Neither nectar nor deception: the role of floral rewards in the pollination system of Laelia (Orchidaceae: Laeliinae).

Orchids offer a variety of floral rewards to pollinators. In many orchid groups, however, the transfer of pollen is based on food-deception, as in the case of Laelia (including Schomburgkia s.s.

Labellar Structure of the Alliance (Orchidaceae: Maxillariinae) Indicates Floral Polyphenols as a Reward for Stingless Bees.

Several studies have reported stingless Meliponini bees gathering hairs from the labella of spp., including , a member of the alliance. Such hairs usually contain food materials and are thought to have nutritional value.

The Influence of Exogenous Jasmonic Acid on the Biosynthesis of Steroids and Triterpenoids in Plants and Hairy Root Culture.

The interplay between steroids and triterpenoids, compounds sharing the same biosynthetic pathway but exerting distinctive functions, is an important part of the defense strategy of plants, and includes metabolic modifications triggered by stress hormones such as jasmonic acid. Two experimental models, hairy root cultures and greenhouse cultivated plants (pot plants), were applied for the investigation of the effects of exogenously applied jasmonic acid on the biosynthesis and accumulation of steroids and triterpenoids, characterized by targeted GC-MS (gas chromatography-mass spectroscopy) metabolomic profiling. Jasmonic acid elicitation strongly increased triterpenoid saponin production in hairy root cultures (up to 86-fold) and their release to the medium (up to 533-fold), whereas the effect observed in pot plants was less remarkable (two-fold enhancement of saponin biosynthesis after a single foliar application).

Evidence of floral rewards in Brasiliorchis supports the convergent evolution of food-hairs in Maxillariinae.

Premise: Angiosperms distributed over a large geographical area may display considerable phenotypic variation that can be recognized at morphological and micromorphological levels. Here, we investigate the pollination biology and the presence of floral rewards in Brazilian populations of the widely distributed orchid, Brasiliorchis picta. Based on the new data presented here this study investigates the evolution of floral rewards in Maxillariinae, and tests for the occurrence of convergent evolution of food-hairs in this subtribe.

Nectar secretion in a dry habitat: structure of the nectary in two endangered Mexican species of (Orchidaceae).

and are endangered, endemic taxa from Mexico. They are epiphytes adapted to dry habitats. Since these plants are xerophytic, their flowers were investigated for structural adaptations to nectar secretion.

Floral micromorphology and nectar composition of the early evolutionary lineage Utricularia (subgenus Polypompholyx, Lentibulariaceae).

Utricularia (Lentibulariaceae) is a genus comprising around 240 species of herbaceous, carnivorous plants. Utricularia is usually viewed as an insect-pollinated genus, with the exception of a few bird-pollinated species. The bladderworts Utricularia multifida and U.

Functional Diversity of Nectary Structure and Nectar Composition in the Genus (Liliaceae).

is a genus consisting of 130 to 140 species of bulbous plants, native to temperate regions of the northern hemisphere. Generally viewed as an insect pollinated genus with the exception of two North American species, and , which are described as hummingbird-pollinated and the Asian species, , described as passerine-pollinated. These pollinator shifts are possibly the result of adaptive changes to the structure and morphology of the nectary, as well as a change in the nectar concentration and composition.

Floral micromorphology of the bird-pollinated carnivorous plant species Utricularia menziesii R.Br. (Lentibulariaceae).

Background And Aims: Bird pollination is rare among species in the genus Utricularia, and has evolved independently in two lineages of this genus. In Western Australia, the Western Spinebill, Acanthorhynchus superciliosus, visits flowers of Utricularia menziesii (section Pleiochasia: subgenus Polypompholyx). This study aimed to examine the micromorphology of U.

Spatiotemporal variation in the pollination systems of a supergeneralist plant: is Angelica sylvestris (Apiaceae) locally adapted to its most effective pollinators?

Background And Aims: In terms of pollination systems, umbellifers (plants of the carrot family, Apiaceae) are regarded as generalists, since their (usually dichogamous) flowers are visited by a wide range of insects representing several taxonomic orders. However, recent analyses of insect effectiveness revealed that these plants may be pollinated effectively by a narrow assemblage of insect visitors. Of particular interest was whether populations of an umbellifer species varied in pollinator assemblages and whether this could lead to local specialization of the pollination system.

Nectar-Secreting and Nectarless : Structure of the Inner Floral Spur.

, the largest genus of Neotropical orchids, contains both nectar-secreting and nectarless species. Here, we compare the fine structure of the inner floral spur, termed the cuniculus, in nectariferous (, ) and seemingly nectarless (, , ) species. This is the first time for such a detailed investigation of cuniculus structure to be undertaken for Our aim was to characterize features indicative of secretory activity and to ascertain whether flowers presumed to be nectarless produce alternative pollinator food-rewards.

Flower palate ultrastructure of the carnivorous plant Genlisea hispidula Stapf with remarks on the structure and function of the palate in the subgenus Genlisea (Lentibulariaceae).

In the genus Genlisea as well as in its sister genus Utricularia, the palate probably plays a key role in providing the colour, mechanical and olfactory stimuli to attract insect pollinators and to guide them to the generative structures and the nectary spur. However, information about the micro-morphology of the palate of Genlisea is scarce. This study aims to examine the structure of the palate in Genlisea hispidula in detail as well as the palate from other five species from the subgenus Genlisea.

Nectar trichome structure of aquatic bladderworts from the section Utricularia (Lentibulariaceae) with observation of flower visitors and pollinators.

In Utricularia, the flower spur is a nectary and in this organ, nectar is produced and stored. This study aimed to examine the structure of the nectary trichomes in four Utricularia species (Utricularia vulgaris L., U.

