Floral biology of two Vanilloideae (Orchidaceae) primarily adapted to pollination by euglossine bees

Abstract

Vanilloideae comprises 15 genera distributed worldwide, among which are Vanilla and Epistephium (tribe Vanilleae). Based on field and laboratory investigations, the pollination biology of V. dubia and E. sclerophyllum was analysed. The former was surveyed in a semi-deciduous mesophytic forest at the biological reserve of Serra do Japi and in a marshy forest at the city of Pradópolis, southeastern Brazil. The latter was examined in rocky outcrop vegetation in the Chapada Diamantina, northeastern Brazil. In the studied populations, the tubular flowers of V. dubia and E. sclerophyllum were pollinated by bees. Pollen was deposited on either their scutellum (V. dubia) or scutum (E. sclerophyllum). The mentum region of V. dubia is dry, whereas that of E. sclerophyllum presents a small quantity of dilute nectar. Flowers of E. sclerophyllum are scentless, while those of V. dubia are odoriferous. Although V. dubia is self-compatible, it needs a pollinator to produce fruit. In contrast, E. sclerophyllum sets fruit through spontaneous self-pollination, but biotic pollination also occurs. Both species are primarily adapted to pollination by euglossine bees. Pollination by Euglossina seems to have occurred at least twice during the evolution of Vanilleae. Furthermore, shifts between rewarding and reward-free flowers and between autogamous and allogamous species have been reported among vanillas.

The uncommon cavitated secretory trichomes inBauhinia s.s.(Fabaceae): the same roles in different organs

“…Floral secretory trichomes associated with the production of fragrances in flowers have only been reported in Phragmipedium × grande (Rchb.f.) Rolfe, Cymbidium tracyanum L.Castle, Cyclopogon elatus (Sw.) Schltr., Vanilla dubia Hoehne (Orchidaceae; Vogel, ; Stpiczyńska, ; Wiemer et al ., ; Pansarin & Pansarin, ), Bulbine inflata Oberm. (Asphodelaceae; Naidoo et al ., ), Anadenanthera peregrina (Fabaceae; Marinho et al ., ), Aesculus hippocastanum L. (Sapindaceae; Chwil et al ., ), Citrus sinensis (L.) Osbeck (Rutaceae; Marques et al ., ), Jacaranda oxyphylla Cham.…”

“…Therefore, the presence of structures that are responsible for the synthesis and release of scent in their floral organs is expected. The vast majority of studies refer to such scent glands as epithelial osmophores (Vogel, ; Endress, ; Marinho et al ., ), with rare reports of trichomes acting in the long‐distance attraction of pollinators (see Vogel, ; Stpiczyńska, ; Guimarães, Di Stasi & Maimoni‐Rodella, ; Wiemer et al ., ; Naidoo et al ., ; Chwil et al ., ; Nadia, Menezes & Machado, ; Marinho et al ., ; Marques et al ., ; Pansarin & Pansarin, ; Boff et al ., ).…”

A new vanilla species from Costa Rica closely related to V. planifolia (Orchidaceae)

“…nov. compared to those of V. planifolia, it is unlikely that a bee capable of pollinating one of the two species would be able to pollinate the other. In addition to size compatibility, the probability of pollinator visits is frequently increased by the aromatic metabolites emitted by orchid flowers, which act as bee attractants (Ackerman 1986;Pansarin & Pansarin 2014). This is particularly important for vanilla flowers that are open a single day, which reduces the chances of pollen-pollinator encounter.…”

Phenodynamics of five orchids species growing on rock outcrops in the Chapada Diamantina Mountains in northeastern Brazil

“…Photoperiodicity has been found to be associated with breaking and/or induction of bud dormancy, making it the trigger for growth and flowering initiation in many plant species (Stevenson et al 2008). The high observed overlap of flowering between pairs of species with similar flower colors during the dry and rainy seasons (including E. lucidum which produces nectar) appears to be a viable reproductive strategy as most orchids mimic melittophilous flowers and, as they offer no floral rewards, are pollinated using deceit strategies (Pansarin & Pansarin 2014). The flowers of species utilizing deceit strategies will be visited less frequently than the flowers of species that offer some type of reward (as insects have the capacity to learn) -and will consequently show less fruiting (Borba & Semir 2001); as such, the high synchrony and overlapping between them presumably favors pollination processes by accentuating floral displays.…”

“…This diversity is associated with morphofunctional characters such as CAM metabolism and the presence of pseudobulbs that retain water resources for metabolic activities and facilitate survival in otherwise unfavorable environments (Silveira et al 2009;Arévalo et al 2011). There has been a notable lack of studies addressing the phenologies of the Orchidaceae family in Brazil, and the available information is generally restricted to records of their flowering periods and floral biology (Pansarin et al 2012;Pansarin & Pansarin 2014). Here, we evaluated the vegetative and reproductive phenological patterns of five Orchidaceae species (Cattleya elongata Barb.…”