Strophanthus caudatus belongs to Apocynaceae (the Dogbane family). It is a small evergreen tree that is distributed from India to Thailand, the Malay Peninsula and Java. This tree grows up to 2-6 m in height, and the leaves are oblong to elliptical and opposite. The yellow flowers come in, and the calyxes grow long and hang down. In eastern India, it has been used for women's hair ornaments. In addition, the branches and the seeds contain the steroid strophanthin, which has been used as an arrow poison, but is now used as a raw material for cardiac stimulants.