title: Floral ultrastructure of two Brazilian aquatic-epiphytic bladderworts: Utricularia cornigera Studnička and U. nelumbifolia Gardner (Lentibulariaceae).
abstract: Utricularia cornigera and Utricularia nelumbifolia are giant, aquatic-epiphytic species of carnivorous bladderwort from southeastern Brazil that grow in the central 'urns' of bromeliads. Both species have large, colourful flowers. The main aim of our study is to ascertain whether the prominent floral palate of U. cornigera and U. nelumbifolia functions as an unguentarius-i.e. an organ that bears osmophores. Floral tissues of both species were investigated using light microscopy, scanning electron microscopy, transmission electron microscopy and histochemistry. Floral palates of U. cornigera and U. nelumbifolia provide clear visual signals for pollinating insects. In both species, the palate possesses diverse micro-morphology, comprising unicellular, conical to villiform papillae and multicellular, uniseriate, glandular trichomes that frequently display terminal branching. The most characteristic ultrastructural feature of these papillae was the presence of relatively large, polymorphic plastids (chromoplasts) containing many plastoglobuli. Similar plastids are known to occur in the fragrance-producing (osmophores) and oil-producing (elaiophores) tissues of several orchid species. Thus, these palate papillae may play a key role in providing the olfactory stimulus for the attraction of insect pollinators. Nectariferous trichomes were observed in the floral spurs of both species, and in U. nelumbifolia, free nectar was also recorded. The location, micro-morphology, anatomy and ultrastructure of the floral palate of the two species investigated may thus indicate that the palate functions as an unguentarius. Furthermore, the flowers of these taxa, like those of U. reniformis, have features consistent with bee pollination.
authors.affiliation: Department of Plant Cytology and Embryology, Jagiellonian University in Kraków, 9 Gronostajowa St., 30-387, Kraków, Poland. bartosz.plachno@uj.edu.pl.
authors.forename: Bartosz J
authors.initials: BJ
authors.lastname: Płachno
authors.affiliation: Faculty of Biology, University of Warsaw, Botanic Garden Al. Ujazdowskie 4, 00-478, Warsaw, Poland.
authors.forename: Małgorzata
authors.initials: M
authors.lastname: Stpiczyńska
authors.affiliation: School of Earth and Ocean Sciences, Cardiff University, Main Building, Park Place, Cardiff, CF10 3AT, UK.
authors.forename: Kevin L
authors.initials: KL
authors.lastname: Davies
authors.affiliation: Department of Animal Histology and Embryology, University of Silesia, 9 Bankowa St., 40-007, Katowice, Poland.
authors.forename: Piotr
authors.initials: P
authors.lastname: Świątek
authors.affiliation: Departamento de Biologia Aplicada à Agropecuária, Faculdade de Ciências Agrárias e Veterinárias, Univ Estadual Paulista-UNESP, Câmpus Jaboticabal, São Paulo, Brazil.
authors.forename: Vitor Fernandes Oliveira
authors.initials: VF
authors.lastname: de Miranda
mesh_terms: D059001:Aquatic Organisms / Q000648:ultrastructure / Q000821:virology*; D001938:Brazil; D035264:Flowers / Q000033:anatomy & histology / Q000166:cytology / Q000648:ultrastructure*; D007150:Immunohistochemistry; D019686:Lamiaceae / Q000033:anatomy & histology / Q000166:cytology / Q000648:ultrastructure*; D057048:Plant Nectar
chemical_list: D057048:Plant Nectar
keywords: Bladderwort; Carnivorous plant; Floral micro-morphology; Lentibulariaceae; Osmophore; Palate; Pollination; Sect. Iperua; Ultrastructure