[in Russian with English abstract: ] This year marks 150th anniversary of the birth of the outstanding Russian cryptogamist, Alexander Alexandrovich Elenkin. He is renowned as the pioneer of the Russian cyanobacterial science school and one of the founding figures in Russian lichenology. A. A. Elenkin has made a titanic work on describing the flora of blue-green algae of the USSR, and created the first domestic identification book of this group. In addition to fundamental scientific research, which has not lost its relevance to this day, Elenkin prepared a pleiad of brilliant students who continued the development of Russian cryptogamic botany. It was through the efforts of A. A. Elenkin that the process of development of individual branches of Russian botanical science — algology, lichenology, bryology, was launched, which spread to many scientific centers of Russia. Keywords: blue-green algae, cyanobacteria, cryptogamic organisms, history of study, Russia.