The "Yamabuki-so" (Chelidonium japonicus) belongs to Papaveraceae (the Poppy family). It is a perennial herb that is distributed westward from Honshu to Shikoku, Kyushu in Japan, as well as the Korean Peninsula and China. This herb grows in wet woods and can reach about 30 cm in height. The leaves are impari-pinnate with irregular serrated leaflets. The flowers are yellow, Bachelor's button-like and four-petaled, and bloom from April to May. It is also known as "kusa-yamabuki" in Japan. In Chinese, it is "荷青花" (he qing hua).