Halophytes are plants adapted to living in a saline environment such as seashores, saltwater marshes and sloughs, mangrove swamps and saline deserts. Among halophytes there is a wide range of salt tolerance and several means of classification. Only about 2% of the earth’s plant species are halophytes.
Plants adapt to survival in saline environments through a combination of morphological and physiological means. Large cells with small intercellular spaces, high cell wall elasticity, salt glands and bladders, leaves covered with trichomes (fine outgrowths), smaller relative surface area , extensive development of water storing tissues and low chlorophyll content are a few of the morphological adaptations of halophylic plants. Physiologically, halophyles may exhibit succulence, C4 photosynthetic pathways, compartmentalization of ions in vacuoles and control of ion uptake by roots among other adaptations.
In my previous post I mentioned the alkali chemical crusts that form in desert or semi-desert environments (Chemical Soil Crusts 01-18-22). At Ash Creek Wildlife Area there is a alkali crust east of the Wayman Barn (Lassen County CA). Two halophytes predominate: alkalai saltgrass (Distichlis spicata and greasewood (Sarcobatus vermiculatus).
One adaptation to a high concentration of salinity in greasewood is succulence. As salt ions concentrate in greasewood leaves, more water is transported to the leaves. This dilutes the salt ions and increases the turgidity of the leaves while maintaining osmotic potential.
Alkali saltgrass has salt glands on the surface of its leaves. Excess salts in the leaves are collected in and excreted through these salt glands, which consist of a basal cell and a cap cell. The salt gland is a reservoir from which the excess salts are excreted onto the surface of the leaf. In the photograph, salt crystals are visible on the leaves.
I always am amazed at how organisms can adapt to even the most extreme environments.