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PREMISE Heterospecific pollen transfer, the transfer of pollen between species, is common among co-flowering plants, yet the amount of pollen received is extremely variable among species. Intraspecific variation in heterospecific pollen receipt can be even greater, but we lack an understanding of its causes and fitness consequences in wild populations. METHODS We examined potential drivers of variation in heterospecific pollen receipt in Oenothera fruticosa. We evaluated the relationship between heterospecific and conspecific pollen receipt and considered how visitation by different pollinator groups, local floral neighborhood composition, and flowering phenology affect the total amount and proportion of heterospecific pollen received. Finally, we tested whether variation in heterospecific pollen receipt translated into lower seed production. RESULTS Heterospecific pollen was ubiquitous on O. fruticosa stigmas, but the amount received was highly variable and unrelated to conspecific pollen receipt. Heterospecific pollen receipt depended on pollinator type, the proportion of nearby conspecific flowers, and flowering date. Significant interactions revealed that the effects of pollinator type and neighborhood were not independent, further contributing to variation in heterospecific pollen. Naturally occurring levels of heterospecific pollen were sufficient to negatively impact seed set, but large amounts of conspecific pollen counteracted this detrimental effect. CONCLUSIONS Although selection could act on floral traits that attract quality pollinators and promote synchronous flowering in O. fruticosa, the risk of heterospecific pollen is equally dependent on local floral context. This work highlights how extrinsic and intrinsic factors contribute to intraspecific variation in heterospecific pollen receipt in wild plants, with significant fitness consequences.

Lush jungle flagship species, woody bamboos (Poaceae–Bambusoideae) are famed for their synchronous flowering as well as the extensive “bamboo forests” some species can form in tropical or temperate environments. In portions of their natural distribution, Bambusoideae members developed various adaptations to seasonality in environmental parameters, such as frost or seasonal drought. A new taxon, Laobambos calcareus, described here, is extremely novel in showing the first documented case of succulence in bamboos, with its ability to seasonally vary the volume of its stem depending on the quantity of water stored. Anatomical studies presented in this paper document this specificity at the cellular level. Though no flowers or fruits are known yet, unique morphological characteristics along with an investigation of its phylogenetic affinities using molecular data show that this new taxon should belong to a new genus herein described.

Bamboos are known as long-living monocarpic plants that exhibit synchronous flowering at long intervals. It has been reported that florivory has a critical effect on their seed production in bamboos, especially in small scale flowering patches. In this study, we aimed to determine species composition and life history of florivorous insects in multiple bamboo species. We collected the inflorescences of 12 bamboo species from 15 sites in Japan from 2017 to 2019 and recorded insect assemblages found in the flowers. Five different insect species were observed to feed on the flowers of bamboo species. Among these, the larvae of two Dicraeus species were the most widely observed florivorous insects of the bamboo species. The other insects included the larvae of Cecidomyiidae sp., which was frequently observed on Sasa species, and the other two insects were Epuraea submicrurula, and Dimorphopterus japonicus. These insects were oviposited on the florets during the budding period. In addition, predators and parasitoids were found in the bamboo flowers. Our findings suggest that the bamboos flowers were mainly consumed by dipteran larvae. Insect species composition and frequency varied among bamboo species and sites. Comparing the frequency of the florivorous insects among bamboo flowering patches, including mass flowering patches, in different areas is needed in future studies.

As the D genome progenitor of common wheat, Aegilops tauschii Cosson is geographically widespread in central Eurasia. In spite of intensive global studies, the origin and population structure of Ae. tauschii from China is still ambiguous. In this work, we detected 4245 single nucleotide polymorphism across 67 Ae. tauschii accessions from whole natural habitat to re-evaluate the population structure and phylogenetic relationship. As a result, Ae. tauschii accessions from Xinjiang were consistently allocated into sublineage 1E, revealing the easternmost of the natural distribution for Ae. tauschii wild population. Unexpectedly, the accessions from Yellow River region were firstly separated from L1 to be an independent cluster, the rest of which then subdivided into sublineages 1W and 1E. In addition, Ae. tauschii in this region exhibited high FST values with those in Central Asia, South Asia, and Xinjiang, respectively, ranging from 0.5863 to 0.8369. These results indicate that Ae. tauschii in Yellow River region might contain individual genetic variations absent in other sublineages, which could provide excellent gene resources for improvement in common wheat. The neighbor-joining tree based on the genetic distances indicated Ae. tauschii in Yellow River region to be closely related with AY57 accession from Turkmenistan, with bootstrap value of 96%. Moreover, a synchronous flowering time was observed in AY57 accession and those in Yellow River region. These results demonstrate that the accessions in Yellow River region, as an adventive population, may be directly radiated from the southern area of Turkmenistan.

