The "Suda-jii" (Castanopsis sieboldii) belongs to Fagaceae (the Beech family). It is a tall evergreen tree that is distributed from Fukushima prefecture of Honshu west to Shikoku, Kyushu in Japan and Jeju-do (southern Korea). This tree grows in the coastal mountains in warm climate and can reach about 30 m in height. The leaves are broad elliptic, alternate with silvery brown hairs on the reverse sides. The panicles are borne upward in May to June. The fruits are conical-ovate nuts covered with bracts. They ripen in October and edible without removing the astringency. The Timbers are used for architectures, furnitures or dead logs for Shiitake. The origin of the Japanese name is not clear, but there is a view that it is derived from the word "素台木", meaning a rootstock-like tree that serves as the foundation for making "Shiitake mushrooms".