Two novel reports of semidry stigmatic surface in Asteraceae

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Intercellular pectic protuberances in Hymenaea stigonocarpa (Fabaceae, Caesalpinioideae): Occurrence and functional aspects

A study of the anatomy and ultrastructural aspects of leaf mesophyll and floral nectaries of Hymenaea stigonocarpa Mart. ex Hayne revealed the presence of intercellular pectic protuberances (IPPs) linking adjacent cells in both the leaf palisade cells and the secretory parenchyma of the floral nectary. Samples of the middle third of the leaf blade and of floral nectaries in anthesis were collected, fixed, and processed using standard procedures for light, transmission, and scanning electron microscopies. The IPPs of palisade cells of the mesophyll and the secretory parenchyma cells of the floral nectary take the form of scalae or strands, respectively. No evidence of the specific synthesis of these structures was observed, and they are apparently formed by the separation of adjacent cells due to cell expansion, when intercellular spaces develop. The IPPs observed in H. stigonocarpa increase cellular contact and probably act in apoplastic transport.

Pollination Biology of Jacaranda oxyphylla with an Emphasis on Staminode Function

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Effect of gibberellic acid on the quality of chrysanthemum (Dendranthema grandiflora L.) cv. Faroe

The aim of the present work was to evaluate the quality of chrysanthemum cultivar Faroe, subjected to different gibberellic acid (GA(3)) concentrations applied to the field. The treatments were composed of four doses of GA(3) (0, 15, 30 and 45 mg L-1) applied at the beginning of the formation of buttom floral (28 days after transplanting of seedlings). According to the results, a single low concentration of GA(3) application did not interfere with the phenotypic characteristics of the chrysanthemum cultivar Faroe.

Repeated unrewarded scent exposure influences the food choice of stingless bee foragers, Melipona scutellaris

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

The Effects of Nectar-Robbing on Fruit Production in Sparattosperma leucanthum (Bignoniaceae)

Many animals behave as robbers or thieves of floral resources, causing damage to floral tissues or consuming resources used to attract pollinators, or producing effects similar to emasculation by reducing the pollen load in the anthers (which generally results in losses in terms of sexual reproduction). The present work examined the direct and indirect impacts caused by nectar-robbing on the reproductive success of Sparattosperma leucanthum. Different manipulations of the flowers were tested to determine if fruit production was influenced by the perforations made in the floral tissues (direct damage), and if there were changes in visitation frequencies or in the behaviors of effective pollinators (indirect damage). Perforations made by nectar robbers did not lower the reproductive success of the plant species studied. The bee Trigona spinipes was the most frequent visitor and caused the largest perforations in the calyx and corolla of S. leucanthum. Additionally, we noted the occurrence of pollen theft by this same bee in flowers that had been protected against nectar-robbing. These results suggest that if S. leucanthum had developed a mechanism of resistance to robbery by T spinipes it would probably have experienced even lower pollination levels as a result of reductions in the quantities of pollen available for transfer by effective pollinators. We were not able to evaluate if nectar depletion through robbery modified the behavior of the effective pollinators (bumblebees of the genus Bombus).

Bee Visitors of Quaresmeira Flowers (Tibouchina granulosa Cogn.) in the Region of Dourados (MS-Brasil)

This research was developed in the center-urban area at the city of Dourados (MS), in Tibouchina granulosa trees, a plant popularly known as quaresmeira in Brazil. The floral visitors of this species were recorded in three daily periods: 7 - 8 a.m., 1 - 2 p.m. and 4 - 5 p. m. Bee visitors of those plants were collected with an entomological net when they landed on the flowers. The bees were anesthetized in a closed camera containing etila acetate, conserved in Dietrich ' s fixative and, soon afterwards, transferred to 70% ethyl alcohol for subsequent identification. Almost 300 specimens of Africanized Apis mellifera, Trigona spinipes and Tetragonisca angustula were collected. The presence of these three species of bees in the flowers of T. granulosa suggests that they can be considered the main floral visitors of that vegetal species. T. angustula workers did not visit the flowers of T. granulosa between 7 and 8 a.m., but they were the main floral visitors from 4 to 5 p.m. The workers of T. spinipes presented a very aggressive behavior against the Africanized A. mellifera workers on the quaresmeira flowers, defending the food sources with strength and efficiency and provoking a drastic reduction in the number of honeybee visits between 1 and 2 p.m. Nevertheless, they did not interfere in the opportunistic activity of foraging by T. angustula workers, mainly between 4 and 5 p.m. The most important result of this research was the detection of the Competitive Exclusion Principle between A. mellifera and T. spinipes species in relation to the foraging behavior, when they exploit the floral resources of T. granulosa.

