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Gynodioecy, the coexistence of hermaphrodites with females, often reflects conflicts between cytoplasmic male sterility (CMS) genes and nuclear genes restoring male fertility. CMS is frequent in plants and has been recently discovered in one animal: the freshwater snail, Physa acuta. In this system, CMS was linked to a single divergent mitochondrial genome (D), devoid of apparent nuclear restoration. Our study uncovers a second, novel CMS-associated mitogenome (K) in Physa acuta , demonstrating an extraordinary acceleration of molecular evolution throughout the entire K mitochondrial genome, akin to the previously observed pattern in D. This suggests a pervasive occurrence of accelerated evolution in both CMS-associated lineages. Through a 17-generation introgression experiment, we further show that nuclear polymorphisms in K-mitogenome individuals contribute to the restoration of male function in natural populations. Our results underscore shared characteristics in gynodioecy between plants and animals, emphasizing the presence of multiple CMS mitotypes and cytonuclear conflicts. This reaffirms the pivotal role of mitochondria in influencing male function and in generating genomic conflicts that impact reproductive processes in animals. [ABSTRACT FROM AUTHOR]

Abstract The increasing global importance of pink peppertree (Schinus terebinthifolia, Anacardiaceae) as a high-value commercial crop and its potential for expansion in production demand appropriate management due to uncertainties regarding its sexual system. This study focused on evaluating the morphology of sterile and fertile floral whorls, as well as analyzing the sexual system of pink pepper in two populations in northeastern Brazil. The results revealed no significant differences in the morphological characteristics of the flowers between the studied areas, suggesting that the species possesses notable adaptability to environmental conditions. However, a significant difference in the proportion of staminate individuals was observed in both areas, representing over 88% and 72%, respectively. A correlation was observed between the size of the stamens and the presence of apparently atrophied pistils (r=0.275; df=178; p

Background. Ranunculus acris L. (Meadow Buttercup) is a perennial herbaceous short-rhizome polycarpic plant. Mentions of flowering and pollination characteristics in gynodioecious R. acris are scarcely found in the literature. Materials and methods. Observations were made in the natural conditions of the Moscow region from 2021 to 2023 by generally accepted methods. Results. Perfect flowers are weakly protandric, bloom for 5–6 days and pistillate flowers – for 3–4 days. The opening of flowers in a closed thyrsus and its lateral dichasia with different reduction options occur according to the order of branching of the shoot. The total flowering time of perfects and females varies from 3 to 4 weeks, and depends on weather conditions. R. acris is an obligate xenogamous species: the pollen/ovary ratio is from 4594 to 7149 in perfect flowers. Both types of flowers open synchronously, with a maximum at 10 a.m. Conclusions. Efficient cross-pollination in R. acris is reached by the presence of gynodioecy, the synchronous rhythm of perfect and female flowering, the formation of a large number of pollen grains in both types of flowers, later onset and earlier completion of flowering of females, and by gametophyte self-incompatibility.

Gynodioecy has been identified to occur in the herbaceous polycarpic Origanum vulgare ssp. gracile growing in Tajikistan and is here described in detail for the first time. The investigated populations of O. vulgare ssp. gracile form two types of flowers, perfect and pistillate, on different individuals. In pistillate flowers, stamens are represented by staminodes. The size of many parts of the corolla and androecium of perfect flowers is significantly larger than in pistillate flowers. Four criteria have been identified that make it possible to reliably distinguish flowers of different sexual forms: the size of the corolla and its parts, the difference between calyx tube length versus corolla tube length, the position of the anthers, and the rate of development of stamens. Perfect flowers are characterized by strictly pronounced protandry. According to the pollen/ovule ratio (from 825 to 953), O. vulgare ssp. gracile is facultatively xenogamous. Hermaphrodites predominated (from 58.9 to 76.2%) in five of the investigated populations. The frequency of females in O. vulgare ssp. gracile was shown to be most dependent on annual precipitation. Finally, we discuss the presence and distribution of gynodioecy within the genus Origanum and its adaptive significance for the existence of populations of O. vulgare ssp. gracile. [ABSTRACT FROM AUTHOR]

This account presents information on all aspects of the biology of Geranium pratense L. (Meadow Crane's‐Bill). The main topics are presented within the standard framework of the Biological Flora of Britain and Ireland : distribution, habitat, communities, responses to biotic factors, responses to environment, structure and physiology, phenology, floral and seed characters, herbivores and disease, history and conservation.Geranium pratense is a perennial gynodioecious forb of neutral grassland. In Britain and Ireland, it is particularly abundant on roadside verges, railway embankments, the margins of watercourses and woodland rides. It is generally intolerant of grazing and is absent or scarce in livestock‐grazed grassland. Geranium pratense is widespread in England, Wales and Scotland but is scarce in Ireland. It has an extensive native range in Europe and Asia, extending eastwards to Russia, north‐western China and Mongolia. It has been widely introduced to new sites within its native range and has been introduced to Canada, the USA and New Zealand.Geranium pratense usually occurs on free‐draining soils but also infrequently where drainage is impeded. The soils are often nutrient‐rich and weakly acidic to weakly alkaline. The underlying geology is usually non‐acidic sedimentary rocks or superficial deposits.Geranium pratense is protandrous and is pollinated by various insects of the orders Hymenoptera, Diptera and Lepidoptera, particularly bumblebees, solitary bees, hoverflies and butterflies. Eleven species of phytophagous insect have been recorded on G. pratense in Britain and Ireland.Geranium pratense has little or no capacity for vegetative spread. Primary seed dispersal is ballistic and seeds may be flung over distances of up to several metres. The species has a transient seed bank, that is germination typically takes place in the winter and spring after seed production, after the physically dormant seeds have become permeable. Seedling establishment is higher in vegetation‐free gaps than in undisturbed grassland vegetation.There has been no significant change in its distribution between the late 1950s and 2019, although since 2000, it has expanded its range, mainly via introductions, in northern and western Scotland, west Wales and in Ireland. Alien sites have increased markedly since the 1960s due to introductions from wildflower seed sowing and spread from gardens. [ABSTRACT FROM AUTHOR]

To explain the co-existence and maintenance of females along with hermaphrodite plants, the female advantage hypothesis has been proposed where females should show greater fecundity compared to their conspecific hermaphrodites. On the other hand, greater attraction would be selected in the hermaphrodites to increase their male function, potentially leading to larger showier flowers, with more rewards. Here, I tested the sexual dimorphism trade-off hypothesis with the gynomonoecious-gynodioecious Dianthus plumarius (Caryophyllaceae), in the gardens of Bariloche (Patagonia, Argentina). I measured in female and hermaphrodite plants: flower size, nectar volume and concentration, flower lifespan, ovule production, seed number, seed set and seed weight. Additionally, bagging and pollen supplementation experiments were carried out to evaluate pollen limitation, probability of apomixis, if spontaneous autogamy is possible, and to examine the importance of pollen origin. I found that hermaphrodite flowers are more attractive, with larger-sized flowers and higher nectar volume, whereas female flowers compensate with longer lifespan of stigmatic receptivity and more concentrated nectar. Despite ovule number was lower in female flowers, these showed higher seed set and produced more and heavier seeds than hermaphrodites under open pollination. No evidence of apomixis was found in females, but spontaneous autogamy may occur in hermaphrodites. Hand-pollination experiments showed first that both flower types suffered pollen limitation, but it was higher on hermaphrodite flowers. Finally, despite self-compatibility, pollen origin is important because hand self-pollination decreases seed weight. These findings provide strong evidence in support of the mechanisms and underlying conditions that would allow the co-existence and maintenance of female and hermaphrodite individuals within populations. [ABSTRACT FROM AUTHOR]

