Wind-pollinated Flowers Research Articles

Phylogeny of Anthospermeae of the Coffee Family Inferred Using Clock and Nonclock Models

Premise of research. With wind-pollinated flowers and partly temperate distribution, the tribe Anthospermeae stands out in the otherwise mostly animal-pollinated and tropical coffee family (Rubiace...

Metapopulation vicariance in the Pacific genus Coprosma (Rubiaceae) and its Gondwanan relatives

Coprosma is perhaps the most ubiquitous plant genus in New Zealand. It belongs to the tribe Anthospermeae, which is distinctive in the family Rubiaceae through its small, simple, wind-pollinated flowers and its southern hemisphere distribution. The tribe comprises four main clades found respectively in South Africa, Africa, Australia and the Pacific. The high level of allopatry among the four subtribes is attributed here to their origin by vicariance. The Pacific clade, subtribe Coprosminae, is widespread around the margins of the South Pacific and also occurs on most of the high islands. Distributions of the main clades in the subtribe are mapped here and are shown to be repeated in other groups. The distribution patterns also coincide with features of regional geology. Large-scale volcanism has persisted in the central Pacific region since at least the Jurassic. At that time, the oldest of the Pacific large igneous provinces, the Shatsky Rise, began to be erupted in the region now occupied by French Polynesia. Large-scale volcanism in the central Pacific continued through the Cretaceous and the Cenozoic. The sustained volcanism, along with details of the clade distributions, both suggest that the Coprosminae have persisted in the central Pacific by survival of metapopulations on individually ephemeral islands. It is also likely that vicariance of metapopulations has taken place, mediated by processes such as the subsidence of the Pacific seafloor by thousands of metres, and rifting of active arcs by transform faults. It is sometimes argued that a vicariance origin is unlikely for groups on young, oceanic islands that have never been connected by continuous land, but metapopulation vicariance does not require physical contact between islands.

Cap removal by honey bees leads to higher pollen rewards from grapevine flowers

Pollen of wind-pollinated plants such as grapevine rapidly dries out and is blown away after the anthers dehisce. Therefore, from the point of view of a pollen-collecting bee, pollen from wind-pollinated flowers is best collected soon after it becomes exposed. In grapevine, pollen becomes available immediately after the calyptra is shed, a process also referred to as capfall. We show, for the first time, that honey bees foraging on grapevine actively remove the calyptra from flowers. Using manual cap removal, we estimate that cap removal increases the pollen yield by 70 % compared to collecting pollen from flowers after capfall. The bees selectively foraged on inflorescences with high numbers of loose caps, thus further enhancing their pollen revenue. We discuss the possible benefits of cap removal by honey bees for the development of individual berries and grape bunches of certain varieties.

Assessment of Genetic Diversity and Population Genetic Structure of Corylus mandshurica in China Using SSR Markers.

Corylus mandshurica, also known as pilose hazelnut, is an economically and ecologically important species in China. In this study, ten polymorphic simple sequence repeat (SSR) markers were applied to evaluate the genetic diversity and population structure of 348 C. mandshurica individuals among 12 populations in China. The SSR markers expressed a relatively high level of genetic diversity (Na = 15.3, Ne = 5.6604, I = 1.8853, Ho = 0.6668, and He = 0.7777). According to the coefficient of genetic differentiation (F st = 0.1215), genetic variation within the populations (87.85%) were remarkably higher than among populations (12.15%). The average gene flow (Nm = 1.8080) significantly impacts the genetic structure of C. mandshurica populations. The relatively high gene flow (Nm = 1.8080) among wild C. mandshurica may be caused by wind-pollinated flowers, highly nutritious seeds and self-incompatible mating system. The UPGMA (unweighted pair group method of arithmetic averages) dendrogram was divided into two main clusters. Moreover, the results of STRUCTURE analysis suggested that C. mandshurica populations fell into two main clusters. Comparison of the UPGMA dendrogram and the Bayesian STRUCTURE analysis showed general agreement between the population subdivisions and the genetic relationships among populations of C. mandshurica. Group I accessions were located in Northeast China, while Group II accessions were in North China. It is worth noting that a number of genetically similar populations were located in the same geographic region. The results further showed that there was obvious genetic differentiation among populations from Northeast China to North China. Results from the Mantel test showed a weak but still significant positive correlation between Nei’s genetic distance and geographic distance (km) among populations (r = 0.419, P = 0.005), suggesting that genetic differentiation in the 12 C. mandshurica populations might be related to geographic distance. These data provide comprehensive information for the development of conservation strategies of these valuable hazelnut resources.

