The Euphorbiaceae sensu lato are distributed mainly in the tropics, in various types of vegetation and habitats, being one of the largest, most complex and diverse families of angiosperms. It has recently been divided into four families, according to classification systems based on molecular phylogeny: Euphorbiaceae sensu stricto, Phyllanthaceae, Putranjivaceae, and Picrodendraceae. There is a proposition to establish Peraceae still under discussion. There were also changes in the taxonomic position of genera widely distributed in the Brazilian territory, such as Amanoa, Drypetes, Pera, Phyllanthus, Podocalyx, Pogonophora, and Richeria, among others. In addition, new species have been proposed and the limits of taxa distribution are expanding in Brazil. Thus, the authors provide an overview of recent studies and advances in the taxonomy of Euphorbiaceae s.l. in the Northern, Northeastern, Southeastern and Southern regions of Brazil, concentrating on review works and regional floras, as well as the changes that resulted in setting a new taxonomic family.

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Clusia fluminensis and C. lanceolata are dioecious shrubs having resiniferous flowers with strongly distinct androecia. The aim of this study was to investigate the development and anatomy of their androecia and the ultrastructure, histochemistry and secretory process of their androecium resin glands, examining whether the cellular aspects of resin secretion differed between these two morphologically distinct androecia. Stamens differ, being free in C. fluminensis and clustered in a synandrium in C. lanceolata. Staminode sterility is due to the undifferentiated nature of the anthers in C. lanceolata and degeneration of meiocytes and anther indehiscence in C. fluminensis. Resin is produced in subepidermal cavities and canals with wide lumens. In the secretory stage, epithelial cells present sinuous walls, voluminous nuclei, polymorphic plastids associated with periplastidial reticulum, mitochondria, oil bodies, multivesicular bodies, endoplasmic reticulum and dictyosomes. The resin is released through rupture points on the distal surface of stamens and staminodes, associated with disrupted cavities and canals. Our results show morphological diversity associated with functional similarity. Also, a secretion pattern shared by the two species includes initiation of the secretory process in young floral buds, compartmentalisation of the secretion in pre-anthesis buds and release of secretions at anthesis. Cellular aspects of resin secretion in these species are quite similar, as are the chemical identities of the main components of the floral resins of the genus.

Characters of the gynoecium are considered potentially significant for the systematics of Myrtaceae. However, only two such characters – ovule number and placentation – have been addressed from an evolutionary perspective. Colleter presence in flowers is a synapomorphy of Myrtales; however, no morphological and histochemical descriptions of such structures have been done in Myrtaceae. Here we analysed the ontogeny and anatomy of the gynoecium combined with the ontogeny, anatomy, ultrastructure, and histochemistry of the colleters to study the evolution of these characters and map their states in the Myrteae phylogenetic tree. Our findings may help elucidate the evolutionary history of this tribe of fleshy-fruit producers so important towards maintaining ecological balance in the rainforest. Floral anatomy and ontogeny were analysed using light microscopy. Colleter samples were processed using standard methods for light and transmission electron microscopy. The main metabolites in colleters were detected via histochemistry. To map character states the program Mesquite version 2.71 was used. The morphological characters of the South American Myrteae here analysed provided an overview of the evolution of gynoecium – with cauline or carpellate placenta – and of colleters, as well as synapomorphies for the clades Plinia + Myrcia and Eugenia + Pimenta. The presence of two integuments in the ovules associated with sclereids and colleters in the gynoecium and the young fleshy fruit assures the efficient dispersal of their seeds. Our findings regarding gynoecium structural diversity of the tribe Myrteae give a new insight on their morphologically uniform flowers.

Many Velloziaceae flowers present conspicuous glands, whose taxonomic value has already been highlighted. However, until now, their micromorphology, anatomy and ultrastructure have not been investigated, nor have the natures and possible functions of their exudates. Our aim was to investigate distribution, ontogenesis, structure, and secretion mechanisms of glands of Barbacenia flava and Vellozia intermedia and to discuss their possible ecological functions. Samples were prepared according to standard methods for investigations of plant anatomy, scanning electron microscopy, and transmission electron microscopy. Histochemical tests were performed, and focal field observations were made in the study site. The capitate stalked glands on the pedicel, tepals and hypanthium are covered by a sticky secretion that is released in the gland head through the outer periclinal cell walls and cuticle. Secretions are produced in the epidermal and subepidermal cells that contain structural components typical of mixed, mainly lipophilic secretions. Bacteria were found inside the oil-resin gland cells of both species. The Meliponina bees Trigona spinipes and Tetragonisca angustula were observed collecting resin from both species, but were not involved in pollination. Our observations clearly indicate that flower glands of B. flava and V. intermedia are oil-resin secreting and remain active in secretion from very young buds, through to immature fruit. New, smaller glands replace senescent glands by divisions near the base of the original stalk cells. Oil-resin glands have a number of different, but important functions, including the interaction with Meliponina bees, protection against water loss and high temperatures by ultraviolet screening, and anti-desiccant properties.

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