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Premise: Volatile emissions from flowers and fruits play a key role in signalling to animals responsible for pollination and seed dispersal. Here, we investigated the pollination biology and chemical ecology of reproduction in Apodolirion buchananii, an African amaryllid that flowers in a leafless state soon after grassland vegetation is burnt in the dry late-winter season., Methods: Pollinators were identified through field collection and pollen loads were quantified. Floral traits including spectral reflectance and scent chemistry were documented. Bioassays using cup traps were used to test the function of floral volatiles. Fruiting biology was investigated using controlled hand-pollination experiments and chemical analysis of fruit scent. Seed germination was scored in greenhouse trials. Seed dispersal was monitored using observations and camera trapping., Results: The sweetly scented white flowers of A. buchananii are pollen-rewarding and pollinated mainly by a diverse assemblage of bees. Cup-trap experiments demonstrated that pollinators are attracted to phenylacetaldehyde, the dominant volatile in the floral scent. Plants are shown to be self-incompatible, and the fleshy fruits were found to emerge from the soil six months after pollination during the peak of the summer rains. Fruits emit a diverse blend of aliphatic and aromatic esters and contain large fleshy recalcitrant seeds which germinate within days of fruits splitting open. Seed dispersal by ants was recorded., Conclusions: This first account of the reproductive biology of a species in the genus Apodolirion highlights an outcrossing mating system involving bees attracted to color and scent as well as the unusual fruiting biology and ant-mediated system of seed dispersal., (© 2024 The Author(s). American Journal of Botany published by Wiley Periodicals LLC on behalf of Botanical Society of America.)

Premise: There are advantages to flowering early in the spring, including greater pollinator fidelity and longer fruit maturation time. But plant phenology has advanced in recent years, making many plants vulnerable to freezing damage from late frosts., Methods: To determine the costs and benefits of flowering early in the growing season, we exposed Prunus pumila plants to two freezing treatments and a delayed flowering treatment in subsequent years. Data were collected on ovary swelling, fruit production, and pollinator visitation on hand- and open-pollinated plants in all treatments. We also measured tissue damage after freeze events., Results: Our results suggest that flowering time and temperature affect reproductive success, with fewer fruits produced after hard freezes. The same was not true for light freezes, which had minimal impact on reproduction. Freezing damage to plants after a hard freeze did affect the number of dipteran pollinators but not the overall pollinator visitation rate. Despite the clear impact of freezing temperatures on plant reproduction, flowering early provided an advantage in that reproductive output decreased with delayed flowering., Conclusions: Our findings suggest that Prunus pumila will retain the ability to attract pollinators and produce viable seeds if exposed to false spring conditions that involve a light freeze, but hard freezes may reduce yield by an order of magnitude. Although the advantages to flowering early may outweigh the risk of freezing damage under current conditions, it is possible that flower viability may be constrained under continued climate warming., (© 2024 The Author(s). American Journal of Botany published by Wiley Periodicals LLC on behalf of Botanical Society of America.)

Premise: In plants, within-individual trait variation might result from mechanisms related to ontogenetic contingency, i.e., to the position of a particular structure within the plant, previous developmental events, and/or the developmental environment. Flower position within inflorescences as well as inflorescence position within plants can influence resource provisioning, phenology, biotic interactions, and reproductive success. Despite the potential implications of within-individual variation in plant reproductive phenotypes, its causes and effects on reproductive success are still little explored., Methods: We assessed how reproductive success, in terms of fruit and seed set, and seed predation of 5883 flowers in Lathyrus vernus were influenced by their position within and among racemes, to what extent relationships between flower position and reproductive success and seed predation were mediated by phenology, and if positional effects on reproductive success depended on the external environment., Results: In three years, basal flowers and racemes opened earlier and had higher fruit set than distal. Basal flowers also experienced higher seed predation. Differences among racemes in fruit and seed set were largely related to phenology, while differences in fruit set, seed set, and seed predation within racemes were not. In one year, differences in fruit set among flowers at different positions depended on flowering duration., Conclusions: Our results highlight the important role of ontogenetic contingency for within-individual variation in phenology and reproductive success. As the spatial distribution of reproductive structures affects both within-plant trait distributions and fitness, it is a likely target for natural selection., (© 2024 The Author(s). American Journal of Botany published by Wiley Periodicals LLC on behalf of Botanical Society of America.)

Cyrtosia septentrionalis, an orchid species, is notable for its sausage-shaped red fleshy fruits, which can reach up to 10 cm in length. Previous research identified frugivorous and omnivorous birds, especially the brown-eared bulbul Hypsipetes amaurotis (Pycnonotidae, Passeriformes), as key seed dispersers of C. septentrionalis in natural habitats. This finding challenges conventional belief that orchid seeds are primarily wind-dispersed. Moreover, given the rarity of specialized co-evolutionary relationships between fruits and frugivores, C. septentrionalis may also rely on mammals for seed dispersal in certain regions. We aimed to explore the fruit consumption habits of animals other than birds. Motion sensor-equipped cameras were used to observe interactions with the fruits of C. septentrionalis and assess the viability of seeds post-consumption. The observations revealed three animal species consuming the fruits, with the masked palm civet Paguma larvata (Viverridae, Carnivora) identified as a dominant consumer in the investigated population. Microscopy analysis of seeds retrieved from P. larvata faeces indicated that the seeds remained intact and viable after passing through the digestive system of this carnivorous mammal. The above discovery suggests a potential role for carnivorous mammals in seed dispersal of C. septentrionalis, alongside birds, thus broadening our understanding of the complex seed dispersal strategies employed by orchids., (© 2024 Wiley‐VCH GmbH. Published by John Wiley & Sons Ltd.)

Most Aristolochiaceae species studied so far are from temperate regions, bearing self-compatible protogynous trap flowers. Although self-incompatibility has been suggested for tropical species, the causes of self-sterility in this family remain unknown. To fill this gap, we studied the pollination of the tropical Aristolochia esperanzae, including the physical and physiological anti-selfing mechanisms. Floral visitors trapped inside flowers were collected to determine the pollinators. Protogyny was characterized by observing the temporal expression of sexual phases and stigmatic receptivity tests. The breeding system was investigated using hand-pollination treatments. Pollen tube growth was observed using epifluorescence to identify the self-incompatibility mechanism. Flies were the most frequent visitors found inside A. esperanzae trap flowers, with individuals from the family Ulidiidae being potential pollinators since they carried pollen. The characteristic flower odour and presence of larvae indicate that A. esperanzae deceives flies through oviposition-site mimicry. Although this species showed incomplete protogyny, stigmatic receptivity decreased during the male phase, avoiding self-pollination. Fruits developed only after cross- and open pollination, indicating that the population is non-autonomous, non-apomictic, and self-sterile. This occurred through a delay in the growth of geitonogamous pollen tubes to the ovary and lower ovule penetration, indicating a late-acting self-incompatibility mechanism. Our findings expand the number of families in which late-acting self-incompatibility has been reported, demonstrating that it is more widespread than previously thought, especially when considering less-studied tropical species among the basal angiosperms., (© 2024 Wiley‐VCH GmbH. Published by John Wiley & Sons Ltd.)

Premise: Gynodioecy is a rare sexual system in which two genders (sensu Lloyd, 1980), cosexuals and females, coexist. To survive, female plants must compensate for their lack of siring capacity and male attractiveness. In European chestnut (Castanea sativa), an outcrossing tree, self-pollination reduces fruit set in cosexual individuals because of late-acting self-incompatibility and early inbreeding depression. Could this negative sexual interaction explain the presence of females in this species?, Methods: We studied gender variation in wild populations of European chestnut. In addition, we compared fruit set (the proportion of flowers giving fruits) and other key female fitness components as well as reproductive allocation between genders. We then performed emasculation experiments in cosexual trees, by removing nectar-producing fertile male inflorescences. We also removed sterile but nectar-producing male inflorescences from female trees, as a control., Results: We found a highly variable proportion of male-sterile individuals in the wild in European chestnut. In the experimental plot, trees from each gender had similar size, flower density, and burr set, but different fruit set. Removing nectar-producing male inflorescences from branches or entire trees increased fruit set in cosexual but not in female trees., Conclusions: These results show that self-pollination impairs fruit set in cosexual trees. Female trees avoid these problems as they do not produce pollen but continue to attract pollinators thanks to their rewarding male-sterile inflorescences, resulting in a much higher fruit set than in cosexuals. This demonstrates that even outcrossed plants can benefit from the cessation of self-pollination, to the point that unisexuality can evolve., (© 2024 The Authors. American Journal of Botany published by Wiley Periodicals LLC on behalf of Botanical Society of America.)

