Androgyny of individuals and polygamy in populations of Salix myrsinifolia Salisb. in the south-western part of its geographical range (NE-Poland)

The aims of the study were to describe the phenomenon of androgyny (a change in the sexual behaviour of individuals) in Salix myrsinifolia, and to consider the implications of androgyny for the sex structure of local populations and for the sex structure of the species across a larger geographical range. Field surveys of the sexual behaviour of individuals and populations of Salix myrsinifolia were carried out over nine years (1989–1997) in an area of 40,000 km² of NE-Poland. More detailed studies were performed on populations in Polana Białowieska (the Białowieża Clearing) in the Białowieża Primeval Forest, in the Białystok area, in the Biebrza Valley and in the experimental garden and laboratory of the Białowieża Geobotanical Station.

The bisexuality of Salix myrsinifolia is basically expressed through the development of a number of different forms of catkin that are intermediate between those that are entirely male and those that are entirely female. Flowers on bisexual catkins are fully developed, as on monosexual ones, but the male segment usually develops prior to the female one. With the exception of one form, a clear partitioning between the male and female parts of the catkin remains. This partitioning of the genders mainly takes place transversely, but in one case longitudinally. It is thus usually possible to speak of the division of a bisexual catkin into male and female sectors.

In all three populations studied in detail, marked shrubs, on which bisexuality had been noted at the beginning, retained this trait throughout the 9-year observation period. However, there were changes in both the expression of bisexuality, i.e. the frequency of bisexual and monosexual catkins, and in the frequency of different patterns of bisexual catkin. Only bisexual individuals with a clear prevalence of female features retained their character. In the two larger populations studied, many originally monosexual individuals became bisexual during the study period.

In the south-western part of the range of S. myrsinifolia in NE-Poland all local populations were characterized by the presence of bisexual individuals and are thus polygamous. There was a close association between the presence of S. myrsinifolia and the degree of ruderalization of habitats. The degree of polygamy in a population was also significantly correlated with ruderalization. It is concluded that androgyny and polygamy may be favoured not only by changes in environmental conditions, but also by the particular pressures to which individuals and populations of a species may be subject at the edge of its geographical range.     

Genetic diversity,sexual condition,and microhabitat preference determine mating patterns in Sphagnum (Sphagnaceae) peat‐mosses

In bryophytes, the possibility of intragametophytic selfing creates complex mating patterns that are not possible in seed plants, although relatively little is known about patterns of inbreeding in natural populations. In the peat‐moss genus Sphagnum, taxa are generally bisexual (gametophytes produce both sperm and egg) or unisexual (gametes produced by separate male and female plants). We sampled populations of 14 species, aiming to assess inbreeding variation and inbreeding depression in sporophytes, and to evaluate correlations between sexual expression, mating systems, and microhabitat preferences. We sampled maternal gametophytes and their attached sporophytes at 12–19 microsatellite loci. Bisexual species exhibited higher levels of inbreeding than unisexual species but did generally engage in some outcrossing. Inbreeding depression did not appear to be common in either unisexual or bisexual species. Genetic diversity was higher in populations of unisexual species compared to populations of bisexual species. We found a significant association between species microhabitat preference and population genetic diversity: species preferring hummocks (high above water table) had populations with lower diversity than species inhabiting hollows (at the water table). We also found a significant interaction between sexual condition, microhabitat preference, and inbreeding coefficients, suggesting a vital role for species ecology in determining mating patterns in Sphagnum populations. © 2015 The Linnean Society of London, Biological Journal of the Linnean Society, 2015, 115 , 96–113.     

Potential for parthenogenesis of virgin females in a bisexual population of the geographically parthenogenetic mayfly Ephoron shigae (Insecta: Ephemeroptera,Polymitarcyidae)

