Premise: Molecular datasets for estimating phylogenetic trees increasingly include more species and gene regions. Often trees are constructed using backbone phylogenies, subtrees, and other techniques to address the challenges of large dataset size. Currently, there is no established approach to integrate these rapidly expanding datasets. Methods: We generated a phylogenetic tree (and 1,000 bootstrap trees) with divergence times that span euphyllophytes. To do this, we integrated taxonomically broad dated backbone phylogenies with species-level trees generated from phylogenetic analysis of individual clades. Datasets for species-level trees were assembled using PyPHLAWD. Results: The resulting dated phylogenetic tree includes: 121,641 angiosperm species; 1,026 gymnosperms; and 5,603 ferns. This is the largest euphyllophyte phylogenetic tree constructed to date. Topological uncertainty spikes at the start of the Cretaceous and gradually increases during the Cenozoic. Uncertainty in age estimates gradually increases in the Cenozoic but increases dramatically in the most recent 5 Myrs. Discussion: This dated phylogenetic framework can underpin evolutionary studies spanning euphyllophytes, and enable the integration of insights from the recent to the distant past. Our approach also enables the tree to be easily updated in the future to reflect future increases in data availability, and systematic and taxonomic advances within specific clades. ### Competing Interest Statement The authors have declared no competing interest. NSF, DEB 2325835

Chrysalidocarpus is the second-largest genus in Arecaceae subtribe Dypsidinae, comprising 60 species distributed across Madagascar, the Comoro Archipelago, and Pemba Island. Since 2022, five new species have been described from cultivation and here we describe and illustrate two more new species, C. comptus and C. marcusorum, based on specimens cultivated in Hawai’i.

Unclear species boundaries are a common challenge in ecological studies and species inventories, obscuring patterns of biodiversity and complicating inferences about ecological and evolutionary processes. One possible cause of fuzziness is hybridisation, but little information exists on hybridisation in the tropics. Here we aim to address the question of potential hybridisation in the tropical American fern genus Trichomanes (Hymenophyllaceae) and to clarify evolutionary relationships within the genus. We take advantage of nuclear target-capture sequencing, haplotype phasing and off-target plastid reads to detect phylogenetic relationships and reticulate histories. We sampled 303 individuals that represent 41 known Trichomanes species. Our analyses recovered a robust backbone for the genus, strongly supporting subgenus Trichomanes as sister to subgen. Feea, and subgen. Davalliopsis as sister to subgen. Lacostea. Trichomanes pinnatum proved to be a complex where six different unnamed morphs represent four different kinds of evolutionary history. Two morphs appear to be stabilised, relatively old hybrid-derived species, one represents a recent hybrid, one reflects repeated spontaneous hybridisation between the same parent species, and one represents within-species morphological variation without any obvious genomic signal. Excluding the four hybrids makes T. pinnatum s.s. morphologically and genetically much more uniform, but its geographic distribution still covers practically all tropical America, indicating that the species may be approaching panmixia.

Tropical rainforests are home to almost half of plant diversity, yet a shortfall in phylogenetic hypotheses for tropical plants hinders our understanding of how rainforests have formed and adapted to past global changes. Phylogenetic and historical biogeographic evidence from key rainforest lineages, such as palms (Arecaceae), are required to illuminate the history of these ecosystems. However, our current understanding of the palm tree of life is based on uneven sampling of plastid and nuclear data. Moreover, numerous palm genera and palm fossils have been described or revised over the past decade, casting doubt on palm relationships, ages and ancestral ranges inferred in early studies. Here, we infer the phylogenetic relationships of all 184 palm genera based on data from 1,033 nuclear genes generated using target sequence capture. Our palm phylogenomic tree is highly resolved and supported. Remaining areas of ambiguity reflect the complex dynamics of palm evolution, including rapid diversification events in subfamily Arecoideae and putative cases of ancient reticulation throughout the family. We undertake a comprehensive review of the palm fossil record and use a vetted selection of fossils to estimate divergence times with two Bayesian methods, the first based on calibration of five nodes using the age of fossils assigned to them, and the second based on co-estimation of divergence times and phylogenetic placements of 113 fossils with a Fossilized Birth-Death model. We then use the distribution ranges of extant and fossil taxa to infer ancestral ranges. We show that the palm family first diversified in the Early Cretaceous in regions corresponding to what is now North, Central and South America and Oceania, that many tribes and subtribes had originated by the Late Cretaceous, and that two thirds of the genera had diverged by the Oligocene. Fossil-informed analyses provide a more complex picture of the early biogeography of palms than analyses relying only on the ranges of extant taxa. Despite uncertainties regarding fossil placement, it is clear that palms dispersed dozens of times across oceanic gaps, and that dispersal and extirpation patterns are consistent with an ancient affinity of palms for megathermal climates. Our dated phylogenomic trees and curated fossil dataset provide a new foundation for evolutionary studies on palms, opening the door to deeper research on the rainforest biome in which they thrive.