Hydrogen sulphide (H 2 S) is a gaseous molecule and originates endogenously in plants. It is considered a potential signalling agent in various physiological processes of plants. Numerous reports have examined the role of H 2 S in fruit ripening and in enhancing fruit quality traits. H 2 S coordinates the fruit antioxidant system, fruit ripening phytohormones, such as ethylene and abscisic acid, together with other ripening-related signalling molecules, including nitric oxide and hydrogen peroxide. Although many studies have increased understanding of various aspects of this complex network, there is a gap in understanding crosstalk of H 2 S with key players of fruit ripening, postharvest senescence and fruit metabolism. This review focused on deciphering fruit H 2 S metabolism, signalling and its interaction with other ripening-related signalling molecules during fruit ripening and postharvest storage. Moreover, we also discuss how H 2 S can be used as a tool for improving fruit quality and productivity and reducing postharvest loss of perishable fruits., (© 2021 German Society for Plant Sciences and The Royal Botanical Society of the Netherlands.)

Fruits of Terminalia chebula Retz. (Combretaceae) are widely used as crude drugs in various traditional medicine systems. The aim of this article is to review the available scientific information regarding the traditional uses, bioactive chemical constituents and the pharmacological activities of T. chebula. Numerous researches conducted on T. chebula have confirmed the presence of wide range of the phytochemicals such as flavonoids, tannins, phenolic acids and other bioactive compounds. T. chebula is also widely studied regarding its pharmacological activities such as antioxidant, hepatoprotective, neuroprotective, cytotoxic, antidiabetic, anti-inflammatory activities among others. However, more in vivo and clinical studies for mechanism-based pharmacological evaluation should be conducted in future to provide stronger scientific evidences for their traditional uses., (© 2020 John Wiley & Sons, Ltd.)

Pollination and resource availability are factors determining reproductive success of plants, and in agriculture these factors influence yield of fruit-bearing crops. Our understanding of the importance of crop pollination is fast improving, but less is known about how the interaction between pollination and resources constrains fruit production. We conducted an experiment with almond trees (Prunus dulcis) to examine how the number of flowers, light availability and competition for resources affected nut (fruit) production on individual spurs (fruit-bearing structures) exposed to open-pollination or hand-pollination. We found a positive relationship between flower number and nut number on spurs with up to four flowers, but no further benefit after four flowers, suggesting a resource threshold expressed by individual spurs. Spurs with few flowers increased the conversion rate of flowers to nuts when supplemented with hand-pollination, but spurs with more flowers were more likely to achieve the threshold number of nuts even under open-pollination. Our experiment included a further treatment involving spraying whole trees with pollen. This treatment reduced nut production by spurs with many flowers and high light availability, suggesting competition is experienced by well-resourced spurs when resources need to be shared among developing nuts across the whole tree. Our study supports the hypothesis that excess flower production in fruit trees increases the potential for fruit production when pollinator and resource availability is variable (bet-hedging). Spurs with more flowers typically produce more nuts (within a limited range), but only if both resources and pollen supply increase with flower number. For almond growers, a focus on maintaining high flower numbers, especially in high light regions of the canopy, is the foundation for high levels of production. Strategies to lift flower number and light are complicated by trade-offs inherent in tree architecture and orchard design. However, fruit set would be lifted above that achieved by current practice by an increase in the pollination rate of flowers., (© 2019 German Society for Plant Sciences and The Royal Botanical Society of the Netherlands.)

Species with rewardless flowers often have low fruit to flower ratios, although wide temporal and spatial variation in fruiting success can occur. We compared floral phenotypes, insect visitors and fruiting success in four populations of the small white (Cypripedium candidum) and yellow (C. parviflorum) lady's slipper orchids and their hybrids near the northern extent of North America's tall grass prairie. Flower and fruit numbers were observed for two seasons on marked individuals (n = 1811). Floral traits were measured on 82-140 individuals per taxon and analysed in relation to fruiting success. All insects found inside flowers were collected, inspected for pollen smears and measured for comparison to floral features. Among orchid taxa, C. candidum had the smallest flowers, lowest number and variety of insect visitors, and lowest fruit to flower ratios. These measures were intermediate in hybrids and highest in C. parviflorum, despite low flower numbers in the latter. Within orchid taxa, fruit number was positively related to flower number, but fruit to flower ratios decreased slightly, as would be expected if pollinators left unrewarding patches. Potential pollinators included the dipteran Odontomyia pubescens and hymenopterans Andrena spp., Apis mellifera and Lasioglossum zonulum. Cypripedium parviflorum had a reproductive advantage over C. candidum across multiple populations and years. Hybrids showed segregation for floral traits, and hybrid fruiting success increased with a deeper intensity of yellow pigment and larger escape routes for floral visitors. These same attributes likely contributed to the relatively high fruit set in C. parviflorum in the study region., (© 2019 German Society for Plant Sciences and The Royal Botanical Society of the Netherlands.)

Premise of the Study: New growth in the spring requires resource mobilization in the vascular system at a time when xylem and phloem function are often reduced in seasonally cold climates. As a result, the timing of leaf out and/or flowering could depend on when the vascular system resumes normal function in the spring. This study investigated whether flowering time is influenced by vascular phenology in plants that flower precociously before they have leaves., Methods: Flower, leaf, and vascular phenology were monitored in pairs of precocious and non-precocious congeners. Differences in resource allocation were quantified by measuring bud dry mass and water content throughout the year, floral hydration was modelled, and a girdling treatment completed on branches in the field., Key Results: Precocious flowering species invested more in floral buds the year before flowering than did their non-precocious congeners, thus mobilizing less water in the spring, which allowed flowering before new vessel maturation., Conclusions: A shift in the timing of resource allocation in precocious flowering plants allowed them to flower before the production of mature vessels and minimized the significance of seasonal changes in vascular function to their flowering phenology. The low investment required to complete floral development in the spring when the plant vascular system is often compromised could explain why flowers can emerge before leaf out., (© 2019 Botanical Society of America.)

Agricultural production in controlled environments is increasingly feasible, and may play an important role in providing nutrition and choice to growing urban centres. New technologies in lighting, ventilation, robotics and irrigation are just a few of the innovations that enable production of high-value specialty crops outside of a traditional field setting. However, despite all of the advances in the hardware within the plant factory operation, innovation of the most complex machine has been neglected - the plant itself. Indoor agricultural operations typically rely on legacy varieties, plants selected and bred for field conditions. In the field, phenotypic stability is paramount, as production must be consistent in an unpredictable and changing environment. However, the controlled environment affords focus on different breeding priorities as environmental flux, pests, pathogens and post-harvest quality are less formidable barriers to production. On the contrary, breeding for controlled environments shifts the focus to a completely different set of plant traits, such as rapid growth, performance in low light environments and active manipulation of plant stature. Instead of breeding for phenotypic stability, plants may be bred to maximise genetic plasticity, allowing specific traits to be presented as a function of the quality of the ambient light spectrum. In this scenario plant varieties may be grown with optimal size, supporting a focus on consumer traits like flavour or accumulation of health-related compounds. Gene editing may be a central technology in the production of designer plants for controlled environments. This review considers the opportunity for breeding for controlled environments, with a focus on a revision of priorities for controlled-environment breeders., (© 2018 German Society for Plant Sciences and The Royal Botanical Society of the Netherlands.)

Premise of the Study: Phenological mismatch has received attention in plant-pollinator interactions, but less so in seed dispersal mutualisms. We investigated whether the seasonal availability of myrmecochorous seeds is well matched to the seasonal activity patterns of seed-dispersing ants., Methods: We compared seasonal timing of seed removal by a keystone seed-dispersing ant, Aphaenogaster rudis, and fruit dehiscence of several species of plants whose seeds it disperses in a deciduous forest in southern Ontario, Canada. We examined the timing of elaiosome "robbing" by the nonnative slug Arion subfuscus and tested whether seed removal by ants declines in response to supplementation with additional elaiosome-bearing seeds (ant "satiation")., Key Results: Seed removal from experimental depots peaked early in the season for all plant species and correlated with temperature. In contrast, elaiosome robbing by slugs increased late in the season and thus may disproportionately affect plants with late-dehiscing fruits. Ant colonies removed seeds at similar rates regardless of seed supplementation, indicating that satiation likely does not impact seasonal patterns of seed dispersal in this system. Fruits of the five myrmecochorous plant species in our study dehisced at discrete intervals throughout the season, with minimal overlap among species. Peak dehiscence did not overlap with peak seed removal for any plant species., Conclusions: Fruit dehiscence of myrmecochorous plants and peak ant seed dispersal activity occur asynchronously. Whether future climate warming will shift ant and plant phenologies in ways that have consequences for seed dispersal remains an open question., (© 2019 Botanical Society of America.)

