The district of Darjeeling in West Bengal lies between 26°31' and 27°13' north latitude and between 87°59' and 88°53' east longitude. It is somewhat triangular in shape. The district has a total area of 3,075 sq km with Nepal on the west, Sikkim on the north, Bhutan on the north-east, Purnea district of Bihar abutting on the south and district Jalpaiguri of West Bengal on the south-east. The principal town is Darjeeling. This is the administrative headquarter of the district. The town Darjeeling is situated in the lower Himalayas in 27°13' north latitude and 38°16' east longitude. The district has four sub-divisions namely Darjeeling, Kalimpong, Kurseong and Siliguri. The name Darjeeling is believed to have been derived from the Tibetan word 'Dorje' which is the scepter of Indra, the God of thunderbolt and 'ling' means the place. The name therefore means the place of Dorje or the thunderbolt.

     Darjeeling falls into two distinct tracts, the Tarai immediately beneath the hills and the ridges and deep valleys of the lower Himalayas. The Tarai portion of the district is a lowlying belt, traversed by numerous rivers and streams rushing down from the hills and by the upland ridges which mark their courses. Behind the Tarai, the mountains lower abruptly from the plains, which are here only about 300 ft above sea level, in lofty spurs reaching to 6,000 and 10,000 ft, and culminate in a series of long ridges and valleys. The slopes, from about 6,000 ft downwards, are now dotted with trim tea gardens interspersed with small tracts of land reserved for native cultivators. Above that level they are clothed in dense forest, through which torrents rush down; but at the higher levels on the Singalila range, there are wide grassy slopes broken here and there with pine forests and masses of Rhododendrons.

     The Himalayan range has commonly three main zones. A) The great range of snowy peaks which roughly speaking form the axis of the chain. B) The lower or outer Himalayas, forming a broad belt of mountains of inferior, though still considerable altitude south of the snows and (C) The comparatively low hills forming the Sub-Himalayan zone either as ridges or spurs contiguous with the outer hills or separated from them by the flat-bottomed valleys. In Darjeeling, the mountains belong to the lower Himalayan zone and consist of long tortuous ranges, running generally from north to south throughout its length. The Sub-Himalayan zone is altogether wanting, and the detached ridges met elsewhere in the Himalayas are unrepresented, while the snowy range lies far beyond the limits of the district to the north, where it gives the appearance of a long range of mountains stretching east and west. This range forms the great backbone of the Darjeeling Himalayas. To the north-west tower the giant peaks of Kanchanjungha and to the north-east is Dongkya. From Kanchanjungha the Singalila range, stretches south to the plains, forming the boundary between Nepal and Darjeeling. It is the continuation of the ridge in the south and then south-easternly direction by Tonglu and Senchal, with its various lateral spurs, which constitutes the Darjeeling hill territory west to the Tista. To the east of that river a lofty ridge southwards from Dongkya, dividing at Gipmochi into two great spurs, one of which runs to the south-east and the other to the south-west, including between them the valley of the Jaldhaka. It is the lower half of the south-western spur, with its numerous ramifications, that constitutes the hills of Kalimpong east of the Tista.

     The Singalila ridge commands Nepal on one side, Sikkim and Darjeeling on the other and it is the watershed of two great river systems, for the streams on its western flank run into the Koshi and affluent of the Ganges, while those on its eastern flank run into the Tista, and affluent of the Brahamputra. The ridge has the highest peaks of Sandakphu and Phalut where the boundaries of Nepal, Darjeeling and Sikkim meet.

     South-east of the Singalila range four great hill ranges radiate from a central point at Ghum, situated to the north-west of the Senchal. One, the Ghum range, climbs due west to Simanabasti, where it meets the Singalila range. To the south, the Senchal-Mahaldiram range trends generally south-wards forwards Kurseong, the highest points being east Senchal ridge below Tiger Hill and west Senchal. The Third range, the Takdah or Tangbu range, branches off form the main Senchal ridge below Tiger Hill, and then takes a north-easternly direction, sinking gradually at the junction of the Great Rangit and Tista rivers. The fourth range, the Darjeeling-Jalapahar range, on which are situated the cantonments of Katapahar and Jalapahar and the civil station of Darjeeling, extends northwards from Ghum, at first rising rather abruptly, then gradually descending at the Chaurasta in Darjeeling, and again rising at Observatory Hill. At this point the range divides into two, the Lebong spur and the Takvar spur, enclosing between them the narrow valley of the Rangit, a tributary of the Great Rangit.

     The valleys of the south-eastern side of the Singalila ridge are drained by Mechi, Balasan and Mahanadi rivers, and all the remainders of Darjeeling hills is drained by the Tista and its tributaries, except the extreme eastern end, where the chief affluent is the Jaldhaka.

