Effective population size mediates the impact of pollination services on pollen limitation.

Inadequate pollen receipt limits flowering plant reproduction worldwide. Ecological causes of pollen limitation (PL), like pollinator scarcity and low plant abundance, have been a primary research focus. The genetic diversity of plant populations could impact both quantity and quality components of PL in concert with ecological factors, yet empirical examples are lacking. We evaluated joint effects of ecological factors (flower abundance, pollinator visitation) and genetic effective population size (NE) on PL across 13 populations of the common herb Argentina anserina. We used a histological approach with 5504 styles from 1137 flowers to separate quantity and quality components of PL, and link these to reproductive output. NE and pollinator visitation interacted to shape PL, but NE had stronger direct effects. Effectively smaller populations experienced stronger quantity PL, and controlled crosses in a pollinator-free environment revealed that stigmatic pollen quantity was an intrinsic population-level attribute that increased with NE. Pollinator visitation enhanced pollen quality, but only in effectively larger populations. Quantity and quality PL negatively impacted fruit and seed set, respectively. Results highlight that PL is dictated by plant population genetic diversity in addition to commonly evaluated ecological factors. Efforts to support pollinators will more strongly enhance plant reproduction in genetically diverse populations.

Evolution of flowering time due to variation in the onset of pollen dispersal among individuals.

The evolution of flowering time is often attributed to variations in pollinator rates over time. This study proposes that flowering time can evolve through siring success variation among individuals caused by differential pollen dispersal timing (a result of flowering time variation). By building quantitative genetic models, I show that flowering time evolves to be earlier when the pollen removal rate is low and pollen deposition rate is high, and the fertilization ability of removed pollen declines slowly. Using evolutionary game theory, I show that the evolutionarily stable variance of flowering time is large when the pollen removal rate is either low or high, the pollen deposition rate is moderate, and the fertilization ability of removed pollen declines rapidly. Investigation of the coevolution of flower longevity and flowering time shows that under constant pollination rates, late flowering will be correlated with long-lived flowers due to nonrandom mating, which suggests that the observed correlation between late flowering and short-lived flowers is caused by other factors, such as declining pollination rates during late-stage flowering. I discuss how altered pollination rates under climate change will influence flowering time evolution and the importance of distinguishing between pollen removal and deposition rates.

SPA, a Stigma-style-transmitting tract Physical microenvironment Assay for investigating mechano-signaling in pollen tubes.

Accurate sensing and responding to physical microenvironment are crucial for cell function and survival, but the underlying molecular mechanisms remain elusive. Pollen tube (PT) provides a perfect single-cell model for studying mechanobiology since it's naturally subjected to complex mechanical instructions from the pistil during invasive growth. Recent reports have revealed discrepant PT behaviors between in vivo and flat, two-dimensional in vitro cultures. Here, we established the Stigma-style-transmitting tract (TT) Physical microenvironment Assay (SPA) to recapitulate pressure changes in the pistil. This biomimetic assay has enabled us to swiftly identify highly redundant genes, GEF8/9/11/12/13, as new regulators for maintaining PTs integrity during style-to-TT emergence. In contrast to normal growth on solid medium, SPA successfully phenocopied gef8/9/11/12/13 PT in vivo growth-arrest deficiency. Our results suggest the existence of distinct signaling pathways regulating in vivo and in vitro PT integrity maintenance, underscoring the necessity of faithfully mimicking the physical microenvironment for studying plant cell biology.

Pollinators differ in their contribution to the male fitness of a self-incompatible composite.

PREMISE: Reproductive fitness in plants is often determined by the quantity and quality of pollen transferred by pollinators. However, many fitness studies measure only female fitness or rely on proxies for male fitness. Here we assessed how five bee taxon groups affect male fitness in a prairie plant by quantifying pollen removal, visitation, and siring success using paternity assignments and a unique pollinator visitation experiment. METHODS: In Echinacea angustifolia, we measured per-visit pollen removal for each pollinator taxon and estimated the number of pollen grains needed for successful ovule fertilization. Additionally, we directly measured pollinator influence on siring by allowing only one bee taxon to visit each pollen-donor plant, while open-pollinated plants acted as unrestricted pollen recipients. We genotyped the resulting offspring, assigned paternity, and used aster statistical models to quantify siring success. RESULTS: Siring success of pollen-donor plants differed among the five pollinator groups. Nongrooming male bees were associated with increased siring success. Bees from all taxa removed most of the flowering head's pollen in one visit. However, coneflower-specialist bee Andrena helianthiformis removed the most pollen per visit. Female fitness and proxy measures of male fitness, such as pollinator visitation and pollen removal, did not align with our direct quantifications of male fitness. CONCLUSIONS: Our results illustrate the need for more studies to directly quantify male fitness, and we caution against using male fitness proxy measures. In addition, conservation efforts that preserve a diverse pollinator community can benefit plants in fragmented landscapes.

