This study describes four recessive homeotic mutations in Arabidopsis thaliana that disrupt flower development. The mutations, agamous (ag), apetala2 (ap2), apetala3 (ap3), and pistillata (pi), each affect the differentiation of floral organs but not their position. agamous flowers have no stamens or carpels and develop chimeric organs. apetala2 flowers show transformations of petals to stamens and sepals to leaves. apetala3 flowers have sepals in the second whorl and carpelloid stamens in the third. pistillata flowers have sepals in the second and third whorls and an abnormal gynoecium. These mutations are temperature-sensitive, with different phenotypes at different temperatures. The AP2 gene product acts early in flower development, while AP3 acts later. The genes may be involved in setting up or responding to concentric, overlapping fields within the flower primordium. The study also describes double mutants, showing interactions between the genes. The results suggest that these genes allow cells to determine their position in the developing flower and differentiate appropriately. The findings indicate that the development of floral organs is regulated by genes that specify different fates for cells in different regions of the flower. The study also highlights the importance of understanding the mechanisms by which cells in developing flowers establish their positions and differentiate into appropriate cell types. The results suggest that the processes of floral development in Arabidopsis are likely similar to those in other plants.This study describes four recessive homeotic mutations in Arabidopsis thaliana that disrupt flower development. The mutations, agamous (ag), apetala2 (ap2), apetala3 (ap3), and pistillata (pi), each affect the differentiation of floral organs but not their position. agamous flowers have no stamens or carpels and develop chimeric organs. apetala2 flowers show transformations of petals to stamens and sepals to leaves. apetala3 flowers have sepals in the second whorl and carpelloid stamens in the third. pistillata flowers have sepals in the second and third whorls and an abnormal gynoecium. These mutations are temperature-sensitive, with different phenotypes at different temperatures. The AP2 gene product acts early in flower development, while AP3 acts later. The genes may be involved in setting up or responding to concentric, overlapping fields within the flower primordium. The study also describes double mutants, showing interactions between the genes. The results suggest that these genes allow cells to determine their position in the developing flower and differentiate appropriately. The findings indicate that the development of floral organs is regulated by genes that specify different fates for cells in different regions of the flower. The study also highlights the importance of understanding the mechanisms by which cells in developing flowers establish their positions and differentiate into appropriate cell types. The results suggest that the processes of floral development in Arabidopsis are likely similar to those in other plants.