Photos Of Plant Resins & Waxes
http://waynesword.palomar.edu/ecoph22.htm
http://waynesword.palomar.edu/images/bunres2.jpg B. Resins: Plant exudates containing nonvolatile 20-carbon diterpenes and 30-carbon triterpenes that are insoluble in water but soluble in organic solvents. [Have you ever tried to wash pine pitch off your hands in water?] Oleoresins (oleo referring to the essential oil component) contain nonvolatile terpenes plus volatile 10-carbon monoterpenes and 15-carbon sesquiterpenes. Resins are generally produced by cells lining resin ducts or canals in stems and leaves. Resins repel insects (such as bark beetles), deter vertebrate herbivores, and inhibit the growth of fungi and bacteria. Exuded resins aid in the healing of wounds and prevent desiccation. The resin glob at left came from the trunk of the Australian bunya-bunya (Araucaria bidwillii). The leaves of some desert shrubs, such as creosote bush (Larrea tridentata) have a glistening resinous coating that reduces water loss through transpiration. Although it has a similar odor, this resin is not the commercial source of creosote. The commercial source of creosote is derived from the distillation of coal tar. It is produced by high temperature carbonization of bituminous coal. Wood creosote is obtained from the distillation of wood tar from several woods of the eastern United States. Wood creosote is a mixture of phenolic compounds that are used medicinally as an antiseptic and expectorant. Under no circumstances should coal tar creosote be taken internally. Although creosote bush does not grow in the chaparral plant community, the dried leaves of this shrub are the source of "chaparral tea," a controversial herbal remedy with antitumor properties. The leaves contain a powerful antioxidant that apparently destroys tumor cells; however, there are reported cases of liver toxicity, including toxic hepatitis and jaundice.
Some resins are referred to as gums, but they are chemically very different. True gums are complex polysaccharides composed of many sugar subunits. Although the sap of the mastic tree (P. lentiscus) is called a gum, it is really an oleoresin used in perfumes, chewing gums, pharmaceuticals, dental adhesives, and in high grade varnishes for protecting pictures. Gum mastic is one of the oldest known high grade resins utilized by people, and it is extensively cultivated on the Greek island of Chios. Gum guaiac is another famous resin from a Caribbean tree called lignum vitae (Guaiacum officinale), one of the world's hardest and heaviest woods. A similar species (G. sanctum) is native to the Florida Keys. Both species are members of the caltrop family (Zygophyllaceae) along with North and South American creosote bush and the ubiquitous puncture vine (Tribulus terrestris). The name lignum vitae means "wood of life," owing to the medicinal properties of the heavy, resinous wood. During the days of masted sailing ships, the wood and sweet-smelling resin globs were sought after for treatments and cures for a variety of human ailments, including gout, syphilis and rheumatism. Today the resin is still used for expectorants and as a dye to detect the presence of occult (hidden) blood. Peroxidase enzymes in the blood cells oxidize chemicals in the resin resulting in a characteristic blue-green color change. The raw resin contains about 15 percent vanillin (artificial vanilla), resulting in the sweet aroma. The density and high resin content of the wood make it extremely resistant to friction and abrasion and account for its remarkable self-lubrication properties. In fact, under certain conditions the wood wears better than iron. Because of this, the wood has been highly valued for pulley sheaves, bearings, casters, food-handling machinery, and especially for end grain thrust blocks which once lined the propeller shafts of steamships. During World War I, attempts were made to use other ironwoods such as Tabebuia guayacan from Central America for propeller shaft bearings, but the wood lacked the oily resin of lignum vitae.
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