黑果枸杞两种花型的花部综合征与传粉特性

黑果枸杞(Lycium ruthenicum)是中国西北地区极端环境中分布的国家二级保护植物, 该物种在新疆南部的自然种群中出现了同型花柱类型(同位花)和柱头探出式雌雄异位类型(异位花)个体, 并且遭遇沙尘暴频繁的种群中异位花个体出现频率减少。该研究对喀什市自然种群中黑果枸杞两种不同花型植株的花部综合征和传粉特性进行比较研究, 以期探讨该物种不同花型植株在南疆早春极端环境中的花部特征的可塑性及其适应性机制。结果表明: 同位花雌雄蕊高度间无显著差异, 而异位花雌蕊高度显著高于雄蕊; 同位花花冠直径、花冠筒长、胚珠数均高于异位花, 而异位花雌雄蕊空间距离、花粉数及花粉胚珠比均比同位花高。黑果枸杞同位花个体比例(68%)高于异位花个体(32%), 种群水平及个体水平同位花花期((117.00 ± 2.25) d, (101.65 ± 1.98) d)比异位花((26.00 ± 1.00) d, (18.75 ± 1.00) d)长, 而单花水平上异位花单花寿命((4.50 ± 0.14) d)比同位花((3.13 ± 0.11) d)长。两种类型花在花早期(紫色)分泌的花蜜量均高于花后期(白色)。在紫色花阶段(花开放早期), 同位花上的主要传粉者意大利蜜蜂、熊蜂和食蚜蝇的访花频率和停留时间均高于异位花; 而白色花阶段(花开放后期)意大利蜜蜂、熊蜂在异位花上的访花频率比同位花高。在不同花色阶段, 同位花柱头花粉落置数、花粉移出率、花粉传递效率均比异位花高, 并且同位花自然坐果率及结籽率均比异位花高。在新疆南部的沙尘暴极端环境下, 同位花通过较高的自交亲和性保障繁殖, 而异交为主的异位花提高了异交率。异位花与同位花在花部综合征和花报酬上的差异, 是影响其繁殖成功的主要因素。     

Comparative micromorphology of nectariferous and nectarless labellar spurs in selected clades of subtribe Orchidinae (Orchidaceae)

Floral nectar spurs are widely considered to influence pollinator behaviour in orchids. Spurs of 21 orchid species selected from within four molecularly circumscribed clades of subtribe Orchidinae (based on Platanthera s.l., Gymnadenia–Dactylorhiza s.l., Anacamptis s.l., Orchis s.s.) were examined under light and scanning electron microscopes in order to estimate correlations between nectar production (categorized as absent, trace, reservoir), interior epidermal papillae (categorized as absent, short, medium, long) and epidermal cell striations (categorized as apparently absent, weak, moderate, strong). Closely related congeneric species scored similarly, but more divergent species showed less evidence of phylogenetic constraints. Nectar secretion was negatively correlated with striations and positively correlated with papillae, which were especially frequent and large in species producing substantial reservoirs of nectar. We speculate that the primary function of the papillae is conserving energy through nectar resorption and explain the presence of large papillae in a minority of deceit‐pollinated species by arguing that the papillae improve pollination because they are a tactile expectation of pollinating insects. In contrast, the prominence of striations may be a ‘spandrel’, simply reflecting the thickness of the overlying cuticle. Developmentally, the spur is an invagination of the labellum; it is primarily vascularized by a single ‘U’‐shaped primary strand, with smaller strands present in some species. Several suggestions are made for developing further, more targeted research programmes. © 2009 The Linnean Society of London, Botanical Journal of the Linnean Society, 2009, 160 , 369–387     

Pollination ecology and pollination system of Impatiens reptans (Balsaminaceae) endemic to China

