"Tairin-aoi" (Heterotropa asaroides) belongs to Aristolochiaceae (the Birthwort family). It is an evergreen perennial herb that is distributed to western part of Chugoku region of Honshu and northern part of Kyushu in Japan. This herb grows in the forest of the mountainous area, and the height becomes 10-15 cm. Leaves are broad ovate, ovate-elliptic or triangular-ovate, green, dull and having cloudlike mottles on the surface. The flowers are dark purple, 3-4 in diameter will bloom from April to May. The calyx tubes are urceolate with large constricted parts at the top of the tubes. The calyx lobes are triangular-round.