Many plants produce latex, which oozes from cuts and injuries as a milky sap. Special cells called laticifers produce latex. In general, latexes have a biological function in herbivore defense and/or laticifers are a dumping ground for metabolic by-products or reservoirs of biosynthetic materials. All latexes are emulsions, aqueous suspensions of insoluble materials which can include alkaloids, terpenes, resins, phenolics, proteins, sugars, and long-chain hydrocarbons. Not all latexes are elastic; those that are contain long-chain hydrocarbons. Some latexes are collected for their resins or their alkaloids (opium).

Rubber is a coagulated, elastic latex. Plants that produce elastic latexes are largely neotropical. Commercial rubber is produced from latex of Hevea brasiliensis. The water proofing and elastic properties (rubber balls) of various rubber producing plants were discovered by native American cultures, the Aztecs or earlier mesoamericans, and South American tribes.

Orginially collected from wild trees in South America, now 90% of rubber production comes from plantations of rubber trees in Southeast Asia.