Fitness consequences of altering floral circadian oscillations for Nicotiana attenuata

Ecological interactions between flowers and pollinators are all about timing.Flower opening/closing and scent emissions are largely synchronized with pollinator activity,and a circadian clock regulates these rhythms.However,whether the circadian clock increases a plant's reproductive success by regulating these floral rhythms remains untested.Flowers of Nicotiana attenuata,a wild tobacco,diurnally and rhythmically open,emit scent and move vertically through a 140° arc to interact with nocturnal hawkmoths.We tethered flowers to evaluate the importance of flower positions for Manduca sexta-mediated pollinations;flower position dramatically influenced pollination.We examined the pollination success of phase-shifted flowers,silenced in circadian clock genes,NaZTL,NaLHY,and NaTOCi,by RNAi.Circadian rhythms in N.attenuata flowers are responsible for altered seed set from outcrossed pollen.     

Do flowers wave to attract pollinators? A case study with Silene maritima

To answer the question whether flowers wave to attract pollinators, we determine: (1) the heritability of floral mobility; (2) whether wavy flowers attract more insects; (3) does the duration of pollination affect seed set; and (4) the relationship between seed set and floral mobility. The pollination ecology of Silene maritima was investigated. Flowers on stalks of different waviness were used to investigate the effect of floral movement on pollinator visits. There is heritable variation in both direct and indirect estimates of floral mobility. The highest insect total visitation times were associated with medium length thin stalks that were visited more frequently and by more insect species. Although mean individual visit durations were less than those of less mobile flowers, this was compensated for by increased visits. Observations of controlled pollinations show that when the visit times are low, so is seed set and therefore low and high mobility flowers might suffer from reduced fitness. Combining these observations provides a mechanism that could be driving stabilizing selection for flower stalk traits, with a trade-off applying between waving to attract pollinators and not being too mobile as to prevent effective pollination. Further evidence for stabilizing selection is provided by the relationship observed in the field between seed set and floral mobility where the highest levels of fitness was associated with intermediate levels of floral waving.     

Effects of florivory on floral volatile emissions and pollination success in the wild parsnip

In addition to reducing fitness by consuming reproductive structures, florivores may also reduce plant fitness by altering interactions with pollinators. To date, the effects of florivore activity on the volatile profile of flowers and subsequent attractiveness to pollinators have not been extensively investigated. In this study, we had three specific objectives: to determine the impact of florivory by the parsnip webworm Depressaria pastinacella on the floral volatile profile of the wild parsnip Pastinaca sativa, to ascertain the mechanisms by which florivory changes the volatile profile, and to estimate the consequences of florivory on visitation by pollinators and eventual seed set. An overall indirect effect of webworms on seed set, that is, the effect of infestation on pollination success, was not detected. However, this overall lack of indirect effect masks the heterogeneity among individual plants. For seven of 14 plants examined, pollination success was altered by webworms, and in four of these plants the alteration in pollination success was consistent with webworm-altered visitation. Webworms significantly altered floral fragrance, in particular causing disproportionate increases in the emissions of octyl esters. Additionally, volatiles from webworm frass, which contains large amounts of the octyl ester metabolite n-octanol, may alter the floral fragrance in ways that change attractiveness of flowers to pollinators. This study suggests that the effects of florivores on plant fitness are not limited to the removal of floral units but may also involve alterations in floral volatile composition, through damage-induced release and detoxification of particular constituents, that affect visitation and pollination success. Handling Editor: Steve Johnson. An erratum to this article can be found at     

Variation in floral longevity between populations of Campanula rotundifolia (Campanulaceae) in response to fitness accrual rate manipulation

