Hermann Merxmüller (30 August 1920 Munich – 8 February 1988) was a German botanist and taxonomist.
Merxmüller's interest in botany was noticed at an early age by his mentors, and he was encouraged to collect in the Bavarian Alps and countryside. At 17 he joined the Bavarian Botanical Society and at the end of World War II was awarded a scholarship by the Maximilian Foundation, enabling him to study biology at the University of Munich. He completed his studies with a dissertation on plant distribution in the Alps, then taking up a post as scientific assistant at the Botanische Staatsammlung. Here the institute's director, Karl Suessenguth, employed him to assist in the creation of a prodromus or introductory treatise on Namibian plants, "Prodromus einer Flora von Südwestafrika". Merxmüller’s interests led him to the genus Hieracium, and eventually to an abiding interest in the Compositae family. He visited Namibia on five occasions, collecting mostly in the company of Willi Giess. Compositenstudien I (1950), an analysis of the collections of Sigmund Rehm from South West Africa, the Transvaal, and the Cape Province, was the first of 11 volumes, the last published in 1984. Suessenguth and Merxmüller produced only one joint publication "A contribution to the flora of the Marandellas District, Southern Rhodesia" (1951).
Merxmüller was an authority on the flowering plants of Africa, and discovered more than 100 new plant species in his expeditions to that continent. He also wrote extensively on Mediterranean and Alpine flora. His publications were on general systematics, taxonomy, cytotaxonomy, and plant geography. He is commemorated in the genus Merxmuellera Conert, and many species, including Barleria merxmuelleri P.G. Meyer, Carex merxmuelleri Podlech, Corchorus merxmuelleri Wild, Erica merxmuelleri Dulffer, Hermannia merxmuelleri Friedr. etc.
Merxmüller headed the Botanische Staatsammlung for more than 25 years, during which time he became a recognized authority in the world of systematic botany. Heinrich Nothdurft worked at the State Institute of Applied Botany in Hamburg, and collaborated with Merxmüller and Kräusel on "Sträucher und Bäume". All had a share in the success of the Kronen-Verlag and the implementation of Erich Cramer's original idea - bring together prominent natural scientists and distinguished artists to create a unique work depicting the exact form and colour of each species, while reflecting its diversity and aesthetic beauty.