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 1868 he introduced the "histogen theory" to explain shoot apex behaviour in plants.
[1] With his close friend, Nathanael Pringsheim (1823–1894), he conducted pioneer research on the fertilization process in ferns.
[2] He was also an editor of the journal Botanische Abhandlungen aus dem Gebiete der Morphologie und Physiologie (Botanical treatises from the areas of morphology and physiology).