Floral longevity, the time between corolla expansion and senescence, contributes directly and indirectly to a plant's overall fitness. Though mating opportunities for insect-pollinated species often differ among populations, few empirical studies have addressed whether floral longevity varies in a manner consistent with these differences. I conducted experiments at thermally distinct sites to examine whether the prevailing floral longevity model predicted such variation between a montane and an alpine population of Campanula rotundifolia. Staminate phase duration was significantly shorter for montane vs. alpine C. rotundifolia flowers in the presence of pollinators, but significantly longer when pollinators were excluded. Montane flowers had a significantly higher female fitness accrual rate, significantly shorter total longevities, and, unlike alpine flowers, were not pollen-limited. Delaying pollinator access to pistillate phase flowers significantly increased total longevity in alpine flowers only. Significant differences in total longevity between populations resulted from an extended pistillate phase in alpine flowers. Overall, the prevailing model accurately predicted the total floral longevity trends found here. However, I provide novel evidence for geographic and gender-specific plasticity in the floral longevity response to fitness accrual rate variation, suggesting C. rotundifolia populations in this study may be attuned to local schedules of pollinator activity.     

Change of floral orientation affects pollinator diversity and their relative importance in an alpine plant with generalized pollination system,Geranium refractum (Geraniaceae)

Floral orientation may affect pollinator attraction and pollination effectiveness, and its influences may differ among pollinator species. We, therefore, hypothesized that, for plant species with a generalized pollination system, changes in floral orientation would affect the composition of pollinators and their relative contribution to pollination. Geranium refractum, an alpine plant with downward floral orientation was used in this study. We created upward-facing flowers by altering the flower angle. We compared the pollinator diversity, pollination effectiveness, and pollinator importance, as well as female reproductive success between flowers with downward- and upward-facing orientation. Results indicated that the upward-facing flowers were visited by a wider spectrum of pollinators (classified into functional groups), with higher pollinator diversity than natural flowers. Moreover, due to influences on visitation number and pollen removal, the pollinator importance exhibited by the main pollinator groups differed between flower types. Compared with natural flowers, the pollination contribution of principal pollinators (i.e., bumblebees) decreased in upward-facing flowers and other infrequent pollinators, such as solitary bees and muscoid flies, removed more pollen. Consequently, stigmatic pollen loads were lower in upward- than in downward-facing flowers. These findings reveal that floral orientation may affect the level of generalization of a pollination system and the relative importance of diverse pollinators. In this species, the natural downward-facing floral orientation may increase pollen transfer by effective pollinators and reduce interference by inferior pollinators.     

Floral closure in response to temperature and pollination in Gentiana straminea Maxim. (Gentianaceae), an alpine perennial in the Qinghai-Tibetan Plateau

Floral closure may be induced by pollination and various other factors, but is rarely studied comprehensively. Different kinds of floral closure should have various effects on reproductive fitness of plants. Two contrasting types of floral closure were observed in the flowers of Gentiana straminea Maxim. in the eastern Qinghai-Tibetan Plateau. The first type occurred prior to pollination during both gender phases, in response mainly to decreasing air temperatures. Flowers closed when decreasing temperatures approached 20°C and subsequently began to reopen the following day during mid-morning when air temperatures warmed to approximately 13–15 °C. This kind of floral closure can protect pollen grains on either stamens or stigmas, increasing fitness of both male and female. Following pollination, permanent floral closure occurred, although there was a delay between the dates of pollination and permanent closure, during which flowers continued to show temporary closure in response to low temperature episodes. The time required for permanent, pollination-induced closure varied according to the age of the gender phase, including a prolonged time before closure if pollination occurred early in the female phase. The retaining of permanent closed flowers increased both approaching (to inflorescences) and visiting (to unpollinated flowers) frequencies of individual plants when with fewer open flowers and the persisting corolla is further beneficial for seed sets of these pollinated flowers. Thus, two separate types of floral closure, one in response to environmental cues and the other in response to the age of each gender stage, appeared to have a strong influence on reproductive fitness in this species. These results revealed a different adaptive strategy of alpine plants in the sexual reproduction assurance in addition to the well-known elevated floral longevity, dominant role of more effective pollinators and increased reproduction allocation in the arid habitats.     

