The birds and the seeds: opportunistic avian nectarivores enhance reproduction in an endemic montane aloe

Opportunistic bird pollination has become more evident in studies that confirm distinct differences in floral adaptations that attract opportunistic, rather than specialist, bird pollinators. Pollination syndrome studies investigating the effectiveness of different pollinator guilds on reproduction seldom do so by measuring seed viability. We studied pollination in Aloe peglerae, a high altitude endemic succulent of the Magaliesberg mountain range, previously thought to be largely sunbird (specialist) pollinated. Using field observation and pollinator exclusion treatments, i.e. (i) open to all visitors, (ii) bird excluded, and (iii) all visitors excluded, we established that birds contributed significantly more to fruit (2.3–5.6 times) and seed (1.3–1.4 times) set than insect or self-pollination, respectively. Overall, pollination by opportunistic avian nectarivores amplified seed production per aloe ~7 and 10 times compared to insects and self-pollination, respectively. One of three opportunistic nectarivores, the Cape Rock-Thrush (Monticola rupestris), played a significant role in pollination, contributing ~60 % of all probes at inflorescences. The difference in reproductive output between insect visited and visitor excluded flowers was not significant and suggests possible self-pollination in A. peglerae which is particularly unusual in Aloe species. Breeding system experiments would help clarify this. In assessing the effectiveness of pollinator guild on seed viability, we found no differences in percentage seed viability, seed germination or seedling emergence between exclusion treatments. Seed viability and germination were low and variable; however, ~19 % seedling emergence was observed across the treatments. Practically, the net effect of bird pollination may result in 8–12 times more potential seedlings compared to insect and self-pollination respectively. These findings highlight the importance of pollination by opportunistic avian nectarivores in Aloe.     

Reproductive ecology of Aloe plicatilis,a fynbos tree aloe endemic to the Cape Winelands,South Africa

While the pollination ecology of many Aloe species is well-documented, knowledge on aloe seed ecology, and hence aloe reproductive ecology in its entirety is limited. The aim of this study was to investigate the reproductive ecology of Aloe plicatilis, a Cape fynbos tree aloe endemic to the Cape Winelands, South Africa. Results from a pollinator exclusion experiment conducted at an A. plicatilis population on Paarl mountain suggests pollination primarily by insects, although bird visitation significantly increased seed set/fruit indicating possible co-pollination with insects. The species' long-tubed flowers and production of concentrated nectar, with observations of malachite sunbirds as the most common avian visitors to A. plicatilis flowers indicate the importance of long-billed specialist avian nectarivores as floral visitors. Analysis of the relationship between plant size and inflorescence production for five populations combined revealed a significant, positive linear relationship between plant size and the logarithm of the number of inflorescences/plant. Natural fruit and seed set determined for three populations (1325, 27,930 and 251,616 seeds/population) suggests low reproductive output compared to several other Aloe species. The smallest (31 individuals) and least dense (75 plants/ha) A. plicatilis population produced the lowest seed set/plant (128 seeds) and per population (1325 seeds), suggesting an Allee effect. Evaluation of seed dispersal potential showed that potential dispersal distances were approximately three times the canopy height; however, the occurrence of A. plicatilis on mountains isolated from more continuous mountain ranges on which the species also occurs suggests the possibility of long-distance dispersal by strong, gusty, summer winds. Soil seed bank samples collected from 13 populations yielded close to zero seedling emergence, indicating the absence of persistent seed banks. A. plicatilis seeds stored under ambient laboratory conditions for 3, 18 and 24 months were germinated in an environmental control chamber and a laboratory. High percentage germination was recorded for 18- and 24-month-seed (86 and 80%, respectively), while germination of 3-month-old seeds was three times lower, suggesting the need for after-ripening. Germination of fresh and one-year-old seed under ambient nursery conditions at the Karoo Desert National Botanical Garden in Worcester yielded emergence percentages of 67 and 44%, respectively, and were therefore less successful than germination under more controlled conditions. This is the first known study to investigate the reproductive ecology of a tree aloe species and that of a Cape fynbos aloe. The study highlights the importance of further studies on aloe seed ecology, particularly for rare and threatened species.     