Flowering phenology is an important life-history trait affecting plant reproductive performance and is influenced by various abiotic and biotic factors. Pre-dispersal seed predation and pollination are expected to impose counteracting selection pressure on flowering phenology, with pre-dispersal seed predation expected to favour off-peak flowering and pollination to favour synchronous flowering. Here we studied the effect of pre-dispersal seed predation by the beetle Byturus ochraceus, a specialist seed herbivore, on the flowering phenology of Geum urbanum. This forest understorey plant species is self-pollinating, so that the influence of seed predation can be studied independent from pollination. We measured in detail the timing and predation rate of individual flowers during two consecutive years in more than 60 individuals. We tested the hypotheses that pre-dispersal seed predation exerts selection for within-season compensatory flowering as well as for induced phenological avoidance in the following season. We found no indication for compensatory flowering within a growing season, but plants that experienced predation shifted their flowers to the end of the flowering season the subsequent year. This induced phenological avoidance points to a plastic response to pre-dispersal seed predation that may be adaptive. Importantly, the delay in flower production came at a cost, since flowers later in the season had a reduced seed output, presumably because of increasing light limitation following forest canopy closure. Synthesis. Herbivory by specialist enemies can cause serious fitness decline in hosts. We here show that induced shifts in phenology can form an important defense strategy against pre-dispersal seed predation. The induced mismatches between herbivore and host phenology are anticipated to be adaptive when herbivory is predictable across successive flowering periods.

Most apple trees (Malus domestica Borkh.) are self-incompatible and fruit yield depends on cross-pollination between genetically compatible cultivars with synchronous flowering. Flowering intensity can vary strongly among years due to the biennial bearing habit of the cultivars. The knowledge of the phenological stages and floral and pollen characteristics is essential to select suitable pollen donors. We evaluated the phenotypic variability of flowering-related traits (i.e., flowering phenology, flowering intensity, pollen production and pollen quality) in 45 apple cultivars over two successive flowering seasons. Large phenotypic variability was found among the studied cultivars indicating that the local germplasm collection provides a good source of genetic and phenotypic diversity. However, low correlations were observed between floral biology traits and, consequently, the improvement in one trait seems not to affect other traits. Some of the cultivars such as ‘Perurico’ and ‘Raxila Dulce’ regularly produced copious amounts of high-quality pollen which can improve the pollen load dispersion leading to a most effective pollination process. We did not identify statistically significant correlations between pollen attributes and the biennial bearing phenomenon. The large variation in bloom dates from year-to-year observed under a typical Oceanic climate makes it advisable to combine cultivars in new plantings.

Dendrocalamus strictus(Roxb.) Nees has started flowering and synchronous flowering can be observed in the hillslopes and roadside of Mussoorie and vicinity areas. The synchronous flowering ofD. strictuswas observed in few locations along hillslopes of Mussoorie – Dehradun roadway. The GPS locations of the site are 30024’55’ N and 7804’41’E, 30024’52” N and 7804’43” E and 30024’49” and 7804’43” E at an elevation of around 1130 msl. The bamboo clumps were overladen with flowers showing synchronous flowering.

In this study, the effect of hybridization on the interspecific differentiation of two species of red oaks, Quercus acutifolia and Q. grahamii, was evaluated. It is thought that hybridization is possible between these two species since they can inhabit adjacently and have periods of synchronous flowering. In addition, individuals with intermediate morphological attributes have been detected within their populations. To resolve this question, samples were collected from 280 adult individuals from 28 sampling locations: 17 of Q. acutifolia and 11 of Q. grahamii. To identify the individuals belonging to the parental species and those with the presence of hybridization, the individuals were genotyped with 10 nuclear microsatellite loci. To determine the patterns of leaf variation, two sets of morphological traits were considered: the first was 22 foliar morphological measurements, and the second was a geometric morphometry analysis using 40 two-dimensional pseudolandmarks. The results of the analysis of genetic allocation revealed that a large proportion of individuals from all populations showed evidence of introgression in their genomes. The morphological comparison showed that there was a clear differentiation between individuals classified as purebred members of the species Q. acutifolia and Q. grahamii. Individuals with evidence of primary hybridization (F1) were scarce and had morphologies similar to those of the Q. grahamii species. On the other hand, introgressed individuals (F2) seemed to be very similar to their genetically closest parents. The results show that the patterns of foliar morphological variation are not very useful for detecting hybridization events between species with continuous genetic exchange.

Background and Aims Daylength determines flowering dates. However, questions remain regarding flowering dates in the natural environment, such as the synchronous flowering of plants sown simultaneously at highly contrasting latitudes. The daily change in sunrise and sunset times is the cue for the flowering of trees and for the synchronization of moulting in birds at the equator. Sunrise and sunset also synchronize the cell circadian clock, which is involved in the regulation of flowering. The goal of this study was to update the photoperiodism model with knowledge acquired since its conception. Methods A large dataset was gathered, including four 2-year series of monthly sowings of 28 sorghum varieties in Mali and two 1-year series of monthly sowings of eight rice varieties in the Philippines to compare with previously published monthly sowings in Japan and Malaysia, and data from sorghum breeders in France, Nicaragua and Colombia. An additive linear model of the duration in days to panicle initiation (PI) and flowering time using daylength and daily changes in sunrise and sunset times was implemented. Key Results Simultaneous with the phyllochron, the duration to PI of field crops acclimated to the mean temperature at seedling emergence within the usual range of mean cropping temperatures. A unique additive linear model combining daylength and daily changes in sunrise and sunset hours was accurately fitted for any type of response in the duration to PI to the sowing date without any temperature input. Once calibrated on a complete and an incomplete monthly sowing series at two tropical latitudes, the model accurately predicted the duration to PI of the concerned varieties from the equatorial to the temperate zone. Conclusions Including the daily changes in sunrise and sunset times in the updated photoperiodism model largely improved its accuracy at the latitude of each experiment. More research is needed to ascertain its multi-latitudinal accuracy, especially at latitudes close to the equator.

