Teak (Tectona grandis) is a tropicalhardwood tree species in the familyLamiaceae. It is a large,deciduous tree that occurs in mixed hardwood forests.Tectona grandis has small, fragrant white flowers arranged in dense clusters (panicles) at the end of the branches. These flowers contain both types of reproductive organs (perfect flowers). The large, papery leaves of teak trees are oftenhairy on the lower surface. Teak wood has a leather-like smell when it is freshly milled and is particularly valued for its durability and water resistance. The wood is used for boat building, exterior construction, veneer, furniture, carving, turnings, and various small projects.[citation needed]
Teak is a largedeciduous tree up to 40 m (131 ft) tall with grey to greyish-brown branches, known for its high-quality wood. Its leaves areovate-elliptic to ovate, 15–45 cm (5.9–17.7 in) long by 8–23 cm (3.1–9.1 in) wide, and are held on robustpetioles which are 2–4 cm (0.8–1.6 in) long.Leaf margins are entire.[6]
Fragrant white flowers are borne on 25–40 cm (10–16 in) long by 30 cm (12 in) widepanicles from June to August. Thecorolla tube is 2.5–3 mm long with 2 mm wide obtuse lobes.Tectona grandis sets fruit from September to December; fruits are globose and 1.2–1.8 cm in diameter.[6] Flowers are weaklyprotandrous in that theanthers precede thestigma in maturity and pollen is shed within a few hours of the flower opening.[7] The flowers are primarilyentomophilous (insect-pollinated), but can occasionally beanemophilous (wind-pollinated).[8] A 1996 study found that in its native range in Thailand, the major pollinators were species in the bee genusCeratina.[7]
Teak forest with large foliage in Parambikulam Tiger Reserve, India
Teak forest in Nilambur, India
Illustration showing detail of leaves, buds and flowers
Wood texture is hard and rings are porous. The density varies according to moisture content: at 15% moisture content it is 660 kg/m3.[9] The heartwood is yellowish to golden-brown. Sapwood is whitish to pale yellowish brown. It can easily separate from heartwood.[citation needed] Teak darkens as it ages. There can be a large variation, depending on which region the teak is from. Old growth has much tighter rings than new growth.[10] There is a leather-like scent in newly cut wood.[11]
Tectona grandis was first formally described byCarl Linnaeus the Younger in his 1782 workSupplementum Plantarum.[12] In 1975,Harold Norman Moldenke published new descriptions of fourforms of this species in the journalPhytologia. Moldenke described each form as varying slightly from thetype specimen:T. grandis f.canescens is distinguished from the type material by being denselycanescent or covered in hairs, on the underside of the leaf,T. grandis f.pilosula is distinct from the type material in the varying morphology of the leaf veins,T. grandis f.punctata is only hairy on the larger veins on the underside of the leaf, andT. grandis f.tomentella is noted for its dense yellowishtomentose hairs on the lower surface of the leaf.[13]
The wordteak derives from thePortugueseteca fromMalayalamthekku (cognate withTamiltekku,Teluguteku, andKannadategu), and was first used in English in the 1690s.[14]
Tectona grandis is found in a variety of habitats and climatic conditions from arid areas with only 500 mm (20 in) of rain per year to very moist forests with up to 5,000 mm (200 in) of rain per year. Typically, though, the annual rainfall in areas where teak grows averages 1,250–1,650 mm (49–65 in) with a 3–5 month dry season.[16]
Teak's naturaloils make it useful in exposed locations and make the timber termite- and pest-resistant. Teak is durable even when not treated with oil or varnish. Timber cut from old teak trees was once believed to be more durable and harder than plantation-grown teak. Studies have shown that plantation teak performs on par with old-growth teak in erosion rate, dimensional stability, warping, and surface checking, but is more susceptible to colour change from UV exposure.[17]
