4,690 results match your criteria American journal of botany[Journal]
Am J Bot 2018 Jun 21. Epub 2018 Jun 21.
State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, P.R. China.
Premise Of The Study: Much research has focused on plant responses to ongoing climate change, but there is relatively little information about how climate change will affect the early plant life history stages. Understanding how global warming and changes in winter snow pattern will affect seed germination and seedling establishment is crucial for predicting future alpine population and vegetation dynamics.
Methods: In a 2-year study, we tested how warming and alteration in the snowmelt regime, both in isolation and combination, influence seedling emergence phenology, first-year growth, biomass allocation, and survival of four native alpine perennial herbs on the southeastern Tibetan Plateau. Read More
Am J Bot 2018 Jun 20. Epub 2018 Jun 20.
Plant Biology Section, School of Integrative Plant Sciences, Cornell University, Ithaca, NY, 14853, USA.
Am J Bot 2018 Jun 19. Epub 2018 Jun 19.
Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Ontario, M5S 3B2, Canada.
Premise Of The Study: The strength of plant-herbivore interactions varies in space and time, but the factors that explain this variation are poorly understood. Several lines of research suggest that variation in plant reproductive systems and latitude may explain resistance against herbivores, but how these factors jointly affect plant-herbivore interactions has not been investigated in detail. We examined the effects of latitude, sexual system, and plant gender on herbivory in Sagittaria latifolia, an aquatic plant in which populations are typically monoecious (separate female and male flowers) or dioecious (separate female and male plants). Read More
Am J Bot 2018 Jun 14. Epub 2018 Jun 14.
Department of Entomology, American Museum of Natural History, Central Park West at 79th New York, NY, 10024, USA.
Premise Of The Study: An inflorescence with three pistillate flowers in amber from the early Upper Cretaceous (Turonian, ~90-94 million years ago) of central New Jersey represents the oldest known flowers with features present in an early stem complex of the Fagales. The inflorescence has characteristics of Nothofagaceae, but also has strikingly distinct characters that suggest it is intermediate between Nothofagus and other Fagales. This intermediacy is consistent with its northern hemisphere distribution. Read More
Am J Bot 2018 Jun 12. Epub 2018 Jun 12.
Department of Biological Sciences, Humboldt State University, Arcata, CA, 95521, USA.
Premise Of The Study: The deep origin and early evolution of seed plants (spermatophytes) are poorly understood. Starting in the Early Devonian, euphyllophytes diversified rapidly into several groups. Two of these groups, progymnospems and Stenokoleales, along with satellite taxa, have been involved in discussions of seed plant origins. Read More
Am J Bot 2018 Jun 12. Epub 2018 Jun 12.
Department of Biological Sciences, Humboldt State University, Arcata, CA, 95521, USA.
Premise Of The Study: The Polytrichaceae are a widespread and morphologically isolated moss lineage. Early attempts to characterize phylogenetic relationships within the family suggested that morphology is not phylogenetically informative. Two well-characterized fossils similar to basal and derived Polytrichaceae (Meantoinea alophosioides and Eopolytrichum antiquum, respectively), are known from Cretaceous rocks. Read More
Am J Bot 2018 May 12;105(5):842-850. Epub 2018 Jun 12.
Graduate School of Life Sciences, Tohoku University, 6-3 Aoba, Sendai, 980-8578, Japan.
Premise Of The Study: Plants that secrete abundant nectar attract many pollinator visits, potentially leading to a high frequency of geitonogamous pollination. However, intraflower variation in nectar volume might enhance early departure from the flower or inflorescence, reducing geitonogamy. To examine the adaptive significance of multiple nectar-producing spurs within flowers, we related intraflower variation in nectar characteristics to pollinator foraging behavior and plant reproductive success in protandrous Aquilegia buergeriana var. Read More
Am J Bot 2017 Oct;104(10):1596
Am J Bot 2017 Sep;104(9):1313-1322
Environmental Health Sciences, University of Massachusetts, Amherst, Massachusetts 01003.
Premise Of The Study: Many plants increase reproduction in response to rising levels of atmospheric CO . However, environmental and genetic variation across heterogeneous landscapes can lead to intraspecific differences in the partitioning of CO -induced carbon gains to reproductive tissue relative to growth.
