The Nilgiris, the smallest district of Tamil Nadu enjoys an equitable temperate climate and an annual rainfall ranges from 125 to 406 cm and hence harbouring interesting flora with potential medicinal value.
At an altitude of 6500 to 8500 ft above MSL, one can find common English plants, whereas at an altitude below 6500 ft one can find Australian and American introduced plants because at above this level, the vegetation changes from rich tropical and sub-tropical arboraceous flora of the Steep slopes to one or more temperate and also more herbaceous character. Owing to this, the nature has exploited the climate as well as the soil and thus harbours vide variety of indigenous exotic trees, flowers, and fruits. Over 2700 species of flowering plants, 160 species of fern and fern allies, countless types of flowerless plants, mosses, fungi, algae, land lichens are found in the sholas which are the ever green forest of this District. No other Hill station is said to have fostered so many of the exotic species as are found in the Nilgiris.
It is not strange to see quite often a foreign botanist recognising the precious merits of Indian plants, herbs, shrubs, trees, flowers etc., and visit the Nilgiris in search of new ones, especially the rare varieties of trees, flowers and fruits.
TREES
There are hundreds of species of trees adorning this beautiful District. It is famous for its towering and gigantic conifers, ever facinating pre-historic tree species like the living fossil - Ginkgo biloba, wide range of flowering trees like Prunus puddum, notable trees like Beech, Birch Maple, an array of Oaks, very rare - the true cork tree - Quercus suber and indigenous evergreen trees such as Micheria nilagirica, Rhododendrum Nilagaricum, Eucalyptus ficifolia etc
FLOWERS
The Nilgiris is endowed with temperate and equitable climatic conditions akin to that of England and other European countries. Hence, introduction of fascinating flower plants from all over the world to this hill station was commenced from the year 1846 onwards. Flowering annuals, biennials, perennials, climbers shrubs, trees etc., were introduced in the Government Botanic Garden, Udhagamandalam and Sim's Park, Coonoor and maintained as germ plasm collection.
Shrubs with colourful foliage and flowers of gorgeous colours add glamour to the garden, round the year. Many species of Fushsias (Dancing dolls), fascinating budleia, beautiful brugmansia (Angel's trumpet), enchanting camellia, breathtaking Streptosolon (Burning bush), attractive azalea, violet veronica, flambouyant Callistemon, delightful Dombeya, lovely Abutilon and Hydrangea are real attraction to the visitors. A wide range of lilies and bulbous plants of delightful colours and forms are seen here.
The upper Nilgiri plateau has a unique ecosystem comprising of rolling grass hills interspersed with dense montane evergreen forests (called Sholas) in the hollows between the folds. These have been termed as climax ecosystems that date back to many millions of years. These are home to several faunal forms like the endangered Nilgiri Tahr, the Nilgiri Marten and primates like the Nilgiri Langur. Birds like the Nilgiri laughing thrush are endemic to these areas. Plant endemism too, is remarkably high. For a small area, around one hundred plant species are not seen elsewhere on earth- not even in adjacent hills. Just one example, the upper Nilgiris is home to forty species of wild balsams - Europe has one species, found in Great Britain-of which one dozen are not seen anywhere else on earth. Many of these are highly endangered and perhaps on the brink of extinction.
The natural vegetation of the valley is typically a dense and rather low forest with much undergrowth and many epiphytes, mossess and ferns. Both tropical and temperate flora occur, vegetation being mostly tropical in character at lower elevations and temperate at higher elevations. Botanically as well as zoologically and ethonologically, the Nilgiris forms a distinct ecological realm of its own, the typical forests of Nilgiris is called "Sholas".
The different types of vegetation are,
1) The Shola grassland vegetation of the Nilgiris plateau. 2) The open sandal bearing scrub of the Sigur plateau. 3) The moist deciduous and the dry deciduous teak forest of the Nilgiris - Wynad and 4) The forests of south eastern outer slopes
Animals :
Nilgiri Tahr
Tahr are closely allied to goats. Its short crisp coat, the rounded outer surface of its horns and the presence of single pair of teats are distinguishing characteristics. Preferred habitat in Nilgiris is scarps and crags above forest level. They associate in flocks of half a dozen or more animals. Thye are extremely watchful against any danger from below but less conscious if coming from above.The population of Tahr is around 145.



Nilgiri Langur
In Nilgiris, the sholas or stretches of dense evergren forest are the favorite haunts with early morning whooping sound. They live at levels ranging from 3000 to 7000 ft and average at 8 to 9 animals per troop. In areas planted with wattle, the flowers and buds are the major source of food. The beauty of their fur and supposed medicinal value of their flesh, blood and organs have caused it to be an endangered species.
Giant Squirrel
Giant squirrel of the genus Ratufa are the largest known tree squirrels and exhibit a striking polymorphism in coat colour and pattern. They inhabit the deciduous mixed and evergreen forests and make loud alarm calls. Normally they keep themselves to the summits of the higher trees and seldom descend to the ground. They build large globular nests for breeding and roosting. Movement is terms of amazing leaps.