Abstract Objective Sidalcea is a genus of flowering plants restricted to the west coast of North America, commonly known as checkermallows. Remarkably, of the ~ 30 recognized species, 16 are of conservation concern (vulnerable, imperilled or critically imperilled). To facilitate biological studies in this genus, and in the wider Malvaceae, we have sequenced the whole plastid genome of Sidalcea hendersonii. This will allow us both to check those regions already developed as general Malvaceae markers in a previous study, and to search for new regions. Results By comparing the Sidalcea genome to that of Althaea, we have identified a hypervariable circa 1 kb region in the short single copy region. This region shows promise for examining phylogeographic pattern, hybridization and haplotype diversity. Remarkably, considering the conservation of plastome architecture between Sidalcea and Althaea, the former has a 237 bp deletion in the otherwise highly conserved inverted repeat region. Newly designed primers provide a PCR assay to determine presence of this indel across the Malvaceae. Screening of previously designed chloroplast microsatellite markers indicates two markers with variation within S. hendersonii that would be useful in future population conservation genetics.

Premise: Under uncertain pollinator visit conditions, plants often exhibit long flowering periods and generalized pollination systems. Flowering of the gynodioecious shrub Daphne jezoensis occurs in early spring in cool temperate forests. Pollination by nocturnal moths is expected, given the species' tubular‐shaped flowers with sweet fragrance and nectar. However, the effectiveness of nocturnal moths under cool conditions is unknown. We evaluated the relative importance of diurnal and nocturnal visitors as pollinators in early spring. Methods: We investigated flowering duration, flower visitors, and floral scents in a natural population. We experimentally exposed flowers to visitors only during daytime or nighttime using bagging treatments and evaluated the contributions of diurnal and nocturnal insects to fruit set, pollen dispersal distance, and paternity diversity using 16 microsatellite markers. Results: Female flowers lasted ~3 wk, which was ~8 d longer than the flowering period of hermaphrodites. Various insects, including Coleoptera, Diptera, Hymenoptera, and Lepidoptera, visited the flowers during both daytime and nighttime. Flowers emitted volatiles, such as lilac aldehyde isomers and β‐ocimene, which are known to attract moths. Fruit‐set rate in the night‐open treatment was similar to or higher than that in the day‐open treatment. However, pollen dispersal distance in the night‐open treatment was shorter than that in the day‐open treatment. Paternity diversity was similar in day‐open and night‐open treatments. Conclusions: Early‐blooming plants ensure pollen receipt and dispersal by having a long flowering period and using both diurnal and nocturnal flower visitors, suggesting the importance of a generalized pollination system under uncertain pollinator visit conditions. [ABSTRACT FROM AUTHOR]

This research delves into plant–pollinator relationships within the Mediterranean region, focusing on two synchronous and sympatric asparagus species: A. acutifolius and A. albus. For the first time, the floral scents of the genus Asparagus are reported. We investigate the volatile organic compounds (VOCs) present in their floral scents and their impact on pollinator attraction. Captured flower-emitted VOCs underwent solid-phase microextraction of headspace (SPME-HS) and gas chromatography and mass spectrometry (GC-MS) analysis. The investigation confirms distinctive aroma profiles for each species. A. albus predominantly emits benzene derivatives and sesquiterpenes, while A. acutifolius is characterized by carotenoid derivatives, monoterpenes, and sesquiterpenes. The only shared compounds between the two species are the sesquiterpenes (Z,E)-α-farnesene and (E,E)-α-farnesene. A positive correlation links peak floral aroma intensity (benzenoids in A. albus and ionones in A. acutifolius) with a higher pollinator visit frequency, emphasizing the critical role of intense floral scents in pollinator attraction. The study of reproductive aspects reveals almost complete gynodioecy in A. acutifolius, influencing unique dynamics for the two species. These adaptations hold significant importance within the Mediterranean ecosystem, particularly during the late dry summer period, when a limited number of plant species vie for a shared primary pollinator. [ABSTRACT FROM AUTHOR]

Summary: There is growing evidence that cytonuclear incompatibilities (i.e. disruption of cytonuclear coadaptation) might contribute to the speciation process. In a former study, we described the possible involvement of plastid–nuclear incompatibilities in the reproductive isolation between four lineages of Silene nutans (Caryophyllaceae). Because organellar genomes are usually cotransmitted, we assessed whether the mitochondrial genome could also be involved in the speciation process, knowing that the gynodioecious breeding system of S. nutans is expected to impact the evolutionary dynamics of this genome.Using hybrid capture and high‐throughput DNA sequencing, we analyzed diversity patterns in the genic content of the organellar genomes in the four S. nutans lineages.Contrary to the plastid genome, which exhibited a large number of fixed substitutions between lineages, extensive sharing of polymorphisms between lineages was found in the mitochondrial genome. In addition, numerous recombination‐like events were detected in the mitochondrial genome, loosening the linkage disequilibrium between the organellar genomes and leading to decoupled evolution.These results suggest that gynodioecy shaped mitochondrial diversity through balancing selection, maintaining ancestral polymorphism and, thus, limiting the involvement of the mitochondrial genome in evolution of hybrid inviability between S. nutans lineages. [ABSTRACT FROM AUTHOR]

Species of Chamaelirium are known to be highly diversified in sexual characters, but there has been no detailed empirical approach to elucidate the mechanism and process of sexual diversification in the genus. This paper reports the results of population‐based analyses on various sexual aspects of C. hisauchianum endemic to Japan. Of the 20 populations surveyed, eight (40%) were composed of facultative hermaphrodites highly labile in sexual expression, exhibiting a wide range of gradational variation from hermaphroditism through andromonoecy to male. The remaining 12 populations (60%) consisted of females and facultative hermaphrodites. In them, 11.8–30.9% (mean 22.2%) of the individuals were female. With no reciprocal sex changes, females and facultative hermaphrodites were regarded as, plausibly genetically determined, discrete sex morphs. In contrast, sexual expression in both sex morphs appeared resource dependent. Besides the difference in floral sexual traits, the average ratio of ovuliferous flowers in females was higher than that in facultative hermaphrodites. The production of ovuliferous flowers by females was less susceptible to both field and cultivated conditions and tended to be significantly relatively higher under unfavorable growing conditions. Females were thus less plastic (or more persistent) in producing ovuliferous flowers (or female organs) than facultative hermaphrodites irrespective of internal and external conditions. In all populations, andromonoecious plants dominated (50.8–100%), which appeared to reflect the high plasticity in sex allocation of facultative hermaphrodites. The different modes of sex allocation were regarded as secondary sex characters and presumably stem from a difference in easiness or attainability of sexual reproduction between the two sex morphs. [ABSTRACT FROM AUTHOR]