Methods: We measured the effects of rising atmospheric CO on biomass allocation in the allergenic plant Ambrosia artemisiifolia (common ragweed) across a geographic climate gradient. Read More
Am J Bot 2017 Sep;104(9):1382-1389
Department of Organismic and Evolutionary Biology, Harvard University Herbaria, Cambridge, Massachusetts 02138 USA.
Premise Of The Study: Partitioning of population genetic variation in plants may be affected by numerous factors including life history and dispersal characteristics. In parasitic plants, interactions with host populations may be an additional factor influencing partitioning. To test for hierarchical population genetic patterns related to obligate endoparasitism, we studied three species of Rafflesiaceae, which grow as extremely reduced endophytes infecting Tetrastigma vines in Southeast Asia. Read More
Am J Bot 2017 Sep;104(9):1299-1312
Department of Evolution, Ecology, and Organismal Biology, 2710 Life Sciences Building, University of California, Riverside, California 92521 USA.
Premise Of The Study: To maximize benefits from symbiosis, legumes must limit physiological inputs into ineffective rhizobia that nodulate hosts without fixing nitrogen. The capacity of legumes to decrease the relative fitness of ineffective rhizobia-known as sanctions-has been demonstrated in several legume species, but its mechanisms remain unclear. Sanctions are predicted to work at the whole-nodule level. Read More
Am J Bot 2017 Sep;104(9):1277-1280
Department of Biology, 440 Biology Building, Colorado State University, Fort Collins, Colorado 80523 USA.
Am J Bot 2017 Sep;104(9):1390-1406
Department of Biology, Graduate School of Science, Chiba University, Yayoi-cho, Inage, Chiba 263-8522, Japan.
Premise Of The Study: Delimitation of cryptic species provides an understanding of biodiversity and opportunities to elucidate speciation processes. Extensive flavonoid variation has been reported in the tetraploid cytotype of the fern, Asplenium normale, although related species have no intraspecific variations in flavonoid composition. We hypothesized that Japanese A. Read More
Am J Bot 2017 Sep;104(9):1424-1430
School of Forestry and Environmental Studies, Yale University, 370 Prospect St., New Haven, Connecticut, 06511 USA.
Premise Of The Study: Despite the strong influence of the frequency and distribution of vessel endings on both hydraulic safety and efficiency, detailed anatomical descriptions or measurements of these structures are generally lacking.
Methods: Here we used high-resolution x-ray microcomputed tomography (microCT) to identify and describe xylem vessel endings within Acer rubrum root segments (1.0-2. Read More
Am J Bot 2017 Sep;104(9):1285-1298
Plant Biology Section, School of Integrative Plant Science, Cornell University, Ithaca, New York 14853 USA.
Premise Of The Study: The hydraulics of xylem has been widely studied in numerous species and organ types. However, comparatively little is known about how phloem and xylem are hydraulically coupled or about many of the basic structural properties of phloem (such as conducting cell numbers and conductive areas), which nevertheless have direct bearing on understanding phloem loading and unloading.
Methods: Using a combination of light, epifluorescence, confocal, and transmission electron microscopy, we quantified the hydraulic architecture of Ginkgo biloba leaf laminae and examined the scaling relationships between phloem and xylem in five fully mature leaves. Read More
Am J Bot 2017 Sep;104(9):1281-1284
Florida Museum of Natural History, University of Florida, Gainesville, Florida 32611 USA.
Am J Bot 2017 Sep;104(9):1344-1369
Plant Biology Section, School of Integrative Plant Science, Cornell University, Ithaca, New York 14853, USA.
Premise Of The Study: The flip-leaved podocarp Retrophyllum has a disjunct extant distribution in South American and Australasian tropical rainforests and a Gondwanic fossil record since the Eocene. Evolutionary, biogeographic, and paleoecological insights from previously described fossils are limited because they preserve little foliar variation and no reproductive structures.
Methods: We investigated new Retrophyllum material from the terminal Cretaceous Lefipán, the early Eocene Laguna del Hunco, and the early/middle Eocene Río Pichileufú floras of Patagonian Argentina. Read More
Am J Bot 2017 Sep;104(9):1407-1423
The Bergius Foundation, The Royal Swedish Academy of Sciences, SE-106 91 Stockholm, Sweden.
