Pentasachme caudatum belongs to Asclepiadaceae (the Milkweed family). It is a perennial herb that is distributed to southern China, the Indochina Peninsula, Burma, Bangladesh and India. This herb grows in mountain thin forests, thickets, along stream and can reach 30-80 cm in height. The leaves are linear-lanceolate and arranged in opposite with short petioles. The 4-8 white flowers bloom at the axils from April to October. All parts are used for herb treatment of hepatitis, nephritis, conjunctivitis and sore throat.