Nectar production dynamics can show inter- and intraspecific variation, which can be associated with environmental and ecological factors and with the ultrastructural diversity of the floral nectary. In this context, we recorded nectar production dynamics from a morphofunctional perspective using the hummingbird-pollinated Billbergia distachia (Bromeliaceae). The scale-throated hermit Phaethornis eurynome was the only floral visitor observed, indicating a specialized pollination system. Nectar production showed significant differences between day and night, and the periods of major pollinator activity and nectar secretion were synchronous. The ultrastructural features of the nectary showed some evidence of nectar reabsorption in flowers at night, and it can be inferred that this process may be a key factor in the nocturnal pause in nectar production. In this way, nectary morphoanatomy, nectar traits and an energy-saving mechanism through nectar reabsorption contribute to the well-established relationship between B. distachia and P. eurynome.

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ResumoO sucesso reprodutivo das plantas pode estar relacionado a diversos fatores. Dessa forma, o presente trabalho teve como objetivo analisar os diferentes morfos florais apresentados por Solanum melongena (híbrido Nápoli) no contexto da biologia reprodutiva e da polinização. O estudo foi realizado em Estiva Gerbi, São Paulo. Os dados de morfometria floral foram coletados com auxílio de paquímetro manual e estereomicroscópio. Para determinar o sistema reprodutivo, verificou-se a formação de tubos polínicos em diferentes horários após a polinização manual ser efetuada. Realizou-se a caracterização dos visitantes florais através de observações de campo e calculou-se a frequência dos mesmos. Constatou-se diferença significativa entre o tamanho das corolas e dos estiletes dos diferentes morfos, não diferindo entre si apenas as anteras. Quanto aos sistemas reprodutivo e sexual, detectou-se que S. melongena é uma espécie xenógama facultativa, assim como apresenta o fenômeno da andromonoicia, no qual as flores de estilete curto apresentam apenas a função masculina funcional. Concluise para S. melongena que ambos os morfos contribuem para seu sucesso reprodutivo, assim como a ação dos polinizadores, pois embora apresente certo grau de autocompatibilidade, a autopolinização não mostrou-se suficiente para uma efetiva fecundação de seus óvulos como quando na ocorrência da polinização cruzada. Palavras-chave: andromonoicia; sistema reprodutivo; visitantes florais. AbstractThe reproductive success of plants may be related to several factors. Thus, this study aimed to analyze the different floral morphs presented by Solanum melongena in the context of reproductive biology and pollination. The study was conducted in Estiva Gerbi, São Paulo. Data on floral morphometry were collected with the aid of a manual caliper and stereomicroscope. To determine the reproductive system, the formation of pollen tubes at different times after manual pollination was observed. The characterization of floral visitors was conducted through field observations, and the frequency of their visits was calculated. There was a significant difference in size between the corollas and styles from different morphs, while only the anthers did not differ significantly. Regarding the sexual and reproductive systems, it was found that S. melongena is a facultative xenogamous species, and presents the andromonoecy phenomenon in which short-styled flowers are only functionally male. The conclusions were that, for S. melongena (hybrid Napoli), both of its floral morphs, as well as the action of its pollinators, contribute to the reproductive success of this species, as, even though it has a certain degree of self-compatibility, self-pollination was not sufficient for a fertilization of ovules as efficient as the one in cross-pollination.

Nectar is an important floral resource in the establishment of plant-pollinator interactions. Recent studies have shown that nectariferous tissues are independent of the ABC model of floral development and that ecological interactions can modify their expression. In this sense, it would be interesting to study generalist species in relation to nectar production and nectary morpho-anatomy to verify the strategies used to attract different pollinator groups. We recorded nectar production dynamics in Aechmea vanhoutteana (Bromeliaceae) from a morpho-functional and ultrastructural perspective. We observed different species of hummingbirds, bees and butterflies visiting flowers of A.vanhoutteana, and their frequency varied throughout floral anthesis. The nectar volume and quantity of sugar also varied significantly during anthesis, and this spatial and temporal variability seems to be related to an increase in bee visits, representing an important aspect of the reproductive strategy of this species, since bees can fly longer distances than the observed hummingbirds (although both have territorial behaviours). Thus, it can be suggested that anatomical and physiological nectar traits may be related to pollen flow, an important aspect of the reproductive strategy of A. vanhoutteana, suggesting plant resource allocation for optimizing reproduction through nectar production.