Premise Of The Study: The Western Indian Ocean Region (WIOR) is a biodiversity hotspot providing an ideal setting for exploring the origins of insular biodiversity and dynamics of island colonization. We aimed to investigate the origins of the WIOR Psychotrieae alliance (Rubiaceae) with typically small, probably mainly bird-dispersed drupes, and the timing and direction or sequence of its colonization events in the region.
Methods: We used the program BEAST to estimate divergence times and Lagrange for biogeographic reconstruction. Read More
Am J Bot 2017 Sep;104(9):1334-1343
Martin Luther University Halle-Wittenberg, Institute of Biology, Geobotany and Botanical Garden, Am Kirchtor 3 06108 Halle, Germany.
Premise Of The Study: Understanding the origin of ecosystems and their changes through time is important. Two mutually contrasting types of grasslands existed in the Arctic: dry- and cold-adapted grasslands of the Pleistocene dominated by Poaceae species, and presently dominating graminoid grasslands composed of sedges and rushes. We studied the taxon recruitment of the Arctic flora for Carex, the most species-rich and widespread genus of the Arctic. Read More
Am J Bot 2017 Sep;104(9):1323-1333
Facultad de Ciencias Exactas y Naturales, Universidad Nacional de La Pampa (UNLPam), 6300 Santa Rosa, La Pampa, Argentina.
Premise Of The Study: Seed-level trade-offs of heterocarpic species remain poorly understood. We propose that seedlings emerging from seeds with a permanent pappus (dispersing seeds) are stronger competitors than those emerging from seeds without a pappus (nondispersing seeds) because dispersing seeds are larger and germinate faster than nondispersing seeds in Centaurea solstitialis.
Methods: We conducted a competition experiment with both seed morphs, in which we recorded emergence rate and proportion, estimated seed dispersal by wind (anemochory) and by mammals (exozoochory), and measured size and abundance of seed morphs. Read More
Am J Bot 2017 Sep;104(9):1370-1381
Chicago Botanic Garden, Glencoe, Illinois 60022 USA.
Premise Of The Study: Hymenophyllaceae ("filmy ferns") are a widely distributed group of predominantly tropical, epiphytic ferns that also include some temperate and terrestrial species. Hymenophyllaceae are one of the earliest-diverging lineages within leptosporangiate ferns, but their fossil record is sparse, most likely because of their low fossilization potential and commonly poor preservation of their delicate, membranaceous fronds. A new species of unequivocal fossil Hymenophyllaceae, Hymenophyllum iwatsukii sp. Read More
Am J Bot 2017 Oct;104(10):1546-1555
Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa, Nagoya 464-8601, Japan.
Premise Of The Study: Hybrid zones are areas where gene flow between related species is currently occurring, so information on the compatibility between related species and their hybrids is essential for predicting the dynamics of such zones generated by introgressive hybridization. In this study, we quantified the compatibility among Magnolia stellata, M. salicifolia, and their hybrids in a hybrid zone using gene dispersal modeling. Read More
Am J Bot 2017 Oct;104(10):1437-1441
Max Planck Institute for Plant Breeding Research, Carl-von-Linné-Weg 10 50829 Cologne, Germany.
Am J Bot 2017 Oct;104(10):1569-1580
Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks Street, Toronto, Ontario, M5S 3B2, Canada.
Premise Of The Study: Assortative mating by flowering time can cause temporal genetic structure in species with heritable flowering times. A strong temporal structure, when coupled with a seasonal shift in selection, may lead to adaptive temporal clines. We implemented a prospective and retrospective method to estimate the temporal genetic structure in the pollen pool of Brassica rapa. Read More
Am J Bot 2017 Oct;104(10):1484-1492
Florida Museum of Natural History, University of Florida, Gainesville, Florida 32611, USA.
