In this article we will discuss about the vegetation of various geographic regions of India: 1. Western Himalaya 2. Eastern Himalaya 3. Arid Zone 4. Gangetic Plain 5. Assam 6. Malabar 7. Deccan.
Geographic Region # 1. Western Himalaya:
In the tropical belt extending up to an altitude of 1000 mtr. we find a Sal forest (Shorea robusta Gaertn) of stunted trees in Kangra and Hoshiarpur but lofty trees in the Siwaliks and West Nepal.
Associated with Sal are found Terminalia tomentosa, Buchanania lanzan, Anogeissus latifolia, Ougenia oojeinensis etc. Bamboo groves of Dendrocalamus strictus are also met with.
The most important climbers are Bauhinia Vahlii, Spatholobus Roxburghii and Milletia auriculata. “Bhabar” tracts are met with where the forest is of open character with trees like Holoptelea integrifolia, Bombax ceiba, Garuga pinnata and Acacia catechu.
In moist situation Trewia nudiflora and Syzygium cumini occur. Near rivers Sal does not occur but Acacia catechu, Dalbergia sissoo and Bombax ceiba form alluvial forests with other deciduous trees. There are grassy tracts — the “savannah” — where the dominant grass isSaccharum narenga. Anthistiria gigantea and Imperata cylindrica are other grasses found on savannahs and other open Sal forests.
Above 1000 meters we come across a broad belt of coniferous forest with Pinus Roxburghii lining the base, and Deodar (Cedrus deodara), Blue Pine (Pinus walli-chiana), Pinus Gerardiana, Picea morinda, Cupressus torulosa, Abies pindrow — A. spectabiles and Junipers forming the upper limit.
Along with the Conifers, species of Oaks (Quercus ilex, Q.incana. Q.dilatata, etc.). Cornus capitata, Populus cilia, Betula utilis, Ulmus Waliichiana, Rhododendron arboreum, Aesculus indica, and species of Acer, Alnus, etc. are found.
Shrubby species of Rosa, Pyrus, Crataegus etc. are found in the open. The orchids are mostly terestrial and Eriophorum comosum is quite common. Species of Aquilegia, Paeonia, Adoxa and several herbs of Ranunculaceae, Labiatae, etc. and many grasses cover the forest floor.
Above the Coniferous temperate zone there is the alpine zone extending upwards from about 3000 mtr. Here wide fields of grassland are, found with herbs like — Corydalis, Primula, Delphinium, Anemone, Astragalus, Arenaria, Saxifraga, Epilobium, etc. Shrubby Rhododendron, Salix, Betula are also met with. Juniperus religiosa, Abies spectabiles, Picea Smitheana and Ephedra Gerardiana represent the Gymnosperms.
Geographic Region # 2. Eastern Himalaya:
The tropical zone is covered with a luxuriant flora. Here also we find a mixed Sal forest composed of tall trees with many climbers and sheltering many epiphytic orchids and ferns. The Sal forests stretch upto an elevation of about 1000 mtr. and are reserved forests.
According to Cowan 2 distinct types of Hyliums or associations are here met with viz:
(1) Shorea — Terminalia — Garuga Hylium and
(2) Shorea- StereospermHm Hylium.
In the former type along with Sal Terminalia bellirica, T.crenulata, Garuga pinnata and G.Gamblei predominate, while in the latter type Stereospermum is the predominant species along with Sal, and Terminalia crenulata is also common.
Schima Wallichii, Bauhinia purpurea, Sterculia villosa, Gmelina arborea, Dillenia pentagyna, Duabanga grandiflora, Lagerstroemia parviflora, Ficus cunia, etc. occur in both types of association, and in addition to these Toona ciliata, Tetrameles nudiflora, Stereospermum tetragonum, Premna mucronata, Dysoxylum binectariferum, Bombax ceiba, Callicarpa arborea, Litsaea polyantha, Albizzia odoratissima, Appanamyxis polystachya, Bischofia javanica are found in the former hylium and Grewia vestita, Elaeocarpus aristatus, Syzygium formosum, Meliosma simplicifolia, Terminalia chebula, Alstonia scholaris,Trewia nudiflora, Beilschmiedia Roxburghiana, B. sikkimensis, Abbizzia procera, Micromelum pubescens, etc. are found in the other, i.e. Shorea — Stereospermum hylium. Dendrocalamus Hamilton! a giant bamboo is frequent in both the hylii.
In places where rainfall is very high an evergreen type of forest is met with where Sal is totally absent or almost so. Here also we find 2 distinct hylii, e.g. Schima — Bauhinia Hylium and Syzygium — Phoebe Hylium. Common shrubs found in the forests of this zone are Bridelia stipularis., Capparis olacifolia, Leea robusta, L. crispa, Moghania macrophylla., Phlogacanthus thyrsiflorus, Coffea bengalensis, Morinda angustifolia, Ixora undulata, Ervatamia coronaria, Melastoma malabathricum, Clerodendrum viscosun C. nutans, C. serratus, Grewia sapida, G. serrulata, Pandanus furcatus, etc.
