Pollen dispersal, the main component of overall plant gene flow, generally decreases with increasing distance from the pollen source, but the pattern of this relationship may differ among sites. Although site‐based differences in pollen dispersal may lead to over‐ or underestimation of gene flow, no studies have investigated pollen dispersal patterns among differing urban site types, despite the incongruent

How genetic variation within a species affects phytochemical composition is a fundamental question in botany. The ratio of two specialized metabolites in Cannabis sativa, tetrahydrocannabinol (THC) and cannabidiol (CBD), can be grouped into three main classes (THC‐type, CBD‐type, and intermediate type). We tested a genetic model associating these three groups with functional and nonfunctional alleles

Species of Apocynaceae are pollinated by a diverse assemblage of animals. Here we report the first record of specialized cockroach pollination in the family, involving an endangered climbing vine species, Vincetoxicum hainanense in China. Experiments were designed to provide direct proof of cockroach pollination and compare the effectiveness of other flower visitors.

Paleontologists use tooth form to assess diets of fossil mammals. Plants would also be expected to adapt their morphology to respond to herbivory. Fossil nettle leaves with definitive stinging trichomes (tribe Urticeae, family Urticaceae) are described from the early Eocene upland lacustrine floras of the Okanogan Highlands, British Columbia, Canada. This is the first report of stinging trichomes in

Plant genome size ranges widely, providing many opportunities to examine how genome size variation affects plant form and function. We analyzed trends in chromosome number, genome size, and leaf traits for the woody angiosperm clade Viburnum to examine the evolutionary associations, functional implications, and possible drivers of genome size.

All students of xylem structure–function relations need to be familiar with the work of Sherwin Carlquist. He studies xylem through the lens of the comparative method, which uses the appearance of similar anatomical features under similar conditions of natural selection to infer function. “Function” in biology implies adaptation; maximally supported adaptation inferences require experimental and comparative

I am pleased to announce the creation of the American Journal of Botany Reviews Section, which will feature timely syntheses of major issues and new insights to guide future research. One of my primary goals as Editor‐in‐Chief of the American Journal of Botany, is to ensure that the journal is serving the needs of the members of the Botanical Society of America and plant biologists generally. In wide‐ranging

Timing of germination can strongly influence plant fitness by affecting seedling survival and by having cascading effects on later life‐history traits. In seasonal environments, the period favorable for seedling establishment and growth is limited, and timing of germination is likely to be under stabilizing selection because of conflicting selection through survival and fecundity. Moreover, optimal

Photosynthetic stems represent a source of extra carbon in plants from hot and dry environments, but little is known about how leaves and photosynthetic stems differ in terms of photosynthetic capacity, trait coordination, and responses to seasonal drought in subtropical systems.

Multipartite mutualisms are widespread in nature, but population‐level variation in these interactions is rarely quantified. In the model multipartite mutualism between legumes, arbuscular mycorrhizal (AM) fungi and rhizobia bacteria, host responses to microbial partners are expected to be synergistic because the nutrients provided by each microbe colimit plant growth, but tests of this prediction

Significant paleobotanical discoveries in recent decades have considerably improved our understanding of the early evolution of angiosperms and their flowers. However, our ability to test the systematic placement of fossil flowers on the basis of phylogenetic analyses has remained limited, mainly due to the lack of an adequate, angiosperm‐wide morphological data set for extant taxa. Earlier attempts

Atmospheric carbon dioxide (CO2) concentration is increasing, as is the frequency and duration of drought in some regions. Elevated CO2 can decrease the effects of drought by further decreasing stomatal opening and, hence, water loss from leaves. Both elevated CO2 and drought typically decrease plant nutrient concentration, but their interactive effects on nutrient status and uptake are little studied

Chloroplast movement is important for leaf growth and the timing of reproduction Chloroplast movement allows plants to optimize light absorption for photosynthesis and to avoid photoinhibition. Howard et al. report that Arabidopsis mutants, growing for six weeks under natural conditions in the field, produced fewer leaves, bolted later, and produced fewer fruits when their chloroplasts were unable

Reactive nitrogen (Nr) is a limiting factor for plant growth in agriculture. Traditionally, manure and cover plants are used as an Nr source to support crop growth. Introduction of the Haber‐Bosch process at the beginning of the last century greatly affected agriculture, offering relatively cheap access to Nr from N2, and its usage in mass‐produced N fertilizers considerably increased crop production

While root‐order approaches to fine‐root classification have shown wide utility among wild plants, they have seen limited use for perennial crop plants. Moreover, inadequate characterization of fine roots across species of domesticated perennial crops has led to a knowledge gap in the understanding of evolutionary and functional patterns associated with different fine‐root orders.