Mitrastemon yamamotoi is completely embedded within the tissues of its hosts, except during the reproductive stage, when aboveground parts emerge from host tissues. Its highly modified appearance has attracted attention of many botanists, but very little is known about the reproductive system. Floral visitors to M. yamamotoi were observed in southern Japan. Pollination experiments were conducted to determine the plant's self-compatibility and pollen limitation, as well as the contribution of diurnal and nocturnal visitors to fruit set and outcrossing. Mitrastemon yamamotoi is mainly pollinated by social wasps, but previously unnoticed pollinators (i.e. crickets and cockroaches) are also important, based on visitation frequency and pollen loads. Results of the pollination experiments suggest that nocturnal visitors, such as crickets and cockroaches, contribute to geitonogamous pollination, whereas diurnal visitors, such as social wasps, facilitate outcrossing. The unexpected pollinator assemblage of M. yamamotoi might be influenced by multiple factors, including the highly modified flowers that are produced close to the ground in dark understorey environments, the species' winter-flowering habit and the location of the study site (i.e. near the northern limit of the species' range). Considering that M. yamamotoi occurs widely in subtropical and tropical forests in Asia, additional studies are needed to assess pollinator assemblages of M. yamamotoi at other locations., (© 2018 German Society for Plant Sciences and The Royal Botanical Society of the Netherlands.)

Thirty crop species provide 90% of our food, most of which display severe yield losses under moderate salinity. Securing and augmenting agricultural yield in times of global warming and population increase is urgent and should, aside from ameliorating saline soils, include attempts to increase crop plant salt tolerance. This short review provides an overview of the processes that limit growth and yield in saline conditions. Yield is reduced if soil salinity surpasses crop-specific thresholds, with cotton, barley and sugar beet being highly tolerant, while sweet potato, wheat and maize display high sensitivity. Apart from Na + , also Cl - , Mg 2+ , SO 4 2- or HCO 3 - contribute to salt toxicity. The inhibition of biochemical or physiological processes cause imbalance in metabolism and cell signalling and enhance the production of reactive oxygen species interfering with cell redox and energy state. Plant development and root patterning is disturbed, and this response depends on redox and reactive oxygen species signalling, calcium and plant hormones. The interlink of the physiological understanding of tolerance processes from molecular processes as well as the agronomical techniques for stabilizing growth and yield and their interlinks might help improving our crops for future demand and will provide improvement for cultivating crops in saline environment., (© 2018 German Society for Plant Sciences and The Royal Botanical Society of the Netherlands.)

Premise of the Study: Although an evolutionary link between breeding system and dispersibility has been proposed, to date empirical data and theoretical models of plants show contrasting trends., Methods: We tested two competing hypotheses for the association between breeding systems and dispersibility in the heterocarpic Hypochaeris salzmanniana (Asteraceae) by using both an experimental approach and surveys over 2 years of five natural populations along an environmental cline with a gradient of pollinator availability., Key Results: Hypochaeris salzmanniana produced two types of fruits, beaked (BF) and nonbeaked (NBF), which differ in their dispersal ability. The BF were lighter and had a lower dropping velocity and higher dispersal distance than the NBF. Potential for long-distance dispersal, measured as BF ratio per head, had high narrow-sense heritability. Greater dispersibility and selfing ability were linked at all the scales studied. Both selfed BF and NBF fruits had longer plumes and lower plume loading than outcrossed fruits, characteristics that promote farther dispersal. Natural populations with a higher percentage of self-compatible plants showed a higher BF ratio. Moreover, selfing led to a higher BF ratio than outcrossing., Conclusions: The avoidance of inbreeding depression seems to be the most plausible selective pressure for the greater dispersibility traits of selfed seeds. Furthermore, the ability to modulate the BF ratio and thus the potential for long-distance dispersal of offspring based on its selfed or outcrossed origin could be advantageous, and therefore selected, under unpredictable pollination environments that favor higher dispersive selfers, which overcome both pollen limitation and inbreeding avoidance., (© 2018 Botanical Society of America.)

Although the Cerrado vegetation is adapted to fire, anthropogenic fires may impair the reproduction of some species. This study aimed to test the role of fruits of Qualea multiflora and their position in the tree crown in protecting the seeds during fires. Ten trees were selected in an area protected from fire (NB) and ten in a biannually burned area (B). Fruits were counted before the 2008 fire and weekly thereafter for 5 weeks. Fruit dehiscence, damage and position in the tree crown were recorded. Seed germination was assessed for seeds from both areas. In NB, 5.7% of fruits were located higher than 2 m, while in B 49.5% were located at this height. One week after the fire, the proportion of dehiscent fruits was lower in NB (19.5%) than in B (34.5%). Five weeks after the fire, all fruits in NB had dispersed their seeds, whereas in B only 47% of the fruits had. Immediately before the fire, the germination rate of seeds collected in NB was 80% (0-1 m), 97% (1-2 m) and 92% (≥2 m). Fifteen days after the fire, the germination rate of seeds in the B area was 3% (0-1 m), 13% (1-2 m) and 78% (≥2 m). Protection of Q. multiflora seeds from high temperatures is related to the fruit position in the tree crown rather than to fruit protection. Therefore, the results suggest that fire may alter the recruitment of new individuals., (© 2018 German Society for Plant Sciences and The Royal Botanical Society of the Netherlands.)

Premise of the Study: Relying on floral traits to assess pollination systems has been shown to underestimate the ecological service that novel mutualisms can provide. Although vertebrates with opportunistic food habits are common on islands, usually feeding upon flowers of entomophilous species (ES), little is known about how effective they are as pollinators. In a previous study, we had reported that native insectivorous and frugivorous Galápagos birds commonly visit ES flowers, without assessing whether they act as pollinators. Here we investigate this by focusing on three typically ES (Cryptocarpus pyriformis, Waltheria ovata, Cordia lutea) and one mostly ornithophilous species (OS), Opuntia echios., Methods: The quantitative component (QNC: the product of floral visit frequency and number of flowers contacted) and qualitative components (QLC: fruit and seed set, fruit length, and mass and proportion of seedling emergence) of pollination effectiveness of birds was compared with that of insects., Key Results: Birds were not quantitatively important pollinators compared to insects. However, selective exclusion experiments in the four plant species revealed that all qualitative components of fitness improved when both birds and insects visited the flowers. Our study is the first to confirm pollination effectiveness of ES by native opportunistic birds., Conclusions: The Galápagos pollination systems are probably more generalized than previous data suggested and, given that ES dominate the flora of this archipelago, we argue that, contrary to expectation, birds might have an important role in maintaining the reproductive success and diversity of plant communities., (© 2018 Botanical Society of America.)

Pedicularis is the largest genus in the Orobanchaceae (>300) with many species co-occurring and co-blooming in subalpine to alpine meadows in the Himalayas. Although it is well known that different Pedicularis species place pollen on different parts of the same bumblebee's body, thus reducing interspecific pollen transfer, it is not known whether post-pollination components also contribute to reproductive isolation (RI). In this study, we quantified the individual strengths and absolute contributions of six pre- and post-pollination components of RI between three sympatric species in two pairs; Pedicularis gruina × Pedicularis tenuisecta (gru × ten) and Pedicularis comptoniifolia × Pedicularis tenuisecta (com × ten). All three Pedicularis species shared the same Bombus species. Individual foragers showed a high, but incomplete, floral constancy for each species. Therefore, pre-pollination barriers were potentially 'leaky' as Bombus species showed a low but consistent frequency of interspecific visitation. The RI strength of pre-pollination was lower in com × ten than in gru × ten. In contrast, post-pollination barriers completely blocked gene flow between both sets of species pairs. Two post-pollination recognition sites were identified. Late acting rejection of interspecific pollen tube growth occurred in com♀ × ten♂, while seeds produced in bi-directional crosses of gru × ten failed to germinate. We propose that, although floral isolation based on pollen placement on pollinators in the genus Pedicularis is crucial to avoid interspecific pollen transfer, the importance of this mode of interspecific isolation may be exaggerated. Post-pollination barriers may play even larger roles for currently established populations of co-blooming and sympatric species in this huge genus in the Himalayas., (© 2018 German Society for Plant Sciences and The Royal Botanical Society of the Netherlands.)

