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The stereotyped floral morphology of Neotropical Malpighiaceae species-zygomorphic and calyx with oil glands-is correlated with oil-bee pollination. In contrast, the floral trends of the Paleotropical lineages are actinomorphy and lack of calyx glands, probably due to the absence of oil-collecting bees. The Paleotropical genus Acridocarpus is an exception because of its zygomorphic, gland-bearing flowers. Glands throughout Acridocarpus inflorescences were morphoanatomically evaluated to verify the occurrence of patterns related to species and geographic distribution. Herbarium (25 species) and fresh samples of A. longifolius were processed according to standard anatomical techniques. To verify the presence of glucose and protein, strip tests were applied to the exudate. Fresh samples were fixed and submitted to histochemical tests. Based on the occurrence, number and placement of glands, three distribution patterns were recognized on the bracteole and ten on the calyx. Bract, bracteole and sepal glands have a typical nectary structure with a palisade-like epidermis and vascularized parenchyma. Glands were classified as short-stalked, sessile or immersed. Histochemical tests performed on bract and sepal glands of A. longifolius were positive for proteins, polysaccharides and phenolic compounds, and negative for oil compounds. Glucose and protein were detected in the exudate. These results allow us to recognize the glands in Acridocarpus inflorescences as nectaries. This comprehensive morphoanatomical study helps to clarify the correlation between patterns of floral morphology and secretion consumers, as well as to better understand floral evolution in Malpighiaceae across their dispersal events.

Premise of research. Colleters are structures that secrete a sticky product that covers and protects the shoot apex and floral buds. In Chamaecrista, colleters have been reported in the cotyledons of three species and on the leaves of all species belonging to sect. Absus subsect. Baseophyllum. Anatomical studies using taxonomic and phylogenetic approaches are necessary to evaluate the presence, diversity, and importance of colleters for Chamaecrista. Methodology. We analyzed 55 species of Chamaecrista belonging to five of the six sections of the genus. Samples from both herbarium- and field-collected material of young vegetative and reproductive meristems were used. The material was subjected to standard anatomical study by light microscopy and SEM, and secretion was evaluated by histochemical analyses. Pivotal results. Histochemical analyses for the total proteins, total polysaccharides, acid mucopolysaccharides, pectins/mucilage, and lipids generated positive results. Six types of colleters are described here: club shaped, racket shaped, long bottle shaped, short bottle shaped, long digitiform, and short digitiform. Sect. Apoucouita showed the short digitiform and club-shaped types and was the only section with colleters on the sepal margins. Most species of sect. Absus subsect. Absus presented the short bottle-shaped type, while all species from subsect. Baseophyllum presented the short digitiform and club-shaped types. Although the short bottle-shaped type was the most common among species from sect. Chamaecrista, the short digitiform and club-shaped types were also observed. The short bottle-shaped colleters were also found in sect. Grimaldia, while in sect. Xerocalyx only the digitiform type was found. Conclusions. The topography and components identified in the secretion of the colleters suggests that such structures may be involved in the protection of developing leaves and flowers. Five of the six types described in our study are novelties for Chamaecrista. The distribution of colleter structural diversity provides an important source of new data that may help to clarify the taxonomy and phylogeny of Chamaecrista.

This work describes the leaf anatomy of 16 species belonging to three genera of the Malpighiaceae family found in the Cerrado (Minas Gerais State, Brazil). The scope of this study was to support the generic delimitation by contributing to the identification of the species and constructing a dichotomous identification key that includes anatomical characters. The taxonomic characters that were considered to be the most important and used in the identification key for the studied Malpighiaceae species were as follows: the presence and location of glands; presence of phloem in the medullary region of the midrib; mesophyll type; presence and type of trichomes; and presence, quantity, and disposition of accessory bundles in the petiole. It was also possible to indicate promising characters for future taxonomic and phylogenetic studies in the Malpighiaceae family, especially for the Banisteriopsis, Byrsonima, and Heteropterys genera.

