Mangrove ecosystem is a very specialised environment occurring in between the terrestrial habitat and the sea in the
tropical and sub-tropical regions. Sundarban is the largest delta formed by the confluence of the Ganges, Brahmaputra
and Meghna rivers in the Bay of Bengal. Tide- dominated funnel-shaped estuary is intersected by mesh-like network of rivers,
channels and creeks. The transitional habitat supports a unique variety of plant community, known as ‘mangrove’.
The term ‘mangrove’ is derived from a Portuguese word ‘mangue’, which means salt tolerant plants.
The Sundarban is one of the prominent examples of mangrove in the world.
The mangrove formation is observed where the tidal interaction is normal with a constant mixing of sea water and fresh water
and the optimal temperature is 20 degree Celsius. The vegetation can be classified as tidal swamp, salt water type mixed forests,
brackish type and palm type forests.
Features of the flora:
- The mangrove species are typically leathery, possess cuticle on the upper surface of the leaves.
- Cable roots along with stilt roots are seen.
- Oxygen is deficient in the soil and the trees posses pneumatophores to overcome the situation.
- Viviparous germination is the unique feature of these halophytes.
- The leaves of the plants secrete excess salt through special micro-hair like structures throughout the year,
have a complex salt- filtration system.
Sundarban is the home of more than 300 species of plants,among them some are true mangroves, namely:
- Kalo Baine(Avicennia alba)
- Peara Baine (Avicennia marina)
- Jat Baine(Avicennia officinalis)
- Genwa (Excoecaria agallocha)
- Hental (Phoenix paludosa)
- Garjan (Rhizophora apiculata)
- Bhara (Rhizophora mucronate)
- Sundari (Heritiera fomes)
- Tora (Aegialitis rotundifolia)
- Khalsi (Aegiceras corniculatum)
- Hargoja (Acanthus ilicifolius)
- Kankra(Bruguiera gymnorrhiza)
- Bakul Kankra(Bruguiera parviflora)
- Jat Garan (Ceriops tagal)
- Jhamti/Jele Garan (Ceriops decundra),
- Chak Keora(Sonneratia caseolaris)
- Karanja (Pongamia pinnata)
- Habli (Thespesia popul)
- Manda (Viscumori entale)
- Baro Manda (Dendrophthoe falcate)
- Kripa (Lumnitzera racemose)
- GolPata (Nypa fruiticans)
- Son Champa (Bruguiera cylindrical)
- Pashur (Xylocarpus mekongensis)
- Tak Keora(Sonneratia apetala)
- Hoya (Hoya parasitica)
- Goria (Kandelia candel)
- Kalak Kambing (Finlaysonia obovata)
Besides these, a native pioneer species called Dhani Ghas (Porteresia coarctata) grows in saline estuarine ecosystem.
Important to note that, the salinity gradient makes the stratification of trees in the ecotone environment.