 In 1799 he was named director of the botanical garden at "Gartenstraße", and in 1809 was appointed professor of botany, zoology, mineralogy and materia medica at the university.He served as director of the botanical garden until his death in 1850, being buried in the central avenue of this botanical garden.Throughout his life thanks to acquisitions and interchanges with other botanists, he assembled a considerable herbarium of 60,000 plants with specimens from North America, South America, Asia, and Africa.