The burrowing polymitarcyid mayfly Ephoron shigae is a geographically parthenogenetic species. Interestingly, the distributions of the bisexual and unisexual populations overlap broadly in their respective geographic ranges. In this mayfly, obligatory diploid thelytoky appears within unisexual populations. In the present study, we examined the potential for parthenogenesis or the parthenogenetic ability of females in a bisexual population aiming to understand the emergence of unisexual populations. The results obtained revealed that females in the examined bisexual populations showed a potential for diploid thelytoky as also seen in the unisexual populations, although, in females from bisexual populations, the development success rates of their unfertilized eggs were considerably lower than those of virgin females from unisexual populations. In the three bisexual reproducing species (Ephemera japonica, Ephemera strigata, and Ephemera orientalis) in the closely‐related family Ephemeridae, diploid thelytoky (i.e. tychoparthenogenesis; < 3%) was also observed. However, in this case, the parthenogenetic development success rates of unfertilized eggs were significantly lower than those of virgin females in the bisexual (Hino‐yosui Irrigation Canal) population of E. shigae. Accordingly, we suggest that parthenogenetic ability (i.e. tychoparthenogenesis or facultative parthenogenesis) in bisexual populations of E. shigae may facilitate the evolutionary transition to unisexual populations with fully obligatory parthenogenesis. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 99 , 326–334.     

Variation in the sexual behaviour of Achnanthes longipes (Bacillariophyta). III. Progeny of crosses between monoecious and unisexual clones

The allogamous raphid diatom Achnanthes longipes C. A. Agardh possesses a complex breeding system involving interactions between three types of clone: monoecious, unisexual and bisexual. Previous studies showed that these three types can be crossed with each other, with a tendency for sexual characteristics to be inherited: inbred monoecious lineages gave rise to monoecious or, very rarely, to bisexual clones, while inbred unisexual lineages yielded unisexual and bisexual clones. The current paper reports on the progeny of crosses between monoecious and unisexual clones and their inbred offspring. All three types of clone appeared in the F₁ and F₂, although unisexual clones of opposite sex to the parental clone were not found. Inbreeding depression was observed and also a tendency for ‘normal’ auxosporulation (producing two auxospores per pair of gametangia) to be replaced by ‘reduced’ or ‘intermediate’ auxosporulation (producing one auxospore per pair). In addition, patterns of incompatibility were observed that were not seen during earlier studies of clones isolated directly from nature. These included the inability of some F₁ clones to mate with each other, in spite of compatibility with all other clones examined (unisexual, bisexual and monoecious).     

Geographic parthenogenesis in the stream mayfly Eurylophella funeralis in eastern North America

Unisexual populations were found largely at the periphery of the geographic range of the mayfly Eurylophella funeralis in eastern North America. Bisexual populations generally had a normal sex ratio but at least two populations were observed with only about 2–11% males. Hatch success for unfertilized eggs depended on temperature but in general averaged >61% in unisexual populations and < 14% in bisexual populations. Eggs took about 65 d to hatch at 10°C and 19 d at 25°C; no hatching occurred at 5 or 30°C. Successful oviposition was observed for about 97% and 20% of unmated female adults from unisexual and bisexual populations respectively. The hatch success of unfertilized eggs for three geographically distinct bisexual populations was in versely correlated with the proportion of males in the populations. The genetic structure of bisexual and unisexual populations was very similar. Unisexual populations consists of clones, with as few as four recognizable phenotypes being present at a given location. All offspring had the same phenotype as the mother. Tychoparthenogenesis is suggested as the most reasonable working hypothesis concerning the origin of unisexual populations in E. funeralis .     

Reproductive mode of the geographic parthenogenetic mayfly Ephoron shigae, with findings from some new localities (Insecta: Ephemeroptera, Polymitarcyidae)

The burrowing polymitarcyid mayfly Ephoron shigae is distributed widely in Japan. Some populations are bisexual, others are unisexual, and the distributions of the two types overlap broadly. Experimental evidence of parthenogenetic reproduction, long suspected in unisexual populations, is presented here, based on a comparative analysis of the developmental rate of fertilized and unfertilized eggs. The developmental rate of fertilized eggs from 20 mated females in a bisexual population was 98.4% ± 0.73% (mean ± SD), and no unfertilized eggs from 20 virgin females in that population developed. The developmental rates of unfertilized eggs in two unisexual populations were 89.0% ± 4.59% and 84.2% ± 1.96%, respectively. This article presents experimental evidence of geographic parthenogenesis in E. shigae and provides support for the previous interpretation. In addition, we discuss the relationship between the sex ratio of each population and the developmental rate of fertilized versus unfertilized eggs from the females in those populations.     

