Patterns of fruit and seed set within inflorescences of Pancratium maritimum (Amaryllidaceae): nonuniform pollination,resource limitation,or architectural effects?

We investigated patterns of fruit and seed production on inflorescences of a population of Pancratium maritimum in northwest Spain over a 2-yr period. Initial findings showed that the earliest opening flowers on an inflorescence are more likely to set fruit and produce more seeds than later opening flowers and that this pattern is maintained throughout the flowering season. Supplementary pollination and flower-removal experiments were performed to investigate whether the observed pattern is attributable (a) to variation in pollen receipt, (b) to sequestration of resources by the earliest flowers on an inflorescence, and/or (c) to "architectural" limitations on the fruit/seed production of later flowers. Supplementary pollination did not improve fruit or seed production by late flowers in either of the 2 yr of study. In flower-removal experiments, the remaining flowers showed improved fruit set and mean number of seeds per flower, by comparison with flowers in the same position on control inflorescences. When all flowers except the latest third were removed, these showed fruit set and seed production similar to those of early flowers on control inflorescences. These results strongly suggest that the observed within-inflorescence patterns of fruit and seed production in P. maritimum are mainly attributable to competition for resources (i.e., explanation b), though other adaptive explanations cannot be ruled out.     

The effect of flower position on male and female reproductive success in a deceptively pollinated tropical orchid

In many plants, including orchids, differential fruit set along the inflorescence has been attributed to pollinator behaviour. For instance, the pollinator, moving up the inflorescence, becomes satiated with the resources and leaves before visiting the upper flowers. Consequently, the pollinators do not visit flowers as frequently higher up the inflorescence. Alternatively, flower size may vary along the inflorescence, making pollination ineffective as flowers decrease in size. I tested for the presence of differential pollination along the inflorescence in a pollinator-limited tropical epiphyte, Lepanthes rupestris Stimson, and determined the likely cause of the observed pattern. As this species has inflorescences with sequential flowering, pollinator behaviour, moving up the inflorescence as in synchronous multiflowering inflorescences, can be discounted as an explanation for differential fruit set. Fruit set is shown to be more frequent at the base of the inflorescence, but male reproductive success through pollinarium removal is basically independent of flower position. Moreover, cross-pollination by hand at variable flower positions along the inflorescence results in equal fruit set, suggesting that resources are not limiting and cannot explain the cause of differential fruit production along the inflorescence in natural populations. Furthermore, flower size is shown to diminish along the inflorescence, suggesting that the pollinator(s) may be ineffective at depositing the pollinarium in the smaller higher flowers. Consequently, pollinator behaviour and its interaction with flower size, and not resource limitation, is likely to be the main cause of differential fruit set along the inflorescence in L. rupestris .  © 2006 The Linnean Society of London, Botanical Journal of the Linnean Society , 2006, 151 , 405–410.     

A ballistic pollen dispersal system influences pollination success and fruit‐set pattern in pollinator‐excluded environments for the endangered species Synaphea stenoloba (Proteaceae)

The critically endangered Synaphea stenoloba (Proteaceae) has numerous scentless flowers clustered in dense inflorescences and deploys a ballistic pollen ejection mechanism to release pollen. We examined the hypothesis that active pollen ejection and flowering patterns within an inflorescence influence the reproductive success (i.e. fruit formation) of individual flowers within or among inflorescences of S. stenoloba in a pollinator‐excluded environment. Our results showed that: (1) no pollen grains were observed deposited on the stigma of their own flower after the pollen ejection system was manually activated, indicating self‐pollination within an individual flower is improbable in S. stenoloba; (2) fruit set in the indoor open pollination treatment and the inflorescence‐closed pollination treatment indicated that S. stenoloba is self‐compatible and pollen ejection can potentially result in inter‐floral pollination success; (3) fruit set in the inflorescence‐closed pollination treatment was significantly lower than that of indoor open pollination, indicating within‐ and between‐flower pollination events in an inflorescence are most likely limited, with pollination between inflorescences providing the highest reproductive opportunity; and (4) analysis of the spatial distribution of cumulative fruit set on inflorescences showed that pollen could reach any flower within an inflorescence and there was no functional limitation on seed set among flowers located at various positions within the inflorescence. These data suggest that the pollen ejection mechanism in S. stenoloba can enhance inter‐plant pollination in pollinator‐excluded environments and may suggest adaptation to pollinator scarcity attributable to habitat disturbance or competition for pollinators in a diverse flora. © 2012 The Linnean Society of London, Botanical Journal of the Linnean Society, 2012, 170 , 59–68.     

