Spartina alterniflora (cordgrass), a halophyte.

See also: biosalinity and halophile

A halophyte is a plant that naturally grows where it is affected by salinity in the root area or by salt spray, such as in saline semi-deserts, mangrove swamps, marshes and sloughs, and seashores. An example of a halophyte is the salt marsh grass Spartina alterniflora (smooth cordgrass). Relatively few plant species are halophytes - perhaps only 2% of all plant species. The large majority of plant species are "glycophytes," and are damaged fairly easily by salinity.^[1] Download high resolution version (900x600, 73 KB)Image of a clump of Spartina alterniflora from http://plants. ... Download high resolution version (900x600, 73 KB)Image of a clump of Spartina alterniflora from http://plants. ... Binomial name Spartina alterniflora Loisel. ... Species See text. ... Biosalinity is the study and practice of using saline (salty) water for irrigating agricultural crops. ... Halophiles are extremophiles that thrive in environments with very high concentrations of salt (at least 2 M, approximately ten times the salt level of ocean water). ... Divisions Green algae Chlorophyta Charophyta Land plants (embryophytes) Non-vascular plants (bryophytes) Marchantiophyta—liverworts Anthocerotophyta—hornworts Bryophyta—mosses Vascular plants (tracheophytes) †Rhyniophyta—rhyniophytes †Zosterophyllophyta—zosterophylls Lycopodiophyta—clubmosses †Trimerophytophyta—trimerophytes Pteridophyta—ferns and horsetails Seed plants (spermatophytes) †Pteridospermatophyta—seed ferns Pinophyta—conifers Cycadophyta—cycads Ginkgophyta—ginkgo Gnetophyta—gnetae Magnoliophyta—flowering plants... Annual mean sea surface salinity for the World Ocean. ... Binomial name Spartina alterniflora Loisel. ...

One quantitative measure of salt tolerance is the "total dissolved solids" in irrigation water that a plant can tolerate. Sea water typically contains 40 grams per liter (g/l) of dissolved salts (mostly sodium chloride). Beans and rice can tolerate about 1-3 g/l, and are considered glycophytes (as are most crop plants). At the other extreme, Salicornia bigalovii (dwarf glasswort) grows well at 70 g/l of dissolved solids, and is a promising halophyte for use as a crop. More than 20 countries are involved in saltwater agriculture projects for food crops. Among the plants known as salwort protein accounts for about 17 per cent of the saltwort seeds' weight, the protein is rich in the amino acids lysine and methionine. A quarter of the seed mass is made of oils that are 93 per cent unsaturated, and thus less likely to cause heart disease This article is on the plant. ... This article needs additional references or sources for verification. ... Species See text. ...

^[2] Plants such as barley (Hordeum vulgare) and the date palm (Phoenix dactylifera) can tolerate about 5 g/l, and can be considered as marginal halophytes.^[1] Binomial name Hordeum vulgare L. Barley (Hordeum vulgare) is a major food and animal feed crop, a member of the grass family Poaceae. ... Binomial name Phoenix dactylifera L. The Date Palm Phoenix dactylifera is a palm, extensively cultivated for its edible fruit. ...

Adaptation to saline environments by halophytes may take the form of salt tolerance (see halotolerance) or salt avoidance. Plants that avoid the effects of high salt even though they live in a saline environment may be referred to as facultative halophytes rather than 'true', or obligatory, halophytes. Halotolerance is the adaptation of living organisms to conditions of high salinity. ...

For example, a short-lived plant species that completes its reproductive life cycle during periods (such as a rainy season) when the salt concentration is low would be avoiding salt rather than tolerating it. Or a plant species may maintain a 'normal' internal salt concentration by excreting excess salts through its leaves or by concentrating salts in leaves that later die and drop off.

External links

• http://www.ussl.ars.usda.gov/pls/caliche/halophyte.preface
• http://makeshiftblog.wordpress.com/2007/07/10/university-of-delaware-researcher-says-seeds-from-salt-tolerant-plant-a-promising-source-of-biodiesel/

References

1. ^ ^{a b} Glenn, E. P., Brown, J. J., and Blumwald, E. (1999). "Salt Tolerance and Crop Potential of Halophytes," Critical Review in Plant Sciences, Vol. 18, No. 2, pp. 227-255. DOI: 10.1080/07352689991309207
2. ^ Glenn, E. P.; Brown, J. J.; O'Leary, J. W. (1998). "Irrigating Crops with Seawater," Scientific American, Vol. 279, no. 8, Aug. 1998, pp. 56-61.