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Eudicots and their currently recognized major subclades are characterized as to floral structure (including some \"embryological\" features) based on ca. 3000 original publications. A new classification of nucelli is presented. In particular, the distinction between tenuinucellar and incompletely tenuinucellar ovules has proven to be useful for the characterization of larger subclades. Tenuinucellar ovules characterize Gentianales, and largely Lamíales of lamiids, and Asteraceae of campanulids, thus all of the most diversified subclades of asterids. In contrast, incompletely tenuinucellar ovules are present in basal asterids and the less diversified subclades of lamiids and campanulids. Interestingly, Santalales and Caryophyllales, which have been tentatively classified in the asterid lineage s.l, have relatively thin nucelli. Also, the presence of endosperm haustoria or the particular differentiation of the embryo suspensor characterizes some larger subclades such as Fabales and Lamíales or core Saxifragales, respectively. The expanded malvids (with inclusion of Crossosomatales, Geraniales, and Myrtales) are supported by floral features. For several features that are potential key innovations, because they characterize strongly diversified clades (e.g., pentamerous flowers in core eudicots or monosymmetric flowers in Lamíales), it is shown that they are also sporadically present in species-poor clades more to the base of the phylogenetic tree. This indicates that what appear as key innovations in certain groups may be present in latent form long before their manifestation as a key innovation. Thus, it is possible that such key innovations are not always apomorphies in a strict sense (e.g., monosymmetric flowers). This conforms with results of evo-devo research, in which genetic structures connected with floral features were found in clades in which the floral features are not present.

Background Eudicots are the most diverse group of flowering plants that compromise five well-defined lineages: core eudicots, Ranunculales, Proteales, Trochodendrales, and Buxales. However, the phylogenetic relationships between these five lineages and their chromosomal evolutions remain unclear, and a lack of high-quality genome analyses for Buxales has hindered many efforts to address this knowledge gap. Results Here, we present a high-quality chromosome-level genome of Buxus austro-yunnanensis (Buxales). Our phylogenomic analyses revealed that Buxales and Trochodendrales are genetically similar and classified as sisters. Additionally, both are sisters to the core eudicots, while Ranunculales was found to be the first lineage to diverge from these groups. Incomplete lineage sorting and hybridization were identified as the main contributors to phylogenetic discordance (34.33%) between the lineages. In fact, B. austro-yunnanensis underwent only one whole-genome duplication event, and collinear gene phylogeny analyses suggested that separate independent polyploidizations occurred in the five eudicot lineages. Using representative genomes from these five lineages, we reconstructed the ancestral eudicot karyotype (AEK) and generated a nearly gapless karyotype projection for each eudicot species. Within core eudicots, we recovered one common chromosome fusion event in asterids and malvids, respectively. Further, we also found that the previously reported fused AEKs in Aquilegia (Ranunculales) and Vitis (core eudicots) have different fusion positions, which indicates that these two species have different karyotype evolution histories. Conclusions Based on our phylogenomic and karyotype evolution analyses, we revealed the likely relationships and evolutionary histories of early eudicots. Ultimately, our study expands genomic resources for early-diverging eudicots.

Although fine roots are important components of the global carbon cycle, there is limited understanding of root structure-function relationships among species. We determined whether root respiration rate and decomposability, two key processes driving carbon cycling but always studied separately, varied with root morphological and chemical traits, in a coordinated way that would demonstrate the existence of a root economics spectrum (RES). Twelve traits were measured on fine roots (diameter 2mm) of 74 species (31 graminoids and 43 herbaceous and dwarf shrub eudicots) collected in three biomes. The findings of this study support the existence of a RES representing an axis of trait variation in which root respiration was positively correlated to nitrogen concentration and specific root length and negatively correlated to the root dry matter content, lignin:nitrogen ratio and the remaining mass after decomposition. This pattern of traits was highly consistent within graminoids but less consistent within eudicots, as a result of an uncoupling between decomposability and morphology, and of heterogeneity of individual roots of eudicots within the fine-root pool. The positive relationship found between root respiration and decomposability is essential for a better understanding of vegetation-soil feedbacks and for improving terrestrial biosphere models predicting the consequences of plant community changes for carbon cycling.