Fatty Acid Composition of Dry and Germinating Pollen of Gymnosperm and Angiosperm Plants.

A pollen grain is a unique haploid organism characterized by a special composition and structure. The pollen of angiosperms and gymnosperms germinate in fundamentally similar ways, but the latter also have important features, including slow growth rates and lower dependence on female tissues. These features are, to some extent, due to the properties of pollen lipids, which perform a number of functions during germination. Here, we compared the absolute content and the fatty acid (FA) composition of pollen lipids of two species of flowering plants and spruce using GC-MS. The FA composition of spruce pollen differed significantly, including the predominance of saturated and monoene FAs, and a high proportion of very-long-chain FAs (VLCFAs). Significant differences between FAs from integumentary lipids (pollen coat (PC)) and lipids of gametophyte cells were found for lily and tobacco, including a very low unsaturation index of the PC. The proportion of VLCFAs in the integument was several times higher than in gametophyte cells. We found that the absolute content of lipids in lily pollen is almost three times higher than in tobacco and spruce pollen. For the first time, changes in the FA composition were analyzed during pollen germination in gymnosperms and angiosperms. The stimulating effect of H2O2 on spruce germination also led to noticeable changes in the FA content and composition of growing pollen. For tobacco in control and test samples, the FA composition was stable.

Type II arabinogalactans initiated by hydroxyproline-O-galactosyltransferases play important roles in pollen-pistil interactions.

Arabinogalactan-proteins (AGPs) are hydroxyproline-rich glycoproteins containing a high sugar content and are widely distributed in the plant kingdom. AGPs have long been suggested to play important roles in sexual plant reproduction. The synthesis of their complex carbohydrates is initiated by a family of hydroxyproline galactosyltransferase (Hyp-GALT) enzymes which add the first galactose to Hyp residues in the protein backbone. Eight Hyp-GALT enzymes have been identified so far, and in the present work a mutant affecting five of these enzymes (galt2galt5galt7galt8galt9) was analyzed regarding the reproductive process. The galt25789 mutant presented a low seed set, and reciprocal crosses indicated a significant female gametophytic contribution to this mutant phenotype. Mutant ovules revealed abnormal callose accumulation inside the embryo sac and integument defects at the micropylar region culminating in defects in pollen tube reception. In addition, immunolocalization and biochemical analyses allowed the detection of a reduction in the amount of glucuronic acid in mutant ovary AGPs. Dramatically low amounts of high-molecular-weight Hyp-O-glycosides obtained following size exclusion chromatography of base-hydrolyzed mutant AGPs compared to the wild type indicated the presence of underglycosylated AGPs in the galt25789 mutant, while the monosaccharide composition of these Hyp-O-glycosides displayed no significant changes compared to the wild-type Hyp-O-glycosides. The present work demonstrates the functional importance of the carbohydrate moieties of AGPs in ovule development and pollen-pistil interactions.

Differences in individual flowering time change pollen limitation and seed set in three montane wildflowers.

PREMISE: Changes to flowering time caused by climate change could affects plant fecundity, but studies that compare the individual-level responses of phenologically distinct, co-occurring species are lacking. We assessed how variation in floral phenology affects the fecundity of individuals from three montane species with different seasonal flowering times, including in snowmelt acceleration treatments to increase variability in phenology. METHODS: We collected floral phenology and seed set data for individuals of three montane plant species (Mertensia fusiformis, Delphinium nuttallianum, Potentilla pulcherrima). To examine the drivers of seed set, we measured conspecific floral density and conducted pollen limitation experiments to isolate pollination function. We advanced the phenology of plant communities in a controlled large-scale snowmelt acceleration experiment. RESULTS: Differences in individual phenology relative to the rest of the population affected fecundity in our focal species, but effects were species-specific. For our early-season species, individuals that bloomed later than the population peak bloom had increased fecundity, while for our midseason species, simply blooming before or after the population peak increased individual fecundity. For our late-season species, blooming earlier than the population peak increased fecundity. The early and midseason species were pollen-limited, and conspecific density affected seed set only for our early-season species. CONCLUSIONS: Our study shows that variation in individual phenology affects fecundity in three phenologically distinct montane species, and that pollen limitation may be more influential than conspecific density. Our results suggest that individual-level changes in phenology are important to consider for understanding plant reproductive success.