白背叶(大戟科)性系统和传粉生物学研究

为探讨野桐属(Mallotus)雌雄异株的进化和传粉机制,对白背叶(Mallotus apelta)野生居群的性系统和传粉生物学进行了研究。结果表明,所调查的白背叶居群均由雌性(F)、雄性(M)和少数两性(B)个体组成,平均性比为1：0.66：0.18(F：M：B);3种性别植株的基径大小差异不显著;雌株与两性植株的单花胚珠数、单果结籽数和自然结实率无显著差异;雄株与两性植株的花粉萌发率、花粉组织化学和花粉微形态特征也无显著差异,但雄株的单花花粉量是两性植株的1.26~1.63倍,且差异显著;雌株的异交结实率为96.67%,两性植株的异交结实率为76.00%,两者差异显著,说明居群内雌株的潜在种子生产力明显高于两性植株;野外观察到雄株和两性植株上的雄花具有访花者而雌株没有;雌株经套网处理后结实率超过30%而套袋处理不结实。这些表明白背叶具典型的亚雌雄异株性系统,雌株和雄株的适合度均高于两性植株;雌株以风媒传粉结实,两性植株可能兼有风媒和虫媒传粉特征。     

Population genetics of bisexual and unisexual populations of the scaly-winged bark louse Echmepteryx hageni (Insecta: Psocoptera)

The scaly-winged bark louse, Echmepteryx hageni, exhibits a unique pattern of co-existence of apparently differnt reproductive modes. Unisexuality is widespread in eastern North America, while sexual populations are restricted to isolated rock out-croppings in southern Illinois and eastern Kentucky. Three of the four nuclear loci examined show greater genetic diversity in the unisexual form compared to the sexual form of E. hageni, in accordance with the pattern previously shown in mitochondrial genetic data. Neutrality tests of the nuclear loci indicate a consistent signal of demographic expansion in asexual populations, but not in sexual populations. There was evidence of inbreeding in the isolated sexual populations at three of the nuclear loci, and one locus had signs of gene specific balancing selection. However, there is no significant genetic differentiation between bisexual and unisexual populations, possibly due to the greater effective population size of nuclear loci relative to mitochondrial loci. The mitochondrial differentiation of E. hageni populations in the northwestern part of their range (Minnesota and Wisconsin) was also not reflected in the nuclear data. We present three hypotheses that may explain the disparity in observed nuclear and mitochondrial genetic diversity between the reproductive forms of E. hageni.     

Genetic analysis of post-mating reproductive barriers in hybridizing European Populus species

Molecular genetic analyses of experimental crosses provide important information on the strength and nature of post-mating barriers to gene exchange between divergent populations, which are topics of great interest to evolutionary geneticists and breeders. Although not a trivial task in long-lived organisms such as trees, experimental interspecific recombinants can sometimes be created through controlled crosses involving natural F(1)'s. Here, we used this approach to understand the genetics of post-mating isolation and barriers to introgression in Populus alba and Populus tremula, two ecologically divergent, hybridizing forest trees. We studied 86 interspecific backcross (BC(1)) progeny and >350 individuals from natural populations of these species for up to 98 nuclear genetic markers, including microsatellites, indels and single nucleotide polymorphisms, and inferred the origin of the cytoplasm of the cross with plastid DNA. Genetic analysis of the BC(1) revealed extensive segregation distortions on six chromosomes, and >90% of these (12 out of 13) favored P. tremula donor alleles in the heterospecific genomic background. Since selection was documented during early diploid stages of the progeny, this surprising result was attributed to epistasis, cyto-nuclear coadaptation, heterozygote advantage at nuclear loci experiencing introgression or a combination of these. Our results indicate that gene flow across 'porous' species barriers affects these poplars and aspens beyond neutral, Mendelian expectations and suggests the mechanisms responsible. Contrary to expectations, the Populus sex determination region is not protected from introgression. Understanding the population dynamics of the Populus sex determination region will require tests based on natural interspecific hybrid zones.     

