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Previous paleobotanical work concluded that Paleogene elements of the sclerophyllous subhumid vegetation of western Eurasia and western North America were endemic to these disjunct regions, suggesting that the southern areas of the Holarctic flora were isolated at that time. Consequently, molecular studies invoked either parallel adaptation to dry climates from related ancestors, or long-distance dispersal in explaining disjunctions between the two regions, dismissing the contemporaneous migration of dry-adapted lineages via land bridges as unlikely. We report Vauquelinia (Rosaceae), currently endemic to western North America, in Cenozoic strata of western Eurasia. Revision of North American fossils previously assigned to Vauquelinia confirmed a single fossil-species of Vauquelinia and one of its close relative Kageneckia. We established taxonomic relationships of fossil-taxa using diagnostic character combinations shared with modern species and constructed a time-calibrated phylogeny. The fossil record suggests that Vauquelinia, currently endemic to arid and subdesert environments, originated under seasonally arid climates in the Eocene of western North America and subsequently crossed the Paleogene North Atlantic land bridge (NALB) to Europe. This pattern is replicated by other sclerophyllous, dry-adapted and warmth-loving plants, suggesting that several of these taxa potentially crossed the North Atlantic via the NALB during Eocene times., (© 2023 The Authors New Phytologist © 2023 New Phytologist Foundation.)

Endophytic feeding behaviors, including stem borings and galling, have been observed in the fossil record from as early as the Devonian and involve the consumption of a variety of plant (and fungal) tissues. Historically, the exploitation of internal stem tissues through galling has been well documented as emerging during the Pennsylvanian (c. 323-299 million years ago (Ma)), replaced during the Permian by galling of foliar tissues. However, leaf mining, a foliar endophytic behavior that today is exhibited exclusively by members of the four hyperdiverse holometabolous insect orders, has been more sparsely documented, with confirmed examples dating back only to the Early Triassic (c. 252-250 Ma). Here, we describe a trace fossil on seed-fern foliage from the Rhode Island Formation of Massachusetts, USA, representing the earliest indication of a general, endophytic type of feeding damage and dating from the Middle Pennsylvanian (c. 312 Ma). Although lacking the full features of Mesozoic leaf mines, this specimen provides evidence of how endophytic mining behavior may have originated. It sheds light on the evolutionary transition to true foliar endophagy, contributes to our understanding of the behaviors of early holometabolous insects, and enhances our knowledge of macroevolutionary patterns of plant-insect interactions., (© 2023 The Authors. New Phytologist © 2023 New Phytologist Foundation This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA.)

Identifying the contours and correlates of species turnover is central to understanding the nature of biogeographical regions. The Hengduan Mountains region of south-central China (HMR) is well known for its high diversity of plants, but its boundaries and internal floristic structure are poorly understood, especially in relation to geographical and environmental factors. With data on occurrences and elevational ranges of seed plants across the HMR and adjacent areas of the greater Qinghai-Tibet Plateau, we identified motifs (distinct species assemblages) by Grade of Membership models, and characterized relative contributions of geography, elevation, and climate to their spatial patterns. Motifs segregate primarily by latitude, elevation, and correlated environmental variables, most sharply across the tropical-temperate divide. Secondarily, they segregate by longitude and geographical features, and reveal a novel divide across the Jinsha River. A core set of motifs corresponds to previous delineations of the HMR. The HMR biodiversity hotspot is more a mosaic of floristic elements than a cohesive entity. Grade of Membership models effectively reveal the geographical contours of biotic structure, and are a valuable new tool for biogeographical analysis., (© 2021 The Authors. New Phytologist © 2021 New Phytologist Foundation.)