We examined populations of North Apennine stenoendemics Cirsium bertolonii in the Apuan Alps and Tuscan-Emilian Apennines and found individuals morphologically shifted to co-occurring C. acaulon or C. erisithales. Hybrid status of these intermediates was confirmed by flow cytometry, morphometrics and amplified fragment length polymorphism (AFLP). We interpreted these hybrids taxonomically as Cirsium ×sagrense (C. acaulon × C. bertolonii) and C. ×abetonense (C. bertolonii × C. erisithales). Estimated genome size (2C) was 2244 ± 31 Mbp for C. ×sagrense and 2152 ± 99 Mbp for C. ×abetonense. Their genomic GC content was 38.95 ± 0.35% and 38.77 ± 0.26%, respectively. Diploid chromosome number 2n = 34 was counted for C. bertolonii, and the previously reported 2n = 12 needs to be considered erroneous. We found C. bertolonii to be a gynodioecious species (like many other Cirsium species) that is not reproductively isolated by ploidy level or chromosome number from co-occurring congeners. The relatively frequent occurrence of C. ×sagrense in Monte Sagro (locus classicus of C. bertolonii) and the prevalence of C. ×abetonense in Alpe Tre Potenze suggest that hybridization occurs repeatedly in C. bertolonii, as also confirmed by older herbarium specimens. C. ×abetonense produces ripe achenes and F2 hybrids or backcrosses, as some other Cirsium hybrids do. Genetic erosion/swamping via interspecific hybridization can therefore pose a risk to the genetic integrity of C. bertolonii, as it does for some other narrowly endemic high-mountain Cirsium species in Europe. [ABSTRACT FROM AUTHOR]

Objective: Sidalcea is a genus of flowering plants restricted to the west coast of North America, commonly known as checkermallows. Remarkably, of the ~ 30 recognized species, 16 are of conservation concern (vulnerable, imperilled or critically imperilled). To facilitate biological studies in this genus, and in the wider Malvaceae, we have sequenced the whole plastid genome of Sidalcea hendersonii. This will allow us both to check those regions already developed as general Malvaceae markers in a previous study, and to search for new regions. Results: By comparing the Sidalcea genome to that of Althaea, we have identified a hypervariable circa 1 kb region in the short single copy region. This region shows promise for examining phylogeographic pattern, hybridization and haplotype diversity. Remarkably, considering the conservation of plastome architecture between Sidalcea and Althaea, the former has a 237 bp deletion in the otherwise highly conserved inverted repeat region. Newly designed primers provide a PCR assay to determine presence of this indel across the Malvaceae. Screening of previously designed chloroplast microsatellite markers indicates two markers with variation within S. hendersonii that would be useful in future population conservation genetics. [ABSTRACT FROM AUTHOR]

Premise: Pollinator decline, by reducing seed production, is predicted to strengthen natural selection on floral traits. However, the effect of pollinator decline on gender dimorphic species (such as gynodioecious species, where plants produce female or hermaphrodite flowers) may differ between the sex morphs: if pollinator decline reduces the seed production of females more than hermaphrodites, then it should also have a larger effect on selection on floral traits in females than in hermaphrodites. Methods: To simulate pollinator decline, we experimentally reduced pollinator access to female and hermaphrodite Lobelia siphilitica plants. We compared the seed production of plants in the reduced pollination treatment to plants that were exposed to ambient pollination conditions. Within each treatment, we also measured directional selection on four floral traits of females and hermaphrodites. Results: Experimentally reducing pollination decreased seed production of both females and hermaphrodites by ~21%. Reducing pollination also strengthened selection on floral traits, but this effect was not larger in females than in hermaphrodites. Instead, reducing pollination intensified selection for taller inflorescences in hermaphrodites, but did not intensify selection on any floral trait in females. Conclusions: Our results suggest that pollinator decline will not have a larger effect on either seed production or selection on floral traits of female plants. As such, any effect of pollinator decline on seed production may be similar for gender dimorphic and monomorphic species. However, the potential for floral traits of females (and thus of gender dimorphic species) to evolve in response to pollinator decline may be limited. [ABSTRACT FROM AUTHOR]

Sexual dimorphism is expressed as different morphologies between the sexes of a species. Dimorphism is pronounced in gynodioecious populations which consist of female and hermaphrodite individuals. The small size of female flowers in gynodioecious species is often explained by resource re‐allocation to seed production instead of large flowers. However, pollinator attraction is critical to female fitness, and factors other than resource savings are needed to explain the small size of female flowers. We hypothesized that the floral size dimorphism in the perennial gynodioecious Geranium sylvaticum (L.) is adaptive in terms of pollination. To test this "pollination hypothesis," we video recorded the small female and large hermaphrodite G. sylvaticum flowers. We parameterized floral visitor behavior when visiting a flower and calculated pollination probabilities by a floral visitor as the probability of touching anther and stigma with the same body part. Pollination probability differed in terms of flower sex and pollinator species. Bumblebees had the highest pollination probability. The small female flowers were more likely to receive pollen via several pollinator groups than the large hermaphrodite flowers. The pollen display of hermaphrodites matched poorly with the stigma display of hermaphrodites, but well with that of females. Although the small size of female flowers is commonly explained by resource re‐allocation, we show that sexual dimorphism in flower size may increase the main reproductive functions of the females and hermaphrodites. Dimorphism increases pollination probability in females and fathering probability of the hermaphrodites likely driving G. sylvaticum populations towards dioecy. [ABSTRACT FROM AUTHOR]

• The objective of this study was to analyze the micromorphology and anatomy of E. angustifolia to enhance our comprehension of its sexual system and potentially apply this information to systematics. • E. angustifolia was gynodioecious, with two distinct floral morphs: hermaphroditic and female individuals. • The female flowers of E. angustifolia possessed abnormal indehiscent anthers containing sterile pollen grains. In contrast, the hermaphroditic flowers had dehiscent anthers with fertile pollen grains. • The main floral scent components of E. angustifolia were elsholtzia ketone and dehydroelsholtzia ketone. Gynodioecy is a sexual system in which hermaphrodites coexist with females and is frequently observed in Lamiaceae. The aim of this study was to investigate the floral morphology of Elsholtzia angustifolia (Loes.) Kitag (Lamiaceae) using stereomicroscopy (SM), light microscopy (LM), and scanning electron microscopy (SEM) to identify floral dimorphism in a potential gynodioecious species. Two different floral morphs were found in Elsholtzia angustifolia , hermaphroditic and female individuals, from three natural populations in South Korea (Ihwa Pass, Mt. Joryeong, and Mt. Sokli). However, females rarely occur in natural populations. Statistical analysis revealed significant size differences in the floral organs of the floral morphs. Micromorphological and anatomical characteristics were also examined using LM and SEM to compare the differences between the female and hermaphroditic types, revealing significant differences in the stamens between the two sexual types. Additionally, floral scent analysis was performed to identify floral morph-specific scent components, with elsholtzia ketone and dehydroelsholtzia ketone as the major components. [ABSTRACT FROM AUTHOR]

This research delves into plant–pollinator relationships within the Mediterranean region, focusing on two synchronous and sympatric asparagus species: A. acutifolius and A. albus. For the first time, the floral scents of the genus Asparagus are reported. We investigate the volatile organic compounds (VOCs) present in their floral scents and their impact on pollinator attraction. Captured flower-emitted VOCs underwent solid-phase microextraction of headspace (SPME-HS) and gas chromatography and mass spectrometry (GC-MS) analysis. The investigation confirms distinctive aroma profiles for each species. A. albus predominantly emits benzene derivatives and sesquiterpenes, while A. acutifolius is characterized by carotenoid derivatives, monoterpenes, and sesquiterpenes. The only shared compounds between the two species are the sesquiterpenes (Z,E)-α-farnesene and (E,E)-α-farnesene. A positive correlation links peak floral aroma intensity (benzenoids in A. albus and ionones in A. acutifolius) with a higher pollinator visit frequency, emphasizing the critical role of intense floral scents in pollinator attraction. The study of reproductive aspects reveals almost complete gynodioecy in A. acutifolius, influencing unique dynamics for the two species. These adaptations hold significant importance within the Mediterranean ecosystem, particularly during the late dry summer period, when a limited number of plant species vie for a shared primary pollinator.