Anogeissus leiocarpa (DC.) Guill. & Perr. (Combretaceae) has important economic and cultural value in West Africa as source of wood, dye and medicine. Although this tree is in high demand by local communities, its planting remains limited due to its very low propagation via seed. In this study, X-rays were used to select filled fruits in order to characterise their morphology and seed germination responses to treatment with sulphuric acid and different incubation temperatures. Morphological observations highlighted a straight orthotropous seed structure. The increase in mass detected for both intact and scarified fruits through imbibition tests, as well as morphological observations of fruits soaked in methylene blue solution, confirmed that they are water-permeable, although acid-scarified fruits reached significantly higher mass increment values than intact ones. Acid scarification (10 min soaking in 98% H 2 SO 4 ) positively affected seed germination rate but not final germination proportions. When intact fruits where incubated at a range of temperatures, no seeds germinated at 10 °C, while maximum seed germination (ca. 80%) was reached at 20 °C. T 50 values ranged from a minimum of ca. 12 days at 25 °C to a maximum of ca. 34 days at 15 and 35 °C. A theoretical base temperature for germination (T b ) of ca. 10 °C and a thermal requirement for 50% germination (S) of ca. 195 °Cd were also identified for intact fruits. The results of this study revealed the seed germination characteristics driven by fruit and seed morphology of this species, which will help in its wider propagation in plantations., (© 2018 German Society for Plant Sciences and The Royal Botanical Society of the Netherlands.)

Diaspore structure has been hypothesised to play a role in seed viability and/or germination of recalcitrant seeds, especially for Swartzia langsdorffii. Thus, this work aims to (i) investigate the in situ contribution of pericarp and aril on seed viability and germination, and (ii) identify morphoanatomical traits of S. langsdorffii diaspores that allow its desiccation-sensitive seeds to remain viable. The role of the pericarp and aril in seed survival and germination was investigated by placing the whole fruit, whole seeds (arillate seed) and bare seeds (without aril) in soil in the forest understorey, assessing germination, emergence, dead, firm and predated seeds, and water content of pericarps, arils and seeds. Correlation analysis was performed between environmental variables and physiological parameters. Histochemical features of diaspores were also investigated. Pericarp water content fell after several months, while the aril maintained its water content. Seeds did not lose water even without the presence of the pericarp and aril. However, presence of the pericarp promoted seed water content, viability and germination long after dispersal. The embryo had a thickened outer periclinal cell wall. Pericarp and aril are not essential to prevent water loss in seeds, but do help to retain seed moisture, favouring viability maintenance and promoting germination during the rainy season. Morphoanatomical features of seeds are suggested as main factors that reduce water loss. Survival of these desiccation-sensitive seeds upon dispersal during the dry season appears to be facilitated by multiple diaspore features that prevent viability loss., (© 2017 German Society for Plant Sciences and The Royal Botanical Society of the Netherlands.)

One of the key environmental factors affecting plant reproductive systems is temperature. Characterising such effects is especially relevant for some commercially important genera such as Citrus. In this genus, failure of fertilisation results in parthenocarpic fruit development and seedlessness, which is a much-prized character. Here, we characterise the effects of temperature on flower and ovary development, and on pollen-pistil interactions in 'Comune' clementine (Citrus clementina Hort. ex Tan.). We examine flower bud development, in vitro pollen germination and pollen-pistil interaction at different temperatures (15, 20, 25 or 30 °C). These temperatures span the range from 'cold' to 'hot' weather during the flowering season in many citrus-growing regions. Temperature had a strong effect on flower and ovary development, pollen germination, and pollen tube growth kinetics. In particular, parthenocarpic fruit development (indicated by juice vesicle growth) was initiated early if flowers were exposed to warmer temperatures during anthesis. Exposure to different temperatures during flower bud development also alters expression of the self-incompatibility reaction. This affects the point in the pistil at which pollen tube growth is arrested and confirms the role of sub- and supra-optimal temperatures in determining the numbers of pollen tubes reaching the ovary., (© 2017 German Society for Plant Sciences and The Royal Botanical Society of the Netherlands.)

The current low latitudinal range margins of many extra-tropical plant species consist of small and scattered populations that persist locally in microrefugia. It remains poorly understood how their refugial distribution affects mating patterns and reproductive success. Here we examine flower and acorn production and their determinants in refugial populations of the widespread European forest tree pedunculate oak (Quercus robur). We monitored male flower, female flower and acorn production in 159 adult trees from 12 oak stands over 2 years. We related these and derived parameters to a series of ecological and genetic predictor variables extrinsic (stand size, density and isolation as well as elevation, topography and forest cover) or intrinsic (size, phenology and several genotypic measures) to the target tree. Tree fertility was unrelated to extrinsic factors but determined by tree size, although we detected size-independent variation in reproductive investment. Female flower number accurately predicted acorn crop size. Fruit set differed between years, evidencing the existence of pollen limitation at the landscape but not at the local scale. Fruit set also tended to increase with the number of mates of the target tree. We detected no other evidence for genetic constraints on mating. Reproduction was triggered by a combination of small-scale and landscape-scale drivers. Although short-distance mating prevailed, limited pollen flow did not appear to significantly constrain reproductive success. The high intrinsic ability of populations to maintain their reproductive capacity may help explain their successful long-term persistence in an adverse broader environment., (© 2017 German Botanical Society and The Royal Botanical Society of the Netherlands.)

Individuals of Aechmea bracteata show inflorescences with red scape bracts and odourless, yellow, tubular diurnal flowers, with closely arranged sexual organs, producing a large amount of fruits. In order to investigate the reproductive system of this species, a suite of characters was assessed: phenology, floral morphology and biology, nectar production dynamics, and fruit and seed production and germination, as a result of controlled pollination crosses. The study was conducted during two flowering seasons in wild populations in Yucatán, Mexico. Results suggest an annual flowering pattern with one flowering peak; flowers were diurnal, showing partial dichogamy (protandry)-herkogamy, anthers and stigma become mature before floral aperture, which could lead to self-pollination, nectar is produced during anthesis, varying in volume and total sugar concentration during the day; fruits and seeds were produced in all experimental crosses (cross-pollination, obligated cross-pollination, assisted and unassisted selfing, geitonogamy and apomixis), as well as high percentage seed germination. Several species of Aechmea are reportedly self-compatible and autogamous, as suggested by results of selfing and non-assisted selfing crosses, but these results are negated by the presence of apomixis, indicating that the species is apomictic. This is the first report of this breeding system for subgenus Aechmea and the sixth for Bromeliaceae. Polyembryony is here suggested for the first time in this genus and family based on the fact that more seeds were recorded that expected based on ovule numbers. Finally, when performing experimental crosses, estimating reproductive success based on number of seeds is a better approach than number of fruits, due to the effect of pseudogamy., (© 2017 German Society for Plant Sciences and The Royal Botanical Society of the Netherlands.)

Premise of the Study: A repeated pattern of American amphitropical disjunct species or sister species distributed on either side of the equator has long-fascinated botanists, but the modes of these disjunctions remain untested. We evaluated diaspore morphology to generate hypotheses on probable dispersal mechanisms., Methods: The sizes and structures of diaspores, habit, habitat, distribution, and dispersal units were collected for 108 species from literature searches and herbarium specimens. Variation was evaluated with summary statistics, χ 2 tests with Monte Carlo simulations, ANOVAs, and the nonparametric Mann-Whitney test., Key Results: Seeds were the dispersing diaspore in 38.0% of the species, 45.4 were dispersed as fruits, and the remaining were dispersed as infructescences or spores. Diaspores were epizoochorous (52.8%), anemochorous (20.4%), achorous (15.7%), endozoochorous (8.3%), and hydrochorous (2.8%). Epizoochory was significantly greater than expected. Zoochory occurred more frequently than expected when considering achorous diaspores as animal-dispersed. Most species were associated with wetland, woodland, and grassland habitats. An ANOVA revealed that diaspores associated with hydrochory were larger and anemochory was smaller; all other syndromes were not significantly different., Conclusions: Botanists have long-held the assumption that bird migrations are responsible for amphitropical disjunctions. Our results support this hypothesis, with the majority of these events occurring by external attachment of small fruits. However, our results also indicate that anemochory might play a greater role in producing amphitropical distributions than previously thought and at a greater rate than endozoochory or hydrochory., (© 2017 Botanical Society of America.)

