Other Spurges and Their Uses
Many spurges are of great economic importance as a source of food, drugs, rubber, and other products. The sap of most species is a milky latex, and the source of a very large part of the world's natural rubber is the latex of the Pará rubber tree. Pará rubber and several other latexes also come from plants of the spurge family. The tropical American Manihot genus includes the cassava, the source of tapioca and the most important tropical root crop next to the sweet potato.
Other valuable commercial products of this family are castor oil and tung oil, expressed from the seeds of Ricinus communis and Aleurites fordii respectively. The castor bean, the source of castor oil, is native to tropical Africa, where it grows as a tree, but is now widespread and is sometimes cultivated in temperate regions as an annual ornamental. The tung tree, indigenous to E Asia and Malaysia, is the only important plant of the spurge family cultivated commercially in the United States. The candlenut tree ( A. moluccana ) and the Japanese wood oil tree ( A. cordata ), of the same genus as the tung tree, also yield oils, as does the Chinese tallow tree ( Sapium sebiferum ), a source of grease for candles and soap.
Various spurges provide medicines, dyes, oils, and other products; primitive peoples utilized the poisonous saps of other spurges on arrow tips and to poison fish. The presence of poisonous substances in many euphorbias and in a number of other spurges has led these to be classed as noxious pests, especially when they grow as weeds on livestock ranges.
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