Johannes von Hanstein

Johannes Ludwig Emil Robert von Hanstein (15 May 1822 – 27 August 1880) was a German botanist who was a native of Potsdam.

He attended classes at the ''Gärtnerlehranstalt'' (Institute of Horticulture) in Potsdam, and later studied sciences in Berlin, obtaining his doctorate in 1848. 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. With his close friend, Nathanael Pringsheim (1823–1894), he conducted pioneer research on the fertilization process in ferns.

The plant genus ''Hansteinia'' of the family Acanthaceae is named after him.

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