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    VEGETATION of Rajasthan Thar desert
    By Ashwani Kumar | September 24th 2009 10:17 PM | Print | E-mail | Track Comments
    About Ashwani

    Professor Emeritus ,Former Head of the Department of Botany, and Director Life Sciences, University of Rajasthan, Jaipur. 302004, India At present...

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    VEGETATION The vegetation of the area has been classified as “scrub jungle”. Plants which can either adapt themselves to high temperatures or to low temperatures and discouraging conditions of soil and rainfall can be found. The trees are commonly lacking, shrubs are the dominant perennials, most of which form thickets e.g. Crotalaria burhia, Leptadenia pyrotechnica, Saricostoma pauciflorum and Zizyphus nummularia. This perhaps is the reason for a very low percentage of tree species. The vegetation can be classified on the basis of habitats viz. 1. Vegetation of sandy areas 2. Weeds and escapes of cultivation 3. Vegetation on hilly tracts 4. Plants of aquatic habitats. 1. Vegetation of Sandy areas The vast sandy tracts which are distributed in the western and central plains of the district, from the dunes to the plains. The dunes are gradually stabilised due to the growth of sand binders like Calotropis procera, Leptadenia pyrotechnica, Aerva tomentosa, Saccharum bengalense, etc. they provide suitable habitat for the growth of some annual grasses e.g. species of Cenchrus, Eragrostis, Aristida, etc., plants like Convolvulus, species of Heliotropium, Indigofera, Tephrosia and perennials like Crotalaria medicaginea and Shurbs like Acacia jacquemontii. If the biotic influence is not allowed to play its devastating role, luxuriance of these species is seen. Moreover, plants like Lepidagathis trinervis, Pulicaria angustifolia along with many others like Cassia tora, Dicoma tomentosa, etc. appear. In such cases the annual herbs form the carpet flora and amongst them the common components are plants like Pupalia, Achyranthes aspera, species of Tephrosia, Indigofera, Portulaca, Justicia, Phyllanthus, Aristida and Commelina. The following tree species also found in the sandy areas – Prosopis cineraria, Balanites aegyptiaca, Zizyphus mauritiana, Ailanthus excelsa, Tecomella undulata, Acacia nilotica var. indica and Holoptelea integrifolia. In the sandy areas Cistanche tubulosa, species of Orobanche and Striga are the most common parasites. Cuscuta spp. are the common total stem parasites. 2. Weeds & Escapes of cultivation Amongst the weeds that occur in the winter crop, the most common ones are prostrate herbs viz. Portulaca meridiana, Malva parviflora, Fumaria indica, and Veronica agrestis. Of the tiny and slender herbs, the most common ones are : Plantago pumila. Stellaria medica, Oldenlandia pumila, Asphodelus tenuifolius is a common geophytic herb. Xanthium strumarium, Argemone mexicana, Pulicaria angustifolia, Acanthospermum hispidium, and Digera muricata are some of those weeds which occur gregariously and can thus be troublesome to some extent. Some of the species which occur exclusively in the rainy season e.g. Cleome gynandra, Sesbania sesban, Tribulus terrestris, Sesamum indicum, Mollugo cerviana, Trianthema Portulacastrum, Aristida spp. Eleusine spp. and Cynodon dactylon. 3. Vegetation on hilly tracts Majority of hills in Jaipur are almost barren. However Hills in the Amber region have Anoegissus pendula, Boswellia serrata and Sterculia urens along with Butea monosperma Their permanent vegetation comprises of Euphorbia neriifolia clumps, which support some seasonal annual vegetation during rains. These hills mostly comprise of denuded rocks. Some grasses like Aristida spp., Oropetium thomaeum grow and cover these hills during rainy season. A large majority to the trees in the area are restricted to the hills. Sterculia urens, Commiphora wightii, Anogeissus pendula, Boswellia serrata, Lannea coromandelica, Rhus mysorensis, Adina cordifolia, Diospyros melanoxylon, Wrightia tinctoria, Cassia fistula,. Aegle marmelos. Cordia gharaf and Ficus racemosa occur naturally on the