A taxonomic revision of native New Zealand Plantago (Plantaginaceae)

Species delimitation is challenging in New Zealand Plantago because of a complex polyploid evolutionary history, few taxonomically useful characters due to reduced habit and wind-pollinated flowers, and phenotypic plasticity. To clarify species limits and revise the taxonomy of this group, analyses of novel morphological data were undertaken and evaluated alongside previously published studies of chromosome number, amplified fragment length polymorphisms, molecular phylogenetics, molecular cytogenetics and morphology. All 11 native species of Plantago recognised here are endemic to New Zealand, except Plantago triantha which is also native to Tasmania, Australia. In contrast to previous treatments, Plantago picta is recognised here at the species rank, Plantago masoniae is treated as a synonym of Plantago triandra, and one new 16-ploid species, Plantago udicola Meudt & Garn.-Jones, is formally described. Seed number and shape, scape, bract and sepal vestiture, and number of flowers and spikes are particularly important characters for species delimitation.

Insects facilitate wind pollination in pollen-limited Crateva adansonii (Capparaceae)

Low fruit-set in obligately outbreeding plant species is attributed to a variety of reasons that can be ascertained from reproductive studies. In the present work, the causes of poor natural fruit-set in Crateva adansonii DC. were investigated. Floral biology, the role of wind and insects in pollination and the breeding system of the species were studied in two natural populations for three consecutive seasons (2006–08). The flowers exhibited traits conducive to a mixture of wind and insect pollination (ambophily). Although a variety of insects visited the flowers, they were ineffective in pollinating. Nevertheless, active foraging by the honeybees (Apis dorsata, A. mellifera and A. cerana indica) facilitated enhanced pollen dispersal in the air and resulted in indirect pollination by wind. Airborne pollen grains pollinated the plants only up to 10 m. Fruit-set from open pollination was comparable to wind-pollinated flowers. Supplemental pollination treatments established the occurrence of strong self-incompatibility (SI) (index of SI = 0.14). Spontaneous autogamy was prevented by pronounced herkogamy. Low natural fecundity in C. adansonii is due to pollination failure, pollen limitation (pollen limitation index = 0.98) and the sparse distribution of the conspecifics; partial SI may partly ensure reproductive assurance through geitonogamy. In the absence of a pollinator wind appears to act as a secondary mode of pollination.

Evolution of flower shape in Plantago lanceolata

Plantago lanceolata produces small actinomorphic (radially symmetric), wind-pollinated flowers that have evolved from a zygomorphic, biotically pollinated ancestral state. To understand the developmental mechanisms that might underlie this change in flower shape, and associated change in pollination syndrome, we analyzed the role of CYC-like genes in P. lanceolata. Related zygomorphic species have two CYC-like genes that are expressed asymmetrically in the dorsal region of young floral meristems and in developing flowers, where they affect the rate of development of dorsal petals and stamens. Plantago has a single CYC-like gene (PlCYC) that is not expressed in early floral meristems and there is no apparent asymmetry in the pattern of PlCYC expression during later flower development. Thus, the evolution of actinomorphy in Plantago correlates with loss of dorsal-specific CYC-like gene function. PlCYC is expressed in the inflorescence stem, in pedicels, and relatively late in stamen development, suggesting a novel role for PlCYC in compacting the inflorescence and retarding stamen elongation in this wind pollinated species.

Wind of change: new insights on the ecology and evolution of pollination and mating in wind-pollinated plants.

The rich literature that characterizes the field of pollination biology has focused largely on animal-pollinated plants. At least 10 % of angiosperms are wind pollinated, and this mode of pollination has evolved on multiple occasions among unrelated lineages, and hence this discrepancy in research interest is surprising. Here, the evolution and functional ecology of pollination and mating in wind-pollinated plants are discussed, a theoretical framework for modelling the selection of wind pollination is outlined, and pollen capture and the occurrence of pollen limitation in diverse wind-pollinated herbs are investigated experimentally. Wind pollination may commonly evolve to provide reproductive assurance when pollinators are scarce. Evidence is presented that pollen limitation in wind-pollinated plants may not be as common as it is in animal-pollinated species. The studies of pollen capture in wind-pollinated herbs demonstrate that pollen transfer efficiency is not substantially lower than in animal-pollinated plants as is often assumed. These findings challenge the explanation that the evolution of few ovules in wind-pollinated flowers is associated with low pollen loads. Floral and inflorescence architecture is crucial to pollination and mating because of the aerodynamics of wind pollination. Evidence is provided for the importance of plant height, floral position, and stamen and stigma characteristics in promoting effective pollen dispersal and capture. Finally, it is proposed that geitonogamous selfing may alleviate pollen limitation in many wind-pollinated plants with unisexual flowers.

