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Asterids are one of the most successful angiosperm lineages, exhibiting extensive morphological diversity and including a number of important crops. Despite their biological prominence and value to humans, the deep asterid phylogeny has not been fully resolved, and the evolutionary landscape underlying their radiation remains unknown. To resolve the asterid phylogeny, we sequenced 213 transcriptomes/genomes and combined them with other data sets, representing all accepted orders and nearly all families of asterids. We show fully supported monophyly of asterids, Berberidopsidales as sister to asterids, monophyly of all orders except Icacinales, Aquifoliales, and Bruniales, and monophyly of all families except Icacinaceae and Ehretiaceae. Novel taxon placements benefited from the expanded sampling with living collections from botanical gardens, resolving hitherto uncertain relationships. The remaining ambiguous placements here are likely due to limited sampling and could be addressed in the future with relevant additional taxa. Using our well-resolved phylogeny as reference, divergence time estimates support an Aptian (Early Cretaceous) origin of asterids and the origin of all orders before the Cretaceous–Paleogene boundary. Ancestral state reconstruction at the family level suggests that the asterid ancestor was a woody terrestrial plant with simple leaves, bisexual, and actinomorphic flowers with free petals and free anthers, a superior ovary with a style, and drupaceous fruits. Whole-genome duplication (WGD) analyses provide strong evidence for 33 WGDs in asterids and one in Berberidopsidales, including four suprafamilial and seven familial/subfamilial WGDs. Our results advance the understanding of asterid phylogeny and provide numerous novel evolutionary insights into their diversification and morphological evolution.

Insects are captured by the carnivorous plant Nepenthes alata when they ‘aquaplane’ on the wet rim, or ‘peristome’, of the plant’s pitcher organ; here it is shown that unidirectional water flow is crucial to the complete wetting of the peristome, and that the underlying mechanism involves multiscale structural features. Pitcher plants have a way with water The carnivorous plant Nepenthes alata captures insects when they 'aquaplane' on the wet rim, or peristome, of the plant's pitcher organ. Huawei Chen and colleagues show that this is achieved through continuous directional water transport on the peristome surface, a result of multi-scale structure features involving periodic duck-billed micro-cavities with arch-shaped open edges. These features optimize capillary rise in the transport direction and prevent back-flow by pinning in place any water front moving in the reverse direction. This produces unidirectional flow despite the absence of any gradient in surface energy, and much faster transport than previously observed with asymmetrically structured surfaces. The mechanisms underlying this behaviour could be relevant for artificial fluid-transport systems with practical applications. Numerous natural systems contain surfaces or threads that enable directional water transport 1 , 2 , 3 , 4 , 5 , 6 , 7 . This behaviour is usually ascribed to hierarchical structural features at the microscale and nanoscale, with gradients in surface energy 8 , 9 and gradients in Laplace pressure 10 thought to be the main driving forces. Here we study the prey-trapping pitcher organs of the carnivorous plant Nepenthes alata . We find that continuous, directional water transport occurs on the surface of the ‘peristome’—the rim of the pitcher—because of its multiscale structure, which optimizes and enhances capillary rise 11 , 12 in the transport direction, and prevents backflow by pinning in place any water front that is moving in the reverse direction. This results not only in unidirectional flow despite the absence of any surface-energy gradient, but also in a transport speed that is much higher than previously thought. We anticipate that the basic ‘design’ principles underlying this behaviour could be used to develop artificial fluid-transport systems with practical applications.

This large comparative phylogenetic study across angiosperms shows that species that are herbaceous or have small conduits evolved these traits before colonizing environments with freezing conditions, whereas deciduous species changed their climate niche before becoming deciduous. Cold comfort for early angiosperms The earliest flowering plants or angiosperms were probably woody evergreen trees in warm tropical environments. If they were to colonize environments that experience freezing conditions, one of several changes was required. They needed either to become deciduous, to become herbaceous, or to reduce the size of their water conduits. Amy Zanne et al . present a large phylogeographic study of 49,000 angiosperms which shows that species that are herbaceous and/or have small conduits evolved these traits before colonizing freezing conditions, whereas deciduous species changed their climate niche before becoming deciduous. Early flowering plants are thought to have been woody species restricted to warm habitats 1 , 2 , 3 . This lineage has since radiated into almost every climate, with manifold growth forms 4 . As angiosperms spread and climate changed, they evolved mechanisms to cope with episodic freezing. To explore the evolution of traits underpinning the ability to persist in freezing conditions, we assembled a large species-level database of growth habit (woody or herbaceous; 49,064 species), as well as leaf phenology (evergreen or deciduous), diameter of hydraulic conduits (that is, xylem vessels and tracheids) and climate occupancies (exposure to freezing). To model the evolution of species’ traits and climate occupancies, we combined these data with an unparalleled dated molecular phylogeny (32,223 species) for land plants. Here we show that woody clades successfully moved into freezing-prone environments by either possessing transport networks of small safe conduits 5 and/or shutting down hydraulic function by dropping leaves during freezing. Herbaceous species largely avoided freezing periods by senescing cheaply constructed aboveground tissue. Growth habit has long been considered labile 6 , but we find that growth habit was less labile than climate occupancy. Additionally, freezing environments were largely filled by lineages that had already become herbs or, when remaining woody, already had small conduits (that is, the trait evolved before the climate occupancy). By contrast, most deciduous woody lineages had an evolutionary shift to seasonally shedding their leaves only after exposure to freezing (that is, the climate occupancy evolved before the trait). For angiosperms to inhabit novel cold environments they had to gain new structural and functional trait solutions; our results suggest that many of these solutions were probably acquired before their foray into the cold.

