• Borneo’s Indigenous Punan people’s centuries-old plant knowledge is fading as younger generations turn to modern medicine, and secrecy limits knowledge sharing.
• Two important medicinal species, Cissus rostrata and Coscinium fenestratum, face severe conservation threats.
• Researchers emphasize long-term partnerships with Indigenous communities as essential for preserving both biodiversity and cultural heritage.

In Borneo’s dense rainforest, some communities of Punan people still find their medicine among the trees. For generations the forest has been their living pharmacy, with each medicinal plant tied to tradition. But as modern pressures grow, both the forest and the knowledge it shelters are slipping away.

To understand what’s at stake, researchers from Universiti Putra Malaysia traveled to Punan communities in the Malaysian state of Sarawak to document traditional medicinal practices and identify the plants behind them. The results were recently published in the journal Tropical Conservation Science.

Tribes in Sarawak, Borneo live in stilted longhouses often along rivers. Historically housing one kin group, today a longhouse is typically home to multiple extended families of mixed heritage. Photo by Beatrice Anak Kayok

Thirteen Indigenous Punan people guided ecologist Keeren Sundara Rajoo and his colleagues through the forest, locating plants and sharing a “spider web” of stories and knowledge. “When a plant species disappears, it’s not only a biological loss,” Sundara Rajoo said. “It also erases part of a community’s heritage and traditional knowledge system.”

Indigenous communities in Sarawak live in stilted longhouses, home to multiple families in private bilik rooms that open onto a shared ruai, the center of communal life. Another tribe’s longhouse may stand only 40 kilometers (25 miles) away, Sundara Rajoo said, yet each group preserves its own system of beliefs, unique language, and festivals.

Among these communities, the Punan are struggling to hold onto some of these cultural traditions. They believe their medicine draws its strength not only from the rainforest’s plants, but from the secrecy surrounding their use. According to a Punan elder, as translated by the researchers, “Our traditional remedies would lose their effectiveness if shared with others, so we need to be selective of what knowledge we share.” This guardedness makes documenting traditional ecological knowledge difficult.

A resident of Kampung Lebu Kulit, an Indigenous Kenyah community in Borneo, shows her cultivated medicinal herbs. Photo by Keeren Sundara Rajoo.

To bridge that gap, the team focused on forming trust-based relationships. “It’s better to build trust and work with communities on a personal level than to look for shortcuts,” Sundara Rajoo said. Their approach was to “eat what they eat, drink what they drink, and do what they do.”

Immersed in daily Punan life, the researchers observed a widening generational divide. Younger Punan increasingly rely on modern medicine, and when they do use herbal remedies, they often maintain the same secrecy as their elders. Less than half of the knowledge is typically passed to the next generation, Sundara Rajoo said. “And it’s only within their small circle of family members. So it’s at risk of extinction if it’s not documented properly.”

The Punan frequently harvest the roots of Coscinium fenestratum, known locally as Akar Penawar Kuning. Photo by Philip Lepun.

The risk of loss goes well beyond the Punan, said Mukesh Singh Sikarwar, an outside source and pharmacognosy researcher at Amity University, Madhya Pradesh. His work focuses on the natural compounds that form the basis of many modern medicines. “In the field of medicine, most discovery comes from nature,” he said. “These unique chemical entities will be lost if traditional wisdom is lost with Indigenous people.”

Aware of this fragile state, the researchers documented 19 medicinal plants used to treat ailments from eye infections to skin diseases, relying on co-author and dendrologist Philip Lepun for identification. Among them, Cissus rostrata, a woody vine whose leaves are used to treat abrasions, lacks a global IUCN assessment but is critically endangered in Singapore, suggesting similar risk elsewhere. Another vine, Coscinium fenestratum, whose roots are used to treat eye-related ailments, is designated as vulnerable. Across the forest, the greatest pressures on these plants come from deforestation, fragmentation, and potential medicinal overharvesting, with climate change adding to the uncertainty.

Borneo’s rainforests are often cleared to create land for agriculture including oil palm and rice, raising concern for native plant species. Photo by Rhett Ayers Butler.

This triple threat to medicinal knowledge — vanishing plants, secrecy, and fading traditions — makes the call for collaborative conservation urgent, Sundara Rajoo said. The researchers plan to continue their work through trusted partnerships, species mapping, and sustainable harvesting initiatives, hoping to provide a model for similar initiatives across Southeast Asia.

Scientists need to focus on long-term goals that “balance our planning or strategy with their belief,” respecting the perspectives and knowledge systems of the communities involved, Sikarwar said. Doing so can help conservation efforts maintain both cultural and botanical diversity.

Rainforest in northern Borneo. Photo by Rhett Ayers Butler

Citation: Rajoo, K. S., Lepun, P., Kayok, B. L. A., Hakiman, M., & Irie, M. (2025). Ethnobotanical Survey of Medicinal Plants Used by the Punan People of Sarawak, Borneo: A Conservation Perspective. Tropical Conservation Science, 18, 19400829251328561.

Cassidy Beach* is a graduate student in the Science Communication M.S. Program at the University of California, Santa Cruz. Other Mongabay stories produced by UCSC students can be found here.*