"Wadan" (Crepidiastrum platyphyllum) belongs to Asteraceae (the Aster family). It is a perennial herb that is distributed from the southern part of the Kanto region to the Tokai region in Honshu, Japan. It grows on coastal cliffs and rocks and can reach 30-60 cm in height. The rhizome is woody and has round to spatula-shaped leaves. When you cut the leaves and stems, you will get a white milky lotion. From September to November, yellow flowers resembling "Yakushi-so" come in bloom. It is a one-time breeding type and withers when it blooms. The origin of the Japanese name is unknown, but there is a theory that what was called "Wadatsumi-na" or "Wata-na" was transformed into "Wadan". By the way, "wadatsumi" is an old word for "sea".