Characteristics of Mangrove Plants

      Stabilization of mud-flats is a preliminary process in the establishment of mangroves. Pioneer plant species like Porterasia coarctata and Cyprus spp. initiate this process. The roots of these plants help in binding the soil and also help the establishment of micro-organisms which further help in stabilizing the area. Stabilization starts from the land side and gradually shifts towards the sea. These pioneer plants are slowly replaced by other mangrove plants and then mangroves gradually spread towards the sea. Once mangroves grow, the submerged banks are fully stabilized; after this, mangroves slowly reach climax vegetation stage. Climax vegetation is represented by the complete circle of life where there are different species of plants, animals (both terrestrial and aquatic) and micro-organisms forming an ecosystem called the tropical salt marsh or the mangrove ecosystem. In case the sediments are not stabilized, submerged banks are washed out. Like in Gangetic delta, thousands of deltas are formed and washed out every year before they can be stabilized.

(a)Specialized Root System in Mangroves-

Knee Roots

Buttresses

       The major plant species forming the mangrove ecosystem have aerial roots, commonly prop roots or even stilt roots. Stilt roots serve to anchor the plants, but also are important in aeration, because the mangrove mud tends to be anaerobic. Rhizophora spp. (Red mangroves) have prop roots descending from the trunk and branches, providing a stable support system. Other species, including the white mangroves (A. marina) obtain stability with an extensive system of shallow, underground ”cable roots” that radiate out from the central trunk for a considerable distance in all directions: pneumatophores extend from these cable roots.

Breathing Roots (Pneumatophores)-  Special vertical roots, called pneumatophores, form from lateral roots in the mud, often projecting above soil permitting some oxygen to reach the oxygen-starved submerged roots.

Stilt roots- are the main organs for breathing especially during the high tide. They are very common in many species of Rhizophora and Avicennia. Aeration occurs also through lenticels in the bark of mangrove species.

(b) Reproductive Strategies of Mangroves: - Virtually all mangroves share two common reproductive strategies: dispersal by means of water and vivipary. Vivipary means that the embryo develops continuously while attached to the parent tree. They may grow in place, attached to the parent tree for one to three years, reaching length upto one meter, before breaking off from the parent plant & falling into the water, these seedling then lodged in the mud where they quickly produce additional roots and begin to grow.

(c) Coping with salt- The first line of defense for many mangroves is to prevent much of the salt from entering by filtering it out at root level, The leaves of many mangroves have special salt glands. another method is the retention of water in the leaves giving rise to leaf succulence in many species. Fourth method of coping with salt is to concentrate it in bark or in older leaves which carry it with them when they drop.

Back