"Matsukaze-so" (Boenninghausenia japonica) belongs to Rutaceae (the Citrus family). It is a perennial that is distributed southward from Miyagi prefecture of Honshu to Shikoku and Kyushu in Japan, and Taiwan. This herb grows in forest edges and landslide scars, and can reach 50-80 cm in height. The leaves are triternate pinnately compound with obovate leaflets. They have glandular dots and a characteristic odor. The cymes are borne on the terminal branches, and the small, four-petaled flowers bloom from August to October.