Premise Of The Study: Polyploidy has extensively shaped the evolution of plants, but the early stages of polyploidy are still poorly understood. The neoallopolyploid species Tragopogon mirus and T. miscellus are both characterized by widespread karyotypic variation, including frequent aneuploidy and intergenomic translocations. Read More
Am J Bot 2017 Oct;104(10):1433-1436
Institute of Evolutionary Biology, The University of Edinburgh, Ashworth Laboratories, Charlotte Auerbach Road, Edinburgh, EH9 3FL, UK.
Parasitic plants demonstrate a diversity of growth strategies, life histories, and developmental and physiological characteristics. Most research to date has focused on a narrow range of parasitic taxa, particularly in the Orobanchaceae, while the other independent origins of parasitism have largely gone unstudied. One type of parasite that has received relatively little attention are the endophytic parasites, which have a fascinating growth strategy where the parasite is embedded within the host tissue, with the flower the only externally visibly plant part. Read More
Am J Bot 2017 Oct;104(10):1451-1463
Genetics, Reproduction, and Populations research group, Earth and Life Institute, Université catholique de Louvain, Croix du Sud 2, Box L7.05.14, B-1348, Louvain-la-Neuve, Belgium.
Premise Of The Study: Pollination performance may depend on the type of floral resource (pollen or nectar) foraged by visitors. In buzz-pollinated plant species, the poricidal anthers release pollen during active pollen collection that induces flower vibrations. These buzz-pollinated species generally do not produce nectar. Read More
Am J Bot 2017 Oct;104(10):1510-1521
Institute of Ecology and Evolution, 335 Pacific Hall 5289, University of Oregon, Eugene, Oregon 97405 USA.
Premise Of The Study: Evolutionary radiations provide excellent opportunities to study the origins of biodiversity, but rapid divergence and ongoing gene flow make inferring evolutionary relationships among taxa difficult. Consequently, combining morphological and genomic analyses will be necessary to clarify the evolutionary history of radiations. We used an integrative approach to shed light on relationships within a diverse radiation of monkeyflowers (Mimulus section Diplacus) with a controversial taxonomic history. Read More
Am J Bot 2017 Oct;104(10):1474-1483
School of Biological Sciences, University of Queensland, St. Lucia, Queensland 4072, Australia.
Premise Of The Study: Fire typically triggers extensive regeneration of plants with heat-stimulated germination by causing short periods of intense soil heating. If plants with heat-stimulated germination are also subject to seed predation and display mast-seeding cycles, postfire recruitment may be contingent on the seedfall density of prefire masts, and on whether granivores are satiated at the time of fire.
Methods: We conducted a longitudinal seedbank study and a mensurative field experiment in central Australia to examine whether fire and the variation in seedfall density across sites in a mast year interact to influence recruitment of slender mulga (Acacia aptaneura), an iteroparous masting shrub with heat-stimulated germination. Read More
Am J Bot 2017 Oct;104(10):1533-1545
Departamento de Ecología, Pontifícia Universidad Católica de Chile, Santiago, Chile.
Premise Of The Study: Plant responses to past climate change could have been shaped by life-history traits. Here we explore the influence of life form on the response of xerophytic plants to Quaternary climate fluctuations, through a comparison of genetic patterns of codistributed herbaceous and shrubby lineages of the genus Nolana.
Methods: We reconstructed the phylogeographic history of a herbaceous lineage of three species of Nolana distributed from a northern arid zone (30°S) to a southern wet-temperate (42°S) zone, by sequencing two cpDNA regions. Read More
Am J Bot 2017 Oct;104(10):1522-1532
Bergius Foundation, Royal Swedish Academy of Sciences, Box 50005, SE-104 05 Stockholm, Sweden.
Premise Of The Study: Reconstruction of plant phylogeny has heavily relied on single-gene or multigene plastid data. New sequencing methods have led to an increasing number of studies based on data from the entire plastid, but the mitochondrion has rarely been used to infer plant phylogeny because of an assumed information poverty and demonstrated lateral transfer of mitochondrial gene regions between distantly related species.
Methods: We explored phylogenetic information from the plant mitochondrion using 57 representatives of the species-rich coffee family as study system and assessed consistency with previous results based (mostly) on plastid data. Read More
Am J Bot 2017 Oct;104(10):1464-1473
Department of Biological Sciences, The George Washington University, Washington, DC DC 20052 USA.
