| Tetraclinis | |
|---|---|
 | |
Scientific classification | |
| Kingdom: | Plantae |
| Clade: | Tracheophytes |
| Clade: | Gymnospermae |
| Division: | Pinophyta |
| Class: | Pinopsida |
| Order: | Cupressales |
| Family: | Cupressaceae |
| Subfamily: | Cupressoideae |
| Genus: | Tetraclinis Mast. |
| Species: | T. articulata |
| Binomial name | |
| Tetraclinis articulata | |
 | |
| Natural range | |
| Synonyms | |
| |
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Tetraclinis (also called arar,[2] araar[3] or Sictus tree) is agenus ofevergreenconiferous trees in the cypress familyCupressaceae, containing only one species,Tetraclinis articulata, also known asThuja articulata,[4]sandarac,sandarac tree[5] orBarbary thuja,[6]endemic to the westernMediterranean region, particularly insouthern Europe andNorth Africa.
It is native to northwesternAfrica in theAtlas Mountains ofMorocco,Algeria, andTunisia, with two small outlying populations onMalta, and nearCartagena in southeastSpain inEurope. It grows at relatively low altitudes in a hot, drysubtropicalMediterranean climate.[7]The species has reportedly become aninvasive species in the eastern Mediterranean drylands.[8] The genus once had a much broader range during theOligocene–Miocene, with some species occurring inNorth America.[9]
Its closest relatives arePlatycladus,Microbiota, andCalocedrus, with the closest resemblance to the latter. In older texts, it was sometimes treated inThuja orCallitris, but it is less closely related to those genera.[7]
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It is a small, slow-growing tree, to 6–15 m (rarely 20 m) tall and 0.5 m (rarely 1 m) trunk diameter, often with two or more trunks from the base. The foliage forms in open sprays with scale-likeleaves 1–8 mm long and 1–1.5 mm broad; the leaves are arranged in opposite decussate pairs, with the successive pairs closely then distantly spaced, so forming apparent whorls of four. Thecones are 10–15 mm long, green ripening brown in about 8 months from pollination, and have four thick scales arranged in two opposite pairs. Theseeds are 5–7 mm long and 2 mm broad, with a 3–4 mm broad papery wing on each side.[7][10]
It is one of only a small number of conifers able tocoppice (regrow by sprouting from stumps), an adaptation to survivewildfire and moderate levels of browsing by animals. Old trees that have sprouted repeatedly over a long period form large burls at the base, known aslupias.[7]
It is thenational tree ofMalta, where it is known asgħargħar (derived from the Arabicعَرْعَرʿarʿar). It is now being used locally in afforestation projects.[citation needed]
Theresin, known assandarac, is used to makevarnish andlacquer; it is particularly valued for preservingpaintings.
Thewood, known as thuya wood,[11] citron wood,[4] and alerce,[12] and historically also known asthyine wood, is used for decorative woodwork, particularly wood from burls at the base of the trunk. It has been used thus since antiquity (Ancient Greek:θύον,[13][14]Latin:citrus[15]), and was used to make valuable furniture in the time of theRoman Empire.[16] The market in Morocco is unsustainable, focusing as it does on the burl, and has resulted in mass deforestation of the species. The species is also threatened byovergrazing, which can kill the coppice regrowth before it gets tall enough to be out of the reach of livestock.[7]
The species is cultivated to be grown as anornamental tree, valued in hot, dry climates. It is also pruned in ahedge form, for privacy and security.[10] The plant can be trained for use asbonsai specimens.
A relatedextinct species,Tetraclinis salicornioides, has leaf and conefossils ofMessinian age (ca. 5.7 Ma) that have been uncovered in Monte Tondo andBorgo Tossignano, northernApennines,Italy.[17]