WITHIN- AND AMONG-TREE VARIATION IN FLOWER AND FRUIT PRODUCTION IN TWO SPECIES OF CARYA (JUGLANDACEAE)

The patterns of variability in the production of staminate inflorescences, pistillate flowers, and fruits for Carya ovata (Mill.) K. Koch and C. tomentosa (Poir.) Nutt. at Hutcheson Memorial Forest (Somerset County, New Jersey) were examined over a four-year period. We sought to determine 1) the patterns of variability in flowering and fruiting (within-trees, among-trees, and between-years), 2) if variable flowering might account for observed nut-bearing patterns, and 3) what were the relative contributions of intrinsic (genetic) and/or extrinsic (environmental) factors in determining flower production and fruit set. In general, our fine-scale analysis of shoots within canopies did not reveal a distinct mast fruiting pattern. While the number of male and female flowers varied significantly (among trees and between years), fruit set was not markedly affected. Variability of flowering and fruiting among shoots within trees was low. Both flowering and fruiting were observed to have a strong genetic and/or microenvironmental basis; however, flowering appeared more plastic and thus more sensitive to yearly environmental vagaries than did fruiting. Favorable environmental conditions at the time of flower differentiation may result in increased flower production; but, this does not necessarily result in increased fruit set. Many pistillate flowers abscise around the time of pollination and fertilization, apparently adjusting fruit set to available shoot resources. Approximately 50% of the pistillate flowers of both species fail to set fruit. Overall, individual trees exhibit their own flowering and fruiting schedules, suggesting the need to account for this level of variability in future studies of mast fruiting.     

Variation in fruit- and seed set among and within inflorescences of Melampyrum roseum var. japonicum (Scrophulariaceae)

Abstract Variations in fruit set and seed set among and within inflorescences of the annual herb, Melampyrum roseum var. japonicum, were studied. Under natural conditions, although the mean fruit set was slightly different among inflorescences, the mean seedset was not significantly different among inflorescences within the plants. In constrast, within the inflorescences, the flowers located at a lower position of the inflorescence and which opened earlier showed higher fruit set than those at a higher position and which opened later. However, the seed set of matured capsules were not significantly different from each other, regardless of the position of flowers within the inflorescences. Patterns of the fruit- and seed set under open pollination indicated that variation in seed reproduction of M. roseum is due to variation in fruit production. The results of clipping experiments of flowers revealed that there was no functional limitation in seed production among flowers located at various positions within the inflorescence. It seemed that the variation in the fruit set within the inflorescences of M. roseum was not attributable to 'architectural effects'. Reduction of the number of flowers within the inflorescences resulted in an increase of fruit set and seed weight, indicating that the flowers in an inflorescence compete for resources. This phenomenon supports the 'resource competition hypothesis', and variation in fruit set within the inflorescence is attributable to competition among flowers within the inflorescence for limited resources. Consequently, it was concluded that, under natural conditions, the early blooming flowers located at lower positions of the inflorescences obtain more resources and produce more fruits than the late blooming flowers located at higher positions in M. roseum .     