Thrips pollination of the dioecious ant plant Macaranga hullettii (Euphorbiaceae) in Southeast Asia

Discussion about thrips (Thysanoptera) as main pollinators has been controversial in the past because thrips do not fit the preconception of an effective pollinator. In this study, we present evidence for thrips pollination in the dioecious pioneer tree genus Macaranga (Euphorbiaceae). Macaranga hullettii is pollinated predominantly by one thrips species, Neoheegeria sp. (Phlaeothripidae, Thysanoptera). As a reward for pollinators, the protective floral bracteoles function as breeding sites for thrips and trichomal nectaries on the adaxial surface of the floral bracteoles provide alimentation. Flowering phenology of both staminate and pistillate trees was highly synchronized within 3-4 wk periods. In contrast to pistillate trees, staminate trees start to breed the thrips inside the developing inflorescences ～2 wk before anthesis. Breeding of Neoheegeria sp. in the laboratory indicates that the thrips development is completed within ～17 d. Thus, staminate trees offer breeding sites for one thrips generation until the onset of pollen presentation. Intraspecific pollen transfer by thrips was proved by pollen loads of thrips taken from receptive pistillate inflorescences of M. hullettii. Bagging experiments of different mesh sizes showed that seed set reached almost the level of open-pollinated flowers when exclusively tiny insects like thrips were able to enter the net bags, but no apomictic seed set occurred when no insect access was given to the flowers.     

Variations of floral traits among different life forms illustrate the evolution of pollination systems in Potamogeton species from China

Four leaf morpha groups (floating-leaved, submerged broad-leaved, submerged linear-leaved and filiform-leaved) and three inflorescences type groups (erect, facultative floating and floating) can be found in the genus Potamogeton. Life forms in the genus correlate with pollination types (anemophily, epihydrophily and hydroautogamy). Floral traits vary greatly among different life forms and pollination types. Both floating and submerged broad-leaved species produce erect inflorescences that are suited for anemophilous pollination. These flowers also have the highest pollen/ovule (P/O) ratio (25,013) and the smallest pollen grain volume (6046 μm³). On the contrary, submerged filiform-leaved species produce only floating inflorescences and their flowers produce the largest pollen grains (17,567 μm³) and have the lowest P/O ratio (6752), which is typical of the syndromes of hydroautogamy and epihydrophily. The relatively prolific seed production (about 70%) and wide dispersal in the floating and submerged broad-leaved species and the submerged filliform-leaved species indicate that these two groups are well adapted to the aquatic environment. This is in contrast with the less well-adapted complex and unstable pollination system found in linear-leaved species. We propose that the pollination systems and life forms in the Potamogeton, have undergone modification in response to the demands imposed by the aquatic environment during the evolutionary process in the genus.     

Self-incompatibility and pollen limitation in the rare tristylous endemic Hugonia serrata on La R��union Island

Surveys of the incompatibility status of island floras have shown a deficit in taxa possessing homomorphic or heteromorphic incompatibility. This observation provides strong evidence for Baker??s Rule (1967) in that self-incompatibility can impede these taxa of colonizing and establishing on islands. The woody liana Hugonia serrata Lam. (Linaceae) is an extremely rare plant species endemic to the Mascarene Islands of La Réunion and Mauritius in the southern Indian Ocean. Previous research has documented the existence of tristyly in this species, thereby raising the number of known tristylous families to six. However, data were based on a very small sampling size and currently no data on the self-incompatibility system of the species are available. In this study, we investigated in detail the breeding system of H. serrata. Calculation of reciprocity and precision indices based on measurements of reproductive organs in a much larger sample size confirmed tristyly in this species. This style?Cstamen polymorphism was accompanied by several ancillary polymorphisms in stigma size, stigma color, anther size and pollen size. The rigidity of the heteromorphic incompatibility system was tested using experimental hand-pollinations. Significantly fewer pollen tubes arrived at the ovary after self- and illegitimate pollination (7%) than after legitimate pollination (12%). Seed set after self-pollination (3.6%) was also much lower than after legitimate pollination (66.7%). Comparison of seed set after legitimate pollination with natural seed set showed evidence for outcross pollen limitation. Our results indicate that despite severe pollen limitation and limited mate availability the heteromorphic incompatibility system in H. serrata is still strict after colonization of La Réunion Island. Because H. serrata is extremely long-lived, these results suggest that establishment of heterostylous species on islands may have been favored by their long life span.     

