As a result of developmental genetic analysis, We have succeeded in identifying key genetic control processes for leaf morphogenesis, such as ROT3, AN, AS2, BOP1/2, ROT4, and AN3 genes, from Arabidopsis thaliana for the first time in the world. The finding that the entire leaf shape of Arabidopsis is independently regulated in two directions, longitudinally and laterally, has been highly evaluated and is introduced in textbooks, such as “Principles of Development” (Wolpert). The AN3 protein has also been shown to have a morphogen-like role in leaf primordia. We have also analyzed the regulation of leaf thickness in response to high light conditions, as an Eco-Evo topic. Nevertheless, many of the key genes that we have identified for leaf morphology are not yet well understood in the sense of how the genes change the behavior of cells and subsequently change leaf shape. We are currently analyzing the relationship between gene function and cell behavior by developing a method of rapid evaluation of cell division frequency and angle in the leaf base. We are also using other model systems such as liverworts, Marchantia polymorpha.