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., Methods: We measured the components of the pollination efficiency (PE) of species foraging on flowers. The measured quantitative components were visitation frequency patterns to plants and individual flowers. The qualitative components were the contributions to the fitness of male and female functions (pollen removal and deposition and fruit set)., Key Results: Pollination by warbler species was highly efficient, but visit frequency was low; conversely, Canarian chiffchaffs had high visit frequency and low efficiency. Overall PE was almost 0 for blue tits due to disruptive behavior. We also found insects acting as nectar robbers., Conclusions: Pollination efficiency of three of the four bird species visiting flowers of Navaea phoenicea may be high enough to maintain selective pressure on floral traits of a relict pollination syndrome. The behavior of these birds plays a crucial role in their pollination efficiency. Perching, by generalist passerines when visiting N. phoenicea flowers, is the most efficient habit. The frequency and PE of insect visits calls into question their role as legitimate visitors., (© 2017 Botanical Society of America.)

Flowering and fruiting are key events in the life history of plants, and both are critical to their reproductive success. Besides the role of evolutionary history, plant reproductive phenology is regulated by abiotic factors and shaped by biotic interactions with pollinators and seed dispersers. In Melastomataceae, a dominant Neotropical family, the reproductive systems vary from allogamous with biotic pollination to apomictic, and seed dispersal varies from dry (self-dispersed) to fleshy (animal-dispersed) fruits. Such variety in reproductive strategies is likely to affect flowering and fruiting phenologies. In this study, we described the reproductive phenology of 81 Melastomataceae species occurring in two biodiversity hotspots: the Atlantic rain forest and the campo rupestre. We aim to disentangle the role of abiotic and biotic factors defining flowering and fruiting times of Melastomataceae species, considering the contrasting breeding and seed dispersal systems, and their evolutionary history. In both vegetation types, pollinator-dependent species had higher flowering seasonality than pollinator-independent ones. Flowering patterns presented phylogenetic signal regardless of vegetation type. Fruiting of fleshy-fruited species was seasonal in campo rupestre but not in Atlantic rain forest; the fruiting of dry-fruited species was also not seasonal in both vegetation types. Fruiting showed a low phylogenetic signal, probably because the influence of environment and dispersal agents on fruiting time is stronger than the phylogenetic affinity. Considering these ecophylogenetic patterns, our results indicate that flowering may be shaped by the different reproductive strategies of Melastomataceae lineages, while fruiting patterns may be governed mainly by the seed dispersal strategy and flowering time, with less phylogenetic influence., (© 2017 German Botanical Society and The Royal Botanical Society of the Netherlands.)

The study of intraspecific seed packaging (i.e. seed size/number strategy) variation across different populations may allow better understanding of the ecological forces that drive seed evolution in plants. Juniperus thurifera (Cupressaceae) provides a good model to study this due to the existence of two subspecies differentiated by phenotypic traits, such as seed size and cone seediness (number of seeds inside a cone), across its range. The aim of this study was to analyse seed packaging (seed mass and cone seediness) variation at different scales (subspecies, populations and individuals) and the relationship between cone and seed traits in European and African J. thurifera populations. After opening more than 5300 cones and measuring 3600 seeds, we found that seed packaging traits followed different patterns of variation. Large-scale effects (region and population) significantly contributed to cone seediness variance, while most of the seed mass variance occurred within individuals. Seed packaging differed between the two sides of the Mediterranean Sea, with African cones bearing fewer but larger seeds than the European ones. However, no differences in seed mass were found between populations when taking into account cone seediness. Larger cones contained more pulp and seeds and displayed a larger variation in individual seed mass. We validated previous reports on the intraspecific differences in J. thurifera seed packaging, although both subspecies followed the same seed size/number trade-off. The higher seediness and variation in seed mass found in larger cones reveals that the positive relationship between seed and cone sizes may not be straightforward.We hypothesise that the large variation of seed size found within cones and individuals in J. thurifera, but also in other fleshy-fruited species, could represent a bet-hedging strategy for dispersal., (© 2017 German Botanical Society and The Royal Botanical Society of the Netherlands.)

Mixed cross and self-pollen load on the stigma (mixed pollination) of species with late-acting self-incompatibility system (LSI) can lead to self-fertilized seed production. This "cryptic self-fertility" may allow selfed seedling development in species otherwise largely self-sterile. Our aims were to check if mixed pollinations would lead to fruit set in LSI Adenocalymma peregrinum, and test for evidence of early-acting inbreeding depression in putative selfed seeds from mixed pollinations. Experimental pollinations were carried out in a natural population. Fruit and seed set from self-, cross and mixed pollinations were analysed. Further germination tests were carried out for the seeds obtained from treatments. Our results confirm self-incompatibility, and fruit set from cross-pollinations was three-fold that from mixed pollinations. This low fruit set in mixed pollinations is most likely due to a greater number of self- than cross-fertilized ovules, which promotes LSI action and pistil abortion. Likewise, higher percentage of empty seeds in surviving fruits from mixed pollinations compared with cross-pollinations is probably due to ovule discounting caused by self-fertilization. Moreover, germinability of seeds with developed embryos was lower in fruits from mixed than from cross-pollinations, and the non-viable seeds from mixed pollinations showed one-third of the mass of those from cross-pollinations. The great number of empty seeds, lower germinability, lower mass of non-viable seeds, and higher variation in seed mass distribution in mixed pollinations, strongly suggests early-acing inbreeding depression in putative selfed seeds. In this sense, LSI and inbreeding depression acting together probably constrain self-fertilized seedling establishment in A. peregrinum., (© 2016 German Botanical Society and The Royal Botanical Society of the Netherlands.)

The incredible pollination mechanisms displayed by orchid flowers has inspired biologists over the centuries. Based on the intriguing flower structures, the relationship among orchid species and their pollinators has been frequently regarded as very specialised. Given that visits on flowers pollinated by oil-collecting bees are regularly rare, and in Oncidiinae the flowers frequently attractexclusively species that act as effective pollinators, the comparative reproductive biology and pollinator specificity of two sympatric Gomesa (G. varicosa and G. montana; Oncidiinae) were analysedbased on records of floral morphology, production of floral rewards, pollinators and pollination mechanisms. Furthermore, experimental pollinations were carried out in order to examine the breeding systems. The results have show that in the studied population, both Gomesa are visited by several bee species, but these orchids present a specific pollination system.Pollinaria are deposited on the head of Centridini (G. varicosa and G. montana) and Epicharitini (G. varicosa) bees when landed on the central callus of the labellumto collect lipoidal substances produced by glandular elaiophores on lateral lobes of the labellum. Both species are dependent on a biotic pollen vector to set fruits. Gomesamontana is completely self-incompatible, while G. varicosa is partially self-compatible. Our results indicate that although the occurrence of self-sterile species seems to be common in Oncidiinae, in partially self-incompatible species, as is the case of G. varicosa, self-compatibility has been considered as an important factor favouring reproductive assurance in populations with low visitation frequencies, despite occurrence of inbreeding depression., (© 2016 German Botanical Society and The Royal Botanical Society of the Netherlands.)

The equatorial orientation of reproductive structures is known in some columnar cacti from extratropical deserts. It has been hypothesised that photosynthetically active radiation (PAR) interception is the main reason for this orientation, because of its key effect on nocturnal CO 2 uptake. However, there are no studies addressing both the effect of PAR and its consequence, carbon gain, on fruit orientation. Accordingly, we tested whether PAR and carbon gain could explain the southern fruit orientation of Myrtillocactus geometrizans, an inter-tropical columnar cactus. We studied three populations of M. geometrizans in Mexico. For each population, azimuth of fruits, total daily PAR, nocturnal acid accumulation (NAA) and fruit production were measured. The relationships between rib orientation and number of fruits, as well as total daily PAR, were evaluated using periodic regressions. The effect of total daily PAR and NAA on number of fruits was assessed using generalised linear models. During spring, mean fruit orientation had a south azimuth for three populations. Likewise, rib orientation had a significant effect on fruit production, with the south-facing ribs having the maximum number of fruits. Total daily PAR was highest in the south-facing ribs, at least for those in the northern and central populations. Furthermore, during spring, there was a significant positive effect of total daily PAR and NAA on fruit production. Our results provide strong evidence that the higher carbon gain in equatorial ribs, through a highest interception of PAR, would be the responsible factor for equatorial orientation of fruits in an inter-tropical columnar cactus., (© 2016 German Botanical Society and The Royal Botanical Society of the Netherlands.)