Mistletoes parasitize many hardwood and softwood tree species; however, they play key roles in forest ecosystems. Adult individuals of Psittacanthus schiedeanus take up water and xylem nutrients from both deciduous and evergreen host trees, suggesting the ability to modify its physiology according to the availability of host resources. Yet, there is little information regarding the effects of mistletoes

The impact of elevated CO2 concentration ([CO2]) and climate warming on plant productivity in dryland ecosystems is influenced strongly by soil moisture availability. We predicted that the influence of warming on the stimulation of photosynthesis by elevated [CO2] in prairie plants would operate primarily through direct and indirect effects on soil water.

As repeatedly shown, the remarkable variation in the genome size of angiosperms can be shaped by extrinsic selective pressures, including nutrient availability. Carnivory has evolved independently in 10 angiosperm clades, but all carnivorous plants share a common affinity to nutrient‐poor habitats. As such, carnivory and genome reduction could be responses to the same environmental pressure. Indeed

Defense investment in plant reproductive structures is relatively understudied compared to the defense of vegetative organs. Here the evolution of chemical defenses in reproductive structures is examined in light of the optimal defense, apparency, and resource availability hypotheses within the genus Cornus using a phylogenetic comparative approach in relation to phenology and native habitat environmental

It has been hypothesized that pollination success in animal‐pollinated dioecious plants relies on opportunistic pollinators with no discrimination against female flowers. However, empirical studies of pollinator foraging behavior and pollination effectiveness in dioecious species are few.

The Sphagnum recurvum complex comprises a group of closely related peat mosses that are dominant components of many northern wetland ecosystems. Taxonomic hypotheses for the group range from interpreting the whole complex as one polymorphic species to distinguishing 6–10 species. The complex occurs throughout the Northern Hemisphere, and some of the putative species have intercontinental ranges. Our

Recent phylogeographic work suggests the existence of latitudinal gradients in genetic diversity in northern Mexican plants, but very few studies have examined plants of the Chihuahuan Desert. Tidestromia lanuginosa is a morphologically variable annual species whose distribution includes the Chihuahuan Desert Region. Here we undertook phylogeographic analyses of chloroplast loci in this species to

The importance of chloroplast movement for plant growth in constant, controlled light and of nonphotochemical quenching (NPQ) in variable, natural light are known. Here we concurrently investigated growth and reproduction of several Arabidopsis thaliana mutants to assess the relative importance of photoprotection via chloroplast movement and NPQ.

Due to an oversight, the original title of this article requires a correction. The original title, “Diversification of crown group Araucaria: the role of Araucaria famii sp. nov. in the mid‐Cretaceous (Campanian) radiation of Araucariaceae in the Northern Hemisphere” has been changed to “Diversification of crown group Araucaria: the role of Araucaria famii sp. nov. in the late Cretaceous (Campanian)

In arid ecosystems, shrub facilitation is a critical process driving plant community structure and assembly, often resulting in increased densities of annual plants beneath shrub canopies. Pollinator‐mediated interactions can have fitness consequences for both plant interactors but are largely unexplored as an indirect consequence of direct shrub‐annual facilitation.

Whole genome duplication is a major evolutionary event, but its role in ecological divergence remains equivocal. When populations of different ploidy (cytotypes) overlap in space, “contact zones” are formed, allowing the study of evolutionary mechanisms contributing toward ploidy divergence. Multiple contact zones per species’ range are often described but rarely leveraged as natural replicates. We

Humans have a strange fascination with flowers. From the multi‐billion dollar cut‐flower industry where flowers are bred, grown, admired, and then thrown away to the houses of Christian Dior and Yves Saint Laurent, where floral extracts are used to make us smell less like mammals and more like plants, our flower obsession makes it easy to forget that they evolved not to beguile us, but primarily to

The use of functional traits has surged in recent decades, providing new insights ranging from individual plant fitness to ecosystem processes. Global plant trait databases have advanced our understanding of plant functional diversity, but they remain incomplete because of geographic and taxonomic biases. Herbarium specimens may help fill these gaps by providing trait information across space and time

Spatial variation in selective pressures can lead to intraspecific variation in life history, favoring some life histories and constraining others depending on the vulnerability of life stages. We examined how spatial variation in herbivory and climate influences flowering size and the occurrence of semelparity (reproducing once) versus iteroparity (reproducing multiple times) in the introduced range

Black mustard plants use old weapons for chemical warfare in their new range Black mustard (Brassica nigra) uses glucosinolate compounds to allelochemically suppress its competitors. This native Eurasian species has successfully invaded North America, raising the question of whether its chemical weapons have changed in the invasion process and made black mustard plants more competitive in their new

