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SUMMARY Using marker genes the breeding system (mating type gene) and the structure (hairy stalk gene) of a zinc–lead mine population of Armeria maritima, an insect-pollinated plant, was studied in situ. Strict allogamy occurs in the population in nature although this population shows self-fertility in experimental garden plots. The population is divided into sub-populations differing in the frequency of hairy stalked individuals. Gene flow between these sub-populations is very low (if any) so that the differences, which are likely to have originated by chance, remain constant through generations.

The biological analysis of several populations confirms the existence in the Iberian Peninsula of two species of Muscari subgenus Leopoldia : M. comosum and M. matritensis (the latter described as new). Karyologically, they differ in at least a translocation rearrangement, in the presence of heterochromatin, which is lacking in M. matritensis , and in some chromosomal characters. At the genic level, the distance between M. comosum and M. matritensis is high (0.378). Morphologically, they show some differences in floral structure which are correlated with different reproductive systems, allogamy in M. comosum and autogamy in M. matritensis . The possible evolutionary relationships between these taxa is discussed.

The breeding system and determinants of fruit and seed production in a population of 114 patches of Mayapple (Podophyllum peltatum L.) were examined. Experimental crosses indicated that Mayapple patches are self-incompatible (clones) and that fruit and seed set were pollinator limited. Mayapple flowers are nectarless yet depend primarily on infrequent visits by nectar-searching bumblebees for pollination. The proportion of flowers setting fruit and ovules setting seed in Mayapple clones was inversely associated with the distance to neighboring clones and the distance to Pedicularis canadensis L. plants. Clones within 45 m of P. canadensis plants (which are heavily visited by bumblebees) showed significant increases in fruit and seed production compared with a similar group of more distant clones. This effect is interpreted as evidence for a facilitative interaction between Mayapple and P. canadensis.

Capsella bursa-pastoris (L.)Med. is a partially self-pollinating, autogamous plant. The selfing-rate depends on ecological factors. High atmospheric humidity at temperatures over 15 °C and low light intensity, i.e. cloudy and rainy weather, lead to almost exclusive self-pollination, while dry and sunny weather favours outcrossing. At low temperatures (about 4–10 °C) anthesis is prolongated up to five-fold, but allogamy is reduced. Day-length distinctly influences the beginning of flowering.Capsella bursa-pastoris is not a day-neutral plant (as was supposed up to now) but behaves as a quantitative long-day plant.

La culture in vitro des antheres de 4 clones, parents potentiels d’hybrides de chou a choucroute (3 en S4, 1 en S7) a permis d’obtenir des plantes androgenetiques de differents niveaux de ploidie (n, 2n, 3n et mixoploides) chez 2 d’entre eux. Apres mesure des cellules de garde des stomates, seules les plantes haploides ont ete traitees a la colchicine pendant la vernalisation. Les plantes haploides doublees (HD) et les plantes diploides spontanees ont ete observees pour la qualite de leur pollen et leur aptitude grainiere. Les lignees HD ayant produit suffisamment de graines ont ete semees au champ et comparees a des lignees pures « SG » (en S10) obtenues par autofecondations successives en selection genealogique. De meme, des hybrides F1 issus du croisement entre une lignee HD et une lignee SG, ont ete places au champ et compares a des hybrides F1 provenant du croisement entre 2 lignees SG. Les observations effectuees montrent l’homogeneite intralignee, la vigueur de toutes les lignees HD et la stabilite d’une generation a l’autre (HD1-HD2). Chez les lignees HD issues du clone en 4S on remarque une importante variabilite interlignees tandis que les lignees HD issues du clone en S7 sont equivalentes aux lignees SG. Plusieurs methodes visant a ameliorer les differentes etapes de la production des lignees HD et simplifier leur incorporation dans un programme de selection sont proposees. L’haplodiploidisation par androgenese in vitrro apparait donc ici comme un outil interessant pour le selectionneur a condition de concevoir une strategie raisonnee d’utilisation optimale.