A Top-Down Hierarchy in Fruit Set on Inflorescences in Iris fulva (Iridaceae)

Abstract: In Iris fulva, the apical flower on an inflorescence opens first, and the flowering sequence then proceeds from the most basal flower upward to the apex (acropetally). Flowering order and flower position are thus partially decoupled, and this provides an opportunity to separately investigate the effects of these two factors upon fruit formation. We recorded natural patterns of fruit set and seed production, and found that fruit set patterns were determined by what appears to be a form of apical dominance. The first, apical flower had the highest fruit set and seed production. Fruit set decreased towards the base of the inflorescence, with later-opening flowers having a higher fruit set. This is contrary to the pattern usually observed in other acropetally flowering plants, which is a higher fruit set for basal, early flowers. By performing additional hand pollinations and counting pollen grains on naturally pollinated flowers, we found that pollen deposition was not a major factor limiting fruit set, and that it could not explain the large difference in fruit set between the apical and basal flowers. Removing the first flower after it had wilted increased fruit set in the remaining flowers, but mainly in the more apical flowers. Only by removing the two topmost flowers could we obtain an increase in fruit set for the basal flower. The fact that the basal flower rarely sets fruit, despite being closer to resources, suggests that the apical meristem is either a strong sink for resources or produces hormones that form a gradient along the inflorescence, which is comparable with apical dominance.     

Morphology and Anatomy of Stems and Pedicels of Spring Flush Shoots Associated with Citrus Fruit Set

Flowering and vegetative shoots of ‘Shamouti’ orange[Citrus sinensis (L.) Osbeck] and ‘Marsh’ seedlessgrapefruit (Citrus paradisi Macf.) were examined for correlationof their morphology and anatomy with fruit set. Fruit set isfavoured on leafy inflorescences whereas abortion is nearlycomplete on leafless inflorescences. Leafless inflorescencesof ‘Shamouti’ with one flower were found to havea very thin stem which contained few vascular bundles, whereasthose with three flowers had better-developed vascular systems.The vascular system of leafy inflorescences is significantlydifferent from that of leafless ones and contains a distinctcentral xylem cylinder. The vascular area of leafless inflorescencesis only about one-quarter of that of the leafy ones. The vascularsystem of grapefruit resembles that of the ‘Shamouti’orange. This study emphasizes the importance of the dimensionof the vascular system for fruit set and provides a possibleexplanation for the better fruit set on both leafy and leaflessinflorescences with several flowers compared with single-floweredinflorescences. Anatomy; citrus; fruit set; leafless inflorescence; leafy inflorescence; pedicel; vascular system; vegetative shoot     

REPRODUCTIVE SUCCESS AND INFLORESCENCE SIZE OF CALOPOGON TUBEROSUS (ORCHIDACEAE)

Reproductive success of Calopogon tuberosus, which produces no nectar, was investigated in relation to inflorescence size and dispersion pattern. Mean inflorescence size was 2.56 (range 1–10). A bagging experiment showed that insects are required for pollen transfer and that fruits are produced from self-, geitonogamous, and cross-pollinations; fruit set was not 100%. Fruit set of nonmanipulated plants was limited by the number of pollinator visits. Reproductive success increased with increasing inflorescence size, although not above theoretical predictions. However, the probability of producing no fruit or contributing no pollinia decreased with increasing inflorescence size since sequential flowering increased the probability of a pollinator visit to the inflorescence over the blooming period. Large inflorescences did not provide a greater pollinator attraction than small ones, because inflorescences only presented a few open flowers at a time. In addition, flowers on plants growing in clumps of 2–8 plants had a higher probability of setting fruit, apparently because of increased pollinator attraction. Although there are obvious selective advantages for large inflorescences, the sequential flowering habit, and low resource availability may reduce the advantages of large inflorescence size at our study site.     