Three species of Calamasjiviz. C. flagellum, C. guruba and C. leptospadix are found here. Among the common climbers are Bauhinia Vahlii, Entada pursaetha, species of Mucuna, Ipomoea, Hoya, etc. Epiphytic orchids are many and there are many terrestrial and epiphytic ferns. Angiopteris evecta with very large fronds is frequently found.
Near rivers Acacia catedu, Dalbergia sissoo, Bombax ceiba and a few deciduous trees form a low alluvial forest. Grasslands are formed on dry beds of rivers that have changed their course. Here Saccharum spontaneum is gregarious. Other tall grasses are Imperata cylindrica, Themeda arundinacea, Arundinella nepalensis, etc. Capillipedium assimile is gregarious on lower hills.
In East Himalaya Coniferous forests are not met with immediately above 1000 mtr. Instead there are forests of broadleaved species. Thus we have Castanopsis tribuleides, C.indica, Schima Wallichii, Piioebe Hainsiana, P.attenuata, as the predominating trees in the forests. Bauhinia purpurea, Stereospermum tetragonum, Callicarpa arborea, Eryth’rina striata are other common trees in these forests.
At an altitude of about 2000 mtr. the forests are composed chiefly of Mchilus edulis, Michelia Cathcartii, Engelhardtia spicata, Castanopsis tribuloides Cinnamomum obtusilobium, Prunus nepaiensis, Nyssa javanica, Casearia glomerata, Ehretia Wallichiana, Actinodaphne sikkimensis, etc.
Ardisia macrocarpa, Boehmaria polystachya, Osbeckia crinita, O. nepaiensis, Maesa chisia, Polygonum molle are common shrubs and are gregarious at certain places. On marshy areas Acorus calamus grows often in pure formations.
This zone lying between 1000 and 2000 mtr. is called subtropical zone where the climate is humid and warm. The trees are usually covered with Mosses and Lichens and support many epiphytic Orchids and other Angiosperms and many ferns. At the foot of the hills and up to 2000 mtr. in Darjeeling district many tea gardens form a characteristic feature of the vegetation.
Above 2000 mtr. plants of teinperate region appear, e.g. Quercus lamellosa, Q.pachyphylla, Acer Campbelli, Michelia excelsa, Echinocarpus dasycarpus Meliosma Thomsoni, Turpinia nepalensis, species of Machilus, Litsaea, etc. Taxus baccata, Cupressus torulosa, Juniperus recurva and Tsuga damosa are found with Oaks, Ilex, Mahonia and Rhododendron.
Higher up the conifers predominate in the forests and the common species are Abies spectabillis, A.densa, Picea spinulosa, Larix Griffithiana, Juniperus squamata and I. Wallichiana. Rhododendron campanulatum a shrubby species grows gregariously.
Many other species of Rhododendron are found at an attitude of about 3000 mtr. of which R.lepidotum, R.setosum and R.anthogonium are dwarf species and are found also in alpine region. Prunus undulatus, Acer caudatum, A. pectinatum, A.sterculiaceum-Brassaiopsis algina, Schefflera, Sorbus, etc., are other broad-leaved species growing at that height.
In the alpine zone along with a few dwarf Rhododendron and Juniperus squamata Salix and Ephedra are also found. The herbaceous flora consists of species of Pedicularis, Primula, Cassiope, Areaaria, Iris, Meconopsis, etc. The grasses are species of Stipa, Phleum, Avena, Festuca and Agropyron.
Geographic Region # 3. Arid Zone:
The arid zone of India has an open forest mainly of Prosopis spicigera, Salvadora oleioides, Acacia nilotica and Capparis decidua. On irrigated lands Albizzia iebbek, Dalbergia sissoo, Azadirachta Indica, Cordia dichotoma and Ficus glomerafa are found.
On Aravalli hills and its outliers forest patches purely of Anogeissus pendula are frequently found. Other trees found there are Boswellia serrata, Grewia salvitolia, G.pilosa, Balanites aegyptiaca, Acacia Senegal,A.leucophloea, Commiphora mukul, Zizyphus numularia and Euphorbia nivulia.
In the western part of this region there are extensive tracts covered by Euphorbia nerlifolia composing the ‘Thor’ vegetation. Scrub jungles cover the rest of the area and are composed of Capparis decidua, Zizyphus glabrata, Commiphora mukul and shrubs and herbs like Soianum indicum, S.suratense, Scaevola frutescence, Atripiex Stocksii, Salicornia brachiata, Suaeda maritima, Fagonia cretica and Ephedra foliata.