Seasonal changes of floral frequency and composition of flower in two cool temperate secondary forests in Japan

As a means of quantitatively evaluating the frequency and species richness of flower at forest community level, we studied flowering phenology throughout the growing season in two cool temperate forests at different successional stages. Flowering observed once for 2 weeks in 1997 and frequency was evaluated the number of 5 m 2 subquadrates flower appeared. The proportion of species that flowered was higher for herbs (76.3 in Pinus-dominated forest and 81.4% in Carpinus-dominated forest) than for trees (35.3 and 35.7%, respectively), shrubs (34.3 and 33.3%, respectively) and vines (21.7 and 11.8%, respectively). A high proportion of the canopy tree species flowered (68.8 and 87.5%, respectively). Similar bimodal distribution of flowering phenology was observed at the community level in both forests, although the total frequency of flowers was much greater in the Carpinus forest than in the Pinus forest. Tree and shrub life forms flowered from spring to summer, with two main flower types: wind-pollinated flowers (29.2 in Pinus-dominated forest and 14.3% in Carpinus-dominated forest) and dish-shaped, insect-pollinated flowers (66.7 and 76.2%, respectively). In contrast, herbs continued flowering until the autumn, and the proportion of funnel-shaped, insect-pollinated flowers was high. White flowers were most abundant for herb and shrub species.

Evolution of novel morphological and reproductive traits in a clade containing Antirrhinum majus (Scrophulariaceae)

Phylogenetic analysis of DNA sequences of the chloroplast genes rcbL and ndhf revealed a highly supported clade composed of the families Plantaginaceae, Callitrichaceae, and Hippuridaceae in close association with the model organism Antirrhinum majus and other members of family Scrophulariaceae. Plantago has miniature actinomorphic wind-pollinated flowers that have evolved from zygomorphic animal-pollinated precursors. The aquatic Hippuridaceae have reduced windpollinated flowers with one reproductive organ per whorl, and three, rather than four, whorls. In monoecious aquatic Callitrichaceae, further reduction has occurred such that there is only one whorl per flower containing a single stamen or carpel. Optimization of character states showed that these families descended from an ancestor similar to Antirrhinum majus. Recent studies of plant developmental genetics have focused on distantly related species. Differences in the molecular mechanisms controlling floral development between model organisms are difficult to interpret due to phylogenetic distance. In order to understand evolutionary changes in floral morphology in terms of their underlying genetic processes, closely related species exhibiting morphological Variation should be examined. Studies of genes that regulate morphogenesis in the clade described here could aid in the elucidation of a general model tot such fundamental issues as how changes in floral symmetry, organ number, and whorl number are achieved, as well as providing insight on the evolution of dicliny and associated changes in pollination syndrome.

Cecropia schreberiana in the Luquillo Mountains of Puerto Rico

Cecropia schreberiana Miq. (Cecropiaceae) is a common tree in the Luquillo Mountains of Puerto Rico because it is a pioneer that establishes abundantly after recurrent hurricanes that damage Luquillo forests. In these forestsC. schreberiana typically reaches about 20 m in height and 60 cm dbh and has few branches, these bearing large, deeply lobed leaves. The wood is light and weak. Unlike most of its congeners,C. schreberiana in Puerto Rico does not have symbiotic ants. It is dioecious and produces wind-pollinated flowers in spikes and abundant minute seeds broadly dispersed by birds and bats. Forest soils contain a high density of its seeds, which lie dormant until canopy opening stimulates germination. With adequate nutrientsC. schreberiana grows fast in high light, while nondominant individuals suffer heavy mortality. An individual of the species is thought to live 30 to 50 years.

Systematics of the Ericaceae, Empetraceae, Epacridaceae and Related Taxa Based Upon rbcL Sequence Data

The Ericaceae, Epacridaceae, and Empetraceae are usually recognized as closely related families of woody plants that share a preference for acidic soils, anthers that invert in development, and the presence of endosperm haustoria, among other characteristics. The Empetraceae are recognized as distinctive because of their often unisexual and wind-pollinated flowers. Epacridaceae are distinguished from Ericaceae by anthers that open by slits rather than pores and a primarily Australian distribution. Phylogenetic relationships of these related families are investigated using nucleotide sequences of the plastid gene rbcL. Parsimony analyses indicate a monophyletic, broadly defined Ericaceae that includes Empetraceae and Epacridaceae

Floral Aroma: How Far Will Plants Go to Attract Pollinators?