The palm family (Arecaceae) has a rich history of phylogenetic research, including several recent phylogenomic studies. However, densely sampled phylogenomic datasets for larger palm clades – such as subfamilies – are still few in number. We used target sequence capture to obtain data for 971 nuclear genes across 421 (ca. 80%) species in the subfamily Coryphoideae. We inferred a robust phylogenetic tree to address systematic issues in the subfamily, specifically the relationships among tribes Cryosophileae, Sabaleae, Phoeniceae and Trachycarpeae, the affinities of seven genera in Trachycarpeae that are not currently assigned to any subtribe, and the monophyly of genera across the subfamily. We recovered relationships among tribes that are in accordance with other major nuclear phylogenomic datasets, but that are incongruent with trees derived from plastome sequences. Importantly, the placement of tribe Phoeniceae (the date palms) remains contentious. Our tree recovered with high support the relationship of all unplaced Trachycarpeae genera, paving the way for an updated classification. Most genera were resolved as monophyletic except for Livistona and all three genera of tribe Caryoteae, calling for a revision of generic limits. Our tree clarifies the relationships of many fan palm species for the first time, allowing for future studies of diversification, trait evolution or biogeography.

Understanding how the remarkable biodiversity of the American tropics developed has been a long-standing question, yet knowledge gaps remain. Previous studies examined the roles of bioregions in shaping diversity patterns but often overlooked speciation, a critical driver of species richness, and insufficiently accounted for temporal changes in speciation and dispersal dynamics. To address this, we investigated the temporal mechanisms of speciation and dispersal that have shaped diversity in the American tropics using ferns (Polypodiopsida) as a model group across nine bioregions. We employed biogeographic stochastic mapping (BSM) and a large-scale phylogenetic tree alongside extensive occurrence records to infer historical patterns of speciation and dispersal. We find that the American tropics function as a biogeographical maze composed of interconnected corridors, characterised by high emigration and immigration rates, rather than isolated regions. The Andes emerged prominently as a biodiversity radiator, playing a dual role by generating substantial species richness through speciation and acting as a primary source of dispersal to neighbouring regions. This unique position underscores the Andes' pivotal role in structuring fern diversity across the American tropics, contrasting with the Amazonian-centred patterns typically observed in angiosperms. Our findings highlight the critical importance of considering speciation and historical contexts in relation to changing environments when interpreting patterns of tropical biodiversity.

Plants are prone to genome duplications and tend to preserve multiple gene copies. This is also the case for the genes encoding the Sm proteins of Arabidopsis thaliana (L). The Sm proteins are best known for their roles in RNA processing such as pre-mRNA splicing and nonsense-mediated mRNA decay. In this study, we have taken a closer look at the phylogeny and differential regulation of the SmE-coding genes found in A. thaliana, PCP/SmE1, best known for its cold-sensitive phenotype, and its paralog, PCPL/SmE2. The phylogeny of the PCP homologs in the green lineage shows that SmE duplications happened multiple times independently in different plant clades and that the duplication that gave rise to PCP and PCPL occurred only in the Brassicaceae family. Our analysis revealed that A. thaliana PCP and PCPL proteins, which only differ in two amino acids, exhibit a very high level of functional conservation and can perform the same function in the cell. However, our results indicate that PCP is the prevailing copy of the two SmE genes in A. thaliana as it is more highly expressed and that the main difference between PCP and PCPL resides in their transcriptional regulation, which is strongly linked to intronic sequences. Our results provide insight into the complex mechanisms that underlie the differentiation of the paralogous gene expression as an adaptation to stress.

