Studies of Mycorrhizal Fungi of Chinese Orchids and Their Role in Orchid Conservation in China—A Review

China has over 1,200 species of native orchids in nearly 173 genera. About one fourth of native species are of horticultural merit. Some species are of Chinese medicinal value. In fact, the demand on orchid species with high Chinese medicinal values such as Gastrodia elata, Dendrobium offcinale, along with demands on species of cultural importance, such as those in the genus of Cymbidium, is a major factor causing wild populations to diminish and in some cases, drive wild populations to the brink of extinction. These market demands have also driven studies on the role of mycorrhizal fungi in orchid seed germination, seedling and adult growth, and reproduction. Most of these mycorrhizal studies of Chinese orchids, however, are published in Chinese, some in medical journals, and thus overlooked by the mainstream orchid mycorrhizal publications. Yet some of these studies contained interesting discoveries on the nature of the mycorrhizal relationships between orchids and fungi. We present a review of some of these neglected publications. The most important discovery comes from the mycorrhizal studies on G. elata, in which the researchers concluded that those fungi species required to stimulate seed germination are different from those that facilitate the growth of G. elata beyond seedling stages. In addition, presence of the mycorrhizal fungi associated with vegetative growth of post-seedling G. elata hindered the germination of seeds. These phenomena were unreported prior to these studies. Furthermore, orchid mycorrhizal studies in China differ from the mainstream orchid studies in that many epiphytic species (in the genus of Dendrobium, as medicinal herbs) were investigated as well as terrestrial orchids (mostly in the genus Cymbidium, as traditional horticultural species). The different responses between epiphytic and terrestrial orchid seeds to fungi derived from roots suggest that epiphytic orchids may have a more general mycorrhizal relationship with fungi than do terrestrial orchid species during the seed germination stage. To date, orchid mycorrhizal research in China has had a strongly commercial purpose. We suggest that this continuing research on orchid mycorrhizal relationships are a solid foundation for further research that includes more rare and endangered taxa, and more in-situ studies to assist conservation and restoration of the endangered orchids. Knowledge on the identities and roles of mycorrhizal fungi of orchids holds one of the keys to successful restoration and sustainable use of Chinese orchids.     

Thynnine wasps discriminate among heights when seeking mates: tests with a sexually deceptive orchid

The flower of a sexually deceptive orchid, Chiloglottis reflexa, mimics both the sex pheromone and the appearance of a female thynnine wasp (Neozeloboria nr. proxima). The flower is pollinated when visited by male wasps, who attempt mating with the flower. We have used these mimetic flowers to investigate mating behavior of the male wasps. In field choice experiments, males strongly prefer to visit flowers that are very low in the habitat, 15 cm, vs. flowers that are placed at 55 or 105 cm. These studies suggest that male precopulatory response is strongly dependent on the microlocation of the female (or female mimic). Other insect-mimicking orchids, which together attract several groups of Hymenoptera, may be useful in analogous experiments on mating behavior. Additionally, these experiments help elucidate features of the mimetic flowers, particularly stature, that act to efficiently attract potential pollinators.     

Environmental determinants of genetic diversity in Caragana microphylla (Fabaceae) in northern China

Non‐rewarding orchids rely on various ruses to attract their pollinators. One of the most common is for them to resemble flowers sought by insects as food sources. This can range from generalized food deception to the mimicry of specific sympatric food plants. We investigated the basis of pollinator deception in the European food‐deceptive orchid Traunsteinera globosa, which has unusually compact flowerheads resembling those of sympatric rewarding species of Knautia and Scabiosa (Dipsacaceae), and Valeriana (Caprifoliaceae). Visual signals of T. globosa are similar in both fly and bee vision models to those of the sympatric food plants used in the choice experiments, but scent signals are divergent. Field experiments conducted in Austria and the Czech Republic showed that both naive and experienced (with respect to visitation of T. globosa) insect species approached the orchids at the same rate as food plants, but direct contact with orchid flowers was taxon specific. Flies were most easily duped into probing the orchid, and, in doing so, frequently received and deposited pollinaria, whereas most bees and butterflies avoided landing on orchid flowers. We conclude that T. globosa is a mimic of a guild of fly‐pollinated plants, but the ecological dependence of the orchid on its models remains to be fully tested. © 2015 The Linnean Society of London, Botanical Journal of the Linnean Society, 2016, 180 , 269–294.     

