The history of various floras of Himalayas was started from 2.5 million years ago during the age of Pleistocene. Many geographical changes and ups and downs happened in the region and during this long journey the present-day floral communities grow in Himalayas with a diversity of species and variations based on its various altitudes. After many geomorphological changes, the present-day life forms arrive or return on the rocks and these are mainly lichens, liverworts, various species of mosses etc. They have been developed with their fine root systems on the rock and some of them have their arial root systems and depended on moister of the air. The other variety of species are also developed across the Himalaya based on its climatic and altitude variations. Stellaria decumbens and Arenaria bryophylla were developed even in the altitude of 6,100 metres.
In the history of botanical exploration in Himalaya, many great botanists have a great contribution and one of the prominent names is Sir Joseph Dalton Hooker who started his exploration in Sikkim in 1849 AD. He visited different parts of Darjeeling and Sikkim Himalayan region and identified various species of plants in that region including Singalila range, great Runjeet river valley, Zongri, Lachen valley, Lachoong etc. Hooker identified 36 species of Rhododendrons in Sikkim and out of these 36 species 24 species are new in the taxonomy. Not only Hooker but there were also many other great Indologists who also have a great contribution to the exploration of Himalayan botanical knowledge including Hugh Falconer, the then superintendent of Botanical Gardens in Calcutta, Dr. Nathaniel Wallich who was the curator of the Indian Museum of Calcutta, Dr. Thomas Thomson who was associated with Tibetan Mission, Mr. White, Dr. Campbell and many more.
Botanical diversity is one of the unique features of Himalayan beauty. In different altitudes and climatic conditions variety of species and different flowering plants can be an attraction to travel Himalayas. Some of the available plants are gentian, anemone, potentilla, primrose, saxifrage, parnassia, ampanula, pedicularis and different species of orchids. Also, there are many types of Rhododendron sp, junipers, pine and so on. It is an unexplored experience of Himalayas.