Heinrich Ludwig Hermann Müller (1829–1883) was a German botanist who provided important evidence for Darwin's theory of evolution.
Müller was an early investigator of coevolution.p27 He was the author in 1873 of Die Befruchtung der Blumen durch Insekten, a book translated at the suggestion of Darwin in 1883 as The fertilisation of flowers. He and Darwin corresponded—36 letters between the two, or from Darwin concerning Müller, are recorded. Darwin cited him extensively in The Descent of Man for his information relating to the behavior of bees.
Hermann was the brother of Fritz Müller,p29 the German doctor who lived in the Amazon and researched its natural history. The work of both brothers was well known to Darwin.The standard author abbreviation H.Müll. is used to indicate this individual as the author when citing a botanical name.