The leafy gene in Arabidopsis controls whether lateral meristems become flowers or branches. By studying new leafy mutations and creating double mutants with other floral genes, researchers found that leafy overrides pistillata and works with agamous to determine early floral development. In later stages, leafy takes over from agamous. Double mutants with leafy and apetala1 or apetala2 lose typical flower features. Leafy, apetala1, and apetala2 together guide lateral meristems to become flowers instead of branches.