Gynodioecy is assumed to be an evolutionary transition from hermaphroditism to dioecy. However, if hermaphrodites can better flexibly regulate seed production depending on resource availability than females, i.e. sex‐differential plasticity (SDP), gynodioecy can be a stable state. In the gynodioecious shrub Daphne jezoensis, hermaphrodites generally exhibit low seed fertility and largely act as males. We examined the SDP hypothesis and the cost of fruit production to clarify why D. jezoensis did not evolve into unisexual morphs.We evaluated the size and resource dependency of reproduction in field experiments by manipulating soil nutrient and light conditions. We compared the plant size and pollen production among females, fruiting hermaphrodites and non‐fruiting hermaphrodites. We then analysed the effect of current fruit production on subsequent flower production, i.e. the cost of fruit production.The fruiting ability was independent of plant size and resource availability in both sexual phenotypes, indicating the absence of SDP in D. jezoensis. Hermaphrodites produced larger‐sized pollen and allocated more resources to pollen production in the non‐fruiting year than in the fruiting year. In contrast, the cost of fruit production was not revealed for either sexual phenotype, even in the absence of pollen limitation, and even when fruit production was maximized.SDP could not explain the maintenance of hermaphrodites in D. jezoensis. Alternatively, the lower cost of fruit production in hermaphrodites due to their potentially low fruiting ability may hinder the evolutionary shift to dioecy. [ABSTRACT FROM AUTHOR]

Mating systems and seed reproduction in gynodioecious Geranium asiaticum Serg. (G.bifolium Patrin.) were studied in four coenopopulations of Western Siberia (Novosibirsk region). The bisexual flower of hermaphrodite individuals of G. asiaticum is characterized by a longer flowering (2.5–3.5 days) than the pistillate flower of female individuals (2–2.5 days), due to the passage of the male (staminate) phase at the beginning of morphogenesis: G. asiaticum is characterized by strict protandry. Mating of individuals of G. asiaticum occurs according to the type of xenogamy, autogamy is completely excluded. In an experiment to isolate individual flowers, 100% of isolated pistillate and bisexual flowers dried up without fertilization. In an experiment on artificial pollination of flowers, 85% (17 out of 20 flowers) of pistillate flowers formed fruits, whereas only 10% (3 out of 30 flowers) of bisexual flowers formed fruits. There were no significant differences in the number of flowers on the generative shoot in female and hermaphrodite individuals. Significant differences were found between heterosexual individuals in terms of the number of fruits and the number of seeds per generative shoot: female individuals formed 16.1–22.1 times more fruits and 13.8–28.3 times more seeds than hermaphrodites. Pistillate flowers formed an average of 1.85 ± 0.08 seeds per flower, and bisexual flowers 0.07 ± 0.02 seeds per flower, i.e., on average, female plants form 26.4 times more seeds than hermaphrodites. It was found that the fruits and seeds were formed mainly by female individuals, but hermaphrodite individuals produced the pollen necessary for fertilization. The different degree of sexual differentiation of G. asiaticum and Geranium sylvaticum L. suggests that in genus Geranium there are transformations in direction of the formation of dioecy. [ABSTRACT FROM AUTHOR]

Sexual dimorphism in plant growth and/or reproductive responses to the surrounding environment has been documented in some plant species. In gynodioecious plants, it is especially important to understand whether females and hermaphrodites differ in their response to environmental stressors, as the fitness of females relative to hermaphrodites determines the extent to which these separate sexes are maintained in natural populations. Soil nutrient availability is of particular importance given the different nutrient requirements of male and female sexual functions in plants. Here, we evaluated and compared the growth of females and hermaphrodites of Geranium maculatum in response to varying levels of nutrients. Using a greenhouse experiment, we manipulated the overall nutrient, nitrogen, and phosphorus levels in the soil and measured growth, allocation, and leaf quality responses in both females and hermaphrodites. We found that the sexes responded similarly in their growth and allocation responses to nutrient availability, despite evidence that female leaf chlorophyll content may have increased more than that of hermaphrodites across soil nitrogen levels. Our findings demonstrate that while hermaphrodites may differ from females in terms of their physiological response to varying nutrient levels, these slight physiological differences do not translate into meaningful growth differences. [ABSTRACT FROM AUTHOR]

Variation in population sex ratio is particularly pronounced in gynodioecious angiosperms. Extremely high female frequencies in gynodioecious populations cannot be readily explained by selective forces alone. To assess the contributions of drift and gene flow to extreme sex-ratio variation, we documented sex ratio and population size in 92 populations of Lobelia siphilitica across its range and genotyped plants using plastid and nuclear genetic markers. Similarity in spatial patterns of genetic and demographic variables may suggest that drift and/or gene flow have contributed to population sex-ratio variation in L. siphilitica. We found strong spatial structuring of extremely high female frequencies: populations with >50% female plants are restricted to the south–central portion of the range. However, we did not detect any spatial structuring in population size nor metrics of genetic diversity, suggesting that extreme variation in female frequency is not strongly affected by drift or gene flow. Extreme sex-ratio variation is frequently observed in gynodioecious plants, but its causes are difficult to identify. Further investigation into mechanisms that create or maintain the spatial structure of sex ratios in gynodioecious species will provide much needed insight. [ABSTRACT FROM AUTHOR]

Premise of research. Plants could respond to declines in pollination services by delaying floral senescence and thus increasing floral longevity. While a plastic increase in longevity could augment seed production by prolonging the opportunity for pollination, it could also reduce seed production if resources are allocated to floral maintenance rather than ovule maturation. However, this reduction in seed production could differ between females and hermaphrodites in gynodioecious species if more resources are required to maintain the larger corollas of hermaphrodite flowers. Methodology. To test whether increased longevity incurs costs of floral maintenance that reduce seed production, we manipulated the pollination of female and hermaphrodite Lobelia siphilitica flowers. We tested whether pollen receipt induces floral senescence, as expected if delayed pollination increases longevity, by measuring the days from corolla opening to wilting for unpollinated flowers and flowers pollinated on day 1 of the female phase. We then tested whether increased longevity reduces seed production by hand-pollinating female and hermaphrodite flowers on day 1 or day 5 of the female phase and counting seeds per fruit. Pivotal results. Relative to the corollas of unpollinated flowers, the corollas of pollinated flowers senesced 50% earlier for females and 14.4% earlier for hermaphrodites. Increased longevity reduced seed production by 34.1%, but there was no difference in the magnitude of this reduction between females and hermaphrodites. Conclusions. Our results suggest that L. siphilitica could respond plastically to declines in pollination services by increasing floral longevity but that this increase incurs costs of corolla maintenance that reduce the seed production of both females and hermaphrodites. Consequently, whether plasticity in longevity can help plants maintain seed production as pollinators decline will depend on whether the resource costs of floral maintenance are outweighed by the benefits of a prolonged opportunity for pollination. [ABSTRACT FROM AUTHOR]