Polyploidy—whole‐genome duplication—is a key process in plant evolution, with one or more duplication events evident in the genomes of nearly all land plant lineages (Leebens‐Mack et al., 2019). Although polyploidization often also involves hybridization (allopolyploidy), it is clear that doubling the genome, in and of itself (autopolyploidy), is a macromutation: a single event with many phenotypic

Whole‐genome duplication (WGD) is a dramatic, common event in plants. Because of the detrimental effects arising from doubling the entire chromosome set, such as minority cytotype exclusion, genomic instability, mitotic and meiotic abnormalities, alterations in cell architecture, or epigenetic changes (Comai, 2005), purifying selection is expected to quickly remove polyploids from the population. Nevertheless

The novel‐weapons hypothesis predicts that some plants are successful invaders because they release allelopathic compounds that are highly suppressive to naïve competitors in invaded ranges but are relatively ineffective against competitors in the native range. For its part, the evolution of enhanced weaponry hypothesis predicts that invasive populations may evolve increased expression of the allelopathic

Resource availability affects biomass allocation in ways that could influence plant responses to disturbance such as fire. This is important because fire also varies across landscapes in ways that are correlated to resource availability. We hypothesized that plants growing in landscape microsites with a shortage of nutrients and water allocate more biomass and resources to belowground structures (and

Water stored in the xylem of woody plants is important for supporting the transpiration stream under prolonged drought, yet the source of stored water within the xylem during drought remains unclear. Insights into xylem water utilization during drought will uncover the adaptation strategies of the test species to stress.

Mortality events involving drought and pathogens in natural plant systems are on the rise due to global climate change. In Santa Barbara, California, United States, big berry manzanita (Arctostaphylos glauca) has experienced canopy dieback related to a multi‐year drought and infection from fungal pathogens in the Botryosphaeriaceae family. A greenhouse experiment was conducted using Neofusicoccum australe

Whole‐genome duplications (WGDs) are prevalent throughout the evolutionary history of plants. For example, dozens of WGDs have been phylogenetically localized across the order Brassicales, specifically, within the family Brassicaceae. A WGD event has also been identified in the Cleomaceae, the sister family to Brassicaceae, yet its placement, as well as that of WGDs in other families in the order,

Within closed‐canopy forests, vertical gradients of light and atmospheric CO2 drive variations in leaf carbon isotope ratios, leaf mass per area (LMA), and the micromorphology of leaf epidermal cells. Variations in traits observed in preserved or fossilized leaves could enable inferences of past forest canopy closure and leaf function and thereby habitat of individual taxa. However, as yet no calibration

The young seedling life stage is critical for reforestation after disturbance and for species migration under climate change, yet little is known regarding their basic hydraulic function or vulnerability to drought. Here, we sought to characterize responses to desiccation including hydraulic vulnerability, xylem anatomical traits, and impacts on other stem tissues that contribute to hydraulic functioning

The mating system has profound consequences, not only for ecology and evolution, but also for the conservation of threatened or endangered species. Unfortunately, small populations are difficult to study owing to limits on sample size and genetic marker diversity. Here, we estimated mating system parameters in three small populations of an island plant using genomic genotyping. Although self‐incompatible

The timing of self‐fertilization has potentially important consequences for the trajectory of mating system evolution, the opportunity for outcrossing, and the maintenance of genetic variation in populations. For primarily selfing taxa, it remains poorly understood as to how floral variation influences the opportunity for outcrossing and whether those attributes vary among populations across geographic

A new fossil species expands evolutionary understanding of crown group Araucaria Araucaria is a genus of evergreen coniferous trees native to the Southern Hemisphere and widely planted for ornamental and timber purposes. Stockey and Rothwell report on a fossil cone of Araucaria from the Cretaceous of Vancouver Island, one of the best‐preserved specimens of this genus ever found, containing seeds with

The question of why some introduced species become invasive has captivated ecologists for more than 60 years (Elton, 1958). Many factors might contribute to invasiveness, but one of the most long‐standing and persistently compelling hypotheses is that invaders benefit from escaping their enemies (Keane and Crawley, 2002). Human‐mediated species introductions are inherently long‐distance dispersal events

Opportunistic nectar‐feeders may act as effective pollinators; nonetheless, we still lack information on whether these opportunistic species differ in their pollination effectiveness from specialized nectarivorous vertebrates and insects. Many nectar specialists have coevolved with the plants on which they feed; therefore, we would expect higher pollination effectiveness in specialists than in opportunistic

The ecological implications of hyperaccumulation have been investigated at the organismal level, but are poorly understood at the plant community level. Questions addressed here were: Does the presence of selenium (Se) hyperaccumulators affect Se distribution and concentration in their native soil, and do hyperaccumulators affect overall vegetation properties and species composition?

