Halophyte

Halophytes can be classified in many ways. According to Stocker (1933), it is mainly of 3 kinds by habitat, viz. • Aqua-halines (aquatic plants) • Emerged Halophytes (most of the stem remains above the water level) • Hydro-halophytes (whole or almost whole plant remains under water) • Terrestro-halines (terrestrial plants) • Hygro-halophytes (grow on swamp lands) • Mesohalophytes (grow on non-swamp, non-dry lands) • Xero-halophytes (grow on dry or mostly dry lands) • Aero-halines (epiphytes and aerophytes) Again, according to Iversen (1936), these plants are classified with respect to the salinity of the soil on which they grow. • Oligo-halophytes (amount of NaCl in the soil is 0.01 to 0.1%) • Meso-halophytes (amount of NaCl in the soil is 0.1 to 1%) • Euhalophytes (amount of NaCl in the soil is >1%) For comparison, seawater has a salinity of about 3.5%. See water salinity for other reference levels. == Habitats of halophytes ==

Major habitats where halophytes flourish include mangrove swamps, sand and cliff shorelines in the tropics, salt deserts and semi-deserts, the Sargasso Sea, mudflats and salt marshes, kelp forests and beds, salt lakes and salt steppes of the Pannonian region, wash fringes, isolated inland saline grasslands, and in places where people have brought about salination. == Salt tolerance ==

True halophytes do not just tolerate saline water, but show optimal growth in saline water. One quantitative measure of salt tolerance (halotolerance) is the total dissolved solids in irrigation water that a plant can tolerate. Seawater typically contains 40 grams per litre (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 bigelovii (dwarf glasswort) grows well at 70 g/L of dissolved solids, and is a promising halophyte for use as a crop. 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. ==Examples==

Some halophytes are: == Uses ==

Biofuel Some halophytes are being studied for use as "3rd-generation" biofuel precursors. Halophytes such as Salicornia bigelovii can be grown in harsh environments and typically do not compete with food crops for resources, making them promising sources of biodiesel or bioalcohol. Phytoremediation Halophytes like Suaeda salsa can store salt ions and rare-earth elements absorbed from soils in their tissues. Halophytes can therefore be used in Phytoremediation measures to adjust salinity levels of surrounding soils. These measures aim to allow glycophytes to survive in previously uninhabitable areas through an environmentally safe, and cost effective process. A higher concentration of halophyte plants in one area leads to higher salt uptake and lower soil salinity levels. Different species of halophytes have different absorption capabilities. Three different halophyte species (Atriplex patula, Atriplex hortensis, and Atriplex canescans) have been found to rehabilitate soils contaminated with road salt over varying lengths of time. == See also ==