A new genus, Andea van der Werff, is described. It consists of 25 gynodioecious species, all occurring in the Andes except for one species found in the mountains of Costa Rica. Morphological characteristics are discussed and a key to the species is presented. [ABSTRACT FROM AUTHOR]

Dioecy, the separation of sex at the individual level, evolved in angiosperms from hermaphroditic ancestors. One of the postulated evolutionary pathways is by way of the gynodioecious stage, i.e., the coexistence of female and hermaphroditic individuals. In a morphologically gynodioecious species, Daphne jezoensis., seed fertility in hermaphrodites is limited compared to that of females, indicating that its sexual system is close to dioecy. The aim of this study was to clarify whether the gynodioecy in this species is a stable sexual system or a transitional state leading to dioecy. We evaluated variations in the degree of pollen limitation, sexual and mating systems, floral morphology, sex ratio, and the genetic structure of 14 populations across the species’ distribution range in Japan. Sexual systems were similar among populations throughout the distribution range although the southernmost populations had unique genetic structures to some extent. Hermaphrodites were commonly self-compatible, but their fruiting capacity was low in every population. This suggests that gynodioecy composed of females and hermaphrodites having low seed fertility is a consistent sexual system in D. jezoensis. Low seed fertility in hermaphrodites throughout the distribution range suggests that this sexual system is not necessarily a transitional state from gynodioecy to dioecy if occasional seed production in hermaphrodites has any advantage. One possible ecological advantage for the maintenance of hermaphrodites is that seed production by autonomous self-pollination may be beneficial in the colonization process after long-distance seed dispersal. [ABSTRACT FROM AUTHOR]

In gynodioecious systems, female plants must counteract the selective disadvantage of not passing genes via pollen production, as hermaphrodites can. Theory predicts that females must produce more or better‐quality seeds than hermaphrodites in order to be maintained within the same population. This female advantage has been widely measured and reported for seed number, but whether female advantage is gained through the production of better seeds remains relatively under‐studied.Here, a meta‐analysis approach was used to investigate whether females in gynodioecious species produce seeds of better quality than hermaphrodites (measured as seed mass, seed nutrient content, seed germinability and seedling survival and performance) in addition to achieving a larger seed production. In total, 50 studies were included, reporting traits for 34 gynodioecious species in 17 different families.Female advantage was significant for seed number and seed germination, but was not detected for seed mass, seed nutrient content or seedling performance.A female advantage in seed number was corroborated in this meta‐analysis, which together with better seed germination, may explain maintenance of female plants within gynodioecious populations. [ABSTRACT FROM AUTHOR]

Thyme (Thymus spp.) is a valuable genus of Lamiaceae family presents a wide range of functional possibilities in the cosmetic, pharmacy, and food industries. T. daenensis and T. pubescens are thymol and carvacrol rich species growing in Iran. The aim of this study was to compare the macro- and micro-morphological, cytogenetical, and biochemical traits present in hermaphrodites and females of T. daenensis and T. pubescens. The analyses were performed by light microscopy (LM) to be compatible with scanning electron microscope (SEM) and gas chromatograph–mass spectrometry (GC–MS). The principal component analysis (PCA) loading plot was carried out using the original numerical data of quantitative characters (e.g., morphological, functional, and life-history traits). Results of gynodioecy analysis showed that the distribution of females in T. daenensis (58.33%) was significantly more than T. pubescens (9.1%). Peltate and capitate glandular trichomes (PGTs and CGTs, respectively) existed in both hermaphrodites and females of T. daenensis and T. pubescens. The size of PGTs in hermaphrodites was significantly larger than these GTs in females. The highest level of thymol and carvacrol was observed in both sexes of T. daenensis and T. pubescens, respectively. The results of the non-metric multidimensional scaling (NMDS) ordination showed separation of hermaphrodite and female types according to essential oil (EO) components. Based on the flow cytometric analysis, the obtained histograms confirmed that T. pubescens and T. daenensis were diploid and tetraploid, respectively. Variation among species and environmental/geographical factors result is differences in the content of thymol and carvacrol in various Thymus species which should be taken into consideration when applying these plants as therapeutic products. [ABSTRACT FROM AUTHOR]

Island plants provide special opportunities for the study of evolution and ecology. In field and greenhouse studies we characterized a model reproductive system for Plocama pendula , endemic to the Canary Islands. This species has a complicated and not immediately obvious reproductive system. Pollination is biotic, and all flowers are morphologically hermaphroditic, but half of the plants characteristically bear flowers with nectar, pistils with reflexed stigmatic lobes and pollen-less anthers (i.e. they are functionally female flowers). The other half bear nectar-less flowers with abundant pollen and full-sized pistils that mostly have un-reflexed stigmatic lobes (i.e. they are hermaphroditic flowers functioning mostly as males). However, experiments show these pollen-bearing flowers to be self-compatible. Thus, the functionally male flowers have a breeding system that allows selfing in limited circumstances, but the functionally male flowers produce far fewer fruits than do functionally female flowers. With morphologically gynodioecious, functionally largely dioecious flowers, sometimes capable of selfing, the reproductive system of this species could be labelled as 'leaky' in many respects. Thus, we propose that P. pendula has colonized new habitats and persists in substantial populations at least in part because it manifests a reproductive system that is a model for successfully balancing the often-conflicting evolutionary demands of colonization, establishment and persistence. [ABSTRACT FROM AUTHOR]

Background and Aims Most angiosperms rely on pollinators to transport pollen and effect fertilization. While some floral visitors are effective pollinators, others act as thieves, consuming pollen but effecting little pollination in return. The importance of pollen theft in male and female reproductive success has received little attention. Here, we examined if pollen consumption by flies altered pollen receipt and exacerbated pollen limitation for a bumblebee-pollinated plant, Polemonium foliosissimum (Polemoniaceae). Methods To examine the effect of pollen-thieving flies, we took a three-pronged approach. First, we used single-visit observations to quantify pollen removal and pollen deposition by flies and bumblebees. Second, we manipulated pollen in the neighbourhood around focal plants in two years to test whether pollen reduction reduced pollen receipt. Third, we combined pollen reduction with hand-pollination to test whether pollen thieving exacerbated pollen limitation. Polemonium foliosissimum is gynodioecious in most populations in the Elk Mountains of central Colorado, USA. Thus, we also tested whether pollen theft affected hermaphrodites and females differently. Results Flies removed significantly more pollen and deposited less pollen per visit than did bumblebees. Reduction of pollen in the neighbourhood around focal plants reduced pollen receipt in both years but only nearly significantly so in 2015. In 2016, plants were significantly pollen-limited; hand-pollination significantly increased seeds per fruit for both hermaphrodites and females. However, the reduction of pollen around focal plants did not exacerbate pollen limitation for either hermaphrodites or females. Conclusions Our results suggest that plants tolerate significant consumption of pollen by thieves and pollinators by producing ample pollen to feed both and fertilize available ovules. Our results demonstrate that pollen limitation in P. foliosissimum is driven by lack of effective pollinators rather than lack of pollen. Teasing out these effects elucidates the relative importance of drivers of reproductive success and thus the expected response to selection by different floral visitors. [ABSTRACT FROM AUTHOR]