Geographic Region # 4. The Gangetic Plain:
The vast tract is divided into 3 subdivisions, viz.:
(i) Upper Gangetic Plain
(ii) Lower Gangetic Plain and
(iii) The Sunderbans.
The whole area excepting the Sunderbans forming the littoral forests at the extreme south-eastern part, is thickly populated and open lands are none but cultivated fields. The natural vegetation is represented by a weed flora and trees planted in orchards and on road sides or growing self-sown in villages.
In the Upper Gangetic Plain trees common on roadside and villages are Azadirachta indica, Ficus rellgiosa, F. glomerata, F. benghalensis, F. Rumphii, Cordia dichotoma, C.Rothii, Acacia nilotica, Tamarindus indica, Albizzia lebbek, Pithecellobium dulce, Syzigium cumini, Manilkara hexandra and a few others.
Euphorbia neriifolia is planted in hedges and is often found gregarious. Agave cantalla an American fibre- plant is grown as a hedge-plant or in plantations. Lantana aculeata an exotic shrub is common all over the area. Dodonaea viscosa, Acacia farnesiana, Carissa carandas, Calotropis procera, C.gigantea, etc. are other shrubs common in the sub-region.
Open forests of Acacia catechu, Dalbergia sissoo, Tamarix Troupii, T.dioica and a few other trees are met with on sandy river banks with Asparagus racemosus, Soianum suratense, Alhagi pseudalhagi, etc. and tall grasses like Erianthus munja, Saccharum spontaneum, Vetiveria zizanioides and Themeda arundinacea. Borassus flabeilifer and Phoenix sylvestris occur wild and the former is occasionally planted.
The weed flora is composed of Xanthium strumarium, Blumea lacera, Cassia tora, Crotalaria medicaginea, Amaranthus spinosus, Argemone mexicana, etc. while the aquatic flora is represented by Nymphaea nouchali, Nelumbo nucifera, Ottelia alismoides, Ipomoea reptans, Trapa bispinosa, Nymphoides cristatum, Potamogeton crispus, Utricularia stellaris, etc.
Eichornia crassipes is found in stagnant pools and in canals where the current is not strong.
In the Lower Gangetic Plain the rainfall is higher and consequently the vegetation denser. The trees noticed in the Upper Gangetic Plain are met with in this subregion also where Trewia nudiflora,Diospyros peregrina, Polyalthea longifolia, Trema orientalis, Terminalia catappa,AIstonia scholaris, Gelonium multiflorum, Ficus hispida, Alangium salvifolium, Streblus asper are other common trees.
In addition to the shrubs found in the Upper Gangetic Plain Cassia sophera, Ecbolium viride, Blumea lacera, Abutilon indicum, Capparis zeylanica, Sida rhombifolia, Urena lobata, Sesbania sesban, Hyptis suaveolens, are very common.
Calotropis procera is absent in this tract. There are many climbers forming impenetrable thickets in places with the shrubby and herbaceous vegetation. Common among them are Coccinea cordifolia, Luffa cylindrica, Daemia extensa, Tylophora asthmatica, Cissus lanceolaria, Dioscorea pentaphylla, Smilax macrophylla, Tiliacora racemosa, and the exotic Mikania micrantha.
The aquatic flora is similar to that met with in the Upper Gangetic Plain. Here are found some tall herbaceous plants which are often gregarious, e.g. Polygonum orientate, Aeschenomene aspera, Typha elephantina, Cyperus exultatus, C. corymbosus, Phragmites karka, Panicum tripheron, etc. Azolla and Salvinia often cover the surface of water in the jheels and Marsilea is found on wet ground.
The Sunderbans occupy the southernmost area of the Lower Gangetic Plain, a comparatively small portion of which is within Indian Union. Here Phoenix paludosa, a dwarf palm is gregarious near inlands. This is replaced by species of Avlcennia further down.
Bruguiera gymrorhiza, Ceriops candolleana, Kandelia Rheedii, Aegiceras majus, A.rotundiiolia, Xytocarpus granatum, Lumnitzera racemosa are other species common in that area. Nypa fruticans a stemless palm with very large leaves and a few species of Heritiera grow where sweet and saline waters meet.
Geographic Region # 5. Assam:
Vegetation of Assam is similar to that of E. Himalaya except that there is no alpine flora. Here also we find sal forests at the foot of the hills and at lower elevations on the hills.
Amoora Wallichii, Vatica lancaefolia, Artocarpus chaplasha, Michelia champaka, Cinnamomum cecicodaphne, Dillenia indica, Aquilaria agailocha, Moras laevigata, etc. often form dense evergreen type of forests. Species of Dipterocarpus and Connarus also occur in Assam.