relationships between plants and insect pollinators challenge biologists ross-pollination is the transfer of pollen from anthers where it is produced to a flower stigma on a different plant. The value of cross-pollination is that it promotes gene mixing and results in greater vigor in the offspring. Because crosspollination is riskier than self-pollination, flowering plants have evolved many ways of ensuring its success. Plants that let the wind carry their pollen indiscriminantly to distant ovules must produce copious amounts of pollen to correct for inaccuracy of delivery. These plants, however, need produce only small, inconspicuous flowers. Other plants use biological agents to deliver their pollen, but at a cost of advertising for and paying the agents. Floral aroma is one example of flower advertisement, and in some cases may even act as compensation for pollination services. Wind-pollinated flowers may not emit aromas, nor may bird-pollinated flowers that rely on vivid red colors, which appear black to many insects (Faegri and van der Pijl 1979, Heinrich 1979b, von Frisch 1967). The origin and function of floral aroma have been of recent interest. The fossil record is incomplete but shows that plants with flowerlike structures and insects capable of evolving into pollinators began their radiations at about the same time

Transmission of Atkinsonella hypoxylon (Clavicipitaceae) by cleistogamous seed of Danthonia spicata (Gramineae)

Atkinsonella hypoxylon is a systemic parasite of the grasses Danthonia spicata, D. compressa, and Stipa leucotricha. The means by which this fungus and other Balansiae (Balansia, Balansiopsis, Epichloë, and Myriogenospora) are transmitted from one plant to another is poorly understood. Host grasses of A. hypoxylon normally produce spikelets of open, wind-pollinated chasmogamous flowers at the apex of the flowering culm and spikelets of self-pollinated cleistogamous flowers in the lower leaf sheaths of the same culm. Plants of D. spicata infected by A. hypoxylon regularly produce cleistogamous spikelets in the lowermost leaf sheaths, although chasmogamous spikelets are aborted by hypothallus development. Embryos of the seeds resulting from these flowers were surrounded by hyphae. The seeds were germinated and when the plants flowered, they produced deformed flowering culms and hypothalli, indicating that A. hypoxylon is transmitted from parent to offspring through cleistogamous seed.

A Hybrid of Gunnera from Costa Rica

A study of a number of morphological characters confirms the pres- ence of a hybrid between the two species of Costa Rican Gunnnera, G. insignis and G. talamancana. Despite wind pollination and similar habitat preferences among all known species, hybrids of Gunnera are rare in nature because the disturbed sites they prefer are so small and labile. Road building, especially of the Pan-American Highway, has established large areas of more or less permanently disturbed habitat allowing the populations of the two different species to interdigitate and hybridize. Gunnera Linneaus is one of the most striking plants of the tropical American cloud forest. Although G. chilensis Lamarck has been a popular ornamental in Europe since before the last century, the systematics of the genus are very poorly understood. Both the gigantic size of its organs (two meter wide leaves, meter and a half long inflorescences), which make it so impressive, and its relatively inaccessible habitat in nature, lead to great difficulty in collecting. Most herbarium collections are quite fragmentary, which obscures and confuses the taxonomy (Biloni, 1959; Palkovic, 1978). I have had the opportunity to study Gunnera in Costa Rica on four different occasions, in 1970, 1971, 1972 and 1973 for the preparation of a study on the genecology, population dynamics and adaptive strategy of G. insignis (Oersted) A. de Candolle. I have become intimately familiar with most of the populations in the country and have studied their size, distribution and composition. There are two species of Gunnera in Costa Rica, G. insignis and G. talamancana Weber & Mora. Gunnera insignis is a wide-ranging giant herb extending from Panama to Nicaragua, found at elevations from perhaps 500 m to over 3400 m. As is characteristic of all species in its subgenus (Panke (Molina) Schindler), it has a solitary, thick, semi-erect stem (pachy- caul), which bears a terminal rosette of rounded, lobed leaves. It does not branch, except through injury, and bears axillary inflorescences. A single inflorescence may bear tens of thousands of tiny, wind-pollinated flowers, each producing a single, minute drupelet. Gunnera insignis is a colonizer of naturally disturbed sites, such as landslides and streambanks. Recently it has become a highly successful colonizer of road cuts, waste spills and other disturbances associated with road building. Construction of the Pan-American Highway opened the higher ele- vations of the Cordillera de Talamanca in the mid-1950's. Weber and Mora (1958) described a new species, G. talamancana, growing along the newly laid road on the crest of the cordillera. Despite its more restricted range, it colonizes disturbed habitats in much the same way as G. insignis.