Pollinia Removal Research Articles

Floral mechanisms promote pollination success and reduce the incidence of self-pollination in a fly-pollinated self-incompatible orchid.

Among flowering plants, self-incompatibility is considered the most efficient system for avoiding self-fertilization. However, many self-incompatible plants have also evolved floral mechanisms to reduce sexual conflict. In China, some studies of Bulbophyllum have been reported to be self-incompatible and no fruit sets. However, we have observed relatively high fruit sets in Bulbophyllum funingense. Therefore, we speculated that if B. funingense is also self-incompatible, and it might present a floral mechanism to avoid sexual conflict. Natural fruit sets, pollinia removal and deposition rates were determined and breeding system was tested in a hand-pollination experiment. The pollination process and visiting frequency of pollinators and their behavior after escape from access were observed and recorded. Floral traits associated with pollination and pollinator size were measured. B. funingense was completely self-incompatible, the fruit sets of cross-pollination in 2 years were all more than 70%, and the natural fruit sets for 2 years were 1.70 ± 4.31% and 6.63 ± 5.29%, respectively. B. funingense did not produce strong odor or nectar, but produced a kind of secretions from its labellum that attracted flies. Calliphora vicina (Calliphoridae) was its only effective pollinator. When C. vicina licked the secretions, they were stuck in the access for a long time. Thus, when they escaped from access, they almost always flew quickly away from the inflorescence removing pollinia most of the times. In B. funingense, a floral mechanism improves pollinia transfer efficiency, reduces pollinia waste, promotes pollination success, reduces the incidence of self-pollination, and avoids sexual conflict to a certain extent.

Continuous video capture, and pollinia tracking, in Platanthera (Orchidaceae) reveal new insect visitors and potential pollinators.

Orchids often have specific pollinators, which should provide reproductive isolation, yet many produce natural hybrids. Platanthera dilatata and P. stricta differ in floral morphology but often co-occur, overlap in flowering, and are reputed parents of P. xestesii. We used motion-triggered video detection units to monitor floral visitors of P. dilatata and P. stricta on Vancouver Island, Canada. Pollinia removal in P. dilatata was observed using histochemical staining, and cross-pollinations were performed to determine compatibility. From 1,152 h, 753 videos were recorded; 655 contained insects and 91 contained arachnids. Bumblebees, butterflies, and moths removed pollinia from P. dilatata. No pollinia removal was observed from P. stricta. Five videos showed insects moving between Platanthera species. Pollinia removal rates were low. Hand-pollinations resulted in capsule development and seed production. This study adds to the known diversity of insects interacting with these orchids, and highlights regional differences in floral visitors.

Pollination success in three tropical dry forest orchid species from Mexico: insights from floral display, visitation rates, and flower micromorphology

Background: Despite long-lasting efforts to disentangle the drivers of orchid pollination, pollination success in tropical dry forest orchids remains largely unknown.
 Questions and hypothesis: How successful are pollination in three tropical dry forest orchids? How is pollination influenced by floral display and floral rewards (as suggested by floral micromorphology)? We hypothesized a positive effect of floral display on pollinia removal and deposition rates.
 Studied species: Barkeria whartoniana (C. Schweinf.) Soto Arenas, Clowesia dodsoniana E. Aguirre, and Cyrtopodium macrobulbon (La Llave & Lex.) G.A. Romero & Carnevali.
 Study site and dates: Nizanda (Oaxaca), Mexico; flowering periods of 2013 and 2014.
 Methods: We calculated pollinia removal and deposition rates, identified floral visitors and analyzed flower microstructure to search for structures potentially producing rewards. Floral display was measured through number of open flowers, and number and length of inflorescences, and its effect on pollination success was assessed through linear modeling.
 Results: Pollinia removal rates were higher than deposition rates, and floral display was related to pollination success in C. dodsoniana only. Visitation rates were low for the three species and most visitors were not true pollinators. The three species possess potentially secreting structures, but for B. whartoniana and C. macrobulbon these rewards are likely part of the pollinator deception mechanism.
 Conclusions: The generalized low pollination success implies the need for high population densities of both interacting parts. We emphasize the need for integrated evaluations of different aspects of the plant-pollinator interaction.

