Paul Sydow (1 November 1851 in Kallies – 26 February 1925 in Sophienstädt near Ruhlsdorf)[1] was a German mycologist and lichenologist, father of Hans Sydow (1879–1946).
He worked as a schoolmaster in Berlin. With his son, Hans, he authored works involving descriptions of new species of ascomycetes, rusts and smuts.[2] Paul Sydow was a prolific author (or co-author) of new fungal species, having formally described 2331 in his career.[3] He also wrote about algae. He authored 252 works in five languages.[4] Between 1880 and 1916 Sydow edited seven exsiccata series, among them Mycotheca Marchica (1880) with Friedrich Wilhelm Zopf as co-editor.[5][6] With his son Hans Sydow he co-edited the first fascicles of the series Mycotheca Germanica (1903–1906).[7]