the "Pflanzenreich" new collections were studied and the results, especially descriptions of new and rare taxa, were published. Between 1914 and 1939 Diels edited for the journal "Botanische Jahrbücher" five contributions to the Flora of Micronesia and Polynesia. In the "Notizblätter des Botanischen Gartens und Museums zu Berlin-Dahlem" papers on several notable collections were published as series: Luetzelburg (Brazil), Steinbach (Bolivia), Tessmann (Peru), and Schlieben (E. Africa, with ca. 500 new taxa!).

When the "Flora brasiliensis" was finished in 1906, no large new floristic project existed in the Museum. Urban all his life had attended to the flora of the West Indies as editor and main author of "Symbolae antillanae", and P. Graebner worked until his death in 1933 on the "Synopsis der mitteleuropäischen Flora" originally founded by Ascherson. Then in 1939 a new institutional project was started - a Flora of S. W. Africa (Anon. 1940: 284). Two years later the treatments of several families were already finished, but most of the manuscripts of the flora burned in 1943 (Werdermann 1954) and the project was resumed after the war at Munich.

Collecting trips by staff members of the Botanical Museum to European countries or to the tropics were not possible during World War I and the following years. The first expedition from 1923-1927 was led by E. Werdermann to Chile and Bolivia. Several collections were also made during short trips to the Balkans, the Near East, the Alps, and to the tropics: Cameroon, Brazil, Ecuador etc. (see Zepernick & Timler 1979: 14 f.).

In the 1920s many collections from China came to Berlin (those of Hu, Klautke, Schneider, Sin, and others) which were studied by Diels and later by visiting Chinese botanists. For example, Y. C. Wu worked for more than 4 years (1936-1940) at the Botanical Museum.

Among the many important collections that were added to the herbarium during the 1920s and 1930s those of A. W. Roth (1757-1834), W. Becker (vouchers and types of his work on Viola), E. H. L. Krause, C. Mez, F. A. Körnicke, H. Sandstede (Cladonia), A. Peter (E. Africa), and K. H. Zahn (Hieracium) are some of the most notable (for details see Appendix A). Another noteworthy acquisition was the herbarium of the Naturhistorischer Verein für die Preussischen Rheinlande und Westfalen at Bonn received in 1936 (Anon. 1937). This huge collection of about 200,000 specimens containing the important herbarium of L. C. Treviranus was evacuated to Müncheberg east to Berlin and did not return to Dahlem after the war. Instead it came to the herbarium of the Humboldt University in East Berlin: BHU (cf. Bässler 1970 and Hiepko 1979). Only in 1993 it returned to B together with the BHU collections (cf. Taxon 42: 897. 1993).

At the beginning of the 1940s the herbarium contained about 4 million specimens (Eckardt 1966: 159); only ten years previously the Phanerogam collection alone had been estimated at 2,2 million sheets (Anon. 1934: 11). Just after the beginning of World War II the collections of Cryptogams stored in the attics of the Herbarium building were moved to safer locations in the cellar, in corridors, and other rooms of the building. Only the Herbarium Willdenow was evacuated to a bank vault. Around the beginning of 1943 a sorting out of types and other authentic material was begun. Unfortunately, this effort was not finished when the Herbarium building was destroyed by fire in a bombing raid on the night of March 1-2, 1943.

"The loss of the Berlin herbarium is a catastrophe of major proportions to world botany" wrote Merrill (1943), who continued: "This herbarium, one of the largest and most important in the world, . . . contained the basic historical collections of Germany outside of those at Munich. Scores of thousands of type specimens from all parts of the world were thus destroyed". Fortunately about 20,000 types of the Phanerogam collections have been saved (see part III).

The dimensions of this loss can only be visualized in comparison with the significance of the old Berlin herbarium. It was founded relatively late. In the territory of the later German Reich seven institutional herbaria existed before 1815, including the Royal Herbarium at Munich, founded in 1813. Many herbaria in other European countries - e.g. the Netherlands, France, Great Britain, and Sweden - were established much earlier.

While most herbaria soon tended to be specialized geographically, the Berlin herbarium did not show any limitations regarding either groups of plants or geographical regions. The fact that plants from the area surrounding Berlin were relatively rare in the collections for more than 40 years after its foundation is characteristic for this herbarium. The neotropics, however, were a special field of interest right from the beginning and in the 1930s the Botanical Museum Berlin-Dahlem consequently "housed the world's largest collection of neotropical types" (Grimé & Plowman 1986: 932).

The growing political importance of Prussia in the 19th century, the fast development of Berlin as capital of the German Reich from 1871, and the key position of the Botanical Museum for the exploration of the new German colonies in Africa and Oceania caused the Berlin herbarium to become the largest in Germany and in German-speaking Europe. With ca. 4 million specimens, it ranked with Kew, Leningrad, and Paris as one of the four largest herbaria of the world.