The uncinate viscidium and floral setae, an evolutionary innovation and exaptation to increase pollination success in the Telipogon alliance (Orchidaceae: Oncidiinae)

Floral innovations are key for pollinator specialization and play a significant role in plant diversification. Orchidaceae present many examples of floral innovations that allow its high degrees of pollinator specialization and promoted speciation. The rich neotropical genus Telipogon evolved an uncinate (=hook-like) viscidium on the pollinarium and setae-bearing flowers, which are uncommon in Orchidaceae; however, the importance of them on pollination success and whether they are floral innovations or exaptations in Telipogon have not been investigated. Here we investigate the morphology of the viscidium and floral setae within the Telipogon alliance (including the genera Hofmeisterella, Trichoceros and Telipogon), test their significance in pollination, and their occurrence and evolution across the Oncidiinae. We used Telipogon peruvianus as a model species to test whether uncinate viscidium and floral setae increased pollination success compared with a cochleariform (=spoon-like) viscidium and lack of floral setae condition. We show that the uncinate viscidium is a synapomorphy for Telipogon; setae-bearing flowers are not universally found among all species of Telipogon and evolved once in the Telipogon alliance. Furthermore, Telipogon peruvianus flowers with an uncinate viscidium have achieved higher pollinia export than those with cochleariform viscidium (ancestral condition), whereas flowers with setae have both higher success in pollinia removal, although not significant, and pollinia deposition than those lacking of setae (ancestral condition). We demonstrate that uncinate viscidia and floral setae in Telipogon are a key innovation and exaptation, respectively, that enhance pollination success and they might act as drivers of diversification and pollinator specialization in this genus.

High fruit sets in a rewardless orchid: a case study of obligate agamospermy in Habenaria

Low fruit set and pollination limitation are common characteristics of non-autogamous orchids, especially in rewardless species. The flowers of many Habenaria species are often characterised by long spurs and are mostly pollinated by long-tongued hawkmoths or butterflies. Unlike the flowers of other Habenaria species, the flowers of Habenaria malintana (Blanco) Merr. have very short spurs with no nectar or scent; however, this species is able to maintain high fecundity in south-west China. Breeding system experiments suggested that H. malintana is an obligate agamospermous orchid. Seed set did not need to be triggered by pollen grain deposition on stigmas, and ~100% fruit set was found in different populations and years. In pollen germination experiments, hand-deposited pollen failed to germinate on stigmas. The flowers of H. malintana failed to attract any pollinators, as we did not observe any floral visitors, and no pollinia removal or deposition occurred in both 2013 and 2014 at two study sites. These results strongly suggested that H. malintana has completely abandoned sexual reproduction and has adopted obligate agamospermy to achieve high reproductive output. We suggest that this strategy may have evolved to provide reproductive assurance and reduce the cost of flowers in response to unreliable pollinator service.

Movements of floral parts and roles of the tooth on the column wall of <i>Bulbophyllum praetervisum</i> (Orchidaceae) flower in pollination by Dacini fruit flies (Diptera: Tephritidae)

Bulbophyllum is the largest genus of the orchid family, with about 2000 species that are mainly pollinated by flies. Flowers of many Bulbophyllum species under the Sections Sestochilos and Beccariana specifically attract Dacini fruit flies, Bactrocera and Zeugodacus species, as pollinators. Non-nectar producing and non-resupinate solitary flowers of Bu. pratervisum emit specific and pleasant floral fragrances to specifically attract and reward male fruit flies. Slippery surfaces on their lateral sepals aid in pollination. Although pollinia removal by male fruit flies has been observed frequently, deposition of pollinia to complete pollination (by two males of Ba. albistrigata and Z. caudatus) has only been observed recently. Field observations show two previously unreported movements of floral parts – a) petals and medial sepal during daily closing and reopening of flowers, and b) the spring-loaded and hinged lip during removal and deposition of pollinia by a male fruit fly. Additionally, a third (novel) movement has been observed, either when the flower closes for the night to protect the stigma, or after a fly has deposited the pollinia onto the stigma, the 'acute tooth' on each column wall folds inwards specifically to secure the newly deposited pollinia.

