The Herbarium Hamburgense houses an internationally important collection of approx. 50,000 specimens of large and micro algae from all parts of the world. The focus is on Central Europe with the North and Baltic Seas, but also the Cape region and Australia. The collection goes back to the private algae herbarium of the former mayor of Hamburg, N. Binder. The Herbarium Binderianum also contains the algae collection of the first director of the Hamburg Botanical Garden, J.G.C. Lehmann. In the middle of the 19th century, Binder's algae collection was arranged and scientifically processed by the important botanist and Hamburg pharmacist O.W. Sonder.