Soil salinity negatively impacts plant function, development, and yield. To overcome this impediment to agricultural productivity, variation in morphological and physiological response to salinity among genotypes of important crops should be explored. Sorghum bicolor is a staple crop that has adapted to a variety of environmental conditions and contains a significant amount of standing genetic diversity

Endopolyploidy is widespread throughout the tree of life and is especially prevalent in herbaceous angiosperms. Its prevalence in this clade suggests that endopolyploidy may be adaptive, but its functional roles are poorly understood. To address this gap in knowledge, we explored whether endopolyploidy was associated with climatic factors and correlated with phenotypic traits related to growth.

Despite the fast pace of exploration of the patterns and processes influencing Neotropical plant hyperdiversity, the taxa explored are mostly from large groups that are widely distributed, morphologically diverse, or economically important. Vochysiaceae is an example of an undersampled taxon, providing an excellent system for investigating Neotropical biogeography. We present a phylogenomics‐based

Fossils show that fly‐speck fungi have been reproducing with small, black thyriothecia on leaf surfaces for ~250 million years. We analyzed morphological characters of extant thyriothecial fungi to develop a phylogenetic framework for interpreting fossil taxa.

A good understanding of genetic variation and gene dispersal in tree populations is crucial for their sustainable management, particularly in a context of rapid environmental changes. West African Sudanian savannahs are being fragmented and degraded, partly due to expansion of crop cultivation and monocultures that reduce tree density and may impact pollinators. The population dynamics of important

Undoubtedly, fossils are critical for understanding evolutionary transformations in deep time. Here, we reinvestigate the microspores and megaspores of Paleoazolla patagonica , a water fern found in Late Cretaceous sediments of the Chubut Province, Patagonia, Argentina, which provides novel evidence on the past history of the water fern clade. The study was based on recently collected specimens and

Exceptional anatomical preservation of a fossil araucarian seed cone from a marine carbonate concretion from Vancouver Island, British Columbia, Canada provides unusually complete evidence for cone structure including seeds, megagametophytes, microgametophytes, and embryos of an Upper Cretaceous (Campanian) species of Araucaria , providing important new insights into the structure and relationships

Here, we correct several analytical and clerical errors in our paper titled “Phylogeography of a widespread eastern North American shrub, Viburnum lantanoides ”. An error in our sequence handling pipeline caused the SNP dataset used in our population genetic and demographic analyses to retain a non‐negligible number of sites that did not conform to the SNP filtering procedure described in our paper

Smooth cordgrass engineers salt marsh soil microbiomes It is becoming increasingly evident that soil microbiomes are influenced by plants, but understanding of causal factors governing interactions remains elusive. Lumibao et al. conducted a field‐scale common garden experiment showing that the diversity and composition of salt marsh rhizosphere microbial communities vary according to genotypic and

How will anthropogenic changes (species invasions/extinctions, land‐use conversion, and climate change) influence the pollination and reproductive success of the world's angiosperms, 85% of which require animal pollination (Ollerton et al., 2011)? Answering this question requires understanding the mechanisms that cause pollen limitation of seed production. Pollen limitation (PL) is widespread (Bennett

Phenological events from budburst to leaf senescence are characterized by changes in organ growth and the mobilization of resources in the vascular system. Yet, in seasonally cold climates, many important phenological events (phenophases) occur in the spring and autumn at times when maintaining an active vascular system is risky and transport in the xylem and phloem might be compromised. Understanding

The dimensions of phloem sieve elements have been shown to vary as a function of tree height, decreasing hydraulic resistance as the transport pathway lengthens. However, little is known about ontogenetic patterns of sieve element scaling. Here we examine within a single species (Quercus rubra ) how decreases in hydraulic resistance with distance from the plant apex are mediated by overall plant size

Adaptive seed dispersal mechanisms are fundamental to plant fitness, but dispersal advantage is scale‐dependent. We tested the hypothesis that informed dispersal in response to an environmental cue enables dispersal by wind on a local scale for Astragalus holmgreniorum , a desert species restricted to swales and wash skirts with overland flow, but prevents longer‐distance dispersal by water into unfavorable

Pyrophilous fungi form aboveground fruiting structures (ascocarps) following wildfires, but their ecology, natural history, and life cycles in the absence of wildfires are largely unknown. Sphaerosporella is considered to be pyrophilous. This study explores Sphaerosporella ascocarp appearance following a rare 2016 wildfire in the Great Smoky Mountains National Park (GSMNP), compares the timing of ascocarp

Clouds have profound consequences for ecosystem structure and function. Yet, the direct monitoring of clouds and their effects on biota is challenging especially in remote and topographically complex tropical cloud forests. We argue that known relationships between climate and the taxonomic and functional composition of plant communities may provide a fingerprint of cloud base height, thus providing