SUMMARYField assessments of varietal contamination from entomophilous outcrossing in okra revealed that the plant characters employed in such assessments influenced the estimate of contamination expressed as percentage of offtypes. In Nigeria, complex cropping systems, land use patterns and the abundance of insects associated with okra flowers make the effective isolation of seed crops difficult. Also, the largely subsistence production where annual seed purchase is infrequent, and consumers' acceptance of variable and ungraded edible okra fruits, imply that breeding for uniform or pure varieties may not be appropriate. Consequently, a composite bulk variety is proposed for growing or seed multiplication in areas where edible fruit production is envisaged. In this way, the difficulty of pure seed production or unwanted adulteration of varieties will not pose problems to breeders or farmers.

Factors affecting reproductive strategies of pearl millet, which is currently classified as a predominantly allogamous species, were investigated. Gametophytic competition as well as the effect of growth temperature on this phenomenon were studied by means of the pollen mixture technique. The relative competitive ability of pollen from five different genetic stocks (Ligui, Massue, "Chinese," Thiotandé, 23d2B) was assessed by isozyme electrophoresis (esterase, alcohol dehydrogenase) of progeny plants. Gametophytic competition with a polygenic inheritance trend for pollen competitive ability is reported. A better competitive ability of autopollen on various types of allopollen was systematically found for the Ligui genotype. Temperature stress enhanced this trend. Hypotheses on the role of gametophytic competition in the evolution of the primary genetic pool of P. typhoides are discussed.Key words: pearl millet, pollen, competitive ability, segregation distortions.

Summary 282 wild races of Hordeum L. subgen. Hordeum have been studied concerning pollination ecology. Anther length is a good character for demonstrating the breeding system. Races of Hordeum spontaneum from primary habitats have relatively long anthers (> 4 mm). They are postulated as initial forms for the evolution of cultivated and weedy barleys. Domestication and transition from primary habitats to ruderal and field areas are processes which decrease the tendency to allogamy. Therefore, the anthers of cultivated and weedy barleys are relatively short ( 4 mm) may not be derived from introgressions of cultivated into wild barleys; those races are discussed as initial forms for the evolution of cultivated barleys. In this connection a diphyletic origin of cultivated barley is discussed.

In this study, we have analysed meiotic pairing in wheat-rye intergeneric hybrids obtained by crossing T. aestivum cv. Chinese Spring with two cultivars of S. cereale (Elbon and Ailes, respectively) and S. vavilovii. The results have shown that meiotic behaviour of hybrids is different in relation to the type of rye utilised. This has been interpreted as being due to the different effect of each particular rye genotype on the homoeologous pairing in relation with the reproductive systems (allogamy or autogamy) of the particular rye.

It was found that climatological environmental influences play an important role in the natural selection of the colour-varieties ofEpipactis helleborine (L)Cr., Wats. & Coult. on the island of Ameland (Netherlands.) Data were obtained from counts in open field of the frequency of the genetical colour varieties. Transplantation-investigations were made, which indicate that the white variety is more resistent to the environmental influences than the red-violet ones. Data were obtained concerning occurrence of self-pollination or allogamy ofEpipactis helleborine. A new variety var.alba Wr. was described. Some conclusions were drawn concerning the systematics ofEpipactis helleborine. Some cytological data were obtained in regard to the chromosomal composition. As basic chromosome number n=10 was found. The spreading-norm of the acidity in which the mycorrhiza can occur was investigated.

