The following points highlight the eight main Phytogeography regions of India. The regions are: 1. Flora of Deccan 2. Flora of Malabar 3. Flora of Indus Plain 4. Flora of Gangetic Plain 5. Flora of Assam 6. Flora of Eastern Himalayas 7. Flora of Central Himalayas 8. Flora of Western Himalaya.
Phytogeography Region # 1. Flora of Deccan:
Deccan includes entire peninsula South of Ganges and east of Malabar. The important trees are Michelia champaca, Dillenia aurea, Chloroxylon swetenia, Cedrela toona, Santalum album, Pterocarpus sentalinus, Soyamida, and tree ferns etc.
Shrubs are mainly Zizyphus, Grewia, Bauhinia, Woodfordia, Capparis, Lagerstroemia, Holarrhena; Climbers like Hiptage, Cassytlea, Dioscorea, Ipomoea, Vitis, Smilax etc. Euphorbia nerrifolia and E. tortilis etc., are common in dry areas whereas herbs are commonly belonging to Lamiaceae, Amaranthaceae, Acanthaceae, Commelinaceae and Orchidacee etc. Bambusa arundinacea, Dendrocalamus, Borassus flabellifer, Phoenix sp. etc. represent family of Arecaceae and Poaceae.
Deccan is characterized by presence of “black cotton soil”. Common planes of this soil are Hibiscus, Cassia auriculata, Acacia arabica, Parkinsonia aculeata, Calotropis procera, Zizyphus numularia, Jatropha grandiflora etc.
The vegetation of Coromandal subregion is same in Deccan except some estuarial and mangrove plants such as Brugiera, Ceriops, Avicinnia etc. Other plants are Mimusops, Garciia, Chloroxylon swietenia, Strychnos nux-vomica etc.
Phytogeography Region # 2. Flora of Malabar:
Area of Malabar includes Kerala, Maharashtra, Gujarat and Karnataka. Hill areas of western ghats are also included in this zone.
Generally, the plants are distributed into:
(a) Temperate evergreen forests,
(b) Subtropical evergreen forests,
(c) Tropical evergreen forests,
(d) Tropical semi-evergreen forests,
(e) Tropical deciduous forests, and
(f) Mangrove forests.
(a) Temperate evergreen forests:
The area includes Nilgri hills, Palni, Annamalai and Tirunevelly hills etc. The vegetation shows red tinged leaves of the trees, e.g., Meliosma wightii, Michelia nilgirica, Rhododendron nilgiricum, Toddalia, Clematis, Impatiens, Arisema, Cymbopogon etc.
(b) Subtropical evergreen forests:
The dominant vegetation of this area is Memecylon, Syzygiun, Etnblica officinalis, Murraya koenigii, Rhododendron nilgiricum, Smilax, Piper, Clematis etc.
(c) Tropical evergreen forests:
The area of includes Mysore plateau, western side of Western Ghats, Coorg and Annamalai Hills etc. Evergreen dense vegetation dominates by the presence of Dillenia pentogyna, Terminalia balerica, Artocarpus peltata, Cinnamomum zeylenicum, Areca, Calamus, Croton, Ixora etc.
(d) Tropical semi evergreen forests:
Plateau of Western Ghats is the main centre with the presence of Dipterocarpus, Lagerstroemia, Xylia, Rauwolfia serpentina, and Terminalia etc.
(e) Tropical deciduous forests:
Wet and Dry types of vegetation are found. Wet type is common in Cochin, west coast of Karnataka and Travencore etc., where rainfall is more. Dominant vegetation is of Tectona grandis, Grewia tiliaefolia, Butea monosperma, Dalbergia latifolia, Mitragyna parviflora, Bombax malabaricum (B. ceiba), Adina cordifolia, Xylia xylocarpa, Anogeissus latifolia, Santalum album, Erythrina variegata, Lantana, Clerodendron, Woodfordia, Kydia calycina, Bambusa arundinacea, Terminalia tomntosa, Gardinia latifolia etc.
