BACKGROUND AND AIMS:In conifers, leaf length exhibits remarkable variation across and within species, even within the same individual. Leaves are often shorter in drier sites and at the tops of taller trees. Several hypotheses have been proposed to explain this shortening, but a clear causal framework is lacking. We hypothesize that conifer needles should exhibit a low rate of tip-to-base conduit widening leading to higher hydraulic resistance in long needles, explaining adaptive leaf shortening. METHODS:We sampled needles from 22 Pinus species and one Sequoia sempervirens across a range of environmental conditions. We conducted a detailed intraspecific analysis on four Pinus species by measuring tracheid diameter along the needle, and an interspecific comparison by measuring tracheid diameter at the needle base across all species. In both analyses, we fitted tracheid diameter against distance from the needle tip and calculated the slope (b) of tip-to-base tracheid widening. KEY RESULTS:A low mean intraspecific widening slope (b = 0.12) was found, indicating that tracheid diameter increases only slightly from tip to base. This low widening rate cannot fully compensate for the increase in hydraulic resistance, which therefore increases with needle length. The interspecific slope of mean tracheid diameter at the needle base vs. needle length (0.25) was higher than the intraspecific mean, suggesting that longer-needled species may have wider conduits at the needle apex, offsetting needle length-imposed resistance. CONCLUSIONS:Our findings suggest that shorter needles should reduce hydraulic resistance under dry conditions or with height growth, maintaining leaf-specific conductance. We offer a novel explanation for the commonly observed pattern of needle shortening, interpreting it as an adaptive response rather than a physiological limitation.

Shrubland ecosystems cover a large part of the five Mediterranean regions of the world, and monitoring their biomass is crucial for assessing fire risk and carbon sequestration. However, biomass models for multi-stemmed shrubs remain scarce, making the quantitative assessment of shrubland biomass imprecise and often unreliable. Here, we measured, harvested, and weighed 411 specimens at two representative sites to quantify aboveground biomass (AGB) in 14 shrub species. To develop species-specific and general models of AGB, we used observations on total height (HT), diameter at collar height (DCH), number of stems (NS), and crown size as well as different geometric shapes representing crown area (CA) and bulk volume (BV). General models including all species were fit, including species identity as a random effect to take variation across species into account. A k-fold cross-validation was used to assess and compare the ability of the models to predict independent data. Individual AGB varied markedly both within and among the 14 species, with on average higher values at the site characterized by lower shrub density and species richness. Two biomass components, woody and leaf + twig, were distinguished, and species-specific means of the woody and leaf + twig proportion varied between 30 and 60

BACKGROUND AND AIMS:Forest expansion into savannas is widespread even though fire and seasonal drought provide environmental conditions against encroachment by forest specialists. A distinct suite of species can establish under savanna trees, forming bush clumps and facilitating forest establishment. Understanding the functional traits of clump-forming species is crucial for uncovering encroachment mechanisms and devising management strategies. Bark likely plays a key role in enabling clump initiation. Fire resistance can be achieved by accumulation of outer bark thickness (OBT), height and/or stem diameter (SD), while drought resistance may be enhanced by greater inner bark thickness (IBT), associated with water and carbohydrate storage. METHODS:We selected representative savanna, clump-forming and closed-canopy species (ecological categories) at two South African sites experiencing forest expansion and differing in rainfall and fire frequency. We compared OBT-SD and IBT-SD allometries across ecological categories and sites and examined whether categories separated along axes reflecting fire/drought resistance (OBT and IBT) and resource allocation strategy (density and water content, leaf size). KEY RESULTS:OBT-SD scaling of clump-forming species was more similar to savanna than forest species, and savanna species at the more fire-prone savanna had steeper OBT-SD scaling, consistent with high OBT providing fire protection in early clump formation. Similar IBT-SD slope across groups was consistent with similar metabolic needs, while higher intercepts in savanna and clump-forming species indicated higher water storage. 'Cheap' low-density tissues in savanna species allow fast accumulation of SD and OBT and resistance to fire topkill. Closed-canopy species had denser tissues and thin stems and bark for a given height, while the clump-forming species were intermediate. CONCLUSIONS:Bark and probably other traits are key in the capacity of some species to form bush clumps. Identifying these traits and the mechanisms underlying clump formation is essential for managing encroached savannas and grasslands.

