Lignum vitae is a trade wood, also called guayacan or guaiacum,[1] and in parts of Europe known as pockenholz, from trees of the genus Guaiacum. This wood was once very important for applications requiring a material with its extraordinary combination of strength, toughness and density. It is also the Jamaican national flower.[2]
The wood is obtained chiefly from Guaiacum officinale and Guaiacum sanctum, both small, slow growing trees. All species of the genus Guaiacum are now listed in Appendix II of CITES (the Convention on International Trade in Endangered Species of Wild Fauna and Flora) as potentially endangered species. Demand for the wood has been reduced by modern materials science, which has led to polymer, alloys and composite materials which can take lignum vitae's place.
"Lignum vitae" is Latin for "wood of life", and derives from its medicinal uses; lignum vitae resin has been used to treat a variety of medical conditions from coughs to arthritis, and chips of the wood can also be used to brew a tea. Other names for lignum vitae include palo santo (Spanish for "holy wood") and greenheart; lignum vitae is also one of the numerous hard, dense woods referred to as ironwood.
Lignum vitae is hard and durable, and is also the densest wood traded; it will easily sink in water. On the Janka Scale of Hardness, which measures hardness of woods, lignum vitae ranks highest of the trade woods, with a Janka hardness of 4500 lbf (compared with African Blackwood at 2940 lbf, Hickory at 1820 lbf, red oak at 1290 lbf, Yellow Pine at 690 lbf, and Balsa at 325 lbf). The heartwood is green in color leading to the common name Greenheart. In the shipbuilding, cabinetry, and woodturning crafts the term greenheart refers to the green heartwood of Chlorocardium rodiei.
Various other hardwoods of Australasia (e.g., some species of Acacia and Eucalyptus) may also be called lignum vitae and should not be confused. The best-known is from Bulnesia arborea and Bulnesia sarmientoi (in the same subfamily as Guaiacum) and is known as Verawood or Argentine lignum vitae; it is somewhat similar in appearance and working qualities as genuine lignum vitae. In the early 2000s the Dogfish Head brewery commissioned a 10,000 gallon brewing barrel made of the latter after hearing that locals used this wood for wine production.[3]
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Due to its density, cricket bails, particularly "heavy bails" used in windy conditions, are sometimes made of lignum vitae. It is also sometimes used to make lawn bowls, croquet mallets and skittles balls. The wood also has seen widespread historical usage in mortars and pestles and for wood carvers' mallets.
It was the traditional wood used for British police truncheon until recently, due to its density (and strength), combined with the relative softness of wood compared to metal, thereby tending to bruise or stun rather than simply cut the skin.
The belaying pins and deadeyes aboard the USS Constitution and many other sailing ships were made from lignum vitae. Due to its density and natural oils, they rarely require replacement, despite the severity of typical marine weathering conditions.
Due to lignum vitae's toughness, it can also be used as a lap in the process of cutting gems. The wood is covered with powdered industrial diamond, attached to a spindle, and used to smooth rough surfaces of gems.
Master clockmaker John Harrison used lignum vitae in the bearings and gears of his pendulum clocks and his early marine timekeepers, since the wood is self-lubricating.
For this same reason it was widely used in water lubricated shaft bearings for ships and hydro-electric power plants. Commonly used in ship's propeller stern-tube bearings, due to its self-lubricating qualities, until the 1960s with the introduction of sealed white metal bearings. According to the San Francisco Maritime National Park Association website, the shaft bearings on the WWII submarine USS Pampanito (SS-383) were made of this wood.[4] The aft main shaft strut bearings for USS Nautilus (SSN-571), the world's first nuclear powered submarine, were composed of this wood. Also, the bearings in the original 1920s turbines of the Conowingo Hydroelectric Plant on the lower Susquehanna River were made from lignum vitae.
After the 1906 San Francisco earthquake, the urgent need to rebuild the streetcar system and the inability to obtain regular composition, porcelain, or glass insulators for the electrical feeders fast enough, a significant number of insulators were turned from this wood.[5](readily available from the ships in the harbor as ballast) as a "temporary" solution. Many of these lasted into the 1970s with a small number remaining in service as of 2009 (all these that had been removed were done so as part of a project to move these 600 V DC feeder wires underground).
Greenheart was used to make the acclaimed Hardy's Greenheart fly fishing rods, by Hardy Brothers of Alnwick.
Pioneering calypsonian/vaudevillian Sam Manning recorded a song entitled "Lignum Vitae" in the 1920s.[6] His reference was doubly salacious, referring to both the bark tea's contraceptive qualities and the phallic symbolism of the hard wood.
According to T.H. White's version of the King Arthur story The Once and Future King, lignum vitae, from which the wand of Merlin is made, has magical powers.
Gabriel García Márquez's novel Love in the Time of Cholera includes a bathtub made of this wood in one of the main characters' homes. His novel Chronicle of a Death Foretold also refers to this wood being used to make a cane for the blind Poncio Vicario.
American folksinger Pete Seeger fashioned the neck of his trademark banjo from lignum vitae.