Cariniana legalis is an emergent tree that reaches the upper canopy in Brazilian Semideciduous Forest. Spatial contrasts in microclimatic conditions between the upper canopy and understorey in a forest may affect morphophysiological leaf traits. In order to test the hypothesis that the upper canopy is more stressful to leaves than a gap environment we compared emergent trees of C. legalis, 28-29 m in height to gap saplings, 6-9 m in height, for the following parameters: leaf area, leaf mass area (LMA the dry weight:leaf area ratio), leaf thickness, leaf anatomical parameters, stomata conductance, and chlorophyll a fluorescence. Leaves from emergent trees had smaller leaf areas but greater LMA compared to saplings. Leaf thickness, palisade layer thickness, and stomatal density were higher for emergent trees than for saplings. The opposite pattern was observed for spongy layer thickness and spongy/palisade ratio. Stomatal conductance was also higher for emergent tree leaves than for sapling leaves, but the magnitude of depression on stomatal conductance near midday was more pronounced in emergent trees. The potential quantum yield of photosystem II, as determined by the F v /F m ratio was lower for leaves from saplings. The lower values of stomatal conductance, indicating restriction in CO 2 diffusion into the mesophyll can be related to higher photoinhibition observed in the saplings. Leaves from emergent trees and saplings exhibited similar values for apparent electron transport rates and non-photochemical quenching. Our results suggest that changes in leaf traits could be associated to dry conditions at the upper canopy as well as to the ontogenetic transition between sapling/emergent tree life stages.

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Colleters are secretory structures located in reproductive and (or) vegetative organs of many eudicots. In Gentianaceae Juss., the presence of foliar colleters has been neglected, and anatomical and histochemical studies are scarce. The objectives of this study were to investigate the anatomy, ontogeny, and chemical nature of the secretion found in Macrocarpaea obtusifolia (Griseb.) Gilg colleters to establish a relationship between their structure and function and check whether these structures are similar to those described for other genera of the Gentianaceae and other families of the Gentianales. Samples of leaves at different developmental stages were collected and processed for anatomical and histochemical analysis using light microscopy and scanning electron microscopy. Colleters in M. obtusifolia have a protodermal origin, are of standard type, and are not vascularized. Young colleters are translucent and produce an abundant amount of sticky secretion. Later, they turn yellowish with a blackened region at the apex of the head, and the secretion, composed of polysaccharides and proteins, becomes less abundant and brownish. During senescence, the process begins with complete degradation and cell collapse of the secretory portion. The colleters of the standard type in M. obtusifolia have been observed for the first time in the Gentianaceae and represent additional evidence that reinforces how common this type of colleter is in the Gentianales. Such results provide new information on the anatomy, ontogeny, histochemistry, and colleter types of Gentianaceae.Key words: micromorphology, mucilage, proteins, secretory structures. Résumé :Les collerettes constituent des structures sécrétrices localisées dans les organes reproducteurs ou végétatifs de plusieurs eudicotylées. Chez les Gentianaceae, on a négligé la présence de collerettes foliaires; en effet, rares sont les études anatomiques et histochimiques. L'objectif des auteurs était d'examiner l'anatomie, l'ontogénie, et la nature chimique de la sécrétion se retrouvant dans les collerettes du Macrocarpaea obtusifolia (Griseb.) Gilg, afin d'établir la relation entre leur structure et leur fonction et de vérifier si ces structures sont semblables à celles décrites chez d'autres genres de Gentianaceae et d'autres familles des Gentianales. Ils ont récolté des échantillons de feuilles à divers stades de développement et effectué des analyses anatomiques et histochimiques à l'aide de la microscopie photonique et à électronique par balayage. Chez le M. obtusifolia, les collerettes ont une origine protodermique, sont de type standard et non vascularisées. Les jeunes collerettes translucides produisent une bonne quantité de sécrétion collante. Plus tard, elles deviennent jaunes avec une région à col noir à l'apex de la tête et la sécrétion, composée de polysaccharides et de protéines, devient moins abondante et brunit. Pendant la sénescence, le processus débute avec une dégradation complète avec un affaissement des cellules de la portion sécrétrice. On a obse...

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Chamaecrista (L.) Moench (Caesalpinioideae-Leguminosae) with 330 species is organized into six sections: Apoucouita, Absus, Grimaldia, Chamaecrista, Caliciopsis and Xerocalyx. Section Absus is the largest section of the Chamaecrista and is organized into four subsections, viz., subsect. Adenophyllum, subsect. Baseophyllum, subsect. Otophyllum and subsect. Absus. This section is not monophyletic and has a complex taxonomy. This study aims to anatomically characterize 60 taxa of Chamaecrista, identifying meaningful morphoanatomical characters that may shed light on the evaluations of the taxonomic and phylogenetic framework of Chamaecrista, especially C. sect. Absus. Standard light microscopy techniques were used to anatomically characterize the leaves. The anatomical data were subjected to a multivariate analysis (Jaccard index). Epidermal papillae on the abaxial side, the distribution and types of secretory and tector trichomes, variations in the arrangement of the vascular system of the midvein and the type of arrangement of the vascular system of the petiole are useful for separating species or groups of species. The presence and type of secretory structure, the type and position of stomata and the venation pattern are important in establishing the affinities between sections and subsections. The phenetic analysis demonstrates that the anatomical data contribute to the establishment of affinities between sections and subsections, supporting the elevation of the taxonomic status of the clade Baseophyllum to section and the insertion of C. absus (C. sect. Grimaldia) into C. sect. Absus, corroborating molecular studies.

This is the first comprehensive study of EFNs on the leaves of neotropical Gentianaceae. The data suggested that NEFs evolved from isolated units for NEFs in aggregates. The results represent a new source of data for future ecological, systematic, and phylogenetic studies in Gentianaceae.

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