This volume is a collection of papers presented at the International Symposium "Let's Talk about Trees" organized by Kikusawa and hosted at the National Museum of Ethnology, Osaka, Japan on February 10, 2013. The purpose of this symposium was to evaluate and examine what it means to apply a "tree model" to express linguistic relationships, and what the advantages and potential pitfalls are in doing so. Specialists of other disciplines such as cladistics, biology, and genetics, where diagrams are also used to express the "relationships" of targeted objects were also invited to participate.