We provide the first comparative multispecies analysis of spatial genetic structure and diversity in the circumpolar Arctic using a common strategy for sampling and genetic analyses. We aimed to identify and explain potential general patterns of genetic discontinuity/connectivity and diversity, and to compare our findings with previously published hypotheses. We collected and analyzed 7707 samples of 17 widespread arctic-alpine plant species for amplified fragment length polymorphisms (AFLPs). Genetic structure, diversity and distinctiveness were analyzed for each species, and extrapolated to cover the geographic range of each species. The resulting maps were overlaid to produce metamaps. The Arctic and Atlantic Oceans, the Greenlandic ice cap, the Urals, and lowland areas between southern mountain ranges and the Arctic were the strongest barriers against gene flow. Diversity was highest in Beringia and gradually decreased into formerly glaciated areas. The highest degrees of distinctiveness were observed in Siberia. We conclude that large-scale general patterns exist in the Arctic, shaped by the Pleistocene glaciations combined with long-standing physical barriers against gene flow. Beringia served as both refugium and source for interglacial (re)colonization, whereas areas further west in Siberia served as refugia, but less as sources for (re)colonization., (© 2013 The Authors. New Phytologist © 2013 New Phytologist Trust.)

Climate refugia, locations where taxa survive periods of regionally adverse climate, are thought to be critical for maintaining biodiversity through the glacial-interglacial climate changes of the Quaternary. A critical research need is to better integrate and reconcile the three major lines of evidence used to infer the existence of past refugia - fossil records, species distribution models and phylogeographic surveys - in order to characterize the complex spatiotemporal trajectories of species and populations in and out of refugia. Here we review the complementary strengths, limitations and new advances for these three approaches. We provide case studies to illustrate their combined application, and point the way towards new opportunities for synthesizing these disparate lines of evidence. Case studies with European beech, Qinghai spruce and Douglas-fir illustrate how the combination of these three approaches successfully resolves complex species histories not attainable from any one approach. Promising new statistical techniques can capitalize on the strengths of each method and provide a robust quantitative reconstruction of species history. Studying past refugia can help identify contemporary refugia and clarify their conservation significance, in particular by elucidating the fine-scale processes and the particular geographic locations that buffer species against rapidly changing climate., (© 2014 The Authors. New Phytologist © 2014 New Phytologist Trust.)

A method for the combined estimation of caffeine, theophylline and theobromine in plant material is presented. The method involved a chloroform-ammonia extraction, separation of the bases in the chloroform extract by thin layer or paper chromatography and finally estimation of the eluted bases by spectrophotometry. Good recoveries of all three compounds were recorded. The method was used to estimate the level of these compounds in tea, coffee beans and cocoa cotyledons. [ABSTRACT FROM AUTHOR]

The strong positive relationship evident between cell and genome size in both animals and plants forms the basis of using the size of stomatal guard cells as a proxy to track changes in plant genome size through geological time. We report for the first time a taxonomic fine-scale investigation into changes in stomatal guard-cell length and use these data to infer changes in genome size through the evolutionary history of land plants. Our data suggest that many of the earliest land plants had exceptionally large genome sizes and that a predicted overall trend of increasing genome size within individual lineages through geological time is not supported. However, maximum genome size steadily increases from the Mississippian (c. 360 million yr ago (Ma)) to the present. We hypothesise that the functional relationship between stomatal size, genome size and atmospheric CO2 may contribute to the dichotomy reported between preferential extinction of neopolyploids and the prevalence of palaeopolyploidy observed in DNA sequence data of extant vascular plants., (© 2013 The Authors. New Phytologist © 2013 New Phytologist Trust.)

We conducted the most extensive meta-analysis of plant and animal responses to elevated CO(2) to date. We analysed > 5000 data points extracted from 270 papers published between 1979 and 2009. We examined the changes in 19 animal response variables to the main effect of elevated CO(2). We found strong evidence for significant variation among arthropod orders and feeding guilds, including interactions in the direction of response. We also examined the main effects of elevated CO(2) on: six plant growth and allocation responses, seven primary metabolite responses, eight secondary metabolite responses, and four physical defence responses. We examined these response variable changes under two-way and three-way interactions between CO(2) and: soil nitrogen, ambient temperature, drought, light availability, photosynthetic pathway, reproductive system, plant growth rate, plant growth form, tissue type, and nitrogen fixation. In general we found smaller effect sizes for many response variables than have been previously reported. We also found that many of the oft-reported main effects of CO(2) obscure the presence of significant two- and three-way interactions, which may help better explain the relationships between the response variables and elevated CO(2)., (© 2012 The Authors. New Phytologist © 2012 New Phytologist Trust.)