The vast majority of commercially harvested teak is grown on teak plantations found inIndonesia and controlled byPerum Perhutani (a state-owned forest enterprise) that manages the country's forests. The primary use of teak harvested in Indonesia is in the production of outdoor teak furniture for export.Nilambur inKerala, India, is also a major producer of teak and is home to the world's oldest teak plantation.[18]
Teak consumption raises several environmental concerns, such as the disappearance of rare old-growth teak. However, its popularity has led to growth in sustainable plantation teak production throughout the seasonally dry tropics inforestryplantations. TheForest Stewardship Council offers certification of sustainably grown and harvested teak products. Propagation of teak via tissue culture for plantation purposes is commercially viable.[citation needed]
Teak plantations were widely established inEquatorial Africa during theColonial era. These timber resources, as well as the oil reserves, are at the heart of the current (2014)South Sudanese conflict.[19]
Much of the world's teak is exported byIndonesia andMyanmar. There is also a rapidly growing plantation-grown market in Central America (Costa Rica) andSouth America. With a depletion of remaining natural hectares of teak forests, growth in plantations in Latin America is expected to rise.[20]
Hyblaea puera, commonly known as the teak defoliator, is amoth native to southeast Asia. It is a teak pest whosecaterpillar feeds on teak and other species of trees common in the region of Southeast Asia.[21]
Teak's high oil content, high tensile strength, and tight grain make it particularly suitable where weather resistance is desired. It is used in the manufacture of outdoorfurniture and boatdecks. It is also used forcutting boards, indoorflooring,countertops, and as aveneer for indoor finishings. Although easily worked, it can cause severe blunting on edged tools because of the presence of silica in the wood. Over time teak can weather to a silvery-grey finish, especially when exposed to sunlight.[22]
Teak is used extensively in India to make doors and window frames, furniture, and columns, and beams in homes. It is resistant totermite attacks and damage caused by otherinsects. Mature teak fetches a very good price. It is grown extensively by forest departments of different states in forest areas. It was also used in the construction of theKaaba in theMasjid al-Haram of Mecca, which is the holiest structure in the Islamic faith.[23]
Leaves of the teak wood tree are used in making Pellakai gatti (jackfruit dumpling), wherebatter is poured into a teak leaf and steamed.[24] This type of usage is found in the coastal district ofUdupi in theTulunadu region in SouthIndia. The leaves are also used ingudeg, a dish of young jackfruit made inCentral Java,Indonesia, and give the dish its dark brown colour.
Teak has been used as aboatbuilding material for over 2000 years (it was found in an archaeological dig inBerenice Panchrysos, a port on theIndian Roman trade route).[25] In addition to relatively high strength, teak is also highly resistant to rot,[26] fungi, and mildew. The wood has a relatively low shrinkage ratio,[27] which makes it excellent for applications where it undergoes periodic changes in moisture. Teak has the unusual property of being both an excellent structural timber for framing or planking, while at the same time being easily worked and finished, unlike some otherwise similar woods such aspurpleheart.[28][29] For this reason, it is also prized for the trim work on boat interiors. Due to the oily nature of the wood, care must be taken to properly prepare the wood before gluing.[30]
When used on boats, teak is also very flexible in the finishes that may be applied. One option is to use no finish at all, in which case the wood will naturally weather to a pleasing silver grey.[31] The wood may also be oiled with a finishing agent such aslinseed ortung oil.[32] This results in a somewhat dull finish. Finally, teak may also be varnished for a deep, lustrous glow.