Nectar and oleiferous trichomes as floral attractants in Bulbophyllum saltatorium Lindl. (Orchidaceae).

Although many Orchidaceae have deceit flowers that produce no reward, the most common reward, when present, is nectar. Bulbophyllum, however, is unusual in that the labellar secretions of most species investigated to date lack sugars, and, therefore, cannot be considered true nectar. The African species Bulbophyllum saltatorium is an exception in that it produces not only nectar but also possesses specialized, capitate oleiferous trichomes.

Flower palate structure of the aquatic bladderworts Utricularia bremii Heer and U. minor L. from section Utricularia (Lentibulariaceae).

There is an enormous diversity in the structure of the flower palate of the carnivorous rootless genus Utricularia. This study aims to examine the structure of the palates in Utricularia bremii Heer and U. minor L of the Utricularia sect.

Floral micromorphology of the Australian carnivorous bladderwort Utricularia dunlopii, a putative pseudocopulatory species.

Flowers of sexually deceptive taxa generally possess a set of morphological and physiological characters that mimic their insect pollinators. These characters often include a specific insect-like floral configuration, together with scent glands (osmophores) that produce fragrances which chemically resemble insect sex pheromones. Furthermore, these flowers tend not to produce pollinator food rewards.

Floral ultrastructure of two Brazilian aquatic-epiphytic bladderworts: Utricularia cornigera Studnička and U. nelumbifolia Gardner (Lentibulariaceae).

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.

Labellar anatomy and secretion in Bulbophyllum Thouars (Orchidaceae: Bulbophyllinae) sect. Racemosae Benth. & Hook. f.

Background And Aims: Floral secretions are common in Bulbophyllum Thouars, and the labella of a number of Asian species are said to produce secretions rich in lipids that act as food rewards for insect pollinators. Although some of these reports are based on simple histochemical tests, a much greater number are anecdotal and, hitherto, neither the ultrastructure of the labellum nor the secretory process has been investigated in detail. Furthermore, sophisticated histochemical approaches have generally not been applied.

Comparative anatomy of floral elaiophores in Vitekorchis Romowicz & Szlach., Cyrtochilum Kunth and a florally dimorphic species of Oncidium Sw. (Orchidaceae: Oncidiinae).

Background And Aims: Recently, molecular approaches have been used to investigate the phylogeny of subtribe Oncidiinae, resulting in the re-alignment of several of its genera. Here, a description is given of the structure of the floral elaiophores (oil glands) of four species formerly assigned to Oncidium Sw. Those of Vitekorchis excavata (Lindl.

Floral elaiophores in Lockhartia Hook. (Orchidaceae: Oncidiinae): their distribution, diversity and anatomy.

Background And Aims: A significant proportion of orchid species assigned to subtribe Oncidiinae produce floral oil as a food reward that attracts specialized bee pollinators. This oil is produced either by glabrous glands (epithelial elaiophores) or by tufts of secretory hairs (trichomal elaiophores). Although the structure of epithelial elaiophores in the Oncidiinae has been well documented, trichomal elaiophores are less common and have not received as much attention.

Comparative anatomy of the floral elaiophore in representatives of the newly re-circumscribed Gomesa and Oncidium clades (Orchidaceae: Oncidiinae).

Background And Aims: Recently, molecular approaches have been used to investigate the phylogeny of Oncidiinae. This has resulted in the transfer of taxa previously considered to be species of Oncidium Sw. into Gomesa R.

Floral elaiophore structure in four representatives of the Ornithocephalus clade (Orchidaceae: Oncidiinae).

Background And Aims: A significant number of species assigned to the Neotropical orchid sub-tribe Oncidiinae reward insect pollinators with oil produced in floral glands termed elaiophores. The latter may be glabrous (epithelial elaiophores) or hirsute (trichomal elaiophores). Although the detailed anatomy and ultrastructure of epithelial elaiophores have been studied for a number of genera, such as Oncidium Sw.

Comparative labellar micromorphology of Zygopetalinae (Orchidaceae).

Background And Aims: Molecular evidence indicates that the Neotropical sub-tribe Zygopetalinae is sister to Maxillariinae. Most members of the latter sub-tribe have deceit pollination strategies, but some species produce rewards such as nectar, pseudopollen, resin and wax, and are pollinated by a range of pollinators that include stingless bees (Meliponini), wasps and hummingbirds. By contrast, relatively little is known about the pollination of Zygopetalinae species.

Comparative anatomy of the nectary spur in selected species of Aeridinae (Orchidaceae).

Background And Aims: To date, the structure of the nectary spur of Aeridinae has not been studied in detail, and data relating to the nectaries of ornithophilous orchids remain scarce. The present paper compares the structural organization of the floral nectary in a range of Aeridinae species, including both entomophilous and ornithophilous taxa.

Methods: Nectary spurs of Ascocentrum ampullaceum (Roxb.

Do plants dynamically regulate nectar features through sugar sensing?

Nectar properties (volume, concentration, viscosity) change dynamically in time. As stated by Pedersen some decades ago (1958), "Nectar is not a static product remaining outside the plant once produced but is in close contact with the plant system."1 It is now evident that secretion may occur concomitantly with resorption and that the latter process sometimes continues after secretion has ended.

Comparative histology of floral elaiophores in the orchids Rudolfiella picta (Schltr.) Hoehne (Maxillariinae sensu lato) and Oncidium ornithorhynchum H.B.K. (Oncidiinae sensu lato).

Background And Aims: Floral elaiophores, although widespread amongst orchids, have not previously been described for Maxillariinae sensu lato. Here, two claims that epithelial, floral elaiophores occur in the genus Rudolfiella Hoehne (Bifrenaria clade) are investigated. Presumed elaiophores were compared with those of Oncidiinae Benth.