Tetraclinis articulata

(Vahl) Masters 1892

Common names

Arartree, alerce (Britannica Online), sandarac gum tree, gharghar [Maltese], thuya d'Algérie, thuya de Barbarie, bois de titre (Farjon 2005), Barbary arbor-vitae, alerce; Mediterranean alerce; citron-wood tree; and African juniper (Stevens 2000).

Taxonomic notes

The sole species in Tetraclinis Masters 1892. Syn: Thuja articulata Vahl 1791; Callitris quadrivalvis Rich. et A. Rich. 1826; Cupressus articulata (Vahl) Forbes 1839; Callitris articulata (Vahl) Murb. 1900. Type: N Tunisia: Hammam-el-Lif (Farjon 2005).

Description

A shrub, or small tree to 6-8(-15) m tall (Farjon 2005).

Distribution and Ecology

S Spain, Morocco, N Algeria, N Tunisia, Malta, perhaps Libya; in Malta and Spain only tiny relict populations remain, and have also been reported (but not collected) from Jabal al Akhdar in NE Libya (Farjon 2005).

Although the species as a whole is "lower risk, not threatened," the Maltese and Spanish populations are listed as highly threatened by the IUCN.

Zone 10 (cold hardiness limit between -1°C and +4.4°C) (Bannister and Neuner 2001).

Big tree

The only measurement I have seen reported is 18.6 m tall and 40 cm dbh (61 feet tall by 49 inches girth) for a tree at the Arboretum of the University of California, Davis (Arthur L. Jacobson e-mail 2007.08.24).

Oldest

Dendrochronology

Ethnobotany

The species is occasionally used as an ornamental, sometimes as a bonsai, sometimes as an outdoor trees where it does well in hot, dry climates and makes an acceptable hedge (Rushforth 1999). The resin is called sandarac and has (had?) various industrial uses, including being used instead of Canada balsam in the preparation of microscope slides (Stevens 2000). The wood, called citron wood in trade, is prized for cabinetry and was extensively used in construction by the Romans (Stevens 2000). The burl wood, commonly called citron burl or thyine burl (from the Greek, thyinos), has long been used to make decorative objects; for examples, Google 'citron burl'. The burls are a somewhat peculiar resource; they grow beneath the ground, and due to their high resin content they are often recovered as subfossil wood in areas where the living trees have long been extirpated. In this respect they constitute a resource comparable to subfossil Agathis australis.

Observations

There is a readily accessible stand of healthy trees in the foothills of the High Atlas just south of Asni (south of Marrakech) in Morocco. The stand breaks up into smaller dispersed patches as one continues the Oued n'Fiss valley toward the Tizi n'Test Pass, a route that also passes through some fine stands of Cupressus atlantica (Nick Macer email 2007.11.07).

In the Ida Outanane, a far western outlier of the High Atlas range, Tetraclinis grows with the very local endemic Olea europaea subsp. maroccana, the Moroccan wild olive, at lower altitude and also right up into the mountains where very healthy regeneration can be seen (Nick Macer email 2007.11.07).

Remarks

This is the national tree of Malta, where its wild occurrence is restricted to about 100 trees in the northern part of the island of Malta (Stevens 2000).

This is also one of the few conifers mentioned in the Bible; Revelation 18:12 refers to "cargoes of .. every sort of citron wood."

Citations

Rushforth, K. 1999. Trees of Britain and Europe. London: Collins.

Stevens, D. 2000. The Maltese national tree - the araar tree. http://www.geocities.com/rainforest/andes/2113/arartree.html?200712, accessed 2007.11.12.

See also

Farjon (2005) provides a detailed account, with illustrations.

Houerou, H.N. 1969. Le végétation de la Tunisie steppique. Annales de l'Institut National de la Recherche Agronomique de Tunisie 42(5): 620.

Ibanez, J.M. et al. 1989. Data on a population of Tetraclinis articulata (Vahl) Masters. Ecologia 3: 99-106.