(f) Mangrove forest:
The vegetation is found in Elora, Elephanta, Bombay suburbs, Mudh Island, Arabian sea shore etc. the major plants are of Rhizophora, Bruguiera parviflora, Ceriops tagal, Kandelia candel, Xylocarpus grantum Acanthus illicifolius, Sonneratia etc.
Phytogeography Region # 3. Flora of Indus Plain:
The area comprises of Gujarat, Delhi, Rajasthan, Haryana and Punjab. It is the dry region from plains to Mt. Abu; deserts and irrigated lands. Rainfall is very low in extremely dry areas. Indus plain can be divided into 3 types of vegetation as tropical dry deciduous, tropical thorny and dry shrubs.
On the basis of topography the area is divided into 3 areas and the vegetation of the region is as follows:
(a) Aravallies:
Anogeissus pendula, Butea, Acacia catechu, Bombax, Zizyphus, Grewia salvifolia, Maytenus (syn. Gymnosporia), Balanites roxburghii, Boswelia serrata, Nyctanthes, Carissa, Euphorbia nivulia, Mangifera indica etc. are prominent. Bamboos are absent
(b) Irrigated or Riverine Lowlands:
It is dominated by Dalbergia sisso, Populus, Butea, Mangifera, Anthocephalus, Amoora, Bombax, Acacia, Melia azadarach, Azadirachta indica, Polyalthia longifolia, Albizia lebbeck, Eucalyptus, Cordia, Lagerstroemia, Ficus religiosa, F. benghalensis, F. infectoria and sp. of Ficus etc.
(c) Kutch:
Generally the vegetation is of thorny plants e.g., Acacia nelotica, A. Senegal, Salvadora, Cassia, Tinospora, Tamarix, Tragia, Rivea, Vitis, Apluda, Cymbopogon, Eragrostis, Paspalidium, Cenchrus, Peristrophe, Grewia populnifolia, Commiphora wightii etc.
(d) Arid Sandy zone:
It includes sandy areas of Rajasthan and Punjab mainly. The land is not irrigated. The plants of this zone mainly are xerophytes e.g., Argemone, Tephrosia, Acacia leucophloea, Prosopis, Salvadora, Butea, Opuntia, Agave, Calotropis, Tamarix, Sueda, Salsola, Solanun surattense, Tribulus, Capparis, Boerhaavia, Echinops etc.
(e) Desert zone:
It is the long track of Rajasthan and other adjoining areas. Mainly sand, gravel and Rock communities are found in this zone e.g., Calotropis procera, Calligonum, Capparis, Citrullus, Aerua, Indigofera, Zizyphus, Farsetia, Salvadora, Tecomella, Maytenus, Tribullus terrestris, Fagonia, Boerhaavia diffusa, Eleusine aristata, Aristida mutabilis, Poinciana, Ficus religiosa, Melia azadirachta, Convolvulus, Lepidagathis, Achyranthes, Salsola, Pupalia, Lindenbergia, etc.
Phytogeography Region # 4. Flora of Gangetic Plain:
The area extends from east Delhi to Sundarbans of Bengal passing through Bihar, Orissa and U.P. It includes dry deciduous (Scrub) and Moist deciduous vegetation. Sometimes the Indus region and Gangetic region, because of similar type of vegetation, is called as Indo Gangetic plain. The Gangetic plain divided into upper Gangetic plain, Lower Gangetic plain and Sundarbans.
(a) Upper Gangetic plain:
The vegetation is dominated by Acacia nilotica, Balanites, Jatropha, Flacourtia, Capparis decidua, Butea monosperma, Madhuca, Zizyphus, Dalbergia, Phoenix, Nyctanthes, Woodfordia, Adhatoda, Terminalia, Prosopis, Tinospora, Vitis, Cocculus, Ixora, Carissa, Hemidesmus and many types of grass.
(b) Lower Gangetic plain:
The vegetation is dominated by Shorea robusta, Artocarpus, Lagerstroemia, Ptersopermum, Bombax, Ehertia, Adhatoda, Murraya koenigii, Pogosternon, Aegle marmelos, Holoptelea, Areca, Borassus, Pagostemon etc.