Are the floral morphology and anatomy of Galphimia australis, an atypical neotropical Malpighiaceae, associated to a new pollination syndrome?

The flowers of the species of Malpighiaceae in the Neotropical Region are relatively uniform in their morphology due to their dependence on oil-collecting bees as their main pollinators. However, many species of the genus Galphimia seem to have acquired a different floral syndrome, lacking markedly zygomorphic flowers and developed elaiophores in the calyx. Likewise, these species present anthers with great development, probably in response to the selection of pollinators that collect pollen. Galphimia australis incorporated some of these traits but also retained some residual characteristics typical of species pollinated by oil bees. This leads to many questions on how these flowers ensure their pollination. Inquiring about the reduction or modification of these characteristics allows us to understand how G. australis achieves a different pollination syndrome. In this research, we carry out a detailed morphological and anatomical study of the flowers and pollen grain devolvement of G. australis and floral visitors were observed and captured. Results were analyzed in order to determine how this species changed from the oil-floral syndrome, typical of neotropical Malpighiaceae, to one syndrome with pollen as the main reward.

Dynamics of endogenous levels and subcellular localization of ABA and cytokinins during pollen germination in spruce and tobacco.

We used the enzyme-linked immunosorbent assay (ELISA) to assess the level of endogenous hormones in spruce pollen, and immunolocalization and confocal microscopy to study hormone localization in spruce and tobacco pollen. During pollen activation, the levels of ABA, zeatin, and its riboside significantly decreased. After the initiation of polar growth, the levels of all cytokinins increased sharply; ABA level also increased. In dormant spruce pollen grains, zeatin and ABA were localized uniformly throughout the cytoplasm. Zeatin was not detected in the nuclei, and the antheridial cell showed higher levels than the vegetative cell; ABA signal was detected in the cytoplasm and the nuclei. In germinating pollen, both hormones were detected mainly in plastids. The similar pattern was found in growing pollen tubes; signal from ABA also had a noticeable level in the cytosol of the tube cell, and was weaker in the antheridial cell. Zeatin fluorescence, on the other hand, was more pronounced in the antheridial cell. In non-germinated grains of tobacco, zeatin was localized mainly in organelles. ABA in dormant pollen grains demonstrated uniform localization, including the nuclei and cytoplasm of both cells. After germination, zeatin was accumulated in the plasmalemma or cell wall. ABA signal in the cytoplasm decreased; in the nuclei, it remained high. In growing tubes, the strongest zeatin and ABA signals were observed at the plasma membrane. The differences in ABA and cytokinin localization between species and dynamic changes in their level in spruce pollen highlight the key spatial and temporal parameters of hormonal regulation of gymnosperm pollen germination.

Pollen-pistil interactions: It takes two to tangle but a molecular cast of many to deliver.

Explosive advances have been made in the molecular understanding of pollen-pistil interactions that underlie reproductive success in flowering plants in the past three decades. Among the most notable is the discovery of pollen tube attractants [1∗,2∗]. The roles these molecules play in facilitating conspecific precedence thus promoting interspecific genetic isolation are also emerging [3-5]. Male-female interactions during the prezygotic phase and contributions from the male and female gametophytes have been comprehensively reviewed recently. Here, we focus on key advances in understanding the mechanistic underpinnings of how these interactions overcome barriers at various pollen-pistil interfaces along the pollen tube growth pathway to facilitate fertilization by desirable mates.

Iron Supplement-Enhanced Growth and Development of Hydrangea macrophylla In Vitro under Normal and High pH.

