Cost of reproduction in the pink lady's slipper orchid (Cypripedium acaule, Orchidaceae): an eleven-year experimental study of three populations

An 11-yr experimental study of the cost of reproduction in three wild populations of the perennial orchid Cypripedium acaule contrasted experimental plants that were repeatedly hand-pollinated and often made fruits with control plants that were not hand-pollinated and only rarely made fruits. Repeated flowering without subsequent fruit production resulted in no detectable reduction in either plant size or probability of flowering in subsequent years. A cost of fruit production was evident in experimental plants in all three populations in terms of a reduced probability of flowering and smaller leaf area in subsequent years, but was not evident in terms of mortality rate. Experimental effects of fruit production reached maximum values at 3-7 yr, depending on the population. The probability of remaining dormant below ground in a given year was strongly dependent on plant size in the previous year. Furthermore, the length of the dormancy period (one to several years) was a significant and inverse function of plant size just prior to dormancy. Sample sizes and the consequent ability to detect experimental effects declined over time as more plants died or stopped flowering. Four to seven years appears to be an optimal duration for studies of the cost of reproduction in perennial herbs similar to this species. Studies lasting less than 4 yr may be too brief to reveal experimental effects, whereas those lasting more than 7 yr may fail to reveal new insights.     

Re-establishment of the lady's slipper orchid (Cypripedium calceolus L.) in Britain

The Sainsbury Orchid Conservation Project (SOCP), based in the Micropropagation Unit of the Royal Botanic Gardens, Kew, has worked for many years with English Nature, and the Species Recovery Programme in particular, in raising plants of the lady's slipper orchid for re-establishment. This is a collaborative venture with the involvement of a large number of organizations and individuals at national and local level.Cypripedium calceolusis one of Britain's rarest plants. Thought at one time to be extinct, its decline is due to overcollection by botanists for herbarium specimens and by gardeners and it is found now on a single, fragile, natural site. It has been wardened since 1970s because of concerns about long-term safety and is protected under Schedule 8 of the Wildlife and Countryside Act 1981. Natural pollination has not been observed and hand pollination is carried out to ensure seed set. Some seed is scattered on site resulting in a few seedlings and the remaining capsules are sent to the Sainsbury Orchid Conservation Project. In addition, some plants of native origin are held in cultivation and molecular techniques are being carried out at Kew to ascertain how these are related. The best pollination strategy to increase genetic diversity is co-ordinated by English Nature and SOCP, as is the optimum collection time post-pollination to achieve maximum germination. Seedlings are propagated in the laboratory using immature green capsules sown on a range of nutrient media. No symbiotic fungus has yet been found for this species. Germination occurs after 6 weeks in the dark and the plants chilled when roots are well developed and shoots beginning to form. Plants potted up at Kew and near the native site have produced leaves and buds and extensive planting trials have now commenced. The main objective is to increase the number of localities whereCypripediumoccurs through re-establishment. As its decline is due to overcollection rather than habitat loss, many old sites have changed very little. Observation of continental populations is important in assessing suitability of potential sites as the extant clone may not be in optimum conditions. An initial planting trial on the wild site in winter 1989/90 resulted in a 75% survival rate of seedlings planted out. However, establishing seedlings is a long process and careful monitoring is required.     

Pollination of the lady's slipper Cypripedium henryi Rolfe (Orchidaceae)

The pollination ecology of Cypripedium henryi Rolfe, a slipper orchid endemic to west China, was investigated, and its floral shape, size, colour, and scent were analysed. Examination of the breeding system suggests that the flowers are self-compatible, but need pollen vectors for successful reproduction. The flower is rewardless; over 15 insects belonging to Araneida, Hymenoptera, Diptera, Lepidoptera, and Coleoptera were recorded as flower visitors, but most only alighted or rested on the flower. In the total 32 h of observations over 2 years, female Lasioglossum bees were found to be the most frequent visitors and the only pollinators. They showed a high visitation frequency and, surprisingly, re-visited the same flowers frequently. Cypripedium henryi probably attracts pollinators visiting the flowers through general food deception (odour components, colour, false nectar guides), as well as special structures (slippery labellum, slippery staminode). Although three Lasioglossum species visited the flowers, only L. sauterum Fan et Ebmer was found with pollen. Lasioglossum flavohirtum Ebmer was large and climbed out from the entrance. Morphologically, L. sichuanense Fan et Ebmer could be considered as a potential pollinator, but the collected specimens were found to have no pollen of C. henryi on their bodies. It was speculated that the particular floral scent of C. henryi discouraged the entrance of L. sichuanense bees. Lasioglossum sauterum was matched morphologically to the flower, but not all of the visitations resulted in effective pollinations, as some flowers of C. henryi were frequently re-visited and the pollen mass had been taken away by bees on previous visitations. © 2008 The Linnean Society of London, Botanical Journal of the Linnean Society , 2008, 156 , 491–499.     

