This was the first use of the term Lilianae by him, but was not formally described and hence attributed ("superordo nov.") till 1966, when he published a formal monograph (in Russian, English translation available 1969) on the classification of the flowering plants. He considered Lilianae a synonym of Liliiforae. At the same time Cronquist and Takhtajan, who had worked closely together, jointly published a formal proposal in English for the nomenclature and classification of the supraordinal taxa, to the level of class.