Cashew Family (Anacardiaceae)

The lacquer tree (Rhus verniciflua) occurs in China and Japan, where the viscous, milky sap of this plant has long been collected and applied as a natural varnish to fine wood carvings and furniture. The sap turns dark after oxidation in the atmosphere, providing an attractive, glossy coating to oriental lacquerware. A lacquer finish is resistant to heat, moisture, acid, alkali, and alcohol, and is therefore an excellent protection for fine works of art. Lacquering is an old art form, although it reached its greatest expression in China during the Ming Dynasty of 1368-1644 and in Japan during the seventeenth century. The finest pieces of lacquerware received as many as hundreds of individual coatings, applied over a period of several years. Other minor sources of lacquer are the Burmese lacquer tree (Melanorrhoea usitata) and an Indonesian sumac (Rhus succedanea).

The leaves of some species in the cashew family are dried and processed as a source of tannins, chemicals that are useful for preparing leather. The Sicilian sumac (Rhus coriaria) of southern Italy is especially useful, as its leaves can have a tannin concentration of 20-35%. This species is actually cultivated as a source of tannins, and it produces a superior, soft leather with a pale color, considered especially useful for fine gloves and bookcovers. The red quebracho (Schinopsis lorentzii) of South American temperate forests is another important source of tannins, which are obtained from the wood of this tree. The dried leaves of native sumacs (Rhus spp.) of North America have also been used as a minor source of tannins.

Poison ivy growing on a tree trunk. © Carolina Biological Supply/Phototake NYC. Reproduced with permission.

Chios mastic is a type of resin derived from the dried sap of Pistacia lentiscus of the Mediterranean region, while Bombay mastic is obtained from P. cabulica of southern Asia. These materials are used to manufacture a clear, high-grade varnish, which is sometimes used to coat metallic art and pictures, and in lithography.

The terebinth tree (Pistacia terebinthus) was the original source of artists' turpentine, but this solvent is now more commonly distilled from other types of trees. Another minor product is a yellow dye obtained from the twigs of the tropical South American tree, Cotinus cuggygroa.