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ADAPTATIONS OF MANGROVE PLANTS
Mangrove plants live in areas of intense light and high temperatures on unconsolidated soils, anaerobic and periodically flooded with saline water. Their saline water is physiologically dry. High salt contents of the surrounding environment tend to dry out their tissues. The adaptations of mangrove plants are normally the characteristics of xerophytes. They have succulent leaves, thickened epidermis and waxy cuticle. They tend to have reduced leaf areas, sunken stomata, smaller cells and high internal pressures.
Mangroves can tolerate greater salt concentrations in the sap, but some species, viz.: Avicennia, Aegialites and Aegiceras are salt escreters (=actually concentrating and removing salt through the leaves). Salt excluders (e.g. Rhizophora, Sonneratia and Lumnitzera) allow less salt to enter and concentrate what it gets by retaining in the leaves.
The roots of mangrove plants are for anchorage then for obtaining water and oxygen in largely anaerobic surroundings by its prop roots or pneumatophores. The function of these specialized roots is to bring the nutritive roots and keep the lenticels leading to the aerenchyma tissue in contact with the air supply. The most intriguing adaptation of mangrove trees is their root system that creates an almost impenetrable maze, allowing them to resist current scour and erosion and become established on very fluid muds and unstable substratum.