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Atriplex halimus L. (Amaranthaceae) (Mediterranean saltbush) is a halophytic shrub that is widely distributed in arid and semi-arid regions around the Mediterranean basin and east to Saudi Arabia, at elevations less than 900 m. It grows on a variety of soils, from fine to coarse texture, with varying degrees of salinity. There are two sub-species of A. halimus: halimus is diploid (2n = 2x = 18) and is found at semi-arid, less-saline sites, while schweinfurthii is tetraploid (2n = 4x = 36) and occupies arid, saline sites. Throughout its distribution, A. halimus is exposed to high light intensity and temperature and varying degrees of drought and salinity; it can also withstand sub-zero winter temperatures or soil contamination by trace elements. Some of its physiological and biochemical tolerance mechanisms - such as adjustment of plant water relations are common to all or several of these environmental stresses, but others are specific to particular stresses. The importance of A. halimus in the functioning of ecosystems is reflected in its promotion of soil biota, while it also acts as a food plant for mammals and arthropods. Its deep root system decreases soil erosion in arid zones, due to stabilisation of the soil. The protein-rich shoot material of A. halimus makes it an important fodder species for livestock, particularly sheep and goats. However, its low energy value means that it should be supplemented with carbohydrate-rich material, such as cereal straw. Potential new uses of this versatile plant species include the phyto-remediation of soils contaminated by trace elements and the exploitation of its biomass as a source of renewable energy. Such applications, together with its continued use in low-intensity farming systems, should ensure that A. halimus remains a vital plant species in low-rainfall regions. (C) 2013 Elsevier Ltd. All rights reserved.