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.

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.

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.

Eriosema comprises c. 150 species and has a pantropical distribution and two centres of diversity, Africa and America. The species occur in tropical savannas and grasslands, including the cerrado in Brazil. They have adapted to these environments by developing specialized underground organs, and an abundance of trichomes. Here we present the first comprehensive molecular phylogenetic analysis of Eriosema, including species from its entire distribution range and generating 391 new DNA sequences. We sampled 140 species from nine genera of Cajaninae, of which 94 (60% of the genus) were Eriosema. Our analyses were based on the nuclear ITS and plastid rpl32 and trnQ regions, and used maximum likelihood and Bayesian phylogenetic analyses of individual and combined data sets. In all analyses, Eriosema was resolved as monophyletic, but its interspecific relationships are not well resolved. Rhynchosia is not monophyletic, and some African Rhynchosia spp. emerged together as sister to Eriosema. Our study supports the monophyly of Adenodolichos, Dunbaria, Flemingia and Cajanus, but Chrysoscias and Bolusafra formed a clade that is sister to a group of Rhynchosia spp. Paracalyx was resolved as paraphyletic and nested among African Rhynchosia spp. Divergence time analysis suggested that the Eriosema lineages diverged 6.5–10.7 Mya. Two major lineages have diversified in Eriosema, one including most of the African species (4.41–6.68 Mya), the other mainly composed of the South American cerrado species (3.56–5.78 Mya). These results revealed that Eriosema is a recent and tropical savanna-adapted group, and its diversification occurred in the late Miocene in parallel with the expansion of C4 grasslands.

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Eriosema is a pantropical genus occurring mostly in savanna vegetation and grasslands of tropical environments, with approximately 150 species and two centers of diversity, one in Africa with about 110 species, and the other in the Neotropics with about 40 species. Considering the large number of Eriosema taxa in Brazil, including five recently described, and the lack of recent study that encompasses all species that occur in the country, a taxonomic synopsis of the Brazilian species of Eriosema was needed and is presented here. Herbaria collections, including type specimens, were consulted and field work was carried out in Brazil. Our study records 35 Eriosema species in Brazil, which concentrates most of the diversity of the genus in the Americas (85%; 35 out of 41 species). Most of this diversity occurs in the Central Brazilian savannas, particularly in the states of Goiás (29 taxa, eight endemic), and Minas Gerais (26 taxa, four endemic). Among all American species in the genus, Eriosema simplicifolium and E. crinitum have the broadest geographical distributions, and occur throughout Brazil and most part of the American continent. They form species complexes and future detailed studies will be necessary in order to understand taxon boundaries and delimitations. An identification key, taxon descriptions, information about type specimens as well as information on the habitat, phenological and geographical records, together with distribution maps, images of representative species in the field and the main morphological characters are provided to assist in the correct identification of this group of savanna plants. We also present 15 lectotypifications, out of which three are second-step.

Eriosema grearii, a new species for the genus (Leguminosae, Papilionoideae, Phaseoleae, Cajaninae), is described and illustrated. Similar to E. heterophyllum, it differs from it morphologically by the free (vs. joined) stipules, lax flowers distributed along the inflorescence axis (vs. congested and concentrated at its apex), inflorescences not opposite to the leaves (vs. opposite), and leaflets with secretory cells at the base of trichomes (vs. absence of secretory cells at the base of trichomes). A survey of the leaflet secretory structures revealed that E. grearii has distinct secretory structures, referred here as secretory-base trichomes, and reported for the first time for the Phaseoleae tribe. An identification key for the Eriosema species in Mato Grosso do Sul, where the new species occurs, is provided.