From 1938-48 he headed a Department at the Yerevan State University, and from 1944-48 was director of the Botanical Institute of the Academy of Sciences of the Armenian SSR, and Professor of the Leningrad State University. Takhtajan was a member of the Russian Academy of Sciences, as well as a foreign associate of the U.S. National Academy of Sciences since 1971. He was also the academician of the Academy of Sciences of the Armenian SSR, the president of the Soviet All-Union Botanical Society (1973) and the International Association for Plant Taxonomy (1975), member of the Finnish Academy of Science and Literature (1971), the German Academy of Naturalists "Leopoldina" (1972) and other scientific societies.