Premise of Study: The factors driving variation in species interactions are often unknown, and few studies have made a link between changes in interactions and the strength of selection., Methods: We report on spatial variation in functional responses by a seed predator (SP) and its parasitic wasps associated with the herb Ruellia nudiflora . We assessed the influence of plant density on consumer responses and determined whether density effects and spatial variation in functional responses altered natural selection by these consumers on the plant. We established common gardens at two sites in Yucatan, Mexico, and planted R. nudiflora at two densities in each garden. We recorded fruit output and SP and parasitoid attack; calculated relative fitness (seed number) under scenarios of three trophic levels (accounting for SP and parasitoid effects), two trophic levels (accounting for SP but not parasitoid effects), and one trophic level (no consumer effects); and compared selection strength on fruit number under these scenarios across sites and densities., Key Results: There was spatial variation in SP recruitment, whereby the SP functional response was negatively density-dependent at one site but density-independent at the other; parasitoid responses were density-independent and invariant across sites. Site variation in SP attack led, in turn, to differences in SP selection on fruit output, and parasitoids did not alter SP selection. There were no significant effects of density at either site., Conclusions: Our results provide a link between consumer functional responses and consumer selection on plants, which deepens our understanding of geographic variation in the evolutionary outcomes of multitrophic interactions., (© 2017 Botanical Society of America.)

Premise of the Study: Central questions in plant reproductive ecology are whether the functions of floral traits in hermaphrodites create conflict between sexes that could slow evolution, and whether individual floral traits function in pollinator attraction, efficiency, or both. We studied how floral traits affect pollinator visitation and efficiency, and how they affect male and female function and female fitness within and across three Asclepias species that differ in floral morphology., Methods: Using separate multiple regressions, we regressed pollen removal, deposition, and fruit number onto six floral traits. We also used path analyses integrating these variables with pollinator visitation data for two of the species to further explore floral function and its effects on fruit production., Key Results: Most traits affected male pollination success only, and these effects often differed between species. The exception was increased slit length, which increased pollinia insertion in two of the species. There were no interspecific differences in the effects of the traits on female pollination success. All traits except horn reach affected pollination efficiency in at least one species, and horn reach and two hood dimensions were the only traits to affect pollinator attraction, but in just one species., Conclusions: Traits tended to function in only one sex, and more traits affected function through pollinator efficiency than through attraction. There was no significant link between female pollination success and female fitness in any of the three species; this pattern is consistent with fruit production not being limited by pollen deposition., (© 2017 Botanical Society of America.)

Considerable variation occurs in post-maturity timing of dehiscence in fruits of Brassicaceae species, and several studies have shown that the pericarp plays an important role in seed germination and retention of viability in species with indehiscent fruits. However, little is known about the significance to seed biology of delay in pericarp dehiscence for <1 year in the field. Thus, we determined the role of the pericarps of Leptaleum filifolium and Neotorularia korolkovii, which open in <1 year after fruit maturity and dispersal, in seed germination and retention of seed viability. We compared dormancy-break via after-ripening in the laboratory and germination phenology and retention of seed viability in intact siliques and isolated seeds buried in an experimental garden. Seeds of both species have Type 6 non-deep physiological dormancy, which is enhanced by the pericarp. Seeds of both species after-ripened during summer 2013, and some of them germinated in autumn and some in the following spring in watered and non-watered soil. Germination percentages of seeds in siliques increased in soil in spring 2014, after the pericarps had opened. Most isolated seeds of L. filifolium and N. korolkovii had germinated or were dead by spring 2014 and summer 2015, respectively, whereas 60% of the seeds of both species in the (opened) pericarps were viable after 24 months. Thus, although the pericarp opened 9-10 months after burial, its presence had a significant effect on seed dormancy, germination phenology and retention of viability of seeds of L. filifolium and N. korolkovii., (© 2016 German Botanical Society and The Royal Botanical Society of the Netherlands.)

This study tested the hypothesis that self-compatibility would be associated with floral traits that facilitate autonomous self-pollination to ensure reproduction under low pollinator visitation. In a comparison of two pairs of Ipomoea species with contrasting breeding systems, we predicted that self-compatible (SC) species would have smaller, less variable flowers, reduced herkogamy, lower pollinator visitation and higher reproductive success than their self-incompatible (SI) congeners. We studied sympatric species pairs, I. hederacea (SC)- I. mitchellae (SI) and I. purpurea (SC)-I. indica (SI), in Mexico, over two years. We quantified variation in floral traits and nectar production, documented pollinator visitation, and determined natural fruit and seed set. Hand-pollination and bagging experiments were conducted to determine potential for autonomous self-pollination and apomixis. Self-compatible Ipomoea species had smaller flowers and lower nectar production than SI species; however, floral variation and integration did not vary according to breeding system. Bees were primary pollinators of all species, but visitation rates were seven times lower in SC than SI species. SC species had a high capacity for autonomous self-pollination due to reduced herkogamy at the highest anther levels. Self-compatible species had two to six times higher fruit set than SI species. Results generally support the hypothesis that self-compatibility and autonomous self-pollination ensure reproduction under low pollinator visitation. However, high variation in morphological traits of SC Ipomoea species suggests they maintain variation through outcrossing. Furthermore, reduced herkogamy was associated with high potential for autonomous self-pollination, providing a reproductive advantage that possibly underlies transitions to self-compatibility in Ipomoea., (© 2016 German Botanical Society and The Royal Botanical Society of the Netherlands.)

Premise of the Study: Factors related to pollen and resource limitation were evaluated to predict female fruit production in a tropical dioecious tree. Pollen limitation via variation in the male density at local scales is expected to limit female reproduction success in dioecious plants., Methodology: We modeled the roles of local male density, female crown size, crown illumination, and female flower production on female fruit initiation and mature fruit production in a continuous population (62 ha plot) of a tropical dioecious tree (Virola surinamensis). In addition, we used microsatellites to describe the scale of effective pollen flow, the male effective population size, and the spatial genetic structure within/between progenies and males., Key Results: The local male density was not related to female fruit initiation or mature fruit production. Female floral production had a positive effect on fruit initiation. The female crown size was positively related to fruit maturation. Seeds from the same female and seeds from different but spatially proximal females were generally half-siblings; however, proximal females showed greater variation. Proximal male-female adult pairs were not significantly more genetically related than distant pairs. The probability of paternity was negatively affected by the distance between seeds and males; most effective pollen dispersal events (∼85%) occurred from males located less than 150 m from females. The number of males siring progenies was greater than the number of males found at local scales., Conclusions: Female fecundity in this continuous population of Virola surinamensis is not limited by the availability of pollen from proximal males. Rather, resource allocation to floral production may ultimately determine female reproductive success., (© 2016 Botanical Society of America.)

Premise of the Study: Self incompatibility (SI) in rare plants presents a unique challenge-SI protects plants from inbreeding depression, but requires a sufficient number of mates and xenogamous pollination. Does SI persist in an endangered polyploid? Is pollinator visitation sufficient to ensure reproductive success? Is there evidence of inbreeding/outbreeding depression? We characterized the mating system, primary pollinators, pollen limitation, and inbreeding/outbreeding depression in Erysimum teretifolium to guide conservation efforts., Methods: We compared seed production following self pollination and within- and between-population crosses. Pollen tubes were visualized after self pollinations and between-population pollinations. Pollen limitation was tested in the field. Pollinator observations were quantified using digital video. Inbreeding/outbreeding depression was assessed in progeny from self and outcross pollinations at early and later developmental stages., Key Results: Self-pollination reduced seed set by 6.5× and quadrupled reproductive failure compared with outcross pollination. Pollen tubes of some self pollinations were arrested at the stigmatic surface. Seed-set data indicated strong SI, and fruit-set data suggested partial SI. Pollinator diversity and visitation rates were high, and there was no evidence of pollen limitation. Inbreeding depression (δ) was weak for early developmental stages and strong for later developmental stages, with no evidence of outbreeding depression., Conclusions: The rare hexaploid E. teretifolium is largely self incompatible and suffers from late-acting inbreeding depression. Reproductive success in natural populations was accomplished through high pollinator visitation rates consistent with a lack of pollen limitation. Future reproductive health for this species will require large population sizes with sufficient mates and a robust pollinator community., (© 2016 Melen et al. Published by the Botanical Society of America. This work is licensed under a Creative Commons Attribution License (CC-BY).)

