It comes from the dried leaves of Isatis indigotica, a cruciferous plant. Isatis indigotica is the source plant of Isatis indigotica, and its leaves are Isatis indigotica. Both Isatis indigotica and Isatis indigotica are from Isatis indigotica, a cruciferous plant. Planting and processing of Isatis indigotica leaves are carried out in summer and autumn. After harvesting, impurities are removed and dried.

Folium Isatidis has the main functions of clearing away heat and toxic materials, cooling blood and stopping bleeding, and can be used to treat diseases such as excessive thirst due to epidemic febrile disease, influenza, acute infectious hepatitis, bacillary dysentery, acute gastroenteritis, acute pneumonia, erysipelas, hematemesis, epistaxis, jaundice, dysentery, laryngitis, aphtha, carbuncle and swelling.