The genusPassifloraprovides a remarkable example of floral complexity and diversity. The extreme variation ofPassifloraflower morphologies allowed a wide range of interactions with pollinators to evolve. We used the analysis of expressed sequence tags (ESTs) as an approach for the characterization of genes expressed duringPassiflorareproductive development. Analyzing thePassiflorafloral EST database (named PASSIOMA), we found sequences showing significant sequence similarity to genes known to be involved in reproductive development such as MADS-box genes. Some of these sequences were studied using RT-PCR andin situhybridization confirming their expression duringPassifloraflower development. The detection of these novel sequences can contribute to the development of EST-based markers for important agronomic traits as well as to the establishment of genomic tools to study the naturally occurring floral diversity amongPassifloraspecies.