Career
In 1855 he was a lecturer of botany at the University of Berlin, and six years later became curator of the royal herbarium. In 1865 he was appointed professor of botany at the University of Bonn and director of the botanical garden. Hanstein is remembered for studies in plant anatomy and morphology.
In 1868 he introduced the "histogen theory" to explain shoot apex behaviour in plants.
The plant genus Hansteinia of the family Acanthaceae is named after him.