Leaf size and venation show remarkable diversity across dicotyledons, and are key determinants of plant adaptation in ecosystems past and present. Here we present global scaling relationships of venation traits with leaf size. Across a new database for 485 globally distributed species, larger leaves had major veins of larger diameter, but lower length per leaf area, whereas minor vein traits were independent of leaf size. These scaling relationships allow estimation of intact leaf size from fragments, to improve hindcasting of past climate and biodiversity from fossil remains. The vein scaling relationships can be explained by a uniquely synthetic model for leaf anatomy and development derived from published data for numerous species. Vein scaling relationships can explain the global biogeographical trend for smaller leaves in drier areas, the greater construction cost of larger leaves and the ability of angiosperms to develop larger and more densely vascularised lamina to outcompete earlier-evolved plant lineages. The size of dicotyledon leaves and their venation vary enormously across ecosystems. In this study, using 485 plant species, scaling relationships are presented between vein traits and leaf size, and explained based on a developmental algorithm that demonstrates why smaller leaves persist in drier areas.

Angiosperms are the most successful plants and support human livelihood and ecosystems. Angiosperm phylogeny is the foundation of studies of gene function and phenotypic evolution, divergence time estimation and biogeography. The relationship of the five divergent groups of the Mesangiospermae (~99.95% of extant angiosperms) remains uncertain, with multiple hypotheses reported in the literature. Here transcriptome data sets are obtained from 26 species lacking sequenced genomes, representing each of the five groups: eudicots, monocots, magnoliids, Chloranthaceae and Ceratophyllaceae. Phylogenetic analyses using 59 carefully selected low-copy nuclear genes resulted in highly supported relationships: sisterhood of eudicots and a clade containing Chloranthaceae and Ceratophyllaceae, with magnoliids being the next sister group, followed by monocots. Our topology allows a re-examination of the evolutionary patterns of 110 morphological characters. The molecular clock estimates of Mesangiospermae diversification during the late to middle Jurassic correspond well to the origins of some insects, which may have been a factor facilitating early angiosperm radiation. The phylogenetic relationships of Angiosperms remain uncertain. Here, the authors reconstruct well-supported phylogenetic relationships of the five major groups of Mesangiospermae and estimate divergence times and evolutionary patterns of plant morphological characters.

Understanding the drivers of geological‐scale patterns in plant macroevolution is limited by a hesitancy to use measurable traits of fossils to infer palaeoecophysiological function. Here, scaling relationships between morphological traits including maximum theoretical stomatal conductance (gₘₐₓ) and leaf vein density (Dᵥ) and physiological measurements including operational stomatal conductance (gₒₚ), saturated (Aₛₐₜ) and maximum (Aₘₐₓ) assimilation rates were investigated for 18 extant taxa in order to improve understanding of angiosperm diversification in the Cretaceous. Our study demonstrated significant relationships between gₒₚ, gₘₐₓ and Dᵥ that together can be used to estimate gas exchange and the photosynthetic capacities of fossils. We showed that acquisition of high gₘₐₓ in angiosperms conferred a competitive advantage over gymnosperms by increasing the dynamic range (plasticity) of their gas exchange and expanding their ecophysiological niche space. We suggest that species with a high gₘₐₓ (> 1400 mmol m⁻² s⁻¹) would have been capable of maintaining a high Aₘₐₓ as the atmospheric CO₂ declined through the Cretaceous, whereas gymnosperms with a low gₘₐₓ would experience severe photosynthetic penalty. Expansion of the ecophysiological niche space in angiosperms, afforded by coordinated evolution of high gₘₐₓ, Dᵥ and increased plasticity in gₒₚ, adds further functional insights into the mechanisms driving angiosperm speciation.

Different portions of tree root systems play distinct functional roles, yet precisely how to distinguish roots of different functions within the branching fine-root system is unclear. Here, anatomy and mycorrhizal colonization was examined by branch order in 23 Chinese temperate tree species of both angiosperms and gymnosperms forming ectomycorrhizal and arbuscular-mycorrhizal associations. Different branch orders showed marked differences in anatomy. First-order roots exhibited primary development with an intact cortex, a high mycorrhizal colonization rate and a low stele proportion, thus serving absorptive functions. Second and third orders had both primary and secondary development. Fourth and higher orders showed mostly secondary development with no cortex or mycorrhizal colonization, and thus have limited role in absorption. Based on anatomical traits, it was estimated that c. 75% of the fine-root length was absorptive, and 68% was mycorrhizal, averaged across species. These results showed that: order predicted differences in root anatomy in a relatively consistent manner across species; anatomical traits associated with absorption and mycorrhizal colonization occurred mainly in the first three orders; the single diameter class approach may have overestimated absorptive root length by 25% in temperate forests.