Lophopterys floribunda is a Neotropical species of Malpighiaceae endemic to Brazil, occurring in both the Amazon and Atlantic Forest. Instead of the typical bi-glandular sepals reported for Neotropical Malpighiaceae, this species presents a single, large gland on the lateral sepals. In addition, ant patrolling was observed at the apex of bracts and bracteoles during fieldwork. Thus, this work aimed to describe the sepalar gland of L. floribunda and other secretory structures in its flowers and inflorescence. Samples of bracts, bracteoles, sepals, petals, and anther were collected and submitted to usual anatomical techniques. Unexpected nectaries at the apex of bracts and bracteoles, not visible to the naked eye, were described and represent a new type of structure for the family due to both their position and size. Mutualistic ants consume the exudate produced by these tiny nectaries, and such structures enable a specific visitation pattern for Lophopterys. Typical epithelial elaiophores occur on the lateral sepals, formed by an invaginated epidermis, which predominantly produce lipid secretion. The petal marginal glands are anatomically similar to the standard type of colleter, which exude mucilaginous substances. The exudate produced by the petal marginal glands was considered to have an additional role of contributing to the maintenance of the closed bud during the beginning of development. The globose epidermal cells containing lipids, proteins, and polysaccharides observed in the connective may be responsible for the typical aroma emitted by these flowers. The diversity of secretory structures reported here has application in both systematic and ecological studies of Malpighiaceae.

This study aims to determine whether morphoanatomical characters of the leaves of the species of Chamaecrista sect. Absus subsection Baseophyllum could be used to support an up-ranking of C. cytisoides varieties to the species level as previously defined by molecular studies. The significance of anatomical adaptive strategies to arid environments is also discussed. Standard light microscopy techniques and histochemical tests were used for both morphoanatomical and histochemical characterization of the leaves. All the species studied share a single-layered epidermis, actinodromous–camptodromous–brochidodromous type of venation, vascular bundles surrounded by layers of fibers bounded externally by a sheath of cells containing solitary crystals, enlarged tracheids at the vein endings, vascular petiole/rachis tissue with a parenchymatous pith, accessory vascular bundles, mucilage idioblasts and hypodermis in the mesophyll, colleters, and non-secretory trichomes. The position and type of stomata, type of mesophyll, number of palisade and spongy parenchyma layers, position of mucilage idioblasts in the mesophyll, and the number of accessory vascular bundles of petiole/rachis provided useful characters for discriminating the eight species of the subsect. Baseophyllum. Histochemical tests reveal the presence of total polysaccharides, pectins, mucilage and phenolic compounds in the idioblasts. Other xeromorphic characters such as thickened outer periclinal cell walls, compact mesophyll, mucilage idioblasts and hypodermis in the mesophyll may help enable the studied species to survive in exposed sunny areas.

Unusual nectaries were anatomically described as being usual traits for Gentianaceae. They are small, avascularized, and formed by 3 to 5 rosette cells with labyrinthine walls around one central cell. Such as nectaries have been reported for stems, petals, and sepals of different species of the family, however, there is no information on the mechanisms involved with the synthesis and release of secretion. Thus, this work aimed to unravel the mechanism of secretion and exudation of nectar for these curious nectaries using Calolisianthus speciosus as a model. Samples were processed according to standard methods for light and electron microscopy. Leaf and sepal nectaries were described, as were those of the apex of petals where ants were observed patrolling a darkened region. The enzymatic method was used for the detection of sugars, proteins, and amino acids in leaf and sepal exudates. The nectaries of petals of C. speciosus are similar to those of its leaves, sepals, and stem, although their activities are asynchronous. Polysaccharides were detected on the labyrinthine walls of rosette cells and protein in the opposite region of the cytoplasm. Labyrinthine walls increase the contact surface between rosette cells and the central cell, allowing for the transfer of secretion. After accumulation, the secretion is released to the subcuticular space of the central cell through disruption of the cuticle. The secretion and exudation of nectar were elucidated and involve distinct organelles.

Previous studies of secretory structures in species of the Neotropical dragon's blood Croton (section Cyclostigma) show inconsistencies in their classification. An accurate assessment of the identity and homology of such structures is essential for taxonomic and evolutionary studies. Field-collected leaves, stipules, and flowers at different developmental stages were sampled. The material was subjected to standard anatomical study by light microscopy and SEM, and secretions were evaluated by histochemical analyses. Leaves and flowers of Croton echinocarpus and Croton urucurana present five secretory structures (idioblasts, laticifers, colleters, extrafloral nectaries, and floral nectaries) with high similarity between the two species. Idioblasts secrete compounds of a mixed nature; laticifers are branched and nonarticulated; and colleters and nectaries present hydrophilic secretion. The leaf marginal glands previously described as extrafloral nectaries are actually colleters of the standard type. We found colleters in staminate and pistillate flowers. The histochemical tests detected proteins in the secretions of all structures. The classes of secondary metabolites detected support the biological activities of secretion described in the literature. The correct identification of colleters in flowers establishes a new register of these structures in flowers of this genus. We show that an approach integrating anatomic structure, histochemistry, and period of secretion activity allows for a more accurate classification and homology assessment of secretory elements in this genus, which is exceptionally rich in this type of structures.

