In our field research in the tropics of Southeast Asia, we have described new taxa, and have also started evo-devo research focusing on unique leaf morphology. For example, we have been analyzing the developmental and evolutionary mechanisms of indeterminate leaves (leaves that can grow indeterminately: a unique developmental pattern shown by Monophylla and Guarea) found in the tropics, using RNA-seq as a starting point. The evolution of narrow leaves in rheophyte plants adapted to high rainfall environments, the development of pouch-like structures at the base of leaf blades in ant plants, and the evolution of scaly leaves in parasitic plants, are also examples of projects that began with tropical research. Besides, we are analyzing the mechanism of unifacial leaves in the genus Juncus. We are trying to deepen our understanding of the developmental mechanism of leaves with unique morphology, which is not seen in Arabidopsis, by applying our knowledge of model plants.