Hydrangea macrophylla is a popular perennial ornamental shrub commercially grown as potted plants, landscape plants, and cut flowers. In the process of reproduction and production of ornamental plants, the absorption of nutrients directly determines the value of the ornamental plants. Hydrangea macrophylla is very sensitive to the content and absorption of the micronutrient iron (Fe) that affects growth of its shoots. However, the physiological activity of Fe as affected by deficiency or supplementation is unknown. This work aimed at preliminary exploring the relationship between Fe and photosynthesis, and also to find the most favorable iron source and level of pH for the growth of H. macrophylla. Two Fe sources, non-chelated iron sulfate (FeSO4) and iron ethylenediaminetetraacetic acid (Fe-EDTA), were supplemented to the multipurpose medium with a final Fe concentration of 2.78 mg·L-1. The medium without any Fe supplementation was used as the control. The pH of the agar-solidified medium was adjusted to either 4.70, 5.70, or 6.70, before autoclaving. The experiment was conducted in a culture room for 60 days with 25/18 °C day and night temperatures, and a 16-hour photoperiod provided at a light intensity of 50 mmol·m-2·s-1 photosynthetic photon flux density (PPFD) from white light-emitting diodes. Supplementary Fe increased the tissue Fe content, and leaves were greener with the medium pH of 4.70, regardless of the Fe source. Compared to the control, the number of leaves for plantlets treated with FeSO4 and Fe-EDTA were 2.0 and 1.5 times greater, respectively. The chlorophyll, macronutrient, and micronutrient contents were the greatest with Fe-EDTA at pH 4.70. Furthermore, the Fe in the leaf affected the photosynthesis by regulating stomata development, pigment content, and antioxidant system, and also by adjusting the expression of genes related to Fe absorption, transport, and redistribution. Supplementation of Fe in a form chelated with EDTA along with a medium pH of 4.70 was found to be the best for the growth and development of H. macrophylla plantlets cultured in vitro.

The evolution of flower longevity in unpredictable pollination environments.

Pollination requires a flower to remain open for long enough to allow for the arrival of pollinators. However, maintaining flowers costs energy and resources. Therefore, flower longevity, the length of time a flower remains viable, is critical for the outcome of plant reproduction. Although previous studies showed that the evolution of flower longevity depends on the rates of pollen deposition and removal, whether plants should increase or decrease flower life span when the pollination environment is unpredictable has not been explored. Moreover, the common hypothesis that an unpredictable pollination environment should select for increased flower longevity may be too simplistic since there is no distinction drawn between the effects of spatial and temporal variation. Adopting evolutionary game theory, we investigate the evolution of flower longevity under three types of variation: spatial heterogeneity, daily fluctuations within a flowering season and yearly fluctuations between flowering seasons. We find that spatial heterogeneity often selects for a shorter flower lifespan, while temporal fluctuations of fitness accrual rates at both daily and yearly time scales tends to favour greater longevity, although daily and yearly fluctuations have somewhat different effects. However, the presence of correlation between female and male fitness accrual rates seems to have no effect on flower longevity. Our work suggests that explicit measurements of spatial and temporal variation in both female and male functions may provide a better understanding of the evolution of flower longevity and reproduction.

Nutrient limitation of plant reproduction in a tropical moist forest.

Nutrient addition experiments indicate that nitrogen and phosphorus limit plant processes in many tropical forests. However, the long-term consequences for forest structure and species composition remain unexplored. We are positioned to evaluate potential long-term consequences of nutrient addition in central Panama where we have maintained a factorial nitrogen-phosphorus-potassium fertilization experiment for 21 yr and an independent study quantified the species-specific nutrient requirements of 550 local tree species. Here, we ask whether nutrients limit reproduction at the species and community levels. We also ask whether species-specific reproductive responses to nutrient addition are stronger among species associated with naturally fertile soils, which could contribute to a shift in species composition. We quantified species-level reproductive responses for 38 focal species in the 21st year of the experiment and community-level reproductive litter production for the first 20 yr. Species-level reproductive responses to nitrogen and potassium addition were weak, inconsistent across species, and insignificant across the 38 focal species. In contrast, species-level responses to phosphorus addition were consistently and significantly positive across the 38 focal species but were unrelated to species-specific phosphorus requirements documented independently for the same species. Community-level reproductive litter production was unaffected by nutrient addition, possibly because spatial and temporal variation is large. We conclude that phosphorus limits reproduction by trees in our experiment but find no evidence that reproductive responses to phosphorus addition favor species associated with naturally phosphorus-rich soils.

The biomechanics of pollen release: new perspectives on the evolution of wind pollination in angiosperms.

