Floristic survey of Darjeeling Himalaya with emphasis on endemism and conservation status

The Darjeeling district of West Bengal, India, is an ideal home to many taxa, like any other part of the Great Himalayas. The floristic survey of the Darjeeling district provides an overview of the region's biodiversity within the Eastern Himalayan hotspot. The present study documented diverse plant taxa from the Darjeeling Himalaya by preparing herbarium specimens using standard methods, identifying them taxonomically and assessing their threat status using the IUCN Red List database. Using floristic inventories analysed through diversity indices (Shannon, Simpson, Margalef), similarity measures (Jaccard, Sørensen), non-metric multidimensional scaling (NMDS) ordination and permutational multivariate analysis of variance (PERMANOVA), quantified the spatial patterns of plant diversity across the study area. This study showed that Orchidaceae, Rosaceae, Lamiaceae, Fabaceae and Acanthaceae are the dominant plant families in the area and recorded 11 plant species that are either endemic or regionally restricted. The study revealed high alpha diversity (species richness 40–109; H′ = 3.69–4.69) and strong beta diversity driven mainly by species turnover (Jaccard dissimilarity 0.28–0.94), with altitude and associated temperature gradients significantly structuring community composition (PERMANOVA R² = 0.316, p = 0.001), whereas precipitation had no significant effect. The conservation status shows that almost 76 % of the plant species are in the "Not Evaluated" (NE) category, followed by "Least Concern" (LC; 19 %), "Endangered" (EN; 1.2 %) and "Critically Endangered" (CR; 1%). The floristic exploration data on species richness and diversity of the flora provide valuable baseline data for future studies.