BACKGROUND AND AIMS: China is one of the centres of geographical distribution of Impatiens L. Studies of the pollination ecology of this genus in China have, until now, been unreported. Impatiens reptans, a species endemic to China, was studied. The aims were to examine the pollination ecology and pollination system of this species, to compare its pollination ecology with other Impatiens species growing in Sumatra and Japan, and to discuss possible reasons for its limited distribution. METHODS: The pollination ecology of I. reptans was studied by carrying out continuous observations within three naturally growing populations. Its pollination system was studied using different pollination methods, marking and counting pollen grains, assessing pollen viability and observing pollinator behaviour. KEY RESULTS: The flowering phase of the protandrous I. reptans lasted for 89 d. The life span of an individual flower was 3.6 d. Primary pollinators were honey-bees and bumble-bees. Secondary pollinators were diurnal hawk moths and butterflies. Bombus briviceps and Bombus sp. were nectar gatherers. The mean nectar sugar concentration was 29.5 %, and the mean value of sucrose/glucose + fructose was 0.82. The proportion of seed set ranged from 0.857 to 0.873. Distances that seeds were ejected ranged from 0.58 to 1.17 m. Percentage seed germination under controlled conditions was 23.1. Pollen viability was highest on the day of anthesis and thereafter decreased. Ratios of pollen : ovules ranged from 958.8 to 970.6. CONCLUSIONS: Impatiens reptans reproduces by means of cross-pollination. Its dependence on a specialized habitat, a narrow environmental niche, a low percentage of seed germination, and habitat loss could be reasons for its limited distribution and endemism.     

Roles of pollination and short-chain saturated fatty acids in flower senescence

Pollination induced an immediate increase in ethylene production in Dianthus caryophyllus and Petunia hybrida. In Cymbidium, a lag of several hours was observed. In all three species, pollination induced premature flower senescence. Treatment of the stigmatic surface with aminoethoxyvinylglycine prior to pollination effectively blocked the increase in ethylene production and alleviated the detrimental effect of pollination on flower life.In all three tested species, octanoic and decanoic acids, when applied to the stigmatic surface, had no effect on ethylene production and flower life. In isolated Cymbidium lips placed with their cut base in solutions containing these fatty acids, no effects on red colouration, ethylene production, and ethylene forming enzyme activity were observed. In addition, ethylene sensitivity of isolated lips was not affected. The putative regulatory role of short-chain saturated fatty acids in (pollination-induced) flower senescence is discussed.     

The importance of monkey beetle (Scarabaeidae: Hopliini) pollination for Aizoaceae and Asteraceae in grazed and ungrazed areas at Paulshoek, Succulent Karoo, South Africa

The relative importance of monkey beetles (Hopliini, Scarabeidae) as pollinators of Asteraceae and Aizoaceae in the Succulent Karoo as well as the influence of livestock grazing on their abundance and diversity was investigated. Hopliine beetles proved to be the, or among the, most abundant flower visitors of 12 investigated plant species. However, during single flower observations at three Aizoaceae species, bees (Apoidea), bee flies (Bombyliidae) and pollen wasps (Masaridae) were the most frequent flower visitors. However, monkey beetles carried the highest Asteraceae and Aizoaceae pollen loads, and are therefore considered to play a vital role in the pollination of these two families. Abundance, species richness and diversity of Hopliini did not appear to be heavily affected by livestock grazing. Annual variation in the composition of monkey beetle populations was more dramatic. Still, some species showed higher abundances on heavily grazed rangeland while others only occurred under low grazing pressure. It is presumed that changes in the composition of the vegetation, especially the observed decrease of perennial plants in favour of annuals and geophytes (Todd and Hoffman 1999) could in turn affect the composition of monkey beetle assemblages.     

Ricochet pollination in Senna (Fabaceae) – petals deflect pollen jets and promote division of labour among flower structures