THE EVOLUTIONARY HISTORY OF PARTHENOGENETIC CNEMIDOPHORUS LEMNISCATUS (SAURIA: TEIIDAE). II. MATERNAL ORIGIN AND AGE INFERRED FROM MITOCHONDRIAL DNA ANALYSES

Restriction endonuclease analyses were performed on mitochondrial DNAs (mtDNAs) representing unisexual parthenogenetic (cytotypes A, B, and C) and bisexual (cytotypes D and E) populations of Amazonian lizards presently regarded as Cnemidophorus lemniscatus. The results of mtDNA cleavage map comparisons among these C. lemniscatus indicated that (1) there was no cleavage site variation among the unisexuals, (2) mtDNAs from the bisexual cytotypes D and E differed in sequence from one another by about 13%, and (3) mtDNAs from cytotypes A–C differed from those of cytotype D by about 5% and from those of cytotype E by about 13%. Higher resolution restriction fragment size comparisons confirmed the high degree of similarity among the unisexual mtDNAs, but identified 12 cleavage site variants among the 13 cytotype D mtDNAs examined. Both cladistic and phenetic (UPGMA) analyses of the data indicate that the unisexual and cytotype D mtDNAs form a single clade, suggesting that a female of cytotype D was the maternal progenitor of the unisexuals. The similarity among the unisexual mtDNAs and the variability among those of cytotype D suggest that the three unisexual cytotypes arose recently from a common maternal lineage. The mtDNA variability observed among cytotype D individuals has a strong geographic component, suggesting that the unisexuals arose from one or a few geographically proximal populations. The mtDNA comparisons also support the conclusion, based on allozyme comparisons (Sites et al., 1990, this issue), that cytotypes D and E, although presently allocated to C. lemniscatus, are separate species.     

Sexual lability during an individual's life: the case of the sedge Carex secalina

Various environmental and physiological factors that affect sex expression in plants have been identified. We made the presumption that in perennials, age may be a key factor that significantly diversifies sex expression over consecutive years of an individual's life. To test this hypothesis, we chose the sedge Carex secalina, a plant that reproduces only sexually and exhibits different sex expression patterns. These patterns had been previously observed in natural populations. In a four‐year experiment, the sex of spikes formed on reproductive tillers of 100 individuals originating from three populations was monitored. A significant association between individuals’ age and number of female/male spikes was found for each population. In addition, significant differences between the populations in the ratio of shoots with bisexual spikes to shoots with unisexual spikes were revealed. We also showed that the proportion of shoots with bisexual spikes in the individual populations changed significantly with the age of an individual and that in the successive years of the individual's life, the production level of female and male structures changed. Moreover, an age‐dependent decrease in both the number and length of female and male spikes was observed.     

MATERNAL ANCESTRY OF THE RUTILUS ALBURNOIDES COMPLEX (TELEOSTEI,CYPRINIDAE) AS DETERMINED BY ANALYSIS OF CYTOCHROME b SEQUENCES

Cytochrome b (cyt b) sequences from specimens of the Rutilus alburnoides unisexual complex and five bisexual species were compared to examine hypotheses regarding the origin and maternal ancestry of this complex. Phylogenetic analysis revealed a monophyletic relationship among unisexuals and Leuciscus pyrenaicus, clearly identifying this species as the maternal ancestor. Considerable mtDNA diversity exists among R. alburnoides populations, with many localities exhibiting unique haplotypes. The topology recovered from analysis of cyt b variation among populations suggested that R. alburnoides is polyphyletically derived from their sympatric L. pyrenaicus populations, indicating that unisexual lineages have been generated through multiple hybridization events. Although much less abundant, R. alburnoides is present outside the range of L. pyrenaicus, suggesting that it may have dispersed from the Tejo drainage into the northern basins. In this region, Leuciscus carolitertii is most likely the sexual host for the unisexual complex.     

Gonad development of the sea anemone Anthopleura asiatica in clonal populations

Seasonal fluctuations in relative gonad volume and oocyte size of the sea anemone Anthopleura asiatica were examined in 3 unisexual (male) populations and one bisexual population in the Seto Inland Sea of Japan from December 1982 to December 1985. A distinct annual cycle of gonadal maturation with a peak in the summer was found in all of the populations, although they appeared to be sustained only by asexual reproduction. Spawning occured synchronously between the 2 sexes early in the fall in the bisexual population while it was one to one and a half months later in the unisexual populations.     

