Ant pollination of <Emphasis Type="Italic">Syzygium occidentale</Emphasis>, an endemic tree species of tropical rain forests of the Western Ghats,India

Although mutualism between ants and flowering plants is wide spread, ant pollination has not evolved as a major pollination syndrome. So far ant pollination has been reported largely in herbaceous species, growing in warm and dry habitats. While studying pollination ecology of Syzygium species (Myrtaceae), growing in tropical forests of the Western Ghats, India, we observed one of the ant species, Technomyrmex albipes, to be the dominant floral visitor in S. occidentale (Bourd.) Chithra among a range of other insect (species of Xylocopa and Trigona, and Apis cerana) and bird visitors. We studied the role of ant species in pollination when compared to other floral visitors. The fruit set in flowers exclusively visited by T. albipes was significantly higher than those visited by any other visitor. The day and night exclusive pollination experiments allowing only T. albipes indicated diel pollination by T. albipes, which was the only active flower visitor during the night. The breeding system of the species was studied through controlled pollinations. The species is partially self-compatible and exhibits considerable autogamy.     

Adaptation of the seed reproduction system to conditions of Maritime Antarctic in <Emphasis Type="Italic">Deschampsia antarctica</Emphasis> E. Desv.

Deschampsia antarctica3 E. Desv. is one of the two flowering plants that, along with Colobanthus quitensis (Kunth) Bartl., was able to settle the ice-free areas of Antarctica. In order to identify the possible adaptations of the D. antarctica reproductive system to adverse environmental conditions, comparative cytoembryological analysis of plants of this species growing on the Antarctic Peninsula with plants of the closely related species D. beringensis Hult. from the Kamchatka Peninsula was conducted. It was found that both species are characterized by sexual mode of reproduction, equal size of pollen grains (25.5 ± 2.2 and 26.2 ± 1.9 μm, respectively), same features of the embryo sac structure, and emryo- and endospermogenesis. Interspecies differences have been found in mature embryo sac size (326.8 ± 12.8 and 161.7 ± 10.4 μm), pollen sterility percentage (86.1 ± 8.9 and 35.3 ± 9.2%), and quantity of pollen in the anthers (140 ± 15.3 and 1578 ± 88.6). Possible causes and significance of these differences are discussed. No unique adaptations of seed reproduction system that are inherent exclusively to D. antarctica were found. The D. antarctica reproduction strategy is based on the combination of autogamy (and its extreme form cleistogamy) with production of excess pollen quantity for its mode of pollination.     

Wind or insect pollination? Ambophily in a subtropical gymnosperm Gnetum parvifolium (Gnetales)

Gnetum (Gnetales) has long been regarded as insect pollinated due to its range‐restricted distribution in tropical rain forests, where wind pollination is supposed to be detrimental. However, ubiquitous pollen limitation in the tropics might cause transition to anemophily, or even ambophily for reproductive assurance, especially for gymnosperms such as Gnetum, which exhibit various anemophilous syndromes, including absence of petals, greenish color of strobili, dioecy and uniovulate flowers. Pollination treatments applied to Gnetum parvifolium in southern China revealed this rare and endangered species to be pollen limited and incapable of apomixis. Pollen grains of G. parvifolium did not adhere to each other and could be trapped by interception traps near the male and female strobili. Seed set in the netted treatment (anemophily) was significantly higher than in the bagged treatment (apomixis) but lower than open pollination (anemophily and entomophily), indicating that both wind and biotic pollination contributed to seed production of G. parvifolium. The occurrence of ambophily in Gnetum and the prevalence of anemophily in Ehpedra and Welwitschia suggest that wind may also play a role in the pollination of the ancient Gnetales.     

Transplantation and immunoincompatibility reactions among reef-building corals

Intracolony or syngeneic transplants of pieces of living coral, either occurring naturally on reefs or produced experimentally, were consistently compatible. In contrast, intercolony allografts performed extensively inAcropora formosa and inPorites andrewsii were incompatible, as were allografts occurring naturally in additional species observed in reef communities. Diverse interspecific combinations of coral xenografts generally displayed greater incompatibilities. Four levels of immuno-reactivity, with manifestations ranging from mild to severe, were distinguishable as follows: a) contact avoidance reactions, b) allogeneic contact incompatibility, c) chronic xenogeneic incompatibility, and d) acute interspecific aggression.Allogeneic incompatibility, most studied inA. formosa, was characterized by soft tissue contact avoidance wherever possible; absence of tissue death despite extensive enforced contact (18–20 days); and late interfacial cementation terminating allogeneic soft tissue contact. The properties ofchronic xenogeneic incompatibility as found in diverse species combinations, are slow onset (>7 days), bidirectional or unidirectional killing in contact zones, and short-range or localized effectiveness.Acute interspecific aggression initiated byFungia fungites as a dominant “aggressor ” is distinguished by early occurrence (2–7 days) and unidirectional contact killing. The presence or absence of these acute xenogeneic reactions sharply discriminated between species within each of the generaAcropora, Pocillopora, andPorites. No hierarchy of aggressive interactions was evident at the generic level.     