Summary The distribution of pollen upon the insect-visitors to three species of Viola is described and correlated with their feeding and cleaning behaviour. Visitors adopt one of two basic positions while feeding. In the prone position the insect alights on the anterior petal and probes for nectar so that its dorsal surfaces contact the floral genitalia. The supine position may be adopted after alighting on the anterior petal when the insect rotates so that it is virtually standing on its head. While probing for nectar from this position it is the ventral surfaces which contact the floral genitalia. Bumblebees adopt either feeding position; many large solitary bee species almost invariably adopt the supine one while large hoverflies always feed from the prone position. The behaviour of short-tongued visitors tends to be highly individual with respect to contact with the floral genitalia and many body surfaces may be involved. The varying activities of insect-visitors while feeding result in the deposition of pollen at different locations on the integument. Consequently insect-borne pollen is presented to the stigma in various ways and there is a spectrum of pollination effects: medium and long-tongued nectar-seeking insects tend to be systematic cross-pollinators while short-tongued or pollengathering species tend to be chance cross- or self-pollinators. The cleaning behaviour of insect-visitors strongly influences pollination as it removes much integumental pollen. Two requirements of the pollen deposition mechanism are postulated: that pollen should be placed (a) in a position not occupied by foreign pollen and (b) in a position irregularly or inefficiently cleaned. There were no positions which were free of foreign pollen throughout the visitor-species. On the other hand, violet pollen was found to be concentrated at locations inaccessible to the cleaning mechanism. Systematic cross-pollination results from the visits of a variety of insects with proboscides over 5 mm long including bumblebees, honeybees, solitary bees, hoverflies and beeflies, therefore, the violet flower is not simply a ‘bee flower’ as previously supposed. The widespread practice of generalizing on the role of insect-visitors in pollination is questioned and the error in labelling flowers according to the taxonomic position of their pollinators is pointed out; the greater relevance of the morphological and behavioural characteristics of the insect-visitors is emphasized. Differences in the floral genitalia of these Viola spp. may reflect a shift from allogamy to facultative autogamy which, in turn, may be a response to a paucity of pollinators at certain seasons. However, the diverse range of pollinators may maintain some out-crossing by the least efficient but more abundant short-tongued pollinators. The diversity of pollinators, therefore, provides a mechanism whereby a sexual system can simultaneously produce variation and invariance. The evolutionary versatility of a mating system incorporating this mechanism may have been partially responsible for the success of the genus Viola throughout the temperate regions of the world.

If the flowers for experiment were separated from the plants one day before pollination and incubated in water at a temperature of 25° C, pollen tube growth in the pistils made itself apparent during the following three days in the glucose and fructose level. On the first day after pollination the amount of these sugars in the apical style parts was higher in non-pollinated flowers, while on the other hand, in most cases it was lower in the basal sections and ovaries than in the corresponding parts of pollinated flowers. During the next two days there was a greater loss of both carbohydrates where pollination, particularly allogamy, occurred, so that after the third day the glucose and fructose level was highest in the non-pollinated pistils and lowest after compatible pollination. This decrease was most pronounced in the ovaries even though the compatible tubes had not yet penetrated into them. In experiments in which the flowers were left on plants cultivated under field conditions, a decrease in the glucose and fructose content of their pistils had not occurred even 80 hours after compatible pollination.

The prevalence of self-incompatibility inOryza barthii Cheval. and its implications on the origin of riceO. sativa L. and some other related taxa are discussed. It is suggested that evolution has been fromO. barthii toO. perennis toO. sativa with corresponding changes in breeding system from allogamy to facultative autogamy to obligate autogamy. The significance of the breeding system for speciation and evolutionary potentialities of these three taxa is pointed out. The presence inO. barthii of the most primitive characters of the genus and its widespread presence in tropical Africa (where nine out of 23 species of the genus occur) have been interpreted as suggesting that this region might have been the centre of origin of the genus.

This paper is concerned with insect visitors to some Canadian weeds. It shows that both self-pollinating (autogamous) and cross-pollinating (allogamous) weeds are visited during the flowering period. It was found that self-incompatible species were visited by insects frequently, whereas self-compatible weeds were not visited or were rarely visited. The self-compatible group showed some difference, in that autogamous annual and winter annual weeds were visited less than were autogamous biennial and short-lived perennial weeds. Most of the insect visitors, to both the autogamous and allogamous species of weeds, were native species, whereas the weeds themselves were mostly introduced species. The insects, also, evidently visited more than a single species of plant over a short period of time. The implications of the insect visits to the genetic structure of the plants and their colonizing abilities are then briefly discussed.

Neighborhood size and area, and equations for their calculation, have been treated in relation to reproduction under diverse reproductive methods. With allogamy via homomorphic incompatibility as the standard system, consideration has been given to the effect of autogamy, allogamy via heteromorphic incompatibility and dioecy, and apomixis upon the neighborhood parameters of colonies. It has been shown that neighborhood size contracts under autogamy, as it does under dioecy or heteromorphic incompatibility if the sex or morph ratios are disproportionate. Neighborhood size may expand under heteromorphic incompatibility or dioecy through enhanced pollen carry-over if the sex ratio is 1:1 and if the plants are insect-pollinated. Because of the formation of clones which are incompatible inter se, it also expands if apomixis is an adjunct to allogamy. As an expansion of neighborhood size may be equated with enhanced outbreeding and a contraction with reduced outbreeding, it is evident that heteromorphic incompa...