Premise of research. In Casearia Jacq., one of the largest genera of Salicaceae, stipular glands are taxonomically important, although these structures have not previously been described anatomically. The aims of this study were to clarify the gland type present on the stipules of three species of Casearia and describe anatomical variations of these glands in Cerrado and forest specimens. Methodology. Samples of Casearia decandra Jacq., a typical forest species; Casearia rufescens Cambess., which is endemic to Cerrado; and Casearia sylvestris Sw., which occurs in both vegetation types, were collected. Samples of stipules and apical meristems were collected in the field or obtained from herbarium material and processed according to standard methodologies for anatomical studies. Pivotal results. Glands occur at the apex, on the margin, and at the base of the stipules of C. decandra and only at the apex and the base of C. rufescens and C. sylvestris. The glands consist of a nonvascular, multicellular, parenchymatous central axis, which is covered by a layer of secretory palisade epidermis, and a thin cuticle. No anatomical differences among the glands of the species and specimens were observed. Histochemical tests detected total polysaccharides, pectins/mucilage and proteins in the cytoplasm, the secretion in the subcuticular space, and the exudate. Based on these tests, the glands are colleters. The histochemical results were the same for the secretion produced by colleters of the species from different environments. In general, no correlation was found between gland size and vegetation type (forest and Cerrado). Conclusions. The anatomical structure, early activity, and mucilaginous nature of the secretion allow us to conclude that the stipule glands of the three species of Casearia are the standard type of colleter. This is the first record of colleters on stipules of Casearia, which may be taxonomically useful.

Premise of research. Casearia sylvestris (Salicaceae) is widely used in traditional medicine and possesses various types of secretory structures, but the mechanisms and compartments involved in the secretory processes have not been elucidated. This study aims to describe the chemical nature of the secretions produced by all secretory structures of C. sylvestris leaves and to identify the compartments and mechanisms of synthesis, storage, and release of secretion. Methodology. Shoot samples were collected and analyzed using standard techniques for light microscopy and for scanning and transmission electron microscopy. Histochemical tests were performed to identify the main classes of exudate compounds. Pivotal results. The subcellular compartments involved in the secretory process of the taniferous idioblasts, cavities, ducts, and colleters were identified, with all organelles being consistent with the chemical nature of secretion. In the colleters, plastids with osmiophilic compounds are related to the production of oil, while dictyosomes are associated with syntheses of polysaccharide secretion. The smooth endoplasmic reticulum, periplastidial reticulum, and plastids present in the secretory epithelium of the cavities and ducts produce the oleoresin, while dictyosomes are involved with hydrophilic secretion. Conclusions. Ultrastructure variation among the organelles of the four types of secretory structures studied, as well as the chemical complexity of exudates produced by them, revealed particularities that enabled the description of models for the secretory mechanism of each. Novelties that reveal the mechanisms involved in the release of secretion through the cell wall are presented.

The objective of this study was to evaluate the genetic effects involved in post-harvest water loss of C. baccatum fruits and to correlate fruit morphological characteristics. Fruits of eight landraces of C. baccatum and their twenty-eight hybrids were evaluated in a randomized, complete block design. Analysis of variance, diallel analysis, phenotypic and genotypic correlation, and path analysis for eight fruit traits were performed. Fruit width, fruit length, dry matter content, and fruit wall thickness were determined by additive gene effects. On the other hand, the non-additive effects played more important role than additive ones, including water loss, cuticle thickness, exocarp thickness, and total soluble solids. The relationship of fruit traits suggested that indirect selection can be carried out from field experiments under different environmental conditions. Overall, genitors 4, 24, 50, and 56 should be selected to form new populations to improve these traits. The Brazilian pepper landraces of C. baccatum species are a source of genetic variability for plant breeders, and the new segregating populations emerging through the crossing of pepper lines with reduced water loss should be developed, opening new ways for conventional breeding.