Initially, Unger studied law at the University of Graz. In 1820 he moved to Vienna to study medicine, in 1822 he enrolled at the Charles University in Prague. In 1823 Unger returned to Vienna and completed his medical studies in 1827.
From 1827 Unger practiced as a doctor in Stockerau near Vienna, then from 1830 as a court physician in Kitzbühel, Tyrol. In 1836 he was named professor of botany at the University of Graz and also taught at the Joanneum (which became the Universalmuseum Joanneum and the Graz University of Technology); in 1850 professor of plant physiology in Vienna. In 1852 he travelled to Northern Europe and to the Orient. Unger retired in 1866 and lived on his farm near Graz.
Unger was one of the major contributors to the field of paleontology, later turning to plant physiology and phytotomy. He hypothesized that (then unknown) combinations of simple elements inside a plant cell determine plant heredity and greatly influenced the experiments of his student Gregor Johann Mendel. Unger was a pioneer in documenting the relationships between soil and plants (1836).
Unger is notable for proposing a theory of evolution before Charles Darwin.1 Unger accepted the transmutation of species. During his time his ideas were widely criticized by those who held religious views.23 In his book Attempt of a History of the Plant World (1852) he devoted a chapter to the evolution of plants.4
Gliboff, Sander (1998). "Evolution, Revolution, and Reform in Vienna: Franz Unger's Ideas on Descent and Their Post-1848 Reception". Journal of the History of Biology. 31 (2): 179–209. doi:10.1023/A:1004379402154. ISSN 0022-5010. JSTOR 4331477. S2CID 81254307. https://www.jstor.org/stable/4331477 ↩
Gliboff, Sander. (1998). Evolution, Revolution, and Reform in Vienna: Franz Unger's Ideas on Descent and Their Post-1848 Reception. Journal of the History of Biology 31: 179-209. ↩
Ruse, Michael; Travis, Joseph. (2009). Evolution: The First Four Billion Years. Belknap Press. p. 729. ISBN 978-0674062214 /wiki/ISBN_(identifier) ↩
Mayr, Ernst (1982). The Growth of Biological Thought: Diversity, Evolution, and Inheritance. Cambridge, MA and London, England: Belknap Press. p. 390-391. ISBN 978-0674364462 – via Internet Archive. 978-0674364462 ↩