Gall inducers use these structures as shelters and sources of nutrition. Consequently, they cause multiple physiological changes in host plants. We studied the impact caused by seed coat galls of a braconid wasp on the performance of fruits, seeds and seedlings of tree Inga laurina. We tested whether these seed galls are 'nutrient sinks' with respect to the fruit/seed of host plant, and so constrain the reproductive ability and reduce seedling longevity. We measured the influence of such galls on the secondary compounds, fruit and seed parameters, seed viability and germination and seedling performance. Inga laurina has indehiscent legumes with polyembryonic seeds surrounded by a fleshy sarcotesta rich in sugars. The galls formed inside the seed coat and galled tissues presented higher phenol concentrations, around 7-fold that of ungalled tissues. Galls caused a significant reduction in parameters such as fruit and seed size, seed weight and the number of embryos. Fluctuating asymmetry (a stress indicator) was 31% higher in leaves of galled seed plants in comparison to ungalled seed plants. However, the negative effects on fruit and seed parameters were not sufficient to reduce seed germination (except the synchronization index) or seedling performance (except leaf area and chlorophyll content). We attributed these results to the ability of I. laurina to tolerate gall attack on seeds without a marked influence on seedling performance. Moreover, because of the intensity of seed galling on host plant, we suggest that polyembryony may play a role in I. laurina reproduction increasing tolerance to seed damage., (© 2016 German Botanical Society and The Royal Botanical Society of the Netherlands.)

Premise of the Study: Interspecific reproductive barriers (IRBs) often prevent hybridization between closely related species in sympatry. In the tomato clade (Solanum section Lycopersicon), interspecific interactions between natural sympatric populations have not been evaluated previously. In this study, we assessed IRBs between members of the tomato clade from nine sympatric sites in Peru., Methods: Coflowering was assessed at sympatric sites in Peru. Using previously collected seeds from sympatric sites in Peru, we evaluated premating prezygotic (floral morphology), postmating prezygotic (pollen-tube growth), and postzygotic barriers (fruit and seed development) between sympatric species in common gardens. Pollen-tube growth and seed development were examined in reciprocal crosses between sympatric species., Key Results: We confirmed coflowering of sympatric species at five sites in Peru. We found three types of postmating prezygotic IRBs during pollen-pistil interactions: (1) unilateral pollen-tube rejection between pistils of self-incompatible species and pollen of self-compatible species; (2) potential conspecific pollen precedence in a cross between two self-incompatible species; and (3) failure of pollen tubes to target ovules. In addition, we found strong postzygotic IRBs that prevented normal seed development in 11 interspecific crosses, resulting in seed-like structures containing globular embryos and aborted endosperm and, in some cases, overgrown endothelium. Viable seed and F 1 hybrid plants were recovered from three of 19 interspecific crosses., Conclusions: We have identified diverse prezygotic and postzygotic IRBs that would prevent hybridization between sympatric wild tomato species, but interspecific hybridization is possible in a few cases., (© 2016 Botanical Society of America.)

Gynodioecy, a state where female and hermaphrodite plants coexist in populations, has been widely proposed an intermediate stage in the evolutionary pathway from hermaphroditism to dioecy. In the gynodioecy-dioecy pathway, hermaphrodites may gain most of their fitness through male function once females invade populations. To test this prediction, comprehensive studies on sex ratio variation across populations and reproductive characteristics of hermaphrodite and female phenotypes are necessary. This study examined the variation in sex ratio, sex expression, flower and fruit production and sexual dimorphism of morphological traits in a gynodioecious shrub, Daphne jezoensis, over multiple populations and years. Population sex ratio (hermaphrodite:female) was close to 1:1 or slightly hermaphrodite-biased. Sex type of individual plants was largely fixed, but 15% of plants changed their sex during a 6-year census. Hermaphrodite plants produced larger flowers and invested 2.5 times more resources in flower production than female plants, but they exhibited remarkably low fruit set (proportion of flowers setting fruits). Female plants produced six times more fruits than hermaphrodite plants. Low fruiting ability of hermaphrodite plants was retained even when hand-pollination was performed. Fruit production of female plants was restricted by pollen limitation under natural conditions, irrespective of high potential fecundity, and this minimised the difference in resources allocated to reproduction between the sexes. Negative effects of previous flower and fruit production on current reproduction were not apparent in both sexes. This study suggests that gynodioecy in this species is functionally close to a dioecious mating system: smaller flower production with larger fruiting ability in female plants, and larger flower production with little fruiting ability in hermaphrodite plants., (© 2016 German Botanical Society and The Royal Botanical Society of the Netherlands.)

Relationships among floral biology, floral micromorphology and pollinator behaviour in bird-pollinated orchids are important issues to understand the evolution of the huge flower diversity within Orchidaceae. We aimed to investigate floral mechanisms underlying the interaction with pollinators in two hummingbird-pollinated orchids occurring in the Atlantic forest. We assessed floral biology, nectar traits, nectary and column micromorphologies, breeding systems and pollinators. In both species, nectar is secreted by lip calli through spaces between the medial lamellar surfaces of epidermal cells. Such a form of floral nectar secretion has not been previously described. Both species present functional protandry and are self-compatible yet pollinator-dependent. Fruit set in hand-pollination experiments was more than twice that under natural conditions, evidencing pollen limitation. The absence of fruit set in interspecific crosses suggests the existence of post-pollination barriers between these sympatric co-flowering species. In Elleanthus brasiliensis, fruits resulting from cross-pollination and natural conditions were heavier than those resulting from self-pollination, suggesting advantages to cross-pollination. Hummingbirds pollinated both species, which share at least one pollinator species. Species differences in floral morphologies led to distinct pollination mechanisms. In E. brasiliensis, attachment of pollinarium to the hummingbird bill occurs through a lever apparatus formed by an appendage in the column, another novelty to our knowledge of orchid pollination. In E. crinipes, pollinarium attachment occurs by simple contact with the bill during insertion into the flower tube, which fits tightly around it. The novelties described here illustrate the overlooked richness in ecology and morphophysiology in Orchidaceae., (© 2015 German Botanical Society and The Royal Botanical Society of the Netherlands.)

Premise of the Study: Most bird-dispersed fruits are green when unripe and become colored and conspicuous when ripe, signaling that fruits are ready to be consumed and dispersed. The color pattern for fruits of Miconia albicans (Melastomataceae), however, is the opposite, with reddish unripe and green ripe fruits. We (1) verified the maintenance over time of its bicolored display, (2) tested the communicative function of unripe fruits, (3) tested the photoprotective role of anthocyanins in unripe fruits, and (4) verified whether green ripe fruits can assimilate carbon., Methods: Using a paired experiment, we tested whether detection of ripe fruits was higher on infructescences with unripe and ripe fruits compared with infructescences with only ripe fruits. We also measured and compared gas exchange, chlorophyll a fluorescence, and heat dissipation of covered (to prevent anthocyanin synthesis) and uncovered ripe and unripe fruits., Key Results: Although the bicolored display was maintained over time, unripe fruits had no influence on bird detection and removal of ripe fruits. Ripe and unripe fruits did not assimilate CO2, but they respired instead., Conclusions: Since the communicative function of unripe fruits was not confirmed, seed dispersers are unlikely to select the display with bicolored fruits. Because of the absence of photosynthetic activity in ripe and unripe fruits and enhanced photoprotective mechanisms in ripe fruits rather than in unripe fruits, we could not confirm the photoprotective role of anthocyanins in unripe fruits. As an alternative hypothesis, we suggest that the bicolored fruit display could be an adaptation to diversify seed dispersal vectors instead of restricting dispersal to birds and that anthocyanins in unripe fruits may have a defense role against pathogens., (© 2015 Botanical Society of America.)

Most habitat fragmentation studies have focused on the effects of population size on reproductive success of single species, but studies assessing the effects of both fragment size and connectivity, and their interaction, on several coexisting species are rare. In this study, we selected 20 fragments along two continuous gradients of size and degree of isolation in a gypsum landscape in central Spain. In each fragment, we selected 15 individuals of each of three dominant gypsophiles (Centaurea hyssopifolia, Lepidium subulatum and Helianthemum squamatum, 300 plants per species, 900 plants in total) and measured several reproductive traits: inflorescence number, fruit set, seed set and seed mass. We hypothesised that plant fitness would be lower on small and isolated fragments due to an interaction between fragment size and connectivity, and that response patterns would be species-specific. Overall, fragment size had very little effect on reproductive traits compared to that of connectivity. We observed a positive effect of fragment connectivity on C. hyssopifolia fitness, mediated by the increased seed predation in plants from isolated fragments, resulting in fewer viable seeds per capitulum and lower seed set. Furthermore, seed mass was lower in plants from isolated fragments for both C. hyssopifolia and L. subulatum. In contrast, few reproductive traits of H. squamatum were affected by habitat fragmentation. We discuss the implications of species-specific responses to habitat fragmentation for the dynamics and conservation of gypsum plant communities. Our results highlight the complex interplay among plants and their mutualistic and antagonistic visitors, and reinforce the often-neglected role of habitat connectivity as a key component of the fragmentation process., (© 2015 German Botanical Society and The Royal Botanical Society of the Netherlands.)

