[2] His extensive and careful studies of the life history of fungi and contribution to the understanding of algae and higher plants established landmarks in biology.

Although he received his degree in medicine, his dissertation at Berlin in 1853 was titled "De plantarum generatione sexuali", a botanical subject.

In 1855, he succeeded the botanist Karl Wilhelm von Nägeli (1818–1891) at Freiburg, where he established the most advanced botanical laboratory at the time and directed many students.

[3] He conducted much research in the university botanical institute, attracted many international students, and made a large contribution to the development of botany.

Similarly, de Bary asserted that rust and smut fungi caused the pathological changes that affected diseased plants.

[3] De Bary spent much time studying the morphology of fungi and noticed that certain forms that were classed as separate species were actually successive stages of development of the same organism.

De Bary studied the developmental history of Myxomycetes (slime molds), and thought it was necessary to reclassify the lower animals.

In his published work in 1863 entitled "Recherches sur le developpement de quelques champignons parasites", he reported inoculating healthy potato leaves with spores of P. infestans.

He observed that mycelium penetrated the leaf and affected the tissue, forming conidia and the black spots characteristic of potato blight.

In 1879 he coined the word "symbiosis", meaning "the living together of unlike organisms", in the publication "Die Erscheinung der Symbiose" (Strasbourg, 1879).

[3] De Bary's concept and methods had a great impact on the fields of bacteriology and botany, making him one of the most influential bioscientists of the 19th century.

[1] De Bary came from a noble family of Huguenots from Wallonia, which was driven out from there by the Spanish Habsburgs under Emperor Charles V and can be found in Frankfurt since 1555.

De Bary married Antonie Einert (21 January 1831, Leipzig – 22 May 1892, Thann, Alsace–Lorraine) in 1861; they raised four children: Wilhelm, August, Marie and Hermann.