Climate change is altering patterns of seed production worldwide with consequences for population recruitment and migration potential. For the many species that regenerate through synchronized, quasiperiodic reproductive events termed masting, these changes include decreases in the synchrony and interannual variation in seed production. This break-down in the occurrence of masting features harms reproduction by decreasing the efficiency of pollination and increasing seed predation. Changes in masting are often paralleled by warming temperatures, but the underlying proximate mechanisms are unknown. We used a unique 39-year study of 139 European beech (Fagus sylvatica) trees that experienced masting break-down to track the seed developmental cycle and pinpoint phases where weather effects on seed production have changed over time. A cold followed by warm summer led to large coordinated flowering efforts among plants. However, trees failed to respond to the weather signal as summers warmed and the frequency of reproductive cues changed fivefold. Less synchronous flowering resulted in less efficient pollination that further decreased the synchrony of seed maturation. As global temperatures are expected to increase this century, perennial plants that fine-tune their reproductive schedules based on temperature cues may suffer regeneration failures.

Background and AimsDaylength determines flowering dates. However, questions remain regarding flowering dates in the natural environment, such as the synchronous flowering of plants sown simultaneously at highly contrasting latitudes. The daily change in sunrise and sunset times is the cue for the flowering of trees and for the synchronisation moulting in birds at the equator. Sunrise and sunset also synchronise the cell circadian clock, which is involved in the regulation of flowering. The goal of this study was to update the photoperiodism model with knowledge acquired since its conception.MethodsA large dataset was gathered, including four 2-year series of monthly sowings of 28 sorghum varieties in Mali and two 1-year series of monthly sowings of eight rice varieties in the Philippines to compare with previously published monthly sowings in Japan and Malaysia, and data from sorghum breeders in France, Nicaragua, and Colombia. An additive linear model of the duration in days to panicle initiation (PI) using day length and daily changes in sunrise and sunset times was implemented.Key ResultsSimultaneous with the phyllochron, the duration to PI of field crops acclimated to the mean temperature at seedling emergence within the usual range of mean cropping temperatures. A unique additive linear model combining daylength and daily changes in sunrise and sunset hours was accurately fitted for any type of response in the duration to PI to the sowing date without any temperature input. Once calibrated on a complete and an incomplete monthly sowing series at two tropical latitudes, the model accurately predicted the duration to PI of the concerned varieties from the equatorial to the temperate zone.ConclusionsThe results of the updated photoperiodism model strongly supported the hypothesis that photoperiodism could be a combined response to day length and daily changes in sunrise and sunset times.

Coffee (Coffea arabica) flowers synchronously and flowers are only open for a few days before senescing. Flower petals often decompose easily, containing higher concentrations of nutrients relative to other plant tissues. Thus, a pulse of petals into the detrital pool could be beneficial for the decomposer community and accelerate decomposition processes. Our research assessed the magnitude of the pulse of petals within a shaded coffee farm, and the impact of petals on the litter arthropod community and on the rate of leaf litter decomposition. Three plots of 12 coffee plants were monitored throughout the flowering period to estimate the magnitude of the bloom. Pitfall traps were used to assess the litter arthropod community before and after flowering. Finally, litterbags with C. arabica leaves alone and C. arabica leaves with flower petals were used to compare the effect of petals on decomposition rates. The average number of flowers open per plant at the peak of the bloom was 792 flowers. When scaling to obtain an estimate per hectare in a year, our results indicate flower petals could contribute 26.27 kg of nitrogen, 2.03 kg of phosphorus, and 26.7 kg of potassium. The leaf litter community did not change during our sampling, suggesting that any community effects may be acting on a longer time scale or smaller spatial scale. Leaf litter decomposed nearly three times as quickly in litterbags that included flower petals, relative to litterbags with only C. arabica leaf litter in the first month and twice as fast in the second month. The rate of decomposition with petals exceeded the rate of decomposition without petals and was highest after one month, though the benefit continued after two months. Our results demonstrate that the presence of flower petals can accelerate short‐term decomposition processes.

Bamboo is a perennial flowering plant with a distinctive life cycle: many bamboo species remain in the vegetative phase for decades, followed by mass synchronous flowering and subsequent death. The phenomenon of bamboo flowering is not fully understood, but its periodicity is a major research focus. Here, we collected information on bamboo flowering events by investigating historical documents and field studies at the Bamboo Research Institute of Nanjing Forestry University. We compiled information on more than 630 flowering events, 124 of which accurately recorded the flowering cycle time. We summarized the specific flowering cycles of 85 bamboo species, as well as four kinds of bamboo flowering habits in detail. We present a theory of the bamboo flowering cycle and discuss the reasons for the observed variations in bamboo flowering. This review also introduces two mechanisms by which bamboo forests are rejuvenated after flowering and explains the flowering phenomena of bamboo forests using the bamboo flowering cycle theory. Finally, we present suggestions for forest management strategies. Bamboo flowering is a normal physiological phenomenon, even though it has unique elements compared with flowering in other plants. The results presented here provide valuable reference material for understanding bamboo flowering and its periodicity.