Z.C.Lu & W.B.Xu, a new species of Salicaceae was discovered from limestone areas of Guangxi, China. The morphology of is similar to , but differs by its evergreen nature; shorter petioles, only 3-8 mm long, and tomentose or glabrous when old; elliptic leaf blade with cuneate base; shorter inflorescence (1.8-4.5 cm long); smaller flowers; and smaller capsules (1.7-2.7 cm long, 5-9 mm in diam.).

Herbarium collections and the data they hold are the main sources of plant biodiversity information. These collections contain taxonomical and spatial data on living and extinct species; consequently, they are the fundamental basis for temporal and spatial biogeographical studies of plants. Mega projects focused on providing digital and free access to accurate biodiversity data have transformed plant science research, mainly in the past two decades. In this sense, researchers today are overwhelmed by the many different datasets in online repositories. There are also several challenges involved in using these data for biogeographical analyses. Analyses performed on the data available in the repositories show that 70-75% of the total amount of data have spatial deficiencies and a high number of records lack coordinates. This shortage of reliable primary biogeographical information creates serious impediments for biogeographical analyses and conservation assessments and taxonomic revisions consequently produces obstacles for evaluations of threats to biodiversity at global, regional and local levels. With the aim of contributing to botanical and biogeographical research, this paper provides georeferenced spatial data for angiosperm species endemic to Brazil. The information from two reliable online databases, i.e. the Flora do Brasil 2020 floristic database (BFG) and Plantas do Brasil: Resgate Histórico e Herbário Virtual para o Conhecimento e Conservação da Flora Brasileira (REFLORA), which are both based on records collected over the course of the last two centuries, is used to create this spatial dataset. We provide three taxonomically-edited and georeferenced datasets for basal angiosperms, monocots and eudicots, covering a total of 14,992 endemic species from Brazil. Producing this consolidated dataset involved several months of detailed revision of coordinates and nomenclaturally updating of the names in these datasets. The information provided in this geo-referenced dataset, covering two centuries of specimen collections, will contribute to several botanical and mainly biogeographical studies.

Explosive diversification is widespread in eukaryotes, making it difficult to resolve phylogenetic relationships. Eudicots contain c. 75% of extant flowering plants, are important for human livelihood and terrestrial ecosystems, and have probably experienced explosive diversifications. The eudicot phylogenetic relationships, especially among those of the Pentapetalae, remain unresolved. Here, we present a highly supported eudicot phylogeny and diversification rate shifts using 31 newly generated transcriptomes and 88 other datasets covering 70% of eudicot orders. A highly supported eudicot phylogeny divided Pentapetalae into two groups: one with rosids, Saxifragales, Vitales and Santalales; the other containing asterids, Caryophyllales and Dilleniaceae, with uncertainty for Berberidopsidales. Molecular clock analysis estimated that crown eudicots originated c. 146 Ma, considerably earlier than earliest tricolpate pollen fossils and most other molecular clock estimates, and Pentapetalae sequentially diverged into eight major lineages within c. 15 Myr. Two identified increases of diversification rate are located in the stems leading to Pentapetalae and asterids, and lagged behind the gamma hexaploidization. The nuclear genes from newly generated transcriptomes revealed a well-resolved eudicot phylogeny, sequential separation of major core eudicot lineages and temporal mode of diversifications, providing new insights into the evolutionary trend of morphologies and contributions to the diversification of eudicots.

C.An & G.C.Lin, a newly-defined species within the family Rosaceae from Fujian Province, China, is formally described and illustrated here. is morphologically similar to , but can be distinguished by several key characteristics, such as long, reddish-purple stipitate glands, soft bristles, light yellow short trichomes (vs. shortly grey tomentose at the early stage, glabrescent) and scattered epidermal prickles (vs. few to many curved prickles). Furthermore, the stipules are pinnately deeply laciniate, measuring 1-1.5 cm (vs. ovate-oblong to ovate-lanceolate, 0.5-0.8 cm). Phylogenetic analyses, based on partial sequences and the complete plastome data, provide robust support for a close relationship between and , while also highlighting distinct genetic differentiation between these two species. The chloroplast genome of is 156,311 bp in length and comprises 132 unique genes, including 86 protein-coding genes, 37 transfer RNAs, eight ribosomal RNAs and one pseudogene.