• Nonnative species may change ecosystem functionality at the expense of native species. Here, we examine the similarity of functional traits of native and nonnative submersed aquatic plants (SAP) in an aquatic ecosystem. • We used field and airborne imaging spectroscopy and isotope ratios of SAP species in the Sacramento-San Joaquin Delta, California (USA) to assess species identification, chlorophyll (Chl) concentration, and differences in photosynthetic efficiency. • Spectral separability between species occurs primarily in the visible and near-infrared spectral regions, which is associated with morphological and physiological differences. Nonnatives had significantly higher Chl, carotene, and anthocyanin concentrations than natives and had significantly higher photochemical reflectance index (PRI) and δ(13) C values. • Results show nonnative SAPs are functionally dissimilar to native SAPs, having wider leaf blades and greater leaf area, dense and evenly distributed vertical canopies, and higher pigment concentrations. Results suggest that nonnatives also use a facultative C(4) -like photosynthetic pathway, allowing efficient photosynthesis in high-light and low-light environments. Differences in plant functionality indicate that nonnative SAPs have a competitive advantage over native SAPs as a result of growth form and greater light-use efficiency that promotes growth under different light conditions, traits affecting system-wide species distributions and community composition., (© 2011 The Authors. New Phytologist © 2011 New Phytologist Trust.)

Conceptually, plant functional types represent a classification scheme between species and broad vegetation types. Historically, these were based on physiological, structural and/or phenological properties, whereas recently, they have reflected plant responses to resources or environmental conditions. Often, an underlying assumption, based on an economic analogy, is that the functional role of vegetation can be identified by linked sets of morphological and physiological traits constrained by resources, based on the hypothesis of functional convergence. Using these concepts, ecologists have defined a variety of functional traits that are often context dependent, and the diversity of proposed traits demonstrates the lack of agreement on universal categories. Historically, remotely sensed data have been interpreted in ways that parallel these observations, often focused on the categorization of vegetation into discrete types, often dependent on the sampling scale. At the same time, current thinking in both ecology and remote sensing has moved towards viewing vegetation as a continuum rather than as discrete classes. The capabilities of new remote sensing instruments have led us to propose a new concept of optically distinguishable functional types ('optical types') as a unique way to address the scale dependence of this problem. This would ensure more direct relationships between ecological information and remote sensing observations.

Quantification of the fate of carbon (C) used by plant metabolism is necessary to improve predictions of terrestrial ecosystem respiration and its sources. Here, a dual isotope ((13)C and (14)C) pulse-label was used to determine the allocation of new C to different respiratory pathways in the early and late growing seasons for two plant functional types, perennial grasses and shrubs, in the Owens Valley, CA, USA. Allocation differences between plant types exceeded seasonal allocation variation. Grasses respired 71 and 64% and shrubs respired 22 and 17% of the label below-ground in the early and late growing seasons, respectively. Across seasons and plant types, approximately 48-61% of the label recovered was respired in 24 h, approximately 68-84% in 6 d, and approximately 16-33% in 6-36 d after labeling. Three C pools were identified for plant metabolism: a fast pool with mean residence times (MRTs) of approximately 0.5 and approximately 1 d below- and above-ground, respectively; an intermediate pool with MRTs of 19.9 and 18.9 d; and a storage pool detected in new leaf early growing season respiration > 9 months after assimilation. Differences in allocation to fast vs intermediate C pools resulted in the mean age of C respired by shrubs being shorter (3.8-4.5 d) than that of the grasses (4.8-8.2 d).