The genus Maesa in New Guinea is revised. Thirty-nine species are accepted in this study and a key to species (including incompletely known taxa) is presented; four new species, M. begoniifolia, M. pilosopapuana, M. serratifolia, and M. tagulensis are described, and a neotype is selected for the widespread Indonesian species M. tetrandra. Distribution, habitat, phenology and detailed taxonomic notes are provided, and the conservation status of each species is estimated based on IUCN criteria.

Distributed across two continents and thousands of islands, the Asian tropics are among the most species-rich areas on Earth. The origins of this diversity, however, remain poorly understood. Here, we reveal and classify contributions of individual tropical Asian regions to their overall diversity by leveraging species-level phylogenomic data and new fossils from the most species-rich Asian palm lineage, the rattans and relatives (Arecaceae, Calamoideae). Radiators (Borneo) generate and distribute diversity, incubators (Indochina, New Guinea, and Sulawesi) produce diversity in isolation, corridors (Java, Maluku, Sumatra, and the Thai-Malay Peninsula) connect neighboring regions, and accumulators (Australia, India, Palawan, and the Philippines) acquire diversity generated elsewhere. These contrasting contributions can be explained by differences in region size and isolation, elucidating how the unique island-dominated geography of the Asian tropics drives their outstanding biodiversity.

Tropical rainforests are home to almost half of all known plant diversity, yet a shortfall in tropical plant phylogenetic hypotheses is hindering our understanding of how rainforests have formed and adapted to past global changes. Phylogenetic and historical biogeographic evidence from key rainforest lineages, including palms (Arecaceae), are required to illuminate the history of these ecosystems. However, our current understanding of the palm tree of life is based on uneven sampling of data from the plastid and nuclear genome, and numerous palm genera and palm fossils have been described or revised over the past decade, casting doubt on many palm relationships, ages and ancestral ranges inferred in previous studies. Here, we infer the phylogenetic relationships of all palm genera based on data from 1,033 nuclear genes generated using target sequence capture. Our palm tree of life is highly resolved and supported. Remaining areas of ambiguity reflect the complex dynamics of palm evolution, including many rapid diversification events in subfamily Arecoideae and putative cases of ancient reticulation throughout the family. We review the phylogenetic placement and age of hundreds of palm fossils and use a vetted selection to estimate divergence times and ancestral ranges for all palm genera. We show that the family is older than previously thought, likely first diversifying in the Early Cretaceous in Laurasia, and that three quarters of the genera had originated by the Oligocene. The early spread of palms across the world involved at least 40 long-distance dispersals across oceanic gaps. Dispersals away from northern latitudes vastly outnumber dispersals into these latitudes, consistent with the ancient affinity of palms for megathermal climates, and suggesting that global cooling during the Oligocene was a major constraint on early palm distribution. Our dated phylogenomic tree and curated fossil dataset provide a new foundation for evolutionary studies on palms, opening the door to deeper research on the rainforest biome in which they thrive. ### Competing Interest Statement The authors have declared no competing interest.

Mountains are among the most biodiverse places on Earth, and plant lineages that inhabit them have some of the highest speciation rates ever recorded. Plant diversity within the alpine zone - the elevation above which trees cannot grow—contributes significantly to overall diversity within mountain systems, but the origins of alpine plant diversity are poorly understood. Here, we quantify the processes that generate alpine plant diversity and their changing dynamics through time in Saxifraga (Saxifragaceae), an angiosperm genus that occurs predominantly in mountain systems. We present a time-calibrated molecular phylogenetic tree for the genus that is inferred from 329 low-copy nuclear loci and incorporates 73% (407) of known species. We show that upslope biome shifts into the alpine zone are considerably more prevalent than dispersal of alpine specialists between regions, and that the rate of upslope biome shifts increased markedly in the last 5 Myr, a timeframe concordant with a cooling and fluctuating climate that is likely to have increased the extent of the alpine zone. Furthermore, alpine zone specialists have lower speciation rates than generalists that occur inside and outside the alpine zone, and major speciation rate increases within Saxifraga significantly pre-date increased rates of upslope biome shifts. Specialisation to the alpine zone is not therefore associated with speciation rate increases. Taken together, this study presents a quantified and broad scale perspective of processes underpinning alpine plant diversity.

