guayule wīyo͞oˈlē, gwä– [key], multibranched flowering evergreen shrub, Parthenium argentatum, native to the deserts of the SW United States and N Mexico. Growing to 3 ft (1 m) in height, the guayule has leaves and outer stems that are covered with silvery hairs; its small yellow-white composite flowers are produced in clusters. Sometimes used as a landscape plant in dry areas, the shrub has been primarily of interest, since the early 1900s, as an alternative source of rubber, and was widely planted for that purpose in California and the Southwest during World War II. The rubber produced from the latex found in the bark of the stems is used in a number of products, including gloves for individuals allergic to latex from the Pará rubber tree. Resin from the shrub is used as a wood preservative, and pulp from processing is used in particle board. The guayule is classified in the division Magnoliophyta, class Magnoliopsida, order Asterales, family Asteraceae.

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