Plants have evolved diverse and sophisticated adaptive mechanisms as well as bizarre organs, morphologies, and body plans under their ever-changing abiotic and biotic environments. Our goal is to unravel such a tremendous diversity of plants at the molecular level and to reconstruct and predict their evolutionary processes, thereby deepening our understanding of biological evolution. The Tsuchimatsu group focuses on (but not limited to) mating system evolution of flowering plants. A powerful tool to address the mechanism of adaptive evolution is the genomic information at the population and species levels, which has recently become available easily thanks to the development of sequencing technologies. The Katayama group aims to clarify the “constraint-breaking factors” that allow drastic evolution and elucidate the driving forces behind the evolutionary mechanisms. We use various model and non-model organisms including Arabidopsis, duckweed and green algae, by utilizing interdisciplinary approaches, ranging from population genetic analysis, lab experiments and field works.