Genetic diversity and structure of the endangered lady's slipper orchid Cypripedium japonicum Thunb. (Orchidaceae) in Japan

Cypripedium japonicum Thunb. (Orchidaceae), once a common perennial herb, is now designated as endangered throughout most of its distribution due to habitat destruction and fragmentation, and the impacts of horticultural collection. We investigated the genetic characteristics of this species for conservation purposes, using microsatellite markers to examine the genetic diversity and structure of 15 native and 5 ex situ populations in Japan. The results imply that although allelic variation is low in Japanese C. japonicum, sexual reproduction by seed, as well as clonal propagation, may occur in some populations. Both native and ex situ populations were found to be genetically differentiated, indicating that some populations may have experienced recent population declines, genetic fragmentation, or bottlenecks. The degree of genetic drift from the putative ancestral population, inferred through STRUCTURE analysis, was more pronounced in northern populations than in southern populations. Some of the ex situ conserved populations exhibited a low degree of differentiation from ancestral native populations. Our results imply that conservation of C. japonicum in Japan is best supported by maintaining individual populations and their unique genetic characteristics.     

Conservation genetics and taxonomic status of the rare Kentucky lady's slipper: Cypripedium kentuckiense (Orchidaceae)

Cypripedium kentuckiense is a recently described rare orchid found in Arkansas (predominantly) and in eight other states. Much debate has focused on whether this taxon should be recognized as a distinct species or considered to be an extreme manifestation of the variability present in the widespread taxon Cypripedium parviflorum var. pubescens. In this study, 12 isozyme loci were analyzed for 14 populations of C. parviflorum var. pubescens and eight populations of C. kentuckiense. These data were used to examine the genetic similarity of these taxa, assess whether isozyme data support the continued recognition of C. kentuckiense as a distinct species, and assess whether a newly discovered disjunct Virginia population of C. kentuckiense is genetically isolated from other C. kentuckiense populations. The isozyme data revealed that the two taxa are very closely related with a high interspecific genetic identity. However, C. kentuckiense populations contain a subset of the variation present in C. parviflorum var. pubescens, and they have expected levels of heterozygosity that are one-quarter that of C. parviflorum var. pubescens populations. Cypripedium kentuckiense also possesses one widespread unique allele and a unique multilocus genotype. These data suggest that C. kentuckiense should be recognized as a distinct species, possibly of recent origin from C. parviflorum. Lastly, the isozyme data support the hypothesis that gene flow between the Virginia population and other populations of C. kentuckiense has been restricted.     

Pollination of a slippery lady slipper orchid in south-west China: Cypripedium guttatum (Orchidaceae)

Cypripedium guttatum was studied in north-west Yunnan at 3490 m a.s.l. The flowers are rewardless 'kettle traps'. The structure of the lip, where pollinators are temporarily kept prisoner, and the method of their capture, are unusual in being Paphiopedilum - rather than Cypripedium -like. The deceptive orchid does not mimic any of the diverse flowers concurrently blooming in the habitat, all being visited by the polylectic pollinators of C. guttatum , viz . Lasioglossum virideglaucum, L. clypeinitens and L. sauterum , besides two additional probable pollinators and four non-pollinating visitors (all Halictidae; three new species). The bees got caught when they tried to climb onto the staminode and their forelegs slid down its slippery downward ridges, causing them to tumble to the pouch bottom. To leave, they had to climb a tunnel leading past the stigma to the anthers where a pollen smear was acquired while extruding themselves from the narrow exit. The similarities with myiophylous Paphiopedilum are discussed in view of the possibility that they may foreshadow evolutionary transitions between melittophily and myiophily found in slipper orchids.  © 2005 The Linnean Society of London, Botanical Journal of the Linnean Society , 2005, 148 , 251–264.     