Visitantes florales y potencial polinizador de trichocentrum stramineum orquídea amenazada y endémica de Veracruz

Trichocentrum stramineum es una orquídea endémica del centro de Veracruz y en categoría de riesgo como amenazada según la NOM-059-SEMARNAT-2010 por la reducción poblacional donde habita. Poca información se ha generado de esta orquídea en la literatura especializada y hasta antes del presente trabajo se desconocían sus visitantes florales y su potencial polinizador. De 2014 a 2017, se realizaron observaciones directas e indirectas a las inflorescencias de T. stramineum para registrar los visitantes florales y determinar al potencial polinizador en dos localidades de su distribución geográfica. Se registraron dos especies de visitantes florales en la localidad 1 y tres en la localidad 2. La abeja Centris nitida (Apidae) fue observada efectuando la remoción y deposición de los polinios de T. stramineum en ambas localidades. La abeja Centris tarsata (Apidae) fue observada un par de ocasiones en cada localidad sin que realizara remoción ni deposición de los polinios. La avispa Polybia sp., fue observada en dos ocasiones sólo en la localidad 2 sin llevar a cabo la remoción de polinios. La orquídea T. stramineum presenta un sistema especializado de polinización al depender solo de una especie para la fecundación de las flores. Los registros del polinizador de T. stramineum son los primeros en obtenerse y documentarse para esta orquídea.

Control of anthocyanin pigmentation during flower development inCymbidiumorchid

The range of flower colours in Cymbidium hybrida orchid is extensive. All three main pigment groups have been detected, but our focus has been on the anthocyanins, which may be present in all sepals and petals, only in the labellum, or as a colour blush. Since anthocyanin pigments have an important influence on final flower colour, it is important to study how their biosynthesis is regulated. We report here the isolation of a MYB transcription factor (ChMYB1) that is shown to be an anthocyanin-related MYB and likely to be part of a regulatory complex controlling anthocyanin biosynthesis in Cymbidium flowers. There are at least two separate phases of anthocyanin development in Cymbidium flowers. One occurs during flower bud development, and the other occurs in open flowers after pollination. The relatively rapid induction of anthocyanin biosynthesis after anther cap removal was used to monitor expression of the MYB1 gene and the flavonoid biosynthetic gene dihydroflavonol 4-reductase (DFR). The involvement of ethylene in this anthocyanin induction was examined by applying the ethylene action inhibitor, 1-methyl-cyclopropene (1-MCP), and by studying the expression of ethylene biosynthesis genes. Expression of the MYB1 gene was first detected 12 h after pollinia removal, and it peaked after 24 h, while expression of the DFR gene was first detected at 24 h after pollinia removal and it peaked after 48 h. 1-MCP treatment abolished completely both anthocyanin accumulation and the expression of the ChMYB1 and ChDFR genes. The results suggest that ChMYB1 regulates in Cymbidium hybrida flowers the pollination-induced anthocyanin production mediated by ethylene signalling.