Reproductive biology of Abolboda pulchella and A. poarchon (Xyridaceae: Poales)

Background and Aims

Abolboda (Xyridaceae) belongs to the Poales, a predominantly wind-pollinated order whose phylogeny has been widely studied in recent years. The reproductive biology of Abolboda pulchella and A. poarchon was studied to determine the main pollination system of these species, providing the first experimental data on reproduction in the Xyridaceae.

Methods

A field study was conducted, including observations on the morphology and biology of the flowers, insect visits and pollinator behaviour. Experimental pollination treatments were performed to assess agamospermy, spontaneous self-pollination and self-compatibility. Pollination success was determined by pollen tube growth, and reproductive success was assessed by fruit- and seed-set.

Key Results

Abolboda pulchella and A. poarchon were pollinated by Apidae, Megachilidae and Halictidae bees. The floral resources were pollen and nectar that was produced by stylar appendages, an uncommom nectary type for monocotyledons. The species were self-compatible, and pollen tube growth from self-pollen was similar to that of cross-pollen. However, herkogamy prevented spontaneous selfing, rendering the plants dependent on the pollinator''s activity. There was no production of seeds by agamospermy.

Conclusions

Melittophily is the main pollination system of these two Abolboda species. Nectar production was first recorded here for Xyridaceae, and along with self-compatibility, herkogamy and bee pollination, is an informative characteristic that can be used in future phylogenetic analyses of the family as well as Poales.     

Relocation of Chydorus barroisi and related species (Cladocera,Chydoridae) to a new genus and description of two new species

Five taxa already in the literature are here removed from Chydorus to their own genus Ephemeroporus, and two new species — E. acanthodes and E. archboldi — are described, with E. acanthodes being designated the type species of the genus. These taxa, plus at least nine undescribed species and others undoubtedly waiting to be sorted out, constitute a tightly circumscribed group of species morphologically. The first two species described — E. barroisi and E. poppei — are nomina dubia for the present, as no specimens exist from the original collections, nor are any available from the type localities or reasonably close thereto. E. hybridus from Brazil has been characterized in greater detail through the availability of specimens from the type series, which has enabled one of the species in the E. hybridus group from North America to be judged conspecific with reasonable certainty. E. tridentatus, from Brazil, has been restored as a valid species, and the highly distinctive E. phintonicus from Sardinia and Algeria constitutes the seventh species in the genus. Chydorus nitidulus and Chydorus tilhoi, which have been suggested to be members of the barroisi complex, are not. What are presently called E. barroisi and E. hybridus, except for E. hybridus, sens. str., each consists of a cluster of species sharing the same number of teeth on the labrum and shell. Because of their wide, distribution, abundance, and frequency of occurrence, especially in South Asia, the species in the E. barroisi group will be especially meaningful to sort out.     

The stimulatory effect of uracil and 5-bromouracil on the seed set inPapaver somniferum L.

A study was made concerning the effect of the analogues of nucleic acid components upon the seed set inPapaver somniferum L. For the experiments flowers one day after anthesis were used, as the pollination taking place at this flower age had previously been found to be most efficient for the seed set. The solutions of analogues in a 10 per cent sucrose were applied by injecting them into the ovaries three hours prior to pollination. Damage to the ovary by the injection reduces the seed set by about two thirds. In comparison with control flowers, into which only a sucrose solution was injected, 5-bromouracil at a concentration of 5.2×10^?4 M increases the seed set by about 70 per cent. Uracil brings about the same degree of promotion. The same concentration of 5-bromodeoxyuridine has no significant effect on the seed set. When applied simultaneously with uracil it suppresses its stimulating effect completely. The equimolar mixture of uracil and bromouracil did not cause any significant increase in the number of seeds in the capsules, either.     

