Anatomia de órgãos vegetativos de Microlicia D. Don (Melastomataceae) ocorrentes em diferentes fitofisionomias campestre de Cerrado

Abstract

ABSTRACT. Venation pattems, descriptions of stomata types and distribution, trichome and emergence morphology, variations in the type of mesophyll and vascular bundles in the leaves, make up the evidence of the anatomical diversity of Microlicia. However, anatomical investigations of vegetative organs for this genus still remain a gap in knowledge given its floristic richness in the Cerrado. With the purpose of expanding knowledge of the anatomical diversity of Microlicia, we investigated the vegetative anatomy organs of M. canastrensis, M. cordata, M. inquinans, M. minensis and Microlicia sp nov, distributed in the Serra da Canastra National Park, Minas Gerais, Brazil. Samples of leaves, stem and roots of these species were collected and fixed, processed and analyzed according to usual light microscopy and scanning electron microscopy protocols. The results confirm the anatomical variation existing in the leaf indumentum, while shows the existence of similar patterns of mesophyll types and vascular bundles. In the stem, the five species analyzed have uniseriate epidermis, a cortex consisting of parenchyma, and endodermis with conspicuous caspary strips, and in the stele the phloem parenchyma gives rise to the phellogen, and consequently, the polyderm in this organ. Vascular tissues have similar characteristics, highlighting distinct patterns of distribution of libriform and gelatinous fibers. In the roots there are differences in the composition of the polyderm, which is aerenchymatous in M. minensis roots, and the xylem and secondary phloem for the five species described have similar anatomical patterns. We present correlations between the anatomical structure, and the probable biotic and abiotic conditions to which the described individuals are subjected in Cerrado.