Pará rubber tree [key], large tree (Hevea brasiliensis) of the family Euphorbiaceae (spurge family), native to tropical South America and the source of the greatest amount and finest quality of natural rubber. Today most Pará rubber is produced from trees grown on plantations in Asia and to a lesser extent in Africa. The yellow or white latex from which rubber is made occurs in numerous specialized latex vessels in the bark, especially outside the phloem. The tree is tapped by making careful incisions, as deep as possible without injuring the tree's growth, in a herringbone pattern or often in a lefthand spiral of 30° around the trunk, for the latex vessels spiral to the right at an angle of about 30° from the horizontal. The latex is collected in small cups and then treated—usually by coagulating it with acid, pressing it free of water, and drying the resultant sheets in a smokehouse to ready them for shipment. The size of the tree, the quality of the latex, and the number of taps possible varies with individual trees; the quantity of latex increases with the age of the tree, which may grow to a height of over 100 ft (30 m). Cultivated trees are tapped throughout the year, usually in the early morning, when the latex flow is greatest. Sometimes other trees that yield latex are also called Pará rubber trees. Pará rubber trees are classified in the division Magnoliophyta, class Magnoliopsida, order Euphorbiales, family Euphorbiaceae.
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