Inbreeding Depression under Drought Stress in the Rare Endemic Echium wildpretii (Boraginaceae) on Tenerife,Canary Islands

How climate-change induced environmental stress may alter the effects of inbreeding in patchy populations of rare species is poorly understood. We investigated the fitness of progeny from experimental self- and cross-pollinations in eight populations of different size of Echium wildpretii, a rare endemic plant of the arid subalpine zone of the Canarian island of Tenerife. As control treatments we used open pollination and autonomous selfing. The seed set of open-pollinated flowers was 55% higher than that of autonomously selfed flowers, showing the importance of animal pollination for reproductive success. The seed set, seed mass and germination rate of seedlings of hand-selfed flowers was similar to that of hand-crossed flowers, indicating weak inbreeding depression (seed set –4.4%, seed mass –4.1%, germination –7.3%). Similarly, under normal watering there were no significant effects of inbreeding on seedling survival (–3.0%). However, under low watering of seedlings inbreeding depression was high (survival –50.2%). Seed set of open- and hand-outcrossed-pollinated flowers was higher in large than in small populations, possibly due to more frequent biparental inbreeding in the latter. However, later measures of progeny fitness were not significantly influenced by population size. We predict that increasing drought duration and frequency due to climate change and reductions of population sizes may increase inbreeding depression in this charismatic plant species and thus threaten its future survival in the longer term.     

The impacts of flowering phenology on the reproductive success of the narrow endemic Nouelia insignis Franch. (Asteraceae)

Nouelia insignis Franch. (Asteraceae) is a short, narrow endemic and endangered tree, growing with a natural population in the dry and hot valley of the Jinsha River in the southwest area of China. In this work, flowering phenology (time and duration), floral biology, visit frequency and behavior of pollinators, and pollination characteristics were studied based on investigation in the field and analysis in the laboratory with the help of a stereomicroscope, and the relationship between seed setting rate and reproductive traits, as well as the relationship between flowering time and rainfall before flowering, was tested using the method of general linear regression model. The results showed that natural population of N. insignis exhibited high flowering synchrony with relatively stable flowering duration, and the flowering time fluctuated greatly depending on the rainfall 5 months before flowering. The pollination of N. insignis required pollinators, and insect activities played a very important role in the pollination process. However, lack of the pollinators was not a limitation for reproductive fitness in N. insignis, although the number of pollinators was small and the frequency of visits was low. In addition, no pollen limitation was found during pollination. The average seed setting rate of N. insignis in the natural condition was only 1.52%–3.73%, and it was generally affected by changes in flowering phenology between years and had a higher seed set in early flowering year. The annual variation of seed set might be related to the annual variations of stamen and pistil functions, such as changes of pollen viability and stigma receptivity, which were closely related to flowering time. The results of this study are of value for further conservation actions on natural population of this threatened endemic plant.     

Spatial Scales of Pollen and Seed-Mediated Gene Flow in Tropical Rain Forest Trees

Gene flow via seed and pollen is a primary determinant of genetic and species diversity in plant communities at different spatial scales. This paper reviews studies of gene flow and population genetic structure in tropical rain forest trees and places them in ecological and biogeographic context. Although much pollination is among nearest neighbors, an increasing number of genetic studies report pollination ranging from 0.5–14 km for canopy tree species, resulting in extensive breeding areas in disturbed and undisturbed rain forest. Direct genetic measures of seed dispersal are still rare; however, studies of fine scale spatial genetic structure (SGS) indicate that the bulk of effective seed dispersal occurs at local scales, and we found no difference in SGS (Sp statistic) between temperate (N?=?24 species) and tropical forest trees (N?=?15). Our analysis did find significantly higher genetic differentiation in tropical trees (F _ST?=?0.177; N?=?42) than in temperate forest trees (F _ST?=?0.116; N?=?82). This may be due to the fact that tropical trees experience low but significant rates of self-fertilization and bi-parental inbreeding, whereas half of the temperate tree species in our survey are wind pollinated and are more strictly allogamous. Genetic drift may also be more pronounced in tropical trees due to the low population densities of most species.     