Survival costs of adult dormancy and the confounding influence of size in lady's slipper orchids, genus Cypripedium

Adult whole-plant dormancy is a phenomenon in which a perennial, herbaceous plant does not sprout for one or more years. Although previous studies have noted a cost of dormancy to survival, none have accounted for the potentially confounding influence of size variation on this relationship. I asked whether the probabilities of dormancy and survival in dormancy-prone plants vary with size, possibly creating the appearance of a life-history tradeoff between survival and dormancy. I censused sympatric populations of three lady's slipper orchid taxa, Cypripedium parviflorum , C. candidum , and C. × andrewsii , in an 11-year study (1994 to 2004) at Gavin Prairie, Illinois, USA. Annual dormancy and survival trends were modeled using Cormack-Jolly-Seber mark-recapture analysis, while stage-specific survival and stratum-transitions (i.e. probability of transitioning among stages conditional upon survival) were modeled with multi-strata mark-recapture analysis. Annual dormancy probabilities and transition probabilities to and from dormancy varied synchronously among taxa, while trends in survival did not. Both survival and dormancy varied with number of sprouts in the previous year, positively in the case of the former and negatively in the case of the latter. Accounting for plant size in this way eliminated any variation in survival by life-history stage, with dormant plants surviving at the same rate as non-dormant plants of the same size. Transitions among stages did not vary with plant size. My results suggest common climatic cues to dormancy, and suggest caution in inferring costs of dormancy from studies in which plant size is not controlled, as such costs may be artifacts of smaller plants being more dormant-prone and less likely to survive.     

Pollination of the Lady's slipper orchid (Cypripedium calceolus) in Scandinavia – taxonomic and conservational aspects

The Lady's slipper orchid Cypripedium calceolus L. is considered one of the most beautiful orchids of Europe. Consequently, the species has suffered from over-collecting and is now critically endangered in many countries. Although pollination success is suspected to influence the long-term survival of Cypripedium calceolus , relatively little is known about the identity of its pollinators in mainland Sweden – a region that comprises the largest European populations. In order to identify which species pollinate eight representative populations in mainland Sweden, we observed and sampled visitors to flowers using a standardized protocol. Specimens were identified and any pollen smear found on their body was examined for the presence of Cypripedium pollen. Nine species were recognized as effective pollen vectors ( Andrena cineraria, A. carantonica, A. haemorrohoa, A. helvola, A. nigroaenea, A. praecox, Colletes cunicularius, Lasioglossum fratellum and L. fulvicorne ), four of them for the first time in Scandinavia. This is the first time that a species of Colletes is reported to carry pollen of Cypripedium in this region. All but one specimens were females. Our results suggest a taxonomically heterogeneous pollinator fauna for Cypripedium calceolus and are discussed in light of the management of this species.     

Embryo development in the lady's slipper orchid, Paphiopedilum delenatii, with emphasis on the ultrastructure of the suspensor

BACKGROUND AND AIMS: Owing to large-scale collecting, the lady's slipper orchid, Paphiopedilum delenatii, is under threat of extinction. Asymbiotic germination provides a useful way to re-establish plants in the wild and for commercial propagation. A detailed study of embryo development would provide information on subsequent germination events and aid in the propagation of the species. METHODS: Developing capsules were collected for histochemical and ultrastructural studies by using both light and transmission electron microscopy. KEY RESULTS: The suspensor of this species consists of three vacuolated cells. During the early globular stage of embryo development, structural differentiation occurs, revealing an abundance of smooth endoplasmic reticulum cisternae and wall ingrowths within the suspensor cells. These features are not present in cells of the embryo proper. Furthermore, the results of Nile red staining demonstrate that a cuticular layer is present only in the embryo proper, but absent from the suspensor. Cuticular material is also present in the inner walls of the seed coat, and persists through seed maturation. CONCLUSIONS: The morphological features of the transfer cell and the absence of cuticular material in the suspensor cell wall corroborate the hypothesis that the suspensor is the major nutrient uptake site for the developing embryo in the lady's slipper orchid. The absence of an endosperm and presence of cuticular material in the inner walls of the seed coat enclosing the embryo proper further support the notion that nutrient uptake by the embryo is confined to the micropylar end of the seed through the suspensor.     