Generalized and complementary pollination system in the Andean cactus Echinopsis schickendantzii

The considerable floral diversity present in the cactus family has often been associated with the specificity of its pollinators. However, many cactus pollination systems are generalized as their flowers are pollinated by a wide spectrum of animals. For example, cactus species with white flowers, nocturnal anthesis and extended floral cycles would present generalized pollination systems in which both nocturnal and diurnal visitors could be effective pollinators. In this article, we tested this hypothesis by studying the pollination biology of Echinopsis schickendantzii, an Andean cactus with sphingophilous flowers. In addition, we evaluated whether the cactus’s pollination system is complementary or redundant regarding the relative contributions of nocturnal and diurnal pollinators. Specifically, we studied the floral cycle, the reproductive system and the pollination effectiveness of floral visitors. The flowers of E. schickendantzii are self-incompatible; they opened at crepuscule and have an extended floral cycle. Moths were frequent visitors at night, whereas bees were frequent visitors during the day; both were effective pollinators of the cactus. Our results indicated that the flowers of this species present phenotypic, functional and ecological generalization, and their fruit set is determined by the contributions of both pollinator functional groups, i.e., they have complementary pollination systems. These results support the hypothesis that cacti in the extra-tropical deserts of South America have generalized pollination systems.     

兰科植物欺骗性传粉

植物与传粉动物的互利关系在生态系统中非常普遍。然而,有许多植物不为传粉者提供任何报酬,而是利用各种欺骗方式诱骗昆虫拜访,从而实现传粉,即欺骗性传粉。兰科是被子植物大科之一,其高度特化的繁殖器官和适应于昆虫传粉的精巧结构令人称奇。进化论创始人达尔文描述了许多兰花与昆虫精巧的传粉系统,但他忽视了欺骗性传粉的存在。事实上,近1/3的兰科植物都依赖于欺骗性传粉。欺骗性传粉可能是导致兰科植物多样性的重要原因之一。兰花利用或操作昆虫觅食、交配、产卵和栖息等行为,演化出各种各样的欺骗性传粉机制,常见的类型包括泛化的食源性欺骗、Batesian拟态、性欺骗、产卵地拟态和栖息地拟态。花的颜色、形态和气味在欺骗性传粉的成功实现中起到了重要作用。欺骗性兰花与传粉昆虫之间的演化可能是不同步的,兰花追踪昆虫的行为信号而发生分化,然而欺骗性传粉可能对昆虫造成一定的伤害,从而对昆虫也施加选择压力。由于昆虫的学习行为,欺骗性的兰花一般具有低的昆虫拜访率和结实率,其繁殖成功率受各种因素的影响。欺骗性加剧了兰花对传粉昆虫的依赖,使其具有更高的灭绝风险,传粉生物学的研究能为兰科植物的有效保护提供指导。在欺骗性传粉系统中,有报酬的伴生植物、拟态模型和其他拟态信号提供者对传粉成功有重要影响。因此,研究欺骗性传粉兰花、传粉昆虫和相关的生物和生态因子的网状进化关系具有重要理论和实践意义。     

Pollinators and nectar robbers cause directional selection for large spur circle in Impatiens oxyanthera (Balsaminaceae)

Nectar spurs have an important role in floral evolution and plant–pollinator coadaptation. The flowers of some species possess spurs curving into a circle. However, it is unclear whether spur circle diameter is under direct selection pressure from different sources, such as pollinators and nectar robbers. In this study, we quantified selection on some floral traits, such as spur circle diameter in Impatiens oxyanthera (Balsaminaceae) using phenotypic selection analysis and compared the relative importance of pollinators and nectar robbers as selective agents using mediation analysis. The study showed that pollinators caused significant selection on corolla length, spur curvature and spur circle diameter while nectar robbers only imposed strong selection on spur circle diameter. Pollinators favored flowers with large corolla, curly spurs and large spur circle while nectar robbers preferred flowers with small spur circle. More pollinator visits resulted in higher female reproductive success, while robbery reduced female fitness. Conflicting selection on spur traits from pollinators and nectar robbers was not found. Mediation analysis showed that selection on floral traits through nectar robbing was stronger than selection through pollination. The results suggested that pollinators and nectar robbers jointly mediated the directional selection for large spur circle, and nectar robbers caused stronger selection than pollinators on floral traits.     

