The Rubber Tree (Hevea brasiliensis)

The Rubber Tree (Hevea brasiliensis)

Rubber is a valuable commodity in today's economy. A vast number of products are made from it, including washers, gloves, gaskets, tubing, waterproof clothing, toys, erasers, belts, elastics, bottle stoppers, and insulation for electrical wiring. The largest single use of rubber is in the manufacture of pneumatic tires which consumes 60% to 70% of the total world production each year. Demand for rubber has grown remarkably since the beginning of the industrial revolution.

It is one species, Hevea brasiliensis, which makes up 99% of the world's natural rubber production. In 1989 that production was worth an estimated 4 billion dollars.

Hevea brasiliensis (the para rubber tree) is a South American native that can grow to a height of 150 feet. The trees have a smooth bark and palmately compound leaves. They are monoecious and have small inconspicuous flowers. The seeds are akin to castor beans. On ripening, the fruit capsule explodes and propels the seeds away from the tree.

Hevea brasiliensis is a member of the family Euphorbiaceae (the spurge family). Euphorbiaceae is a diverse family with approximately 290 genera and 7,500 species. Within the family, there are herbs, shrubs, trees, and fleshy cactus-like species. Some plants from this family are used for their medicinal properties and edible parts. Others are used simply as ornamentals.

While there are many useful plants in the family Euphorbiaceae, the sweet and bitter cassava plants (Manihot dulcis and Manihot esculenta), as well as the castor oil plant (Ricinus communis), are of greatest economic importance.

Latex bearing plants are found in some 20 botanical families. The most prominent families include Sapotaceae, Moraceae, Compositae, Apocynaceae, Asclepiadaceae, and Euphorbiaceae. In total there are about 18,000 species of latex-producing plants. Yet, only a few species are currently exploited.

Commercially useful rubber-producing species include Hevea benthamiana (Para rubber), Hevea guianensus (Para rubber), Manihot glaziovii (Ceara rubber), Manihot dichotoma (Jeque rubber), Castilla elastica (Panama rubber), Ficus elastica (India rubber), Funtimia elastica (Lagos rubber), Landolphia kirkii (Landolphia rubber), Landolphia gentilli (Landolphia or Madagascar rubber), Landolphia heudelotii (Landolphia or Madagascar rubber), Landolphia owariensis (Landolphia or Madagascar rubber), Crytostegia grandiflora (Madagascar rubber), Crytostegia madagascariansis (Madagascar rubber), Parthenium argentatum (Guayule), Taraxacum kok-saghyz (Russian dandelion), Taraxacum megalorhizon (Russian dandelion), Palaquim gutta (Gutta percha), Manilkara bidentata (Balata), and Manilkara zapata (Chicle).

Depending on the species of plant, the latex may be found in a number of locations. It may be within the cells or intercellular spaces of the roots, stems, or leaves of the plant.