Food fortification entails augmenting essential minerals, vitamins and bioactive compounds in food products to benefit the consumers by fulfilling their nutritional quality and energy requirements. Nutritionists employ synthetic and readily available micronutrients to fortify both staple and non-staple food items, thereby meeting consumers’ nutritional and energy needs. Over the past decade, food scientists have displayed a growing interest in Moringa oleifera for developing edible products and incorporating them as fortifiers. This review article specifically focuses on nutritional quality, phytochemicals, and utilization of moringa leaf powdered extracts in different commercial beverages, bread, yoghurt, and bakery products. The article also delves into clinical evidences and toxicological impacts of moringa consumption, emphasizing its health-promoting effects against celiac disease. Moreover, this comprehensive review provides valuable insights for researchers and professionals in the food industry, guiding their research and development projects in line with recent trends. Moringa leaf powder and extracts play a pivotal role in fortifying food products, such as bread, yoghurt, cookies, brownies, cake, biscuits, and beverages enhancing their nutritional quality, phytochemical content, and shelf life without significantly altering sensory attributes. The consumption of moringa-fortified products may positively impact individuals with celiac disease. Importantly, no reported toxicological effects have emerged from the consumption of these products. However, further studies on toxicological evaluations of moringa powder and extracts, particularly focusing on their impact on individuals with glycaemic, cardiac, and arthritis conditions, are warranted. The existing literature on this aspect is limited, and available data may be controversial due to various trial conditions and experiment handling.

Along their lengths, stems experience different functional demands. Because bark and wood traits are usually studied at single points on stems, it remains unclear how carbon allocation changes along tip-to-base trajectories across species. We examined bark vs wood allocation by measuring cross-sectional areas of outer and inner bark (OB and IB), IB regions (secondary phloem, cortex, and phelloderm), and wood from stem tips to bases of 35 woody angiosperm species of diverse phylogenetic lineages, climates, fire regimes, and bark morphologies. We examined how varied bark vs wood allocation was and how it was affected by precipitation, temperature, soil fertility, leaf habit, and fire regime. Allocation to phloem (relative to wood) varied little across species, whereas allocation to other tissues, strongly affected by the environment or shed in ontogeny, varied widely. Allocation to parenchyma-rich cortex and phloem was higher at drier sites, suggesting storage. Higher allocation to phloem and cortex also occurred on infertile soils, and to phloem in drought-deciduous vs cold-deciduous and evergreen species. Allocation to OB was highest at sites with frequent fires and decreased with fire frequency. Our approach contextualizes inferences from across-species studies, allows testing functional hypotheses, and contributes to disentangling the functional roles of poorly understood bark tissues.

The turgor limitation hypothesis (TLH) predicts that reduced turgor caused by gravity and hydraulic resistance at the treetop makes cell expansion beyond a certain size impossible. This environmentally-imposed upper limit on cell size should be manifest as an abrupt right-hand threshold in cell size distributions. Selection is “limited” from reaching the favored cell size, which remains on the right-hand, inaccessible, side of the developmental threshold. The TLH thus predicts that as trees grow taller, treetop leaf cell size distributions should become increasingly narrow–as selection pushes as close as possible toward the inaccessible, favored values– with a right-hand threshold. To test this, we sampled 58 individuals of two tree species across different heights, along with 24 canopy-dominant rainforest species. We measured guard, subsidiary, and pavement cell lengths from apicalmost leaves. Contrary to TLH predictions, leaf cell dimension distributions were symmetrical, without right-hand thresholds, even in the tallest trees. Regression analyses mostly revealed positive or non-significant relationships between cell size, skewness, variance, and tree height, rather than the predicted negative trends. Our findings suggest that, instead of turgor-imposed “limitation,” it is more plausible that trees produce the heights, leaf sizes, and cell dimensions favored by selection in a given environment. ### Competing Interest Statement The authors have declared no competing interest.

Background and Aims: Recent studies have focused on resolving the systematics of the tribe Gonolobinae of the family Apocynaceae, as well as the controversial genus Matelea s.l. However, many species within Matelea s.l. have not been evaluated phylogenetically. This is the case of M. gonoloboides, previously recognized as the type species of Urostephanus, and other taxa with similar floral morphology. The aim of this study is to test the monophyly of Urostephanus, including some species with morphology similar to M. gonoloboides. Furthermore, we evaluate the taxonomic position of the Urostephanus clade within the subtribe Gonolobinae and compare morphology among related clades. Methods: To assess phylogenetic relationships within Gonolobinae, we downloaded sequences from four loci for 94 species of the subtribe from GenBank. We extracted DNA and sequenced the trnL-F intergenic spacer and rps16 intron from four species of Dictyanthus and six species of Matelea, which are considered to belong to Urostephanus. We reconstructed the phylogeny with Bayesian inference using the maximum clade credibility tree. Based on the phylogenetic pattern, we performed morphological comparisons between the clades Dictyanthus, Polystemma, and Urostephanus. Key results: Phylogenetic analysis recovered Urostephanus as monophyletic and sister to Dictyanthus. Based on this phylogenetic pattern and floral morphology, we resurrect the genus Urostephanus. We propose eight new combinations for the species included in the phylogeny, as well as for those that share floral morphological similarity. We designate two lectotypes. Finally, we discuss aspects of morphology between Urostephanus and closely related groups. Conclusions: The current circumscription of Matelea s.l. includes species with high morphological diversity. With the phylogenetic and morphological evidence among related taxa, we support the resurrection of Urostephanus, more than 120 years after its description. These results contribute to the resolution of the systematics of Gonolobinae in Mesoamerica.

