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Species identification and phylogenetic relationship clarification are fundamental goals in species delimitation. However, these tasks pose challenges when based on morphologies, geographic distribution, and genomic data. Previously, two species of the fern genus Bolbitis, B. × multipinna and B. longiaurita were described based on morphological traits; they are phylogenetically intertwined with B. sinensis and fail to form monophyletic groups. To address the unclear phylogenetic relationships within the B. sinensis species complex, RAD sequencing was performed on 65 individuals from five populations. Our integrated analysis of phylogenetic trees, neighbor nets, and genetic structures indicate that the B. sinensis species complex should not be considered as separate species. Moreover, our findings reveal differences in the degree of genetic differentiation among the five populations, ranging from low to moderate, which might be influenced by geographical distance and gene flow. The Fst values also confirmed that genetic differentiation intensifies with increasing geographic distance. Collectively, this study clarifies the complex phylogenetic relationships within the B. sinensis species complex, elucidates the genetic diversity and differentiation across the studied populations, and offers valuable genetic insights that contribute to the broader study of evolutionary relationships and population genetics within the Bolbitis species.

Abstract Tropical cyclones are among the major climatic disasters threatening human survival and development. They are also responsible in part for forest taxonomic composition and dynamics and may lead to catastrophic succession between ecosystems. In this study, we aimed to investigate the extensiveness and severity of the effect caused by Typhoon Hato among the three primary plant communities in Macau, China, including Guia Hill, Taipa Grande, and Ka Ho. The plants' damage was classified into seven categories, ranging from Degree 6, which represents the most severe damage, to Degree 0, which represents almost no damage. The impact of Typhoon Hato was evaluated at different levels, including sample plots, species, DBH, and community structure. Our results show that the sub‐climax community of Guia Hill was most disturbed, with the highest damage index (DI) of 55.28%. Similarly, the Ka Ho shoreline shrub community was also considerably influenced, with a DI of 48.14%. By contrast, the managed secondary forest around Taipa Grande was the least affected, with a DI of 32.66%. Additionally, from the tree layer perspective, the tall trees at Guia Hill canopy layer were directly affected by wind, while the dense understory layer suffered from severe secondary damage due to the fallen trees and branches. For Taipa Grande, the dominant species in the canopy layer were shorter and had less direct damage; the secondary damage was also small as a consequence. Ka Ho had more dwarfed and multibranched species surviving from the sea breeze since Ka Ho was close to the sea. The dense plant structure in Ka Ho protected plants from being easily broken by typhoons, but some twigs and leaves were lost. Some less damaged local species and easily recovered species found in this study could inform the selection of wind‐resistant species for the typhoon‐affected communities.

Bolbitis multipinna is an endemic fern found in Yunnan, China. In the case of the chloroplast genome, Illumina Hiseq X-Ten was used, and it revealed a conserved quadripartite structure of 152,437 bp, including a large single-copy (LSC) region of 82,618 bp, a small single-copy (SSC) region of 21,403 bp, and a pair of inverted repeat regions of 24,208 bp (IRa and IRb). The chloroplast genome of B. multipinna contains 132 genes, including 89 protein-coding genes, 35 tRNA genes, and eight rRNA genes. By using the maximum-likelihood method and the Bayesian analysis on the chloroplast genomes of 15 species ferns, the phylogenetic analysis revealed that B. multipinna is closely related to B. heteroclita.

Salinity adversity has been a major environmental stressor for plant growth and reproduction worldwide. Semi-mangrove Clerodendrum inerme, a naturally salt-tolerant plant, can be studied as a successful example to understand the biological mechanism of saline resistance. Since it is a sophisticated and all-round scale process for plants to react to stress, our greenhouse study interpreted the response of C. inerme to salt challenge in the following aspects: morphology, osmotic protectants, ROS production and scavenging, ion homeostasis, photosynthetic efficiency, and transcriptome reprogramming. The results drew an overview picture to illustrate the tolerant performance of C. inerme from salt acclimatization (till medium NaCl level, 0.3 mol/L) to salinity stress (high NaCl level, 0.5 mol/L). The overall evaluation leads to a conclusion that the main survival strategy of C. inerme is globally reshaping metabolic and ion profiles to adapt to saline adversity. These findings uncover the defense mechanism by which C. inerme moderates its development rate to resist the short- and long-term salt adversity, along with rebalancing the energy allocation between growth and stress tolerance.

