Humboldtia Vahl – An under-utilised, under-researched, and vulnerable tree genus endemic to the Western Ghats-Sri Lanka biodiversity hotspot

Humboldtia Vahl is a tree genus restricted to a single biogeographic realm—the Western Ghats–Sri Lanka Biodiversity Hotspot. Consisting of only eight species, all of which are currently facing varying degrees of extinction risk, the genus represents one of the most vulnerable, evolutionarily distinctive, and understudied lineages within the region’s flora. Species of Humboldtia exhibit distinctive ecological adaptations, notably domatia-mediated ant–plant symbiosis and cauliflorous flowering, which underscore their evolutionary and ecological significance. The genus is characterised by a high degree of endemism, small and fragmented populations, and restricted gene flow, factors that contribute to its vulnerability and evolutionary isolation. Owing to these features, Humboldtia serves as an excellent model system for exploring the processes of speciation, biogeographical evolution, and ecological specialisation within tropical forest ecosystems. Given its exceptional ecological relevance and evolutionary distinctiveness, Humboldtia remains critically underrepresented in current research and conservation agendas. Focused scientific investigation and urgent conservation action are imperative to safeguard this unique genus and its integral role within the Western Ghats–Sri Lanka Biodiversity Hotspot. • Humboldtia Vahl, is a scientifically valuable yet underexplored endemic genus from the Western Ghats – Sri Lanka Biodiversity hotspot. • Comprising just eight species, all of which are under threat of extinction, the genus stands out as one of the most vulnerable, evolutionarily unique, and least explored plant lineages within the region’s flora. • The genus shows ecological adaptations, such as domatia-mediated ant–plant symbiosis and cauliflorous flowering, which are important in its natural habitat. • Humboldtia can be used as an exceptional model for investigating speciation dynamics, biogeographical diversification, and ecological specialisation in tropical forest ecosystems. • However, the genus remains poorly studied and inadequately protected, calling for increased attention in both research and conservation efforts.