There are special type of Halophytic plants which grow on soils with high concentration of salts. Examples: Rhizophora, Sonneratia and Avicennia.
Halophytes are usually found near the seashores and Estuaries. The soils are physically wet but physiologically dry. As plants cannot use salt water directly they require filtration of salt using physiological processes. This vegetation is also known as mangrove forest and the plants are called mangroves.
• The temperate halophytes are herbaceous but the tropical halophytes are mostly bushy
• In addition to the normal roots, many stilt roots are developed
• A special type of negatively geotropic roots called pneumatophores with pneumathodes to get sufficient aeration are also present. They are called breathing roots. Example: Avicennia
• Presence of thick cuticle on the aerial parts of the plant body
• Leaves are thick, entire, succulent and glossy. Some species are aphyllous (without leaves).
• Viviparous mode of seed germination is found in halophytes
• Epidermal cells of stem is heavy cutinized, almost squarish and are filled with oil and tannins.
• ‘Star’ shaped sclereids and ‘H’ shaped heavy thickened spicules that provide mechanical strength to cortex are present in the stem.
• The leaves may be dorsiventral or isobilateral with salt secreting glands. Physiological adaptations
• High osmotic pressure exists in some plants .
• Seeds germinate in the fruits while on the mother plant (Vivipary).