Fruit set in Styrax obassia (Styracaceae): the effect of light availability, display size, and local floral density

Maternal reproductive success was examined in Styrax obassia (Styracaceae), a bumble-bee pollinated mass-flowering tree in a cool-temperate deciduous forest in northern Japan. The effects of flower number on the success of individual flowers at three levels (inflorescence, individual, and population) were considered. During 1995 and 1996, variations in size, light availability to branches, floral display size, and fruit set were monitored in 37 out of 211 individual S. obassia trees in a 4-ha forest plot. In addition, the locations of the 211 trees in this plot were mapped and the number of inflorescences in each tree was counted. A multiple regression analysis showed that flower number per inflorescence and inflorescence number per individual had negative effects on fruit set, and inflorescence number of aggregated clumps of flowering trees, tree size, and light resource had positive effects on fruit set although significant level were marginal. It is concluded that pollinator attraction may occur not at the individual tree level, but at the level of a clump of flowering trees. It is also suggested that geitonogamy increased with inflorescence number of tree and inflorescence size and that resource limitation was related to the light condition and variation of tree size.     

Floral phenology and compatibility of sawgrass, Cladium jamaicense (Cyperaceae)

Sawgrass, Cladium jamaicense, is the dominant macrophyte in the Florida Everglades. We examined sawgrass flowering phenology and compatibility reactions in ex situ and in situ populations over 2 yr. Sawgrass flowers in May in southern Florida. Flower maturation was relatively synchronous within an inflorescence. Along the entire inflorescence, functionally male flowers emerged initially, followed by stigmas, then anthers of hermaphroditic flowers. Flowers of each sex expanded over 2 d with less than 1 d in between, totaling 6- 7 d for an inflorescence to complete flowering. Hand pollinations showed that sawgrass was self-compatible and not pollen-limited, because open pollinations produced fruit set similar to self- and cross-pollinations. Fruit set was low in autogamy and manipulation treatments. Manipulation treatments were used to study the effect of exposure to airborne pollen during hand pollinations. This treatment thus provides a useful technique for studies on the in situ compatibility of wind-pollinated graminoids. Sawgrass was able to self-fertilize, but the timing of flower maturation on an inflorescence promoted outcrossing. Actual outcrossing rates in sawgrass thus depend on clonal architecture and the timing of floral maturation on other inflorescences within a clone rather than on inflorescences of other genets in a population.     

Seasonal variation in honeyeater foraging behaviour,infloresence abundance and fruit set in Banksia spinulosa (Proteaceae)

Seasonal variation in the foraging behaviour of honeyeaters and the production of fruit were examined in relation to the flowering intensity of Banksia spinulosa over two flowering seasons. The abundance of inflorescences was greater in the mid than in the early and late periods of the flowering season. In the mid period, many plants were blooming and each plant had many flowering inflorescences. Inflorescences received most visits by honeyeaters in the early flowering period; the visitation rate declining as flowering progressed. Eastern spinebills were the most common floral visitors at all times during the season. The number of foraging probes made at inflorescences by eastern spinebills did not differ throughout the season. Foraging movements between inflorescences on the same plant were more frequent in the mid period than in the early and late periods. Long distance movements between plants (more than 10 m apart) were promoted by aggressive interactions between honeyeaters. Inflorescences flowering in the late period were less likely to develop follicles because there were fewer visits by birds and/or because resources had been allocated to inflorescences pollinated earlier in the season. The number of follicles produced per infructescence did not differ between flowering periods. Overall, the number of inflorescences produced per plant, the number of visits received per inflorescence and the proportion of inflorescences that developed follicles were greater in 1987 than in 1988.     

