The architecture of inflorescences diverged during the evolution of distinct plant families by mechanisms that remain unknown. Using computer modeling, Przemyslaw Prusinkiewicz and colleagues established a single model for the development of distinct inflorescences. Selection restricts inflorescence evolution to high fitness paths that vary with climate and other factors that influence reproductive success - explaining why some evolutionary transitions are more likely than others. This model presents an important framework for future plant 'evo-devo' research. © 2007 Elsevier Ltd. All rights reserved.