The goal of evolutionary biology is to explain the diversity of the entire sweep of the natural world; population biology only examines tiny slices of time of a few individuals of single species. What gives the tiny scale of population biology its relevance to evolutionary biology is the following assumption: processes identical or similar to those observed in a given population biology study are operative in unexamined individuals in the same species, have been operative throughout the history of the species, and are operative in other species. Without this assumption, population biology studies are just very detailed descriptions of a handful of individuals of a species. Population biology lacks the means to test its jusifying assumption. It is tested by the comparative method, studies of convergent evolution across species. The comparative method has its own blind spots, mainly its inability to examine intraspecific variation, heritability, and fitness directly, exactly the purview of population biology. Population and comparative biology thus provide complementary sources of direct evidence regarding evolutionary process. Both, along with optimality models, evo-devo studies of the variants that can or can’t be produced in development, together with assumptions about unseeable ancestral populations, make up essential parts of a maximally well-supported evolutionary explanation. Recognizing this essential epistemic interdependence shows why it is necessary to select sources of evidence from across population, comparative, optimality, and developmental studies, leading to collaboration rather than criticism across these fields, and stronger explanations accounting for the evolution of diversity in organismal form and function.

Skeletal muscle tissue can regenerate after damage through the action of satellite cells, which proliferate as myoblasts when activated. Oxidative stress, marked by high rates of reactive oxygen species (e.g., hydrogen peroxide, H2O2), impairs this process by increasing myoblast cell death. Moringa oleifera leaf extract (MOLE), known for its antioxidant properties, was tested for its protective effects on C2C12 myoblasts under oxidative stress. We assessed MOLE’s impact on total antioxidant capacity (TAC), glutathione homeostasis (GSH/GSSG), cell viability, and wound recovery. The metabolomic analysis of MOLE using an LC-MSMS ZenoTOF 7600 mass spectrometry system identified key compounds, including peculiar glucosinolates (42.1%) and flavonoids (18.8%), as well as phenolic acids (4.5%) and other significant metabolites (34.6%; among them, amino acids, vitamins, and fatty acids). H2O2 disrupted myoblast redox balance and caused cell death, but MOLE treatment restored the GSH/GSSG ratio, improved TAC, and increased cell viability. Additionally, MOLE promoted faster wound closure in myoblasts exposed to H2O2. These findings suggest that MOLE can protect C2C12 myoblasts by restoring redox balance and enhancing recovery under oxidative stress.

This article is a Commentary on Huntsman & Leslie (2024), 242: 2301–2311.

Abstract In a neotropical lineage of the plant clade Viburnum (Adoxaceae) several leaf ecomorphs evolved independently and repeatedly as the group radiated through cloud forests of North and South America. Here, we focus on one pair of co-occurring sister species within this radiation with strongly contrasting leaf morphotypes and document the presence of phenotypically diverse and genetically admixed hybrid individuals in multiple hybrid swarms. Hybrid phenotypes are generally intermediate in form, but sometimes show parental or entirely novel and transgressive combinations of leaf traits, suggesting that parental leaf ecomorphs can be functionally and genetically dissociated. We used admixture mapping within hybrid swarms to investigate the genetic architecture of key traits comprising these leaf ecomorphs and uncovered loci proximal to known genes implicated in leaf development, including some that may alter multiple leaf traits simultaneously, potentially facilitating the emergence of leaf syndromes. We conclude that the shared genetic architecture underlying some traits, such as leaf size and marginal teeth, could promote the repeated evolution of these traits in concert, while low levels of genetic linkage between other leaf traits supports the hypothesis that selection promoted the repeated assembly of particular combinations of leaf traits as Viburnum radiated throughout the neotropics.

