Strophanthus is a genus of 35-40 species of flowering plants in the family Apocynaceae, native mainly to tropical Africa, extending to South Africa, with a few species in Asia, from southern India to the Philippines and southern China. The name (strophos anthos, “twisted cord flower”) derives from the long twisted threadlike segments of the corolla, which in one species (S. preussii) attain a length of 30-35 cm. The genus includes vines, shrubs and small trees. The leaves are opposite or whorled, simple broad lanceolate, 2-20 cm long, with an entire margin. Several of the African tribes used Strophanthus as the principal ingredient in arrow poison. Plants from this genus produce toxic alkaloids and cardiac glycosides g-strophanthin (syn. ouabain), k-strophanthin and e-strophanthin. As ordinarily administered, the drug acts on the heart before influencing any other organ or tissue. Often indeed no other action can be observed. It is used to produce the drug Ouabain which was taken as a cardiac stimulant to treat heart failure, and is similar to the drug Digoxin produced from Digitalis purpurea.

Strophanthus caudatus, synonymously known as Strophanthus dichotomus, Strophanthus griffithii or Strophanthus longicaudatus and commonly known as Tandok-tandok, Tanduk-tanduk or Dudur Kijang, is an exotic evergreen climber of beautiful white star-shaped flowers with long twisting red tendrils coming from the end of each petal. The flowers attract butterflies to the garden. Grow in full sun to semi-shade for optimal growth. It grows natively from Guangxi in southern China, through Indochina (including the Andaman and Nicobar Islands) to Malesia and New Guinea.