Context: Darjeeling and Sikkim Himalayas are home to more than one-third of all types of rhododendrons found in India, reveals the latest publication of the Botanical Survey of India (BSI). The publication titled ‘Rhododendrons of Sikkim and Darjeeling Himalaya- An Illustrated Account’ lists 45 taxa of rhododendrons (36 species, 1 subspecies, 1 variety, and 7 natural hybrids). 

What are Rhododendrons? 

  • Rhododendron is a very large genus of about 1,024 species of woody plants in the heath family. They can be either evergreen or deciduous. Most species are native to eastern Asia and the Himalayan region, but smaller numbers occur elsewhere in Asia, and in North America, Europe and Australia.
  • It is the national flower of Nepal, the state flower of Washington and West Virginia in the United States, the state flower of Nagaland in India, the provincial flower of Jiangxi in China and the state tree of Sikkim and Uttarakhand in India. 
  • There are 132 taxa (80 species, 25 subspecies and 27 varieties) of rhododendrons found in India. Arunachal Pradesh is home to the highest number with 119 taxa (74 species, 21 sub species and 24 varieties) of the Rhododendron. The small State of Sikkim is home to 42 taxa (25 species, 11 sub-species and six varieties) while 10 taxa are found in Manipur, four in Mizoram and 11 in Nagaland. 
  • Darjeeling and Sikkim Himalayas comprise only 0.3% of India’s geographical area but the region is home to one-third (34%) of all Rhododendron types. This highlights the ecological significance of the region as far as an indicator species like Rhododendron is concerned 
  • Only three taxa — Rhododendron arboretum nilagiricum found in south India and Rhododendron colletianum and Rhododendron rawatti from the western Himalayas are not found in the north-east. 
  • The cold, moist slopes and deep valleys of the eastern Himalayas form a conducive habitat for the luxuriant growth of Rhododendron species 
  • Rhododendrons were first recorded by Captain Hardwick in Jammu and Kashmir in 1776 where he spotted the Rhododendron arboreum. However, it was a visit by the British botanist Joseph D. Hooker to Sikkim between 1848 and 1850 that revealed the rhododendron wealth of the Sikkim and Darjeeling Himalayas. 

What are the Uses of Rhododendron 

  • Rhododendrons are commonly used as an ornamental plant for gardens, plantations in the streets or vessels for its aesthetic value. Because of its numerous phytochemical potential, it is being utilized as a traditional remedy for different diseases.  
  • Flowers of this plant are traditionally utilized by the people residing in the mountainous region to make pickle, juice, jam, syrup, honey, squash, etc., and to treat various ailments like diarrhea, headache, inflammation, bacterial and fungal infections. 
  • Rhododendrons are indicator species as far as climate change is concerned and have a prominent place in the botanical history of the country. The flowering season starts in February and continues till April in the lower elevations while in the higher reaches, blooms appear in late May and continue till June. However, recently, flowering was found to begin as early as January for some species. “This is an indication that those areas are getting warmer and the phenology of rhododendrons can be an important indicator of climate change

What are the Threats? 

  • Of the 45 taxa documented by BSI, five are facing a high threat due to anthropological pressures and climate change. 
  • The Rhododendron edgeworthii, with white campanulate flowers, recorded a huge habitat decline in both Darjeeling and Sikkim. Rhododendron niveum, with big purple flowers, found in the Lachung area of north Sikkim is facing threats due to rampant constructions. Rhododendron baileyiRhododendron lindleyi and Rhododendron maddenii are also threatened. 

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