Dynamics and viability analysis of transplanted and natural lady's slipper (Cypripedium japonicum) populations under habitat management in South Korea

To assess the effectiveness of conservation‐based transplantation of the endangered orchid (Cypripedium japonicum), we compared the morphology, physiology, stem‐count change, and population viability of natural versus transplanted populations undergoing habitat management (repeated removal of competing understory vegetation) between 2009 and 2015 in South Korea. The restored site had lower transmitted light and soil humidity than the natural site. The natural and transplanted populations differed in leaf morphology and total chlorophyll content (natural: 1.00 ± 0.04, restored: 0.53 ± 0.06). No recruitment occurred during the monitoring period. Population viability tended to decrease in the restored population (λ_G = 0.97, μ = ?0.05, σ² = 0.036) and increase in the natural population (λ_G = 1.07, μ = 0.03, σ² = 0.075). The repeated removal of competing understory vegetation had different effects on leaf traits, abundance, and reproductive properties of the endangered orchids in both populations. Notably, habitat management increased the stem count and flowering rate in natural C. japonicum but did not increase the fruit‐setting rate. Thus, despite repeated habitat management efforts (removal of competing understory vegetation), we conclude that the population viability of transplanted populations of the endangered orchid C. japonicum had poor long‐term viability compared with naturally occurring populations, a difference that is mainly attributed to inappropriate transplant‐site selection.     

Spatial genetic structure and clonal diversity of island populations of lady's slipper (Cypripedium calceolus) from the Biebrza National Park (northeast Poland)

Three populations of the rare and endangered plant species Cypripedium calceolus were included in a study of genetic diversity and spatial genetic structure in the Biebrza National Park, northeast Poland. Analysis of 11 allozyme loci indicate that the populations of this species contained high genetic variability (P = 45.5%, A= 1.73). On the other hand, the genetic differentiation (FST = 0.014, P < 0.05) among C. calceolus populations was very low when compared to other species with similar life history characteristics. The observed high rate of gene flow (Nm = 18) may suggest that the populations studied derived from each other in the recent past. Five polymorphic allozyme markers identified 109 multilocus genotypes in three populations and the majority of them (67%) were population-specific. One of the populations studied, characterized by particularly extensive vegetative reproduction, showed the lowest clonal diversity (G/N = 0.15) and heterozygosity (HO = 0.111) values and the highest FIS(0.380), when compared to other two populations (G/N = 0.26-0.27, HO= 0.166-178, FIS = 0.024-0.055). This may indicate that clonal reproduction has an important influence on the genetic structure of C. calceolus populations. The longevity of genets, the out-crossing breeding system and the presence of recruitment from seeds are factors maintaining genetic diversity in C. calceolus.     

Nuclear cytoplasmic domains,microtubules and organelles in microsporocytes of the slipper orchid Cypripedium californicum A. Gray dividing by simultaneous cytokinesis

Microsporocytes of the slipper orchidCypripedium californicum A. Gray divide simultaneously after second meiosis. The organization and apportionment of the cytoplasm throughout meiosis are functions of nuclear-based radial microtubule systems (RMSs) that define domains of cytoplasm - a single sporocyte domain before meiosis, dyad domains within the undivided cytoplasm after first meiosis, and four spore domains after second meiosis. Organelles migrate to the interface of dyad domains in the undivided cytoplasm after first meiotic division, and second meiotic division takes place simultaneously on both sides of the equatorial organelle band. Microtubules emanating from the telophase II nuclei interact to form columnar arrrays that interconnect all four nuclei, non-sister as well as sister. Cell plates are initiated in these columns of microtubules and expand centrifugally along the interface of opposing RMSs, coalescing in the center of the sporocyte and joining with the original sporocyte wall at the periphery to form the tetrad of microspores. Organelles are distributed into the spore domains in conjunction with RMSs. These data, demonstrating that cytokinesis in microsporogenesis can occur in the absence of both components of the typical cytokinetic apparatus (the preprophase band of microtubules which predicts the division site and the phragmoplast which controls cell-plate deposition), suggest that plant nuclei have an inherent ability to establish a domain of cytoplasm via radial microtubule systems and to regulate wall deposition independently of the more complex cytokinetic apparatus of vegetative cells.     