濒危植物焕镛木的兼性无融合生殖

2001～2002年连续两年在广西环江木论和广西罗城大黄泥的2个焕镛木(Woonyoungia septentrionalis(Dandy)Law)自然种群中,对单性异株的濒危植物焕镛木进行繁育系统测定,对即将开花的雌花花蕾分别进行套袋、套网、人工授粉处理,并用自然授粉雌花作对照,其座果率和结实率统计结果表明:自然授粉、人工授粉、套袋和套网处理的花均能结实,但它们的座果率和结实率存在较大的差异.在两个种群中,人工授粉和自然授粉的总结实率(PERS)均比套袋和套网处理的高,其中人工授粉的最高,套网处理的最低.由此可见,焕镛木既能通过有性生殖方式结实,又能通过无融合生殖方式结实,而且这两种生殖方式获得的种子均能萌发成幼苗,由此断定,焕镛木的繁育系统为兼性无融合生殖.这是首次报道木兰科植物存在无融合生殖现象.     

濒危植物焕镛木的兼性无融合生殖

2001—2002年连续两年在广西环江木论和广西罗城大黄泥的2个焕镛木(Woonyoungia septentrionalis (Dandy) Law)自然种群中,对单性异株的濒危植物焕镛木进行繁育系统测定,对即将开花的雌花花蕾分别进行套袋、套网、人工授粉处理,并用自然授粉雌花作对照,其座果率和结实率统计结果表明：自然授粉、人工授粉、套袋和套网处理的花均能结实,但它们的座果率和结实率存在较大的差异。在两个种群中,人工授粉和自然授粉的总结实率(PERS)均比套袋和套网处理的高,其中人工授粉的最高,套网处理的最低。由此可见,焕镛木既能通过有性生殖方式结实,又能通过无融合生殖方式结实,而且这两种生殖方式获得的种子均能萌发成幼苗,由此断定,焕镛木的繁育系统为兼性无融合生殖。这是首次报道木兰科植物存在无融合生殖现象。     

Do pollinators influence seed-set in Banksia paludosa Sm. and Banksia spinulosa R. Br.?

The consequences of observed variations in pollinator activity for plant reproduction depend on the breeding system of the plant and also on whether pollination is a resource in short supply. These factors are frequently assumed rather than tested. In bagging experiments with Banksia paludosa in heath and B. spinulosa var. spinulosa in woodland, the present study demonstrated that seed-set does not occur by autogamy and that pollinators are indeed necessary. Experimental addition of outcrossed pollen to inflorescences failed to produce any increase in the mean number of seeds per inflorescence, measured for non-barren inflorescences, for either species. However, in B. paludosa, the addition of pollen increased the numbers of inflorescences that set seed from 20% (controls) to 45% (pollen-added treatment). This suggests either unusual patterns of pollen movement among and within plants or control of the pattern of seed-set within a plant. Pollen additions failed to alter seed-set in B. spinulosa. It is possible that a greater abundance of pollinators in the woodland ensures adequate pollination for these plants     

Pollination and breeding system of the enigmatic South African parasitic plant Mystropetalon thomii (Mystropetalaceae): rodents welcome,but not needed