Influence of inflorescence size on sexual expression and female reproductive success in a monoecious species

Sex allocation theory forecasts that larger plant size may modify the balance in fitness gain in both genders, leading to uneven optimal male and female allocation. This reasoning can be applied to flowers and inflorescences, because the increase in flower or inflorescence size can differentially benefit different gender functions, and thus favour preferential allocation to specific floral structures. We investigated how inflorescence size influenced sexual expression and female reproductive success in the monoecious Tussilago farfara, by measuring patterns of biomass, and N and P allocation. Inflorescences of T.?farfara showed broad variation in sex expression and, according to expectations, allocation to different sexual structures showed an allometric pattern. Unexpectedly, two studied populations had a contrasting pattern of sex allocation with an increase in inflorescence size. In a shaded site, larger inflorescences were female-biased and had disproportionately more allocation to attraction structures; while in an open site, larger inflorescences were male-biased. Female reproductive success was higher in larger, showier inflorescences. Surprisingly, male flowers positively influenced female reproductive success. These allometric patterns were not easily interpretable as a result of pollen limitation when na?vely assuming an unequivocal relationship between structure and function for the inflorescence structures. In this and other Asteraceae, where inflorescences are the pollination unit, both male and female flowers can play a role in pollinator attraction.     

Choice of flowers by foraging honey bees (Apis mellifera): possible morphological cues

Abstract.

• 1 Honey bees foraging for nectar on lavender (Lavandula stoechas) chose inflorescences with more of their flowers open. The number of open flowers predicted whether an inflorescence was visited by bees, inspected but rejected, or ignored. Inflorescences chosen arbitrarily by observers had numbers of open flowers intermediate between those of visited and ignored inflorescences.
• 2 Differences in morphological characters between types of inflorescence correlated with nectar volume and sugar weight per flower so that visited inflorescences had a disproportionately greater volume of nectar and weight of sugar per flower and greater variance in nectar volume.
• 3 Although there were significant associations between nectar content and the morphological characters of inflorescences, discriminant function analysis revealed discrimination on the basis of morphology rather than nectar content.
• 4 Visited inflorescences tended to have smaller than average flowers but bees tended to probe the largest flowers on visited inflorescences.
• 5 Choice of flowers within inflorescences is explicable in terms of the relationship between flower size and nectar content.

     

Risk‐averse inflorescence departure in hummingbirds and bumble bees: could plants benefit from variable nectar volumes?

Most hermaphroditic, many-flowered plants should suffer reduced fitness from within-plant selfing (geitonogamy). Large inflorescences are most attractive to pollinators, but also promote many flower visits during a single plant visit, which may increase selfing and decrease pollen export. A plant might avoid the negative consequences of attractiveness through modification of the floral display to promote fewer flower visits, while retaining attractiveness. This report shows that increasing only the variance in nectar volume per flower results in fewer flower visits per inflorescence by wild hummingbirds ( Selasphorus rufus ) and captive bumble bees ( Bombus flavifrons ) foraging on artificial inflorescences. Inflorescences were either constant (all flowers contained the same nectar volume) or variable (half the flowers were empty, the other half contained twice as much nectar as in the constant flowers). Both types of inflorescence were simultaneously available to foragers. Risk-averse foraging behaviour was expressed as a patch departure preference: birds and bees visited fewer flowers on variable inflorescences, and this preference was expressed when resource variability could be determined only by concurrent sampling. When variance treatments were clearly labelled with colour and offered to hummingbirds, the departure effect was maintained; however, when preference was measured by inflorescence choice, birds did not consistently prefer to visit constant inflorescences. The reduced visitation lengths on variable inflorescences by both birds and bees documented in this study imply that variance in nectar production rates within inflorescences may represent an adaptive trait to avoid the costs of geitonogamy.     

A gradual reduction of female structures in the pistillate flowers ofRicinus communis L. (castor-bean) with chlorflurenol (morphactin)

Chlorflurenol (morphactin) EMD 7301 W (60, 120 and 240 mg I^?1) when applied at five to seven leaf and 10–12 leaf stage induced hermaphrodite flowers in the inflorescences ofRicinus communis. The hermaphrodite flowers were mostly apical in position unlike the apical female flower in the control. With an increase in the time gap between sowing and emergence of the inflorescence there was a reduction of the female structures in the hermaphrodite flowers. The last formed inflorescences had an apical male flower in place of a female. The largest number of inflorescences with an apical male or hermaphrodite flower were produced with 60 mg 1^?1 applied at five to seven leaf stage. The hermaphrodite flowers failed to set fruits.     