Abstract Imbalance in species richness among related clades is a pervasive, yet incompletely understood feature of biodiversity. Comparison of species-poor and species-rich clades that have evolved within the same region can shed light on the mechanisms underlying this phenomenon. The long-isolated island of Madagascar is an ideal place for doing this. Madagascar harbours at least ten clades of palms (Arecaceae) that have colonized the island independently and diversified to widely differing degrees, ranging from one to 180 known species. We estimated colonization times and diversification rates for these clades based on an extensive phylogenomic dataset and tested the degree to which clades that arrived in Madagascar earlier have more species (time-for-speciation effect), finding a moderate effect. For context, we tested for time-for-speciation effects in other plant and animal lineages, finding variable but qualitatively similar results. Our findings suggest that variation in diversification rate (i.e. speciation and/or extinction rate) is a major driver of species richness imbalance among Malagasy clades, both in palms and elsewhere. We demonstrate that in palms, differences in diversification rates originated long before colonization of the island, suggesting a minor role of classical ‘island radiation’ and a stronger role of heritable traits driving diversification rate. Ability to colonize new climates also appears to play a role. Future work should address the interplay between the dynamic environment of Madagascar and the inherited traits of colonizing lineages to fully explain the island’s intriguing mix of species-poor and species-rich clades.

Seed dispersal is a key process in the generation and maintenance of genetic diversity and genetic differentiation of plant populations in tropical ecosystems. During the Last Quaternary, most seed-dispersing megafauna was lost globally, but whether this has caused dispersal limitation, loss of genetic diversity, and increased genetic differentiation between plant populations with large, ‘megafaunal’ fruits (i.e., > 4 cm - megafruits) remains unclear. Here, we assessed whether megafrugivore extinctions in Madagascar (e.g., giant lemurs, elephant birds) have affected the genetic diversity and genetic differentiation of four animal-dispersed Malagasy palm (Arecaceae) species with large ( Borassus madagascariensis ), medium-sized ( Hyphaene coriacea, Bismarckia nobilis ), and small ( Chrysalidocarpus madagascariensis ) fruits. We integrated double-digest restriction-site-associated DNA sequencing (ddRAD) of 167 individuals from 25 populations with (past) distribution ranges for extinct and extant seed-dispersing animal species, climate and human impact data, and applied linear mixed-effects models to explore the drivers of variation in genetic diversity and genetic differentiation across Malagasy palm populations. We detected higher genetic diversity in species with megafruits than in the species with small fruits, and genetic differentiation was lowest for the human-used medium-sized megafruit species. Furthermore, we found that a higher number of shared extinct megafrugivore species between palm population pairs was associated with less genetic differentiation, indicating higher gene flow, whereas no relationship with extant frugivores – that are not able to swallow and disperse the seeds – was found. Finally, genetic diversity decreased with road density, whereas genetic differentiation decreased with increasing human population density, but only for populations with megafruits. Our results suggest that the legacy of megafrugivores regularly achieving long dispersal distances is still reflected in the genetic diversity and genetic differentiation of palms that were formerly dispersed by such large animals. Furthermore, high genetic diversity and low genetic differentiation were possibly maintained after the megafauna extinctions through human-mediated dispersal, long generation times, and long lifespans of these palms. Our study illustrates how integrating genetics with ecological data on species interactions, climate, and human impact, provides novel insights into the consequences of megafauna extinctions for plants with megafruits.

Societal Impact StatementBiological samples and their associated information are an essential resource used by scientists, governments, policymakers, practitioners and communities to ensure that biodiversity can be appropriately protected and sustainably used. Yet, considering the enormous task of documenting the vast numbers of as‐yet‐unknown plant and fungal species, greater international coordination for biological collecting and recording is necessary, built on equitable collecting practices and standards. Here, we propose five commitments to accelerate and enhance scientific knowledge of plant and fungal diversity, while increasing collaboration, benefit sharing and efficiency.SummaryAlmost all life depends on plants and fungi, making knowledge of their diversity and distribution—primarily derived from biological collections—fundamental to national and international conservation, restoration and sustainable use commitments. However, it is estimated that some 15% of all plant species and over 90% of all fungal species have not yet been scientifically described, hampering our ability to assess and demonstrate the impact of efforts to halt biodiversity loss. In addition, organisations and researchers around the world lack a concerted strategy for increasing complementarity and avoiding overlap in botanical and mycological research, particularly in relation to the collection of specimens. We here present the 2030 Declaration on Scientific Plant and Fungal Collecting, summarising a commitment towards such a necessary strategy. Its components were identified from discussions during and after a series of four workshops and plenary discussions at the 2023 State of the World's Plants and Fungi symposium convened by the Royal Botanic Gardens, Kew, and were then consolidated into the present form by the authors. The Declaration was subsequently opened up for endorsement by signatories. Collectively, we agree on a set of five commitments for cataloguing the world's flora and funga, designed to maximise efficiency, facilitate knowledge exchange and promote equitable collaborations: (1) use evidence‐based collection strategies; (2) strengthen local capacity; (3) collaborate across taxa and disciplines; (4) collect for the future; and (5) share the benefits. This Declaration is a first step towards increased global and regional coordination of scientific collecting efforts.

