Checklist of threatened plants of Sabah, Malaysian Borneo

Covering approximately 10% of Borneo’s land area, Sabah is one of the global hotspots for plant biodiversity, yet it faces increasing threats to its flora due to habitat loss and exploitation. This paper aims to compile a comprehensive checklist of threatened plant species in Sabah based on assessments published in the IUCN Red List of Threatened Species. A total of 660 vascular plant species from 73 families and 199 genera are classified as threatened and compiled in this checklist. Of these, 71 species are listed as Critically Endangered, 169 are Endangered, and 420 are Vulnerable. The high-value timber family Dipterocarpaceae, with 101 species from eight genera, has the highest number of threatened species. Notably, the genus Shorea contributes 44 species, the highest among all other genera. Around 76% of these threatened species are endemic to Borneo, including 239 species that are endemic to Sabah. Despite recent assessment efforts, only 39% of Sabah’s plant species have been evaluated under the IUCN Red List, and non-seed plants are severely underrepresented. This checklist provides essential data to inform conservation planning and policy in Sabah, underscoring the urgent need for continued assessment and protection of its unique plant diversity.