Orchids are known for both their floral diversity and ecological strategies. The versatility and specialization in orchid floral morphology, structure and physiological properties have fascinated botanists for centuries. In floral studies, MADS-box genes contributing to the now famous ABC model of floral organ identity control have dominated conceptual thinking. The sophisticated orchid floral organization, such as labellum and gynostemium, offers an opportunity to discover new variant genes and different levels of complexity to the ABC model. In our studies, we suggest that the duplication and differential expression of B and C class genes may contribute to the specificity of orchid floral morphology. We also proposed a molecular model to explain the development of sterile and fertile floral organs in orchids. Knowledge of MADS-box genes encoding ABC functions in orchids will give insights into the highly evolved floral morphogenetic networks and the diversification of orchids.