Breeding system and pollination by mimicry of the orchid Tolumnia guibertiana in Western Cuba

The mimicry of malpighiaceous oil‐flowers appears to be a recurrent pollination strategy among many orchids of the subtribe Oncidiinae. These two plant groups are mainly pollinated by oil‐gathering bees, which also specialize in pollen collection by buzzing. In the present study, the floral ecology of the rewardless orchid Tolumnia guibertiana (Oncidiinae) was studied for the first time. The orchid was self‐incompatible and completely dependent on oil‐gathering female bees (Centris poecila) for fruit production. This bee species was also the pollinator of two other yellow‐flowered plants in the area: the pollen and oil producing Stigmaphyllon diversifolium (Malpighiaceae) and the polliniferous and buzzing‐pollinated Ouratea agrophylla (Ochnaceae). To evaluate whether this system is a case of mimetism, we observed pollinator visits to flowers of the three plant species and compared the floral morphometrics of these flowers. The behavior, preferences and movement patterns of Centris bees among these plants, as well as the morphological data, suggest that, as previously thought, flowers of T. guibertiana mimic the Malpighiaceae S. diversifolium. However, orchid pollination in one of the studied populations appears to depend also on the presence of O. agrophylla. Moreover, at the two studied populations, male and female pollination successes of T. guibertiana were not affected by its own floral display, and did not differ between populations. The results are discussed in relation to the behavior and preferences of Centris bees, as well as the differential presence and influence of each of the two floral models.     

Male mate‐seeking and mating behaviors of Eucera nipponensis (Hymenoptera: Apidae) at a nectarless orchid habitat: Are empty flower patches a profitable rendezvous site?

Male solitary bees typically use emergence‐nesting areas and/or flower patches of food plants, where receptive females are relatively numerous, as rendezvous sites. However, mate‐seeking males have been also observed at food‐deceptive orchid patches, where numerous encounters with foraging females can hardly be expected, owing to the lack of floral rewards. Here, we describe the male mate‐seeking and mating behaviors of the Japanese long‐horned bee Eucera nipponensis at habitats of the food‐deceptive orchid Cymbidium goeringii. On the basis of the results, we report empty flower patches are not necessarily fruitless sites for mate‐seeking males because naive female bees, which are highly likely to be recently emerged and unmated, can be attracted to non‐rewarding orchids. We also suggest a possibility that a small number of the males could receive a “sexual reward” (i.e. mating opportunities), owing to the food‐deceptive orchid, in return for their pollination work. This occasional interaction could represent the initial stage in the evolution of sexually deceptive orchids from food‐deceptive orchids.     

Comparative reproductive biology and pollinator specificity among sympatric Gomesa (Orchidaceae: Oncidiinae)

• The incredible pollination mechanisms displayed by orchid flowers has inspired biologists over the centuries. Based on the intriguing flower structures, the relationship among orchid species and their pollinators has been frequently regarded as very specialised.
• Given that visits on flowers pollinated by oil‐collecting bees are regularly rare, and in Oncidiinae the flowers frequently attractexclusively species that act as effective pollinators, the comparative reproductive biology and pollinator specificity of two sympatric Gomesa (G. varicosa and G. montana; Oncidiinae) were analysedbased on records of floral morphology, production of floral rewards, pollinators and pollination mechanisms. Furthermore, experimental pollinations were carried out in order to examine the breeding systems.
• The results have show that in the studied population, both Gomesa are visited by several bee species, but these orchids present a specific pollination system.Pollinaria are deposited on the head of Centridini (G. varicosa and G. montana) and Epicharitini (G. varicosa) bees when landed on the central callus of the labellumto collect lipoidal substances produced by glandular elaiophores on lateral lobes of the labellum. Both species are dependent on a biotic pollen vector to set fruits. Gomesamontana is completely self‐incompatible, while G. varicosa is partially self‐compatible.
• Our results indicate that although the occurrence of self‐sterile species seems to be common in Oncidiinae, in partially self‐incompatible species, as is the case of G. varicosa, self‐compatibility has been considered as an important factor favouring reproductive assurance in populations with low visitation frequencies, despite occurrence of inbreeding depression.

