Isert and Thonning's plants and Schumacher's Beskrivelse af Guineiske Planter (1827) – A Danish legacy to the study of the West African flora

Abstract Friis, I. & M.W. Callmander (2021). Isert and Thonning's plants and Schumacher's Beskrivelse af Guineiske Planter (1827) – A Danish legacy to the study of the West African flora. Candollea 76: 171–190. In English, English abstract. In the late 18th century, the Danish government planned to establish plantations in Danish Guinea (now southeastern Ghana), and detailed botanical studies were initiated for this. Material of more than 600 species was collected, mostly preserved at C, with duplicates at B, BM, FI-W, G, G-DC, K, LE, M, P-JU and S. Duplicates were distributed and studied across Europe long before the publication of a treatment of the entire collection. Examples of research on duplicates at B, C, G and G-DC illustrate how the material was sometimes described under different names during this period, as when Augustin-Pyramus de Candolle in Geneva took up Thonning's intended generic name Tricliceras Thonn. ex DC. for a new genus, while Schumacher in Copenhagen named the same genus Wormskioldia Schumach. & Thonn. This example also illustrates the contacts between Danish botanists and Candolle in Geneva, both directly and via Marc Nicolas Puerari. A manuscript dealing with the entire Guinean collection was ready by 1819, but only published when the Royal Danish Academy of Sciences and Letters took responsibility for it. Archival studies document that, on 30 June 1826, the Academy decided to publish Beskrivelse but not when and how a preprint became available. In a range of libraries in Europe and USA there are copies of this preprint entitled Beskrivelse af Guineiske Planter and the year of publication given as “1827”, while in the regular series of the Academy's publications the first 228 pages of Beskrivelse appeared in 1828 and the remaining 236 in 1829. The International Code of Nomenclature for Algae, Fungi and Plants stipulates that the priority of all new names published in a work must be counted from the year indicated as the year of publication on the work itself, unless this can be documented to be wrong, so 1827 must stand as the year of publication. Soon after that, Beskrivelse became an important source of information on West African plants. Received: March 7, 2021; Accepted: April 26, 2021; First published online: July 7, 2021