• Unrelated plants adapted to particular pollinator types tend to exhibit convergent evolution in floral traits. However, inferences about likely pollinators from ‘pollination syndromes’ can be problematic due to trait overlap among some syndromes and unusual floral architecture in some lineages. An example is the rare South African parasitic plant Mystropetalon thomii (Mystropetalaceae), which has highly unusual brush‐like inflorescences that exhibit features of both bird and rodent pollination syndromes.
• We used camera traps to record flower visitors, quantified floral spectral reflectance and nectar and scent production, experimentally determined self‐compatibility and breeding system, and studied pollen dispersal using fluorescent dyes.
• The dark‐red inflorescences are usually monoecious, with female flowers maturing before male flowers, but some inflorescences are purely female (gynoecious). Inflorescences were visited intensively by several rodent species that carried large pollen loads, while visits by birds were extremely rare. Rodents prefer male‐ over female‐phase inflorescences, likely because of the male flowers’ higher nectar and scent production. The floral scent contains several compounds known to attract rodents. Despite the obvious pollen transfer by rodents, we found that flowers on both monoecious and gynoecious inflorescences readily set seed in the absence of rodents and even when all flower visitors are excluded.
• Our findings suggest that seed production occurs at least partially through apomixis and that M. thomii is not ecologically dependent on its rodent pollinators. Our study adds another species and family to the growing list of rodent‐pollinated plants, thus contributing to our understanding of the floral traits associated with pollination by non‐flying mammals.

     

Reproductive trade-offs in a specialized plant/pollinator system involving Asplundia uncinata Harling (Cyclanthaceae) and a derelomine flower weevil (Coleoptera: Curculionidae)

The reproductive interactions of a specialized plant/pollinator system involving Asplundia uncinata Harling (Cyclanthaceae) and a derelomine flower weevil (Coleoptera: Curculionidae: Derelomini) were studied at La Selva, Costa Rica. The inflorescences of A. uncinata exhibit a suite of cantharophilous characters including a precisely synchronized anthesis, protogyny, thermogenesis, olfactory attraction of visitors via modified staminodes, and narrow interfloral entrances. The weevil pollinators use the inflorescences for feeding, mating, and oviposition. The larvae are detritivorous and develop either in the detaching staminate flowers or, at a more favorable rate, in the rotting infructescences. The rate of infructescence abortion was high and caused by low levels of pollination. Manual pollination treatments yielded significantly higher seed counts than obtained under natural conditions, and furthermore demonstrated the inflorescences' ability to reproduce via geitonogamy. In the longer term, the reproductive benefits of maintaining low levels of pollination may shift away from the weevils and towards the plants via an increase in the size of the pollinator population.     

Microspatial population genetic structure of the Mediterranean shrub Fumana thymifolia

Fumana thymifolia (Cistaceae) is an insect-pollinated, gravity-dispersed evergreen shrub, which is a common component of fire-prone Mediterranean shrubland ecosystems. Despite the availability of basic knowledge on its ecology, little is known of its breeding system and no information is available on its population genetic structure. We explored the within-population genetic structure of this species using amplified fragment length polymorphism (AFLP) molecular markers and related this to predictions based on its breeding system, pollen and seed dispersal. Existing information on the reproductive ecology of F. thymifolia was supplemented by artificial pollination experiments. We determined that self-fertilisation can occur in F. thymifolia but results in reduced fruit set. Significant genetic structuring was detected within the population, a likely consequence of localised seed dispersal in combination with a mixed mating system. In a study site covering approximately 0.5 ha, amova revealed that approximately 9% of genetic variability was distributed among population subsamples. Significant spatial genetic structure was detected, with kinship coefficients being significantly elevated above the null expectation in the first six distance classes (maximum 5 m), and a value of Sp of up to 0.0342, comparable with species having similar ecological characteristics. Weak isolation by distance at the plot scale was detected, suggesting that insect-mediated pollen flow is non-random, despite being more extensive than seed dispersal. Fumana thymifolia provides a promising model for the investigation of both short- and long-term population dynamics in relation to fire frequency within this plant community.     