(c) Sunderbans:
The largest mangrove forest of the world is of sunderbans covering and area of over 15,000 sq. km. The area has sea creepers and swampy islands. The main vegetation includes Typha elephantine (elephant grass), Pharagmites karka (reed), Pandanus, Alpina, Ipomoea biloba, Bruguiera con ugata, Kandelia. candel, Heritiera, Ceriops, Aviecnnia officinalis, Aegiceras, Sonneratia, Nipa fruiticons, Pheonix paludosa, Cocos nucifera, Rhizophora mucronata, Acanthus illicifolius, Panicum repens, Sueda maritima, Salicornia, Allophylus, Tamarix, Hygrophila, Derris etc.
Phytogeography Region # 5. Flora of Assam:
The area includes Valleys of Brahmputra, Jaintia, Khasi and Garo hills, Mishmi hills, North Himalayas, Santosh River, Naga, Cachar and Mizo hills, Mizoram, Meghalaya, Nagaland, Manipur, Tripura and Assam region. Good rainfall, dense vegetation is characteristic of this area. The vegetation is richest in the world except Khasi hills region. The vegetation is divided into many types e.g.,
(a) Tropical forest:
It is the low foot hill, valley and plains zone.
This may be:
(i) Evergreen:
Vegetation includes Dipterocarpus, Artocarpus, Ficus, Mesua, Amoora, Ficus elastica, Persea, Calamus, Talauma, Cinnamomum, Sterculia, Adina, Vernonina, Mimusops hexandra, Diospyros ebenum, Ixora parviflora, Carissa carnadas, Asparagus, Derris, Acacia intsia etc.
(ii) Deciduous forests:
It is dominated by Tectona grandis and Shorea robusta. The other plants are Kydia, Terminalia, Dipterocorpus etc.
(b) Wet temperate forests:
The main vegetation consists of bamboos and shrubs. The trees are taller in height e.g., Rhododendron, Alnus, Betula, Michelia, Magnolia, Quercus, Carpinus, Acer, Prunus, Pyrus and Bucklandia (Symingtonia) etc.
(c) Pine forest:
The area is 1200-2000 metre above the hill. Majority of plants are of Pinus. Other plants of the vegetation are Acer, Myrica, Camellia, Lithocarpus, Quercus griffithii, Rhus, Prunus, Rubus, Bambusa, Viburnum, Arundinaria etc.
(d) Riverine forests:
Vegetation is found along the banks of rivers and streams. Vegetation is evergreen and deciduous. Mainly the plants found in this region are Pterospermum, Mesua, Salix, Amoora, Anthocephalus, Albizzia procera, Acacia catechu, Dalbergia sisso, Terminalia, Bombax, Sterculia etc.
(e) Swamp forests:
Swampy aras are common in Assam. The important plants of this region are Cephalanthus, Glochidion, Ficus heterophylla, Dracaena, Marsilea, Scirpus, Cyperus, Panicum, Azolla, Salvinia, Euryale, Nymphaea, Nelumbo, Barringtonia, Alpina, etc.
(f) Grass lands:
Grasslands are generally found in plains in Assam. The plants of this region are mainly Paspalidium, Phragmites, Arundo, Panicum, Erianthus, Apluda, Sorghum, Themeda, Saccharum, Andropogon, Cymbopogon etc.
Phytogeography Region # 6. Flora of Eastern Himalayas:
Eastern Himalayas comprises of mountain ranges from Sikkim to Arunachal. It is botanically best known part of this region. More than 4,000 sp. of phanerogams belonging to 160 families and lower plants are found in this region. The Eastern Himalayas are chiefly distributed into 3 regions i.e., Tropical, Temperate and Alpine zone.
(a) Tropical zone:
Rainfall in this zone is heavy and for longer period, the forest in this region are sal forests, mixed deciduous forests, semi-evergreen, evergreen and subtropical forests. Savannah is the grass land which includes trees like Albizzia, Bombax, Bischofia, and grasses like Erianthus, Cymbopogon, Microstegia etc.