Premise Of The Study: Wood density is the top predictor of growth and mortality rates (vital rates) but with modest explanatory power at best. Stronger links to vital rates are expected if wood density is decomposed into its anatomical properties at sapling and adult stages, since saplings and adults differ in wood traits and vital rates. We examined whether anatomical determinants of wood density and strength of the relationship between wood traits and vital rates shift between saplings and adults. Read More
Am J Bot 2017 Oct;104(10):1493-1509
Departamento de Botânica, Instituto de Biociências, Universidade de São Paulo, Rua do Matão 277, Cidade Universitária, CEP 05508-090, São Paulo, SP, Brazil.
Premise Of The Study: Bignoniaceae is an important component of neotropical forests and a model for evolutionary and biogeographical studies. A previous combination of molecular markers and morphological traits improved the phylogeny of the group. Here we demonstrate the value of next-generation sequencing (NGS) to assemble the chloroplast genome of eight Anemopaegma species and solve taxonomic problems. Read More
Am J Bot 2017 Oct;104(10):1556-1568
Real Jardín Botánico, RJB-CSIC, Plaza de Murillo 2. 28014 Madrid, Spain.
Premise Of The Study: A bird pollination syndrome exists in the Canary Islands archipelago across independent plant lineages despite the absence of specialist birds. The pollination efficiency of current floral visitors remains unknown for many plant species despite this being a fundamental factor in testing hypotheses about the origin of the syndrome. Here, we studied the components of pollination efficiency in the paleoendemic Navaea phoenicea, a species exhibiting conspicuous anatomical modifications associated with bird pollination. Read More
Am J Bot 2017 Oct;104(10):1442-1450
Department of Biology, John Carroll University, University Heights, Ohio 44118.
Premise Of The Study: Gypsum endemism in plants (gypsophily) is common on gypsum outcrops worldwide, but little is known about the functional ecology of Chihuahuan Desert gypsophiles. We investigated whether leaf chemistry of gypsophile lineages from the northern Chihuahuan Desert are similar to leaves of related nonendemic (gypsovag) species relative to their soil chemistry. We expected widely distributed gypsophiles (hypothesized to be older lineages on gypsum) would have distinct leaf chemistry from narrowly distributed, relatively younger lineages endemic to gypsum and gypsovags, reflecting adaptation to gypsum. Read More
Am J Bot 2017 Oct;104(10):1581-1595
Department of Biology, Duke University, Box 90338, Durham, North Carolina 27708 USA.
Premise Of The Study: The California Floristic Province (CA-FP) is a unique and diverse region of floral endemism, yet the timing and nature of divergence and diversification of many lineages remain underexplored. We seek to elucidate the evolutionary history of the red oaks of the CA-FP, the Agrifoliae.
Methods: We collected PstI-associated RAD-seq data as well as morphometrics from individuals of the four species across their ranges, including varieties and hybrids. Read More
Am J Bot 2018 May 8;105(5):927-942. Epub 2018 Jun 8.
L. H. Bailey Hortorium, Plant Biology Section, School of Integrative Plant Science, Cornell University, Ithaca, NY, 14853, USA.
Premise Of The Study: The fossil record is critical for testing biogeographic hypotheses. Menispermaceae (moonseeds) are a widespread family with a rich fossil record and alternative hypotheses related to their origin and diversification. The family is well-represented in Cenozoic deposits of the northern hemisphere, but the record in the southern hemisphere is sparse. Read More
Am J Bot 2018 May 8;105(5):915-926. Epub 2018 Jun 8.
Program in Plant Biology and Conservation, Northwestern University, Evanston, IL, 60208, USA.
Premise Of The Study: Underutilized crops, such as breadfruit (Artocarpus altilis, Moraceae) have the potential to improve global food security. Humans have artificially selected many cultivars of breadfruit since its domestication began approximately 3500 years ago. The goal of this research was to identify transcriptomic signals of positive selection and to develop genomic resources that may facilitate the development of improved breadfruit cultivars in the future. Read More
Am J Bot 2018 May 7;105(5):813-814. Epub 2018 Jun 7.
Am J Bot 2018 May 6;105(5):888-897. Epub 2018 Jun 6.