Nectaries and reproductive biology of Croton sarcopetalus (Euphorbiaceae)

Flower morphology, nectary structure, nectar chemical composition, breeding system, floral visitors and pollination were analysed in Croton sarcopetalus, a diclinous-monoecious shrub from Argentina. Male flowers have five receptacular nectaries, with no special vascular bundles, that consist of a uniserial epidermis with stomata subtended by a secretory parenchyma. Female flowers bear two different types of nectaries: inner (IN) and outer (ON) floral nectaries. IN, five in all, are structurally similar to the nectaries of male flowers. The five ON are vascularized, stalked, and composed of secretory, column-shaped epidermal cells without stomata subtended by secretory and ground parenchyma. In addition, ON act as post-floral nectaries secreting nectar during fruit ripening. Extrafloral nectaries (EFN) are located on petioles, stipules and leaf margins. Petiolar EFN are patelliform, stalked and anatomically similar to the ON of the female flower. Nectar sampled from all nectary types is hexose dominant, except for the ON of the female flower at the post-floral stage that is sucrose dominant. The species is self-compatible, but geitonogamous fertilization is rarely possible because male and female flowers are not usually open at the same time in the same individual, i.e. there is temporal dioecism. Flowers are visited by 22 insect species, wasps being the most important group of pollinators. No significant differences were found in fruit and seed set between natural and hand pollinated flowers. This pattern indicates that fruit production in this species is not pollen/pollinator limited and is mediated by a wide array of pollinators. (C) 2001 the Linnean Society of London.

Polinização e dispersão de sementes em Myrtaceae do Brasil

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

The movement of involucral bracts of Syngonanthus elegans (Eriocaulaceae-Poales): Anatomical and ecological aspects

Syngonanthus elegans flowers are distributed in capitula whose involucral bracts open and close in a diurnal rhythm. The anatomy of these bracts was studied to understand how such movements occur and how it influences reproductive ecology of the species. The involucral bracts have a single layered epidermis composed of thick-walled cells on the abaxial surface, which are responsible for the movement. Since they are hygroscopic, these cells swell when they absorb water from the surrounding environment, causing the bracts to bend and the capitula to close. In natural conditions, the capitula open by day, when temperature increases and the relative air humidity decreases, and close at night, when temperature decreases and the relative air humidity increases. The involucral bracts may thus protect the flowers from abiotic factors, exposing them only at the time of the day when temperature is higher and insects are more active, favoring pollination by small insects. The closed capitula do not only protect the flowers, but they also function as a shelter for floral visitors as Brachiacantha australe (Coccinellidae) and Eumolpini sp. (Chrysomelidae). These small Coleoptera pollinate the flowers of S. elegans during the day and remain within the closed capitula during the night, in a possible mutualistic relationship. (C) 2008 Elsevier GmbH. All rights reserved.

Flower morpho-anatomy in Epiphyllum phyllanthus (Cactaceae)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Anatomical aspects of the gynoecium of species of Anthurium sect. Urospadix Engl. (Araceae, Alismatales)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Effects of self-, chase and mixed self/cross-pollinations on pistil longevity and fruit set in Ceiba species (Bombacaceae) with late-acting self-incompatibility

Background and aims Late-acting self-incompatibility (LSI). in which selfed flowers fail to form fruits despite apparently successful growth of the pollen tubes to the ovules, is a contentious and still poorly understood phenomenon. Some studies have indicated pollen tube-pistil interactions, and major gene control. Others favour an early acting inbreeding depression explanation.Methods Experimental pollinations, including selfs (in a subsample of which the style was cut before pollen tubes reached the ovary), chase self/cross-pollinations, crosses, and mixed self/cross-pollinations were used to study floral/pistil longevity and effect on fruit set and seed yield in two Ceiba species known to have LSI.Results Self-pollinations, including those with a cut style, had extended floral longevity compared with unpollinated flowers. Chase pollinations in which cross-pollen was applied up to 3 h after selfing set fruits, but with reduced seed set compared with crosses. Those with cross-pollen applied at 4 and 8 h after self-pollination all failed to set fruits. Flowers subjected to 1 : 1 and 2 : 1 self/cross-pollinations all produced fruits but again with a significantly lower seed set compared with crosses.Conclusions Extended floral longevity initiated with self-pollen tubes growing in the style indicates some kind of pollen tube-pistil interaction. Fruit set only in chase pollinations up to 3 h implies that self-pollen tubes either grow more slowly in the style or penetrate ovules more slowly on arrival at the ovary compared with cross-tubes. This agrees with previous observations indicating that the incidence of penetrated ovules is initially lower in selfed compared with crossed pistils. However, the low seed yield from mixed pollinations indicates that self- and cross-pollen tubes arrive at the ovary and penetrate ovules more or less simultaneously. Possible explanations for these discordant results are discussed. (C) 2004 Annals of Botany Company.

Trait-mediated effects on flowers: Artificial spiders deceive pollinators and decrease plant fitness

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)