Angiosperms are the cornerstone of most terrestrial ecosystems and human livelihoods(1,2). A robust understanding of angiosperm evolution is required to explain their rise to ecological dominance. So far, the angiosperm tree of life has been determined primarily by means of analyses of the plastid genome(3,4). Many studies have drawn on this foundational work, such as classification and first insights into angiosperm diversification since their Mesozoic origins(5-7). However, the limited and biased sampling of both taxa and genomes undermines confidence in the tree and its implications. Here, we build the tree of life for almost 8,000 (about 60%) angiosperm genera using a standardized set of 353 nuclear genes(8). This 15-fold increase in genus-level sampling relative to comparable nuclear studies(9) provides a critical test of earlier results and brings notable change to key groups, especially in rosids, while substantiating many previously predicted relationships. Scaling this tree to time using 200 fossils, we discovered that early angiosperm evolution was characterized by high gene tree conflict and explosive diversification, giving rise to more than 80% of extant angiosperm orders. Steady diversification ensued through the remaining Mesozoic Era until rates resurged in the Cenozoic Era, concurrent with decreasing global temperatures and tightly linked with gene tree conflict. Taken together, our extensive sampling combined with advanced phylogenomic methods shows the deep history and full complexity in the evolution of a megadiverse clade.

Seed dispersal affects gene flow and hence genetic differentiation of plant populations. During the Late Quaternary, most fruit-eating and seed-dispersing megafauna went extinct, but whether these animals have left signatures in the population genetics of their food plants, particularly those with large, 'megafaunal' fruits (i.e. >4 cm-megafruits), remains unclear. Here, we assessed the population history, genetic differentiation and recent migration among populations of four animal-dispersed palm (Arecaceae) species with large (Borassus madagascariensis), medium-sized (Hyphaene coriacea, Bismarckia nobilis) and small (Chrysalidocarpus madagascariensis) fruits on Madagascar. We integrated double-digest restriction-site-associated DNA sequencing (ddRAD) of 167 individuals from 25 populations with (past) distribution ranges for extinct (e.g., giant lemurs and elephant birds) and extant seed-dispersing animals, landscape and human impact data, and applied linear mixed-effects models to explore the drivers of genetic variation in Malagasy palms. Palm populations that shared more megafrugivore species in the past had lower genetic differentiation than populations that shared fewer megafrugivore species. This suggests that megafrugivore-mediated seed dispersal in the past may have led to frequent gene flow among populations. In comparison, extant frugivore diversity only decreased genetic differentiation in the small-fruited palm. Furthermore, genetic differentiation of all palm species decreased with landscape connectivity (i.e. environmental suitability, forest cover and river density) and human impact (i.e. road density), while migration rates of the small-fruit palm increased with road density. Synthesis. Our results suggest that the legacy of megafrugivores regularly achieving long dispersal distances is still reflected in the population genetics of palms that were formerly dispersed by such animals. Furthermore, low genetic differentiation was possibly maintained after the megafauna extinctions through alternative dispersal (e.g. human- or river-mediated), long generation times and long lifespans of these megafruit palms. Our study illustrates how species interactions that happened >1000 years ago can leave imprints in their population genetics.