腐生植物无叶美冠兰食源性欺骗传粉研究

无叶美冠兰是一种典型的腐生兰科植物,为揭示该物种的自然传粉机制,拓展对兰科植物生殖特性的认识,在广西雅长兰科植物国家级自然保护区对其开展了传粉生态学观测研究。结果表明:无叶美冠兰花朵具备高度自交亲和能力,但不存在自动自花授粉机制,必须依赖外部传粉媒介把花粉送到柱头,实现有效传粉;绿彩带蜂是无叶美冠兰唯一有效传粉昆虫;传粉昆虫与花朵在与传粉功能相关的关键性状在形态上良好拟合;绿彩带蜂的访花活动主要发生在3个阶段:8.6%发生在9:00~11:30,80.2%发生在11:30~14:00,11.2%发生在14:00~15:30;花朵在中午强烈的阳光直射下挥发出香甜的气味。无叶美冠兰花朵主要通过挥发极具诱惑力的香甜气味和唇瓣上黄色的蜜导来诱导绿彩带蜂进入花朵中觅食,传粉昆虫与花朵在与传粉功能相关的关键性状在形态上良好拟合促成有效传粉,绿彩带蜂在整个传粉过程没有获得报酬,是食源性欺骗传粉机制。     

Pollination of Schisandra henryi (Schisandraceae) by female, pollen-eating Megommata species (Cecidomyiidae, Diptera) in south-central China

BACKGROUND AND AIMS: The mutualistic interaction between insects and flowers is considered to be a major factor in the early evolution of flowering plants. The Schisandraceae were, until now, the only family in the ANITA group lacking information on pollination biology in natural ecosystems. Thus, the objective of this research was to document the pollination biology and breeding system of Schisandra henryi. METHODS: Field observations were conducted in three populations of S. henryi and the floral phenology, floral characters and insect activities were recorded. Floral fragrances were sampled in the field and analysed using TCT-GC-MS. Floral thermogenesis was measured with a TR-71U Thermo Recorder. Pollen loads and location of pollen grains on insect bodies (including the gut) were checked with a scanning electron microscope and under a light microscope. KEY RESULTS: Schisandra henryi is strictly dioecious. Male flowers are similar to female flowers in colour, shape, and size, but more abundant than female flowers. The distance between tepals and the androecium or gynoecium is narrow. Neither male nor female flowers are fragrant or thermogenic. Schisandra henryi is pollinated only by adult female Megommata sp. (Cecidomyiidae, Diptera) that eat the pollen grains as extra nutrition for ovary maturation and ovipositing. Both male and female flowers attract the pollinators using similar visual cues and thus the female flowers use deceit as they offer no food. CONCLUSIONS: Schisandra henryi exhibits a specialized pollination system, which differs from the generalized pollination system documented in other ANITA members. Pollen is the sole food resource for Megommata sp. and the female flowers of S. henryi attract pollinators by deceit. This is the first report of predacious gall midges utilizing pollen grains as a food source. The lack of floral thermogenesis and floral odours further enforces the visual cues by reducing attractants for other potential pollinators.     

Three pollination guilds and variation in floral characteristics of Bornean gingers (Zingiberaceae and Costaceae)

The pollinators of 29 ginger species representing 11 genera in relation to certain floral morphological characteristics in a mixed-dipterocarp forest in Borneo were investigated. Among the 29 species studied, eight were pollinated by spiderhunters (Nectariniidae), 11 by medium-sized Amegilla bees (Anthophoridae), and ten by small halictid bees. These pollination guilds found in gingers in Sarawak are comparable to the pollination guilds of neotropical Zingiberales, i.e., hummingbird-, and euglossine-bee-pollinated guilds. Canonical discriminant analysis revealed that there were significant correlations between floral morphology and pollination guilds and suggests the importance of plant–pollinator interactions in the evolution of floral morphology. Most species in the three guilds were separated on the plot by the first and second canonical variables. Spiderhunter-pollinated flowers had longer floral tubes, while Amegilla-pollinated flowers had wider lips than the others, which function as a platform for the pollinators. Pistils and stamens of halictid-pollinated flowers were smaller than the others. The fact that gingers with diverse morphologies in a forest with high species diversity were grouped into only three pollination guilds and that the pollinators themselves showed low species diversity suggests that many species of rare understory plants have evolved without segregating pollinators in each pollination guild.     

