Guwahati: A plant previously thought to be confined to the Andaman and Nicobar Islands has been recorded in the hills of Assam’s Dima Hasao district, marking the first reported occurrence of the variety on mainland India.
Researchers have recorded Trigonostemon viridissimus var. confertifolius, a medium-sized shrub, in the Jatinga hills of Dima Hasao. Until now, the variety was known only from Saddle Peak in North Andaman and was regarded as endemic to the islands.
The discovery was made by a research team led by Dr Selim Mehmud, which found a naturally growing population of just six mature individuals at an elevation of around 630–720 metres in a moist, shady hill forest. The plants were found growing in association with larger trees.
The finding has been reported in a short communication published in National Academy Science Letters, titled “Trigonostemon viridissimus var. confertifolius (Euphorbiaceae), A New Record from Mainland India”. The paper was authored by Kangkan Kumar Das, Selim Mehmud, Himu Roy, Pranab Bujarbarua, Debjyoti Bhattacharyya and Tapas Chakrabarty.
The discovery is the second report in recent months suggesting an Andaman-Assam floristic link, highlighting the region’s rich biodiversity and the potential for further discoveries of both flora and fauna.
The finding also has taxonomic significance. The variety had previously been merged with T. viridissimus, but a later study reinstated it as a distinct variety, a treatment supported by the authors of the new study.
The researchers also noted some morphological variation in the Assam population, including differences in leaf-tip shape and minute serrations towards the leaf apex that had not been reported previously.
A tiny population, and a conservation question
The discovery comes with a conservation concern. Only a handful of individuals were found at the site, and the researchers said a formal population assessment following IUCN guidelines is required, particularly in view of the rapid decline in forest cover caused by frequent soil erosion, landslides and other anthropogenic activities.
For now, the finding extends the known range of the variety from the Andaman and Nicobar Islands to mainland India, revealing a strikingly disjunct distribution.
The researchers described the Assam record as an important addition to India’s plant diversity and said it underlines the value of continued botanical surveys
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