     The rocks of Darjeeling district can be divided into five groups, (1) The gneiss varies from a foliated granitoid rock composed of quartz, felspar and biotite to a more or less pure mica schist, and include partly intrusive granite and partly metamorphosed beds of sedimentary origin. (2) The Daling series covers a large area in the northern and eastern parts of the district, consisting of phyllite, slate and very subordinate bands of dolomite and crystalline limestone. Copper ore is frequently found disseminated through the slates and schists. (3) The Buxa series, which is largely developed in the western Duars occurs only at the extreme end of Darjeeling district and consists of slates, quartzites and dolomite. (4) The Gondawana beds crop out near the base of the hills and constitute a narrow band between the Dalings and the Tertiaries, running from Pankhabari to Dalingkot consisting chiefly of sandstone, shale and coal, all of which have been intensely crushed and faulted, and dip at high angles to the north-northwest; they are frequently metamorphosed by pressure, and their component rocks converted into quartzites, slates and graphitic schists. (5) The Tertiary beds fringe the older rocks continuously from close to the Mechi eastwards nearly as far as Dalingkot and consists of mica and felspar. Coal occurs in the bank of Gondawana rocks which run from Pankhabari to Dalingkot. The outcrops of these rocks form a series of bands, running more or less parallel to the genereal trend of the Himalayas and dipping one beneath the other into the hills. The most interesting feature of these subdivisions is that the youngest formations always appear to underline the older, thus the Tertiary beds disappear under the Gjondawanas; the Gondawanas under the Buxa and Daling series and the latter under the gneiss, the original order of superposition having been completely reversed by folding and faulting.

     The total population of the district is about 10,24,269 with a density of 331 heads per sq km. The spectacular growth in population ever since has been a problem of great concern. The people are mostly farmer or tea gardeners or gardeners of medicinal plants. The cultivable man : land ratio is fast on the decline due to rise in population. The district has an interesting assemblage of various ethnic groups, most of them being tribals. The great majority of the inhabitants in the hills are Nepalese, the rest is comprised of Bengalese, Muslims, Chinese, Marwaris, Europeans, Sherpas, Bhutias, Tibetans and Lepchas in varying degrees. The Nepalese community is historically a heterogenous mixture of tribes with respective dialects in addition to the Nepali language. Each ethnic group has its own social and religious traditions so that there exists a great deal of cultural diversity in the district. Socio-eco-nomically the district has rich natural resources. Good agroclimatic conditions of the areas have been utilized to develop only two industries like tea and medicinal plants including Cinchona.

     Floristically, Darjeeling is one jof the richest district in India with its various areas still due to be scientifically explored. The heavy annual rainfall and other climatic, physiographic and edaphic conditions combine themselves to provide the most conducive environment for richness in diversity of plant species. Even as far back as 1970, Sir Joseph Dalton Hooker, who was the first naturalist to study the Botany of the Eastern Himalayas, had recorded 4,000 different species of flowering plants under 160 families, 280 species of ferns and their allies of which, 8 were tree ferns, 20 palms, 23 species of bamboo and 440 species of orchids. The diversity of species is always on the increase as a result of natural hybridization and immigration from neighbouring countries.

     The most remarkable feature of natural vegetation of Darjeeling is the wonderful variety of species. There are in fact probably a few places in the world in which so many different types of forests exists within so small an area. At the highest altitudes, from the elevation of 8,000 to 12,000 ft forests of Abies webbiana are found interspersed with grassy slopes. These generally merge into extensive Rhododendron forests. Lower down are thickets of bamboos, which at 6,000 ft give way to forests of Chestnut (Castanea sp), Maple (Acer sp), Oak (Quercus sp), Magnolia (Magnolia sp), and Laurel (Laurus sp) the chief source of supply of timber and firewood. Still lower down, the Oak disappears and the chief species are Maple, Birch (Betual sp), Alder (Alnus sp) and the graceful Pipli (Bucklandia populnea). At the level of 4,000 ft these trees of the temperate zone are replaced by mixed forests, which, with the exception of Cederela toona are little value except for fuel. At 3,000 ft the upper limit of Sal (Shorea robusta) is reached and this tree is the chief constituent of valuable forests in the lower hills, extending from the extreme west of the district to the Chel river on the east, where it ceases abruptly. Besides the Sal forest, the Tarai, as the lower foot hills and adjacent plains are called, contains swamp, riverbed and savannah forests. The grassy savannahs used to be great source of danger to the adjoining forests from their extreme inflammability.

     The semi-tropical low level forests are found in the valleys and clothes the lower slopes of the hills. Shorea robusta which is found in patches up to about 3,000 ft in elevation, is the most valuable as well as the most characteristic timber tree in this zone. The other valuable species in order of importance are Tectona grandis, Michelia champaca, Duabanga Sonneratioides, Terminalia tomentosa, Terminalia myricarpa etc. This zone is included in the Tista valley range. It stretches from the Riyang river along the estern bank of the Tista as far as the junction with the Great Rangit, and then follows the western bank of the latter river as far as the junction with the Little Rangit. The ground is nearly everywhere steep and sometimes precipitous, and is broken up by several land slides.

     The most striking feature of the temperate forest is the wealth of orchids, ferns mosses and other epiphytes and creepers, which load the branches of the older trees. The trees belong to a great number of different genera, the most valuable are the Michelia excelsa, Cedrela toona, Quercus lamellose, Quercus lineata, Quercus pachyphylla, Castanopsis hystrix, Bucklandia populnea and Juglans regia.

     The sub-alpine tract is characterized in its upper portion of the forest of Abies webbiana which lower down gives place to the Tsuga brunoniana. This forest is mixed with Betula utilis and underneath of various Rhododendron spp and in the upper parts the Yew and Junipers are noticeable. The undergrowth in these forests between 7,000 to 10,000 ft consists of hill bamboos, Arundinaria recemosa. Several species of Aconitum are found at higher elevation of this zone.