Male and female reproductive success in natural and anthropogenic populations of Malaxis monophyllos (L.) Sw. (Orchidaceae)

Abstract In the presented study, male and female reproductive success was analyzed in relation to the population size, floral display and pollinators’ availability in natural and anthropogenic populations of the orchid Malaxis monophyllos (L.) Sw. Our results indicated significant differences between all investigated populations in parameters of floral display, including heights and number of flowers per inflorescence, as well the number of flowering individuals and their spatial structure. Additionally, populations differed both in male (pollinia removal) and female (fruit set) reproductive success, but only the fruit set clearly differentiated anthropogenic and natural populations. Despite the average flower number per plant being significantly higher in two of the anthropogenic populations, it was not related to the fruits set, which was significantly lower there. Moreover, our preliminary study concerning the potential pollinators of M. monophyllos showed a higher contribution of flies in natural habitats than in anthropogenic ones. Thus, we can suspect that the main factors influencing the level of female reproductive success in M. monophyllos populations are abundance of effective pollinators, as well as flower visitors, which may have resulted in a different level of pollen discounting in populations. Therefore, further studies concerning breeding system and pollination as important forces that shape demographic processes in M. monophyllos populations are necessary. Our results also indicate that suitable conservation methods in M. monophyllos should always include the preservation of potential pollinators, especially in these new, secondary habitats.

Experimental fertilization increases amino acid content in floral nectar, fruit set and degree of selfing in the orchid Gymnadenia conopsea.

Floral traits have evolved to maximize reproductive success by attracting pollinators and facilitating pollination. Highly attractive floral traits may, however, also increase the degree of self-pollination, which could become detrimental for plant fitness through inbreeding depression. Floral nectar is a trait that is known to strongly mediate pollinator attraction and plant reproductive success, but the particular role of the nectar amino acid (AA) composition is poorly understood. Therefore, we experimentally manipulated the nectar AA composition and abundance of the Lepidoptera-pollinated orchid Gymnadenia conopsea through soil fertilization, and we quantified AA content and AA composition through high performance anion exchange chromatography with pulsed amperometric detection. Mixed models were then used to evaluate differences in pollinia removal, fruit set, seed set and degree of selfing between fertilized and control individuals. Selfing rates were estimated using microsatellite markers. We found that fertilized individuals had a significantly higher nectar AA content and an altered AA composition, whereas plant height, number of flowers, nectar volume and sugar concentration remained unchanged. Fertilized individuals also had significantly more pollinia removed and a higher fruit set, whereas control plants that did not receive the fertilization treatment had significantly fewer selfed seeds, and more viable seeds. Although we cannot exclude a role of changes in floral scent following the fertilization treatment, our results strongly suggest a relation among nectar AA composition, fruiting success and selfing rates. Our results also indicate potential consequences of nutrient pollution for plant reproductive success, through the induced changes in nectar AA composition.

Mast fruiting in a hawkmoth-pollinated orchid Habenaria glaucifolia: an 8-year survey

The hypothesis of predator satiation has been proposed to explain mast fruiting in various flowering plants. It considers that the simultaneous production of large numbers of seeds by a plant population reduces the risk of seed predation for each individual. Orchids produce huge numbers of seeds per fruit and rarely experience seed predation. It remains unclear which factors may affect fluctuating fruit production in orchids, which generally suffer a widespread pollen limitation. To explore the temporal pattern of fruiting and potential factors related to fluctuation in fruit production, we investigated reproductive success of a long-spurred orchid (Habenaria glaucifolia) in an alpine meadow with thousands of individuals over 8 years. To estimate reproductive success, pollinator observation was conducted by day and at night, and pollinia removal and receipt were recorded in the field population for 8 years. To examine whether fruit set and seed set are pollen limited, we conducted supplementary pollination experiments and compared fruit set, seed set and pollinia movement of open-pollinated flowers from 2011 to 2013. We measured lengths of spurs and pollinator proboscises, and nectar volume and concentration, to identify potential pollinators. Hawkmoths were seen to be effective pollinators for H. glaucifolia in 3 years, whereas in the remaining 5 years no pollinators were observed, and consequently pollinia were rarely transferred. Numerous pollinia movements were observed in 2012, 2013 and 2014 (pollinia removal: 48, 59 and 85%; pollinia receipt 51, 70 and 80%), and correspondingly fruit set was significantly higher in 2012 and 2013 (59 and 46%) than in 2011 (25%). It was fruit set, rather than seed set, that was pollen limited in this orchid in the 3 years, in that supplementary pollination increased fruit set but did not increase seed set per fruit compared to natural. Three species of hawkmoths had proboscis lengths that matched the spur length of H. glaucifolia. Fruit set in this long spurred orchid depends on the activity of long-tongued hawkmoths, resulting in significant temporal variation in fruit production. Mast fruiting in this alpine orchid could be attributed to a ‘sit and wait’ strategy, awaiting an abundance of effective pollinators.

