The application of group theory to the description of biological objects’ pseudosymmetry is proposed and substantiated by the example of the rotatory symmetry of actinomorphic and zygomorphic flowers. The problems of biosymmetrics terminology are considered, and point symmetry elements are characterized as applied to the description of floral symmetry. Fundamental provisions of group theory are stated. Application of the Curie principle to biological objects is described. Algorithms for the quantitative assessment of floral pseudosymmetry are given; the description is made of floral pseudosymmetry in terms of group theory, including the evolutionary aspect. The conclusion is made that adaptation of group theory to the description of biological objects’ symmetry (biosymmetrics) is important not only from the fundamental point of view but also as a tool of interdisciplinary mutual understanding among biologists, physicists, crystallographers, and other specialists whose communicative language is mathematics.