The systematization of Maesa, a genus of almost 200 species, has haunted taxonomists for more than a century due to its lack of distinct qualitative characters or discontinuities in quantitative characters for species delimitation. The clarification of phylogenetic relationships in such a problematic genus like Maesa is essential to aid infrageneric classification and species delimitation. Here, a species-level phylogenetic tree of Maesa is reconstructed. Leaf materials were sampled mainly from herbarium specimens which cover 60% of the species across the entire distribution range of the genus. Targeted sequence capture with the Angiosperms353 probe set was used to acquire sequences for downstream bioinformatic analyses. We obtained a species tree inferred from 310 gene trees that divides Maesa into an African clade and an Asian-Pacific clade. The African clade is further divided into two subclades, while the Asian-Pacific clade is divided into three subclades; all subclades are well supported. Hence, we propose five subgenera of Maesa, namely M. subg. Maesa, subg. Indicae, subg. Monotaxis, subg. Papuanae and subg. Ramentaceae. In addition, we scrutinize some species complexes within the genus; however, with the lack of phylogenetic signal at shallow levels, we are unable to conclusively resolve all species boundaries in these complexes. This study provides the phylogenomic framework to untangle taxonomic problems in the genus Maesa and lays the foundation for further detailed studies in biogeography, trait evolution and population genetics.

Across the globe, tree species are under high anthropogenic pressure. Risks of extinction are notably more severe for species with restricted ranges and distinct evolutionary histories. Here, we use a global dataset covering 41,835 species (65.1% of known tree species) to assess the spatial pattern of tree species’ phylogenetic endemism, its macroecological drivers, and how future pressures may affect the conservation status of the identified hotspots. We found that low-to-mid latitudes host most endemism hotspots, with current climate being the strongest driver, and climatic stability across thousands to millions of years back in time as a major co-determinant. These hotspots are mostly located outside of protected areas and face relatively high land-use change and future climate change pressure. Our study highlights the risk from climate change for tree diversity and the necessity to strengthen conservation and restoration actions in global hotspots of phylogenetic endemism for trees to avoid major future losses of tree diversity.

A genus and species of palm from the Truong Son Range in Vietnam, Truongsonia lecongkietii, is described as new to science. Phylogenomic analysis strongly supports the placement of the new taxon in subfamily Arecoideae as sister to the African endemic tribe Podococceae, which comprises a single genus Podococcus. A new tribe Truongsonieae is also described to accommodate Truongsonia in the current phylogenetic classification of palms. Truongsonia is a dwarf, acaulescent, clump-forming palm bearing entire, bifid leaves with a fibre-like extension of the rachis through the sinus of the two lobes of the leaf. The interfoliar inflorescence is exserted on a long peduncle with 3­–4 tightly sheathing peduncular bracts and rachillae presented at the apex only. The ovary is triovulate-tricarpellate, but fruits are single-seeded. Truongsonia is Critically Endangered, with surveys locating only 10–15 plants in the wild. Swift conservation action is required to secure the future of this remarkable and phylogenetically isolated lineage of palms.

Societal Impact Statement Plants are fundamental to terrestrial and aquatic ecosystems and are key to human livelihoods. To protect plant diversity, systematic approaches to conservation assessment are needed. Many nations have legislation or other policy instruments that seek to protect biodiversity (including plants), and species‐level assessments are essential for identifying the most threatened species that require special and immediate protection measures. Some plants occur in only one place (for instance, a single country) and here we have estimated how many of these ‘endemic’ species have had their threats assessed in each country or close country‐equivalent worldwide. We show that the level of assessment completion is only weakly related to the income of countries or the likely level of threat that species face. Summary The Global Strategy for Plant Conservation ambitiously called for an assessment of the conservation status of all recognised plant taxa by 2020. This target was not met in the short term. Nevertheless, the need for conservation assessments remains urgent as plants go extinct and face increasing threats from human impacts on the biosphere. Here, the completeness of threat assessments for endemic flora in 179 countries or their close equivalents was assessed. To do so, distribution information from the World Checklist of Vascular Plants was combined with assessments collated in the ThreatSearch database. The completeness of assessments was expected to be associated with the objective affluence of countries (measured using inequality‐adjusted Human Development Index (IHDI)) and/or the exposure of their plant species to threats associated with human impacts (measured using Global Human Modification index (GHM)). The number of endemic species per country was also hypothesised to influence the completion of assessments. Overall, 58% of all country‐based endemic species examined have no conservation assessment (127,643 species). Countries' progress toward the completion of threat assessments for endemic plants could not be confidently predicted by IHDI, GHM or the richness of endemic plant flora. The shortfall in threat assessments identified here restricts national regulation of actions which imperil plant species, with particular consequences for endemic plant species subject to local laws. Some nations with high IHDI scores (i.e. wealthier nations) are not systematically assessing extinction risk in their endemic species. Scarce funding should be directed to global hotspots of endemism with few available resources for assessment.