The main vegetaion in forest regions includes Quercus, Cycas, Pinus, Populus, Salix, Pandanus, Dillenia, Sterculia, Toona ciliata, Lagerstroemia, Bombax, Shorea robusta, Amoora, Terminalia, Bauhinia, Michelia, Artocarpus, Syzygium, Cinnamomum, Alnus, Rhus and others like Entada, Beaumontia grandiflora, Hiptage, Tinospora cordifolia, Bambusa etc.
(b) Temperate zone:
The zone ranges from 2,000 to 3,540 meter. The region includes broad leaved forests and coniferous forests. The vegetation comprises of mainly Quercus, Magnolia, Pyrus, Abies, Larix, Picea, Tsuga, Juniperus, Taxas, Betula, Acer, Arundinaria, Lyonia, Syringa, Sorbus, Ilex, Fraxinus, Camellia kissi (wild tea) etc.
(c) Alpine zone:
This zone ranges from 3,690 to 5,540 meter. The prominent members belong to Primulaceae and Scrophulariaceae. Vegetation consists of chiefly Artemisia, Potentilla, Carex, Astragalus, Juncus, Rheum, Ephedra, Berberis, Abies, Rhododendron, Primula, Salix, Pedicularis, Meconopsis, Corydalis, Polygounm, Lonicera, Caranga and Saussurea etc.
Phytogeography Region # 7. Flora of Central Himalayas:
Central Himalaya is restricted to Nepal. They are joined to Kumaon Himalaya in west and Sikkim Himalaya in east. The region is divided into western, central and eastern Nepal. The Vegetation consists of chiefly Shorea robusta, Bombax, Gmelina, Petalidium, Clerodendron, Bauhinia vahlii, Ehertia, Rhus, Olea, Quercus, Alnus, Rhododendron, Pinus, Eriobortya, Lindera, Berberis, Tsuga, Abies, Juniperus, Lonicera, Primula, Caranga, Pennisatum, Artemesia, Lyonia, Spiraea, Cornus, Zanthoxylum in western Nepal; Bauhinia, Kydia, Spathodea, Albizzia, Shorea robusta, Trema, Bombax, Saccharum arundinaceum, Cymbopogon martini, Quercus, Acer, Alnus, Mesua, Cyathea, Rhododendron, Camellia, Fraxinus, Pinus, Taxus, Syringa, Barberis, Polygonum, Pedicularia and Mecenopsis etc., in central Nepal and Shorea, Lagerstroemia, Cassia, Sterculia, Flacourtia, Dendracalamus, Smilax, Beaumontia, Euphorbia, Woodfordia, Schima, Quercus, Prunus, Boehmeria, Camellia, Arundinaria, Betula, Eragrostis, Sedum, Saxifrega, Carex, Agrostis, Potentilla, Sedum etc., in Eastern Nepal area are very common.
The flora of Nepal or central Himalaya is a mixture of eastern and western Himalayas. There are certain species of Acer e.g., Acer cappadoscicum, Quercus floribunda and Populus ciliata etc. which are not found in eastern Himalaya but are present in Central Himalaya.
Phytogeography Region # 8. Flora of Western Himalaya:
The region of western Himalaya extends from Kumaon ranges to Kashmir. Plants are present in cold, dry climate and high altitude. The vegetation of this region consists of chiefly Acacia modesta, Euphorbia royleana, Olea, Bombax ceiba, Themada, Chrysopogon serrulatus, Bauhinia vahlii, Shorea robusta, Cassia fistula, Lagerstroemia parviflora, Murraya keonigii, Zanthoxylum alatum, Terminalia, Anogeissus latifolia, Toona ciliata, Zanthoxylum alatum, Adhatoda, Carissa, Rosa, Rubus, Syzygium, Crataegus, Diospyros, Emblica, Picea, Pinus wallichiana, Cedrus deodara, Rhamnus, Salix, Berberis, Smilax, Arundinaria, Fraxinus, Fragaria, Viola, Artemesia, Rheum, Sedum, Betula, Anemone, Saxifraga, Geranium, etc.