Buddleja colvilei Hook.f. & Thomson (Scrophulariaceae) is a threatened alpine plant with a distribution throughout the Himalayas, also used as an ornamental plant. The name Buddleja sessilifolia B.S. Sun ex S.Y. Pao was assigned in 1983 to a plant distributed throughout the Gaoligong Mountains, but the name was later placed in synonymy with B. colvilei in the Flora of China. In this study we sequenced the complete chloroplast (cp) genomes of two individuals of B. colvilei and three individuals of B. sessilifolia from across the range. Both molecular and morphological analysis support the revision of B. sessilifolia. The phylogenetic analysis constructed with the whole cp genomes, the large single-copy regions (LSC), small single-copy regions (SSC), inverted repeat (IR) and the nuclear genes 18S/ITS1/5.8S/ITS2/28S all supported B. sessilifolia as a distinct species. Additionally, coalescence-based species delimitation methods (bGMYC, bPTP) using the whole chloroplast datasets also supported B. sessilifolia as a distinct species. The results suggest that the B. sessilifolia lineage was early diverging among the Asian Buddleja species. Overall gene contents were similar and gene arrangements were found to be highly conserved in the two species, however, fixed differences were found between the two species. A total of 474 single nucleotide polymorphisms (SNPs) were identified between the two species. The Principal Coordinate Analysis of the morphological characters resolved two groups and supported B. sessilifolia as a distinct species. Discrimination of B. colvilei and B. sessilifolia using morphological characters and the redescription of B. sessilifolia are detailed here.

Species of the genus Buddleja in Asia are mainly distributed in the Sino-Himalayan region and form a challenging taxonomic group, with extensive hybridization and polyploidization. A phylogenetic approach to unravelling the history of reticulation in this lineage will deepen our understanding of the speciation in biodiversity hotspots. For this study, we obtained 80 accessions representing all the species in the Asian Buddleja clade, and the ploidy level of each taxon was determined by flow cytometry analyses. Whole plastid genomes, nuclear ribosomal DNA, single nucleotide polymorphisms and a large number of low-copy nuclear genes assembled from genome skimming data were used to investigate the reticulate evolutionary history of Asian Buddleja. Complex cytonuclear conflicts were detected through a comparison of plastid and species trees. Gene tree incongruence was also analysed to detect any reticulate events in the history of this lineage. Six hybridization events were detected, which are able to explain the cytonuclear conflict in Asian Buddleja. Furthermore, PhyloNet analysis combining species ploidy data indicated several allopolyploid speciation events. A strongly supported species tree inferred from a large number of low-copy nuclear genes not only corrected some earlier misinterpretations, but also indicated that there are many Asian Buddleja species that have been lumped mistakenly. Divergent time estimation shows two periods of rapid diversification (8–10 and 0–3 Mya) in the Asian Buddleja clade, which might coincide with the final uplift of the Hengduan Mountains and Quaternary climate fluctuations, respectively. This study presents a well-supported phylogenetic backbone for the Asian Buddleja species, elucidates their complex and reticulate evolutionary history and suggests that tectonic activity, climate fluctuations, polyploidization and hybridization together promoted the diversification of this lineage.

Societal Impact Statement: Globalization and rapid shifts in culture and economy threaten indigenous and local knowledge (ILK) systems, and large intergenerational gaps in this knowledge already exist. Buddleja asiatica is a deciduous shrub or small tree with traditional medicinal applications but is currently largely overlooked as a medicinal resource. This study investigates the traditional uses of B. asiatica in indigenous communities in the Pan‐Himalayan region through ethnobotanical field surveys, with a view to preserving cultural heritage and strengthening economic resilience in these communities, as well as developing B. asiatica as a medicinal resource. Prioritizing the well‐being of mountain communities, this study aims to bridge community development with nature.Summary: Buddleja asiatica Lour. (Scrophulariaceae) is widely distributed across the Pan‐Himalayan region. It has traditional medicinal applications and cultural value, as well as ecological significance. We conducted an ethnobotanical study combining field surveys from Nepal and Xizang, China with a literature review using Web of Science (WoS) to review the ethnobotanical, phytochemical, and pharmacological aspects of this species. Our study highlights the cultural significance of B. asiatica within indigenous communities and, in particular, the use of the leaves to make a starter culture for the preparation of wine. However, an evident intergenerational gap in knowledge transfer exists. The phytochemical investigation revealed the presence of various chemical classes (carbohydrates, terpenoids, flavonoids, saponins, esters, steroids, glycosides, and fatty acids), of which 15 phytoconstituents were first reported from various parts of B. asiatica. The potential medicinal properties of these chemicals include anti‐inflammatory, antioxidant, cytotoxic, antihepatotoxic, antimicrobial, and cholinesterase activities. We combine these lines of evidence to show the prospects for the livelihoods of local people across this region and propose future research directions.

The global burden of cancer, with over 19 million new cases annually, underscores the urgent need for effective therapies. Among the most promising anticancer compounds is camptothecin (CPT), a monoterpene alkaloid predominantly derived from Nothapodytes species. Despite its significant pharmaceutical value, the exploitation of such Threatened Plant Species with Widespread Distribution (TPSWD), particularly driven by the global demand for natural compounds in anticancer therapies, presents a paradox in which their widespread distribution fails to ensure their secure conservation status. Furthermore, the lack of in-depth biogeographic and systematic studies complicates efforts to balance resource utilization with biodiversity preservation. The asymmetric distribution of CPT within plant taxa, along with limited knowledge of its biosynthetic pathways and the enzymes and genes involved, further hampers sustainable production. Here, we review the current knowledge on the production and protection of Nothapodytes, focusing on their plant resources, active ingredients, and natural drug derivatives. We also explore strategies for rescuing and sustainably utilizing Nothapodytes, including biotechnological advancements and integrated conservation practices. Finally, we propose future directions to address conservation challenges, ensuring a sustainable supply of CPT while safeguarding these TPSWD species.