Glandonia is a rare genus comprising three species confined to Amazonian rainforest. Glandonia macrocarpa has been documented in some localities of the lower Rio Negro, in the municipality of Manaus, Brazil. Glandonia prancei is represented by only a few herbarium specimens, which were collected along the Madeira and Purus rivers in the 1960s and 70s. A recent record of G. prancei was discovered while analyzing collections of G. macrocarpa, providing a new locality where we found and collected G. prancei. Glandonia williamsii, which had not been recorded in Brazil for the past three decades, was collected in the upper Rio Negro in this study. This work reexamines the taxonomy of the genus, based on fieldwork and herbarium specimens, and includes notes on morpho-anatomy, distribution and phenology. New morpho-anatomical characters are provided to better describe the species (e.g., outline of epidermal cell walls of the leaf, arrangement of petiolar vascular system, bracteole gland surface, and distribution of glands on the leaf blade and petals).
A taxonomic revision of Mcvaughia is presented, including the description of a new species from the state of Piauí, Brazil, and notes on wood, secondary phloem, leaf, and floral morpho-anatomy. We present a key to the species, full morphological descriptions, a distribution map, and notes on distribution, ecology, etymology, and conservation status for each species.
Colleters are secretory structures that play a role in protecting meristems from dehydration. Little attention has been given to the effect of seasonal variation on colleter exudates. Therefore, this study aimed to characterise the main chemical groups found in colleter exudates as well as to correlate the chemical nature of the secretion with seasonal variation. We used Myrcia splendens as a model to understand seasonal variation in colleter exudates. For that, meristems and shoot apices of M. splendens were collected and subjected to standard anatomical techniques. In M. splendens, colleters arise from protodermal cells and are similar to trichomes. Mature colleters are conic and composed of a short stalk and a long secretory head. Histochemical analyses found that colleter exudates differed according to the seasonality. Composition of the secretions was more diverse in the dry season than in the wet season. During the dry season, colleters secreted five different compounds (i.e. total polysaccharides, mucilage–pectins, total proteins, total lipids and phenolic compounds), whereas in the wet season, only three compounds were found (i.e. total proteins, total lipids and phenolic compounds). Our study extends what was known in earlier works, demonstrating changes in colleter exudates due to environmental seasonality.
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