Quantifying historic increases in water-limited potential yield (PYw) achieved through breeding provides insight into associated changes in physiology and can assist with future cultivar improvement. We compared PYw of bread wheat cultivars popular in southern New South Wales released between 1901 and 2014. In both 2015 and 2016, cultivars were sown at multiple sowing dates to allow comparisons to be made at a consistent optimal flowering date (early October), and thus control for the large differences in life cycle duration. Seasonal conditions were close to average in 2015 and extremely favorable in 2016. In both, grain yield increased across the historic period studied at 26 kg/ha per annum, regardless of whether a common sowing date or flowering date was used. Yield gain was not linear, and there was a period of rapid yield increase during the middle of the 20th century, that culminated with the release of semi-dwarf cultivars. Yield gain was relatively slower from the 1980s until the present day, possibly due to selection for grain quality traits (grain size) at the expense of grain number. Historic yield increases were not associated with earlier flowering, but with an interplay between greater grain number/m2 and greater grain weight which was the result of increased partitioning of assimilates to spikes, and greater number of grains per unit spike weight (fruiting efficiency). Greater partitioning to the spike in modern cultivars was associated with reduced dry matter (DM) production prior to flowering. Modern cultivars have a less stable flowering time across sowing dates, and shorter life cycle, but improved partitioning in modern cultivars appeared decoupled from shorter developmental phases prior to flowering. The performance of the novel vernalisation sensitive cultivar Longsword showed that future yield gain may be achieved through the combination of early sowing and slow development, increased DM production and superior partitioning to grain.

Sympatric plant species that flower at the same time in highly seasonal environments are subject to competitive interference. Many species of the genus Psychotria (Rubiaceae) are sympatric and have an aggregated flowering period, which may have a strong influence on interactions among these species and their pollinators. We assessed the strategies of sympatric species of Psychotria to segregate or share pollinators, and the consequences for intra- and interspecific pollen flow. We sampled pollinators and analyzed flowering phenology, floral tube length, pollinator tongue length and floral nectar production of three sympatric species of Psychotria in the understory of a tropical forest in Brazil. We also marked flowers with fluorescent powder to monitor the flow of pollen. The studied species of Psychotria exhibited a short synchronous flowering period, with the sharing of pollinators and interspecific pollen exchange. The prevalence of shared or unshared pollinators and of intra- or interspecific pollen exchange varied among the studied species. Variation in floral tube length and nectar was not enough to hamper the sharing of most pollinators and pollen flow between Psychotria nitidula and P. hoffmannseggiana. Non-shared pollinators were more common in flowers of P. prunifolia, probably due to its longer floral tube, which can impede the access of shared pollinators. The higher offer of floral nectar by P. prunifolia makes this species more attractive to a greater number of flower visitors. Pollinator sharing seems to have no negative effect on intraspecific pollen flow and on the reproductive success of the studied synchronopatric species of Psychotria.

Bamboos are widely distributed in mainland Southeast Asia and have abundant biomass. They are characterized by prolonged vegetative growth and semelparity. Where bamboos are dominant, their synchronous flowering and death has a major impact on forest vegetation. Although the small-scale dynamics of this process have become clearer in recent years, the history, geographical scale and synchronicity of bamboo flowering over broad areas remains unknown. This study focused on the flowering history of six bamboo species, Bambusa tulda, Cephalostachyum virgatum, Dendrocalamus hamiltonii, Dendrocalamus membranaceus, Indosasa sinica and Oxytenanthera parvifolia, over 40 years across a broad area of northern Laos. We also examined the synchronicity of flowering in D. membranaceus. We visited 49 villages in northern Laos and surveyed knowledgeable inhabitants about bamboo flowering history. The timing, scale and synchronicity of gregarious flowering varied among species. D. hamiltonii and D. membranaceus showed higher flowering synchronicity than other species. All the species except I. sinica had both sporadic and gregarious flowering traits, and showed conspicuous variability in their flowering scale. The flowering bamboo population at two gregarious flowering sites for D. membranaceus was surveyed. While this species had the highest synchronicity in this study, its synchronicity was lower than other species in previous studies worldwide. We found that the gregarious flowering of bamboos in northern Laos over the last 40 years showed lower synchronicity than bamboo flowering reported in other areas of the world. The historical dynamics and scale of bamboo flowering must be further clarified to understand the vegetation composition of this area.

To solve the issue of insufficient pollinating of insects for the oil tree peony &lsquo, Feng Dan&rsquo, (Paeonia ostii T. Hong et J.X. Zhang) and improve its seed set and yield, we conducted observations from 2017 to 2018 to investigate the relationship between honey bee (Apis mellifera L.) foraging behavior and diurnal activity. We compared the single-fruit seed set ratio among three flower types on the same plants of the oil tree peony, which flowered simultaneously, in three pollination areas (bee pollination, natural field pollination, and controlled pollination by pollinators) and in a net room under self-pollination, wind pollination and bee pollination. Apis mellifera exhibited short single visitations, long visitations to a single flower and repeated visits to flowers of the oil tree peony. The number of flower visits of A. mellifera was significantly and positively yet weakly correlated with the number of stigma visits (2017: r = 0.045, p &lt, 0.05, 2018: r = 0.195, p &lt, 0.01). The seed set of oil tree peony follicles in the A. mellifera pollination area was significantly higher than that in the natural pollination field area and the control net rooms. On the same oil tree peony plant with synchronous flowering, the percent seed set of follicles pollinated by A. mellifera at a high density was significantly higher than that resulting from wind pollination and self-pollination.

