A system for formal description of Arabidopsis thaliana floral development is proposed. It is based on correlations between elementary modules composing the flower and activity profiles of the genes controlling determination of floral organ identity. Flower development has been formally described for wild-type plant and mutants in floral morphogenesis (leafy, apetala1, apetala2, apetala3, pistillata, agamous, and superman genes). A mathematical (automata–theoretical) model of genetic control of determination of floral organ identity has been developed. The model adequately predicts the pattern of organogenetic changes in double mutants in floral development, i.e., predicts the type of interactions between these genes.