The subtribe Cajaninae of papilionoid legumes has a pantropical distribution and comprises approximately 490 species. These species have diversified throughout dry environments where there are high temperatures and strong light. The subtribe stands out because all its representatives have vesicular glands. In addition, bulbous-based and capitate trichomes are important secretory structures present in all genera of the Cajaninae. We analyzed the ultrastructure and histochemistry of these glandular trichome types in leaflets of the three species of the subtribe. Using transmission electron microscopy and histochemical analyses, we link the glandular secretions to subcellular structures. We here report for the first time the type of exudate and ultrastructure of the glands of subtribe Cajaninae. Terpenoids and phenolics were confirmed by histochemistry tests, and we observed that the organelles responsible for biosynthesis of oils are the most representative in these glands. Each glandular trichome showed particular ultrastructural features compatible with the compounds produced. We suggest that these glandular trichomes, with their respective exudates, act in defense against herbivory and against possible damage by ultraviolet radiation.

A comparative anatomical study was carried out on the secretory structures of leaflets from taxa belonging to the genus Rhynchosia -taxa difficult to delimit because of uncertain interspecific relations -in order to evaluate the potential diagnostic value of these anatomical traits for taxonomic assignment. A further objective was to establish consensual denomination for these secretory structures. The new anatomical features found in these taxa were sufficiently consistent to separate the species evaluated. The presence and localization of glandular-punctate structures bulbous-based trichomes, the number of layers in the palisade parenchyma and the arrangement of vascular units distinguish the taxa investigated and these characteristics can be extended to other species of Papilionoideae. The trichomes analyzed were described and classified into five types. Depicted in diagrams, photomicrographs, and by scanning electron microscopy, and listed for the first time at the genus and species levels. The information obtained served to effectively distinguish the taxa investigated among species of Papilonoideae.

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Prosopis L. is particularly rich and important in the Chaco region where forest vegetation currently persists as fragments. Its species are very important for the conservation and management of Chaco vegetation, and understanding their phenology and reproductive biology is essential. Here, we studied the phenology and pollination biology of P. rubriflora Hassl. in the Brazilian Chaco compared to other species of the genus. Differing from other Prosopis species, P. rubriflora is evergreen, and most phenophases are nonseasonal and bimodal (except fruiting), with a continuous pattern. Prosopis rubriflora is andromonoecious, but only weakly, since plants produce relatively few staminate flowers. Flowers showed three floral stylar phenotypes: short, medium and long style. Short-style flowers are functionally staminate because the stigma is nonreceptive. To compensate for the small size of P. rubriflora red brush flowers, attraction is compressed and transferred to the spike, which functions as a collective pollination unit. This compression may favour self-and intraplant pollination, which may reduce and/or prevent the occurrence of protogyny and partial, i.e. temporal, herkogamy in hermaphrodite flowers. Prosopis rubriflora has generalist pollination, but differs from the other Prosopis species because it is also pollinated by hummingbird, most likely due to its ''ornithophilous'' characteristics. This species is the first of the genus recorded as pollinated by hummingbirds. Although the exotic bee Apis mellifera L. presents high frequency of visit, this bee is not effective pollinator, due to its foraging style that does not favour cross-pollen flow. Native insects and hummingbird species are main pollinators because they present trapline foraging.