Summary: Greenbeards are selfish genetic elements that make their bearers behave either altruistically towards individuals bearing similar greenbeard copies or harmfully towards individuals bearing different copies. They were first proposed by W. D. Hamilton over 50 yr ago, to illustrate that kin selection may operate at the level of single genes. Examples of greenbeards have now been reported in a wide range of taxa, but they remain undocumented in plants. In this paper, we discuss the theoretical likelihood of greenbeard existence in plants. We then question why the greenbeard concept has never been applied to plants and speculate on how hypothetical greenbeards could affect plant–plant interactions. Finally, we point to different research directions to improve our knowledge of greenbeards in plants. [ABSTRACT FROM AUTHOR]

An introduction is presented in which the editor discusses the contribution of former editor-in-chiefs (EiCs) Peter Ayres and Ian Woodward within the issue.

The influence of number of seeds per clump upon germination of Plantago coronopus L. was investigated at different salinity levels on filter paper, sand and soil. These substrates provide both artificial and semi-natural microenvironments for seed germination. On all substrates, germination was positively dependent on clump density and seeds in clumps had a higher tolerance of salinity as reflected in higher germination percentages. Final percentage germination for a given clump size and salinity level depended upon substrate, being far higher on filter paper and sand than on soil, whilst the time required to reach final germination also increased in that order. The possible ecological significance of density-dependent seed germination is discussed. [ABSTRACT FROM AUTHOR]

The article comments on the prominence of papers featured in the "New Phytologist" journal that consider various aspects of plant interactions with the environment. The author believes that the relative change in scope can be traced back over more than a century that the journal has been published. The coordinated efforts of scientists are needed to respond to the challenges posed by atmospheric and climactic change.

Global ecology - the study of the interactions among the Earth's ecosystems, land, atmosphere and oceans - depends crucially on global observations: this paper focuses on space-based observations of global terrestrial ecosystems. Early global ecology relied on an extrapolation of detailed site-level observations, using models of increasing complexity. Modern global ecology has been enabled largely by vegetation indices (greenness) from operational space-based imagery but current capabilities greatly expand scientific possibilities. New observations from spacecraft in orbit allowed an estimation of gross carbon fluxes, photosynthesis, biomass burning, evapotranspiration and biomass, to create virtual eddy covariance sites in the sky. Planned missions will reveal the dimensions of the diversity of life itself. These observations will improve our understanding of the global productivity and carbon storage, land use, carbon cycle-climate feedback, diversity-productivity relationships and enable improved climate forecasts. Advances in remote sensing challenge ecologists to relate information organised by biome and species to new data arrayed by pixels and develop theory to address previously unobserved scales., (© 2019 Jet Propulsion Lab, California Institute of Technology New Phytologist © 2019 New Phytologist Trust.)

In a previous paper (Faiz and Weatherley, 1977), evidence was put forward for the development of steep gradients of water potential in the soil surrounding the individual roots of rapidly transpiring plants (perirhizal gradients). In this paper, similar experiments are described in which additional data on the dimensions of the root system, distribution of soil water potentials within the rooting zone and the water potentials of the roots themselves were obtained. It was found with experiments on soil that the surface area of the root system was X 60 the cross-sectional area of the pararhizal pathway (cross-sectional area of the pot) through which water moved to the root zone from the water table below. Since the volume rate of flow through the pen- and pararhizal zones was the same, the velocity of movement up to the individual root was therefore only 1/60 of that through the soil supplying the root system. Under conditions of rapid transpiration, the gradient of water potential in that part of the pararhizal pathway immediately beneath the root zone was found to be about 1 bar cm-1. Thus it would be expected that the perirhizal gradient would be 1/60 of this, i.e. it would be negligibly small. However, the actual perirhizal drop in water potential was found to be about 8 bars through a distance of 0.1 cm, i.e. the gradient was 80 bars cm1. Such a steep gradient would require the hydraulic conductivity of the soil in the perirhizal zones to be 4 orders of magnitude lower than that in the pararhizal pathway. An even greater discrepancy was found with fine sand. The soil within the rooting zone had a somewhat lower water content than that in the pararhizal zone, but it is not thought that this, and some other imponderables which are discussed, could account for this enormous discrepancy. It is concluded that in these experiments, measurable perirhizal gradients were unlikely to develop. [ABSTRACT FROM AUTHOR]