The floral biology and reproductive system of <Emphasis Type="Italic">Mauritia flexuosa</Emphasis> (Arecaceae) in a restinga environment in northeastern Brazil

Studies of the floral biology of the buriti palm, Mauritia flexuosa, have presented conflicting results with respect to the mechanism of pollination, indicating either cantharophily or anemophily. To resolve this question, the floral biology of M. flexuosa was studied in a coastal restinga environment in northeastern Brazil. The reproductive system was studied experimentally, and floral visitors were collected by bagging inflorescences. In this environment, M. flexuosa, a dioecious species, has several gender-specific floral features that function to attract pollinators, especially beetles. The male flowers produce large amounts of pollen as a reward, and male and female inflorescences produce similar odors that attract pollinators to female flowers, which offer only a nectar secretion as a reward. When feeding on the female flowers, the visitors frequently come into contact with the stigmata. To increase the chances of pollination, the female flowers persist longer than the male ones, and the viability of the pollen grain is very high. A curculionid beetle species of the genus Grasidius was found to be an effective pollinator. We suspect that wind also contributes to the pollination of M. flexuosa in the study area, but in a relatively minor way.     

Anthecology and reproductive system of Mourera fluviatilis (Podostemaceae): Pollination by bees and xenogamy in a predominantly anemophilous and autogamous family?

The Podostemaceae are sessile hydrophytes restricted to habitats with waterfalls and seasonal flow variability. Mourera fluviatilis belongs to the family and has a disjunct distribution in the Amazon and northeastern Brazil. The following hypotheses were tested: (i) both autogamy and anemophily act on the pollination system of M. fluviatilis, and (ii) the highest reproductive success is achieved by cross-pollination. Natural populations were monitored in the rivers Pirangi and Ipojuca, northeastern Brazil. Floral visitors are the polylectic bees Apis mellifera, Trigona spinipes (Apidae), Augochlora sp. and Augochloropsis sp. (Halictidae), though only the latter three are effective pollinators. In experiments on the reproductive system and pollination there was a high percentage of fruit formation (>86%), both in treatment and control plants. Although the index of self-incompatibility is 0.86, there was a significant difference in the number of seeds produced among reproductive system treatments, and xenogamy produced more seeds. There was no significant difference in the number of penetrated ovules between control and manual cross-pollination (xenogamy) treatments, 24 h after pollination. However, there were differences among treatments, 48 h after pollination, except for the control and xenogamy treatments. The pollen tubes from cross-pollination treatments usually penetrate the micropyle in shorter time and in higher quantity. We found differences among pollination experiments, except for the control and non-emasculated treatments, and between emasculated treatments. In spite of the ambiguity of floral attributes (pedicel, filaments and anthers colors, sweet odor, reduced perianth, absence of nectar, small and dry pollen grains), wind pollination is less important for this species; what predominates instead are first allogamy mediated by bees and second self-pollination at the end of anthesis.     