Premise of research. Whole-genome duplication is often associated with the evolution of dimorphic sexual systems; however, the association is not universal, and the evolutionary pathway(s) underlying the association remain unresolved. The genus Lycium has been demonstrated as a useful system for investigating ploidy and sexual system variation. Here, we describe ploidy and floral variation in L. australe and document genetic diversity and dimorphism across its range. Methodology. Sexual system and size dimorphism were assessed using morphological measurements of 486 flowers. Flow cytometry was used to determine DNA content and ploidy level for 167 plants from across the species range. Using the plastid region trnH-psbA and restriction site–associated DNA sequencing (RADseq), we explored the genetic structure of the species, including an examination of associations of ploidy and sexual system with genetic structure. Pivotal results. We find correlated variation in ploidy level, sexual system, and genetic structure in L. australe. Both gynodioecy and dioecy are documented and are associated with diploidy and polyploidy, respectively. Floral size dimorphism is also found among morphs in both sexual systems. We find significant genetic structure associated with ploidy level and geography based on genome-wide single-nucleotide polymorphisms and plastid haplotypes. Conclusions. We show that L. australe has associated polymorphism in sexual system and ploidy, but the association is an exception to the pattern in the genus. Genetic and ploidy variation in the species suggests potential reproductive barriers and ecological differentiation between cytotypes of differing ploidies. The widespread parapatric distributions of diploid and polyploid L. australe make it an ideal system for studying questions related to reproductive compatibility, ecological differentiation, and polyploid speciation. [ABSTRACT FROM AUTHOR]

The origin and establishment of gender dimorphism has been postulated as a key element in the evolution of insular floras but has generally not been studied in an explicit phylogenetic framework. We tested the prior conclusion that the origin of gender dimorphism in the New Zealand species of Gaultheria Kalm ex L. is allochthonous by newly tracing the evolution of gender dimorphism on a phylogenetic tree of the Wintergreen Clade. We scored species for male sterility and breeding system type (cosexual, gynodioecious, or dioecious) based on the literature, and observations from the field and herbarium specimens. We traced the evolution of gender dimorphism, fruit evolution, and ancestral areas on the tree with parsimony, maximum likelihood, and Bayesian methods. Our analyses revealed that male sterility in New Zealand most likely emanated from a male-sterile fleshy red-fruited South American lineage, with reversals to cosexuality in two or three Australian lineages of the more inclusive Australasian Clade. The results support an allochthonous origin of gynodioecy in New Zealand Gaultheria and corroborate arrival of the ancestral ancestor through over-water dispersal, likely by birds. Although gender dimorphism could have arrived to New Zealand as a preadaptation to avoid inbreeding depression in an island setting, its correlation with fleshy fruit, unspecialised flowers, and woody habit across the genus suggests that factors other than the island setting per se are responsible for its maintenance in New Zealand. Although gender dimorphism in New Zealand has usually arisen autochthonously in dry-fruited genera, in Gaultheria the presence of gynodioecy in several dry-fruited species is best explained by its retention from fleshy-fruited ancestors. [ABSTRACT FROM AUTHOR]

Female flowers of gynodioecious plants usually have smaller corollas than bisexual flowers. This difference is explained as a developmental consequence of stamen abortion and as a result of stronger selection for larger corolla size in hermaphroditic flowers that solely ensure male function within populations. This study evaluated whether the size difference of zygomorphic corollas in a widely distributed gynodioecious herb Glechoma hederacea is accompanied by variation in shape and bilateral fluctuating asymmetry of sexually differentiated flowers. Geometric morphometric analyses of bilateral symmetry in the shapes of corolla lower lips showed that male-sterile flowers were significantly more plastic and asymmetric, implying that they may be subjected to weaker stabilizing selection for corolla shape in comparison to hermaphrodites. These results illustrated that sexual differentiation may be an important factor contributing to bilateral fluctuating asymmetry in the shape of zygomorphic flowers. [ABSTRACT FROM AUTHOR]

The behavioural patterns of flower-visiting insects are influenced by floral display size, floral reward, etc. We tested whether insects of various taxa visiting Cimicifuga simplex would change their behaviour between hermaphroditic and female flowers. Male-phase flowers of hermaphroditic ramets provide flower visitors with nectar and pollen as rewards, whereas female flowers of female ramets provide flower visitors with only nectar. The appearance of the both sexes in C. simplex is different with hermaphrodite being relatively large and female ramet being relatively small. Therefore, to investigate how sexual differences in floral rewards and conspicuousness affect flower visitor behaviour, we compared flower visitor behaviour between male-phase hermaphroditic ramets and female ramets. C. simplex was visited by the bumblebee Bombus beaticola beaticola (Hymenoptera), Vespula flaviceps (Hymenoptera), Anthomyiidae spp. (Diptera), Episyrphus balteatus (Diptera), and Pidonia aegrota (Coleoptera). The visitation frequency of all visitors, especially of bumblebees and dipteran insects, to male-phase hermaphroditic ramets was higher than that to female ramets. The number of flowers contacted per single visit to an inflorescence was significantly higher for hermaphroditic ramets than for female ramets in bumblebees, but no difference was found in other insect groups. These results suggest that bumblebees visit the low-reward female ramets less often than male-phase hermaphroditic ramets, and they stay on female ramets for a shorter time. In contrast, insects other than bumblebees seem to decide which flowers to visit according to how conspicuous the flowers are, but once they visit a ramet they continue to visit flowers on the ramet even if no pollen rewards there are. [ABSTRACT FROM AUTHOR]

Abstract Background Gynodioecy, a sexual system with hermaphrodite and female individuals in a population, raises the question how the two sexual morphs are maintained. Salvia pratensis is a gynodioecious species featured by its modified stamens that act as a lever mechanism in pollination. Given sexual dimorphism in floral traits of the species, it is predictable that two sexual morphs differ in their interplay with pollinators and thus in their fitness. In this study, we investigated sex-specific reproduction success and floral adaptation in a population of S. pratensis. Results We found that two sexual morphs in S. pratensis distinctly differed in their floral proportions. Female flowers fitted better to the pollinators than hermaphrodites in terms of touching the stigmas when being probed, and hence were more efficient in pollen deposition. Floral traits overall underwent stronger selection in the population, with stigma position and corolla length subject to disruptive selection mediated by different body-sized bumble bees; some selections on floral traits were significantly different in the strength, even opposite in the direction between two morphs. Flower production tended to be under correlational selection with floral structural traits, implying that a large plant with many flowers did not show an advantage in fitness unless its flower construction mechanically matched the pollinators well. Conclusions In conclusion, the pollinator-mediated selection likely played an important role in the evolution and maintenance of sexual dimorphism in the gynodioecious S. pratensis; and sex-divergent mechanical interaction with pollinators served as a critical mechanism by which female individuals were maintained in the population with a female advantage in pollen deposition efficiency (i.e. receiving pollen).

Plant speciation results from intricate processes such as polyploidization, reproductive strategy shifts and adaptation. These evolutionary processes often co-occur, blurring their respective contributions and interactions in the speciation continuum. Here, relying on a large-scale study, we tested whether gynodioecy triggers the divergent evolution of flower morphology and genome between sexes, and contributes to the establishment of polyploids and colonization of ecological niches in Stellaria graminea. We found that gynodioecy in S. graminea leads to flower morphology divergence between females and hermaphrodites, likely due to sexual selection. Contrary to our expectations, gynodioecy occurs evenly in diploids and tetraploids, suggesting that this reproductive strategy was not involved in the establishment of polyploids. Both diploid and tetraploid females have a larger genome size than hermaphrodites, suggesting the presence of sex chromosomes. Finally, ecology differs between cytotypes and to a lesser extent between sexes, suggesting that the link between environment and presence of females is indirect and likely explained by other aspects of the species’ life history. Our study shows that gynodioecy leads to the consistent evolution of sexual traits across a wide range of populations, cytotypes and environments within a given species, and this likely contributes to the phenotypic and genetic distinctiveness of the species from its sister clades.

