ABSTRACT Colleters produce a secretion composed of hydrophilic and/or lipophilic substances which lubricates and protects the shoot apical meristem against biotic and abiotic agents. Little attention has been given to these structures in Clusiaceae. In the present study, the structure and development of the leaf colleters of Clusia criuva subsp. criuva were described and variations in the exudate composition of the colleters at different stages of leaf development were identified. The samples were collected and processed according to techniques for light and scanning electron microscopy. Colleters are of the standard type and not vascularized, and during leaf development, changes in color, structure, and secretion abundance were observed. Asynchrony in the development was noticeable in the leaf primordia and young leaves, from colleters in early formation to those in early senescence. In early phases there was an abundance of polysaccharide, lipid, and protein secretions, whereas adult and senescent leaves revealed an accumulation of phenolic compounds and cell degradation. The secretion was released by the rupture of the cuticle. The structural changes and secretion composition during leaf development emphasize the role of colleters in protecting meristems and developing organs.

RESUMO Embora Araliaceae possua muitas espécies contendo folhas com margens denteadas, a estrutura anatômica dessas projeções nunca foi investigada. Assim, este estudo teve como objetivo caracterizar a anatomia dos dentes foliares de Hydrocotyle asterias Cham. & Schltdl., representante desta família. Fragmentos do limbo foliar com dentes marginais foram processados conforme técnicas usuais para microscopia óptica (diafanização, cortes paradérmicos e testes histoquímicos) e microscopia eletrônica de varredura. Os dentes de H. asterias consistem em hidatódios, cujo tamanho, formato e espaço entre os dentes variam nos diferentes estágios de desenvolvimento da folha. Eles apresentam epiderme uniestratificada, composta por células isodiamétricas com paredes levemente espessadas, cutícula delgada e estômatos concentrados na região apical. A vascularização é composta por xilema que se projeta até o epitema. Este estudo apresenta as primeiras informações sobre a estrutura anatômica dos dentes foliares da família Araliaceae e amplia o conhecimento sobre os hidatódios localizados nos dentes foliares.

ABSTRACT Although Araliaceae has many species with toothed leaf margins, the anatomical structure of these projections hasnever been investigated. The objective of this study was to characterize the anatomy of the leaf teeth of Hydrocotyle asterias Cham. & Schltdl., a representative of this family. Fragments of the leaf teeth were processed according to the usual techniques for optical microscopy (diaphanization and paradermal cuts) and scanning electron microscopy. The leaf tooth of H. asterias consists of hydathodes whose size, shape, and space between teeth vary among the different stages of leaf development. They have unstratified epidermis composed of isodiametric cells with slightly thickened walls, thin cuticle, and stomata concentrated at the apical region. Vascularization is composed of xylem that projects to the epithem. This study presents the first data on the anatomical structure of the leaf teeth of the Araliaceae family and expands the knowledge about the hydathodes associated with leaf teeth.

ABSTRACT Extrafloral nectaries (EFNs) are specialized structures that produce and release nectar and are located on leaves, cotyledons and, more seldomly, stems. Peculiar leaf nectaries have been described for thirty-three Neotropical species of Gentianaceae, while stem nectaries have been reported for only nine. The aim of this study was to verify the occurrence of stem EFNs within Gentianaceae and investigate the existence of a correlation between their occurrence and the geographical distribution of species. Samples of internodal regions from field and herbarium specimens were submitted to standard light microscopy techniques. Data regarding the geographical distribution of species were acquired from herbarium specimens and the literature. A total of 37 species were investigated, representing 25 genera distributed among five tribes. Nectaries, composed of modified epidermal cells, were observed in 16 species restricted to the Neotropical tribes Helieae, Saccifolieae, Potalieae and Coutoubeinae; exceptions were Cicendia quadrangularis and Zygostigma australe, which both occur in the Neotropics but do not possess EFNs. These results demonstrate that stem EFNs are common among Neotropical taxa of Gentianaceae, and are typically absent from taxa in temperate regions.