Colleters are secretory structures widely distributed in eudicots and with taxonomic value in many families. Although glandular trichomes have been described in some Anacardiaceae species, the chemical characterization of their secretions is scarce and to date there are no reports on colleters. Light microscopy and scanning electron microscopy were used to study the distribution and structure of colleters on the vegetative buds of Anacardium humile A.St.-Hil., Lithraea molleoides (Vell.) Engl., Spondias dulcis Parkinson, and Tapirira guianensis Aubl., and to characterize their secretory products histochemically. In all of these Anacardiaceae species, colleters are multicellular and multiseriate ovoid or club-shaped glandular trichomes of protodermic origin, present on both surfaces of leaf primordia. They reach the secretory phase at early stages of leaf development, after which they gradually degenerate, become brown, and fall off. Histochemical tests indicate that the secretion within the glandular cells and outside the trichomes is a complex mixture containing mucilage, fatty acids, and phenolic compounds, which are secretory products that can play an important role in the protection of meristems against desiccation and attack by pathogens. Therefore, the distribution of these glandular trichomes, their short-life, the chemical nature of their secretions and their presumed functions support their being classified as colleters.

The goal of this study was to analyse possible structural and ultrastructural differences between the secretory disk of male and functionally female flowers of Tapirira guianensis (Anacardiaceae) at different developmental stages. Studies were carried out using light, scanning and transmission electron microscopy. Biochemical tests were employed to determine the proportion of sugars in the nectar of the floral morphotypes: they were found to be similar, both predominantly composed of sucrose. In addition to sugars, lipids and phenolic substances were identified in anthetic flowers; thus, the secretory disk is a mixed secretion gland, also called a sensu lato nectary. During anthesis, granulocrine and eccrine secretory mechanisms occur in both floral morphotypes. After anthesis and fertilization of the functionally female flower, only the lipophilic and phenolic secretion continues until the early stages of fruit development. An intrastaminal secretory disk that produces both nectar and lipids is reported for the first time in Anacardiaceae.

This work points out some variations in leaf anatomy useful in the separation of two species of the genus Varronia P.Br., V. globosa Jacq. and V. leucocephala (Moric.) J. S. Mill., and some anatomical adaptations of the semiarid climate. These species differ in stomata distribution, types of glandular trichomes, non-glandular trichomes density, accumulation of substances in V. leucocephala, crystal types, colenchyma type in midrib and petiole, and the vascular bundles in petiole. As unifying characters, both have uniseriate epidermis, glandular and non-glandular trichomes, dorsiventral leaves, crystals, collateral vascular bundles in leaf blades, and petiole with three vascular traces. The morphological study of trichomes has been extensively explored since it is one of the main characteristics differing the species from the genus, and being recognized several types of glandular trichomes, particular to each species. Some anatomical typical features of plants occurring in xeric environments were also identified: stomatal distribution, abundant trichomes with micropapillae on its surfaces, and lipid accumulation.

Presumed domatia are actually extrafloral nectaries on leaves of Anacardium humile (Anacardiaceae), a species from the Brazilian savannah, is associated with foraging ants, which leads to the description of the structure of its leaves as domatia. However, the ants collect secretions on the leaves, a phenomenon that inspired us to elucidate this structure. To this end, we conducted an analysis of the distribution, micromorphology, anatomy and histochemistry of these supposed domatia. They are located in the axil of thicker leaf veins and are composed of glandular trichomes which exude glucose; they are, therefore, described here as extrafloral nectaries (EFNs). The nectariferous trichomes are located at the same level as the other epidermal cells on young leaves, while in mature leaves they were found in depressions of the leaf blade. The secretory activity of EFNs is limited to juvenile phases, becoming degenerated in mature leaves. Carbohydrates and lipophilic compounds were detected in the produced secretion. It can be concluded that the presence of ants foraging leaves to collect from EFNs indicates a mutualistic interaction, with the plant providing a sugar resource to the ants in return for protection against herbivory since they are present in developing leaves. Key words: Cashew, extrafloral nectary, glandular trichomes, histochemistry, nectar. ResumoSupostas domácias foliares de Anacardium humile (Anacardiaceae) são na realidade nectários extrafloraisAnacardium humile, uma espécie do cerrado brasileiro, está associada a formigas forrageadoras, o que leva à descrição da estrutura presente em suas folhas como domácias. No entanto, as formigas coletam a secreção das folhas, um fenômeno que inspirou este estudo, que visa justamente elucidar esta estrutura. Por esta razão, foi realizada uma análise da distribuição, micromorfologia, anatomia e histoquímica das supostas domácias. Elas estão localizadas nas axilas das nervuras foliares de maior calibre e são compostas por tricomas glandulares. Os tricomas exsudam glicose, portanto, são descritos aqui como nectários extraflorais (NEFs). Os tricomas nectaríferos estão localizados no mesmo nível que as células da epiderme em folhas jovens, enquanto, nas folhas maduras, foram encontradas nas depressões da lâmina foliar. A atividade secretora nos NEFs é limitada a fases juvenis, degenerando em folhas maduras. Carboidratos e substâncias lipofílicas foram detectados na secreção produzida. Pode-se concluir que a presença de formigas forrageando folhas para coleta nos NEFs indica uma interação mutualística, com a planta fornecendo recursos para as formigas em troca de proteção contra herbivoria, uma vez que as mesmas estão presentes em folhas ainda em desenvolvimento. Palavras-chave: Caju, nectário extrafloral, tricomas glandulares, histoquímica, néctar.

Most species of Anacardiaceae have drupes containing secretory structures.. Th e substances produced by these structures may have importance to industry and folk medicine, and may even cause allergenic eff ects. Th is work describes the ontogeny of pericarp of Tapirira guianensis with an emphasis on the secretory structures present at diff erent stages of development. Ovary and fruits in various stages of development were collected, fi xed and processed for studies using light and scanning electron microscopy according to conventional techniques. Histochemical tests were employed to identify the major metabolites present in the tissues. Th e fruit is a drupe formed by exocarp, mesocarp containing secretory ducts and idioblasts, and endocarp with some lignifi ed layers. Fruit growth occurs through the division and elongation of cells. Th e secretory ducts produce mainly phenols and lipids and are active during all stages of development. Th e secreted substances protect the fruit against pathogens and predators. In ripe fruits the cells of the mesocarp accumulate starch. Th is study is the fi rst report of the presence of a secretory endocarp in young fruits of a species of Anacardiaceae. Th e substances produced by the endocarp in early developmental stages may play an important role in seed dispersal and germination.