Evolution of floral display in Eichhornia paniculata (Pontederiaceae): genetic correlations between flower size and number

The evolution of floral display is thought to be constrained by trade‐offs between the size and number of flowers and inflorescences. We grew in the glasshouse 60 maternal families from each of two Brazilian populations of the annual herb, Eichhornia paniculata. We measured flower size, daily flower number, and total flower number per inflorescence, and two indices of module size, leaf area and age at flowering. We also assessed the size and number of inflorescences produced over 6 weeks. All floral traits exhibited significant heritable variation, some of which was due to genetic variation in module size. Genetic (maternal family) correlations between daily and total flower number did not differ from 1.0, indicating that display size (daily flower number) cannot evolve independently from total flower number per inflorescence. Genetic correlations between flower size and daily flower number ranged from negative to positive (r=–0.78 to +0.84), depending on population and inflorescence. Positive correlations occurred when variation in investment per inflorescence was high so that some families produced both larger and more flowers. These correlations became zero when we controlled for variation in module size. Families that flowered later produced fewer, larger inflorescences (r=–0.33, –0.85). These data support theoretical predictions regarding the combined effects of variation in resource acquisition and allocation on traits involved in trade‐offs, and they emphasize the hierarchical organization of floral displays. Our results imply that patterns of resource allocation among inflorescences influence evolutionary changes in flower size and number per inflorescence.     

Male-biased sex allocation in late-blooming flowers driven by resource limitation in the clonal perennial Aconitum kusnezoffii (Ranunculaceae)

Flowering phenology and clonal growth are known to affect resource and pollen availability, and therefore select for adaptive or constrained sex allocation strategies to some degree. However, the consequences of temporal sex allocation patterns for reproductive fitness across the flower, inflorescence, and genet levels have rarely been examined. Moreover, experimental tests of the underlying regulatory mechanisms are scarce. We examined the association of flowering phenology and inflorescence position with temporal sex allocation and reproductive success in the protandrous perennial clonal herb, Aconitum kusnezoffii, over four consecutive growing seasons by examining more than 39 000 flowers. We also conducted controlled experiments to test the effects of resource and pollen limitation on the female reproductive success of lateral inflorescences. We found that some male functions were positively correlated with flowering phenology, whereas female reproductive success was negatively correlated with flowering phenology and inflorescence position. Lateral inflorescences invested more in male function than terminal inflorescences and therefore yielded fewer and smaller seeds. Resource limitation may serve as the key mechanism underlying this differentiated pattern. Decreased female reproductive success was consistently observed at the flower and inflorescence levels as flowering occurred later in the growth season. Late-blooming lateral inflorescences specialized in the male function, and their female reproductive success was constrained by early-blooming terminal inflorescences. This might be the first attempt to systematically demonstrate sex allocation strategy differentiation in a protandrous plant species at the inflorescence level. In addition, our study provides empirical evidence of dichogamy selecting for specialized sex allocation strategies among inflorescences.     

ALLOCATION OF REPRODUCTIVE RESOURCES WITHIN AND AMONG INFLORESCENCES OF LAVANDULA STOECHAS (LAMIACEAE)

