Ecological Adaptations - Halophytes

The plants, which grow in saline habitats, are called Halophytes. There is high concentration of salts like sodium chloride, MgSO₄ etc. in these habitats. As the habitat is physiologically dry due to salts, the halophytes show characters similar to Xerophytes.

In tropical and subtropical regions, the sea-shore has dense tress of halophytes forming mangrove forests. The common trees found are Avicennia, Rhizophora. Mangroove trees are characterized by the presence of negatively geotropic breathing roots called Pneumatophores which help in respiration, as these plants live in salty marshes and do not get sufficient oxygen from the soil.

Like Xerophytes, halophytes also possess

• Succulent leaves and stem

• Thick walled and heavily cutinized epidermis

• Hairy covering and mucilage cells.

Adaptations

• The leaves are reduced to small scaly structures (Casuarinas) or spines (Opuntia)

• The leaves are shed when water is scarce

• Water storage structures develop in the leaves

• They have a thick cuticle and a multiple layered epidermis

• They have sunken stomata

• They have long roots, which go in search of water

• The stem becomes green and takes over the function of photosynthesis where the leaves are absent/reduced/shed.

Adaptations to oligotrophic soils

These soils contain low amount of nutrients. Due to weathering and high rates of leaching, these soils have poor nutrients.

Many plants growing is such nutrient poor soils, possess mycorrhizae, which is an association of roots with fungi. Mycorrhizae help in absorption of nutrients they can be either endo mycorrhizae or ectomycorrhizae. In endo mycorrhizae the fungus lives inside roots. In ectomycorrhizae the fungal hyphase are found outside the root.