The Scholander-Hammel pressure chamber has been used in thousands of papers to measure osmotic pressure, πc, turgor pressure, Pt, and bulk modulus of elasticity, ε, of leaf cells by pressure-volume ( PV) curve analysis. PV analysis has been questioned in the past., In this paper we use micromechanical analysis of leaf cells to examine the impact on PV curve analysis of negative turgor in living cells ( Pt)., Models predict negative Pt (−0.1 to −1.8 MPa) depending on leaf cell size and shape in agreement with experimental values reported by J. J. Oertli. Modeled PV curves have linear regions even when Pt is quite negative, contrary to the arguments of M.T. Tyree. Negative Pt is totally missed by PV curve analysis and results in large errors in derived πc and Pt but smaller errors in ε., A survey of leaf cell sizes vs habitat (arid, temperate, and rainforest), suggests that the majority of published PV curves result in errors of 0.1-1.8 MPa in derived πc and Pt, whereby the error increases with decreasing cell size. We propose that small cell size in leaves is an ecological adaptation that permits plants to endure negative values of water potential with relatively little water loss. [ABSTRACT FROM AUTHOR]

Although primarily valued for their suitability for oceanographic applications and soil moisture estimation, microwave remote sensing observations are also sensitive to plant water content (M w ). Since M w depends on both plant water status and biomass, these observations have the potential to be useful for a range of plant drought response studies. In this paper, we introduce the principles behind microwave remote sensing observations to illustrate how they are sensitive to plant water content and discuss the relationship between landscape-scale M w and common stand-scale metrics, including plant-scale relative water content, live fuel moisture content and leaf water potential. Lastly, we discuss how various sensor types can be leveraged for specific applications depending on the spatio-temporal resolution needed., (© 2019 The Authors. New Phytologist © 2019 New Phytologist Trust.)

Contents Summary 1253 I. Introduction 1253 II. What is the rate and molecular spectrum of spontaneous epimutations? 1254 III. Do spontaneous epimutations have phenotypic consequences? 1257 IV. Conclusion and discussion 1258 Acknowledgements 1258 References 1258 SUMMARY: Heritable gains or losses of cytosine methylation can arise stochastically in plant genomes independently of DNA sequence changes. These so-called 'spontaneous epimutations' appear to be a byproduct of imperfect DNA methylation maintenance and epigenome reinforcement events that occur in specialized cell types. There is continued interest in the plant epigenetics community in trying to understand the broader implications of these stochastic events, as some have been shown to induce heritable gene expression changes, shape patterns of methylation diversity within and among plant populations, and appear to be responsive to multi-generational environmental stressors. In this paper we synthesized our current knowledge of the molecular basis and functional consequences of spontaneous epimutations in plants, discuss technical and conceptual challenges, and highlight emerging research directions., (© 2018 The Authors. New Phytologist © 2018 New Phytologist Trust.)

Methods of growing axenic seedlings infected by vesicular arbuscular mycorrhizal fungi are described, using agar, paper or glass as a support. Two of the techniques are particularly suitable for studying the interaction between the fungus and the host plant, for example the germination of the spore inoculum, hyphal growth around the roots before the symbiosis has been initiated and the early stages of root penetration. [ABSTRACT FROM AUTHOR]

According to the plant-apparency hypothesis, apparent plants allocate resources to quantitative defenses that negatively affect generalist and specialist herbivores, while unapparent plants invest more in qualitative defenses that negatively affect nonadapted generalists. Although this hypothesis has provided a useful framework for understanding the evolution of plant chemical defense, there are many inconsistencies surrounding associated predictions, and it has been heavily criticized and deemed obsolete. We used a hierarchical Bayesian meta-analysis model to test whether defenses from apparent and unapparent plants differ in their effects on herbivores. We collected a total of 225 effect sizes from 158 published papers in which the effects of plant chemistry on herbivore performance were reported. As predicted by the plant-apparency hypothesis, we found a prevalence of quantitative defenses in woody plants and qualitative defenses in herbaceous plants. However, the detrimental impacts of qualitative defenses were more effective against specialists than generalists, and the effects of chemical defenses did not significantly differ between specialists and generalists for woody or herbaceous plants. A striking pattern that emerged from our data was a pervasiveness of beneficial effects of secondary metabolites on herbivore performance, especially generalists. This pattern provides evidence that herbivores are evolving effective counteradaptations to putative plant defenses., (© 2016 The Authors. New Phytologist © 2016 New Phytologist Trust.)