Background The mechanisms leading to dieback and death of trees under drought remain unclear. To gain an understanding of these mechanisms, addressing major empirical gaps regarding tree structure-function relations remains essential.Scope We give reasons to think that a central factor shaping plant form and function is selection simultaneously favouring constant leaf-specific conductance with height growth and isometric (1:1) scaling between leaf area and the volume of metabolically active sink tissues ('sapwood'). Sapwood volume-leaf area isometry implies that per-leaf area sapwood volumes become transversely narrower with height growth; we call this 'stretching'. Stretching means that selection must favour increases in permeability above and beyond that afforded by tip-to-base conduit widening ("ultra-widening permeability"), via fewer and wider vessels or tracheids with larger pits or larger margo openings. Leaf area-metabolically active sink tissue isometry would mean that it is unlikely that larger trees die during drought because of carbon starvation due to greater sink-source relationships as compared to shorter plants. Instead, an increase in permeability is most plausibly associated with greater risk of embolism, and this seems a more probable explanation of the preferential vulnerability of larger trees to climate change-induced drought. Other implications of selection favouring constant per-leaf area sapwood construction and maintenance costs are departure from the da Vinci rule expectation of similar sapwood areas across branching orders, and that extensive conduit furcation in the stem seems unlikely.Conclusions Because all these considerations impact the likelihood of vulnerability to hydraulic failure versus carbon starvation, both implicated as key suspects in forest mortality, we suggest that these predictions represent essential priorities for empirical testing.

Hypoallometric (slope<1) scaling between metabolic rate and body mass is often regarded as near-universal across organisms. However, there are compelling reasons to question hypoallometric scaling in woody plants, where metabolic rate is directly proportional to leaf area. This leaf area must provide carbon to the volume of the metabolically active sapwood (V-MASW). Within populations of a species, variants in which V-MASW increases per unit leaf area with height growth (e.g. 2/3 or 3/44 scaling) would have proportionally less carbon for growth and reproduction as they grow taller. Therefore, selection should favor individuals in which, as they grow taller, leaf area scales isometrically with shoot V-MASW (slope=1). Using tetrazolium staining, we measured total V-MASW and total leaf area (LA(tot)) across 22 individuals of Ricinus communis and confirmed that leaf area scales isometrically with V-MASW, and that V-MASW is much smaller than total sapwood volume. With the potential of the LA(tot)-V-MASW relationship to shape factors as diverse as the crown area-stem diameter relationship, conduit diameter scaling, reproductive output, and drought-induced mortality, our work indicates that the notion that sapwood increases per unit leaf area with height growth requires revision.

Greater diversity in functional morphology should be associated with the evolution of greater ontogenetic diversity, an expectation difficult to test in most long-lived wild organisms. In the cells derived from the wood meristem (vascular cambium), plants provide extraordinary systems for reconstructing ontogenies in often long-lived organisms. The vascular cambium produces files of cells from the stem center to the periphery, with each cambial derivative "deciding" which of four cell types it differentiates into. Wood cell files remain in place, allowing tracing of the ontogenetic "decisions" taken throughout the life of a stem. We compared cell files from the Pedilanthus clade (genus Euphorbia), which span a range of growth forms from small trees and shrubs of tropical habitats to desert succulents. Using language theory, we represented wood cell types as "letters" and combinations of cell types in cell files as "words," allowing us to measure the diversity of decisions based on word frequency matrices. We also used information content metrics to compare levels of predictability in "decision-making." Our analyses identified a wider array of developmental decisions in woody trees as compared to succulent shrubs, illustrating ways that woody plants provide unparalleled systems for studying the evolution of ontogeny in long-lived, non-model species.

"Carlquist's Law" isa striking pattern of association between anatomical features in the wood of vessel-bearing plants. It derives from Sherwin Carlquist's observation that xylem vessels tend to be solitary when embedded in a matrix of imperforate tracheary elements that appear to be conductive, whereas xylem vessels tend to be grouped when surrounded by seemingly non-conductive cells. Vessel-vessel contacts (vessel grouping) allow water to travel between conduits, but also provide pathways for air to propagate from embolized (air-filled) vessels into functional vessels. If the background matrix is conductive, it is conceivable that water could bypass embolized vessels, providing an alternative transport route in species with conductive backgrounds and solitary vessels. Much remains to be tested in this hypothesis, including the topology of the vessel networks in species with solitary versus grouped vessels and how conductive the different imperforate tracheary element types are. Exploring Carlquist's Law promises to provide key insight into the causes of embolism in plant conduits, the modes of embolism passage between conduits, and how vessels and the cells in which they are imbedded may interact to govern the pathways of water flow through plants.

