The "Zuda-yakushu" (Tiarella polyphylla) belongs to Saxifragaceae (the Saxifrage family). It is a perennial herb that is native to Hokkaido, Honshu and Shikoku of Japan. This herb grows in montane to sub-alpine wettish forests and can reach 20-40 cm in height. The stem is erect and covered with glandular hairs, together with petioles. The leaves are cordate-round and divided into five lobes shallowly. The racemes are borne and the small white flowers bloom from May to July. The petals are needle-like and the sepals are petaloid. The fruits are capsules and covered with two short and long, boat-shaped carpels. The Japanese name comes from the Shinshu dialect word for asthma, "zuda", and the plant's use as a folk medicine.