• Naturalists Fritz and Hermann Müller hypothesised that heteranthery often leads to a division of labour into ‘feeding’ and ‘pollinating’ stamens; the latter often being as long as the pistil so as to promote successful pollination on the bees’ back. In many buzz‐pollinated species of Senna, however, the so‐called pollinating stamens are short and not level with the stigma, raising the question of how pollen is shed on the bees’ back. Here we explore a mechanism called ‘ricochet pollination’. We test whether division of labour is achieved through the interaction between short lower stamens and strongly concave ‘deflector petals’.
• We studied the arrangement and morphology of the floral organs involved in the ricochet pollination, functioning of the flowers through artificial sonication and observed the interactions between bees and flowers in the field.
• The middle stamens are adapted to eject pollen downwards, which can be readily collected on the bee mid legs. Most of the pollen is ejected towards the deflector petal(s). Pollen from this set of stamens is more likely to contribute to pollination. The pollen grains seem to ricochet multiple times against the deflector petals to eventually reach the bee's back.
• The pollen ricochet mechanism promotes a division of labour by involving additional floral organs, such as petals, reinforcing the Müllers’ division‐of‐labour hypothesis. However, alternative, non‐multiexclusive hypotheses could be explored in genus Senna and other angiosperm species.

     

The population ecology of male gametophytes: the link between pollination and seed production

The fate of male gametophytes after pollen reaches stigmas links pollination to ovule fertilisation, governing subsequent siring success and seed production. Although male gametophyte performance primarily involves cellular processes, an ecological analogy may expose insights into the nature and implications of male gametophyte success. We elaborate this analogy theoretically and present empirical examples that illustrate associated insights. Specifically, we consider pollen loads on stigmas as localised populations subject to density‐independent mortality and density‐dependent processes as they traverse complex stylar environments. Different combinations of the timing of pollen‐tube access to limiting stylar resources (simultaneous or sequential), the tube distribution among resources (repulsed or random) and the timing of density‐independent mortality relative to competition (before or after) create signature relations of mean pollen‐tube success and its variation among pistils to pollen receipt. Using novel nonlinear regression analyses (two‐moment regression), we illustrate contrasting relations for two species, demonstrating that variety in these relations is a feature of reproductive diversity among angiosperms, rather than merely a theoretical curiosity. Thus, the details of male gametophyte ecology should shape sporophyte reproductive success and hence the dynamics and structure of angiosperm populations.     

Hydrophilous pollination and breeding system evolution in seagrasses: a phylogenetic approach to the evolutionary ecology of the Cymodoceaceae

COX, P. A. & HUMPHRIES, C. J. 1992. Hydrophilous pollination and breeding system evolution in seagrasses: a phylogenetic approach to the evolutionary ecology of the Cymodoceaceae. A phylogenetic analysis of seagrasses of the Cymodoceaceae shows the Cymodoceaceae to be monophyletic and Posidoniaceae to be their sister group. Information on the pollination ecologies and breeding systems of the various genera of the Cymodoceaceae were plotted onto the consensus tree obtained for the group. From this analysis, it is suggested that the clade composed of the Zosteraceae, Posidoniaceae and Cymodoceaceae evolved from a freshwater hydrophilous ancestor that developed submarine pollination and filiform pollen in association with invasion of the marine environment. Dioecism and surface pollination appear to have evolved in the progenitor of the Cymodoceaceae, and hence the seagrasses of the Cymodoceaceae are dioecious due to common descent rather than to convergent evolutionary processes in extant genera.     

传粉细蛾与大戟科植物专性授粉的互惠共生体系

在已知的昆虫与植物所形成的专性授粉互惠共生体系中,榕树—榕小蜂、丝兰—丝兰蛾体系是经典实例,国内外学者已经从不同角度进行了大量的研究,为我们理解植物—传粉者互惠共生体系协同进化的机理和历史积累了宝贵的资料。近些年的研究发现鳞翅目细蛾科头细蛾属昆虫与大戟科植物之间也存在相似的协同进化关系。文章对国内外学者有关传粉细蛾与大戟科植物互惠共生协同进化的研究进行了整理。     