Synotisjinpingensis (Asteraceae, Senecioneae), a new species from Jinping county in southeastern Yunnan province, China, is described and illustrated. This species is distinguished by having white ray florets in the genus Synotis, in which only species with yellow ray florets have been hitherto known. In habit and leaf shape S.jinpingensis is most closely similar to S.duclouxii, a species occurring in southwestern Guizhou, southern Sichuan and northeastern Yunnan, China, but differs, in addition to the color of ray florets, by having fewer lateral veins of leaves, obviously longer bracts of calyculus, and larger phyllaries. The membership of the new species within Synotis is strongly corroborated by evidence from floral micromorphology and phylogenetic analyses based on ITS sequence data. Color photographs of living plants, a distribution map, and provisional IUCN status of S.jinpingensis are provided.Synotisjinpingensis (Asteraceae, Senecioneae), a new species from Jinping county in southeastern Yunnan province, China, is described and illustrated. This species is distinguished by having white ray florets in the genus Synotis, in which only species with yellow ray florets have been hitherto known. In habit and leaf shape S.jinpingensis is most closely similar to S.duclouxii, a species occurring in southwestern Guizhou, southern Sichuan and northeastern Yunnan, China, but differs, in addition to the color of ray florets, by having fewer lateral veins of leaves, obviously longer bracts of calyculus, and larger phyllaries. The membership of the new species within Synotis is strongly corroborated by evidence from floral micromorphology and phylogenetic analyses based on ITS sequence data. Color photographs of living plants, a distribution map, and provisional IUCN status of S.jinpingensis are provided.

We present molecular dating analyses for land plants that incorporate 33 fossil calibrations, permit rates of molecular evolution to be uncorrelated across the tree, and take into account uncertainties in phylogenetic relationships and the fossil record. We attached a prior probability to each fossil-based minimum age, and explored the effects of relying on the first appearance of tricolpate pollen grains as a lower bound for the age of eudicots. Many of our divergence-time estimates for major clades coincide well with both the known fossil record and with previous estimates. However, our estimates for the origin of crown-clade angiosperms, which center on the Late Triassic, are considerably older than the unequivocal fossil record of flowering plants or than the molecular dates presented in recent studies. Nevertheless, we argue that our older estimates should be taken into account in studying the causes and consequences of the angiosperm radiation in relation to other major events, including the diversification of holometabolous insects. Although the methods used here do help to correct for lineage-specific heterogeneity in rates of molecular evolution (associated, for example, with evolutionary shifts in life history), we remain concerned that some such effects (e.g., the early radiation of herbaceous clades within angiosperms) may still be biasing our inferences.

Angiosperms and their flowers have greatly diversified into an overwhelming array of forms in the past 135 million years. Diversification was shaped by changes in climate and the biological environment (vegetation, interaction with other organisms) and by internal structural constraints and potentials. This review focuses on the development and structural diversity of flowers and structural constraints. It traces floral diversification in the different organs and organ complexes (perianth, androecium, gynoecium) through the major clades of extant angiosperms. The continuously improved results of molecular phylogenetics provide the framework for this endeavor, which is necessary for the understanding of the biology of the angiosperms and their flowers. Diversification appears to work with innovations and modifications of form. Many structural innovations originated in several clades and in special cases could become key innovations, which likely were hot spots of diversification. Synorganization between organs was an important process to reach new structural levels, from which new diversifications originated. Complexity of synorganization reached peaks in Orchidaceae and Apocynaceae with the independent evolution of pollinaria. Such a review throughout the major clades of angiosperms also shows how superficial and fragmentary our knowledge on floral structure in many clades is. Fresh studies and a multidisciplinary approach are needed.