Alcantarea nahoumii occurs exclusively in the state of Bahia, Brazil, and is classified as vulnerable due to deforestation and frequent fires in the region. Knowledge of floral and reproductive biology is fundamental to understanding ecological interactions, as well as the reproductive success of plant species. The objective of this study was to evaluate the floral and reproductive biology of A. nahoumii in an Atlantic Forest fragment with regard to phenology, pollen viability, stigma receptivity, pollination ecology and reproductive systems, all of which are important parameters for of the development of conservation strategies for the species. Anthesis is diurnal and heterogeneous, starting at 6:30 a.m. and lasting until 8:00 a.m. Highest germination percentages and greatest pollen tube lengths were obtained in BK culture medium. Histochemical tests revealed high pollen viability (89.71 %). Stigma receptivity occurred during anthesis and lasted for up to 24 hours after floral opening. Alcantarea nahoumii exhibited preferential allogamy and self-compatibility, and required a pollinator to production of viable seeds. Sixteen species of pollinators were observed visiting A. nahoumii, among which were five hummingbird species. Even though its reproductive system is efficient, this bromeliad remains threatened mainly due to habitat fragmentation caused by deforestation, burning and predatory extractivism.

Summary A chloroplast triazine resistant population of Poa annua from a triazine treated area was compared with one from an adjacent untreated area. A study of morphological characters and isoenzymes showed that the resistant population contained as much polymorphism as the susceptible one. One phenotype, on an isozyme basis, was much more frequent in each habitat, suggesting the importance of natural selection in each population. The possibility of a ‘founder effect’ within the resistant population is discussed. A dominant esterase allozyme was used to estimate the outcrossing rate giving an estimate of 13 % under greenhouse conditions. Transmission of herbicide resistance was also tested and found to be mainly inherited maternally (0·1% transmission via pollen). Paternal transmission is therefore not important for gene flow. Allogamy would appear responsible for the high degree of polymorphism found in the resistant population.

Faba beans are widely believed to have originated in the Mediterranean-West Asia Region, probably in the late Neolithic period (16)(9). Throughout their long history as a cultivated crop, faba beans have been subjected to both natural selection and selection by farmers in the different environments in which the crop has been grown. This has resulted in the wide range of genetic variation in the species today. In spite of centuries of such selection, Vicia faba retains vestiges of its wild past and, in certain respects, can be regarded as an incompletely domesticated species. The indeterminate nature of the growth habit and the existence of dehiscent pods in many populations (31) can be cited as examples. The breeding system of the species, which stands between full autogamy and full allogamy, may be another.

The floral biology of Chaenorrhinum minus (L.) Lange (Scrophulariaceae) was studied at two sites in central New York State. Individual flowers are short-lived (approximately 24 hr). Small plants generally produce flowers intermittently. More vigorous individuals produce many flower-bearing branches, which increases the probability that they will have at least one flower open when a pollinator visits the patch. Chaenorrhinum minus is self-compatible, though it has adaptations for insect pollination. The only insect pollinators observed during 2 seasons were halictid bees. These visited infrequently. Accordingly, most of the flowers in the population of C. minus were selffertilized. INTRODUCTION The genus Chaenorrhinum consists of 10 herbaceous species, five perennials and five annuals (Tutin et al., 1972). Most of these species have a localized distribution in southern Europe. Only one of them, C. minus, has spread widely, throughout most of Europe and much of eastern and central North America. This paper describes the floral characteristics and phenology of Chaenorrhinum minus in central New York State. Observations on the relative frequency of autogamy and insect-mediated allogamy are also reported. The plant is an introduced annual, which is locally abundant as a pioneer on well-drained, gravelly soils, especially on the cinder ballast of railroad tracks. It was first recorded in the United States at Camden, New Jersey, in 1874 (Deam, 1940). The population dynamics and seed dispersal mechanisms of this species have been previously described (Arnold, 1981). MATERIALS AND METHODS Field studies were carried out on populations of Chaenorrhinum minus growing on railroad cinders near the village of Poolville, Madison Co., New York, in 1979, and at a patch of waste ground ("weedlot") near the village of Hamilton, Madison Co., N.Y., in 1979 and 1980. These sites have been previously described (Arnold, 1981). Floral characteristics. -The lifespan of flowers was estimated by observing buds, uniquely marked with enamel paint, from opening to wilting. Observations were made at 3-hr intervals throughout the lifespan of each of the 15 flowers observed. The temporal relationship between anthesis and stigma receptivity was investigated by testing for the presence of peroxidase enzymes at the stigmatic surface in flowers at different stages of anthesis. Zeisler (1938) showed that the appearance of peroxidases in stigmatic tissue is correlated, in many plants, with the onset of stigma receptivity. To perform the test, excised stigma-style complexes were immersed in a 3 % solution of hydrogen peroxide. Formation of oxygen bubbles was used as an indicator of stigma receptivity. Pollen tube germination at stigmatic surfaces was studied in excised stigma-style complexes that were cut open longitudinally and stained with acetocarmine and basic fuchsin (Chandler, 1931). Phenology. Blooming times of Chaenorrhinum minus at the weedlot during 1980 were determined by weekly counts of the number of open flowers in five 1-M2 quadrats. A daily expected number of flowers per plant as a function of the number of flowerbearing branches was estimated by randomly sampling 60 plants each day for 14 days at the peak of the blooming season (July 1-July 13). Also spelled Chaenorhinum by some European authorities.