Evolutionary transitions from animal to wind pollination have occurred repeatedly during the history of the angiosperms, but the selective mechanisms remain elusive. Here, we propose that knowledge of pollen release biomechanics is critical for understanding the ecological and evolutionary processes underpinning this shift in pollination mode. Pollen release is the critical first stage of wind pollination (anemophily) and stamen properties are therefore likely to be under strong selection early in the transition. We describe current understanding of pollen release biomechanics to provide insights on the phenotypic and ecological drivers of wind pollination. Pollen release occurs when detachment forces dominate resistive forces retaining pollen within anthers. Detachment forces can be active or passive depending on whether they require energy input from the environment. Passive release is more widespread in anemophilous species and involves processes driven by steady or unsteady aerodynamic forces or turbulence-induced vibrations that shake pollen from anthers. We review empirical and theoretical studies suggesting that stamen vibration is likely to be a key mechanism of pollen release. The vibration response is governed by morphological and biomechanical properties of stamens, which may undergo divergent selection in the presence or absence of pollinators. Resistive forces have rarely been investigated for pollen within anthers, but are probably sensitive to environmental conditions and depend on flower age, varying systematically between animal- and wind-pollinated species. Animal and wind pollination are traditionally viewed as dichotomous alternatives because they are usually associated with strikingly different pollination syndromes. But this perspective has diverted attention from subtler, continuously varying traits which mediate the fluid dynamic process of pollen release. Reinterpreting the flower as a biomechanical entity that responds to fluctuating environmental forces may provide a promising way forward. We conclude by identifying several profitable areas for future research to obtain deeper insight into the evolution of wind pollination.

KATANIN and cortical microtubule organization have a pivotal role in early pollen tube guidance.

Following pollen deposition on the receptive surface of the stigma, pollen germinates a tube that carries male gametes toward the ovule where fertilization occurs. As soon as it emerges from the pollen grain, the pollen tube has to be properly guided through the pistil tissues so as to reach the ovule and ensure double fertilization. Chemical attractants, nutrients as well as receptor kinase-dependent signaling pathways have been implicated in this guidance. Recently, we showed in Arabidopsis that the microtubule severing enzyme KATANIN, by acting both on cortical microtubule (CMT) dynamics and cellulose microfibril (CMF) deposition, conferred particular mechanical properties to the papilla cell wall that act as active guidance factors. Here we confirm the importance of KATANIN and CMT orientation in pollen tube directionality by examining another katanin mutant.

Hydrogen peroxide in tobacco stigma exudate affects pollen proteome and membrane potential in pollen tubes.

ROS are known to be accumulated in stigmas of different species and can possibly perform different functions important for plant reproduction. Here we tested the assumption that one of their functions is to control membrane potential and provoke synthesis of unique proteins in germinating pollen. We used spectrofluorometry and spectrophotometry to detect H2 O2 in stigma exudate, quantitative fluorescent microscopy of pollen tubes and flow cytometry of pollen protoplasts to reveal effects on membrane potential, and a label-free quantification approach to study pollen proteome changes after H2 O2 treatment. We found that in both growing pollen tubes and pollen protoplasts exudate causes plasmalemma hyperpolarization similar to that provoked by H2 O2 . This effect is abolished by catalase treatment and the ROS quencher, MnTMPP. Inhibitory analysis indicates probable participation of Ca2+ - and K+ -conducting channels in the observed hyperpolarization. For a deeper understanding of pollen response, we analysed proteome alterations in H2 O2 -treated pollen grains. We found 50 unique proteins and 20 differently accumulated proteins that are mainly involved in cell metabolism, energetics, protein synthesis and folding. Observed hyperpolarization and proteome alterations agree well with previously reported stimulation of pollen germination by H2 O2 and sensitivity of Ca2+ - and K+ -conducting channels to this ROS. Thus, H2 O2 is one of the active substances in tobacco stigma exudate that stimulates various physiological processes in germinating pollen.

ROS and Ions in Cell Signaling during Sexual Plant Reproduction.

Pollen grain is a unique haploid organism characterized by two key physiological processes: activation of metabolism upon exiting dormancy and polar tube growth. In gymnosperms and flowering plants, these processes occur in different time frames and exhibit important features; identification of similarities and differences is still in the active phase. In angiosperms, the growth of male gametophyte is directed and controlled by its microenvironment, while in gymnosperms it is relatively autonomous. Recent reviews have detailed aspects of interaction between angiosperm female tissues and pollen such as interactions between peptides and their receptors; however, accumulated evidence suggests low-molecular communication, in particular, through ion exchange and ROS production, equally important for polar growth as well as for pollen germination. Recently, it became clear that ROS and ionic currents form a single regulatory module, since ROS production and the activity of ion transport systems are closely interrelated and form a feedback loop.