Made available in DSpace on 2019-10-04T11:57:23Z (GMT). No. of bitstreams: 0 Previous issue date: 2019-03-01 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) The seasonal timing of reproductive events in plants is explained by exogenous factors (i.e. climate) and endogenous characteristics. Arecaceae family is an important component of the tropical savanna flora, but the reproductive phenology of these plant species is not well understood. We aimed to: (i) test whether flowering and fruiting timing of the palms Syagrus comosa (Mart.) Mart., Syagrus flexuosa (Mart.) Becc. and Syagrus glazioviana (Mart.) Becc. were seasonal and correlated with precipitation; and (ii) investigate if closely related species overlapped in flowering and fruiting. The study was carried out during four years in three tropical woodland savanna sites in Brazil (Cerrado). At each of the three sites, we randomly tagged 20 adult individuals of each species and monthly monitored them for reproductive phenological events. We counted the number of flowers and of fruits and we compared these data with climatic records (precipitation). To test whether the three palm species flowered and fruited uniformly throughout the year, we applied the Rayleigh Z test. We correlated total rainfall of the month with number of flowers or fruits produced using a Spearman correlation test. Flowering and fruiting timing of the species during the years and across sites were mostly aseasonal and were in general not influenced by precipitation. These palm species had synchronous flowering but did not have synchronous fruiting. Because of the year-round fruit production, S. comosa, S. flexuosa and S. glazioviana might be fundamental species to the maintenance of frugivores. The synchronized flowering is an effective means of attracting pollinators and satiating florivores, improving plant reproductive success. The shifted fruiting peaks may emphasize the role of these palms in providing food for frugivores during the year. Univ Brasilia, Inst Ciencias Biol, Dept Ecol, Campus Darcy Ribeiro, BR-70910970 Brasilia, DF, Brazil Univ Sao Paulo, Dept Ecol, Rua Matao 321,Travessa 14, BR-05508090 Sao Paulo, SP, Brazil Univ Catolica Brasilia, PEA, BR-71966700 Aguas Claras, DF, Brazil FAPESP: 2015/24802-4

Plant fitness is reduced by pollen limitation when the amount and quality of pollen deposited on stigmas is restricted. Pollen limitation has direct implications in mating system and floral evolution, and negatively affects population dynamics. We assessed pollen limitation in the cactus Ariocarpus kotschoubeyanus from the western Chihuahuan Desert. We performed a supplementary pollen treatment then compared outcomes with naturally pollinated flowers using generalized linear models (GLM) and a pollen limitation index (L). Floral aperture was compared between days of anthesis using a single ANOVA, whereas nectar production was contrasted between covered/uncovered flowers and days of anthesis using a factorial ANOVA. Results of both GLM and L show that seed set proportion decreases 0.22 as a result of pollen limitation in natural pollinated flowers contrasted with pollen-supplemented flowers. Most flowers opened two days, and floral aperture between the first and second day varied slightly. Nectar...

Heterodichogamous reproduction in plants involves two flowering morphs, reciprocal in their timing of male and female sexual functions. The degree of synchrony in floral sex phase, within and between individuals of each morph, determines the flowers&rsquo, potential fertilization partners. Complete within-morph synchrony enables across-morph mating alone, whereas unsynchronized floral sex phases may allow fertilization within a plant individual (geitonogamy) or within a morph. We documented the disruption of flowering synchrony in the heterodichogamous Ziziphus spina-christi towards the end of its seven-month flowering season. This desert tree has self-incompatible, protandrous, short-lived (2-day) flowers that open before dawn (&lsquo, Early&rsquo, morph) or around noon (&lsquo, Late&rsquo, morph). We counted flowers in the male and female phase on flowering branches that were sampled monthly during the 2016&ndash, 2018 flowering seasons. In 2018, we also tagged flowers and followed their sex-phase distributions over two days at the start, middle, and end of the season. The switch to the female phase was delayed at the end-season (November-December), and 74% of the flowers did not develop beyond their male phase. Differences in male-phase duration resulted in asynchrony among flowers within each tree and among trees of both flowering morphs. Consequently, fertilization between trees of the same morph becomes potentially possible during the end-season. In controlled hand-pollination assays, some within-morph fertilizations set fruit. The end-season breakdown of synchronous flowering generates variability within morphs and populations. We suggest that this variability may potentially enable new mating combinations in a population and enhance its genetic diversity.

Premise Sexual dimorphism in flowering phenology traits may have evolved under sexual selection and vector-mediated selection. The conspicuous sexual dimorphism and sex-specific selection pressures in flowering phenology traits have been investigated mainly in entomophilous dioecious plants, whereas little is known about this in anemophilous plants. Methods We examined sexual dimorphism in flowering onset, flowering peak, flowering duration, maximum proportion of open flowers per inflorescence branch, maximum proportion of newly opening flowers on a given date per branch, and longevity of individual flowers in natural Rumex acetosa populations. Correlations between flowering phenology traits and the degree of flowering overlap with the opposite sex were examined. We also tested whether the overlap of female flowering with male flowering enhanced seed set in female plants. Results Little sexual dimorphism was observed in flowering onset, peak, duration, and maximum proportion of newly opening flowers. Females had greater floral longevity and greater maximum proportion of open flowers than males. Flowering overlap with the opposite sex significantly increased with the maximum proportion of newly opening flowers and decreased with temporal deviation in the flowering peak in both sexes. Females with greater flowering overlap with males set more seeds in two of the three study populations. Conclusions In wind-pollinated R. acetosa, little sexual dimorphism in phenological traits may have evolved to achieve synchronous flowering with the opposite sex. Our results suggest that, in angiosperms, not only common selection but also anemophily-specific selection may shape little sexual dimorphism in R. acetosa, unlike in entomophilous plants.