Sequential decline in fruit resource allocation within inflorescences of Sagittaria trifolia: a test of non‐uniform pollination hypothesis

Flowering plants often exhibit declining resource investment to floral organs, fruits and seeds temporally or spatially in an inflorescence. To account for such variances, non‐uniform pollination hypothesis, which highlights various mating environments each flower experiences, provides adaptive significance for allocation patterns but with controversial supports. Sagittaria trifolia (Alismataceae) was used to examine differences in seed number, seed weight and germination rate among sequential fruits within inflorescences. Ovule number was also investigated to evaluate allocation patterns in the floral stage. To test the non‐uniform pollination hypothesis, we used three polymorphic microsatellite loci of S. trifolia to estimate the seed outcrossing rate in proximal and distal fruits. The results showed that the seed number, average seed weight and seed germination rate of S. trifolia gradually decreased from proximal to distal fruits within inflorescences. The percent of decrease in seed number between two contiguous fruits was 14.68 ± 3.22%, which was much stronger than the percent of decrease in ovule number at 6.95 ± 1.60%. Both proximal and distal fruits within inflorescences had high outcrossing rates (81.5 ± 5.0%, proximal; 82.3 ± 6.9%, distal) and they did not differ significantly. Overall, there was an acropetal decline of resource allocation to fruits within inflorescences of S. trifolia. Allocation pattern to ovules was not a limiting factor for seed production. The lack of difference in outcrossing rate between proximal and distal fruits indicated that the allocation strategy was probably not caused by non‐uniform pollination, but more likely position effects.     

Pollen dispersal and gene flow within and into a population of the alpine monocarpic plant Campanula thyrsoides

Background and Aims

Gene flow by seed and pollen largely shapes the genetic structure within and among plant populations. Seed dispersal is often strongly spatially restricted, making gene flow primarily dependent on pollen dispersal within and into populations. To understand distance-dependent pollination success, pollen dispersal and gene flow were studied within and into a population of the alpine monocarpic perennial Campanula thyrsoides.

Methods

A paternity analysis was performed on sampled seed families using microsatellites, genotyping 22 flowering adults and 331 germinated offspring to estimate gene flow, and pollen analogues were used to estimate pollen dispersal. The focal population was situated among 23 genetically differentiated populations on a subalpine mountain plateau (<10 km²) in central Switzerland.

Key Results

Paternity analysis assigned 110 offspring (33·2 %) to a specific pollen donor (i.e. ‘father’) in the focal population. Mean pollination distance was 17·4 m for these offspring, and the pollen dispersal curve based on positive LOD scores of all 331 offspring was strongly decreasing with distance. The paternal contribution from 20–35 offspring (6·0–10·5 %) originated outside the population, probably from nearby populations on the plateau. Multiple potential fathers were assigned to each of 186 offspring (56·2 %). The pollination distance to ‘mother’ plants was negatively affected by the mothers'' degree of spatial isolation in the population. Variability in male mating success was not related to the degree of isolation of father plants.

Conclusions

Pollen dispersal patterns within the C. thyrsoides population are affected by spatial positioning of flowering individuals and pollen dispersal may therefore contribute to the course of evolution of populations of this species. Pollen dispersal into the population was high but apparently not strong enough to prevent the previously described substantial among-population differentiation on the plateau, which may be due to the monocarpic perenniality of this species.     

Reproductive biology of Ranunculus weyleri (Ranunculaceae), a narrowly endemic plant from the Balearic Islands with disjunct populations

Ranunculus weyleri is a species endemic to Mallorca Island (western Mediterranean basin) that is currently threatened due to its reduced geographical distribution and disjunct, isolated populations. It is a small, perennial herb that inhabits rocky environments, together with other endemic plants with creeping life-forms. In the present study, for the first time the reproductive biology of the species was investigated in terms of its floral phenology (floral stages and times of formation), pollen/ovule (P/O) ratios, and fruit and seed setting under natural and pollen manipulation experiments, assessing the breeding system, pollination vectors and pollen limitations. Cross-pollinations among populations were performed to evaluate the levels of compatibility between populations. In addition, the floral displays and the reproductive outputs of four wild populations were determined. The observed high P/O ratios, results of the hand-pollination experiments, and flower traits indicate that this species is predominantly allogamous. Combinations of both insects (belonging to Coleoptera, Diptera, Lepidoptera and Hymenoptera) and wind (ambophily) constitute the main pollination vectors, and pollen limitation was observed. Interpopulation crossing was effective, and exogamic depression was not present, as evidenced by the fecundity levels. The predation of the floral stems by herbivores (mainly goats) severely limits the reproductive success of this endemic species in wild populations. Finally, several ways of action are proposed for R. weyleri conservation.     

