Lignum vitae (/ˈlɪɡnəmˈvaɪti,-ˈviːtaɪ/[1]), also calledguayacan orguaiacum,[2] and in parts of Europe known asPockholz orpokhout, is awood from trees of the genusGuaiacum. The trees are indigenous to the Caribbean and the northern coast of South America (e.g., Colombia and Venezuela) and have been an important export crop to Europe since the beginning of the 16th century. The wood was once very important for applications requiring a material with its extraordinary combination ofstrength,toughness, anddensity. It is also the national tree ofthe Bahamas, and theJamaican national flower.[3]
The wood is obtained chiefly fromGuaiacum officinale andGuaiacum sanctum, both small, slow-growing trees. All species of the genusGuaiacum are now listed in Appendix II ofCITES (the Convention on International Trade in Endangered Species of Wild Fauna and Flora) as potentiallyendangered species.G. sanctum is listed asNear Threatened by theIUCNRed List. Demand for the wood has been reduced by modernmaterials science, which has led topolymers,alloys andcomposite materials that can take lignum vitae's place.
Various other hardwoods may also be called lignum vitae and should not be confused with it. The best-known come fromBulnesia arborea andBulnesia sarmientoi (in the samesubfamily asGuaiacum) and are known asverawood orArgentine lignum vitae; they are somewhat similar in appearance and working qualities as genuine lignum vitae. Note that these species are now[when?]Plectrocarpa arborea andPlectrocarpa sarmientoi. Some hardwoods fromAustralasia (e.g.,Vitex lignum-vitae and some species ofAcacia andEucalyptus) are also referred to as lignum vitae.
Lignum vitae isLatin for "wood of life". The plant derives its name from its medicinal uses; lignum vitae resin has been used to treat a variety of medical conditions fromcoughs toarthritis.
Other names for lignum vitae includepalo santo (Spanish for "holy stick"),Aura palo santo and "bastard greenheart" (not to be confused with true greenheartChlorocardium rodiei, a popular wood in shipbuilding, cabinetry, andwoodturning but a completely different timber). Lignum vitae is also one of the numerous hard, dense woods loosely referred to as "ironwood".
The tree is slow-growing and relatively small in stature, even when mature and old. It bears small, purplish-blue flowers which result in paired orangedehiscent fruits. The bark ismottled.
Lignum vitae is hard and durable, and is also the densest wood traded (average dried density: ~79 lb/ft3 or ~1,260 kg/m3);[4] it will easily sink in water. On theJanka scale of hardness, which measures hardness of woods, lignum vitae ranks highest of the trade woods, with a Janka hardness of 4,390 lbf (compared withOlneya at 3,260 lbf,[5]African blackwood at 2,940 lbf,hickory at 1,820 lbf,red oak at 1,290 lbf,yellow pine at 690 lbf, andbalsa at 100 lbf). The densest of all woods isAllocasuarina luehmannii.[6]Krugiodendron typically has a higher density, among many other woods that vary by sample.
Because of the density of the wood,cricket bails, in particular "heavy bails" used in windy conditions, are sometimes made of lignum vitae. It is also sometimes used to makelawn bowls,croquet mallets, andskittles balls. The wood also has seen widespread historical usage inmortars and pestles and for wood carvers' mallets.
It was the traditional wood used for the British policetruncheon until recently because of both its density and its strength, combined with its relative softness compared to metal, thereby tending to bruise rather than cut the skin.
Thebelaying pins anddeadeyes aboard many historic 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, and also resist jamming in their mortise holes. Thesheaves ofblocks on sailing vessels were made of lignum vitae until the introduction of modern synthetics.
Lignum vitae's toughness also allows its use as alap in the process of cutting gems.[citation needed] The wood is covered with powdered industrial diamond, attached to a spindle, and used to smooth rough surfaces of gems.
John Harrison used lignum vitae in the bearings and gears of hispendulum clocks and his first threemarine chronometers as the wood is self-lubricating. The use of lignum vitae eliminates the need forhorologicallubricating oil; 18th-century horological oil would become viscous and reduce the accuracy of a timepiece under unfavourable conditions (including those that prevail at sea).
For the same reason it was widely used in water-lubricated shaft bearings for ships and hydro-electric power plants[7] and in thestern-tube bearings of ship propeller shafts[8] until the 1960s saw the introduction of sealedwhite metalbearings. According to the San Francisco Maritime National Park Association website, the shaft bearings on the WWII submarineUSS Pampanito (SS-383) were made of this wood.[9] The aft main shaft strut bearings forUSS Nautilus (SSN-571), the world's first nuclear-powered submarine, were composed of this wood. Also, the bearings in the original 1920s turbines of theConowingo hydroelectric plant on the lowerSusquehanna River were made from lignum vitae. The shaft bearings on the horizontal turbines at thePointe du Bois generating station in Manitoba are made from lignum vitae. Other hydroelectric plant turbine bearings, many of them still in service, were fabricated with lignum vitae and are too numerous to be listed here.[10]
TheUnited Railroads of San Francisco (an ancestor of theSan Francisco Municipal Railway) began installing insulators made of composite materials to support the heavy 600-volt DC feeder wires for their trolley system in 1904. These lines were damaged, along with most everything else, during the1906 earthquake and the fires that followed. Rebuilding the trolley system and expanding it to replace cable car routes destroyed in the quake created a huge demand for insulators, a demand manufacturers further east were unable to meet. The properties of lignum vitae, namely its ability to withstand high stress (from heavy cables on long spans and the strain of lines rounding corners) and high temperature (from the feeder cables' becoming very hot during peak operating hours), and its ready availability from the holds of the ships in the harbor (where it served asdunnage andballast) made it an ideal "temporary" solution. Many were still in use well into the 1970s, and the final few were replaced with underground feeder systems in the 2000s.[11][12]
It was also used extensively in the manufacture of British Railways Mark 1 rolling stock, as a "bump stop" in the bogies (the frame that carries the wheels).
Calypsonian/vaudevillianSam Manning recorded a song titled "Lignum Vitae" in the 1920s.[13]
Benvenuto Cellini recounts using lignum vitae, presumably decocted, to cure himself of avenereal disease, the "French Pox", presumablysyphilis.[14]
According toT. H. White's version of theArthurian legend,The Once and Future King,Merlin's wand is made of lignum vitae and has magical powers.
Gabriel García Márquez's novelLove in the Time of Cholera includes a bathtub made of this wood in one of the main characters' homes. His novelChronicle of a Death Foretold also refers to the use of this wood in making a cane for the blind Poncio Vicario.
American folksingerPete Seeger fashioned the neck of his trademarkbanjo from lignum vitae.
InCharles Dickens' novelBleak House, one of the characters, Matthew Bagnet is referred to as lignum vitae, "in compliment to the extreme hardness and toughness of his physiognomy."
InPhilip Pullman's novelThe Secret Commonwealth, the heroineLyra Belacqua carries a truncheon made from lignum vitae as a weapon.
InFinal Fantasy XIV: Shadowbringers, lignum vitae logs are a crafting material commonly used by carpenters.
