The "Shiro-yanagi" (Salix jessoensis) belongs to Salicaceae (the Willow family). It is a tall deciduous tree that is distributed from Hokkaido to Tohoku-Hokuriku district and northern Kanto district of Honshu in Japan. This tree grows in river beds, has round crown, reaching a height of 15-20 m. The bark is pale grayish brown and furrowed longitudinally. The leaves are linear with acute small toothed edges. The back side of the leaf is powdery white and covered with dense silk hair. It is dioecious. The flowers come with new leaves from March to April. The fruits are seed capsules, ripen in June, and splitting open.