东南亚兰科植物的物种多样性、生活习性及其传粉系统（附表）

兰科(Orchidaceae)植物广布于除两极和极端沙漠地区外的各种陆地生态系统,包括5个亚科800多属28 000多种。东南亚地区兰科植物种数约占世界的1/3,是兰科植物生物多样性热点区域之一。通过查阅文献及书籍等资料,该文系统整理了东南亚兰科植物物种种类及其扩散演化历史,并对其生活习性和传粉系统进行了归类。结果表明:(1)东南亚兰科植物8 855种,分属5亚科17族26亚族240属;(2)主要生活型为附生的有127属6 000种以上,地生97属2 000种以上,腐生13属约100种,藤本4属40余种;(3)根据整理出的东南亚79个属的兰科植物传粉系统发现,有44个属含有自动自交的物种,具报酬物的传粉系统有花粉(仅见于拟兰亚科)、芳香类物质(仅见于香荚兰亚科)和花蜜(5个亚科均有)等报酬物类型。欺骗性传粉系统广泛存在于各个亚科,包括食源性欺骗、性拟态、繁殖地拟态和信息素拟态等类型。东南亚兰科植物在物种、生活习性及传粉系统都展现出极高的多样性,对这些生物学特点的总结将为兰科植物的保育提供一定的理论基础和本底资料。     

Floral biology and mechanisms of spontaneous self‐pollination in five neotropical species of Gentianaceae

Cross‐ and self‐fertilization in angiosperms are regulated by several factors, and a knowledge of the mechanism and time of spontaneous self‐pollination offers opportunities for a better understanding of the evolution of mating systems and floral traits. The floral biology of five species of Gentianaceae found in high‐altitude neotropical grassland is presented, with emphasis on the mechanisms that promote spontaneous self‐pollination. A presumed floral Batesian mimicry system is suggested between the rare and rewardless Zygostigma australe and Calydorea campestris, a species of Iridaceae with pollen‐flowers, pollinated by syrphids and bees. The floral morphology of the other four gentian species points to three different pollination syndromes: melittophily, phalaenophily and ornithophily. However, with the exception of the nocturnal Helia oblongifolia, flowers are nectarless and appear to exhibit non‐model deceptive mechanisms, providing similar floral cues to some sympatric rewarding species with the same syndrome. The similar mechanism of spontaneous self‐pollination in Calolisianthus pedunculatus, Calolisianthus pendulus and H. oblongifolia (Helieae) is based on the stigmatic movements towards the anthers. Selfing is promoted by movements of the style/stigma and of the corolla in Deianira nervosa and Z. australe (Chironieae), respectively. The movements of stamens, style and stigma during anthesis seem to be the most common method of spontaneous self‐pollination in angiosperms. It is suggested that the evolution of delayed spontaneous self‐pollination would be more expected in those taxa with dichogamous flowers associated with herkogamy. Such a characteristic is frequent in long‐lived flowers of certain groups of Asteridae, which comprise most documented cases of autonomous selfing. Thus, the presence of dichogamy associated with herkogamy (which supposedly evolved as a result of selection to promote both separation of male and female functions and the efficient transfer of cross pollen) may be the first step in the adaptive evolution of delayed selfing to provide reproductive assurance. © 2009 The Linnean Society of London, Botanical Journal of the Linnean Society, 2009, 160 , 357–368.     

Insect and wind pollination of an alpine biennial Aconitum gymnandrum (Ranunculaceae)

Wind pollination can provide reproductive insurance for animal‐pollinated dioecious plants in the absence of available pollinators, but combinations of insect and wind pollination (ambophily) have rarely been studied in hermaphrodite herbs. We examined the stable occurrence of insect pollination and wind pollination over 4 years in a population of a biennial Aconitum species (A. gymnandrum) with actinomorphic and degenerate sepals. The total frequency of visits of two bumblebee species showed no distinct fluctuations in the studied population among the 4 years. However, seed production of netted flowers after emasculation indicated wind pollination had occurred. The seed number of bagged flowers with one visit by bumblebees was significantly less than that of netted flowers after one visit, or in control flowers. Both seed number and fruit set of netted flowers were significantly lower than in control flowers. These results suggest that wind pollination provides supplementary pollen to unvisited and/or once‐visited flowers, but accounts for only a small amount of seed production compared to bumblebee pollination in natural conditions. Such a combination of insect and wind pollination might play an important role in maintaining sexual reproduction of this biennial herb, allowing it to persist in arid habitats on the Qinghai‐Tibetan Plateau, especially during Quaternary glacial periods when pollinator populations oscillated extensively.     

