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Background Eriocaulon is a wetland plant genus with important ecological value, and one of the famous taxonomically challenging groups among angiosperms, mainly due to the high intraspecific diversity and low interspecific variation in the morphological characters of species within this genus. In this study, 22 samples representing 15 Eriocaulon species from China, were sequenced and combined with published samples of Eriocaulon to test the phylogenetic resolution using the complete chloroplast genome. Furthermore, comparative analyses of the chloroplast genomes were performed to investigate the chloroplast genome evolution of Eriocaulon. Results The 22 Eriocaulon chloroplast genomes and the nine published samples were proved highly similar in genome size, gene content, and order. The Eriocaulon chloroplast genomes exhibited typical quadripartite structures with lengths from 150,222 bp to 151,584 bp. Comparative analyses revealed that four mutation hotspot regions (psbK-trnS, trnE-trnT, ndhF-rpl32, and ycf1) could serve as effective molecular markers for further phylogenetic analyses and species identification of Eriocaulon species. Phylogenetic results supported Eriocaulon as a monophyletic group. The identified relationships supported the taxonomic treatment of section Heterochiton and Leucantherae, and the section Heterochiton was the first divergent group. Phylogenetic tree supported Eriocaulon was divided into five clades. The divergence times indicated that all the sections diverged in the later Miocene and most of the extant Eriocaulon species diverged in the Quaternary. The phylogeny and divergence times supported rapid radiation occurred in the evolution history of Eriocaulon. Conclusion Our study mostly supported the taxonomic treatment at the section level for Eriocaulon species in China and demonstrated the power of phylogenetic resolution using whole chloroplast genome sequences. Comparative analyses of the Eriocaulon chloroplast genome developed molecular markers that can help us better identify and understand the evolutionary history of Eriocaulon species in the future.

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Eriocaulon buergerianum Körnicke. (Eriocaulaceae) is one of the most common and least expensive herbal medicines for eye disease. This species is facing potential threats from climate change. Insufficient biogeographic knowledge of this plant species can hinder its effective management for long-term population survival. We integrated ecological niche modelling (Biomod2) with 70 records of E. buergerianum and eight environmental variables to estimate changes in distribution over time. A core area Zonation algorithm was introduced to identify conservation priority areas. Our results indicate that the range of E. buergerianum will likely decrease in the future: the overall range change on average is -44.36 ± 21.56% (-3.70% to -77.73%); values of range loss and range gain are 45.79 ± 20.30% (9.29-78.19%) and 1.43 ± 1.53% (0.18-5.59%), respectively. According to conservation priority analysis, the mandatory reserve (top 5%), negotiable reserve (0.95-0.9) and partial reserve (0.9-0.8) areas are 19,799, 19,799 and 39,597 km , respectively. The areas identified as conservation priority are located in the southeast, especially in northern Taiwan and the Wuyi Mountains. Based on these results, we suggest a re-evaluation of the threatened status of this species, with a potential upgrade to the vulnerable (VU) category. To overcome the adverse conditions faced by populations of E. buergerianum in China, we propose a multi-faceted conservation strategy involving more complete resource assessment, a monitoring system, medical research focused on revealing medicinal components or substitutes, and a regional development plan that considers both wildlife and socio-economic issues.