A tropical South American tree (Hevea brasiliensis) widely cultivated throughout the Tropics and yielding a milky juice that is a major source of commercial rubber. South American tropical tree (Hevea brasiliensis) of the spurge family. Cultivated on plantations in the tropics and subtropics, especially in Southeast Asia and western Africa, it replaced the rubber plant in the early 20th century as the chief source of natural rubber. It has soft wood, high, branching limbs, and a large area of bark. The milky liquid (latex) that oozes from any wound to the tree bark contains about 30% rubber, which can be coagulated and processed into solid products such as tires. Latex can also be concentrated for producing dipped goods such as surgical gloves