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Low seed ovule ratios have been observed in natural populations of Polygala vayredae Costa, a narrowly endemic species from the oriental pre-Pyrenees. To evaluate physical and nutritional constraints and pollen tube attrition in this endemic species, stigma and style anatomy, as well as pollen tube development along the pistil were investigated using light(More)
BACKGROUND AND AIMS The effect of pollination on flower life span has been widely studied, but so far little attention has been paid to the reproductive consequences of delayed pollination in plants with long floral life spans. In the present study, Polygala vayredae was used to answer the following questions. (1) How does male and female success affect the(More)
Plant–pollinator interactions are one of the most important and variable mutualisms having major implications for plant fitness. The present study evaluates the interactions between an endemic milkwort, Polygala vayredae, and its floral visitors by studying the temporal variability, foraging behaviour and effectiveness of floral visitors in three(More)
Secondary pollen presentation is the relocation and presentation of pollen in floral structures (termed pollen presenters) other than the anthers. These pollen presenters are often found close to the stigma and have been hypothesized to increase the accuracy of pollen transfer, although no experimental studies have been done. We examined the function of the(More)
[1] We investigate by first‐principles the influence of iron on the elastic properties of the b–phase (wadsleyite) and g–phase (ringwoodite), polymorphs of olivine, the most abundant minerals of the upper and lower parts of the transition zone, respectively. Our study aims to complement experiments to understand details of the 410 km and 520 km(More)
The use of clays for therapeutic practice is widespread in almost all regions of the world. In this study the physicochemical and microbiological healing characteristics of a clay from Ocara, Brazil, popularly used for therapeutic uses, were analyzed. The presence of Ca, Mg, Al, Fe, and Si was observed, which initially indicated that the clay had potential(More)
I dedicate this dissertation to myself and all my family, friends and professors, my lovely girlfriend and my parents-in-law, who gave me all necessary support to get here. Acknowledgements The music " The long and winding road " written by Sir Paul McCartney translates all my feeling at the right moment I finished this work and I may have no words to(More)