Unlabelled: •, Premise of the Study: Sexual floral dimorphism may have evolved under pollinator-mediated natural selection by which female and male functions are differently influenced. We hypothesized that mating success is differently influenced by display size between sexes, under which sexual dimorphism in flowering schedule has evolved in dioecious species.•, Methods: We examined sexual dimorphism in the total number of flowers per shoot, maximum daily display size, longevity of individual flowers, and flowering synchrony (maximum proportion of open flowers) in three dioecious Ilex species (I. pedunculosa, I. serrata, and I. crenata) whose female flowers are not smaller than male flowers. We compared pollinator response to natural variation of daily display size between sexes. We also examined the effect of display size on female and male success (fruit set and pollen deposition and removal).•, Key Results: In the three species, male shoots produced significantly more flowers than female shoots did. Although female flowers lasted longer and opened more synchronously than male flowers, maximum daily display size was larger on male shoots than on female shoots. Fruit set was significantly pollen-limited in the field in all species. Pollen deposition and/or fruit set increased with female display size, whereas pollen removal decreased or was approximately constant with male display size in the three species.•, Conclusions: We suggest that sexual dimorphism in floral longevity and flowering synchrony might enhance both female and male success in relation to the display size-mating success (pollinator attraction) association irrespective of flower size dimorphism., (© 2015 Botanical Society of America, Inc.)

Literature investigations indicate that the grapes have quite complex fertilisation biology. This complexity necessitates extensive investigations to obtain reliable knowledge for both well-organised hybridisation studies and maximising grape yield. Therefore, this study was conducted to investigate the influences of self-, free- and cross-pollination on berry and seed characteristics in grape. Five different pollination treatments were applied to 'Narince', the most widely known and popular white wine grape in Turkey. Pollen tests indicated that all the cultivars had satisfactory in vitro pollen viability percentages. Free-pollination produced a significantly higher percentage berry set. Among the pollinizers, the use of pollen of 'Thompson Seedless' and 'Cardinal' varieties resulted in higher berry set percentage in 'Narince'. The free-pollination was also superior in giving the highest weight, length and width of the berry, as well as number of seeds per berry. These findings revealed that there were strong xenial and metaxenial effects in the studied grape cultivars. Among the pollinizer cultivars, the most effective pollinator was 'Thompson Seedless'. Hence, for better berry set and quality, the use of 'Thompson Seedless' as a pollinizer may be an attractive option in both grape production and breeding studies., (© 2014 German Botanical Society and The Royal Botanical Society of the Netherlands.)

Unlabelled: •, Premise of the Study: Although rewarding orchids are believed to have a high pollination efficiency, pollination success is often low, suggesting that rewarding orchids may be prone to pollen limitation. Assuming that selfing contributes significantly to fruit and seed set (i.e., reproductive assurance) and that the quality of selfed seeds is high (i.e., low inbreeding depression), it can be hypothesized that under these circumstances populations evolve to facultative or even complete self-pollination.•, Methods: In this study, we performed emasculation and pollen supplementation experiments in the field to assess the extent of outcross pollen limitation and the contribution of autonomous self-pollination to fruit and seed set in the rewarding orchid Epipactis palustris. Hand-pollinations using cross and self-pollen were performed in the greenhouse to investigate the impact of selfing on seed set and seed quality and to assess the magnitude of inbreeding depression.•, Key Results: Fruit set under natural conditions was high: ca. 70% of all flowers set fruit. Percentage fruit set of emasculated plants was 56%, implying that fruit set in about 14% of all flowers was the result of autonomous self-pollination. Pollen supplementation significantly increased fruit and seed set, indicating strong outcross pollen limitation. Hand-pollination with cross pollen resulted in significantly higher seed set and seed quality compared with manual self-pollination, indicating high levels of early inbreeding depression (δ = 0.46 ± 0.08).•, Conclusions: Overall, these results indicate that, despite the high pollination efficiency, populations of this rewarding orchid species were strongly pollen limited. Costs of early inbreeding depression, on the other hand, were high, which may prevent rapid evolution of complete selfing., (© 2015 Botanical Society of America, Inc.)

Subdioecy is thought to occupy a transitional position in the gynodioecy-dioecy pathway, explaining one of the evolutionary routes from hermaphroditism to dioecy. Quantifying any female reproductive advantage of females versus hermaphrodites is fundamental to examining the spectrum between subdioecy and dioecy; however, this is challenging, as multiple interacting factors, such as pollen limitation and resource availability, affect plant reproduction. We compared the female reproductive success of females and hermaphrodites via a field experiment in which we hand-pollinated individuals of the subdioecious shrub Eurya japonica of similar size growing under similar light conditions. Effects of pollen limitation and seed quality were also evaluated through comparing the results of hand- and natural-pollination treatments and performing additional laboratory and greenhouse experiments. Overall, females had higher fruit set and produced heavier fruit and more seeds than hermaphrodites, and these results were more pronounced for hand-pollinated than for natural-pollinated plants of both sexes. We also found that seeds naturally produced by females had a higher mean germination rate. These results indicate that females had a pronounced advantage in female reproductive success under conditions of no pollen limitation. The sexual difference in the degree of pollen limitation suggests a pollinator-mediated interaction, whereas the higher female reproductive success of females even under natural conditions implies that E. japonica is a good model species for elucidating the later stages of the gynodioecy-dioecy pathway., (© 2014 German Botanical Society and The Royal Botanical Society of the Netherlands.)

Pollination is critical to fruit production, but the interactions of pollination with plant resources on a plant's reproductive and vegetative features are largely overlooked. We examined the influences of pollination, irrigation and fertilisation on the performance of almond, Prunus dulcis, in northern California. We used a full-factorial design to test for the effects of pollination limitation on fruit production and foliage variables of whole trees experiencing four resource treatments: (i) normal water and nutrients, (ii) reduced water, (iii) no nutrients, and (iv) reduced water and no nutrients. In each of these combinations, we applied three pollination treatments: hand-cross pollination, open-pollination and pollinator exclusion. Pollination strongly affected yield even under reduced water and no nutrient applications. Hand-cross pollination resulted in over 50% fruit set with small kernels, while open-pollinated flowers showed over 30% fruit set with moderate-sized kernels. Pollinator-excluded flowers had a maximum fruit set of 5%, with big and heavy kernels. Reduced water interacted with the open- and hand-cross pollination treatments, reducing yield more than in the pollinator exclusion treatment. The number of kernels negatively influenced the number of leaves, and reduced water and no nutrient applications interacted with the pollination treatments. Overall, our results indicate that the influences of pollination on fruit tree yield interact with the plant availability of nutrients and water and that excess pollination can reduce fruit quality and the production of leaves for photosynthesis. Such information is critical to understand how pollination influences fruit tree performance., (© 2014 German Botanical Society and The Royal Botanical Society of the Netherlands.)

The frequency of hybrid formation in angiosperms depends on how and when heterospecific pollen is transferred to the stigma, and on the success of that heterospecific pollen at fertilising ovules. We applied pollen mixtures to stigmas to determine how pollen interactions affect siring success and the frequency of hybrid formation between two species of Mediterranean deceptive orchid. Plants of Orchis italica and O. anthropophora were pollinated with conspecific and heterospecific pollen (first conspecific pollen then heterospecific pollen and vice versa) and molecular analysis was used to check the paternity of the seeds produced. In this pair of Mediterranean orchids, competition between conspecific and heterospecific pollen functions as a post-pollination pre-zygotic barrier limiting the frequency of the formation of hybrids in nature. Flowers pollinated with heterospecific pollen can remain receptive for the arrival of conspecific pollen for a long time. There is always an advantage of conspecific pollen for fruit formation, whether it comes before or after heterospecific pollen, because it overtakes the heterospecific pollen. The conspecific pollen advantage exhibited in O. italica and O. anthropophora is likely to result from the reduced germination of heterospecific pollen or retarded growth of heterospecific pollen tubes in the stigma and ovary. Overall, the results indicate that our hybrid zone represents a phenomenon of little evolutionary consequence, and the conspecific pollen advantage maintains the genetic integrity of the parental species., (© 2014 German Botanical Society and The Royal Botanical Society of the Netherlands.)