Flower orientation in Gloriosa superba (Colchicaceae) promotes cross-pollination via butterfly wings

Abstract

Background and Aims Complex modifications of angiosperm flowers often function for precise pollen placement on pollinators and to promote cross-pollination. We explore the functional significance of the unusually elaborate morphology of Gloriosa superba flowers, which are divided into one hermaphrodite meranthium and five male meranthia (functional pollination units of a single flower). Methods We used controlled pollination experiments, floral measurements, pollen load analyses and visitor observations in four populations of G. superba in South Africa to determine the breeding system, mechanism of pollination and role of flower in the promotion of cross-pollination. Key Results We established that G. superba is self-compatible, but reliant on pollinators for seed production. Butterflies, in particular the pierid Eronia cleodora, were the primary pollinators (>90 % of visitors). Butterflies brush against the anthers and stigma during nectar feeding and pollen is carried on their ventral wing surfaces. Butterfly scales were positively correlated with the number of pollen grains on stigmas. We demonstrate that the styles were orientated towards clearings in the vegetation and we confirm that the highest proportion of initial visits was to hermaphrodite meranthia pointing towards clearings. Conclusions The flower morphology of G. superba results in effective pollen transfer on the wings of butterfly visitors. The style-bearing hermaphrodite meranthium of the flowers orientates towards open spaces in the vegetation, thus increasing the probability that butterflies land first on the hermaphrodite meranthium. This novel aspect of flower orientation is interpreted as a mechanism that promotes cross-pollination.

The enantiostylous floral polymorphism of Barberetta aurea (Haemodoraceae) facilitates wing pollination by syrphid flies

“…Wing pollination has now been recorded in at least eight plant families and is strongly associated with highly exserted styles and stamens, often in a brush arrangement ( Butler and Johnson, 2020 ). It has been reported previously for flowers pollinated by butterflies ( Cruden and Hermann-Parker, 1979 ; Kiepiel and Johnson, 2014 ; Epps et al , 2015 ; Butler and Johnson, 2020 ; Daniels et al , 2020 ) and bees ( Holmqvist et al , 2005 ; Minnaar and Anderson, 2021 ), but the present study is, to our knowledge, the first known case involving flies. The traits associated with wing pollination systems are not fully elucidated, but one common feature appears to be pollen grains that are very sticky.…”

“…Adaptations of plants for transfer of pollen on insect wings is increasingly being recognized as being an important factor in the evolution of complex floral morphology ( Butler and Johnson, 2020 ; Daniels et al , 2020 ). Wing pollination has now been recorded in at least eight plant families and is strongly associated with highly exserted styles and stamens, often in a brush arrangement ( Butler and Johnson, 2020 ).…”

Online community photo-sharing in entomology: a large-scale review with suggestions on best practices

“…Behaviors that have been documented through community photographs include predator–prey interactions (Hernandez et al 2019, Priyadarshana 2021) and communal prey subduction (Forthman and Weirauch 2012), parental care of eggs (Leocádio et al 2020) and young (Giribet and Moreno-González 2021), phoretic associations (Parks 2016), oviposition and egg-laying sites (Early 2019, Heraty et al 2019), nectar robbing (Fateryga 2021), spider web decorating (Kerr 2021), and mating behavior (Matteini Palmerini 2013, Dioli and Zanetti 2019, Ament et al 2021). Other ecological and natural history discoveries include host and food records for herbivorous (Pérez Hidalgo et al 2009, Wheeler 2017b, Roets et al 2019), fungivorous (Macias et al 2019), saproxylic (Muscarella et al 2013), coprophagic (Deschodt et al 2021), parasitic (Paiero et al 2021), and predatory arthropods (Forthman and Weirauch 2012, Gordon and Weirauch 2016, Powell et al 2021), including arthropods preying on vertebrates (Nyffeler and Altig 2020, Nyffeler and Whitfield 2021), the first feeding record for a family (Skvarla et al 2016a), pollinator host records (Wilson et al 2020, Aripin et al 2021), pollinator bias across flower species (Villalona et al 2020, Catron 2021), pathogen surveys (Douch and Poupa 2021), habitat (Deschodt et al 2021) and nest site preference (Maher et al 2019, Saunders et al 2021), how flower orientation affects pollination via butterfly wings (Daniels et al 2020), and prevalence of cooperative nest founding (Sheehan et al 2015).…”

Characterizing each step of pollination in Phlox drummondii reveals that a single butterfly species predominates in the pollinator assemblage

“…Although these kinds of data exist for some plant groups, our knowledge is far from complete. Notably, the distribution of these data is uneven across biological systems, with relatively fewer examples of butterfly pollination compared to other insects (e.g., bees; Weiss, 2001; Mertens et al, 2021; but see Epps et al, 2015; Daniels et al, 2020; Kiepiel and Johnson, 2021).…”