A supra-annual, community-level synchronous flowering prevails in several parts of the tropical forests of Southeast Asia and its evolution has been hypothesized to be linked to pollinator shifts. The aseasonal Southeast Asian lowland rainforests are dominated by Dipterocarpaceae, which exhibit great floral diversity, a range of pollination syndromes and include species with annual and supra-annual gregarious flowering. Phylogenetic relationships within this family are still unclear, especially in the tribe Shoreeae. Here, we develop a pipeline to maximize recovery of genome-wide SNPs from restriction-site associated DNA sequencing (RADseq) in non-model organisms across wide phylogenetic scales. We then infer phylogenomic relationships in the tribe Shoreeae using both traditional and coalescent analyses. The phylogenetic trees obtained with these methods are congruent to each other and highly resolved. They allow reconstructing the evolutionary patterns of floral traits (number of stamens, anther structure and anther/appendage size) in the group. Our inferences indicate that species with many stamens, but smaller, globose anthers and longer appendages and have evolved multiple times from species with fewer stamens, but larger, oblong anthers and shorter appendages. This could have happened in parallel to iterative shifts in pollinators across the uncovered phylogeny from larger, longer generation to smaller, shorter-generation insects that can quickly build up the necessary population sizes during mass flowering episodes.

Caesalpinia crista L., commanly known as Gray Nicker, is an oligohaline mangrove associate confined to landward marginal areas of the Coringa Mangrove Forest, Andhra Pradesh, India. The flowering occurs during the wet season from June to November. The flowers are hermaphroditic, self-compatible and exhibit a mixed breeding system. The floral characteristics that constitute melittophilous pollination syndrome include diurnal anthesis, slight fragrance, zygomorphy, yellow petals, with a flag petal displaying a conspicuous nectar guide, and the presence of nectar with a high sugar concentration. Extra-floral nectar along the rachis is an additional attractant and is easily perceivable by bees. The plant is pollinated almost exclusively by bees, especially carpenter bees. The floral characteristics such as free petals, fully exposed stamens with dry and powdery pollen grains and hairy stigma facilitate anemophily which is effective due to high winds during the rainy season. The prolific growth and near synchronous flowering at population level contribute to pollen availability in huge quantities and enable anemophily as an effective mode of pollination. The functionality of melittophily and anemophily together constitutes ambophily. Hand-pollination experiments indicated that the plant is principally out-crossing. The natural fruit set does not exceed 10%; this lowest percentage could be partly due to flower-feeding by the beetle, Mylabris phalerata. The fruits are indehiscent, 1-seeded, which are buoyant and are not dispersed far away from the parental sites. The viable seeds produce new plants in the vicinity of parental plants during the rainy season. This plant builds up its population as small patches or in pure stands and hence is important in building landward mangrove cover.

Cattails ( Typha spp.) in northeastern North American wetlands are increasingly dominant, partly because of hybridization between Typha latifolia and Typha angustifolia which results in the widespread and successful hybrid T. × glauca . Both parental species are protogynous, and previous studies have shown that T. angustifolia flowers earlier than T. latifolia. Nevertheless, experimental studies have shown that hybridization is overwhelmingly asymmetric, involving T. angustifolia female flowers and T. latifolia pollen which should have minimal overlap in the times at which they are produced. In this study we surveyed two Typha stands in eastern North America, and at both sites found substantial overlap in the times at which the parental species and the hybrids shed pollen and presumably are receptive to fertilization; this means that flowering time is not a prezygotic barrier to either the formation of hybrids or their subsequent backcrossing to parental species. Consistent with experimental studies, all hybrids had T. angustifolia as their maternal parent. Our results suggest that reproductive barriers between Typha spp. are evolving.

SUMMARYCurrent agricultural practices rely on crops with developmental phenologies adapted to local climate, photoperiods and soils; however, global climate change will alter some abiotic factors (e.g. temperature and precipitation). Previously adapted varieties may be poorly prepared for these changing conditions, if such conditions induce mismatched phenologies. Crops that depend on cross-pollination and synchronous flowering may be most susceptible, e.g. monoecious plants have separate male and female flowers, and changes in flowering synchrony may alter yield. Using genetically diverse (open-pollinated (OP)) and genetically homogeneous (hybrid) varieties of a monoecious crop, courgette, also known as zuchinni (Cucurbita pepo), phenological responses to experimentally manipulated moisture conditions were explored in an agricultural context. Under drier and wetter conditions, the hybrid courgette plants shifted towards a male-biased floral sex ratio due to the reduced production of female flowers. However, flowering synchrony and fruit production were unaffected by moisture treatment in both varieties. The hybrid and OP varieties differed in many traits related to floral sex ratios, phenology, synchrony and fruit production. Further, the OP variety displayed more phenotypic variation than the hybrid in many traits. Being in a population context rather than relying on self-pollination increased the availability of potential mates for a given female flower in both the hybrid and, particularly, the OP variety. Thus, the increased genetic diversity found in OP v. hybrid varieties may buffer the possible environmental effects on flowering synchrony within a cropping context. Finally, the likelihood of female flowers setting fruit increased with the number of male flowers within a population, and the rate of increase was higher in the hybrid variety. In summary, climate change is predicted to reduce investment in female function in some monoecious crops and genetically diverse varieties may play an important role in maintaining reproductive synchrony in altered environments.