Mecardonia tenella (Plantaginaceae) Attracts Oil-, Perfume-, and Pollen-Gathering Bees in Southern Brazil

Floral characteristics often indicate the pollinators' functional group visiting the plant and the pollination syndromes associated with them. This idea has been challenged in the past decades due to increasing evidence that most plants, including those exhibiting floral syndromes, are visited by large arrays of species that differ in their effectiveness as pollinators. Our study focuses on Mecardonia tenella (Plantaginaceae) from the Araucaria forest of southern Brazil, which exhibits characteristics of the oil flower pollination syndrome. However, it is visited by three types of functional groups of bees: male orchid bees, oil-collecting bees, and pollen-seeking bees. The relative contribution of each functional group to the plant's reproductive success was estimated based on their pollen load, visitation frequency, and morphology. We assessed resources, phenology, and breeding system of M. tenella . Our results indicate that flowers lack nectar, but volatiles, lipids, and pollen are resources that can be gathered by visitors. This combination of floral traits and visitors' assemblage makes M. tenella a challenge to the concept of pollination syndromes. Our findings indicate that the current interactions may not reflect the circumstances under which some floral traits of this plant were selected.     

Specialized pollination in the African milkweed Xysmalobium orbiculare: a key role for floral scent in the attraction of spider-hunting wasps

Specialized pollination by prey-hunting wasps is poorly documented in rewarding plants. Furthermore, the mechanisms of achieving specialization are not clear since flowers typically produce exposed nectar and have no morphological adaptations (such as long spurs) to exclude non-pollinating visitors. We investigated the pollination of Xysmalobium orbiculare and explored the functional roles of floral scent and nectar in attracting pollinators and deterring nectar robbers. Floral visitor observations showed that this milkweed is visited almost exclusively by pompilid wasps in the genus Hemipepsis. These wasps were the only insects to carry pollinia, and a cage experiment confirmed their effectiveness in removing and inserting pollinia on flowers. Hand-pollinations showed that plants are genetically self-incompatible and thus reliant on pollinators for seed set. Palatability experiments with honeybees showed that nectar is distasteful to non-pollinating insects and is therefore likely to play a functional role in deterring nectar thieves. Choice experiments in the field showed that the wasp pollinators are attracted primarily by floral scent rather than visual cues. Analysis of spectral reflectance of flowers revealed that flowers are dull colored and are unlikely to stand out from the background vegetation. We conclude that X. orbiculare is specialized for pollination by spider-hunting wasps in the genus Hemipepsis and utilizes floral scent to selectively attract its pollinators and unpalatable nectar to deter non-pollinating visitors.     

Are pollinators the agents of selection on flower colour and size in irises?

Plant–pollinator interactions are believed to play a major role in the evolution of floral traits. Flower colour and flower size are important for attracting pollinators, directly influencing reproduction, and thus expected to be under pollinator‐mediated selection. Pollinator‐mediated selection is also proposed to play a role in maintaining flower colour polymorphism within populations. However, pigment concentrations, and thus flower colour, are also under selective pressures independent of pollinators. We quantified phenotypic pollinator‐mediated selection on flower colour and size in two colour polymorphic Iris species. Using female fitness, we estimated phenotypic selection on flower colour and size, and tested for pollinator‐mediated selection by comparing selection gradients between flowers open to natural pollination and supplementary pollinated flowers. In both species, we found evidence for pollen limitation, which set the base for pollinator‐mediated selection. In the colour dimorphic Iris lutescens, while pigment concentration and flower size were found to be under selection, this was independent of pollinators. For the polymorphic Iris pumila, pigment concentration is under selective pressure by pollinators, but only for one colour morph. Our results suggest that pollinators are not the main agents of selection on floral traits in these irises, as opposed to the accepted paradigm on floral evolution. This study provides an opposing example to the largely‐accepted theory that pollinators are the major agent of selection on floral traits.     

