Lignum Vitae (Ryokudan)

Genuine lignum vitae (Guaiacum) comes from Central America and northern South America and has been exploited for centuries for its wood and resin, leaving populations severely reduced. Argentine lignum vitae grows in the Gran Chaco of Argentina, Paraguay and Bolivia, and much commercial wood comes from Argentina; it is listed as endangered mainly because of projected habitat loss in the Chaco. Guaiacum was among the first CITES-listed timbers in 1975, and the Argentine species later joined it on Appendix II, so international trade in both needs CITES permits.

The two woods look alike but can be separated with a hand lens: Guaiacum pores are solitary and scattered, while Plectrocarpa pores form radial or diagonal rows, and quartersawn Argentine wood shows a feathered or herringbone figure. Genuine lignum vitae is on average darker and its scent is milder and fades sooner; a Japanese pen maker also describes it as waxy and sticky to the touch, unlike the sweet-smelling Argentine wood. The Wood Database calls selling the Argentine species simply as "lignum vitae" a misleading omission, and the name palo santo is also used for an unrelated incense wood, Bursera graveolens; calling ryokudan "green sandalwood" is likewise a misnomer, as it is not sandalwood.

The name lignum vitae is Latin for "wood of life", from the tree's many medicinal uses; it was imported into Europe for medicine from 1508, and demand was such that it reportedly sold for as much as seven gold crowns a pound. Its hardness and self-lubricating oil made it the classic material for ships' propeller shaft bearings, pulley wheels, mallet heads and tool handles. In Japan the wood has mostly been used for Buddhist prayer beads (juzu), and the vernacular name ryokudan was coined on the pattern of shitan (rosewood) and kokutan (ebony); a Japanese timber importer notes that the Argentine wood's resinous heartwood was burned as church incense, hence the name palo santo, "holy wood".