Buzz pollination in eight bumblebee-pollinated Pedicularis species: does it involve vibration-induced triboelectric charging of pollen grains?

Background And Aims: Buzz pollination involves explosive pollen release in response to vibration, usually by bees. The mechanism of pollen release is poorly understood, and it is not clear which component of vibration (acceleration, frequency, displacement or velocity) is critical; the role of buzz frequency has been particularly controversial. This study proposes a novel hypothesis that explosive pollen release results from vibration-induced triboelectric charging.

In the right place at the right time: Parnassia resolves the herkogamy dilemma by accurate repositioning of stamens and stigmas.

Background And Aims: Spatial (herkogamy) and temporal (dichogamy) separation of pollen presentation and stigma receptivity have been interpreted as reducing interference between male and female functions in hermaphroditic flowers. However, spatial separation leads to a potential conflict: reduced pollination accuracy, where pollen may be placed in a location on the pollinator different from the point of stigma contact.

Methods: To understand better how herkogamous flowers resolve this conflict, a study was made of a subalpine herb, Parnassia epunctulata, the nectariferous flowers of which exhibit sequential anther dehiscence (staggered pollen presentation) and stamen movements; usually one newly dehisced anther is positioned each day over the central gynoecium, while the older stamens bend away from the central position.

Native or Exotic? Double or Single? Evaluating Plants for Pollinator-friendly Gardens.

In a series of dawn-to-dusk studies, we examined the nature and accessibility of nectar rewards for pollinating insects by monitoring insect visits and the secretion rate and standing crop of nectar in the British native plant species Salvia pratensis , Stachys palustris , S. officinalis , Lythrum salicaria , Linaria vulgaris , the non-native Calendula officinalis , Petunia  ×  hybrida , Salvia splendens , and the possibly introduced Saponaria officinalis . We also compared single with double variants of Lotus corniculatus , Saponaria officinalis , Petunia  ×  hybrida and Calendula officinalis .

Fruit and seed production in relation to pollination and resources in bluebell, Hyacinthoides non-scripta.

This paper explores spatial and temporal patterns in the interaction of pollination and resources as constraints on the initiation and maturation of fruits and seeds in bluebell (Hyacinthoides non-scripta, Liliaceae). Field and laboratory experiments showed a degree of self-incompatibility (cross-pollination gave greater seed and fruit numbers than self-pollination), and pollinator limitation (hand cross-pollination gave greater seed and fruit numbers than open-pollination) as well as␣resource limitation. Bud removal, designed to relax interfruit competition for resources in the remaining flowers, increased percent fruit maturation in unpollinated flowers and increased the percent of initiated seeds that matured in cross-pollinated flowers.

Why do nectar-foraging bees and wasps work upwards on inflorescences?

Wasps (Dolichovespula and Vespula spp.) worked predominantly upwards when foraging for nectar on inflorescences of the protogynous Scrophularia aquatica, in which the standing crop of nectar sugar per flower showed no clear pattern of vertical distribution up an inflorescence. Bumblebees taking nectar (Bombus hortorum visiting legally, and certain individuals of B.

The nectar of Justicia and Columnea: Composition and concentration in a humid tropical climate.

Studies in Costa Rica on two ornithophilous flowers, Justicia aurea (Acanthaceae) and Columnea glabra (Gesneriaceae) showed a constancy of nectar solute concentrations that was attributed to microclimatic protection by the tubular corolla and to copious nectar secretion, helped by waterproofing by a lipid film on the nectar surface in Justicia and by preferential compass orientation of the flowers of Columnea.Most of the corollas in the patch of Justicia had been pierced by nectar-robbers. A consequence of this damage, together with local microclimate effects, was flower-to-flower variation in the amount and accessibility of nectar and in the nature and concentration of its minor components, notably amino acids.