Weak trophic links between a crab-spider and the effective pollinators of a rewardless orchid

Sit and wait predators hunting on flowers are considered to be exploiters of plant–pollinator mutualisms. Several studies have shown that plant–pollinator interactions can be highly susceptible to the impact of a third trophic level, via consumptive (direct) and non-consumptive (indirect) effects that alter pollinator behavior and, ultimately, plant fitness. However, most flowering plants attract a wide array of flower visitors, from which only a subset will be effective pollinators. Hence, a negative effect of an ambush predator on plant fitness should be expected only when: (i) the effective pollinators are part of the predators' diet and/or (ii) the non-consumptive effects of predator presence (e.g. dead prey) alter the behavior of effective pollinators and pollen movement among individual plants. We analyzed the direct and indirect effects of a crab-spider (Misumenops pallidus), on the pollination and reproductive success of Chloraea alpina, a Patagonian rewardless orchid. Our results indicate that most of the flower visitors do not behave as effective pollinators and most effective pollinators were not observed as prey for the crab-spider. In terms of non-consumptive effects, inflorescences with and without spiders and/or dead-prey did not vary the frequency of flower visitors, nor pollinia removal or deposition. Hence, it is not surprising that M. pallidus has a neutral effect on pollinia removal and deposition as well as on fruit and seed set. Similar to other rewardless orchids, the low reproductive success of C. alpina (∼6% fruit set) was associated with the limited number of visits by effective pollinators. Negative top-down effects of a flower-visitor predator on plant pollination may not be anticipated without studying the direct and indirect effects of this predator on the effective pollinators. In pollination systems where effective pollinators visited flowers erratically, such as in deceptive orchids, we expect weak or no effect of predators on plant fitness.

Both biotic and abiotic factors influence floral longevity in three species of Epidendrum (Orchidaceae)

AbstractExtended flower longevity has been widely defended to occur as a consequence of low pollination activity. To test this hypothesis in Neotropical rainforests, we selected three species of Epidendrum that flower during rainy conditions and commonly exhibit low levels of insect visits. Experimental studies carried out in 15 populations distributed along a wide spatial gradient detected the presence of pollinator limitation in all populations. Pollinia removal without pollen deposition increased longevity, and thus extended longevity could apparently be considered as an ecological advantage for these orchids. Nevertheless, flower longevity was severely shortened by abiotic factors like precipitation and humidity. Comparison with other tropical orchids showed that flower longevity was higher even in species that flower during periods of more pollinator activity than the ones studied here, which is contrary to the hypothesis that pollinators are the only driving force for long‐lived flowers in Epidendrum. Thus, although long floral longevities are apparently favorable for the reproductive success of these species, the high maintenance costs experienced during rainy conditions are also an important factor constraining the selection of long‐lived flowers in Epidendrum.

Clubiona spider (Araneae: Clubionidae) visiting flowers of nectariferous orchid Neottianthe cucullata

AbstractSpiders are usually thought to obtain their energy for growth, maintenance and reproduction from captured prey. However, not all spiders should be assumed to receive all of their energy from prey. Accumulated studies have documented nectarivory in a wide variety of hunting spiders. We report a Clubiona spider visiting flowers of the nectariferous orchid Neottianthe cucullata as an example of spider nectarivory. In addition, during the visitations by Clubiona spider, pollinia removal was observed. The impact of the Clubiona spider on the N. cucullata reproductive success is also discussed.

