Three generations of the Wendland family, Johann Christoph Wendland (1755–1828), Heinrich Ludolph Wendland (1792–1869) and Hermann Wendland (1825–1903), were outstanding court gardeners at the Royal Gardens of Herrenhausen (Hanover, Germany). The “Wendlands” not only enriched the botanical diversity of the gardens through plants obtained in exchange, purchased or collected during their own journeys, but they also achieved a good scientific reputation by publications on diverse botanical themes including the description of new taxa. Moreover, there exists a herbarium of approximately 16,600 plant specimens related to these gardens, the Wendlands and their publications. Numerous papers dealing with the Wendlands and the Royal Gardens of Herrenhausen have been published. The Herrenhausen Herbarium, however, also known as the Wendland Herbarium, which was donated to the University of Göttingen in 1969, was so far neither digitized nor revised. Here, we describe the history and the current digitization of this herbarium, which includes specimens collected between 1780 and 1857. It consists of three major parts: the Herrenhausen Herbarium arranged according to the Linnaean System (13,035 specimens), the palm collection (1069 specimens) and smaller collections (specimens collected by Hermann Wendland in Central America, collections of Carl Hoffmann from Costa Rica and a part of Jakob Friedrich Ehrhart's herbarium, who was a student of Linnaeus; approximately 2500 specimens). The systematic digitization of this historical herbarium as a whole revealed a seemingly unconventional arrangement of the specimens, which we explain here for the correct interpretation of collection data. Furthermore, and despite the meagre information on the herbarium labels, we were able to identify 260 specimens from a trip of Heinrich Ludolph Wendland to Switzerland in 1820. By comparing the specimen labels with entries in his diary and travel report, we were able to retrace detailed information on localities and dates, providing historical biodiversity information. Also, the historical identification of these specimens was revised. A list of collectors represented in the Herrenhausen Herbarium is provided, which includes famous names such as Linnaeus and his students Afzelius, Bergius, Ehrhart, Schreber, and Thunberg.