Floral rewards are essential in understanding floral function and evolution of the relationships between flowers and pollinators. Whether sugars are present in stigmatic exudates in Anthurium and whether it has floral nectaries have remained controversial because of the scarcity of structural studies. To solve these questions, we investigated the floral anatomy of A. andraeanum to elucidate whether

Inbreeding depression is well documented in flowering plants and adversely affects a wide range of fitness‐related traits. Recent work has begun to explore the effects of inbreeding on ecological interactions among plants and other organisms, including insect herbivores and pathogens. However, the effects of inbreeding on floral traits, floral scents, and pollinator visitation are less well studied

Belowground functional traits play a significant role in determining plant water‐use strategies and plant performance, but we lack data on root traits across communities, particularly in the tropical savanna biome, where vegetation dynamics are hypothesized to be strongly driven by tree–grass functional differences in water use.

Abiotic factors and plant species traits have been shown to drive latitudinal gradients in herbivory, and yet, population‐level factors have been largely overlooked within this context. One such factor is plant density, which may influence the strength of herbivory and may vary with latitude.

Events of accelerated species diversification represent one of Earth’s most celebrated evolutionary outcomes. Northern Andean high‐elevation ecosystems, or páramos, host some plant lineages that have experienced the fastest diversification rates, likely triggered by ecological opportunities created by mountain uplifts, local climate shifts, and key trait innovations. However, the mechanisms behind

Environmental heterogeneity influences plant distributions and diversity at several spatial scales. In temperate forests, fine‐scale environmental variation may promote local coexistence among herbaceous species by allowing plants to spatially partition microsites within forest stands. Here we argue that shallow soils, low soil water‐holding capacity and fertility, and reduced light near tree boles

Desiccation tolerance has evolved recurrently across diverse land plant lineages as an adaptation for survival in regions where seasonal rainfall drives periodic drying of vegetative tissues. Growing interest in this phenomenon has fueled recent physiological, biochemical, and genomic insights into the mechanistic basis of desiccation tolerance. Although, desiccation tolerance is often viewed as binary

All organisms engage in parasitic relations, as either parasites or hosts. Some species may even play both roles simultaneously. Among flowering plants, the most widespread form of parasitism is characterized by the development of an intrusive organ called the haustorium, which absorbs water and nutrients from the host. Despite this functionally unifying feature of parasitic plants, haustoria are not

Due to climate change, more frequent and intense periodic droughts are predicted to increasingly pose major challenges to the persistence of plant populations. When a severe drought occurs over a broad geographical region, independent responses by individual populations provide replicated natural experiments for examining the evolution of drought resistance and the potential for evolutionary rescue

Host genotype determines the effects of root‐associated fungi on a dominant coastal plant species Root‐associated fungi provide a range of functions for their hosts and can strongly influence plant structural and physiological traits. A better understanding of intraspecific variation in plant‐fungal relationships is needed, particularly in non‐model systems of high ecological importance, where these

INTRODUCTION The domestication of plants and animals was one of the most significant changes in human history. A managed cultivation of crops allowed a sedentary lifestyle and the division of work, which freed capacities to develop modern societies. The change from a wild plant to a crop required substantial morphological and physiological adaptation. Crops with similar uses display similar trait changes

Lianas are intriguing forest components in the tropics worldwide. They are characterized by thin and flexible stems, which have been related to a unique stem anatomy. Here, we hypothesized that the anatomical diversity of lianas, varying in shapes, proportions, and dimensions of tissues and cell types, would result in different stem bending stiffnesses across species. To test this hypothesis, we chose

The multiple exogenous pathways by which light availability affects plant reproduction (e.g., via influence on attraction of mutualists and antagonists) remain surprisingly understudied. The light environment experienced by a parent can also have transgenerational effects on offspring via these same pathways.

Root‐associated fungi provide a wide range of functions for their host plants, including nutrient provisioning, pathogen protection, and stress alleviation. In so doing, they can markedly influence host‐plant structural and physiological traits, although the degree to which these effects vary within particular plant host species is not well understood.

Orchids depend primarily on mycorrhizal fungi to obtain nutrients throughout their life cycle. Epiphytic orchids account for 69% of orchid diversity. The unstable availability of water and nutrients in their arboreal habitats often results in severe water and nutrient stresses. Consequently, mycorrhizal associations may be important for the survival of epiphytic orchids, but our understanding thereof

Understanding edaphic specialization is crucial for conserving rare plants that may need relocation due to habitat loss. Focusing on Eriogonum crosbyae, a rare soil specialist in the Great Basin of the United States, we asked how site‐level variation among volcanic soil outcrops affected plant growth and population distribution.

