An approach on anatomical structure of Chaetostoma glaziovii Cogn – Melastomataceae – and its successful establishment at high-altitude fields

Resumo

Chaetostoma glaziovii Cogn. is an endemic species of the Brazilian flora and grows exclusively in fields at elevations above 2000 meters. It belongs to Melastomataceae family, Microlicieae tribe, which presents little variation on vegetative organs, making it difficult to identify sterile individuals. Anatomical studies, using optical and scanning electron microscopes are carried on comparing the data with the anatomical characteristics of xeromorphic plants, cited in the literature, to check its similarities. This study aims, also, highlight data that may contribute to characterization of the species due to the great similarities among sterile individuals within the tribe. Leaf and stem anatomical data of C. glaziovii are interpreted considering climatic factors, aiming to understand the species’ successful establishment in an environment characterized by intense light exposure, strong winds and extreme temperatures. It is noteworthy the great amount of fibers on the abaxial and marginal regions of leaf blade, forming an armor against environmental aggressions. In addition, this characteristic is valued from the taxonomic perspective because no other species of the tribe exhibits such extensive fiber development. The material was collected in the Itatiaia National Park at an altitude of 2350 meters, latitude S 22° 23' 26'' and longitude W 44º 40' 17''. Histochemical tests were performed on unfixed samples to identify starch grains, lipids, phenolic compounds, glycides and crystals. The anatomical data revealed that some characteristics of C. glaziovii are like those found on xeromorphic plants and are important for its identification beyond to contribute for understanding the intricate plant-environment relationships.