Bukidnon, Philippines — In a major botanical milestone, a new population of Rafflesia schadenbergiana, the Philippines’ largest and rarest flower, has been discovered blooming in Mt. Sinayawan within the Tangkulan Mountain Range of Bukidnon. This remarkable find extends the known range of the giant parasitic plant to a fourth mountain range in Mindanao — a triumph for biodiversity research and indigenous-led conservation efforts.
The discovery, published in Sylvatrop, the Department of Environment and Natural Resources’ (DENR) scientific journal, was made possible through routine forest patrols by community forest guards from the Kibongcog Tigwahanon Ancestral Domain (KTAD), in partnership with the Philippine Eagle Foundation (PEF).
At 73 centimeters in diameter, the flower is a member of the elusive and critically endangered Rafflesia schadenbergiana species — a giant, foul-smelling blossom that parasitizes vines of the genus Tetrastigma. The species was first discovered in Mt. Apo in 1882 and was believed extinct for over a century until reappearances in scattered sites in Bukidnon and South Cotabato. The Tangkulan Range find is the latest and northernmost known population.
“This discovery of the Philippines’ largest flower in Mt. Sinayawan is another example of the power of collaboration of IP, NGO, LGU, DENR, the academe and volunteers,” said Dr. Julie Barcelona, a botanist-taxonomist affiliated with the University of Canterbury and PEF research fellow, and one of the study’s co-authors.
The Tangkulan Range spans the municipalities of Valencia City, Quezon, and San Fernando and lies within the ancestral lands of the Manobo Tigwahanon, Manobo Pulangiyon, and Matigsalug communities. Despite its ecological value, the mountain range has long remained outside the formal protected area system, due in part to historical insecurity and limited scientific exploration.
However, local knowledge proved essential. According to the researchers, members of the KTAD community were already aware of the flower’s presence, but only recently shared the find with conservationists after observing blooms during patrols.
“Indigenous forest guards not only found the flower but documented buds, senescent blooms, and host vines — all crucial data for confirming the species,” said Andrei Von Mariano Tirona, lead author of the study and conservationist with the PEF.
The study details two sites within the ancestral domain where multiple flowers and buds were found in November 2023 and again in May 2024, including one fully open bloom measuring 66 cm in diameter. All plants were identified as R. schadenbergiana based on floral morphology and host species.
The rediscovery is especially timely as forested areas across Mindanao are under increasing pressure from land conversion, resource extraction, and climate change. Conservationists say this find can catalyze further protection of the Tangkulan Range, potentially leading to its designation as a Local Conservation Area (LCA) or Indigenous Community Conserved Area (ICCA) — a vital step toward national recognition as a Protected Area.
“This rare flower’s reappearance in a previously undocumented site signals hope, not only for the species, but for collaborative conservation in regions long overlooked due to conflict and inaccessibility,” said Dr. Jayson Ibañez, co-author and PEF’s Director for Research and Conservation.
Four species of Rafflesia are endemic to Mindanao, with R. schadenbergiana being the largest. It can grow up to 80 centimeters wide and is known for its striking reddish-orange color, mottled pattern, and strong odor that attracts pollinators like carrion flies.
The discovery was supported by Mandai Nature and the USAID-INSPIRE Project, with field assistance from the LGU of San Fernando and DENR regional offices in Northern Mindanao and SOCCSKSARGEN. The documentation effort forms part of a broader biodiversity initiative focused on indigenous co-stewardship and cultural conservation models.
With many of the known populations of R. schadenbergiana now found within ancestral lands or protected areas, researchers emphasize the importance of mapping potential habitats and involving local communities in field validation. Species distribution modeling — a technique being proposed by the authors — may help predict new habitats for conservation prioritization.
“This discovery reminds us that we are only beginning to understand the full richness of Mindanao’s forests. There’s still so much hidden in these mountains — and it’s often the indigenous peoples who know where to find it,” said Dr. Barcelona.
As the country continues to grapple with biodiversity loss, the giant Rafflesia’s bloom in Tangkulan stands as a powerful symbol — a reminder of the treasures that survive in Mindanao’s threatened landscapes and the key role that indigenous wisdom and stewardship play in protecting them.
Read the full scientific article:
A new distribution record of Rafflesia schadenbergiana in Mt. Sinayawan, Tangkulan Range, Bukidnon, Mindanao, Philippines – Sylvatrop Vol. 35 No. 1 (Jan–June 2025)
🔗 https://www.philippineeaglefoundation.org/resources
About Sylvatrop:
Sylvatrop is DENR’s official peer-reviewed journal for scientific and technical papers on Philippine ecosystems and natural resources. It is indexed in the Web of Science Master Journal List and is freely available at:
🔗 https://erdb.denr.gov.ph/publications/sylvatrop/