In addition to the collections currently used for teaching and research, there is a historical collection of plants preserved in alcohol, reflecting the course of botanical research at JGU since its reestablishment in 1946. Exemplary preparations are being preserved for documentary purposes. Over a hundred teaching maps (botanische Lehrtafeln) with partially handmade and hand-colored plant drawings are available and still used in lectures until some years ago. The Botanical Garden also preserves an extensive collection of pollen-gathering wild bees, first assembled and classified in the 1980s. The garden also holds preparations of various flowering plant families created using scanning electron microscopy (SEM).

The value of the collection lies in providing (rare) plant material. PhD students, postdocs and students use them for their research works, lecturers for teaching. Many samples are being preserved as reference of the elaborated research results. Of particular importance is the coordination of the alcohol-preserved collection with the Botanical Garden’s living collection and the Herbarium’s dry collection. The garden maintains a special Salvia (sage) collection, including alcohol-preserved specimens and silica samples for molecular studies, linked to the living collection and Herbarium records. Over 150 species mainly from Europe, Mexico, California and South Africa are documented in this way. South African Bruniaceae and African Marantaceae (from Gabon) are preserved almost entirely in at least two collections, allowing for detailed comparative studies.

The Wilhelm Troll Collection, belonging to the Botanical Collections, preserves scientific drawings, glass slides, photos, manuscripts, and alcohol specimens that trace the Botanic Garden’s evolution.