Search results for "Pollen"
showing 10 items of 302 documents
Degradation of sexual reproduction in Veronica filiformis after introduction to Europe
2011
Abstract Background Baker’s law predicts that self-incompatible plant species are generally poor colonizers because their mating system requires a high diversity of genetically differentiated individuals and thus self-compatibility should develop after long-distance dispersal. However, cases like the introduction of the self-incompatible Veronica filiformis (Plantaginaceae) to Europe constitute an often overlooked alternative to this rule. This species was introduced from subalpine areas of the Pontic-Caucasian Mountains and colonized many parts of Central and Western Europe in the last century, apparently without producing seeds. To investigate the consequences of the absence of sexual rep…
Pollination biology in Roepera (Zygophyllaceae): How flower structure and shape influence foraging activity
2019
The foraging behavior of bees is a complex phenomenon that depends on numerous physical features of flowers. Of particular importance are accessibility of floral rewards, floral proportions, symmetry and orientation. The flowers of Roepera are characterized by the presence of staminal scales (SS), which play an important role in nectar protection. We studied two species of Roepera with different symmetry and flower orientation, which are mainly visited by honeybees (Apis mellifera). We aimed to show how the foraging behavior of honey bees is affected by the function of SS, floral symmetry and orientation. The foraging behavior was documented by video photography. Handling time, access to ne…
The plasticity of breeding system in arid-adapted Zygophylloideae
2019
Abstract The assurance of reproductive success is an important challenge for arid-adapted plants. Self-compatibility is suggested as a mechanism to compensate for the inadequate breeding opportunities in extreme environments. Zygophylloideae is an arid-adapted subfamily which has successfully radiated in different ranges of arid habitats. In order to study the significance of selfing for the reproductive success of the Zygophylloideae, we calculated pollen ovule ratios (P/O) and conducted bagging experiments for autogamy and xenogamy in eleven representative members of Zygophylloideae and three species of the sister subfamilies Tribuloideae and Larreoideae. Our results revealed an extremely…
Fine-scale spatial genetic structure and gene dispersal in Silene latifolia
2010
Plants are sessile organisms, often characterized by limited dispersal. Seeds and pollen are the critical stages for gene flow. Here we investigate spatial genetic structure, gene dispersal and the relative contribution of pollen vs seed in the movement of genes in a stable metapopulation of the white campion Silene latifolia within its native range. This short-lived perennial plant is dioecious, has gravity-dispersed seeds and moth-mediated pollination. Direct measures of pollen dispersal suggested that large populations receive more pollen than small isolated populations and that most gene flow occurs within tens of meters. However, these studies were performed in the newly colonized rang…
Small sweat bees (Hymenoptera: Halictidae) as potential major pollinators of melon (Cucumis melo) in the Mediterranean
2016
In the current scenario of a general decline of the honeybee worldwide, studies on the potential of alternative bee species in pollinating cultivated plants are important. Although melon, Cucumis melo, is a crop with great commercial importance, there is very little information on its pollinating fauna in Europe, and none from the southern Mediterranean area. In a locality in central Spain, using both pan-traps and net collections, we found that melon flowers are visited by 31 species of bees spanning four families, though only four were both dominant and constant. These four species belonged to the family Halictidae (sweat bees) and mostly (three species) to the genus Lasioglossum. Five ot…
The Eurasian Modern Pollen Database (EMPD), version 2
2020
The Eurasian (née European) Modern Pollen Database (EMPD) was established in 2013 to provide a public database of high-quality modern pollen surface samples to help support studies of past climate, land cover, and land use using fossil pollen. The EMPD is part of, and complementary to, the European Pollen Database (EPD) which contains data on fossil pollen found in Late Quaternary sedimentary archives throughout the Eurasian region. The EPD is in turn part of the rapidly growing Neotoma database, which is now the primary home for global palaeoecological data. This paper describes version 2 of the EMPD in which the number of samples held in the database has been increased by 60% from 4826 to…
Light availability affects sex lability in a gynodioecious plant.
2016
PREMISE OF THE STUDY: Sex lability (i.e., gender diphasy) in plants is classically linked to the larger resource needs associated with the female sexual function (i.e., seed production) compared to the male function (i.e., pollen production). Sex lability in response to the environment is extensively documented in dioecious species, but has been largely overlooked in gynodioecious plants. METHODS: Here, we tested whether environmental conditions induce sex lability in the gynodioecious Geranium sylvaticum. We conducted a transplantation experiment in the field where plants with different sex expression were reciprocally transplanted between high light and low light habitats. We measured pla…
Staying alive on an active volcano: 80 years population dynamics of Cytisus aeolicus (Fabaceae) from Stromboli (Aeolian Islands, Italy)
2020
Abstract Cytisus aeolicus is a narrow endemic species restricted to the Aeolian archipelago (SE Tyrrhenian Sea, Italy) and it is one of the most evolutionarily isolated plants in the Mediterranean flora. Historical and literature data suggest that both metapopulations and isolated individuals of C. aeolicus are gradually shrinking. Field investigations and drone images demonstrate that the C. aeolicus metapopulation from Stromboli experienced a strikingly fast increase during the last decades. As of 2019, more than 7000 ± 3000 mature individuals occur on Stromboli, i.e. 14 to 20 times more than those counted during the last census, 25 years ago. The diachronic analysis of aerial photos conc…
Morphological observations on the reproductive structures of Ambrosina (Araceae), a Mediterranean endemic monotypic genus
2017
This research was carried out to better define the pollen, fruit and seed morphology of Ambrosina bassii , the only species of this rare Mediterranean endemic genus. Pollen traits were already known, but here we investigated on their variability in distant populations and in different morphotypes (‘varieties’). Fruit and seed traits were almost unknown, also because of the rarity of fruit-set in this species. The surface features of pollen, fruit and seed, as well as length, width and length/width ratio, were analysed by means of scanning electron microscopy (SEM). Comparative observations were made also on Arisarum vulgare , since Arisarum is the closest genus. The principal component anal…
Millerandage and flower abscission in ‘Grillo’, ‘Frappato’ and ‘Nero d’Avola’ grapevines: Some probable causes
2018
Some Sicilian cultivars, in particular vintage, showed a high percentage of flower abscissions and shot berries. In this paper, to understand these phenomena, some aspects of the flower morphology of three Sicilian cultivars (two black: ‘Nero d’Avola’ and ‘Frappato’; and one white: ‘Grillo’) was studied. The number of stamens, ovule adherence to the ovary wall and pollen germination were evaluated using standard light microscopy. At harvest, seed number was counted on 30 berries per cultivar. The percentage of six stamens was lowest in ‘Frappato’ and highest in ‘Grillo’. The ovule adherence to the ovary wall was highest in ‘Frappato’ and lowest in ‘Nero d’Avola’. The percentage of pollen ge…