We tested 25 classic and novel hypotheses regarding trait–origin, trait–trait, and trait–environment relationships to account for flora‐wide variation in life history, habit, and especially reproductive traits using a plastid DNA phylogeny of most native (96.6%, or 1494/1547 species) and introduced (87.5%, or 690/789 species) angiosperms in Wisconsin, USA.

Nucleic acid integrity can be compromised under many abiotic stresses. To date, however, few studies have considered whether nucleic acid damage and damage repair play a role in cold‐stress adaptation. A further insufficiently explored question concerns how age affects cold stress adaptation among mature perennials. As a plant ages, the optimal trade‐off between growth and stress tolerance may shift

Targeted enrichment methods facilitate sequencing of hundreds of nuclear loci to enhance phylogenetic resolution and elucidate why some parts of the “tree of life” are difficult (if not impossible) to resolve. The mimosoid legumes are a prominent pantropical clade of ~3300 species of woody angiosperms for which previous phylogenies have shown extensive lack of resolution, especially among the species‐rich

Large disjunctions in species distributions provide excellent opportunities to study processes that shape biogeographic patterns. One such disjunction is the eastern Asia–eastern North America (EA‐ENA) floristic disjunction. For many genera with this disjunction, species richness is greater in EA than in ENA; this pattern has been attributed, in part, to higher rates of molecular evolution and speciation

Solanaceae is a scientifically and economically important angiosperm family with a minimal fossil record and an intriguing early evolutionary history. Here, we report a newly discovered fossil lantern fruit with a suite of features characteristic of Physalideae within Solanaceae. The fossil comes from the early Eocene Laguna del Hunco site (ca. 52 Ma) in Chubut, Argentina, which previously yielded

Fossils provide fundamental evidence of the evolutionary processes that crafted today’s biodiversity and consequently for understanding life on Earth. We report the finding of Myrtaceidites eucalyptoides pollen grains preserved within the anthers of a 52‐million‐year‐old Eucalyptus flower collected at Laguna del Hunco locality of Argentinean Patagonia and discuss its implications in understanding the

The Eocene–Oligocene transition (EOT; 34–33 Ma) was marked by global cooling and increased seasonality and aridity, leading to a shift in North American floras from subtropical forests to deciduous hardwood forests similar to today. This shift is well documented taxonomically and biogeographically, but its ecological nature is less known.

Fossil leaf traits can enable reconstruction of ancient environments and climates. Among these, leaf size has been particularly studied because it reflects several climatic forcings (e.g., precipitation and surface temperature) and, potentially, environment characteristics (e.g., nutrient availability, local topography, and openness of vegetation). However, imperfect preservation and fragmentation

Hybridization plays a key role in introgressive adaptation, speciation, and adaptive radiation as a source of evolutionary innovation. Hybridization is considered common in Arctostaphylos, yet species boundaries are retained in stands containing multiple species. Arctostaphylos contains diploids and tetraploids, and recent phylogenies indicate two clades; we hypothesize combinations of these traits

Cryptic species are evolutionarily distinct lineages lacking distinguishing morphological traits. Hidden diversity may be lurking in widespread species whose distributions cross phylogeographic barriers. This study investigates molecular and morphological variation in the widely distributed Caulanthus lasiophyllus (Brassicaceae) in comparison to its closest relatives.

Seed dispersal is extremely important for the recovery and restoration of forest communities. Relict tree genus Zelkova possesses a unique dispersal mechanism: mature fruits fall with the entire twig, and the dried leaves that are still attached function as a drag‐enhancing appendage, carrying the fruits away from the parent tree. This singular adaptation has never been investigated in Z. abelicea

The xylem tissue of plants performs three principal functions: transport of water, support of the plant body, and nutrient storage. Tradeoffs may arise because different structural requirements are associated with different functions or because suites of traits are under selection that relate to resource acquisition, use, and turnover. The structural and functional basis of xylem storage is not well

The importance of hybridization to invasion has been frequently discussed, with most studies focusing on the comparison of fitness‐related traits between F1 hybrids and their parents and the consequences of such fitness differences. However, relatively little attention has been given to late‐generation hybrids. Different fitness landscapes could emerge in later generations after hybrids cross with

Woody plants with photosynthetic stems are common in the drylands of the world; however, we know little about the origin(s) and geographical distribution of photosynthetic stems. Therefore, we set to answer the following questions: (1) Is stem photosynthesis phylogenetically conserved? (2) Do green‐stemmed and fleshy‐stemmed species have identifiable climatic niches?

