rubber tree, (Hevea brasiliensis), South American tropical tree of the spurge family (Euphorbiaceae). 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 percent rubber