     

A specialised pollination system using nectar‐seeking thynnine wasps in Caladenia nobilis (Orchidaceae)

• Caladenia is a diverse Australian genus that is exceptional among orchids in having both species pollinated by food‐seeking and sexually deceived insects. Here, we investigated the pollination of Caladenia nobilis, a species predicted to be food‐deceptive due to its large, cream‐coloured and apparently nectarless flowers.
• Pollinator observations were made using experimental clumps of flowers. Measurements of floral colour were undertaken with a spectrometer, nectar was tested using GC‐MS, and reproductive success was quantified for 2 years.
• While C. nobilis attracted nine species of insect, only males of the thynnine wasp Rhagigaster discrepans exhibited the correct size and behaviour to remove and deposit pollen. Male R. discrepans attempted to feed from the surface of the labellum, often crawling to multiple flowers, but showed no evidence of sexual attraction. Most flowers produced little or no nectar, although some may provide enough sucrose to act as a meagre reward to pollinators. Floral colouration was similar to a related Caladenia species pollinated by sexual deception, although the sexually deceptive species had a dull‐red labellum. Reproductive success was generally low and highly variable between sites and years.
• In addition to most visitors being of inappropriate size for pollinia removal, the lack of response to the orchid by several co‐occurring species of thynnine wasp suggests filtering of potential pollinators at the attraction phase. Our discovery of a pollination strategy that may be intermediate between food deception and food reward raises the question, how many putatively rewardless orchids actually produce meagre amounts of nectar?

     

Autonomous self‐pollination in the nectarless orchid Pogonia minor

The pollination biology of the nectarless orchid Pogonia minor was investigated in central Japan. The investigation revealed that the solitary flowers failed to attract pollinators, while high rates of fruit set were observed in the natural population. Comparable levels of fruit set were obtained in bagged, artificial self‐pollinated and artificial cross‐pollinated plants, indicating that the species is not pollinator‐limited for fruit set under natural conditions. Autonomous self‐pollination in P. minor resulted from a reduced rostellum, which allowed contact between the pollinia and the stigma. Self‐pollination is thought to be an adaptive response that provides reproductive assurance under conditions of pollinator limitation. Since pollen limitation is generally known to be frequent among deceptive orchids, strong pollen limitation is probably a driving force in the autonomous self‐pollination mechanism in the nectarless orchid P. minor.     

Sex pheromone mimicry in the early spider orchid (Ophrys sphegodes): patterns of hydrocarbons as the key mechanism for pollination by sexual deception

We investigated the female-produced sex pheromone of the solitary bee Andrena nigroaenea and compared it with floral scent of the sexually deceptive orchid Ophrys sphegodes which is pollinated by Andrena nigroaenea males. We identified physiologically and behaviorally active compounds by gas chromatography with electroantennographic detection, gas chromatography-mass spectrometry, and behavioral tests in the field. Dummies scented with cuticle extracts of virgin females or of O.sphegodes labellum extracts elicited significantly more male reactions than odorless dummies. Therefore, copulation behavior eliciting semiochemicals are located on the surface of the females' cuticle and the surface of the flowers. Within bee and orchid samples, n-alkanes and n-alkenes, aldehydes, esters, all-trans-farnesol and all-trans-farnesyl hexanoate triggered electroantennographic responses in male antennae. Most of the alkanes and alkenes occurred in similar patterns both in the bees and orchids. O. sphegodes leaf extracts contained mostly the same compounds but in different proportions. In behavioral tests with synthetic compounds, blends of alkenes triggered significantly more approaches and pounces of the males whereas alkanes were not more attractive than odorless dummies. Since alkanes and alkenes together were most attractive, we conclude they constitute the bees' sex pheromone as well as the pseudocopulation-behavior releasing orchid-odor bouquet. Accepted: 30 March 2000     

Visual discrimination between two sexually deceptive <Emphasis Type="Italic">Ophrys</Emphasis> species by a bee pollinator

Almost all species of the orchid genus Ophrys are pollinated by sexual deception. The orchids mimic the sex pheromone of receptive female insects, mainly hymenopterans, in order to attract males seeking to copulate. Most Ophrys species have achromatic flowers, but some exhibit a coloured perianth and a bright, conspicuous labellum pattern. We recently showed that the pink perianth of Ophrys heldreichii flowers increases detectability by its pollinator, males of the long-horned bee Eucera berlandi. Here we tested the hypothesis that the bright, complex labellum pattern mimics the female of the pollinator to increase attractiveness toward males. In a dual-choice test we offered E. berlandi males an O. heldreichii flower and a flower from O. dictynnae, which also exhibits a pinkish perianth but no conspicuous labellum pattern. Both flowers were housed in UV-transmitting acrylic glass boxes to exclude olfactory signals. Males significantly preferred O. heldreichii to O. dictynnae flowers. In a second experiment, we replaced the perianth of both flowers with identical artificial perianths made from pink card, so that only the labellum differed between the two flower stimuli. Males then chose between both stimuli at random, suggesting that the presence of a labellum pattern does not affect their choice. Spectral measurements revealed higher colour contrast with the background of the perianth of O. heldreichii compared to O. dictynnae, but no difference in green receptor-specific contrast or brightness. Our results show that male choice is guided by the chromatic contrast of the perianth during the initial flower approach but is not affected by the presence of a labellum pattern. Instead, we hypothesise that the labellum pattern is involved in aversive learning during post-copulatory behaviour and used by the orchid as a strategy to increase outcrossing.     