The aim of producing sustainable liquid biofuels and chemicals from lignocellulosic biomass remains high on the sustainability agenda, but is challenged by the costs of producing fermentable sugars from these materials. Sugars from plant biomass can be fermented to alcohols or even alkanes, creating a liquid fuel in which carbon released on combustion is balanced by its photosynthetic capture. Large amounts of sugar are present in the woody, nonfood parts of crops and could be used for fuel production without compromising global food security. However, the sugar in woody biomass is locked up in the complex and recalcitrant lignocellulosic plant cell wall, making it difficult and expensive to extract. In this paper, we review what is known about the major polymeric components of woody plant biomass, with an emphasis on the molecular interactions that contribute to its recalcitrance to enzymatic digestion. In addition, we review the extensive research that has been carried out in order to understand and reduce lignocellulose recalcitrance and enable more cost-effective production of fuel from woody plant biomass., (© 2015 The Authors. New Phytologist © 2015 New Phytologist Trust.)

Photosynthetic pigment composition has been a major study target in plant ecophysiology during the last three decades. Although more than 2000 papers have been published, a comprehensive evaluation of the responses of photosynthetic pigment composition to environmental conditions is not yet available. After an extensive survey, we compiled data from 525 papers including 809 species (subkingdom Viridiplantae) in which pigment composition was described. A meta-analysis was then conducted to assess the ranges of photosynthetic pigment content. Calculated frequency distributions of pigments were compared with those expected from the theoretical pigment composition. Responses to environmental factors were also analysed. The results revealed that lutein and xanthophyll cycle pigments (VAZ) were highly responsive to the environment, emphasizing the high phenotypic plasticity of VAZ, whereas neoxanthin was very stable. The present meta-analysis supports the existence of relatively narrow limits for pigment ratios and also supports the presence of a pool of free 'unbound' VAZ. Results from this study provide highly reliable ranges of photosynthetic pigment contents as a framework for future research on plant pigments., (© 2014 The Authors. New Phytologist © 2014 New Phytologist Trust.)

Globally, root production accounts for 33-67% of terrestrial net primary productivity and influences decomposition via root production and turnover, carbon (C) allocation to mycorrhizal fungi and root exudation. As recognized above ground, the timing of phenological events affects terrestrial C balance, yet there is no parallel understanding for below-ground phenology. In this paper we examine the phenology of root production and its relationship to temperature, soil moisture, and above-ground phenology. Synthesizing 87 observations of whole-plant phenology from 40 studies, we found that, on average, root growth occurs 25 ± 8 d after shoot growth but that the offset between the peak in root and shoot growth varies > 200 d across biomes (boreal, temperate, Mediterranean, and subtropical). Root and shoot growth are positively correlated with median monthly temperature and mean monthly precipitation in boreal, temperate, and subtropical biomes. However, a temperature hysteresis in these biomes leads to the hypothesis that internal controls over C allocation to roots are an equally, if not more, important driver of phenology. The specific mechanisms are as yet unclear but they are likely mediated by some combination of photoassimilate supply, hormonal signaling, and growth form.

The article introduces the journal New Phytologist. The New Phytologist founded in 1902 by researcher Arthur Tansley and now a registered charitable trust, is managed by a panel of Trustees and Advisors who receive no remuneration. Among their tasks, in addition to those of editing papers and preparing the monthly issues of the journal, are ensuring that the Trust remains on a firm financial footing and that profit from sales are used entirely to enhance the study of plants. To these ends, the Trustees and Advisors have continued actively to exploit the competition that exists in the publishing trade to obtain the best return for the outlay of subscribers.