Discovering how xylem function emerges from xylem structure requires approaches that are distinct from those invented for wood identification. I exemplify this need for different approaches by discussing the classification of imperforate tracheary elements, the cells that go by names such as "fibers," tracheids, fiber-tracheids, and libriform fibers. Currently, there are two classification systems, one for wood identification and one championed by Sherwin Carlquist for research on xylem function. I emphasize that neither is globally "correct" for all applications, but instead each is appropriate for the aims of its field. Wood identification uses an easily-applied classification of imperforate tracheary elements, designed to remain stable over the long term. This stability allows anatomists to build large databases of wood data that are maximally useful for wood identification. In contrast, functional xylem biologists need flexible definitions that serve as hypotheses of imperforate tracheary element function to be tested, modified, and tested again, in an open-ended process of refining knowledge of xylem structure-function relations. I highlight some of the many open questions that the functional classification points to, such as the morphological correlates of the conductive/nonconductive imperforate tracheary element distinction, how imperforate tracheary element features are associated with vessel grouping, whether the libriform fiber-fiber tracheid distinction is arbitrary or not, and other topics. Recognizing that the purpose of a functional classification is to drive research shifts focus away from debates about whether a given cell type classification is "correct" and onto the empirical priorities that need study. While there is a solid tradition within comparative wood anatomy of training in wood identification, there is a need to train functional comparative wood anatomists, who can guide and interact with xylem physiologists to build more robust explanations of xylem structure and function.

Knowing how species and communities respond to environmental change is fundamental in the context of climate change. The search for patterns of abundance and phenotypic variation along altitudinal gradients can provide evidence on adaptive limits. We evaluated the species abundance and the variation in morphometric and stomatal characters in five tree ferns species (Cyathea fulva, C. divergens, C. myosuroides, Alsophila firma and Gymnosphaera salvinii) distributed along an elevation gradient in a well-preserved Mexican cloud forest. Variation at the community and species level was assessed using exploratory and multivariate data analysis methods. We wanted to explore if the species abundance is environmentally determined, to determine the degree of variation along the elevation gradient, to test for differences between zones and associations with elevation, humidity and soil nutrients, and to assess contribution of the intra- and interspecific variation to the community response to elevation and soil nutrients. The studied fern community showed strong species turnover along the elevation gradient, with some influence of soil nutrient concentration, supporting environmental determinism. All measured characters displayed variation along the gradient. Stomatal characters (size and density) had significantly less variation than morphometric characters (trunk diameter, stipe length and blade length), but stomatal density also shows interesting intraspecific patterns. In general, patterns within the fern community suggest a strong influence of species identity, especially of species inhabiting the lower edge of the cloud forest, which showed the clearest morphometric and stomatal patterns, associated to contrasting environments rather than to changes in elevation. The coincidence between morphometric and stomatal patterns in this area suggest hydraulic adjustments in response to contrasting environments. Our results provide evidence that tree ferns species respond to environmental changes through adjustments of morphometric plasticity and stomatal density, which is relevant to predict possible responses to variation in environmental conditions resulting from climate change.

¾-power scaling between metabolic rate and body mass is regarded as near-universal across organisms. However, there are compelling reasons to question ¾-power scaling in woody plants, where metabolic rate≈leaf area. This leaf area must provide carbon to the metabolically active sapwood volume (V ). V is necessarily a much smaller volume than total wood volume, meaning that scaling of total leaf area LA with V should be >¾. Within populations of a species, variants in which V increases per unit leaf area with height growth (e.g. ¾ scaling) would have proportionally less carbon for growth and reproduction as they grow taller. Therefore, selection should favor individuals in which, as they grow taller, leaf area scales isometrically with V . Using tetrazolium staining, we measured total V and total leaf area across 22 individuals of Ricinus communis and confirmed that leaf area scales isometrically with V , and that V is much smaller than total sapwood volume. With the potential of the LA -V relationship to shape factors as diverse as the crown area-stem diameter relationship, conduit diameter scaling, reproductive output, and drought-induced mortality, our work suggests that the notion that sapwood increases per unit leaf area with height growth requires revision.

Evo-devo is often thought of as being the study of which genes underlie which phenotypes. However, evo-devo is much more than this, especially in plant science. In leaf scars along stems, cell changes across wood growth rings, or flowers along inflorescences, plants trace a record of their own development. Plant morpho evo-devo provides data that genes could never furnish on themes such as heterochrony, the evolution of temporal phenotypes, modularity, and phenotype-first evolution. As plant science surges into increasingly -omic realms, it is essential to keep plant morpho evo-devo in full view as an honored member of the evo-devo canon, ensuring that plant scientists can, wherever they are, generate fundamental insights at the appropriate level of biological organization.