During the reproductive transition in flowering plants, a vegetative apical meristem (SAM) transforms into an inflorescence meristem (IM) that forms bracts and flowers. In grasses such as rice, a genetic regulatory network (GRN) controlling reproductive transitions has been identified. It includes the integration of promoters and repressors from different gene lineages with active duplication events during angiosperm diversification. With the objective to understand the evolution and expression of flowering GRN in Orchidaceae, we performed comprehensive phylogenetic analyses of all genes from the flowering GRN and analyzed by RT-PCR the expression of targeted homologs in key developmental stages. Our ML results indicate that the FT/TFL1, FD, FLC/FUL, SOC1 and AGL24/SVP gene lineages have been subject to multiple duplications in monocots, as well as in Orchidaceae. Conversely, FLC genes are lost in Orchidaceae, suggesting major changes in the repression of flowering. Our studies also show active expression of many target genes in Elleanthus aurantiacus (Orchidoideae) in the SAM and in IM, indicating important functions in the reproductive transition. We describe how the flowering GRN in orchids has significant variations in copy number and expression patterns when compared to the canonical rice flowering GRN.