This paper describes the ecology of a coastal alluvial plain at Chichiriviche in northern Venezuela. The area supports a great diversity of plant communities, ranging from mangroves on the seaward edge of the plain to non-halophytic, fresh-water communities on the landward side. Small differences on topography result in a mosaic of saline and less-saline environments . Rainfall is strongly seasonal, causing superficial flooding of the alluvial plain in the rainy season and the creation of a hypersaline substratum during the dry season. As a consequence, much of the plain is devoid on vegetation. Towards the landward side of the plain there are numerous small 'vegetation islands', fringed by halophilic succulent herbs, and made up of deciduous and semi-deciduous shrubs and trees together with non-halophytic CAM plants such as cacti and bromeliads. In subsequent papers the results of ecophysiological studies of these diverse plant species are presented. [ABSTRACT FROM AUTHOR]

The long period covered by this paper probably saw the most drastic changes wrought by man on the plant cover of these islands in the whole of postglacial history. Much of our information about vegetation changes comes from those parts of the country where peats and mires are abundant, which leaves those areas which were the cradle of successive cultural groups largely unrepresented. Sources of environmental evidence are now emerging even from this unpromising background, an important element amongst which are man's own works. The evidence of changes wrought by man may come from non-botanical as well as botanical material. Pollen, charcoal, phytoliths, seeds, mosses, and other macroscopic plant remains may be extracted, but indirect evidence may also be obtained from land snails, insects, bones (including small vertebrates), as well as from preserved soils and land surfaces. In the various environments considered a trend from forest through clearance to pastoral or arable agriculture can usually be demonstrated. These changes may ultimately result in site deterioration on a large scale, the nature of which will depend upon the ecological conditions and the practices at work. In extreme cases peat may form or soil erosion take place. On base-poor soils, soil acidification may become so intense that the land is no longer usable for traditional agriculture and is allowed to degenerate to moorland or heath. In early historic times much degraded land came into use again for hill-grazing, a process which further depauperated both the flora and the soils. [ABSTRACT FROM AUTHOR]

Reproduction was examined in one summer annual (Euphrasia pseudokerneri) and two biennials (Linum catharticum and Gentianella amarella) in chalk grassland, and three dune winter annuals (Erophila verna, Cerastium semidecandrum and Myosotic ramosissima). Gentianella was examined in 1979 to 1981 and all other species in 1980 and 1981, making a total of 13 separate datasets, Plants with one or two fruits had fewer seeds per fruit in all 13 cases. As plant size increased to six to ten fruits, seed number gradually increased. The relationship was similar in 1980 and 1981 for all six species. A 'depauperate' plant was therefore defined as one which produces significantly fewer seeds per fruit than large plants. Field populations of all species averaged less than nine fruits per plant, so that the relationship between seed number and fruit number was important in determining seeds produced per plant. Although this relationship has only been noted in three other species, I interpret five recent papers as suggesting the existence of a similar relationship between fruit number and seed number. I interpret the effect as analogous to the abortion of fruits in plants with many fruits. [ABSTRACT FROM AUTHOR]

The fruit of aonla (Emblica officinalis) remains at rest without growth for a period of 3½ months after setting and resumes growth thereafter. Studies on endogenous gibberellin activity of the fruit and exogenous applications of gibberellin to the fruit at rest suggest that the inability of the fruit to resume growth immediately after setting is not due to gibberellin deficiency. The fruit, when making rapid growth following its rest, contained six gibberellin-like factors active in the lettuce hypocotyl test. Five behaved like gibberellins A1, A3, A4, A7 and A9 in paper, thin-layer and silicic acid : celite column chromatography. [ABSTRACT FROM AUTHOR]

