This is the first in-depth account on the Botanische Zentralstelle für die deutschen Kolonien [Botanical Central Office for the German Colonies] affiliated to the Royal Botanic Garden and Museum in Berlin from 1891 until 1920. Based on copious archival material, mainly kept in the Bundesarchiv Lichterfelde and the Geheimes Staatsarchiv Preussischer Kulturbesitz in Berlin but largely never studied before, Kaiser's book is most welcome for several reasons. One of them is the fact that only very few senior members of staff of today's Botanic Garden and Botanical Museum Berlin (BGBM) understand the special administrative structure, purpose and history of the Botanische Zentralstelle. Another reason is that Kaiser's very comprehensive treatment on 537 pages with a total of 1817 footnotes adds significantly to the history of the BGBM, to the biography of Adolf Engler (1844–1930), its long reigning director (cf. Lack 2000), and to the history of botany, zoology and ethnology in Berlin in general. It is a remarkable achievement, in particular because it was written by a historian, not by a plant taxonomist, and offers a fresh outside view, free from misconceptions and incorrect terminology. Needless to say, this text, based on Kaiser's doctoral thesis submitted to the Freie Universität Berlin in 2019, belongs to the postcolonial studies but at the same time is also a contribution to institutional history.

The German Empire was a latecomer on the colonial scene. For complex reasons, all matters referring to the colonies were Reichssache [matter of the empire], whereas all matters referring to science in the broad sense belonged to the responsibilities of the different states forming the German Empire, with the Kingdom of Prussia being by far the largest and most powerful of them. This very special state of affairs led to a long-discussed agreement between the Reichskolonialamt for the empire and the Preußisches Ministerium der geistlichen, Unterrichts- und Medizinalangelegenheiten for Prussia with the purpose of making use of the Königlicher Botanischer Garten und Botanisches Museum, an institution referring to that ministry, for colonial economy. The arrangement was based on an earlier decision taken by the Bundesrat and resulted in the co-funding of a new administrative structure attached to the Royal Botanic Garden and Museum Berlin called Botanische Zentralstelle. It was to serve as a kind of clearing house for (1) plant material, living or permanently preserved, (2) botanical knowledge, in particular on economic plants, and, (3) specialized staff, mainly gardeners, all three either arriving from the German colonies or being sent there. With the Royal Botanic Gardens, Kew as model to follow, this agreement led to an unprecedented influx of specimens to the Royal Botanic Garden and Museum in Berlin and pertinent research based on these accessions. As a consequence, the latter institution enjoyed a privileged position in the German Empire and the German colonies like Kew possessed in the British Empire. As clearly set out by Kaiser, the Royal Botanic Garden and Museum Berlin was, in contrast to Kew, never a national institution, but a Prussian institution with the Botanische Zentralstelle a Mischinstitution [mixed institution] (p. 113). Therefore, it never enjoyed the authority that Kew and its directors achieved in colonial matters. Furthermore, Kew's budget is calculated to having been on average three times larger than that of the sister institution in Berlin (p. 114). For decades, Kew remained the point of reference for the BGBM, although Kaiser for good reasons calls the persistent comparisons with Kew part of the “offizielle[n] nationalistische[n] Rhetorik” [official nationalistic rhetoric] (p. 376).

The key figures of this book are clearly Engler, who in addition to his other positions was also the head of the Botanische Zentralstelle; Ignaz Urban (1848–1931), for many years his deputy; Friedrich Althoff (1839–1908), for some 25 years the man in the Prussian ministry who knew how to pull the strings, instrumental in the relocation of the Royal Botanic Garden and Museum Berlin and buried there even before it had been formally inaugurated; and Georg Volkens (1855–1917), the curator at the Botanische Zentralstelle and its actual manager. Kaiser's text is rich in gems, e.g. her “erhöhte quellenkritische Sorgfalt” [increased source-critical diligence] (p. 47) advised when reading the reports of the Botanische Zentralstelle addressed to the Reichskolonialamt and the Prussian ministry, because these papers followed the logic of the funding bodies and not of the botanists involved. For good reason, Kaiser also cautions her readers of Urban's and Volkens's “positive Selbstdarstellung” [positive self-portrayal] of their share in the developments (p. 45). The complex reasons for translocating the institution to its new site, in Engler's words “aufs Dorf” [to the village, i.e. Dahlem] (p. 157), is another piece of excellent reading.

Naturally access to never-tapped archival material led to new insights into the precise sequence of events and modified previous views, e.g. those published on the translocation (Grotz 2010). Kaiser also does not suppress information on the smaller or more substantial feuds between the figures involved, among them Engler's conflicts with Otto Warburg (1859–1938) at the Seminar für orientalische Sprachen (p. 127) and with the physician, pharmacologist and toxicologist Louis Lewin (1850–1929) (p. 129). Among Engler's arguments against the former was simply his own higher status – he was a full professor and full member of the Royal Prussian Academy of Science, whereas Warburg had only the title of professor (p. 131), which is a nice specimen of the realities in hierarchy-minded Prussia. Quite naturally, this conflict is echoed in the controversy between Volkens and Warburg (p. 466). Strong egos were also involved when Engler together with his colleagues at the Museum für Naturkunde and the Museum für Völkerkunde, both based in Berlin, defended their privileged position in exclusively receiving materials from the German colonies and successfully opposed the foundation of a major museum for colonial matters in Berlin (p. 127).

Kaiser also deals in detail with the educational role of the BGBM in the years 1891–1920. Interestingly, the Prussian ministry explicitly called the institution “Institut der allgemeinen Volksbildung” [institute for general popular education] (p. 191), a mission statement reworded by Engler as “Bildungsstätten für das Volk” [educational institutions for the people] (p. 221). As evident from this book, Engler and his team were most successful in addressing the ministry's expectations.

The book under review contains only ten figures, but these are very carefully chosen. They include a photograph of the only Wardian case extant in the BGBM, which is the key item of Chapter 2 and a central piece of evidence in a brand-new book on this subject (Keogh 2020); a photograph showing workers in a plantation in Kyimbila, now Tanzania, which is central for Chapter 5; a photograph showing the former colonial section of the Botanical Museum; and reproductions of maps of the Royal Botanical Garden in Schöneberg and in Dahlem with the respective colonial sections.

The number of inaccuracies is small: Tropical rainforests do not exist in Togo (p. 71), Engler headed the Royal Botanic Garden and Museum Berlin for 32, not 22 years (p. 98), Sir Joseph Banks (1743–1820) was not the director of the Royal Garden at Kew, but was active there rather in his position as president of the Royal Society and as a figure at court (p. 112). There are a few demerits. Of these, the most significant is the total absence of indices: there is neither an index to the names of persons nor to general terms nor to place names. Why was the publisher not prepared to pay for a freelance indexer to do this job? Who will have the time and patience to read 537 pages of solid German prose with often very long sentences to find the information he or she is looking for? Secondly Kaiser's text is rich in redundancies that could have been avoided by making use of more cross-references. It would also have been helpful to include a very condensed version of this book in English, not just a one-page abstract in English and French. Considering the outstanding quality and comprehensiveness of Kaiser's text, it is strongly recommended that, in addition to her summary (Kaiser 2015), some of the key arguments are published in English and in a journal specialized in the history of biology, e.g. Annals of Natural History. It would also have been a good idea to include a timeline for the Botanische Zentralstelle, which was dissolved when the German Empire lost its colonies after the end of the First World War, but was officially reactivated in 1941, remaining functional only for a very short time (p. 471).

In short, this is a major and long overdue contribution to the fields of “botanical imperialism” and the history of science and merits general attention.