Salt Tolerance (eHALOPH)

There are over 1500 naturally occurring salt-tolerant plants; trees (including mangroves), shrubs, grasses and herbs. These are collectively known as halophytes. A halophyte is a plant that completes its life cycle in a salty environment; many survive in seawater or even higher concentrations of salt. Most other plants (called glycophytes) cannot survive even one tenth the salt concentration found in seawater; this group includes virtually all our crop plants. Given the extent of salt-affected land, perhaps 6% of the world’s land surface and a continual increase in the extent of salinised agricultural land, information about halophytes provides a basis for the restoration of this land, the adaptation of agriculture and agro-forestry systems to salinity and the better understanding of the physiology and evolutionary ecology of salt tolerance among plants.

The most comprehensive list of halophytes was compiled by James Aronson during the 1980s: his 'HALOPH A Data Base of Salt Tolerant Plants of the World' was published in 1984 by the Office of Arid Land Studies at the University of Arizona, Tucson, Arizona. This database is now incorporated into SID. It contains a list of 1554 species for which there is evidence that they are salt tolerant; the maximum salinity tolerated by the plant is included (where available this is expressed as an electrical conductivity of a solution in which the plants were growing), together with its photosynthetic pathway where known. Also included in the data is a description of the life form, the plant type and distribution, as well as bibliographic references up to 1989.

The salt tolerance (eHALOPH) module in SID was compiled, with permission, by Tim and Sam Flowers with funding provided by the University of Sussex. The source of the data was ‘HALOPH A Data Base of Salt Tolerant Plants of the World’ by James Aronson (CNRS, France), which was published in 1989 in Tucson, Arizona by the Office of Arid Land Studies at the University of Arizona.

Max/ dS/m

Numerical value This is the maximum reported salinity tolerated by a species and reported as the conductivity (in dS/m) of the soil (a saturation extract) or solution in which the species was grown.
SW is an abbreviation for ‘SeaWater’ – whose conductivity is at least 40 dS/m.
?? means there was doubt (in the mind of James Aronson) that the species met the criterion.

Readers are recommended to consult the original literature before drawing final conclusions about the salt tolerance of a species.

Photosynthetic pathway

C3 the primary products of carbon dioxide fixation are 3-C compounds
C4 the primary products of carbon dioxide fixation are 4-C compounds
? if one or more species within a genus has known PHOPATH, any additional species in that genus included were labelled with that same PHOPATH followed by a "?", except in the case of genera, (e.g., Atriplex and Suaeda) known to have species with more than one PHOPATH


Timothy J Flowers1, Sylvia A Flowers1, James Aronson2, and Sarah Flynn3

1Department of Biology and Environmental Science,
John Maynard Smith Building,
School of Life Sciences,
University of Sussex,
Falmer, Brighton, BN1 9QG,

2Restoration Ecology Group,
1919 Route de Mende,
34293 Montpellier,
cedex 5,

3Seed Conservation Department,
Royal Botanic Gardens, Kew,
Wakehurst Place,
Ardingly, Haywards Heath,
West Sussex, RH17 6TN,

University of Sussex