Teak is also used extensively in boatdecks, as it is extremely durable but requires regular maintenance. The teak tends to wear into the softer 'summer' growth bands first, forming a natural 'non-slip' surface.[31] Any sanding is therefore only damaging. The use of modern cleaning compounds, oils, or preservatives will shorten the life of the teak, as it contains natural teak oil a very small distance below the white surface. Wooden boat experts will only wash the teak with salt water, and re-caulk when needed. This cleans the deck and prevents it from drying out and the wood shrinking. The salt helps it absorb and retain moisture and prevents any mildew and algal growth. Over-maintenance, such as cleaning teak with harsh chemicals, can shorten its usable lifespan as decking.[26] Teak has been used by the U.S. Navy for ship decks, such as theIowa-class battleshipUSS Missouri, to protect against sparks caused by metal rubbing on metal, and as insulation to avoid the interior of the ship getting too hot.[33]
Teak is propagated mainly from seeds. Germination of the seeds involves pretreatment to remove dormancy arising from the thick pericarp. Pretreatment involves alternate wetting and drying of the seed. The seeds are soaked in water for 12 hours and then spread to dry in the sun for 12 hours. This is repeated for 10–14 days and then the seeds are sown in shallow germination beds of coarse peat covered by sand. The seeds then germinate after 15 to 30 days.[34][35]
Clonal propagation of teak has been successfully done through grafting, rooted stem cuttings, and micropropagation. While bud grafting onto seedling root stock has been the method used for establishing clonal seed orchards that enables assemblage of clones of the superior trees to encourage crossing, rooted stem cuttings and micro propagated plants are being increasingly used around the world for raising clonal plantations.[36]
Illegal logging is prevalent in countries with natural teak forests, including India and Burma.[37]
Since 1989, the state-ownedMyanma Timber Enterprise has run the country's logging industry.[38] In 2014, Myanmar's government imposed a strict ban on exporting wild-grown teak logs.[39] In 2015, 153 Chinese loggers were sentenced to life in prison for illegal logging.[40] Illegal teak logging persists, especially in contested areas.[39] While it is illegal for timber to be exported via land borders, 95% of Myanmar's teak enters China through theChina–Myanmar border.[38]
Since the2021 Myanmar coup d'état, illegal logging of teak and tamalan trees has surged in Sagaing Region, predominantly in key contested battlegrounds, includingKani,Yinmabin,Kantbalu,Indaw, andBanmauk townships.[41] Both the Burmese military and resistance groups have profited from the illegal logging trade.[41] Smugglers transport the wood to India to circumventeconomic sanctions and use the Myanma Timber Enterprise to license the wood as being sourced from permitted areas.[41][42]
The regulation that addresses the import of timber, including teak, into the EU from unknown or illegal sources is theEU Timber Regulation (EUTR) No. 995/2010. This regulation aims to prevent the trade of illegally harvested timber and timber products within the EU market. It places an obligation on operators who place timber and timber products on the EU market to ensure they are legally harvested.
This regulation specifically applies toteak and other high-risk timber species, particularly those sourced from countries with poor forest governance or illegal logging activities. Myanmar, for example, has been a focus due to concerns over illegal teak harvesting from there.[43]
Previously, the world's biggest recorded teak tree was located within theParambikulam Wildlife Sanctuary in thePalakkad District ofKerala in India, named Kannimara. The tree is approximately 47.5 metres (156 ft) tall. Its age is between 450 and 500 years and is considered one of the oldest teak trees in the world.[45][46]
In 2017, a tree was discovered in the Ottakallan area of the Thundathil range of the Malayattoor Forest Division in Kerala with a girth of 7.65 metres (25.1 ft) and a height of 40 metres (130 ft).[47] A teak tree in Kappayam, Edamalayar, Kerala, which used to be considered the biggest, has a girth of 7.23 metres.[47]
Tree No. 23 is the oldest planted teak on Earth. It is located in Conolly's plot (the world's oldest teak plantation),Nilambur, Kerala.[48]
^Herbison-Evans, Don (6 September 2007)."Hyblaea puera". University of Technology,Sydney. Archived fromthe original on 24 July 2008. Retrieved12 March 2008.
^"49 pieces of the world's most powerful wood hold the Kaaba".Al Arabiya English.Al Arabiya. 9 December 2016. Retrieved27 May 2023.The roof of the Kaaba is held by 49 piece of teak wood brought from Burma and processed in Jeddah. They were evenly distributed on the walls of the Kaaba.
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