Regulation of gametangial formation in bryophytes

Under in vitro conditions gametangial formation in bryophytes can be regulated by a variety of physical and chemical factors. Liverworts are relatively more sensitive to photoperiod than are mosses. With the exception ofRiccia crystallina all species of liverworts thus far investigated are either long-day or short-day plants. Among mosses, all butSphagnum plumulosum appear to be independent of photoperiod for the onset of the reproductive phase. The photoperiodic response in liverworts increases with increasing light intensity. Mosses, on the other hand, exhibit differential behavior.Leptobryum pyriforme andBartramidula bartramioides exhibit a linear relationship with light intensity for this response, whereasBryum argenteum, B. coronatum andBarbula gregaria have a specific light intensity requirement for optimal response. The photoperiodic effect in bryophytes is operative within certain temperature limits. Most bryophytes do not require a low temperature pretreatment for gametangial induction. Some become fertile in a broad temperature range, whereas others require a specific temperature. Among chemical factors, carbohydrates in general enhance gametangial formation.Riccia crystallina andBartramidula bartramioides develop gametangia in the presence of a carbohydrate, butBryum spp. (B. argenteum andB. coronatum) andBarbula gregaria respond even in its absence. High carbohydrate-nitrogen ratio seems more favorable for the onset of reproductive phase. Bryophytes respond differentially to various forms of nitrogen. Depletion of inorganic nitrogen (nitrate or ammonium) significantly favors gametangial induction. On the other hand, organic nitrogen (such as amino acids, peptone and urea) has differential effects on the enhancement of antheridial and archegonial formation in liverworts. Growth hormones have variable effects on gametangial induction. Indole-3-acetic acid increases archegonial formation inRiccia crystallina, but it is more favorable for antheridial production in mosses likeBryum coronatum, B. argenteum andBarbula gregaria. Gibberellins enhance antheridial formation in all the investigated bryophytes. Cytokinins stimulate induction of archegonia and inhibit antheridial formation inRiccia crystallina andBryum argenteum. Auxins, gibberellins and cytokinins also interact in eliciting the response. Iron and copper chelating agents such as EDTA and EDDHA favor vegetative growth and gametangial formation. InRiccia these chelates enhance archegonial production more than antheridial formation, but inBryum argenteum their effect is just the reverse. Salicylic acid, known to chelate iron and copper in certain animal systems, inhibits gametangial formation in most bryophytes, except inBartramidula in which it enhances vegetative growth as well as gametangial formation. InBryum argenteum the effect of these chelates is accompanied with marked changes in the endogenous levels of iron and copper. Iron appears to favor the onset of reproductive phase, whereas copper is inhibitory. Cyclic AMP, a well known mediator of hormone action in animal systems, enhances gametangial formation inBryum argenteum. The response is specific and is mimicked by phosphodiesterase inhibitors. Cyclic AMP also increases antheridial production inBryum coronatum andBarbula gregaria. InBryum argenteum it overcomes the inhibitory effect of ammonium ions and high concentrations of sucrose on gametangial formation. In addition to the above factors, pH and nutritional status of the medium also affect the onset of reproductive phase. Bryophytes exhibit maximum response in a definite pH range. Moreover, a specific change in pH of the medium is observed during gametangial initiation. Nutritional status, as affected by the concentration of nutrients in the medium, has varied effects on gametangial formation. In most instances dilution of the medium is more favorable for the response. Certain other factors, such as yeast extract and animal sex hormones, also enhance the formation of antheridia and archegonia. The onset of the reproductive phase involves metabolic changes in the differentiating tissues. Archegonial initiation is accomplished by intense metabolic activities, and in certain liverworts there is an increase in the content of carbohydrates, auxins, RNA and proteins, whereas the level of total nitrogen drops. Besides this a number of enzymes and phenolic compounds also exhibit marked qualitative and quantitative changes. Once gametangia are induced under in vitro conditions, fertilization can be accomplished by flooding the cultures bearing mature gametangia with sterile, distilled water. Development of sporophytes is markedly affected by temperature and nutritional status of the medium.     

Some pollination strategies in neotropical savannas and forests

Previously published data on flowering phenology and pollination of neotropical families are reviewed and compared with new observations, in order to evaluate some trends of pollination strategies in neotropical savannas and forests. Central American forestBignoniaceae apparently diminish competition between sympatric species with identical pollination strategies by alternating flowering. On the other hand, in theBignoniaceae of Brazilian cerrado savannas coincident flowering is more common, suggesting different pollination strategies. Bees specialized in nectar robbery are associated withBignoniaceae, particularly mass-flowering species. These nectar robbers stimulate pollinator movements between flowers and thus increase pollen-flow. The flowering phenology of theMalpighiaceae from forests and savannas apparently follows the phenology of theAnthophorinae (mainlyCentridini)-bees, on which this plant group almost exclusively depends for pollination in the Neotropics. As the flowers of different genera and species are very uniform, the bees quite indiscriminately pollinate coexistingMalpighiaceae taxa. In theMalvaceae, the more primitive tree or shrub habit and an allogamous reproduction system is quite significantly associated with an ornithophilous pollination mode. Hummingbirds in the Neotropics have probably influenced the origin of the primitive bird-pollinatedMalvaceae flower. In conjunction with the diversification of theMalvaceae and their migration into more open regions, pollination by bees has apparently become more prominent. ChiropterophilousMalvaceae seem to have developed more recently from ornithophilous ancestors within the neotropical forest regions. As a result of this ecological radiation, parallel modifications of the basic ornithophilous flower principle can be traced in different groups of theMalvaceae. Dynastinae-beetles are pollinators of South and Central American species ofAnnona, Cymbopetalum, Caladium, Talauma, Philodendron, Victoria, Nymphaea, Cyclanthus, Bactris and others. In many cases the relationship between flowers and theirDynastinae visitors is not very specific, principally reflecting differences in the faunistic spectrum of diverse regions and vegetation types. The attraction of these beetles as flower visitors in several unrelated groups of Angiosperms must have occurred repeatedly. It is suggested that the flower visiting species of this beetle group may have acquired their preference for certain pungent or aromatic flower odours by their feeding habits during the larval stage.     