The ornamental value of florist azalea depends strongly on its synchronous flowering. This quality demand is however not always met. A clear cut direct cause is seldom found; interaction between several elements related to the culture conditions should be at the base. In this experiment the application of plant growth regulators (PGR) were tested on two cultivars, ‘H. Vogel’ (early flowering) and ‘Kint’ (late flowering). Six applications with 2.25 g/l chloormequat were combined with 4 applications with 0.012 g/l paclobutrazol. A control group was not treated with any PGR. Microscopic observations showed that flower initiation in PGR treated plants was enhanced by 12 days for ‘H. Vogel’, but was unchanged for ‘Kint’. Differentiation was only slightly enhanced (2-4 days) compared to the control plants. When the floral primordia were fully developed cold treatments (7°C for 2 to 8 weeks) to fulfill flower bud dormancy requirements were applied. Results show that the late flowering cultivar ‘Mw. Kint’ has a stronger dormancy than the early flowering cultivar ‘H. Vogel’. Subsequently a longer period at 7°C is necessary for ideal flowering. For both ‘Mw. Kint’ and ‘H. Vogel’, PGR treated plants have a stronger dormancy, resulting in delayed flowering when forcing the plants at 21°C.

In order to clarify spatial and temporal patterns in the flowering process of S. veitchii var. hirsuta, the authors investigated the flowering of the species at a regional level in a mountainous area of Kyoto City, and at population/individual culm levels at experimental forest stations within the same municipal region. S. veitchii var. hirsuta flowered in several separate areas spanning ranges between several and more than 10 km north–south and east–west from 2004 to 2007. Sporadic flowering occurred the year before mass flowering. In the mass-flowering year, 98% of the culms in an S. veitchii var. hirsuta population flowered, and the other 2% or so flowered in the years before and after mass flowering. These results show a spatiotemporal synchronous flowering pattern (with most culms of populations gregariously flowering in a year over a large area) and an asynchronous flowering pattern (with a small percentage of the culms of populations flowering before and after the mass-flowering year) for S. veitchii var. hirsuta. It was also clarified that the year and scale of mass flowering differ by area, and that mass flowering occurs in individual areas in successive years. The survey performed at the individual culm level revealed that the mean numbers of open florets and attached seeds per culm showed two peaks from April to July, suggesting that S. veitchii var. hirsuta flowering events occur twice a year.

Accurately estimating the contribution of pollinators to production in crop species is important but could be challenging for species that are widely cultivated. One factor that may influence the pollinator-production relationship across regions is phenology, or the timing of recurring biological events, because crop phenology can be proximately controlled by climatic variables and phenology can affect plant reproductive success. For the economically important crop, coffee (Coffea arabica), at least three aspects of flowering phenology (onset, density and frequency) are influenced by precipitation, which varies across coffee’s cultivated range. Of these aspects of flowering phenology, flower density may particularly impact production in coffee because high-density flowering can severely limit outcrossing which is a major contributor to high yields and larger, high quality beans. We studied the C. arabica coffee plant-pollinator interaction over 3 years and across two distinct types of coffee blooms: (1) low-density, synchronous flowering and (2) high-density, synchronous (mass) flowering. Bee species richness was similar for four out of five flowering periods (9.8 ± 2.7 95% CI), but nearly tripled during one high-density flowering period (26 ± 8.6 95% CI). During low-density flowering coffee fruit set rates were varied, but when coffee flowered at high-density, initial fruit set rates remained close to 60% (the rate obtained from manual self-pollination of coffee flowers in pollination experiments). We discuss how changing precipitation patterns may alter coffee flowering phenology and the coffee plant-pollinator relationship, providing insight into how climate change may influence this interaction as well as the resultant coffee production.

Invasive plant species can potentially exert competitive or facilitative effects on insect pollination services of native species. Factors that influence these effects include the degree of shared pollinator species, synchronous flowering phenology, similar flower morphology and color, relatedness of invasive and natives, and showiness and densities of flowers. We investigated such plant-pollinator dynamics by comparing the invasive Lespedeza cuneata and three native congeners, all sympatric with synchronous flowering, using in situ populations over 2 years during peak floral displays. Insect visitation rates of the invasive were significantly higher per plant in both years than on the native species. The invasive exerted a competitive effect on visitation of the two native species with fewer shared pollinators, and a facilitative effect on visitation of the native species with the highest degree of shared insect visitors. Positive correlations were found between floral density and visitation rate per plant in all the native species. Although no such correlation was found for the invasive, floral density in L. cuneata was at least twenty times higher than in the native species and likely saturated the response of the pollinator community. Analyses of insect visitor taxonomic data indicated the insect communities visiting each of the Lespedeza species were generally similar though with species-specific differences. The main exception was that the common honeybee, Apis mellifera, was a primary visitor to the invasive plant species, yet was never observed on the native Lespedeza species.