四川黄龙沟少花鹤顶兰繁殖成功特征

PDF HTML阅读 XML下载 导出引用 引用提醒 四川黄龙沟少花鹤顶兰繁殖成功特征 DOI: 10.5846/stxb201109301441 作者: 作者单位: 南昌工程学院,中国科学院植物研究所系统与进化植物学重点实验室,四川省黄龙国家级风景名胜区管理局,四川省黄龙国家级风景名胜区管理局 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目(30770379);中国科学院重大创新项目(kzcx2-yw-414) Pollination success of Phaius delavayi in Huanglong Valley, Sichuan Author: Affiliation: Nan Chang Institute of Technology,,, Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:少花鹤顶兰(Phaiu delavayi)是多年生、多次结实的具有克隆能力的地生兰科植物,是中国特有种。目前少花鹤顶兰开花物候、花寿命、繁殖成功等生物学特征尚不清楚,而这些资料是开展少花鹤顶兰进化和保护生物学研究的基础。利用2005-2007年四川黄龙沟少花鹤顶兰的调查数据,对少花鹤顶兰繁殖成功特征进行了研究。结果表明黄龙沟少花鹤顶兰每个花序的平均花朵数为3(1-7)朵。叶和花的形态指标在年季间无显著变异。2005-2007年3年间的开花物候没有明显的差异,花期始于6月中旬,于7月底至8月初结束,持续约6-7周,80%-90%的花在7月初的开花高峰期开放,属花集中开放模式。花寿命与是否授粉密切相关,成功授粉的花寿命比没有授粉的花寿命短。少花鹤顶兰是自交亲和的,但其结实完全依赖于两种熊蜂的传粉,不存在自动自花授粉和无融合生殖现象。柱头可授性和花粉活力可维持15 d左右。繁殖成功率年季间的变化很大,并表现出逐年下降的趋势,花粉移走率为18%-51%,自然结实率为10%-36%。繁殖成功下降的趋势可能与黄龙沟喷洒农药有关。 Abstract:Phaius delavayi is a long-lived, polycarpic, pseudobulbous clonal orchid species and is endemic to China. Generally, the flower phenology, flower life span, and pollination success are important features for plant species evolution and conservation. Those features in Phaius delavayi were studied detailed in 2005-2007 in Huanglong Valley, Sichuan. The results showed that the plants have 3 or 4 leaves, and the largest leaf were 16.9-17.5 cm long, 4.8 -4.9 cm wide. The inflorescence is sparsely 1-7-flowered (with mean 3), exceeding height of leaves, 18.4-19.5 cm. Flowers widely opening, with 1.9-2.2 cm long, 1.1 cm wide labellum, and 1.0-1.2 cm long spur. Length of the leaf and floral traits were not significant different, as well as flower phenology during three years. Fruits were 20.78 mm long, 8.10 mm wide, and 00424 g weight. The inflorescence growth began in mid May and last about 50 days, continued until early July. Flowering began in mid June and last about 6-7 weeks, continued until late July/early August, with 80%-90% flowers flowered in a peak time (last about 10 days) in early July. Life span of inflorescences showed considerable variation among years, which were 23, 21, and 29 days for 2005, 2006, and 2007, respectively. The flower life span was closely correlated with pollination, that with successful pollination was 15-19 days, significantly shorter than that of flowers without pollination (17-22 days). Fruit maturity was in mid-latter September, and the leaves were yellow and withered. The results of pollinia viability and stigma receptivity experiments showed that the flowers are self-compatible, but the reproductive success is strictly dependent on visitation by pollinia vectors (Bombus hypnorum and B. lepidus), and there is no autogamy and apogamy in this speices. The stigma has receptivity at the first day of flowering, and can last about 15 days, and lost receptivity completely 20 days after flowering. The fruit set was higher 1-10 days after flowering than that 15 days after flowering. The pollinia has also viability at the first day of flowering, and can last about 15 days, lost viability completely 20 days after flowering, but there was no differences in pollinia viability during one to 15 days. The lost of stigma receptivity was sharper than that of pollinia viability. The pollinia viability and stigma receptivity can last even to the flower withered. Reproductive success showed considerable variation among years and was decline with year. The pollinia removal and nature fruit set were 18%-51% and 10%-36%, respectively, and spraying of pesticides in Huanglong Valley may play a role for the declination of pollination success. 参考文献 相似文献 引证文献