hills but have probably been introduced in other areas. Some other species like Grewia tenax, Butea monosperma and Acacia senegal are restricted to the bases of the hills. These hills change their colour to green due to presence of leaves during rains and look ash coloured in rest of the year, due to the dominant species Anogeissus pendula which is a deciduous small tree of the hill tops. Some of the Shurbs of common occurrence are : Grewia damine, Melhania hamiltoniana, Plumbago zeylanica, and Lantana indica. The herbaceous flora of the general surface of the hills is rich during rains and is composed mainly of small herbs. Some of the prostrate herbs growing during this period are Triumfetta rhomboidea, Boerhavia diffusa, Lepidagathis trinervis, Cassia pumila, Indigofera cordifolia, Tephrosia pauciflora, T. strigosa etc. Some of the erect form are Crotalaria triquetra, Cassia absus, Bidens biternata, Solanum indicum, Dicoma tomentosa, Achyranthes aspera, Acalypha ciliata etc. Urginea indica is a common geophyte which can be identified by its leaves during rainy season and by its copper coloured scapes and flowers during the spring season. 4. Plants of aquatic habitats Jaipur division is devoid of any permanent streams and rivers. There are seasonal rivers where water may stay beyond the rainy season in some deep ditches. Therefore a permanent aquatic vegetation is absent except in some deep ditches inside the area of the reservoir. As usual, the aquatic vegetation is free floating, submerged, anchored on marginal belts and of the plants on the banks that are liable to submersion. Free floating and submerged vegetation consists of members of the family Hydrocharitaceae viz. Vallisneria spiralis Hydrilla verticillata, and Naian graminea. Species of Lemna and wolffia often form a scum on water and in places devoid of nitrogenous matter, Utricularia aurea is also seen at some places. Plants growing on marshy banks commonly grow in the marsh but are often submerged under water. The common ones of these are: Aeschynomene indica, Polygonum glabrum, Typha elephantina, Scirus roylei, Arundo donax, Imperata cylindrica and other like the twinner Oxystelma esculentum commonly seen on, Typha spp., Phoenix sylvestris is the arborescent species of such courses. The vegetation of the area has been classified as “scrub jungle”. Plants which can either adapt themselves to high temperatures or to low temperatures and discouraging conditions of soil and rainfall can be found. The trees are commonly lacking, shrubs are the dominant perennials, most of which form thickets e.g. Crotalaria burhia, Leptadenia pyrotechnica, Saricostoma pauciflorum and Zizyphus nummularia. This perhaps is the reason for a very low percentage of tree species. The vegetation can be classified on the basis of habitats viz. 1. Vegetation of sandy areas 2. Weeds and escapes of cultivation 3. Vegetation on hilly tracts 4. Plants of aquatic habitats. 1. Vegetation of Sandy areas The vast sandy tracts which are distributed in the western and central plains of the district, from the dunes to the plains. The dunes are gradually stabilised due to the growth of sand binders like Calotropis procera, Leptadenia pyrotechnica, Aerva tomentosa, Saccharum bengalense, etc. they provide suitable habitat for the growth of some annual grasses e.g. species of Cenchrus, Eragrostis, Aristida, etc., plants like Convolvulus, species of Heliotropium, Indigofera, Tephrosia and perennials like Crotalaria medicaginea and Shurbs like Acacia jacquemontii. If the biotic influence is not allowed to play its devastating role, luxuriance of these species is seen. Moreover, plants like Lepidagathis trinervis, Pulicaria angustifolia along with many others like Cassia tora, Dicoma tomentosa, etc. appear. In such cases the annual herbs form the carpet flora and amongst them the common components are plants like Pupalia, Achyranthes aspera, species of Tephrosia, Indigofera, Portulaca, Justicia, Phyllanthus, Aristida and Commelina. The following tree species also found in the sandy areas – Prosopis cineraria, Balanites aegyptiaca, Zizyphus mauritiana, Ailanthus excelsa, Tecomella undulata, Acacia nilotica var. indica and Holoptelea integrifolia. In the sandy areas Cistanche tubulosa, species of Orobanche and Striga are the most common parasites. Cuscuta spp. are the common total stem parasites. 