[1] Typically, exsiccatae are numbered collections of dried herbarium specimens or preserved biological samples published in several duplicate sets with a common theme or title, such as Lichenes Helvetici (see figure).
Exsiccatae are regarded as scientific contributions of the editor(s) with characteristics from the library world (published booklets of scientific literature, with authors/ editors, titles, often published in serial publications like journals and magazines and in serial formats with fascicles) and features from the herbarium world (uniform and numbered collections of duplicate herbarium specimens).
The text in the printed matters/published booklets is basically a list of labels (schedae [de]) with information on each single numbered exsiccatal unit.
[11] The oldest series known as an exsiccata is that of the German naturalist and pharmacist Johann Balthasar Ehrhart [de] called Herbarium vivum recens collectum...
[14] As one of the first Jakob Friedrich Ehrhart promoted the selling of dried plants with several series, among others Arbores, frutices et suffrutices Linnaei quas in usum dendrophilorum collegit et exsiccavit Fr.
Two examples: Alexander Braun, Gottlob Ludwig Rabenhorst and Ernst Stizenberger have distributed Die Characeen Europa's in getrockneten Exemplaren, unter Mitwirkung mehrerer Freunde der Botanik, gesammelt und herausgegeben von Prof. A. Braun, L. Rabenhorst und E. Stizenberger[18] in 1878 and Thomas Drummond published Musci Americani; or, specimens of the mosses collected in British North America, and chiefly among the Rocky Mountains, during the Second Land Arctic Expedition under the command of Captain Franklin, R.N.
[19] Some series are devoted to organisms of economical or medicinal relevance, and thus of interest for pharmacists, plant pathologists, veterinarians, people working in horticulture, agriculture and forestry.
In the case that they published exsiccatae, the series are explicitly cited in Frans Stafleu and Richard Sumner Cowan's standard work Taxonomic Literature: A Selective Guide to Botanical Publications and Collections, with Dates, Commentaries, and Types (7 volumes) and in the 8 volumes of the supplement series with the first 6 co-authored by Erik Albert Mennega.
In the Vienna rules (1906) of the ICBN, now International Code of Nomenclature for algae, fungi, and plants (ICN), exsiccatae and their printed matters were explicitly mentioned in the context of valid publication (Article 37).
Citizen science approaches for herbarium label digitization have instructions about how to recognize exsiccatae and how to mobilize this information in a structured manner.
Similar as iDigBio the concept for complete digitization of German herbaria is including the mobilisation of this structured historical information using a standard reference list of editors, titles, abbreviations, publication dates and number ranges.
This procedure will facilitate the discovery of duplicate exsiccata specimens in the various herbaria and avoid multiple typing of the same text information.
[29] Ideally, exsiccatae comprise dried plant or fungus material as a result of plant collecting, have a descriptive title, one or more editors (or alternatively an editing organisation), printed labels and the single dried specimens have printed taxon names, locality information and exsiccatal numbers and are distributed in sets/fascicles.
Some of them distributed specimen series with characteristic printed labels superficially resembling exsiccatae, mostly with anonymous editors.
[38][39] In addition to the plant exchange organisations described above, there were learned societies which, among other activities, published and distributed exsiccata-like collections of specimens.
1-86 published by Theodor Oswald Weigel, Leipzig, who organised the sale of exsiccatae and exsiccata-like series in a professional manner.
This kind of unique herbaria might superficially resemble exsiccatae and were offered for purchase to single academic societies and princely courts as for example Giorgio Jan did at the beginning of the 19th century.
[47] In few cases the term exsiccata is used for characterizing botanical art works bounded as books, which contain decorative assortments of pressed plant specimens mounted to the pages, usually arranged in a theme.