The molecular basis for allelic differences suggests Restorer-of-fertility 1 is a complex locus in sugar beet (Beta vulgaris L.).

BACKGROUND: Cytoplasmic male sterility (CMS) is a widely used trait for hybrid seed production in many crops. Sugar beet CMS is associated with a unique mitochondrial protein named preSATP6 that forms a 250-kDa complex. Restorer-of-fertility 1 (Rf1) is a nuclear gene that suppresses CMS and is, hence, one of the targets of sugar beet breeding. Rf1 has dominant, semi-dominant and recessive alleles, suggesting that it may be a multi-allelic locus; however, the molecular basis for differences in genetic action is obscure. Molecular cloning of Rf1 revealed a gene (orf20) whose protein products produced in transgenics can bind with preSATP6 to generate a novel 200-kDa complex. The complex is also detected in fertility-restored anthers concomitant with a decrease in the amount of the 250-kDa complex. Molecular diversity of the Rf1 locus involves organizational diversity of a gene cluster composed of orf20-like genes (RF-Oma1s). We examined the possibility that members of the clustered RF-Oma1 in this locus could be associated with fertility restoration. RESULTS: Six yet uncharacterized RF-Oma1s from dominant and recessive alleles were examined to determine whether they could generate the 200-kDa complex. Analyses of transgenic calli revealed that three RF-Oma1s from a dominant allele could generate the 200-kDa complex, suggesting that clustered RF-Oma1s in the dominant allele can participate in fertility restoration. None of the three copies from two recessive alleles was 200-kDa generative. The absence of this ability was confirmed by analyzing mitochondrial complexes in anthers of plants having these recessive alleles. Together with our previous data, we designed a set of PCR primers specific to the 200-kDa generative RF-Oma1s. The amount of mRNA measured by this primer set inversely correlated with the amount of the 250-kDa complex in anthers and positively correlated with the strength of the Rf1 alleles. CONCLUSIONS: Fertility restoration by sugar beet Rf1 can involve multiple RF-Oma1s clustered in the locus, implying that stacking 200-kDa generative copies in the locus strengthens the efficacy, whereas the absence of 200-kDa generative copies in the locus makes the allele recessive irrespective of the copy number. We propose that sugar beet Rf1 is a complex locus.

From theory to experiments for testing the proximate mechanisms of mast seeding: an agenda for an experimental ecology.

Highly variable and synchronised production of seeds by plant populations, known as masting, is implicated in many important ecological processes, but how it arises remains poorly understood. The lack of experimental studies prevents underlying mechanisms from being explicitly tested, and thereby precludes meaningful predictions on the consequences of changing environments for plant reproductive patterns and global vegetation dynamics. Here we review the most relevant proximate drivers of masting and outline a research agenda that takes the biology of masting from a largely observational field of ecology to one rooted in mechanistic understanding. We divide the experimental framework into three main processes: resource dynamics, pollen limitation and genetic and hormonal regulation, and illustrate how specific predictions about proximate mechanisms can be tested, highlighting the few successful experiments as examples. We envision that the experiments we outline will deliver new insights into how and why masting patterns might respond to a changing environment.

Plant traits moderate pollen limitation of introduced and native plants: a phylogenetic meta-analysis of global scale.

The role of pollination in the success of invasive plants needs to be understood because invasives have substantial effects on species interactions and ecosystem functions. Previous research has shown both that reproduction of invasive plants is often pollen limited and that invasive plants can have high seed production, motivating the questions: How do invasive populations maintain reproductive success in spite of pollen limitation? What species traits moderate pollen limitation for invaders? We conducted a phylogenetic meta-analysis with 68 invasive, 50 introduced noninvasive and 1931 native plant populations, across 1249 species. We found that invasive populations with generalist pollination or pollinator dependence were less pollen limited than natives, but invasives and introduced noninvasives did not differ. Invasive species produced 3× fewer ovules/flower and >250× more flowers per plant, compared with their native relatives. While these traits were negatively correlated, consistent with a tradeoff, this did not differ with invasion status. Invasive plants that produce many flowers and have floral generalisation are able to compensate for or avoid pollen limitation, potentially helping to explain the invaders' reproductive successes.