Background: The breeding system of Mammillaria magnimamma was initially described as hermaphroditic. However, some individuals in a natural population at Valle del Mezquital exhibited a seemingly non-functional androecium. Objectives: To determine the breeding system of M. magnimamma through morphological characterization of floral types. Study site and years: The study was conducted at Valle del Mezquital, Mexico, during the 2019 reproductive season. Methods: We characterized floral polymorphism by means of scanning electron microscopy and morphometric analysis of 18 floral traits. Pollinator frequency, size and number of seeds, and germination rate were compared between flower types. Results: 87.85 % of the plants were hermaphrodites, and 12.15 % were females with non-functional androecium, with significantly smaller stamens, indehiscent anthers, and malformed pollen. Female flowers were shorter (14.007 ± 0.742 mm) and had smaller (1.856 ± 0.151 mm) nectar chambers than hermaphroditic flowers (15.821 ± 0.450 and 2.194 ± 0.090 mm, respectively). Although pollinators visited hermaphrodites (124 visits) about twice as often as pistillate flowers (60 visits), the latter produced more numerous (F1,26 = 8.320, P = 0.003) and larger (Hc = 4.637, P = 0.031) seeds that also germinated faster (Hc = 70.59, P < 0.0001). Conclusions: This M. magnimamma population exhibits a gynodioecious breeding system with both hermaphroditic and male sterile female plants. Females produce more, higher quality seeds, which favour their maintenance in the population.

Plant speciation results from intricate processes such as polyploidization, reproductive strategy shifts and adaptation. These evolutionary processes often co-occur, blurring their respective contributions and interactions in the speciation continuum. Here, relying on a large-scale study, we tested whether gynodioecy triggers the divergent evolution of flower morphology and genome between sexes, and contributes to the establishment of polyploids and colonization of ecological niches in Stellaria graminea. We found that gynodioecy in S. graminea leads to flower morphology divergence between females and hermaphrodites, likely due to sexual selection. Contrary to our expectations, gynodioecy occurs evenly in diploids and tetraploids, suggesting that this reproductive strategy was not involved in the establishment of polyploids. Both diploid and tetraploid females have a larger genome size than hermaphrodites, suggesting the presence of sex chromosomes. Finally, ecology differs between cytotypes and to a lesser extent between sexes, suggesting that the link between environment and presence of females is indirect and likely explained by other aspects of the species' life history. Our study shows that gynodioecy leads to the consistent evolution of sexual traits across a wide range of populations, cytotypes and environments within a given species, and this likely contributes to the phenotypic and genetic distinctiveness of the species from its sister clades. [ABSTRACT FROM AUTHOR]

Variation in population sex ratio is particularly pronounced in gynodioecious angiosperms. Extremely high female frequencies in gynodioecious populations cannot be readily explained by selective forces alone. To assess the contributions of drift and gene flow to extreme sex-ratio variation, we documented sex ratio and population size in 92 populations of Lobelia siphilitica across its range and genotyped plants using plastid and nuclear genetic markers. Similarity in spatial patterns of genetic and demographic variables may suggest that drift and/or gene flow have contributed to population sex-ratio variation in L. siphilitica. We found strong spatial structuring of extremely high female frequencies: populations with >50% female plants are restricted to the south–central portion of the range. However, we did not detect any spatial structuring in population size nor metrics of genetic diversity, suggesting that extreme variation in female frequency is not strongly affected by drift or gene flow. Extreme sex-ratio variation is frequently observed in gynodioecious plants, but its causes are difficult to identify. Further investigation into mechanisms that create or maintain the spatial structure of sex ratios in gynodioecious species will provide much needed insight.

Floral traits and sexual systems in angiosperms are strategies that enhance outcrossing within hermaphrodite flowers and among individuals in a population. Sexual systems with unisexual flowers have also evolved among angiosperms, resulting in sex specialization. Furthermore, the interaction of floral traits and floral visitors determines successful plant reproduction. Globose cacti are bee pollinated, and variation in the diversity of their pollinator assemblages is strongly associated with floral phenotype. Our objective was to describe the floral biology of the cactus Coryphantha elephantidens and to determine its relationship with pollinators. Floral traits were studied by direct observations in live and fixed flowers. The breeding system was determined using two estimators based on floral morphology: pollen grains to ovules per flower (P/O) ratio and outcrossing index. Pollination treatments were conducted to determine the mating system. Floral visitors were recorded using direct observation. Flowers of C. elephantidens are variable in color, protandric, herkogamous and nectarless. Estimators of the breeding system indicated xenogamy, which is consistent with the obligate outcrossing revealed by the pollination experiment. Thirty‐seven percent of the plants have female flowers that do not produce pollen, making this population functionally gynodioecious. Both fruit and seed set were high compared to other globose cacti. Pollinators included eight species of native bees, a more diverse pollinator assemblage than other globose cacti. Given the high pressure on pollen due to functional gynodioecy, nectarless flowers, an outcrossing mating system, and the necessity of pollinators to set seeds, we concluded that native bees are highly efficient pollinators that play a crucial role in the sexual reproduction of C. elephantidens. [ABSTRACT FROM AUTHOR]

Generalized pollination systems may be favored in early spring flowering plants, as during this period pollinator activity is unpredictable. Many previous studies have concentrated on the importance of diurnal visitors in pollination, and consequently, information on the contribution of nocturnal visitors to pollination in early spring is limited. This study was conducted to evaluate the relative importance of diurnal and nocturnal pollinators in the early spring flowering dioecious shrub Stachyurus praecox (Stachyuraceae), in two temperate forests in central Japan. Visitors to the female and male flowers were observed during day and night, and their relative contributions to seed set were compared. The pollinator observations revealed that the diurnal and nocturnal insects visited both male and female flowers, and that the main flower visitors were diurnal small bees and flies as well as nocturnal settling moths. The diurnal and nocturnal flower visitors also acted as pollinators, as the pollen grains of S. praecox were attached to the insects collected from the female flowers. Pollination experiments demonstrated that the contributions of diurnal pollinators to the seed set were higher than those of the nocturnal pollinators. The results of this study indicate that S. praecox has a generalized pollination system, comprising both diurnal insects and nocturnal settling moths. Although the roles of diurnal insects are more important in the pollination of S. praecox, nocturnal settling moths may have a complementary role in early spring. [ABSTRACT FROM AUTHOR]

Plants have developed numerous strategies to maximise resource uptake in response to the highly heterogeneous resource distribution in soils. Clonal growth enables plants to scavenge larger surfaces, potentially maximising nutrient acquisition by selectively growing in nutrient-rich patches. However, the production of clonal units put plants into higher intraspecific competition. In gynodioecious clonal plants, genders usually exhibit sexual dimorphism in several growth and life history traits, but whether the genders have different competitive abilities and whether these are affected by nutrient distribution is underexplored. Here, we investigated whether the genders of Glechoma hederacea have different competitive abilities and whether these are affected by soil nutrient distribution using a greenhouse pot experiment. Female and hermaphrodite ramets were grown either alone or in competition with the same or the opposite gender in two different soil nutrient distributions for four months. Our results show that competition was the strongest factor affecting biomass accumulation and allocation. Females and hermaphrodites showed little sexual dimorphism in total biomass accumulation, but they differed in how they allocated this biomass between roots and shoots and in their clonal growth strategies in response to soil nutrient distribution. Taken together, our results indicate that soil nutrient distribution affects the competitive abilities of G. hederacea in a gender-specific manner. In the field, these differences would determine the structure and the dynamics of the two genders within the populations. [ABSTRACT FROM AUTHOR]