Global variation in total bark thickness (TBT) is traditionally attributed to fire. However, bark is multifunctional, as reflected by its inner living and outer dead regions, meaning that, in addition to fire protection, other factors probably contribute to TBT variation. To address how fire, climate, and plant size contribute to variation in TBT, inner bark thickness (IBT) and outer bark thickness (OBT), I sampled 640 species spanning all major angiosperm clades and 18 sites with contrasting precipitation, temperature, and fire regime. Stem size was by far the main driver of variation in thickness, with environment being less important. IBT was closely correlated with stem diameter, probably for metabolic reasons, and, controlling for size, was thicker in drier and hotter environments, even fire-free ones, probably reflecting its water and photosynthate storage role. OBT was less closely correlated with size, and was thicker in drier, seasonal sites experiencing frequent fires. IBT and OBT covaried loosely and both contributed to overall TBT variation. Thickness variation was higher within than across sites and was evolutionarily labile. Given high within-site diversity and the multiple selective factors acting on TBT, continued study of the different drivers of variation in bark thickness is crucial to understand bark ecology.

Across eukaryotes phenotypic correlations with genome size are thought to scale from genome size effects on cell size. However, for plants the genome/cell size link has only been thoroughly documented within ploidy series and small subsets of herbaceous species. Here, the first large-scale comparative analysis is made of the relationship between genome size and cell size across 101 species of angiosperms of varying growth forms. Guard cell length and epidermal cell area were used as two metrics of cell size and, in addition, stomatal density was measured. There was a significant positive relationship between genome size and both guard cell length and epidermal cell area and a negative relationship with stomatal density. Independent contrast analyses revealed that these traits are undergoing correlated evolution with genome size. However, the relationship was growth form dependent (nonsignificant results within trees/shrubs), although trees had the smallest genome/cell sizes and the highest stomatal density. These results confirm the generality of the genome size/cell size relationship. The results also suggest that changes in genome size, with concomitant influences on stomatal size and density, may influence physiology, and perhaps play an important genetic role in determining the ecological and life-history strategy of a species.

The surface that hates almost everything Inspired by the insect-eating Nepenthes pitcher plant, which snares its prey on a surface lubricated by a remarkably slippery aqueous secretion, Joanna Aizenberg and colleagues have synthesized omniphobic surfaces that can self-repair and function at high pressures. Their 'slippery liquid-infused porous surfaces' (or SLIPS) exhibit almost perfect slipperiness towards polar, organic and complex liquids. SLIPS function under extreme conditions, are easily constructed from inexpensive materials and can be endowed with other useful characteristics, such as enhanced optical transparency, through the selection of appropriate substrates and lubricants. Ultra-slippery surfaces of this type might find application in biomedical fluid handling, fuel transport, antifouling, anti-icing, optical imaging and elsewhere. Creating a robust synthetic surface that repels various liquids would have broad technological implications for areas ranging from biomedical devices and fuel transport to architecture but has proved extremely challenging 1 . Inspirations from natural nonwetting structures 2 , 3 , 4 , 5 , 6 , particularly the leaves of the lotus, have led to the development of liquid-repellent microtextured surfaces that rely on the formation of a stable air–liquid interface 7 , 8 , 9 . Despite over a decade of intense research, these surfaces are, however, still plagued with problems that restrict their practical applications: limited oleophobicity with high contact angle hysteresis 9 , failure under pressure 10 , 11 , 12 and upon physical damage 1 , 7 , 11 , inability to self-heal and high production cost 1 , 11 . To address these challenges, here we report a strategy to create self-healing, slippery liquid-infused porous surface(s) (SLIPS) with exceptional liquid- and ice-repellency, pressure stability and enhanced optical transparency. Our approach—inspired by Nepenthes pitcher plants 13 —is conceptually different from the lotus effect, because we use nano/microstructured substrates to lock in place the infused lubricating fluid. We define the requirements for which the lubricant forms a stable, defect-free and inert ‘slippery’ interface. This surface outperforms its natural counterparts 2 , 3 , 4 , 5 , 6 and state-of-the-art synthetic liquid-repellent surfaces 8 , 9 , 14 , 15 , 16 in its capability to repel various simple and complex liquids (water, hydrocarbons, crude oil and blood), maintain low contact angle hysteresis (<2.5°), quickly restore liquid-repellency after physical damage (within 0.1–1 s), resist ice adhesion, and function at high pressures (up to about 680 atm). We show that these properties are insensitive to the precise geometry of the underlying substrate, making our approach applicable to various inexpensive, low-surface-energy structured materials (such as porous Teflon membrane). We envision that these slippery surfaces will be useful in fluid handling and transportation, optical sensing, medicine, and as self-cleaning and anti-fouling materials operating in extreme environments.