Ethnobotanical review of traditional use of wild food plants in Japan

Japan, which has a diverse climate, is home to 8118 species of wild vascular plants, with more than 1000 of these species considered edible. However, there are fewer studies on the use of wild food plants in Japan than in other parts of the world. This research aims to provide an ethnobotanical review of the traditional food use of wild plants in Japan. It draws upon the largest database of traditional Japanese foodways, with a specific focus on the period approximately 1930. This occurred prior to Japan's rapid economic growth, which resulted in significant changes in the use of wild plants. The use of wild food plants in Japan was reviewed by studying the collection of Japanese foodways (Nihon no shokuseikatsu zenshu), which is the largest database on Japanese traditional foodways and contains records of approximately 52,000 dishes, including food uses of wild plants. The review extracted the local and common names, use locations, uses, processing and cooking methods, habitats and other relevant details pertaining to the reported use of wild food plants. This information was subsequently analyzed via Excel. A total of 268 taxa belonging to 87 families used in Japan approximately 1930 were documented. Asteraceae was the most frequently reported family as well as the most species-rich family. In terms of use, vegetables composed the largest group, followed by dessert fruits. The majority of species have been documented in only a limited number of reports. The review revealed local traditional uses of plants, including the use of plants as binders for making rice cake, the selection of plants according to their sex, and techniques for detoxifying toxic plants. A comparison with those of previous studies on wild species used in other Asian regions revealed a similar preference for vegetables. However, notably, in Japan, ferns are also consumed in considerable quantities. Conversely, further elucidation is clearly needed with respect to certain matters, including the perception of plant sex and the relationships between diverse ash components and detoxification techniques. It is evident that further ethnobotanical research is needed, both in the form of an examination of ethnographic records and in the field, to gain a deeper understanding of the use of wild food plants in Japan.