Effect of individual height and labellum colour on the pollination of Caladenia (syn. Arachnorchis) behrii (Orchidaceae) in the northern Adelaide region, South Australia

Caladenia behrii, a sexually deceptive orchid, is an endangered terrestrial orchid endemic to the Adelaide Hills, South Australia. We examined pollination success among individuals of different colours and heights in three populations of C. behrii in the northern Adelaide region. The labellum of C. behrii varies from cream to deep maroon. Over five years, the pollination success (pollinia deposited on stigma) of four colour groups (maroon, maroon and cream, hatched, and cream) was assessed for a total of 782 flowers. Labellum colour had no effect on the pollination success of individuals, indicating no frequency-dependent selection. It is likely that pollinators use the sexual pheromone mimic produced by the flowers as the main orientation cue. For three years the height of pollinated C. behrii individuals was recorded, along with the height of the nearest non-pollinated neighbour (distance of labellum from the ground, rather than stem length). Although a range of different heights was pollinated at population level, individual flowers that were taller than their closest neighbours were significantly more likely to be pollinated. Flower head height was not correlated with opening date and was greater for orchids growing among grass-tree leaves. Results imply that pollinators are more successful in finding tall flowers than short ones for visual and/or olfactory reasons; however, the effect of height preference is eliminated at population level.     

Orchid seed removal by ants in Neotropical ant‐gardens

• Most plants that inhabit ant‐gardens (AGs) are cultivated by the ants. Some orchids occur in AGs; however, it is not known whether their seeds are dispersed by AG ants because most orchid seeds are tiny and dispersed by wind.
• We performed in situ seed removal experiments, in which we simultaneously provided Azteca gnava ants with seeds of three AG orchid species and three other AG epiphyte species (Bromeliaceae, Cactaceae and Gesneriaceae), as well as the non‐AG orchid Catasetum integerrimum.
• The seeds most removed were those of the bromeliad Aechmea tillandsioides and the gesneriad Codonanthe uleana, while seeds of AG orchids Coryanthes picturata, Epidendrum flexuosum and Epidendrum pachyrachis were less removed. The non‐AG orchid was not removed. Removal values were positively correlated with the frequency of the AG epiphytes in the AGs, and seeds of AG orchids were larger than those of non‐AG orchids, which should favour myrmecochory.
• Our data show that Azt. gnava ants discriminate and preferentially remove seeds of the AG epiphytes. We report for the first time the removal of AG orchid seeds by AG ants in Neotropical AGs.

     

A nocturnal Provespa wasp species as the probable pollinator of epiphytic orchid Coelogyne fimbriata

Many vespid wasps visit flowers to forage nectar. These hymenopterans sometimes contribute to flower pollination. However, none of the nocturnal wasp species is a known pollinator. We collected individuals of light‐attracted Provespa nocturna workers in a montane rainforest on Peninsular Malaysia: some wasps collected bore orchid pollinia on their thoraxes. Among 114 trapped individuals, four bore pollinaria and nine bore only viscidia, suggesting that pollinia had been successfully transported. Molecular barcoding of the pollinia (based on their ITS sequences) assigned the orchid to a species in Coelogyne fimbriata complex. These findings and our other analyses suggest that this nocturnal wasp contributes to pollination of an epiphytic nectarless orchid that probably releases olfactory attractants. This discovery sheds light on the importance of mutualistic relationships between the nocturnal social wasps and epiphytic orchids in Southeast Asian tropical rainforest canopies.     

