Theodor Carl (Karl) Julius Herzog (7 July 1880, Freiburg im Breisgau – 6 May 1961, Jena) was a German bryologist and phytogeographer.
He studied sciences in Freiburg and Zürich, obtaining his doctorate in 1903 from the University of Munich as a student of botanist Ludwig Radlkofer (1829-1927).
Later on, he obtained his habilitation at Eidgenössische Technische Hochschule in Zürich under the sponsorship of Carl Joseph Schröter (1855-1939).
[2] He was a leading authority of mosses, and also dealt with the systematics and phytogeography of flowering plants.
As his career progressed, he focused more of his attention towards the classification of liverworts, in particular the family Lejeuneaceae.