A genus of trees belonging to the madder family (Rubiaceae), occurring indigenously in the cool, cloud forests of the Andes from Colombia to Peru. Many species have been described, most of which may be variants of Cinchona pubescens or C. officinalis. The bark contains several alkaloids, the most important of which is quinine. This bitter substance is the most specific drug used in the treatment of malaria. The great demand for quinine and the wasteful methods used in collecting the materials threatened extinction of the plants; therefore cultivation was begun. Now there are extensive cinchona plantations in India, Java, Ceylon, Australia, and Jamaica.