Lost’ for 160 years, Himalayan plant rediscovered in Dibang Valley

Guwahati: A plant species last seen during British-era botanical explorations has resurfaced in the forests of Arunachal Pradesh—160 years after it vanished from scientific records—offering both a moment of scientific triumph and an urgent conservation warning.

The rediscovery was made during field surveys in 2023 by scientist Dr Umeshkumar L. Tiwari of the Botanical Survey of India and has now been formally documented in the Nordic Journal of Botany. Beyond confirming the plant’s survival, the study resolves a long-standing taxonomic puzzle that dates back to the 19th century.

The species, Phialacanthus griffithii, is a rare flowering shrub belonging to the Acanthaceae family, now recorded from the Upper Dibang Valley of the Eastern Himalaya.

It was originally collected in the 1860s from the Mishmi Hills by British botanist William Griffith but was never seen again—leading generations of botanists to assume it had either gone extinct or remained hidden in one of India’s least-explored landscapes.

“The rediscovery of Phialacanthus griffithii after more than 160 years underscores its rarity and conservation concern,” Tiwari notes in the study. “The species is currently known from a single extant population in the Upper Dibang Valley, located at around 798 metres elevation in a moist evergreen subtropical forest. No other recent records exist, and it has not been documented in any Indian floristic survey since its original description.”

The absence of fresh collections for over a century and a half had also left the plant’s identity in limbo. “Since its original description, the species had not been recollected or reported, and its identity remained uncertain due to the lack of comprehensive morphological data,” the study says. As a result, the species was omitted from several regional floras and conservation assessments.

A ghost from colonial botany

When Phialacanthus griffithii was first described in 1876 by George Bentham and Joseph Dalton Hooker, no single “type specimen” was designated—a requirement under modern botanical rules. With no subsequent collections, the species gradually slipped into obscurity.

The new study designates a lectotype from Griffith’s original specimens preserved at the Kew Herbarium, stabilising the plant’s scientific identity after decades of uncertainty. Fresh field collections have also allowed researchers to document its morphology, flowering pattern and ecological niche for the first time.

A fragile survivor

The rediscovered shrub grows as an understory plant in moist evergreen forests at around 800 metres elevation, producing striking yellow, tubular flowers that stand out against the dark forest floor. But its survival appears precarious.

So far, scientists have located only a single population, with fewer than 50 mature individuals observed. No seedlings were recorded during field surveys, raising concerns about poor regeneration. Insect-damaged flowers and the absence of documented pollinators further cloud the species’ future.

Based on these findings, the plant has been assessed as Critically Endangered under the criteria of the International Union for Conservation of Nature, reflecting its extremely limited distribution and high vulnerability to habitat disturbance.

Tiwari notes that the plant occupies a unique ecological niche in a mid-elevation forest belt typically dominated by tropical elements. “This suggests that P. griffithii may serve as a useful indicator species for monitoring ecological integrity in these forests,” he writes, adding that low flowering frequency and the absence of seedlings point to possible reproductive limitations linked to pollinator decline or genetic bottlenecks.

Conservation urgency

The rediscovery once again highlights the Eastern Himalaya’s status as a global biodiversity hotspot, particularly regions like Dibang Valley that remain botanically underexplored due to rugged terrain and limited access. Scientists say the find is a reminder that even well-known plant families can still harbour “missing” species in India’s remote forests.

At the same time, the habitat where Phialacanthus griffithii survives faces growing pressure from shifting cultivation, selective logging and road expansion, all common across the Eastern Himalaya. Without targeted in situ and ex situ conservation measures, researchers warn, the species could disappear again—this time permanently.

For conservationists, the rediscovery is both a success story and a cautionary tale: proof that rare species can endure unnoticed for generations, but also evidence of how narrowly balanced their survival has become in a rapidly changing landscape.

As India steps up biodiversity documentation and conservation planning, the forests of Dibang offer a stark reminder—there is still much left to discover, and even less time to protect it.

Also Read: Arunachal: New ginger species discovered in Siang Valley