Ethnobotanical wealth of the Indian Himalaya: a synthesis of useful species, traditional knowledge and conservation priorities

The Himalaya constitutes one of the significant repositories of traditional plant knowledge maintained by indigenous communities over centuries. Its systematic synthesis is critical for conservation, drug discovery, and reversing loss of biocultural heritage. This study aimed to evaluate trends on utilization of plant resources by the indigenous communities across the Indian Himalaya. A systematic review following PRISMA framework was conducted to document all useful species—including plants, fungi, lichens, and algae—reported from the Indian Himalaya. After harmonization of data for taxonomy, distribution, life forms, uses, plant parts and diseases, a comprehensive analysis was conducted on spatial distribution, usage and conservation priorities of useful species in the Indian Himalaya. Because the number of source studies differs greatly among states, state-level richness was modelled statistically against research effort, area and number of districts sampled, and was additionally standardized by sample-based rarefaction and Chao2 estimation of inventory completeness. A total of 5,404 useful species were documented, constituting 90% angiosperms and 4.5% fungi. Herbs were the prominent life form (49.3%), and medicinal plants were most prevalent (96.4%), followed by human food (49%) and material use (36.6%). Raw species totals were highest in Uttarakhand (44.6% of the flora), Himachal Pradesh (34.0%) and Arunachal Pradesh (30.9%), but these rankings largely track research effort: the number of source studies alone explained 86.5% of the variance in state-level richness (R² = 0.865, p < 0.001). After standardizing to a common effort of 57 publications, Arunachal Pradesh ranked highest (946 species, 95% CI 653–1,255), ahead of Uttarakhand (587, 301–1,048) and Himachal Pradesh (555, 283–872), while the Assam hills yielded the most species per publication of any unit (24.6). Chao2 estimates indicate that no unit is more than 69% inventoried. Leaves were the most frequently utilized plant part (51.1%), followed by whole plant (30.4%), fruits (27.4%), and roots (26%); 51.3% of species had at least one part whose collection is potentially destructive. Only 23.5% of the useful flora has been assessed by the IUCN Red List, among which 95 species are threatened (17 Critically Endangered, 34 Endangered, 44 Vulnerable). Medicinal plants were used to cure more than 3,000 ailments with highest use values for Acorus calamus , Centella asiatica , Phyllanthus emblica , Cannabis sativa , and Picrorhiza kurroa . The Indian Himalaya harbors an extraordinary and largely untapped reservoir of ethnobotanical knowledge. The breadth of medicinal applications, the multi-functional use of plant resources, and the identification of high-use-value species provide a robust evidence base for prioritizing conservation interventions and phytochemical research. The strong dependence of recorded richness on research effort further identifies the eastern Himalayan states as the highest-return targets for future primary fieldwork. Not applicable.