Karl von Keissler
Karl von Keissler was an Austrian lichenologist and mycologist.
In 1895 he obtained his doctorate from the University of Vienna, afterwards spending several years as an assistant in the botanical garden at Vienna. From 1899 to 1938, he performed various functions in the botanical department at the Naturhistorisches Museum. In 1922 he was appointed director of the museum's botanical department. Starting from 1923 until 1933 he published the exsiccata Kryptogamae exsiccatae editae a Museo Palatino Vindobonensi.
The lichenicolous fungi genus Keissleriomyces bears his name, as do the mycological genera Keissleria and Keissleriella. Similarly, Keisslerellum was published by Werner in 1944 before becoming a synonym for Mycoporellum Also Keisslerina and Neokeissleria both were named by Franz Petrak.