The content of gibberellin-like (GA-like) substances in various parts of young alder (Alnus glutinosa (L.) Gaertn.) plants was estimated by means of the lettuce hypocotyl bioassay. The highest levels of GA-like activity were found in the root nodules, of dormant plants, plants emerging from dormancy, and plants in full leaf. No major differences were found in the roots and leaves of nodulated as opposed to nonnodulated plants, although the stems of nodulated plants did contain lower levels of GA-like activity. The detection of seasonal changes in GA-like activity in root nodules from mature trees was dependent upon the method of chromatography employed. One major peak of biological activity was detected following paper chromatography and no large changes were detected in the level of this component. In contrast, three zones of GA-like activity could be detected after thin layer chromatography (TLC) and there were marked seasonal changes in activity in these three zones. This can be attributed either to changes in levels of the GA-like substances themselves and/or to variations in the amounts of impurities interfering with the response of the bioassay. A number of peaks of GA-like activity were detected by lettuce and rice bioassays following analysis of a large-scale extract on a preparative high performance liquid chromatograph (HPLC). However, both the total number and the identity of the substances responsible for this activity, remain to be determined. [ABSTRACT FROM AUTHOR]

Invasion science is a very active subdiscipline of ecology. However, some scientists contend that theoretical integration has been limited and that predictive power remains weak. This paper, focusing on plants, proposes a new multi-pronged research strategy that builds on recent advances in invasion science. More intensive studies on particular model organisms and ecosystems are needed to improve our understanding of the full suite of interacting factors that influence invasions ('model system research'). At the same time, comparative studies across many study systems are essential for unravelling the context-dependencies of insights that emerge from particular studies ('multi-site studies'); and quantitative synthesis based on large datasets should be constrained to well-defined theoretical domains ('focused meta-analysis'). We also suggest ways for better integration of information about species biology and ecosystem characteristics ('invasion syndromes'). We expect that a resulting theory of invasions will need to be conceived as a somewhat heterogeneous conglomerate of elements of varying generality and predictive power: laws that apply to well-specified domains, general concepts and theoretical frameworks that can guide thinking in research and management, and in-depth knowledge about the drivers of particular invasions., (© 2013 The Authors. New Phytologist © 2013 New Phytologist Trust.)

Examines the splitting open of sedimentary rocks and finding fossil plants. Leaf characteristics of extant Nothofagus cunninghamii; Contribution of genotypic control and environmental plasticity; Analysis of the genotypic control of leaves.

Waterlogging affects large areas of agricultural land, resulting in severe economic penalties because of massive losses in crop production. Traditionally, plant breeding for waterlogging tolerance has been based on the field assessment of a range of agronomic and morphological characteristics. This review argues for a need to move towards more physiologically based approaches by targeting specific cellular mechanisms underling key components of waterlogging tolerance in plants. Also, while the main focus of researchers was predominantly on plant anoxia tolerance, less attention was given to plant tolerance to phytotoxins under waterlogged conditions. This paper reviews the production of major elemental and organic phytotoxins in waterlogged soils and describes their adverse effects on plant performance. The critical role of plasma membrane transporters in plant tolerance to secondary metabolite toxicity is highlighted, and ionic mechanisms mediating the this tolerance are discussed. A causal link between the secondary metabolite-induced disturbances to cell ionic homeostasis and programmed cell death is discussed, and a new ethylene-independent pathway for aerenchyma formation is put forward. It is concluded that plant breeding for waterlogging tolerance may significantly benefit from targeting mechanisms of tolerance to phytotoxins.

Agricultural weeds evolve in response to crop cultivation. Nevertheless, the central importance of evolutionary ecology for understanding weed invasion, persistence and management in agroecosystems is not widely acknowledged. This paper calls for more evolutionarily-enlightened weed management, in which management principles are informed by evolutionary biology to prevent or minimize weed adaptation and spread. As a first step, a greater knowledge of the extent, structure and significance of genetic variation within and between weed populations is required to fully assess the potential for weed adaptation. The evolution of resistance to herbicides is a classic example of weed adaptation. Even here, most research focuses on describing the physiological and molecular basis of resistance, rather than conducting studies to better understand the evolutionary dynamics of selection for resistance. We suggest approaches to increase the application of evolutionary-thinking to herbicide resistance research. Weed population dynamics models are increasingly important tools in weed management, yet these models often ignore intrapopulation and interpopulation variability, neglecting the potential for weed adaptation in response to management. Future agricultural weed management can benefit from greater integration of ecological and evolutionary principles to predict the long-term responses of weed populations to changing weed management, agricultural environments and global climate.