Quantifying patch‐specific seed dispersal and local population dynamics to estimate population spread of an endangered plant species

AimHabitat loss and fragmentation impose high extinction risk upon endangered plant species globally. For many endangered plant species, as the remnant habitats become smaller and more fragmented, it is vital to estimate the population spread rate of small patches in order to effectively manage and preserve them for potential future range expansion. However, population spread rate has rarely been quantified at the patch level to inform conservation strategies and management decisions. To close this gap, we quantify the patch‐specific seed dispersal and local population dynamics of Minuartia smejkalii, which is a critically endangered plant species endemic in the Czech Republic and is of urgent conservation concern.LocationŽelivka and Hrnčíře, Czechia.MethodsWe conducted demographic analyses using population projection matrices with long‐term demographic data and used an analytic mechanistic dispersal model to simulate seed dispersal. We then used information on local population dynamics and seed dispersal to estimate the population spread rate and compared the relative contributions of seed dispersal and population growth rate to the population spread rate.ResultsWe found that although both seed dispersal and population growth rate in M. smejkalii were critically limited, the population spread rate depended more strongly on the maximal dispersal distance than on the population growth rate.Main conclusionsWe recommend conservationists to largely increase the dispersal distance of M. smejkalii. Generally, efforts made to increase seed dispersal ability could largely raise efficiency and effectiveness of conservation actions for critically endangered plant species.     

自花授粉在安徽羽叶报春花色选育中应用的初步研究

安徽羽叶报春是我国特有的一种珍稀濒危花卉。论文对自花授粉在其花色选育中的应用进行了初步研究。结果表明：安徽羽叶报春自花授粉亲和性较高,平均结籽数可达36.03粒/果,能达到正配授粉结籽数的71.11%（正配授粉结籽数为50.69粒/果）,而且自花授粉种子也基本能正常萌发,萌发率为41.13%,达到正配授粉种子萌发率的57.98%。花色分析显示自花授粉子代花色R值比重均值（即红色成分,为0.382）显著高于其亲本群体及正配授粉子代的均值（均为0.375左右）。因此安徽羽叶报春自花授粉虽存在一定的衰退现象,但它有利于花色的选育和纯合品系的获得,在其花色的选育过程中应加以重视和利用。     

Pollination of Richea dracophylla (Ericaceae) and the role of the nocturnal ant Notoncus hickmani (Formicinae)

Our observation of large numbers of ants Notoncus hickmani (Formicinae) on the flowers of a Tasmanian endemic shrub Richea dracophyllum (Ericacea) during the night in winter prompted us to carry out a more extensive study of pollination of R. dracophyllum at two sites. Terminal panicles bear inflorescences of 300+ flowers whose petals are fused into calyptrae covering the reproductive organs, and the calyptrae must be removed before pollination can occur. To exclude birds, we placed mesh bags over some inflorescences. Inflorescences with exclusion bags had a high proportion of retained calyptra and the numbers of viable seeds were greatly reduced. We found R. dracophyllum to have a very long flowering period (more than 6 months) and a range of floral visitors, including honey-eaters (Meliphagidae) and flying insects. At one site we observed large numbers (up to 100) of N. hickmani on inflorescences between dusk and midnight during winter at air temperatures down to 2.5°C. They fed on nectar from flowers that had lost their calyptra where they were exposed to pollen from the anthers and scanning electron microscopy showed high numbers of pollen grains being carried on the ants. The feeding behaviour of these ants would facilitate pollination between adjacent flowers (geitonogamy). Smaller numbers of dolichoderine ants (Iridomyrmex bicknelli?) were observed during the daytime in spring but mainly fed under partially detached calyptrae where they had little exposure to pollen. We suggest that R. dracophylla is pollinated by a range of species and functional groups—birds, flying insects and ants, and that the pollinating species will vary during the year and between sites, although insects depend on birds to remove the calyptrae. Ant pollination is rare, nocturnal ant pollination is extremely rare, and pollination by nocturnal cryophilic ants has not been documented previously.