Hill forests are ever green broad-leafed forests or Pine-forests. The former includes species of Magnolia, Manglietia, Michelia, Schima, Acer, Pyrus, Prunus, Andromeda, Alnus nepalensls, Litsaea citrata, Betula alnoides and many species of Quercus and a few of Rhododendron at higher elevations.
Camelia drupifera is very common with Leucosceptrum canum, Eleagnus latifolia and Saurauja nepalensis. Berberls and Mahonia occur at higher altitude and Rubus, Zanthoxylon, Osbeckia and Polygala are common at about 2000 mtr. Gomphostemma, Hedycbium and many species of Impatiens and Polygonum are found at lower elevations.
Presence of Nepenthes Khasiana is noteworthy. Orchids, epiphytic and terrestrial are abundant and at some places the tree fern Cyathea imparts a characteristic form to the forest. There are many other ferns terrestrial or epiphytic in the valleys and on the hills.
Geographic Region # 6. Malabar:
In Malabar tropical evergreen forests are found from Kanara southwards and have lofty trees like Dipterocarpus indicus, Hopea parviflora, Calophyllum tomentosum, Dysoxylon malabaricum, Toona ciliata, Vateria indica, Canarium strictum, Mesua ferrea, Artocarpus lakoocha, Hydnocarpus Wightiana, Garcinia morella, Ochrocarpus longifolius and many other trees.
A reed like bamboo Ochlandra travancorica is common along hill streams. Barringtonia racemosa occurs in swampy areas.
Mixed deciduous forests occur in the north containing Tectona grandis, Dalbcrgia latifolia, Terminalia tomentosa, T. paniculata, T.bellirica, Lagerstroemia lanceolata, Pterospermum marsupium, Xylia xylocarpa, Grewia tiliaefolia and a few other species.
On Nilgiri hills at about 2000 mtr. a forest of sub-temperate or temperate nature is encountered. Here we find short trees like Michelia nilagirica, Ternstroemia japonica, Eurya japonica, Rhododendron nilagiricum, Gordonia obtusa, Ilex, Euonymus, Symplocos and many Lauraceae.
There are shrubs like Berberis tinctoria, Mahonia Leschenaultii, folygala arillata, Xanthoxylum, Strobiianthus, etc. and herbs like Anemone rivularis, Thalictrum javanicum, Viola serpens, Geranium nepalense, Parochaetus commanis, etc.
Geographic Region # 7. Deccan:
In Deccan proper mixed deciduous forests occupy the major part of the plateau with thorn forests in drier parts of central India and Mysore.
The thorn forests are open in character and consists of Acacia nilotica, A.leucophloea, Dichrostachys cinera, Balanites aegyptiaca, Butea monosperma, Emblica officinalis, Zizyphus nummularia, Z.oenoplia, Xylia xylocarpa, Boswellia serrata, Sterculia urens and Cochlospermum religiosum with grasses like Pennisetum setosum, P. pedicellatum, Heteropogon contortus, Chrysopogoa lanceolarius, Ischaemum angustifolium, Cymbopogon martini etc.
The mixed deciduous forests are composed of Tectona grandis, Terminalia tomentosa, T. bellirica, T. chebula, Anogeisus latifolia, Lagerstroemia parviflora, Pterocarpus marsupium, Dalbergia Cassia fistula, Butea monosperma, Lannea coromandelica, Schleichera oleosa, Buchanania lanzan and a few others.
The prevailing bamboo is Dendrocalamus strictus. In some parts Anogeissus pendula grows gregariously and Phoenix humilis a dwarf palm is frequent. Cymbopogon martini the Russa grass is very common. Sandal wood Santalum album grows in open forest in the uplands of Mysore, Coorg, Salem and N. Arcot. Pterocarpus santalinus, the Red sandal wood occurs in a dry type of mixed forest.
In the extreme south a special type of thorn forest exists consisting of Acacia planiformis, A.latorum, Prosopis spicigera, Cassia auriculata, Capparis divaricata, C. aphylla and a few fleshy Euphorbiaceae. Sal forests occur on the hilly tracts of Orissa, Chota Nagpur and Santal Parganas.
Chief companions of Sal in these places are Terminalia tomentosa, Pterocarpus marsupium, Anogeissus latifolia, Diospyros melanoxylon, Madhuka latifolia, Dalbergia latifolia, Schleichera oleosa, Holarrhena antidysenterica, Butea monosperma and Emblica officinalis.
The Coromandal subregion supports the same type of vegetation but is rather sparse. The steep slopes of Eastern Ghats are densely wooded.
In Carnatic a dry evergreen forest occurs with Mimusops hexandra, M.elengi, Diospyros peregrina, Strychnos nux — vomica, Pterospermum suberifolium, P.heyneanum, Memecylon edule, Cbloroxylon swietinia and species of Syzygium predominating, Mangroves occur in the estuaries of Coromandel. At the southern end Acacia planiformis and Cassia angustifolia are very common.