Included here is the area around Bengal including the lowlands of the lower courses of the Ganges and Brahmaputra, the lowlands of Orissa north of the Mahanadi River together with the tropical parts of Assam, Manipur, Nagaland and Tripura. A major part of this zone is the Bengal Delta, one of the largest in the World.

Bengalian Coastal Sand Dunes

The dune complex along the Digha shore (Midnapore District) can extent inland for up to 8 km. These can be broadly classified into foredunes and backdunes.

Some of the mobile dunes in this region are huge and characteristically have gentle seaward slopes while the leeward slopes are steeper and comparable to the barchan dunes of the inland arid zones. They are mostly calcareous with a strong alkaline reaction. In the partially consolidated areas the vegetation comprises Ipomea pes-caprae, Launaea sarmentosa, Dactyloctenium aegypticum and Cyperus arenaria in order of relative abundance. Further inland the on tops of sand dunes species such as Borreria articularis, Brachiaria reptans, Narenga porphyrocoma, Rothia indica, Synostemon bacciforme and Trianthema pentandra make up the main vegetation type.

In general these form undulating slopes with conical, flat toped and parabolic dunes up to 15 m high with slacks in the inter-dune areas. The tops of dunes are either dominated by Borreria sporobolus or codominated by Cyperus arenarius and Sida cordifolia. Other species include Hybanthus enneaspermus, Polycarpaea corymbosa and Veronica cinera. Where the dune tops have undergone further stabilization a shrubby association including Bulbostylis barbata, Glycosmis arborea and Tephrosia purpurea occurs. The mid-slopes are predominantly colonised with Carissa spinarum and Sporobolus virginicus. However, on stabilised dunes with moderate slopes other species occur with Tephrosia purpurea often associated with Borreria articularis, Bulbostylis barbata, Cyperus arenarius, Evolvolus alsinoides, Polycarpaea corymbose, Polygala erioptera, Sida cordifolia, Zornia gibbosa and the weedy, invasive Croton bonplandianum.

Slacks or Swales
These are largely colonised by a Paspalum scorbiculatum community. Associated species include Bulbostylis barbata, Cyperus ciliaris, Marselia quadrifida and Nymphaea nouchalii. In the wetter slacks other species such as Ipomoea aquatica, Nymphoides indicum, Pista stratiotes and Scacciolepis interupta appear, while at the dryer end of the spectrum Brachiaria reptans tends to dominate together with Drocera burmanni and other species.


Rao, T. A., Shanware, P. G. & Mukherjee, A. K. 1974. Ecological studies on the coastal sand dunes and slacks in the vicinity of Digha, Midnapore District, West Bengal.  Indian Forester, 100: 101-107.