Gynodioecy, the co-occurrence of female and hermaphrodite plants in the same population is relatively common in the genus Thymus, where a high and variable female frequency has been reported in several species, populations and years. In most gynodioecious species, female plants produce more and/or better seeds than hermaphrodite plants, facilitating female maintenance in natural populations. Thymus × arundanus and T. granatensis are two sympatric gynodioecious species that inhabit the region of Andalucia, Spain. Here we studied reproductive components in two different years (1987 and 2016) as flower number, fruit-set, seed number and seed mass, and their possible relation to female frequencies in those years in natural populations of both species. In T. × arundanus, mean female frequency (59%) was ten times higher than that of T. granatensis (5%). Female frequency was relatively constant in T. × arundanus after almost 15 years (1987–2016), and in T. granatensis low female frequencies were observed (0–5%) with the exception of one population (18%). However, reproductive components were variable among species, years and genders, showing no consistent female fertility advantage. High female frequencies in T. × arundanus are not likely to be maintained by female fertility advantage but stochastic and pleiotropic effects on sex determination may play a relevant role in sex ratio variation in the studied populations of both species. [ABSTRACT FROM AUTHOR]

Origanum vulgare L. is a gynodioecious species, populations of which include hermaphroditic plants with bisexual flowers and female plants with pistillate flowers. This is a holarctic forest–steppe species belonging to herbaceous perennial plants. The variability of the female-to-hermaphrodite ratio in 26 coenopopulations of O. vulgare from different habitats has been studied. The data on eight populations were obtained in the course of the authors' studies in southern Siberia, while 18 populations from Eastern Europe were analyzed based on the published data of other researchers. For all habitats, the projective cover of the species was determined according to the standard geobotanical methods. The plants studied represented a long-rhizome life form, so a partial shoot or a partial shrub (ramets) was used as a countable unit. The gender structure of coenopopulations was studied by counting generative plants within transects with an area of 10 to 20 m2. For each population, the total number of plants to be counted was at least 90. A significant positive correlation between the projective cover of O. vulgare in a phytocenosis and the percentage of female plants in coenopopulations was revealed (the Pearson correlation coefficient r = 0.86, p = 0.001). The ANOVA analysis showed no significant difference in the percentage of female plants in six different habitats (Femp = 3.36; Fcrit 5.5 = 5.1; p = 0.05). Taking into account the morphological and reproductive features of different genders of O. vulgare, one can suggest that an increase in the projective cover of the species in a phytocoenosis and an increase in the percentage of female plants in the gender spectrum depend on successful seed regeneration in the phytocenosis. [ABSTRACT FROM AUTHOR]

Background. In gynodioecious species, populations of two types of individuals are found – bisexual and female. The morphological and biological characteristics of these two morphs are different. A. reptans is an example of a gynodioecious species. However, information about the flowering biology of both its sexual forms is extremely fragmented. The aim of our research is to study the flowering of A. reptans’ bisexual and female morphs in the Moscow region. Materials and methods. Anthecological observations were made in natural conditions in the Moscow region from 2015 to 2019 according to generally accepted methods. Results. The floral unit of A. reptans is the apical open bracteose thyrsus, which has constituent elements of 3 or 5 flower cymoids. In lateral dichasium, the flower opens acropetally; in the thyrsus, flowers on the axis bloom almost simultaneously. Bisexual flowers of A. reptans are characterized by a weak protandry. Bisexual and pistillate flowers have a long lifespan, surviving for 12–13 days without pollination. A. reptans is characterized by a daily flowering rhythm, with two maximums at 9 a.m and 12 a.m. Bisexual and pistillate flowers open simultaneously. Conclusions. A number of anthecological characters of A. reptans demonstrate that it flowers in spring: the lack of a clear acropetal sequence in the order of flowers blooming in a thyrsus, the long lifespan of both bisexual and pistillate flowers, the opening of flowers during almost all daylight hours, and a fairly short flowering period, due to the need for development in a strictly defined period of vegetation.

Abstract Cimicifuga simplex has three genetically and ecologically distinct pollination morphs with different flowering phenology, flower sex expressions, and selfing rates. A previous study showed that strong protandry in hermaphroditic flowers of C. simplex causes there to be seasonal minority sexes; for example, unisexual female ramets are advantageous in the first half of the flowering season and bloom then (minority sex hypothesis). That study, however, did not distinguish among the three pollination morphs of C. simplex. We investigated seasonal sex ratio changes and pollinator environments of the three morphs to verify and expand the minority sex hypothesis. We investigated flowering phenology, pollinator quantity and quality, seasonal population sex ratio dynamics, and stamen/ovule ratios in hermaphroditic flowers. We also examined the seasonal female reproductive success of hermaphroditic flowers, and the effect of male flower excision on fruit set by morph II hermaphroditic flowers. Morph I (mainly hermaphroditic and female ramets) had high pollinator quality and quantity. Fruit set of hermaphroditic ramets was high throughout the flowering season. Morph II (hermaphroditic and andromonoecious ramets) had low pollinator quality, and few pollinators visited near the beginning and end of the season. Removal of male flowers led to a pollen limitation. Morph III (hermaphroditic ramets and a high selfing rate) had very low pollinator abundance throughout the flowering season, and male and female phases largely overlapped. The scarcity of male flowers in morph I is likely a result of the high pollinator quantity and quality. The high fruit set suggests that no pollen limitation existed. The low pollinator quality and quantity of the morph II population caused it to suffer from pollen limitation and may explain the absence of unisexual female ramets in this morph. The high selfing rate of morph III may be due to the extremely low pollinator abundance. Theoretical studies have indicated that the optimal investment allocation to male and female functions depends on whether a pollen limitation exists. In C. simplex, the observed relationships between pollinator environment and reproductive systems are consistent with these theoretical models.

Gynodioecy is typically associated with a smaller perianth size in purely pistillate flowers than in hermaphrodite flowers. However, it is unclear whether this size differentiation is associated with any differences in flower shape between the two sexual groups. A geometric morphometric analysis of the symmetry of tetrameric corolla shapes was used in the study of Euonymus europaeus L., Darwin’s classical system of floral sexual differentiation. I investigated whether there are any shape differences between the female and bisexual flowers, with respect to both purely symmetric variation involving coordinated shape changes of the four petals and asymmetry among petals within flowers. The corolla shapes of the female and bisexual flowers and the variability among flowers within each sexual group were very similar in the purely symmetric components of shape variation. However, the female flowers were significantly more asymmetric with respect to both the lateral and transversal asymmetry of their corolla shapes. This is the first study to apply geometric morphometrics in the analysis of morphological patterns in a sexually differentiated gynodioecious plant system. The results showed that subtle shape differences in corolla asymmetry differ between the sexual groups and indicate diverging developmental or selection signals between the sexes.