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Diversification of MADS box genes has been proposed as a major driving force for floral diversity in land plants. Yamaguchi et al. (pages 15-28) investigate the functions of rice OSMADS3 and OSMADS58, homologs of Arabidopsis AGAMOUS, a C-class MADS box gene that regulates stamen and carpel identity and floral meristem determinacy. The authors show that disruption of OSMADS3 in a T-DNA insertion line results in homeotic transformation of stamens into lodicules and the ectopic development of lodicules in the second whorl. By contrast, RNA-silenced lines of OSMADS58 developed flowers that reiterate lodicules, stamens, and carpel-like organs, suggesting loss of determinacy in the floral meristem. The results suggest that functions regulated by AGAMOUS in Arabidopsis have been partially subfunctionalized during the evolution of rice into two paralogous genes, OSMADS3 and OSMADS58, which arose from a recent gene duplication event. In addition, the development of ectopic lodicules in OSMADS3 loss-of-function mutants points to a role for C-class genes in the asymmetric distribution of lodicules in the rice flower.