Comparative water balance profiles of Orchidaceae seeds for epiphytic and terrestrial taxa endemic to North America

The Orchidaceae have dust-like seeds that use wind currents for long-distance dispersal. Lacking endosperm, orchid embryos consume free-living, mycorrhizal fungi as a carbon source (mycotrophy) after settling on a substrate. Few studies have investigated orchid seed morphology as it relates to ecology, but conceivably variations in seed size and testa characteristics could be linked to water loss rates aimed at maximizing germination in a particular habitat. Seeds of 2 epiphytic, 1 aquatic, and 7 terrestrial orchids native to North America were compared with respect to water balance profiles: Cleistes bifaria, Encyclia tampensis, Epidendrum nocturnum, Habenaria repens, Isotria medeoloides, Liparis elata, L. hawaiensis, Platanthera holochila, P. integrilabia, and P. leucophaea. Water content, water loss rate, activation energy, and equilibrium humidity were assessed for each species. Seeds of epiphytic orchids were smaller, lighter, more porous, and had higher water loss rates compared to terrestrials. No active mechanism for water absorption exists in seeds of either group. Water loss appears to be a species-specific phenomenon that may be linked to the ecological niches these species occupy.     

Pollination of Platanthera chlorantha (Orchidaceae): new video registration of a hawkmoth (Sphingidae)

Documenting species interactions is a time consuming enterprise, in particular for rare interaction events and interactions taking place at night. Pollinators foraging on orchids have traditionally been monitored by discovering pollen vectors on collected insects, recording traces left by moths on the orchid, direct observations and recently by continuous video monitoring. Direct observations in the wild of orchids with low visitation rates is time demanding. In the present study I monitored greater butterfly‐orchids (Platanthera chlorantha), by using a event triggered video monitoring system. A total of 23 nights of monitoring were conducted, whereas only 6 nights had visits by one moth species, namely the pine hawk‐moth (Hyloicus pinastri). The total numbers of pine hawk‐moths registered were 18. In addition to species identification, the video recordings also enabled detection of pollinaria on the pine hawk‐moths. Most of the pine hawk‐moth visits took place around midnight. The visit lasted on average for 38.0 sec and the average number of flowers visited was 9.6. In future studies, this video system could give more details on interactions between orchids and insects and even link it to environmental factors (e.g. varying weather conditions).     

Retrospective spatial analysis of the pollination of two miniature epiphytic orchids with different pollination strategies in a coffee plantation in Soconusco,Chiapas, Mexico

Quantitative and spatial data for orchid pollination are scarce and may be important tools for reintroduction and conservation; however, conclusions cannot be drawn on the basis of the typically infrequent and unpredictable pollination events. We carried out a novel, retrospective, spatial analysis of the pollination of the entire population of two miniature orchids, Erycina crista‐galli and Notylia barkeri, on coffee bushes in plantations at 900 m in Soconusco, south‐eastern Mexico. The numbers of mature flowering plants of both species in the experimental site were similar. Notylia barkeri produced nearly four times as many flowers, but a similar proportion of the total number of flowers produced was pollinated (1.23% and 1.48% for N. barkeri and E. crista‐galli, respectively). An estimated 29 919 977 (±4 983 995) seeds were produced by N. barkeri, nearly 12 times more than E. crista‐galli at 1 009 414 (±147 000). The pollinators of N. barkeri chose flower clusters at random and pollinated various flowers within a patch, whereas the pollinators of E. crista‐galli chose patches of flowers slightly more systematically, with less dependence on flower density, and appeared to dedicate less attention to each patch. For both species, pollinators slightly favoured larger clusters of flowers and left many individual and groups of flowers unvisited. To restore populations of these orchids in coffee plantations as a replacement habitat, N. barkeri should be planted in small, separate groups and E. crista‐galli in larger groups of individuals, dispersed regularly throughout the selected site to maximize the possibility that the flowers will be discovered by pollinators. © 2008 The Linnean Society of London, Botanical Journal of the Linnean Society, 2008, 158 , 448–459.     