Change in floral orientation in Anisodus luridus (Solanaceae) protects pollen grains and facilitates development of fertilized ovules

? Premise of the study: Some floral traits could be selected by pollinators and nonpollinator agents, and studying the floral traits shaped by physical agents could reveal adaptive mechanisms to the environment. We explored the adaptive significance of the change in floral orientation, from pendulous flowers to erect fruits that have a persistent calyx, in Anisodus luridus, a perennial native to the Qinghai-Tibet Plateau (QTP). ? Methods: We examined the effect of flower orientation on pollinator visitation rates, pollen deposition efficiency, pollen quantity, and pollen viability to estimate whether pendulous flowers have improved male fitness. We then measured seed production and seed germination rate to assess whether erect fruits have enhanced female fitness. ? Key results: Pendulous flowers did not have any preferred pollinators or increased pollen deposition. In artificially erected flowers, the number of pollen grains greatly decreased after rainwash. Pollen germination experiments indicated that pollen damage by water and exposure to solar radiation is serious. In the persistent calyx that holds water within it, the temperature inside the calyx changed slower than in the calyx that had the water removed. After supplemental pollination, the seed number, seed set, and seed mass of fruits that had water removed from the calyx were reduced greatly in both years. ? Conclusions: We conclude that the change in floral orientation could enhance male and female fitness of A. luridus and is effectively adaptive to the alpine environments, indicating a strong selection by the combined pressure from various abiotic nonpollinator agents in shaping the floral traits of this alpine plant.     

Reproductive biology of Echinopsis terscheckii (Cactaceae): the role of nocturnal and diurnal pollinators

The aim of this study was to analyse the reproductive biology of Echinopsis terscheckii, a species endemic to northwest Argentina that has nocturnal flowers. We expected that this species had a generalised pollination system, with moths and diurnal visitors as the primary pollinators. To test this, we studied the floral biology, breeding system and floral visitors of this species and the effectiveness of nocturnal and diurnal visitors. Floral biology was defined based on floral morphology, floral cycle and nectar production of the flowers. The breeding system and relative contributions of diurnal and nocturnal visitors to fruit and seed set were analysed through field experiments. E.?terscheckii flowers opened at sunset and closed the following day. The peak of nectar production occurred at midnight. Flowers were determined to be self-incompatible. Moths, bees and birds were identified as floral visitors. Moths were the most frequent visitors at night, whereas bees were the most frequent visitors during the day. Fruit production by diurnal pollinators was less than that by nocturnal pollinators; among all floral visitors, moths were the most effective pollinators. We have demonstrated for the first time that moths are the primary pollinators of columnar cacti of the genus Echinopsis. Our results suggest that moths might be important pollinators of columnar cactus species with nocturnal flowers in the extra-tropical deserts of South America.     

Effects of low-efficiency pollinators on plant fitness and floral trait evolution in <Emphasis Type="Italic">Campanula americana</Emphasis> (Campanulaceae)

Floral visitors vary in their pollination efficiency and their preferences for floral traits. If low-efficiency pollinators decrease the amount of pollen available to higher efficiency visitors, then low-efficiency visitors may actually have negative fitness consequences for the plants that they visit. We used experimental arrays in two populations to determine the floral preferences and the fitness effects of low-efficiency (or ugly) pollinators on Campanula americana. These ugly pollinators (halictid bees) preferentially visited flowers with pollen over flowers that had had their pollen removed. C. americana pollen color varies quantitatively from light tan to dark purple, and we found that natural variation in pollen color influenced the magnitude of halictid preferences for flowers with pollen. In general, preferences for flowers with pollen were stronger when the ugly pollinators foraged in arrays of flowers with tan-colored pollen than in arrays with purple-colored pollen. When plants received few visits by efficient Bombus pollinators, visits by ugly pollinators significantly decreased siring success relative to plants where visits by ugly pollinators were prevented. In contrast, ugly pollinators did not influence siring success when higher efficiency pollinators were more abundant. Thus, the relationship between low-efficiency pollinators and the plants that they visit varies from commensalistic to antagonistic depending on the presence of other pollinators in the community. Our findings suggest that the negative fitness effects and floral preferences of low-efficiency or ugly pollinators may contribute to the maintenance of a pollen color polymorphism in C. americana.     