SUMMARYThe results of research into the water relations of cocoa are reviewed in the context of drought mitigation and irrigation need. Background information on the centres of production of the cocoa tree, and the role of water in crop development and growth processes, is followed by reviews of the effects of water stress on stomatal conductance, leaf water status and gas exchange, together with drought tolerance, crop water use and water productivity. Leaf and shoot growth occur in a series of flushes, which are synchronized by the start of the rains following a dry season (or an increase in temperature), alternating with periods of ‘dormancy’. Flowering is inhibited by water stress but synchronous flowering occurs soon after the dry season ends. Roots too grow in a rhythmic pattern similar to that of leaf flushes. Roots can reach depths of 1.5–2.0 m, but with a mass of roots in the top 0.2–0.4 m, and spread laterally >5 m from the stem. Stomata open in low light intensities and remain fully open in full sunlight in well-watered plants. Partial stomatal closure begins at a leaf water potential of about −1.5 MPa. Stomatal conductance is sensitive to dry air, declining as the saturation deficit increases from about 1.0 up to 3.5 kPa. Net photosynthesis and transpiration both consequently decline over a similar range of values. Little has been published on the actual water use of cocoa in the field. Measured ETc values equate to −1only, whereas computed ETc rates of 3–6 mm d−1in the rains and −1in the dry season have also been reported. Despite its sensitivity to water stress, there is too a paucity of reliable, field-based published data of practical value on the yield responses of cocoa to drought or to irrigation. With the threat of climate change leading to less, or more erratic, rainfall in the tropics, uncertainty in yield forecasting as a result of water stress will increase. Social, technical and economic issues influencing the research agenda are discussed.

Mango flowering is an important physiological event that sets the start of fruit production. Initiation is the first event that takes place for mangoes to flower. Coincident with shoot initiation, induction occurs based on the conditions present at the time of initiation. Numerous studies with mango trees support the existence of a florigenic promoter (FP) that is continuously synthesized in mango leaves and induces flowering. Translocation experiments suggest that the FP is carried from leaves to buds in phloem. Induction appears to be governed by the interaction of the FP and a vegetative promoter (VP). The FP is translocated as far as 100 cm in subtropical conditions and 52 cm in tropical conditions. In the tropics, floral induction occurs in stems that have attained sufficient time in rest since the previous flush. The age of the last flush is the primary factor governing flowering in the tropics as evidenced by experiments in Colombia. Tip pruning is ideal to synchronize vegetative flush events in the canopy. Potassium nitrate (KNO 3 ) has been shown to stimulate flowering in sufficiently mature stems. Tip pruning and foliar applied KNO 3 are effective methodologies that induce synchronous flowering especially in Colombia. Cool temperatures are important for mango floral induction under subtropical conditions. Mangoes grown in the low-latitude tropics rely less on low temperature. Soil and leaf analyses should be conducted to evaluate the nutrient status of trees.

Synchronous monocarpy in long-lived plants is often associated with pollination by wind, in part because infrequent mass flowering may satiate pollinators. Selfing in synchronous monocarps may provide reproductive assurance but conflict with the benefits of outcrossing, a key evolutionary driver of synchrony. We predicted that animal-pollinated species with synchronous flowering would have unspecialised flowers and attract abundant generalised pollinators, but predictions for selfing and outcrossing frequencies were not obvious. We examined the pollination biology of Isoglossa woodii (Acanthaceae), an insect-pollinated, monocarpic herb that flowers synchronously at 4-7-year intervals. The most frequent visitor to I. woodii flowers was the African honeybee, Apis mellifera adansonii. Hand-pollination failed to enhance seed production, indicating that the pollinators were not saturated. No seed was set in the absence of pollinators. Seed set was similar among selfed and outcrossed flowers, demonstrating a geitonogamous mixed-mating strategy with no direct evidence of preferential outcrossing. Flowers contained four ovules, but most fruits only developed one seed, raising the possibility that preferential outcrossing occurs by post-pollination processes. We argue that a number of the theoretical concerns about geitonogamous selfing as a form of reproductive assurance do not apply to a long-lived synchronous monocarp such as I. woodii.

Sweet cherry (Prunus avium) is a member of the Rosaceae family, with a gametophytic self-incompatibility system that strongly affects pollination and fruit set. Alleles at the S-locus control this system, and fertilization does not occur if the S-allele of a haploid pollen gamete matches either S-allele of the diploid maternal pistil. To produce fruit, self-incompatible cherry trees require nearby cross-compatible trees with synchronous flowering. In cherry orchards, two or more cross-compatible pollinizer cultivars are therefore usually inter-planted with the main cultivar. Fortunately, self-compatibility exists, the result of a mutation of one of the alleles at the S-locus, permitting the breeding of self-compatible cultivars that do not require pollinizer trees. The Washington State University (WSU) sweet cherry breeding program seeks to produce self-compatible cultivars (in addition to superior fruit quality and other trait improvements) and desires an early detection system for self-compatible seedlings. PCR-based S-genotyping that included primers for detecting self-compatibility was conducted for 243 seedlings from crosses made in 2004 that initiated this modern breeding program. While self-compatible seedlings were identified, a large proportion of seedlings resulted from unintended parentage, with implications for future breeding strategies.