Assessment of the role of Wolbachia in mtDNA paraphyly and the evolution of unisexuality in Calligrapha (Coleoptera: Chrysomelidae)

Calligrapha is a New World leaf beetle genus that includes several unisexual species in northeastern North America. Each unisexual species had an independent hybrid origin involving different combinations of bisexual species. However, surprisingly, they all cluster in a single mtDNA clade and with some individuals of their parental species, which are in turn deeply polyphyletic for mtDNA. This pattern is suggestive of a selective sweep which, together with mtDNA taxonomic incongruence and occurrence of unisexuality in Calligrapha, led to hypothesize that Wolbachia might be responsible. I tested this hypothesis studying the correlation between diversity of Wolbachia and well‐established mtDNA lineages in >500 specimens of two bisexual species of Calligrapha and their derived unisexual species. Wolbachia appears highly prevalent (83.4%), and fifteen new supergroup‐A strains of the bacteria are characterized, belonging to three main classes: wCallA, occupying the whole species ranges, and wCallB and wCallC, narrowly parapatric, infecting beetles with highly divergent mtDNAs where they coexist. Most beetles (71.6%) carried double infections of wCallA with another sequence class. Bayesian inference of ancestral character states and association tests between bacterial diversity and the mtDNA genealogy show that each mtDNA lineage of Calligrapha has specific types of infection. Moreover, shifts can be explained by horizontal or vertical transfer from local populations to an expanding lineage and cytoplasmic incompatibility between wCallB and wCallC types, suggesting that the symbionts hitchhike with the host and are not responsible for selective mtDNA sweeps. Lack of evidence for sweeps and the fact that individuals in the unisexual clade are uninfected or infected by the widespread wCallA type indicate that Wolbachia does not induce unisexuality in Calligrapha, although they may manipulate host reproduction through cytoplasmic incompatibility.     

Home ranges of parthenogenetic and bisexual species in a community of Darevskia lizards (Reptilia: Lacertidae)

We analysed the home ranges of a community of Darevskia rock lizards composed of a bisexual species (D. valentini), two parthenogens (D. armeniaca and D. unisexualis), and two backcross forms between bisexual and unisexual forms. We estimated home range areas of ink-marked, GPS-located lizards using Minimum Convex Polygon (MCP) and 95% of the locations for those individuals with five or more sightings. The bisexual D. valentini was the species with the largest home ranges, distances travelled, and the most intersections. No differences between unisexual species and backcrosses were recorded for any comparison. In males, home range size and perimeter were related to morphological characteristics. Contrary to what has been described in allopatry, unisexual species showed smaller home ranges and fewer overlaps than sympatric bisexual species. We tentatively suggest that the presence of potential bisexual partners might increase sexual competition among parthenogenetic females while differences in habitat use should also be considered.     

Flower structure and potential bisexuality in Freycinetia reineckei (Pandanaceae), a species of the Samoa Islands

In Freycinetia reineckei the staminate flower (on the staminate spikes) comprises 3 or 4 (sometimes 2) stamens and a pistillode with 2 (sometimes 4) carpellodes, and the pistillate flower (on the pistillate spikes) is formed of a pistil with 2 (sometimes 4) carpels and of 3 or 4 (sometimes 2) staminodes. This perfect floral homology, also observed in all the other species that were studied with both pistillate and staminate material, strongly suggests that the flower of Freycinetia is basically and potentially bisexual, and may explain the occasional sexual lability and bisexuality of that flower (occurrence of both pistillate and staminate inflorescences, and/or of bisexual inflorescences with bisexual flowers and/or unisexual flowers, on the same individuals) in some species, and also the frequent occurrence of bisexual spikes in this species. These may be partitioned into pistillate, staminate, mixed and sterile zones. In the pistillate zones the flowers have the same aspect and structure as the pistillate flowers. In the staminate zones the flowers generally comprise 3 or 4 (sometimes 2) stamens and a ‘semi-pistil’ some have both stamens and staminodes. The semi-pistils are intermediate between pistils and pistillodes in length, aspect and structure, but always have placentas and ovules. In the mixed zones the flowers are generally formed of a pistil and 3 or 4 (sometimes 2) stamens, and are therefore true hermaphrodite flowers; some have both stamens and staminodes. In the sterile zones the flowers comprise a semi-pistil and 3 or 4 (sometimes 2) staminodes. The staminodes are anatomically very similar to the stamens, especially in the staminate, mixed, and sterile zones, in which they exhibit a wide range of variation in length, aspect and structure. The perfect floral homology as generic character on one hand, and the occasional bisexuality both with and without bisexual flowers and other aspects of sex expression (e.g. occurrence of both pistillate and staminate shoots on the same individuals) in some species on the other hand, seem to indicate that Freycinetia is a basically monoecious, sex changing genus.     