Desiccation tolerance (DT) is a widespread phenomenon among land plants, and variable ecological strategies for DT are likely to exist. Using Syntrichia caninervis, a dryland moss and model system used in DT studies, we hypothesized that DT is lowest in juvenile (protonemal) tissues, highest in asexual reproductive propagules (gemmae), and intermediate in adults (shoots). We tested the long‐standing

Viburnum genome size variation is associated with multiple polyploidy events but not physiology Genome size may influence several aspects of plant biology, from gene regulation and cell size to physiology and speciation, but do global genome size‐trait relationships always hold up in different evolutionary contexts? Moeglein et al. used genome size estimates, in combination with chromosome counts and

Relatively recent increases in molecular and geographic data for many taxa in different areas of the world have provided scientists with tools to evaluate biodiversity using evolutionary or phylogeny‐based indices (reviewed by Laffan, 2018). These measures provide quantitative estimates of the portion of the tree of life contained in a taxon or community, aiming to answer the question of what percentage

Leaves are traditionally classified into microphylls and megaphylls, and recently have been regarded as independently originating in lycophytes, ferns, and seed plants. The developmental genetics of leaf dorsoventrality, a synapomorphy in vascular plants, has been extensively studied in flowering plants. AUXIN RESPONSE FACTOR4 (ARF4) genes are key to leaf abaxial identity in flowering plants, but whether

The nondestructive measurement of leaf area is important for expediting data acquisition in the field. The Montgomery equation (ME) assumes that leaf area (A) is a proportional function of the product of leaf length (L) and width (W), i.e., A = cLW, where c is called the Montgomery parameter. The ME has been successfully applied to calculate the surface area of many broad‐leaved species with simple

Leaf phenology is an essential developmental process in trees and an important component in understanding climate change. However, little is known about the regulation of leaf phenology in tropical trees.

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

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

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.

Past climate fluctuations during the Holocene and Pleistocene shaped the distribution of several plant species in temperate areas over the world. Wild maize, commonly known as teosinte, is a good system to evaluate the effects of historical climate fluctuations on genetic diversity due to its wide distribution in Mexico with contrasting environmental conditions. We explored the influence of contemporary

Climate change is predicted to affect natural and plantation forests. The responses of conifers to overcome changing environments will depend on their adaptation to local conditions; however, intraspecific adaptive genetic variation is unknown for most gymnosperms. Studying genetic diversity associated with phenotypic variability along environmental gradients will enhance our understanding of adaptation

Polyploidy may serve to contribute to range size if autopolyploid cytotypes are adapted to differing ecological conditions. This study aims to establish the geographic distribution of cytotypes within the giant goldenrod (Solidago gigantea), and to assess whether cytotypes exhibit differing ecological tolerances and morphology.

With digitization and data sharing initiatives underway over the last 15 years, an important need has been prioritizing specimens to digitize. Because duplicate specimens are shared among herbaria in exchange and gift programs, we investigated the extent to which unique biogeographic data are held in small herbaria vs. these data being redundant with those held by larger institutions. We evaluated

Because of their own weight and additional wind forces, plants are exposed to various bending and torsional loads that sometimes require contradictory structural characteristics and mechanical properties. The resulting trade‐off between flexural and torsional rigidity can be quantified and compared using the dimensionless twist‐to‐bend ratio.

Boreal and northern temperate forest trees possess finely tuned mechanisms of dormancy, which match bud phenology with local seasonality. After winter dormancy, the accumulation of chilling degree days (CDD) required for rest completion before the accumulation of growing degree days (GDD) during quiescence is an important step in the transition to spring bud flush. While bud flush timing is known to

The association of carnivory (an adaptation to nutrient‐poor soils) with fire has been described as a paradox, given increases in nutrient availability that often accompany fire. The nutrients that increase in availability following fire, however, may not be the same as those provided by prey and may not reduce nutrient limitation if accompanied by even greater increases in light.

One of these mutualisms is not like the other: Interactions between a plant host and two soil microbial partners may have evolved independently Legumes often interact with two types of soil microbial mutualists: arbuscular mycorrhizal (AM) fungi and rhizobia bacteria. Plants are expected to respond synergistically to these microbes, because each partner provides a different limiting nutrient (AM fungi

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

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

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

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.

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.

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

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

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

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

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.

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

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

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