Reproductive biology of two Himalayan alpine gingers (Roscoea spp., Zingiberaceae) in China: pollination syndrome and compensatory floral mechanisms

According to the concept of pollination syndromes, floral traits reflect specialisation to a particular pollinator or set of pollinators. However, the reproductive biology of endemic, and often specialised, plants may require increased attention as climate change accelerates worldwide. Species of Roscoea endemic to the Himalayan region have striking orchid-like flowers with long corolla tubes, suggesting pollination by long-tongued insects. Until now, the reproductive biology of species of Roscoea has been poorly documented. We investigated the floral biology, breeding system and pollination ecology of R. cautleoides and R. humeana, from Hengduan Mountains, a global biodiversity hotspot in southwest China. We also tested whether floral longevity increases pollination success. Pollination experiments showed that the two species were self-compatible and depended on insects for fruit production. Over several flowering seasons we did not observe any potential pollinators with long tongues that matched the corolla tube visiting flowers in centres of distribution. The principal pollinators observed were pollen-collecting generalist bees, with low visitation frequencies. In general, members of the ginger family are characterised by short-lived (usually 1 day) flowers, but flowers of R. cautleoides and R. humeana last 8 and 6 days, respectively. Removing stigmas decreased fruit set in both study populations. Our results suggest that the original pollinators may have been long-tongued insects that are now absent from the Chinese Himalayas because habitats have responded to climate change. However, long-lived and self-compatible flowers, coupled with the presence of generalist pollinators, are traits that have allowed these gingers to reproduce and continue to persist in the alpine habitats.     

贠建全:广东荷包岛维管束植物名录

以分布于秦岭的金花忍冬（Lonicera chrysantha Turcz.）、忍冬（L.japonica Thunb.）、葱皮忍冬（L.ferdinandii Franch.）和金银忍冬（L.maackii（Rupr.）Maxim.）为对象,通过定位观察、人工授粉实验、人为设置实验斑块的方法对忍冬属4种植物的开花生物学特性、繁育系统、花色变化现象、传粉过程进行了研究。结果表明,4种植物的单花花期、花部特征存在差异。人工授粉实验显示,4种植物均存在一定的花粉限制,自交不亲和。除葱皮忍冬外,其余3种植物随着花色由白变黄,花粉和花蜜报酬减少、雌雄生殖能力逐渐降低;葱皮忍冬花变色后花蜜量变化不显著,且仍保留较强的雌性生殖能力。变色花的保留被认为是植物的一种生殖策略,通过增大植物的花展示来扩大自身的吸引力,以吸引更多远距传粉者访花。人为控制白、黄花不同数量比的实验结果表明,大多数传粉者偏向访问白花（变色前的花）,且白花提供的报酬量和黄花（变色后的花）数量显著影响传粉者的访花频率,即当花蜜量减少或黄花数量增多时,传粉者访花频率随之降低。因此,我们认为忍冬属4种植物的花色变化可能除了增大植物对远距传粉者的吸引力外,对近距传粉者的访花行为也可能具有一定的影响。当传粉者接近植株时,变色后的花可能暗示其花蜜（花粉）报酬已经发生变化,并驱使昆虫离开并飞向同株或异株植物新开放的报酬丰富的白花,这既有利于提高传粉者的觅食效率,又能降低植物同株异花授粉的几率,对忍冬属植物及传粉者都具有重要意义,是植物长期与授粉昆虫相互适应的反映。