Past hybridization between Quercus macrocarpa and Quercus gambelii

Introgression between two allopatric species,Quercus macrocarpa andQ. gambelii, has been observed in two separate locations: northeastern New Mexico and the Black Hills of western South Dakota and adjacent Wyoming. The probability that this introgression is the result of long-range pollination appears remote. Presumably these two species hybridized during a period of past sympatric association. Further indication of past sympatry in the Black Hills is the presence of a common species of obligate parasite, i.e., wasp(Cynips insulensis) onQ. gambelii in the Rocky Mountains and onQ. macrocarpa of the Black Hills. The hybrid oaks in New Mexico probably reflect a westward migration ofQ. macrocarpa during pluvial periods of the Pleistocene.Quercus gambelii most likely reached the Black Hills during the warmer postglacial hypsithermal era. The hybridization reported here may reflect secondary sympatry, i.e., sympatric occurrence after the species, or their ancestors, became geographically separated.     

Chromosomal localization and genomic organization of cloned repetitive DNA fragments in mosquitoes (Diptera: Culicidae)

The chromosomal localization and genomic organization of three cloned repetitive DNA fragments (viz., H-76, H-61, and H-19) isolated from theAedes albopictus genome have been examined inAe. albopictus and six otherAedes species:Ae. aegypti, Ae. seatoi, Ae. flavopictus, Ae. polynesiensis, Ae. alcasidi andAe. katherinensis. The results fromin situ and Southern hybridization analyses show that the sequences homologous to cloned repetitive DNA fragments are dispersed throughout the genome in each species. The sequences homologous to these cloned repetitive DNA fragments are also found inHaemagogus equinus, Tripteroides bambusa andAnopheles quadrimaculatus and are dispersed in their genomes. Data indicate divergence in the amount and the structural organization of sequences homologous to these cloned fragments among mosquito species.     

Production of extracellular enzymes by aquatic hyphomycetes

Preliminary studies of the production of extracellular enzymes in eight species of aquatic hyphomycetes showed that none of the organisms contained a proteinase activity. Pyrocateehol oxidase activity was restricted toI. hamata andP. constricta. Significant cellulase and α-amylase activity was found inL. curvula. Triacylglycerol lipase activity was maximum inP. constricta.     

Adding Perches for Cross-Pollination Ensures the Reproduction of a Self-Incompatible Orchid

Background

Outcrossing is known to carry genetic advantages in comparison with inbreeding. In many cases, flowering plants develop a self-incompatibility mechanism, along with a floral component adaptation mechanism, to avoid self-pollination and to promote outbreeding. Orchids commonly have a lip in their flower that functions as the a visiting plate for insect pollinators. Aside from the lip, however, many species (including Coelogyne rigida) have sheaths around the axis of inflorescence. The function of these sheaths remains unknown, and has long been a puzzle to researchers.

Methodology/Principal Findings

We investigated the function of these sheaths in relation to the lip and the pollinators, as well as their role in the modes of pollination and reproduction of Coelogyne rigida in 30 flowering populations of orchids in the limestone area of Southeast Yunnan, China. We found that self-incompatible C. rigida developed specialized bird perches around the basal axis of inflorescence to attract sunbirds and to complement their behavioral tendency to change foraging locations frequently. This self-incompatibility mechanism operates separately from the floral component adaptation mechanism. This mechanism thus prevents bees from repeatedly visiting the floral lip of the same plant which, in turn, results in autogamy. In this way, instead of preventing autogamy, C. rigida responds to these negative effects through a highly efficient cross-pollination method that successfully transfers pollen to different plants.

Conclusions

The proposed method ensures reproductive success, while offsetting the infertile self-pollination by insects, thereby reducing mating costs and addressing the lack of cross-pollination. The adaptation provides a novel and striking example of structural adaptation that promotes cross-pollination in angiosperms.     

Reproductive biology of the threatened <Emphasis Type="Italic">Lilium pomponium</Emphasis> (Liliaceae), a species endemic to Maritime and Ligurian Alps

Pollination ecology and breeding system of Lilium pomponium L. were studied, and their effect on the reproductive outcome was assessed. This species has high conservation interest in Europe, because it is included in Annex V of the EU Habitat Directive and it is one out of the five Lilium species listed in IUCN Global Red List. To achieve our aim, the pollen vectors as well as the effect of bagging, emasculation and artificial pollination on reproductive output were studied. The most frequent visitor was the Lepidopteran Gonepteryx rhamnii. In general, reproductive outputs were close to zero for all the self-pollination treatments; however, geitonogamy and facilitated selfing seem slightly more efficient than autogamy, as also confirmed by self-compatibility and autofertility indices. Altogether, our results suggest a self-incompatible outcrossing breeding system, with a poor capacity for selfing. Nevertheless, climate change and anthropic threats might promote a shift toward self-fertilization, even maladaptive, favouring the few individuals able to produce selfed seeds.     