The effectiveness of flower strips and hedgerows on pest control,pollination services and crop yield: a quantitative synthesis

Floral plantings are promoted to foster ecological intensification of agriculture through provisioning of ecosystem services. However, a comprehensive assessment of the effectiveness of different floral plantings, their characteristics and consequences for crop yield is lacking. Here we quantified the impacts of flower strips and hedgerows on pest control (18 studies) and pollination services (17 studies) in adjacent crops in North America, Europe and New Zealand. Flower strips, but not hedgerows, enhanced pest control services in adjacent fields by 16% on average. However, effects on crop pollination and yield were more variable. Our synthesis identifies several important drivers of variability in effectiveness of plantings: pollination services declined exponentially with distance from plantings, and perennial and older flower strips with higher flowering plant diversity enhanced pollination more effectively. These findings provide promising pathways to optimise floral plantings to more effectively contribute to ecosystem service delivery and ecological intensification of agriculture in the future.     

Breeding system and thrips (Thysanoptera) pollination in the endangered tree Ocotea porosa (Lauraceae): implications for conservation

Ocotea porosa has been extensively exploited over the past few decades because of the quality of its wood. Today, populations are reduced and the species is now included in the Red List of threatened species by the International Union for Nature Conservation. For conservation and management purposes, it is extremely important that we understand its reproductive ecology. Floral morphology was described based on field and scanning electron microscopic examination. The reproductive system was determined through experimentally controlled pollination along with observations of pollen tube growth. Pollinators were identified through field observations. Flowers of O. porosa are small, shallow, inconspicuous, asynchronous and grouped in inflorescences. This species presented self‐compatibility, but did not reproduce through apomixy and spontaneous self‐pollination was very rare (5%). Despite being monoclinal, flowers were protogynic, and the gynoecium was receptive after the first day of anthesis when the anthers were closed. Spontaneous self‐pollination was avoided by the extrorse position of the anthers of the internal stamens. Frankliniella gardeniae (Thysanoptera) was the only pollinating species observed and, after visiting several asynchronous flowers in the same inflorescence, favors geitonogamy. Together the small distance supposedly achieved by thrips in flight and the small population density of O. porosa can reduce the chances of cross‐pollination in this species. If so, conservation measures must include preservation of the current population and possibly planting to increase population density. This would reduce the distance between individuals and increase genetic variability. Thrips as pollinators must be included in conservation planning for O. porosa.     

濒危植物丰都车前的繁育系统与传粉生物学研究

丰都车前为三峡库区特有珍稀濒危植物,目前仅在重庆市江津支坪镇涂家村附近大中坝上有一小种群分布。以野生种群和移栽种群为对象,通过野外观察和人工授粉实验对丰都车前传粉生物学及繁育系统进行研究。结果表明:(1)丰都车前单花花期约4 d,花序花期约8 d,种群花期约3个月;单花开花进程可分为6个时期:花蕾期、雌蕊伸长期、雄蕊初露期、花瓣展开期、花瓣反折期、枯萎凋谢期。(2)花瓣展开前,柱头先伸出花冠,达最高可受性,之后花瓣展开雄蕊才露出,而此时大部分柱头已枯萎失活丧失可受性,只有少部分具可受性。表现出雌雄异熟的特征,一定程度避免了自交的发生。(3)花粉活力始于雄蕊初露期,花瓣展开、花药开裂时花粉活力最高,至枯萎凋谢前均具有活力。花粉活力最高期避开了柱头可受性最佳期,仅有少部分重叠。(4)繁育系统检测显示,花粉/胚珠比为15373.29,杂交指数为3。结合套袋实验表明,丰都车前可能同时具有风媒和虫媒传粉机制,传粉昆虫为中华蜜蜂、食蚜蝇,但数量偏少,不存在无融合生殖,异交为主,部分自交亲和,有时需要传粉者。(5)开花时期避开了其分布地洪水淹没期,能够顺利完成开花授粉及座果。综上所述,丰都车前的花部特征、开花物候和繁育系统为适应分布地夏季洪水水淹胁迫提供了一定的生殖保障,促进了该种群的续存。     