Pollination and fruit set in two rewardless slipper orchids and their hybrids (Cypripedium,Orchidaceae): large yellow flowers outperform small white flowers in the northern tall grass prairie

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

     

Allozyme differentiation and genetic structure of the Lady's slipper (Cypripedium calceolus) island populations in north-east Poland

The population genetic structure in the rare and endangered perennial plant, Cypripedium calceolus , from north-east Poland was investigated. A total of 11 loci were analysed, of which five were polymorphic for the species and in every population. The 11 loci resolved gave a total of 19 alleles with the mean number of 1.73 alleles per locus. The proportion of polymorphic loci (P) was the same for the species and in every population, 45.5%. The average observed and expected heterozygosities for the total Lady's slipper data set were 0.156 and 0.184, respectively. The average expected heterozygosity for the populations under study ranged from 0.176 to 0.188 and did not differ significantly among populations. Genetic diversity within C. calceolus populations from the Biebrza Valley is relatively high compared with rare taxa and taxa with similar life histories. The genetic diversity among populations of C. calceolus studied ( F _ST = 0.016) is much smaller than the genetic diversity within populations. In the species studied, there was no significant correlation between genetic and geographical distances ( r = −0.73, Mantel test). This may indicate the relatively recent origin of the populations studied, or a high level of gene flow among populations. © 2002 The Linnean Society of London, Botanical Journal of the Linnean Society , 2002, 138 , 433–440.     

Contrasting levels of genetic diversity between the historically rare orchid Cypripedium japonicum and the historically common orchid Cypripedium macranthos in South Korea

Many terrestrial orchids are historically rare and occur in small, spatially isolated populations. Theory predicts that such species will harbour low levels of genetic variation within populations and will exhibit a high degree of population genetic divergence, primarily as a result of genetic drift. If the origin of the present‐day populations is relatively recent from the same genetically depauperate source population, a complete lack of genetic differentiation between conspecific populations is expected. If a terrestrial orchid was historically common with moderate or high levels of genetic diversity, but has experienced more recent anthropogenic disturbance as a result of over‐collection, it would still exhibit initial levels of genetic variation within populations and a low degree of genetic divergence between populations. To test these predictions, we examined the genetic diversity in six populations (N = 131) of the historically and currently rare Cypripedium japonicum and in four populations (N = 94) of the historically common but now rare C. macranthos from South Korea. Fourteen putative allozyme loci resolved from eight enzyme systems revealed no variation either within or among populations of C. japonicum, which supports the first prediction. In contrast, populations of C. macranthos harboured high levels of genetic variation (mean percentage of polymorphic loci %P = 46.7; mean expected heterozygosity H_e = 0.185) and exhibited a low degree of population genetic divergence (G_ST = 0.059), supporting the second prediction. The lack of genetic variation both within and among conspecific populations of C. japonicum may suggest that populations originated from the same genetically depauperate ancestral population. The high levels of genetic diversity maintained in populations of C. macranthos suggest that the collection‐mediated decrease in the number of individuals is still too recent for long‐term effects on genetic variation. Based on current demographic and genetic data, in situ and ex situ conservation strategies should be provided to preserve genetic variation and to ensure the long‐term survival of the two species in the Korean Peninsula. © 2009 The Linnean Society of London, Botanical Journal of the Linnean Society, 2009, 160 , 119–129.     

Population size,pollinator visitation and fruit production in the deceptive orchid Calypso bulbosa

It has been proposed that in non-rewarding animal-pollinated plants the pollination intensity should decrease with increasing population size and should increase with increasing local abundance of reward-producing plants. To test these hypotheses, we examined how population size, local abundance of Salix caprea, and tree cover were related to pollen removal and fruit production in 16 populations of the deceptive, early-flowering and bumblebee-pollinated orchid Calypso bulbosa in northern Sweden in 3 consecutive years. To determine whether fruit production was limited by pollinator visitation, supplemental hand-pollinations were performed in three populations in 3 years. Finally, to examine whether increased fruit production was associated with a reduction in future flower production, vegetative growth or survival, supplemental hand-pollination was repeated for 5 years in one population. The levels of pollen export, pollen deposition, and fruit set of C. bulbosa varied considerably among years and among populations. The proportion of plants exporting pollen was negatively related to population size, and positively related to density of S. caprea and to tree cover in 1 of the 3 years. In the other 2 years, no significant relationship was detected between proportion of plants exporting pollen and the latter three variables. In no year was there a significant relationship between fruit set and population size, density of S. caprea and tree cover. There was substantial among-year variation in the extent to which fruit production was limited by insufficient pollen deposition and in the amount of weather-induced damage to flowers and developing fruits. Fruit set was consistently higher in hand-pollinated than in open-pollinated plants, but this difference was statistically significant in only one of 3 years. Supplemental hand-pollination in 5 consecutive years increased cumulative fruit production 1.8 times, but did not affect flower production, plant size, or survival. Tree cover was negatively correlated with the incidence of frost damage in 1 year. The results indicate that life-time seed production may be pollen limited in C. bulbosa, and that variation in population size and local abundance of the early-flowering, nectar-producing S. caprea can only partly explain the extensive variation in pollinator visitation among populations of this species.     