Do specialized flowers promote reproductive isolation? Realized pollination accuracy of three sympatric Pedicularis species

Background and Aims

Interest in pollinator-mediated evolutionary divergence of flower phenotype and speciation in plants has been at the core of plant evolutionary studies since Darwin. Specialized pollination is predicted to lead to reproductive isolation and promote speciation among sympatric species by promoting partitioning of (1) the species of pollinators used, (2) when pollinators are used, or (3) the sites of pollen placement. Here this last mechanism is investigated by observing the pollination accuracy of sympatric Pedicularis species (Orobanchacae).

Methods

Pollinator behaviour was observed on three species of Pedicularis (P. densispica, P. tricolor and P. dichotoma) in the Hengduan Mountains, south-west China. Using fluorescent powder and dyed pollen, the accuracy was assessed of stigma contact with, and pollen deposition on, pollinating bumble-bees, respectively.

Key Results

All three species of Pedicularis were pollinated by bumble-bees. It was found that the adaptive accuracy of female function was much higher than that of male function in all three flower species. Although peak pollen deposition corresponded to the optimal location on the pollinator (i.e. the site of stigma contact) for each species, substantial amounts of pollen were scattered over much of the bees'' bodies.

Conclusions

The Pedicularis species studied in the eastern Himalayan region did not conform with Grant''s ‘Pedicularis Model’ of mechanical reproductive isolation. The specialized flowers of this diverse group of plants seem unlikely to have increased the potential for reproductive isolation or influenced rates of speciation. It is suggested instead that the extreme species richness of the Pedicularis clade was generated in other ways and that specialized flowers and substantial pollination accuracy evolved as a response to selection generated by the diversity of co-occurring congeners.     

Woloszynskia stoschii andGymnodinium indicum,two new freshwater dinoflagellates from India: Morphology,reproduction and cytology

The distinctive morphological and karyological features of the two new species, collected from freshwater habitats in North India, are presented and compared with those of related taxa of the generaWoloszynskia andGymnodinium. Asexual reproduction takes place through zoospore formation and sexual reproduction through planozygotes inWoloszynskia stoschii.     

New taxa and combinations inAlchemilla (Rosaceae) (2)

47 names and combinations are published as new, chiefly from the elaboration ofAlchemilla byA. Plocek inL. Bertová (ed.), Flóra Slovenska 4/3, Bratislava (in press). The populations recognized as varieties and species new to science (12 and 29, respectively) come from the summits of W. Beskids (9 taxa), Belianske Tatry (12), other parts of Tatra (8), Fatra (5), elsewhere in the Central Carpathians in Slovakia (4), the Low Beskids in E. Slovakia (1), W. and E. Carpathians (1), N. Moravia (1). In addition, three epithets are published in a new combination, and the names for two new subseries and a new forma are proposed.     

Insect-induced wind pollination of the palm Chamaedorea pinnatifrons and pollination in the related Wendlandiella sp.

In Peruvian Amazonia pollination ecology of two palms, Chamaedorea pinnatifrons (Jacq.) Oerst. and Wendlandiella sp. was studied from October 1988 to January 1990. Both palms are dioecious understory species that form locally dense populations.In C. pinnatifrons both sexes flower synchronously during the dry season. Prior to anthesis, the pendulous male inflorescence is inhabited by numerous thrips (Thysanoptera) and Ptiliidae (Coleoptera). Staminate flowers open by a small basal slit between the petals. At anthesis pollen is shed and the movements of the insects inside the flowers trigger pollen release in small clouds. Thus, the powdery pollen becomes airborne and finally air currents act as a vector, carrying pollen to the inconspicuous female plants, which usually are not visited by insects. The term insect induced wind pollination is suggested for this pollination mode. Wendlandiella flowers during four months in the dry season. Male and female plants were not visited by insects. The dry condition of the pollen indicates that anemophily is the pollination mode in Wendlandiella. Fructification is rare but the plants show intense vegetative propagation.The significance of anemophily in the tropical lowland rain forest is discussed.