Influence of flower functionality and pollination system on the pollen size-pistil length relationship

Twenty-five biotically pollinated plants of the Chaco Serrano Forest (Córdoba, Argentina) were studied in order to analyze whether ‘flower functionality’ is related to the relationship between pollen size and pistil length. Because flower functionality may act on the respective mean values of pollen size and pistil length rather than on intraspecific variation in these traits, we expected (1) a high positive correlation between pollen size and pistil length in a set of sympatric species, independent of their degree of pollination specialization or generalization; and (2) no interspecific correlation between the coefficients of variation (CVs) of those traits. On the other hand, on the assumption that pollinators are influencing the variation in floral traits (e.g. in pistil length) we expected lower mean phenotypic variation of pollen size and pistil length in pollination-specialist plants than in pollination-generalist ones. A positive correlation between pollen size and pistil length was found for the set of species, but not between the CVs of these traits. This trend was maintained when pollination-specialist plants were analyzed separately, but no statistical significance was obtained for the correlation in pollination-generalist plants. Contrary to our expectations, pollination-specialist plants did not show less mean intraspecific variation in floral traits than pollination-generalist plants. Therefore, the relationship between pollen size and pistil length among species suggests that the pollination system may be of less importance as a selective force than flower functionality.     

Comparison of pollination characteristics between the insular shrub Clerodendrum izuinsulare and its widespread congener C. trichotomum

Impact of pollinator shift on differentiation of floral morphology has attracted the interest of naturalists for many years. A comparative investigation was conducted for determining the pollination characteristics, including pollinator assemblage, floral morphology, flowering phenology, and self‐compatibility, of two closely related Clerodendrum species—insular C. izuinsulare and widespread C. trichotomum. Japanese black swallowtail butterflies were the predominant flower visitors in mainland Japan, whereas diurnal hawk moths were predominantly found on the Izu Islands, a chain of oceanic islands located off the southeastern coast of the main Japanese island of Honshu in the west Pacific Ocean. The corolla tube of C. izuinsulare was longer than that of C. trichotomum, whereas the filaments and petals of C. izuinsulare were shorter than those of C. trichotomum. The flowering season of C. izuinsulare was later than that of C. trichotomum. The self‐compatibility of C. izuinsulare was higher than that of C. trichotomum. These differences might be associated with the low density of Japanese black swallowtail butterflies and dominance of diurnal hawk moths on the Izu Islands.     

Evolutionary transition between bee pollination and hummingbird pollination in Salvia: Comparing means,variances and covariances of corolla traits

Covariation among traits can modify the evolutionary trajectory of complex structures. This process is thought to operate at a microevolutionary scale, but its long‐term effects remain controversial because trait covariation can itself evolve. Flower morphology, and particularly floral trait (co)variation, has been envisioned as the product of pollinator‐mediated selection. Available evidence suggests that major changes in pollinator assemblages may affect the joint expression of floral traits and their phenotypic integration. We expect species within a monophyletic lineage sharing the same pollinator type will show not only similarity in trait means but also similar phenotypic variance‐covariance structures. Here, we tested this expectation using eighteen Salvia species pollinated either by bees or by hummingbirds. Our findings indicated a nonsignificant multivariate phylogenetic signal and a decoupling between means and variance‐covariance phenotypic matrices of floral traits during the evolution to hummingbird pollination. Mean trait value analyses revealed significant differences between bee‐ and hummingbird‐pollinated Salvia species although fewer differences were detected in the covariance structure between groups. Variance‐covariance matrices were much more similar among bee‐ than hummingbird‐pollinated species. This pattern is consistent with the expectation that, unlike hummingbirds, bees physically manipulate the flower, presumably exerting stronger selection pressures favouring morphological convergence among species. Overall, we conclude that the evolution of hummingbird pollination proceeded through different independent transitions. Thus, although the evolution of hummingbird pollination led to a new phenotypic optimum, the process involved the diversification of the covariance structure.