Guwahati: In a remarkable botanical breakthrough, a team of Indian researchers have found Ranunculus trichophyllus—a cold-water aquatic herb unseen in the Eastern Himalaya for 115 years—during recent fieldwork in Tawang, Arunachal Pradesh.
The species was last recorded in Sikkim in 1909, making this one of the most significant Himalayan plant rediscoveries in recent decades.
The study was carried out by Suman Halder of the Botanical Survey of India (BSI), Botanic Garden of Indian Republic, Noida; Piyush Gaikwad, Divisional Forest Officer (Western Arunachal Circle), Tawang; and Anand Kumar of BSI’s Central National Herbarium, Howrah. Their work extends the species’ known range eastward into Arunachal Pradesh for the first time.
The researchers encountered the plant while surveying the pristine high-altitude wetlands surrounding P.T. Tso Lake at 4,000 metres.
At first glance, it appeared to be a typical aquatic herb, but the finely divided capillary leaves and solitary white flowers with yellow centres matched the diagnostic features of Ranunculus trichophyllus. The identification was confirmed after consulting herbarium specimens from CAL, BSD, G, K, and P, along with global literature.
Images from the study show the dramatic mountain-ringed lake where the plant was located, alongside close-ups of the flower that helped establish its identity.
Historical records reveal that the species was widely collected across the Western Himalaya in the 1800s and early 1900s—from Jammu & Kashmir, Himachal Pradesh, Ladakh, and Uttarakhand. But in the Eastern Himalaya, it had been known only from Sikkim, and no collection had been made since 1909. A graph in the paper charts this long absence.
The new Tawang collection—catalogued by Suman Halder (ARUN)—ends this century-long gap.
Ranunculus section Batrachium—to which R. trichophyllus belongs—is a group of delicate aquatic herbs that thrive only in cold, oxygen-rich waters. Their sensitivity to ecological change makes them powerful indicators of wetland health.
By documenting the species in Arunachal Pradesh for the first time, the researchers have updated India’s floristic knowledge and highlighted the rich biodiversity of Tawang’s alpine wetlands, ecosystems increasingly vulnerable to climate change, shrinking water bodies, and unregulated tourism.
The plant was found growing alongside iconic Himalayan species such as Abies densa, Ligularia amplexicaulis, Cyananthus lobatus, and Rhododendron anthopogon, illustrating the unique plant communities that define Tawang’s high-altitude landscapes.
The finding underscores a growing understanding among botanists: even well-documented Himalayan regions still harbour species waiting to be found again.
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