Effects of defoliation and girdling on fruit production in Ilex aquifolium

1. The effects of defoliation and girdling on fruit production in European holly Ilex aquifolium were studied in a northern Spanish population. Three defoliation treatments (control, 50% and 100% leaf removal) were applied at branch level in 10 trees. Six branches were used per treatment in each tree and half of these branches were girdled (a ring of bark and cambium was removed from the branch base).
2. Leaf removal from ungirdled branches had little effect on fruit set, fruit production and reproductive allocation at branch level. However, these variables decreased as the extent of defoliation increased on girdled branches.
3. Fruit production in undefoliated branches did not differ between girdled and ungirdled branches, showing that girdled branches were autonomous for fruit production when undamaged. Mean fruit mass of girdled-100% defoliated branches averaged 8% of fruit mass produced by control branches.
4. Fruit production of ungirdled-100% defoliated branches did not differ from control branches, showing the importance of resource importation from other branches. Hence the branches may be regarded as only partially autonomous for fruit production.
5. Fruit production of girdled-50% defoliated branches was 42% of fruit production of control branches, while ungirdled-50% defoliated branches amounted to 70% of controls. These results also demonstrated resource importation but did not support the existence of photosynthetic compensatory mechanisms.
6. The ability of resource importation developed by fruiting branches might be a mechanism to reduce the effect of reproductive costs in this species.     

The mesmerizing wart: the pollination strategy of epiphytic lady slipper orchid Paphiopedilum villosum (Lindl.) Stein (Orchidaceae)

Paphiopedilum uillosum was studied in hill evergreen forests (at up to 35 m above ground level) in North Thailand between 1990 and 1994. Flowering lasted 4.5 months: flower longevity 2–3 months. During 224 hours of flower-watching, less than 100 specimens of Syrphidae (Diptera) were seen in the vicinity of the flowers; 15 cases of pollen acquisition were mainly by female Eplsyrphus alternans, Syrphus fulvifacies, Betasyrphus serarius among 6 spp. of pollinators. Populations peaked during the main flower opening period, one month before the maximum number of open flowers was reached in early February. The flowers are 'kettle-traps' without known reward, luring mainly by food deception. Long distance attraction is probably by a urine-like odour (attraction to mammalian excretions had hitherto been little reported) and colour contrast. Close range lure is by the glittering staminode (probably mimicking droplets of honeydew/moisture) centred by a slippery wart (faking a perch) at which pollinators fly, immediately losing their grip and tumbling into the pouch, preventing wing action and falling being disrupted by a trough-shaped frame. Escape is up the tunnel, past the stigma, to the exit where, pressed by several mechanisms against the anther, the hoverfly scoops off very sticky pollen which has a viability of at least 8 weeks. Capsule formation averaged 8%.     

Breeding system and factors limiting fruit production in the nectarless orchid Broughtonia lindenii

Low fruit set values in most orchids (especially epiphytic and tropical species) are normally thought to be the consequence of pollination constraints and limited resources. In particular, pollination constraints are modulated by pollinator visitation rates, pollinator visitation behaviour (promoting crossing or selfing), the type and number of pollinia deposited on stigmas (in the case of orchids with subequal pollinia) and the amount of pollen loaded per inflorescence. In order to assess to what extent these factors can affect fruit set in specific orchid-pollinator systems, the repercussions of some of these aspects on reproduction of Broughtonia lindenii were examined in a coastal population in western Cuba. The study focused on plant breeding system, importance of pollen load and type of pollinia on subsequent fruit and seed, limiting factors of seed production and interaction with pollinators. This species presents long-lasting flowers that senesce after all forms of effective visit. Pollinator dependence for fruit production was demonstrated, while hand-pollination experiments revealed self-compatibility and inbreeding depression at seed level. More pollinia on stigmas enhance the proportion of well-developed seeds. In contrast, the pollinia type used in pollination is not important for seed quality of fruits, suggesting that small pollinia are not rudimentary. Natural fruit set in two consecutive years was substantially affected by pollinator activity, and also by systematic depredatory activity of ants and a caterpillar. Considering that this orchid completely lacks nectar and that the local assemblage of pollinators and predators influenced its reproduction, a minor importance of resource constraints in this epiphyte (with long-lasting reserve structures) is confirmed at least for a short time.