Inflorescence architecture affects pollinator behaviour and mating success in Spiranthes sinensis (Orchidaceae)

• Despite the wide inflorescence diversity among angiosperms, the effects of inflorescence architecture (three-dimensional flower arrangement) on pollinator behaviour and mating success have not been sufficiently studied in natural plant populations. • Here, we investigated how inflorescence architecture affected inter- and intra-plant pollinator movements and consequent mating success in a field population of Spiranthes sinensis var. amoena (S. sinensis). In this species, the flowers are helically arranged around the stem, and the degree of twisting varies greatly among individuals. The large variation in inflorescence architecture in S. sinensis results from variation in a single structural parameter, the helical angle (the angular distance between neighbour-flower directions). • The numbers of visits per inflorescence and successive probes per visit by leaf-cutting bees decreased with helical angle, indicating that individual flowers of tightly twisted inflorescences received less visitations. As expected from pollinator behaviour, pollinia removal and fruit set of individual flowers decreased with helical angle. Meanwhile, geitonogamy decreased in tightly twisted inflorescences. • Our novel findings demonstrate that natural variation in inflorescence architecture significantly affects pollinator behaviour and reproductive success, suggesting that inflorescence architecture can evolve under pollinator-mediated natural selection in plant populations. We also discuss how diverse inflorescence architectures may have been maintained in S. sinensis populations.

Floral longevity and scent respond to pollen manipulation and resource status in the tropical orchid Myrmecophila christinae

Floral longevity (FL) is a key aspect in plant reproductive ecology. Despite this, the effect of resource status on FL has usually been ignored, and never has resource status been linked to the effects of pollen manipulation on FL. In addition, immediate changes in floral scent characteristics subsequent to pollen addition/removal have not been looked at. Here we use the tropical orchid Myrmecophila christinae to address the following: (1) Does flower bud removal (resource status change) increase FL? (2) Does pollen manipulation (addition/removal) decrease FL, and do such effects interact with plant resource status? (3) Are there rapid changes in floral scent production and composition after pollen manipulation? To answer the first question, we removed 50% of the flower buds on 24 plants (24 more were controls). To test the second question, 1 month after removing buds, one of four flowers on each inflorescence received one of the following treatments: no manipulation, pollinia removal, pollination, or pollination + pollinia removal. Finally, to answer the third question, one of four flowers on each of 15 plants (different site) received one of the above-mentioned pollen treatments. Flowers were collected 2, 4, and 6 h after manipulation to measure scent production/composition. Results showed that flowers on bud-removed plants remained open significantly longer relative to those on control plants, and that pollination significantly decreased FL. Additionally, scent production increased throughout the morning and responded differently depending on the pollen manipulation treatment; scent composition on the other hand, remained relatively unchanged throughout the sampling period. By studying both floral scent and physical changes in M. christinae, this study intends to offer a more integrated view of floral senescence within the context of resource and pollen status conditions.

An Asian orchid, Eulophia graminea (Orchidaceae: Cymbidieae), naturalizes in Florida