Chromosome levels in the Bothriochloa saccharoides complex are hexaploid (2n = 60) and duodecaploid (2n = 120); pollen size correlates with chromosome number. These grasses re- produce sexually, via allogamy or autogamy, and have relatively high seed set (73-93%). Principal components analysis of morphological traits reveals three major clusters corresponding to the species, B. saccharoides, B. laguroides, and B. exaristata. A fourth species, B. longipaniculata, is segregated from the B. laguroides phenetic cluster. Proposed new combinations are B. saccharoides subsp. reevesii, B. laguroides subsp. torreyana, and B. longipaniculata. Bothriochloa imperatoides and An- dropogon saccharoides subsp. parvispiculus are excluded from the complex. Keys, descriptions, and distribution maps are provided. saccharoides var. pulvinata (Gould) Gould, and B. saccharoides var. torreyana (Steudel) Gould. The subvariety paucirameus was not originally in- cluded as part of this study, because it is some- what atypical morphologically when compared to the other members of the complex. The re- lationship was perceived after most of the in- vestigation was completed. Hence, data for this taxon were missing for certain portions of the study. Historically, taxa belonging to this alliance have been grouped in one to three genera. Most

Background Variations in floral display represent one of the core features associated with the transition from allogamy to autogamy in angiosperms. The promotion of autogamy under stress conditions suggests the potential involvement of a signaling pathway with a dual role in both flower development and stress response. The jasmonic acid (JA) pathway is a plausible candidate to play such a role because of its involvement in many plant responses to environmental and developmental cues. In the present study, we used peach (Prunus persica L.) varieties with showy and non-showy flowers to investigate the role of JA (and JA signaling suppressors) in floral display. Results Our results show that PpJAZ1, a component of the JA signaling pathway in peach, regulates petal expansion during anthesis and promotes self-pollination. PpJAZ1 transcript levels were higher in petals of the non-showy flowers than those of showy flowers at anthesis. Moreover, the ectopic expression of PpJAZ1 in tobacco (Nicotiana tabacum L.) converted the showy, chasmogamous tobacco flowers into non-showy, cleistogamous flowers. Stability of PpJAZ1 was confirmed in vivo using PpJAZ1-GFP chimeric protein. PpJAZ1 inhibited JA-dependent processes in roots and leaves of transgenic plants, including induction of JA-response genes to mechanical wounding. However, the inhibitory effect of PpJAZ1 on JA-dependent fertility functions was weaker, indicating that PpJAZ1 regulates the spatial localization of JA signaling in different plant organs. Indeed, JA-related genes showed differential expression patterns in leaves and flowers of transgenic plants. Conclusions Our results reveal that under stress conditions – for example, herbivore attacks -- stable JAZ proteins such as PpJAZ1 may alter JA signaling in different plant organs, resulting in autogamy as a reproductive assurance mechanism. This represents an additional mechanism by which plant hormone signaling can modulate a vital developmental process in response to stress. Electronic supplementary material The online version of this article (doi:10.1186/s12915-015-0124-6) contains supplementary material, which is available to authorized users.