While roots and leaves have evolved independently in lycophytes, ferns and seed plants, there is still confusion regarding the morphological evolution of ferns, especially in whisk ferns, which lack true leaves and roots and instead only exhibit leaf-like appendages and absorptive rhizoids. In this study, analyses of comparative transcriptomics on positively selected genes were performed to provide insights into the adaptive evolution of whisk fern morphologies. Significantly clustered gene families specific to whisk ferns were mainly enriched in Gene Ontology (GO) terms “binding proteins” and “transmembrane transporter activity”, and positive selection was detected in genes involved in transmembrane transporter activities and stress response (e.g., sodium/hydrogen exchanger and heat shock proteins), which could be related to the adaptive evolution of tolerance to epiphytic environments. The analysis of TF/TR gene family sizes indicated that some rapidly evolving gene families (e.g., the GRF and the MADS-MIKC families) related to the development of morphological organs were commonly reduced in whisk ferns and ophioglossoid ferns. Furthermore, the WUS homeobox-containing (WOX) gene family and the knotted1-like homeobox (KNOX) gene family, both associated with root and leaf development, were phylogenetically conserved in whisk ferns and ophioglossoid ferns. In general, our results suggested that adaptive evolution to epiphytic environments might have occurred in whisk ferns. We propose that the simplified and reduced leaf and root system in whisk ferns is the result of reduction from the common ancestor of whisk ferns and ophioglossoid ferns, rather than an independent origin.

Plant diversity, habitat properties, and their relationships in karst caves remain poorly understood. We surveyed vascular plant and bryophyte diversities and measured the habitat characteristics in six karst caves in south China with different disturbance histories (one had been disturbed by poultry feeding, three had been disturbed by tourism, and two were undisturbed). The plant diversity differences among the six caves were analyzed using cluster analysis, and the relationships of plant diversity and microhabitat were assessed using canonical correspondence analysis. We found a total of 43 angiosperm species from 27 families, 20 lycophyte and fern species from 9 families, and 20 species of bryophytes from 13 families in the six caves. Habitat characteristics including light intensity, air relative humidity, air temperature, and soil properties varied among the caves. The plant diversity in karst caves was not rich, but the species composition was unique. The caves with high disturbance had the lowest species richness, numbers of individuals, and Shannon-Wiener diversity indices but the highest Simpson’s dominance indices. The caves with less disturbance had the highest numbers of species, numbers of individuals, and Shannon-Wiener diversity indices but the lowest Simpson’s dominance indices. The disturbed caves were often dominated by drought-tolerant, tenacious mosses (bryophytes), while the relatively undisturbed caves contained abundant liverworts (bryophytes), which were better adapted to humid environments. Plant diversity in karst caves was closely related to habitat heterogeneity, light and water status, and nutrient availability. Tourism and poultry farming were associated with the degradation of vegetation in some karst caves. Protecting and restoring bryophytes might facilitate the settlement, growth, and succession of vascular plants in karst caves. Bryophytes can be used as indicators of overall plant diversity and restoration status in karst caves.

In this study, we investigated suitable habitats for the endangered tree fern, Sphaeropteris lepifera (J. Sm. ex Hook.) R.M. Tryon, based on fieldwork, ecological niche modeling, and regression approaches. We combined these data with the characterization of spore germination and gametophytic development in the laboratory to assess the reasons why S. lepifera is endangered and to propose a conservation strategy that focuses on suitable sites for reintroduction and accounts for the ecology and biphasic life cycle of the species. Our methods represent an integration of process- and correlation-based approaches to understanding the distributional patterns of this species, and this combined approach, while uncommonly applied, is a more robust strategy than either approach used in isolation. Our ecological niche models indicated that cold temperature extremes, temperature stability over long- and short-terms, and the seasonality of precipitation were among the most important abiotic environmental factors affecting the distribution of S. lepifera among the variables that we measured. Moreover, distribution of this fern species is also strongly influenced by the timing of development of male and female gametes. Additionally, we observed that slope aspect, specifically south-facing slopes, facilitates more incoming sunlight for mature trees, and simultaneously, provides greater, much-needed shade for fiddleheads on account of the canopy being denser. We believe that our study can provide important guidance on the restoration of S. lepifera in the wild. Specifically, potential restoration areas can be screened for the specific environmental factors that we infer to have a critical impact on the survival of the species.