Patterns of fruit set were studied in Lavandula stoechas, a Mediterranean shrub commonly occurring in southern Spain. The small, hermaphroditic flowers of this shrub are aggregated into dense, headlike inflorescences and exhibit extensive variations in fecundity. It was shown that as the number of developing fruits in the inflorescence increased, the probability of a flower setting fruit, the size of seeds, and their germinability decreased, most likely because of strong within-inflorescence resource limitation. An experiment was designed to ascertain whether increased fertility in late-opening flowers could be induced through reallocation of reproductive resources between different inflorescences. The experiment consisted of removing half of the inflorescence buds from a set of plants and comparing their fecundity with that of intact individuals. Thinning did not increase the proportion of flowers setting fruit which, in fact, was slightly lower than that of intact individuals (probably due to some reduction of floral display brought about by thinning). Although treated plants produced heavier seeds than controls, results suggest that inflorescences of L. stoechas behave as autonomous modules among which resources cannot be reallocated. Predispersal seed predation by insects accounted on average for a 31% reduction in fruit set. Predation was found to be nonrandomly distributed within inflorescences, with most damage concentrated on late fruits (i.e., those with smaller and less germinable seeds).     

Decorative sterile flowers in nine Japanese species of Viburnum (Adoxaceae) and their influence on pollinator visits

Framed inflorescences are unique arrangements in which a cluster of small fertile flowers is surrounded by several larger, decorative sterile flowers. Viburnum (Adoxaceae) species vary in their inflorescence arrangements; some species exhibit framed inflorescences, whereas others do not. We hypothesize that the decorative flowers increase the pollinator-attracting functions of the inflorescences; as proved by previous studies, they additionally function as landing-sites for pollinators. To test our hypotheses, field manipulation experiments were carried out for nine Viburnum species, three with inherently framed inflorescences and six without them: sterile flowers were removed and mounted on species with and without framed inflorescences, respectively. Results show that inflorescences with decorative flowers had higher visit rates than inflorescences without them, and that insect flower visitors did not show landing preference for either flower type. These results suggest that decorative flowers appeared only in a subset of Viburnum species to increase their pollination chances by, mainly, enhancing the attractiveness of the inflorescence. It is likely that species without framed inflorescences use other attraction-enhancing mechanisms, such as a high flowering synchrony within a single cluster of fertile flowers, a trait found in most studied species without decorative flowers.     

Ecological constraints on fruit initiation by Calyptrogyne ghiesbreghtiana (Arecaceae): FLORAL HERBIVORY,POLLEN AVAILABILITY,AND VISITATION BY POLLINATING BATS

Failure of a flower to initiate fruit can be attributed to an insufficiency of resources, genetic incompatibilities, or ecological constraints on pollination. Flower visitors can increase fruit initiation by pollinating flowers, or decrease fruit initiation by damaging them. If, however, resources limit fruit initiation, variation in visitation may be relatively unimportant. Visitors to Calyptrogyne ghiesbreghtiana, a rain forest understory palm, leave a record of their activity by feeding on floral tissue. I recorded variation in inflorescence visitation, floral display, and fruit initiation during 7 mo over two field seasons. On average, bats visited 50-60% of flowers; katydids and scarab beetles visited and damaged the remaining 40-50%. Four species of bat (Phyllostomidae) captured near inflorescences were found to be carrying C. ghiesbreghtiana pollen. Approximately 18% of flowers visited by bats and not damaged by insects initiated fruit, whereas insect-damaged flowers set a negligible number. Some variation in fruit initiation was explained by nightly variation in the proportion of inflorescences at each site that were potential pollen donors (male-phase inflorescences). Visitors responded to variation in floral display; katydids damaged more flowers on taller inflorescences, and in one season bats visited a greater proportion of flowers on inflorescences with many flowers. However, floral display only explained a small amount of variation in visitation. A similar amount of variation in flower visitation was explained by the degree to which inflorescences were obstructed by surrounding vegetation. I used path analysis to summarize the overall effect of floral display on visitation by both pollinators and florivores and the effect of visitation and site sex ratio on fruit initiation. Because almost all flowers were visited by bats or damaged by katydids, the amount of bat visitation was strongly negatively correlated with katydid damage. In spite of the low fruit set from bat-visited flowers, variation in bat visitation explained 27-37% of the variation in fruit initiation.