Long-term ecology of euglossine orchid-bees (Apidae: Euglossini) in Panama

Summary Abundance patterns during 6–7 years and orchid visitation were determined for 51 species of the 57 local euglossine bees. Male bees were counted at 3 chemical attractants presented in the same manner each month. Sites were separated by 75 km but included wet Atlantic forest at 500 m elevation, moist forest at 180 m near Barro Colorado Island, and cloud forest at 900 m near the Pacific ocean. 1. From 15 to 30 euglossine species of 4 genera were active in each month and site; monthly species number and general bee abundance were positively correlated. Many species had 3 annual abundance peaks (range 1–4) and were active throughout the year, but peak annual abundances rarely occurred during late wet or early dry seasons. In contrast, Eufriesea generally were present as adults only 1–2 months in a year. 2. Euglossine populations were exceptionally stable. Species at each site were more stable than any known insect population, and stability and abundance were positively associated. However, year-to-year population stability and the degree of seasonality were not correlated. Among the three sites, the more diverse (species rich) bee assemblages displayed lower stability; these were the wetter and upland sites. 3. The most abundant bees visited more orchid species. Eg. and El. each visited and average of 4 orchid species (range 0–13); Ex. and Ef. visited 0–3. Stable populations did not visit more or fewer orchid species than did unstable populations. 4. Less than 68% of species at each site visited orchid flowers; less than a few dozen of the 100–800 bees counted in a day carried orchid pollinaria. Over 20% of the euglossine species never were seen with pollinaria at any site and probably seldom visit orchids in central Panama. 5. Most bee species visited 1 or no fragrance orchids in a given habitat. Orchids tended to utilize common pollinators that seldom included more than 1 species, and they utilized stable or unstable, seasonal or aseasonal bees. However, the most stable and abundant bee, Eg. imperialis, rarely pollinated orchids; fewer than 10 of ca. 20000 bees carried pollinaria. 6. Orchids may interact primarily with discrete seasonal bee population peaks-probably the emerging adults. Although specialized orchid preferences are implicated for species that visit few or no local orchids but pollinate other species and carry pollinaria in other areas, euglossine bees do not need orchids to survive or reproduce.     

Size,structure and nitrogen content of seeds of Fabaceae in relation to nodulation

Looking for clues to explain the low rate and unpredictability of the pollination of allogamous, epiphytic orchids in the context of the success of the orchid family in general, we compared the pollination of two miniature twig epiphytes in Mexico: Notylia barkeri, a ‘weedy’, rewarding species, and Erycina crista‐galli, a rare, deceptive species. We measured the effects of the spatial organization of the flowers and various parameters of visibility and height above the ground in relation to the spatial organization of the seed capsules (which retrospectively measures the activity of the pollinators). The spatial presentation of the flowers of E. crista‐galli explained only 5% of the distribution of the seed capsules. For N. barkeri, with compound flowers, the spatial presentation, considering individual flowers or inflorescences, explained 12% and 45% of the distribution of the seed capsules, respectively, and all other interactions between the variables were insignificant. Both the deceptive and reward strategies resulted in the production of large numbers of seeds despite a low pollination percentage (1–5%). Notylia barkeri produced 11.8 (2005–6) and 53.7 (2007–8) times more seeds in total than E. crista‐galli. Furthermore, unlike E. crista‐galli, N. barkeri responded to loss of individuals after high winds with an increased production of flowers per plant. We suggest that orchids have evolved to specialize in chance, and instead of maximizing pollinator attraction, they maximize the seed production resulting from every casual encounter. © 2010 The Linnean Society of London, Botanical Journal of the Linnean Society, 2011, 165 , 251–266.     

Non-species-specific pollen transfer and double-reward production in euglossine-pollinated Vanilla

• Commonly attributed to orchids, the pollen movement in Vanilla has been associated with food deception and specific plant–pollinator relationships.
• This study investigated the role of flower rewards and pollinator specificity in the pollen transfer of a widely distributed member to the euglossinophilous Vanilla clade, V. pompona Schiede using data collected from Brazilian populations. These included investigations on morphology, light microscopy and histochemistry, and analysis of flowers scent using GC–MS. The pollinators and the mechanisms of pollination were recorded through focal observations.
• The yellow flowers of V. pompona are fragrant and offer nectar as reward. The major volatile compound of the V. pompona scent, carvone oxide, shows convergent evolution in Eulaema-pollinated Angiosperms. The pollination system of V. pompona is not species-specific, but its flowers are strongly adapted to pollination by large Eulaema males. Pollination mechanism is based in a combination of perfume collection and nectar seeking.
• The dogma of a species-specific pollination system based on food deception in Vanilla has been broken with the increase in studies on this Pantropical orchid genus. Here, least three bee species and dual reward-offering are involved in pollen transfer in V. pompona. Visitation frequency of bees collecting perfumes, used in courtship by male euglossines, is higher than in searching for food, as short-lived young euglossine males seem to be more interested in sex than food. A pollination system based on offering both nectar and perfumes as resources is described for the first time in orchids.