How do plants cope with salinity?

Plants of salt marshes and other saline habitats grow in a physiologically dry environment.

Known as halophytes, they take in water that contains high levels of solutes.

They accumulate high levels of ions within their cells, especially in the leaves.

Taking up water heavy in sodium and chloride, some halophytes dilute it with water they have stored in their tissues.

Some plants have salt-secreting glands that deposit excess salt on the leaves to be washed away by rain.

Others remove salts mechanically at the root membranes.

Plants of saline deserts encounter worse problems.

Not only do they grow in salty soil; they must also endure dry conditions.

A number of desert plants allow only certain ions to pass across root membranes and keep others out.

That selectivity allows these plants to absorb essential nutrients from the soil and maintain osmotic pressure.

Some plants, such as salt marsh hay grass (Spartina patens), grow best at low salinities.

Halophytes, however, vary in their degree of tolerance to salt.

Salt marsh cordgrass (S. alternifolia), do best at moderate levels of salinity.

◦A few, such as the glasswort (salicornia spp.), tolerate high salinities.

◦They are able to exist only in saline environments.

◦It is edible and sometimes referred to as “marsh asparagus.”