Biological Sciences, University of Southampton, Life Sciences Building 85, Highfield Campus, Southampton, SO17 1BJ, UK.
Premise Of The Study: For many crops, research into the origin and partitioning of genetic variation is limited and this can slow or prevent crop improvement programs. Many of these underutilized crops have traits that could be of benefit in a changing climate due to stress tolerance or nutritional properties. Winged bean (Psophocarpus tetragonolobus (L. Read More
Am J Bot 2018 May 6;105(5):851-861. Epub 2018 Jun 6.
Department of Forest Resources, University of Minnesota, 1530 North Cleveland Avenue, St. Paul, MN, 55108, USA.
Premise Of The Study: Changes to plant phenology have been linked to warmer temperatures caused by climate change. Despite the importance of the groundlayer to community and forest dynamics, few warming experiments have focused on herbaceous plant and shrub phenology.
Methods: Using a field study in Minnesota, United States, we investigated phenological responses of 16 species to warming over five growing seasons (2009-2013) at two sites, under two canopy covers, and in three levels of simultaneous above- and belowground warming: ambient temperature, ambient +1. Read More
Am J Bot 2018 May 6;105(5):898-914. Epub 2018 Jun 6.
Department of Plant Science, Chicago Botanic Garden, 1000 Lake Cook Road, Glencoe, IL, 60022, USA.
Premise Of The Study: Underutilized crops and their wild relatives are important resources for crop improvement and food security. Cempedak [Artocarpus integer (Thunb). Merr. Read More
Am J Bot 2018 May 6;105(5):950-956. Epub 2018 Jun 6.
Laboratory of Tree Ring Research, University of Arizona, Tucson, AZ, 85721, USA.
Premise Of The Study: Most dendroecological studies focus on dominant trees, but little is known about the growing season of trees belonging to different size classes and their sensitivity to biotic factors. The objective of this study was to compare the dynamics of xylem formation between dominant and suppressed trees of Abies fabri of similar age growing in the Gongga Mountains, southeastern Tibetan Plateau, and to identify the association between xylem growth and climate.
Methods: The timing and duration of xylogenesis in histological sections were investigated weekly during the 2013-2015 growing seasons. Read More
Am J Bot 2018 Apr;105(4):812
Am J Bot 2018 May 28;105(5):815-818. Epub 2018 May 28.
The Ecosystems Center, Marine Biological Laboratory, Woods Hole, MA, 02543, USA.
Am J Bot 2018 Apr 31;105(4):623-624. Epub 2018 May 31.
Am J Bot 2018 May 25;105(5):836-841. Epub 2018 May 25.
Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania, 15260, USA.
Premise Of The Study: Studies on the effects of heterospecific pollen (HP) transfer have been focused mainly on insect-pollinated species, despite evidence of insect visitation to wind-pollinated species and transfer of their pollen onto stigmas of insect-pollinated plants. Thus, the potential consequences of HP transfer from wind-pollinated species remain largely unknown. Furthermore, accumulation of pesticide residues in pollen of wind-pollinated crops has been documented, but its potential effects on wild plant species via HP transfer have not been tested. Read More
Am J Bot 2018 May 24;105(5):943-949. Epub 2018 May 24.
Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, Arizona, 85721, USA.
Premise Of The Study: Organisms engage in multiple species interactions simultaneously. While pollination studies generally focus on plants and pollinators exclusively, secondary robbing, a behavior that requires other species (primary robbers) to first create access holes in corollas, is common. It has been shown that secondary robbing can reduce plants' female fitness; however, we lack knowledge about its impact on male plant fitness. Read More
Am J Bot 2018 May 24. Epub 2018 May 24.
Department of Ecology and Evolutionary Biology and Biodiversity Institute, University of Kansas, Lawrence, KS, 66045, USA.
Premise Of The Study: The basal asterid order, Cornales, experienced a rapid radiation during the Cretaceous, which has made it difficult to elucidate the early evolution of the order using extant taxa only. Recent paleobotanical studies, however, have begun to shed light on the early diversification of Cornales. Herein, fossils are directly incorporated in phylogenetic and quantitative morphological analyses to reconstruct early cornalean evolution. Read More