2. Weeds & Escapes of cultivation Amongst the weeds that occur in the winter crop, the most common ones are prostrate herbs viz. Portulaca meridiana, Malva parviflora, Fumaria indica, and Veronica agrestis. Of the tiny and slender herbs, the most common ones are : Plantago pumila. Stellaria medica, Oldenlandia pumila, Asphodelus tenuifolius is a common geophytic herb. Xanthium strumarium, Argemone mexicana, Pulicaria angustifolia, Acanthospermum hispidium, and Digera muricata are some of those weeds which occur gregariously and can thus be troublesome to some extent. Some of the species which occur exclusively in the rainy season e.g. Cleome gynandra, Sesbania sesban, Tribulus terrestris, Sesamum indicum, Mollugo cerviana, Trianthema Portulacastrum, Aristida spp. Eleusine spp. and Cynodon dactylon. 3. Vegetation on hilly tracts Majority of hills in Jaipur are almost barren. However Hills in the Amber region have Anoegissus pendula, Boswellia serrata and Sterculia urens along with Butea monosperma Their permanent vegetation comprises of Euphorbia neriifolia clumps, which support some seasonal annual vegetation during rains. These hills mostly comprise of denuded rocks. Some grasses like Aristida spp., Oropetium thomaeum grow and cover these hills during rainy season. A large majority to the trees in the area are restricted to the hills. Sterculia urens, Commiphora wightii, Anogeissus pendula, Boswellia serrata, Lannea coromandelica, Rhus mysorensis, Adina cordifolia, Diospyros melanoxylon, Wrightia tinctoria, Cassia fistula,. Aegle marmelos. Cordia gharaf and Ficus racemosa occur naturally on the hills but have probably been introduced in other areas. Some other species like Grewia tenax, Butea monosperma and Acacia senegal are restricted to the bases of the hills. These hills change their colour to green due to presence of leaves during rains and look ash coloured in rest of the year, due to the dominant species Anogeissus pendula which is a deciduous small tree of the hill tops. Some of the Shurbs of common occurrence are : Grewia damine, Melhania hamiltoniana, Plumbago zeylanica, and Lantana indica. The herbaceous flora of the general surface of the hills is rich during rains and is composed mainly of small herbs. Some of the prostrate herbs growing during this period are Triumfetta rhomboidea, Boerhavia diffusa, Lepidagathis trinervis, Cassia pumila, Indigofera cordifolia, Tephrosia pauciflora, T. strigosa etc. Some of the erect form are Crotalaria triquetra, Cassia absus, Bidens biternata, Solanum indicum, Dicoma tomentosa, Achyranthes aspera, Acalypha ciliata etc. Urginea indica is a common geophyte which can be identified by its leaves during rainy season and by its copper coloured scapes and flowers during the spring season. 4. Plants of aquatic habitats Jaipur division is devoid of any permanent streams and rivers. There are seasonal rivers where water may stay beyond the rainy season in some deep ditches. Therefore a permanent aquatic vegetation is absent except in some deep ditches inside the area of the reservoir. As usual, the aquatic vegetation is free floating, submerged, anchored on marginal belts and of the plants on the banks that are liable to submersion. Free floating and submerged vegetation consists of members of the family Hydrocharitaceae viz. Vallisneria spiralis Hydrilla verticillata, and Naian graminea. Species of Lemna and wolffia often form a scum on water and in places devoid of nitrogenous matter, Utricularia aurea is also seen at some places. Plants growing on marshy banks commonly grow in the marsh but are often submerged under water. The common ones of these are: Aeschynomene indica, Polygonum glabrum, Typha elephantina, Scirus roylei, Arundo donax, Imperata cylindrica and other like the twinner Oxystelma esculentum commonly seen on, Typha spp., Phoenix sylvestris is the arborescent species of such courses.