Coexistence of bisexual and unisexual populations of Nysius groenlandicus in the Zackenberg Valley,Northeast Greenland

The seed‐feeding true bug Nysius groenlandicus (Zetterstedt) (Heteroptera: Lygaeidae) has temperature and humidity preferences similar to many desert‐inhabiting insects. Nevertheless, it is widely distributed in Greenland and occurs even in high arctic areas. This seeming paradox implies that the species has developed physiological, ecological, and behavioral mechanisms that enable it to cope with the extreme arctic environment. One of these adaptations is its ability to reproduce both sexually and asexually. Sexual reproduction is most common in coastal populations, whereas asexual reproduction (parthenogenesis) occurs mainly in inland populations. Preliminary data from the Zackenberg Valley in Northeast Greenland indicated that both reproductive strategies occurred within the same area. We therefore decided to focus on this area to find evidence of (1) coexistence of unisexual and bisexual populations, (2) factors that correlate with the distribution of the two reproductive types, and (3) morphological differences between females from sexual and asexual populations. We sampled N. groenlandicus at 51 sites within the Zackenberg area. Males and females were found in almost equal numbers in only four of the samples, and only in samples taken close to the coast line, whereas samples from the inner part of the valley consisted almost entirely of females. Thus, the distribution of uni‐ and bisexual populations at the local scale agreed with the pattern previously found for Greenland as a whole. Using data obtained from two climate stations operated in the area, we showed that average summer temperatures tend to be more favorable for N. groenlandicus in the inner part of the valley than at the coast. The inland populations inhabited small isolated patches, whereas the sexual populations were found in the more homogeneous areas along the coast. Data support the hypothesis that coexistence of the two reproductive types is maintained by a combination of environmental variability, which gives sexual reproduction an advantage, and metapopulation dynamics characterized by frequent extinctions and re‐colonizations, which favors asexual reproduction. Head width of females from unisexual populations was on average 7% larger than that of females from bisexual populations. The mechanism behind this morphological difference needs further investigation.     

Phylogenetic analysis of sexual systems in Inuleae (Asteraceae)

From an ancestor with bisexual flowers, plants with unisexual flowers, or even unisexual individuals have evolved in different lineages of angiosperms. The Asteraceae tribe Inuleae includes hermaphroditic, monoecious, dioecious, and gynomonoecious species. Gynomonoecy, the sexual system in which female and bisexual flowers occur on the same plant, is prevalent in the Asteraceae. We inferred one large gene phylogeny (ndhF) and two supertrees to investigate whether gynomonoecy was a stage in the evolution from hermaphroditism to monoecy. We identified transitions in sexual system evolution using the stochastic character mapping method. From gynomonoecious ancestors, both hermaphroditic and monoecious descendants have evolved. Gynomonoecy was not restricted to a stage in the evolution toward monoecy because the number of transitions and the rate of change from monoecy to gynomonoecy were much higher than the opposite. We also investigated one hypothesized association among female flowers and the development of a petaloid ray as an explanation of gynomonoecy maintenance in Asteraceae. We found that peripheral female flowers and petaloid rays were phylogenetically correlated. However, empirical evidence shows that a causal relationship between these traits is not clear.     

Developmental Events Associated with the Critical Stage for Sex Determination in Wild-Rice Florets

The developmental events of florets and a critical stage for sex determination in two wild-rice populations (Zizania palustris cv. Franklin and Zizania palustris cv. K-2Pi) have been identified. Formation of bisexual florets precedes the development of both male and female florets. Developmental indicators, established by measuring the length of florets and panicles, indicate that the critical stage for sex determination occurs when floret and panicle lengths are 1-2 mm and 3 cm, respectively. The stage of floret development at which sex determination occurs is the same in the two investigated wild-rice populations. Organ suppression in bisexual florets is an essential step for sex determination during the formation of unisexual florets. Histological examination of suppressed stamens or pistils in unisexual florets of wild-rice indicates that cell death does not occur during sex determination. In addition, the length of anthers and pistils in bisexual florets indicates that floral development in the transition zone is normal when compared with the male florets in the male spikelets and female florets in the female spikelets.