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Phylogenetic analyses of early-diverging Faboideae have indicated that genera previously positioned in distinct tribes are instead closely related, e.g. in the Amburaneae clade, and the relatively recent rearrangements of many genera into clades has hampered the identification of morphological synapomorphies for previously unrecognized clades. Our aims are to evaluate anatomical vegetative characters of leaflets attached to reproductive features in the Amburaneae clade, to identify new synapomorphies for the clade and subclades, to identify characters supporting intergeneric relationships and diagnostic characters for the genus and species and to provide information about the morphology and histochemistry of secretory structures. The study was based on the anatomy of the leaflet of 19 species of the Amburaneae clade. Papillae cells, the presence of vascular system units and hypodermis are shared features of Amburaneae. Anatomical characters of the leaflet can be diagnostic at the generic and specific levels in Amburaneae. Secretory structures found in the clade are secretory cavities, secretory channels, idioblasts, mucilaginous epidermal cells and glandular trichomes. The broader concept of Amburaneae is reinforced here by morphological and molecular data, with the identification of new synapomorphies. Our dataset supports the intergeneric relationships resolved by molecular data.

The secretory structures of Alismataceae have been described as secretory ducts, laticifer ducts, laticifer canals or schizogenous ducts. However, these terms are not found in the specialized literature, and ontogenetic analyses for the exact classification of these structures are missing. Accordingly, more studies regarding the secretory structures of Alismataceae are necessary to establish homology in the family or in the order. Thus, the aim of this study was to describe the anatomy, ontogeny, distribution in the organs and exudate composition of the secretory structures present in five Alismataceae species in order to determine whether the family has laticifers or secretory ducts. Samples of leaves, flowers and floral apices were processed for anatomical and histochemical analyses by light microscopy. The analysis indicated the presence of anastomosing secretory ducts in all species, occurring in both leaves and flowers. The exudate contains lipids, alkaloids, proteins and polysaccharides, including mucilage. The secretory duct structure, distribution and exudate composition suggest a defense role against herbivory and in wound sealing. The presence of secretory ducts in all species analyzed indicates a probable synapomorphy for the family.

Brazilian mangroves have been severely impacted by metallurgical, petrochemical, pyrometallurgical smelters and other industrial activities. In Rio de Janeiro, mangroves are part of the Atlantic Rainforest now under the stress of high levels of industrial waste. Therefore, this work aimed to detect potentially toxic elements (PTEs) by evaluating the leaves of Laguncularia racemosa (L.) Gaertn. f. collected from three mangroves with different levels of pollution. To gain further insight toward an accurate diagnosis of the effects of anthropogenic pollution on mangrove stands, we evaluated leaf epicuticular wax composition, as well as morphological and anatomical traits. Samples were analyzed using inductively coupled plasma-optical emission spectroscopy (ICP-OES), gas chromatography (GC) and microscopy. Results revealed variation in the contents of PTEs among the three mangroves from lowest to highest concentration, as follows: Al (0.30–0.73), Pb (0.095–0.325) and Zn (0.25–0.30) mg/kg. Zn was detected in sclerenchyma tissues. Leaf epicuticular wax contained more than 50% of triterpenes, in particular, the pentacyclic triterpenes lupeol (41.61–55.63%) and β-amyrin (8.81–16.35%). Such high concentrations promote the increase in leaf permeability to salts and PTEs. Micromorphology of leaf epicuticular wax in L. racemosa also varied among the three evaluated sites, especially around stomatal openings, but no harmful changes were noted. L. racemosa plays a key role in the rich diversity of mangrove ecosystems. As such, this species could, by the presence of PTEs in its leaves, be a suitable biomonitor of toxic substances in coastal environments of the world and used accordingly in strategies designed for eco-sustainable technologies.

Leaves of Laguncularia racemosa (L.) Gaertn. f. were collected from the following mangroves along Brazil’s southeastern Atlantic coast: Coroa Grande (CG), Pedra de Guaratiba (PG) and Marambaia (M). This work aimed to evaluate the presence of minerals by Energy Dispersive X-Ray Spectroscopy (EDS) and Inductively coupled plasma - optical emission spectrometry (ICP-OES); the chemical composition of epicuticular waxes by gas chromatography–mass spectrometry (GC-MS) and the leaf morphoanatomical features. Results revealed variation in metal contents among mangroves in the following ranges: Al (0.307–0.73), Cd (0.004–0.016) and Pb (0.095–0.325) mg/mL by ICP-OES. Leaf epicuticular wax contained more than 50% of triterpenes, in particular the pentacyclic triterpenes lupeol (41.61–55.63%) and β-amyrin (8.81–16.35%), as well as n-alkanes, such as hentriacontane and tetratetracontane. In particular, we observed differences in the micromorphology of the epicuticular wax in the leaves of plants from each of the three evaluated sites, especially around stomatal entrances. Histochemical reaction indicated the presence of zinc in fiber cell walls and druse crystals of leaves.

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Rhizophora mangle L. (Rhizophoraceae) is a halophyte from two mangroves in the municipality of Rio de Janeiro in Rio de Janeiro state, Brazil. This work aimed to determine the presence of environmental contaminants in the leaf of R. mangle through morphological and chemical analyses. We collected samples in Coroa Grande mangrove (CG), near an industrial park, and Pedra de Guaratiba mangrove (PG), which is currently under threat of anthropization by domestic occupation. Energy Dispersive X-Ray Spectroscopy (EDS) coupled to Scanning Electron Microscopy (SEM) revealed the presence of chemicals and their relative quantities in leaves. Light microscopy and Scanning Electron Microscopy (SEM) were used to examine leaf tissue. Na, Ca and Cl were found in both CG and PG. Specific leaf area was significantly lower in PG. Leaves from CG also presented the three heavy metals Mn, Zn and Cu. R. mangle presents succulent, hypostomatic leaves with dorsiventral structure. Abundant mucilage and crystals in idioblasts were observed. Slight differences in anatomical qualitative traits between leaves from both sites were detected. Leaves from CG were slightly thicker than those examined from PG, especially on main vein vascular system, and a high quantity of stomata was observed in abaxial surface of leaves from PG. Collectively, these findings indicate that R. mangle is resilient and tolerant to the environmental pollutants and presents functional traits related with saline environments; therefore, the morphoanatomical variations are probably related to abiotic factors.

Discolobium and Riedeliella, exclusively South American genera, have been shown in phylogenetic analyses to be the sister group to the Pterocarpus clade. The species of the two genera can be confused when reproductive structures are absent, resulting in taxonomic misunderstandings in botanical collections. This study aimed to investigate the anatomical characters of leaflets of representatives of Discolobium and Riedeliella in terms of their diagnostic value at the genus and species levels and to provide information about the type, location and histochemistry of their secretory structures, and their usefulness for the systematics of the genera. The taxa were analysed using light microscopy and scanning electron microscopy. Unistratified epidermis, epidermal cell contour and fibre bundles of the main vein are features shared by the two genera. The position of the stomata and of the tector trichomes and the shape of the epidermal cells and of the mucilaginous idioblasts are diagnostic anatomical features at the genus level. Epidermal mucilaginous idioblasts are confirmed for all species studied. Phenolic idioblasts are present in Riedeliella and Discolobium, and secretory trichomes are found only in Discolobium. The anatomical characters of the leaflets are useful for the taxonomy of all species studied. Furthermore, our dataset shows novelties for the systematics of Fabaceae.