Braun was born in Regensburg (Ratisbon) where his father Alexander was a tax inspector in the postal department. His mother Henriette was the daughter of a priest and mathematics professor. He studied at Karlsruhe and Freiburg (Breisgau) where his father was transferred. He went to the University of Heidelberg to study medicine. His teachers included
Gottlieb Wilhelm Bischoff,
Johann Heinrich Dierbach and
Franz Joseph Schelver. At Heidelberg he studied with
Louis Agassiz,
Carl Schimper and
George Engelmann. Agassiz would marry Braun's sister Cecilie while Schimper was engaged briefly to Braun's sister Emilie. He completed his studies at Paris and
Munich. In 1833 he began teaching botany at the Polytechnic School of
Karlsruhe, staying there until 1846. Afterwards he was a professor of botany in
Freiburg (from 1846),
Giessen (from 1850) and at the
University of Berlin (1851), where he remained until 1877. While in Berlin, he was also director of the
botanical garden. He designed the layout which was later documented by Paul Friedrich August Ascherson. In 1852, he was elected a foreign member of the
Royal Swedish Academy of Sciences. With
Gottlob Ludwig Rabenhorst (1806–1881) and
Ernst Stizenberger (1827–1895), he was editor of the
exsiccata series ''Die Characeen Europa's in getrockneten Exemplaren, unter Mitwirkung mehrerer Freunde der Botanik, gesammelt und herausgegeben von Prof. A. Braun, L. Rabenhorst und E. Stizenberger''. Braun is largely known for his research involving
plant morphology. He accepted evolution but was a critic of
Darwinism. He was a proponent of
vitalism, a popular 19th-century speculative theory that claimed that a regulative force existed within living matter in order to maintain functionality. Braun made important contributions in the field of
cell theory. His students included
August Wilhelm Eichler. From his 1830s analysis of the arrangement of scales on a
pine cone he was a pioneer of mathematical
phyllotaxis developing what is called the Schimper-Braun theory. In 1877,
Wilhelm Philippe Schimper and
Philipp Bruch named the plant genus
Braunia in his honor. Also, a decorative plant known as "Braun's holly
fern" (
Polystichum braunii) commemorates his name. == Published works ==