Eulophia graminea, a terrestrial orchid native to Asia, has naturalized in southern Florida. Orchids naturalize less often than other flowering plants or ferns, but E. graminea has also recently become naturalized in Australia. Plants were found growing in five neighborhoods in Miami-Dade County, spanning 35 km from the most northern to the most southern site, and growing only in woodchip mulch at four of the sites. Plants at four sites bore flowers, and fruit were observed at two sites. Hand pollination treatments determined that the flowers are self compatible but fewer fruit were set in selfed flowers (4/10) than in out-crossed flowers (10/10). No fruit set occurred in plants isolated from pollinators, indicating that E. graminea is not autogamous. Pollinia removal was not detected at one site, but was 24.3 % at the other site evaluated for reproductive success. A total of 26 and 92 fruit were found at these two sites, where an average of 6.5 and 3.4 fruit were produced per plant. These fruits ripened and dehisced rapidly; some dehiscing while their inflorescences still bore open flowers. Fruit set averaged 9.2 and 4.5 % at the two sites. No floral visitors were seen during limited (6.5 hr duration) timed watches of flowers. Individual flowers are open an average 11 days, and the inflorescences may bear flowers for at least one month. How E. graminea entered Florida is unknown, but capsules, bulbs and plantlets in flasks are available for sale and/or trade via the internet from Thailand and other places outside the U.S. The occurrence of the orchid at 900-1000 m elevation its native Sikkim (27-28oN) and in Kashmir (above 32oN), suggest that it can live well north of current area of naturalization in southern Florida, which is at sea level and 26oN latitude.

Is Floral Longevity Influenced by Reproductive Costs and Pollination Success in Cohniella ascendens (Orchidaceae)?

Although studies have shown that pollen addition and/or removal decreases floral longevity, less attention has been paid to the relationship between reproductive costs and floral longevity. In addition, the influence of reproductive costs on floral longevity responses to pollen addition and/or removal has not yet been evaluated. Here, the orchid Cohniella ascendens is used to answer the following questions. (a) Does experimental removal of flower buds in C. ascendens increase flower longevity? (b) Does pollen addition and/or removal decrease floral longevity, and does this response depend on plant reproductive resource status? To study the effect of reproductive costs on floral longevity 21 plants were selected from which we removed 50 % of the developing flower buds on a marked inflorescence. Another 21 plants were not manipulated (controls). One month later, one of four flowers on each marked inflorescence received one of the following pollen manipulation treatments: control, pollinia removal, pollination without pollinia removal or pollination with pollinia removal. The response variable measured was the number of days each flower remained open (i.e. longevity). The results showed significant flower bud removal and pollen manipulation effects on floral longevity; the interaction between these two factors was not significant. Flowers on inflorescences with previously removed flower buds remained open significantly longer than flowers on control inflorescences. On the other hand, pollinated flowers closed much faster than control and removed-pollinia flowers, the latter not closing significantly faster than control flowers, although this result was marginal. The results emphasize the strong relationship between floral longevity and pollination in orchids, as well as the influence of reproductive costs on the former.

Flowering phenology, nectary structure and breeding system in Corymborkis flava (Spiranthoideae:Tropidieae), a terrestrial orchid from a Neotropical forest

Flowering phenology, breeding system and nectary structure of Corymborkis flava (Sw.) Kuntze were studied in a fragment of the Atlantic Forest in south-eastern Brazil. The flowering period extended from March (end of rainy season) to early June and seed dispersal occurred from June to September (dry season). Flowering peak occurred mainly in April, with up to 34 open flowers per plant being observed. The yellow, odourless and tubular flowers lasted ~7.8 days. The flowers present a perigonal nectary located in the basal lateral parts of the labellum; this is the first report on the nectary location and characterisation in the Tropidieae tribe. At the pre-anthesis stage, cells of both secretory parenchyma and epidermis of the nectary are filled with compound amyloplasts. However, starch grains were not observed in these tissues in senescent flowers, indicating that these starch grains are hydrolysed and used as source of sugars for nectar production. The nectar accumulates between the cuticle and the outer periclinal wall of the epidermal cells before flowing out into the nectar chamber. C. flava is a self-compatible species and spontaneous self-pollination does not occur because of hercogamy. The high pollinia removal (0.80) and insertion (0.82) per flower, as well as the high natural fruit-set indicate an efficient natural pollination system. The present study contributes for the knowledge of the diversity of reproductive strategies and nectary structures in Orchidaceae.