The Botanical Gardens primarily serve research and teaching. Around 11,000 plant species are cultivated here. The outdoor area consists of a park-like arboretum (tree collection) and the flower beds of the various teaching departments. The nine showhouses show around 4,500 species: Tropical plants, ferns, mangroves, water lilies, cacti and orchids from all over the world live here in natural communities. In addition, there are four smaller culture and showhouses.