Among his many contributions to taxonomy are his treatments of the Medusagynaceae, Theaceae, Violaceae, and Canellaceae for the second edition of the Die Natürlichen Pflanzenfamilien of Engler & K. Prantl, the publication as editor with E. Werdermann, of ed. 12 (1954-1964) of Engler's "Syllabus der Pflanzenfamilien", and, as a last major contribution (with Hans Kastner) of Gewürze (1974). He died in Berlin, aged 89.
